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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 the same as the format generated by <tt>date
1624 </footnote> (compatible and with the same semantics of
1625 RFC 2822 and RFC 5322):
1626 <example>day-of-week, dd month yyyy hh:mm:ss +zzzz</example>
1628 <list compact="compact">
1630 day-of week is one of: Mon, Tue, Wed, Thu, Fri, Sat, Sun
1633 dd is a one- or two-digit day of the month (01-31)
1636 month is one of: Jan, Feb, Mar, Apr, May, Jun, Jul, Aug,
1639 <item>yyyy is the four-digit year (e.g. 2010)</item>
1640 <item>hh is the two-digit hour (00-23)</item>
1641 <item>mm is the two-digit minutes (00-59)</item>
1642 <item>ss is the two-digit seconds (00-60)</item>
1644 +zzzz or -zzzz is the the time zone offset from Coordinated
1645 Universal Time (UTC). "+" indicates that the time is ahead
1646 of (i.e., east of) UTC and "-" indicates that the time is
1647 behind (i.e., west of) UTC. The first two digits indicate
1648 the hour difference from UTC and the last two digits
1649 indicate the number of additional minutes difference from
1650 UTC. The last two digits must be in the range 00-59.
1656 The first "title" line with the package name must start
1657 at the left hand margin. The "trailer" line with the
1658 maintainer and date details must be preceded by exactly
1659 one space. The maintainer details and the date must be
1660 separated by exactly two spaces.
1664 The entire changelog must be encoded in UTF-8.
1668 For more information on placement of the changelog files
1669 within binary packages, please see <ref id="changelogs">.
1673 <sect id="dpkgcopyright">
1674 <heading>Copyright: <file>debian/copyright</file></heading>
1676 Every package must be accompanied by a verbatim copy of its
1677 copyright information and distribution license in the file
1678 <file>/usr/share/doc/<var>package</var>/copyright</file>
1679 (see <ref id="copyrightfile"> for further details). Also see
1680 <ref id="pkgcopyright"> for further considerations related
1681 to copyrights for packages.
1685 <heading>Error trapping in makefiles</heading>
1688 When <prgn>make</prgn> invokes a command in a makefile
1689 (including your package's upstream makefiles and
1690 <file>debian/rules</file>), it does so using <prgn>sh</prgn>. This
1691 means that <prgn>sh</prgn>'s usual bad error handling
1692 properties apply: if you include a miniature script as one
1693 of the commands in your makefile you'll find that if you
1694 don't do anything about it then errors are not detected
1695 and <prgn>make</prgn> will blithely continue after
1700 Every time you put more than one shell command (this
1701 includes using a loop) in a makefile command you
1702 must make sure that errors are trapped. For
1703 simple compound commands, such as changing directory and
1704 then running a program, using <tt>&&</tt> rather
1705 than semicolon as a command separator is sufficient. For
1706 more complex commands including most loops and
1707 conditionals you should include a separate <tt>set -e</tt>
1708 command at the start of every makefile command that's
1709 actually one of these miniature shell scripts.
1713 <sect id="timestamps">
1714 <heading>Time Stamps</heading>
1716 Maintainers should preserve the modification times of the
1717 upstream source files in a package, as far as is reasonably
1719 The rationale is that there is some information conveyed
1720 by knowing the age of the file, for example, you could
1721 recognize that some documentation is very old by looking
1722 at the modification time, so it would be nice if the
1723 modification time of the upstream source would be
1729 <sect id="restrictions">
1730 <heading>Restrictions on objects in source packages</heading>
1733 The source package may not contain any hard links<footnote>
1735 This is not currently detected when building source
1736 packages, but only when extracting
1740 Hard links may be permitted at some point in the
1741 future, but would require a fair amount of
1744 </footnote>, device special files, sockets or setuid or
1745 setgid files.<footnote>
1746 Setgid directories are allowed.
1751 <sect id="debianrules">
1752 <heading>Main building script: <file>debian/rules</file></heading>
1755 This file must be an executable makefile, and contains the
1756 package-specific recipes for compiling the package and
1757 building binary package(s) from the source.
1761 It must start with the line <tt>#!/usr/bin/make -f</tt>,
1762 so that it can be invoked by saying its name rather than
1763 invoking <prgn>make</prgn> explicitly. That is, invoking
1764 either of <tt>make -f debian/rules <em>args...</em></tt>
1765 or <tt>./debian/rules <em>args...</em></tt> must result in
1770 Since an interactive <file>debian/rules</file> script makes it
1771 impossible to auto-compile that package and also makes it
1772 hard for other people to reproduce the same binary
1773 package, all <em>required targets</em> must be
1774 non-interactive. At a minimum, required targets are the
1775 ones called by <prgn>dpkg-buildpackage</prgn>, namely,
1776 <em>clean</em>, <em>binary</em>, <em>binary-arch</em>,
1777 <em>binary-indep</em>, and <em>build</em>. It also follows
1778 that any target that these targets depend on must also be
1783 The targets are as follows (required unless stated otherwise):
1785 <tag><tt>build</tt></tag>
1788 The <tt>build</tt> target should perform all the
1789 configuration and compilation of the package.
1790 If a package has an interactive pre-build
1791 configuration routine, the Debianized source package
1792 must either be built after this has taken place (so
1793 that the binary package can be built without rerunning
1794 the configuration) or the configuration routine
1795 modified to become non-interactive. (The latter is
1796 preferable if there are architecture-specific features
1797 detected by the configuration routine.)
1801 For some packages, notably ones where the same
1802 source tree is compiled in different ways to produce
1803 two binary packages, the <tt>build</tt> target
1804 does not make much sense. For these packages it is
1805 good enough to provide two (or more) targets
1806 (<tt>build-a</tt> and <tt>build-b</tt> or whatever)
1807 for each of the ways of building the package, and a
1808 <tt>build</tt> target that does nothing. The
1809 <tt>binary</tt> target will have to build the
1810 package in each of the possible ways and make the
1811 binary package out of each.
1815 The <tt>build</tt> target must not do anything
1816 that might require root privilege.
1820 The <tt>build</tt> target may need to run the
1821 <tt>clean</tt> target first - see below.
1825 When a package has a configuration and build routine
1826 which takes a long time, or when the makefiles are
1827 poorly designed, or when <tt>build</tt> needs to
1828 run <tt>clean</tt> first, it is a good idea to
1829 <tt>touch build</tt> when the build process is
1830 complete. This will ensure that if <tt>debian/rules
1831 build</tt> is run again it will not rebuild the whole
1833 Another common way to do this is for <tt>build</tt>
1834 to depend on <prgn>build-stamp</prgn> and to do
1835 nothing else, and for the <prgn>build-stamp</prgn>
1836 target to do the building and to <tt>touch
1837 build-stamp</tt> on completion. This is
1838 especially useful if the build routine creates a
1839 file or directory called <tt>build</tt>; in such a
1840 case, <tt>build</tt> will need to be listed as
1841 a phony target (i.e., as a dependency of the
1842 <tt>.PHONY</tt> target). See the documentation of
1843 <prgn>make</prgn> for more information on phony
1849 <tag><tt>build-arch</tt> (optional),
1850 <tt>build-indep</tt> (optional)
1854 A package may also provide both of the targets
1855 <tt>build-arch</tt> and <tt>build-indep</tt>.
1856 The <tt>build-arch</tt> target, if provided, should
1857 perform all the configuration and compilation required
1858 for producing all architecture-dependant binary packages
1859 (those packages for which the body of the
1860 <tt>Architecture</tt> field in <tt>debian/control</tt>
1861 is not <tt>all</tt>).
1862 Similarly, the <tt>build-indep</tt> target, if
1863 provided, should perform all the configuration and
1864 compilation required for producing all
1865 architecture-independent binary packages
1866 (those packages for which the body of the
1867 <tt>Architecture</tt> field in <tt>debian/control</tt>
1869 The <tt>build</tt> target should depend on those of the
1870 targets <tt>build-arch</tt> and <tt>build-indep</tt> that
1871 are provided in the rules file.
1875 If one or both of the targets <tt>build-arch</tt> and
1876 <tt>build-indep</tt> are not provided, then invoking
1877 <file>debian/rules</file> with one of the not-provided
1878 targets as arguments should produce a exit status code
1879 of 2. Usually this is provided automatically by make
1880 if the target is missing.
1884 The <tt>build-arch</tt> and <tt>build-indep</tt> targets
1885 must not do anything that might require root privilege.
1889 <tag><tt>binary</tt>, <tt>binary-arch</tt>,
1890 <tt>binary-indep</tt>
1894 The <tt>binary</tt> target must be all that is
1895 necessary for the user to build the binary package(s)
1896 produced from this source package. It is
1897 split into two parts: <prgn>binary-arch</prgn> builds
1898 the binary packages which are specific to a particular
1899 architecture, and <tt>binary-indep</tt> builds
1900 those which are not.
1903 <tt>binary</tt> may be (and commonly is) a target with
1904 no commands which simply depends on
1905 <tt>binary-arch</tt> and <tt>binary-indep</tt>.
1908 Both <tt>binary-*</tt> targets should depend on the
1909 <tt>build</tt> target, or on the appropriate
1910 <tt>build-arch</tt> or <tt>build-indep</tt> target, if
1911 provided, so that the package is built if it has not
1912 been already. It should then create the relevant
1913 binary package(s), using <prgn>dpkg-gencontrol</prgn> to
1914 make their control files and <prgn>dpkg-deb</prgn> to
1915 build them and place them in the parent of the top
1920 Both the <tt>binary-arch</tt> and
1921 <tt>binary-indep</tt> targets <em>must</em> exist.
1922 If one of them has nothing to do (which will always be
1923 the case if the source generates only a single binary
1924 package, whether architecture-dependent or not), it
1925 must still exist and must always succeed.
1929 The <tt>binary</tt> targets must be invoked as
1931 The <prgn>fakeroot</prgn> package often allows one
1932 to build a package correctly even without being
1938 <tag><tt>clean</tt></tag>
1941 This must undo any effects that the <tt>build</tt>
1942 and <tt>binary</tt> targets may have had, except
1943 that it should leave alone any output files created in
1944 the parent directory by a run of a <tt>binary</tt>
1949 If a <tt>build</tt> file is touched at the end of
1950 the <tt>build</tt> target, as suggested above, it
1951 should be removed as the first action that
1952 <tt>clean</tt> performs, so that running
1953 <tt>build</tt> again after an interrupted
1954 <tt>clean</tt> doesn't think that everything is
1959 The <tt>clean</tt> target may need to be
1960 invoked as root if <tt>binary</tt> has been
1961 invoked since the last <tt>clean</tt>, or if
1962 <tt>build</tt> has been invoked as root (since
1963 <tt>build</tt> may create directories, for
1968 <tag><tt>get-orig-source</tt> (optional)</tag>
1971 This target fetches the most recent version of the
1972 original source package from a canonical archive site
1973 (via FTP or WWW, for example), does any necessary
1974 rearrangement to turn it into the original source
1975 tar file format described below, and leaves it in the
1980 This target may be invoked in any directory, and
1981 should take care to clean up any temporary files it
1986 This target is optional, but providing it if
1987 possible is a good idea.
1991 <tag><tt>patch</tt> (optional)</tag>
1994 This target performs whatever additional actions are
1995 required to make the source ready for editing (unpacking
1996 additional upstream archives, applying patches, etc.).
1997 It is recommended to be implemented for any package where
1998 <tt>dpkg-source -x</tt> does not result in source ready
1999 for additional modification. See
2000 <ref id="readmesource">.
2006 The <tt>build</tt>, <tt>binary</tt> and
2007 <tt>clean</tt> targets must be invoked with the current
2008 directory being the package's top-level directory.
2013 Additional targets may exist in <file>debian/rules</file>,
2014 either as published or undocumented interfaces or for the
2015 package's internal use.
2019 The architectures we build on and build for are determined
2020 by <prgn>make</prgn> variables using the utility
2021 <qref id="pkg-dpkg-architecture"><prgn>dpkg-architecture</prgn></qref>.
2022 You can determine the
2023 Debian architecture and the GNU style architecture
2024 specification string for the build machine (the machine type
2025 we are building on) as well as for the host machine (the
2026 machine type we are building for). Here is a list of
2027 supported <prgn>make</prgn> variables:
2028 <list compact="compact">
2030 <tt>DEB_*_ARCH</tt> (the Debian architecture)
2033 <tt>DEB_*_ARCH_CPU</tt> (the Debian CPU name)
2036 <tt>DEB_*_ARCH_OS</tt> (the Debian System name)
2039 <tt>DEB_*_GNU_TYPE</tt> (the GNU style architecture
2040 specification string)
2043 <tt>DEB_*_GNU_CPU</tt> (the CPU part of
2044 <tt>DEB_*_GNU_TYPE</tt>)
2047 <tt>DEB_*_GNU_SYSTEM</tt> (the System part of
2048 <tt>DEB_*_GNU_TYPE</tt>)
2050 where <tt>*</tt> is either <tt>BUILD</tt> for specification of
2051 the build machine or <tt>HOST</tt> for specification of the
2056 Backward compatibility can be provided in the rules file
2057 by setting the needed variables to suitable default
2058 values; please refer to the documentation of
2059 <prgn>dpkg-architecture</prgn> for details.
2063 It is important to understand that the <tt>DEB_*_ARCH</tt>
2064 string only determines which Debian architecture we are
2065 building on or for. It should not be used to get the CPU
2066 or system information; the <tt>DEB_*_ARCH_CPU</tt> and
2067 <tt>DEB_*_ARCH_OS</tt> variables should be used for that.
2068 GNU style variables should generally only be used with upstream
2072 <sect1 id="debianrules-options">
2073 <heading><file>debian/rules</file> and
2074 <tt>DEB_BUILD_OPTIONS</tt></heading>
2077 Supporting the standardized environment variable
2078 <tt>DEB_BUILD_OPTIONS</tt> is recommended. This variable can
2079 contain several flags to change how a package is compiled and
2080 built. Each flag must be in the form <var>flag</var> or
2081 <var>flag</var>=<var>options</var>. If multiple flags are
2082 given, they must be separated by whitespace.<footnote>
2083 Some packages support any delimiter, but whitespace is the
2084 easiest to parse inside a makefile and avoids ambiguity with
2085 flag values that contain commas.
2087 <var>flag</var> must start with a lowercase letter
2088 (<tt>a-z</tt>) and consist only of lowercase letters,
2089 numbers (<tt>0-9</tt>), and the characters
2090 <tt>-</tt> and <tt>_</tt> (hyphen and underscore).
2091 <var>options</var> must not contain whitespace. The same
2092 tag should not be given multiple times with conflicting
2093 values. Package maintainers may assume that
2094 <tt>DEB_BUILD_OPTIONS</tt> will not contain conflicting tags.
2098 The meaning of the following tags has been standardized:
2102 This tag says to not run any build-time test suite
2103 provided by the package.
2107 The presence of this tag means that the package should
2108 be compiled with a minimum of optimization. For C
2109 programs, it is best to add <tt>-O0</tt> to
2110 <tt>CFLAGS</tt> (although this is usually the default).
2111 Some programs might fail to build or run at this level
2112 of optimization; it may be necessary to use
2113 <tt>-O1</tt>, for example.
2117 This tag means that the debugging symbols should not be
2118 stripped from the binary during installation, so that
2119 debugging information may be included in the package.
2121 <tag>parallel=n</tag>
2123 This tag means that the package should be built using up
2124 to <tt>n</tt> parallel processes if the package build
2125 system supports this.<footnote>
2126 Packages built with <tt>make</tt> can often implement
2127 this by passing the <tt>-j</tt><var>n</var> option to
2130 If the package build system does not support parallel
2131 builds, this string must be ignored. If the package
2132 build system only supports a lower level of concurrency
2133 than <var>n</var>, the package should be built using as
2134 many parallel processes as the package build system
2135 supports. It is up to the package maintainer to decide
2136 whether the package build times are long enough and the
2137 package build system is robust enough to make supporting
2138 parallel builds worthwhile.
2144 Unknown flags must be ignored by <file>debian/rules</file>.
2148 The following makefile snippet is an example of how one may
2149 implement the build options; you will probably have to
2150 massage this example in order to make it work for your
2152 <example compact="compact">
2155 INSTALL_FILE = $(INSTALL) -p -o root -g root -m 644
2156 INSTALL_PROGRAM = $(INSTALL) -p -o root -g root -m 755
2157 INSTALL_SCRIPT = $(INSTALL) -p -o root -g root -m 755
2158 INSTALL_DIR = $(INSTALL) -p -d -o root -g root -m 755
2160 ifneq (,$(filter noopt,$(DEB_BUILD_OPTIONS)))
2165 ifeq (,$(filter nostrip,$(DEB_BUILD_OPTIONS)))
2166 INSTALL_PROGRAM += -s
2168 ifneq (,$(filter parallel=%,$(DEB_BUILD_OPTIONS)))
2169 NUMJOBS = $(patsubst parallel=%,%,$(filter parallel=%,$(DEB_BUILD_OPTIONS)))
2170 MAKEFLAGS += -j$(NUMJOBS)
2175 ifeq (,$(filter nocheck,$(DEB_BUILD_OPTIONS)))
2176 # Code to run the package test suite.
2183 <!-- FIXME: section pkg-srcsubstvars is the same as substvars -->
2184 <sect id="substvars">
2185 <heading>Variable substitutions: <file>debian/substvars</file></heading>
2188 When <prgn>dpkg-gencontrol</prgn>,
2189 <prgn>dpkg-genchanges</prgn> and <prgn>dpkg-source</prgn>
2190 generate control files they perform variable substitutions
2191 on their output just before writing it. Variable
2192 substitutions have the form <tt>${<var>variable</var>}</tt>.
2193 The optional file <file>debian/substvars</file> contains
2194 variable substitutions to be used; variables can also be set
2195 directly from <file>debian/rules</file> using the <tt>-V</tt>
2196 option to the source packaging commands, and certain
2197 predefined variables are also available.
2201 The <file>debian/substvars</file> file is usually generated and
2202 modified dynamically by <file>debian/rules</file> targets, in
2203 which case it must be removed by the <tt>clean</tt> target.
2207 See <manref name="deb-substvars" section="5"> for full
2208 details about source variable substitutions, including the
2209 format of <file>debian/substvars</file>.</p>
2212 <sect id="debianwatch">
2213 <heading>Optional upstream source location: <file>debian/watch</file></heading>
2216 This is an optional, recommended control file for the
2217 <tt>uscan</tt> utility which defines how to automatically
2218 scan ftp or http sites for newly available updates of the
2219 package. This is used by <url id="
2220 http://dehs.alioth.debian.org/"> and other Debian QA tools
2221 to help with quality control and maintenance of the
2222 distribution as a whole.
2227 <sect id="debianfiles">
2228 <heading>Generated files list: <file>debian/files</file></heading>
2231 This file is not a permanent part of the source tree; it
2232 is used while building packages to record which files are
2233 being generated. <prgn>dpkg-genchanges</prgn> uses it
2234 when it generates a <file>.changes</file> file.
2238 It should not exist in a shipped source package, and so it
2239 (and any backup files or temporary files such as
2240 <file>files.new</file><footnote>
2241 <file>files.new</file> is used as a temporary file by
2242 <prgn>dpkg-gencontrol</prgn> and
2243 <prgn>dpkg-distaddfile</prgn> - they write a new
2244 version of <tt>files</tt> here before renaming it,
2245 to avoid leaving a corrupted copy if an error
2247 </footnote>) should be removed by the
2248 <tt>clean</tt> target. It may also be wise to
2249 ensure a fresh start by emptying or removing it at the
2250 start of the <tt>binary</tt> target.
2254 When <prgn>dpkg-gencontrol</prgn> is run for a binary
2255 package, it adds an entry to <file>debian/files</file> for the
2256 <file>.deb</file> file that will be created when <tt>dpkg-deb
2257 --build</tt> is run for that binary package. So for most
2258 packages all that needs to be done with this file is to
2259 delete it in the <tt>clean</tt> target.
2263 If a package upload includes files besides the source
2264 package and any binary packages whose control files were
2265 made with <prgn>dpkg-gencontrol</prgn> then they should be
2266 placed in the parent of the package's top-level directory
2267 and <prgn>dpkg-distaddfile</prgn> should be called to add
2268 the file to the list in <file>debian/files</file>.</p>
2271 <sect id="embeddedfiles">
2272 <heading>Convenience copies of code</heading>
2275 Some software packages include in their distribution convenience
2276 copies of code from other software packages, generally so that
2277 users compiling from source don't have to download multiple
2278 packages. Debian packages should not make use of these
2279 convenience copies unless the included package is explicitly
2280 intended to be used in this way.<footnote>
2281 For example, parts of the GNU build system work like this.
2283 If the included code is already in the Debian archive in the
2284 form of a library, the Debian packaging should ensure that
2285 binary packages reference the libraries already in Debian and
2286 the convenience copy is not used. If the included code is not
2287 already in Debian, it should be packaged separately as a
2288 prerequisite if possible.
2290 Having multiple copies of the same code in Debian is
2291 inefficient, often creates either static linking or shared
2292 library conflicts, and, most importantly, increases the
2293 difficulty of handling security vulnerabilities in the
2299 <sect id="readmesource">
2300 <heading>Source package handling:
2301 <file>debian/README.source</file></heading>
2304 If running <prgn>dpkg-source -x</prgn> on a source package
2305 doesn't produce the source of the package, ready for editing,
2306 and allow one to make changes and run
2307 <prgn>dpkg-buildpackage</prgn> to produce a modified package
2308 without taking any additional steps, creating a
2309 <file>debian/README.source</file> documentation file is
2310 recommended. This file should explain how to do all of the
2313 <item>Generate the fully patched source, in a form ready for
2314 editing, that would be built to create Debian
2315 packages. Doing this with a <tt>patch</tt> target in
2316 <file>debian/rules</file> is recommended; see
2317 <ref id="debianrules">.</item>
2318 <item>Modify the source and save those modifications so that
2319 they will be applied when building the package.</item>
2320 <item>Remove source modifications that are currently being
2321 applied when building the package.</item>
2322 <item>Optionally, document what steps are necessary to
2323 upgrade the Debian source package to a new upstream version,
2324 if applicable.</item>
2326 This explanation should include specific commands and mention
2327 any additional required Debian packages. It should not assume
2328 familiarity with any specific Debian packaging system or patch
2333 This explanation may refer to a documentation file installed by
2334 one of the package's build dependencies provided that the
2335 referenced documentation clearly explains these tasks and is not
2336 a general reference manual.
2340 <file>debian/README.source</file> may also include any other
2341 information that would be helpful to someone modifying the
2342 source package. Even if the package doesn't fit the above
2343 description, maintainers are encouraged to document in a
2344 <file>debian/README.source</file> file any source package with a
2345 particularly complex or unintuitive source layout or build
2346 system (for example, a package that builds the same source
2347 multiple times to generate different binary packages).
2353 <chapt id="controlfields">
2354 <heading>Control files and their fields</heading>
2357 The package management system manipulates data represented in
2358 a common format, known as <em>control data</em>, stored in
2359 <em>control files</em>.
2360 Control files are used for source packages, binary packages and
2361 the <file>.changes</file> files which control the installation
2362 of uploaded files<footnote>
2363 <prgn>dpkg</prgn>'s internal databases are in a similar
2368 <sect id="controlsyntax">
2369 <heading>Syntax of control files</heading>
2372 A control file consists of one or more paragraphs of
2374 The paragraphs are also sometimes referred to as stanzas.
2376 The paragraphs are separated by blank lines. Some control
2377 files allow only one paragraph; others allow several, in
2378 which case each paragraph usually refers to a different
2379 package. (For example, in source packages, the first
2380 paragraph refers to the source package, and later paragraphs
2381 refer to binary packages generated from the source.)
2385 Each paragraph consists of a series of data fields; each
2386 field consists of the field name, followed by a colon and
2387 then the data/value associated with that field. It ends at
2388 the end of the (logical) line. Horizontal whitespace
2389 (spaces and tabs) may occur immediately before or after the
2390 value and is ignored there; it is conventional to put a
2391 single space after the colon. For example, a field might
2393 <example compact="compact">
2396 the field name is <tt>Package</tt> and the field value
2401 Many fields' values may span several lines; in this case
2402 each continuation line must start with a space or a tab.
2403 Any trailing spaces or tabs at the end of individual
2404 lines of a field value are ignored.
2408 In fields where it is specified that lines may not wrap,
2409 only a single line of data is allowed and whitespace is not
2410 significant in a field body. Whitespace must not appear
2411 inside names (of packages, architectures, files or anything
2412 else) or version numbers, or between the characters of
2413 multi-character version relationships.
2417 Field names are not case-sensitive, but it is usual to
2418 capitalize the field names using mixed case as shown below.
2419 Field values are case-sensitive unless the description of the
2420 field says otherwise.
2424 Blank lines, or lines consisting only of spaces and tabs,
2425 are not allowed within field values or between fields - that
2426 would mean a new paragraph.
2430 All control files must be encoded in UTF-8.
2434 <sect id="sourcecontrolfiles">
2435 <heading>Source package control files -- <file>debian/control</file></heading>
2438 The <file>debian/control</file> file contains the most vital
2439 (and version-independent) information about the source package
2440 and about the binary packages it creates.
2444 The first paragraph of the control file contains information about
2445 the source package in general. The subsequent sets each describe a
2446 binary package that the source tree builds.
2450 The fields in the general paragraph (the first one, for the source
2453 <list compact="compact">
2454 <item><qref id="f-Source"><tt>Source</tt></qref> (mandatory)</item>
2455 <item><qref id="f-Maintainer"><tt>Maintainer</tt></qref> (mandatory)</item>
2456 <item><qref id="f-Uploaders"><tt>Uploaders</tt></qref></item>
2457 <item><qref id="f-Section"><tt>Section</tt></qref> (recommended)</item>
2458 <item><qref id="f-Priority"><tt>Priority</tt></qref> (recommended)</item>
2459 <item><qref id="sourcebinarydeps"><tt>Build-Depends</tt> et al</qref></item>
2460 <item><qref id="f-Standards-Version"><tt>Standards-Version</tt></qref> (recommended)</item>
2461 <item><qref id="f-Homepage"><tt>Homepage</tt></qref></item>
2466 The fields in the binary package paragraphs are:
2468 <list compact="compact">
2469 <item><qref id="f-Package"><tt>Package</tt></qref> (mandatory)</item>
2470 <item><qref id="f-Architecture"><tt>Architecture</tt></qref> (mandatory)</item>
2471 <item><qref id="f-Section"><tt>Section</tt></qref> (recommended)</item>
2472 <item><qref id="f-Priority"><tt>Priority</tt></qref> (recommended)</item>
2473 <item><qref id="f-Essential"><tt>Essential</tt></qref></item>
2474 <item><qref id="binarydeps"><tt>Depends</tt> et al</qref></item>
2475 <item><qref id="f-Description"><tt>Description</tt></qref> (mandatory)</item>
2476 <item><qref id="f-Homepage"><tt>Homepage</tt></qref></item>
2481 The syntax and semantics of the fields are described below.
2487 These fields are used by <prgn>dpkg-gencontrol</prgn> to
2488 generate control files for binary packages (see below), by
2489 <prgn>dpkg-genchanges</prgn> to generate the
2490 <tt>.changes</tt> file to accompany the upload, and by
2491 <prgn>dpkg-source</prgn> when it creates the
2492 <file>.dsc</file> source control file as part of a source
2493 archive. Many fields are permitted to span multiple lines in
2494 <file>debian/control</file> but not in any other control
2495 file. These tools are responsible for removing the line
2496 breaks from such fields when using fields from
2497 <file>debian/control</file> to generate other control files.
2501 The fields here may contain variable references - their
2502 values will be substituted by <prgn>dpkg-gencontrol</prgn>,
2503 <prgn>dpkg-genchanges</prgn> or <prgn>dpkg-source</prgn>
2504 when they generate output control files.
2505 See <ref id="substvars"> for details.
2509 In addition to the control file syntax described <qref
2510 id="controlsyntax">above</qref>, this file may also contain
2511 comment lines starting with <tt>#</tt> without any preceding
2512 whitespace. All such lines are ignored, even in the middle of
2513 continuation lines for a multiline field, and do not end a
2519 <sect id="binarycontrolfiles">
2520 <heading>Binary package control files -- <file>DEBIAN/control</file></heading>
2523 The <file>DEBIAN/control</file> file contains the most vital
2524 (and version-dependent) information about a binary package.
2528 The fields in this file are:
2530 <list compact="compact">
2531 <item><qref id="f-Package"><tt>Package</tt></qref> (mandatory)</item>
2532 <item><qref id="f-Source"><tt>Source</tt></qref></item>
2533 <item><qref id="f-Version"><tt>Version</tt></qref> (mandatory)</item>
2534 <item><qref id="f-Section"><tt>Section</tt></qref> (recommended)</item>
2535 <item><qref id="f-Priority"><tt>Priority</tt></qref> (recommended)</item>
2536 <item><qref id="f-Architecture"><tt>Architecture</tt></qref> (mandatory)</item>
2537 <item><qref id="f-Essential"><tt>Essential</tt></qref></item>
2538 <item><qref id="binarydeps"><tt>Depends</tt> et al</qref></item>
2539 <item><qref id="f-Installed-Size"><tt>Installed-Size</tt></qref></item>
2540 <item><qref id="f-Maintainer"><tt>Maintainer</tt></qref> (mandatory)</item>
2541 <item><qref id="f-Description"><tt>Description</tt></qref> (mandatory)</item>
2542 <item><qref id="f-Homepage"><tt>Homepage</tt></qref></item>
2547 <sect id="debiansourcecontrolfiles">
2548 <heading>Debian source control files -- <tt>.dsc</tt></heading>
2551 This file contains a series of fields, identified and
2552 separated just like the fields in the control file of
2553 a binary package. The fields are listed below; their
2554 syntax is described above, in <ref id="pkg-controlfields">.
2556 <list compact="compact">
2557 <item><qref id="f-Format"><tt>Format</tt></qref> (mandatory)</item>
2558 <item><qref id="f-Source"><tt>Source</tt></qref> (mandatory)</item>
2559 <item><qref id="f-Version"><tt>Version</tt></qref> (mandatory)</item>
2560 <item><qref id="f-Maintainer"><tt>Maintainer</tt></qref> (mandatory)</item>
2561 <item><qref id="f-Uploaders"><tt>Uploaders</tt></qref></item>
2562 <item><qref id="f-Binary"><tt>Binary</tt></qref></item>
2563 <item><qref id="f-Architecture"><tt>Architecture</tt></qref></item>
2564 <item><qref id="sourcebinarydeps"><tt>Build-Depends</tt> et al</qref></item>
2565 <item><qref id="f-Standards-Version"><tt>Standards-Version</tt></qref> (recommended)</item>
2566 <item><qref id="f-Files"><tt>Files</tt></qref> (mandatory)</item>
2567 <item><qref id="f-Homepage"><tt>Homepage</tt></qref></item>
2572 The source package control file is generated by
2573 <prgn>dpkg-source</prgn> when it builds the source
2574 archive, from other files in the source package,
2575 described above. When unpacking, it is checked against
2576 the files and directories in the other parts of the
2582 <sect id="debianchangesfiles">
2583 <heading>Debian changes files -- <file>.changes</file></heading>
2586 The .changes files are used by the Debian archive maintenance
2587 software to process updates to packages. They contain one
2588 paragraph which contains information from the
2589 <tt>debian/control</tt> file and other data about the
2590 source package gathered via <tt>debian/changelog</tt>
2591 and <tt>debian/rules</tt>.
2595 The fields in this file are:
2597 <list compact="compact">
2598 <item><qref id="f-Format"><tt>Format</tt></qref> (mandatory)</item>
2599 <item><qref id="f-Date"><tt>Date</tt></qref> (mandatory)</item>
2600 <item><qref id="f-Source"><tt>Source</tt></qref> (mandatory)</item>
2601 <item><qref id="f-Binary"><tt>Binary</tt></qref> (mandatory)</item>
2602 <item><qref id="f-Architecture"><tt>Architecture</tt></qref> (mandatory)</item>
2603 <item><qref id="f-Version"><tt>Version</tt></qref> (mandatory)</item>
2604 <item><qref id="f-Distribution"><tt>Distribution</tt></qref> (mandatory)</item>
2605 <item><qref id="f-Urgency"><tt>Urgency</tt></qref> (recommended)</item>
2606 <item><qref id="f-Maintainer"><tt>Maintainer</tt></qref> (mandatory)</item>
2607 <item><qref id="f-Changed-By"><tt>Changed-By</tt></qref></item>
2608 <item><qref id="f-Description"><tt>Description</tt></qref> (mandatory)</item>
2609 <item><qref id="f-Closes"><tt>Closes</tt></qref></item>
2610 <item><qref id="f-Changes"><tt>Changes</tt></qref> (mandatory)</item>
2611 <item><qref id="f-Files"><tt>Files</tt></qref> (mandatory)</item>
2616 <sect id="controlfieldslist">
2617 <heading>List of fields</heading>
2619 <sect1 id="f-Source">
2620 <heading><tt>Source</tt></heading>
2623 This field identifies the source package name.
2627 In <file>debian/control</file> or a <file>.dsc</file> file,
2628 this field must contain only the name of the source package.
2632 In a binary package control file or a <file>.changes</file>
2633 file, the source package name may be followed by a version
2634 number in parentheses<footnote>
2635 It is customary to leave a space after the package name
2636 if a version number is specified.
2638 This version number may be omitted (and is, by
2639 <prgn>dpkg-gencontrol</prgn>) if it has the same value as
2640 the <tt>Version</tt> field of the binary package in
2641 question. The field itself may be omitted from a binary
2642 package control file when the source package has the same
2643 name and version as the binary package.
2647 Package names (both source and binary,
2648 see <ref id="f-Package">) must consist only of lower case
2649 letters (<tt>a-z</tt>), digits (<tt>0-9</tt>), plus
2650 (<tt>+</tt>) and minus (<tt>-</tt>) signs, and periods
2651 (<tt>.</tt>). They must be at least two characters long and
2652 must start with an alphanumeric character.
2656 <sect1 id="f-Maintainer">
2657 <heading><tt>Maintainer</tt></heading>
2660 The package maintainer's name and email address. The name
2661 should come first, then the email address inside angle
2662 brackets <tt><></tt> (in RFC822 format).
