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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 for
1858 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> is
1861 not <tt>all</tt>). Similarly, the <tt>build-indep</tt>
1862 target, if provided, should perform all the configuration
1863 and compilation required for producing all
1864 architecture-independent binary packages (those packages
1865 for which the body of the <tt>Architecture</tt> field
1866 in <tt>debian/control</tt> is <tt>all</tt>).
1867 The <tt>build</tt> target should depend on those of the
1868 targets <tt>build-arch</tt> and <tt>build-indep</tt> that
1869 are provided in the rules file.<footnote>
1870 The intent of this split is so that binary-only builds
1871 need not install the dependencies required for
1872 the <tt>build-indep</tt> target. However, this is not
1873 yet used in practice since <tt>dpkg-buildpackage
1874 -B</tt>, and therefore the autobuilders,
1875 invoke <tt>build</tt> rather than <tt>build-arch</tt>
1876 due to the difficulties in determining whether the
1877 optional <tt>build-arch</tt> target exists.
1882 If one or both of the targets <tt>build-arch</tt> and
1883 <tt>build-indep</tt> are not provided, then invoking
1884 <file>debian/rules</file> with one of the not-provided
1885 targets as arguments should produce a exit status code
1886 of 2. Usually this is provided automatically by make
1887 if the target is missing.
1891 The <tt>build-arch</tt> and <tt>build-indep</tt> targets
1892 must not do anything that might require root privilege.
1896 <tag><tt>binary</tt>, <tt>binary-arch</tt>,
1897 <tt>binary-indep</tt>
1901 The <tt>binary</tt> target must be all that is
1902 necessary for the user to build the binary package(s)
1903 produced from this source package. It is
1904 split into two parts: <prgn>binary-arch</prgn> builds
1905 the binary packages which are specific to a particular
1906 architecture, and <tt>binary-indep</tt> builds
1907 those which are not.
1910 <tt>binary</tt> may be (and commonly is) a target with
1911 no commands which simply depends on
1912 <tt>binary-arch</tt> and <tt>binary-indep</tt>.
1915 Both <tt>binary-*</tt> targets should depend on the
1916 <tt>build</tt> target, or on the appropriate
1917 <tt>build-arch</tt> or <tt>build-indep</tt> target, if
1918 provided, so that the package is built if it has not
1919 been already. It should then create the relevant
1920 binary package(s), using <prgn>dpkg-gencontrol</prgn> to
1921 make their control files and <prgn>dpkg-deb</prgn> to
1922 build them and place them in the parent of the top
1927 Both the <tt>binary-arch</tt> and
1928 <tt>binary-indep</tt> targets <em>must</em> exist.
1929 If one of them has nothing to do (which will always be
1930 the case if the source generates only a single binary
1931 package, whether architecture-dependent or not), it
1932 must still exist and must always succeed.
1936 The <tt>binary</tt> targets must be invoked as
1938 The <prgn>fakeroot</prgn> package often allows one
1939 to build a package correctly even without being
1945 <tag><tt>clean</tt></tag>
1948 This must undo any effects that the <tt>build</tt>
1949 and <tt>binary</tt> targets may have had, except
1950 that it should leave alone any output files created in
1951 the parent directory by a run of a <tt>binary</tt>
1956 If a <tt>build</tt> file is touched at the end of
1957 the <tt>build</tt> target, as suggested above, it
1958 should be removed as the first action that
1959 <tt>clean</tt> performs, so that running
1960 <tt>build</tt> again after an interrupted
1961 <tt>clean</tt> doesn't think that everything is
1966 The <tt>clean</tt> target may need to be
1967 invoked as root if <tt>binary</tt> has been
1968 invoked since the last <tt>clean</tt>, or if
1969 <tt>build</tt> has been invoked as root (since
1970 <tt>build</tt> may create directories, for
1975 <tag><tt>get-orig-source</tt> (optional)</tag>
1978 This target fetches the most recent version of the
1979 original source package from a canonical archive site
1980 (via FTP or WWW, for example), does any necessary
1981 rearrangement to turn it into the original source
1982 tar file format described below, and leaves it in the
1987 This target may be invoked in any directory, and
1988 should take care to clean up any temporary files it
1993 This target is optional, but providing it if
1994 possible is a good idea.
1998 <tag><tt>patch</tt> (optional)</tag>
2001 This target performs whatever additional actions are
2002 required to make the source ready for editing (unpacking
2003 additional upstream archives, applying patches, etc.).
2004 It is recommended to be implemented for any package where
2005 <tt>dpkg-source -x</tt> does not result in source ready
2006 for additional modification. See
2007 <ref id="readmesource">.
2013 The <tt>build</tt>, <tt>binary</tt> and
2014 <tt>clean</tt> targets must be invoked with the current
2015 directory being the package's top-level directory.
2020 Additional targets may exist in <file>debian/rules</file>,
2021 either as published or undocumented interfaces or for the
2022 package's internal use.
2026 The architectures we build on and build for are determined
2027 by <prgn>make</prgn> variables using the utility
2028 <qref id="pkg-dpkg-architecture"><prgn>dpkg-architecture</prgn></qref>.
2029 You can determine the
2030 Debian architecture and the GNU style architecture
2031 specification string for the build machine (the machine type
2032 we are building on) as well as for the host machine (the
2033 machine type we are building for). Here is a list of
2034 supported <prgn>make</prgn> variables:
2035 <list compact="compact">
2037 <tt>DEB_*_ARCH</tt> (the Debian architecture)
2040 <tt>DEB_*_ARCH_CPU</tt> (the Debian CPU name)
2043 <tt>DEB_*_ARCH_OS</tt> (the Debian System name)
2046 <tt>DEB_*_GNU_TYPE</tt> (the GNU style architecture
2047 specification string)
2050 <tt>DEB_*_GNU_CPU</tt> (the CPU part of
2051 <tt>DEB_*_GNU_TYPE</tt>)
2054 <tt>DEB_*_GNU_SYSTEM</tt> (the System part of
2055 <tt>DEB_*_GNU_TYPE</tt>)
2057 where <tt>*</tt> is either <tt>BUILD</tt> for specification of
2058 the build machine or <tt>HOST</tt> for specification of the
2063 Backward compatibility can be provided in the rules file
2064 by setting the needed variables to suitable default
2065 values; please refer to the documentation of
2066 <prgn>dpkg-architecture</prgn> for details.
2070 It is important to understand that the <tt>DEB_*_ARCH</tt>
2071 string only determines which Debian architecture we are
2072 building on or for. It should not be used to get the CPU
2073 or system information; the <tt>DEB_*_ARCH_CPU</tt> and
2074 <tt>DEB_*_ARCH_OS</tt> variables should be used for that.
2075 GNU style variables should generally only be used with upstream
2079 <sect1 id="debianrules-options">
2080 <heading><file>debian/rules</file> and
2081 <tt>DEB_BUILD_OPTIONS</tt></heading>
2084 Supporting the standardized environment variable
2085 <tt>DEB_BUILD_OPTIONS</tt> is recommended. This variable can
2086 contain several flags to change how a package is compiled and
2087 built. Each flag must be in the form <var>flag</var> or
2088 <var>flag</var>=<var>options</var>. If multiple flags are
2089 given, they must be separated by whitespace.<footnote>
2090 Some packages support any delimiter, but whitespace is the
2091 easiest to parse inside a makefile and avoids ambiguity with
2092 flag values that contain commas.
2094 <var>flag</var> must start with a lowercase letter
2095 (<tt>a-z</tt>) and consist only of lowercase letters,
2096 numbers (<tt>0-9</tt>), and the characters
2097 <tt>-</tt> and <tt>_</tt> (hyphen and underscore).
2098 <var>options</var> must not contain whitespace. The same
2099 tag should not be given multiple times with conflicting
2100 values. Package maintainers may assume that
2101 <tt>DEB_BUILD_OPTIONS</tt> will not contain conflicting tags.
2105 The meaning of the following tags has been standardized:
2109 This tag says to not run any build-time test suite
2110 provided by the package.
2114 The presence of this tag means that the package should
2115 be compiled with a minimum of optimization. For C
2116 programs, it is best to add <tt>-O0</tt> to
2117 <tt>CFLAGS</tt> (although this is usually the default).
2118 Some programs might fail to build or run at this level
2119 of optimization; it may be necessary to use
2120 <tt>-O1</tt>, for example.
2124 This tag means that the debugging symbols should not be
2125 stripped from the binary during installation, so that
2126 debugging information may be included in the package.
2128 <tag>parallel=n</tag>
2130 This tag means that the package should be built using up
2131 to <tt>n</tt> parallel processes if the package build
2132 system supports this.<footnote>
2133 Packages built with <tt>make</tt> can often implement
2134 this by passing the <tt>-j</tt><var>n</var> option to
2137 If the package build system does not support parallel
2138 builds, this string must be ignored. If the package
2139 build system only supports a lower level of concurrency
2140 than <var>n</var>, the package should be built using as
2141 many parallel processes as the package build system
2142 supports. It is up to the package maintainer to decide
2143 whether the package build times are long enough and the
2144 package build system is robust enough to make supporting
2145 parallel builds worthwhile.
2151 Unknown flags must be ignored by <file>debian/rules</file>.
2155 The following makefile snippet is an example of how one may
2156 implement the build options; you will probably have to
2157 massage this example in order to make it work for your
2159 <example compact="compact">
2162 INSTALL_FILE = $(INSTALL) -p -o root -g root -m 644
2163 INSTALL_PROGRAM = $(INSTALL) -p -o root -g root -m 755
2164 INSTALL_SCRIPT = $(INSTALL) -p -o root -g root -m 755
2165 INSTALL_DIR = $(INSTALL) -p -d -o root -g root -m 755
2167 ifneq (,$(filter noopt,$(DEB_BUILD_OPTIONS)))
2172 ifeq (,$(filter nostrip,$(DEB_BUILD_OPTIONS)))
2173 INSTALL_PROGRAM += -s
2175 ifneq (,$(filter parallel=%,$(DEB_BUILD_OPTIONS)))
2176 NUMJOBS = $(patsubst parallel=%,%,$(filter parallel=%,$(DEB_BUILD_OPTIONS)))
2177 MAKEFLAGS += -j$(NUMJOBS)
2182 ifeq (,$(filter nocheck,$(DEB_BUILD_OPTIONS)))
2183 # Code to run the package test suite.
2190 <!-- FIXME: section pkg-srcsubstvars is the same as substvars -->
2191 <sect id="substvars">
2192 <heading>Variable substitutions: <file>debian/substvars</file></heading>
2195 When <prgn>dpkg-gencontrol</prgn>,
2196 <prgn>dpkg-genchanges</prgn> and <prgn>dpkg-source</prgn>
2197 generate control files they perform variable substitutions
2198 on their output just before writing it. Variable
2199 substitutions have the form <tt>${<var>variable</var>}</tt>.
2200 The optional file <file>debian/substvars</file> contains
2201 variable substitutions to be used; variables can also be set
2202 directly from <file>debian/rules</file> using the <tt>-V</tt>
2203 option to the source packaging commands, and certain
2204 predefined variables are also available.
2208 The <file>debian/substvars</file> file is usually generated and
2209 modified dynamically by <file>debian/rules</file> targets, in
2210 which case it must be removed by the <tt>clean</tt> target.
2214 See <manref name="deb-substvars" section="5"> for full
2215 details about source variable substitutions, including the
2216 format of <file>debian/substvars</file>.</p>
2219 <sect id="debianwatch">
2220 <heading>Optional upstream source location: <file>debian/watch</file></heading>
2223 This is an optional, recommended control file for the
2224 <tt>uscan</tt> utility which defines how to automatically
2225 scan ftp or http sites for newly available updates of the
2226 package. This is used by <url id="
2227 http://dehs.alioth.debian.org/"> and other Debian QA tools
2228 to help with quality control and maintenance of the
2229 distribution as a whole.
2234 <sect id="debianfiles">
2235 <heading>Generated files list: <file>debian/files</file></heading>
2238 This file is not a permanent part of the source tree; it
2239 is used while building packages to record which files are
2240 being generated. <prgn>dpkg-genchanges</prgn> uses it
2241 when it generates a <file>.changes</file> file.
2245 It should not exist in a shipped source package, and so it
2246 (and any backup files or temporary files such as
2247 <file>files.new</file><footnote>
2248 <file>files.new</file> is used as a temporary file by
2249 <prgn>dpkg-gencontrol</prgn> and
2250 <prgn>dpkg-distaddfile</prgn> - they write a new
2251 version of <tt>files</tt> here before renaming it,
2252 to avoid leaving a corrupted copy if an error
2254 </footnote>) should be removed by the
2255 <tt>clean</tt> target. It may also be wise to
2256 ensure a fresh start by emptying or removing it at the
2257 start of the <tt>binary</tt> target.
2261 When <prgn>dpkg-gencontrol</prgn> is run for a binary
2262 package, it adds an entry to <file>debian/files</file> for the
2263 <file>.deb</file> file that will be created when <tt>dpkg-deb
2264 --build</tt> is run for that binary package. So for most
2265 packages all that needs to be done with this file is to
2266 delete it in the <tt>clean</tt> target.
2270 If a package upload includes files besides the source
2271 package and any binary packages whose control files were
2272 made with <prgn>dpkg-gencontrol</prgn> then they should be
2273 placed in the parent of the package's top-level directory
2274 and <prgn>dpkg-distaddfile</prgn> should be called to add
2275 the file to the list in <file>debian/files</file>.</p>
2278 <sect id="embeddedfiles">
2279 <heading>Convenience copies of code</heading>
2282 Some software packages include in their distribution convenience
2283 copies of code from other software packages, generally so that
2284 users compiling from source don't have to download multiple
2285 packages. Debian packages should not make use of these
2286 convenience copies unless the included package is explicitly
2287 intended to be used in this way.<footnote>
2288 For example, parts of the GNU build system work like this.
2290 If the included code is already in the Debian archive in the
2291 form of a library, the Debian packaging should ensure that
2292 binary packages reference the libraries already in Debian and
2293 the convenience copy is not used. If the included code is not
2294 already in Debian, it should be packaged separately as a
2295 prerequisite if possible.
2297 Having multiple copies of the same code in Debian is
2298 inefficient, often creates either static linking or shared
2299 library conflicts, and, most importantly, increases the
2300 difficulty of handling security vulnerabilities in the
2306 <sect id="readmesource">
2307 <heading>Source package handling:
2308 <file>debian/README.source</file></heading>
2311 If running <prgn>dpkg-source -x</prgn> on a source package
2312 doesn't produce the source of the package, ready for editing,
2313 and allow one to make changes and run
2314 <prgn>dpkg-buildpackage</prgn> to produce a modified package
2315 without taking any additional steps, creating a
2316 <file>debian/README.source</file> documentation file is
2317 recommended. This file should explain how to do all of the
2320 <item>Generate the fully patched source, in a form ready for
2321 editing, that would be built to create Debian
2322 packages. Doing this with a <tt>patch</tt> target in
2323 <file>debian/rules</file> is recommended; see
2324 <ref id="debianrules">.</item>
2325 <item>Modify the source and save those modifications so that
2326 they will be applied when building the package.</item>
2327 <item>Remove source modifications that are currently being
2328 applied when building the package.</item>
2329 <item>Optionally, document what steps are necessary to
2330 upgrade the Debian source package to a new upstream version,
2331 if applicable.</item>
2333 This explanation should include specific commands and mention
2334 any additional required Debian packages. It should not assume
2335 familiarity with any specific Debian packaging system or patch
2340 This explanation may refer to a documentation file installed by
2341 one of the package's build dependencies provided that the
2342 referenced documentation clearly explains these tasks and is not
2343 a general reference manual.
2347 <file>debian/README.source</file> may also include any other
2348 information that would be helpful to someone modifying the
2349 source package. Even if the package doesn't fit the above
2350 description, maintainers are encouraged to document in a
2351 <file>debian/README.source</file> file any source package with a
2352 particularly complex or unintuitive source layout or build
2353 system (for example, a package that builds the same source
2354 multiple times to generate different binary packages).
2360 <chapt id="controlfields">
2361 <heading>Control files and their fields</heading>
2364 The package management system manipulates data represented in
2365 a common format, known as <em>control data</em>, stored in
2366 <em>control files</em>.
2367 Control files are used for source packages, binary packages and
2368 the <file>.changes</file> files which control the installation
2369 of uploaded files<footnote>
2370 <prgn>dpkg</prgn>'s internal databases are in a similar
2375 <sect id="controlsyntax">
2376 <heading>Syntax of control files</heading>
2379 A control file consists of one or more paragraphs of
2381 The paragraphs are also sometimes referred to as stanzas.
2383 The paragraphs are separated by blank lines. Some control
2384 files allow only one paragraph; others allow several, in
2385 which case each paragraph usually refers to a different
2386 package. (For example, in source packages, the first
2387 paragraph refers to the source package, and later paragraphs
2388 refer to binary packages generated from the source.)
2392 Each paragraph consists of a series of data fields; each
2393 field consists of the field name, followed by a colon and
2394 then the data/value associated with that field. It ends at
2395 the end of the (logical) line. Horizontal whitespace
2396 (spaces and tabs) may occur immediately before or after the
2397 value and is ignored there; it is conventional to put a
2398 single space after the colon. For example, a field might
2400 <example compact="compact">
2403 the field name is <tt>Package</tt> and the field value
2408 Many fields' values may span several lines; in this case
2409 each continuation line must start with a space or a tab.
2410 Any trailing spaces or tabs at the end of individual
2411 lines of a field value are ignored.
2415 In fields where it is specified that lines may not wrap,
2416 only a single line of data is allowed and whitespace is not
2417 significant in a field body. Whitespace must not appear
2418 inside names (of packages, architectures, files or anything
2419 else) or version numbers, or between the characters of
2420 multi-character version relationships.
2424 Field names are not case-sensitive, but it is usual to
2425 capitalize the field names using mixed case as shown below.
2426 Field values are case-sensitive unless the description of the
2427 field says otherwise.
2431 Blank lines, or lines consisting only of spaces and tabs,
2432 are not allowed within field values or between fields - that
2433 would mean a new paragraph.
2437 All control files must be encoded in UTF-8.
2441 <sect id="sourcecontrolfiles">
2442 <heading>Source package control files -- <file>debian/control</file></heading>
2445 The <file>debian/control</file> file contains the most vital
2446 (and version-independent) information about the source package
2447 and about the binary packages it creates.
2451 The first paragraph of the control file contains information about
2452 the source package in general. The subsequent sets each describe a
2453 binary package that the source tree builds.
2457 The fields in the general paragraph (the first one, for the source
2460 <list compact="compact">
2461 <item><qref id="f-Source"><tt>Source</tt></qref> (mandatory)</item>
2462 <item><qref id="f-Maintainer"><tt>Maintainer</tt></qref> (mandatory)</item>
2463 <item><qref id="f-Uploaders"><tt>Uploaders</tt></qref></item>
2464 <item><qref id="f-Section"><tt>Section</tt></qref> (recommended)</item>
2465 <item><qref id="f-Priority"><tt>Priority</tt></qref> (recommended)</item>
2466 <item><qref id="sourcebinarydeps"><tt>Build-Depends</tt> et al</qref></item>
2467 <item><qref id="f-Standards-Version"><tt>Standards-Version</tt></qref> (recommended)</item>
2468 <item><qref id="f-Homepage"><tt>Homepage</tt></qref></item>
2473 The fields in the binary package paragraphs are:
2475 <list compact="compact">
2476 <item><qref id="f-Package"><tt>Package</tt></qref> (mandatory)</item>
2477 <item><qref id="f-Architecture"><tt>Architecture</tt></qref> (mandatory)</item>
2478 <item><qref id="f-Section"><tt>Section</tt></qref> (recommended)</item>
2479 <item><qref id="f-Priority"><tt>Priority</tt></qref> (recommended)</item>
2480 <item><qref id="f-Essential"><tt>Essential</tt></qref></item>
2481 <item><qref id="binarydeps"><tt>Depends</tt> et al</qref></item>
2482 <item><qref id="f-Description"><tt>Description</tt></qref> (mandatory)</item>
2483 <item><qref id="f-Homepage"><tt>Homepage</tt></qref></item>
2488 The syntax and semantics of the fields are described below.
2494 These fields are used by <prgn>dpkg-gencontrol</prgn> to
2495 generate control files for binary packages (see below), by
2496 <prgn>dpkg-genchanges</prgn> to generate the
2497 <tt>.changes</tt> file to accompany the upload, and by
2498 <prgn>dpkg-source</prgn> when it creates the
2499 <file>.dsc</file> source control file as part of a source
2500 archive. Many fields are permitted to span multiple lines in
2501 <file>debian/control</file> but not in any other control
2502 file. These tools are responsible for removing the line
2503 breaks from such fields when using fields from
2504 <file>debian/control</file> to generate other control files.
2508 The fields here may contain variable references - their
2509 values will be substituted by <prgn>dpkg-gencontrol</prgn>,
2510 <prgn>dpkg-genchanges</prgn> or <prgn>dpkg-source</prgn>
2511 when they generate output control files.
2512 See <ref id="substvars"> for details.
2516 In addition to the control file syntax described <qref
2517 id="controlsyntax">above</qref>, this file may also contain
2518 comment lines starting with <tt>#</tt> without any preceding
2519 whitespace. All such lines are ignored, even in the middle of
2520 continuation lines for a multiline field, and do not end a
2526 <sect id="binarycontrolfiles">
2527 <heading>Binary package control files -- <file>DEBIAN/control</file></heading>
2530 The <file>DEBIAN/control</file> file contains the most vital
2531 (and version-dependent) information about a binary package.
2535 The fields in this file are:
2537 <list compact="compact">
2538 <item><qref id="f-Package"><tt>Package</tt></qref> (mandatory)</item>
2539 <item><qref id="f-Source"><tt>Source</tt></qref></item>
2540 <item><qref id="f-Version"><tt>Version</tt></qref> (mandatory)</item>
2541 <item><qref id="f-Section"><tt>Section</tt></qref> (recommended)</item>
2542 <item><qref id="f-Priority"><tt>Priority</tt></qref> (recommended)</item>
2543 <item><qref id="f-Architecture"><tt>Architecture</tt></qref> (mandatory)</item>
2544 <item><qref id="f-Essential"><tt>Essential</tt></qref></item>
2545 <item><qref id="binarydeps"><tt>Depends</tt> et al</qref></item>
2546 <item><qref id="f-Installed-Size"><tt>Installed-Size</tt></qref></item>
2547 <item><qref id="f-Maintainer"><tt>Maintainer</tt></qref> (mandatory)</item>
2548 <item><qref id="f-Description"><tt>Description</tt></qref> (mandatory)</item>
2549 <item><qref id="f-Homepage"><tt>Homepage</tt></qref></item>
2554 <sect id="debiansourcecontrolfiles">
2555 <heading>Debian source control files -- <tt>.dsc</tt></heading>
2558 This file contains a series of fields, identified and
2559 separated just like the fields in the control file of
2560 a binary package. The fields are listed below; their
2561 syntax is described above, in <ref id="pkg-controlfields">.
2563 <list compact="compact">
2564 <item><qref id="f-Format"><tt>Format</tt></qref> (mandatory)</item>
2565 <item><qref id="f-Source"><tt>Source</tt></qref> (mandatory)</item>
2566 <item><qref id="f-Version"><tt>Version</tt></qref> (mandatory)</item>
2567 <item><qref id="f-Maintainer"><tt>Maintainer</tt></qref> (mandatory)</item>
2568 <item><qref id="f-Uploaders"><tt>Uploaders</tt></qref></item>
2569 <item><qref id="f-Binary"><tt>Binary</tt></qref></item>
2570 <item><qref id="f-Architecture"><tt>Architecture</tt></qref></item>
2571 <item><qref id="sourcebinarydeps"><tt>Build-Depends</tt> et al</qref></item>
2572 <item><qref id="f-Standards-Version"><tt>Standards-Version</tt></qref> (recommended)</item>
2573 <item><qref id="f-Files"><tt>Files</tt></qref> (mandatory)</item>
2574 <item><qref id="f-Homepage"><tt>Homepage</tt></qref></item>
2579 The source package control file is generated by
2580 <prgn>dpkg-source</prgn> when it builds the source
2581 archive, from other files in the source package,
2582 described above. When unpacking, it is checked against
2583 the files and directories in the other parts of the
2589 <sect id="debianchangesfiles">
2590 <heading>Debian changes files -- <file>.changes</file></heading>
2593 The .changes files are used by the Debian archive maintenance
2594 software to process updates to packages. They contain one
2595 paragraph which contains information from the
2596 <tt>debian/control</tt> file and other data about the
2597 source package gathered via <tt>debian/changelog</tt>
2598 and <tt>debian/rules</tt>.
2602 The fields in this file are:
2604 <list compact="compact">
2605 <item><qref id="f-Format"><tt>Format</tt></qref> (mandatory)</item>
2606 <item><qref id="f-Date"><tt>Date</tt></qref> (mandatory)</item>
2607 <item><qref id="f-Source"><tt>Source</tt></qref> (mandatory)</item>
2608 <item><qref id="f-Binary"><tt>Binary</tt></qref> (mandatory)</item>
2609 <item><qref id="f-Architecture"><tt>Architecture</tt></qref> (mandatory)</item>
2610 <item><qref id="f-Version"><tt>Version</tt></qref> (mandatory)</item>
2611 <item><qref id="f-Distribution"><tt>Distribution</tt></qref> (mandatory)</item>
2612 <item><qref id="f-Urgency"><tt>Urgency</tt></qref> (recommended)</item>
2613 <item><qref id="f-Maintainer"><tt>Maintainer</tt></qref> (mandatory)</item>
2614 <item><qref id="f-Changed-By"><tt>Changed-By</tt></qref></item>
2615 <item><qref id="f-Description"><tt>Description</tt></qref> (mandatory)</item>
2616 <item><qref id="f-Closes"><tt>Closes</tt></qref></item>
2617 <item><qref id="f-Changes"><tt>Changes</tt></qref> (mandatory)</item>
2618 <item><qref id="f-Files"><tt>Files</tt></qref> (mandatory)</item>
2623 <sect id="controlfieldslist">
2624 <heading>List of fields</heading>
2626 <sect1 id="f-Source">
2627 <heading><tt>Source</tt></heading>
2630 This field identifies the source package name.
2634 In <file>debian/control</file> or a <file>.dsc</file> file,
2635 this field must contain only the name of the source package.
2639 In a binary package control file or a <file>.changes</file>
2640 file, the source package name may be followed by a version
2641 number in parentheses<footnote>
2642 It is customary to leave a space after the package name
2643 if a version number is specified.
2645 This version number may be omitted (and is, by
2646 <prgn>dpkg-gencontrol</prgn>) if it has the same value as
2647 the <tt>Version</tt> field of the binary package in
2648 question. The field itself may be omitted from a binary
2649 package control file when the source package has the same
2650 name and version as the binary package.
2654 Package names (both source and binary,
2655 see <ref id="f-Package">) must consist only of lower case
2656 letters (<tt>a-z</tt>), digits (<tt>0-9</tt>), plus
2657 (<tt>+</tt>) and minus (<tt>-</tt>) signs, and periods
2658 (<tt>.</tt>). They must be at least two characters long and
2659 must start with an alphanumeric character.
2663 <sect1 id="f-Maintainer">
2664 <heading><tt>Maintainer</tt></heading>
2667 The package maintainer's name and email address. The name
2668 should come first, then the email address inside angle
2669 brackets <tt><></tt> (in RFC822 format).
2673 If the maintainer's name contains a full stop then the
2674 whole field will not work directly as an email address due
2675 to a misfeature in the syntax specified in RFC822; a
2676 program using this field as an address must check for this
2677 and correct the problem if necessary (for example by
2678 putting the name in round brackets and moving it to the
2679 end, and bringing the email address forward).
2683 <sect1 id="f-Uploaders">
2684 <heading><tt>Uploaders</tt></heading>
2687 List of the names and email addresses of co-maintainers of
2688 the package, if any. If the package has other maintainers
2689 beside the one named in the
2690 <qref id="f-Maintainer">Maintainer field</qref>, their
2691 names and email addresses should be listed here. The
2692 format is the same as that of the Maintainer tag, and
2693 multiple entries should be comma separated. Currently,
2694 this field is restricted to a single line of data. This
2695 is an optional field.
2698 Any parser that interprets the Uploaders field in
2699 <file>debian/control</file> must permit it to span multiple
2700 lines. Line breaks in an Uploaders field that spans multiple
2701 lines are not significant and the semantics of the field are
2702 the same as if the line breaks had not been present.
2706 <sect1 id="f-Changed-By">
2707 <heading><tt>Changed-By</tt></heading>
2710 The name and email address of the person who changed the
2711 said package. Usually the name of the maintainer.
2712 All the rules for the Maintainer field apply here, too.
2716 <sect1 id="f-Section">
2717 <heading><tt>Section</tt></heading>
2720 This field specifies an application area into which the package
2721 has been classified. See <ref id="subsections">.
2725 When it appears in the <file>debian/control</file> file,
2726 it gives the value for the subfield of the same name in
2727 the <tt>Files</tt> field of the <file>.changes</file> file.
2728 It also gives the default for the same field in the binary
2733 <sect1 id="f-Priority">
2734 <heading><tt>Priority</tt></heading>
2737 This field represents how important it is that the user
2738 have the package installed. See <ref id="priorities">.
2742 When it appears in the <file>debian/control</file> file,
2743 it gives the value for the subfield of the same name in
2744 the <tt>Files</tt> field of the <file>.changes</file> file.
2745 It also gives the default for the same field in the binary
2750 <sect1 id="f-Package">
2751 <heading><tt>Package</tt></heading>
2754 The name of the binary package.
2758 Binary package names must follow the same syntax and
2759 restrictions as source package names. See <ref id="f-Source">
2764 <sect1 id="f-Architecture">
2765 <heading><tt>Architecture</tt></heading>
2768 Depending on context and the control file used, the
2769 <tt>Architecture</tt> field can include the following sets of
2773 A unique single word identifying a Debian machine
2774 architecture as described in <ref id="arch-spec">.
2777 An architecture wildcard identifying a set of Debian
2778 machine architectures, see <ref id="arch-wildcard-spec">.
2779 <tt>any</tt> matches all Debian machine architectures
2780 and is the most frequently used.
2783 <tt>all</tt>, which indicates an
2784 architecture-independent package.
2787 <tt>source</tt>, which indicates a source package.
2793 In the main <file>debian/control</file> file in the source
2794 package, this field may contain the special
2795 value <tt>all</tt>, the special architecture
2796 wildcard <tt>any</tt>, or a list of specific and wildcard
2797 architectures separated by spaces. If <tt>all</tt>
2798 or <tt>any</tt> appears, that value must be the entire
2799 contents of the field. Most packages will use
2800 either <tt>all</tt> or <tt>any</tt>.
2804 Specifying a specific list of architectures indicates that the
2805 source will build an architecture-dependent package only on
2806 architectures included in the list. Specifying a list of
2807 architecture wildcards indicates that the source will build an
2808 architecture-dependent package on only those architectures
2809 that match any of the specified architecture wildcards.
2810 Specifying a list of architectures or architecture wildcards
2811 other than <tt>any</tt> is for the minority of cases where a
2812 program is not portable or is not useful on some
2813 architectures. Where possible, the program should be made
2818 In the source package control file <file>.dsc</file>, this
2819 field may contain either the architecture
2820 wildcard <tt>any</tt> or a list of architectures and
2821 architecture wildcards separated by spaces. If a list is
2822 given, it may include (or consist solely of) the special
2823 value <tt>all</tt>. In other words, in <file>.dsc</file>
2824 files unlike the <file>debian/control</file>, <tt>all</tt> may
2825 occur in combination with specific architectures.
2826 The <tt>Architecture</tt> field in the source package control
2827 file <file>.dsc</file> is generally constructed from
2828 the <tt>Architecture</tt> fields in
2829 the <file>debian/control</file> in the source package.
2833 Specifying <tt>any</tt> indicates that the source package
2834 isn't dependent on any particular architecture and should
2835 compile fine on any one. The produced binary package(s)
2836 will either be specific to whatever the current build
2837 architecture is or will be architecture-independent.
2841 Specifying only <tt>all</tt> indicates that the source package
2842 will only build architecture-independent packages. If this is
2843 the case, <tt>all</tt> must be used rather than <tt>any</tt>;
2844 <tt>any</tt> implies that the source package will build at
2845 least one architecture-dependent package.
2849 Specifying a list of architectures or architecture wildcards
2850 indicates that the source will build an architecture-dependent
2851 package, and will only work correctly on the listed or
2852 matching architectures. If the source package also builds at
2853 least one architecture-independent package, <tt>all</tt> will
2854 also be included in the list.
2858 In a <file>.changes</file> file, the <tt>Architecture</tt>
2859 field lists the architecture(s) of the package(s) currently
2860 being uploaded. This will be a list; if the source for the
2861 package is also being uploaded, the special
2862 entry <tt>source</tt> is also present. <tt>all</tt> will be
2863 present if any architecture-independent packages are being
2864 uploaded. Architecture wildcards such as <tt>any</tt> must
2865 never occur in the <tt>Architecture</tt> field in
2866 the <file>.changes</file> file.
2870 See <ref id="debianrules"> for information on how to get
2871 the architecture for the build process.
2875 <sect1 id="f-Essential">
2876 <heading><tt>Essential</tt></heading>
2879 This is a boolean field which may occur only in the
2880 control file of a binary package or in a per-package fields
2881 paragraph of a main source control data file.
