1 <!doctype debiandoc system [
2 <!-- include version information so we don't have to hard code it
3 within the document -->
4 <!entity % versiondata SYSTEM "version.ent"> %versiondata;
5 <!-- current Debian changes file format -->
6 <!entity changesversion "1.8">
12 <title>Debian Policy Manual</title>
13 <author><qref id="authors">The Debian Policy Mailing List</qref></author>
14 <version>version &version;, &date;</version>
17 This manual describes the policy requirements for the Debian
18 distribution. This includes the structure and
19 contents of the Debian archive and several design issues of
20 the operating system, as well as technical requirements that
21 each package must satisfy to be included in the distribution.
26 Copyright © 1996,1997,1998 Ian Jackson
27 and Christian Schwarz.
30 These are the copyright dates of the original Policy manual.
31 Since then, this manual has been updated by many others. No
32 comprehensive collection of copyright notices for subsequent
37 This manual is free software; you may redistribute it and/or
38 modify it under the terms of the GNU General Public License
39 as published by the Free Software Foundation; either version
40 2, or (at your option) any later version.
44 This is distributed in the hope that it will be useful, but
45 <em>without any warranty</em>; without even the implied
46 warranty of merchantability or fitness for a particular
47 purpose. See the GNU General Public License for more
52 A copy of the GNU General Public License is available as
53 <file>/usr/share/common-licenses/GPL</file> in the Debian
54 distribution or on the World Wide Web at
55 <url id="http://www.gnu.org/copyleft/gpl.html"
56 name="the GNU General Public Licence">. You can also
57 obtain it by writing to the Free Software Foundation, Inc.,
58 51 Franklin St, Fifth Floor, Boston, MA 02110-1301, USA.
66 <heading>About this manual</heading>
68 <heading>Scope</heading>
70 This manual describes the policy requirements for the Debian
71 distribution. This includes the structure and
72 contents of the Debian archive and several design issues of the
73 operating system, as well as technical requirements that
74 each package must satisfy to be included in the
79 This manual also describes Debian policy as it relates to
80 creating Debian packages. It is not a tutorial on how to build
81 packages, nor is it exhaustive where it comes to describing
82 the behavior of the packaging system. Instead, this manual
83 attempts to define the interface to the package management
84 system that the developers have to be conversant with.<footnote>
85 Informally, the criteria used for inclusion is that the
86 material meet one of the following requirements:
87 <taglist compact="compact">
88 <tag>Standard interfaces</tag>
90 The material presented represents an interface to
91 the packaging system that is mandated for use, and
92 is used by, a significant number of packages, and
93 therefore should not be changed without peer
94 review. Package maintainers can then rely on this
95 interface not changing, and the package management
96 software authors need to ensure compatibility with
97 this interface definition. (Control file and
98 changelog file formats are examples.)
100 <tag>Chosen Convention</tag>
102 If there are a number of technically viable choices
103 that can be made, but one needs to select one of
104 these options for inter-operability. The version
105 number format is one example.
108 Please note that these are not mutually exclusive;
109 selected conventions often become parts of standard
115 The footnotes present in this manual are
116 merely informative, and are not part of Debian policy itself.
120 The appendices to this manual are not necessarily normative,
121 either. Please see <ref id="pkg-scope"> for more information.
125 In the normative part of this manual,
126 the words <em>must</em>, <em>should</em> and
127 <em>may</em>, and the adjectives <em>required</em>,
128 <em>recommended</em> and <em>optional</em>, are used to
129 distinguish the significance of the various guidelines in
130 this policy document. Packages that do not conform to the
131 guidelines denoted by <em>must</em> (or <em>required</em>)
132 will generally not be considered acceptable for the Debian
133 distribution. Non-conformance with guidelines denoted by
134 <em>should</em> (or <em>recommended</em>) will generally be
135 considered a bug, but will not necessarily render a package
136 unsuitable for distribution. Guidelines denoted by
137 <em>may</em> (or <em>optional</em>) are truly optional and
138 adherence is left to the maintainer's discretion.
142 These classifications are roughly equivalent to the bug
143 severities <em>serious</em> (for <em>must</em> or
144 <em>required</em> directive violations), <em>minor</em>,
145 <em>normal</em> or <em>important</em>
146 (for <em>should</em> or <em>recommended</em> directive
147 violations) and <em>wishlist</em> (for <em>optional</em>
150 Compare RFC 2119. Note, however, that these words are
151 used in a different way in this document.
156 Much of the information presented in this manual will be
157 useful even when building a package which is to be
158 distributed in some other way or is intended for local use
164 <heading>New versions of this document</heading>
167 This manual is distributed via the Debian package
168 <package><url name="debian-policy"
169 id="http://packages.debian.org/debian-policy"></package>
170 (<httpsite>packages.debian.org</httpsite>
171 <httppath>/debian-policy</httppath>).
175 The current version of this document is also available from
176 the Debian web mirrors at
177 <tt><url name="/doc/debian-policy/"
178 id="http://www.debian.org/doc/debian-policy/"></tt>.
180 <httpsite>www.debian.org</httpsite>
181 <httppath>/doc/debian-policy/</httppath>)
182 Also available from the same directory are several other
183 formats: <file>policy.html.tar.gz</file>
184 (<httppath>/doc/debian-policy/policy.html.tar.gz</httppath>),
185 <file>policy.pdf.gz</file>
186 (<httppath>/doc/debian-policy/policy.pdf.gz</httppath>)
187 and <file>policy.ps.gz</file>
188 (<httppath>/doc/debian-policy/policy.ps.gz</httppath>).
192 The <package>debian-policy</package> package also includes the file
193 <file>upgrading-checklist.txt.gz</file> which indicates policy
194 changes between versions of this document.
199 <heading>Authors and Maintainers</heading>
202 Originally called "Debian GNU/Linux Policy Manual", this
203 manual was initially written in 1996 by Ian Jackson.
204 It was revised on November 27th, 1996 by David A. Morris.
205 Christian Schwarz added new sections on March 15th, 1997,
206 and reworked/restructured it in April-July 1997.
207 Christoph Lameter contributed the "Web Standard".
208 Julian Gilbey largely restructured it in 2001.
212 Since September 1998, the responsibility for the contents of
213 this document lies on the <url name="debian-policy mailing list"
214 id="mailto:debian-policy@lists.debian.org">. Proposals
215 are discussed there and inserted into policy after a certain
216 consensus is established.
217 <!-- insert shameless policy-process plug here eventually -->
218 The actual editing is done by a group of maintainers that have
219 no editorial powers. These are the current maintainers:
222 <item>Julian Gilbey</item>
223 <item>Branden Robinson</item>
224 <item>Josip Rodin</item>
225 <item>Manoj Srivastava</item>
230 While the authors of this document have tried hard to avoid
231 typos and other errors, these do still occur. If you discover
232 an error in this manual or if you want to give any
233 comments, suggestions, or criticisms please send an email to
234 the Debian Policy List,
235 <email>debian-policy@lists.debian.org</email>, or submit a
236 bug report against the <tt>debian-policy</tt> package.
240 Please do not try to reach the individual authors or maintainers
241 of the Policy Manual regarding changes to the Policy.
246 <heading>Related documents</heading>
249 There are several other documents other than this Policy Manual
250 that are necessary to fully understand some Debian policies and
255 The external "sub-policy" documents are referred to in:
256 <list compact="compact">
257 <item><ref id="fhs"></item>
258 <item><ref id="virtual_pkg"></item>
259 <item><ref id="menus"></item>
260 <item><ref id="mime"></item>
261 <item><ref id="perl"></item>
262 <item><ref id="maintscriptprompt"></item>
263 <item><ref id="emacs"></item>
268 In addition to those, which carry the weight of policy, there
269 is the Debian Developer's Reference. This document describes
270 procedures and resources for Debian developers, but it is
271 <em>not</em> normative; rather, it includes things that don't
272 belong in the Policy, such as best practices for developers.
276 The Developer's Reference is available in the
277 <package>developers-reference</package> package.
278 It's also available from the Debian web mirrors at
279 <tt><url name="/doc/developers-reference/"
280 id="http://www.debian.org/doc/developers-reference/"></tt>.
284 <sect id="definitions">
285 <heading>Definitions</heading>
288 The following terms are used in this Policy Manual:
292 The character encoding specified by ANSI X3.4-1986 and its
293 predecessor standards, referred to in MIME as US-ASCII, and
294 corresponding to an encoding in eight bits per character of
295 the first 128 <url id="http://www.unicode.org/"
296 name="Unicode"> characters, with the eighth bit always zero.
300 The transformation format (sometimes called encoding) of
301 <url id="http://www.unicode.org/" name="Unicode"> defined by
302 <url id="http://www.rfc-editor.org/rfc/rfc3629.txt"
303 name="RFC 3629">. UTF-8 has the useful property of having
304 ASCII as a subset, so any text encoded in ASCII is trivially
314 <heading>The Debian Archive</heading>
317 The Debian system is maintained and distributed as a
318 collection of <em>packages</em>. Since there are so many of
319 them (currently well over 15000), they are split into
320 <em>sections</em> and given <em>priorities</em> to simplify
321 the handling of them.
325 The effort of the Debian project is to build a free operating
326 system, but not every package we want to make accessible is
327 <em>free</em> in our sense (see the Debian Free Software
328 Guidelines, below), or may be imported/exported without
329 restrictions. Thus, the archive is split into areas<footnote>
330 The Debian archive software uses the term "component" internally
331 and in the Release file format to refer to the division of an
332 archive. The Debian Social Contract simply refers to "areas."
333 This document uses terminology similar to the Social Contract.
334 </footnote> based on their licenses and other restrictions.
338 The aims of this are:
340 <list compact="compact">
341 <item>to allow us to make as much software available as we can</item>
342 <item>to allow us to encourage everyone to write free software,
344 <item>to allow us to make it easy for people to produce
345 CD-ROMs of our system without violating any licenses,
346 import/export restrictions, or any other laws.</item>
351 The <em>main</em> archive area forms the <em>Debian distribution</em>.
355 Packages in the other archive areas (<tt>contrib</tt>,
356 <tt>non-free</tt>) are not considered to be part of the Debian
357 distribution, although we support their use and provide
358 infrastructure for them (such as our bug-tracking system and
359 mailing lists). This Debian Policy Manual applies to these
364 <heading>The Debian Free Software Guidelines</heading>
366 The Debian Free Software Guidelines (DFSG) form our
367 definition of "free software". These are:
369 <tag>1. Free Redistribution
372 The license of a Debian component may not restrict any
373 party from selling or giving away the software as a
374 component of an aggregate software distribution
375 containing programs from several different
376 sources. The license may not require a royalty or
377 other fee for such sale.
382 The program must include source code, and must allow
383 distribution in source code as well as compiled form.
385 <tag>3. Derived Works
388 The license must allow modifications and derived
389 works, and must allow them to be distributed under the
390 same terms as the license of the original software.
392 <tag>4. Integrity of The Author's Source Code
395 The license may restrict source-code from being
396 distributed in modified form <em>only</em> if the
397 license allows the distribution of "patch files"
398 with the source code for the purpose of modifying the
399 program at build time. The license must explicitly
400 permit distribution of software built from modified
401 source code. The license may require derived works to
402 carry a different name or version number from the
403 original software. (This is a compromise. The Debian
404 Project encourages all authors to not restrict any
405 files, source or binary, from being modified.)
407 <tag>5. No Discrimination Against Persons or Groups
410 The license must not discriminate against any person
413 <tag>6. No Discrimination Against Fields of Endeavor
416 The license must not restrict anyone from making use
417 of the program in a specific field of endeavor. For
418 example, it may not restrict the program from being
419 used in a business, or from being used for genetic
422 <tag>7. Distribution of License
425 The rights attached to the program must apply to all
426 to whom the program is redistributed without the need
427 for execution of an additional license by those
430 <tag>8. License Must Not Be Specific to Debian
433 The rights attached to the program must not depend on
434 the program's being part of a Debian system. If the
435 program is extracted from Debian and used or
436 distributed without Debian but otherwise within the
437 terms of the program's license, all parties to whom
438 the program is redistributed must have the same
439 rights as those that are granted in conjunction with
442 <tag>9. License Must Not Contaminate Other Software
445 The license must not place restrictions on other
446 software that is distributed along with the licensed
447 software. For example, the license must not insist
448 that all other programs distributed on the same medium
449 must be free software.
451 <tag>10. Example Licenses
454 The "GPL," "BSD," and "Artistic" licenses are examples of
455 licenses that we consider <em>free</em>.
462 <heading>Archive areas</heading>
465 <heading>The main archive area</heading>
468 Every package in <em>main</em> must comply with the DFSG
469 (Debian Free Software Guidelines).