2666 If the maintainer's name contains a full stop then the
2667 whole field will not work directly as an email address due
2668 to a misfeature in the syntax specified in RFC822; a
2669 program using this field as an address must check for this
2670 and correct the problem if necessary (for example by
2671 putting the name in round brackets and moving it to the
2672 end, and bringing the email address forward).
2676 <sect1 id="f-Uploaders">
2677 <heading><tt>Uploaders</tt></heading>
2680 List of the names and email addresses of co-maintainers of
2681 the package, if any. If the package has other maintainers
2682 beside the one named in the
2683 <qref id="f-Maintainer">Maintainer field</qref>, their
2684 names and email addresses should be listed here. The
2685 format is the same as that of the Maintainer tag, and
2686 multiple entries should be comma separated. Currently,
2687 this field is restricted to a single line of data. This
2688 is an optional field.
2691 Any parser that interprets the Uploaders field in
2692 <file>debian/control</file> must permit it to span multiple
2693 lines. Line breaks in an Uploaders field that spans multiple
2694 lines are not significant and the semantics of the field are
2695 the same as if the line breaks had not been present.
2699 <sect1 id="f-Changed-By">
2700 <heading><tt>Changed-By</tt></heading>
2703 The name and email address of the person who changed the
2704 said package. Usually the name of the maintainer.
2705 All the rules for the Maintainer field apply here, too.
2709 <sect1 id="f-Section">
2710 <heading><tt>Section</tt></heading>
2713 This field specifies an application area into which the package
2714 has been classified. See <ref id="subsections">.
2718 When it appears in the <file>debian/control</file> file,
2719 it gives the value for the subfield of the same name in
2720 the <tt>Files</tt> field of the <file>.changes</file> file.
2721 It also gives the default for the same field in the binary
2726 <sect1 id="f-Priority">
2727 <heading><tt>Priority</tt></heading>
2730 This field represents how important it is that the user
2731 have the package installed. See <ref id="priorities">.
2735 When it appears in the <file>debian/control</file> file,
2736 it gives the value for the subfield of the same name in
2737 the <tt>Files</tt> field of the <file>.changes</file> file.
2738 It also gives the default for the same field in the binary
2743 <sect1 id="f-Package">
2744 <heading><tt>Package</tt></heading>
2747 The name of the binary package.
2751 Binary package names must follow the same syntax and
2752 restrictions as source package names. See <ref id="f-Source">
2757 <sect1 id="f-Architecture">
2758 <heading><tt>Architecture</tt></heading>
2761 Depending on context and the control file used, the
2762 <tt>Architecture</tt> field can include the following sets of
2766 A unique single word identifying a Debian machine
2767 architecture as described in <ref id="arch-spec">.
2770 An architecture wildcard identifying a set of Debian
2771 machine architectures, see <ref id="arch-wildcard-spec">.
2772 <tt>any</tt> matches all Debian machine architectures
2773 and is the most frequently used.
2776 <tt>all</tt>, which indicates an
2777 architecture-independent package.
2780 <tt>source</tt>, which indicates a source package.
2786 In the main <file>debian/control</file> file in the source
2787 package, this field may contain the special
2788 value <tt>all</tt>, the special architecture
2789 wildcard <tt>any</tt>, or a list of specific and wildcard
2790 architectures separated by spaces. If <tt>all</tt>
2791 or <tt>any</tt> appears, that value must be the entire
2792 contents of the field. Most packages will use
2793 either <tt>all</tt> or <tt>any</tt>.
2797 Specifying a specific list of architectures indicates that the
2798 source will build an architecture-dependent package only on
2799 architectures included in the list. Specifying a list of
2800 architecture wildcards indicates that the source will build an
2801 architecture-dependent package on only those architectures
2802 that match any of the specified architecture wildcards.
2803 Specifying a list of architectures or architecture wildcards
2804 other than <tt>any</tt> is for the minority of cases where a
2805 program is not portable or is not useful on some
2806 architectures. Where possible, the program should be made
2811 In the source package control file <file>.dsc</file>, this
2812 field may contain either the architecture
2813 wildcard <tt>any</tt> or a list of architectures and
2814 architecture wildcards separated by spaces. If a list is
2815 given, it may include (or consist solely of) the special
2816 value <tt>all</tt>. In other words, in <file>.dsc</file>
2817 files unlike the <file>debian/control</file>, <tt>all</tt> may
2818 occur in combination with specific architectures.
2819 The <tt>Architecture</tt> field in the source package control
2820 file <file>.dsc</file> is generally constructed from
2821 the <tt>Architecture</tt> fields in
2822 the <file>debian/control</file> in the source package.
2826 Specifying <tt>any</tt> indicates that the source package
2827 isn't dependent on any particular architecture and should
2828 compile fine on any one. The produced binary package(s)
2829 will either be specific to whatever the current build
2830 architecture is or will be architecture-independent.
2834 Specifying only <tt>all</tt> indicates that the source package
2835 will only build architecture-independent packages. If this is
2836 the case, <tt>all</tt> must be used rather than <tt>any</tt>;
2837 <tt>any</tt> implies that the source package will build at
2838 least one architecture-dependent package.
2842 Specifying a list of architectures or architecture wildcards
2843 indicates that the source will build an architecture-dependent
2844 package, and will only work correctly on the listed or
2845 matching architectures. If the source package also builds at
2846 least one architecture-independent package, <tt>all</tt> will
2847 also be included in the list.
2851 In a <file>.changes</file> file, the <tt>Architecture</tt>
2852 field lists the architecture(s) of the package(s) currently
2853 being uploaded. This will be a list; if the source for the
2854 package is also being uploaded, the special
2855 entry <tt>source</tt> is also present. <tt>all</tt> will be
2856 present if any architecture-independent packages are being
2857 uploaded. Architecture wildcards such as <tt>any</tt> must
2858 never occur in the <tt>Architecture</tt> field in
2859 the <file>.changes</file> file.
2863 See <ref id="debianrules"> for information on how to get
2864 the architecture for the build process.
2868 <sect1 id="f-Essential">
2869 <heading><tt>Essential</tt></heading>
2872 This is a boolean field which may occur only in the
2873 control file of a binary package or in a per-package fields
2874 paragraph of a main source control data file.
2878 If set to <tt>yes</tt> then the package management system
2879 will refuse to remove the package (upgrading and replacing
2880 it is still possible). The other possible value is <tt>no</tt>,
2881 which is the same as not having the field at all.
2886 <heading>Package interrelationship fields:
2887 <tt>Depends</tt>, <tt>Pre-Depends</tt>,
2888 <tt>Recommends</tt>, <tt>Suggests</tt>,
2889 <tt>Breaks</tt>, <tt>Conflicts</tt>,
2890 <tt>Provides</tt>, <tt>Replaces</tt>, <tt>Enhances</tt>
2894 These fields describe the package's relationships with
2895 other packages. Their syntax and semantics are described
2896 in <ref id="relationships">.</p>
2899 <sect1 id="f-Standards-Version">
2900 <heading><tt>Standards-Version</tt></heading>
2903 The most recent version of the standards (the policy
2904 manual and associated texts) with which the package
2909 The version number has four components: major and minor
2910 version number and major and minor patch level. When the
2911 standards change in a way that requires every package to
2912 change the major number will be changed. Significant
2913 changes that will require work in many packages will be
2914 signaled by a change to the minor number. The major patch
2915 level will be changed for any change to the meaning of the
2916 standards, however small; the minor patch level will be
2917 changed when only cosmetic, typographical or other edits
2918 are made which neither change the meaning of the document
2919 nor affect the contents of packages.
2923 Thus only the first three components of the policy version
2924 are significant in the <em>Standards-Version</em> control
2925 field, and so either these three components or all four
2926 components may be specified.<footnote>
2927 In the past, people specified the full version number
2928 in the Standards-Version field, for example "2.3.0.0".
2929 Since minor patch-level changes don't introduce new
2930 policy, it was thought it would be better to relax
2931 policy and only require the first 3 components to be
2932 specified, in this example "2.3.0". All four
2933 components may still be used if someone wishes to do so.
2939 <sect1 id="f-Version">
2940 <heading><tt>Version</tt></heading>
2943 The version number of a package. The format is:
2944 [<var>epoch</var><tt>:</tt>]<var>upstream_version</var>[<tt>-</tt><var>debian_revision</var>]
2948 The three components here are:
2950 <tag><var>epoch</var></tag>
2953 This is a single (generally small) unsigned integer. It
2954 may be omitted, in which case zero is assumed. If it is
2955 omitted then the <var>upstream_version</var> may not
2960 It is provided to allow mistakes in the version numbers
2961 of older versions of a package, and also a package's
2962 previous version numbering schemes, to be left behind.
2966 <tag><var>upstream_version</var></tag>
2969 This is the main part of the version number. It is
2970 usually the version number of the original ("upstream")
2971 package from which the <file>.deb</file> file has been made,
2972 if this is applicable. Usually this will be in the same
2973 format as that specified by the upstream author(s);
2974 however, it may need to be reformatted to fit into the
2975 package management system's format and comparison
2980 The comparison behavior of the package management system
2981 with respect to the <var>upstream_version</var> is
2982 described below. The <var>upstream_version</var>
2983 portion of the version number is mandatory.
2987 The <var>upstream_version</var> may contain only
2988 alphanumerics<footnote>
2989 Alphanumerics are <tt>A-Za-z0-9</tt> only.
2991 and the characters <tt>.</tt> <tt>+</tt> <tt>-</tt>
2992 <tt>:</tt> <tt>~</tt> (full stop, plus, hyphen, colon,
2993 tilde) and should start with a digit. If there is no
2994 <var>debian_revision</var> then hyphens are not allowed;
2995 if there is no <var>epoch</var> then colons are not
3000 <tag><var>debian_revision</var></tag>
3003 This part of the version number specifies the version of
3004 the Debian package based on the upstream version. It
3005 may contain only alphanumerics and the characters
3006 <tt>+</tt> <tt>.</tt> <tt>~</tt> (plus, full stop,
3007 tilde) and is compared in the same way as the
3008 <var>upstream_version</var> is.
3012 It is optional; if it isn't present then the
3013 <var>upstream_version</var> may not contain a hyphen.
3014 This format represents the case where a piece of
3015 software was written specifically to be turned into a
3016 Debian package, and so there is only one "debianisation"
3017 of it and therefore no revision indication is required.
3021 It is conventional to restart the
3022 <var>debian_revision</var> at <tt>1</tt> each time the
3023 <var>upstream_version</var> is increased.
3027 The package management system will break the version
3028 number apart at the last hyphen in the string (if there
3029 is one) to determine the <var>upstream_version</var> and
3030 <var>debian_revision</var>. The absence of a
3031 <var>debian_revision</var> is equivalent to a
3032 <var>debian_revision</var> of <tt>0</tt>.
3039 When comparing two version numbers, first the <var>epoch</var>
3040 of each are compared, then the <var>upstream_version</var> if
3041 <var>epoch</var> is equal, and then <var>debian_revision</var>
3042 if <var>upstream_version</var> is also equal.
3043 <var>epoch</var> is compared numerically. The
3044 <var>upstream_version</var> and <var>debian_revision</var>
3045 parts are compared by the package management system using the
3046 following algorithm:
3050 The strings are compared from left to right.
3054 First the initial part of each string consisting entirely of
3055 non-digit characters is determined. These two parts (one of
3056 which may be empty) are compared lexically. If a difference
3057 is found it is returned. The lexical comparison is a
3058 comparison of ASCII values modified so that all the letters
3059 sort earlier than all the non-letters and so that a tilde
3060 sorts before anything, even the end of a part. For example,
3061 the following parts are in sorted order from earliest to
3062 latest: <tt>~~</tt>, <tt>~~a</tt>, <tt>~</tt>, the empty part,
3063 <tt>a</tt>.<footnote>
3064 One common use of <tt>~</tt> is for upstream pre-releases.
3065 For example, <tt>1.0~beta1~svn1245</tt> sorts earlier than
3066 <tt>1.0~beta1</tt>, which sorts earlier than <tt>1.0</tt>.
3071 Then the initial part of the remainder of each string which
3072 consists entirely of digit characters is determined. The
3073 numerical values of these two parts are compared, and any
3074 difference found is returned as the result of the comparison.
3075 For these purposes an empty string (which can only occur at
3076 the end of one or both version strings being compared) counts
3081 These two steps (comparing and removing initial non-digit
3082 strings and initial digit strings) are repeated until a
3083 difference is found or both strings are exhausted.
3087 Note that the purpose of epochs is to allow us to leave behind
3088 mistakes in version numbering, and to cope with situations
3089 where the version numbering scheme changes. It is
3090 <em>not</em> intended to cope with version numbers containing
3091 strings of letters which the package management system cannot
3092 interpret (such as <tt>ALPHA</tt> or <tt>pre-</tt>), or with
3093 silly orderings.<footnote>
3094 The author of this manual has heard of a package whose
3095 versions went <tt>1.1</tt>, <tt>1.2</tt>, <tt>1.3</tt>,
3096 <tt>1</tt>, <tt>2.1</tt>, <tt>2.2</tt>, <tt>2</tt> and so
3102 <sect1 id="f-Description">
3103 <heading><tt>Description</tt></heading>
3106 In a source or binary control file, the <tt>Description</tt>
3107 field contains a description of the binary package, consisting
3108 of two parts, the synopsis or the short description, and the
3109 long description. The field's format is as follows:
3114 Description: <single line synopsis>
3115 <extended description over several lines>
3120 The lines in the extended description can have these formats:
3126 Those starting with a single space are part of a paragraph.
3127 Successive lines of this form will be word-wrapped when
3128 displayed. The leading space will usually be stripped off.
3132 Those starting with two or more spaces. These will be
3133 displayed verbatim. If the display cannot be panned
3134 horizontally, the displaying program will line wrap them "hard"
3135 (i.e., without taking account of word breaks). If it can they
3136 will be allowed to trail off to the right. None, one or two
3137 initial spaces may be deleted, but the number of spaces
3138 deleted from each line will be the same (so that you can have
3139 indenting work correctly, for example).
3143 Those containing a single space followed by a single full stop
3144 character. These are rendered as blank lines. This is the
3145 <em>only</em> way to get a blank line<footnote>
3146 Completely empty lines will not be rendered as blank lines.
3147 Instead, they will cause the parser to think you're starting
3148 a whole new record in the control file, and will therefore
3149 likely abort with an error.
3154 Those containing a space, a full stop and some more characters.
3155 These are for future expansion. Do not use them.
3161 Do not use tab characters. Their effect is not predictable.
3165 See <ref id="descriptions"> for further information on this.
3169 In a <file>.changes</file> file, the <tt>Description</tt>
3170 field contains a summary of the descriptions for the packages
3171 being uploaded. For this case, the first line of the field
3172 value (the part on the same line as <tt>Description:</tt>) is
3173 always empty. The content of the field is expressed as
3174 continuation lines, one line per package. Each line is
3175 indented by one space and contains the name of a binary
3176 package, a space, a hyphen (<tt>-</tt>), a space, and the
3177 short description line from that package.
3181 <sect1 id="f-Distribution">
3182 <heading><tt>Distribution</tt></heading>
3185 In a <file>.changes</file> file or parsed changelog output
3186 this contains the (space-separated) name(s) of the
3187 distribution(s) where this version of the package should
3188 be installed. Valid distributions are determined by the
3189 archive maintainers.<footnote>
3190 Example distribution names in the Debian archive used in
3191 <file>.changes</file> files are:
3192 <taglist compact="compact">
3193 <tag><em>unstable</em></tag>
3195 This distribution value refers to the
3196 <em>developmental</em> part of the Debian distribution
3197 tree. Most new packages, new upstream versions of
3198 packages and bug fixes go into the <em>unstable</em>
3202 <tag><em>experimental</em></tag>
3204 The packages with this distribution value are deemed
3205 by their maintainers to be high risk. Oftentimes they
3206 represent early beta or developmental packages from
3207 various sources that the maintainers want people to
3208 try, but are not ready to be a part of the other parts
3209 of the Debian distribution tree.
3214 Others are used for updating stable releases or for
3215 security uploads. More information is available in the
3216 Debian Developer's Reference, section "The Debian
3220 The Debian archive software only supports listing a single
3221 distribution. Migration of packages to other distributions is
3222 handled outside of the upload process.
3227 <heading><tt>Date</tt></heading>
3230 This field includes the date the package was built or last
3231 edited. It must be in the same format as the <var>date</var>
3232 in a <file>debian/changelog</file> entry.
3236 The value of this field is usually extracted from the
3237 <file>debian/changelog</file> file - see
3238 <ref id="dpkgchangelog">).
3242 <sect1 id="f-Format">
3243 <heading><tt>Format</tt></heading>
3246 This field specifies a format revision for the file.
3247 The most current format described in the Policy Manual
3248 is version <strong>1.5</strong>. The syntax of the
3249 format value is the same as that of a package version
3250 number except that no epoch or Debian revision is allowed
3251 - see <ref id="f-Version">.
3255 <sect1 id="f-Urgency">
3256 <heading><tt>Urgency</tt></heading>
3259 This is a description of how important it is to upgrade to
3260 this version from previous ones. It consists of a single
3261 keyword taking one of the values <tt>low</tt>,
3262 <tt>medium</tt>, <tt>high</tt>, <tt>emergency</tt>, or
3263 <tt>critical</tt><footnote>
3264 Other urgency values are supported with configuration
3265 changes in the archive software but are not used in Debian.
3266 The urgency affects how quickly a package will be considered
3267 for inclusion into the <tt>testing</tt> distribution and
3268 gives an indication of the importance of any fixes included
3269 in the upload. <tt>Emergency</tt> and <tt>critical</tt> are
3270 treated as synonymous.
3271 </footnote> (not case-sensitive) followed by an optional
3272 commentary (separated by a space) which is usually in
3273 parentheses. For example:
3276 Urgency: low (HIGH for users of diversions)
3282 The value of this field is usually extracted from the
3283 <file>debian/changelog</file> file - see
3284 <ref id="dpkgchangelog">.
3288 <sect1 id="f-Changes">
3289 <heading><tt>Changes</tt></heading>
3292 This field contains the human-readable changes data, describing
3293 the differences between the last version and the current one.
3297 The first line of the field value (the part on the same line
3298 as <tt>Changes:</tt>) is always empty. The content of the
3299 field is expressed as continuation lines, with each line
3300 indented by at least one space. Blank lines must be
3301 represented by a line consisting only of a space and a full
3306 The value of this field is usually extracted from the
3307 <file>debian/changelog</file> file - see
3308 <ref id="dpkgchangelog">).
3312 Each version's change information should be preceded by a
3313 "title" line giving at least the version, distribution(s)
3314 and urgency, in a human-readable way.
3318 If data from several versions is being returned the entry
3319 for the most recent version should be returned first, and
3320 entries should be separated by the representation of a
3321 blank line (the "title" line may also be followed by the
3322 representation of a blank line).
3326 <sect1 id="f-Binary">
3327 <heading><tt>Binary</tt></heading>
3330 This field is a list of binary packages. Its syntax and
3331 meaning varies depending on the control file in which it
3336 When it appears in the <file>.dsc</file> file, it lists binary
3337 packages which a source package can produce, separated by
3339 A space after each comma is conventional.
3340 </footnote>. It may span multiple lines. The source package
3341 does not necessarily produce all of these binary packages for
3342 every architecture. The source control file doesn't contain
3343 details of which architectures are appropriate for which of
3344 the binary packages.
3348 When it appears in a <file>.changes</file> file, it lists the
3349 names of the binary packages being uploaded, separated by
3350 whitespace (not commas). It may span multiple lines.
3354 <sect1 id="f-Installed-Size">
3355 <heading><tt>Installed-Size</tt></heading>
3358 This field appears in the control files of binary packages,
3359 and in the <file>Packages</file> files. It gives an estimate
3360 of the total amount of disk space required to install the
3361 named package. Actual installed size may vary based on block
3362 size, file system properties, or actions taken by package
3367 The disk space is given as the integer value of the estimated
3368 installed size in bytes, divided by 1024 and rounded up.
3372 <sect1 id="f-Files">
3373 <heading><tt>Files</tt></heading>
3376 This field contains a list of files with information about
3377 each one. The exact information and syntax varies with
3382 In all cases, Files is a multiline field. The first line of
3383 the field value (the part on the same line as <tt>Files:</tt>)
3384 is always empty. The content of the field is expressed as
3385 continuation lines, one line per file. Each line must be
3386 indented by one space and contain a number of sub-fields,
3387 separated by spaces, as described below.
3391 In the <file>.dsc</file> file, each line contains the MD5
3392 checksum, size and filename of the tar file and (if
3393 applicable) diff file which make up the remainder of the
3394 source package<footnote>
3395 That is, the parts which are not the <tt>.dsc</tt>.
3396 </footnote>. For example:
3399 c6f698f19f2a2aa07dbb9bbda90a2754 571925 example_1.2.orig.tar.gz
3400 938512f08422f3509ff36f125f5873ba 6220 example_1.2-1.diff.gz
3402 The exact forms of the filenames are described
3403 in <ref id="pkg-sourcearchives">.
3407 In the <file>.changes</file> file this contains one line per
3408 file being uploaded. Each line contains the MD5 checksum,
3409 size, section and priority and the filename. For example:
3412 4c31ab7bfc40d3cf49d7811987390357 1428 text extra example_1.2-1.dsc
3413 c6f698f19f2a2aa07dbb9bbda90a2754 571925 text extra example_1.2.orig.tar.gz
3414 938512f08422f3509ff36f125f5873ba 6220 text extra example_1.2-1.diff.gz
3415 7c98fe853b3bbb47a00e5cd129b6cb56 703542 text extra example_1.2-1_i386.deb
3417 The <qref id="f-Section">section</qref>
3418 and <qref id="f-Priority">priority</qref> are the values of
3419 the corresponding fields in the main source control file. If
3420 no section or priority is specified then <tt>-</tt> should be
3421 used, though section and priority values must be specified for
3422 new packages to be installed properly.
3426 The special value <tt>byhand</tt> for the section in a
3427 <tt>.changes</tt> file indicates that the file in question
3428 is not an ordinary package file and must by installed by
3429 hand by the distribution maintainers. If the section is
3430 <tt>byhand</tt> the priority should be <tt>-</tt>.
3434 If a new Debian revision of a package is being shipped and
3435 no new original source archive is being distributed the
3436 <tt>.dsc</tt> must still contain the <tt>Files</tt> field
3437 entry for the original source archive
3438 <file><var>package</var>_<var>upstream-version</var>.orig.tar.gz</file>,
3439 but the <file>.changes</file> file should leave it out. In
3440 this case the original source archive on the distribution
3441 site must match exactly, byte-for-byte, the original
3442 source archive which was used to generate the
3443 <file>.dsc</file> file and diff which are being uploaded.</p>
3446 <sect1 id="f-Closes">
3447 <heading><tt>Closes</tt></heading>
3450 A space-separated list of bug report numbers that the upload
3451 governed by the .changes file closes.
3455 <sect1 id="f-Homepage">
3456 <heading><tt>Homepage</tt></heading>
3459 The URL of the web site for this package, preferably (when
3460 applicable) the site from which the original source can be
3461 obtained and any additional upstream documentation or
3462 information may be found. The content of this field is a
3463 simple URL without any surrounding characters such as
3471 <heading>User-defined fields</heading>
3474 Additional user-defined fields may be added to the
3475 source package control file. Such fields will be
3476 ignored, and not copied to (for example) binary or
3477 source package control files or upload control files.
3481 If you wish to add additional unsupported fields to
3482 these output files you should use the mechanism
3487 Fields in the main source control information file with
3488 names starting <tt>X</tt>, followed by one or more of
3489 the letters <tt>BCS</tt> and a hyphen <tt>-</tt>, will
3490 be copied to the output files. Only the part of the
3491 field name after the hyphen will be used in the output
3492 file. Where the letter <tt>B</tt> is used the field
3493 will appear in binary package control files, where the
3494 letter <tt>S</tt> is used in source package control
3495 files and where <tt>C</tt> is used in upload control
3496 (<tt>.changes</tt>) files.
3500 For example, if the main source information control file
3503 XBS-Comment: I stand between the candle and the star.
3505 then the binary and source package control files will contain the
3508 Comment: I stand between the candle and the star.
3517 <chapt id="maintainerscripts">
3518 <heading>Package maintainer scripts and installation procedure</heading>
3521 <heading>Introduction to package maintainer scripts</heading>
3524 It is possible to supply scripts as part of a package which
3525 the package management system will run for you when your
3526 package is installed, upgraded or removed.
3530 These scripts are the files <prgn>preinst</prgn>,
3531 <prgn>postinst</prgn>, <prgn>prerm</prgn> and
3532 <prgn>postrm</prgn> in the control area of the package.
3533 They must be proper executable files; if they are scripts
3534 (which is recommended), they must start with the usual
3535 <tt>#!</tt> convention. They should be readable and
3536 executable by anyone, and must not be world-writable.
3540 The package management system looks at the exit status from
3541 these scripts. It is important that they exit with a
3542 non-zero status if there is an error, so that the package
3543 management system can stop its processing. For shell
3544 scripts this means that you <em>almost always</em> need to
3545 use <tt>set -e</tt> (this is usually true when writing shell
3546 scripts, in fact). It is also important, of course, that
3547 they exit with a zero status if everything went well.
3551 Additionally, packages interacting with users using
3552 <tt>debconf</tt> in the <prgn>postinst</prgn> script should
3553 install a <prgn>config</prgn> script in the control area,
3554 see <ref id="maintscriptprompt"> for details.
3558 When a package is upgraded a combination of the scripts from
3559 the old and new packages is called during the upgrade
3560 procedure. If your scripts are going to be at all
3561 complicated you need to be aware of this, and may need to
3562 check the arguments to your scripts.
3566 Broadly speaking the <prgn>preinst</prgn> is called before
3567 (a particular version of) a package is installed, and the
3568 <prgn>postinst</prgn> afterwards; the <prgn>prerm</prgn>
3569 before (a version of) a package is removed and the
3570 <prgn>postrm</prgn> afterwards.
3574 Programs called from maintainer scripts should not normally
3575 have a path prepended to them. Before installation is
3576 started, the package management system checks to see if the
3577 programs <prgn>ldconfig</prgn>,
3578 <prgn>start-stop-daemon</prgn>, <prgn>install-info</prgn>,
3579 and <prgn>update-rc.d</prgn> can be found via the
3580 <tt>PATH</tt> environment variable. Those programs, and any
3581 other program that one would expect to be in the
3582 <tt>PATH</tt>, should thus be invoked without an absolute
3583 pathname. Maintainer scripts should also not reset the
3584 <tt>PATH</tt>, though they might choose to modify it by
3585 prepending or appending package-specific directories. These
3586 considerations really apply to all shell scripts.</p>
3589 <sect id="idempotency">
3590 <heading>Maintainer scripts idempotency</heading>
3593 It is necessary for the error recovery procedures that the
3594 scripts be idempotent. This means that if it is run
3595 successfully, and then it is called again, it doesn't bomb
3596 out or cause any harm, but just ensures that everything is
3597 the way it ought to be. If the first call failed, or
3598 aborted half way through for some reason, the second call
3599 should merely do the things that were left undone the first
3600 time, if any, and exit with a success status if everything
3602 This is so that if an error occurs, the user interrupts
3603 <prgn>dpkg</prgn> or some other unforeseen circumstance
3604 happens you don't leave the user with a badly-broken
3605 package when <prgn>dpkg</prgn> attempts to repeat the
3611 <sect id="controllingterminal">
3612 <heading>Controlling terminal for maintainer scripts</heading>
3615 Maintainer scripts are not guaranteed to run with a controlling
3616 terminal and may not be able to interact with the user. They
3617 must be able to fall back to noninteractive behavior if no
3618 controlling terminal is available. Maintainer scripts that
3619 prompt via a program conforming to the Debian Configuration
3620 Management Specification (see <ref id="maintscriptprompt">) may
3621 assume that program will handle falling back to noninteractive
3626 For high-priority prompts without a reasonable default answer,
3627 maintainer scripts may abort if there is no controlling
3628 terminal. However, this situation should be avoided if at all
3629 possible, since it prevents automated or unattended installs.
3630 In most cases, users will consider this to be a bug in the
3635 <sect id="exitstatus">
3636 <heading>Exit status</heading>
3639 Each script must return a zero exit status for
3640 success, or a nonzero one for failure, since the package
3641 management system looks for the exit status of these scripts
3642 and determines what action to take next based on that datum.
3646 <sect id="mscriptsinstact"><heading>Summary of ways maintainer
3651 <list compact="compact">
3653 <var>new-preinst</var> <tt>install</tt>
3656 <var>new-preinst</var> <tt>install</tt> <var>old-version</var>
3659 <var>new-preinst</var> <tt>upgrade</tt> <var>old-version</var>
3662 <var>old-preinst</var> <tt>abort-upgrade</tt>
3663 <var>new-version</var>
3668 <list compact="compact">
3670 <var>postinst</var> <tt>configure</tt>
3671 <var>most-recently-configured-version</var>
3674 <var>old-postinst</var> <tt>abort-upgrade</tt>
3675 <var>new-version</var>
3678 <var>conflictor's-postinst</var> <tt>abort-remove</tt>
3679 <tt>in-favour</tt> <var>package</var>
3680 <var>new-version</var>
3683 <var>postinst</var> <tt>abort-remove</tt>
3686 <var>deconfigured's-postinst</var>
3687 <tt>abort-deconfigure</tt> <tt>in-favour</tt>
3688 <var>failed-install-package</var> <var>version</var>
3689 [<tt>removing</tt> <var>conflicting-package</var>
3695 <list compact="compact">
3697 <var>prerm</var> <tt>remove</tt>
3700 <var>old-prerm</var> <tt>upgrade</tt>
3701 <var>new-version</var>
3704 <var>new-prerm</var> <tt>failed-upgrade</tt>
3705 <var>old-version</var>
3708 <var>conflictor's-prerm</var> <tt>remove</tt>
3709 <tt>in-favour</tt> <var>package</var>
3710 <var>new-version</var>
3713 <var>deconfigured's-prerm</var> <tt>deconfigure</tt>
3714 <tt>in-favour</tt> <var>package-being-installed</var>
3715 <var>version</var> [<tt>removing</tt>
3716 <var>conflicting-package</var>
3722 <list compact="compact">
3724 <var>postrm</var> <tt>remove</tt>
3727 <var>postrm</var> <tt>purge</tt>
3730 <var>old-postrm</var> <tt>upgrade</tt>
3731 <var>new-version</var>
3734 <var>new-postrm</var> <tt>failed-upgrade</tt>
3735 <var>old-version</var>
3738 <var>new-postrm</var> <tt>abort-install</tt>
3741 <var>new-postrm</var> <tt>abort-install</tt>
3742 <var>old-version</var>
3745 <var>new-postrm</var> <tt>abort-upgrade</tt>
3746 <var>old-version</var>
3749 <var>disappearer's-postrm</var> <tt>disappear</tt>
3750 <var>overwriter</var>
3751 <var>overwriter-version</var>
3757 <sect id="unpackphase">
3758 <heading>Details of unpack phase of installation or upgrade</heading>
3761 The procedure on installation/upgrade/overwrite/disappear
3762 (i.e., when running <tt>dpkg --unpack</tt>, or the unpack
3763 stage of <tt>dpkg --install</tt>) is as follows. In each
3764 case, if a major error occurs (unless listed below) the
3765 actions are, in general, run backwards - this means that the
3766 maintainer scripts are run with different arguments in
3767 reverse order. These are the "error unwind" calls listed
3774 If a version of the package is already installed, call
3775 <example compact="compact">
3776 <var>old-prerm</var> upgrade <var>new-version</var>
3780 If the script runs but exits with a non-zero
3781 exit status, <prgn>dpkg</prgn> will attempt:
3782 <example compact="compact">
3783 <var>new-prerm</var> failed-upgrade <var>old-version</var>
3785 If this works, the upgrade continues. If this
3786 does not work, the error unwind:
3787 <example compact="compact">
3788 <var>old-postinst</var> abort-upgrade <var>new-version</var>
3790 If this works, then the old-version is
3791 "Installed", if not, the old version is in a
3792 "Half-Configured" state.
3798 If a "conflicting" package is being removed at the same time,
3799 or if any package will be broken (due to <tt>Breaks</tt>):
3802 If <tt>--auto-deconfigure</tt> is
3803 specified, call, for each package to be deconfigured
3804 due to <tt>Breaks</tt>:
3805 <example compact="compact">
3806 <var>deconfigured's-prerm</var> deconfigure \
3807 in-favour <var>package-being-installed</var> <var>version</var>
3810 <example compact="compact">
3811 <var>deconfigured's-postinst</var> abort-deconfigure \
3812 in-favour <var>package-being-installed-but-failed</var> <var>version</var>
3814 The deconfigured packages are marked as
3815 requiring configuration, so that if
3816 <tt>--install</tt> is used they will be
3817 configured again if possible.
3820 If any packages depended on a conflicting
3821 package being removed and <tt>--auto-deconfigure</tt> is
3822 specified, call, for each such package:
3823 <example compact="compact">
3824 <var>deconfigured's-prerm</var> deconfigure \
3825 in-favour <var>package-being-installed</var> <var>version</var> \
3826 removing <var>conflicting-package</var> <var>version</var>
3829 <example compact="compact">
3830 <var>deconfigured's-postinst</var> abort-deconfigure \
3831 in-favour <var>package-being-installed-but-failed</var> <var>version</var> \
3832 removing <var>conflicting-package</var> <var>version</var>
3834 The deconfigured packages are marked as
3835 requiring configuration, so that if
3836 <tt>--install</tt> is used they will be
3837 configured again if possible.
3840 To prepare for removal of each conflicting package, call:
3841 <example compact="compact">
3842 <var>conflictor's-prerm</var> remove \
3843 in-favour <var>package</var> <var>new-version</var>
3846 <example compact="compact">
3847 <var>conflictor's-postinst</var> abort-remove \
3848 in-favour <var>package</var> <var>new-version</var>
3857 If the package is being upgraded, call:
3858 <example compact="compact">
3859 <var>new-preinst</var> upgrade <var>old-version</var>
3861 If this fails, we call:
3863 <var>new-postrm</var> abort-upgrade <var>old-version</var>
3870 <var>old-postinst</var> abort-upgrade <var>new-version</var>
3872 is called. If this works, then the old version
3873 is in an "Installed" state, or else it is left
3874 in an "Unpacked" state.