2885 If set to <tt>yes</tt> then the package management system
2886 will refuse to remove the package (upgrading and replacing
2887 it is still possible). The other possible value is <tt>no</tt>,
2888 which is the same as not having the field at all.
2893 <heading>Package interrelationship fields:
2894 <tt>Depends</tt>, <tt>Pre-Depends</tt>,
2895 <tt>Recommends</tt>, <tt>Suggests</tt>,
2896 <tt>Breaks</tt>, <tt>Conflicts</tt>,
2897 <tt>Provides</tt>, <tt>Replaces</tt>, <tt>Enhances</tt>
2901 These fields describe the package's relationships with
2902 other packages. Their syntax and semantics are described
2903 in <ref id="relationships">.</p>
2906 <sect1 id="f-Standards-Version">
2907 <heading><tt>Standards-Version</tt></heading>
2910 The most recent version of the standards (the policy
2911 manual and associated texts) with which the package
2916 The version number has four components: major and minor
2917 version number and major and minor patch level. When the
2918 standards change in a way that requires every package to
2919 change the major number will be changed. Significant
2920 changes that will require work in many packages will be
2921 signaled by a change to the minor number. The major patch
2922 level will be changed for any change to the meaning of the
2923 standards, however small; the minor patch level will be
2924 changed when only cosmetic, typographical or other edits
2925 are made which neither change the meaning of the document
2926 nor affect the contents of packages.
2930 Thus only the first three components of the policy version
2931 are significant in the <em>Standards-Version</em> control
2932 field, and so either these three components or all four
2933 components may be specified.<footnote>
2934 In the past, people specified the full version number
2935 in the Standards-Version field, for example "2.3.0.0".
2936 Since minor patch-level changes don't introduce new
2937 policy, it was thought it would be better to relax
2938 policy and only require the first 3 components to be
2939 specified, in this example "2.3.0". All four
2940 components may still be used if someone wishes to do so.
2946 <sect1 id="f-Version">
2947 <heading><tt>Version</tt></heading>
2950 The version number of a package. The format is:
2951 [<var>epoch</var><tt>:</tt>]<var>upstream_version</var>[<tt>-</tt><var>debian_revision</var>]
2955 The three components here are:
2957 <tag><var>epoch</var></tag>
2960 This is a single (generally small) unsigned integer. It
2961 may be omitted, in which case zero is assumed. If it is
2962 omitted then the <var>upstream_version</var> may not
2967 It is provided to allow mistakes in the version numbers
2968 of older versions of a package, and also a package's
2969 previous version numbering schemes, to be left behind.
2973 <tag><var>upstream_version</var></tag>
2976 This is the main part of the version number. It is
2977 usually the version number of the original ("upstream")
2978 package from which the <file>.deb</file> file has been made,
2979 if this is applicable. Usually this will be in the same
2980 format as that specified by the upstream author(s);
2981 however, it may need to be reformatted to fit into the
2982 package management system's format and comparison
2987 The comparison behavior of the package management system
2988 with respect to the <var>upstream_version</var> is
2989 described below. The <var>upstream_version</var>
2990 portion of the version number is mandatory.
2994 The <var>upstream_version</var> may contain only
2995 alphanumerics<footnote>
2996 Alphanumerics are <tt>A-Za-z0-9</tt> only.
2998 and the characters <tt>.</tt> <tt>+</tt> <tt>-</tt>
2999 <tt>:</tt> <tt>~</tt> (full stop, plus, hyphen, colon,
3000 tilde) and should start with a digit. If there is no
3001 <var>debian_revision</var> then hyphens are not allowed;
3002 if there is no <var>epoch</var> then colons are not
3007 <tag><var>debian_revision</var></tag>
3010 This part of the version number specifies the version of
3011 the Debian package based on the upstream version. It
3012 may contain only alphanumerics and the characters
3013 <tt>+</tt> <tt>.</tt> <tt>~</tt> (plus, full stop,
3014 tilde) and is compared in the same way as the
3015 <var>upstream_version</var> is.
3019 It is optional; if it isn't present then the
3020 <var>upstream_version</var> may not contain a hyphen.
3021 This format represents the case where a piece of
3022 software was written specifically to be turned into a
3023 Debian package, and so there is only one "debianisation"
3024 of it and therefore no revision indication is required.
3028 It is conventional to restart the
3029 <var>debian_revision</var> at <tt>1</tt> each time the
3030 <var>upstream_version</var> is increased.
3034 The package management system will break the version
3035 number apart at the last hyphen in the string (if there
3036 is one) to determine the <var>upstream_version</var> and
3037 <var>debian_revision</var>. The absence of a
3038 <var>debian_revision</var> is equivalent to a
3039 <var>debian_revision</var> of <tt>0</tt>.
3046 When comparing two version numbers, first the <var>epoch</var>
3047 of each are compared, then the <var>upstream_version</var> if
3048 <var>epoch</var> is equal, and then <var>debian_revision</var>
3049 if <var>upstream_version</var> is also equal.
3050 <var>epoch</var> is compared numerically. The
3051 <var>upstream_version</var> and <var>debian_revision</var>
3052 parts are compared by the package management system using the
3053 following algorithm:
3057 The strings are compared from left to right.
3061 First the initial part of each string consisting entirely of
3062 non-digit characters is determined. These two parts (one of
3063 which may be empty) are compared lexically. If a difference
3064 is found it is returned. The lexical comparison is a
3065 comparison of ASCII values modified so that all the letters
3066 sort earlier than all the non-letters and so that a tilde
3067 sorts before anything, even the end of a part. For example,
3068 the following parts are in sorted order from earliest to
3069 latest: <tt>~~</tt>, <tt>~~a</tt>, <tt>~</tt>, the empty part,
3070 <tt>a</tt>.<footnote>
3071 One common use of <tt>~</tt> is for upstream pre-releases.
3072 For example, <tt>1.0~beta1~svn1245</tt> sorts earlier than
3073 <tt>1.0~beta1</tt>, which sorts earlier than <tt>1.0</tt>.
3078 Then the initial part of the remainder of each string which
3079 consists entirely of digit characters is determined. The
3080 numerical values of these two parts are compared, and any
3081 difference found is returned as the result of the comparison.
3082 For these purposes an empty string (which can only occur at
3083 the end of one or both version strings being compared) counts
3088 These two steps (comparing and removing initial non-digit
3089 strings and initial digit strings) are repeated until a
3090 difference is found or both strings are exhausted.
3094 Note that the purpose of epochs is to allow us to leave behind
3095 mistakes in version numbering, and to cope with situations
3096 where the version numbering scheme changes. It is
3097 <em>not</em> intended to cope with version numbers containing
3098 strings of letters which the package management system cannot
3099 interpret (such as <tt>ALPHA</tt> or <tt>pre-</tt>), or with
3100 silly orderings.<footnote>
3101 The author of this manual has heard of a package whose
3102 versions went <tt>1.1</tt>, <tt>1.2</tt>, <tt>1.3</tt>,
3103 <tt>1</tt>, <tt>2.1</tt>, <tt>2.2</tt>, <tt>2</tt> and so
3109 <sect1 id="f-Description">
3110 <heading><tt>Description</tt></heading>
3113 In a source or binary control file, the <tt>Description</tt>
3114 field contains a description of the binary package, consisting
3115 of two parts, the synopsis or the short description, and the
3116 long description. The field's format is as follows:
3121 Description: <single line synopsis>
3122 <extended description over several lines>
3127 The lines in the extended description can have these formats:
3133 Those starting with a single space are part of a paragraph.
3134 Successive lines of this form will be word-wrapped when
3135 displayed. The leading space will usually be stripped off.
3139 Those starting with two or more spaces. These will be
3140 displayed verbatim. If the display cannot be panned
3141 horizontally, the displaying program will line wrap them "hard"
3142 (i.e., without taking account of word breaks). If it can they
3143 will be allowed to trail off to the right. None, one or two
3144 initial spaces may be deleted, but the number of spaces
3145 deleted from each line will be the same (so that you can have
3146 indenting work correctly, for example).
3150 Those containing a single space followed by a single full stop
3151 character. These are rendered as blank lines. This is the
3152 <em>only</em> way to get a blank line<footnote>
3153 Completely empty lines will not be rendered as blank lines.
3154 Instead, they will cause the parser to think you're starting
3155 a whole new record in the control file, and will therefore
3156 likely abort with an error.
3161 Those containing a space, a full stop and some more characters.
3162 These are for future expansion. Do not use them.
3168 Do not use tab characters. Their effect is not predictable.
3172 See <ref id="descriptions"> for further information on this.
3176 In a <file>.changes</file> file, the <tt>Description</tt>
3177 field contains a summary of the descriptions for the packages
3178 being uploaded. For this case, the first line of the field
3179 value (the part on the same line as <tt>Description:</tt>) is
3180 always empty. The content of the field is expressed as
3181 continuation lines, one line per package. Each line is
3182 indented by one space and contains the name of a binary
3183 package, a space, a hyphen (<tt>-</tt>), a space, and the
3184 short description line from that package.
3188 <sect1 id="f-Distribution">
3189 <heading><tt>Distribution</tt></heading>
3192 In a <file>.changes</file> file or parsed changelog output
3193 this contains the (space-separated) name(s) of the
3194 distribution(s) where this version of the package should
3195 be installed. Valid distributions are determined by the
3196 archive maintainers.<footnote>
3197 Example distribution names in the Debian archive used in
3198 <file>.changes</file> files are:
3199 <taglist compact="compact">
3200 <tag><em>unstable</em></tag>
3202 This distribution value refers to the
3203 <em>developmental</em> part of the Debian distribution
3204 tree. Most new packages, new upstream versions of
3205 packages and bug fixes go into the <em>unstable</em>
3209 <tag><em>experimental</em></tag>
3211 The packages with this distribution value are deemed
3212 by their maintainers to be high risk. Oftentimes they
3213 represent early beta or developmental packages from
3214 various sources that the maintainers want people to
3215 try, but are not ready to be a part of the other parts
3216 of the Debian distribution tree.
3221 Others are used for updating stable releases or for
3222 security uploads. More information is available in the
3223 Debian Developer's Reference, section "The Debian
3227 The Debian archive software only supports listing a single
3228 distribution. Migration of packages to other distributions is
3229 handled outside of the upload process.
3234 <heading><tt>Date</tt></heading>
3237 This field includes the date the package was built or last
3238 edited. It must be in the same format as the <var>date</var>
3239 in a <file>debian/changelog</file> entry.
3243 The value of this field is usually extracted from the
3244 <file>debian/changelog</file> file - see
3245 <ref id="dpkgchangelog">).
3249 <sect1 id="f-Format">
3250 <heading><tt>Format</tt></heading>
3253 This field specifies a format revision for the file.
3254 The most current format described in the Policy Manual
3255 is version <strong>1.5</strong>. The syntax of the
3256 format value is the same as that of a package version
3257 number except that no epoch or Debian revision is allowed
3258 - see <ref id="f-Version">.
3262 <sect1 id="f-Urgency">
3263 <heading><tt>Urgency</tt></heading>
3266 This is a description of how important it is to upgrade to
3267 this version from previous ones. It consists of a single
3268 keyword taking one of the values <tt>low</tt>,
3269 <tt>medium</tt>, <tt>high</tt>, <tt>emergency</tt>, or
3270 <tt>critical</tt><footnote>
3271 Other urgency values are supported with configuration
3272 changes in the archive software but are not used in Debian.
3273 The urgency affects how quickly a package will be considered
3274 for inclusion into the <tt>testing</tt> distribution and
3275 gives an indication of the importance of any fixes included
3276 in the upload. <tt>Emergency</tt> and <tt>critical</tt> are
3277 treated as synonymous.
3278 </footnote> (not case-sensitive) followed by an optional
3279 commentary (separated by a space) which is usually in
3280 parentheses. For example:
3283 Urgency: low (HIGH for users of diversions)
3289 The value of this field is usually extracted from the
3290 <file>debian/changelog</file> file - see
3291 <ref id="dpkgchangelog">.
3295 <sect1 id="f-Changes">
3296 <heading><tt>Changes</tt></heading>
3299 This field contains the human-readable changes data, describing
3300 the differences between the last version and the current one.
3304 The first line of the field value (the part on the same line
3305 as <tt>Changes:</tt>) is always empty. The content of the
3306 field is expressed as continuation lines, with each line
3307 indented by at least one space. Blank lines must be
3308 represented by a line consisting only of a space and a full
3313 The value of this field is usually extracted from the
3314 <file>debian/changelog</file> file - see
3315 <ref id="dpkgchangelog">).
3319 Each version's change information should be preceded by a
3320 "title" line giving at least the version, distribution(s)
3321 and urgency, in a human-readable way.
3325 If data from several versions is being returned the entry
3326 for the most recent version should be returned first, and
3327 entries should be separated by the representation of a
3328 blank line (the "title" line may also be followed by the
3329 representation of a blank line).
3333 <sect1 id="f-Binary">
3334 <heading><tt>Binary</tt></heading>
3337 This field is a list of binary packages. Its syntax and
3338 meaning varies depending on the control file in which it
3343 When it appears in the <file>.dsc</file> file, it lists binary
3344 packages which a source package can produce, separated by
3346 A space after each comma is conventional.
3347 </footnote>. It may span multiple lines. The source package
3348 does not necessarily produce all of these binary packages for
3349 every architecture. The source control file doesn't contain
3350 details of which architectures are appropriate for which of
3351 the binary packages.
3355 When it appears in a <file>.changes</file> file, it lists the
3356 names of the binary packages being uploaded, separated by
3357 whitespace (not commas). It may span multiple lines.
3361 <sect1 id="f-Installed-Size">
3362 <heading><tt>Installed-Size</tt></heading>
3365 This field appears in the control files of binary packages,
3366 and in the <file>Packages</file> files. It gives an estimate
3367 of the total amount of disk space required to install the
3368 named package. Actual installed size may vary based on block
3369 size, file system properties, or actions taken by package
3374 The disk space is given as the integer value of the estimated
3375 installed size in bytes, divided by 1024 and rounded up.
3379 <sect1 id="f-Files">
3380 <heading><tt>Files</tt></heading>
3383 This field contains a list of files with information about
3384 each one. The exact information and syntax varies with
3389 In all cases, Files is a multiline field. The first line of
3390 the field value (the part on the same line as <tt>Files:</tt>)
3391 is always empty. The content of the field is expressed as
3392 continuation lines, one line per file. Each line must be
3393 indented by one space and contain a number of sub-fields,
3394 separated by spaces, as described below.
3398 In the <file>.dsc</file> file, each line contains the MD5
3399 checksum, size and filename of the tar file and (if
3400 applicable) diff file which make up the remainder of the
3401 source package<footnote>
3402 That is, the parts which are not the <tt>.dsc</tt>.
3403 </footnote>. For example:
3406 c6f698f19f2a2aa07dbb9bbda90a2754 571925 example_1.2.orig.tar.gz
3407 938512f08422f3509ff36f125f5873ba 6220 example_1.2-1.diff.gz
3409 The exact forms of the filenames are described
3410 in <ref id="pkg-sourcearchives">.
3414 In the <file>.changes</file> file this contains one line per
3415 file being uploaded. Each line contains the MD5 checksum,
3416 size, section and priority and the filename. For example:
3419 4c31ab7bfc40d3cf49d7811987390357 1428 text extra example_1.2-1.dsc
3420 c6f698f19f2a2aa07dbb9bbda90a2754 571925 text extra example_1.2.orig.tar.gz
3421 938512f08422f3509ff36f125f5873ba 6220 text extra example_1.2-1.diff.gz
3422 7c98fe853b3bbb47a00e5cd129b6cb56 703542 text extra example_1.2-1_i386.deb
3424 The <qref id="f-Section">section</qref>
3425 and <qref id="f-Priority">priority</qref> are the values of
3426 the corresponding fields in the main source control file. If
3427 no section or priority is specified then <tt>-</tt> should be
3428 used, though section and priority values must be specified for
3429 new packages to be installed properly.
3433 The special value <tt>byhand</tt> for the section in a
3434 <tt>.changes</tt> file indicates that the file in question
3435 is not an ordinary package file and must by installed by
3436 hand by the distribution maintainers. If the section is
3437 <tt>byhand</tt> the priority should be <tt>-</tt>.
3441 If a new Debian revision of a package is being shipped and
3442 no new original source archive is being distributed the
3443 <tt>.dsc</tt> must still contain the <tt>Files</tt> field
3444 entry for the original source archive
3445 <file><var>package</var>_<var>upstream-version</var>.orig.tar.gz</file>,
3446 but the <file>.changes</file> file should leave it out. In
3447 this case the original source archive on the distribution
3448 site must match exactly, byte-for-byte, the original
3449 source archive which was used to generate the
3450 <file>.dsc</file> file and diff which are being uploaded.</p>
3453 <sect1 id="f-Closes">
3454 <heading><tt>Closes</tt></heading>
3457 A space-separated list of bug report numbers that the upload
3458 governed by the .changes file closes.
3462 <sect1 id="f-Homepage">
3463 <heading><tt>Homepage</tt></heading>
3466 The URL of the web site for this package, preferably (when
3467 applicable) the site from which the original source can be
3468 obtained and any additional upstream documentation or
3469 information may be found. The content of this field is a
3470 simple URL without any surrounding characters such as
3478 <heading>User-defined fields</heading>
3481 Additional user-defined fields may be added to the
3482 source package control file. Such fields will be
3483 ignored, and not copied to (for example) binary or
3484 source package control files or upload control files.
3488 If you wish to add additional unsupported fields to
3489 these output files you should use the mechanism
3494 Fields in the main source control information file with
3495 names starting <tt>X</tt>, followed by one or more of
3496 the letters <tt>BCS</tt> and a hyphen <tt>-</tt>, will
3497 be copied to the output files. Only the part of the
3498 field name after the hyphen will be used in the output
3499 file. Where the letter <tt>B</tt> is used the field
3500 will appear in binary package control files, where the
3501 letter <tt>S</tt> is used in source package control
3502 files and where <tt>C</tt> is used in upload control
3503 (<tt>.changes</tt>) files.
3507 For example, if the main source information control file
3510 XBS-Comment: I stand between the candle and the star.
3512 then the binary and source package control files will contain the
3515 Comment: I stand between the candle and the star.
3524 <chapt id="maintainerscripts">
3525 <heading>Package maintainer scripts and installation procedure</heading>
3528 <heading>Introduction to package maintainer scripts</heading>
3531 It is possible to supply scripts as part of a package which
3532 the package management system will run for you when your
3533 package is installed, upgraded or removed.
3537 These scripts are the files <prgn>preinst</prgn>,
3538 <prgn>postinst</prgn>, <prgn>prerm</prgn> and
3539 <prgn>postrm</prgn> in the control area of the package.
3540 They must be proper executable files; if they are scripts
3541 (which is recommended), they must start with the usual
3542 <tt>#!</tt> convention. They should be readable and
3543 executable by anyone, and must not be world-writable.
3547 The package management system looks at the exit status from
3548 these scripts. It is important that they exit with a
3549 non-zero status if there is an error, so that the package
3550 management system can stop its processing. For shell
3551 scripts this means that you <em>almost always</em> need to
3552 use <tt>set -e</tt> (this is usually true when writing shell
3553 scripts, in fact). It is also important, of course, that
3554 they exit with a zero status if everything went well.
3558 Additionally, packages interacting with users using
3559 <tt>debconf</tt> in the <prgn>postinst</prgn> script should
3560 install a <prgn>config</prgn> script in the control area,
3561 see <ref id="maintscriptprompt"> for details.
3565 When a package is upgraded a combination of the scripts from
3566 the old and new packages is called during the upgrade
3567 procedure. If your scripts are going to be at all
3568 complicated you need to be aware of this, and may need to
3569 check the arguments to your scripts.
3573 Broadly speaking the <prgn>preinst</prgn> is called before
3574 (a particular version of) a package is installed, and the
3575 <prgn>postinst</prgn> afterwards; the <prgn>prerm</prgn>
3576 before (a version of) a package is removed and the
3577 <prgn>postrm</prgn> afterwards.
3581 Programs called from maintainer scripts should not normally
3582 have a path prepended to them. Before installation is
3583 started, the package management system checks to see if the
3584 programs <prgn>ldconfig</prgn>,
3585 <prgn>start-stop-daemon</prgn>, <prgn>install-info</prgn>,
3586 and <prgn>update-rc.d</prgn> can be found via the
3587 <tt>PATH</tt> environment variable. Those programs, and any
3588 other program that one would expect to be in the
3589 <tt>PATH</tt>, should thus be invoked without an absolute
3590 pathname. Maintainer scripts should also not reset the
3591 <tt>PATH</tt>, though they might choose to modify it by
3592 prepending or appending package-specific directories. These
3593 considerations really apply to all shell scripts.</p>
3596 <sect id="idempotency">
3597 <heading>Maintainer scripts idempotency</heading>
3600 It is necessary for the error recovery procedures that the
3601 scripts be idempotent. This means that if it is run
3602 successfully, and then it is called again, it doesn't bomb
3603 out or cause any harm, but just ensures that everything is
3604 the way it ought to be. If the first call failed, or
3605 aborted half way through for some reason, the second call
3606 should merely do the things that were left undone the first
3607 time, if any, and exit with a success status if everything
3609 This is so that if an error occurs, the user interrupts
3610 <prgn>dpkg</prgn> or some other unforeseen circumstance
3611 happens you don't leave the user with a badly-broken
3612 package when <prgn>dpkg</prgn> attempts to repeat the
3618 <sect id="controllingterminal">
3619 <heading>Controlling terminal for maintainer scripts</heading>
3622 Maintainer scripts are not guaranteed to run with a controlling
3623 terminal and may not be able to interact with the user. They
3624 must be able to fall back to noninteractive behavior if no
3625 controlling terminal is available. Maintainer scripts that
3626 prompt via a program conforming to the Debian Configuration
3627 Management Specification (see <ref id="maintscriptprompt">) may
3628 assume that program will handle falling back to noninteractive
3633 For high-priority prompts without a reasonable default answer,
3634 maintainer scripts may abort if there is no controlling
3635 terminal. However, this situation should be avoided if at all
3636 possible, since it prevents automated or unattended installs.
3637 In most cases, users will consider this to be a bug in the
3642 <sect id="exitstatus">
3643 <heading>Exit status</heading>
3646 Each script must return a zero exit status for
3647 success, or a nonzero one for failure, since the package
3648 management system looks for the exit status of these scripts
3649 and determines what action to take next based on that datum.
3653 <sect id="mscriptsinstact"><heading>Summary of ways maintainer
3658 <list compact="compact">
3660 <var>new-preinst</var> <tt>install</tt>
3663 <var>new-preinst</var> <tt>install</tt> <var>old-version</var>
3666 <var>new-preinst</var> <tt>upgrade</tt> <var>old-version</var>
3669 <var>old-preinst</var> <tt>abort-upgrade</tt>
3670 <var>new-version</var>
3675 <list compact="compact">
3677 <var>postinst</var> <tt>configure</tt>
3678 <var>most-recently-configured-version</var>
3681 <var>old-postinst</var> <tt>abort-upgrade</tt>
3682 <var>new-version</var>
3685 <var>conflictor's-postinst</var> <tt>abort-remove</tt>
3686 <tt>in-favour</tt> <var>package</var>
3687 <var>new-version</var>
3690 <var>postinst</var> <tt>abort-remove</tt>
3693 <var>deconfigured's-postinst</var>
3694 <tt>abort-deconfigure</tt> <tt>in-favour</tt>
3695 <var>failed-install-package</var> <var>version</var>
3696 [<tt>removing</tt> <var>conflicting-package</var>
3702 <list compact="compact">
3704 <var>prerm</var> <tt>remove</tt>
3707 <var>old-prerm</var> <tt>upgrade</tt>
3708 <var>new-version</var>
3711 <var>new-prerm</var> <tt>failed-upgrade</tt>
3712 <var>old-version</var>
3715 <var>conflictor's-prerm</var> <tt>remove</tt>
3716 <tt>in-favour</tt> <var>package</var>
3717 <var>new-version</var>
3720 <var>deconfigured's-prerm</var> <tt>deconfigure</tt>
3721 <tt>in-favour</tt> <var>package-being-installed</var>
3722 <var>version</var> [<tt>removing</tt>
3723 <var>conflicting-package</var>
3729 <list compact="compact">
3731 <var>postrm</var> <tt>remove</tt>
3734 <var>postrm</var> <tt>purge</tt>
3737 <var>old-postrm</var> <tt>upgrade</tt>
3738 <var>new-version</var>
3741 <var>new-postrm</var> <tt>failed-upgrade</tt>
3742 <var>old-version</var>
3745 <var>new-postrm</var> <tt>abort-install</tt>
3748 <var>new-postrm</var> <tt>abort-install</tt>
3749 <var>old-version</var>
3752 <var>new-postrm</var> <tt>abort-upgrade</tt>
3753 <var>old-version</var>
3756 <var>disappearer's-postrm</var> <tt>disappear</tt>
3757 <var>overwriter</var>
3758 <var>overwriter-version</var>
3764 <sect id="unpackphase">
3765 <heading>Details of unpack phase of installation or upgrade</heading>
3768 The procedure on installation/upgrade/overwrite/disappear
3769 (i.e., when running <tt>dpkg --unpack</tt>, or the unpack
3770 stage of <tt>dpkg --install</tt>) is as follows. In each
3771 case, if a major error occurs (unless listed below) the
3772 actions are, in general, run backwards - this means that the
3773 maintainer scripts are run with different arguments in
3774 reverse order. These are the "error unwind" calls listed
3781 If a version of the package is already installed, call
3782 <example compact="compact">
3783 <var>old-prerm</var> upgrade <var>new-version</var>
3787 If the script runs but exits with a non-zero
3788 exit status, <prgn>dpkg</prgn> will attempt:
3789 <example compact="compact">
3790 <var>new-prerm</var> failed-upgrade <var>old-version</var>
3792 If this works, the upgrade continues. If this
3793 does not work, the error unwind:
3794 <example compact="compact">
3795 <var>old-postinst</var> abort-upgrade <var>new-version</var>
3797 If this works, then the old-version is
3798 "Installed", if not, the old version is in a
3799 "Half-Configured" state.
3805 If a "conflicting" package is being removed at the same time,
3806 or if any package will be broken (due to <tt>Breaks</tt>):
3809 If <tt>--auto-deconfigure</tt> is
3810 specified, call, for each package to be deconfigured
3811 due to <tt>Breaks</tt>:
3812 <example compact="compact">
3813 <var>deconfigured's-prerm</var> deconfigure \
3814 in-favour <var>package-being-installed</var> <var>version</var>
3817 <example compact="compact">
3818 <var>deconfigured's-postinst</var> abort-deconfigure \
3819 in-favour <var>package-being-installed-but-failed</var> <var>version</var>
3821 The deconfigured packages are marked as
3822 requiring configuration, so that if
3823 <tt>--install</tt> is used they will be
3824 configured again if possible.
3827 If any packages depended on a conflicting
3828 package being removed and <tt>--auto-deconfigure</tt> is
3829 specified, call, for each such package:
3830 <example compact="compact">
3831 <var>deconfigured's-prerm</var> deconfigure \
3832 in-favour <var>package-being-installed</var> <var>version</var> \
3833 removing <var>conflicting-package</var> <var>version</var>
3836 <example compact="compact">
3837 <var>deconfigured's-postinst</var> abort-deconfigure \
3838 in-favour <var>package-being-installed-but-failed</var> <var>version</var> \
3839 removing <var>conflicting-package</var> <var>version</var>
3841 The deconfigured packages are marked as
3842 requiring configuration, so that if
3843 <tt>--install</tt> is used they will be
3844 configured again if possible.
3847 To prepare for removal of each conflicting package, call:
3848 <example compact="compact">
3849 <var>conflictor's-prerm</var> remove \
3850 in-favour <var>package</var> <var>new-version</var>
3853 <example compact="compact">
3854 <var>conflictor's-postinst</var> abort-remove \
3855 in-favour <var>package</var> <var>new-version</var>
3864 If the package is being upgraded, call:
3865 <example compact="compact">
3866 <var>new-preinst</var> upgrade <var>old-version</var>
3868 If this fails, we call:
3870 <var>new-postrm</var> abort-upgrade <var>old-version</var>
3877 <var>old-postinst</var> abort-upgrade <var>new-version</var>
3879 is called. If this works, then the old version
3880 is in an "Installed" state, or else it is left
3881 in an "Unpacked" state.
3886 If it fails, then the old version is left
3887 in an "Half-Installed" state.
3894 Otherwise, if the package had some configuration
3895 files from a previous version installed (i.e., it
3896 is in the "configuration files only" state):
3897 <example compact="compact">
3898 <var>new-preinst</var> install <var>old-version</var>
3902 <var>new-postrm</var> abort-install <var>old-version</var>
3904 If this fails, the package is left in a
3905 "Half-Installed" state, which requires a
3906 reinstall. If it works, the packages is left in
3907 a "Config-Files" state.
3910 Otherwise (i.e., the package was completely purged):
3911 <example compact="compact">
3912 <var>new-preinst</var> install
3915 <example compact="compact">
3916 <var>new-postrm</var> abort-install
3918 If the error-unwind fails, the package is in a
3919 "Half-Installed" phase, and requires a
3920 reinstall. If the error unwind works, the
3921 package is in a not installed state.
3928 The new package's files are unpacked, overwriting any
3929 that may be on the system already, for example any
3930 from the old version of the same package or from
3931 another package. Backups of the old files are kept
3932 temporarily, and if anything goes wrong the package
3933 management system will attempt to put them back as
3934 part of the error unwind.
3938 It is an error for a package to contain files which
3939 are on the system in another package, unless
3940 <tt>Replaces</tt> is used (see <ref id="replaces">).
3942 The following paragraph is not currently the case:
3943 Currently the <tt>- - force-overwrite</tt> flag is
3944 enabled, downgrading it to a warning, but this may not
3950 It is a more serious error for a package to contain a
3951 plain file or other kind of non-directory where another
3952 package has a directory (again, unless
3953 <tt>Replaces</tt> is used). This error can be
3954 overridden if desired using
3955 <tt>--force-overwrite-dir</tt>, but this is not
3960 Packages which overwrite each other's files produce
3961 behavior which, though deterministic, is hard for the
3962 system administrator to understand. It can easily
3963 lead to "missing" programs if, for example, a package
3964 is installed which overwrites a file from another
3965 package, and is then removed again.<footnote>
3966 Part of the problem is due to what is arguably a
3967 bug in <prgn>dpkg</prgn>.
3972 A directory will never be replaced by a symbolic link
3973 to a directory or vice versa; instead, the existing
3974 state (symlink or not) will be left alone and
3975 <prgn>dpkg</prgn> will follow the symlink if there is
3984 If the package is being upgraded, call
3985 <example compact="compact">
3986 <var>old-postrm</var> upgrade <var>new-version</var>
3990 If this fails, <prgn>dpkg</prgn> will attempt:
3991 <example compact="compact">
3992 <var>new-postrm</var> failed-upgrade <var>old-version</var>
3994 If this works, installation continues. If not,
3996 <example compact="compact">
3997 <var>old-preinst</var> abort-upgrade <var>new-version</var>
3999 If this fails, the old version is left in a
4000 "Half-Installed" state. If it works, dpkg now
4002 <example compact="compact">
4003 <var>new-postrm</var> abort-upgrade <var>old-version</var>
4005 If this fails, the old version is left in a
4006 "Half-Installed" state. If it works, dpkg now
4008 <example compact="compact">
4009 <var>old-postinst</var> abort-upgrade <var>new-version</var>
4011 If this fails, the old version is in an
4018 This is the point of no return - if
4019 <prgn>dpkg</prgn> gets this far, it won't back off
4020 past this point if an error occurs. This will
4021 leave the package in a fairly bad state, which
4022 will require a successful re-installation to clear
4023 up, but it's when <prgn>dpkg</prgn> starts doing
4024 things that are irreversible.
4029 Any files which were in the old version of the package
4030 but not in the new are removed.
4034 The new file list replaces the old.
4038 The new maintainer scripts replace the old.
4042 Any packages all of whose files have been overwritten
4043 during the installation, and which aren't required for
4044 dependencies, are considered to have been removed.
4045 For each such package
4048 <prgn>dpkg</prgn> calls:
4049 <example compact="compact">
4050 <var>disappearer's-postrm</var> disappear \
4051 <var>overwriter</var> <var>overwriter-version</var>
4055 The package's maintainer scripts are removed.
4058 It is noted in the status database as being in a
4059 sane state, namely not installed (any conffiles
4060 it may have are ignored, rather than being
4061 removed by <prgn>dpkg</prgn>). Note that
4062 disappearing packages do not have their prerm
4063 called, because <prgn>dpkg</prgn> doesn't know
4064 in advance that the package is going to
4071 Any files in the package we're unpacking that are also
4072 listed in the file lists of other packages are removed
4073 from those lists. (This will lobotomize the file list
4074 of the "conflicting" package if there is one.)
4078 The backup files made during installation, above, are
4084 The new package's status is now sane, and recorded as
4089 Here is another point of no return - if the
4090 conflicting package's removal fails we do not unwind
4091 the rest of the installation; the conflicting package
4092 is left in a half-removed limbo.
4097 If there was a conflicting package we go and do the
4098 removal actions (described below), starting with the
4099 removal of the conflicting package's files (any that
4100 are also in the package being installed have already
4101 been removed from the conflicting package's file list,
4102 and so do not get removed now).