473 In addition, the packages in <em>main</em>
474 <list compact="compact">
476 must not require a package outside of <em>main</em>
477 for compilation or execution (thus, the package must
478 not declare a "Depends", "Recommends", or
479 "Build-Depends" relationship on a non-<em>main</em>
483 must not be so buggy that we refuse to support them,
487 must meet all policy requirements presented in this
496 <heading>The contrib archive area</heading>
499 Every package in <em>contrib</em> must comply with the DFSG.
503 In addition, the packages in <em>contrib</em>
504 <list compact="compact">
506 must not be so buggy that we refuse to support them,
510 must meet all policy requirements presented in this
518 Examples of packages which would be included in
519 <em>contrib</em> are:
520 <list compact="compact">
522 free packages which require <em>contrib</em>,
523 <em>non-free</em> packages or packages which are not
524 in our archive at all for compilation or execution,
528 wrapper packages or other sorts of free accessories for
535 <sect1 id="non-free">
536 <heading>The non-free archive area</heading>
539 Packages must be placed in <em>non-free</em> if they are
540 not compliant with the DFSG or are encumbered by patents
541 or other legal issues that make their distribution
546 In addition, the packages in <em>non-free</em>
547 <list compact="compact">
549 must not be so buggy that we refuse to support them,
553 must meet all policy requirements presented in this
554 manual that it is possible for them to meet.
556 It is possible that there are policy
557 requirements which the package is unable to
558 meet, for example, if the source is
559 unavailable. These situations will need to be
560 handled on a case-by-case basis.
569 <sect id="pkgcopyright">
570 <heading>Copyright considerations</heading>
573 Every package must be accompanied by a verbatim copy of its
574 copyright information and distribution license in the file
575 <file>/usr/share/doc/<var>package</var>/copyright</file>
576 (see <ref id="copyrightfile"> for further details).
580 We reserve the right to restrict files from being included
581 anywhere in our archives if
582 <list compact="compact">
584 their use or distribution would break a law,
587 there is an ethical conflict in their distribution or
591 we would have to sign a license for them, or
594 their distribution would conflict with other project
601 Programs whose authors encourage the user to make
602 donations are fine for the main distribution, provided
603 that the authors do not claim that not donating is
604 immoral, unethical, illegal or something similar; in such
605 a case they must go in <em>non-free</em>.
609 Packages whose copyright permission notices (or patent
610 problems) do not even allow redistribution of binaries
611 only, and where no special permission has been obtained,
612 must not be placed on the Debian FTP site and its mirrors
617 Note that under international copyright law (this applies
618 in the United States, too), <em>no</em> distribution or
619 modification of a work is allowed without an explicit
620 notice saying so. Therefore a program without a copyright
621 notice <em>is</em> copyrighted and you may not do anything
622 to it without risking being sued! Likewise if a program
623 has a copyright notice but no statement saying what is
624 permitted then nothing is permitted.
628 Many authors are unaware of the problems that restrictive
629 copyrights (or lack of copyright notices) can cause for
630 the users of their supposedly-free software. It is often
631 worthwhile contacting such authors diplomatically to ask
632 them to modify their license terms. However, this can be a
633 politically difficult thing to do and you should ask for
634 advice on the <tt>debian-legal</tt> mailing list first, as
639 When in doubt about a copyright, send mail to
640 <email>debian-legal@lists.debian.org</email>. Be prepared
641 to provide us with the copyright statement. Software
642 covered by the GPL, public domain software and BSD-like
643 copyrights are safe; be wary of the phrases "commercial
644 use prohibited" and "distribution restricted".
648 <sect id="subsections">
649 <heading>Sections</heading>
652 The packages in the archive areas <em>main</em>,
653 <em>contrib</em> and <em>non-free</em> are grouped further into
654 <em>sections</em> to simplify handling.
658 The archive area and section for each package should be
659 specified in the package's <tt>Section</tt> control record (see
660 <ref id="f-Section">). However, the maintainer of the Debian
661 archive may override this selection to ensure the consistency of
662 the Debian distribution. The <tt>Section</tt> field should be
664 <list compact="compact">
666 <em>section</em> if the package is in the
667 <em>main</em> archive area,
670 <em>area/section</em> if the package is in
671 the <em>contrib</em> or <em>non-free</em>
678 The Debian archive maintainers provide the authoritative
679 list of sections. At present, they are:
680 <em>admin</em>, <em>cli-mono</em>, <em>comm</em>, <em>database</em>,
681 <em>devel</em>, <em>debug</em>, <em>doc</em>, <em>editors</em>,
682 <em>electronics</em>, <em>embedded</em>, <em>fonts</em>,
683 <em>games</em>, <em>gnome</em>, <em>graphics</em>, <em>gnu-r</em>,
684 <em>gnustep</em>, <em>hamradio</em>, <em>haskell</em>,
685 <em>httpd</em>, <em>interpreters</em>, <em>java</em>, <em>kde</em>,
686 <em>kernel</em>, <em>libs</em>, <em>libdevel</em>, <em>lisp</em>,
687 <em>localization</em>, <em>mail</em>, <em>math</em>, <em>misc</em>,
688 <em>net</em>, <em>news</em>, <em>ocaml</em>, <em>oldlibs</em>,
689 <em>otherosfs</em>, <em>perl</em>, <em>php</em>, <em>python</em>,
690 <em>ruby</em>, <em>science</em>, <em>shells</em>, <em>sound</em>,
691 <em>tex</em>, <em>text</em>, <em>utils</em>, <em>vcs</em>,
692 <em>video</em>, <em>web</em>, <em>x11</em>, <em>xfce</em>,
693 <em>zope</em>. The additional section <em>debian-installer</em>
694 contains special packages used by the installer and is not used
695 for normal Debian packages.
699 For more information about the sections and their definitions,
700 see the <url id="http://packages.debian.org/unstable/"
701 name="list of sections in unstable">.
705 <sect id="priorities">
706 <heading>Priorities</heading>
709 Each package should have a <em>priority</em> value, which is
710 included in the package's <em>control record</em>
711 (see <ref id="f-Priority">).
712 This information is used by the Debian package management tools to
713 separate high-priority packages from less-important packages.
717 The following <em>priority levels</em> are recognized by the
718 Debian package management tools.
720 <tag><tt>required</tt></tag>
722 Packages which are necessary for the proper
723 functioning of the system (usually, this means that
724 dpkg functionality depends on these packages).
725 Removing a <tt>required</tt> package may cause your
726 system to become totally broken and you may not even
727 be able to use <prgn>dpkg</prgn> to put things back,
728 so only do so if you know what you are doing. Systems
729 with only the <tt>required</tt> packages are probably
730 unusable, but they do have enough functionality to
731 allow the sysadmin to boot and install more software.
733 <tag><tt>important</tt></tag>
735 Important programs, including those which one would
736 expect to find on any Unix-like system. If the
737 expectation is that an experienced Unix person who
738 found it missing would say "What on earth is going on,
739 where is <prgn>foo</prgn>?", it must be an
740 <tt>important</tt> package.<footnote>
741 This is an important criterion because we are
742 trying to produce, amongst other things, a free
745 Other packages without which the system will not run
746 well or be usable must also have priority
747 <tt>important</tt>. This does
748 <em>not</em> include Emacs, the X Window System, TeX
749 or any other large applications. The
750 <tt>important</tt> packages are just a bare minimum of
751 commonly-expected and necessary tools.
753 <tag><tt>standard</tt></tag>
755 These packages provide a reasonably small but not too
756 limited character-mode system. This is what will be
757 installed by default if the user doesn't select anything
758 else. It doesn't include many large applications.
760 <tag><tt>optional</tt></tag>
762 (In a sense everything that isn't required is
763 optional, but that's not what is meant here.) This is
764 all the software that you might reasonably want to
765 install if you didn't know what it was and don't have
766 specialized requirements. This is a much larger system
767 and includes the X Window System, a full TeX
768 distribution, and many applications. Note that
769 optional packages should not conflict with each other.
771 <tag><tt>extra</tt></tag>
773 This contains all packages that conflict with others
774 with required, important, standard or optional
775 priorities, or are only likely to be useful if you
776 already know what they are or have specialized
777 requirements (such as packages containing only detached
784 Packages must not depend on packages with lower priority
785 values (excluding build-time dependencies). In order to
786 ensure this, the priorities of one or more packages may need
795 <heading>Binary packages</heading>
798 The Debian distribution is based on the Debian
799 package management system, called <prgn>dpkg</prgn>. Thus,
800 all packages in the Debian distribution must be provided
801 in the <tt>.deb</tt> file format.
805 A <tt>.deb</tt> package contains two sets of files: a set of files
806 to install on the system when the package is installed, and a set
807 of files that provide additional metadata about the package or
808 which are executed when the package is installed or removed. This
809 second set of files is called <em>control information files</em>.
810 Among those files are the package maintainer scripts
811 and <file>control</file>, the <qref id="binarycontrolfiles">binary
812 package control file</qref> that contains the control fields for
813 the package. Other control information files
814 include <qref id="sharedlibs-shlibdeps">the <file>shlibs</file>
815 file</qref> used to store shared library dependency information
816 and the <file>conffiles</file> file that lists the package's
817 configuration files (described in <ref id="config-files">).
821 There is unfortunately a collision of terminology here between
822 control information files and files in the Debian control file
823 format. Throughout this document, a <em>control file</em> refers
824 to a file in the Debian control file format. These files are
825 documented in <ref id="controlfields">. Only files referred to
826 specifically as <em>control information files</em> are the files
827 included in the control information file member of
828 the <file>.deb</file> file format used by binary packages. Most
829 control information files are not in the Debian control file
834 <heading>The package name</heading>
837 Every package must have a name that's unique within the Debian
842 The package name is included in the control field
843 <tt>Package</tt>, the format of which is described
844 in <ref id="f-Package">.
845 The package name is also included as a part of the file name
846 of the <tt>.deb</tt> file.
851 <heading>The version of a package</heading>
854 Every package has a version number recorded in its
855 <tt>Version</tt> control file field, described in
856 <ref id="f-Version">.
860 The package management system imposes an ordering on version
861 numbers, so that it can tell whether packages are being up- or
862 downgraded and so that package system front end applications
863 can tell whether a package it finds available is newer than
864 the one installed on the system. The version number format
865 has the most significant parts (as far as comparison is
866 concerned) at the beginning.
870 If an upstream package has problematic version numbers they
871 should be converted to a sane form for use in the
872 <tt>Version</tt> field.
876 <heading>Version numbers based on dates</heading>
879 In general, Debian packages should use the same version
880 numbers as the upstream sources. However, upstream version
881 numbers based on some date formats (sometimes used for
882 development or "snapshot" releases) will not be ordered
883 correctly by the package management software. For
884 example, <prgn>dpkg</prgn> will consider "96May01" to be
885 greater than "96Dec24".
889 To prevent having to use epochs for every new upstream
890 version, the date-based portion of any upstream version number
891 should be given in a way that sorts correctly: four-digit year
892 first, followed by a two-digit numeric month, followed by a
893 two-digit numeric date, possibly with punctuation between the
898 Native Debian packages (i.e., packages which have been written
899 especially for Debian) whose version numbers include dates
900 should also follow these rules. If punctuation is desired
901 between the date components, remember that hyphen (<tt>-</tt>)
902 cannot be used in native package versions. Period
903 (<tt>.</tt>) is normally a good choice.
909 <sect id="maintainer">
910 <heading>The maintainer of a package</heading>
913 Every package must have a maintainer, except for orphaned
914 packages as described below. The maintainer may be one person
915 or a group of people reachable from a common email address, such
916 as a mailing list. The maintainer is responsible for
917 maintaining the Debian packaging files, evaluating and
918 responding appropriately to reported bugs, uploading new
919 versions of the package (either directly or through a sponsor),
920 ensuring that the package is placed in the appropriate archive
921 area and included in Debian releases as appropriate for the
922 stability and utility of the package, and requesting removal of
923 the package from the Debian distribution if it is no longer
924 useful or maintainable.
928 The maintainer must be specified in the <tt>Maintainer</tt>
929 control field with their correct name and a working email
930 address. The email address given in the <tt>Maintainer</tt>
931 control field must accept mail from those role accounts in
932 Debian used to send automated mails regarding the package. This
933 includes non-spam mail from the bug-tracking system, all mail
934 from the Debian archive maintenance software, and other role
935 accounts or automated processes that are commonly agreed on by
936 the project.<footnote>
937 A sample implementation of such a whitelist written for the
938 Mailman mailing list management software is used for mailing
939 lists hosted by alioth.debian.org.
941 If one person or team maintains several packages, they should
942 use the same form of their name and email address in
943 the <tt>Maintainer</tt> fields of those packages.
947 The format of the <tt>Maintainer</tt> control field is
948 described in <ref id="f-Maintainer">.
952 If the maintainer of the package is a team of people with a
953 shared email address, the <tt>Uploaders</tt> control field must
954 be present and must contain at least one human with their
955 personal email address. See <ref id="f-Uploaders"> for the
956 syntax of that field.
960 An orphaned package is one with no current maintainer. Orphaned
961 packages should have their <tt>Maintainer</tt> control field set
962 to <tt>Debian QA Group <packages@qa.debian.org></tt>.