3879 If it fails, then the old version is left
3880 in an "Half-Installed" state.
3887 Otherwise, if the package had some configuration
3888 files from a previous version installed (i.e., it
3889 is in the "configuration files only" state):
3890 <example compact="compact">
3891 <var>new-preinst</var> install <var>old-version</var>
3895 <var>new-postrm</var> abort-install <var>old-version</var>
3897 If this fails, the package is left in a
3898 "Half-Installed" state, which requires a
3899 reinstall. If it works, the packages is left in
3900 a "Config-Files" state.
3903 Otherwise (i.e., the package was completely purged):
3904 <example compact="compact">
3905 <var>new-preinst</var> install
3908 <example compact="compact">
3909 <var>new-postrm</var> abort-install
3911 If the error-unwind fails, the package is in a
3912 "Half-Installed" phase, and requires a
3913 reinstall. If the error unwind works, the
3914 package is in a not installed state.
3921 The new package's files are unpacked, overwriting any
3922 that may be on the system already, for example any
3923 from the old version of the same package or from
3924 another package. Backups of the old files are kept
3925 temporarily, and if anything goes wrong the package
3926 management system will attempt to put them back as
3927 part of the error unwind.
3931 It is an error for a package to contain files which
3932 are on the system in another package, unless
3933 <tt>Replaces</tt> is used (see <ref id="replaces">).
3935 The following paragraph is not currently the case:
3936 Currently the <tt>- - force-overwrite</tt> flag is
3937 enabled, downgrading it to a warning, but this may not
3943 It is a more serious error for a package to contain a
3944 plain file or other kind of non-directory where another
3945 package has a directory (again, unless
3946 <tt>Replaces</tt> is used). This error can be
3947 overridden if desired using
3948 <tt>--force-overwrite-dir</tt>, but this is not
3953 Packages which overwrite each other's files produce
3954 behavior which, though deterministic, is hard for the
3955 system administrator to understand. It can easily
3956 lead to "missing" programs if, for example, a package
3957 is installed which overwrites a file from another
3958 package, and is then removed again.<footnote>
3959 Part of the problem is due to what is arguably a
3960 bug in <prgn>dpkg</prgn>.
3965 A directory will never be replaced by a symbolic link
3966 to a directory or vice versa; instead, the existing
3967 state (symlink or not) will be left alone and
3968 <prgn>dpkg</prgn> will follow the symlink if there is
3977 If the package is being upgraded, call
3978 <example compact="compact">
3979 <var>old-postrm</var> upgrade <var>new-version</var>
3983 If this fails, <prgn>dpkg</prgn> will attempt:
3984 <example compact="compact">
3985 <var>new-postrm</var> failed-upgrade <var>old-version</var>
3987 If this works, installation continues. If not,
3989 <example compact="compact">
3990 <var>old-preinst</var> abort-upgrade <var>new-version</var>
3992 If this fails, the old version is left in a
3993 "Half-Installed" state. If it works, dpkg now
3995 <example compact="compact">
3996 <var>new-postrm</var> abort-upgrade <var>old-version</var>
3998 If this fails, the old version is left in a
3999 "Half-Installed" state. If it works, dpkg now
4001 <example compact="compact">
4002 <var>old-postinst</var> abort-upgrade <var>new-version</var>
4004 If this fails, the old version is in an
4011 This is the point of no return - if
4012 <prgn>dpkg</prgn> gets this far, it won't back off
4013 past this point if an error occurs. This will
4014 leave the package in a fairly bad state, which
4015 will require a successful re-installation to clear
4016 up, but it's when <prgn>dpkg</prgn> starts doing
4017 things that are irreversible.
4022 Any files which were in the old version of the package
4023 but not in the new are removed.
4027 The new file list replaces the old.
4031 The new maintainer scripts replace the old.
4035 Any packages all of whose files have been overwritten
4036 during the installation, and which aren't required for
4037 dependencies, are considered to have been removed.
4038 For each such package
4041 <prgn>dpkg</prgn> calls:
4042 <example compact="compact">
4043 <var>disappearer's-postrm</var> disappear \
4044 <var>overwriter</var> <var>overwriter-version</var>
4048 The package's maintainer scripts are removed.
4051 It is noted in the status database as being in a
4052 sane state, namely not installed (any conffiles
4053 it may have are ignored, rather than being
4054 removed by <prgn>dpkg</prgn>). Note that
4055 disappearing packages do not have their prerm
4056 called, because <prgn>dpkg</prgn> doesn't know
4057 in advance that the package is going to
4064 Any files in the package we're unpacking that are also
4065 listed in the file lists of other packages are removed
4066 from those lists. (This will lobotomize the file list
4067 of the "conflicting" package if there is one.)
4071 The backup files made during installation, above, are
4077 The new package's status is now sane, and recorded as
4082 Here is another point of no return - if the
4083 conflicting package's removal fails we do not unwind
4084 the rest of the installation; the conflicting package
4085 is left in a half-removed limbo.
4090 If there was a conflicting package we go and do the
4091 removal actions (described below), starting with the
4092 removal of the conflicting package's files (any that
4093 are also in the package being installed have already
4094 been removed from the conflicting package's file list,
4095 and so do not get removed now).
4101 <sect id="configdetails"><heading>Details of configuration</heading>
4104 When we configure a package (this happens with <tt>dpkg
4105 --install</tt> and <tt>dpkg --configure</tt>), we first
4106 update any <tt>conffile</tt>s and then call:
4107 <example compact="compact">
4108 <var>postinst</var> configure <var>most-recently-configured-version</var>
4113 No attempt is made to unwind after errors during
4114 configuration. If the configuration fails, the package is in
4115 a "Failed Config" state, and an error message is generated.
4119 If there is no most recently configured version
4120 <prgn>dpkg</prgn> will pass a null argument.
4123 Historical note: Truly ancient (pre-1997) versions of
4124 <prgn>dpkg</prgn> passed <tt><unknown></tt>
4125 (including the angle brackets) in this case. Even older
4126 ones did not pass a second argument at all, under any
4127 circumstance. Note that upgrades using such an old dpkg
4128 version are unlikely to work for other reasons, even if
4129 this old argument behavior is handled by your postinst script.
4135 <sect id="removedetails"><heading>Details of removal and/or
4136 configuration purging</heading>
4142 <example compact="compact">
4143 <var>prerm</var> remove
4147 If prerm fails during replacement due to conflict
4149 <var>conflictor's-postinst</var> abort-remove \
4150 in-favour <var>package</var> <var>new-version</var>
4154 <var>postinst</var> abort-remove
4158 If this fails, the package is in a "Half-Configured"
4159 state, or else it remains "Installed".
4163 The package's files are removed (except <tt>conffile</tt>s).
4166 <example compact="compact">
4167 <var>postrm</var> remove
4171 If it fails, there's no error unwind, and the package is in
4172 an "Half-Installed" state.
4177 All the maintainer scripts except the <prgn>postrm</prgn>
4182 If we aren't purging the package we stop here. Note
4183 that packages which have no <prgn>postrm</prgn> and no
4184 <tt>conffile</tt>s are automatically purged when
4185 removed, as there is no difference except for the
4186 <prgn>dpkg</prgn> status.
4190 The <tt>conffile</tt>s and any backup files
4191 (<tt>~</tt>-files, <tt>#*#</tt> files,
4192 <tt>%</tt>-files, <tt>.dpkg-{old,new,tmp}</tt>, etc.)
4197 <example compact="compact">
4198 <var>postrm</var> purge
4202 If this fails, the package remains in a "Config-Files"
4207 The package's file list is removed.
4216 <chapt id="relationships">
4217 <heading>Declaring relationships between packages</heading>
4219 <sect id="depsyntax">
4220 <heading>Syntax of relationship fields</heading>
4223 These fields all have a uniform syntax. They are a list of
4224 package names separated by commas.
4228 In the <tt>Depends</tt>, <tt>Recommends</tt>,
4229 <tt>Suggests</tt>, <tt>Pre-Depends</tt>,
4230 <tt>Build-Depends</tt> and <tt>Build-Depends-Indep</tt>
4231 control file fields of the package, which declare
4232 dependencies on other packages, the package names listed may
4233 also include lists of alternative package names, separated
4234 by vertical bar (pipe) symbols <tt>|</tt>. In such a case,
4235 if any one of the alternative packages is installed, that
4236 part of the dependency is considered to be satisfied.
4240 All of the fields except for <tt>Provides</tt> may restrict
4241 their applicability to particular versions of each named
4242 package. This is done in parentheses after each individual
4243 package name; the parentheses should contain a relation from
4244 the list below followed by a version number, in the format
4245 described in <ref id="f-Version">.
4249 The relations allowed are <tt><<</tt>, <tt><=</tt>,
4250 <tt>=</tt>, <tt>>=</tt> and <tt>>></tt> for
4251 strictly earlier, earlier or equal, exactly equal, later or
4252 equal and strictly later, respectively. The deprecated
4253 forms <tt><</tt> and <tt>></tt> were used to mean
4254 earlier/later or equal, rather than strictly earlier/later,
4255 so they should not appear in new packages (though
4256 <prgn>dpkg</prgn> still supports them).
4260 Whitespace may appear at any point in the version
4261 specification subject to the rules in <ref
4262 id="controlsyntax">, and must appear where it's necessary to
4263 disambiguate; it is not otherwise significant. All of the
4264 relationship fields may span multiple lines. For
4265 consistency and in case of future changes to
4266 <prgn>dpkg</prgn> it is recommended that a single space be
4267 used after a version relationship and before a version
4268 number; it is also conventional to put a single space after
4269 each comma, on either side of each vertical bar, and before
4270 each open parenthesis. When wrapping a relationship field, it
4271 is conventional to do so after a comma and before the space
4272 following that comma.
4276 For example, a list of dependencies might appear as:
4277 <example compact="compact">
4280 Depends: libc6 (>= 2.2.1), exim | mail-transport-agent
4285 All fields that specify build-time relationships
4286 (<tt>Build-Depends</tt>, <tt>Build-Depends-Indep</tt>,
4287 <tt>Build-Conflicts</tt> and <tt>Build-Conflicts-Indep</tt>)
4288 may be restricted to a certain set of architectures. This
4289 is indicated in brackets after each individual package name and
4290 the optional version specification. The brackets enclose a
4291 list of Debian architecture names separated by whitespace.
4292 Exclamation marks may be prepended to each of the names.
4293 (It is not permitted for some names to be prepended with
4294 exclamation marks while others aren't.) If the current Debian
4295 host architecture is not in this list and there are no
4296 exclamation marks in the list, or it is in the list with a
4297 prepended exclamation mark, the package name and the
4298 associated version specification are ignored completely for
4299 the purposes of defining the relationships.
4304 <example compact="compact">
4306 Build-Depends-Indep: texinfo
4307 Build-Depends: kernel-headers-2.2.10 [!hurd-i386],
4308 hurd-dev [hurd-i386], gnumach-dev [hurd-i386]
4310 requires <tt>kernel-headers-2.2.10</tt> on all architectures
4311 other than hurd-i386 and requires <tt>hurd-dev</tt> and
4312 <tt>gnumach-dev</tt> only on hurd-i386.
4316 If the architecture-restricted dependency is part of a set of
4317 alternatives using <tt>|</tt>, that alternative is ignored
4318 completely on architectures that do not match the restriction.
4320 <example compact="compact">
4321 Build-Depends: foo [!i386] | bar [!amd64]
4323 is equivalent to <tt>bar</tt> on the i386 architecture, to
4324 <tt>foo</tt> on the amd64 architecture, and to <tt>foo |
4325 bar</tt> on all other architectures.
4329 All fields that specify build-time relationships may also be
4330 restricted to a certain set of architectures using architecture
4331 wildcards. The syntax for declaring such restrictions is the
4332 same as declaring restrictions using a certain set of
4333 architectures without architecture wildcards. For example:
4334 <example compact="compact">
4335 Build-Depends: foo [linux-any], bar [any-i386], baz [!linux-any]
4337 is equivalent to <tt>foo</tt> on architectures using the Linux
4338 kernel and any cpu, <tt>bar</tt> on architectures using any
4339 kernel and an i386 cpu, and <tt>baz</tt> on any architecture
4340 using a kernel other than Linux.
4344 Note that the binary package relationship fields such as
4345 <tt>Depends</tt> appear in one of the binary package
4346 sections of the control file, whereas the build-time
4347 relationships such as <tt>Build-Depends</tt> appear in the
4348 source package section of the control file (which is the
4353 <sect id="binarydeps">
4354 <heading>Binary Dependencies - <tt>Depends</tt>,
4355 <tt>Recommends</tt>, <tt>Suggests</tt>, <tt>Enhances</tt>,
4356 <tt>Pre-Depends</tt>
4360 Packages can declare in their control file that they have
4361 certain relationships to other packages - for example, that
4362 they may not be installed at the same time as certain other
4363 packages, and/or that they depend on the presence of others.
4367 This is done using the <tt>Depends</tt>, <tt>Pre-Depends</tt>,
4368 <tt>Recommends</tt>, <tt>Suggests</tt>, <tt>Enhances</tt>,
4369 <tt>Breaks</tt> and <tt>Conflicts</tt> control file fields.
4370 <tt>Breaks</tt> is described in <ref id="breaks">, and
4371 <tt>Conflicts</tt> is described in <ref id="conflicts">. The
4372 rest are described below.
4376 These seven fields are used to declare a dependency
4377 relationship by one package on another. Except for
4378 <tt>Enhances</tt> and <tt>Breaks</tt>, they appear in the
4379 depending (binary) package's control file.
4380 (<tt>Enhances</tt> appears in the recommending package's
4381 control file, and <tt>Breaks</tt> appears in the version of
4382 depended-on package which causes the named package to
4387 A <tt>Depends</tt> field takes effect <em>only</em> when a
4388 package is to be configured. It does not prevent a package
4389 being on the system in an unconfigured state while its
4390 dependencies are unsatisfied, and it is possible to replace
4391 a package whose dependencies are satisfied and which is
4392 properly installed with a different version whose
4393 dependencies are not and cannot be satisfied; when this is
4394 done the depending package will be left unconfigured (since
4395 attempts to configure it will give errors) and will not
4396 function properly. If it is necessary, a
4397 <tt>Pre-Depends</tt> field can be used, which has a partial
4398 effect even when a package is being unpacked, as explained
4399 in detail below. (The other three dependency fields,
4400 <tt>Recommends</tt>, <tt>Suggests</tt> and
4401 <tt>Enhances</tt>, are only used by the various front-ends
4402 to <prgn>dpkg</prgn> such as <prgn>apt-get</prgn>,
4403 <prgn>aptitude</prgn>, and <prgn>dselect</prgn>.)
4407 For this reason packages in an installation run are usually
4408 all unpacked first and all configured later; this gives
4409 later versions of packages with dependencies on later
4410 versions of other packages the opportunity to have their
4411 dependencies satisfied.
4415 In case of circular dependencies, since installation or
4416 removal order honoring the dependency order can't be
4417 established, dependency loops are broken at some point
4418 (based on rules below), and some packages may not be able to
4419 rely on their dependencies being present when being
4420 installed or removed, depending on which side of the break
4421 of the circular dependency loop they happen to be on. If one
4422 of the packages in the loop has no postinst script, then the
4423 cycle will be broken at that package, so as to ensure that
4424 all postinst scripts run with the dependencies properly
4425 configured if this is possible. Otherwise the breaking point
4430 The <tt>Depends</tt> field thus allows package maintainers
4431 to impose an order in which packages should be configured.
4435 The meaning of the five dependency fields is as follows:
4437 <tag><tt>Depends</tt></tag>
4440 This declares an absolute dependency. A package will
4441 not be configured unless all of the packages listed in
4442 its <tt>Depends</tt> field have been correctly
4447 The <tt>Depends</tt> field should be used if the
4448 depended-on package is required for the depending
4449 package to provide a significant amount of
4454 The <tt>Depends</tt> field should also be used if the
4455 <prgn>postinst</prgn>, <prgn>prerm</prgn> or
4456 <prgn>postrm</prgn> scripts require the package to be
4457 present in order to run. Note, however, that the
4458 <prgn>postrm</prgn> cannot rely on any non-essential
4459 packages to be present during the <tt>purge</tt>
4463 <tag><tt>Recommends</tt></tag>
4466 This declares a strong, but not absolute, dependency.
4470 The <tt>Recommends</tt> field should list packages
4471 that would be found together with this one in all but
4472 unusual installations.
4476 <tag><tt>Suggests</tt></tag>
4478 This is used to declare that one package may be more
4479 useful with one or more others. Using this field
4480 tells the packaging system and the user that the
4481 listed packages are related to this one and can
4482 perhaps enhance its usefulness, but that installing
4483 this one without them is perfectly reasonable.
4486 <tag><tt>Enhances</tt></tag>
4488 This field is similar to Suggests but works in the
4489 opposite direction. It is used to declare that a
4490 package can enhance the functionality of another
4494 <tag><tt>Pre-Depends</tt></tag>
4497 This field is like <tt>Depends</tt>, except that it
4498 also forces <prgn>dpkg</prgn> to complete installation
4499 of the packages named before even starting the
4500 installation of the package which declares the
4501 pre-dependency, as follows:
4505 When a package declaring a pre-dependency is about to
4506 be <em>unpacked</em> the pre-dependency can be
4507 satisfied if the depended-on package is either fully
4508 configured, <em>or even if</em> the depended-on
4509 package(s) are only unpacked or in the "Half-Configured"
4510 state, provided that they have been configured
4511 correctly at some point in the past (and not removed
4512 or partially removed since). In this case, both the
4513 previously-configured and currently unpacked or
4514 "Half-Configured" versions must satisfy any version
4515 clause in the <tt>Pre-Depends</tt> field.
4519 When the package declaring a pre-dependency is about
4520 to be <em>configured</em>, the pre-dependency will be
4521 treated as a normal <tt>Depends</tt>, that is, it will
4522 be considered satisfied only if the depended-on
4523 package has been correctly configured.
4527 <tt>Pre-Depends</tt> should be used sparingly,
4528 preferably only by packages whose premature upgrade or
4529 installation would hamper the ability of the system to
4530 continue with any upgrade that might be in progress.
4534 <tt>Pre-Depends</tt> are also required if the
4535 <prgn>preinst</prgn> script depends on the named
4536 package. It is best to avoid this situation if
4544 When selecting which level of dependency to use you should
4545 consider how important the depended-on package is to the
4546 functionality of the one declaring the dependency. Some
4547 packages are composed of components of varying degrees of
4548 importance. Such a package should list using
4549 <tt>Depends</tt> the package(s) which are required by the
4550 more important components. The other components'
4551 requirements may be mentioned as Suggestions or
4552 Recommendations, as appropriate to the components' relative
4558 <heading>Packages which break other packages - <tt>Breaks</tt></heading>
4561 When one binary package declares that it breaks another,
4562 <prgn>dpkg</prgn> will refuse to allow the package which
4563 declares <tt>Breaks</tt> be installed unless the broken
4564 package is deconfigured first, and it will refuse to
4565 allow the broken package to be reconfigured.
4569 A package will not be regarded as causing breakage merely
4570 because its configuration files are still installed; it must
4571 be at least "Half-Installed".
4575 A special exception is made for packages which declare that
4576 they break their own package name or a virtual package which
4577 they provide (see below): this does not count as a real
4582 Normally a <tt>Breaks</tt> entry will have an "earlier than"
4583 version clause; such a <tt>Breaks</tt> is introduced in the
4584 version of an (implicit or explicit) dependency which
4585 violates an assumption or reveals a bug in earlier versions
4586 of the broken package. This use of <tt>Breaks</tt> will
4587 inform higher-level package management tools that broken
4588 package must be upgraded before the new one.
4592 If the breaking package also overwrites some files from the
4593 older package, it should use <tt>Replaces</tt> (not
4594 <tt>Conflicts</tt>) to ensure this goes smoothly.
4598 <sect id="conflicts">
4599 <heading>Conflicting binary packages - <tt>Conflicts</tt></heading>
4602 When one binary package declares a conflict with another
4603 using a <tt>Conflicts</tt> field, <prgn>dpkg</prgn> will
4604 refuse to allow them to be installed on the system at the
4609 If one package is to be installed, the other must be removed
4610 first - if the package being installed is marked as
4611 replacing (see <ref id="replaces">) the one on the system,
4612 or the one on the system is marked as deselected, or both
4613 packages are marked <tt>Essential</tt>, then
4614 <prgn>dpkg</prgn> will automatically remove the package
4615 which is causing the conflict, otherwise it will halt the
4616 installation of the new package with an error. This
4617 mechanism is specifically designed to produce an error when
4618 the installed package is <tt>Essential</tt>, but the new
4623 A package will not cause a conflict merely because its
4624 configuration files are still installed; it must be at least
4629 A special exception is made for packages which declare a
4630 conflict with their own package name, or with a virtual
4631 package which they provide (see below): this does not
4632 prevent their installation, and allows a package to conflict
4633 with others providing a replacement for it. You use this
4634 feature when you want the package in question to be the only
4635 package providing some feature.
4639 A <tt>Conflicts</tt> entry should almost never have an
4640 "earlier than" version clause. This would prevent
4641 <prgn>dpkg</prgn> from upgrading or installing the package
4642 which declared such a conflict until the upgrade or removal
4643 of the conflicted-with package had been completed. Instead,
4644 <tt>Breaks</tt> may be used.
4648 <sect id="virtual"><heading>Virtual packages - <tt>Provides</tt>
4652 As well as the names of actual ("concrete") packages, the
4653 package relationship fields <tt>Depends</tt>,
4654 <tt>Recommends</tt>, <tt>Suggests</tt>, <tt>Enhances</tt>,
4655 <tt>Pre-Depends</tt>, <tt>Breaks</tt>, <tt>Conflicts</tt>,
4656 <tt>Build-Depends</tt>, <tt>Build-Depends-Indep</tt>,
4657 <tt>Build-Conflicts</tt> and <tt>Build-Conflicts-Indep</tt>
4658 may mention "virtual packages".
4662 A <em>virtual package</em> is one which appears in the
4663 <tt>Provides</tt> control file field of another package.
4664 The effect is as if the package(s) which provide a
4665 particular virtual package name had been listed by name
4666 everywhere the virtual package name appears. (See also <ref
4671 If there are both concrete and virtual packages of the same
4672 name, then the dependency may be satisfied (or the conflict
4673 caused) by either the concrete package with the name in
4674 question or any other concrete package which provides the
4675 virtual package with the name in question. This is so that,
4676 for example, supposing we have
4677 <example compact="compact">
4680 </example> and someone else releases an enhanced version of
4681 the <tt>bar</tt> package they can say:
4682 <example compact="compact">
4686 and the <tt>bar-plus</tt> package will now also satisfy the
4687 dependency for the <tt>foo</tt> package.
4691 If a relationship field has a version number attached
4692 then only real packages will be considered to see whether
4693 the relationship is satisfied (or the prohibition violated,
4694 for a conflict or breakage) - it is assumed that a real
4695 package which provides the virtual package is not of the
4696 "right" version. So, a <tt>Provides</tt> field may not
4697 contain version numbers, and the version number of the
4698 concrete package which provides a particular virtual package
4699 will not be looked at when considering a dependency on or
4700 conflict with the virtual package name.
4704 It is likely that the ability will be added in a future
4705 release of <prgn>dpkg</prgn> to specify a version number for
4706 each virtual package it provides. This feature is not yet
4707 present, however, and is expected to be used only
4712 If you want to specify which of a set of real packages
4713 should be the default to satisfy a particular dependency on
4714 a virtual package, you should list the real package as an
4715 alternative before the virtual one.
4720 <sect id="replaces"><heading>Overwriting files and replacing
4721 packages - <tt>Replaces</tt></heading>
4724 Packages can declare in their control file that they should
4725 overwrite files in certain other packages, or completely
4726 replace other packages. The <tt>Replaces</tt> control file
4727 field has these two distinct purposes.
4730 <sect1><heading>Overwriting files in other packages</heading>
4733 Firstly, as mentioned before, it is usually an error for a
4734 package to contain files which are on the system in
4739 However, if the overwriting package declares that it
4740 <tt>Replaces</tt> the one containing the file being
4741 overwritten, then <prgn>dpkg</prgn> will replace the file
4742 from the old package with that from the new. The file
4743 will no longer be listed as "owned" by the old package.
4747 If a package is completely replaced in this way, so that
4748 <prgn>dpkg</prgn> does not know of any files it still
4749 contains, it is considered to have "disappeared". It will
4750 be marked as not wanted on the system (selected for
4751 removal) and not installed. Any <tt>conffile</tt>s
4752 details noted for the package will be ignored, as they
4753 will have been taken over by the overwriting package. The
4754 package's <prgn>postrm</prgn> script will be run with a
4755 special argument to allow the package to do any final
4756 cleanup required. See <ref id="mscriptsinstact">.
4759 Replaces is a one way relationship -- you have to
4760 install the replacing package after the replaced
4767 For this usage of <tt>Replaces</tt>, virtual packages (see
4768 <ref id="virtual">) are not considered when looking at a
4769 <tt>Replaces</tt> field - the packages declared as being
4770 replaced must be mentioned by their real names.
4774 Furthermore, this usage of <tt>Replaces</tt> only takes
4775 effect when both packages are at least partially on the
4776 system at once, so that it can only happen if they do not
4777 conflict or if the conflict has been overridden.
4782 <sect1><heading>Replacing whole packages, forcing their
4786 Secondly, <tt>Replaces</tt> allows the packaging system to
4787 resolve which package should be removed when there is a
4788 conflict - see <ref id="conflicts">. This usage only
4789 takes effect when the two packages <em>do</em> conflict,
4790 so that the two usages of this field do not interfere with
4795 In this situation, the package declared as being replaced
4796 can be a virtual package, so for example, all mail
4797 transport agents (MTAs) would have the following fields in
4798 their control files:
4799 <example compact="compact">
4800 Provides: mail-transport-agent
4801 Conflicts: mail-transport-agent
4802 Replaces: mail-transport-agent
4804 ensuring that only one MTA can be installed at any one
4809 <sect id="sourcebinarydeps">
4810 <heading>Relationships between source and binary packages -
4811 <tt>Build-Depends</tt>, <tt>Build-Depends-Indep</tt>,
4812 <tt>Build-Conflicts</tt>, <tt>Build-Conflicts-Indep</tt>
4816 Source packages that require certain binary packages to be
4817 installed or absent at the time of building the package
4818 can declare relationships to those binary packages.
4822 This is done using the <tt>Build-Depends</tt>,
4823 <tt>Build-Depends-Indep</tt>, <tt>Build-Conflicts</tt> and
4824 <tt>Build-Conflicts-Indep</tt> control file fields.
4828 Build-dependencies on "build-essential" binary packages can be
4829 omitted. Please see <ref id="pkg-relations"> for more information.
4833 The dependencies and conflicts they define must be satisfied
4834 (as defined earlier for binary packages) in order to invoke
4835 the targets in <tt>debian/rules</tt>, as follows:<footnote>
4837 If you make "build-arch" or "binary-arch", you need
4838 Build-Depends. If you make "build-indep" or
4839 "binary-indep", you need Build-Depends and
4840 Build-Depends-Indep. If you make "build" or "binary",
4844 There is no Build-Depends-Arch; this role is essentially
4845 met with Build-Depends. Anyone building the
4846 <tt>build-indep</tt> and binary-indep<tt></tt> targets
4847 is basically assumed to be building the whole package
4848 anyway and so installs all build dependencies. The
4849 autobuilders use <tt>dpkg-buildpackage -B</tt>, which
4850 calls <tt>build</tt> (not <tt>build-arch</tt>, since it
4851 does not yet know how to check for its existence) and
4852 <tt>binary-arch</tt>.
4855 The purpose of the original split, I recall, was so that
4856 the autobuilders wouldn't need to install extra packages
4857 needed only for the binary-indep targets. But without a
4858 build-arch/build-indep split, this didn't work, since
4859 most of the work is done in the build target, not in the
4865 <tag><tt>Build-Depends</tt>, <tt>Build-Conflicts</tt></tag>
4867 The <tt>Build-Depends</tt> and
4868 <tt>Build-Conflicts</tt> fields must be satisfied when
4869 any of the following targets is invoked:
4870 <tt>build</tt>, <tt>clean</tt>, <tt>binary</tt>,
4871 <tt>binary-arch</tt>, <tt>build-arch</tt>,
4872 <tt>build-indep</tt> and <tt>binary-indep</tt>.
4874 <tag><tt>Build-Depends-Indep</tt>,
4875 <tt>Build-Conflicts-Indep</tt></tag>
4877 The <tt>Build-Depends-Indep</tt> and
4878 <tt>Build-Conflicts-Indep</tt> fields must be
4879 satisfied when any of the following targets is
4880 invoked: <tt>build</tt>, <tt>build-indep</tt>,
4881 <tt>binary</tt> and <tt>binary-indep</tt>.
4891 <chapt id="sharedlibs"><heading>Shared libraries</heading>
4894 Packages containing shared libraries must be constructed with
4895 a little care to make sure that the shared library is always
4896 available. This is especially important for packages whose
4897 shared libraries are vitally important, such as the C library
4898 (currently <tt>libc6</tt>).
4902 Packages involving shared libraries should be split up into
4903 several binary packages. This section mostly deals with how
4904 this separation is to be accomplished; rules for files within
4905 the shared library packages are in <ref id="libraries"> instead.
4908 <sect id="sharedlibs-runtime">
4909 <heading>Run-time shared libraries</heading>
4912 The run-time shared library needs to be placed in a package
4913 whose name changes whenever the shared object version
4916 Since it is common place to install several versions of a
4917 package that just provides shared libraries, it is a
4918 good idea that the library package should not
4919 contain any extraneous non-versioned files, unless they
4920 happen to be in versioned directories.</p>
4922 The most common mechanism is to place it in a package
4924 <package><var>libraryname</var><var>soversion</var></package>,
4925 where <file><var>soversion</var></file> is the version number
4926 in the soname of the shared library<footnote>
4927 The soname is the shared object name: it's the thing
4928 that has to match exactly between building an executable
4929 and running it for the dynamic linker to be able run the
4930 program. For example, if the soname of the library is
4931 <file>libfoo.so.6</file>, the library package would be
4932 called <file>libfoo6</file>.
4934 Alternatively, if it would be confusing to directly append
4935 <var>soversion</var> to <var>libraryname</var> (e.g. because
4936 <var>libraryname</var> itself ends in a number), you may use
4937 <package><var>libraryname</var>-<var>soversion</var></package> and
4938 <package><var>libraryname</var>-<var>soversion</var>-dev</package>
4943 If you have several shared libraries built from the same
4944 source tree you may lump them all together into a single
4945 shared library package, provided that you change all of
4946 their sonames at once (so that you don't get filename
4947 clashes if you try to install different versions of the
4948 combined shared libraries package).
4952 The package should install the shared libraries under
4953 their normal names. For example, the <package>libgdbm3</package>
4954 package should install <file>libgdbm.so.3.0.0</file> as
4955 <file>/usr/lib/libgdbm.so.3.0.0</file>. The files should not be
4956 renamed or re-linked by any <prgn>prerm</prgn> or
4957 <prgn>postrm</prgn> scripts; <prgn>dpkg</prgn> will take care
4958 of renaming things safely without affecting running programs,
4959 and attempts to interfere with this are likely to lead to
4964 Shared libraries should not be installed executable, since
4965 the dynamic linker does not require this and trying to
4966 execute a shared library usually results in a core dump.
4970 The run-time library package should include the symbolic link that
4971 <prgn>ldconfig</prgn> would create for the shared libraries.
4972 For example, the <package>libgdbm3</package> package should include
4973 a symbolic link from <file>/usr/lib/libgdbm.so.3</file> to
4974 <file>libgdbm.so.3.0.0</file>. This is needed so that the dynamic
4975 linker (for example <prgn>ld.so</prgn> or
4976 <prgn>ld-linux.so.*</prgn>) can find the library between the
4977 time that <prgn>dpkg</prgn> installs it and the time that
4978 <prgn>ldconfig</prgn> is run in the <prgn>postinst</prgn>
4980 The package management system requires the library to be
4981 placed before the symbolic link pointing to it in the
4982 <file>.deb</file> file. This is so that when
4983 <prgn>dpkg</prgn> comes to install the symlink
4984 (overwriting the previous symlink pointing at an older
4985 version of the library), the new shared library is already
4986 in place. In the past, this was achieved by creating the
4987 library in the temporary packaging directory before
4988 creating the symlink. Unfortunately, this was not always
4989 effective, since the building of the tar file in the
4990 <file>.deb</file> depended on the behavior of the underlying
4991 file system. Some file systems (such as reiserfs) reorder
4992 the files so that the order of creation is forgotten.
4993 Since version 1.7.0, <prgn>dpkg</prgn>
4994 reorders the files itself as necessary when building a
4995 package. Thus it is no longer important to concern
4996 oneself with the order of file creation.
5000 <sect1 id="ldconfig">
5001 <heading><tt>ldconfig</tt></heading>
5004 Any package installing shared libraries in one of the default
5005 library directories of the dynamic linker (which are currently
5006 <file>/usr/lib</file> and <file>/lib</file>) or a directory that is
5007 listed in <file>/etc/ld.so.conf</file><footnote>
5009 <list compact="compact">
5010 <item>/usr/local/lib</item>
5011 <item>/usr/lib/libc5-compat</item>
5012 <item>/lib/libc5-compat</item>
5015 must use <prgn>ldconfig</prgn> to update the shared library
5020 The package maintainer scripts must only call
5021 <prgn>ldconfig</prgn> under these circumstances:
5022 <list compact="compact">
5023 <item>When the <prgn>postinst</prgn> script is run with a
5024 first argument of <tt>configure</tt>, the script must call
5025 <prgn>ldconfig</prgn>, and may optionally invoke
5026 <prgn>ldconfig</prgn> at other times.
5028 <item>When the <prgn>postrm</prgn> script is run with a
5029 first argument of <tt>remove</tt>, the script should call
5030 <prgn>ldconfig</prgn>.