4108 <sect id="configdetails"><heading>Details of configuration</heading>
4111 When we configure a package (this happens with <tt>dpkg
4112 --install</tt> and <tt>dpkg --configure</tt>), we first
4113 update any <tt>conffile</tt>s and then call:
4114 <example compact="compact">
4115 <var>postinst</var> configure <var>most-recently-configured-version</var>
4120 No attempt is made to unwind after errors during
4121 configuration. If the configuration fails, the package is in
4122 a "Failed Config" state, and an error message is generated.
4126 If there is no most recently configured version
4127 <prgn>dpkg</prgn> will pass a null argument.
4130 Historical note: Truly ancient (pre-1997) versions of
4131 <prgn>dpkg</prgn> passed <tt><unknown></tt>
4132 (including the angle brackets) in this case. Even older
4133 ones did not pass a second argument at all, under any
4134 circumstance. Note that upgrades using such an old dpkg
4135 version are unlikely to work for other reasons, even if
4136 this old argument behavior is handled by your postinst script.
4142 <sect id="removedetails"><heading>Details of removal and/or
4143 configuration purging</heading>
4149 <example compact="compact">
4150 <var>prerm</var> remove
4154 If prerm fails during replacement due to conflict
4156 <var>conflictor's-postinst</var> abort-remove \
4157 in-favour <var>package</var> <var>new-version</var>
4161 <var>postinst</var> abort-remove
4165 If this fails, the package is in a "Half-Configured"
4166 state, or else it remains "Installed".
4170 The package's files are removed (except <tt>conffile</tt>s).
4173 <example compact="compact">
4174 <var>postrm</var> remove
4178 If it fails, there's no error unwind, and the package is in
4179 an "Half-Installed" state.
4184 All the maintainer scripts except the <prgn>postrm</prgn>
4189 If we aren't purging the package we stop here. Note
4190 that packages which have no <prgn>postrm</prgn> and no
4191 <tt>conffile</tt>s are automatically purged when
4192 removed, as there is no difference except for the
4193 <prgn>dpkg</prgn> status.
4197 The <tt>conffile</tt>s and any backup files
4198 (<tt>~</tt>-files, <tt>#*#</tt> files,
4199 <tt>%</tt>-files, <tt>.dpkg-{old,new,tmp}</tt>, etc.)
4204 <example compact="compact">
4205 <var>postrm</var> purge
4209 If this fails, the package remains in a "Config-Files"
4214 The package's file list is removed.
4223 <chapt id="relationships">
4224 <heading>Declaring relationships between packages</heading>
4226 <sect id="depsyntax">
4227 <heading>Syntax of relationship fields</heading>
4230 These fields all have a uniform syntax. They are a list of
4231 package names separated by commas.
4235 In the <tt>Depends</tt>, <tt>Recommends</tt>,
4236 <tt>Suggests</tt>, <tt>Pre-Depends</tt>,
4237 <tt>Build-Depends</tt> and <tt>Build-Depends-Indep</tt>
4238 control file fields of the package, which declare
4239 dependencies on other packages, the package names listed may
4240 also include lists of alternative package names, separated
4241 by vertical bar (pipe) symbols <tt>|</tt>. In such a case,
4242 if any one of the alternative packages is installed, that
4243 part of the dependency is considered to be satisfied.
4247 All of the fields except for <tt>Provides</tt> may restrict
4248 their applicability to particular versions of each named
4249 package. This is done in parentheses after each individual
4250 package name; the parentheses should contain a relation from
4251 the list below followed by a version number, in the format
4252 described in <ref id="f-Version">.
4256 The relations allowed are <tt><<</tt>, <tt><=</tt>,
4257 <tt>=</tt>, <tt>>=</tt> and <tt>>></tt> for
4258 strictly earlier, earlier or equal, exactly equal, later or
4259 equal and strictly later, respectively. The deprecated
4260 forms <tt><</tt> and <tt>></tt> were used to mean
4261 earlier/later or equal, rather than strictly earlier/later,
4262 so they should not appear in new packages (though
4263 <prgn>dpkg</prgn> still supports them).
4267 Whitespace may appear at any point in the version
4268 specification subject to the rules in <ref
4269 id="controlsyntax">, and must appear where it's necessary to
4270 disambiguate; it is not otherwise significant. All of the
4271 relationship fields may span multiple lines. For
4272 consistency and in case of future changes to
4273 <prgn>dpkg</prgn> it is recommended that a single space be
4274 used after a version relationship and before a version
4275 number; it is also conventional to put a single space after
4276 each comma, on either side of each vertical bar, and before
4277 each open parenthesis. When wrapping a relationship field, it
4278 is conventional to do so after a comma and before the space
4279 following that comma.
4283 For example, a list of dependencies might appear as:
4284 <example compact="compact">
4287 Depends: libc6 (>= 2.2.1), exim | mail-transport-agent
4292 All fields that specify build-time relationships
4293 (<tt>Build-Depends</tt>, <tt>Build-Depends-Indep</tt>,
4294 <tt>Build-Conflicts</tt> and <tt>Build-Conflicts-Indep</tt>)
4295 may be restricted to a certain set of architectures. This
4296 is indicated in brackets after each individual package name and
4297 the optional version specification. The brackets enclose a
4298 list of Debian architecture names separated by whitespace.
4299 Exclamation marks may be prepended to each of the names.
4300 (It is not permitted for some names to be prepended with
4301 exclamation marks while others aren't.) If the current Debian
4302 host architecture is not in this list and there are no
4303 exclamation marks in the list, or it is in the list with a
4304 prepended exclamation mark, the package name and the
4305 associated version specification are ignored completely for
4306 the purposes of defining the relationships.
4311 <example compact="compact">
4313 Build-Depends-Indep: texinfo
4314 Build-Depends: kernel-headers-2.2.10 [!hurd-i386],
4315 hurd-dev [hurd-i386], gnumach-dev [hurd-i386]
4317 requires <tt>kernel-headers-2.2.10</tt> on all architectures
4318 other than hurd-i386 and requires <tt>hurd-dev</tt> and
4319 <tt>gnumach-dev</tt> only on hurd-i386.
4323 If the architecture-restricted dependency is part of a set of
4324 alternatives using <tt>|</tt>, that alternative is ignored
4325 completely on architectures that do not match the restriction.
4327 <example compact="compact">
4328 Build-Depends: foo [!i386] | bar [!amd64]
4330 is equivalent to <tt>bar</tt> on the i386 architecture, to
4331 <tt>foo</tt> on the amd64 architecture, and to <tt>foo |
4332 bar</tt> on all other architectures.
4336 All fields that specify build-time relationships may also be
4337 restricted to a certain set of architectures using architecture
4338 wildcards. The syntax for declaring such restrictions is the
4339 same as declaring restrictions using a certain set of
4340 architectures without architecture wildcards. For example:
4341 <example compact="compact">
4342 Build-Depends: foo [linux-any], bar [any-i386], baz [!linux-any]
4344 is equivalent to <tt>foo</tt> on architectures using the Linux
4345 kernel and any cpu, <tt>bar</tt> on architectures using any
4346 kernel and an i386 cpu, and <tt>baz</tt> on any architecture
4347 using a kernel other than Linux.
4351 Note that the binary package relationship fields such as
4352 <tt>Depends</tt> appear in one of the binary package
4353 sections of the control file, whereas the build-time
4354 relationships such as <tt>Build-Depends</tt> appear in the
4355 source package section of the control file (which is the
4360 <sect id="binarydeps">
4361 <heading>Binary Dependencies - <tt>Depends</tt>,
4362 <tt>Recommends</tt>, <tt>Suggests</tt>, <tt>Enhances</tt>,
4363 <tt>Pre-Depends</tt>
4367 Packages can declare in their control file that they have
4368 certain relationships to other packages - for example, that
4369 they may not be installed at the same time as certain other
4370 packages, and/or that they depend on the presence of others.
4374 This is done using the <tt>Depends</tt>, <tt>Pre-Depends</tt>,
4375 <tt>Recommends</tt>, <tt>Suggests</tt>, <tt>Enhances</tt>,
4376 <tt>Breaks</tt> and <tt>Conflicts</tt> control file fields.
4377 <tt>Breaks</tt> is described in <ref id="breaks">, and
4378 <tt>Conflicts</tt> is described in <ref id="conflicts">. The
4379 rest are described below.
4383 These seven fields are used to declare a dependency
4384 relationship by one package on another. Except for
4385 <tt>Enhances</tt> and <tt>Breaks</tt>, they appear in the
4386 depending (binary) package's control file.
4387 (<tt>Enhances</tt> appears in the recommending package's
4388 control file, and <tt>Breaks</tt> appears in the version of
4389 depended-on package which causes the named package to
4394 A <tt>Depends</tt> field takes effect <em>only</em> when a
4395 package is to be configured. It does not prevent a package
4396 being on the system in an unconfigured state while its
4397 dependencies are unsatisfied, and it is possible to replace
4398 a package whose dependencies are satisfied and which is
4399 properly installed with a different version whose
4400 dependencies are not and cannot be satisfied; when this is
4401 done the depending package will be left unconfigured (since
4402 attempts to configure it will give errors) and will not
4403 function properly. If it is necessary, a
4404 <tt>Pre-Depends</tt> field can be used, which has a partial
4405 effect even when a package is being unpacked, as explained
4406 in detail below. (The other three dependency fields,
4407 <tt>Recommends</tt>, <tt>Suggests</tt> and
4408 <tt>Enhances</tt>, are only used by the various front-ends
4409 to <prgn>dpkg</prgn> such as <prgn>apt-get</prgn>,
4410 <prgn>aptitude</prgn>, and <prgn>dselect</prgn>.)
4414 For this reason packages in an installation run are usually
4415 all unpacked first and all configured later; this gives
4416 later versions of packages with dependencies on later
4417 versions of other packages the opportunity to have their
4418 dependencies satisfied.
4422 In case of circular dependencies, since installation or
4423 removal order honoring the dependency order can't be
4424 established, dependency loops are broken at some point
4425 (based on rules below), and some packages may not be able to
4426 rely on their dependencies being present when being
4427 installed or removed, depending on which side of the break
4428 of the circular dependency loop they happen to be on. If one
4429 of the packages in the loop has no postinst script, then the
4430 cycle will be broken at that package, so as to ensure that
4431 all postinst scripts run with the dependencies properly
4432 configured if this is possible. Otherwise the breaking point
4437 The <tt>Depends</tt> field thus allows package maintainers
4438 to impose an order in which packages should be configured.
4442 The meaning of the five dependency fields is as follows:
4444 <tag><tt>Depends</tt></tag>
4447 This declares an absolute dependency. A package will
4448 not be configured unless all of the packages listed in
4449 its <tt>Depends</tt> field have been correctly
4454 The <tt>Depends</tt> field should be used if the
4455 depended-on package is required for the depending
4456 package to provide a significant amount of
4461 The <tt>Depends</tt> field should also be used if the
4462 <prgn>postinst</prgn>, <prgn>prerm</prgn> or
4463 <prgn>postrm</prgn> scripts require the package to be
4464 present in order to run. Note, however, that the
4465 <prgn>postrm</prgn> cannot rely on any non-essential
4466 packages to be present during the <tt>purge</tt>
4470 <tag><tt>Recommends</tt></tag>
4473 This declares a strong, but not absolute, dependency.
4477 The <tt>Recommends</tt> field should list packages
4478 that would be found together with this one in all but
4479 unusual installations.
4483 <tag><tt>Suggests</tt></tag>
4485 This is used to declare that one package may be more
4486 useful with one or more others. Using this field
4487 tells the packaging system and the user that the
4488 listed packages are related to this one and can
4489 perhaps enhance its usefulness, but that installing
4490 this one without them is perfectly reasonable.
4493 <tag><tt>Enhances</tt></tag>
4495 This field is similar to Suggests but works in the
4496 opposite direction. It is used to declare that a
4497 package can enhance the functionality of another
4501 <tag><tt>Pre-Depends</tt></tag>
4504 This field is like <tt>Depends</tt>, except that it
4505 also forces <prgn>dpkg</prgn> to complete installation
4506 of the packages named before even starting the
4507 installation of the package which declares the
4508 pre-dependency, as follows:
4512 When a package declaring a pre-dependency is about to
4513 be <em>unpacked</em> the pre-dependency can be
4514 satisfied if the depended-on package is either fully
4515 configured, <em>or even if</em> the depended-on
4516 package(s) are only unpacked or in the "Half-Configured"
4517 state, provided that they have been configured
4518 correctly at some point in the past (and not removed
4519 or partially removed since). In this case, both the
4520 previously-configured and currently unpacked or
4521 "Half-Configured" versions must satisfy any version
4522 clause in the <tt>Pre-Depends</tt> field.
4526 When the package declaring a pre-dependency is about
4527 to be <em>configured</em>, the pre-dependency will be
4528 treated as a normal <tt>Depends</tt>, that is, it will
4529 be considered satisfied only if the depended-on
4530 package has been correctly configured.
4534 <tt>Pre-Depends</tt> should be used sparingly,
4535 preferably only by packages whose premature upgrade or
4536 installation would hamper the ability of the system to
4537 continue with any upgrade that might be in progress.
4541 <tt>Pre-Depends</tt> are also required if the
4542 <prgn>preinst</prgn> script depends on the named
4543 package. It is best to avoid this situation if
4551 When selecting which level of dependency to use you should
4552 consider how important the depended-on package is to the
4553 functionality of the one declaring the dependency. Some
4554 packages are composed of components of varying degrees of
4555 importance. Such a package should list using
4556 <tt>Depends</tt> the package(s) which are required by the
4557 more important components. The other components'
4558 requirements may be mentioned as Suggestions or
4559 Recommendations, as appropriate to the components' relative
4565 <heading>Packages which break other packages - <tt>Breaks</tt></heading>
4568 When one binary package declares that it breaks another,
4569 <prgn>dpkg</prgn> will refuse to allow the package which
4570 declares <tt>Breaks</tt> be installed unless the broken
4571 package is deconfigured first, and it will refuse to
4572 allow the broken package to be reconfigured.
4576 A package will not be regarded as causing breakage merely
4577 because its configuration files are still installed; it must
4578 be at least "Half-Installed".
4582 A special exception is made for packages which declare that
4583 they break their own package name or a virtual package which
4584 they provide (see below): this does not count as a real
4589 Normally a <tt>Breaks</tt> entry will have an "earlier than"
4590 version clause; such a <tt>Breaks</tt> is introduced in the
4591 version of an (implicit or explicit) dependency which
4592 violates an assumption or reveals a bug in earlier versions
4593 of the broken package. This use of <tt>Breaks</tt> will
4594 inform higher-level package management tools that broken
4595 package must be upgraded before the new one.
4599 If the breaking package also overwrites some files from the
4600 older package, it should use <tt>Replaces</tt> (not
4601 <tt>Conflicts</tt>) to ensure this goes smoothly.
4605 <sect id="conflicts">
4606 <heading>Conflicting binary packages - <tt>Conflicts</tt></heading>
4609 When one binary package declares a conflict with another
4610 using a <tt>Conflicts</tt> field, <prgn>dpkg</prgn> will
4611 refuse to allow them to be installed on the system at the
4616 If one package is to be installed, the other must be removed
4617 first - if the package being installed is marked as
4618 replacing (see <ref id="replaces">) the one on the system,
4619 or the one on the system is marked as deselected, or both
4620 packages are marked <tt>Essential</tt>, then
4621 <prgn>dpkg</prgn> will automatically remove the package
4622 which is causing the conflict, otherwise it will halt the
4623 installation of the new package with an error. This
4624 mechanism is specifically designed to produce an error when
4625 the installed package is <tt>Essential</tt>, but the new
4630 A package will not cause a conflict merely because its
4631 configuration files are still installed; it must be at least
4636 A special exception is made for packages which declare a
4637 conflict with their own package name, or with a virtual
4638 package which they provide (see below): this does not
4639 prevent their installation, and allows a package to conflict
4640 with others providing a replacement for it. You use this
4641 feature when you want the package in question to be the only
4642 package providing some feature.
4646 A <tt>Conflicts</tt> entry should almost never have an
4647 "earlier than" version clause. This would prevent
4648 <prgn>dpkg</prgn> from upgrading or installing the package
4649 which declared such a conflict until the upgrade or removal
4650 of the conflicted-with package had been completed. Instead,
4651 <tt>Breaks</tt> may be used.
4655 <sect id="virtual"><heading>Virtual packages - <tt>Provides</tt>
4659 As well as the names of actual ("concrete") packages, the
4660 package relationship fields <tt>Depends</tt>,
4661 <tt>Recommends</tt>, <tt>Suggests</tt>, <tt>Enhances</tt>,
4662 <tt>Pre-Depends</tt>, <tt>Breaks</tt>, <tt>Conflicts</tt>,
4663 <tt>Build-Depends</tt>, <tt>Build-Depends-Indep</tt>,
4664 <tt>Build-Conflicts</tt> and <tt>Build-Conflicts-Indep</tt>
4665 may mention "virtual packages".
4669 A <em>virtual package</em> is one which appears in the
4670 <tt>Provides</tt> control file field of another package.
4671 The effect is as if the package(s) which provide a
4672 particular virtual package name had been listed by name
4673 everywhere the virtual package name appears. (See also <ref
4678 If there are both concrete and virtual packages of the same
4679 name, then the dependency may be satisfied (or the conflict
4680 caused) by either the concrete package with the name in
4681 question or any other concrete package which provides the
4682 virtual package with the name in question. This is so that,
4683 for example, supposing we have
4684 <example compact="compact">
4687 </example> and someone else releases an enhanced version of
4688 the <tt>bar</tt> package they can say:
4689 <example compact="compact">
4693 and the <tt>bar-plus</tt> package will now also satisfy the
4694 dependency for the <tt>foo</tt> package.
4698 If a relationship field has a version number attached
4699 then only real packages will be considered to see whether
4700 the relationship is satisfied (or the prohibition violated,
4701 for a conflict or breakage) - it is assumed that a real
4702 package which provides the virtual package is not of the
4703 "right" version. So, a <tt>Provides</tt> field may not
4704 contain version numbers, and the version number of the
4705 concrete package which provides a particular virtual package
4706 will not be looked at when considering a dependency on or
4707 conflict with the virtual package name.
4711 It is likely that the ability will be added in a future
4712 release of <prgn>dpkg</prgn> to specify a version number for
4713 each virtual package it provides. This feature is not yet
4714 present, however, and is expected to be used only
4719 If you want to specify which of a set of real packages
4720 should be the default to satisfy a particular dependency on
4721 a virtual package, you should list the real package as an
4722 alternative before the virtual one.
4727 <sect id="replaces"><heading>Overwriting files and replacing
4728 packages - <tt>Replaces</tt></heading>
4731 Packages can declare in their control file that they should
4732 overwrite files in certain other packages, or completely
4733 replace other packages. The <tt>Replaces</tt> control file
4734 field has these two distinct purposes.
4737 <sect1><heading>Overwriting files in other packages</heading>
4740 Firstly, as mentioned before, it is usually an error for a
4741 package to contain files which are on the system in
4746 However, if the overwriting package declares that it
4747 <tt>Replaces</tt> the one containing the file being
4748 overwritten, then <prgn>dpkg</prgn> will replace the file
4749 from the old package with that from the new. The file
4750 will no longer be listed as "owned" by the old package.
4754 For example, if a package <package>foo</package> is split
4755 into <package>foo</package> and <package>foo-data</package>
4756 starting at version 1.2-3, <package>foo-data</package> should
4758 <example compact="compact">
4759 Replaces: foo (<< 1.2-3)
4761 in its control file. The package <package>foo</package>
4762 doesn't need any special control fields in this example,
4763 although would generally depend on or
4764 recommend <package>foo-data</package>.
4768 If a package is completely replaced in this way, so that
4769 <prgn>dpkg</prgn> does not know of any files it still
4770 contains, it is considered to have "disappeared". It will
4771 be marked as not wanted on the system (selected for
4772 removal) and not installed. Any <tt>conffile</tt>s
4773 details noted for the package will be ignored, as they
4774 will have been taken over by the overwriting package. The
4775 package's <prgn>postrm</prgn> script will be run with a
4776 special argument to allow the package to do any final
4777 cleanup required. See <ref id="mscriptsinstact">.
4780 Replaces is a one way relationship -- you have to
4781 install the replacing package after the replaced
4788 For this usage of <tt>Replaces</tt>, virtual packages (see
4789 <ref id="virtual">) are not considered when looking at a
4790 <tt>Replaces</tt> field - the packages declared as being
4791 replaced must be mentioned by their real names.
4795 Furthermore, this usage of <tt>Replaces</tt> only takes
4796 effect when both packages are at least partially on the
4797 system at once, so that it can only happen if they do not
4798 conflict or if the conflict has been overridden.
4803 <sect1><heading>Replacing whole packages, forcing their
4807 Secondly, <tt>Replaces</tt> allows the packaging system to
4808 resolve which package should be removed when there is a
4809 conflict - see <ref id="conflicts">. This usage only
4810 takes effect when the two packages <em>do</em> conflict,
4811 so that the two usages of this field do not interfere with
4816 In this situation, the package declared as being replaced
4817 can be a virtual package, so for example, all mail
4818 transport agents (MTAs) would have the following fields in
4819 their control files:
4820 <example compact="compact">
4821 Provides: mail-transport-agent
4822 Conflicts: mail-transport-agent
4823 Replaces: mail-transport-agent
4825 ensuring that only one MTA can be installed at any one
4830 <sect id="sourcebinarydeps">
4831 <heading>Relationships between source and binary packages -
4832 <tt>Build-Depends</tt>, <tt>Build-Depends-Indep</tt>,
4833 <tt>Build-Conflicts</tt>, <tt>Build-Conflicts-Indep</tt>
4837 Source packages that require certain binary packages to be
4838 installed or absent at the time of building the package
4839 can declare relationships to those binary packages.
4843 This is done using the <tt>Build-Depends</tt>,
4844 <tt>Build-Depends-Indep</tt>, <tt>Build-Conflicts</tt> and
4845 <tt>Build-Conflicts-Indep</tt> control file fields.
4849 Build-dependencies on "build-essential" binary packages can be
4850 omitted. Please see <ref id="pkg-relations"> for more information.
4854 The dependencies and conflicts they define must be satisfied
4855 (as defined earlier for binary packages) in order to invoke
4856 the targets in <tt>debian/rules</tt>, as follows:<footnote>
4858 There is no Build-Depends-Arch; this role is essentially
4859 met with Build-Depends. Anyone building the
4860 <tt>build-indep</tt> and binary-indep<tt></tt> targets is
4861 assumed to be building the whole package, and therefore
4862 installation of all build dependencies is required.
4865 The autobuilders use <tt>dpkg-buildpackage -B</tt>, which
4866 calls <tt>build</tt>, not <tt>build-arch</tt> since it does
4867 not yet know how to check for its existence, and
4868 <tt>binary-arch</tt>. The purpose of the original split
4869 between <tt>Build-Depends</tt> and
4870 <tt>Build-Depends-Indep</tt> was so that the autobuilders
4871 wouldn't need to install extra packages needed only for the
4872 binary-indep targets. But without a build-arch/build-indep
4873 split, this didn't work, since most of the work is done in
4874 the build target, not in the binary target.
4878 <tag><tt>clean</tt>, <tt>build-arch</tt>, and
4879 <tt>binary-arch</tt></tag>
4881 Only the <tt>Build-Depends</tt> and <tt>Build-Conflicts</tt>
4882 fields must be satisfied when these targets are invoked.
4884 <tag><tt>build</tt>, <tt>build-indep</tt>, <tt>binary</tt>,
4885 and <tt>binary-indep</tt></tag>
4887 The <tt>Build-Depends</tt>, <tt>Build-Conflicts</tt>,
4888 <tt>Build-Depends-Indep</tt>, and
4889 <tt>Build-Conflicts-Indep</tt> fields must be satisfied when
4890 these targets are invoked.
4898 <chapt id="sharedlibs"><heading>Shared libraries</heading>
4901 Packages containing shared libraries must be constructed with
4902 a little care to make sure that the shared library is always
4903 available. This is especially important for packages whose
4904 shared libraries are vitally important, such as the C library
4905 (currently <tt>libc6</tt>).
4909 Packages involving shared libraries should be split up into
4910 several binary packages. This section mostly deals with how
4911 this separation is to be accomplished; rules for files within
4912 the shared library packages are in <ref id="libraries"> instead.
4915 <sect id="sharedlibs-runtime">
4916 <heading>Run-time shared libraries</heading>
4919 The run-time shared library needs to be placed in a package
4920 whose name changes whenever the shared object version
4923 Since it is common place to install several versions of a
4924 package that just provides shared libraries, it is a
4925 good idea that the library package should not
4926 contain any extraneous non-versioned files, unless they
4927 happen to be in versioned directories.</p>
4929 The most common mechanism is to place it in a package
4931 <package><var>libraryname</var><var>soversion</var></package>,
4932 where <file><var>soversion</var></file> is the version number
4933 in the soname of the shared library<footnote>
4934 The soname is the shared object name: it's the thing
4935 that has to match exactly between building an executable
4936 and running it for the dynamic linker to be able run the
4937 program. For example, if the soname of the library is
4938 <file>libfoo.so.6</file>, the library package would be
4939 called <file>libfoo6</file>.
4941 Alternatively, if it would be confusing to directly append
4942 <var>soversion</var> to <var>libraryname</var> (e.g. because
4943 <var>libraryname</var> itself ends in a number), you may use
4944 <package><var>libraryname</var>-<var>soversion</var></package> and
4945 <package><var>libraryname</var>-<var>soversion</var>-dev</package>
4950 If you have several shared libraries built from the same
4951 source tree you may lump them all together into a single
4952 shared library package, provided that you change all of
4953 their sonames at once (so that you don't get filename
4954 clashes if you try to install different versions of the
4955 combined shared libraries package).
4959 The package should install the shared libraries under
4960 their normal names. For example, the <package>libgdbm3</package>
4961 package should install <file>libgdbm.so.3.0.0</file> as
4962 <file>/usr/lib/libgdbm.so.3.0.0</file>. The files should not be
4963 renamed or re-linked by any <prgn>prerm</prgn> or
4964 <prgn>postrm</prgn> scripts; <prgn>dpkg</prgn> will take care
4965 of renaming things safely without affecting running programs,
4966 and attempts to interfere with this are likely to lead to
4971 Shared libraries should not be installed executable, since
4972 the dynamic linker does not require this and trying to
4973 execute a shared library usually results in a core dump.
4977 The run-time library package should include the symbolic link that
4978 <prgn>ldconfig</prgn> would create for the shared libraries.
4979 For example, the <package>libgdbm3</package> package should include
4980 a symbolic link from <file>/usr/lib/libgdbm.so.3</file> to
4981 <file>libgdbm.so.3.0.0</file>. This is needed so that the dynamic
4982 linker (for example <prgn>ld.so</prgn> or
4983 <prgn>ld-linux.so.*</prgn>) can find the library between the
4984 time that <prgn>dpkg</prgn> installs it and the time that
4985 <prgn>ldconfig</prgn> is run in the <prgn>postinst</prgn>
4987 The package management system requires the library to be
4988 placed before the symbolic link pointing to it in the
4989 <file>.deb</file> file. This is so that when
4990 <prgn>dpkg</prgn> comes to install the symlink
4991 (overwriting the previous symlink pointing at an older
4992 version of the library), the new shared library is already
4993 in place. In the past, this was achieved by creating the
4994 library in the temporary packaging directory before
4995 creating the symlink. Unfortunately, this was not always
4996 effective, since the building of the tar file in the
4997 <file>.deb</file> depended on the behavior of the underlying
4998 file system. Some file systems (such as reiserfs) reorder
4999 the files so that the order of creation is forgotten.
5000 Since version 1.7.0, <prgn>dpkg</prgn>
5001 reorders the files itself as necessary when building a
5002 package. Thus it is no longer important to concern
5003 oneself with the order of file creation.
5007 <sect1 id="ldconfig">
5008 <heading><tt>ldconfig</tt></heading>
5011 Any package installing shared libraries in one of the default
5012 library directories of the dynamic linker (which are currently
5013 <file>/usr/lib</file> and <file>/lib</file>) or a directory that is
5014 listed in <file>/etc/ld.so.conf</file><footnote>
5016 <list compact="compact">
5017 <item>/usr/local/lib</item>
5018 <item>/usr/lib/libc5-compat</item>
5019 <item>/lib/libc5-compat</item>
5022 must use <prgn>ldconfig</prgn> to update the shared library
5027 The package maintainer scripts must only call
5028 <prgn>ldconfig</prgn> under these circumstances:
5029 <list compact="compact">
5030 <item>When the <prgn>postinst</prgn> script is run with a
5031 first argument of <tt>configure</tt>, the script must call
5032 <prgn>ldconfig</prgn>, and may optionally invoke
5033 <prgn>ldconfig</prgn> at other times.
5035 <item>When the <prgn>postrm</prgn> script is run with a
5036 first argument of <tt>remove</tt>, the script should call
5037 <prgn>ldconfig</prgn>.
5042 During install or upgrade, the preinst is called before
5043 the new files are installed, so calling "ldconfig" is
5044 pointless. The preinst of an existing package can also be
5045 called if an upgrade fails. However, this happens during
5046 the critical time when a shared libs may exist on-disk
5047 under a temporary name. Thus, it is dangerous and
5048 forbidden by current policy to call "ldconfig" at this
5053 When a package is installed or upgraded, "postinst
5054 configure" runs after the new files are safely on-disk.
5055 Since it is perfectly safe to invoke ldconfig
5056 unconditionally in a postinst, it is OK for a package to
5057 simply put ldconfig in its postinst without checking the
5058 argument. The postinst can also be called to recover from
5059 a failed upgrade. This happens before any new files are
5060 unpacked, so there is no reason to call "ldconfig" at this
5065 For a package that is being removed, prerm is
5066 called with all the files intact, so calling ldconfig is
5067 useless. The other calls to "prerm" happen in the case of
5068 upgrade at a time when all the files of the old package
5069 are on-disk, so again calling "ldconfig" is pointless.
5073 postrm, on the other hand, is called with the "remove"
5074 argument just after the files are removed, so this is
5075 the proper time to call "ldconfig" to notify the system
5076 of the fact that the shared libraries from the package
5077 are removed. The postrm can be called at several other
5078 times. At the time of "postrm purge", "postrm
5079 abort-install", or "postrm abort-upgrade", calling
5080 "ldconfig" is useless because the shared lib files are
5081 not on-disk. However, when "postrm" is invoked with
5082 arguments "upgrade", "failed-upgrade", or "disappear", a
5083 shared lib may exist on-disk under a temporary filename.
5091 <sect id="sharedlibs-support-files">
5092 <heading>Shared library support files</heading>
5095 If your package contains files whose names do not change with
5096 each change in the library shared object version, you must not
5097 put them in the shared library package. Otherwise, several
5098 versions of the shared library cannot be installed at the same
5099 time without filename clashes, making upgrades and transitions
5100 unnecessarily difficult.
5104 It is recommended that supporting files and run-time support
5105 programs that do not need to be invoked manually by users, but
5106 are nevertheless required for the package to function, be placed
5107 (if they are binary) in a subdirectory of <file>/usr/lib</file>,
5108 preferably under <file>/usr/lib/</file><var>package-name</var>.
5109 If the program or file is architecture independent, the
5110 recommendation is for it to be placed in a subdirectory of
5111 <file>/usr/share</file> instead, preferably under
5112 <file>/usr/share/</file><var>package-name</var>. Following the
5113 <var>package-name</var> naming convention ensures that the file
5114 names change when the shared object version changes.
5118 Run-time support programs that use the shared library but are
5119 not required for the library to function or files used by the
5120 shared library that can be used by any version of the shared
5121 library package should instead be put in a separate package.
5122 This package might typically be named
5123 <package><var>libraryname</var>-tools</package>; note the
5124 absence of the <var>soversion</var> in the package name.
5128 Files and support programs only useful when compiling software
5129 against the library should be included in the development
5130 package for the library.<footnote>
5131 For example, a <file><var>package-name</var>-config</file>
5132 script or <package>pkg-config</package> configuration files.
5137 <sect id="sharedlibs-static">
5138 <heading>Static libraries</heading>
5141 The static library (<file><var>libraryname.a</var></file>)
5142 is usually provided in addition to the shared version.
5143 It is placed into the development package (see below).
5147 In some cases, it is acceptable for a library to be
5148 available in static form only; these cases include:
5150 <item>libraries for languages whose shared library support
5151 is immature or unstable</item>
5152 <item>libraries whose interfaces are in flux or under
5153 development (commonly the case when the library's
5154 major version number is zero, or where the ABI breaks
5155 across patchlevels)</item>
5156 <item>libraries which are explicitly intended to be
5157 available only in static form by their upstream
5162 <sect id="sharedlibs-dev">
5163 <heading>Development files</heading>
5166 The development files associated to a shared library need to be
5167 placed in a package called
5168 <package><var>libraryname</var><var>soversion</var>-dev</package>,
5169 or if you prefer only to support one development version at a
5170 time, <package><var>libraryname</var>-dev</package>.
5174 In case several development versions of a library exist, you may
5175 need to use <prgn>dpkg</prgn>'s Conflicts mechanism (see
5176 <ref id="conflicts">) to ensure that the user only installs one
5177 development version at a time (as different development versions are
5178 likely to have the same header files in them, which would cause a
5179 filename clash if both were installed).