963 These packages are considered maintained by the Debian project
964 as a whole until someone else volunteers to take over
965 maintenance.<footnote>
966 The detailed procedure for gracefully orphaning a package can
967 be found in the Debian Developer's Reference
968 (see <ref id="related">).
973 <sect id="descriptions">
974 <heading>The description of a package</heading>
977 Every Debian package must have a <tt>Description</tt> control
978 field which contains a synopsis and extended description of the
979 package. Technical information about the format of the
980 <tt>Description</tt> field is in <ref id="f-Description">.
984 The description should describe the package (the program) to a
985 user (system administrator) who has never met it before so that
986 they have enough information to decide whether they want to
987 install it. This description should not just be copied verbatim
988 from the program's documentation.
992 Put important information first, both in the synopsis and
993 extended description. Sometimes only the first part of the
994 synopsis or of the description will be displayed. You can
995 assume that there will usually be a way to see the whole
996 extended description.
1000 The description should also give information about the
1001 significant dependencies and conflicts between this package
1002 and others, so that the user knows why these dependencies and
1003 conflicts have been declared.
1007 Instructions for configuring or using the package should
1008 not be included (that is what installation scripts,
1009 manual pages, info files, etc., are for). Copyright
1010 statements and other administrivia should not be included
1011 either (that is what the copyright file is for).
1014 <sect1 id="synopsis"><heading>The single line synopsis</heading>
1017 The single line synopsis should be kept brief - certainly
1018 under 80 characters.
1022 Do not include the package name in the synopsis line. The
1023 display software knows how to display this already, and you
1024 do not need to state it. Remember that in many situations
1025 the user may only see the synopsis line - make it as
1026 informative as you can.
1031 <sect1 id="extendeddesc"><heading>The extended description</heading>
1034 Do not try to continue the single line synopsis into the
1035 extended description. This will not work correctly when
1036 the full description is displayed, and makes no sense
1037 where only the summary (the single line synopsis) is
1042 The extended description should describe what the package
1043 does and how it relates to the rest of the system (in terms
1044 of, for example, which subsystem it is which part of).
1048 The description field needs to make sense to anyone, even
1049 people who have no idea about any of the things the
1050 package deals with.<footnote>
1051 The blurb that comes with a program in its
1052 announcements and/or <prgn>README</prgn> files is
1053 rarely suitable for use in a description. It is
1054 usually aimed at people who are already in the
1055 community where the package is used.
1064 <heading>Dependencies</heading>
1067 Every package must specify the dependency information
1068 about other packages that are required for the first to
1073 For example, a dependency entry must be provided for any
1074 shared libraries required by a dynamically-linked executable
1075 binary in a package.
1079 Packages are not required to declare any dependencies they
1080 have on other packages which are marked <tt>Essential</tt>
1081 (see below), and should not do so unless they depend on a
1082 particular version of that package.<footnote>
1084 Essential is needed in part to avoid unresolvable dependency
1085 loops on upgrade. If packages add unnecessary dependencies
1086 on packages in this set, the chances that there
1087 <strong>will</strong> be an unresolvable dependency loop
1088 caused by forcing these Essential packages to be configured
1089 first before they need to be is greatly increased. It also
1090 increases the chances that frontends will be unable to
1091 <strong>calculate</strong> an upgrade path, even if one
1095 Also, functionality is rarely ever removed from the
1096 Essential set, but <em>packages</em> have been removed from
1097 the Essential set when the functionality moved to a
1098 different package. So depending on these packages <em>just
1099 in case</em> they stop being essential does way more harm
1106 Sometimes, unpacking one package requires that another package
1107 be first unpacked <em>and</em> configured. In this case, the
1108 depending package must specify this dependency in
1109 the <tt>Pre-Depends</tt> control field.
1113 You should not specify a <tt>Pre-Depends</tt> entry for a
1114 package before this has been discussed on the
1115 <tt>debian-devel</tt> mailing list and a consensus about
1116 doing that has been reached.
1120 The format of the package interrelationship control fields is
1121 described in <ref id="relationships">.
1125 <sect id="virtual_pkg">
1126 <heading>Virtual packages</heading>
1129 Sometimes, there are several packages which offer
1130 more-or-less the same functionality. In this case, it's
1131 useful to define a <em>virtual package</em> whose name
1132 describes that common functionality. (The virtual
1133 packages only exist logically, not physically; that's why
1134 they are called <em>virtual</em>.) The packages with this
1135 particular function will then <em>provide</em> the virtual
1136 package. Thus, any other package requiring that function
1137 can simply depend on the virtual package without having to
1138 specify all possible packages individually.
1142 All packages should use virtual package names where
1143 appropriate, and arrange to create new ones if necessary.
1144 They should not use virtual package names (except privately,
1145 amongst a cooperating group of packages) unless they have
1146 been agreed upon and appear in the list of virtual package
1147 names. (See also <ref id="virtual">)
1151 The latest version of the authoritative list of virtual
1152 package names can be found in the <tt>debian-policy</tt> package.
1153 It is also available from the Debian web mirrors at
1154 <tt><url name="/doc/packaging-manuals/virtual-package-names-list.txt"
1155 id="http://www.debian.org/doc/packaging-manuals/virtual-package-names-list.txt"></tt>.
1159 The procedure for updating the list is described in the preface
1166 <heading>Base system</heading>
1169 The <tt>base system</tt> is a minimum subset of the Debian
1170 system that is installed before everything else
1171 on a new system. Only very few packages are allowed to form
1172 part of the base system, in order to keep the required disk
1177 The base system consists of all those packages with priority
1178 <tt>required</tt> or <tt>important</tt>. Many of them will
1179 be tagged <tt>essential</tt> (see below).
1184 <heading>Essential packages</heading>
1187 Essential is defined as the minimal set of functionality that
1188 must be available and usable on the system at all times, even
1189 when packages are in an unconfigured (but unpacked) state.
1190 Packages are tagged <tt>essential</tt> for a system using the
1191 <tt>Essential</tt> control field. The format of the
1192 <tt>Essential</tt> control field is described in <ref
1197 Since these packages cannot be easily removed (one has to
1198 specify an extra <em>force option</em> to
1199 <prgn>dpkg</prgn> to do so), this flag must not be used
1200 unless absolutely necessary. A shared library package
1201 must not be tagged <tt>essential</tt>; dependencies will
1202 prevent its premature removal, and we need to be able to
1203 remove it when it has been superseded.
1207 Since dpkg will not prevent upgrading of other packages
1208 while an <tt>essential</tt> package is in an unconfigured
1209 state, all <tt>essential</tt> packages must supply all of
1210 their core functionality even when unconfigured. If the
1211 package cannot satisfy this requirement it must not be
1212 tagged as essential, and any packages depending on this
1213 package must instead have explicit dependency fields as
1218 Maintainers should take great care in adding any programs,
1219 interfaces, or functionality to <tt>essential</tt> packages.
1220 Packages may assume that functionality provided by
1221 <tt>essential</tt> packages is always available without
1222 declaring explicit dependencies, which means that removing
1223 functionality from the Essential set is very difficult and is
1224 almost never done. Any capability added to an
1225 <tt>essential</tt> package therefore creates an obligation to
1226 support that capability as part of the Essential set in
1231 You must not tag any packages <tt>essential</tt> before
1232 this has been discussed on the <tt>debian-devel</tt>
1233 mailing list and a consensus about doing that has been
1238 <sect id="maintscripts">
1239 <heading>Maintainer Scripts</heading>
1242 The package installation scripts should avoid producing
1243 output which is unnecessary for the user to see and
1244 should rely on <prgn>dpkg</prgn> to stave off boredom on
1245 the part of a user installing many packages. This means,
1246 amongst other things, using the <tt>--quiet</tt> option on
1247 <prgn>install-info</prgn>.
1251 Errors which occur during the execution of an installation
1252 script must be checked and the installation must not
1253 continue after an error.
1257 Note that in general <ref id="scripts"> applies to package
1258 maintainer scripts, too.
1262 You should not use <prgn>dpkg-divert</prgn> on a file belonging
1263 to another package without consulting the maintainer of that
1264 package first. When adding or removing diversions, package
1265 maintainer scripts must provide the <tt>--package</tt> flag
1266 to <prgn>dpkg-divert</prgn> and must not use <tt>--local</tt>.
1270 All packages which supply an instance of a common command
1271 name (or, in general, filename) should generally use
1272 <prgn>update-alternatives</prgn>, so that they may be
1273 installed together. If <prgn>update-alternatives</prgn>
1274 is not used, then each package must use
1275 <tt>Conflicts</tt> to ensure that other packages are
1276 de-installed. (In this case, it may be appropriate to
1277 specify a conflict against earlier versions of something
1278 that previously did not use
1279 <prgn>update-alternatives</prgn>; this is an exception to
1280 the usual rule that versioned conflicts should be
1284 <sect1 id="maintscriptprompt">
1285 <heading>Prompting in maintainer scripts</heading>
1287 Package maintainer scripts may prompt the user if
1288 necessary. Prompting must be done by communicating
1289 through a program, such as <prgn>debconf</prgn>, which
1290 conforms to the Debian Configuration Management
1291 Specification, version 2 or higher.
1295 Packages which are essential, or which are dependencies of
1296 essential packages, may fall back on another prompting method
1297 if no such interface is available when they are executed.
1301 The Debian Configuration Management Specification is included
1302 in the <file>debconf_specification</file> files in the
1303 <package>debian-policy</package> package.
1304 It is also available from the Debian web mirrors at
1305 <tt><url name="/doc/packaging-manuals/debconf_specification.html"
1306 id="http://www.debian.org/doc/packaging-manuals/debconf_specification.html"></tt>.
1310 Packages which use the Debian Configuration Management
1311 Specification may contain the additional control information
1312 files <file>config</file>
1313 and <file>templates</file>. <file>config</file> is an
1314 additional maintainer script used for package configuration,
1315 and <file>templates</file> contains templates used for user
1316 prompting. The <prgn>config</prgn> script might be run before
1317 the <prgn>preinst</prgn> script and before the package is
1318 unpacked or any of its dependencies or pre-dependencies are
1319 satisfied. Therefore it must work using only the tools
1320 present in <em>essential</em> packages.<footnote>
1321 <package>Debconf</package> or another tool that
1322 implements the Debian Configuration Management
1323 Specification will also be installed, and any
1324 versioned dependencies on it will be satisfied
1325 before preconfiguration begins.
1330 Packages which use the Debian Configuration Management
1331 Specification must allow for translation of their user-visible
1332 messages by using a gettext-based system such as the one
1333 provided by the <package>po-debconf</package> package.
1337 Packages should try to minimize the amount of prompting
1338 they need to do, and they should ensure that the user
1339 will only ever be asked each question once. This means
1340 that packages should try to use appropriate shared
1341 configuration files (such as <file>/etc/papersize</file> and
1342 <file>/etc/news/server</file>), and shared
1343 <package>debconf</package> variables rather than each
1344 prompting for their own list of required pieces of
1349 It also means that an upgrade should not ask the same
1350 questions again, unless the user has used
1351 <tt>dpkg --purge</tt> to remove the package's configuration.
1352 The answers to configuration questions should be stored in an
1353 appropriate place in <file>/etc</file> so that the user can
1354 modify them, and how this has been done should be
1359 If a package has a vitally important piece of
1360 information to pass to the user (such as "don't run me
1361 as I am, you must edit the following configuration files
1362 first or you risk your system emitting badly-formatted
1363 messages"), it should display this in the
1364 <prgn>config</prgn> or <prgn>postinst</prgn> script and
1365 prompt the user to hit return to acknowledge the
1366 message. Copyright messages do not count as vitally
1367 important (they belong in
1368 <file>/usr/share/doc/<var>package</var>/copyright</file>);
1369 neither do instructions on how to use a program (these
1370 should be in on-line documentation, where all the users
1375 Any necessary prompting should almost always be confined
1376 to the <prgn>config</prgn> or <prgn>postinst</prgn>
1377 script. If it is done in the <prgn>postinst</prgn>, it
1378 should be protected with a conditional so that
1379 unnecessary prompting doesn't happen if a package's
1380 installation fails and the <prgn>postinst</prgn> is
1381 called with <tt>abort-upgrade</tt>,
1382 <tt>abort-remove</tt> or <tt>abort-deconfigure</tt>.
1392 <heading>Source packages</heading>
1394 <sect id="standardsversion">
1395 <heading>Standards conformance</heading>
1398 Source packages should specify the most recent version number
1399 of this policy document with which your package complied
1400 when it was last updated.
1404 This information may be used to file bug reports
1405 automatically if your package becomes too much out of date.
1409 The version is specified in the <tt>Standards-Version</tt>
1411 The format of the <tt>Standards-Version</tt> field is
1412 described in <ref id="f-Standards-Version">.