5035 During install or upgrade, the preinst is called before
5036 the new files are installed, so calling "ldconfig" is
5037 pointless. The preinst of an existing package can also be
5038 called if an upgrade fails. However, this happens during
5039 the critical time when a shared libs may exist on-disk
5040 under a temporary name. Thus, it is dangerous and
5041 forbidden by current policy to call "ldconfig" at this
5046 When a package is installed or upgraded, "postinst
5047 configure" runs after the new files are safely on-disk.
5048 Since it is perfectly safe to invoke ldconfig
5049 unconditionally in a postinst, it is OK for a package to
5050 simply put ldconfig in its postinst without checking the
5051 argument. The postinst can also be called to recover from
5052 a failed upgrade. This happens before any new files are
5053 unpacked, so there is no reason to call "ldconfig" at this
5058 For a package that is being removed, prerm is
5059 called with all the files intact, so calling ldconfig is
5060 useless. The other calls to "prerm" happen in the case of
5061 upgrade at a time when all the files of the old package
5062 are on-disk, so again calling "ldconfig" is pointless.
5066 postrm, on the other hand, is called with the "remove"
5067 argument just after the files are removed, so this is
5068 the proper time to call "ldconfig" to notify the system
5069 of the fact that the shared libraries from the package
5070 are removed. The postrm can be called at several other
5071 times. At the time of "postrm purge", "postrm
5072 abort-install", or "postrm abort-upgrade", calling
5073 "ldconfig" is useless because the shared lib files are
5074 not on-disk. However, when "postrm" is invoked with
5075 arguments "upgrade", "failed-upgrade", or "disappear", a
5076 shared lib may exist on-disk under a temporary filename.
5084 <sect id="sharedlibs-support-files">
5085 <heading>Shared library support files</heading>
5088 If your package contains files whose names do not change with
5089 each change in the library shared object version, you must not
5090 put them in the shared library package. Otherwise, several
5091 versions of the shared library cannot be installed at the same
5092 time without filename clashes, making upgrades and transitions
5093 unnecessarily difficult.
5097 It is recommended that supporting files and run-time support
5098 programs that do not need to be invoked manually by users, but
5099 are nevertheless required for the package to function, be placed
5100 (if they are binary) in a subdirectory of <file>/usr/lib</file>,
5101 preferably under <file>/usr/lib/</file><var>package-name</var>.
5102 If the program or file is architecture independent, the
5103 recommendation is for it to be placed in a subdirectory of
5104 <file>/usr/share</file> instead, preferably under
5105 <file>/usr/share/</file><var>package-name</var>. Following the
5106 <var>package-name</var> naming convention ensures that the file
5107 names change when the shared object version changes.
5111 Run-time support programs that use the shared library but are
5112 not required for the library to function or files used by the
5113 shared library that can be used by any version of the shared
5114 library package should instead be put in a separate package.
5115 This package might typically be named
5116 <package><var>libraryname</var>-tools</package>; note the
5117 absence of the <var>soversion</var> in the package name.
5121 Files and support programs only useful when compiling software
5122 against the library should be included in the development
5123 package for the library.<footnote>
5124 For example, a <file><var>package-name</var>-config</file>
5125 script or <package>pkg-config</package> configuration files.
5130 <sect id="sharedlibs-static">
5131 <heading>Static libraries</heading>
5134 The static library (<file><var>libraryname.a</var></file>)
5135 is usually provided in addition to the shared version.
5136 It is placed into the development package (see below).
5140 In some cases, it is acceptable for a library to be
5141 available in static form only; these cases include:
5143 <item>libraries for languages whose shared library support
5144 is immature or unstable</item>
5145 <item>libraries whose interfaces are in flux or under
5146 development (commonly the case when the library's
5147 major version number is zero, or where the ABI breaks
5148 across patchlevels)</item>
5149 <item>libraries which are explicitly intended to be
5150 available only in static form by their upstream
5155 <sect id="sharedlibs-dev">
5156 <heading>Development files</heading>
5159 The development files associated to a shared library need to be
5160 placed in a package called
5161 <package><var>libraryname</var><var>soversion</var>-dev</package>,
5162 or if you prefer only to support one development version at a
5163 time, <package><var>libraryname</var>-dev</package>.
5167 In case several development versions of a library exist, you may
5168 need to use <prgn>dpkg</prgn>'s Conflicts mechanism (see
5169 <ref id="conflicts">) to ensure that the user only installs one
5170 development version at a time (as different development versions are
5171 likely to have the same header files in them, which would cause a
5172 filename clash if both were installed).
5176 The development package should contain a symlink for the associated
5177 shared library without a version number. For example, the
5178 <package>libgdbm-dev</package> package should include a symlink
5179 from <file>/usr/lib/libgdbm.so</file> to
5180 <file>libgdbm.so.3.0.0</file>. This symlink is needed by the linker
5181 (<prgn>ld</prgn>) when compiling packages, as it will only look for
5182 <file>libgdbm.so</file> when compiling dynamically.
5186 <sect id="sharedlibs-intradeps">
5187 <heading>Dependencies between the packages of the same library</heading>
5190 Typically the development version should have an exact
5191 version dependency on the runtime library, to make sure that
5192 compilation and linking happens correctly. The
5193 <tt>${binary:Version}</tt> substitution variable can be
5194 useful for this purpose.
5196 Previously, <tt>${Source-Version}</tt> was used, but its name
5197 was confusing and it has been deprecated since dpkg 1.13.19.
5202 <sect id="sharedlibs-shlibdeps">
5203 <heading>Dependencies between the library and other packages -
5204 the <tt>shlibs</tt> system</heading>
5207 If a package contains a binary or library which links to a
5208 shared library, we must ensure that when the package is
5209 installed on the system, all of the libraries needed are
5210 also installed. This requirement led to the creation of the
5211 <tt>shlibs</tt> system, which is very simple in its design:
5212 any package which <em>provides</em> a shared library also
5213 provides information on the package dependencies required to
5214 ensure the presence of this library, and any package which
5215 <em>uses</em> a shared library uses this information to
5216 determine the dependencies it requires. The files which
5217 contain the mapping from shared libraries to the necessary
5218 dependency information are called <file>shlibs</file> files.
5222 Thus, when a package is built which contains any shared
5223 libraries, it must provide a <file>shlibs</file> file for other
5224 packages to use, and when a package is built which contains
5225 any shared libraries or compiled binaries, it must run
5226 <qref id="pkg-dpkg-shlibdeps"><prgn>dpkg-shlibdeps</prgn></qref>
5227 on these to determine the libraries used and hence the
5228 dependencies needed by this package.<footnote>
5230 In the past, the shared libraries linked to were
5231 determined by calling <prgn>ldd</prgn>, but now
5232 <prgn>objdump</prgn> is used to do this. The only
5233 change this makes to package building is that
5234 <prgn>dpkg-shlibdeps</prgn> must also be run on shared
5235 libraries, whereas in the past this was unnecessary.
5236 The rest of this footnote explains the advantage that
5241 We say that a binary <tt>foo</tt> <em>directly</em> uses
5242 a library <tt>libbar</tt> if it is explicitly linked
5243 with that library (that is, it uses the flag
5244 <tt>-lbar</tt> during the linking stage). Other
5245 libraries that are needed by <tt>libbar</tt> are linked
5246 <em>indirectly</em> to <tt>foo</tt>, and the dynamic
5247 linker will load them automatically when it loads
5248 <tt>libbar</tt>. A package should depend on
5249 the libraries it directly uses, and the dependencies for
5250 those libraries should automatically pull in the other
5255 Unfortunately, the <prgn>ldd</prgn> program shows both
5256 the directly and indirectly used libraries, meaning that
5257 the dependencies determined included both direct and
5258 indirect dependencies. The use of <prgn>objdump</prgn>
5259 avoids this problem by determining only the directly
5264 A good example of where this helps is the following. We
5265 could update <tt>libimlib</tt> with a new version that
5266 supports a new graphics format called dgf (but retaining
5267 the same major version number). If we used the old
5268 <prgn>ldd</prgn> method, every package that uses
5269 <tt>libimlib</tt> would need to be recompiled so it
5270 would also depend on <tt>libdgf</tt> or it wouldn't run
5271 due to missing symbols. However with the new system,
5272 packages using <tt>libimlib</tt> can rely on
5273 <tt>libimlib</tt> itself having the dependency on
5274 <tt>libdgf</tt> and so they would not need rebuilding.
5280 In the following sections, we will first describe where the
5281 various <tt>shlibs</tt> files are to be found, then how to
5282 use <prgn>dpkg-shlibdeps</prgn>, and finally the <tt>shlibs</tt>
5283 file format and how to create them if your package contains a
5288 <heading>The <tt>shlibs</tt> files present on the system</heading>
5291 There are several places where <tt>shlibs</tt> files are
5292 found. The following list gives them in the order in which
5294 <qref id="pkg-dpkg-shlibdeps"><prgn>dpkg-shlibdeps</prgn></qref>.
5295 (The first one which gives the required information is used.)
5301 <p><file>debian/shlibs.local</file></p>
5304 This lists overrides for this package. Its use is
5305 described below (see <ref id="shlibslocal">).
5310 <p><file>/etc/dpkg/shlibs.override</file></p>
5313 This lists global overrides. This list is normally
5314 empty. It is maintained by the local system
5320 <p><file>DEBIAN/shlibs</file> files in the "build directory"</p>
5323 When packages are being built, any
5324 <file>debian/shlibs</file> files are copied into the
5325 control file area of the temporary build directory and
5326 given the name <file>shlibs</file>. These files give
5327 details of any shared libraries included in the
5329 An example may help here. Let us say that the
5330 source package <tt>foo</tt> generates two binary
5331 packages, <tt>libfoo2</tt> and
5332 <tt>foo-runtime</tt>. When building the binary
5333 packages, the two packages are created in the
5334 directories <file>debian/libfoo2</file> and
5335 <file>debian/foo-runtime</file> respectively.
5336 (<file>debian/tmp</file> could be used instead of one
5337 of these.) Since <tt>libfoo2</tt> provides the
5338 <tt>libfoo</tt> shared library, it will require a
5339 <tt>shlibs</tt> file, which will be installed in
5340 <file>debian/libfoo2/DEBIAN/shlibs</file>, eventually
5342 <file>/var/lib/dpkg/info/libfoo2.shlibs</file>. Then
5343 when <prgn>dpkg-shlibdeps</prgn> is run on the
5345 <file>debian/foo-runtime/usr/bin/foo-prog</file>, it
5347 <file>debian/libfoo2/DEBIAN/shlibs</file> file to
5348 determine whether <tt>foo-prog</tt>'s library
5349 dependencies are satisfied by any of the libraries
5350 provided by <tt>libfoo2</tt>. For this reason,
5351 <prgn>dpkg-shlibdeps</prgn> must only be run once
5352 all of the individual binary packages'
5353 <tt>shlibs</tt> files have been installed into the
5360 <p><file>/var/lib/dpkg/info/*.shlibs</file></p>
5363 These are the <file>shlibs</file> files corresponding to
5364 all of the packages installed on the system, and are
5365 maintained by the relevant package maintainers.
5370 <p><file>/etc/dpkg/shlibs.default</file></p>
5373 This file lists any shared libraries whose packages
5374 have failed to provide correct <file>shlibs</file> files.
5375 It was used when the <file>shlibs</file> setup was first
5376 introduced, but it is now normally empty. It is
5377 maintained by the <tt>dpkg</tt> maintainer.
5385 <heading>How to use <prgn>dpkg-shlibdeps</prgn> and the
5386 <file>shlibs</file> files</heading>
5390 <qref id="pkg-dpkg-shlibdeps"><prgn>dpkg-shlibdeps</prgn></qref>
5391 into your <file>debian/rules</file> file. If your package
5392 contains only compiled binaries and libraries (but no scripts),
5393 you can use a command such as:
5394 <example compact="compact">
5395 dpkg-shlibdeps debian/tmp/usr/bin/* debian/tmp/usr/sbin/* \
5396 debian/tmp/usr/lib/*
5398 Otherwise, you will need to explicitly list the compiled
5399 binaries and libraries.<footnote>
5400 If you are using <tt>debhelper</tt>, the
5401 <prgn>dh_shlibdeps</prgn> program will do this work for
5402 you. It will also correctly handle multi-binary
5408 This command puts the dependency information into the
5409 <file>debian/substvars</file> file, which is then used by
5410 <prgn>dpkg-gencontrol</prgn>. You will need to place a
5411 <tt>${shlibs:Depends}</tt> variable in the <tt>Depends</tt>
5412 field in the control file for this to work.
5416 If <prgn>dpkg-shlibdeps</prgn> doesn't complain, you're
5417 done. If it does complain you might need to create your own
5418 <file>debian/shlibs.local</file> file, as explained below (see
5419 <ref id="shlibslocal">).
5423 If you have multiple binary packages, you will need to call
5424 <prgn>dpkg-shlibdeps</prgn> on each one which contains
5425 compiled libraries or binaries. In such a case, you will
5426 need to use the <tt>-T</tt> option to the <tt>dpkg</tt>
5427 utilities to specify a different <file>substvars</file> file.
5431 If you are creating a udeb for use in the Debian Installer,
5432 you will need to specify that <prgn>dpkg-shlibdeps</prgn>
5433 should use the dependency line of type <tt>udeb</tt> by
5434 adding the <tt>-tudeb</tt> option<footnote>
5435 <prgn>dh_shlibdeps</prgn> from the <tt>debhelper</tt> suite
5436 will automatically add this option if it knows it is
5438 </footnote>. If there is no dependency line of type <tt>udeb</tt>
5439 in the <file>shlibs</file> file, <prgn>dpkg-shlibdeps</prgn> will
5440 fall back to the regular dependency line.
5444 For more details on dpkg-shlibdeps, please see
5445 <ref id="pkg-dpkg-shlibdeps"> and
5446 <manref name="dpkg-shlibdeps" section="1">.
5451 <heading>The <file>shlibs</file> File Format</heading>
5454 Each <file>shlibs</file> file has the same format. Lines
5455 beginning with <tt>#</tt> are considered to be comments and
5456 are ignored. Each line is of the form:
5457 <example compact="compact">
5458 [<var>type</var>: ]<var>library-name</var> <var>soname-version</var> <var>dependencies ...</var>
5463 We will explain this by reference to the example of the
5464 <tt>zlib1g</tt> package, which (at the time of writing)
5465 installs the shared library <file>/usr/lib/libz.so.1.1.3</file>.
5469 <var>type</var> is an optional element that indicates the type
5470 of package for which the line is valid. The only type currently
5471 in use is <tt>udeb</tt>. The colon and space after the type are
5476 <var>library-name</var> is the name of the shared library,
5477 in this case <tt>libz</tt>. (This must match the name part
5478 of the soname, see below.)
5482 <var>soname-version</var> is the version part of the soname of
5483 the library. The soname is the thing that must exactly match
5484 for the library to be recognized by the dynamic linker, and is
5486 <tt><var>name</var>.so.<var>major-version</var></tt>, in our
5487 example, <tt>libz.so.1</tt>.<footnote>
5488 This can be determined using the command
5489 <example compact="compact">
5490 objdump -p /usr/lib/libz.so.1.1.3 | grep SONAME
5493 The version part is the part which comes after
5494 <tt>.so.</tt>, so in our case, it is <tt>1</tt>.
5498 <var>dependencies</var> has the same syntax as a dependency
5499 field in a binary package control file. It should give
5500 details of which packages are required to satisfy a binary
5501 built against the version of the library contained in the
5502 package. See <ref id="depsyntax"> for details.
5506 In our example, if the first version of the <tt>zlib1g</tt>
5507 package which contained a minor number of at least
5508 <tt>1.3</tt> was <var>1:1.1.3-1</var>, then the
5509 <tt>shlibs</tt> entry for this library could say:
5510 <example compact="compact">
5511 libz 1 zlib1g (>= 1:1.1.3)
5513 The version-specific dependency is to avoid warnings from
5514 the dynamic linker about using older shared libraries with
5519 As zlib1g also provides a udeb containing the shared library,
5520 there would also be a second line:
5521 <example compact="compact">
5522 udeb: libz 1 zlib1g-udeb (>= 1:1.1.3)
5528 <heading>Providing a <file>shlibs</file> file</heading>
5531 If your package provides a shared library, you need to create
5532 a <file>shlibs</file> file following the format described above.
5533 It is usual to call this file <file>debian/shlibs</file> (but if
5534 you have multiple binary packages, you might want to call it
5535 <file>debian/shlibs.<var>package</var></file> instead). Then
5536 let <file>debian/rules</file> install it in the control area:
5537 <example compact="compact">
5538 install -m644 debian/shlibs debian/tmp/DEBIAN
5540 or, in the case of a multi-binary package:
5541 <example compact="compact">
5542 install -m644 debian/shlibs.<var>package</var> debian/<var>package</var>/DEBIAN/shlibs
5544 An alternative way of doing this is to create the
5545 <file>shlibs</file> file in the control area directly from
5546 <file>debian/rules</file> without using a <file>debian/shlibs</file>
5547 file at all,<footnote>
5548 This is what <prgn>dh_makeshlibs</prgn> in the
5549 <tt>debhelper</tt> suite does. If your package also has a udeb
5550 that provides a shared library, <prgn>dh_makeshlibs</prgn> can
5551 automatically generate the <tt>udeb:</tt> lines if you specify
5552 the name of the udeb with the <tt>--add-udeb</tt> option.
5554 since the <file>debian/shlibs</file> file itself is ignored by
5555 <prgn>dpkg-shlibdeps</prgn>.
5559 As <prgn>dpkg-shlibdeps</prgn> reads the
5560 <file>DEBIAN/shlibs</file> files in all of the binary packages
5561 being built from this source package, all of the
5562 <file>DEBIAN/shlibs</file> files should be installed before
5563 <prgn>dpkg-shlibdeps</prgn> is called on any of the binary
5568 <sect1 id="shlibslocal">
5569 <heading>Writing the <file>debian/shlibs.local</file> file</heading>
5572 This file is intended only as a <em>temporary</em> fix if
5573 your binaries or libraries depend on a library whose package
5574 does not yet provide a correct <file>shlibs</file> file.
5578 We will assume that you are trying to package a binary
5579 <tt>foo</tt>. When you try running
5580 <prgn>dpkg-shlibdeps</prgn> you get the following error
5581 message (<tt>-O</tt> displays the dependency information on
5582 <tt>stdout</tt> instead of writing it to
5583 <tt>debian/substvars</tt>, and the lines have been wrapped
5584 for ease of reading):
5585 <example compact="compact">
5586 $ dpkg-shlibdeps -O debian/tmp/usr/bin/foo
5587 dpkg-shlibdeps: warning: unable to find dependency
5588 information for shared library libbar (soname 1,
5589 path /usr/lib/libbar.so.1, dependency field Depends)
5590 shlibs:Depends=libc6 (>= 2.2.2-2)
5592 You can then run <prgn>ldd</prgn> on the binary to find the
5593 full location of the library concerned:
5594 <example compact="compact">
5596 libbar.so.1 => /usr/lib/libbar.so.1 (0x4001e000)
5597 libc.so.6 => /lib/libc.so.6 (0x40032000)
5598 /lib/ld-linux.so.2 => /lib/ld-linux.so.2 (0x40000000)
5600 So the <prgn>foo</prgn> binary depends on the
5601 <prgn>libbar</prgn> shared library, but no package seems to
5602 provide a <file>*.shlibs</file> file handling
5603 <file>libbar.so.1</file> in <file>/var/lib/dpkg/info/</file>. Let's
5604 determine the package responsible:
5605 <example compact="compact">
5606 $ dpkg -S /usr/lib/libbar.so.1
5607 bar1: /usr/lib/libbar.so.1
5608 $ dpkg -s bar1 | grep Version
5611 This tells us that the <tt>bar1</tt> package, version 1.0-1,
5612 is the one we are using. Now we can file a bug against the
5613 <tt>bar1</tt> package and create our own
5614 <file>debian/shlibs.local</file> to locally fix the problem.
5615 Including the following line into your
5616 <file>debian/shlibs.local</file> file:
5617 <example compact="compact">
5618 libbar 1 bar1 (>= 1.0-1)
5620 should allow the package build to work.
5624 As soon as the maintainer of <tt>bar1</tt> provides a
5625 correct <file>shlibs</file> file, you should remove this line
5626 from your <file>debian/shlibs.local</file> file. (You should
5627 probably also then have a versioned <tt>Build-Depends</tt>
5628 on <tt>bar1</tt> to help ensure that others do not have the
5629 same problem building your package.)
5638 <chapt id="opersys"><heading>The Operating System</heading>
5641 <heading>File system hierarchy</heading>
5645 <heading>File System Structure</heading>
5648 The location of all installed files and directories must
5649 comply with the Filesystem Hierarchy Standard (FHS),
5650 version 2.3, with the exceptions noted below, and except
5651 where doing so would violate other terms of Debian
5652 Policy. The following exceptions to the FHS apply:
5657 The optional rules related to user specific
5658 configuration files for applications are stored in
5659 the user's home directory are relaxed. It is
5660 recommended that such files start with the
5661 '<tt>.</tt>' character (a "dot file"), and if an
5662 application needs to create more than one dot file
5663 then the preferred placement is in a subdirectory
5664 with a name starting with a '.' character, (a "dot
5665 directory"). In this case it is recommended the
5666 configuration files not start with the '.'
5672 The requirement for amd64 to use <file>/lib64</file>
5673 for 64 bit binaries is removed.
5678 The requirement for object files, internal binaries, and
5679 libraries, including <file>libc.so.*</file>, to be located
5680 directly under <file>/lib{,32}</file> and
5681 <file>/usr/lib{,32}</file> is amended, permitting files
5682 to instead be installed to
5683 <file>/lib/<var>triplet</var></file> and
5684 <file>/usr/lib/<var>triplet</var></file>, where
5685 <tt><var>triplet</var></tt> is the value returned by
5686 <tt>dpkg-architecture -qDEB_HOST_GNU_TYPE</tt> for the
5687 architecture of the package. Packages may <em>not</em>
5688 install files to any <var>triplet</var> path other
5689 than the one matching the architecture of that package;
5690 for instance, an <tt>Architecture: amd64</tt> package
5691 containing 32-bit x86 libraries may not install these
5692 libraries to <file>/usr/lib/i486-linux-gnu</file>.
5694 This is necessary in order to reserve the directories for
5695 use in cross-installation of library packages from other
5696 architectures, as part of the planned deployment of
5701 Applications may also use a single subdirectory under
5702 <file>/usr/lib/<var>triplet</var></file>.
5705 The execution time linker/loader, ld*, must still be made
5706 available in the existing location under /lib or /lib64
5707 since this is part of the ELF ABI for the architecture.
5712 The requirement that
5713 <file>/usr/local/share/man</file> be "synonymous"
5714 with <file>/usr/local/man</file> is relaxed to a
5719 The requirement that windowmanagers with a single
5720 configuration file call it <file>system.*wmrc</file>
5721 is removed, as is the restriction that the window
5722 manager subdirectory be named identically to the
5723 window manager name itself.
5728 The requirement that boot manager configuration
5729 files live in <file>/etc</file>, or at least are
5730 symlinked there, is relaxed to a recommendation.
5735 The following directories in the root filesystem are
5736 additionally allowed: <file>/sys</file> and
5737 <file>/selinux</file>. <footnote>These directories
5738 are used as mount points to mount virtual filesystems
5739 to get access to kernel information.</footnote>
5746 The version of this document referred here can be
5747 found in the <tt>debian-policy</tt> package or on <url
5748 id="http://www.debian.org/doc/packaging-manuals/fhs/"
5749 name="FHS (Debian copy)"> alongside this manual (or, if
5750 you have the <package>debian-policy</package> installed,
5752 id="file:///usr/share/doc/debian-policy/fhs/" name="FHS
5753 (local copy)">). The
5754 latest version, which may be a more recent version, may
5756 <url id="http://www.pathname.com/fhs/" name="FHS (upstream)">.
5757 Specific questions about following the standard may be
5758 asked on the <tt>debian-devel</tt> mailing list, or
5759 referred to the FHS mailing list (see the
5760 <url id="http://www.pathname.com/fhs/" name="FHS web site"> for
5766 <heading>Site-specific programs</heading>
5769 As mandated by the FHS, packages must not place any
5770 files in <file>/usr/local</file>, either by putting them in
5771 the file system archive to be unpacked by <prgn>dpkg</prgn>
5772 or by manipulating them in their maintainer scripts.
5776 However, the package may create empty directories below
5777 <file>/usr/local</file> so that the system administrator knows
5778 where to place site-specific files. These are not
5779 directories <em>in</em> <file>/usr/local</file>, but are
5780 children of directories in <file>/usr/local</file>. These
5781 directories (<file>/usr/local/*/dir/</file>)
5782 should be removed on package removal if they are
5787 Note that this applies only to
5788 directories <em>below</em> <file>/usr/local</file>,
5789 not <em>in</em> <file>/usr/local</file>. Packages must
5790 not create sub-directories in the
5791 directory <file>/usr/local</file> itself, except those
5792 listed in FHS, section 4.5. However, you may create
5793 directories below them as you wish. You must not remove
5794 any of the directories listed in 4.5, even if you created
5799 Since <file>/usr/local</file> can be mounted read-only from a
5800 remote server, these directories must be created and
5801 removed by the <prgn>postinst</prgn> and <prgn>prerm</prgn>
5802 maintainer scripts and not be included in the
5803 <file>.deb</file> archive. These scripts must not fail if
5804 either of these operations fail.
5808 For example, the <tt>emacsen-common</tt> package could
5809 contain something like
5810 <example compact="compact">
5811 if [ ! -e /usr/local/share/emacs ]
5813 if mkdir /usr/local/share/emacs 2>/dev/null
5815 chown root:staff /usr/local/share/emacs
5816 chmod 2775 /usr/local/share/emacs
5820 in its <prgn>postinst</prgn> script, and
5821 <example compact="compact">
5822 rmdir /usr/local/share/emacs/site-lisp 2>/dev/null || true
5823 rmdir /usr/local/share/emacs 2>/dev/null || true
5825 in the <prgn>prerm</prgn> script. (Note that this form is
5826 used to ensure that if the script is interrupted, the
5827 directory <file>/usr/local/share/emacs</file> will still be
5832 If you do create a directory in <file>/usr/local</file> for
5833 local additions to a package, you should ensure that
5834 settings in <file>/usr/local</file> take precedence over the
5835 equivalents in <file>/usr</file>.
5839 However, because <file>/usr/local</file> and its contents are
5840 for exclusive use of the local administrator, a package
5841 must not rely on the presence or absence of files or
5842 directories in <file>/usr/local</file> for normal operation.
5846 The <file>/usr/local</file> directory itself and all the
5847 subdirectories created by the package should (by default) have
5848 permissions 2775 (group-writable and set-group-id) and be
5849 owned by <tt>root:staff</tt>.
5854 <heading>The system-wide mail directory</heading>
5856 The system-wide mail directory
5857 is <file>/var/mail</file>. This directory is part of the
5858 base system and should not be owned by any particular mail
5859 agents. The use of the old
5860 location <file>/var/spool/mail</file> is deprecated, even
5861 though the spool may still be physically located there.
5867 <heading>Users and groups</heading>
5870 <heading>Introduction</heading>
5872 The Debian system can be configured to use either plain or
5877 Some user ids (UIDs) and group ids (GIDs) are reserved
5878 globally for use by certain packages. Because some
5879 packages need to include files which are owned by these
5880 users or groups, or need the ids compiled into binaries,
5881 these ids must be used on any Debian system only for the
5882 purpose for which they are allocated. This is a serious
5883 restriction, and we should avoid getting in the way of
5884 local administration policies. In particular, many sites
5885 allocate users and/or local system groups starting at 100.
5889 Apart from this we should have dynamically allocated ids,
5890 which should by default be arranged in some sensible
5891 order, but the behavior should be configurable.
5895 Packages other than <tt>base-passwd</tt> must not modify
5896 <file>/etc/passwd</file>, <file>/etc/shadow</file>,
5897 <file>/etc/group</file> or <file>/etc/gshadow</file>.
5902 <heading>UID and GID classes</heading>
5904 The UID and GID numbers are divided into classes as
5910 Globally allocated by the Debian project, the same
5911 on every Debian system. These ids will appear in
5912 the <file>passwd</file> and <file>group</file> files of all
5913 Debian systems, new ids in this range being added
5914 automatically as the <tt>base-passwd</tt> package is
5919 Packages which need a single statically allocated
5920 uid or gid should use one of these; their
5921 maintainers should ask the <tt>base-passwd</tt>
5929 Dynamically allocated system users and groups.
5930 Packages which need a user or group, but can have
5931 this user or group allocated dynamically and
5932 differently on each system, should use <tt>adduser
5933 --system</tt> to create the group and/or user.
5934 <prgn>adduser</prgn> will check for the existence of
5935 the user or group, and if necessary choose an unused
5936 id based on the ranges specified in
5937 <file>adduser.conf</file>.
5941 <tag>1000-59999:</tag>
5944 Dynamically allocated user accounts. By default
5945 <prgn>adduser</prgn> will choose UIDs and GIDs for
5946 user accounts in this range, though
5947 <file>adduser.conf</file> may be used to modify this
5952 <tag>60000-64999:</tag>
5955 Globally allocated by the Debian project, but only
5956 created on demand. The ids are allocated centrally
5957 and statically, but the actual accounts are only
5958 created on users' systems on demand.
5962 These ids are for packages which are obscure or
5963 which require many statically-allocated ids. These
5964 packages should check for and create the accounts in
5965 <file>/etc/passwd</file> or <file>/etc/group</file> (using
5966 <prgn>adduser</prgn> if it has this facility) if
5967 necessary. Packages which are likely to require
5968 further allocations should have a "hole" left after
5969 them in the allocation, to give them room to
5974 <tag>65000-65533:</tag>
5982 User <tt>nobody</tt>. The corresponding gid refers
5983 to the group <tt>nogroup</tt>.
5990 <tt>(uid_t)(-1) == (gid_t)(-1)</tt> <em>must
5991 not</em> be used, because it is the error return
6000 <sect id="sysvinit">
6001 <heading>System run levels and <file>init.d</file> scripts</heading>
6003 <sect1 id="/etc/init.d">
6004 <heading>Introduction</heading>
6007 The <file>/etc/init.d</file> directory contains the scripts
6008 executed by <prgn>init</prgn> at boot time and when the
6009 init state (or "runlevel") is changed (see <manref
6010 name="init" section="8">).
6014 There are at least two different, yet functionally
6015 equivalent, ways of handling these scripts. For the sake
6016 of simplicity, this document describes only the symbolic
6017 link method. However, it must not be assumed by maintainer
6018 scripts that this method is being used, and any automated
6019 manipulation of the various runlevel behaviors by
6020 maintainer scripts must be performed using
6021 <prgn>update-rc.d</prgn> as described below and not by
6022 manually installing or removing symlinks. For information
6023 on the implementation details of the other method,
6024 implemented in the <tt>file-rc</tt> package, please refer
6025 to the documentation of that package.
6029 These scripts are referenced by symbolic links in the
6030 <file>/etc/rc<var>n</var>.d</file> directories. When changing
6031 runlevels, <prgn>init</prgn> looks in the directory
6032 <file>/etc/rc<var>n</var>.d</file> for the scripts it should
6033 execute, where <tt><var>n</var></tt> is the runlevel that
6034 is being changed to, or <tt>S</tt> for the boot-up
6039 The names of the links all have the form
6040 <file>S<var>mm</var><var>script</var></file> or
6041 <file>K<var>mm</var><var>script</var></file> where
6042 <var>mm</var> is a two-digit number and <var>script</var>
6043 is the name of the script (this should be the same as the
6044 name of the actual script in <file>/etc/init.d</file>).
6048 When <prgn>init</prgn> changes runlevel first the targets
6049 of the links whose names start with a <tt>K</tt> are
6050 executed, each with the single argument <tt>stop</tt>,
6051 followed by the scripts prefixed with an <tt>S</tt>, each
6052 with the single argument <tt>start</tt>. (The links are
6053 those in the <file>/etc/rc<var>n</var>.d</file> directory
6054 corresponding to the new runlevel.) The <tt>K</tt> links
6055 are responsible for killing services and the <tt>S</tt>
6056 link for starting services upon entering the runlevel.
6060 For example, if we are changing from runlevel 2 to
6061 runlevel 3, init will first execute all of the <tt>K</tt>
6062 prefixed scripts it finds in <file>/etc/rc3.d</file>, and then
6063 all of the <tt>S</tt> prefixed scripts in that directory.
6064 The links starting with <tt>K</tt> will cause the
6065 referred-to file to be executed with an argument of
6066 <tt>stop</tt>, and the <tt>S</tt> links with an argument
6071 The two-digit number <var>mm</var> is used to determine
6072 the order in which to run the scripts: low-numbered links
6073 have their scripts run first. For example, the
6074 <tt>K20</tt> scripts will be executed before the
6075 <tt>K30</tt> scripts. This is used when a certain service
6076 must be started before another. For example, the name
6077 server <prgn>bind</prgn> might need to be started before
6078 the news server <prgn>inn</prgn> so that <prgn>inn</prgn>
6079 can set up its access lists. In this case, the script
6080 that starts <prgn>bind</prgn> would have a lower number
6081 than the script that starts <prgn>inn</prgn> so that it
6083 <example compact="compact">
6090 The two runlevels 0 (halt) and 6 (reboot) are slightly
6091 different. In these runlevels, the links with an
6092 <tt>S</tt> prefix are still called after those with a
6093 <tt>K</tt> prefix, but they too are called with the single
6094 argument <tt>stop</tt>.
6098 <sect1 id="writing-init">
6099 <heading>Writing the scripts</heading>
6102 Packages that include daemons for system services should
6103 place scripts in <file>/etc/init.d</file> to start or stop
6104 services at boot time or during a change of runlevel.