5183 The development package should contain a symlink for the associated
5184 shared library without a version number. For example, the
5185 <package>libgdbm-dev</package> package should include a symlink
5186 from <file>/usr/lib/libgdbm.so</file> to
5187 <file>libgdbm.so.3.0.0</file>. This symlink is needed by the linker
5188 (<prgn>ld</prgn>) when compiling packages, as it will only look for
5189 <file>libgdbm.so</file> when compiling dynamically.
5193 <sect id="sharedlibs-intradeps">
5194 <heading>Dependencies between the packages of the same library</heading>
5197 Typically the development version should have an exact
5198 version dependency on the runtime library, to make sure that
5199 compilation and linking happens correctly. The
5200 <tt>${binary:Version}</tt> substitution variable can be
5201 useful for this purpose.
5203 Previously, <tt>${Source-Version}</tt> was used, but its name
5204 was confusing and it has been deprecated since dpkg 1.13.19.
5209 <sect id="sharedlibs-shlibdeps">
5210 <heading>Dependencies between the library and other packages -
5211 the <tt>shlibs</tt> system</heading>
5214 If a package contains a binary or library which links to a
5215 shared library, we must ensure that when the package is
5216 installed on the system, all of the libraries needed are
5217 also installed. This requirement led to the creation of the
5218 <tt>shlibs</tt> system, which is very simple in its design:
5219 any package which <em>provides</em> a shared library also
5220 provides information on the package dependencies required to
5221 ensure the presence of this library, and any package which
5222 <em>uses</em> a shared library uses this information to
5223 determine the dependencies it requires. The files which
5224 contain the mapping from shared libraries to the necessary
5225 dependency information are called <file>shlibs</file> files.
5229 Thus, when a package is built which contains any shared
5230 libraries, it must provide a <file>shlibs</file> file for other
5231 packages to use, and when a package is built which contains
5232 any shared libraries or compiled binaries, it must run
5233 <qref id="pkg-dpkg-shlibdeps"><prgn>dpkg-shlibdeps</prgn></qref>
5234 on these to determine the libraries used and hence the
5235 dependencies needed by this package.<footnote>
5237 In the past, the shared libraries linked to were
5238 determined by calling <prgn>ldd</prgn>, but now
5239 <prgn>objdump</prgn> is used to do this. The only
5240 change this makes to package building is that
5241 <prgn>dpkg-shlibdeps</prgn> must also be run on shared
5242 libraries, whereas in the past this was unnecessary.
5243 The rest of this footnote explains the advantage that
5248 We say that a binary <tt>foo</tt> <em>directly</em> uses
5249 a library <tt>libbar</tt> if it is explicitly linked
5250 with that library (that is, it uses the flag
5251 <tt>-lbar</tt> during the linking stage). Other
5252 libraries that are needed by <tt>libbar</tt> are linked
5253 <em>indirectly</em> to <tt>foo</tt>, and the dynamic
5254 linker will load them automatically when it loads
5255 <tt>libbar</tt>. A package should depend on
5256 the libraries it directly uses, and the dependencies for
5257 those libraries should automatically pull in the other
5262 Unfortunately, the <prgn>ldd</prgn> program shows both
5263 the directly and indirectly used libraries, meaning that
5264 the dependencies determined included both direct and
5265 indirect dependencies. The use of <prgn>objdump</prgn>
5266 avoids this problem by determining only the directly
5271 A good example of where this helps is the following. We
5272 could update <tt>libimlib</tt> with a new version that
5273 supports a new graphics format called dgf (but retaining
5274 the same major version number). If we used the old
5275 <prgn>ldd</prgn> method, every package that uses
5276 <tt>libimlib</tt> would need to be recompiled so it
5277 would also depend on <tt>libdgf</tt> or it wouldn't run
5278 due to missing symbols. However with the new system,
5279 packages using <tt>libimlib</tt> can rely on
5280 <tt>libimlib</tt> itself having the dependency on
5281 <tt>libdgf</tt> and so they would not need rebuilding.
5287 In the following sections, we will first describe where the
5288 various <tt>shlibs</tt> files are to be found, then how to
5289 use <prgn>dpkg-shlibdeps</prgn>, and finally the <tt>shlibs</tt>
5290 file format and how to create them if your package contains a
5295 <heading>The <tt>shlibs</tt> files present on the system</heading>
5298 There are several places where <tt>shlibs</tt> files are
5299 found. The following list gives them in the order in which
5301 <qref id="pkg-dpkg-shlibdeps"><prgn>dpkg-shlibdeps</prgn></qref>.
5302 (The first one which gives the required information is used.)
5308 <p><file>debian/shlibs.local</file></p>
5311 This lists overrides for this package. Its use is
5312 described below (see <ref id="shlibslocal">).
5317 <p><file>/etc/dpkg/shlibs.override</file></p>
5320 This lists global overrides. This list is normally
5321 empty. It is maintained by the local system
5327 <p><file>DEBIAN/shlibs</file> files in the "build directory"</p>
5330 When packages are being built, any
5331 <file>debian/shlibs</file> files are copied into the
5332 control file area of the temporary build directory and
5333 given the name <file>shlibs</file>. These files give
5334 details of any shared libraries included in the
5336 An example may help here. Let us say that the
5337 source package <tt>foo</tt> generates two binary
5338 packages, <tt>libfoo2</tt> and
5339 <tt>foo-runtime</tt>. When building the binary
5340 packages, the two packages are created in the
5341 directories <file>debian/libfoo2</file> and
5342 <file>debian/foo-runtime</file> respectively.
5343 (<file>debian/tmp</file> could be used instead of one
5344 of these.) Since <tt>libfoo2</tt> provides the
5345 <tt>libfoo</tt> shared library, it will require a
5346 <tt>shlibs</tt> file, which will be installed in
5347 <file>debian/libfoo2/DEBIAN/shlibs</file>, eventually
5349 <file>/var/lib/dpkg/info/libfoo2.shlibs</file>. Then
5350 when <prgn>dpkg-shlibdeps</prgn> is run on the
5352 <file>debian/foo-runtime/usr/bin/foo-prog</file>, it
5354 <file>debian/libfoo2/DEBIAN/shlibs</file> file to
5355 determine whether <tt>foo-prog</tt>'s library
5356 dependencies are satisfied by any of the libraries
5357 provided by <tt>libfoo2</tt>. For this reason,
5358 <prgn>dpkg-shlibdeps</prgn> must only be run once
5359 all of the individual binary packages'
5360 <tt>shlibs</tt> files have been installed into the
5367 <p><file>/var/lib/dpkg/info/*.shlibs</file></p>
5370 These are the <file>shlibs</file> files corresponding to
5371 all of the packages installed on the system, and are
5372 maintained by the relevant package maintainers.
5377 <p><file>/etc/dpkg/shlibs.default</file></p>
5380 This file lists any shared libraries whose packages
5381 have failed to provide correct <file>shlibs</file> files.
5382 It was used when the <file>shlibs</file> setup was first
5383 introduced, but it is now normally empty. It is
5384 maintained by the <tt>dpkg</tt> maintainer.
5392 <heading>How to use <prgn>dpkg-shlibdeps</prgn> and the
5393 <file>shlibs</file> files</heading>
5397 <qref id="pkg-dpkg-shlibdeps"><prgn>dpkg-shlibdeps</prgn></qref>
5398 into your <file>debian/rules</file> file. If your package
5399 contains only compiled binaries and libraries (but no scripts),
5400 you can use a command such as:
5401 <example compact="compact">
5402 dpkg-shlibdeps debian/tmp/usr/bin/* debian/tmp/usr/sbin/* \
5403 debian/tmp/usr/lib/*
5405 Otherwise, you will need to explicitly list the compiled
5406 binaries and libraries.<footnote>
5407 If you are using <tt>debhelper</tt>, the
5408 <prgn>dh_shlibdeps</prgn> program will do this work for
5409 you. It will also correctly handle multi-binary
5415 This command puts the dependency information into the
5416 <file>debian/substvars</file> file, which is then used by
5417 <prgn>dpkg-gencontrol</prgn>. You will need to place a
5418 <tt>${shlibs:Depends}</tt> variable in the <tt>Depends</tt>
5419 field in the control file for this to work.
5423 If <prgn>dpkg-shlibdeps</prgn> doesn't complain, you're
5424 done. If it does complain you might need to create your own
5425 <file>debian/shlibs.local</file> file, as explained below (see
5426 <ref id="shlibslocal">).
5430 If you have multiple binary packages, you will need to call
5431 <prgn>dpkg-shlibdeps</prgn> on each one which contains
5432 compiled libraries or binaries. In such a case, you will
5433 need to use the <tt>-T</tt> option to the <tt>dpkg</tt>
5434 utilities to specify a different <file>substvars</file> file.
5438 If you are creating a udeb for use in the Debian Installer,
5439 you will need to specify that <prgn>dpkg-shlibdeps</prgn>
5440 should use the dependency line of type <tt>udeb</tt> by
5441 adding the <tt>-tudeb</tt> option<footnote>
5442 <prgn>dh_shlibdeps</prgn> from the <tt>debhelper</tt> suite
5443 will automatically add this option if it knows it is
5445 </footnote>. If there is no dependency line of type <tt>udeb</tt>
5446 in the <file>shlibs</file> file, <prgn>dpkg-shlibdeps</prgn> will
5447 fall back to the regular dependency line.
5451 For more details on dpkg-shlibdeps, please see
5452 <ref id="pkg-dpkg-shlibdeps"> and
5453 <manref name="dpkg-shlibdeps" section="1">.
5458 <heading>The <file>shlibs</file> File Format</heading>
5461 Each <file>shlibs</file> file has the same format. Lines
5462 beginning with <tt>#</tt> are considered to be comments and
5463 are ignored. Each line is of the form:
5464 <example compact="compact">
5465 [<var>type</var>: ]<var>library-name</var> <var>soname-version</var> <var>dependencies ...</var>
5470 We will explain this by reference to the example of the
5471 <tt>zlib1g</tt> package, which (at the time of writing)
5472 installs the shared library <file>/usr/lib/libz.so.1.1.3</file>.
5476 <var>type</var> is an optional element that indicates the type
5477 of package for which the line is valid. The only type currently
5478 in use is <tt>udeb</tt>. The colon and space after the type are
5483 <var>library-name</var> is the name of the shared library,
5484 in this case <tt>libz</tt>. (This must match the name part
5485 of the soname, see below.)
5489 <var>soname-version</var> is the version part of the soname of
5490 the library. The soname is the thing that must exactly match
5491 for the library to be recognized by the dynamic linker, and is
5493 <tt><var>name</var>.so.<var>major-version</var></tt>, in our
5494 example, <tt>libz.so.1</tt>.<footnote>
5495 This can be determined using the command
5496 <example compact="compact">
5497 objdump -p /usr/lib/libz.so.1.1.3 | grep SONAME
5500 The version part is the part which comes after
5501 <tt>.so.</tt>, so in our case, it is <tt>1</tt>.
5505 <var>dependencies</var> has the same syntax as a dependency
5506 field in a binary package control file. It should give
5507 details of which packages are required to satisfy a binary
5508 built against the version of the library contained in the
5509 package. See <ref id="depsyntax"> for details.
5513 In our example, if the first version of the <tt>zlib1g</tt>
5514 package which contained a minor number of at least
5515 <tt>1.3</tt> was <var>1:1.1.3-1</var>, then the
5516 <tt>shlibs</tt> entry for this library could say:
5517 <example compact="compact">
5518 libz 1 zlib1g (>= 1:1.1.3)
5520 The version-specific dependency is to avoid warnings from
5521 the dynamic linker about using older shared libraries with
5526 As zlib1g also provides a udeb containing the shared library,
5527 there would also be a second line:
5528 <example compact="compact">
5529 udeb: libz 1 zlib1g-udeb (>= 1:1.1.3)
5535 <heading>Providing a <file>shlibs</file> file</heading>
5538 If your package provides a shared library, you need to create
5539 a <file>shlibs</file> file following the format described above.
5540 It is usual to call this file <file>debian/shlibs</file> (but if
5541 you have multiple binary packages, you might want to call it
5542 <file>debian/shlibs.<var>package</var></file> instead). Then
5543 let <file>debian/rules</file> install it in the control area:
5544 <example compact="compact">
5545 install -m644 debian/shlibs debian/tmp/DEBIAN
5547 or, in the case of a multi-binary package:
5548 <example compact="compact">
5549 install -m644 debian/shlibs.<var>package</var> debian/<var>package</var>/DEBIAN/shlibs
5551 An alternative way of doing this is to create the
5552 <file>shlibs</file> file in the control area directly from
5553 <file>debian/rules</file> without using a <file>debian/shlibs</file>
5554 file at all,<footnote>
5555 This is what <prgn>dh_makeshlibs</prgn> in the
5556 <tt>debhelper</tt> suite does. If your package also has a udeb
5557 that provides a shared library, <prgn>dh_makeshlibs</prgn> can
5558 automatically generate the <tt>udeb:</tt> lines if you specify
5559 the name of the udeb with the <tt>--add-udeb</tt> option.
5561 since the <file>debian/shlibs</file> file itself is ignored by
5562 <prgn>dpkg-shlibdeps</prgn>.
5566 As <prgn>dpkg-shlibdeps</prgn> reads the
5567 <file>DEBIAN/shlibs</file> files in all of the binary packages
5568 being built from this source package, all of the
5569 <file>DEBIAN/shlibs</file> files should be installed before
5570 <prgn>dpkg-shlibdeps</prgn> is called on any of the binary
5575 <sect1 id="shlibslocal">
5576 <heading>Writing the <file>debian/shlibs.local</file> file</heading>
5579 This file is intended only as a <em>temporary</em> fix if
5580 your binaries or libraries depend on a library whose package
5581 does not yet provide a correct <file>shlibs</file> file.
5585 We will assume that you are trying to package a binary
5586 <tt>foo</tt>. When you try running
5587 <prgn>dpkg-shlibdeps</prgn> you get the following error
5588 message (<tt>-O</tt> displays the dependency information on
5589 <tt>stdout</tt> instead of writing it to
5590 <tt>debian/substvars</tt>, and the lines have been wrapped
5591 for ease of reading):
5592 <example compact="compact">
5593 $ dpkg-shlibdeps -O debian/tmp/usr/bin/foo
5594 dpkg-shlibdeps: warning: unable to find dependency
5595 information for shared library libbar (soname 1,
5596 path /usr/lib/libbar.so.1, dependency field Depends)
5597 shlibs:Depends=libc6 (>= 2.2.2-2)
5599 You can then run <prgn>ldd</prgn> on the binary to find the
5600 full location of the library concerned:
5601 <example compact="compact">
5603 libbar.so.1 => /usr/lib/libbar.so.1 (0x4001e000)
5604 libc.so.6 => /lib/libc.so.6 (0x40032000)
5605 /lib/ld-linux.so.2 => /lib/ld-linux.so.2 (0x40000000)
5607 So the <prgn>foo</prgn> binary depends on the
5608 <prgn>libbar</prgn> shared library, but no package seems to
5609 provide a <file>*.shlibs</file> file handling
5610 <file>libbar.so.1</file> in <file>/var/lib/dpkg/info/</file>. Let's
5611 determine the package responsible:
5612 <example compact="compact">
5613 $ dpkg -S /usr/lib/libbar.so.1
5614 bar1: /usr/lib/libbar.so.1
5615 $ dpkg -s bar1 | grep Version
5618 This tells us that the <tt>bar1</tt> package, version 1.0-1,
5619 is the one we are using. Now we can file a bug against the
5620 <tt>bar1</tt> package and create our own
5621 <file>debian/shlibs.local</file> to locally fix the problem.
5622 Including the following line into your
5623 <file>debian/shlibs.local</file> file:
5624 <example compact="compact">
5625 libbar 1 bar1 (>= 1.0-1)
5627 should allow the package build to work.
5631 As soon as the maintainer of <tt>bar1</tt> provides a
5632 correct <file>shlibs</file> file, you should remove this line
5633 from your <file>debian/shlibs.local</file> file. (You should
5634 probably also then have a versioned <tt>Build-Depends</tt>
5635 on <tt>bar1</tt> to help ensure that others do not have the
5636 same problem building your package.)
5645 <chapt id="opersys"><heading>The Operating System</heading>
5648 <heading>File system hierarchy</heading>
5652 <heading>File System Structure</heading>
5655 The location of all installed files and directories must
5656 comply with the Filesystem Hierarchy Standard (FHS),
5657 version 2.3, with the exceptions noted below, and except
5658 where doing so would violate other terms of Debian
5659 Policy. The following exceptions to the FHS apply:
5664 The optional rules related to user specific
5665 configuration files for applications are stored in
5666 the user's home directory are relaxed. It is
5667 recommended that such files start with the
5668 '<tt>.</tt>' character (a "dot file"), and if an
5669 application needs to create more than one dot file
5670 then the preferred placement is in a subdirectory
5671 with a name starting with a '.' character, (a "dot
5672 directory"). In this case it is recommended the
5673 configuration files not start with the '.'
5679 The requirement for amd64 to use <file>/lib64</file>
5680 for 64 bit binaries is removed.
5685 The requirement for object files, internal binaries, and
5686 libraries, including <file>libc.so.*</file>, to be located
5687 directly under <file>/lib{,32}</file> and
5688 <file>/usr/lib{,32}</file> is amended, permitting files
5689 to instead be installed to
5690 <file>/lib/<var>triplet</var></file> and
5691 <file>/usr/lib/<var>triplet</var></file>, where
5692 <tt><var>triplet</var></tt> is the value returned by
5693 <tt>dpkg-architecture -qDEB_HOST_GNU_TYPE</tt> for the
5694 architecture of the package. Packages may <em>not</em>
5695 install files to any <var>triplet</var> path other
5696 than the one matching the architecture of that package;
5697 for instance, an <tt>Architecture: amd64</tt> package
5698 containing 32-bit x86 libraries may not install these
5699 libraries to <file>/usr/lib/i486-linux-gnu</file>.
5701 This is necessary in order to reserve the directories for
5702 use in cross-installation of library packages from other
5703 architectures, as part of the planned deployment of
5708 Applications may also use a single subdirectory under
5709 <file>/usr/lib/<var>triplet</var></file>.
5712 The execution time linker/loader, ld*, must still be made
5713 available in the existing location under /lib or /lib64
5714 since this is part of the ELF ABI for the architecture.
5719 The requirement that
5720 <file>/usr/local/share/man</file> be "synonymous"
5721 with <file>/usr/local/man</file> is relaxed to a
5726 The requirement that windowmanagers with a single
5727 configuration file call it <file>system.*wmrc</file>
5728 is removed, as is the restriction that the window
5729 manager subdirectory be named identically to the
5730 window manager name itself.
5735 The requirement that boot manager configuration
5736 files live in <file>/etc</file>, or at least are
5737 symlinked there, is relaxed to a recommendation.
5742 The following directories in the root filesystem are
5743 additionally allowed: <file>/sys</file> and
5744 <file>/selinux</file>. <footnote>These directories
5745 are used as mount points to mount virtual filesystems
5746 to get access to kernel information.</footnote>
5753 The version of this document referred here can be
5754 found in the <tt>debian-policy</tt> package or on <url
5755 id="http://www.debian.org/doc/packaging-manuals/fhs/"
5756 name="FHS (Debian copy)"> alongside this manual (or, if
5757 you have the <package>debian-policy</package> installed,
5759 id="file:///usr/share/doc/debian-policy/fhs/" name="FHS
5760 (local copy)">). The
5761 latest version, which may be a more recent version, may
5763 <url id="http://www.pathname.com/fhs/" name="FHS (upstream)">.
5764 Specific questions about following the standard may be
5765 asked on the <tt>debian-devel</tt> mailing list, or
5766 referred to the FHS mailing list (see the
5767 <url id="http://www.pathname.com/fhs/" name="FHS web site"> for
5773 <heading>Site-specific programs</heading>
5776 As mandated by the FHS, packages must not place any
5777 files in <file>/usr/local</file>, either by putting them in
5778 the file system archive to be unpacked by <prgn>dpkg</prgn>
5779 or by manipulating them in their maintainer scripts.
5783 However, the package may create empty directories below
5784 <file>/usr/local</file> so that the system administrator knows
5785 where to place site-specific files. These are not
5786 directories <em>in</em> <file>/usr/local</file>, but are
5787 children of directories in <file>/usr/local</file>. These
5788 directories (<file>/usr/local/*/dir/</file>)
5789 should be removed on package removal if they are
5794 Note that this applies only to
5795 directories <em>below</em> <file>/usr/local</file>,
5796 not <em>in</em> <file>/usr/local</file>. Packages must
5797 not create sub-directories in the
5798 directory <file>/usr/local</file> itself, except those
5799 listed in FHS, section 4.5. However, you may create
5800 directories below them as you wish. You must not remove
5801 any of the directories listed in 4.5, even if you created
5806 Since <file>/usr/local</file> can be mounted read-only from a
5807 remote server, these directories must be created and
5808 removed by the <prgn>postinst</prgn> and <prgn>prerm</prgn>
5809 maintainer scripts and not be included in the
5810 <file>.deb</file> archive. These scripts must not fail if
5811 either of these operations fail.
5815 For example, the <tt>emacsen-common</tt> package could
5816 contain something like
5817 <example compact="compact">
5818 if [ ! -e /usr/local/share/emacs ]
5820 if mkdir /usr/local/share/emacs 2>/dev/null
5822 chown root:staff /usr/local/share/emacs
5823 chmod 2775 /usr/local/share/emacs
5827 in its <prgn>postinst</prgn> script, and
5828 <example compact="compact">
5829 rmdir /usr/local/share/emacs/site-lisp 2>/dev/null || true
5830 rmdir /usr/local/share/emacs 2>/dev/null || true
5832 in the <prgn>prerm</prgn> script. (Note that this form is
5833 used to ensure that if the script is interrupted, the
5834 directory <file>/usr/local/share/emacs</file> will still be
5839 If you do create a directory in <file>/usr/local</file> for
5840 local additions to a package, you should ensure that
5841 settings in <file>/usr/local</file> take precedence over the
5842 equivalents in <file>/usr</file>.
5846 However, because <file>/usr/local</file> and its contents are
5847 for exclusive use of the local administrator, a package
5848 must not rely on the presence or absence of files or
5849 directories in <file>/usr/local</file> for normal operation.
5853 The <file>/usr/local</file> directory itself and all the
5854 subdirectories created by the package should (by default) have
5855 permissions 2775 (group-writable and set-group-id) and be
5856 owned by <tt>root:staff</tt>.
5861 <heading>The system-wide mail directory</heading>
5863 The system-wide mail directory
5864 is <file>/var/mail</file>. This directory is part of the
5865 base system and should not be owned by any particular mail
5866 agents. The use of the old
5867 location <file>/var/spool/mail</file> is deprecated, even
5868 though the spool may still be physically located there.
5874 <heading>Users and groups</heading>
5877 <heading>Introduction</heading>
5879 The Debian system can be configured to use either plain or
5884 Some user ids (UIDs) and group ids (GIDs) are reserved
5885 globally for use by certain packages. Because some
5886 packages need to include files which are owned by these
5887 users or groups, or need the ids compiled into binaries,
5888 these ids must be used on any Debian system only for the
5889 purpose for which they are allocated. This is a serious
5890 restriction, and we should avoid getting in the way of
5891 local administration policies. In particular, many sites
5892 allocate users and/or local system groups starting at 100.
5896 Apart from this we should have dynamically allocated ids,
5897 which should by default be arranged in some sensible
5898 order, but the behavior should be configurable.
5902 Packages other than <tt>base-passwd</tt> must not modify
5903 <file>/etc/passwd</file>, <file>/etc/shadow</file>,
5904 <file>/etc/group</file> or <file>/etc/gshadow</file>.
5909 <heading>UID and GID classes</heading>
5911 The UID and GID numbers are divided into classes as
5917 Globally allocated by the Debian project, the same
5918 on every Debian system. These ids will appear in
5919 the <file>passwd</file> and <file>group</file> files of all
5920 Debian systems, new ids in this range being added
5921 automatically as the <tt>base-passwd</tt> package is
5926 Packages which need a single statically allocated
5927 uid or gid should use one of these; their
5928 maintainers should ask the <tt>base-passwd</tt>
5936 Dynamically allocated system users and groups.
5937 Packages which need a user or group, but can have
5938 this user or group allocated dynamically and
5939 differently on each system, should use <tt>adduser
5940 --system</tt> to create the group and/or user.
5941 <prgn>adduser</prgn> will check for the existence of
5942 the user or group, and if necessary choose an unused
5943 id based on the ranges specified in
5944 <file>adduser.conf</file>.
5948 <tag>1000-59999:</tag>
5951 Dynamically allocated user accounts. By default
5952 <prgn>adduser</prgn> will choose UIDs and GIDs for
5953 user accounts in this range, though
5954 <file>adduser.conf</file> may be used to modify this
5959 <tag>60000-64999:</tag>
5962 Globally allocated by the Debian project, but only
5963 created on demand. The ids are allocated centrally
5964 and statically, but the actual accounts are only
5965 created on users' systems on demand.
5969 These ids are for packages which are obscure or
5970 which require many statically-allocated ids. These
5971 packages should check for and create the accounts in
5972 <file>/etc/passwd</file> or <file>/etc/group</file> (using
5973 <prgn>adduser</prgn> if it has this facility) if
5974 necessary. Packages which are likely to require
5975 further allocations should have a "hole" left after
5976 them in the allocation, to give them room to
5981 <tag>65000-65533:</tag>
5989 User <tt>nobody</tt>. The corresponding gid refers
5990 to the group <tt>nogroup</tt>.
5997 <tt>(uid_t)(-1) == (gid_t)(-1)</tt> <em>must
5998 not</em> be used, because it is the error return
6007 <sect id="sysvinit">
6008 <heading>System run levels and <file>init.d</file> scripts</heading>
6010 <sect1 id="/etc/init.d">
6011 <heading>Introduction</heading>
6014 The <file>/etc/init.d</file> directory contains the scripts
6015 executed by <prgn>init</prgn> at boot time and when the
6016 init state (or "runlevel") is changed (see <manref
6017 name="init" section="8">).
6021 There are at least two different, yet functionally
6022 equivalent, ways of handling these scripts. For the sake
6023 of simplicity, this document describes only the symbolic
6024 link method. However, it must not be assumed by maintainer
6025 scripts that this method is being used, and any automated
6026 manipulation of the various runlevel behaviors by
6027 maintainer scripts must be performed using
6028 <prgn>update-rc.d</prgn> as described below and not by
6029 manually installing or removing symlinks. For information
6030 on the implementation details of the other method,
6031 implemented in the <tt>file-rc</tt> package, please refer
6032 to the documentation of that package.
6036 These scripts are referenced by symbolic links in the
6037 <file>/etc/rc<var>n</var>.d</file> directories. When changing
6038 runlevels, <prgn>init</prgn> looks in the directory
6039 <file>/etc/rc<var>n</var>.d</file> for the scripts it should
6040 execute, where <tt><var>n</var></tt> is the runlevel that
6041 is being changed to, or <tt>S</tt> for the boot-up
6046 The names of the links all have the form
6047 <file>S<var>mm</var><var>script</var></file> or
6048 <file>K<var>mm</var><var>script</var></file> where
6049 <var>mm</var> is a two-digit number and <var>script</var>
6050 is the name of the script (this should be the same as the
6051 name of the actual script in <file>/etc/init.d</file>).
6055 When <prgn>init</prgn> changes runlevel first the targets
6056 of the links whose names start with a <tt>K</tt> are
6057 executed, each with the single argument <tt>stop</tt>,
6058 followed by the scripts prefixed with an <tt>S</tt>, each
6059 with the single argument <tt>start</tt>. (The links are
6060 those in the <file>/etc/rc<var>n</var>.d</file> directory
6061 corresponding to the new runlevel.) The <tt>K</tt> links
6062 are responsible for killing services and the <tt>S</tt>
6063 link for starting services upon entering the runlevel.
6067 For example, if we are changing from runlevel 2 to
6068 runlevel 3, init will first execute all of the <tt>K</tt>
6069 prefixed scripts it finds in <file>/etc/rc3.d</file>, and then
6070 all of the <tt>S</tt> prefixed scripts in that directory.
6071 The links starting with <tt>K</tt> will cause the
6072 referred-to file to be executed with an argument of
6073 <tt>stop</tt>, and the <tt>S</tt> links with an argument
6078 The two-digit number <var>mm</var> is used to determine
6079 the order in which to run the scripts: low-numbered links
6080 have their scripts run first. For example, the
6081 <tt>K20</tt> scripts will be executed before the
6082 <tt>K30</tt> scripts. This is used when a certain service
6083 must be started before another. For example, the name
6084 server <prgn>bind</prgn> might need to be started before
6085 the news server <prgn>inn</prgn> so that <prgn>inn</prgn>
6086 can set up its access lists. In this case, the script
6087 that starts <prgn>bind</prgn> would have a lower number
6088 than the script that starts <prgn>inn</prgn> so that it
6090 <example compact="compact">
6097 The two runlevels 0 (halt) and 6 (reboot) are slightly
6098 different. In these runlevels, the links with an
6099 <tt>S</tt> prefix are still called after those with a
6100 <tt>K</tt> prefix, but they too are called with the single
6101 argument <tt>stop</tt>.
6105 <sect1 id="writing-init">
6106 <heading>Writing the scripts</heading>
6109 Packages that include daemons for system services should
6110 place scripts in <file>/etc/init.d</file> to start or stop
6111 services at boot time or during a change of runlevel.
6112 These scripts should be named
6113 <file>/etc/init.d/<var>package</var></file>, and they should
6114 accept one argument, saying what to do:
6117 <tag><tt>start</tt></tag>
6118 <item>start the service,</item>
6120 <tag><tt>stop</tt></tag>
6121 <item>stop the service,</item>
6123 <tag><tt>restart</tt></tag>
6124 <item>stop and restart the service if it's already running,
6125 otherwise start the service</item>
6127 <tag><tt>reload</tt></tag>
6128 <item><p>cause the configuration of the service to be
6129 reloaded without actually stopping and restarting
6132 <tag><tt>force-reload</tt></tag>
6133 <item>cause the configuration to be reloaded if the
6134 service supports this, otherwise restart the
6138 The <tt>start</tt>, <tt>stop</tt>, <tt>restart</tt>, and
6139 <tt>force-reload</tt> options should be supported by all
6140 scripts in <file>/etc/init.d</file>, the <tt>reload</tt>
6145 The <file>init.d</file> scripts must ensure that they will
6146 behave sensibly (i.e., returning success and not starting
6147 multiple copies of a service) if invoked with <tt>start</tt>
6148 when the service is already running, or with <tt>stop</tt>
6149 when it isn't, and that they don't kill unfortunately-named
6150 user processes. The best way to achieve this is usually to
6151 use <prgn>start-stop-daemon</prgn> with the <tt>--oknodo</tt>
6156 Be careful of using <tt>set -e</tt> in <file>init.d</file>
6157 scripts. Writing correct <file>init.d</file> scripts requires
6158 accepting various error exit statuses when daemons are already
6159 running or already stopped without aborting
6160 the <file>init.d</file> script, and common <file>init.d</file>
6161 function libraries are not safe to call with <tt>set -e</tt>
6163 <tt>/lib/lsb/init-functions</tt>, which assists in writing
6164 LSB-compliant init scripts, may fail if <tt>set -e</tt> is
6165 in effect and echoing status messages to the console fails,
6167 </footnote>. For <tt>init.d</tt> scripts, it's often easier
6168 to not use <tt>set -e</tt> and instead check the result of
6169 each command separately.
6173 If a service reloads its configuration automatically (as
6174 in the case of <prgn>cron</prgn>, for example), the
6175 <tt>reload</tt> option of the <file>init.d</file> script
6176 should behave as if the configuration has been reloaded
6181 The <file>/etc/init.d</file> scripts must be treated as
6182 configuration files, either (if they are present in the
6183 package, that is, in the .deb file) by marking them as
6184 <tt>conffile</tt>s, or, (if they do not exist in the .deb)
6185 by managing them correctly in the maintainer scripts (see
6186 <ref id="config-files">). This is important since we want
6187 to give the local system administrator the chance to adapt
6188 the scripts to the local system, e.g., to disable a
6189 service without de-installing the package, or to specify
6190 some special command line options when starting a service,
6191 while making sure their changes aren't lost during the next
6196 These scripts should not fail obscurely when the
6197 configuration files remain but the package has been
6198 removed, as configuration files remain on the system after
6199 the package has been removed. Only when <prgn>dpkg</prgn>
6200 is executed with the <tt>--purge</tt> option will
6201 configuration files be removed. In particular, as the
6202 <file>/etc/init.d/<var>package</var></file> script itself is
6203 usually a <tt>conffile</tt>, it will remain on the system
6204 if the package is removed but not purged. Therefore, you
6205 should include a <tt>test</tt> statement at the top of the
6207 <example compact="compact">
6208 test -f <var>program-executed-later-in-script</var> || exit 0
6213 Often there are some variables in the <file>init.d</file>
6214 scripts whose values control the behavior of the scripts,
6215 and which a system administrator is likely to want to
6216 change. As the scripts themselves are frequently
6217 <tt>conffile</tt>s, modifying them requires that the
6218 administrator merge in their changes each time the package
6219 is upgraded and the <tt>conffile</tt> changes. To ease
6220 the burden on the system administrator, such configurable
6221 values should not be placed directly in the script.