1416 You should regularly, and especially if your package has
1417 become out of date, check for the newest Policy Manual
1418 available and update your package, if necessary. When your
1419 package complies with the new standards you should update the
1420 <tt>Standards-Version</tt> source package field and
1421 release it.<footnote>
1422 See the file <file>upgrading-checklist</file> for
1423 information about policy which has changed between
1424 different versions of this document.
1430 <sect id="pkg-relations">
1431 <heading>Package relationships</heading>
1434 Source packages should specify which binary packages they
1435 require to be installed or not to be installed in order to
1436 build correctly. For example, if building a package
1437 requires a certain compiler, then the compiler should be
1438 specified as a build-time dependency.
1442 It is not necessary to explicitly specify build-time
1443 relationships on a minimal set of packages that are always
1444 needed to compile, link and put in a Debian package a
1445 standard "Hello World!" program written in C or C++. The
1446 required packages are called <em>build-essential</em>, and
1447 an informational list can be found in
1448 <file>/usr/share/doc/build-essential/list</file> (which is
1449 contained in the <tt>build-essential</tt>
1452 <list compact="compact">
1454 This allows maintaining the list separately
1455 from the policy documents (the list does not
1456 need the kind of control that the policy
1460 Having a separate package allows one to install
1461 the build-essential packages on a machine, as
1462 well as allowing other packages such as tasks to
1463 require installation of the build-essential
1464 packages using the depends relation.
1467 The separate package allows bug reports against
1468 the list to be categorized separately from
1469 the policy management process in the BTS.
1476 When specifying the set of build-time dependencies, one
1477 should list only those packages explicitly required by the
1478 build. It is not necessary to list packages which are
1479 required merely because some other package in the list of
1480 build-time dependencies depends on them.<footnote>
1481 The reason for this is that dependencies change, and
1482 you should list all those packages, and <em>only</em>
1483 those packages that <em>you</em> need directly. What
1484 others need is their business. For example, if you
1485 only link against <file>libimlib</file>, you will need to
1486 build-depend on <package>libimlib2-dev</package> but
1487 not against any <tt>libjpeg*</tt> packages, even
1488 though <tt>libimlib2-dev</tt> currently depends on
1489 them: installation of <package>libimlib2-dev</package>
1490 will automatically ensure that all of its run-time
1491 dependencies are satisfied.
1496 If build-time dependencies are specified, it must be
1497 possible to build the package and produce working binaries
1498 on a system with only essential and build-essential
1499 packages installed and also those required to satisfy the
1500 build-time relationships (including any implied
1501 relationships). In particular, this means that version
1502 clauses should be used rigorously in build-time
1503 relationships so that one cannot produce bad or
1504 inconsistently configured packages when the relationships
1505 are properly satisfied.
1509 <ref id="relationships"> explains the technical details.
1514 <heading>Changes to the upstream sources</heading>
1517 If changes to the source code are made that are not
1518 specific to the needs of the Debian system, they should be
1519 sent to the upstream authors in whatever form they prefer
1520 so as to be included in the upstream version of the
1525 If you need to configure the package differently for
1526 Debian or for Linux, and the upstream source doesn't
1527 provide a way to do so, you should add such configuration
1528 facilities (for example, a new <prgn>autoconf</prgn> test
1529 or <tt>#define</tt>) and send the patch to the upstream
1530 authors, with the default set to the way they originally
1531 had it. You can then easily override the default in your
1532 <file>debian/rules</file> or wherever is appropriate.
1536 You should make sure that the <prgn>configure</prgn> utility
1537 detects the correct architecture specification string
1538 (refer to <ref id="arch-spec"> for details).
1542 If you need to edit a <prgn>Makefile</prgn> where GNU-style
1543 <prgn>configure</prgn> scripts are used, you should edit the
1544 <file>.in</file> files rather than editing the
1545 <prgn>Makefile</prgn> directly. This allows the user to
1546 reconfigure the package if necessary. You should
1547 <em>not</em> configure the package and edit the generated
1548 <prgn>Makefile</prgn>! This makes it impossible for someone
1549 else to later reconfigure the package without losing the
1555 <sect id="dpkgchangelog">
1556 <heading>Debian changelog: <file>debian/changelog</file></heading>
1559 Changes in the Debian version of the package should be
1560 briefly explained in the Debian changelog file
1561 <file>debian/changelog</file>.<footnote>
1563 Mistakes in changelogs are usually best rectified by
1564 making a new changelog entry rather than "rewriting
1565 history" by editing old changelog entries.
1568 This includes modifications
1569 made in the Debian package compared to the upstream one
1570 as well as other changes and updates to the package.
1572 Although there is nothing stopping an author who is also
1573 the Debian maintainer from using this changelog for all
1574 their changes, it will have to be renamed if the Debian
1575 and upstream maintainers become different people. In such
1576 a case, however, it might be better to maintain the package
1577 as a non-native package.
1582 The format of the <file>debian/changelog</file> allows the
1583 package building tools to discover which version of the package
1584 is being built and find out other release-specific information.
1588 That format is a series of entries like this:
1590 <example compact="compact">
1591 <var>package</var> (<var>version</var>) <var>distribution(s)</var>; urgency=<var>urgency</var>
1593 [optional blank line(s), stripped]
1595 * <var>change details</var>
1596 <var>more change details</var>
1598 [blank line(s), included in output of dpkg-parsechangelog]
1600 * <var>even more change details</var>
1602 [optional blank line(s), stripped]
1604 -- <var>maintainer name</var> <<var>email address</var>><var>[two spaces]</var> <var>date</var>
1609 <var>package</var> and <var>version</var> are the source
1610 package name and version number.
1614 <var>distribution(s)</var> lists the distributions where
1615 this version should be installed when it is uploaded - it
1616 is copied to the <tt>Distribution</tt> field in the
1617 <file>.changes</file> file. See <ref id="f-Distribution">.
1621 <var>urgency</var> is the value for the <tt>Urgency</tt>
1622 field in the <file>.changes</file> file for the upload
1623 (see <ref id="f-Urgency">). It is not possible to specify
1624 an urgency containing commas; commas are used to separate
1625 <tt><var>keyword</var>=<var>value</var></tt> settings in the
1626 <prgn>dpkg</prgn> changelog format (though there is
1627 currently only one useful <var>keyword</var>,
1632 The change details may in fact be any series of lines
1633 starting with at least two spaces, but conventionally each
1634 change starts with an asterisk and a separating space and
1635 continuation lines are indented so as to bring them in
1636 line with the start of the text above. Blank lines may be
1637 used here to separate groups of changes, if desired.
1641 If this upload resolves bugs recorded in the Bug Tracking
1642 System (BTS), they may be automatically closed on the
1643 inclusion of this package into the Debian archive by
1644 including the string: <tt>closes: Bug#<var>nnnnn</var></tt>
1645 in the change details.<footnote>
1646 To be precise, the string should match the following
1647 Perl regular expression:
1649 /closes:\s*(?:bug)?\#?\s?\d+(?:,\s*(?:bug)?\#?\s?\d+)*/i
1651 Then all of the bug numbers listed will be closed by the
1652 archive maintenance script (<prgn>katie</prgn>) using the
1653 <var>version</var> of the changelog entry.
1655 This information is conveyed via the <tt>Closes</tt> field
1656 in the <tt>.changes</tt> file (see <ref id="f-Closes">).
1660 The maintainer name and email address used in the changelog
1661 should be the details of the person uploading <em>this</em>
1662 version. They are <em>not</em> necessarily those of the
1663 usual package maintainer.<footnote>
1664 If the developer uploading the package is not one of the usual
1665 maintainers of the package (as listed in
1666 the <qref id="f-Maintainer"><tt>Maintainer</tt></qref>
1667 or <qref id="f-Uploaders"><tt>Uploaders</tt></qref> control
1668 fields of the package), the first line of the changelog is
1669 conventionally used to explain why a non-maintainer is
1670 uploading the package. The Debian Developer's Reference
1671 (see <ref id="related">) documents the conventions
1673 The information here will be copied to the <tt>Changed-By</tt>
1674 field in the <tt>.changes</tt> file
1675 (see <ref id="f-Changed-By">), and then later used to send an
1676 acknowledgement when the upload has been installed.
1680 The <var>date</var> has the following format<footnote>
1681 This is the same as the format generated by <tt>date
1683 </footnote> (compatible and with the same semantics of
1684 RFC 2822 and RFC 5322):
1685 <example>day-of-week, dd month yyyy hh:mm:ss +zzzz</example>
1687 <list compact="compact">
1689 day-of week is one of: Mon, Tue, Wed, Thu, Fri, Sat, Sun
1692 dd is a one- or two-digit day of the month (01-31)
1695 month is one of: Jan, Feb, Mar, Apr, May, Jun, Jul, Aug,
1698 <item>yyyy is the four-digit year (e.g. 2010)</item>
1699 <item>hh is the two-digit hour (00-23)</item>
1700 <item>mm is the two-digit minutes (00-59)</item>
1701 <item>ss is the two-digit seconds (00-60)</item>
1703 +zzzz or -zzzz is the the time zone offset from Coordinated
1704 Universal Time (UTC). "+" indicates that the time is ahead
1705 of (i.e., east of) UTC and "-" indicates that the time is
1706 behind (i.e., west of) UTC. The first two digits indicate
1707 the hour difference from UTC and the last two digits
1708 indicate the number of additional minutes difference from
1709 UTC. The last two digits must be in the range 00-59.
1715 The first "title" line with the package name must start
1716 at the left hand margin. The "trailer" line with the
1717 maintainer and date details must be preceded by exactly
1718 one space. The maintainer details and the date must be
1719 separated by exactly two spaces.
1723 The entire changelog must be encoded in UTF-8.
1727 For more information on placement of the changelog files
1728 within binary packages, please see <ref id="changelogs">.
1732 <sect id="dpkgcopyright">
1733 <heading>Copyright: <file>debian/copyright</file></heading>
1735 Every package must be accompanied by a verbatim copy of its
1736 copyright information and distribution license in the file
1737 <file>/usr/share/doc/<var>package</var>/copyright</file>
1738 (see <ref id="copyrightfile"> for further details). Also see
1739 <ref id="pkgcopyright"> for further considerations related
1740 to copyrights for packages.
1744 <heading>Error trapping in makefiles</heading>
1747 When <prgn>make</prgn> invokes a command in a makefile
1748 (including your package's upstream makefiles and
1749 <file>debian/rules</file>), it does so using <prgn>sh</prgn>. This
1750 means that <prgn>sh</prgn>'s usual bad error handling
1751 properties apply: if you include a miniature script as one
1752 of the commands in your makefile you'll find that if you
1753 don't do anything about it then errors are not detected
1754 and <prgn>make</prgn> will blithely continue after
1759 Every time you put more than one shell command (this
1760 includes using a loop) in a makefile command you
1761 must make sure that errors are trapped. For
1762 simple compound commands, such as changing directory and
1763 then running a program, using <tt>&&</tt> rather
1764 than semicolon as a command separator is sufficient. For
1765 more complex commands including most loops and
1766 conditionals you should include a separate <tt>set -e</tt>
1767 command at the start of every makefile command that's
1768 actually one of these miniature shell scripts.
1772 <sect id="timestamps">
1773 <heading>Time Stamps</heading>
1775 Maintainers should preserve the modification times of the
1776 upstream source files in a package, as far as is reasonably
1778 The rationale is that there is some information conveyed
1779 by knowing the age of the file, for example, you could
1780 recognize that some documentation is very old by looking
1781 at the modification time, so it would be nice if the
1782 modification time of the upstream source would be
1788 <sect id="restrictions">
1789 <heading>Restrictions on objects in source packages</heading>
1792 The source package may not contain any hard links<footnote>
1794 This is not currently detected when building source
1795 packages, but only when extracting
1799 Hard links may be permitted at some point in the
1800 future, but would require a fair amount of
1803 </footnote>, device special files, sockets or setuid or
1804 setgid files.<footnote>
1805 Setgid directories are allowed.
1810 <sect id="debianrules">
1811 <heading>Main building script: <file>debian/rules</file></heading>
1814 This file must be an executable makefile, and contains the
1815 package-specific recipes for compiling the package and
1816 building binary package(s) from the source.
1820 It must start with the line <tt>#!/usr/bin/make -f</tt>,
1821 so that it can be invoked by saying its name rather than
1822 invoking <prgn>make</prgn> explicitly. That is, invoking
1823 either of <tt>make -f debian/rules <em>args...</em></tt>
1824 or <tt>./debian/rules <em>args...</em></tt> must result in
1829 The following targets are required and must be implemented
1830 by <file>debian/rules</file>: <tt>clean</tt>, <tt>binary</tt>,
1831 <tt>binary-arch</tt>, <tt>binary-indep</tt>, and <tt>build</tt>.
1832 These are the targets called by <prgn>dpkg-buildpackage</prgn>.
1836 Since an interactive <file>debian/rules</file> script makes it
1837 impossible to auto-compile that package and also makes it hard
1838 for other people to reproduce the same binary package, all
1839 required targets must be non-interactive. It also follows that
1840 any target that these targets depend on must also be
1845 The targets are as follows:
1847 <tag><tt>build</tt> (required)</tag>
1850 The <tt>build</tt> target should perform all the
1851 configuration and compilation of the package.