6105 These scripts should be named
6106 <file>/etc/init.d/<var>package</var></file>, and they should
6107 accept one argument, saying what to do:
6110 <tag><tt>start</tt></tag>
6111 <item>start the service,</item>
6113 <tag><tt>stop</tt></tag>
6114 <item>stop the service,</item>
6116 <tag><tt>restart</tt></tag>
6117 <item>stop and restart the service if it's already running,
6118 otherwise start the service</item>
6120 <tag><tt>reload</tt></tag>
6121 <item><p>cause the configuration of the service to be
6122 reloaded without actually stopping and restarting
6125 <tag><tt>force-reload</tt></tag>
6126 <item>cause the configuration to be reloaded if the
6127 service supports this, otherwise restart the
6131 The <tt>start</tt>, <tt>stop</tt>, <tt>restart</tt>, and
6132 <tt>force-reload</tt> options should be supported by all
6133 scripts in <file>/etc/init.d</file>, the <tt>reload</tt>
6138 The <file>init.d</file> scripts must ensure that they will
6139 behave sensibly (i.e., returning success and not starting
6140 multiple copies of a service) if invoked with <tt>start</tt>
6141 when the service is already running, or with <tt>stop</tt>
6142 when it isn't, and that they don't kill unfortunately-named
6143 user processes. The best way to achieve this is usually to
6144 use <prgn>start-stop-daemon</prgn> with the <tt>--oknodo</tt>
6149 Be careful of using <tt>set -e</tt> in <file>init.d</file>
6150 scripts. Writing correct <file>init.d</file> scripts requires
6151 accepting various error exit statuses when daemons are already
6152 running or already stopped without aborting
6153 the <file>init.d</file> script, and common <file>init.d</file>
6154 function libraries are not safe to call with <tt>set -e</tt>
6156 <tt>/lib/lsb/init-functions</tt>, which assists in writing
6157 LSB-compliant init scripts, may fail if <tt>set -e</tt> is
6158 in effect and echoing status messages to the console fails,
6160 </footnote>. For <tt>init.d</tt> scripts, it's often easier
6161 to not use <tt>set -e</tt> and instead check the result of
6162 each command separately.
6166 If a service reloads its configuration automatically (as
6167 in the case of <prgn>cron</prgn>, for example), the
6168 <tt>reload</tt> option of the <file>init.d</file> script
6169 should behave as if the configuration has been reloaded
6174 The <file>/etc/init.d</file> scripts must be treated as
6175 configuration files, either (if they are present in the
6176 package, that is, in the .deb file) by marking them as
6177 <tt>conffile</tt>s, or, (if they do not exist in the .deb)
6178 by managing them correctly in the maintainer scripts (see
6179 <ref id="config-files">). This is important since we want
6180 to give the local system administrator the chance to adapt
6181 the scripts to the local system, e.g., to disable a
6182 service without de-installing the package, or to specify
6183 some special command line options when starting a service,
6184 while making sure their changes aren't lost during the next
6189 These scripts should not fail obscurely when the
6190 configuration files remain but the package has been
6191 removed, as configuration files remain on the system after
6192 the package has been removed. Only when <prgn>dpkg</prgn>
6193 is executed with the <tt>--purge</tt> option will
6194 configuration files be removed. In particular, as the
6195 <file>/etc/init.d/<var>package</var></file> script itself is
6196 usually a <tt>conffile</tt>, it will remain on the system
6197 if the package is removed but not purged. Therefore, you
6198 should include a <tt>test</tt> statement at the top of the
6200 <example compact="compact">
6201 test -f <var>program-executed-later-in-script</var> || exit 0
6206 Often there are some variables in the <file>init.d</file>
6207 scripts whose values control the behavior of the scripts,
6208 and which a system administrator is likely to want to
6209 change. As the scripts themselves are frequently
6210 <tt>conffile</tt>s, modifying them requires that the
6211 administrator merge in their changes each time the package
6212 is upgraded and the <tt>conffile</tt> changes. To ease
6213 the burden on the system administrator, such configurable
6214 values should not be placed directly in the script.
6215 Instead, they should be placed in a file in
6216 <file>/etc/default</file>, which typically will have the same
6217 base name as the <file>init.d</file> script. This extra file
6218 should be sourced by the script when the script runs. It
6219 must contain only variable settings and comments in SUSv3
6220 <prgn>sh</prgn> format. It may either be a
6221 <tt>conffile</tt> or a configuration file maintained by
6222 the package maintainer scripts. See <ref id="config-files">
6227 To ensure that vital configurable values are always
6228 available, the <file>init.d</file> script should set default
6229 values for each of the shell variables it uses, either
6230 before sourcing the <file>/etc/default/</file> file or
6231 afterwards using something like the <tt>:
6232 ${VAR:=default}</tt> syntax. Also, the <file>init.d</file>
6233 script must behave sensibly and not fail if the
6234 <file>/etc/default</file> file is deleted.
6238 <file>/var/run</file> and <file>/var/lock</file> may be mounted
6239 as temporary filesystems<footnote>
6240 For example, using the <tt>RAMRUN</tt> and <tt>RAMLOCK</tt>
6241 options in <file>/etc/default/rcS</file>.
6242 </footnote>, so the <file>init.d</file> scripts must handle this
6243 correctly. This will typically amount to creating any required
6244 subdirectories dynamically when the <file>init.d</file> script
6245 is run, rather than including them in the package and relying on
6246 <prgn>dpkg</prgn> to create them.
6251 <heading>Interfacing with the initscript system</heading>
6254 Maintainers should use the abstraction layer provided by
6255 the <prgn>update-rc.d</prgn> and <prgn>invoke-rc.d</prgn>
6256 programs to deal with initscripts in their packages'
6257 scripts such as <prgn>postinst</prgn>, <prgn>prerm</prgn>
6258 and <prgn>postrm</prgn>.
6262 Directly managing the /etc/rc?.d links and directly
6263 invoking the <file>/etc/init.d/</file> initscripts should
6264 be done only by packages providing the initscript
6265 subsystem (such as <prgn>sysv-rc</prgn> and
6266 <prgn>file-rc</prgn>).
6270 <heading>Managing the links</heading>
6273 The program <prgn>update-rc.d</prgn> is provided for
6274 package maintainers to arrange for the proper creation and
6275 removal of <file>/etc/rc<var>n</var>.d</file> symbolic links,
6276 or their functional equivalent if another method is being
6277 used. This may be used by maintainers in their packages'
6278 <prgn>postinst</prgn> and <prgn>postrm</prgn> scripts.
6282 You must not include any <file>/etc/rc<var>n</var>.d</file>
6283 symbolic links in the actual archive or manually create or
6284 remove the symbolic links in maintainer scripts; you must
6285 use the <prgn>update-rc.d</prgn> program instead. (The
6286 former will fail if an alternative method of maintaining
6287 runlevel information is being used.) You must not include
6288 the <file>/etc/rc<var>n</var>.d</file> directories themselves
6289 in the archive either. (Only the <tt>sysvinit</tt>
6294 By default <prgn>update-rc.d</prgn> will start services in
6295 each of the multi-user state runlevels (2, 3, 4, and 5)
6296 and stop them in the halt runlevel (0), the single-user
6297 runlevel (1) and the reboot runlevel (6). The system
6298 administrator will have the opportunity to customize
6299 runlevels by simply adding, moving, or removing the
6300 symbolic links in <file>/etc/rc<var>n</var>.d</file> if
6301 symbolic links are being used, or by modifying
6302 <file>/etc/runlevel.conf</file> if the <tt>file-rc</tt> method
6307 To get the default behavior for your package, put in your
6308 <prgn>postinst</prgn> script
6309 <example compact="compact">
6310 update-rc.d <var>package</var> defaults
6312 and in your <prgn>postrm</prgn>
6313 <example compact="compact">
6314 if [ "$1" = purge ]; then
6315 update-rc.d <var>package</var> remove
6317 </example>. Note that if your package changes runlevels
6318 or priority, you may have to remove and recreate the links,
6319 since otherwise the old links may persist. Refer to the
6320 documentation of <prgn>update-rc.d</prgn>.
6324 This will use a default sequence number of 20. If it does
6325 not matter when or in which order the <file>init.d</file>
6326 script is run, use this default. If it does, then you
6327 should talk to the maintainer of the <prgn>sysvinit</prgn>
6328 package or post to <tt>debian-devel</tt>, and they will
6329 help you choose a number.
6333 For more information about using <tt>update-rc.d</tt>,
6334 please consult its man page <manref name="update-rc.d"
6340 <heading>Running initscripts</heading>
6342 The program <prgn>invoke-rc.d</prgn> is provided to make
6343 it easier for package maintainers to properly invoke an
6344 initscript, obeying runlevel and other locally-defined
6345 constraints that might limit a package's right to start,
6346 stop and otherwise manage services. This program may be
6347 used by maintainers in their packages' scripts.
6351 The package maintainer scripts must use
6352 <prgn>invoke-rc.d</prgn> to invoke the
6353 <file>/etc/init.d/*</file> initscripts, instead of
6354 calling them directly.
6358 By default, <prgn>invoke-rc.d</prgn> will pass any
6359 action requests (start, stop, reload, restart...) to the
6360 <file>/etc/init.d</file> script, filtering out requests
6361 to start or restart a service out of its intended
6366 Most packages will simply need to change:
6367 <example compact="compact">/etc/init.d/<package>
6368 <action></example> in their <prgn>postinst</prgn>
6369 and <prgn>prerm</prgn> scripts to:
6370 <example compact="compact">
6371 if which invoke-rc.d >/dev/null 2>&1; then
6372 invoke-rc.d <var>package</var> <action>
6374 /etc/init.d/<var>package</var> <action>
6380 A package should register its initscript services using
6381 <prgn>update-rc.d</prgn> before it tries to invoke them
6382 using <prgn>invoke-rc.d</prgn>. Invocation of
6383 unregistered services may fail.
6387 For more information about using
6388 <prgn>invoke-rc.d</prgn>, please consult its man page
6389 <manref name="invoke-rc.d" section="8">.
6395 <heading>Boot-time initialization</heading>
6398 There used to be another directory, <file>/etc/rc.boot</file>,
6399 which contained scripts which were run once per machine
6400 boot. This has been deprecated in favour of links from
6401 <file>/etc/rcS.d</file> to files in <file>/etc/init.d</file> as
6402 described in <ref id="/etc/init.d">. Packages must not
6403 place files in <file>/etc/rc.boot</file>.
6408 <heading>Example</heading>
6411 An example on which you can base your
6412 <file>/etc/init.d</file> scripts is found in
6413 <file>/etc/init.d/skeleton</file>.
6420 <heading>Console messages from <file>init.d</file> scripts</heading>
6423 This section describes the formats to be used for messages
6424 written to standard output by the <file>/etc/init.d</file>
6425 scripts. The intent is to improve the consistency of
6426 Debian's startup and shutdown look and feel. For this
6427 reason, please look very carefully at the details. We want
6428 the messages to have the same format in terms of wording,
6429 spaces, punctuation and case of letters.
6433 Here is a list of overall rules that should be used for
6434 messages generated by <file>/etc/init.d</file> scripts.
6440 The message should fit in one line (fewer than 80
6441 characters), start with a capital letter and end with
6442 a period (<tt>.</tt>) and line feed (<tt>"\n"</tt>).
6446 If the script is performing some time consuming task in
6447 the background (not merely starting or stopping a
6448 program, for instance), an ellipsis (three dots:
6449 <tt>...</tt>) should be output to the screen, with no
6450 leading or tailing whitespace or line feeds.
6454 The messages should appear as if the computer is telling
6455 the user what it is doing (politely :-), but should not
6456 mention "it" directly. For example, instead of:
6457 <example compact="compact">
6458 I'm starting network daemons: nfsd mountd.
6460 the message should say
6461 <example compact="compact">
6462 Starting network daemons: nfsd mountd.
6469 <tt>init.d</tt> script should use the following standard
6470 message formats for the situations enumerated below.
6476 <p>When daemons are started</p>
6479 If the script starts one or more daemons, the output
6480 should look like this (a single line, no leading
6482 <example compact="compact">
6483 Starting <var>description</var>: <var>daemon-1</var> ... <var>daemon-n</var>.
6485 The <var>description</var> should describe the
6486 subsystem the daemon or set of daemons are part of,
6487 while <var>daemon-1</var> up to <var>daemon-n</var>
6488 denote each daemon's name (typically the file name of
6493 For example, the output of <file>/etc/init.d/lpd</file>
6495 <example compact="compact">
6496 Starting printer spooler: lpd.
6501 This can be achieved by saying
6502 <example compact="compact">
6503 echo -n "Starting printer spooler: lpd"
6504 start-stop-daemon --start --quiet --exec /usr/sbin/lpd
6507 in the script. If there are more than one daemon to
6508 start, the output should look like this:
6509 <example compact="compact">
6510 echo -n "Starting remote file system services:"
6511 echo -n " nfsd"; start-stop-daemon --start --quiet nfsd
6512 echo -n " mountd"; start-stop-daemon --start --quiet mountd
6513 echo -n " ugidd"; start-stop-daemon --start --quiet ugidd
6516 This makes it possible for the user to see what is
6517 happening and when the final daemon has been started.
6518 Care should be taken in the placement of white spaces:
6519 in the example above the system administrators can
6520 easily comment out a line if they don't want to start
6521 a specific daemon, while the displayed message still
6527 <p>When a system parameter is being set</p>
6530 If you have to set up different system parameters
6531 during the system boot, you should use this format:
6532 <example compact="compact">
6533 Setting <var>parameter</var> to "<var>value</var>".
6538 You can use a statement such as the following to get
6540 <example compact="compact">
6541 echo "Setting DNS domainname to \"$domainname\"."
6546 Note that the same symbol (<tt>"</tt>) <!-- " --> is used
6547 for the left and right quotation marks. A grave accent
6548 (<tt>`</tt>) is not a quote character; neither is an
6549 apostrophe (<tt>'</tt>).
6554 <p>When a daemon is stopped or restarted</p>
6557 When you stop or restart a daemon, you should issue a
6558 message identical to the startup message, except that
6559 <tt>Starting</tt> is replaced with <tt>Stopping</tt>
6560 or <tt>Restarting</tt> respectively.
6564 For example, stopping the printer daemon will look like
6566 <example compact="compact">
6567 Stopping printer spooler: lpd.
6573 <p>When something is executed</p>
6576 There are several examples where you have to run a
6577 program at system startup or shutdown to perform a
6578 specific task, for example, setting the system's clock
6579 using <prgn>netdate</prgn> or killing all processes
6580 when the system shuts down. Your message should look
6582 <example compact="compact">
6583 Doing something very useful...done.
6585 You should print the <tt>done.</tt> immediately after
6586 the job has been completed, so that the user is
6587 informed why they have to wait. You can get this
6589 <example compact="compact">
6590 echo -n "Doing something very useful..."
6599 <p>When the configuration is reloaded</p>
6602 When a daemon is forced to reload its configuration
6603 files you should use the following format:
6604 <example compact="compact">
6605 Reloading <var>description</var> configuration...done.
6607 where <var>description</var> is the same as in the
6608 daemon starting message.
6616 <heading>Cron jobs</heading>
6619 Packages must not modify the configuration file
6620 <file>/etc/crontab</file>, and they must not modify the files in
6621 <file>/var/spool/cron/crontabs</file>.</p>
6624 If a package wants to install a job that has to be executed
6625 via cron, it should place a file with the name of the
6626 package in one or more of the following directories:
6627 <example compact="compact">
6633 As these directory names imply, the files within them are
6634 executed on an hourly, daily, weekly, or monthly basis,
6635 respectively. The exact times are listed in
6636 <file>/etc/crontab</file>.</p>
6639 All files installed in any of these directories must be
6640 scripts (e.g., shell scripts or Perl scripts) so that they
6641 can easily be modified by the local system administrator.
6642 In addition, they must be treated as configuration files.
6646 If a certain job has to be executed at some other frequency or
6647 at a specific time, the package should install a file
6648 <file>/etc/cron.d/<var>package</var></file>. This file uses the
6649 same syntax as <file>/etc/crontab</file> and is processed by
6650 <prgn>cron</prgn> automatically. The file must also be
6651 treated as a configuration file. (Note that entries in the
6652 <file>/etc/cron.d</file> directory are not handled by
6653 <prgn>anacron</prgn>. Thus, you should only use this
6654 directory for jobs which may be skipped if the system is not
6657 Unlike <file>crontab</file> files described in the IEEE Std
6658 1003.1-2008 (POSIX.1) available from
6659 <url id="http://www.opengroup.org/onlinepubs/9699919799/"
6660 name="The Open Group">, the files in
6661 <file>/etc/cron.d</file> and the file
6662 <file>/etc/crontab</file> have seven fields; namely:
6664 <item>Minute [0,59]</item>
6665 <item>Hour [0,23]</item>
6666 <item>Day of the month [1,31]</item>
6667 <item>Month of the year [1,12]</item>
6668 <item>Day of the week ([0,6] with 0=Sunday)</item>
6669 <item>Username</item>
6670 <item>Command to be run</item>
6672 Ranges of numbers are allowed. Ranges are two numbers
6673 separated with a hyphen. The specified range is inclusive.
6674 Lists are allowed. A list is a set of numbers (or ranges)
6675 separated by commas. Step values can be used in conjunction
6680 The scripts or <tt>crontab</tt> entries in these directories should
6681 check if all necessary programs are installed before they
6682 try to execute them. Otherwise, problems will arise when a
6683 package was removed but not purged since configuration files
6684 are kept on the system in this situation.
6688 Any <tt>cron</tt> daemon must provide
6689 <file>/usr/bin/crontab</file> and support normal
6690 <tt>crontab</tt> entries as specified in POSIX. The daemon
6691 must also support names for days and months, ranges, and
6692 step values. It has to support <file>/etc/crontab</file>,
6693 and correctly execute the scripts in
6694 <file>/etc/cron.d</file>. The daemon must also correctly
6696 <file>/etc/cron.{hourly,daily,weekly,monthly}</file>.
6701 <heading>Menus</heading>
6704 The Debian <tt>menu</tt> package provides a standard
6705 interface between packages providing applications and
6706 <em>menu programs</em> (either X window managers or
6707 text-based menu programs such as <prgn>pdmenu</prgn>).
6711 All packages that provide applications that need not be
6712 passed any special command line arguments for normal
6713 operation should register a menu entry for those
6714 applications, so that users of the <tt>menu</tt> package
6715 will automatically get menu entries in their window
6716 managers, as well in shells like <tt>pdmenu</tt>.
6720 Menu entries should follow the current menu policy.
6724 The menu policy can be found in the <tt>menu-policy</tt>
6725 files in the <tt>debian-policy</tt> package.
6726 It is also available from the Debian web mirrors at
6727 <tt><url name="/doc/packaging-manuals/menu-policy/"
6728 id="http://www.debian.org/doc/packaging-manuals/menu-policy/"></tt>.
6732 Please also refer to the <em>Debian Menu System</em>
6733 documentation that comes with the <package>menu</package>
6734 package for information about how to register your
6740 <heading>Multimedia handlers</heading>
6743 MIME (Multipurpose Internet Mail Extensions, RFCs 2045-2049)
6744 is a mechanism for encoding files and data streams and
6745 providing meta-information about them, in particular their
6746 type (e.g. audio or video) and format (e.g. PNG, HTML,
6751 Registration of MIME type handlers allows programs like mail
6752 user agents and web browsers to invoke these handlers to
6753 view, edit or display MIME types they don't support directly.
6757 Packages which provide the ability to view/show/play,
6758 compose, edit or print MIME types should register themselves
6759 as such following the current MIME support policy.
6763 The MIME support policy can be found in the <tt>mime-policy</tt>
6764 files in the <tt>debian-policy</tt> package.
6765 It is also available from the Debian web mirrors at
6766 <tt><url name="/doc/packaging-manuals/mime-policy/"
6767 id="http://www.debian.org/doc/packaging-manuals/mime-policy/"></tt>.
6773 <heading>Keyboard configuration</heading>
6776 To achieve a consistent keyboard configuration so that all
6777 applications interpret a keyboard event the same way, all
6778 programs in the Debian distribution must be configured to
6779 comply with the following guidelines.
6783 The following keys must have the specified interpretations:
6786 <tag><tt><--</tt></tag>
6787 <item>delete the character to the left of the cursor</item>
6789 <tag><tt>Delete</tt></tag>
6790 <item>delete the character to the right of the cursor</item>
6792 <tag><tt>Control+H</tt></tag>
6793 <item>emacs: the help prefix</item>
6796 The interpretation of any keyboard events should be
6797 independent of the terminal that is used, be it a virtual
6798 console, an X terminal emulator, an rlogin/telnet session,
6803 The following list explains how the different programs
6804 should be set up to achieve this:
6810 <tt><--</tt> generates <tt>KB_BackSpace</tt> in X.
6814 <tt>Delete</tt> generates <tt>KB_Delete</tt> in X.
6818 X translations are set up to make
6819 <tt>KB_Backspace</tt> generate ASCII DEL, and to make
6820 <tt>KB_Delete</tt> generate <tt>ESC [ 3 ~</tt> (this
6821 is the vt220 escape code for the "delete character"
6822 key). This must be done by loading the X resources
6823 using <prgn>xrdb</prgn> on all local X displays, not
6824 using the application defaults, so that the
6825 translation resources used correspond to the
6826 <prgn>xmodmap</prgn> settings.
6830 The Linux console is configured to make
6831 <tt><--</tt> generate DEL, and <tt>Delete</tt>
6832 generate <tt>ESC [ 3 ~</tt>.
6836 X applications are configured so that <tt><</tt>
6837 deletes left, and <tt>Delete</tt> deletes right. Motif
6838 applications already work like this.
6842 Terminals should have <tt>stty erase ^?</tt> .
6846 The <tt>xterm</tt> terminfo entry should have <tt>ESC
6847 [ 3 ~</tt> for <tt>kdch1</tt>, just as for
6848 <tt>TERM=linux</tt> and <tt>TERM=vt220</tt>.
6852 Emacs is programmed to map <tt>KB_Backspace</tt> or
6853 the <tt>stty erase</tt> character to
6854 <tt>delete-backward-char</tt>, and <tt>KB_Delete</tt>
6855 or <tt>kdch1</tt> to <tt>delete-forward-char</tt>, and
6856 <tt>^H</tt> to <tt>help</tt> as always.
6860 Other applications use the <tt>stty erase</tt>
6861 character and <tt>kdch1</tt> for the two delete keys,
6862 with ASCII DEL being "delete previous character" and
6863 <tt>kdch1</tt> being "delete character under
6871 This will solve the problem except for the following
6878 Some terminals have a <tt><--</tt> key that cannot
6879 be made to produce anything except <tt>^H</tt>. On
6880 these terminals Emacs help will be unavailable on
6881 <tt>^H</tt> (assuming that the <tt>stty erase</tt>
6882 character takes precedence in Emacs, and has been set
6883 correctly). <tt>M-x help</tt> or <tt>F1</tt> (if
6884 available) can be used instead.
6888 Some operating systems use <tt>^H</tt> for <tt>stty
6889 erase</tt>. However, modern telnet versions and all
6890 rlogin versions propagate <tt>stty</tt> settings, and
6891 almost all UNIX versions honour <tt>stty erase</tt>.
6892 Where the <tt>stty</tt> settings are not propagated
6893 correctly, things can be made to work by using
6894 <tt>stty</tt> manually.
6898 Some systems (including previous Debian versions) use
6899 <prgn>xmodmap</prgn> to arrange for both
6900 <tt><--</tt> and <tt>Delete</tt> to generate
6901 <tt>KB_Delete</tt>. We can change the behavior of
6902 their X clients using the same X resources that we use
6903 to do it for our own clients, or configure our clients
6904 using their resources when things are the other way
6905 around. On displays configured like this
6906 <tt>Delete</tt> will not work, but <tt><--</tt>
6911 Some operating systems have different <tt>kdch1</tt>
6912 settings in their <tt>terminfo</tt> database for
6913 <tt>xterm</tt> and others. On these systems the
6914 <tt>Delete</tt> key will not work correctly when you
6915 log in from a system conforming to our policy, but
6916 <tt><--</tt> will.
6923 <heading>Environment variables</heading>
6926 A program must not depend on environment variables to get
6927 reasonable defaults. (That's because these environment
6928 variables would have to be set in a system-wide
6929 configuration file like <file>/etc/profile</file>, which is not
6930 supported by all shells.)
6934 If a program usually depends on environment variables for its
6935 configuration, the program should be changed to fall back to
6936 a reasonable default configuration if these environment
6937 variables are not present. If this cannot be done easily
6938 (e.g., if the source code of a non-free program is not
6939 available), the program must be replaced by a small
6940 "wrapper" shell script which sets the environment variables
6941 if they are not already defined, and calls the original program.
6945 Here is an example of a wrapper script for this purpose:
6947 <example compact="compact">
6949 BAR=${BAR:-/var/lib/fubar}
6951 exec /usr/lib/foo/foo "$@"
6956 Furthermore, as <file>/etc/profile</file> is a configuration
6957 file of the <prgn>base-files</prgn> package, other packages must
6958 not put any environment variables or other commands into that
6963 <sect id="doc-base">
6964 <heading>Registering Documents using doc-base</heading>
6967 The <package>doc-base</package> package implements a
6968 flexible mechanism for handling and presenting
6969 documentation. The recommended practice is for every Debian
6970 package that provides online documentation (other than just
6971 manual pages) to register these documents with
6972 <package>doc-base</package> by installing a
6973 <package>doc-base</package> control file via the
6974 <prgn/install-docs/ script at installation time and
6975 de-register the manuals again when the package is removed.
6978 Please refer to the documentation that comes with the
6979 <package>doc-base</package> package for information and
6988 <heading>Files</heading>
6991 <heading>Binaries</heading>
6994 Two different packages must not install programs with
6995 different functionality but with the same filenames. (The
6996 case of two programs having the same functionality but
6997 different implementations is handled via "alternatives" or
6998 the "Conflicts" mechanism. See <ref id="maintscripts"> and
6999 <ref id="conflicts"> respectively.) If this case happens,
7000 one of the programs must be renamed. The maintainers should
7001 report this to the <tt>debian-devel</tt> mailing list and
7002 try to find a consensus about which program will have to be
7003 renamed. If a consensus cannot be reached, <em>both</em>
7004 programs must be renamed.
7008 By default, when a package is being built, any binaries
7009 created should include debugging information, as well as
7010 being compiled with optimization. You should also turn on
7011 as many reasonable compilation warnings as possible; this
7012 makes life easier for porters, who can then look at build
7013 logs for possible problems. For the C programming language,
7014 this means the following compilation parameters should be
7016 <example compact="compact">
7018 CFLAGS = -O2 -g -Wall # sane warning options vary between programs
7020 INSTALL = install -s # (or use strip on the files in debian/tmp)
7025 Note that by default all installed binaries should be stripped,
7026 either by using the <tt>-s</tt> flag to
7027 <prgn>install</prgn>, or by calling <prgn>strip</prgn> on
7028 the binaries after they have been copied into
7029 <file>debian/tmp</file> but before the tree is made into a
7034 Although binaries in the build tree should be compiled with
7035 debugging information by default, it can often be difficult to
7036 debug programs if they are also subjected to compiler
7037 optimization. For this reason, it is recommended to support the
7038 standardized environment variable <tt>DEB_BUILD_OPTIONS</tt>
7039 (see <ref id="debianrules-options">). This variable can contain
7040 several flags to change how a package is compiled and built.
7044 It is up to the package maintainer to decide what
7045 compilation options are best for the package. Certain
7046 binaries (such as computationally-intensive programs) will
7047 function better with certain flags (<tt>-O3</tt>, for
7048 example); feel free to use them. Please use good judgment
7049 here. Don't use flags for the sake of it; only use them
7050 if there is good reason to do so. Feel free to override
7051 the upstream author's ideas about which compilation
7052 options are best: they are often inappropriate for our
7058 <sect id="libraries">
7059 <heading>Libraries</heading>
7062 If the package is <strong>architecture: any</strong>, then
7063 the shared library compilation and linking flags must have
7064 <tt>-fPIC</tt>, or the package shall not build on some of
7065 the supported architectures<footnote>
7067 If you are using GCC, <tt>-fPIC</tt> produces code with
7068 relocatable position independent code, which is required for
7069 most architectures to create a shared library, with i386 and
7070 perhaps some others where non position independent code is
7071 permitted in a shared library.
7074 Position independent code may have a performance penalty,
7075 especially on <tt>i386</tt>. However, in most cases the
7076 speed penalty must be measured against the memory wasted on
7077 the few architectures where non position independent code is
7080 </footnote>. Any exception to this rule must be discussed on
7081 the mailing list <em>debian-devel@lists.debian.org</em>, and
7082 a rough consensus obtained. The reasons for not compiling
7083 with <tt>-fPIC</tt> flag must be recorded in the file
7084 <tt>README.Debian</tt>, and care must be taken to either
7085 restrict the architecture or arrange for <tt>-fPIC</tt> to
7086 be used on architectures where it is required.<footnote>
7088 Some of the reasons why this might be required is if the
7089 library contains hand crafted assembly code that is not
7090 relocatable, the speed penalty is excessive for compute
7091 intensive libs, and similar reasons.
7096 As to the static libraries, the common case is not to have
7097 relocatable code, since there is no benefit, unless in specific
7098 cases; therefore the static version must not be compiled
7099 with the <tt>-fPIC</tt> flag. Any exception to this rule
7100 should be discussed on the mailing list
7101 <em>debian-devel@lists.debian.org</em>, and the reasons for
7102 compiling with the <tt>-fPIC</tt> flag must be recorded in
7103 the file <tt>README.Debian</tt>. <footnote>
7105 Some of the reasons for linking static libraries with
7106 the <tt>-fPIC</tt> flag are if, for example, one needs a
7107 Perl API for a library that is under rapid development,
7108 and has an unstable API, so shared libraries are
7109 pointless at this phase of the library's development. In
7110 that case, since Perl needs a library with relocatable
7111 code, it may make sense to create a static library with
7112 relocatable code. Another reason cited is if you are
7113 distilling various libraries into a common shared
7114 library, like <tt>mklibs</tt> does in the Debian
7120 In other words, if both a shared and a static library is
7121 being built, each source unit (<tt>*.c</tt>, for example,
7122 for C files) will need to be compiled twice, for the normal
7126 You must specify the gcc option <tt>-D_REENTRANT</tt>
7127 when building a library (either static or shared) to make
7128 the library compatible with LinuxThreads.
7132 Although not enforced by the build tools, shared libraries
7133 must be linked against all libraries that they use symbols from
7134 in the same way that binaries are. This ensures the correct
7135 functioning of the <qref id="sharedlibs-shlibdeps">shlibs</qref>
7136 system and guarantees that all libraries can be safely opened
7137 with <tt>dlopen()</tt>. Packagers may wish to use the gcc
7138 option <tt>-Wl,-z,defs</tt> when building a shared library.
7139 Since this option enforces symbol resolution at build time,
7140 a missing library reference will be caught early as a fatal
7145 All installed shared libraries should be stripped with
7146 <example compact="compact">
7147 strip --strip-unneeded <var>your-lib</var>
7149 (The option <tt>--strip-unneeded</tt> makes
7150 <prgn>strip</prgn> remove only the symbols which aren't
7151 needed for relocation processing.) Shared libraries can
7152 function perfectly well when stripped, since the symbols for
7153 dynamic linking are in a separate part of the ELF object
7155 You might also want to use the options
7156 <tt>--remove-section=.comment</tt> and
7157 <tt>--remove-section=.note</tt> on both shared libraries
7158 and executables, and <tt>--strip-debug</tt> on static
7164 Note that under some circumstances it may be useful to
7165 install a shared library unstripped, for example when
7166 building a separate package to support debugging.
7170 Shared object files (often <file>.so</file> files) that are not
7171 public libraries, that is, they are not meant to be linked
7172 to by third party executables (binaries of other packages),
7173 should be installed in subdirectories of the
7174 <file>/usr/lib</file> directory. Such files are exempt from the
7175 rules that govern ordinary shared libraries, except that
7176 they must not be installed executable and should be
7178 A common example are the so-called "plug-ins",
7179 internal shared objects that are dynamically loaded by
7180 programs using <manref name="dlopen" section="3">.
7185 An ever increasing number of packages are using
7186 <prgn>libtool</prgn> to do their linking. The latest GNU
7187 libtools (>= 1.3a) can take advantage of the metadata in the
7188 installed <prgn>libtool</prgn> archive files (<file>*.la</file>
7189 files). The main advantage of <prgn>libtool</prgn>'s
7190 <file>.la</file> files is that it allows <prgn>libtool</prgn> to
7191 store and subsequently access metadata with respect to the
7192 libraries it builds. <prgn>libtool</prgn> will search for
7193 those files, which contain a lot of useful information about
7194 a library (such as library dependency information for static
7195 linking). Also, they're <em>essential</em> for programs
7196 using <tt>libltdl</tt>.<footnote>
7197 Although <prgn>libtool</prgn> is fully capable of
7198 linking against shared libraries which don't have
7199 <tt>.la</tt> files, as it is a mere shell script it can
7200 add considerably to the build time of a
7201 <prgn>libtool</prgn>-using package if that shell script
7202 has to derive all this information from first principles
7203 for each library every time it is linked. With the
7204 advent of <prgn>libtool</prgn> version 1.4 (and to a
7205 lesser extent <prgn>libtool</prgn> version 1.3), the
7206 <file>.la</file> files also store information about
7207 inter-library dependencies which cannot necessarily be
7208 derived after the <file>.la</file> file is deleted.
7213 Packages that use <prgn>libtool</prgn> to create shared
7214 libraries should include the <file>.la</file> files in the
7215 <tt>-dev</tt> package, unless the package relies on
7216 <tt>libtool</tt>'s <tt>libltdl</tt> library, in which case
7217 the <tt>.la</tt> files must go in the run-time library
7222 You must make sure that you use only released versions of
7223 shared libraries to build your packages; otherwise other
7224 users will not be able to run your binaries
7225 properly. Producing source packages that depend on
7226 unreleased compilers is also usually a bad
7233 <heading>Shared libraries</heading>
7235 This section has moved to <ref id="sharedlibs">.
7241 <heading>Scripts</heading>
7244 All command scripts, including the package maintainer
7245 scripts inside the package and used by <prgn>dpkg</prgn>,
7246 should have a <tt>#!</tt> line naming the shell to be used
7251 In the case of Perl scripts this should be
7252 <tt>#!/usr/bin/perl</tt>.