6222 Instead, they should be placed in a file in
6223 <file>/etc/default</file>, which typically will have the same
6224 base name as the <file>init.d</file> script. This extra file
6225 should be sourced by the script when the script runs. It
6226 must contain only variable settings and comments in SUSv3
6227 <prgn>sh</prgn> format. It may either be a
6228 <tt>conffile</tt> or a configuration file maintained by
6229 the package maintainer scripts. See <ref id="config-files">
6234 To ensure that vital configurable values are always
6235 available, the <file>init.d</file> script should set default
6236 values for each of the shell variables it uses, either
6237 before sourcing the <file>/etc/default/</file> file or
6238 afterwards using something like the <tt>:
6239 ${VAR:=default}</tt> syntax. Also, the <file>init.d</file>
6240 script must behave sensibly and not fail if the
6241 <file>/etc/default</file> file is deleted.
6245 <file>/var/run</file> and <file>/var/lock</file> may be mounted
6246 as temporary filesystems<footnote>
6247 For example, using the <tt>RAMRUN</tt> and <tt>RAMLOCK</tt>
6248 options in <file>/etc/default/rcS</file>.
6249 </footnote>, so the <file>init.d</file> scripts must handle this
6250 correctly. This will typically amount to creating any required
6251 subdirectories dynamically when the <file>init.d</file> script
6252 is run, rather than including them in the package and relying on
6253 <prgn>dpkg</prgn> to create them.
6258 <heading>Interfacing with the initscript system</heading>
6261 Maintainers should use the abstraction layer provided by
6262 the <prgn>update-rc.d</prgn> and <prgn>invoke-rc.d</prgn>
6263 programs to deal with initscripts in their packages'
6264 scripts such as <prgn>postinst</prgn>, <prgn>prerm</prgn>
6265 and <prgn>postrm</prgn>.
6269 Directly managing the /etc/rc?.d links and directly
6270 invoking the <file>/etc/init.d/</file> initscripts should
6271 be done only by packages providing the initscript
6272 subsystem (such as <prgn>sysv-rc</prgn> and
6273 <prgn>file-rc</prgn>).
6277 <heading>Managing the links</heading>
6280 The program <prgn>update-rc.d</prgn> is provided for
6281 package maintainers to arrange for the proper creation and
6282 removal of <file>/etc/rc<var>n</var>.d</file> symbolic links,
6283 or their functional equivalent if another method is being
6284 used. This may be used by maintainers in their packages'
6285 <prgn>postinst</prgn> and <prgn>postrm</prgn> scripts.
6289 You must not include any <file>/etc/rc<var>n</var>.d</file>
6290 symbolic links in the actual archive or manually create or
6291 remove the symbolic links in maintainer scripts; you must
6292 use the <prgn>update-rc.d</prgn> program instead. (The
6293 former will fail if an alternative method of maintaining
6294 runlevel information is being used.) You must not include
6295 the <file>/etc/rc<var>n</var>.d</file> directories themselves
6296 in the archive either. (Only the <tt>sysvinit</tt>
6301 By default <prgn>update-rc.d</prgn> will start services in
6302 each of the multi-user state runlevels (2, 3, 4, and 5)
6303 and stop them in the halt runlevel (0), the single-user
6304 runlevel (1) and the reboot runlevel (6). The system
6305 administrator will have the opportunity to customize
6306 runlevels by simply adding, moving, or removing the
6307 symbolic links in <file>/etc/rc<var>n</var>.d</file> if
6308 symbolic links are being used, or by modifying
6309 <file>/etc/runlevel.conf</file> if the <tt>file-rc</tt> method
6314 To get the default behavior for your package, put in your
6315 <prgn>postinst</prgn> script
6316 <example compact="compact">
6317 update-rc.d <var>package</var> defaults
6319 and in your <prgn>postrm</prgn>
6320 <example compact="compact">
6321 if [ "$1" = purge ]; then
6322 update-rc.d <var>package</var> remove
6324 </example>. Note that if your package changes runlevels
6325 or priority, you may have to remove and recreate the links,
6326 since otherwise the old links may persist. Refer to the
6327 documentation of <prgn>update-rc.d</prgn>.
6331 This will use a default sequence number of 20. If it does
6332 not matter when or in which order the <file>init.d</file>
6333 script is run, use this default. If it does, then you
6334 should talk to the maintainer of the <prgn>sysvinit</prgn>
6335 package or post to <tt>debian-devel</tt>, and they will
6336 help you choose a number.
6340 For more information about using <tt>update-rc.d</tt>,
6341 please consult its man page <manref name="update-rc.d"
6347 <heading>Running initscripts</heading>
6349 The program <prgn>invoke-rc.d</prgn> is provided to make
6350 it easier for package maintainers to properly invoke an
6351 initscript, obeying runlevel and other locally-defined
6352 constraints that might limit a package's right to start,
6353 stop and otherwise manage services. This program may be
6354 used by maintainers in their packages' scripts.
6358 The package maintainer scripts must use
6359 <prgn>invoke-rc.d</prgn> to invoke the
6360 <file>/etc/init.d/*</file> initscripts, instead of
6361 calling them directly.
6365 By default, <prgn>invoke-rc.d</prgn> will pass any
6366 action requests (start, stop, reload, restart...) to the
6367 <file>/etc/init.d</file> script, filtering out requests
6368 to start or restart a service out of its intended
6373 Most packages will simply need to change:
6374 <example compact="compact">/etc/init.d/<package>
6375 <action></example> in their <prgn>postinst</prgn>
6376 and <prgn>prerm</prgn> scripts to:
6377 <example compact="compact">
6378 if which invoke-rc.d >/dev/null 2>&1; then
6379 invoke-rc.d <var>package</var> <action>
6381 /etc/init.d/<var>package</var> <action>
6387 A package should register its initscript services using
6388 <prgn>update-rc.d</prgn> before it tries to invoke them
6389 using <prgn>invoke-rc.d</prgn>. Invocation of
6390 unregistered services may fail.
6394 For more information about using
6395 <prgn>invoke-rc.d</prgn>, please consult its man page
6396 <manref name="invoke-rc.d" section="8">.
6402 <heading>Boot-time initialization</heading>
6405 There used to be another directory, <file>/etc/rc.boot</file>,
6406 which contained scripts which were run once per machine
6407 boot. This has been deprecated in favour of links from
6408 <file>/etc/rcS.d</file> to files in <file>/etc/init.d</file> as
6409 described in <ref id="/etc/init.d">. Packages must not
6410 place files in <file>/etc/rc.boot</file>.
6415 <heading>Example</heading>
6418 An example on which you can base your
6419 <file>/etc/init.d</file> scripts is found in
6420 <file>/etc/init.d/skeleton</file>.
6427 <heading>Console messages from <file>init.d</file> scripts</heading>
6430 This section describes the formats to be used for messages
6431 written to standard output by the <file>/etc/init.d</file>
6432 scripts. The intent is to improve the consistency of
6433 Debian's startup and shutdown look and feel. For this
6434 reason, please look very carefully at the details. We want
6435 the messages to have the same format in terms of wording,
6436 spaces, punctuation and case of letters.
6440 Here is a list of overall rules that should be used for
6441 messages generated by <file>/etc/init.d</file> scripts.
6447 The message should fit in one line (fewer than 80
6448 characters), start with a capital letter and end with
6449 a period (<tt>.</tt>) and line feed (<tt>"\n"</tt>).
6453 If the script is performing some time consuming task in
6454 the background (not merely starting or stopping a
6455 program, for instance), an ellipsis (three dots:
6456 <tt>...</tt>) should be output to the screen, with no
6457 leading or tailing whitespace or line feeds.
6461 The messages should appear as if the computer is telling
6462 the user what it is doing (politely :-), but should not
6463 mention "it" directly. For example, instead of:
6464 <example compact="compact">
6465 I'm starting network daemons: nfsd mountd.
6467 the message should say
6468 <example compact="compact">
6469 Starting network daemons: nfsd mountd.
6476 <tt>init.d</tt> script should use the following standard
6477 message formats for the situations enumerated below.
6483 <p>When daemons are started</p>
6486 If the script starts one or more daemons, the output
6487 should look like this (a single line, no leading
6489 <example compact="compact">
6490 Starting <var>description</var>: <var>daemon-1</var> ... <var>daemon-n</var>.
6492 The <var>description</var> should describe the
6493 subsystem the daemon or set of daemons are part of,
6494 while <var>daemon-1</var> up to <var>daemon-n</var>
6495 denote each daemon's name (typically the file name of
6500 For example, the output of <file>/etc/init.d/lpd</file>
6502 <example compact="compact">
6503 Starting printer spooler: lpd.
6508 This can be achieved by saying
6509 <example compact="compact">
6510 echo -n "Starting printer spooler: lpd"
6511 start-stop-daemon --start --quiet --exec /usr/sbin/lpd
6514 in the script. If there are more than one daemon to
6515 start, the output should look like this:
6516 <example compact="compact">
6517 echo -n "Starting remote file system services:"
6518 echo -n " nfsd"; start-stop-daemon --start --quiet nfsd
6519 echo -n " mountd"; start-stop-daemon --start --quiet mountd
6520 echo -n " ugidd"; start-stop-daemon --start --quiet ugidd
6523 This makes it possible for the user to see what is
6524 happening and when the final daemon has been started.
6525 Care should be taken in the placement of white spaces:
6526 in the example above the system administrators can
6527 easily comment out a line if they don't want to start
6528 a specific daemon, while the displayed message still
6534 <p>When a system parameter is being set</p>
6537 If you have to set up different system parameters
6538 during the system boot, you should use this format:
6539 <example compact="compact">
6540 Setting <var>parameter</var> to "<var>value</var>".
6545 You can use a statement such as the following to get
6547 <example compact="compact">
6548 echo "Setting DNS domainname to \"$domainname\"."
6553 Note that the same symbol (<tt>"</tt>) <!-- " --> is used
6554 for the left and right quotation marks. A grave accent
6555 (<tt>`</tt>) is not a quote character; neither is an
6556 apostrophe (<tt>'</tt>).
6561 <p>When a daemon is stopped or restarted</p>
6564 When you stop or restart a daemon, you should issue a
6565 message identical to the startup message, except that
6566 <tt>Starting</tt> is replaced with <tt>Stopping</tt>
6567 or <tt>Restarting</tt> respectively.
6571 For example, stopping the printer daemon will look like
6573 <example compact="compact">
6574 Stopping printer spooler: lpd.
6580 <p>When something is executed</p>
6583 There are several examples where you have to run a
6584 program at system startup or shutdown to perform a
6585 specific task, for example, setting the system's clock
6586 using <prgn>netdate</prgn> or killing all processes
6587 when the system shuts down. Your message should look
6589 <example compact="compact">
6590 Doing something very useful...done.
6592 You should print the <tt>done.</tt> immediately after
6593 the job has been completed, so that the user is
6594 informed why they have to wait. You can get this
6596 <example compact="compact">
6597 echo -n "Doing something very useful..."
6606 <p>When the configuration is reloaded</p>
6609 When a daemon is forced to reload its configuration
6610 files you should use the following format:
6611 <example compact="compact">
6612 Reloading <var>description</var> configuration...done.
6614 where <var>description</var> is the same as in the
6615 daemon starting message.
6623 <heading>Cron jobs</heading>
6626 Packages must not modify the configuration file
6627 <file>/etc/crontab</file>, and they must not modify the files in
6628 <file>/var/spool/cron/crontabs</file>.</p>
6631 If a package wants to install a job that has to be executed
6632 via cron, it should place a file with the name of the
6633 package in one or more of the following directories:
6634 <example compact="compact">
6640 As these directory names imply, the files within them are
6641 executed on an hourly, daily, weekly, or monthly basis,
6642 respectively. The exact times are listed in
6643 <file>/etc/crontab</file>.</p>
6646 All files installed in any of these directories must be
6647 scripts (e.g., shell scripts or Perl scripts) so that they
6648 can easily be modified by the local system administrator.
6649 In addition, they must be treated as configuration files.
6653 If a certain job has to be executed at some other frequency or
6654 at a specific time, the package should install a file
6655 <file>/etc/cron.d/<var>package</var></file>. This file uses the
6656 same syntax as <file>/etc/crontab</file> and is processed by
6657 <prgn>cron</prgn> automatically. The file must also be
6658 treated as a configuration file. (Note that entries in the
6659 <file>/etc/cron.d</file> directory are not handled by
6660 <prgn>anacron</prgn>. Thus, you should only use this
6661 directory for jobs which may be skipped if the system is not
6664 Unlike <file>crontab</file> files described in the IEEE Std
6665 1003.1-2008 (POSIX.1) available from
6666 <url id="http://www.opengroup.org/onlinepubs/9699919799/"
6667 name="The Open Group">, the files in
6668 <file>/etc/cron.d</file> and the file
6669 <file>/etc/crontab</file> have seven fields; namely:
6671 <item>Minute [0,59]</item>
6672 <item>Hour [0,23]</item>
6673 <item>Day of the month [1,31]</item>
6674 <item>Month of the year [1,12]</item>
6675 <item>Day of the week ([0,6] with 0=Sunday)</item>
6676 <item>Username</item>
6677 <item>Command to be run</item>
6679 Ranges of numbers are allowed. Ranges are two numbers
6680 separated with a hyphen. The specified range is inclusive.
6681 Lists are allowed. A list is a set of numbers (or ranges)
6682 separated by commas. Step values can be used in conjunction
6687 The scripts or <tt>crontab</tt> entries in these directories should
6688 check if all necessary programs are installed before they
6689 try to execute them. Otherwise, problems will arise when a
6690 package was removed but not purged since configuration files
6691 are kept on the system in this situation.
6695 Any <tt>cron</tt> daemon must provide
6696 <file>/usr/bin/crontab</file> and support normal
6697 <tt>crontab</tt> entries as specified in POSIX. The daemon
6698 must also support names for days and months, ranges, and
6699 step values. It has to support <file>/etc/crontab</file>,
6700 and correctly execute the scripts in
6701 <file>/etc/cron.d</file>. The daemon must also correctly
6703 <file>/etc/cron.{hourly,daily,weekly,monthly}</file>.
6708 <heading>Menus</heading>
6711 The Debian <tt>menu</tt> package provides a standard
6712 interface between packages providing applications and
6713 <em>menu programs</em> (either X window managers or
6714 text-based menu programs such as <prgn>pdmenu</prgn>).
6718 All packages that provide applications that need not be
6719 passed any special command line arguments for normal
6720 operation should register a menu entry for those
6721 applications, so that users of the <tt>menu</tt> package
6722 will automatically get menu entries in their window
6723 managers, as well in shells like <tt>pdmenu</tt>.
6727 Menu entries should follow the current menu policy.
6731 The menu policy can be found in the <tt>menu-policy</tt>
6732 files in the <tt>debian-policy</tt> package.
6733 It is also available from the Debian web mirrors at
6734 <tt><url name="/doc/packaging-manuals/menu-policy/"
6735 id="http://www.debian.org/doc/packaging-manuals/menu-policy/"></tt>.
6739 Please also refer to the <em>Debian Menu System</em>
6740 documentation that comes with the <package>menu</package>
6741 package for information about how to register your
6747 <heading>Multimedia handlers</heading>
6750 MIME (Multipurpose Internet Mail Extensions, RFCs 2045-2049)
6751 is a mechanism for encoding files and data streams and
6752 providing meta-information about them, in particular their
6753 type (e.g. audio or video) and format (e.g. PNG, HTML,
6758 Registration of MIME type handlers allows programs like mail
6759 user agents and web browsers to invoke these handlers to
6760 view, edit or display MIME types they don't support directly.
6764 Packages which provide the ability to view/show/play,
6765 compose, edit or print MIME types should register themselves
6766 as such following the current MIME support policy.
6770 The MIME support policy can be found in the <tt>mime-policy</tt>
6771 files in the <tt>debian-policy</tt> package.
6772 It is also available from the Debian web mirrors at
6773 <tt><url name="/doc/packaging-manuals/mime-policy/"
6774 id="http://www.debian.org/doc/packaging-manuals/mime-policy/"></tt>.
6780 <heading>Keyboard configuration</heading>
6783 To achieve a consistent keyboard configuration so that all
6784 applications interpret a keyboard event the same way, all
6785 programs in the Debian distribution must be configured to
6786 comply with the following guidelines.
6790 The following keys must have the specified interpretations:
6793 <tag><tt><--</tt></tag>
6794 <item>delete the character to the left of the cursor</item>
6796 <tag><tt>Delete</tt></tag>
6797 <item>delete the character to the right of the cursor</item>
6799 <tag><tt>Control+H</tt></tag>
6800 <item>emacs: the help prefix</item>
6803 The interpretation of any keyboard events should be
6804 independent of the terminal that is used, be it a virtual
6805 console, an X terminal emulator, an rlogin/telnet session,
6810 The following list explains how the different programs
6811 should be set up to achieve this:
6817 <tt><--</tt> generates <tt>KB_BackSpace</tt> in X.
6821 <tt>Delete</tt> generates <tt>KB_Delete</tt> in X.
6825 X translations are set up to make
6826 <tt>KB_Backspace</tt> generate ASCII DEL, and to make
6827 <tt>KB_Delete</tt> generate <tt>ESC [ 3 ~</tt> (this
6828 is the vt220 escape code for the "delete character"
6829 key). This must be done by loading the X resources
6830 using <prgn>xrdb</prgn> on all local X displays, not
6831 using the application defaults, so that the
6832 translation resources used correspond to the
6833 <prgn>xmodmap</prgn> settings.
6837 The Linux console is configured to make
6838 <tt><--</tt> generate DEL, and <tt>Delete</tt>
6839 generate <tt>ESC [ 3 ~</tt>.
6843 X applications are configured so that <tt><</tt>
6844 deletes left, and <tt>Delete</tt> deletes right. Motif
6845 applications already work like this.
6849 Terminals should have <tt>stty erase ^?</tt> .
6853 The <tt>xterm</tt> terminfo entry should have <tt>ESC
6854 [ 3 ~</tt> for <tt>kdch1</tt>, just as for
6855 <tt>TERM=linux</tt> and <tt>TERM=vt220</tt>.
6859 Emacs is programmed to map <tt>KB_Backspace</tt> or
6860 the <tt>stty erase</tt> character to
6861 <tt>delete-backward-char</tt>, and <tt>KB_Delete</tt>
6862 or <tt>kdch1</tt> to <tt>delete-forward-char</tt>, and
6863 <tt>^H</tt> to <tt>help</tt> as always.
6867 Other applications use the <tt>stty erase</tt>
6868 character and <tt>kdch1</tt> for the two delete keys,
6869 with ASCII DEL being "delete previous character" and
6870 <tt>kdch1</tt> being "delete character under
6878 This will solve the problem except for the following
6885 Some terminals have a <tt><--</tt> key that cannot
6886 be made to produce anything except <tt>^H</tt>. On
6887 these terminals Emacs help will be unavailable on
6888 <tt>^H</tt> (assuming that the <tt>stty erase</tt>
6889 character takes precedence in Emacs, and has been set
6890 correctly). <tt>M-x help</tt> or <tt>F1</tt> (if
6891 available) can be used instead.
6895 Some operating systems use <tt>^H</tt> for <tt>stty
6896 erase</tt>. However, modern telnet versions and all
6897 rlogin versions propagate <tt>stty</tt> settings, and
6898 almost all UNIX versions honour <tt>stty erase</tt>.
6899 Where the <tt>stty</tt> settings are not propagated
6900 correctly, things can be made to work by using
6901 <tt>stty</tt> manually.
6905 Some systems (including previous Debian versions) use
6906 <prgn>xmodmap</prgn> to arrange for both
6907 <tt><--</tt> and <tt>Delete</tt> to generate
6908 <tt>KB_Delete</tt>. We can change the behavior of
6909 their X clients using the same X resources that we use
6910 to do it for our own clients, or configure our clients
6911 using their resources when things are the other way
6912 around. On displays configured like this
6913 <tt>Delete</tt> will not work, but <tt><--</tt>
6918 Some operating systems have different <tt>kdch1</tt>
6919 settings in their <tt>terminfo</tt> database for
6920 <tt>xterm</tt> and others. On these systems the
6921 <tt>Delete</tt> key will not work correctly when you
6922 log in from a system conforming to our policy, but
6923 <tt><--</tt> will.
6930 <heading>Environment variables</heading>
6933 A program must not depend on environment variables to get
6934 reasonable defaults. (That's because these environment
6935 variables would have to be set in a system-wide
6936 configuration file like <file>/etc/profile</file>, which is not
6937 supported by all shells.)
6941 If a program usually depends on environment variables for its
6942 configuration, the program should be changed to fall back to
6943 a reasonable default configuration if these environment
6944 variables are not present. If this cannot be done easily
6945 (e.g., if the source code of a non-free program is not
6946 available), the program must be replaced by a small
6947 "wrapper" shell script which sets the environment variables
6948 if they are not already defined, and calls the original program.
6952 Here is an example of a wrapper script for this purpose:
6954 <example compact="compact">
6956 BAR=${BAR:-/var/lib/fubar}
6958 exec /usr/lib/foo/foo "$@"
6963 Furthermore, as <file>/etc/profile</file> is a configuration
6964 file of the <prgn>base-files</prgn> package, other packages must
6965 not put any environment variables or other commands into that
6970 <sect id="doc-base">
6971 <heading>Registering Documents using doc-base</heading>
6974 The <package>doc-base</package> package implements a
6975 flexible mechanism for handling and presenting
6976 documentation. The recommended practice is for every Debian
6977 package that provides online documentation (other than just
6978 manual pages) to register these documents with
6979 <package>doc-base</package> by installing a
6980 <package>doc-base</package> control file via the
6981 <prgn/install-docs/ script at installation time and
6982 de-register the manuals again when the package is removed.
6985 Please refer to the documentation that comes with the
6986 <package>doc-base</package> package for information and
6995 <heading>Files</heading>
6998 <heading>Binaries</heading>
7001 Two different packages must not install programs with
7002 different functionality but with the same filenames. (The
7003 case of two programs having the same functionality but
7004 different implementations is handled via "alternatives" or
7005 the "Conflicts" mechanism. See <ref id="maintscripts"> and
7006 <ref id="conflicts"> respectively.) If this case happens,
7007 one of the programs must be renamed. The maintainers should
7008 report this to the <tt>debian-devel</tt> mailing list and
7009 try to find a consensus about which program will have to be
7010 renamed. If a consensus cannot be reached, <em>both</em>
7011 programs must be renamed.
7015 By default, when a package is being built, any binaries
7016 created should include debugging information, as well as
7017 being compiled with optimization. You should also turn on
7018 as many reasonable compilation warnings as possible; this
7019 makes life easier for porters, who can then look at build
7020 logs for possible problems. For the C programming language,
7021 this means the following compilation parameters should be
7023 <example compact="compact">
7025 CFLAGS = -O2 -g -Wall # sane warning options vary between programs
7027 INSTALL = install -s # (or use strip on the files in debian/tmp)
7032 Note that by default all installed binaries should be stripped,
7033 either by using the <tt>-s</tt> flag to
7034 <prgn>install</prgn>, or by calling <prgn>strip</prgn> on
7035 the binaries after they have been copied into
7036 <file>debian/tmp</file> but before the tree is made into a
7041 Although binaries in the build tree should be compiled with
7042 debugging information by default, it can often be difficult to
7043 debug programs if they are also subjected to compiler
7044 optimization. For this reason, it is recommended to support the
7045 standardized environment variable <tt>DEB_BUILD_OPTIONS</tt>
7046 (see <ref id="debianrules-options">). This variable can contain
7047 several flags to change how a package is compiled and built.
7051 It is up to the package maintainer to decide what
7052 compilation options are best for the package. Certain
7053 binaries (such as computationally-intensive programs) will
7054 function better with certain flags (<tt>-O3</tt>, for
7055 example); feel free to use them. Please use good judgment
7056 here. Don't use flags for the sake of it; only use them
7057 if there is good reason to do so. Feel free to override
7058 the upstream author's ideas about which compilation
7059 options are best: they are often inappropriate for our
7065 <sect id="libraries">
7066 <heading>Libraries</heading>
7069 If the package is <strong>architecture: any</strong>, then
7070 the shared library compilation and linking flags must have
7071 <tt>-fPIC</tt>, or the package shall not build on some of
7072 the supported architectures<footnote>
7074 If you are using GCC, <tt>-fPIC</tt> produces code with
7075 relocatable position independent code, which is required for
7076 most architectures to create a shared library, with i386 and
7077 perhaps some others where non position independent code is
7078 permitted in a shared library.
7081 Position independent code may have a performance penalty,
7082 especially on <tt>i386</tt>. However, in most cases the
7083 speed penalty must be measured against the memory wasted on
7084 the few architectures where non position independent code is
7087 </footnote>. Any exception to this rule must be discussed on
7088 the mailing list <em>debian-devel@lists.debian.org</em>, and
7089 a rough consensus obtained. The reasons for not compiling
7090 with <tt>-fPIC</tt> flag must be recorded in the file
7091 <tt>README.Debian</tt>, and care must be taken to either
7092 restrict the architecture or arrange for <tt>-fPIC</tt> to
7093 be used on architectures where it is required.<footnote>
7095 Some of the reasons why this might be required is if the
7096 library contains hand crafted assembly code that is not
7097 relocatable, the speed penalty is excessive for compute
7098 intensive libs, and similar reasons.
7103 As to the static libraries, the common case is not to have
7104 relocatable code, since there is no benefit, unless in specific
7105 cases; therefore the static version must not be compiled
7106 with the <tt>-fPIC</tt> flag. Any exception to this rule
7107 should be discussed on the mailing list
7108 <em>debian-devel@lists.debian.org</em>, and the reasons for
7109 compiling with the <tt>-fPIC</tt> flag must be recorded in
7110 the file <tt>README.Debian</tt>. <footnote>
7112 Some of the reasons for linking static libraries with
7113 the <tt>-fPIC</tt> flag are if, for example, one needs a
7114 Perl API for a library that is under rapid development,
7115 and has an unstable API, so shared libraries are
7116 pointless at this phase of the library's development. In
7117 that case, since Perl needs a library with relocatable
7118 code, it may make sense to create a static library with
7119 relocatable code. Another reason cited is if you are
7120 distilling various libraries into a common shared
7121 library, like <tt>mklibs</tt> does in the Debian
7127 In other words, if both a shared and a static library is
7128 being built, each source unit (<tt>*.c</tt>, for example,
7129 for C files) will need to be compiled twice, for the normal
7133 You must specify the gcc option <tt>-D_REENTRANT</tt>
7134 when building a library (either static or shared) to make
7135 the library compatible with LinuxThreads.
7139 Although not enforced by the build tools, shared libraries
7140 must be linked against all libraries that they use symbols from
7141 in the same way that binaries are. This ensures the correct
7142 functioning of the <qref id="sharedlibs-shlibdeps">shlibs</qref>
7143 system and guarantees that all libraries can be safely opened
7144 with <tt>dlopen()</tt>. Packagers may wish to use the gcc
7145 option <tt>-Wl,-z,defs</tt> when building a shared library.
7146 Since this option enforces symbol resolution at build time,
7147 a missing library reference will be caught early as a fatal
7152 All installed shared libraries should be stripped with
7153 <example compact="compact">
7154 strip --strip-unneeded <var>your-lib</var>
7156 (The option <tt>--strip-unneeded</tt> makes
7157 <prgn>strip</prgn> remove only the symbols which aren't
7158 needed for relocation processing.) Shared libraries can
7159 function perfectly well when stripped, since the symbols for
7160 dynamic linking are in a separate part of the ELF object
7162 You might also want to use the options
7163 <tt>--remove-section=.comment</tt> and
7164 <tt>--remove-section=.note</tt> on both shared libraries
7165 and executables, and <tt>--strip-debug</tt> on static
7171 Note that under some circumstances it may be useful to
7172 install a shared library unstripped, for example when
7173 building a separate package to support debugging.
7177 Shared object files (often <file>.so</file> files) that are not
7178 public libraries, that is, they are not meant to be linked
7179 to by third party executables (binaries of other packages),
7180 should be installed in subdirectories of the
7181 <file>/usr/lib</file> directory. Such files are exempt from the
7182 rules that govern ordinary shared libraries, except that
7183 they must not be installed executable and should be
7185 A common example are the so-called "plug-ins",
7186 internal shared objects that are dynamically loaded by
7187 programs using <manref name="dlopen" section="3">.
7192 An ever increasing number of packages are using
7193 <prgn>libtool</prgn> to do their linking. The latest GNU
7194 libtools (>= 1.3a) can take advantage of the metadata in the
7195 installed <prgn>libtool</prgn> archive files (<file>*.la</file>
7196 files). The main advantage of <prgn>libtool</prgn>'s
7197 <file>.la</file> files is that it allows <prgn>libtool</prgn> to
7198 store and subsequently access metadata with respect to the
7199 libraries it builds. <prgn>libtool</prgn> will search for
7200 those files, which contain a lot of useful information about
7201 a library (such as library dependency information for static
7202 linking). Also, they're <em>essential</em> for programs
7203 using <tt>libltdl</tt>.<footnote>
7204 Although <prgn>libtool</prgn> is fully capable of
7205 linking against shared libraries which don't have
7206 <tt>.la</tt> files, as it is a mere shell script it can
7207 add considerably to the build time of a
7208 <prgn>libtool</prgn>-using package if that shell script
7209 has to derive all this information from first principles
7210 for each library every time it is linked. With the
7211 advent of <prgn>libtool</prgn> version 1.4 (and to a
7212 lesser extent <prgn>libtool</prgn> version 1.3), the
7213 <file>.la</file> files also store information about
7214 inter-library dependencies which cannot necessarily be
7215 derived after the <file>.la</file> file is deleted.
7220 Packages that use <prgn>libtool</prgn> to create shared
7221 libraries should include the <file>.la</file> files in the
7222 <tt>-dev</tt> package, unless the package relies on
7223 <tt>libtool</tt>'s <tt>libltdl</tt> library, in which case
7224 the <tt>.la</tt> files must go in the run-time library
7229 You must make sure that you use only released versions of
7230 shared libraries to build your packages; otherwise other
7231 users will not be able to run your binaries
7232 properly. Producing source packages that depend on
7233 unreleased compilers is also usually a bad
7240 <heading>Shared libraries</heading>
7242 This section has moved to <ref id="sharedlibs">.
7248 <heading>Scripts</heading>
7251 All command scripts, including the package maintainer
7252 scripts inside the package and used by <prgn>dpkg</prgn>,
7253 should have a <tt>#!</tt> line naming the shell to be used
7258 In the case of Perl scripts this should be
7259 <tt>#!/usr/bin/perl</tt>.
7263 When scripts are installed into a directory in the system
7264 PATH, the script name should not include an extension such
7265 as <tt>.sh</tt> or <tt>.pl</tt> that denotes the scripting
7266 language currently used to implement it.
7269 Shell scripts (<prgn>sh</prgn> and <prgn>bash</prgn>) other than
7270 <file>init.d</file> scripts should almost certainly start
7271 with <tt>set -e</tt> so that errors are detected.
7272 <file>init.d</file> scripts are something of a special case, due
7273 to how frequently they need to call commands that are allowed to
7274 fail, and it may instead be easier to check the exit status of
7275 commands directly. See <ref id="writing-init"> for more
7276 information about writing <file>init.d</file> scripts.
7279 Every script should use <tt>set -e</tt> or check the exit status
7280 of <em>every</em> command.
7283 Scripts may assume that <file>/bin/sh</file> implements the
7284 SUSv3 Shell Command Language<footnote>
7285 Single UNIX Specification, version 3, which is also IEEE
7286 1003.1-2004 (POSIX), and is available on the World Wide Web
7287 from <url id="http://www.unix.org/version3/online.html"
7288 name="The Open Group"> after free
7289 registration.</footnote>
7290 plus the following additional features not mandated by
7292 These features are in widespread use in the Linux community
7293 and are implemented in all of bash, dash, and ksh, the most
7294 common shells users may wish to use as <file>/bin/sh</file>.
7297 <item><tt>echo -n</tt>, if implemented as a shell built-in,
7298 must not generate a newline.</item>
7299 <item><tt>test</tt>, if implemented as a shell built-in, must
7300 support <tt>-a</tt> and <tt>-o</tt> as binary logical
7302 <item><tt>local</tt> to create a scoped variable must be
7303 supported, including listing multiple variables in a single
7304 local command and assigning a value to a variable at the
7305 same time as localizing it. <tt>local</tt> may or
7306 may not preserve the variable value from an outer scope if
7307 no assignment is present. Uses such as:
7311 # ... use a, b, c, d ...
7314 must be supported and must set the value of <tt>c</tt> to
7318 If a shell script requires non-SUSv3 features from the shell
7319 interpreter other than those listed above, the appropriate shell
7320 must be specified in the first line of the script (e.g.,
7321 <tt>#!/bin/bash</tt>) and the package must depend on the package
7322 providing the shell (unless the shell package is marked
7323 "Essential", as in the case of <prgn>bash</prgn>).
7327 You may wish to restrict your script to SUSv3 features plus the
7328 above set when possible so that it may use <file>/bin/sh</file>
7329 as its interpreter. If your script works with <prgn>dash</prgn>
7330 (originally called <prgn>ash</prgn>), it probably complies with
7331 the above requirements, but if you are in doubt, use
7332 <file>/bin/bash</file>.