1852 If a package has an interactive pre-build
1853 configuration routine, the Debian source package
1854 must either be built after this has taken place (so
1855 that the binary package can be built without rerunning
1856 the configuration) or the configuration routine
1857 modified to become non-interactive. (The latter is
1858 preferable if there are architecture-specific features
1859 detected by the configuration routine.)
1863 For some packages, notably ones where the same
1864 source tree is compiled in different ways to produce
1865 two binary packages, the <tt>build</tt> target
1866 does not make much sense. For these packages it is
1867 good enough to provide two (or more) targets
1868 (<tt>build-a</tt> and <tt>build-b</tt> or whatever)
1869 for each of the ways of building the package, and a
1870 <tt>build</tt> target that does nothing. The
1871 <tt>binary</tt> target will have to build the
1872 package in each of the possible ways and make the
1873 binary package out of each.
1877 The <tt>build</tt> target must not do anything
1878 that might require root privilege.
1882 The <tt>build</tt> target may need to run the
1883 <tt>clean</tt> target first - see below.
1887 When a package has a configuration and build routine
1888 which takes a long time, or when the makefiles are
1889 poorly designed, or when <tt>build</tt> needs to
1890 run <tt>clean</tt> first, it is a good idea to
1891 <tt>touch build</tt> when the build process is
1892 complete. This will ensure that if <tt>debian/rules
1893 build</tt> is run again it will not rebuild the whole
1895 Another common way to do this is for <tt>build</tt>
1896 to depend on <prgn>build-stamp</prgn> and to do
1897 nothing else, and for the <prgn>build-stamp</prgn>
1898 target to do the building and to <tt>touch
1899 build-stamp</tt> on completion. This is
1900 especially useful if the build routine creates a
1901 file or directory called <tt>build</tt>; in such a
1902 case, <tt>build</tt> will need to be listed as
1903 a phony target (i.e., as a dependency of the
1904 <tt>.PHONY</tt> target). See the documentation of
1905 <prgn>make</prgn> for more information on phony
1911 <tag><tt>build-arch</tt> (optional),
1912 <tt>build-indep</tt> (optional)
1916 A package may also provide both of the targets
1917 <tt>build-arch</tt> and <tt>build-indep</tt>.
1918 The <tt>build-arch</tt> target, if provided, should
1919 perform all the configuration and compilation required for
1920 producing all architecture-dependant binary packages
1921 (those packages for which the body of the
1922 <tt>Architecture</tt> field in <tt>debian/control</tt> is
1923 not <tt>all</tt>). Similarly, the <tt>build-indep</tt>
1924 target, if provided, should perform all the configuration
1925 and compilation required for producing all
1926 architecture-independent binary packages (those packages
1927 for which the body of the <tt>Architecture</tt> field
1928 in <tt>debian/control</tt> is <tt>all</tt>).
1929 The <tt>build</tt> target should depend on those of the
1930 targets <tt>build-arch</tt> and <tt>build-indep</tt> that
1931 are provided in the rules file.<footnote>
1932 The intent of this split is so that binary-only builds
1933 need not install the dependencies required for
1934 the <tt>build-indep</tt> target. However, this is not
1935 yet used in practice since <tt>dpkg-buildpackage
1936 -B</tt>, and therefore the autobuilders,
1937 invoke <tt>build</tt> rather than <tt>build-arch</tt>
1938 due to the difficulties in determining whether the
1939 optional <tt>build-arch</tt> target exists.
1944 If one or both of the targets <tt>build-arch</tt> and
1945 <tt>build-indep</tt> are not provided, then invoking
1946 <file>debian/rules</file> with one of the not-provided
1947 targets as arguments should produce a exit status code
1948 of 2. Usually this is provided automatically by make
1949 if the target is missing.
1953 The <tt>build-arch</tt> and <tt>build-indep</tt> targets
1954 must not do anything that might require root privilege.
1958 <tag><tt>binary</tt> (required), <tt>binary-arch</tt>
1959 (required), <tt>binary-indep</tt> (required)
1963 The <tt>binary</tt> target must be all that is
1964 necessary for the user to build the binary package(s)
1965 produced from this source package. It is
1966 split into two parts: <prgn>binary-arch</prgn> builds
1967 the binary packages which are specific to a particular
1968 architecture, and <tt>binary-indep</tt> builds
1969 those which are not.
1972 <tt>binary</tt> may be (and commonly is) a target with
1973 no commands which simply depends on
1974 <tt>binary-arch</tt> and <tt>binary-indep</tt>.
1977 Both <tt>binary-*</tt> targets should depend on the
1978 <tt>build</tt> target, or on the appropriate
1979 <tt>build-arch</tt> or <tt>build-indep</tt> target, if
1980 provided, so that the package is built if it has not
1981 been already. It should then create the relevant
1982 binary package(s), using <prgn>dpkg-gencontrol</prgn> to
1983 make their control files and <prgn>dpkg-deb</prgn> to
1984 build them and place them in the parent of the top
1989 Both the <tt>binary-arch</tt> and
1990 <tt>binary-indep</tt> targets <em>must</em> exist.
1991 If one of them has nothing to do (which will always be
1992 the case if the source generates only a single binary
1993 package, whether architecture-dependent or not), it
1994 must still exist and must always succeed.
1998 The <tt>binary</tt> targets must be invoked as
2000 The <prgn>fakeroot</prgn> package often allows one
2001 to build a package correctly even without being
2007 <tag><tt>clean</tt> (required)</tag>
2010 This must undo any effects that the <tt>build</tt>
2011 and <tt>binary</tt> targets may have had, except
2012 that it should leave alone any output files created in
2013 the parent directory by a run of a <tt>binary</tt>
2018 If a <tt>build</tt> file is touched at the end of
2019 the <tt>build</tt> target, as suggested above, it
2020 should be removed as the first action that
2021 <tt>clean</tt> performs, so that running
2022 <tt>build</tt> again after an interrupted
2023 <tt>clean</tt> doesn't think that everything is
2028 The <tt>clean</tt> target may need to be
2029 invoked as root if <tt>binary</tt> has been
2030 invoked since the last <tt>clean</tt>, or if
2031 <tt>build</tt> has been invoked as root (since
2032 <tt>build</tt> may create directories, for
2037 <tag><tt>get-orig-source</tt> (optional)</tag>
2040 This target fetches the most recent version of the
2041 original source package from a canonical archive site
2042 (via FTP or WWW, for example), does any necessary
2043 rearrangement to turn it into the original source
2044 tar file format described below, and leaves it in the
2049 This target may be invoked in any directory, and
2050 should take care to clean up any temporary files it
2055 This target is optional, but providing it if
2056 possible is a good idea.
2060 <tag><tt>patch</tt> (optional)</tag>
2063 This target performs whatever additional actions are
2064 required to make the source ready for editing (unpacking
2065 additional upstream archives, applying patches, etc.).
2066 It is recommended to be implemented for any package where
2067 <tt>dpkg-source -x</tt> does not result in source ready
2068 for additional modification. See
2069 <ref id="readmesource">.
2075 The <tt>build</tt>, <tt>binary</tt> and
2076 <tt>clean</tt> targets must be invoked with the current
2077 directory being the package's top-level directory.
2082 Additional targets may exist in <file>debian/rules</file>,
2083 either as published or undocumented interfaces or for the
2084 package's internal use.
2088 The architectures we build on and build for are determined
2089 by <prgn>make</prgn> variables using the
2090 utility <qref id="pkg-dpkg-architecture"><prgn>dpkg-architecture</prgn></qref>.
2091 You can determine the Debian architecture and the GNU style
2092 architecture specification string for the build architecture as
2093 well as for the host architecture. The build architecture is
2094 the architecture on which <file>debian/rules</file> is run and
2095 the package build is performed. The host architecture is the
2096 architecture on which the resulting package will be installed
2097 and run. These are normally the same, but may be different in
2098 the case of cross-compilation (building packages for one
2099 architecture on machines of a different architecture).
2103 Here is a list of supported <prgn>make</prgn> variables:
2104 <list compact="compact">
2106 <tt>DEB_*_ARCH</tt> (the Debian architecture)
2109 <tt>DEB_*_ARCH_CPU</tt> (the Debian CPU name)
2112 <tt>DEB_*_ARCH_OS</tt> (the Debian System name)
2115 <tt>DEB_*_GNU_TYPE</tt> (the GNU style architecture
2116 specification string)
2119 <tt>DEB_*_GNU_CPU</tt> (the CPU part of
2120 <tt>DEB_*_GNU_TYPE</tt>)
2123 <tt>DEB_*_GNU_SYSTEM</tt> (the System part of
2124 <tt>DEB_*_GNU_TYPE</tt>)
2126 where <tt>*</tt> is either <tt>BUILD</tt> for specification of
2127 the build architecture or <tt>HOST</tt> for specification of the
2132 Backward compatibility can be provided in the rules file
2133 by setting the needed variables to suitable default
2134 values; please refer to the documentation of
2135 <prgn>dpkg-architecture</prgn> for details.
2139 It is important to understand that the <tt>DEB_*_ARCH</tt>
2140 string only determines which Debian architecture we are
2141 building on or for. It should not be used to get the CPU
2142 or system information; the <tt>DEB_*_ARCH_CPU</tt> and
2143 <tt>DEB_*_ARCH_OS</tt> variables should be used for that.
2144 GNU style variables should generally only be used with upstream
2148 <sect1 id="debianrules-options">
2149 <heading><file>debian/rules</file> and
2150 <tt>DEB_BUILD_OPTIONS</tt></heading>
2153 Supporting the standardized environment variable
2154 <tt>DEB_BUILD_OPTIONS</tt> is recommended. This variable can
2155 contain several flags to change how a package is compiled and
2156 built. Each flag must be in the form <var>flag</var> or
2157 <var>flag</var>=<var>options</var>. If multiple flags are
2158 given, they must be separated by whitespace.<footnote>
2159 Some packages support any delimiter, but whitespace is the
2160 easiest to parse inside a makefile and avoids ambiguity with
2161 flag values that contain commas.
2163 <var>flag</var> must start with a lowercase letter
2164 (<tt>a-z</tt>) and consist only of lowercase letters,
2165 numbers (<tt>0-9</tt>), and the characters
2166 <tt>-</tt> and <tt>_</tt> (hyphen and underscore).
2167 <var>options</var> must not contain whitespace. The same
2168 tag should not be given multiple times with conflicting
2169 values. Package maintainers may assume that
2170 <tt>DEB_BUILD_OPTIONS</tt> will not contain conflicting tags.
2174 The meaning of the following tags has been standardized:
2178 This tag says to not run any build-time test suite
2179 provided by the package.
2183 The presence of this tag means that the package should
2184 be compiled with a minimum of optimization. For C
2185 programs, it is best to add <tt>-O0</tt> to
2186 <tt>CFLAGS</tt> (although this is usually the default).
2187 Some programs might fail to build or run at this level
2188 of optimization; it may be necessary to use
2189 <tt>-O1</tt>, for example.
2193 This tag means that the debugging symbols should not be
2194 stripped from the binary during installation, so that
2195 debugging information may be included in the package.
2197 <tag>parallel=n</tag>
2199 This tag means that the package should be built using up
2200 to <tt>n</tt> parallel processes if the package build
2201 system supports this.<footnote>
2202 Packages built with <tt>make</tt> can often implement
2203 this by passing the <tt>-j</tt><var>n</var> option to
2206 If the package build system does not support parallel
2207 builds, this string must be ignored. If the package
2208 build system only supports a lower level of concurrency
2209 than <var>n</var>, the package should be built using as
2210 many parallel processes as the package build system
2211 supports. It is up to the package maintainer to decide
2212 whether the package build times are long enough and the
2213 package build system is robust enough to make supporting
2214 parallel builds worthwhile.
2220 Unknown flags must be ignored by <file>debian/rules</file>.
2224 The following makefile snippet is an example of how one may
2225 implement the build options; you will probably have to
2226 massage this example in order to make it work for your
2228 <example compact="compact">
2231 INSTALL_FILE = $(INSTALL) -p -o root -g root -m 644
2232 INSTALL_PROGRAM = $(INSTALL) -p -o root -g root -m 755
2233 INSTALL_SCRIPT = $(INSTALL) -p -o root -g root -m 755
2234 INSTALL_DIR = $(INSTALL) -p -d -o root -g root -m 755
2236 ifneq (,$(filter noopt,$(DEB_BUILD_OPTIONS)))
2241 ifeq (,$(filter nostrip,$(DEB_BUILD_OPTIONS)))
2242 INSTALL_PROGRAM += -s
2244 ifneq (,$(filter parallel=%,$(DEB_BUILD_OPTIONS)))
2245 NUMJOBS = $(patsubst parallel=%,%,$(filter parallel=%,$(DEB_BUILD_OPTIONS)))
2246 MAKEFLAGS += -j$(NUMJOBS)
2251 ifeq (,$(filter nocheck,$(DEB_BUILD_OPTIONS)))
2252 # Code to run the package test suite.