7256 When scripts are installed into a directory in the system
7257 PATH, the script name should not include an extension such
7258 as <tt>.sh</tt> or <tt>.pl</tt> that denotes the scripting
7259 language currently used to implement it.
7262 Shell scripts (<prgn>sh</prgn> and <prgn>bash</prgn>) other than
7263 <file>init.d</file> scripts should almost certainly start
7264 with <tt>set -e</tt> so that errors are detected.
7265 <file>init.d</file> scripts are something of a special case, due
7266 to how frequently they need to call commands that are allowed to
7267 fail, and it may instead be easier to check the exit status of
7268 commands directly. See <ref id="writing-init"> for more
7269 information about writing <file>init.d</file> scripts.
7272 Every script should use <tt>set -e</tt> or check the exit status
7273 of <em>every</em> command.
7276 Scripts may assume that <file>/bin/sh</file> implements the
7277 SUSv3 Shell Command Language<footnote>
7278 Single UNIX Specification, version 3, which is also IEEE
7279 1003.1-2004 (POSIX), and is available on the World Wide Web
7280 from <url id="http://www.unix.org/version3/online.html"
7281 name="The Open Group"> after free
7282 registration.</footnote>
7283 plus the following additional features not mandated by
7285 These features are in widespread use in the Linux community
7286 and are implemented in all of bash, dash, and ksh, the most
7287 common shells users may wish to use as <file>/bin/sh</file>.
7290 <item><tt>echo -n</tt>, if implemented as a shell built-in,
7291 must not generate a newline.</item>
7292 <item><tt>test</tt>, if implemented as a shell built-in, must
7293 support <tt>-a</tt> and <tt>-o</tt> as binary logical
7295 <item><tt>local</tt> to create a scoped variable must be
7296 supported, including listing multiple variables in a single
7297 local command and assigning a value to a variable at the
7298 same time as localizing it. <tt>local</tt> may or
7299 may not preserve the variable value from an outer scope if
7300 no assignment is present. Uses such as:
7304 # ... use a, b, c, d ...
7307 must be supported and must set the value of <tt>c</tt> to
7311 If a shell script requires non-SUSv3 features from the shell
7312 interpreter other than those listed above, the appropriate shell
7313 must be specified in the first line of the script (e.g.,
7314 <tt>#!/bin/bash</tt>) and the package must depend on the package
7315 providing the shell (unless the shell package is marked
7316 "Essential", as in the case of <prgn>bash</prgn>).
7320 You may wish to restrict your script to SUSv3 features plus the
7321 above set when possible so that it may use <file>/bin/sh</file>
7322 as its interpreter. If your script works with <prgn>dash</prgn>
7323 (originally called <prgn>ash</prgn>), it probably complies with
7324 the above requirements, but if you are in doubt, use
7325 <file>/bin/bash</file>.
7329 Perl scripts should check for errors when making any
7330 system calls, including <tt>open</tt>, <tt>print</tt>,
7331 <tt>close</tt>, <tt>rename</tt> and <tt>system</tt>.
7335 <prgn>csh</prgn> and <prgn>tcsh</prgn> should be avoided as
7336 scripting languages. See <em>Csh Programming Considered
7337 Harmful</em>, one of the <tt>comp.unix.*</tt> FAQs, which
7338 can be found at <url id="http://www.faqs.org/faqs/unix-faq/shell/csh-whynot/">.
7339 If an upstream package comes with <prgn>csh</prgn> scripts
7340 then you must make sure that they start with
7341 <tt>#!/bin/csh</tt> and make your package depend on the
7342 <prgn>c-shell</prgn> virtual package.
7346 Any scripts which create files in world-writeable
7347 directories (e.g., in <file>/tmp</file>) must use a
7348 mechanism which will fail atomically if a file with the same
7349 name already exists.
7353 The Debian base system provides the <prgn>tempfile</prgn>
7354 and <prgn>mktemp</prgn> utilities for use by scripts for
7361 <heading>Symbolic links</heading>
7364 In general, symbolic links within a top-level directory
7365 should be relative, and symbolic links pointing from one
7366 top-level directory into another should be absolute. (A
7367 top-level directory is a sub-directory of the root
7368 directory <file>/</file>.)
7372 In addition, symbolic links should be specified as short as
7373 possible, i.e., link targets like <file>foo/../bar</file> are
7378 Note that when creating a relative link using
7379 <prgn>ln</prgn> it is not necessary for the target of the
7380 link to exist relative to the working directory you're
7381 running <prgn>ln</prgn> from, nor is it necessary to change
7382 directory to the directory where the link is to be made.
7383 Simply include the string that should appear as the target
7384 of the link (this will be a pathname relative to the
7385 directory in which the link resides) as the first argument
7390 For example, in your <prgn>Makefile</prgn> or
7391 <file>debian/rules</file>, you can do things like:
7392 <example compact="compact">
7393 ln -fs gcc $(prefix)/bin/cc
7394 ln -fs gcc debian/tmp/usr/bin/cc
7395 ln -fs ../sbin/sendmail $(prefix)/bin/runq
7396 ln -fs ../sbin/sendmail debian/tmp/usr/bin/runq
7401 A symbolic link pointing to a compressed file should always
7402 have the same file extension as the referenced file. (For
7403 example, if a file <file>foo.gz</file> is referenced by a
7404 symbolic link, the filename of the link has to end with
7405 "<file>.gz</file>" too, as in <file>bar.gz</file>.)
7410 <heading>Device files</heading>
7413 Packages must not include device files or named pipes in the
7418 If a package needs any special device files that are not
7419 included in the base system, it must call
7420 <prgn>MAKEDEV</prgn> in the <prgn>postinst</prgn> script,
7421 after notifying the user<footnote>
7422 This notification could be done via a (low-priority)
7423 debconf message, or an echo (printf) statement.
7428 Packages must not remove any device files in the
7429 <prgn>postrm</prgn> or any other script. This is left to the
7430 system administrator.
7434 Debian uses the serial devices
7435 <file>/dev/ttyS*</file>. Programs using the old
7436 <file>/dev/cu*</file> devices should be changed to use
7437 <file>/dev/ttyS*</file>.
7441 Named pipes needed by the package must be created in
7442 the <prgn>postinst</prgn> script<footnote>
7443 It's better to use <prgn>mkfifo</prgn> rather
7444 than <prgn>mknod</prgn> to create named pipes so that
7445 automated checks for packages incorrectly creating device
7446 files with <prgn>mknod</prgn> won't have false positives.
7447 </footnote> and removed in
7448 the <prgn>prerm</prgn> or <prgn>postrm</prgn> script as
7453 <sect id="config-files">
7454 <heading>Configuration files</heading>
7457 <heading>Definitions</heading>
7461 <tag>configuration file</tag>
7463 A file that affects the operation of a program, or
7464 provides site- or host-specific information, or
7465 otherwise customizes the behavior of a program.
7466 Typically, configuration files are intended to be
7467 modified by the system administrator (if needed or
7468 desired) to conform to local policy or to provide
7469 more useful site-specific behavior.
7472 <tag><tt>conffile</tt></tag>
7474 A file listed in a package's <tt>conffiles</tt>
7475 file, and is treated specially by <prgn>dpkg</prgn>
7476 (see <ref id="configdetails">).
7482 The distinction between these two is important; they are
7483 not interchangeable concepts. Almost all
7484 <tt>conffile</tt>s are configuration files, but many
7485 configuration files are not <tt>conffiles</tt>.
7489 As noted elsewhere, <file>/etc/init.d</file> scripts,
7490 <file>/etc/default</file> files, scripts installed in
7491 <file>/etc/cron.{hourly,daily,weekly,monthly}</file>, and cron
7492 configuration installed in <file>/etc/cron.d</file> must be
7493 treated as configuration files. In general, any script that
7494 embeds configuration information is de-facto a configuration
7495 file and should be treated as such.
7500 <heading>Location</heading>
7503 Any configuration files created or used by your package
7504 must reside in <file>/etc</file>. If there are several,
7505 consider creating a subdirectory of <file>/etc</file>
7506 named after your package.
7510 If your package creates or uses configuration files
7511 outside of <file>/etc</file>, and it is not feasible to modify
7512 the package to use <file>/etc</file> directly, put the files
7513 in <file>/etc</file> and create symbolic links to those files
7514 from the location that the package requires.
7519 <heading>Behavior</heading>
7522 Configuration file handling must conform to the following
7524 <list compact="compact">
7526 local changes must be preserved during a package
7530 configuration files must be preserved when the
7531 package is removed, and only deleted when the
7538 The easy way to achieve this behavior is to make the
7539 configuration file a <tt>conffile</tt>. This is
7540 appropriate only if it is possible to distribute a default
7541 version that will work for most installations, although
7542 some system administrators may choose to modify it. This
7543 implies that the default version will be part of the
7544 package distribution, and must not be modified by the
7545 maintainer scripts during installation (or at any other
7550 In order to ensure that local changes are preserved
7551 correctly, no package may contain or make hard links to
7552 conffiles.<footnote>
7553 Rationale: There are two problems with hard links.
7554 The first is that some editors break the link while
7555 editing one of the files, so that the two files may
7556 unwittingly become unlinked and different. The second
7557 is that <prgn>dpkg</prgn> might break the hard link
7558 while upgrading <tt>conffile</tt>s.
7563 The other way to do it is via the maintainer scripts. In
7564 this case, the configuration file must not be listed as a
7565 <tt>conffile</tt> and must not be part of the package
7566 distribution. If the existence of a file is required for
7567 the package to be sensibly configured it is the
7568 responsibility of the package maintainer to provide
7569 maintainer scripts which correctly create, update and
7570 maintain the file and remove it on purge. (See <ref
7571 id="maintainerscripts"> for more information.) These
7572 scripts must be idempotent (i.e., must work correctly if
7573 <prgn>dpkg</prgn> needs to re-run them due to errors
7574 during installation or removal), must cope with all the
7575 variety of ways <prgn>dpkg</prgn> can call maintainer
7576 scripts, must not overwrite or otherwise mangle the user's
7577 configuration without asking, must not ask unnecessary
7578 questions (particularly during upgrades), and must
7579 otherwise be good citizens.
7583 The scripts are not required to configure every possible
7584 option for the package, but only those necessary to get
7585 the package running on a given system. Ideally the
7586 sysadmin should not have to do any configuration other
7587 than that done (semi-)automatically by the
7588 <prgn>postinst</prgn> script.
7592 A common practice is to create a script called
7593 <file><var>package</var>-configure</file> and have the
7594 package's <prgn>postinst</prgn> call it if and only if the
7595 configuration file does not already exist. In certain
7596 cases it is useful for there to be an example or template
7597 file which the maintainer scripts use. Such files should
7598 be in <file>/usr/share/<var>package</var></file> or
7599 <file>/usr/lib/<var>package</var></file> (depending on whether
7600 they are architecture-independent or not). There should
7601 be symbolic links to them from
7602 <file>/usr/share/doc/<var>package</var>/examples</file> if
7603 they are examples, and should be perfectly ordinary
7604 <prgn>dpkg</prgn>-handled files (<em>not</em>
7605 configuration files).
7609 These two styles of configuration file handling must
7610 not be mixed, for that way lies madness:
7611 <prgn>dpkg</prgn> will ask about overwriting the file
7612 every time the package is upgraded.
7617 <heading>Sharing configuration files</heading>
7620 Packages which specify the same file as a
7621 <tt>conffile</tt> must be tagged as <em>conflicting</em>
7622 with each other. (This is an instance of the general rule
7623 about not sharing files. Note that neither alternatives
7624 nor diversions are likely to be appropriate in this case;
7625 in particular, <prgn>dpkg</prgn> does not handle diverted
7626 <tt>conffile</tt>s well.)
7630 The maintainer scripts must not alter a <tt>conffile</tt>
7631 of <em>any</em> package, including the one the scripts
7636 If two or more packages use the same configuration file
7637 and it is reasonable for both to be installed at the same
7638 time, one of these packages must be defined as
7639 <em>owner</em> of the configuration file, i.e., it will be
7640 the package which handles that file as a configuration
7641 file. Other packages that use the configuration file must
7642 depend on the owning package if they require the
7643 configuration file to operate. If the other package will
7644 use the configuration file if present, but is capable of
7645 operating without it, no dependency need be declared.
7649 If it is desirable for two or more related packages to
7650 share a configuration file <em>and</em> for all of the
7651 related packages to be able to modify that configuration
7652 file, then the following should be done:
7653 <enumlist compact="compact">
7655 One of the related packages (the "owning" package)
7656 will manage the configuration file with maintainer
7657 scripts as described in the previous section.
7660 The owning package should also provide a program
7661 that the other packages may use to modify the
7665 The related packages must use the provided program
7666 to make any desired modifications to the
7667 configuration file. They should either depend on
7668 the core package to guarantee that the configuration
7669 modifier program is available or accept gracefully
7670 that they cannot modify the configuration file if it
7671 is not. (This is in addition to the fact that the
7672 configuration file may not even be present in the
7679 Sometimes it's appropriate to create a new package which
7680 provides the basic infrastructure for the other packages
7681 and which manages the shared configuration files. (The
7682 <tt>sgml-base</tt> package is a good example.)
7687 <heading>User configuration files ("dotfiles")</heading>
7690 The files in <file>/etc/skel</file> will automatically be
7691 copied into new user accounts by <prgn>adduser</prgn>.
7692 No other program should reference the files in
7693 <file>/etc/skel</file>.
7697 Therefore, if a program needs a dotfile to exist in
7698 advance in <file>$HOME</file> to work sensibly, that dotfile
7699 should be installed in <file>/etc/skel</file> and treated as a
7704 However, programs that require dotfiles in order to
7705 operate sensibly are a bad thing, unless they do create
7706 the dotfiles themselves automatically.
7710 Furthermore, programs should be configured by the Debian
7711 default installation to behave as closely to the upstream
7712 default behavior as possible.
7716 Therefore, if a program in a Debian package needs to be
7717 configured in some way in order to operate sensibly, that
7718 should be done using a site-wide configuration file placed
7719 in <file>/etc</file>. Only if the program doesn't support a
7720 site-wide default configuration and the package maintainer
7721 doesn't have time to add it may a default per-user file be
7722 placed in <file>/etc/skel</file>.
7726 <file>/etc/skel</file> should be as empty as we can make it.
7727 This is particularly true because there is no easy (or
7728 necessarily desirable) mechanism for ensuring that the
7729 appropriate dotfiles are copied into the accounts of
7730 existing users when a package is installed.
7736 <heading>Log files</heading>
7738 Log files should usually be named
7739 <file>/var/log/<var>package</var>.log</file>. If you have many
7740 log files, or need a separate directory for permission
7741 reasons (<file>/var/log</file> is writable only by
7742 <file>root</file>), you should usually create a directory named
7743 <file>/var/log/<var>package</var></file> and place your log
7748 Log files must be rotated occasionally so that they don't
7749 grow indefinitely; the best way to do this is to drop a log
7750 rotation configuration file into the directory
7751 <file>/etc/logrotate.d</file> and use the facilities provided by
7752 logrotate.<footnote>
7754 The traditional approach to log files has been to set up
7755 <em>ad hoc</em> log rotation schemes using simple shell
7756 scripts and cron. While this approach is highly
7757 customizable, it requires quite a lot of sysadmin work.
7758 Even though the original Debian system helped a little
7759 by automatically installing a system which can be used
7760 as a template, this was deemed not enough.
7764 The use of <prgn>logrotate</prgn>, a program developed
7765 by Red Hat, is better, as it centralizes log management.
7766 It has both a configuration file
7767 (<file>/etc/logrotate.conf</file>) and a directory where
7768 packages can drop their individual log rotation
7769 configurations (<file>/etc/logrotate.d</file>).
7772 Here is a good example for a logrotate config
7773 file (for more information see <manref name="logrotate"
7775 <example compact="compact">
7776 /var/log/foo/*.log {
7781 /etc/init.d/foo force-reload
7785 This rotates all files under <file>/var/log/foo</file>, saves 12
7786 compressed generations, and forces the daemon to reload its
7787 configuration information after the log rotation.
7791 Log files should be removed when the package is
7792 purged (but not when it is only removed). This should be
7793 done by the <prgn>postrm</prgn> script when it is called
7794 with the argument <tt>purge</tt> (see <ref
7795 id="removedetails">).
7800 <heading>Permissions and owners</heading>
7803 The rules in this section are guidelines for general use.
7804 If necessary you may deviate from the details below.
7805 However, if you do so you must make sure that what is done
7806 is secure and you should try to be as consistent as possible
7807 with the rest of the system. You should probably also
7808 discuss it on <prgn>debian-devel</prgn> first.
7812 Files should be owned by <tt>root:root</tt>, and made
7813 writable only by the owner and universally readable (and
7814 executable, if appropriate), that is mode 644 or 755.
7818 Directories should be mode 755 or (for group-writability)
7819 mode 2775. The ownership of the directory should be
7820 consistent with its mode: if a directory is mode 2775, it
7821 should be owned by the group that needs write access to
7824 When a package is upgraded, and the owner or permissions
7825 of a file included in the package has changed, dpkg
7826 arranges for the ownership and permissions to be
7827 correctly set upon installation. However, this does not
7828 extend to directories; the permissions and ownership of
7829 directories already on the system does not change on
7830 install or upgrade of packages. This makes sense, since
7831 otherwise common directories like <tt>/usr</tt> would
7832 always be in flux. To correctly change permissions of a
7833 directory the package owns, explicit action is required,
7834 usually in the <tt>postinst</tt> script. Care must be
7835 taken to handle downgrades as well, in that case.
7842 Setuid and setgid executables should be mode 4755 or 2755
7843 respectively, and owned by the appropriate user or group.
7844 They should not be made unreadable (modes like 4711 or
7845 2711 or even 4111); doing so achieves no extra security,
7846 because anyone can find the binary in the freely available
7847 Debian package; it is merely inconvenient. For the same
7848 reason you should not restrict read or execute permissions
7849 on non-set-id executables.
7853 Some setuid programs need to be restricted to particular
7854 sets of users, using file permissions. In this case they
7855 should be owned by the uid to which they are set-id, and by
7856 the group which should be allowed to execute them. They
7857 should have mode 4754; again there is no point in making
7858 them unreadable to those users who must not be allowed to
7863 It is possible to arrange that the system administrator can
7864 reconfigure the package to correspond to their local
7865 security policy by changing the permissions on a binary:
7866 they can do this by using <prgn>dpkg-statoverride</prgn>, as
7867 described below.<footnote>
7868 Ordinary files installed by <prgn>dpkg</prgn> (as
7869 opposed to <tt>conffile</tt>s and other similar objects)
7870 normally have their permissions reset to the distributed
7871 permissions when the package is reinstalled. However,
7872 the use of <prgn>dpkg-statoverride</prgn> overrides this
7875 Another method you should consider is to create a group for
7876 people allowed to use the program(s) and make any setuid
7877 executables executable only by that group.
7881 If you need to create a new user or group for your package
7882 there are two possibilities. Firstly, you may need to
7883 make some files in the binary package be owned by this
7884 user or group, or you may need to compile the user or
7885 group id (rather than just the name) into the binary
7886 (though this latter should be avoided if possible, as in
7887 this case you need a statically allocated id).</p>
7890 If you need a statically allocated id, you must ask for a
7891 user or group id from the <tt>base-passwd</tt> maintainer,
7892 and must not release the package until you have been
7893 allocated one. Once you have been allocated one you must
7894 either make the package depend on a version of the
7895 <tt>base-passwd</tt> package with the id present in
7896 <file>/etc/passwd</file> or <file>/etc/group</file>, or arrange for
7897 your package to create the user or group itself with the
7898 correct id (using <tt>adduser</tt>) in its
7899 <prgn>preinst</prgn> or <prgn>postinst</prgn>. (Doing it in
7900 the <prgn>postinst</prgn> is to be preferred if it is
7901 possible, otherwise a pre-dependency will be needed on the
7902 <tt>adduser</tt> package.)
7906 On the other hand, the program might be able to determine
7907 the uid or gid from the user or group name at runtime, so
7908 that a dynamically allocated id can be used. In this case
7909 you should choose an appropriate user or group name,
7910 discussing this on <prgn>debian-devel</prgn> and checking
7911 with the <package/base-passwd/ maintainer that it is unique and that
7912 they do not wish you to use a statically allocated id
7913 instead. When this has been checked you must arrange for
7914 your package to create the user or group if necessary using
7915 <prgn>adduser</prgn> in the <prgn>preinst</prgn> or
7916 <prgn>postinst</prgn> script (again, the latter is to be
7917 preferred if it is possible).
7921 Note that changing the numeric value of an id associated
7922 with a name is very difficult, and involves searching the
7923 file system for all appropriate files. You need to think
7924 carefully whether a static or dynamic id is required, since
7925 changing your mind later will cause problems.
7928 <sect1><heading>The use of <prgn>dpkg-statoverride</prgn></heading>
7930 This section is not intended as policy, but as a
7931 description of the use of <prgn>dpkg-statoverride</prgn>.
7935 If a system administrator wishes to have a file (or
7936 directory or other such thing) installed with owner and
7937 permissions different from those in the distributed Debian
7938 package, they can use the <prgn>dpkg-statoverride</prgn>
7939 program to instruct <prgn>dpkg</prgn> to use the different
7940 settings every time the file is installed. Thus the
7941 package maintainer should distribute the files with their
7942 normal permissions, and leave it for the system
7943 administrator to make any desired changes. For example, a
7944 daemon which is normally required to be setuid root, but
7945 in certain situations could be used without being setuid,
7946 should be installed setuid in the <tt>.deb</tt>. Then the
7947 local system administrator can change this if they wish.
7948 If there are two standard ways of doing it, the package
7949 maintainer can use <tt>debconf</tt> to find out the
7950 preference, and call <prgn>dpkg-statoverride</prgn> in the
7951 maintainer script if necessary to accommodate the system
7952 administrator's choice. Care must be taken during
7953 upgrades to not override an existing setting.
7957 Given the above, <prgn>dpkg-statoverride</prgn> is
7958 essentially a tool for system administrators and would not
7959 normally be needed in the maintainer scripts. There is
7960 one type of situation, though, where calls to
7961 <prgn>dpkg-statoverride</prgn> would be needed in the
7962 maintainer scripts, and that involves packages which use
7963 dynamically allocated user or group ids. In such a
7964 situation, something like the following idiom can be very
7965 helpful in the package's <prgn>postinst</prgn>, where
7966 <tt>sysuser</tt> is a dynamically allocated id:
7968 for i in /usr/bin/foo /usr/sbin/bar
7970 # only do something when no setting exists
7971 if ! dpkg-statoverride --list $i >/dev/null 2>&1
7973 #include: debconf processing, question about foo and bar
7974 if [ "$RET" = "true" ] ; then
7975 dpkg-statoverride --update --add sysuser root 4755 $i
7980 The corresponding code to remove the override when the package
7983 for i in /usr/bin/foo /usr/sbin/bar
7985 if dpkg-statoverride --list $i >/dev/null 2>&1
7987 dpkg-statoverride --remove $i
7997 <chapt id="customized-programs">
7998 <heading>Customized programs</heading>
8000 <sect id="arch-spec">
8001 <heading>Architecture specification strings</heading>
8004 If a program needs to specify an <em>architecture specification
8005 string</em> in some place, it should select one of the strings
8006 provided by <tt>dpkg-architecture -L</tt>. The strings are in
8007 the format <tt><var>os</var>-<var>arch</var></tt>, though the OS
8008 part is sometimes elided, as when the OS is Linux.
8012 Note that we don't want to use
8013 <tt><var>arch</var>-debian-linux</tt> to apply to the rule
8014 <tt><var>architecture</var>-<var>vendor</var>-<var>os</var></tt>
8015 since this would make our programs incompatible with other
8016 Linux distributions. We also don't use something like
8017 <tt><var>arch</var>-unknown-linux</tt>, since the
8018 <tt>unknown</tt> does not look very good.
8021 <sect1 id="arch-wildcard-spec">
8022 <heading>Architecture wildcards</heading>
8025 A package may specify an architecture wildcard. Architecture
8026 wildcards are in the format <tt>any</tt> (which matches every
8027 architecture), <tt><var>os</var></tt>-any, or
8028 any-<tt><var>cpu</var></tt>. <footnote>
8029 Internally, the package system normalizes the GNU triplets
8030 and the Debian arches into Debian arch triplets (which are
8031 kind of inverted GNU triplets), with the first component of
8032 the triplet representing the libc and ABI in use, and then
8033 does matching against those triplets. However, such
8034 triplets are an internal implementation detail that should
8035 not be used by packages directly. The libc and ABI portion
8036 is handled internally by the package system based on
8037 the <var>os</var> and <var>cpu</var>.
8044 <heading>Daemons</heading>
8047 The configuration files <file>/etc/services</file>,
8048 <file>/etc/protocols</file>, and <file>/etc/rpc</file> are managed
8049 by the <prgn>netbase</prgn> package and must not be modified
8054 If a package requires a new entry in one of these files, the
8055 maintainer should get in contact with the
8056 <prgn>netbase</prgn> maintainer, who will add the entries
8057 and release a new version of the <prgn>netbase</prgn>
8062 The configuration file <file>/etc/inetd.conf</file> must not be
8063 modified by the package's scripts except via the
8064 <prgn>update-inetd</prgn> script or the
8065 <file>DebianNet.pm</file> Perl module. See their documentation
8066 for details on how to add entries.
8070 If a package wants to install an example entry into
8071 <file>/etc/inetd.conf</file>, the entry must be preceded with
8072 exactly one hash character (<tt>#</tt>). Such lines are
8073 treated as "commented out by user" by the
8074 <prgn>update-inetd</prgn> script and are not changed or
8075 activated during package updates.
8080 <heading>Using pseudo-ttys and modifying wtmp, utmp and
8084 Some programs need to create pseudo-ttys. This should be done
8085 using Unix98 ptys if the C library supports it. The resulting
8086 program must not be installed setuid root, unless that
8087 is required for other functionality.
8091 The files <file>/var/run/utmp</file>, <file>/var/log/wtmp</file> and
8092 <file>/var/log/lastlog</file> must be installed writable by
8093 group <tt>utmp</tt>. Programs which need to modify those
8094 files must be installed setgid <tt>utmp</tt>.
8099 <heading>Editors and pagers</heading>
8102 Some programs have the ability to launch an editor or pager
8103 program to edit or display a text document. Since there are
8104 lots of different editors and pagers available in the Debian
8105 distribution, the system administrator and each user should
8106 have the possibility to choose their preferred editor and
8111 In addition, every program should choose a good default
8112 editor/pager if none is selected by the user or system
8117 Thus, every program that launches an editor or pager must
8118 use the EDITOR or PAGER environment variable to determine
8119 the editor or pager the user wishes to use. If these
8120 variables are not set, the programs <file>/usr/bin/editor</file>
8121 and <file>/usr/bin/pager</file> should be used, respectively.
8125 These two files are managed through the <prgn>dpkg</prgn>
8126 "alternatives" mechanism. Thus every package providing an
8127 editor or pager must call the
8128 <prgn>update-alternatives</prgn> script to register these
8133 If it is very hard to adapt a program to make use of the
8134 EDITOR or PAGER variables, that program may be configured to
8135 use <file>/usr/bin/sensible-editor</file> and
8136 <file>/usr/bin/sensible-pager</file> as the editor or pager
8137 program respectively. These are two scripts provided in the
8138 <package>sensible-utils</package> package that check the EDITOR
8139 and PAGER variables and launch the appropriate program, and fall
8140 back to <file>/usr/bin/editor</file>
8141 and <file>/usr/bin/pager</file> if the variable is not set.
8145 A program may also use the VISUAL environment variable to
8146 determine the user's choice of editor. If it exists, it
8147 should take precedence over EDITOR. This is in fact what
8148 <file>/usr/bin/sensible-editor</file> does.
8152 It is not required for a package to depend on
8153 <tt>editor</tt> and <tt>pager</tt>, nor is it required for a
8154 package to provide such virtual packages.<footnote>
8155 The Debian base system already provides an editor and a
8161 <sect id="web-appl">
8162 <heading>Web servers and applications</heading>
8165 This section describes the locations and URLs that should
8166 be used by all web servers and web applications in the
8173 Cgi-bin executable files are installed in the
8175 <example compact="compact">
8176 /usr/lib/cgi-bin/<var>cgi-bin-name</var>
8178 and should be referred to as
8179 <example compact="compact">
8180 http://localhost/cgi-bin/<var>cgi-bin-name</var>
8186 <p>Access to HTML documents</p>
8189 HTML documents for a package are stored in
8190 <file>/usr/share/doc/<var>package</var></file>
8191 and can be referred to as
8192 <example compact="compact">
8193 http://localhost/doc/<var>package</var>/<var>filename</var>
8198 The web server should restrict access to the document
8199 tree so that only clients on the same host can read
8200 the documents. If the web server does not support such
8201 access controls, then it should not provide access at
8202 all, or ask about providing access during installation.
8207 <p>Access to images</p>
8209 It is recommended that images for a package be stored
8210 in <tt>/usr/share/images/<var>package</var></tt> and
8211 may be referred to through an alias <tt>/images/</tt>
8214 http://localhost/images/<package>/<filename>
8221 <p>Web Document Root</p>
8224 Web Applications should try to avoid storing files in
8225 the Web Document Root. Instead they should use the
8226 /usr/share/doc/<var>package</var> directory for
8227 documents and register the Web Application via the
8228 <package>doc-base</package> package. If access to the
8229 web document root is unavoidable then use
8230 <example compact="compact">
8233 as the Document Root. This might be just a symbolic
8234 link to the location where the system administrator
8235 has put the real document root.
8238 <item><p>Providing httpd and/or httpd-cgi</p>
8240 All web servers should provide the virtual package
8241 <tt>httpd</tt>. If a web server has CGI support it should
8242 provide <tt>httpd-cgi</tt> additionally.
8245 All web applications which do not contain CGI scripts should
8246 depend on <tt>httpd</tt>, all those web applications which
8247 <tt>do</tt> contain CGI scripts, should depend on
8255 <sect id="mail-transport-agents">
8256 <heading>Mail transport, delivery and user agents</heading>
8259 Debian packages which process electronic mail, whether mail
8260 user agents (MUAs) or mail transport agents (MTAs), must
8261 ensure that they are compatible with the configuration
8262 decisions below. Failure to do this may result in lost
8263 mail, broken <tt>From:</tt> lines, and other serious brain
8268 The mail spool is <file>/var/mail</file> and the interface to
8269 send a mail message is <file>/usr/sbin/sendmail</file> (as per
8270 the FHS). On older systems, the mail spool may be
8271 physically located in <file>/var/spool/mail</file>, but all
8272 access to the mail spool should be via the
8273 <file>/var/mail</file> symlink. The mail spool is part of the
8274 base system and not part of the MTA package.
8278 All Debian MUAs, MTAs, MDAs and other mailbox accessing
8279 programs (such as IMAP daemons) must lock the mailbox in an
8280 NFS-safe way. This means that <tt>fcntl()</tt> locking must
8281 be combined with dot locking. To avoid deadlocks, a program
8282 should use <tt>fcntl()</tt> first and dot locking after
8283 this, or alternatively implement the two locking methods in
8284 a non blocking way<footnote>
8285 If it is not possible to establish both locks, the
8286 system shouldn't wait for the second lock to be
8287 established, but remove the first lock, wait a (random)
8288 time, and start over locking again.
8289 </footnote>. Using the functions <tt>maillock</tt> and
8290 <tt>mailunlock</tt> provided by the
8291 <tt>liblockfile*</tt><footnote>
8292 You will need to depend on <tt>liblockfile1 (>>1.01)</tt>
8293 to use these functions.
8294 </footnote> packages is the recommended way to realize this.
8298 Mailboxes are generally either mode 600 and owned by
8299 <var>user</var> or mode 660 and owned by
8300 <tt><var>user</var>:mail</tt><footnote>
8301 There are two traditional permission schemes for mail spools:
8302 mode 600 with all mail delivery done by processes running as
8303 the destination user, or mode 660 and owned by group mail with
8304 mail delivery done by a process running as a system user in
8305 group mail. Historically, Debian required mode 660 mail
8306 spools to enable the latter model, but that model has become
8307 increasingly uncommon and the principle of least privilege
8308 indicates that mail systems that use the first model should
8309 use permissions of 600. If delivery to programs is permitted,
8310 it's easier to keep the mail system secure if the delivery
8311 agent runs as the destination user. Debian Policy therefore
8312 permits either scheme.
8313 </footnote>. The local system administrator may choose a
8314 different permission scheme; packages should not make
8315 assumptions about the permission and ownership of mailboxes
8316 unless required (such as when creating a new mailbox). A MUA
8317 may remove a mailbox (unless it has nonstandard permissions) in
8318 which case the MTA or another MUA must recreate it if needed.
8322 The mail spool is 2775 <tt>root:mail</tt>, and MUAs should
8323 be setgid mail to do the locking mentioned above (and
8324 must obviously avoid accessing other users' mailboxes
8325 using this privilege).</p>
8328 <file>/etc/aliases</file> is the source file for the system mail
8329 aliases (e.g., postmaster, usenet, etc.), it is the one
8330 which the sysadmin and <prgn>postinst</prgn> scripts may
8331 edit. After <file>/etc/aliases</file> is edited the program or
8332 human editing it must call <prgn>newaliases</prgn>. All MTA
8333 packages must come with a <prgn>newaliases</prgn> program,
8334 even if it does nothing, but older MTA packages did not do
8335 this so programs should not fail if <prgn>newaliases</prgn>
8336 cannot be found. Note that because of this, all MTA
8337 packages must have <tt>Provides</tt>, <tt>Conflicts</tt> and
8338 <tt>Replaces: mail-transport-agent</tt> control file
8343 The convention of writing <tt>forward to
8344 <var>address</var></tt> in the mailbox itself is not
8345 supported. Use a <tt>.forward</tt> file instead.</p>
8348 The <prgn>rmail</prgn> program used by UUCP
8349 for incoming mail should be <file>/usr/sbin/rmail</file>.
8350 Likewise, <prgn>rsmtp</prgn>, for receiving
8351 batch-SMTP-over-UUCP, should be <file>/usr/sbin/rsmtp</file> if it
8355 If your package needs to know what hostname to use on (for
8356 example) outgoing news and mail messages which are generated
8357 locally, you should use the file <file>/etc/mailname</file>. It
8358 will contain the portion after the username and <tt>@</tt>
8359 (at) sign for email addresses of users on the machine
8360 (followed by a newline).