7336 Perl scripts should check for errors when making any
7337 system calls, including <tt>open</tt>, <tt>print</tt>,
7338 <tt>close</tt>, <tt>rename</tt> and <tt>system</tt>.
7342 <prgn>csh</prgn> and <prgn>tcsh</prgn> should be avoided as
7343 scripting languages. See <em>Csh Programming Considered
7344 Harmful</em>, one of the <tt>comp.unix.*</tt> FAQs, which
7345 can be found at <url id="http://www.faqs.org/faqs/unix-faq/shell/csh-whynot/">.
7346 If an upstream package comes with <prgn>csh</prgn> scripts
7347 then you must make sure that they start with
7348 <tt>#!/bin/csh</tt> and make your package depend on the
7349 <prgn>c-shell</prgn> virtual package.
7353 Any scripts which create files in world-writeable
7354 directories (e.g., in <file>/tmp</file>) must use a
7355 mechanism which will fail atomically if a file with the same
7356 name already exists.
7360 The Debian base system provides the <prgn>tempfile</prgn>
7361 and <prgn>mktemp</prgn> utilities for use by scripts for
7368 <heading>Symbolic links</heading>
7371 In general, symbolic links within a top-level directory
7372 should be relative, and symbolic links pointing from one
7373 top-level directory into another should be absolute. (A
7374 top-level directory is a sub-directory of the root
7375 directory <file>/</file>.)
7379 In addition, symbolic links should be specified as short as
7380 possible, i.e., link targets like <file>foo/../bar</file> are
7385 Note that when creating a relative link using
7386 <prgn>ln</prgn> it is not necessary for the target of the
7387 link to exist relative to the working directory you're
7388 running <prgn>ln</prgn> from, nor is it necessary to change
7389 directory to the directory where the link is to be made.
7390 Simply include the string that should appear as the target
7391 of the link (this will be a pathname relative to the
7392 directory in which the link resides) as the first argument
7397 For example, in your <prgn>Makefile</prgn> or
7398 <file>debian/rules</file>, you can do things like:
7399 <example compact="compact">
7400 ln -fs gcc $(prefix)/bin/cc
7401 ln -fs gcc debian/tmp/usr/bin/cc
7402 ln -fs ../sbin/sendmail $(prefix)/bin/runq
7403 ln -fs ../sbin/sendmail debian/tmp/usr/bin/runq
7408 A symbolic link pointing to a compressed file should always
7409 have the same file extension as the referenced file. (For
7410 example, if a file <file>foo.gz</file> is referenced by a
7411 symbolic link, the filename of the link has to end with
7412 "<file>.gz</file>" too, as in <file>bar.gz</file>.)
7417 <heading>Device files</heading>
7420 Packages must not include device files or named pipes in the
7425 If a package needs any special device files that are not
7426 included in the base system, it must call
7427 <prgn>MAKEDEV</prgn> in the <prgn>postinst</prgn> script,
7428 after notifying the user<footnote>
7429 This notification could be done via a (low-priority)
7430 debconf message, or an echo (printf) statement.
7435 Packages must not remove any device files in the
7436 <prgn>postrm</prgn> or any other script. This is left to the
7437 system administrator.
7441 Debian uses the serial devices
7442 <file>/dev/ttyS*</file>. Programs using the old
7443 <file>/dev/cu*</file> devices should be changed to use
7444 <file>/dev/ttyS*</file>.
7448 Named pipes needed by the package must be created in
7449 the <prgn>postinst</prgn> script<footnote>
7450 It's better to use <prgn>mkfifo</prgn> rather
7451 than <prgn>mknod</prgn> to create named pipes so that
7452 automated checks for packages incorrectly creating device
7453 files with <prgn>mknod</prgn> won't have false positives.
7454 </footnote> and removed in
7455 the <prgn>prerm</prgn> or <prgn>postrm</prgn> script as
7460 <sect id="config-files">
7461 <heading>Configuration files</heading>
7464 <heading>Definitions</heading>
7468 <tag>configuration file</tag>
7470 A file that affects the operation of a program, or
7471 provides site- or host-specific information, or
7472 otherwise customizes the behavior of a program.
7473 Typically, configuration files are intended to be
7474 modified by the system administrator (if needed or
7475 desired) to conform to local policy or to provide
7476 more useful site-specific behavior.
7479 <tag><tt>conffile</tt></tag>
7481 A file listed in a package's <tt>conffiles</tt>
7482 file, and is treated specially by <prgn>dpkg</prgn>
7483 (see <ref id="configdetails">).
7489 The distinction between these two is important; they are
7490 not interchangeable concepts. Almost all
7491 <tt>conffile</tt>s are configuration files, but many
7492 configuration files are not <tt>conffiles</tt>.
7496 As noted elsewhere, <file>/etc/init.d</file> scripts,
7497 <file>/etc/default</file> files, scripts installed in
7498 <file>/etc/cron.{hourly,daily,weekly,monthly}</file>, and cron
7499 configuration installed in <file>/etc/cron.d</file> must be
7500 treated as configuration files. In general, any script that
7501 embeds configuration information is de-facto a configuration
7502 file and should be treated as such.
7507 <heading>Location</heading>
7510 Any configuration files created or used by your package
7511 must reside in <file>/etc</file>. If there are several,
7512 consider creating a subdirectory of <file>/etc</file>
7513 named after your package.
7517 If your package creates or uses configuration files
7518 outside of <file>/etc</file>, and it is not feasible to modify
7519 the package to use <file>/etc</file> directly, put the files
7520 in <file>/etc</file> and create symbolic links to those files
7521 from the location that the package requires.
7526 <heading>Behavior</heading>
7529 Configuration file handling must conform to the following
7531 <list compact="compact">
7533 local changes must be preserved during a package
7537 configuration files must be preserved when the
7538 package is removed, and only deleted when the
7542 Obsolete configuration files without local changes may be
7543 removed by the package during upgrade.
7547 The easy way to achieve this behavior is to make the
7548 configuration file a <tt>conffile</tt>. This is
7549 appropriate only if it is possible to distribute a default
7550 version that will work for most installations, although
7551 some system administrators may choose to modify it. This
7552 implies that the default version will be part of the
7553 package distribution, and must not be modified by the
7554 maintainer scripts during installation (or at any other
7559 In order to ensure that local changes are preserved
7560 correctly, no package may contain or make hard links to
7561 conffiles.<footnote>
7562 Rationale: There are two problems with hard links.
7563 The first is that some editors break the link while
7564 editing one of the files, so that the two files may
7565 unwittingly become unlinked and different. The second
7566 is that <prgn>dpkg</prgn> might break the hard link
7567 while upgrading <tt>conffile</tt>s.
7572 The other way to do it is via the maintainer scripts. In
7573 this case, the configuration file must not be listed as a
7574 <tt>conffile</tt> and must not be part of the package
7575 distribution. If the existence of a file is required for
7576 the package to be sensibly configured it is the
7577 responsibility of the package maintainer to provide
7578 maintainer scripts which correctly create, update and
7579 maintain the file and remove it on purge. (See <ref
7580 id="maintainerscripts"> for more information.) These
7581 scripts must be idempotent (i.e., must work correctly if
7582 <prgn>dpkg</prgn> needs to re-run them due to errors
7583 during installation or removal), must cope with all the
7584 variety of ways <prgn>dpkg</prgn> can call maintainer
7585 scripts, must not overwrite or otherwise mangle the user's
7586 configuration without asking, must not ask unnecessary
7587 questions (particularly during upgrades), and must
7588 otherwise be good citizens.
7592 The scripts are not required to configure every possible
7593 option for the package, but only those necessary to get
7594 the package running on a given system. Ideally the
7595 sysadmin should not have to do any configuration other
7596 than that done (semi-)automatically by the
7597 <prgn>postinst</prgn> script.
7601 A common practice is to create a script called
7602 <file><var>package</var>-configure</file> and have the
7603 package's <prgn>postinst</prgn> call it if and only if the
7604 configuration file does not already exist. In certain
7605 cases it is useful for there to be an example or template
7606 file which the maintainer scripts use. Such files should
7607 be in <file>/usr/share/<var>package</var></file> or
7608 <file>/usr/lib/<var>package</var></file> (depending on whether
7609 they are architecture-independent or not). There should
7610 be symbolic links to them from
7611 <file>/usr/share/doc/<var>package</var>/examples</file> if
7612 they are examples, and should be perfectly ordinary
7613 <prgn>dpkg</prgn>-handled files (<em>not</em>
7614 configuration files).
7618 These two styles of configuration file handling must
7619 not be mixed, for that way lies madness:
7620 <prgn>dpkg</prgn> will ask about overwriting the file
7621 every time the package is upgraded.
7626 <heading>Sharing configuration files</heading>
7629 Packages which specify the same file as a
7630 <tt>conffile</tt> must be tagged as <em>conflicting</em>
7631 with each other. (This is an instance of the general rule
7632 about not sharing files. Note that neither alternatives
7633 nor diversions are likely to be appropriate in this case;
7634 in particular, <prgn>dpkg</prgn> does not handle diverted
7635 <tt>conffile</tt>s well.)
7639 The maintainer scripts must not alter a <tt>conffile</tt>
7640 of <em>any</em> package, including the one the scripts
7645 If two or more packages use the same configuration file
7646 and it is reasonable for both to be installed at the same
7647 time, one of these packages must be defined as
7648 <em>owner</em> of the configuration file, i.e., it will be
7649 the package which handles that file as a configuration
7650 file. Other packages that use the configuration file must
7651 depend on the owning package if they require the
7652 configuration file to operate. If the other package will
7653 use the configuration file if present, but is capable of
7654 operating without it, no dependency need be declared.
7658 If it is desirable for two or more related packages to
7659 share a configuration file <em>and</em> for all of the
7660 related packages to be able to modify that configuration
7661 file, then the following should be done:
7662 <enumlist compact="compact">
7664 One of the related packages (the "owning" package)
7665 will manage the configuration file with maintainer
7666 scripts as described in the previous section.
7669 The owning package should also provide a program
7670 that the other packages may use to modify the
7674 The related packages must use the provided program
7675 to make any desired modifications to the
7676 configuration file. They should either depend on
7677 the core package to guarantee that the configuration
7678 modifier program is available or accept gracefully
7679 that they cannot modify the configuration file if it
7680 is not. (This is in addition to the fact that the
7681 configuration file may not even be present in the
7688 Sometimes it's appropriate to create a new package which
7689 provides the basic infrastructure for the other packages
7690 and which manages the shared configuration files. (The
7691 <tt>sgml-base</tt> package is a good example.)
7696 <heading>User configuration files ("dotfiles")</heading>
7699 The files in <file>/etc/skel</file> will automatically be
7700 copied into new user accounts by <prgn>adduser</prgn>.
7701 No other program should reference the files in
7702 <file>/etc/skel</file>.
7706 Therefore, if a program needs a dotfile to exist in
7707 advance in <file>$HOME</file> to work sensibly, that dotfile
7708 should be installed in <file>/etc/skel</file> and treated as a
7713 However, programs that require dotfiles in order to
7714 operate sensibly are a bad thing, unless they do create
7715 the dotfiles themselves automatically.
7719 Furthermore, programs should be configured by the Debian
7720 default installation to behave as closely to the upstream
7721 default behavior as possible.
7725 Therefore, if a program in a Debian package needs to be
7726 configured in some way in order to operate sensibly, that
7727 should be done using a site-wide configuration file placed
7728 in <file>/etc</file>. Only if the program doesn't support a
7729 site-wide default configuration and the package maintainer
7730 doesn't have time to add it may a default per-user file be
7731 placed in <file>/etc/skel</file>.
7735 <file>/etc/skel</file> should be as empty as we can make it.
7736 This is particularly true because there is no easy (or
7737 necessarily desirable) mechanism for ensuring that the
7738 appropriate dotfiles are copied into the accounts of
7739 existing users when a package is installed.
7745 <heading>Log files</heading>
7747 Log files should usually be named
7748 <file>/var/log/<var>package</var>.log</file>. If you have many
7749 log files, or need a separate directory for permission
7750 reasons (<file>/var/log</file> is writable only by
7751 <file>root</file>), you should usually create a directory named
7752 <file>/var/log/<var>package</var></file> and place your log
7757 Log files must be rotated occasionally so that they don't
7758 grow indefinitely; the best way to do this is to drop a log
7759 rotation configuration file into the directory
7760 <file>/etc/logrotate.d</file> and use the facilities provided by
7761 logrotate.<footnote>
7763 The traditional approach to log files has been to set up
7764 <em>ad hoc</em> log rotation schemes using simple shell
7765 scripts and cron. While this approach is highly
7766 customizable, it requires quite a lot of sysadmin work.
7767 Even though the original Debian system helped a little
7768 by automatically installing a system which can be used
7769 as a template, this was deemed not enough.
7773 The use of <prgn>logrotate</prgn>, a program developed
7774 by Red Hat, is better, as it centralizes log management.
7775 It has both a configuration file
7776 (<file>/etc/logrotate.conf</file>) and a directory where
7777 packages can drop their individual log rotation
7778 configurations (<file>/etc/logrotate.d</file>).
7781 Here is a good example for a logrotate config
7782 file (for more information see <manref name="logrotate"
7784 <example compact="compact">
7785 /var/log/foo/*.log {
7790 /etc/init.d/foo force-reload
7794 This rotates all files under <file>/var/log/foo</file>, saves 12
7795 compressed generations, and forces the daemon to reload its
7796 configuration information after the log rotation.
7800 Log files should be removed when the package is
7801 purged (but not when it is only removed). This should be
7802 done by the <prgn>postrm</prgn> script when it is called
7803 with the argument <tt>purge</tt> (see <ref
7804 id="removedetails">).
7809 <heading>Permissions and owners</heading>
7812 The rules in this section are guidelines for general use.
7813 If necessary you may deviate from the details below.
7814 However, if you do so you must make sure that what is done
7815 is secure and you should try to be as consistent as possible
7816 with the rest of the system. You should probably also
7817 discuss it on <prgn>debian-devel</prgn> first.
7821 Files should be owned by <tt>root:root</tt>, and made
7822 writable only by the owner and universally readable (and
7823 executable, if appropriate), that is mode 644 or 755.
7827 Directories should be mode 755 or (for group-writability)
7828 mode 2775. The ownership of the directory should be
7829 consistent with its mode: if a directory is mode 2775, it
7830 should be owned by the group that needs write access to
7833 When a package is upgraded, and the owner or permissions
7834 of a file included in the package has changed, dpkg
7835 arranges for the ownership and permissions to be
7836 correctly set upon installation. However, this does not
7837 extend to directories; the permissions and ownership of
7838 directories already on the system does not change on
7839 install or upgrade of packages. This makes sense, since
7840 otherwise common directories like <tt>/usr</tt> would
7841 always be in flux. To correctly change permissions of a
7842 directory the package owns, explicit action is required,
7843 usually in the <tt>postinst</tt> script. Care must be
7844 taken to handle downgrades as well, in that case.
7851 Setuid and setgid executables should be mode 4755 or 2755
7852 respectively, and owned by the appropriate user or group.
7853 They should not be made unreadable (modes like 4711 or
7854 2711 or even 4111); doing so achieves no extra security,
7855 because anyone can find the binary in the freely available
7856 Debian package; it is merely inconvenient. For the same
7857 reason you should not restrict read or execute permissions
7858 on non-set-id executables.
7862 Some setuid programs need to be restricted to particular
7863 sets of users, using file permissions. In this case they
7864 should be owned by the uid to which they are set-id, and by
7865 the group which should be allowed to execute them. They
7866 should have mode 4754; again there is no point in making
7867 them unreadable to those users who must not be allowed to
7872 It is possible to arrange that the system administrator can
7873 reconfigure the package to correspond to their local
7874 security policy by changing the permissions on a binary:
7875 they can do this by using <prgn>dpkg-statoverride</prgn>, as
7876 described below.<footnote>
7877 Ordinary files installed by <prgn>dpkg</prgn> (as
7878 opposed to <tt>conffile</tt>s and other similar objects)
7879 normally have their permissions reset to the distributed
7880 permissions when the package is reinstalled. However,
7881 the use of <prgn>dpkg-statoverride</prgn> overrides this
7884 Another method you should consider is to create a group for
7885 people allowed to use the program(s) and make any setuid
7886 executables executable only by that group.
7890 If you need to create a new user or group for your package
7891 there are two possibilities. Firstly, you may need to
7892 make some files in the binary package be owned by this
7893 user or group, or you may need to compile the user or
7894 group id (rather than just the name) into the binary
7895 (though this latter should be avoided if possible, as in
7896 this case you need a statically allocated id).</p>
7899 If you need a statically allocated id, you must ask for a
7900 user or group id from the <tt>base-passwd</tt> maintainer,
7901 and must not release the package until you have been
7902 allocated one. Once you have been allocated one you must
7903 either make the package depend on a version of the
7904 <tt>base-passwd</tt> package with the id present in
7905 <file>/etc/passwd</file> or <file>/etc/group</file>, or arrange for
7906 your package to create the user or group itself with the
7907 correct id (using <tt>adduser</tt>) in its
7908 <prgn>preinst</prgn> or <prgn>postinst</prgn>. (Doing it in
7909 the <prgn>postinst</prgn> is to be preferred if it is
7910 possible, otherwise a pre-dependency will be needed on the
7911 <tt>adduser</tt> package.)
7915 On the other hand, the program might be able to determine
7916 the uid or gid from the user or group name at runtime, so
7917 that a dynamically allocated id can be used. In this case
7918 you should choose an appropriate user or group name,
7919 discussing this on <prgn>debian-devel</prgn> and checking
7920 with the <package/base-passwd/ maintainer that it is unique and that
7921 they do not wish you to use a statically allocated id
7922 instead. When this has been checked you must arrange for
7923 your package to create the user or group if necessary using
7924 <prgn>adduser</prgn> in the <prgn>preinst</prgn> or
7925 <prgn>postinst</prgn> script (again, the latter is to be
7926 preferred if it is possible).
7930 Note that changing the numeric value of an id associated
7931 with a name is very difficult, and involves searching the
7932 file system for all appropriate files. You need to think
7933 carefully whether a static or dynamic id is required, since
7934 changing your mind later will cause problems.
7937 <sect1><heading>The use of <prgn>dpkg-statoverride</prgn></heading>
7939 This section is not intended as policy, but as a
7940 description of the use of <prgn>dpkg-statoverride</prgn>.
7944 If a system administrator wishes to have a file (or
7945 directory or other such thing) installed with owner and
7946 permissions different from those in the distributed Debian
7947 package, they can use the <prgn>dpkg-statoverride</prgn>
7948 program to instruct <prgn>dpkg</prgn> to use the different
7949 settings every time the file is installed. Thus the
7950 package maintainer should distribute the files with their
7951 normal permissions, and leave it for the system
7952 administrator to make any desired changes. For example, a
7953 daemon which is normally required to be setuid root, but
7954 in certain situations could be used without being setuid,
7955 should be installed setuid in the <tt>.deb</tt>. Then the
7956 local system administrator can change this if they wish.
7957 If there are two standard ways of doing it, the package
7958 maintainer can use <tt>debconf</tt> to find out the
7959 preference, and call <prgn>dpkg-statoverride</prgn> in the
7960 maintainer script if necessary to accommodate the system
7961 administrator's choice. Care must be taken during
7962 upgrades to not override an existing setting.
7966 Given the above, <prgn>dpkg-statoverride</prgn> is
7967 essentially a tool for system administrators and would not
7968 normally be needed in the maintainer scripts. There is
7969 one type of situation, though, where calls to
7970 <prgn>dpkg-statoverride</prgn> would be needed in the
7971 maintainer scripts, and that involves packages which use
7972 dynamically allocated user or group ids. In such a
7973 situation, something like the following idiom can be very
7974 helpful in the package's <prgn>postinst</prgn>, where
7975 <tt>sysuser</tt> is a dynamically allocated id:
7977 for i in /usr/bin/foo /usr/sbin/bar
7979 # only do something when no setting exists
7980 if ! dpkg-statoverride --list $i >/dev/null 2>&1
7982 #include: debconf processing, question about foo and bar
7983 if [ "$RET" = "true" ] ; then
7984 dpkg-statoverride --update --add sysuser root 4755 $i
7989 The corresponding code to remove the override when the package
7992 for i in /usr/bin/foo /usr/sbin/bar
7994 if dpkg-statoverride --list $i >/dev/null 2>&1
7996 dpkg-statoverride --remove $i
8006 <chapt id="customized-programs">
8007 <heading>Customized programs</heading>
8009 <sect id="arch-spec">
8010 <heading>Architecture specification strings</heading>
8013 If a program needs to specify an <em>architecture specification
8014 string</em> in some place, it should select one of the strings
8015 provided by <tt>dpkg-architecture -L</tt>. The strings are in
8016 the format <tt><var>os</var>-<var>arch</var></tt>, though the OS
8017 part is sometimes elided, as when the OS is Linux.
8021 Note that we don't want to use
8022 <tt><var>arch</var>-debian-linux</tt> to apply to the rule
8023 <tt><var>architecture</var>-<var>vendor</var>-<var>os</var></tt>
8024 since this would make our programs incompatible with other
8025 Linux distributions. We also don't use something like
8026 <tt><var>arch</var>-unknown-linux</tt>, since the
8027 <tt>unknown</tt> does not look very good.
8030 <sect1 id="arch-wildcard-spec">
8031 <heading>Architecture wildcards</heading>
8034 A package may specify an architecture wildcard. Architecture
8035 wildcards are in the format <tt>any</tt> (which matches every
8036 architecture), <tt><var>os</var></tt>-any, or
8037 any-<tt><var>cpu</var></tt>. <footnote>
8038 Internally, the package system normalizes the GNU triplets
8039 and the Debian arches into Debian arch triplets (which are
8040 kind of inverted GNU triplets), with the first component of
8041 the triplet representing the libc and ABI in use, and then
8042 does matching against those triplets. However, such
8043 triplets are an internal implementation detail that should
8044 not be used by packages directly. The libc and ABI portion
8045 is handled internally by the package system based on
8046 the <var>os</var> and <var>cpu</var>.
8053 <heading>Daemons</heading>
8056 The configuration files <file>/etc/services</file>,
8057 <file>/etc/protocols</file>, and <file>/etc/rpc</file> are managed
8058 by the <prgn>netbase</prgn> package and must not be modified
8063 If a package requires a new entry in one of these files, the
8064 maintainer should get in contact with the
8065 <prgn>netbase</prgn> maintainer, who will add the entries
8066 and release a new version of the <prgn>netbase</prgn>
8071 The configuration file <file>/etc/inetd.conf</file> must not be
8072 modified by the package's scripts except via the
8073 <prgn>update-inetd</prgn> script or the
8074 <file>DebianNet.pm</file> Perl module. See their documentation
8075 for details on how to add entries.
8079 If a package wants to install an example entry into
8080 <file>/etc/inetd.conf</file>, the entry must be preceded with
8081 exactly one hash character (<tt>#</tt>). Such lines are
8082 treated as "commented out by user" by the
8083 <prgn>update-inetd</prgn> script and are not changed or
8084 activated during package updates.
8089 <heading>Using pseudo-ttys and modifying wtmp, utmp and
8093 Some programs need to create pseudo-ttys. This should be done
8094 using Unix98 ptys if the C library supports it. The resulting
8095 program must not be installed setuid root, unless that
8096 is required for other functionality.
8100 The files <file>/var/run/utmp</file>, <file>/var/log/wtmp</file> and
8101 <file>/var/log/lastlog</file> must be installed writable by
8102 group <tt>utmp</tt>. Programs which need to modify those
8103 files must be installed setgid <tt>utmp</tt>.
8108 <heading>Editors and pagers</heading>
8111 Some programs have the ability to launch an editor or pager
8112 program to edit or display a text document. Since there are
8113 lots of different editors and pagers available in the Debian
8114 distribution, the system administrator and each user should
8115 have the possibility to choose their preferred editor and
8120 In addition, every program should choose a good default
8121 editor/pager if none is selected by the user or system
8126 Thus, every program that launches an editor or pager must
8127 use the EDITOR or PAGER environment variable to determine
8128 the editor or pager the user wishes to use. If these
8129 variables are not set, the programs <file>/usr/bin/editor</file>
8130 and <file>/usr/bin/pager</file> should be used, respectively.
8134 These two files are managed through the <prgn>dpkg</prgn>
8135 "alternatives" mechanism. Thus every package providing an
8136 editor or pager must call the
8137 <prgn>update-alternatives</prgn> script to register these
8142 If it is very hard to adapt a program to make use of the
8143 EDITOR or PAGER variables, that program may be configured to
8144 use <file>/usr/bin/sensible-editor</file> and
8145 <file>/usr/bin/sensible-pager</file> as the editor or pager
8146 program respectively. These are two scripts provided in the
8147 <package>sensible-utils</package> package that check the EDITOR
8148 and PAGER variables and launch the appropriate program, and fall
8149 back to <file>/usr/bin/editor</file>
8150 and <file>/usr/bin/pager</file> if the variable is not set.
8154 A program may also use the VISUAL environment variable to
8155 determine the user's choice of editor. If it exists, it
8156 should take precedence over EDITOR. This is in fact what
8157 <file>/usr/bin/sensible-editor</file> does.
8161 It is not required for a package to depend on
8162 <tt>editor</tt> and <tt>pager</tt>, nor is it required for a
8163 package to provide such virtual packages.<footnote>
8164 The Debian base system already provides an editor and a
8170 <sect id="web-appl">
8171 <heading>Web servers and applications</heading>
8174 This section describes the locations and URLs that should
8175 be used by all web servers and web applications in the
8182 Cgi-bin executable files are installed in the
8184 <example compact="compact">
8185 /usr/lib/cgi-bin/<var>cgi-bin-name</var>
8187 or a subdirectory of that directory, and should be
8189 <example compact="compact">
8190 http://localhost/cgi-bin/<var>cgi-bin-name</var>
8192 (possibly with a subdirectory name
8193 before <var>cgi-bin-name</var>).
8197 <p>Access to HTML documents</p>
8200 HTML documents for a package are stored in
8201 <file>/usr/share/doc/<var>package</var></file>
8202 and can be referred to as
8203 <example compact="compact">
8204 http://localhost/doc/<var>package</var>/<var>filename</var>
8209 The web server should restrict access to the document
8210 tree so that only clients on the same host can read
8211 the documents. If the web server does not support such
8212 access controls, then it should not provide access at
8213 all, or ask about providing access during installation.
8218 <p>Access to images</p>
8220 It is recommended that images for a package be stored
8221 in <tt>/usr/share/images/<var>package</var></tt> and
8222 may be referred to through an alias <tt>/images/</tt>
8225 http://localhost/images/<package>/<filename>
8232 <p>Web Document Root</p>
8235 Web Applications should try to avoid storing files in
8236 the Web Document Root. Instead they should use the
8237 /usr/share/doc/<var>package</var> directory for
8238 documents and register the Web Application via the
8239 <package>doc-base</package> package. If access to the
8240 web document root is unavoidable then use
8241 <example compact="compact">
8244 as the Document Root. This might be just a symbolic
8245 link to the location where the system administrator
8246 has put the real document root.
8249 <item><p>Providing httpd and/or httpd-cgi</p>
8251 All web servers should provide the virtual package
8252 <tt>httpd</tt>. If a web server has CGI support it should
8253 provide <tt>httpd-cgi</tt> additionally.
8256 All web applications which do not contain CGI scripts should
8257 depend on <tt>httpd</tt>, all those web applications which
8258 <tt>do</tt> contain CGI scripts, should depend on
8266 <sect id="mail-transport-agents">
8267 <heading>Mail transport, delivery and user agents</heading>
8270 Debian packages which process electronic mail, whether mail
8271 user agents (MUAs) or mail transport agents (MTAs), must
8272 ensure that they are compatible with the configuration
8273 decisions below. Failure to do this may result in lost
8274 mail, broken <tt>From:</tt> lines, and other serious brain
8279 The mail spool is <file>/var/mail</file> and the interface to
8280 send a mail message is <file>/usr/sbin/sendmail</file> (as per
8281 the FHS). On older systems, the mail spool may be
8282 physically located in <file>/var/spool/mail</file>, but all
8283 access to the mail spool should be via the
8284 <file>/var/mail</file> symlink. The mail spool is part of the
8285 base system and not part of the MTA package.
8289 All Debian MUAs, MTAs, MDAs and other mailbox accessing
8290 programs (such as IMAP daemons) must lock the mailbox in an
8291 NFS-safe way. This means that <tt>fcntl()</tt> locking must
8292 be combined with dot locking. To avoid deadlocks, a program
8293 should use <tt>fcntl()</tt> first and dot locking after
8294 this, or alternatively implement the two locking methods in
8295 a non blocking way<footnote>
8296 If it is not possible to establish both locks, the
8297 system shouldn't wait for the second lock to be
8298 established, but remove the first lock, wait a (random)
8299 time, and start over locking again.
8300 </footnote>. Using the functions <tt>maillock</tt> and
8301 <tt>mailunlock</tt> provided by the
8302 <tt>liblockfile*</tt><footnote>
8303 You will need to depend on <tt>liblockfile1 (>>1.01)</tt>
8304 to use these functions.
8305 </footnote> packages is the recommended way to realize this.
8309 Mailboxes are generally either mode 600 and owned by
8310 <var>user</var> or mode 660 and owned by
8311 <tt><var>user</var>:mail</tt><footnote>
8312 There are two traditional permission schemes for mail spools:
8313 mode 600 with all mail delivery done by processes running as
8314 the destination user, or mode 660 and owned by group mail with
8315 mail delivery done by a process running as a system user in
8316 group mail. Historically, Debian required mode 660 mail
8317 spools to enable the latter model, but that model has become
8318 increasingly uncommon and the principle of least privilege
8319 indicates that mail systems that use the first model should
8320 use permissions of 600. If delivery to programs is permitted,
8321 it's easier to keep the mail system secure if the delivery
8322 agent runs as the destination user. Debian Policy therefore
8323 permits either scheme.
8324 </footnote>. The local system administrator may choose a
8325 different permission scheme; packages should not make
8326 assumptions about the permission and ownership of mailboxes
8327 unless required (such as when creating a new mailbox). A MUA
8328 may remove a mailbox (unless it has nonstandard permissions) in
8329 which case the MTA or another MUA must recreate it if needed.
8333 The mail spool is 2775 <tt>root:mail</tt>, and MUAs should
8334 be setgid mail to do the locking mentioned above (and
8335 must obviously avoid accessing other users' mailboxes
8336 using this privilege).</p>
8339 <file>/etc/aliases</file> is the source file for the system mail
8340 aliases (e.g., postmaster, usenet, etc.), it is the one
8341 which the sysadmin and <prgn>postinst</prgn> scripts may
8342 edit. After <file>/etc/aliases</file> is edited the program or
8343 human editing it must call <prgn>newaliases</prgn>. All MTA
8344 packages must come with a <prgn>newaliases</prgn> program,
8345 even if it does nothing, but older MTA packages did not do
8346 this so programs should not fail if <prgn>newaliases</prgn>
8347 cannot be found. Note that because of this, all MTA
8348 packages must have <tt>Provides</tt>, <tt>Conflicts</tt> and
8349 <tt>Replaces: mail-transport-agent</tt> control file
8354 The convention of writing <tt>forward to
8355 <var>address</var></tt> in the mailbox itself is not
8356 supported. Use a <tt>.forward</tt> file instead.</p>
8359 The <prgn>rmail</prgn> program used by UUCP
8360 for incoming mail should be <file>/usr/sbin/rmail</file>.
8361 Likewise, <prgn>rsmtp</prgn>, for receiving
8362 batch-SMTP-over-UUCP, should be <file>/usr/sbin/rsmtp</file> if it
8366 If your package needs to know what hostname to use on (for
8367 example) outgoing news and mail messages which are generated
8368 locally, you should use the file <file>/etc/mailname</file>. It
8369 will contain the portion after the username and <tt>@</tt>
8370 (at) sign for email addresses of users on the machine
8371 (followed by a newline).
8375 Such a package should check for the existence of this file
8376 when it is being configured. If it exists, it should be
8377 used without comment, although an MTA's configuration script
8378 may wish to prompt the user even if it finds that this file
8379 exists. If the file does not exist, the package should
8380 prompt the user for the value (preferably using
8381 <prgn>debconf</prgn>) and store it in <file>/etc/mailname</file>
8382 as well as using it in the package's configuration. The
8383 prompt should make it clear that the name will not just be
8384 used by that package. For example, in this situation the
8385 <tt>inn</tt> package could say something like:
8386 <example compact="compact">
8387 Please enter the "mail name" of your system. This is the
8388 hostname portion of the address to be shown on outgoing
8389 news and mail messages. The default is
8390 <var>syshostname</var>, your system's host name. Mail
8391 name ["<var>syshostname</var>"]:
8393 where <var>syshostname</var> is the output of <tt>hostname
8399 <heading>News system configuration</heading>
8402 All the configuration files related to the NNTP (news)
8403 servers and clients should be located under
8404 <file>/etc/news</file>.</p>
8407 There are some configuration issues that apply to a number
8408 of news clients and server packages on the machine. These
8412 <tag><file>/etc/news/organization</file></tag>
8414 A string which should appear as the
8415 organization header for all messages posted
8416 by NNTP clients on the machine
8419 <tag><file>/etc/news/server</file></tag>
8421 Contains the FQDN of the upstream NNTP
8422 server, or localhost if the local machine is
8427 Other global files may be added as required for cross-package news
8434 <heading>Programs for the X Window System</heading>
8437 <heading>Providing X support and package priorities</heading>
8440 Programs that can be configured with support for the X
8441 Window System must be configured to do so and must declare
8442 any package dependencies necessary to satisfy their
8443 runtime requirements when using the X Window System. If
8444 such a package is of higher priority than the X packages
8445 on which it depends, it is required that either the
8446 X-specific components be split into a separate package, or
8447 that an alternative version of the package, which includes
8448 X support, be provided, or that the package's priority be
8454 <heading>Packages providing an X server</heading>
8457 Packages that provide an X server that, directly or
8458 indirectly, communicates with real input and display
8459 hardware should declare in their control data that they
8460 provide the virtual package <tt>xserver</tt>.<footnote>
8461 This implements current practice, and provides an
8462 actual policy for usage of the <tt>xserver</tt>
8463 virtual package which appears in the virtual packages
8464 list. In a nutshell, X servers that interface
8465 directly with the display and input hardware or via
8466 another subsystem (e.g., GGI) should provide
8467 <tt>xserver</tt>. Things like <tt>Xvfb</tt>,
8468 <tt>Xnest</tt>, and <tt>Xprt</tt> should not.