2259 <!-- FIXME: section pkg-srcsubstvars is the same as substvars -->
2260 <sect id="substvars">
2261 <heading>Variable substitutions: <file>debian/substvars</file></heading>
2264 When <prgn>dpkg-gencontrol</prgn>
2265 generates <qref id="binarycontrolfiles">binary package control
2266 files</qref> (<file>DEBIAN/control</file>), it performs variable
2267 substitutions on its output just before writing it. Variable
2268 substitutions have the form <tt>${<var>variable</var>}</tt>.
2269 The optional file <file>debian/substvars</file> contains
2270 variable substitutions to be used; variables can also be set
2271 directly from <file>debian/rules</file> using the <tt>-V</tt>
2272 option to the source packaging commands, and certain predefined
2273 variables are also available.
2277 The <file>debian/substvars</file> file is usually generated and
2278 modified dynamically by <file>debian/rules</file> targets, in
2279 which case it must be removed by the <tt>clean</tt> target.
2283 See <manref name="deb-substvars" section="5"> for full
2284 details about source variable substitutions, including the
2285 format of <file>debian/substvars</file>.</p>
2288 <sect id="debianwatch">
2289 <heading>Optional upstream source location: <file>debian/watch</file></heading>
2292 This is an optional, recommended configuration file for the
2293 <tt>uscan</tt> utility which defines how to automatically scan
2294 ftp or http sites for newly available updates of the
2295 package. This is used
2296 by <url id="http://dehs.alioth.debian.org/"> and other Debian QA
2297 tools to help with quality control and maintenance of the
2298 distribution as a whole.
2303 <sect id="debianfiles">
2304 <heading>Generated files list: <file>debian/files</file></heading>
2307 This file is not a permanent part of the source tree; it
2308 is used while building packages to record which files are
2309 being generated. <prgn>dpkg-genchanges</prgn> uses it
2310 when it generates a <file>.changes</file> file.
2314 It should not exist in a shipped source package, and so it
2315 (and any backup files or temporary files such as
2316 <file>files.new</file><footnote>
2317 <file>files.new</file> is used as a temporary file by
2318 <prgn>dpkg-gencontrol</prgn> and
2319 <prgn>dpkg-distaddfile</prgn> - they write a new
2320 version of <tt>files</tt> here before renaming it,
2321 to avoid leaving a corrupted copy if an error
2323 </footnote>) should be removed by the
2324 <tt>clean</tt> target. It may also be wise to
2325 ensure a fresh start by emptying or removing it at the
2326 start of the <tt>binary</tt> target.
2330 When <prgn>dpkg-gencontrol</prgn> is run for a binary
2331 package, it adds an entry to <file>debian/files</file> for the
2332 <file>.deb</file> file that will be created when <tt>dpkg-deb
2333 --build</tt> is run for that binary package. So for most
2334 packages all that needs to be done with this file is to
2335 delete it in the <tt>clean</tt> target.
2339 If a package upload includes files besides the source
2340 package and any binary packages whose control files were
2341 made with <prgn>dpkg-gencontrol</prgn> then they should be
2342 placed in the parent of the package's top-level directory
2343 and <prgn>dpkg-distaddfile</prgn> should be called to add
2344 the file to the list in <file>debian/files</file>.</p>
2347 <sect id="embeddedfiles">
2348 <heading>Convenience copies of code</heading>
2351 Some software packages include in their distribution convenience
2352 copies of code from other software packages, generally so that
2353 users compiling from source don't have to download multiple
2354 packages. Debian packages should not make use of these
2355 convenience copies unless the included package is explicitly
2356 intended to be used in this way.<footnote>
2357 For example, parts of the GNU build system work like this.
2359 If the included code is already in the Debian archive in the
2360 form of a library, the Debian packaging should ensure that
2361 binary packages reference the libraries already in Debian and
2362 the convenience copy is not used. If the included code is not
2363 already in Debian, it should be packaged separately as a
2364 prerequisite if possible.
2366 Having multiple copies of the same code in Debian is
2367 inefficient, often creates either static linking or shared
2368 library conflicts, and, most importantly, increases the
2369 difficulty of handling security vulnerabilities in the
2375 <sect id="readmesource">
2376 <heading>Source package handling:
2377 <file>debian/README.source</file></heading>
2380 If running <prgn>dpkg-source -x</prgn> on a source package
2381 doesn't produce the source of the package, ready for editing,
2382 and allow one to make changes and run
2383 <prgn>dpkg-buildpackage</prgn> to produce a modified package
2384 without taking any additional steps, creating a
2385 <file>debian/README.source</file> documentation file is
2386 recommended. This file should explain how to do all of the
2389 <item>Generate the fully patched source, in a form ready for
2390 editing, that would be built to create Debian
2391 packages. Doing this with a <tt>patch</tt> target in
2392 <file>debian/rules</file> is recommended; see
2393 <ref id="debianrules">.</item>
2394 <item>Modify the source and save those modifications so that
2395 they will be applied when building the package.</item>
2396 <item>Remove source modifications that are currently being
2397 applied when building the package.</item>
2398 <item>Optionally, document what steps are necessary to
2399 upgrade the Debian source package to a new upstream version,
2400 if applicable.</item>
2402 This explanation should include specific commands and mention
2403 any additional required Debian packages. It should not assume
2404 familiarity with any specific Debian packaging system or patch
2409 This explanation may refer to a documentation file installed by
2410 one of the package's build dependencies provided that the
2411 referenced documentation clearly explains these tasks and is not
2412 a general reference manual.
2416 <file>debian/README.source</file> may also include any other
2417 information that would be helpful to someone modifying the
2418 source package. Even if the package doesn't fit the above
2419 description, maintainers are encouraged to document in a
2420 <file>debian/README.source</file> file any source package with a
2421 particularly complex or unintuitive source layout or build
2422 system (for example, a package that builds the same source
2423 multiple times to generate different binary packages).
2429 <chapt id="controlfields">
2430 <heading>Control files and their fields</heading>
2433 The package management system manipulates data represented in
2434 a common format, known as <em>control data</em>, stored in
2435 <em>control files</em>.
2436 Control files are used for source packages, binary packages and
2437 the <file>.changes</file> files which control the installation
2438 of uploaded files<footnote>
2439 <prgn>dpkg</prgn>'s internal databases are in a similar
2444 <sect id="controlsyntax">
2445 <heading>Syntax of control files</heading>
2448 A control file consists of one or more paragraphs of
2450 The paragraphs are also sometimes referred to as stanzas.
2452 The paragraphs are separated by blank lines. Some control
2453 files allow only one paragraph; others allow several, in
2454 which case each paragraph usually refers to a different
2455 package. (For example, in source packages, the first
2456 paragraph refers to the source package, and later paragraphs
2457 refer to binary packages generated from the source.)
2461 Each paragraph consists of a series of data fields; each
2462 field consists of the field name, followed by a colon and
2463 then the data/value associated with that field. It ends at
2464 the end of the (logical) line. Horizontal whitespace
2465 (spaces and tabs) may occur immediately before or after the
2466 value and is ignored there; it is conventional to put a
2467 single space after the colon. For example, a field might
2469 <example compact="compact">
2472 the field name is <tt>Package</tt> and the field value
2477 A paragraph must not contain more than one instance of a
2478 particular field name.
2482 Many fields' values may span several lines; in this case
2483 each continuation line must start with a space or a tab.
2484 Any trailing spaces or tabs at the end of individual
2485 lines of a field value are ignored.
2489 In fields where it is specified that lines may not wrap,
2490 only a single line of data is allowed and whitespace is not
2491 significant in a field body. Whitespace must not appear
2492 inside names (of packages, architectures, files or anything
2493 else) or version numbers, or between the characters of
2494 multi-character version relationships.
2498 Field names are not case-sensitive, but it is usual to
2499 capitalize the field names using mixed case as shown below.
2500 Field values are case-sensitive unless the description of the
2501 field says otherwise.
2505 Blank lines, or lines consisting only of spaces and tabs,
2506 are not allowed within field values or between fields - that
2507 would mean a new paragraph.
2511 All control files must be encoded in UTF-8.
2515 <sect id="sourcecontrolfiles">
2516 <heading>Source package control files -- <file>debian/control</file></heading>
2519 The <file>debian/control</file> file contains the most vital
2520 (and version-independent) information about the source package
2521 and about the binary packages it creates.
2525 The first paragraph of the control file contains information about
2526 the source package in general. The subsequent sets each describe a
2527 binary package that the source tree builds.
2531 The fields in the general paragraph (the first one, for the source
2534 <list compact="compact">
2535 <item><qref id="f-Source"><tt>Source</tt></qref> (mandatory)</item>
2536 <item><qref id="f-Maintainer"><tt>Maintainer</tt></qref> (mandatory)</item>
2537 <item><qref id="f-Uploaders"><tt>Uploaders</tt></qref></item>
2538 <item><qref id="f-DM-Upload-Allowed"<tt>DM-Upload-Allowed</tt></qref></item>
2539 <item><qref id="f-Section"><tt>Section</tt></qref> (recommended)</item>
2540 <item><qref id="f-Priority"><tt>Priority</tt></qref> (recommended)</item>
2541 <item><qref id="sourcebinarydeps"><tt>Build-Depends</tt> et al</qref></item>
2542 <item><qref id="f-Standards-Version"><tt>Standards-Version</tt></qref> (recommended)</item>
2543 <item><qref id="f-Homepage"><tt>Homepage</tt></qref></item>
2548 The fields in the binary package paragraphs are:
2550 <list compact="compact">
2551 <item><qref id="f-Package"><tt>Package</tt></qref> (mandatory)</item>
2552 <item><qref id="f-Architecture"><tt>Architecture</tt></qref> (mandatory)</item>
2553 <item><qref id="f-Section"><tt>Section</tt></qref> (recommended)</item>
2554 <item><qref id="f-Priority"><tt>Priority</tt></qref> (recommended)</item>
2555 <item><qref id="f-Essential"><tt>Essential</tt></qref></item>
2556 <item><qref id="binarydeps"><tt>Depends</tt> et al</qref></item>
2557 <item><qref id="f-Description"><tt>Description</tt></qref> (mandatory)</item>
2558 <item><qref id="f-Homepage"><tt>Homepage</tt></qref></item>
2563 The syntax and semantics of the fields are described below.
2567 These fields are used by <prgn>dpkg-gencontrol</prgn> to
2568 generate control files for binary packages (see below), by
2569 <prgn>dpkg-genchanges</prgn> to generate the
2570 <file>.changes</file> file to accompany the upload, and by
2571 <prgn>dpkg-source</prgn> when it creates the
2572 <file>.dsc</file> source control file as part of a source
2573 archive. Many fields are permitted to span multiple lines in
2574 <file>debian/control</file> but not in any other control
2575 file. These tools are responsible for removing the line
2576 breaks from such fields when using fields from
2577 <file>debian/control</file> to generate other control files.
2581 The fields here may contain variable references - their
2582 values will be substituted by <prgn>dpkg-gencontrol</prgn>,
2583 <prgn>dpkg-genchanges</prgn> or <prgn>dpkg-source</prgn>
2584 when they generate output control files.
2585 See <ref id="substvars"> for details.
2589 In addition to the control file syntax described <qref
2590 id="controlsyntax">above</qref>, this file may also contain
2591 comment lines starting with <tt>#</tt> without any preceding
2592 whitespace. All such lines are ignored, even in the middle of
2593 continuation lines for a multiline field, and do not end a
2599 <sect id="binarycontrolfiles">
2600 <heading>Binary package control files -- <file>DEBIAN/control</file></heading>
2603 The <file>DEBIAN/control</file> file contains the most vital
2604 (and version-dependent) information about a binary package. It
2605 consists of a single paragraph.
2609 The fields in this file are:
2611 <list compact="compact">
2612 <item><qref id="f-Package"><tt>Package</tt></qref> (mandatory)</item>
2613 <item><qref id="f-Source"><tt>Source</tt></qref></item>
2614 <item><qref id="f-Version"><tt>Version</tt></qref> (mandatory)</item>
2615 <item><qref id="f-Section"><tt>Section</tt></qref> (recommended)</item>
2616 <item><qref id="f-Priority"><tt>Priority</tt></qref> (recommended)</item>
2617 <item><qref id="f-Architecture"><tt>Architecture</tt></qref> (mandatory)</item>
2618 <item><qref id="f-Essential"><tt>Essential</tt></qref></item>
2619 <item><qref id="binarydeps"><tt>Depends</tt> et al</qref></item>
2620 <item><qref id="f-Installed-Size"><tt>Installed-Size</tt></qref></item>
2621 <item><qref id="f-Maintainer"><tt>Maintainer</tt></qref> (mandatory)</item>
2622 <item><qref id="f-Description"><tt>Description</tt></qref> (mandatory)</item>
2623 <item><qref id="f-Homepage"><tt>Homepage</tt></qref></item>
2628 <sect id="debiansourcecontrolfiles">
2629 <heading>Debian source control files -- <tt>.dsc</tt></heading>
2632 This file consists of a single paragraph, possibly surrounded by
2633 a PGP signature. The fields of that paragraph are listed below.