8364 Such a package should check for the existence of this file
8365 when it is being configured. If it exists, it should be
8366 used without comment, although an MTA's configuration script
8367 may wish to prompt the user even if it finds that this file
8368 exists. If the file does not exist, the package should
8369 prompt the user for the value (preferably using
8370 <prgn>debconf</prgn>) and store it in <file>/etc/mailname</file>
8371 as well as using it in the package's configuration. The
8372 prompt should make it clear that the name will not just be
8373 used by that package. For example, in this situation the
8374 <tt>inn</tt> package could say something like:
8375 <example compact="compact">
8376 Please enter the "mail name" of your system. This is the
8377 hostname portion of the address to be shown on outgoing
8378 news and mail messages. The default is
8379 <var>syshostname</var>, your system's host name. Mail
8380 name ["<var>syshostname</var>"]:
8382 where <var>syshostname</var> is the output of <tt>hostname
8388 <heading>News system configuration</heading>
8391 All the configuration files related to the NNTP (news)
8392 servers and clients should be located under
8393 <file>/etc/news</file>.</p>
8396 There are some configuration issues that apply to a number
8397 of news clients and server packages on the machine. These
8401 <tag><file>/etc/news/organization</file></tag>
8403 A string which should appear as the
8404 organization header for all messages posted
8405 by NNTP clients on the machine
8408 <tag><file>/etc/news/server</file></tag>
8410 Contains the FQDN of the upstream NNTP
8411 server, or localhost if the local machine is
8416 Other global files may be added as required for cross-package news
8423 <heading>Programs for the X Window System</heading>
8426 <heading>Providing X support and package priorities</heading>
8429 Programs that can be configured with support for the X
8430 Window System must be configured to do so and must declare
8431 any package dependencies necessary to satisfy their
8432 runtime requirements when using the X Window System. If
8433 such a package is of higher priority than the X packages
8434 on which it depends, it is required that either the
8435 X-specific components be split into a separate package, or
8436 that an alternative version of the package, which includes
8437 X support, be provided, or that the package's priority be
8443 <heading>Packages providing an X server</heading>
8446 Packages that provide an X server that, directly or
8447 indirectly, communicates with real input and display
8448 hardware should declare in their control data that they
8449 provide the virtual package <tt>xserver</tt>.<footnote>
8450 This implements current practice, and provides an
8451 actual policy for usage of the <tt>xserver</tt>
8452 virtual package which appears in the virtual packages
8453 list. In a nutshell, X servers that interface
8454 directly with the display and input hardware or via
8455 another subsystem (e.g., GGI) should provide
8456 <tt>xserver</tt>. Things like <tt>Xvfb</tt>,
8457 <tt>Xnest</tt>, and <tt>Xprt</tt> should not.
8463 <heading>Packages providing a terminal emulator</heading>
8466 Packages that provide a terminal emulator for the X Window
8467 System which meet the criteria listed below should declare
8468 in their control data that they provide the virtual
8469 package <tt>x-terminal-emulator</tt>. They should also
8470 register themselves as an alternative for
8471 <file>/usr/bin/x-terminal-emulator</file>, with a priority of
8476 To be an <tt>x-terminal-emulator</tt>, a program must:
8477 <list compact="compact">
8479 Be able to emulate a DEC VT100 terminal, or a
8480 compatible terminal.
8484 Support the command-line option <tt>-e
8485 <var>command</var></tt>, which creates a new
8486 terminal window<footnote>
8487 "New terminal window" does not necessarily mean
8488 a new top-level X window directly parented by
8489 the window manager; it could, if the terminal
8490 emulator application were so coded, be a new
8491 "view" in a multiple-document interface (MDI).
8493 and runs the specified <var>command</var>,
8494 interpreting the entirety of the rest of the command
8495 line as a command to pass straight to exec, in the
8496 manner that <tt>xterm</tt> does.
8500 Support the command-line option <tt>-T
8501 <var>title</var></tt>, which creates a new terminal
8502 window with the window title <var>title</var>.
8509 <heading>Packages providing a window manager</heading>
8512 Packages that provide a window manager should declare in
8513 their control data that they provide the virtual package
8514 <tt>x-window-manager</tt>. They should also register
8515 themselves as an alternative for
8516 <file>/usr/bin/x-window-manager</file>, with a priority
8517 calculated as follows:
8518 <list compact="compact">
8520 Start with a priority of 20.
8524 If the window manager supports the Debian menu
8525 system, add 20 points if this support is available
8526 in the package's default configuration (i.e., no
8527 configuration files belonging to the system or user
8528 have to be edited to activate the feature); if
8529 configuration files must be modified, add only 10
8535 If the window manager complies with <url
8536 id="http://www.freedesktop.org/Standards/wm-spec"
8537 name="The Window Manager Specification Project">,
8538 written by the <url id="http://www.freedesktop.org/"
8539 name="Free Desktop Group">, add 40 points.
8543 If the window manager permits the X session to be
8544 restarted using a <em>different</em> window manager
8545 (without killing the X server) in its default
8546 configuration, add 10 points; otherwise add none.
8553 <heading>Packages providing fonts</heading>
8556 Packages that provide fonts for the X Window
8558 For the purposes of Debian Policy, a "font for the X
8559 Window System" is one which is accessed via X protocol
8560 requests. Fonts for the Linux console, for PostScript
8561 renderer, or any other purpose, do not fit this
8562 definition. Any tool which makes such fonts available
8563 to the X Window System, however, must abide by this
8566 must do a number of things to ensure that they are both
8567 available without modification of the X or font server
8568 configuration, and that they do not corrupt files used by
8569 other font packages to register information about
8573 Fonts of any type supported by the X Window System
8574 must be in a separate binary package from any
8575 executables, libraries, or documentation (except
8576 that specific to the fonts shipped, such as their
8577 license information). If one or more of the fonts
8578 so packaged are necessary for proper operation of
8579 the package with which they are associated the font
8580 package may be Recommended; if the fonts merely
8581 provide an enhancement, a Suggests relationship may
8582 be used. Packages must not Depend on font
8584 This is because the X server may retrieve fonts
8585 from the local file system or over the network
8586 from an X font server; the Debian package system
8587 is empowered to deal only with the local
8593 BDF fonts must be converted to PCF fonts with the
8594 <prgn>bdftopcf</prgn> utility (available in the
8595 <tt>xfonts-utils</tt> package, <prgn>gzip</prgn>ped, and
8596 placed in a directory that corresponds to their
8598 <list compact="compact">
8600 100 dpi fonts must be placed in
8601 <file>/usr/share/fonts/X11/100dpi/</file>.
8605 75 dpi fonts must be placed in
8606 <file>/usr/share/fonts/X11/75dpi/</file>.
8610 Character-cell fonts, cursor fonts, and other
8611 low-resolution fonts must be placed in
8612 <file>/usr/share/fonts/X11/misc/</file>.
8618 Type 1 fonts must be placed in
8619 <file>/usr/share/fonts/X11/Type1/</file>. If font
8620 metric files are available, they must be placed here
8625 Subdirectories of <file>/usr/share/fonts/X11/</file>
8626 other than those listed above must be neither
8627 created nor used. (The <file>PEX</file>, <file>CID</file>,
8628 <file>Speedo</file>, and <file>cyrillic</file> directories
8629 are excepted for historical reasons, but installation of
8630 files into these directories remains discouraged.)
8634 Font packages may, instead of placing files directly
8635 in the X font directories listed above, provide
8636 symbolic links in that font directory pointing to
8637 the files' actual location in the filesystem. Such
8638 a location must comply with the FHS.
8642 Font packages should not contain both 75dpi and
8643 100dpi versions of a font. If both are available,
8644 they should be provided in separate binary packages
8645 with <tt>-75dpi</tt> or <tt>-100dpi</tt> appended to
8646 the names of the packages containing the
8647 corresponding fonts.
8651 Fonts destined for the <file>misc</file> subdirectory
8652 should not be included in the same package as 75dpi
8653 or 100dpi fonts; instead, they should be provided in
8654 a separate package with <tt>-misc</tt> appended to
8659 Font packages must not provide the files
8660 <file>fonts.dir</file>, <file>fonts.alias</file>, or
8661 <file>fonts.scale</file> in a font directory:
8664 <file>fonts.dir</file> files must not be provided at all.
8668 <file>fonts.alias</file> and <file>fonts.scale</file>
8669 files, if needed, should be provided in the
8671 <file>/etc/X11/fonts/<var>fontdir</var>/<var>package</var>.<var>extension</var></file>,
8672 where <var>fontdir</var> is the name of the
8674 <file>/usr/share/fonts/X11/</file> where the
8675 package's corresponding fonts are stored
8676 (e.g., <tt>75dpi</tt> or <tt>misc</tt>),
8677 <var>package</var> is the name of the package
8678 that provides these fonts, and
8679 <var>extension</var> is either <tt>scale</tt>
8680 or <tt>alias</tt>, whichever corresponds to
8687 Font packages must declare a dependency on
8688 <tt>xfonts-utils</tt> in their control
8693 Font packages that provide one or more
8694 <file>fonts.scale</file> files as described above must
8695 invoke <prgn>update-fonts-scale</prgn> on each
8696 directory into which they installed fonts
8697 <em>before</em> invoking
8698 <prgn>update-fonts-dir</prgn> on that directory.
8699 This 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 that provide one or more
8707 <file>fonts.alias</file> files as described above must
8708 invoke <prgn>update-fonts-alias</prgn> on each
8709 directory into which they installed fonts. This
8710 invocation must occur in both the
8711 <prgn>postinst</prgn> (for all arguments) and
8712 <prgn>postrm</prgn> (for all arguments except
8713 <tt>upgrade</tt>) scripts.
8717 Font packages must invoke
8718 <prgn>update-fonts-dir</prgn> on each directory into
8719 which they installed fonts. This invocation must
8720 occur in both the <prgn>postinst</prgn> (for all
8721 arguments) and <prgn>postrm</prgn> (for all
8722 arguments except <tt>upgrade</tt>) scripts.
8726 Font packages must not provide alias names for the
8727 fonts they include which collide with alias names
8728 already in use by fonts already packaged.
8732 Font packages must not provide fonts with the same
8733 XLFD registry name as another font already packaged.
8739 <sect1 id="appdefaults">
8740 <heading>Application defaults files</heading>
8743 Application defaults files must be installed in the
8744 directory <file>/etc/X11/app-defaults/</file> (use of a
8745 localized subdirectory of <file>/etc/X11/</file> as described
8746 in the <em>X Toolkit Intrinsics - C Language
8747 Interface</em> manual is also permitted). They must be
8748 registered as <tt>conffile</tt>s or handled as
8749 configuration files.
8753 Customization of programs' X resources may also be
8754 supported with the provision of a file with the same name
8755 as that of the package placed in
8756 the <file>/etc/X11/Xresources/</file> directory, which
8757 must be registered as a <tt>conffile</tt> or handled as a
8758 configuration file.<footnote>
8759 Note that this mechanism is not the same as using
8760 app-defaults; app-defaults are tied to the client
8761 binary on the local file system, whereas X resources
8762 are stored in the X server and affect all connecting
8769 <heading>Installation directory issues</heading>
8772 Historically, packages using the X Window System used a
8773 separate set of installation directories from other packages.
8774 This practice has been discontinued and packages using the X
8775 Window System should now generally be installed in the same
8776 directories as any other package. Specifically, packages must
8777 not install files under the <file>/usr/X11R6/</file> directory
8778 and the <file>/usr/X11R6/</file> directory hierarchy should be
8779 regarded as obsolete.
8783 Include files previously installed under
8784 <file>/usr/X11R6/include/X11/</file> should be installed into
8785 <file>/usr/include/X11/</file>. For files previously
8786 installed into subdirectories of
8787 <file>/usr/X11R6/lib/X11/</file>, package maintainers should
8788 determine if subdirectories of <file>/usr/lib/</file> and
8789 <file>/usr/share/</file> can be used. If not, a subdirectory
8790 of <file>/usr/lib/X11/</file> should be used.
8794 Configuration files for window, display, or session managers
8795 or other applications that are tightly integrated with the X
8796 Window System may be placed in a subdirectory
8797 of <file>/etc/X11/</file> corresponding to the package name.
8798 Other X Window System applications should use
8799 the <file>/etc/</file> directory unless otherwise mandated by
8800 policy (such as for <ref id="appdefaults">).
8805 <heading>The OSF/Motif and OpenMotif libraries</heading>
8808 <em>Programs that require the non-DFSG-compliant OSF/Motif or
8809 OpenMotif libraries</em><footnote>
8810 OSF/Motif and OpenMotif are collectively referred to as
8811 "Motif" in this policy document.
8813 should be compiled against and tested with LessTif (a free
8814 re-implementation of Motif) instead. If the maintainer
8815 judges that the program or programs do not work
8816 sufficiently well with LessTif to be distributed and
8817 supported, but do so when compiled against Motif, then two
8818 versions of the package should be created; one linked
8819 statically against Motif and with <tt>-smotif</tt>
8820 appended to the package name, and one linked dynamically
8821 against Motif and with <tt>-dmotif</tt> appended to the
8826 Both Motif-linked versions are dependent
8827 upon non-DFSG-compliant software and thus cannot be
8828 uploaded to the <em>main</em> distribution; if the
8829 software is itself DFSG-compliant it may be uploaded to
8830 the <em>contrib</em> distribution. While known existing
8831 versions of Motif permit unlimited redistribution of
8832 binaries linked against the library (whether statically or
8833 dynamically), it is the package maintainer's
8834 responsibility to determine whether this is permitted by
8835 the license of the copy of Motif in their possession.
8841 <heading>Perl programs and modules</heading>
8844 Perl programs and modules should follow the current Perl policy.
8848 The Perl policy can be found in the <tt>perl-policy</tt>
8849 files in the <tt>debian-policy</tt> package.
8850 It is also available from the Debian web mirrors at
8851 <tt><url name="/doc/packaging-manuals/perl-policy/"
8852 id="http://www.debian.org/doc/packaging-manuals/perl-policy/"></tt>.
8857 <heading>Emacs lisp programs</heading>
8860 Please refer to the "Debian Emacs Policy" for details of how to
8861 package emacs lisp programs.
8865 The Emacs policy is available in
8866 <file>debian-emacs-policy.gz</file> of the
8867 <package>emacsen-common</package> package.
8868 It is also available from the Debian web mirrors at
8869 <tt><url name="/doc/packaging-manuals/debian-emacs-policy"
8870 id="http://www.debian.org/doc/packaging-manuals/debian-emacs-policy"></tt>.
8875 <heading>Games</heading>
8878 The permissions on <file>/var/games</file> are mode 755, owner
8879 <tt>root</tt> and group <tt>root</tt>.
8883 Each game decides on its own security policy.</p>
8886 Games which require protected, privileged access to
8887 high-score files, saved games, etc., may be made
8888 set-<em>group</em>-id (mode 2755) and owned by
8889 <tt>root:games</tt>, and use files and directories with
8890 appropriate permissions (770 <tt>root:games</tt>, for
8891 example). They must not be made
8892 set-<em>user</em>-id, as this causes security problems. (If
8893 an attacker can subvert any set-user-id game they can
8894 overwrite the executable of any other, causing other players
8895 of these games to run a Trojan horse program. With a
8896 set-group-id game the attacker only gets access to less
8897 important game data, and if they can get at the other
8898 players' accounts at all it will take considerably more
8902 Some packages, for example some fortune cookie programs, are
8903 configured by the upstream authors to install with their
8904 data files or other static information made unreadable so
8905 that they can only be accessed through set-id programs
8906 provided. You should not do this in a Debian package: anyone can
8907 download the <file>.deb</file> file and read the data from it,
8908 so there is no point making the files unreadable. Not
8909 making the files unreadable also means that you don't have
8910 to make so many programs set-id, which reduces the risk of a
8914 As described in the FHS, binaries of games should be
8915 installed in the directory <file>/usr/games</file>. This also
8916 applies to games that use the X Window System. Manual pages
8917 for games (X and non-X games) should be installed in
8918 <file>/usr/share/man/man6</file>.</p>
8924 <heading>Documentation</heading>
8927 <heading>Manual pages</heading>
8930 You should install manual pages in <prgn>nroff</prgn> source
8931 form, in appropriate places under <file>/usr/share/man</file>.
8932 You should only use sections 1 to 9 (see the FHS for more
8933 details). You must not install a pre-formatted "cat page".
8937 Each program, utility, and function should have an
8938 associated manual page included in the same package. It is
8939 suggested that all configuration files also have a manual
8940 page included as well. Manual pages for protocols and other
8941 auxiliary things are optional.
8945 If no manual page is available, this is considered as a bug
8946 and should be reported to the Debian Bug Tracking System (the
8947 maintainer of the package is allowed to write this bug report
8948 themselves, if they so desire). Do not close the bug report
8949 until a proper man page is available.<footnote>
8950 It is not very hard to write a man page. See the
8951 <url id="http://www.schweikhardt.net/man_page_howto.html"
8952 name="Man-Page-HOWTO">,
8953 <manref name="man" section="7">, the examples
8954 created by <prgn>debmake</prgn> or <prgn>dh_make</prgn>,
8955 the helper program <prgn>help2man</prgn>, or the
8956 directory <file>/usr/share/doc/man-db/examples</file>.
8961 You may forward a complaint about a missing man page to the
8962 upstream authors, and mark the bug as forwarded in the
8963 Debian bug tracking system. Even though the GNU Project do
8964 not in general consider the lack of a man page to be a bug,
8965 we do; if they tell you that they don't consider it a bug
8966 you should leave the bug in our bug tracking system open
8971 Manual pages should be installed compressed using <tt>gzip -9</tt>.
8975 If one man page needs to be accessible via several names it
8976 is better to use a symbolic link than the <file>.so</file>
8977 feature, but there is no need to fiddle with the relevant
8978 parts of the upstream source to change from <file>.so</file> to
8979 symlinks: don't do it unless it's easy. You should not
8980 create hard links in the manual page directories, nor put
8981 absolute filenames in <file>.so</file> directives. The filename
8982 in a <file>.so</file> in a man page should be relative to the
8983 base of the man page tree (usually
8984 <file>/usr/share/man</file>). If you do not create any links
8985 (whether symlinks, hard links, or <tt>.so</tt> directives)
8986 in the file system to the alternate names of the man page,
8987 then you should not rely on <prgn>man</prgn> finding your
8988 man page under those names based solely on the information in
8989 the man page's header.<footnote>
8990 Supporting this in <prgn>man</prgn> often requires
8991 unreasonable processing time to find a manual page or to
8992 report that none exists, and moves knowledge into man's
8993 database that would be better left in the file system.
8994 This support is therefore deprecated and will cease to
8995 be present in the future.
9000 Manual pages in locale-specific subdirectories of
9001 <file>/usr/share/man</file> should use either UTF-8 or the usual
9002 legacy encoding for that language (normally the one corresponding
9003 to the shortest relevant locale name in
9004 <file>/usr/share/i18n/SUPPORTED</file>). For example, pages under
9005 <file>/usr/share/man/fr</file> should use either UTF-8 or
9006 ISO-8859-1.<footnote>
9007 <prgn>man</prgn> will automatically detect whether UTF-8 is in
9008 use. In future, all manual pages will be required to use
9014 A country name (the <tt>DE</tt> in <tt>de_DE</tt>) should not be
9015 included in the subdirectory name unless it indicates a
9016 significant difference in the language, as this excludes
9017 speakers of the language in other countries.<footnote>
9018 At the time of writing, Chinese and Portuguese are the main
9019 languages with such differences, so <file>pt_BR</file>,
9020 <file>zh_CN</file>, and <file>zh_TW</file> are all allowed.
9025 If a localized version of a manual page is provided, it should
9026 either be up-to-date or it should be obvious to the reader that
9027 it is outdated and the original manual page should be used
9028 instead. This can be done either by a note at the beginning of
9029 the manual page or by showing the missing or changed portions in
9030 the original language instead of the target language.
9035 <heading>Info documents</heading>
9038 Info documents should be installed in <file>/usr/share/info</file>.
9039 They should be compressed with <tt>gzip -9</tt>.
9043 The <prgn>install-info</prgn> program maintains a directory of
9044 installed info documents in <file>/usr/share/info/dir</file> for
9045 the use of info readers.<footnote>
9046 It was previously necessary for packages installing info
9047 documents to run <prgn>install-info</prgn> from maintainer
9048 scripts. This is no longer necessary. The installation
9049 system now uses dpkg triggers.
9051 This file must not be included in packages. Packages containing
9052 info documents should depend on <tt>dpkg (>= 1.15.4) |
9053 install-info</tt> to ensure that the directory file is properly
9054 rebuilt during partial upgrades from Debian 5.0 (lenny) and
9059 Info documents should contain section and directory entry
9060 information in the document for the use
9061 of <prgn>install-info</prgn>. The section should be specified
9062 via a line starting with <tt>INFO-DIR-SECTION</tt> followed by a
9063 space and the section of this info page. The directory entry or
9064 entries should be included between
9065 a <tt>START-INFO-DIR-ENTRY</tt> line and
9066 an <tt>END-INFO-DIR-ENTRY</tt> line. For example:
9068 INFO-DIR-SECTION Individual utilities
9069 START-INFO-DIR-ENTRY
9070 * example: (example). An example info directory entry.
9073 To determine which section to use, you should look
9074 at <file>/usr/share/info/dir</file> on your system and choose
9075 the most relevant (or create a new section if none of the
9076 current sections are relevant).<footnote>
9077 Normally, info documents are generated from Texinfo source.
9078 To include this information in the generated info document, if
9079 it is absent, add commands like:
9081 @dircategory Individual utilities
9083 * example: (example). An example info directory entry.
9086 to the Texinfo source of the document and ensure that the info
9087 documents are rebuilt from source during the package build.
9093 <heading>Additional documentation</heading>
9096 Any additional documentation that comes with the package may
9097 be installed at the discretion of the package maintainer.
9098 Plain text documentation should be installed in the directory
9099 <file>/usr/share/doc/<var>package</var></file>, where
9100 <var>package</var> is the name of the package, and
9101 compressed with <tt>gzip -9</tt> unless it is small.
9105 If a package comes with large amounts of documentation which
9106 many users of the package will not require you should create
9107 a separate binary package to contain it, so that it does not
9108 take up disk space on the machines of users who do not need
9109 or want it installed.</p>
9112 It is often a good idea to put text information files
9113 (<file>README</file>s, changelogs, and so forth) that come with
9114 the source package in <file>/usr/share/doc/<var>package</var></file>
9115 in the binary package. However, you don't need to install
9116 the instructions for building and installing the package, of
9120 Packages must not require the existence of any files in
9121 <file>/usr/share/doc/</file> in order to function
9123 The system administrator should be able to
9124 delete files in <file>/usr/share/doc/</file> without causing
9125 any programs to break.
9127 Any files that are referenced by programs but are also
9128 useful as stand alone documentation should be installed under
9129 <file>/usr/share/<var>package</var>/</file> with symbolic links from
9130 <file>/usr/share/doc/<var>package</var></file>.
9134 <file>/usr/share/doc/<var>package</var></file> may be a symbolic
9135 link to another directory in <file>/usr/share/doc</file> only if
9136 the two packages both come from the same source and the
9137 first package Depends on the second.<footnote>
9139 Please note that this does not override the section on
9140 changelog files below, so the file
9141 <file>/usr/share/doc/<var>package</var>/changelog.Debian.gz</file>
9142 must refer to the changelog for the current version of
9143 <var>package</var> in question. In practice, this means
9144 that the sources of the target and the destination of the
9145 symlink must be the same (same source package and
9152 Former Debian releases placed all additional documentation
9153 in <file>/usr/doc/<var>package</var></file>. This has been
9154 changed to <file>/usr/share/doc/<var>package</var></file>,
9155 and packages must not put documentation in the directory
9156 <file>/usr/doc/<var>package</var></file>. <footnote>
9157 At this phase of the transition, we no longer require a
9158 symbolic link in <file>/usr/doc/</file>. At a later point,
9159 policy shall change to make the symbolic links a bug.
9165 <heading>Preferred documentation formats</heading>
9168 The unification of Debian documentation is being carried out
9172 If your package comes with extensive documentation in a
9173 markup format that can be converted to various other formats
9174 you should if possible ship HTML versions in a binary
9175 package, in the directory
9176 <file>/usr/share/doc/<var>appropriate-package</var></file> or
9177 its subdirectories.<footnote>
9178 The rationale: The important thing here is that HTML
9179 docs should be available in <em>some</em> package, not
9180 necessarily in the main binary package.
9185 Other formats such as PostScript may be provided at the
9186 package maintainer's discretion.
9190 <sect id="copyrightfile">
9191 <heading>Copyright information</heading>
9194 Every package must be accompanied by a verbatim copy of its
9195 copyright information and distribution license in the file
9196 <file>/usr/share/doc/<var>package</var>/copyright</file>. This
9197 file must neither be compressed nor be a symbolic link.
9201 In addition, the copyright file must say where the upstream
9202 sources (if any) were obtained. It should name the original
9203 authors of the package and the Debian maintainer(s) who were
9204 involved with its creation.
9208 Packages in the <em>contrib</em> or <em>non-free</em> archive
9209 areas should state in the copyright file that the package is not
9210 part of the Debian GNU/Linux distribution and briefly explain
9215 A copy of the file which will be installed in
9216 <file>/usr/share/doc/<var>package</var>/copyright</file> should
9217 be in <file>debian/copyright</file> in the source package.
9221 <file>/usr/share/doc/<var>package</var></file> may be a symbolic
9222 link to another directory in <file>/usr/share/doc</file> only if
9223 the two packages both come from the same source and the
9224 first package Depends on the second. These rules are
9225 important because copyrights must be extractable by
9230 Packages distributed under the Apache license (version 2.0), the
9231 Artistic license, the GNU GPL (version 2 or 3), the GNU LGPL
9232 (versions 2, 2.1, or 3), and the GNU FDL (versions 1.2 or 1.3)
9233 should refer to the corresponding files
9234 under <file>/usr/share/common-licenses</file>,<footnote>
9237 <file>/usr/share/common-licenses/Apache-2.0</file>,
9238 <file>/usr/share/common-licenses/Artistic</file>,
9239 <file>/usr/share/common-licenses/GPL-2</file>,
9240 <file>/usr/share/common-licenses/GPL-3</file>,
9241 <file>/usr/share/common-licenses/LGPL-2</file>,
9242 <file>/usr/share/common-licenses/LGPL-2.1</file>,
9243 <file>/usr/share/common-licenses/LGPL-3</file>,
9244 <file>/usr/share/common-licenses/GFDL-1.2</file>, and
9245 <file>/usr/share/common-licenses/GFDL-1.3</file>
9246 respectively. The University of California BSD license is
9247 also included in <package>base-files</package> as
9248 <file>/usr/share/common-licenses/BSD</file>, but given the
9249 brevity of this license, its specificity to code whose
9250 copyright is held by the Regents of the Univesrity of
9251 California, and the frequency of minor wording changes, its
9252 text should be included in the copyright file rather than
9253 referencing this file.
9255 </footnote> rather than quoting them in the copyright
9260 You should not use the copyright file as a general <file>README</file>
9261 file. If your package has such a file it should be
9262 installed in <file>/usr/share/doc/<var>package</var>/README</file> or
9263 <file>README.Debian</file> or some other appropriate place.</p>
9267 <heading>Examples</heading>
9270 Any examples (configurations, source files, whatever),
9271 should be installed in a directory
9272 <file>/usr/share/doc/<var>package</var>/examples</file>. These
9273 files should not be referenced by any program: they're there
9274 for the benefit of the system administrator and users as
9275 documentation only. Architecture-specific example files
9276 should be installed in a directory
9277 <file>/usr/lib/<var>package</var>/examples</file> with symbolic
9279 <file>/usr/share/doc/<var>package</var>/examples</file>, or the
9280 latter directory itself may be a symbolic link to the
9285 If the purpose of a package is to provide examples, then the
9286 example files may be installed into
9287 <file>/usr/share/doc/<var>package</var></file>.
9291 <sect id="changelogs">
9292 <heading>Changelog files</heading>
9295 Packages that are not Debian-native must contain a
9296 compressed copy of the <file>debian/changelog</file> file from
9297 the Debian source tree in
9298 <file>/usr/share/doc/<var>package</var></file> with the name
9299 <file>changelog.Debian.gz</file>.
9303 If an upstream changelog is available, it should be accessible as
9304 <file>/usr/share/doc/<var>package</var>/changelog.gz</file> in
9305 plain text. If the upstream changelog is distributed in
9306 HTML, it should be made available in that form as
9307 <file>/usr/share/doc/<var>package</var>/changelog.html.gz</file>
9308 and a plain text <file>changelog.gz</file> should be generated
9309 from it using, for example, <tt>lynx -dump -nolist</tt>. If
9310 the upstream changelog files do not already conform to this
9311 naming convention, then this may be achieved either by
9312 renaming the files, or by adding a symbolic link, at the
9313 maintainer's discretion.<footnote>
9314 Rationale: People should not have to look in places for
9315 upstream changelogs merely because they are given
9316 different names or are distributed in HTML format.
9321 All of these files should be installed compressed using
9322 <tt>gzip -9</tt>, as they will become large with time even
9323 if they start out small.
9327 If the package has only one changelog which is used both as
9328 the Debian changelog and the upstream one because there is
9329 no separate upstream maintainer then that changelog should
9330 usually be installed as
9331 <file>/usr/share/doc/<var>package</var>/changelog.gz</file>; if
9332 there is a separate upstream maintainer, but no upstream
9333 changelog, then the Debian changelog should still be called
9334 <file>changelog.Debian.gz</file>.
9338 For details about the format and contents of the Debian
9339 changelog file, please see <ref id="dpkgchangelog">.
9344 <appendix id="pkg-scope">
9345 <heading>Introduction and scope of these appendices</heading>
9348 These appendices are taken essentially verbatim from the
9349 now-deprecated Packaging Manual, version 3.2.1.0. They are
9350 the chapters which are likely to be of use to package
9351 maintainers and which have not already been included in the
9352 policy document itself. Most of these sections are very likely
9353 not relevant to policy; they should be treated as
9354 documentation for the packaging system. Please note that these
9355 appendices are included for convenience, and for historical
9356 reasons: they used to be part of policy package, and they have
9357 not yet been incorporated into dpkg documentation. However,
9358 they still have value, and hence they are presented here.
9362 They have not yet been checked to ensure that they are
9363 compatible with the contents of policy, and if there are any
9364 contradictions, the version in the main policy document takes
9365 precedence. The remaining chapters of the old Packaging
9366 Manual have also not been read in detail to ensure that there
9367 are not parts which have been left out. Both of these will be
9372 Certain parts of the Packaging manual were integrated into the
9373 Policy Manual proper, and removed from the appendices. Links
9374 have been placed from the old locations to the new ones.
9378 <prgn>dpkg</prgn> is a suite of programs for creating binary
9379 package files and installing and removing them on Unix
9381 <prgn>dpkg</prgn> is targeted primarily at Debian
9382 GNU/Linux, but may work on or be ported to other
9388 The binary packages are designed for the management of
9389 installed executable programs (usually compiled binaries) and
9390 their associated data, though source code examples and
9391 documentation are provided as part of some packages.</p>
9394 This manual describes the technical aspects of creating Debian
9395 binary packages (<file>.deb</file> files). It documents the
9396 behavior of the package management programs
9397 <prgn>dpkg</prgn>, <prgn>dselect</prgn> et al. and the way
9398 they interact with packages.</p>
9401 It also documents the interaction between
9402 <prgn>dselect</prgn>'s core and the access method scripts it
9403 uses to actually install the selected packages, and describes
9404 how to create a new access method.</p>
9407 This manual does not go into detail about the options and
9408 usage of the package building and installation tools. It
9409 should therefore be read in conjunction with those programs'
9414 The utility programs which are provided with <prgn>dpkg</prgn>
9415 for managing various system configuration and similar issues,
9416 such as <prgn>update-rc.d</prgn> and
9417 <prgn>install-info</prgn>, are not described in detail here -
9418 please see their man pages.
9422 It is assumed that the reader is reasonably familiar with the
9423 <prgn>dpkg</prgn> System Administrators' manual.
9424 Unfortunately this manual does not yet exist.
9428 The Debian version of the FSF's GNU hello program is provided
9429 as an example for people wishing to create Debian
9430 packages. The Debian <prgn>debmake</prgn> package is
9431 recommended as a very helpful tool in creating and maintaining
9432 Debian packages. However, while the tools and examples are
9433 helpful, they do not replace the need to read and follow the
9434 Policy and Programmer's Manual.</p>
9437 <appendix id="pkg-binarypkg">
9438 <heading>Binary packages (from old Packaging Manual)</heading>
9441 The binary package has two main sections. The first part
9442 consists of various control information files and scripts used
9443 by <prgn>dpkg</prgn> when installing and removing. See <ref
9444 id="pkg-controlarea">.
9448 The second part is an archive containing the files and
9449 directories to be installed.
9453 In the future binary packages may also contain other
9454 components, such as checksums and digital signatures. The
9455 format for the archive is described in full in the
9456 <file>deb(5)</file> man page.
9460 <sect id="pkg-bincreating"><heading>Creating package files -
9461 <prgn>dpkg-deb</prgn>
9465 All manipulation of binary package files is done by
9466 <prgn>dpkg-deb</prgn>; it's the only program that has
9467 knowledge of the format. (<prgn>dpkg-deb</prgn> may be
9468 invoked by calling <prgn>dpkg</prgn>, as <prgn>dpkg</prgn>
9469 will spot that the options requested are appropriate to
9470 <prgn>dpkg-deb</prgn> and invoke that instead with the same
9475 In order to create a binary package you must make a
9476 directory tree which contains all the files and directories
9477 you want to have in the file system data part of the package.
9478 In Debian-format source packages this directory is usually
9479 <file>debian/tmp</file>, relative to the top of the package's
9484 They should have the locations (relative to the root of the
9485 directory tree you're constructing) ownerships and
9486 permissions which you want them to have on the system when
9491 With current versions of <prgn>dpkg</prgn> the uid/username
9492 and gid/groupname mappings for the users and groups being
9493 used should be the same on the system where the package is
9494 built and the one where it is installed.