8474 <heading>Packages providing a terminal emulator</heading>
8477 Packages that provide a terminal emulator for the X Window
8478 System which meet the criteria listed below should declare
8479 in their control data that they provide the virtual
8480 package <tt>x-terminal-emulator</tt>. They should also
8481 register themselves as an alternative for
8482 <file>/usr/bin/x-terminal-emulator</file>, with a priority of
8487 To be an <tt>x-terminal-emulator</tt>, a program must:
8488 <list compact="compact">
8490 Be able to emulate a DEC VT100 terminal, or a
8491 compatible terminal.
8495 Support the command-line option <tt>-e
8496 <var>command</var></tt>, which creates a new
8497 terminal window<footnote>
8498 "New terminal window" does not necessarily mean
8499 a new top-level X window directly parented by
8500 the window manager; it could, if the terminal
8501 emulator application were so coded, be a new
8502 "view" in a multiple-document interface (MDI).
8504 and runs the specified <var>command</var>,
8505 interpreting the entirety of the rest of the command
8506 line as a command to pass straight to exec, in the
8507 manner that <tt>xterm</tt> does.
8511 Support the command-line option <tt>-T
8512 <var>title</var></tt>, which creates a new terminal
8513 window with the window title <var>title</var>.
8520 <heading>Packages providing a window manager</heading>
8523 Packages that provide a window manager should declare in
8524 their control data that they provide the virtual package
8525 <tt>x-window-manager</tt>. They should also register
8526 themselves as an alternative for
8527 <file>/usr/bin/x-window-manager</file>, with a priority
8528 calculated as follows:
8529 <list compact="compact">
8531 Start with a priority of 20.
8535 If the window manager supports the Debian menu
8536 system, add 20 points if this support is available
8537 in the package's default configuration (i.e., no
8538 configuration files belonging to the system or user
8539 have to be edited to activate the feature); if
8540 configuration files must be modified, add only 10
8546 If the window manager complies with <url
8547 id="http://www.freedesktop.org/Standards/wm-spec"
8548 name="The Window Manager Specification Project">,
8549 written by the <url id="http://www.freedesktop.org/"
8550 name="Free Desktop Group">, add 40 points.
8554 If the window manager permits the X session to be
8555 restarted using a <em>different</em> window manager
8556 (without killing the X server) in its default
8557 configuration, add 10 points; otherwise add none.
8564 <heading>Packages providing fonts</heading>
8567 Packages that provide fonts for the X Window
8569 For the purposes of Debian Policy, a "font for the X
8570 Window System" is one which is accessed via X protocol
8571 requests. Fonts for the Linux console, for PostScript
8572 renderer, or any other purpose, do not fit this
8573 definition. Any tool which makes such fonts available
8574 to the X Window System, however, must abide by this
8577 must do a number of things to ensure that they are both
8578 available without modification of the X or font server
8579 configuration, and that they do not corrupt files used by
8580 other font packages to register information about
8584 Fonts of any type supported by the X Window System
8585 must be in a separate binary package from any
8586 executables, libraries, or documentation (except
8587 that specific to the fonts shipped, such as their
8588 license information). If one or more of the fonts
8589 so packaged are necessary for proper operation of
8590 the package with which they are associated the font
8591 package may be Recommended; if the fonts merely
8592 provide an enhancement, a Suggests relationship may
8593 be used. Packages must not Depend on font
8595 This is because the X server may retrieve fonts
8596 from the local file system or over the network
8597 from an X font server; the Debian package system
8598 is empowered to deal only with the local
8604 BDF fonts must be converted to PCF fonts with the
8605 <prgn>bdftopcf</prgn> utility (available in the
8606 <tt>xfonts-utils</tt> package, <prgn>gzip</prgn>ped, and
8607 placed in a directory that corresponds to their
8609 <list compact="compact">
8611 100 dpi fonts must be placed in
8612 <file>/usr/share/fonts/X11/100dpi/</file>.
8616 75 dpi fonts must be placed in
8617 <file>/usr/share/fonts/X11/75dpi/</file>.
8621 Character-cell fonts, cursor fonts, and other
8622 low-resolution fonts must be placed in
8623 <file>/usr/share/fonts/X11/misc/</file>.
8629 Type 1 fonts must be placed in
8630 <file>/usr/share/fonts/X11/Type1/</file>. If font
8631 metric files are available, they must be placed here
8636 Subdirectories of <file>/usr/share/fonts/X11/</file>
8637 other than those listed above must be neither
8638 created nor used. (The <file>PEX</file>, <file>CID</file>,
8639 <file>Speedo</file>, and <file>cyrillic</file> directories
8640 are excepted for historical reasons, but installation of
8641 files into these directories remains discouraged.)
8645 Font packages may, instead of placing files directly
8646 in the X font directories listed above, provide
8647 symbolic links in that font directory pointing to
8648 the files' actual location in the filesystem. Such
8649 a location must comply with the FHS.
8653 Font packages should not contain both 75dpi and
8654 100dpi versions of a font. If both are available,
8655 they should be provided in separate binary packages
8656 with <tt>-75dpi</tt> or <tt>-100dpi</tt> appended to
8657 the names of the packages containing the
8658 corresponding fonts.
8662 Fonts destined for the <file>misc</file> subdirectory
8663 should not be included in the same package as 75dpi
8664 or 100dpi fonts; instead, they should be provided in
8665 a separate package with <tt>-misc</tt> appended to
8670 Font packages must not provide the files
8671 <file>fonts.dir</file>, <file>fonts.alias</file>, or
8672 <file>fonts.scale</file> in a font directory:
8675 <file>fonts.dir</file> files must not be provided at all.
8679 <file>fonts.alias</file> and <file>fonts.scale</file>
8680 files, if needed, should be provided in the
8682 <file>/etc/X11/fonts/<var>fontdir</var>/<var>package</var>.<var>extension</var></file>,
8683 where <var>fontdir</var> is the name of the
8685 <file>/usr/share/fonts/X11/</file> where the
8686 package's corresponding fonts are stored
8687 (e.g., <tt>75dpi</tt> or <tt>misc</tt>),
8688 <var>package</var> is the name of the package
8689 that provides these fonts, and
8690 <var>extension</var> is either <tt>scale</tt>
8691 or <tt>alias</tt>, whichever corresponds to
8698 Font packages must declare a dependency on
8699 <tt>xfonts-utils</tt> in their control
8704 Font packages that provide one or more
8705 <file>fonts.scale</file> files as described above must
8706 invoke <prgn>update-fonts-scale</prgn> on each
8707 directory into which they installed fonts
8708 <em>before</em> invoking
8709 <prgn>update-fonts-dir</prgn> on that directory.
8710 This 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 that provide one or more
8718 <file>fonts.alias</file> files as described above must
8719 invoke <prgn>update-fonts-alias</prgn> on each
8720 directory into which they installed fonts. This
8721 invocation must occur in both the
8722 <prgn>postinst</prgn> (for all arguments) and
8723 <prgn>postrm</prgn> (for all arguments except
8724 <tt>upgrade</tt>) scripts.
8728 Font packages must invoke
8729 <prgn>update-fonts-dir</prgn> on each directory into
8730 which they installed fonts. This invocation must
8731 occur in both the <prgn>postinst</prgn> (for all
8732 arguments) and <prgn>postrm</prgn> (for all
8733 arguments except <tt>upgrade</tt>) scripts.
8737 Font packages must not provide alias names for the
8738 fonts they include which collide with alias names
8739 already in use by fonts already packaged.
8743 Font packages must not provide fonts with the same
8744 XLFD registry name as another font already packaged.
8750 <sect1 id="appdefaults">
8751 <heading>Application defaults files</heading>
8754 Application defaults files must be installed in the
8755 directory <file>/etc/X11/app-defaults/</file> (use of a
8756 localized subdirectory of <file>/etc/X11/</file> as described
8757 in the <em>X Toolkit Intrinsics - C Language
8758 Interface</em> manual is also permitted). They must be
8759 registered as <tt>conffile</tt>s or handled as
8760 configuration files.
8764 Customization of programs' X resources may also be
8765 supported with the provision of a file with the same name
8766 as that of the package placed in
8767 the <file>/etc/X11/Xresources/</file> directory, which
8768 must be registered as a <tt>conffile</tt> or handled as a
8769 configuration file.<footnote>
8770 Note that this mechanism is not the same as using
8771 app-defaults; app-defaults are tied to the client
8772 binary on the local file system, whereas X resources
8773 are stored in the X server and affect all connecting
8780 <heading>Installation directory issues</heading>
8783 Historically, packages using the X Window System used a
8784 separate set of installation directories from other packages.
8785 This practice has been discontinued and packages using the X
8786 Window System should now generally be installed in the same
8787 directories as any other package. Specifically, packages must
8788 not install files under the <file>/usr/X11R6/</file> directory
8789 and the <file>/usr/X11R6/</file> directory hierarchy should be
8790 regarded as obsolete.
8794 Include files previously installed under
8795 <file>/usr/X11R6/include/X11/</file> should be installed into
8796 <file>/usr/include/X11/</file>. For files previously
8797 installed into subdirectories of
8798 <file>/usr/X11R6/lib/X11/</file>, package maintainers should
8799 determine if subdirectories of <file>/usr/lib/</file> and
8800 <file>/usr/share/</file> can be used. If not, a subdirectory
8801 of <file>/usr/lib/X11/</file> should be used.
8805 Configuration files for window, display, or session managers
8806 or other applications that are tightly integrated with the X
8807 Window System may be placed in a subdirectory
8808 of <file>/etc/X11/</file> corresponding to the package name.
8809 Other X Window System applications should use
8810 the <file>/etc/</file> directory unless otherwise mandated by
8811 policy (such as for <ref id="appdefaults">).
8816 <heading>The OSF/Motif and OpenMotif libraries</heading>
8819 <em>Programs that require the non-DFSG-compliant OSF/Motif or
8820 OpenMotif libraries</em><footnote>
8821 OSF/Motif and OpenMotif are collectively referred to as
8822 "Motif" in this policy document.
8824 should be compiled against and tested with LessTif (a free
8825 re-implementation of Motif) instead. If the maintainer
8826 judges that the program or programs do not work
8827 sufficiently well with LessTif to be distributed and
8828 supported, but do so when compiled against Motif, then two
8829 versions of the package should be created; one linked
8830 statically against Motif and with <tt>-smotif</tt>
8831 appended to the package name, and one linked dynamically
8832 against Motif and with <tt>-dmotif</tt> appended to the
8837 Both Motif-linked versions are dependent
8838 upon non-DFSG-compliant software and thus cannot be
8839 uploaded to the <em>main</em> distribution; if the
8840 software is itself DFSG-compliant it may be uploaded to
8841 the <em>contrib</em> distribution. While known existing
8842 versions of Motif permit unlimited redistribution of
8843 binaries linked against the library (whether statically or
8844 dynamically), it is the package maintainer's
8845 responsibility to determine whether this is permitted by
8846 the license of the copy of Motif in their possession.
8852 <heading>Perl programs and modules</heading>
8855 Perl programs and modules should follow the current Perl policy.
8859 The Perl policy can be found in the <tt>perl-policy</tt>
8860 files in the <tt>debian-policy</tt> package.
8861 It is also available from the Debian web mirrors at
8862 <tt><url name="/doc/packaging-manuals/perl-policy/"
8863 id="http://www.debian.org/doc/packaging-manuals/perl-policy/"></tt>.
8868 <heading>Emacs lisp programs</heading>
8871 Please refer to the "Debian Emacs Policy" for details of how to
8872 package emacs lisp programs.
8876 The Emacs policy is available in
8877 <file>debian-emacs-policy.gz</file> of the
8878 <package>emacsen-common</package> package.
8879 It is also available from the Debian web mirrors at
8880 <tt><url name="/doc/packaging-manuals/debian-emacs-policy"
8881 id="http://www.debian.org/doc/packaging-manuals/debian-emacs-policy"></tt>.
8886 <heading>Games</heading>
8889 The permissions on <file>/var/games</file> are mode 755, owner
8890 <tt>root</tt> and group <tt>root</tt>.
8894 Each game decides on its own security policy.</p>
8897 Games which require protected, privileged access to
8898 high-score files, saved games, etc., may be made
8899 set-<em>group</em>-id (mode 2755) and owned by
8900 <tt>root:games</tt>, and use files and directories with
8901 appropriate permissions (770 <tt>root:games</tt>, for
8902 example). They must not be made
8903 set-<em>user</em>-id, as this causes security problems. (If
8904 an attacker can subvert any set-user-id game they can
8905 overwrite the executable of any other, causing other players
8906 of these games to run a Trojan horse program. With a
8907 set-group-id game the attacker only gets access to less
8908 important game data, and if they can get at the other
8909 players' accounts at all it will take considerably more
8913 Some packages, for example some fortune cookie programs, are
8914 configured by the upstream authors to install with their
8915 data files or other static information made unreadable so
8916 that they can only be accessed through set-id programs
8917 provided. You should not do this in a Debian package: anyone can
8918 download the <file>.deb</file> file and read the data from it,
8919 so there is no point making the files unreadable. Not
8920 making the files unreadable also means that you don't have
8921 to make so many programs set-id, which reduces the risk of a
8925 As described in the FHS, binaries of games should be
8926 installed in the directory <file>/usr/games</file>. This also
8927 applies to games that use the X Window System. Manual pages
8928 for games (X and non-X games) should be installed in
8929 <file>/usr/share/man/man6</file>.</p>
8935 <heading>Documentation</heading>
8938 <heading>Manual pages</heading>
8941 You should install manual pages in <prgn>nroff</prgn> source
8942 form, in appropriate places under <file>/usr/share/man</file>.
8943 You should only use sections 1 to 9 (see the FHS for more
8944 details). You must not install a pre-formatted "cat page".
8948 Each program, utility, and function should have an
8949 associated manual page included in the same package. It is
8950 suggested that all configuration files also have a manual
8951 page included as well. Manual pages for protocols and other
8952 auxiliary things are optional.
8956 If no manual page is available, this is considered as a bug
8957 and should be reported to the Debian Bug Tracking System (the
8958 maintainer of the package is allowed to write this bug report
8959 themselves, if they so desire). Do not close the bug report
8960 until a proper man page is available.<footnote>
8961 It is not very hard to write a man page. See the
8962 <url id="http://www.schweikhardt.net/man_page_howto.html"
8963 name="Man-Page-HOWTO">,
8964 <manref name="man" section="7">, the examples
8965 created by <prgn>debmake</prgn> or <prgn>dh_make</prgn>,
8966 the helper program <prgn>help2man</prgn>, or the
8967 directory <file>/usr/share/doc/man-db/examples</file>.
8972 You may forward a complaint about a missing man page to the
8973 upstream authors, and mark the bug as forwarded in the
8974 Debian bug tracking system. Even though the GNU Project do
8975 not in general consider the lack of a man page to be a bug,
8976 we do; if they tell you that they don't consider it a bug
8977 you should leave the bug in our bug tracking system open
8982 Manual pages should be installed compressed using <tt>gzip -9</tt>.
8986 If one man page needs to be accessible via several names it
8987 is better to use a symbolic link than the <file>.so</file>
8988 feature, but there is no need to fiddle with the relevant
8989 parts of the upstream source to change from <file>.so</file> to
8990 symlinks: don't do it unless it's easy. You should not
8991 create hard links in the manual page directories, nor put
8992 absolute filenames in <file>.so</file> directives. The filename
8993 in a <file>.so</file> in a man page should be relative to the
8994 base of the man page tree (usually
8995 <file>/usr/share/man</file>). If you do not create any links
8996 (whether symlinks, hard links, or <tt>.so</tt> directives)
8997 in the file system to the alternate names of the man page,
8998 then you should not rely on <prgn>man</prgn> finding your
8999 man page under those names based solely on the information in
9000 the man page's header.<footnote>
9001 Supporting this in <prgn>man</prgn> often requires
9002 unreasonable processing time to find a manual page or to
9003 report that none exists, and moves knowledge into man's
9004 database that would be better left in the file system.
9005 This support is therefore deprecated and will cease to
9006 be present in the future.
9011 Manual pages in locale-specific subdirectories of
9012 <file>/usr/share/man</file> should use either UTF-8 or the usual
9013 legacy encoding for that language (normally the one corresponding
9014 to the shortest relevant locale name in
9015 <file>/usr/share/i18n/SUPPORTED</file>). For example, pages under
9016 <file>/usr/share/man/fr</file> should use either UTF-8 or
9017 ISO-8859-1.<footnote>
9018 <prgn>man</prgn> will automatically detect whether UTF-8 is in
9019 use. In future, all manual pages will be required to use
9025 A country name (the <tt>DE</tt> in <tt>de_DE</tt>) should not be
9026 included in the subdirectory name unless it indicates a
9027 significant difference in the language, as this excludes
9028 speakers of the language in other countries.<footnote>
9029 At the time of writing, Chinese and Portuguese are the main
9030 languages with such differences, so <file>pt_BR</file>,
9031 <file>zh_CN</file>, and <file>zh_TW</file> are all allowed.
9036 If a localized version of a manual page is provided, it should
9037 either be up-to-date or it should be obvious to the reader that
9038 it is outdated and the original manual page should be used
9039 instead. This can be done either by a note at the beginning of
9040 the manual page or by showing the missing or changed portions in
9041 the original language instead of the target language.
9046 <heading>Info documents</heading>
9049 Info documents should be installed in <file>/usr/share/info</file>.
9050 They should be compressed with <tt>gzip -9</tt>.
9054 The <prgn>install-info</prgn> program maintains a directory of
9055 installed info documents in <file>/usr/share/info/dir</file> for
9056 the use of info readers.<footnote>
9057 It was previously necessary for packages installing info
9058 documents to run <prgn>install-info</prgn> from maintainer
9059 scripts. This is no longer necessary. The installation
9060 system now uses dpkg triggers.
9062 This file must not be included in packages. Packages containing
9063 info documents should depend on <tt>dpkg (>= 1.15.4) |
9064 install-info</tt> to ensure that the directory file is properly
9065 rebuilt during partial upgrades from Debian 5.0 (lenny) and
9070 Info documents should contain section and directory entry
9071 information in the document for the use
9072 of <prgn>install-info</prgn>. The section should be specified
9073 via a line starting with <tt>INFO-DIR-SECTION</tt> followed by a
9074 space and the section of this info page. The directory entry or
9075 entries should be included between
9076 a <tt>START-INFO-DIR-ENTRY</tt> line and
9077 an <tt>END-INFO-DIR-ENTRY</tt> line. For example:
9079 INFO-DIR-SECTION Individual utilities
9080 START-INFO-DIR-ENTRY
9081 * example: (example). An example info directory entry.
9084 To determine which section to use, you should look
9085 at <file>/usr/share/info/dir</file> on your system and choose
9086 the most relevant (or create a new section if none of the
9087 current sections are relevant).<footnote>
9088 Normally, info documents are generated from Texinfo source.
9089 To include this information in the generated info document, if
9090 it is absent, add commands like:
9092 @dircategory Individual utilities
9094 * example: (example). An example info directory entry.
9097 to the Texinfo source of the document and ensure that the info
9098 documents are rebuilt from source during the package build.
9104 <heading>Additional documentation</heading>
9107 Any additional documentation that comes with the package may
9108 be installed at the discretion of the package maintainer.
9109 Plain text documentation should be installed in the directory
9110 <file>/usr/share/doc/<var>package</var></file>, where
9111 <var>package</var> is the name of the package, and
9112 compressed with <tt>gzip -9</tt> unless it is small.
9116 If a package comes with large amounts of documentation which
9117 many users of the package will not require you should create
9118 a separate binary package to contain it, so that it does not
9119 take up disk space on the machines of users who do not need
9120 or want it installed.</p>
9123 It is often a good idea to put text information files
9124 (<file>README</file>s, changelogs, and so forth) that come with
9125 the source package in <file>/usr/share/doc/<var>package</var></file>
9126 in the binary package. However, you don't need to install
9127 the instructions for building and installing the package, of
9131 Packages must not require the existence of any files in
9132 <file>/usr/share/doc/</file> in order to function
9134 The system administrator should be able to
9135 delete files in <file>/usr/share/doc/</file> without causing
9136 any programs to break.
9138 Any files that are referenced by programs but are also
9139 useful as stand alone documentation should be installed under
9140 <file>/usr/share/<var>package</var>/</file> with symbolic links from
9141 <file>/usr/share/doc/<var>package</var></file>.
9145 <file>/usr/share/doc/<var>package</var></file> may be a symbolic
9146 link to another directory in <file>/usr/share/doc</file> only if
9147 the two packages both come from the same source and the
9148 first package Depends on the second.<footnote>
9150 Please note that this does not override the section on
9151 changelog files below, so the file
9152 <file>/usr/share/doc/<var>package</var>/changelog.Debian.gz</file>
9153 must refer to the changelog for the current version of
9154 <var>package</var> in question. In practice, this means
9155 that the sources of the target and the destination of the
9156 symlink must be the same (same source package and
9163 Former Debian releases placed all additional documentation
9164 in <file>/usr/doc/<var>package</var></file>. This has been
9165 changed to <file>/usr/share/doc/<var>package</var></file>,
9166 and packages must not put documentation in the directory
9167 <file>/usr/doc/<var>package</var></file>. <footnote>
9168 At this phase of the transition, we no longer require a
9169 symbolic link in <file>/usr/doc/</file>. At a later point,
9170 policy shall change to make the symbolic links a bug.
9176 <heading>Preferred documentation formats</heading>
9179 The unification of Debian documentation is being carried out
9183 If your package comes with extensive documentation in a
9184 markup format that can be converted to various other formats
9185 you should if possible ship HTML versions in a binary
9186 package, in the directory
9187 <file>/usr/share/doc/<var>appropriate-package</var></file> or
9188 its subdirectories.<footnote>
9189 The rationale: The important thing here is that HTML
9190 docs should be available in <em>some</em> package, not
9191 necessarily in the main binary package.
9196 Other formats such as PostScript may be provided at the
9197 package maintainer's discretion.
9201 <sect id="copyrightfile">
9202 <heading>Copyright information</heading>
9205 Every package must be accompanied by a verbatim copy of its
9206 copyright information and distribution license in the file
9207 <file>/usr/share/doc/<var>package</var>/copyright</file>. This
9208 file must neither be compressed nor be a symbolic link.
9212 In addition, the copyright file must say where the upstream
9213 sources (if any) were obtained. It should name the original
9214 authors of the package and the Debian maintainer(s) who were
9215 involved with its creation.
9219 Packages in the <em>contrib</em> or <em>non-free</em> archive
9220 areas should state in the copyright file that the package is not
9221 part of the Debian GNU/Linux distribution and briefly explain
9226 A copy of the file which will be installed in
9227 <file>/usr/share/doc/<var>package</var>/copyright</file> should
9228 be in <file>debian/copyright</file> in the source package.
9232 <file>/usr/share/doc/<var>package</var></file> may be a symbolic
9233 link to another directory in <file>/usr/share/doc</file> only if
9234 the two packages both come from the same source and the
9235 first package Depends on the second. These rules are
9236 important because copyrights must be extractable by
9241 Packages distributed under the Apache license (version 2.0), the
9242 Artistic license, the GNU GPL (version 2 or 3), the GNU LGPL
9243 (versions 2, 2.1, or 3), and the GNU FDL (versions 1.2 or 1.3)
9244 should refer to the corresponding files
9245 under <file>/usr/share/common-licenses</file>,<footnote>
9248 <file>/usr/share/common-licenses/Apache-2.0</file>,
9249 <file>/usr/share/common-licenses/Artistic</file>,
9250 <file>/usr/share/common-licenses/GPL-2</file>,
9251 <file>/usr/share/common-licenses/GPL-3</file>,
9252 <file>/usr/share/common-licenses/LGPL-2</file>,
9253 <file>/usr/share/common-licenses/LGPL-2.1</file>,
9254 <file>/usr/share/common-licenses/LGPL-3</file>,
9255 <file>/usr/share/common-licenses/GFDL-1.2</file>, and
9256 <file>/usr/share/common-licenses/GFDL-1.3</file>
9257 respectively. The University of California BSD license is
9258 also included in <package>base-files</package> as
9259 <file>/usr/share/common-licenses/BSD</file>, but given the
9260 brevity of this license, its specificity to code whose
9261 copyright is held by the Regents of the Univesrity of
9262 California, and the frequency of minor wording changes, its
9263 text should be included in the copyright file rather than
9264 referencing this file.
9266 </footnote> rather than quoting them in the copyright
9271 You should not use the copyright file as a general <file>README</file>
9272 file. If your package has such a file it should be
9273 installed in <file>/usr/share/doc/<var>package</var>/README</file> or
9274 <file>README.Debian</file> or some other appropriate place.</p>
9278 <heading>Examples</heading>
9281 Any examples (configurations, source files, whatever),
9282 should be installed in a directory
9283 <file>/usr/share/doc/<var>package</var>/examples</file>. These
9284 files should not be referenced by any program: they're there
9285 for the benefit of the system administrator and users as
9286 documentation only. Architecture-specific example files
9287 should be installed in a directory
9288 <file>/usr/lib/<var>package</var>/examples</file> with symbolic
9290 <file>/usr/share/doc/<var>package</var>/examples</file>, or the
9291 latter directory itself may be a symbolic link to the
9296 If the purpose of a package is to provide examples, then the
9297 example files may be installed into
9298 <file>/usr/share/doc/<var>package</var></file>.
9302 <sect id="changelogs">
9303 <heading>Changelog files</heading>
9306 Packages that are not Debian-native must contain a
9307 compressed copy of the <file>debian/changelog</file> file from
9308 the Debian source tree in
9309 <file>/usr/share/doc/<var>package</var></file> with the name
9310 <file>changelog.Debian.gz</file>.
9314 If an upstream changelog is available, it should be accessible as
9315 <file>/usr/share/doc/<var>package</var>/changelog.gz</file> in
9316 plain text. If the upstream changelog is distributed in
9317 HTML, it should be made available in that form as
9318 <file>/usr/share/doc/<var>package</var>/changelog.html.gz</file>
9319 and a plain text <file>changelog.gz</file> should be generated
9320 from it using, for example, <tt>lynx -dump -nolist</tt>. If
9321 the upstream changelog files do not already conform to this
9322 naming convention, then this may be achieved either by
9323 renaming the files, or by adding a symbolic link, at the
9324 maintainer's discretion.<footnote>
9325 Rationale: People should not have to look in places for
9326 upstream changelogs merely because they are given
9327 different names or are distributed in HTML format.
9332 All of these files should be installed compressed using
9333 <tt>gzip -9</tt>, as they will become large with time even
9334 if they start out small.
9338 If the package has only one changelog which is used both as
9339 the Debian changelog and the upstream one because there is
9340 no separate upstream maintainer then that changelog should
9341 usually be installed as
9342 <file>/usr/share/doc/<var>package</var>/changelog.gz</file>; if
9343 there is a separate upstream maintainer, but no upstream
9344 changelog, then the Debian changelog should still be called
9345 <file>changelog.Debian.gz</file>.
9349 For details about the format and contents of the Debian
9350 changelog file, please see <ref id="dpkgchangelog">.
9355 <appendix id="pkg-scope">
9356 <heading>Introduction and scope of these appendices</heading>
9359 These appendices are taken essentially verbatim from the
9360 now-deprecated Packaging Manual, version 3.2.1.0. They are
9361 the chapters which are likely to be of use to package
9362 maintainers and which have not already been included in the
9363 policy document itself. Most of these sections are very likely
9364 not relevant to policy; they should be treated as
9365 documentation for the packaging system. Please note that these
9366 appendices are included for convenience, and for historical
9367 reasons: they used to be part of policy package, and they have
9368 not yet been incorporated into dpkg documentation. However,
9369 they still have value, and hence they are presented here.
9373 They have not yet been checked to ensure that they are
9374 compatible with the contents of policy, and if there are any
9375 contradictions, the version in the main policy document takes
9376 precedence. The remaining chapters of the old Packaging
9377 Manual have also not been read in detail to ensure that there
9378 are not parts which have been left out. Both of these will be
9383 Certain parts of the Packaging manual were integrated into the
9384 Policy Manual proper, and removed from the appendices. Links
9385 have been placed from the old locations to the new ones.
9389 <prgn>dpkg</prgn> is a suite of programs for creating binary
9390 package files and installing and removing them on Unix
9392 <prgn>dpkg</prgn> is targeted primarily at Debian
9393 GNU/Linux, but may work on or be ported to other
9399 The binary packages are designed for the management of
9400 installed executable programs (usually compiled binaries) and
9401 their associated data, though source code examples and
9402 documentation are provided as part of some packages.</p>
9405 This manual describes the technical aspects of creating Debian
9406 binary packages (<file>.deb</file> files). It documents the
9407 behavior of the package management programs
9408 <prgn>dpkg</prgn>, <prgn>dselect</prgn> et al. and the way
9409 they interact with packages.</p>
9412 It also documents the interaction between
9413 <prgn>dselect</prgn>'s core and the access method scripts it
9414 uses to actually install the selected packages, and describes
9415 how to create a new access method.</p>
9418 This manual does not go into detail about the options and
9419 usage of the package building and installation tools. It
9420 should therefore be read in conjunction with those programs'
9425 The utility programs which are provided with <prgn>dpkg</prgn>
9426 for managing various system configuration and similar issues,
9427 such as <prgn>update-rc.d</prgn> and
9428 <prgn>install-info</prgn>, are not described in detail here -
9429 please see their man pages.
9433 It is assumed that the reader is reasonably familiar with the
9434 <prgn>dpkg</prgn> System Administrators' manual.
9435 Unfortunately this manual does not yet exist.
9439 The Debian version of the FSF's GNU hello program is provided
9440 as an example for people wishing to create Debian
9441 packages. The Debian <prgn>debmake</prgn> package is
9442 recommended as a very helpful tool in creating and maintaining
9443 Debian packages. However, while the tools and examples are
9444 helpful, they do not replace the need to read and follow the
9445 Policy and Programmer's Manual.</p>
9448 <appendix id="pkg-binarypkg">
9449 <heading>Binary packages (from old Packaging Manual)</heading>
9452 The binary package has two main sections. The first part
9453 consists of various control information files and scripts used
9454 by <prgn>dpkg</prgn> when installing and removing. See <ref
9455 id="pkg-controlarea">.
9459 The second part is an archive containing the files and
9460 directories to be installed.
9464 In the future binary packages may also contain other
9465 components, such as checksums and digital signatures. The
9466 format for the archive is described in full in the
9467 <file>deb(5)</file> man page.
9471 <sect id="pkg-bincreating"><heading>Creating package files -
9472 <prgn>dpkg-deb</prgn>
9476 All manipulation of binary package files is done by
9477 <prgn>dpkg-deb</prgn>; it's the only program that has
9478 knowledge of the format. (<prgn>dpkg-deb</prgn> may be
9479 invoked by calling <prgn>dpkg</prgn>, as <prgn>dpkg</prgn>
9480 will spot that the options requested are appropriate to
9481 <prgn>dpkg-deb</prgn> and invoke that instead with the same
9486 In order to create a binary package you must make a
9487 directory tree which contains all the files and directories
9488 you want to have in the file system data part of the package.
9489 In Debian-format source packages this directory is usually
9490 <file>debian/tmp</file>, relative to the top of the package's
9495 They should have the locations (relative to the root of the
9496 directory tree you're constructing) ownerships and
9497 permissions which you want them to have on the system when
9502 With current versions of <prgn>dpkg</prgn> the uid/username
9503 and gid/groupname mappings for the users and groups being
9504 used should be the same on the system where the package is
9505 built and the one where it is installed.
9509 You need to add one special directory to the root of the
9510 miniature file system tree you're creating:
9511 <prgn>DEBIAN</prgn>. It should contain the control
9512 information files, notably the binary package control file
9513 (see <ref id="pkg-controlfile">).
9517 The <prgn>DEBIAN</prgn> directory will not appear in the
9518 file system archive of the package, and so won't be installed
9519 by <prgn>dpkg</prgn> when the package is installed.