2634 Their syntax is described above, in <ref id="pkg-controlfields">.
2636 <list compact="compact">
2637 <item><qref id="f-Format"><tt>Format</tt></qref> (mandatory)</item>
2638 <item><qref id="f-Source"><tt>Source</tt></qref> (mandatory)</item>
2639 <item><qref id="f-Binary"><tt>Binary</tt></qref></item>
2640 <item><qref id="f-Architecture"><tt>Architecture</tt></qref></item>
2641 <item><qref id="f-Version"><tt>Version</tt></qref> (mandatory)</item>
2642 <item><qref id="f-Maintainer"><tt>Maintainer</tt></qref> (mandatory)</item>
2643 <item><qref id="f-Uploaders"><tt>Uploaders</tt></qref></item>
2644 <item><qref id="f-DM-Upload-Allowed"<tt>DM-Upload-Allowed</tt></qref></item>
2645 <item><qref id="f-Homepage"><tt>Homepage</tt></qref></item>
2646 <item><qref id="f-Standards-Version"><tt>Standards-Version</tt></qref> (recommended)</item>
2647 <item><qref id="sourcebinarydeps"><tt>Build-Depends</tt> et al</qref></item>
2648 <item><qref id="f-Checksums"><tt>Checksums-Sha1</tt>
2649 and <tt>Checksums-Sha256</tt></qref> (recommended)</item>
2650 <item><qref id="f-Files"><tt>Files</tt></qref> (mandatory)</item>
2655 The source package control file is generated by
2656 <prgn>dpkg-source</prgn> when it builds the source
2657 archive, from other files in the source package,
2658 described above. When unpacking, it is checked against
2659 the files and directories in the other parts of the
2665 <sect id="debianchangesfiles">
2666 <heading>Debian changes files -- <file>.changes</file></heading>
2669 The <file>.changes</file> files are used by the Debian archive
2670 maintenance software to process updates to packages. They
2671 consist of a single paragraph, possibly surrounded by a PGP
2672 signature. That paragraph contains information from the
2673 <file>debian/control</file> file and other data about the
2674 source package gathered via <file>debian/changelog</file>
2675 and <file>debian/rules</file>.
2679 <file>.changes</file> files have a format version that is
2680 incremented whenever the documented fields or their meaning
2681 change. This document describes format &changesversion;.
2685 The fields in this file are:
2687 <list compact="compact">
2688 <item><qref id="f-Format"><tt>Format</tt></qref> (mandatory)</item>
2689 <item><qref id="f-Date"><tt>Date</tt></qref> (mandatory)</item>
2690 <item><qref id="f-Source"><tt>Source</tt></qref> (mandatory)</item>
2691 <item><qref id="f-Binary"><tt>Binary</tt></qref> (mandatory)</item>
2692 <item><qref id="f-Architecture"><tt>Architecture</tt></qref> (mandatory)</item>
2693 <item><qref id="f-Version"><tt>Version</tt></qref> (mandatory)</item>
2694 <item><qref id="f-Distribution"><tt>Distribution</tt></qref> (mandatory)</item>
2695 <item><qref id="f-Urgency"><tt>Urgency</tt></qref> (recommended)</item>
2696 <item><qref id="f-Maintainer"><tt>Maintainer</tt></qref> (mandatory)</item>
2697 <item><qref id="f-Changed-By"><tt>Changed-By</tt></qref></item>
2698 <item><qref id="f-Description"><tt>Description</tt></qref> (mandatory)</item>
2699 <item><qref id="f-Closes"><tt>Closes</tt></qref></item>
2700 <item><qref id="f-Changes"><tt>Changes</tt></qref> (mandatory)</item>
2701 <item><qref id="f-Checksums"><tt>Checksums-Sha1</tt>
2702 and <tt>Checksums-Sha256</tt></qref> (recommended)</item>
2703 <item><qref id="f-Files"><tt>Files</tt></qref> (mandatory)</item>
2708 <sect id="controlfieldslist">
2709 <heading>List of fields</heading>
2711 <sect1 id="f-Source">
2712 <heading><tt>Source</tt></heading>
2715 This field identifies the source package name.
2719 In <file>debian/control</file> or a <file>.dsc</file> file,
2720 this field must contain only the name of the source package.
2724 In a binary package control file or a <file>.changes</file>
2725 file, the source package name may be followed by a version
2726 number in parentheses<footnote>
2727 It is customary to leave a space after the package name
2728 if a version number is specified.
2730 This version number may be omitted (and is, by
2731 <prgn>dpkg-gencontrol</prgn>) if it has the same value as
2732 the <tt>Version</tt> field of the binary package in
2733 question. The field itself may be omitted from a binary
2734 package control file when the source package has the same
2735 name and version as the binary package.
2739 Package names (both source and binary,
2740 see <ref id="f-Package">) must consist only of lower case
2741 letters (<tt>a-z</tt>), digits (<tt>0-9</tt>), plus
2742 (<tt>+</tt>) and minus (<tt>-</tt>) signs, and periods
2743 (<tt>.</tt>). They must be at least two characters long and
2744 must start with an alphanumeric character.
2748 <sect1 id="f-Maintainer">
2749 <heading><tt>Maintainer</tt></heading>
2752 The package maintainer's name and email address. The name
2753 must come first, then the email address inside angle
2754 brackets <tt><></tt> (in RFC822 format).
2758 If the maintainer's name contains a full stop then the
2759 whole field will not work directly as an email address due
2760 to a misfeature in the syntax specified in RFC822; a
2761 program using this field as an address must check for this
2762 and correct the problem if necessary (for example by
2763 putting the name in round brackets and moving it to the
2764 end, and bringing the email address forward).
2768 See <ref id="maintainer"> for additional requirements and
2769 information about package maintainers.
2773 <sect1 id="f-Uploaders">
2774 <heading><tt>Uploaders</tt></heading>
2777 List of the names and email addresses of co-maintainers of the
2778 package, if any. If the package has other maintainers besides
2779 the one named in the <qref id="f-Maintainer">Maintainer
2780 field</qref>, their names and email addresses should be listed
2781 here. The format of each entry is the same as that of the
2782 Maintainer field, and multiple entries must be comma
2787 This is normally an optional field, but if
2788 the <tt>Maintainer</tt> control field names a group of people
2789 and a shared email address, the <tt>Uploaders</tt> field must
2790 be present and must contain at least one human with their
2791 personal email address.
2795 Any parser that interprets the Uploaders field in
2796 <file>debian/control</file> must permit it to span multiple
2797 lines. Line breaks in an Uploaders field that spans multiple
2798 lines are not significant and the semantics of the field are
2799 the same as if the line breaks had not been present.
2803 <sect1 id="f-Changed-By">
2804 <heading><tt>Changed-By</tt></heading>
2807 The name and email address of the person who prepared this
2808 version of the package, usually a maintainer. The syntax is
2809 the same as for the <qref id="f-Maintainer">Maintainer
2814 <sect1 id="f-Section">
2815 <heading><tt>Section</tt></heading>
2818 This field specifies an application area into which the package
2819 has been classified. See <ref id="subsections">.
2823 When it appears in the <file>debian/control</file> file,
2824 it gives the value for the subfield of the same name in
2825 the <tt>Files</tt> field of the <file>.changes</file> file.
2826 It also gives the default for the same field in the binary
2831 <sect1 id="f-Priority">
2832 <heading><tt>Priority</tt></heading>
2835 This field represents how important it is that the user
2836 have the package installed. See <ref id="priorities">.
2840 When it appears in the <file>debian/control</file> file,
2841 it gives the value for the subfield of the same name in
2842 the <tt>Files</tt> field of the <file>.changes</file> file.
2843 It also gives the default for the same field in the binary
2848 <sect1 id="f-Package">
2849 <heading><tt>Package</tt></heading>
2852 The name of the binary package.
2856 Binary package names must follow the same syntax and
2857 restrictions as source package names. See <ref id="f-Source">
2862 <sect1 id="f-Architecture">
2863 <heading><tt>Architecture</tt></heading>
2866 Depending on context and the control file used, the
2867 <tt>Architecture</tt> field can include the following sets of
2871 A unique single word identifying a Debian machine
2872 architecture as described in <ref id="arch-spec">.
2875 An architecture wildcard identifying a set of Debian
2876 machine architectures, see <ref id="arch-wildcard-spec">.
2877 <tt>any</tt> matches all Debian machine architectures
2878 and is the most frequently used.
2881 <tt>all</tt>, which indicates an
2882 architecture-independent package.
2885 <tt>source</tt>, which indicates a source package.
2891 In the main <file>debian/control</file> file in the source
2892 package, this field may contain the special
2893 value <tt>all</tt>, the special architecture
2894 wildcard <tt>any</tt>, or a list of specific and wildcard
2895 architectures separated by spaces. If <tt>all</tt>
2896 or <tt>any</tt> appears, that value must be the entire
2897 contents of the field. Most packages will use
2898 either <tt>all</tt> or <tt>any</tt>.
2902 Specifying a specific list of architectures indicates that the
2903 source will build an architecture-dependent package only on
2904 architectures included in the list. Specifying a list of
2905 architecture wildcards indicates that the source will build an
2906 architecture-dependent package on only those architectures
2907 that match any of the specified architecture wildcards.
2908 Specifying a list of architectures or architecture wildcards
2909 other than <tt>any</tt> is for the minority of cases where a
2910 program is not portable or is not useful on some
2911 architectures. Where possible, the program should be made
2916 In the source package control file <file>.dsc</file>, this
2917 field may contain either the architecture
2918 wildcard <tt>any</tt> or a list of architectures and
2919 architecture wildcards separated by spaces. If a list is
2920 given, it may include (or consist solely of) the special
2921 value <tt>all</tt>. In other words, in <file>.dsc</file>
2922 files unlike the <file>debian/control</file>, <tt>all</tt> may
2923 occur in combination with specific architectures.
2924 The <tt>Architecture</tt> field in the source package control
2925 file <file>.dsc</file> is generally constructed from
2926 the <tt>Architecture</tt> fields in
2927 the <file>debian/control</file> in the source package.
2931 Specifying <tt>any</tt> indicates that the source package
2932 isn't dependent on any particular architecture and should
2933 compile fine on any one. The produced binary package(s)
2934 will either be specific to whatever the current build
2935 architecture is or will be architecture-independent.
2939 Specifying only <tt>all</tt> indicates that the source package
2940 will only build architecture-independent packages. If this is
2941 the case, <tt>all</tt> must be used rather than <tt>any</tt>;
2942 <tt>any</tt> implies that the source package will build at
2943 least one architecture-dependent package.
2947 Specifying a list of architectures or architecture wildcards
2948 indicates that the source will build an architecture-dependent
2949 package, and will only work correctly on the listed or
2950 matching architectures. If the source package also builds at
2951 least one architecture-independent package, <tt>all</tt> will
2952 also be included in the list.
2956 In a <file>.changes</file> file, the <tt>Architecture</tt>
2957 field lists the architecture(s) of the package(s) currently
2958 being uploaded. This will be a list; if the source for the
2959 package is also being uploaded, the special
2960 entry <tt>source</tt> is also present. <tt>all</tt> will be
2961 present if any architecture-independent packages are being
2962 uploaded. Architecture wildcards such as <tt>any</tt> must
2963 never occur in the <tt>Architecture</tt> field in
2964 the <file>.changes</file> file.
2968 See <ref id="debianrules"> for information on how to get
2969 the architecture for the build process.
2973 <sect1 id="f-Essential">
2974 <heading><tt>Essential</tt></heading>
2977 This is a boolean field which may occur only in the
2978 control file of a binary package or in a per-package fields
2979 paragraph of a main source control data file.
2983 If set to <tt>yes</tt> then the package management system
2984 will refuse to remove the package (upgrading and replacing
2985 it is still possible). The other possible value is <tt>no</tt>,
2986 which is the same as not having the field at all.
2991 <heading>Package interrelationship fields:
2992 <tt>Depends</tt>, <tt>Pre-Depends</tt>,
2993 <tt>Recommends</tt>, <tt>Suggests</tt>,
2994 <tt>Breaks</tt>, <tt>Conflicts</tt>,
2995 <tt>Provides</tt>, <tt>Replaces</tt>, <tt>Enhances</tt>
2999 These fields describe the package's relationships with
3000 other packages. Their syntax and semantics are described
3001 in <ref id="relationships">.</p>
3004 <sect1 id="f-Standards-Version">
3005 <heading><tt>Standards-Version</tt></heading>
3008 The most recent version of the standards (the policy
3009 manual and associated texts) with which the package
3014 The version number has four components: major and minor
3015 version number and major and minor patch level. When the
3016 standards change in a way that requires every package to
3017 change the major number will be changed. Significant
3018 changes that will require work in many packages will be
3019 signaled by a change to the minor number. The major patch
3020 level will be changed for any change to the meaning of the
3021 standards, however small; the minor patch level will be
3022 changed when only cosmetic, typographical or other edits
3023 are made which neither change the meaning of the document
3024 nor affect the contents of packages.