9498 You need to add one special directory to the root of the
9499 miniature file system tree you're creating:
9500 <prgn>DEBIAN</prgn>. It should contain the control
9501 information files, notably the binary package control file
9502 (see <ref id="pkg-controlfile">).
9506 The <prgn>DEBIAN</prgn> directory will not appear in the
9507 file system archive of the package, and so won't be installed
9508 by <prgn>dpkg</prgn> when the package is installed.
9512 When you've prepared the package, you should invoke:
9514 dpkg --build <var>directory</var>
9519 This will build the package in
9520 <file><var>directory</var>.deb</file>. (<prgn>dpkg</prgn> knows
9521 that <tt>--build</tt> is a <prgn>dpkg-deb</prgn> option, so
9522 it invokes <prgn>dpkg-deb</prgn> with the same arguments to
9527 See the man page <manref name="dpkg-deb" section="8"> for details of how
9528 to examine the contents of this newly-created file. You may find the
9529 output of following commands enlightening:
9531 dpkg-deb --info <var>filename</var>.deb
9532 dpkg-deb --contents <var>filename</var>.deb
9533 dpkg --contents <var>filename</var>.deb
9535 To view the copyright file for a package you could use this command:
9537 dpkg --fsys-tarfile <var>filename</var>.deb | tar xOf - --wildcards \*/copyright | pager
9542 <sect id="pkg-controlarea">
9543 <heading>Package control information files</heading>
9546 The control information portion of a binary package is a
9547 collection of files with names known to <prgn>dpkg</prgn>.
9548 It will treat the contents of these files specially - some
9549 of them contain information used by <prgn>dpkg</prgn> when
9550 installing or removing the package; others are scripts which
9551 the package maintainer wants <prgn>dpkg</prgn> to run.
9555 It is possible to put other files in the package control
9556 area, but this is not generally a good idea (though they
9557 will largely be ignored).
9561 Here is a brief list of the control info files supported by
9562 <prgn>dpkg</prgn> and a summary of what they're used for.
9567 <tag><tt>control</tt>
9570 This is the key description file used by
9571 <prgn>dpkg</prgn>. It specifies the package's name
9572 and version, gives its description for the user,
9573 states its relationships with other packages, and so
9574 forth. See <ref id="sourcecontrolfiles"> and
9575 <ref id="binarycontrolfiles">.
9579 It is usually generated automatically from information
9580 in the source package by the
9581 <prgn>dpkg-gencontrol</prgn> program, and with
9582 assistance from <prgn>dpkg-shlibdeps</prgn>.
9583 See <ref id="pkg-sourcetools">.
9587 <tag><tt>postinst</tt>, <tt>preinst</tt>, <tt>postrm</tt>,
9592 These are executable files (usually scripts) which
9593 <prgn>dpkg</prgn> runs during installation, upgrade
9594 and removal of packages. They allow the package to
9595 deal with matters which are particular to that package
9596 or require more complicated processing than that
9597 provided by <prgn>dpkg</prgn>. Details of when and
9598 how they are called are in <ref id="maintainerscripts">.
9602 It is very important to make these scripts idempotent.
9603 See <ref id="idempotency">.
9607 The maintainer scripts are not guaranteed to run with a
9608 controlling terminal and may not be able to interact with
9609 the user. See <ref id="controllingterminal">.
9613 <tag><tt>conffiles</tt>
9616 This file contains a list of configuration files which
9617 are to be handled automatically by <prgn>dpkg</prgn>
9618 (see <ref id="pkg-conffiles">). Note that not necessarily
9619 every configuration file should be listed here.
9622 <tag><tt>shlibs</tt>
9625 This file contains a list of the shared libraries
9626 supplied by the package, with dependency details for
9627 each. This is used by <prgn>dpkg-shlibdeps</prgn>
9628 when it determines what dependencies are required in a
9629 package control file. The <tt>shlibs</tt> file format
9630 is described on <ref id="shlibs">.
9635 <sect id="pkg-controlfile">
9636 <heading>The main control information file: <tt>control</tt></heading>
9639 The most important control information file used by
9640 <prgn>dpkg</prgn> when it installs a package is
9641 <tt>control</tt>. It contains all the package's "vital
9646 The binary package control files of packages built from
9647 Debian sources are made by a special tool,
9648 <prgn>dpkg-gencontrol</prgn>, which reads
9649 <file>debian/control</file> and <file>debian/changelog</file> to
9650 find the information it needs. See <ref id="pkg-sourcepkg"> for
9655 The fields in binary package control files are listed in
9656 <ref id="binarycontrolfiles">.
9660 A description of the syntax of control files and the purpose
9661 of the fields is available in <ref id="controlfields">.
9666 <heading>Time Stamps</heading>
9669 See <ref id="timestamps">.
9674 <appendix id="pkg-sourcepkg">
9675 <heading>Source packages (from old Packaging Manual) </heading>
9678 The Debian binary packages in the distribution are generated
9679 from Debian sources, which are in a special format to assist
9680 the easy and automatic building of binaries.
9683 <sect id="pkg-sourcetools">
9684 <heading>Tools for processing source packages</heading>
9687 Various tools are provided for manipulating source packages;
9688 they pack and unpack sources and help build of binary
9689 packages and help manage the distribution of new versions.
9693 They are introduced and typical uses described here; see
9694 <manref name="dpkg-source" section="1"> for full
9695 documentation about their arguments and operation.
9699 For examples of how to construct a Debian source package,
9700 and how to use those utilities that are used by Debian
9701 source packages, please see the <prgn>hello</prgn> example
9705 <sect1 id="pkg-dpkg-source">
9707 <prgn>dpkg-source</prgn> - packs and unpacks Debian source
9712 This program is frequently used by hand, and is also
9713 called from package-independent automated building scripts
9714 such as <prgn>dpkg-buildpackage</prgn>.
9718 To unpack a package it is typically invoked with
9720 dpkg-source -x <var>.../path/to/filename</var>.dsc
9725 with the <file><var>filename</var>.tar.gz</file> and
9726 <file><var>filename</var>.diff.gz</file> (if applicable) in
9727 the same directory. It unpacks into
9728 <file><var>package</var>-<var>version</var></file>, and if
9730 <file><var>package</var>-<var>version</var>.orig</file>, in
9731 the current directory.
9735 To create a packed source archive it is typically invoked:
9737 dpkg-source -b <var>package</var>-<var>version</var>
9742 This will create the <file>.dsc</file>, <file>.tar.gz</file> and
9743 <file>.diff.gz</file> (if appropriate) in the current
9744 directory. <prgn>dpkg-source</prgn> does not clean the
9745 source tree first - this must be done separately if it is
9750 See also <ref id="pkg-sourcearchives">.</p>
9754 <sect1 id="pkg-dpkg-buildpackage">
9756 <prgn>dpkg-buildpackage</prgn> - overall package-building
9761 <prgn>dpkg-buildpackage</prgn> is a script which invokes
9762 <prgn>dpkg-source</prgn>, the <file>debian/rules</file>
9763 targets <tt>clean</tt>, <tt>build</tt> and
9764 <tt>binary</tt>, <prgn>dpkg-genchanges</prgn> and
9765 <prgn>gpg</prgn> (or <prgn>pgp</prgn>) to build a signed
9766 source and binary package upload.
9770 It is usually invoked by hand from the top level of the
9771 built or unbuilt source directory. It may be invoked with
9772 no arguments; useful arguments include:
9773 <taglist compact="compact">
9774 <tag><tt>-uc</tt>, <tt>-us</tt></tag>
9777 Do not sign the <tt>.changes</tt> file or the
9778 source package <tt>.dsc</tt> file, respectively.</p>
9780 <tag><tt>-p<var>sign-command</var></tt></tag>
9783 Invoke <var>sign-command</var> instead of finding
9784 <tt>gpg</tt> or <tt>pgp</tt> on the <prgn>PATH</prgn>.
9785 <var>sign-command</var> must behave just like
9786 <prgn>gpg</prgn> or <tt>pgp</tt>.</p>
9788 <tag><tt>-r<var>root-command</var></tt></tag>
9791 When root privilege is required, invoke the command
9792 <var>root-command</var>. <var>root-command</var>
9793 should invoke its first argument as a command, from
9794 the <prgn>PATH</prgn> if necessary, and pass its
9795 second and subsequent arguments to the command it
9796 calls. If no <var>root-command</var> is supplied
9797 then <var>dpkg-buildpackage</var> will take no
9798 special action to gain root privilege, so that for
9799 most packages it will have to be invoked as root to
9802 <tag><tt>-b</tt>, <tt>-B</tt></tag>
9805 Two types of binary-only build and upload - see
9806 <manref name="dpkg-source" section="1">.
9813 <sect1 id="pkg-dpkg-gencontrol">
9815 <prgn>dpkg-gencontrol</prgn> - generates binary package
9820 This program is usually called from <file>debian/rules</file>
9821 (see <ref id="pkg-sourcetree">) in the top level of the source
9826 This is usually done just before the files and directories in the
9827 temporary directory tree where the package is being built have their
9828 permissions and ownerships set and the package is constructed using
9829 <prgn>dpkg-deb/</prgn>
9831 This is so that the control file which is produced has
9832 the right permissions
9837 <prgn>dpkg-gencontrol</prgn> must be called after all the
9838 files which are to go into the package have been placed in
9839 the temporary build directory, so that its calculation of
9840 the installed size of a package is correct.
9844 It is also necessary for <prgn>dpkg-gencontrol</prgn> to
9845 be run after <prgn>dpkg-shlibdeps</prgn> so that the
9846 variable substitutions created by
9847 <prgn>dpkg-shlibdeps</prgn> in <file>debian/substvars</file>
9852 For a package which generates only one binary package, and
9853 which builds it in <file>debian/tmp</file> relative to the top
9854 of the source package, it is usually sufficient to call
9855 <prgn>dpkg-gencontrol</prgn>.
9859 Sources which build several binaries will typically need
9862 dpkg-gencontrol -Pdebian/tmp-<var>pkg</var> -p<var>package</var>
9863 </example> The <tt>-P</tt> tells
9864 <prgn>dpkg-gencontrol</prgn> that the package is being
9865 built in a non-default directory, and the <tt>-p</tt>
9866 tells it which package's control file should be generated.
9870 <prgn>dpkg-gencontrol</prgn> also adds information to the
9871 list of files in <file>debian/files</file>, for the benefit of
9872 (for example) a future invocation of
9873 <prgn>dpkg-genchanges</prgn>.</p>
9876 <sect1 id="pkg-dpkg-shlibdeps">
9878 <prgn>dpkg-shlibdeps</prgn> - calculates shared library
9883 This program is usually called from <file>debian/rules</file>
9884 just before <prgn>dpkg-gencontrol</prgn> (see <ref
9885 id="pkg-sourcetree">), in the top level of the source tree.
9889 Its arguments are executables and shared libraries
9892 They may be specified either in the locations in the
9893 source tree where they are created or in the locations
9894 in the temporary build tree where they are installed
9895 prior to binary package creation.
9897 </footnote> for which shared library dependencies should
9898 be included in the binary package's control file.
9902 If some of the found shared libraries should only
9903 warrant a <tt>Recommends</tt> or <tt>Suggests</tt>, or if
9904 some warrant a <tt>Pre-Depends</tt>, this can be achieved
9905 by using the <tt>-d<var>dependency-field</var></tt> option
9906 before those executable(s). (Each <tt>-d</tt> option
9907 takes effect until the next <tt>-d</tt>.)
9911 <prgn>dpkg-shlibdeps</prgn> does not directly cause the
9912 output control file to be modified. Instead by default it
9913 adds to the <file>debian/substvars</file> file variable
9914 settings like <tt>shlibs:Depends</tt>. These variable
9915 settings must be referenced in dependency fields in the
9916 appropriate per-binary-package sections of the source
9921 For example, a package that generates an essential part
9922 which requires dependencies, and optional parts that
9923 which only require a recommendation, would separate those
9924 two sets of dependencies into two different fields.<footnote>
9925 At the time of writing, an example for this was the
9926 <package/xmms/ package, with Depends used for the xmms
9927 executable, Recommends for the plug-ins and Suggests for
9928 even more optional features provided by unzip.
9930 It can say in its <file>debian/rules</file>:
9932 dpkg-shlibdeps -dDepends <var>program anotherprogram ...</var> \
9933 -dRecommends <var>optionalpart anotheroptionalpart</var>
9935 and then in its main control file <file>debian/control</file>:
9938 Depends: ${shlibs:Depends}
9939 Recommends: ${shlibs:Recommends}
9945 Sources which produce several binary packages with
9946 different shared library dependency requirements can use
9947 the <tt>-p<var>varnameprefix</var></tt> option to override
9948 the default <tt>shlibs:</tt> prefix (one invocation of
9949 <prgn>dpkg-shlibdeps</prgn> per setting of this option).
9950 They can thus produce several sets of dependency
9951 variables, each of the form
9952 <tt><var>varnameprefix</var>:<var>dependencyfield</var></tt>,
9953 which can be referred to in the appropriate parts of the
9954 binary package control files.
9959 <sect1 id="pkg-dpkg-distaddfile">
9961 <prgn>dpkg-distaddfile</prgn> - adds a file to
9962 <file>debian/files</file>
9966 Some packages' uploads need to include files other than
9967 the source and binary package files.
9971 <prgn>dpkg-distaddfile</prgn> adds a file to the
9972 <file>debian/files</file> file so that it will be included in
9973 the <file>.changes</file> file when
9974 <prgn>dpkg-genchanges</prgn> is run.
9978 It is usually invoked from the <tt>binary</tt> target of
9979 <file>debian/rules</file>:
9981 dpkg-distaddfile <var>filename</var> <var>section</var> <var>priority</var>
9983 The <var>filename</var> is relative to the directory where
9984 <prgn>dpkg-genchanges</prgn> will expect to find it - this
9985 is usually the directory above the top level of the source
9986 tree. The <file>debian/rules</file> target should put the
9987 file there just before or just after calling
9988 <prgn>dpkg-distaddfile</prgn>.
9992 The <var>section</var> and <var>priority</var> are passed
9993 unchanged into the resulting <file>.changes</file> file.
9998 <sect1 id="pkg-dpkg-genchanges">
10000 <prgn>dpkg-genchanges</prgn> - generates a <file>.changes</file>
10001 upload control file
10005 This program is usually called by package-independent
10006 automatic building scripts such as
10007 <prgn>dpkg-buildpackage</prgn>, but it may also be called
10012 It is usually called in the top level of a built source
10013 tree, and when invoked with no arguments will print out a
10014 straightforward <file>.changes</file> file based on the
10015 information in the source package's changelog and control
10016 file and the binary and source packages which should have
10022 <sect1 id="pkg-dpkg-parsechangelog">
10024 <prgn>dpkg-parsechangelog</prgn> - produces parsed
10025 representation of a changelog
10029 This program is used internally by
10030 <prgn>dpkg-source</prgn> et al. It may also occasionally
10031 be useful in <file>debian/rules</file> and elsewhere. It
10032 parses a changelog, <file>debian/changelog</file> by default,
10033 and prints a control-file format representation of the
10034 information in it to standard output.
10038 <sect1 id="pkg-dpkg-architecture">
10040 <prgn>dpkg-architecture</prgn> - information about the build and
10045 This program can be used manually, but is also invoked by
10046 <tt>dpkg-buildpackage</tt> or <file>debian/rules</file> to set
10047 environment or make variables which specify the build and host
10048 architecture for the package building process.
10053 <sect id="pkg-sourcetree">
10054 <heading>The Debianised source tree</heading>
10057 The source archive scheme described later is intended to
10058 allow a Debianised source tree with some associated control
10059 information to be reproduced and transported easily. The
10060 Debianised source tree is a version of the original program
10061 with certain files added for the benefit of the
10062 Debianisation process, and with any other changes required
10063 made to the rest of the source code and installation
10068 The extra files created for Debian are in the subdirectory
10069 <file>debian</file> of the top level of the Debianised source
10070 tree. They are described below.
10073 <sect1 id="pkg-debianrules">
10074 <heading><file>debian/rules</file> - the main building script</heading>
10077 See <ref id="debianrules">.
10081 <sect1 id="pkg-srcsubstvars">
10082 <heading><file>debian/substvars</file> and variable substitutions</heading>
10085 See <ref id="substvars">.
10091 <heading><file>debian/files</file></heading>
10094 See <ref id="debianfiles">.
10098 <sect1><heading><file>debian/tmp</file>
10102 This is the canonical temporary location for the
10103 construction of binary packages by the <tt>binary</tt>
10104 target. The directory <file>tmp</file> serves as the root of
10105 the file system tree as it is being constructed (for
10106 example, by using the package's upstream makefiles install
10107 targets and redirecting the output there), and it also
10108 contains the <tt>DEBIAN</tt> subdirectory. See <ref
10109 id="pkg-bincreating">.
10113 If several binary packages are generated from the same
10114 source tree it is usual to use several
10115 <file>debian/tmp<var>something</var></file> directories, for
10116 example <file>tmp-a</file> or <file>tmp-doc</file>.
10120 Whatever <file>tmp</file> directories are created and used by
10121 <tt>binary</tt> must of course be removed by the
10122 <tt>clean</tt> target.</p></sect1>
10126 <sect id="pkg-sourcearchives"><heading>Source packages as archives
10130 As it exists on the FTP site, a Debian source package
10131 consists of three related files. You must have the right
10132 versions of all three to be able to use them.
10137 <tag>Debian source control file - <tt>.dsc</tt></tag>
10139 This file is a control file used by <prgn>dpkg-source</prgn>
10140 to extract a source package.
10141 See <ref id="debiansourcecontrolfiles">.
10145 Original source archive -
10147 <var>package</var>_<var>upstream-version</var>.orig.tar.gz
10153 This is a compressed (with <tt>gzip -9</tt>)
10154 <prgn>tar</prgn> file containing the source code from
10155 the upstream authors of the program.
10160 Debianisation diff -
10162 <var>package</var>_<var>upstream_version-revision</var>.diff.gz
10168 This is a unified context diff (<tt>diff -u</tt>)
10169 giving the changes which are required to turn the
10170 original source into the Debian source. These changes
10171 may only include editing and creating plain files.
10172 The permissions of files, the targets of symbolic
10173 links and the characteristics of special files or
10174 pipes may not be changed and no files may be removed
10179 All the directories in the diff must exist, except the
10180 <file>debian</file> subdirectory of the top of the source
10181 tree, which will be created by
10182 <prgn>dpkg-source</prgn> if necessary when unpacking.
10186 The <prgn>dpkg-source</prgn> program will
10187 automatically make the <file>debian/rules</file> file
10188 executable (see below).</p></item>
10193 If there is no original source code - for example, if the
10194 package is specially prepared for Debian or the Debian
10195 maintainer is the same as the upstream maintainer - the
10196 format is slightly different: then there is no diff, and the
10198 <file><var>package</var>_<var>version</var>.tar.gz</file>,
10199 and preferably contains a directory named
10200 <file><var>package</var>-<var>version</var></file>.
10205 <heading>Unpacking a Debian source package without <prgn>dpkg-source</prgn></heading>
10208 <tt>dpkg-source -x</tt> is the recommended way to unpack a
10209 Debian source package. However, if it is not available it
10210 is possible to unpack a Debian source archive as follows:
10211 <enumlist compact="compact">
10214 Untar the tarfile, which will create a <file>.orig</file>
10218 <p>Rename the <file>.orig</file> directory to
10219 <file><var>package</var>-<var>version</var></file>.</p>
10223 Create the subdirectory <file>debian</file> at the top of
10224 the source tree.</p>
10226 <item><p>Apply the diff using <tt>patch -p0</tt>.</p>
10228 <item><p>Untar the tarfile again if you want a copy of the original
10229 source code alongside the Debianised version.</p>
10234 It is not possible to generate a valid Debian source archive
10235 without using <prgn>dpkg-source</prgn>. In particular,
10236 attempting to use <prgn>diff</prgn> directly to generate the
10237 <file>.diff.gz</file> file will not work.
10241 <heading>Restrictions on objects in source packages</heading>
10244 The source package may not contain any hard links
10246 This is not currently detected when building source
10247 packages, but only when extracting
10251 Hard links may be permitted at some point in the
10252 future, but would require a fair amount of
10254 </footnote>, device special files, sockets or setuid or
10257 Setgid directories are allowed.
10262 The source packaging tools manage the changes between the
10263 original and Debianised source using <prgn>diff</prgn> and
10264 <prgn>patch</prgn>. Turning the original source tree as
10265 included in the <file>.orig.tar.gz</file> into the debianised
10266 source must not involve any changes which cannot be
10267 handled by these tools. Problematic changes which cause
10268 <prgn>dpkg-source</prgn> to halt with an error when
10269 building the source package are:
10270 <list compact="compact">
10271 <item><p>Adding or removing symbolic links, sockets or pipes.</p>
10273 <item><p>Changing the targets of symbolic links.</p>
10275 <item><p>Creating directories, other than <file>debian</file>.</p>
10277 <item><p>Changes to the contents of binary files.</p></item>
10278 </list> Changes which cause <prgn>dpkg-source</prgn> to
10279 print a warning but continue anyway are:
10280 <list compact="compact">
10283 Removing files, directories or symlinks.
10285 Renaming a file is not treated specially - it is
10286 seen as the removal of the old file (which
10287 generates a warning, but is otherwise ignored),
10288 and the creation of the new one.
10294 Changed text files which are missing the usual final
10295 newline (either in the original or the modified
10300 Changes which are not represented, but which are not detected by
10301 <prgn>dpkg-source</prgn>, are:
10302 <list compact="compact">
10303 <item><p>Changing the permissions of files (other than
10304 <file>debian/rules</file>) and directories.</p></item>
10309 The <file>debian</file> directory and <file>debian/rules</file>
10310 are handled specially by <prgn>dpkg-source</prgn> - before
10311 applying the changes it will create the <file>debian</file>
10312 directory, and afterwards it will make
10313 <file>debian/rules</file> world-executable.
10319 <appendix id="pkg-controlfields">
10320 <heading>Control files and their fields (from old Packaging Manual)</heading>
10323 Many of the tools in the <prgn>dpkg</prgn> suite manipulate
10324 data in a common format, known as control files. Binary and
10325 source packages have control data as do the <file>.changes</file>
10326 files which control the installation of uploaded files, and
10327 <prgn>dpkg</prgn>'s internal databases are in a similar
10332 <heading>Syntax of control files</heading>
10335 See <ref id="controlsyntax">.
10339 It is important to note that there are several fields which
10340 are optional as far as <prgn>dpkg</prgn> and the related
10341 tools are concerned, but which must appear in every Debian
10342 package, or whose omission may cause problems.
10347 <heading>List of fields</heading>
10350 See <ref id="controlfieldslist">.
10354 This section now contains only the fields that didn't belong
10355 to the Policy manual.
10358 <sect1 id="pkg-f-Filename">
10359 <heading><tt>Filename</tt> and <tt>MSDOS-Filename</tt></heading>
10362 These fields in <tt>Packages</tt> files give the
10363 filename(s) of (the parts of) a package in the
10364 distribution directories, relative to the root of the
10365 Debian hierarchy. If the package has been split into
10366 several parts the parts are all listed in order, separated
10371 <sect1 id="pkg-f-Size">
10372 <heading><tt>Size</tt> and <tt>MD5sum</tt></heading>
10375 These fields in <file>Packages</file> files give the size (in
10376 bytes, expressed in decimal) and MD5 checksum of the
10377 file(s) which make(s) up a binary package in the
10378 distribution. If the package is split into several parts
10379 the values for the parts are listed in order, separated by
10384 <sect1 id="pkg-f-Status">
10385 <heading><tt>Status</tt></heading>
10388 This field in <prgn>dpkg</prgn>'s status file records
10389 whether the user wants a package installed, removed or
10390 left alone, whether it is broken (requiring
10391 re-installation) or not and what its current state on the
10392 system is. Each of these pieces of information is a
10397 <sect1 id="pkg-f-Config-Version">
10398 <heading><tt>Config-Version</tt></heading>
10401 If a package is not installed or not configured, this
10402 field in <prgn>dpkg</prgn>'s status file records the last
10403 version of the package which was successfully
10408 <sect1 id="pkg-f-Conffiles">
10409 <heading><tt>Conffiles</tt></heading>
10412 This field in <prgn>dpkg</prgn>'s status file contains
10413 information about the automatically-managed configuration
10414 files held by a package. This field should <em>not</em>
10415 appear anywhere in a package!
10420 <heading>Obsolete fields</heading>
10423 These are still recognized by <prgn>dpkg</prgn> but should
10424 not appear anywhere any more.
10426 <taglist compact="compact">
10428 <tag><tt>Revision</tt></tag>
10429 <tag><tt>Package-Revision</tt></tag>
10430 <tag><tt>Package_Revision</tt></tag>
10432 The Debian revision part of the package version was
10433 at one point in a separate control file field. This
10434 field went through several names.
10437 <tag><tt>Recommended</tt></tag>
10438 <item>Old name for <tt>Recommends</tt>.</item>
10440 <tag><tt>Optional</tt></tag>
10441 <item>Old name for <tt>Suggests</tt>.</item>
10443 <tag><tt>Class</tt></tag>
10444 <item>Old name for <tt>Priority</tt>.</item>
10453 <appendix id="pkg-conffiles">
10454 <heading>Configuration file handling (from old Packaging Manual)</heading>
10457 <prgn>dpkg</prgn> can do a certain amount of automatic
10458 handling of package configuration files.
10462 Whether this mechanism is appropriate depends on a number of
10463 factors, but basically there are two approaches to any
10464 particular configuration file.
10468 The easy method is to ship a best-effort configuration in the
10469 package, and use <prgn>dpkg</prgn>'s conffile mechanism to
10470 handle updates. If the user is unlikely to want to edit the
10471 file, but you need them to be able to without losing their
10472 changes, and a new package with a changed version of the file
10473 is only released infrequently, this is a good approach.
10477 The hard method is to build the configuration file from
10478 scratch in the <prgn>postinst</prgn> script, and to take the
10479 responsibility for fixing any mistakes made in earlier
10480 versions of the package automatically. This will be
10481 appropriate if the file is likely to need to be different on
10485 <sect><heading>Automatic handling of configuration files by
10490 A package may contain a control area file called
10491 <tt>conffiles</tt>. This file should be a list of filenames
10492 of configuration files needing automatic handling, separated
10493 by newlines. The filenames should be absolute pathnames,
10494 and the files referred to should actually exist in the
10499 When a package is upgraded <prgn>dpkg</prgn> will process
10500 the configuration files during the configuration stage,
10501 shortly before it runs the package's <prgn>postinst</prgn>
10506 For each file it checks to see whether the version of the
10507 file included in the package is the same as the one that was
10508 included in the last version of the package (the one that is
10509 being upgraded from); it also compares the version currently
10510 installed on the system with the one shipped with the last
10515 If neither the user nor the package maintainer has changed
10516 the file, it is left alone. If one or the other has changed
10517 their version, then the changed version is preferred - i.e.,
10518 if the user edits their file, but the package maintainer
10519 doesn't ship a different version, the user's changes will
10520 stay, silently, but if the maintainer ships a new version
10521 and the user hasn't edited it the new version will be
10522 installed (with an informative message). If both have
10523 changed their version the user is prompted about the problem
10524 and must resolve the differences themselves.
10528 The comparisons are done by calculating the MD5 message
10529 digests of the files, and storing the MD5 of the file as it
10530 was included in the most recent version of the package.
10534 When a package is installed for the first time
10535 <prgn>dpkg</prgn> will install the file that comes with it,
10536 unless that would mean overwriting a file already on the
10541 However, note that <prgn>dpkg</prgn> will <em>not</em>
10542 replace a conffile that was removed by the user (or by a
10543 script). This is necessary because with some programs a
10544 missing file produces an effect hard or impossible to
10545 achieve in another way, so that a missing file needs to be
10546 kept that way if the user did it.
10550 Note that a package should <em>not</em> modify a
10551 <prgn>dpkg</prgn>-handled conffile in its maintainer
10552 scripts. Doing this will lead to <prgn>dpkg</prgn> giving
10553 the user confusing and possibly dangerous options for
10554 conffile update when the package is upgraded.</p>
10557 <sect><heading>Fully-featured maintainer script configuration
10562 For files which contain site-specific information such as
10563 the hostname and networking details and so forth, it is
10564 better to create the file in the package's
10565 <prgn>postinst</prgn> script.
10569 This will typically involve examining the state of the rest
10570 of the system to determine values and other information, and
10571 may involve prompting the user for some information which
10572 can't be obtained some other way.
10576 When using this method there are a couple of important
10577 issues which should be considered:
10581 If you discover a bug in the program which generates the
10582 configuration file, or if the format of the file changes
10583 from one version to the next, you will have to arrange for
10584 the postinst script to do something sensible - usually this
10585 will mean editing the installed configuration file to remove
10586 the problem or change the syntax. You will have to do this
10587 very carefully, since the user may have changed the file,
10588 perhaps to fix the very problem that your script is trying
10589 to deal with - you will have to detect these situations and
10590 deal with them correctly.
10594 If you do go down this route it's probably a good idea to
10595 make the program that generates the configuration file(s) a
10596 separate program in <file>/usr/sbin</file>, by convention called
10597 <file><var>package</var>config</file> and then run that if
10598 appropriate from the post-installation script. The
10599 <tt><var>package</var>config</tt> program should not
10600 unquestioningly overwrite an existing configuration - if its
10601 mode of operation is geared towards setting up a package for
10602 the first time (rather than any arbitrary reconfiguration
10603 later) you should have it check whether the configuration
10604 already exists, and require a <tt>--force</tt> flag to
10605 overwrite it.</p></sect>
10608 <appendix id="pkg-alternatives"><heading>Alternative versions of
10609 an interface - <prgn>update-alternatives</prgn> (from old
10614 When several packages all provide different versions of the
10615 same program or file it is useful to have the system select a
10616 default, but to allow the system administrator to change it
10617 and have their decisions respected.
10621 For example, there are several versions of the <prgn>vi</prgn>
10622 editor, and there is no reason to prevent all of them from
10623 being installed at once, each under their own name
10624 (<prgn>nvi</prgn>, <prgn>vim</prgn> or whatever).
10625 Nevertheless it is desirable to have the name <tt>vi</tt>
10626 refer to something, at least by default.
10630 If all the packages involved cooperate, this can be done with
10631 <prgn>update-alternatives</prgn>.
10635 Each package provides its own version under its own name, and
10636 calls <prgn>update-alternatives</prgn> in its postinst to
10637 register its version (and again in its prerm to deregister
10642 See the man page <manref name="update-alternatives"
10643 section="8"> for details.
10647 If <prgn>update-alternatives</prgn> does not seem appropriate
10648 you may wish to consider using diversions instead.</p>
10651 <appendix id="pkg-diversions"><heading>Diversions - overriding a
10652 package's version of a file (from old Packaging Manual)
10656 It is possible to have <prgn>dpkg</prgn> not overwrite a file
10657 when it reinstalls the package it belongs to, and to have it
10658 put the file from the package somewhere else instead.
10662 This can be used locally to override a package's version of a
10663 file, or by one package to override another's version (or
10664 provide a wrapper for it).
10668 Before deciding to use a diversion, read <ref
10669 id="pkg-alternatives"> to see if you really want a diversion
10670 rather than several alternative versions of a program.
10674 There is a diversion list, which is read by <prgn>dpkg</prgn>,
10675 and updated by a special program <prgn>dpkg-divert</prgn>.
10676 Please see <manref name="dpkg-divert" section="8"> for full
10677 details of its operation.
10681 When a package wishes to divert a file from another, it should
10682 call <prgn>dpkg-divert</prgn> in its preinst to add the
10683 diversion and rename the existing file. For example,
10684 supposing that a <prgn>smailwrapper</prgn> package wishes to
10685 install a wrapper around <file>/usr/sbin/smail</file>:
10687 dpkg-divert --package smailwrapper --add --rename \
10688 --divert /usr/sbin/smail.real /usr/sbin/smail
10689 </example> The <tt>--package smailwrapper</tt> ensures that
10690 <prgn>smailwrapper</prgn>'s copy of <file>/usr/sbin/smail</file>
10691 can bypass the diversion and get installed as the true version.
10692 It's safe to add the diversion unconditionally on upgrades since
10693 it will be left unchanged if it already exists, but
10694 <prgn>dpkg-divert</prgn> will display a message. To suppress that
10695 message, make the command conditional on the version from which
10696 the package is being upgraded:
10698 if [ upgrade != "$1" ] || dpkg --compare-versions "$2" lt 1.0-2; then
10699 dpkg-divert --package smailwrapper --add --rename \
10700 --divert /usr/sbin/smail.real /usr/sbin/smail
10702 </example> where <tt>1.0-2</tt> is the version at which the
10703 diversion was first added to the package. Running the command
10704 during abort-upgrade is pointless but harmless.
10708 The postrm has to do the reverse:
10710 if [ remove = "$1" -o abort-install = "$1" -o disappear = "$1" ]; then
10711 dpkg-divert --package smailwrapper --remove --rename \
10712 --divert /usr/sbin/smail.real /usr/sbin/smail
10714 </example> If the diversion was added at a particular version, the
10715 postrm should also handle the failure case of upgrading from an
10716 older version (unless the older version is so old that direct
10717 upgrades are no longer supported):
10719 if [ abort-upgrade = "$1" ] && dpkg --compare-versions "$2" lt 1.0-2; then
10720 dpkg-divert --package smailwrapper --remove --rename \
10721 --divert /usr/sbin/smail.real /usr/sbin/smail
10723 </example> where <tt>1.02-2</tt> is the version at which the
10724 diversion was first added to the package. The postrm should not
10725 remove the diversion on upgrades both because there's no reason to
10726 remove the diversion only to immediately re-add it and since the
10727 postrm of the old package is run after unpacking so the removal of
10728 the diversion will fail.
10732 Do not attempt to divert a file which is vitally important for
10733 the system's operation - when using <prgn>dpkg-divert</prgn>
10734 there is a time, after it has been diverted but before
10735 <prgn>dpkg</prgn> has installed the new version, when the file
10736 does not exist.</p>
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