9523 When you've prepared the package, you should invoke:
9525 dpkg --build <var>directory</var>
9530 This will build the package in
9531 <file><var>directory</var>.deb</file>. (<prgn>dpkg</prgn> knows
9532 that <tt>--build</tt> is a <prgn>dpkg-deb</prgn> option, so
9533 it invokes <prgn>dpkg-deb</prgn> with the same arguments to
9538 See the man page <manref name="dpkg-deb" section="8"> for details of how
9539 to examine the contents of this newly-created file. You may find the
9540 output of following commands enlightening:
9542 dpkg-deb --info <var>filename</var>.deb
9543 dpkg-deb --contents <var>filename</var>.deb
9544 dpkg --contents <var>filename</var>.deb
9546 To view the copyright file for a package you could use this command:
9548 dpkg --fsys-tarfile <var>filename</var>.deb | tar xOf - --wildcards \*/copyright | pager
9553 <sect id="pkg-controlarea">
9554 <heading>Package control information files</heading>
9557 The control information portion of a binary package is a
9558 collection of files with names known to <prgn>dpkg</prgn>.
9559 It will treat the contents of these files specially - some
9560 of them contain information used by <prgn>dpkg</prgn> when
9561 installing or removing the package; others are scripts which
9562 the package maintainer wants <prgn>dpkg</prgn> to run.
9566 It is possible to put other files in the package control
9567 area, but this is not generally a good idea (though they
9568 will largely be ignored).
9572 Here is a brief list of the control info files supported by
9573 <prgn>dpkg</prgn> and a summary of what they're used for.
9578 <tag><tt>control</tt>
9581 This is the key description file used by
9582 <prgn>dpkg</prgn>. It specifies the package's name
9583 and version, gives its description for the user,
9584 states its relationships with other packages, and so
9585 forth. See <ref id="sourcecontrolfiles"> and
9586 <ref id="binarycontrolfiles">.
9590 It is usually generated automatically from information
9591 in the source package by the
9592 <prgn>dpkg-gencontrol</prgn> program, and with
9593 assistance from <prgn>dpkg-shlibdeps</prgn>.
9594 See <ref id="pkg-sourcetools">.
9598 <tag><tt>postinst</tt>, <tt>preinst</tt>, <tt>postrm</tt>,
9603 These are executable files (usually scripts) which
9604 <prgn>dpkg</prgn> runs during installation, upgrade
9605 and removal of packages. They allow the package to
9606 deal with matters which are particular to that package
9607 or require more complicated processing than that
9608 provided by <prgn>dpkg</prgn>. Details of when and
9609 how they are called are in <ref id="maintainerscripts">.
9613 It is very important to make these scripts idempotent.
9614 See <ref id="idempotency">.
9618 The maintainer scripts are not guaranteed to run with a
9619 controlling terminal and may not be able to interact with
9620 the user. See <ref id="controllingterminal">.
9624 <tag><tt>conffiles</tt>
9627 This file contains a list of configuration files which
9628 are to be handled automatically by <prgn>dpkg</prgn>
9629 (see <ref id="pkg-conffiles">). Note that not necessarily
9630 every configuration file should be listed here.
9633 <tag><tt>shlibs</tt>
9636 This file contains a list of the shared libraries
9637 supplied by the package, with dependency details for
9638 each. This is used by <prgn>dpkg-shlibdeps</prgn>
9639 when it determines what dependencies are required in a
9640 package control file. The <tt>shlibs</tt> file format
9641 is described on <ref id="shlibs">.
9646 <sect id="pkg-controlfile">
9647 <heading>The main control information file: <tt>control</tt></heading>
9650 The most important control information file used by
9651 <prgn>dpkg</prgn> when it installs a package is
9652 <tt>control</tt>. It contains all the package's "vital
9657 The binary package control files of packages built from
9658 Debian sources are made by a special tool,
9659 <prgn>dpkg-gencontrol</prgn>, which reads
9660 <file>debian/control</file> and <file>debian/changelog</file> to
9661 find the information it needs. See <ref id="pkg-sourcepkg"> for
9666 The fields in binary package control files are listed in
9667 <ref id="binarycontrolfiles">.
9671 A description of the syntax of control files and the purpose
9672 of the fields is available in <ref id="controlfields">.
9677 <heading>Time Stamps</heading>
9680 See <ref id="timestamps">.
9685 <appendix id="pkg-sourcepkg">
9686 <heading>Source packages (from old Packaging Manual) </heading>
9689 The Debian binary packages in the distribution are generated
9690 from Debian sources, which are in a special format to assist
9691 the easy and automatic building of binaries.
9694 <sect id="pkg-sourcetools">
9695 <heading>Tools for processing source packages</heading>
9698 Various tools are provided for manipulating source packages;
9699 they pack and unpack sources and help build of binary
9700 packages and help manage the distribution of new versions.
9704 They are introduced and typical uses described here; see
9705 <manref name="dpkg-source" section="1"> for full
9706 documentation about their arguments and operation.
9710 For examples of how to construct a Debian source package,
9711 and how to use those utilities that are used by Debian
9712 source packages, please see the <prgn>hello</prgn> example
9716 <sect1 id="pkg-dpkg-source">
9718 <prgn>dpkg-source</prgn> - packs and unpacks Debian source
9723 This program is frequently used by hand, and is also
9724 called from package-independent automated building scripts
9725 such as <prgn>dpkg-buildpackage</prgn>.
9729 To unpack a package it is typically invoked with
9731 dpkg-source -x <var>.../path/to/filename</var>.dsc
9736 with the <file><var>filename</var>.tar.gz</file> and
9737 <file><var>filename</var>.diff.gz</file> (if applicable) in
9738 the same directory. It unpacks into
9739 <file><var>package</var>-<var>version</var></file>, and if
9741 <file><var>package</var>-<var>version</var>.orig</file>, in
9742 the current directory.
9746 To create a packed source archive it is typically invoked:
9748 dpkg-source -b <var>package</var>-<var>version</var>
9753 This will create the <file>.dsc</file>, <file>.tar.gz</file> and
9754 <file>.diff.gz</file> (if appropriate) in the current
9755 directory. <prgn>dpkg-source</prgn> does not clean the
9756 source tree first - this must be done separately if it is
9761 See also <ref id="pkg-sourcearchives">.</p>
9765 <sect1 id="pkg-dpkg-buildpackage">
9767 <prgn>dpkg-buildpackage</prgn> - overall package-building
9772 <prgn>dpkg-buildpackage</prgn> is a script which invokes
9773 <prgn>dpkg-source</prgn>, the <file>debian/rules</file>
9774 targets <tt>clean</tt>, <tt>build</tt> and
9775 <tt>binary</tt>, <prgn>dpkg-genchanges</prgn> and
9776 <prgn>gpg</prgn> (or <prgn>pgp</prgn>) to build a signed
9777 source and binary package upload.
9781 It is usually invoked by hand from the top level of the
9782 built or unbuilt source directory. It may be invoked with
9783 no arguments; useful arguments include:
9784 <taglist compact="compact">
9785 <tag><tt>-uc</tt>, <tt>-us</tt></tag>
9788 Do not sign the <tt>.changes</tt> file or the
9789 source package <tt>.dsc</tt> file, respectively.</p>
9791 <tag><tt>-p<var>sign-command</var></tt></tag>
9794 Invoke <var>sign-command</var> instead of finding
9795 <tt>gpg</tt> or <tt>pgp</tt> on the <prgn>PATH</prgn>.
9796 <var>sign-command</var> must behave just like
9797 <prgn>gpg</prgn> or <tt>pgp</tt>.</p>
9799 <tag><tt>-r<var>root-command</var></tt></tag>
9802 When root privilege is required, invoke the command
9803 <var>root-command</var>. <var>root-command</var>
9804 should invoke its first argument as a command, from
9805 the <prgn>PATH</prgn> if necessary, and pass its
9806 second and subsequent arguments to the command it
9807 calls. If no <var>root-command</var> is supplied
9808 then <var>dpkg-buildpackage</var> will take no
9809 special action to gain root privilege, so that for
9810 most packages it will have to be invoked as root to
9813 <tag><tt>-b</tt>, <tt>-B</tt></tag>
9816 Two types of binary-only build and upload - see
9817 <manref name="dpkg-source" section="1">.
9824 <sect1 id="pkg-dpkg-gencontrol">
9826 <prgn>dpkg-gencontrol</prgn> - generates binary package
9831 This program is usually called from <file>debian/rules</file>
9832 (see <ref id="pkg-sourcetree">) in the top level of the source
9837 This is usually done just before the files and directories in the
9838 temporary directory tree where the package is being built have their
9839 permissions and ownerships set and the package is constructed using
9840 <prgn>dpkg-deb/</prgn>
9842 This is so that the control file which is produced has
9843 the right permissions
9848 <prgn>dpkg-gencontrol</prgn> must be called after all the
9849 files which are to go into the package have been placed in
9850 the temporary build directory, so that its calculation of
9851 the installed size of a package is correct.
9855 It is also necessary for <prgn>dpkg-gencontrol</prgn> to
9856 be run after <prgn>dpkg-shlibdeps</prgn> so that the
9857 variable substitutions created by
9858 <prgn>dpkg-shlibdeps</prgn> in <file>debian/substvars</file>
9863 For a package which generates only one binary package, and
9864 which builds it in <file>debian/tmp</file> relative to the top
9865 of the source package, it is usually sufficient to call
9866 <prgn>dpkg-gencontrol</prgn>.
9870 Sources which build several binaries will typically need
9873 dpkg-gencontrol -Pdebian/tmp-<var>pkg</var> -p<var>package</var>
9874 </example> The <tt>-P</tt> tells
9875 <prgn>dpkg-gencontrol</prgn> that the package is being
9876 built in a non-default directory, and the <tt>-p</tt>
9877 tells it which package's control file should be generated.
9881 <prgn>dpkg-gencontrol</prgn> also adds information to the
9882 list of files in <file>debian/files</file>, for the benefit of
9883 (for example) a future invocation of
9884 <prgn>dpkg-genchanges</prgn>.</p>
9887 <sect1 id="pkg-dpkg-shlibdeps">
9889 <prgn>dpkg-shlibdeps</prgn> - calculates shared library
9894 This program is usually called from <file>debian/rules</file>
9895 just before <prgn>dpkg-gencontrol</prgn> (see <ref
9896 id="pkg-sourcetree">), in the top level of the source tree.
9900 Its arguments are executables and shared libraries
9903 They may be specified either in the locations in the
9904 source tree where they are created or in the locations
9905 in the temporary build tree where they are installed
9906 prior to binary package creation.
9908 </footnote> for which shared library dependencies should
9909 be included in the binary package's control file.
9913 If some of the found shared libraries should only
9914 warrant a <tt>Recommends</tt> or <tt>Suggests</tt>, or if
9915 some warrant a <tt>Pre-Depends</tt>, this can be achieved
9916 by using the <tt>-d<var>dependency-field</var></tt> option
9917 before those executable(s). (Each <tt>-d</tt> option
9918 takes effect until the next <tt>-d</tt>.)
9922 <prgn>dpkg-shlibdeps</prgn> does not directly cause the
9923 output control file to be modified. Instead by default it
9924 adds to the <file>debian/substvars</file> file variable
9925 settings like <tt>shlibs:Depends</tt>. These variable
9926 settings must be referenced in dependency fields in the
9927 appropriate per-binary-package sections of the source
9932 For example, a package that generates an essential part
9933 which requires dependencies, and optional parts that
9934 which only require a recommendation, would separate those
9935 two sets of dependencies into two different fields.<footnote>
9936 At the time of writing, an example for this was the
9937 <package/xmms/ package, with Depends used for the xmms
9938 executable, Recommends for the plug-ins and Suggests for
9939 even more optional features provided by unzip.
9941 It can say in its <file>debian/rules</file>:
9943 dpkg-shlibdeps -dDepends <var>program anotherprogram ...</var> \
9944 -dRecommends <var>optionalpart anotheroptionalpart</var>
9946 and then in its main control file <file>debian/control</file>:
9949 Depends: ${shlibs:Depends}
9950 Recommends: ${shlibs:Recommends}
9956 Sources which produce several binary packages with
9957 different shared library dependency requirements can use
9958 the <tt>-p<var>varnameprefix</var></tt> option to override
9959 the default <tt>shlibs:</tt> prefix (one invocation of
9960 <prgn>dpkg-shlibdeps</prgn> per setting of this option).
9961 They can thus produce several sets of dependency
9962 variables, each of the form
9963 <tt><var>varnameprefix</var>:<var>dependencyfield</var></tt>,
9964 which can be referred to in the appropriate parts of the
9965 binary package control files.
9970 <sect1 id="pkg-dpkg-distaddfile">
9972 <prgn>dpkg-distaddfile</prgn> - adds a file to
9973 <file>debian/files</file>
9977 Some packages' uploads need to include files other than
9978 the source and binary package files.
9982 <prgn>dpkg-distaddfile</prgn> adds a file to the
9983 <file>debian/files</file> file so that it will be included in
9984 the <file>.changes</file> file when
9985 <prgn>dpkg-genchanges</prgn> is run.
9989 It is usually invoked from the <tt>binary</tt> target of
9990 <file>debian/rules</file>:
9992 dpkg-distaddfile <var>filename</var> <var>section</var> <var>priority</var>
9994 The <var>filename</var> is relative to the directory where
9995 <prgn>dpkg-genchanges</prgn> will expect to find it - this
9996 is usually the directory above the top level of the source
9997 tree. The <file>debian/rules</file> target should put the
9998 file there just before or just after calling
9999 <prgn>dpkg-distaddfile</prgn>.
10003 The <var>section</var> and <var>priority</var> are passed
10004 unchanged into the resulting <file>.changes</file> file.
10009 <sect1 id="pkg-dpkg-genchanges">
10011 <prgn>dpkg-genchanges</prgn> - generates a <file>.changes</file>
10012 upload control file
10016 This program is usually called by package-independent
10017 automatic building scripts such as
10018 <prgn>dpkg-buildpackage</prgn>, but it may also be called
10023 It is usually called in the top level of a built source
10024 tree, and when invoked with no arguments will print out a
10025 straightforward <file>.changes</file> file based on the
10026 information in the source package's changelog and control
10027 file and the binary and source packages which should have
10033 <sect1 id="pkg-dpkg-parsechangelog">
10035 <prgn>dpkg-parsechangelog</prgn> - produces parsed
10036 representation of a changelog
10040 This program is used internally by
10041 <prgn>dpkg-source</prgn> et al. It may also occasionally
10042 be useful in <file>debian/rules</file> and elsewhere. It
10043 parses a changelog, <file>debian/changelog</file> by default,
10044 and prints a control-file format representation of the
10045 information in it to standard output.
10049 <sect1 id="pkg-dpkg-architecture">
10051 <prgn>dpkg-architecture</prgn> - information about the build and
10056 This program can be used manually, but is also invoked by
10057 <tt>dpkg-buildpackage</tt> or <file>debian/rules</file> to set
10058 environment or make variables which specify the build and host
10059 architecture for the package building process.
10064 <sect id="pkg-sourcetree">
10065 <heading>The Debianised source tree</heading>
10068 The source archive scheme described later is intended to
10069 allow a Debianised source tree with some associated control
10070 information to be reproduced and transported easily. The
10071 Debianised source tree is a version of the original program
10072 with certain files added for the benefit of the
10073 Debianisation process, and with any other changes required
10074 made to the rest of the source code and installation
10079 The extra files created for Debian are in the subdirectory
10080 <file>debian</file> of the top level of the Debianised source
10081 tree. They are described below.
10084 <sect1 id="pkg-debianrules">
10085 <heading><file>debian/rules</file> - the main building script</heading>
10088 See <ref id="debianrules">.
10092 <sect1 id="pkg-srcsubstvars">
10093 <heading><file>debian/substvars</file> and variable substitutions</heading>
10096 See <ref id="substvars">.
10102 <heading><file>debian/files</file></heading>
10105 See <ref id="debianfiles">.
10109 <sect1><heading><file>debian/tmp</file>
10113 This is the canonical temporary location for the
10114 construction of binary packages by the <tt>binary</tt>
10115 target. The directory <file>tmp</file> serves as the root of
10116 the file system tree as it is being constructed (for
10117 example, by using the package's upstream makefiles install
10118 targets and redirecting the output there), and it also
10119 contains the <tt>DEBIAN</tt> subdirectory. See <ref
10120 id="pkg-bincreating">.
10124 If several binary packages are generated from the same
10125 source tree it is usual to use several
10126 <file>debian/tmp<var>something</var></file> directories, for
10127 example <file>tmp-a</file> or <file>tmp-doc</file>.
10131 Whatever <file>tmp</file> directories are created and used by
10132 <tt>binary</tt> must of course be removed by the
10133 <tt>clean</tt> target.</p></sect1>
10137 <sect id="pkg-sourcearchives"><heading>Source packages as archives
10141 As it exists on the FTP site, a Debian source package
10142 consists of three related files. You must have the right
10143 versions of all three to be able to use them.
10148 <tag>Debian source control file - <tt>.dsc</tt></tag>
10150 This file is a control file used by <prgn>dpkg-source</prgn>
10151 to extract a source package.
10152 See <ref id="debiansourcecontrolfiles">.
10156 Original source archive -
10158 <var>package</var>_<var>upstream-version</var>.orig.tar.gz
10164 This is a compressed (with <tt>gzip -9</tt>)
10165 <prgn>tar</prgn> file containing the source code from
10166 the upstream authors of the program.
10171 Debianisation diff -
10173 <var>package</var>_<var>upstream_version-revision</var>.diff.gz
10179 This is a unified context diff (<tt>diff -u</tt>)
10180 giving the changes which are required to turn the
10181 original source into the Debian source. These changes
10182 may only include editing and creating plain files.
10183 The permissions of files, the targets of symbolic
10184 links and the characteristics of special files or
10185 pipes may not be changed and no files may be removed
10190 All the directories in the diff must exist, except the
10191 <file>debian</file> subdirectory of the top of the source
10192 tree, which will be created by
10193 <prgn>dpkg-source</prgn> if necessary when unpacking.
10197 The <prgn>dpkg-source</prgn> program will
10198 automatically make the <file>debian/rules</file> file
10199 executable (see below).</p></item>
10204 If there is no original source code - for example, if the
10205 package is specially prepared for Debian or the Debian
10206 maintainer is the same as the upstream maintainer - the
10207 format is slightly different: then there is no diff, and the
10209 <file><var>package</var>_<var>version</var>.tar.gz</file>,
10210 and preferably contains a directory named
10211 <file><var>package</var>-<var>version</var></file>.
10216 <heading>Unpacking a Debian source package without <prgn>dpkg-source</prgn></heading>
10219 <tt>dpkg-source -x</tt> is the recommended way to unpack a
10220 Debian source package. However, if it is not available it
10221 is possible to unpack a Debian source archive as follows:
10222 <enumlist compact="compact">
10225 Untar the tarfile, which will create a <file>.orig</file>
10229 <p>Rename the <file>.orig</file> directory to
10230 <file><var>package</var>-<var>version</var></file>.</p>
10234 Create the subdirectory <file>debian</file> at the top of
10235 the source tree.</p>
10237 <item><p>Apply the diff using <tt>patch -p0</tt>.</p>
10239 <item><p>Untar the tarfile again if you want a copy of the original
10240 source code alongside the Debianised version.</p>
10245 It is not possible to generate a valid Debian source archive
10246 without using <prgn>dpkg-source</prgn>. In particular,
10247 attempting to use <prgn>diff</prgn> directly to generate the
10248 <file>.diff.gz</file> file will not work.
10252 <heading>Restrictions on objects in source packages</heading>
10255 The source package may not contain any hard links
10257 This is not currently detected when building source
10258 packages, but only when extracting
10262 Hard links may be permitted at some point in the
10263 future, but would require a fair amount of
10265 </footnote>, device special files, sockets or setuid or
10268 Setgid directories are allowed.
10273 The source packaging tools manage the changes between the
10274 original and Debianised source using <prgn>diff</prgn> and
10275 <prgn>patch</prgn>. Turning the original source tree as
10276 included in the <file>.orig.tar.gz</file> into the debianised
10277 source must not involve any changes which cannot be
10278 handled by these tools. Problematic changes which cause
10279 <prgn>dpkg-source</prgn> to halt with an error when
10280 building the source package are:
10281 <list compact="compact">
10282 <item><p>Adding or removing symbolic links, sockets or pipes.</p>
10284 <item><p>Changing the targets of symbolic links.</p>
10286 <item><p>Creating directories, other than <file>debian</file>.</p>
10288 <item><p>Changes to the contents of binary files.</p></item>
10289 </list> Changes which cause <prgn>dpkg-source</prgn> to
10290 print a warning but continue anyway are:
10291 <list compact="compact">
10294 Removing files, directories or symlinks.
10296 Renaming a file is not treated specially - it is
10297 seen as the removal of the old file (which
10298 generates a warning, but is otherwise ignored),
10299 and the creation of the new one.
10305 Changed text files which are missing the usual final
10306 newline (either in the original or the modified
10311 Changes which are not represented, but which are not detected by
10312 <prgn>dpkg-source</prgn>, are:
10313 <list compact="compact">
10314 <item><p>Changing the permissions of files (other than
10315 <file>debian/rules</file>) and directories.</p></item>
10320 The <file>debian</file> directory and <file>debian/rules</file>
10321 are handled specially by <prgn>dpkg-source</prgn> - before
10322 applying the changes it will create the <file>debian</file>
10323 directory, and afterwards it will make
10324 <file>debian/rules</file> world-executable.
10330 <appendix id="pkg-controlfields">
10331 <heading>Control files and their fields (from old Packaging Manual)</heading>
10334 Many of the tools in the <prgn>dpkg</prgn> suite manipulate
10335 data in a common format, known as control files. Binary and
10336 source packages have control data as do the <file>.changes</file>
10337 files which control the installation of uploaded files, and
10338 <prgn>dpkg</prgn>'s internal databases are in a similar
10343 <heading>Syntax of control files</heading>
10346 See <ref id="controlsyntax">.
10350 It is important to note that there are several fields which
10351 are optional as far as <prgn>dpkg</prgn> and the related
10352 tools are concerned, but which must appear in every Debian
10353 package, or whose omission may cause problems.
10358 <heading>List of fields</heading>
10361 See <ref id="controlfieldslist">.
10365 This section now contains only the fields that didn't belong
10366 to the Policy manual.
10369 <sect1 id="pkg-f-Filename">
10370 <heading><tt>Filename</tt> and <tt>MSDOS-Filename</tt></heading>
10373 These fields in <tt>Packages</tt> files give the
10374 filename(s) of (the parts of) a package in the
10375 distribution directories, relative to the root of the
10376 Debian hierarchy. If the package has been split into
10377 several parts the parts are all listed in order, separated
10382 <sect1 id="pkg-f-Size">
10383 <heading><tt>Size</tt> and <tt>MD5sum</tt></heading>
10386 These fields in <file>Packages</file> files give the size (in
10387 bytes, expressed in decimal) and MD5 checksum of the
10388 file(s) which make(s) up a binary package in the
10389 distribution. If the package is split into several parts
10390 the values for the parts are listed in order, separated by
10395 <sect1 id="pkg-f-Status">
10396 <heading><tt>Status</tt></heading>
10399 This field in <prgn>dpkg</prgn>'s status file records
10400 whether the user wants a package installed, removed or
10401 left alone, whether it is broken (requiring
10402 re-installation) or not and what its current state on the
10403 system is. Each of these pieces of information is a
10408 <sect1 id="pkg-f-Config-Version">
10409 <heading><tt>Config-Version</tt></heading>
10412 If a package is not installed or not configured, this
10413 field in <prgn>dpkg</prgn>'s status file records the last
10414 version of the package which was successfully
10419 <sect1 id="pkg-f-Conffiles">
10420 <heading><tt>Conffiles</tt></heading>
10423 This field in <prgn>dpkg</prgn>'s status file contains
10424 information about the automatically-managed configuration
10425 files held by a package. This field should <em>not</em>
10426 appear anywhere in a package!
10431 <heading>Obsolete fields</heading>
10434 These are still recognized by <prgn>dpkg</prgn> but should
10435 not appear anywhere any more.
10437 <taglist compact="compact">
10439 <tag><tt>Revision</tt></tag>
10440 <tag><tt>Package-Revision</tt></tag>
10441 <tag><tt>Package_Revision</tt></tag>
10443 The Debian revision part of the package version was
10444 at one point in a separate control file field. This
10445 field went through several names.
10448 <tag><tt>Recommended</tt></tag>
10449 <item>Old name for <tt>Recommends</tt>.</item>
10451 <tag><tt>Optional</tt></tag>
10452 <item>Old name for <tt>Suggests</tt>.</item>
10454 <tag><tt>Class</tt></tag>
10455 <item>Old name for <tt>Priority</tt>.</item>
10464 <appendix id="pkg-conffiles">
10465 <heading>Configuration file handling (from old Packaging Manual)</heading>
10468 <prgn>dpkg</prgn> can do a certain amount of automatic
10469 handling of package configuration files.
10473 Whether this mechanism is appropriate depends on a number of
10474 factors, but basically there are two approaches to any
10475 particular configuration file.
10479 The easy method is to ship a best-effort configuration in the
10480 package, and use <prgn>dpkg</prgn>'s conffile mechanism to
10481 handle updates. If the user is unlikely to want to edit the
10482 file, but you need them to be able to without losing their
10483 changes, and a new package with a changed version of the file
10484 is only released infrequently, this is a good approach.
10488 The hard method is to build the configuration file from
10489 scratch in the <prgn>postinst</prgn> script, and to take the
10490 responsibility for fixing any mistakes made in earlier
10491 versions of the package automatically. This will be
10492 appropriate if the file is likely to need to be different on
10496 <sect><heading>Automatic handling of configuration files by
10501 A package may contain a control area file called
10502 <tt>conffiles</tt>. This file should be a list of filenames
10503 of configuration files needing automatic handling, separated
10504 by newlines. The filenames should be absolute pathnames,
10505 and the files referred to should actually exist in the
10510 When a package is upgraded <prgn>dpkg</prgn> will process
10511 the configuration files during the configuration stage,
10512 shortly before it runs the package's <prgn>postinst</prgn>
10517 For each file it checks to see whether the version of the
10518 file included in the package is the same as the one that was
10519 included in the last version of the package (the one that is
10520 being upgraded from); it also compares the version currently
10521 installed on the system with the one shipped with the last
10526 If neither the user nor the package maintainer has changed
10527 the file, it is left alone. If one or the other has changed
10528 their version, then the changed version is preferred - i.e.,
10529 if the user edits their file, but the package maintainer
10530 doesn't ship a different version, the user's changes will
10531 stay, silently, but if the maintainer ships a new version
10532 and the user hasn't edited it the new version will be
10533 installed (with an informative message). If both have
10534 changed their version the user is prompted about the problem
10535 and must resolve the differences themselves.
10539 The comparisons are done by calculating the MD5 message
10540 digests of the files, and storing the MD5 of the file as it
10541 was included in the most recent version of the package.
10545 When a package is installed for the first time
10546 <prgn>dpkg</prgn> will install the file that comes with it,
10547 unless that would mean overwriting a file already on the
10552 However, note that <prgn>dpkg</prgn> will <em>not</em>
10553 replace a conffile that was removed by the user (or by a
10554 script). This is necessary because with some programs a
10555 missing file produces an effect hard or impossible to
10556 achieve in another way, so that a missing file needs to be
10557 kept that way if the user did it.
10561 Note that a package should <em>not</em> modify a
10562 <prgn>dpkg</prgn>-handled conffile in its maintainer
10563 scripts. Doing this will lead to <prgn>dpkg</prgn> giving
10564 the user confusing and possibly dangerous options for
10565 conffile update when the package is upgraded.</p>
10568 <sect><heading>Fully-featured maintainer script configuration
10573 For files which contain site-specific information such as
10574 the hostname and networking details and so forth, it is
10575 better to create the file in the package's
10576 <prgn>postinst</prgn> script.
10580 This will typically involve examining the state of the rest
10581 of the system to determine values and other information, and
10582 may involve prompting the user for some information which
10583 can't be obtained some other way.
10587 When using this method there are a couple of important
10588 issues which should be considered:
10592 If you discover a bug in the program which generates the
10593 configuration file, or if the format of the file changes
10594 from one version to the next, you will have to arrange for
10595 the postinst script to do something sensible - usually this
10596 will mean editing the installed configuration file to remove
10597 the problem or change the syntax. You will have to do this
10598 very carefully, since the user may have changed the file,
10599 perhaps to fix the very problem that your script is trying
10600 to deal with - you will have to detect these situations and
10601 deal with them correctly.
10605 If you do go down this route it's probably a good idea to
10606 make the program that generates the configuration file(s) a
10607 separate program in <file>/usr/sbin</file>, by convention called
10608 <file><var>package</var>config</file> and then run that if
10609 appropriate from the post-installation script. The
10610 <tt><var>package</var>config</tt> program should not
10611 unquestioningly overwrite an existing configuration - if its
10612 mode of operation is geared towards setting up a package for
10613 the first time (rather than any arbitrary reconfiguration
10614 later) you should have it check whether the configuration
10615 already exists, and require a <tt>--force</tt> flag to
10616 overwrite it.</p></sect>
10619 <appendix id="pkg-alternatives"><heading>Alternative versions of
10620 an interface - <prgn>update-alternatives</prgn> (from old
10625 When several packages all provide different versions of the
10626 same program or file it is useful to have the system select a
10627 default, but to allow the system administrator to change it
10628 and have their decisions respected.
10632 For example, there are several versions of the <prgn>vi</prgn>
10633 editor, and there is no reason to prevent all of them from
10634 being installed at once, each under their own name
10635 (<prgn>nvi</prgn>, <prgn>vim</prgn> or whatever).
10636 Nevertheless it is desirable to have the name <tt>vi</tt>
10637 refer to something, at least by default.
10641 If all the packages involved cooperate, this can be done with
10642 <prgn>update-alternatives</prgn>.
10646 Each package provides its own version under its own name, and
10647 calls <prgn>update-alternatives</prgn> in its postinst to
10648 register its version (and again in its prerm to deregister
10653 See the man page <manref name="update-alternatives"
10654 section="8"> for details.
10658 If <prgn>update-alternatives</prgn> does not seem appropriate
10659 you may wish to consider using diversions instead.</p>
10662 <appendix id="pkg-diversions"><heading>Diversions - overriding a
10663 package's version of a file (from old Packaging Manual)
10667 It is possible to have <prgn>dpkg</prgn> not overwrite a file
10668 when it reinstalls the package it belongs to, and to have it
10669 put the file from the package somewhere else instead.
10673 This can be used locally to override a package's version of a
10674 file, or by one package to override another's version (or
10675 provide a wrapper for it).
10679 Before deciding to use a diversion, read <ref
10680 id="pkg-alternatives"> to see if you really want a diversion
10681 rather than several alternative versions of a program.
10685 There is a diversion list, which is read by <prgn>dpkg</prgn>,
10686 and updated by a special program <prgn>dpkg-divert</prgn>.
10687 Please see <manref name="dpkg-divert" section="8"> for full
10688 details of its operation.
10692 When a package wishes to divert a file from another, it should
10693 call <prgn>dpkg-divert</prgn> in its preinst to add the
10694 diversion and rename the existing file. For example,
10695 supposing that a <prgn>smailwrapper</prgn> package wishes to
10696 install a wrapper around <file>/usr/sbin/smail</file>:
10698 dpkg-divert --package smailwrapper --add --rename \
10699 --divert /usr/sbin/smail.real /usr/sbin/smail
10700 </example> The <tt>--package smailwrapper</tt> ensures that
10701 <prgn>smailwrapper</prgn>'s copy of <file>/usr/sbin/smail</file>
10702 can bypass the diversion and get installed as the true version.
10703 It's safe to add the diversion unconditionally on upgrades since
10704 it will be left unchanged if it already exists, but
10705 <prgn>dpkg-divert</prgn> will display a message. To suppress that
10706 message, make the command conditional on the version from which
10707 the package is being upgraded:
10709 if [ upgrade != "$1" ] || dpkg --compare-versions "$2" lt 1.0-2; then
10710 dpkg-divert --package smailwrapper --add --rename \
10711 --divert /usr/sbin/smail.real /usr/sbin/smail
10713 </example> where <tt>1.0-2</tt> is the version at which the
10714 diversion was first added to the package. Running the command
10715 during abort-upgrade is pointless but harmless.
10719 The postrm has to do the reverse:
10721 if [ remove = "$1" -o abort-install = "$1" -o disappear = "$1" ]; then
10722 dpkg-divert --package smailwrapper --remove --rename \
10723 --divert /usr/sbin/smail.real /usr/sbin/smail
10725 </example> If the diversion was added at a particular version, the
10726 postrm should also handle the failure case of upgrading from an
10727 older version (unless the older version is so old that direct
10728 upgrades are no longer supported):
10730 if [ abort-upgrade = "$1" ] && dpkg --compare-versions "$2" lt 1.0-2; then
10731 dpkg-divert --package smailwrapper --remove --rename \
10732 --divert /usr/sbin/smail.real /usr/sbin/smail
10734 </example> where <tt>1.02-2</tt> is the version at which the
10735 diversion was first added to the package. The postrm should not
10736 remove the diversion on upgrades both because there's no reason to
10737 remove the diversion only to immediately re-add it and since the
10738 postrm of the old package is run after unpacking so the removal of
10739 the diversion will fail.
10743 Do not attempt to divert a file which is vitally important for
10744 the system's operation - when using <prgn>dpkg-divert</prgn>
10745 there is a time, after it has been diverted but before
10746 <prgn>dpkg</prgn> has installed the new version, when the file
10747 does not exist.</p>
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