3028 Thus only the first three components of the policy version
3029 are significant in the <em>Standards-Version</em> control
3030 field, and so either these three components or all four
3031 components may be specified.<footnote>
3032 In the past, people specified the full version number
3033 in the Standards-Version field, for example "2.3.0.0".
3034 Since minor patch-level changes don't introduce new
3035 policy, it was thought it would be better to relax
3036 policy and only require the first 3 components to be
3037 specified, in this example "2.3.0". All four
3038 components may still be used if someone wishes to do so.
3044 <sect1 id="f-Version">
3045 <heading><tt>Version</tt></heading>
3048 The version number of a package. The format is:
3049 [<var>epoch</var><tt>:</tt>]<var>upstream_version</var>[<tt>-</tt><var>debian_revision</var>]
3053 The three components here are:
3055 <tag><var>epoch</var></tag>
3058 This is a single (generally small) unsigned integer. It
3059 may be omitted, in which case zero is assumed. If it is
3060 omitted then the <var>upstream_version</var> may not
3065 It is provided to allow mistakes in the version numbers
3066 of older versions of a package, and also a package's
3067 previous version numbering schemes, to be left behind.
3071 <tag><var>upstream_version</var></tag>
3074 This is the main part of the version number. It is
3075 usually the version number of the original ("upstream")
3076 package from which the <file>.deb</file> file has been made,
3077 if this is applicable. Usually this will be in the same
3078 format as that specified by the upstream author(s);
3079 however, it may need to be reformatted to fit into the
3080 package management system's format and comparison
3085 The comparison behavior of the package management system
3086 with respect to the <var>upstream_version</var> is
3087 described below. The <var>upstream_version</var>
3088 portion of the version number is mandatory.
3092 The <var>upstream_version</var> may contain only
3093 alphanumerics<footnote>
3094 Alphanumerics are <tt>A-Za-z0-9</tt> only.
3096 and the characters <tt>.</tt> <tt>+</tt> <tt>-</tt>
3097 <tt>:</tt> <tt>~</tt> (full stop, plus, hyphen, colon,
3098 tilde) and should start with a digit. If there is no
3099 <var>debian_revision</var> then hyphens are not allowed;
3100 if there is no <var>epoch</var> then colons are not
3105 <tag><var>debian_revision</var></tag>
3108 This part of the version number specifies the version of
3109 the Debian package based on the upstream version. It
3110 may contain only alphanumerics and the characters
3111 <tt>+</tt> <tt>.</tt> <tt>~</tt> (plus, full stop,
3112 tilde) and is compared in the same way as the
3113 <var>upstream_version</var> is.
3117 It is optional; if it isn't present then the
3118 <var>upstream_version</var> may not contain a hyphen.
3119 This format represents the case where a piece of
3120 software was written specifically to be a Debian
3121 package, where the Debian package source must always
3122 be identical to the pristine source and therefore no
3123 revision indication is required.
3127 It is conventional to restart the
3128 <var>debian_revision</var> at <tt>1</tt> each time the
3129 <var>upstream_version</var> is increased.
3133 The package management system will break the version
3134 number apart at the last hyphen in the string (if there
3135 is one) to determine the <var>upstream_version</var> and
3136 <var>debian_revision</var>. The absence of a
3137 <var>debian_revision</var> is equivalent to a
3138 <var>debian_revision</var> of <tt>0</tt>.
3145 When comparing two version numbers, first the <var>epoch</var>
3146 of each are compared, then the <var>upstream_version</var> if
3147 <var>epoch</var> is equal, and then <var>debian_revision</var>
3148 if <var>upstream_version</var> is also equal.
3149 <var>epoch</var> is compared numerically. The
3150 <var>upstream_version</var> and <var>debian_revision</var>
3151 parts are compared by the package management system using the
3152 following algorithm:
3156 The strings are compared from left to right.
3160 First the initial part of each string consisting entirely of
3161 non-digit characters is determined. These two parts (one of
3162 which may be empty) are compared lexically. If a difference
3163 is found it is returned. The lexical comparison is a
3164 comparison of ASCII values modified so that all the letters
3165 sort earlier than all the non-letters and so that a tilde
3166 sorts before anything, even the end of a part. For example,
3167 the following parts are in sorted order from earliest to
3168 latest: <tt>~~</tt>, <tt>~~a</tt>, <tt>~</tt>, the empty part,
3169 <tt>a</tt>.<footnote>
3170 One common use of <tt>~</tt> is for upstream pre-releases.
3171 For example, <tt>1.0~beta1~svn1245</tt> sorts earlier than
3172 <tt>1.0~beta1</tt>, which sorts earlier than <tt>1.0</tt>.
3177 Then the initial part of the remainder of each string which
3178 consists entirely of digit characters is determined. The
3179 numerical values of these two parts are compared, and any
3180 difference found is returned as the result of the comparison.
3181 For these purposes an empty string (which can only occur at
3182 the end of one or both version strings being compared) counts
3187 These two steps (comparing and removing initial non-digit
3188 strings and initial digit strings) are repeated until a
3189 difference is found or both strings are exhausted.
3193 Note that the purpose of epochs is to allow us to leave behind
3194 mistakes in version numbering, and to cope with situations
3195 where the version numbering scheme changes. It is
3196 <em>not</em> intended to cope with version numbers containing
3197 strings of letters which the package management system cannot
3198 interpret (such as <tt>ALPHA</tt> or <tt>pre-</tt>), or with
3199 silly orderings.<footnote>
3200 The author of this manual has heard of a package whose
3201 versions went <tt>1.1</tt>, <tt>1.2</tt>, <tt>1.3</tt>,
3202 <tt>1</tt>, <tt>2.1</tt>, <tt>2.2</tt>, <tt>2</tt> and so
3208 <sect1 id="f-Description">
3209 <heading><tt>Description</tt></heading>
3212 In a source or binary control file, the <tt>Description</tt>
3213 field contains a description of the binary package, consisting
3214 of two parts, the synopsis or the short description, and the
3215 long description. The field's format is as follows:
3220 Description: <single line synopsis>
3221 <extended description over several lines>
3226 The lines in the extended description can have these formats:
3232 Those starting with a single space are part of a paragraph.
3233 Successive lines of this form will be word-wrapped when
3234 displayed. The leading space will usually be stripped off.
3238 Those starting with two or more spaces. These will be
3239 displayed verbatim. If the display cannot be panned
3240 horizontally, the displaying program will line wrap them "hard"
3241 (i.e., without taking account of word breaks). If it can they
3242 will be allowed to trail off to the right. None, one or two
3243 initial spaces may be deleted, but the number of spaces
3244 deleted from each line will be the same (so that you can have
3245 indenting work correctly, for example).
3249 Those containing a single space followed by a single full stop
3250 character. These are rendered as blank lines. This is the
3251 <em>only</em> way to get a blank line<footnote>
3252 Completely empty lines will not be rendered as blank lines.
3253 Instead, they will cause the parser to think you're starting
3254 a whole new record in the control file, and will therefore
3255 likely abort with an error.
3260 Those containing a space, a full stop and some more characters.
3261 These are for future expansion. Do not use them.
3267 Do not use tab characters. Their effect is not predictable.
3271 See <ref id="descriptions"> for further information on this.
3275 In a <file>.changes</file> file, the <tt>Description</tt>
3276 field contains a summary of the descriptions for the packages
3277 being uploaded. For this case, the first line of the field
3278 value (the part on the same line as <tt>Description:</tt>) is
3279 always empty. The content of the field is expressed as
3280 continuation lines, one line per package. Each line is
3281 indented by one space and contains the name of a binary
3282 package, a space, a hyphen (<tt>-</tt>), a space, and the
3283 short description line from that package.
3287 <sect1 id="f-Distribution">
3288 <heading><tt>Distribution</tt></heading>
3291 In a <file>.changes</file> file or parsed changelog output
3292 this contains the (space-separated) name(s) of the
3293 distribution(s) where this version of the package should
3294 be installed. Valid distributions are determined by the
3295 archive maintainers.<footnote>
3296 Example distribution names in the Debian archive used in
3297 <file>.changes</file> files are:
3298 <taglist compact="compact">
3299 <tag><em>unstable</em></tag>
3301 This distribution value refers to the
3302 <em>developmental</em> part of the Debian distribution
3303 tree. Most new packages, new upstream versions of
3304 packages and bug fixes go into the <em>unstable</em>
3308 <tag><em>experimental</em></tag>
3310 The packages with this distribution value are deemed
3311 by their maintainers to be high risk. Oftentimes they
3312 represent early beta or developmental packages from
3313 various sources that the maintainers want people to
3314 try, but are not ready to be a part of the other parts
3315 of the Debian distribution tree.
3320 Others are used for updating stable releases or for
3321 security uploads. More information is available in the
3322 Debian Developer's Reference, section "The Debian
3326 The Debian archive software only supports listing a single
3327 distribution. Migration of packages to other distributions is
3328 handled outside of the upload process.
3333 <heading><tt>Date</tt></heading>
3336 This field includes the date the package was built or last
3337 edited. It must be in the same format as the <var>date</var>
3338 in a <file>debian/changelog</file> entry.
3342 The value of this field is usually extracted from the
3343 <file>debian/changelog</file> file - see
3344 <ref id="dpkgchangelog">).
3348 <sect1 id="f-Format">
3349 <heading><tt>Format</tt></heading>
3352 In <qref id="debianchangesfiles"><file>.changes</file></qref>
3353 files, this field declares the format version of that file.
3354 The syntax of the field value is the same as that of
3355 a <qref id="f-Version">package version number</qref> except
3356 that no epoch or Debian revision is allowed. The format
3357 described in this document is <tt>&changesversion;</tt>.
3361 In <qref id="debiansourcecontrolfiles"><file>.dsc</file>
3362 Debian source control</qref> files, this field declares the
3363 format of the source package. The field value is used by
3364 programs acting on a source package to interpret the list of
3365 files in the source package and determine how to unpack it.
3366 The syntax of the field value is a numeric major revision, a
3367 period, a numeric minor revision, and then an optional subtype
3368 after whitespace, which if specified is an alphanumeric word
3369 in parentheses. The subtype is optional in the syntax but may
3370 be mandatory for particular source format revisions.
3372 The source formats currently supported by the Debian archive
3373 software are <tt>1.0</tt>, <tt>3.0 (native)</tt>,
3374 and <tt>3.0 (quilt)</tt>.
3379 <sect1 id="f-Urgency">
3380 <heading><tt>Urgency</tt></heading>
3383 This is a description of how important it is to upgrade to
3384 this version from previous ones. It consists of a single
3385 keyword taking one of the values <tt>low</tt>,
3386 <tt>medium</tt>, <tt>high</tt>, <tt>emergency</tt>, or
3387 <tt>critical</tt><footnote>
3388 Other urgency values are supported with configuration
3389 changes in the archive software but are not used in Debian.
3390 The urgency affects how quickly a package will be considered
3391 for inclusion into the <tt>testing</tt> distribution and
3392 gives an indication of the importance of any fixes included
3393 in the upload. <tt>Emergency</tt> and <tt>critical</tt> are
3394 treated as synonymous.
3395 </footnote> (not case-sensitive) followed by an optional
3396 commentary (separated by a space) which is usually in
3397 parentheses. For example:
3400 Urgency: low (HIGH for users of diversions)
3406 The value of this field is usually extracted from the
3407 <file>debian/changelog</file> file - see
3408 <ref id="dpkgchangelog">.
3412 <sect1 id="f-Changes">
3413 <heading><tt>Changes</tt></heading>
3416 This field contains the human-readable changes data, describing
3417 the differences between the last version and the current one.
3421 The first line of the field value (the part on the same line
3422 as <tt>Changes:</tt>) is always empty. The content of the
3423 field is expressed as continuation lines, with each line
3424 indented by at least one space. Blank lines must be
3425 represented by a line consisting only of a space and a full
3430 The value of this field is usually extracted from the
3431 <file>debian/changelog</file> file - see
3432 <ref id="dpkgchangelog">).
3436 Each version's change information should be preceded by a
3437 "title" line giving at least the version, distribution(s)
3438 and urgency, in a human-readable way.
3442 If data from several versions is being returned the entry
3443 for the most recent version should be returned first, and
3444 entries should be separated by the representation of a
3445 blank line (the "title" line may also be followed by the
3446 representation of a blank line).
3450 <sect1 id="f-Binary">
3451 <heading><tt>Binary</tt></heading>
3454 This field is a list of binary packages. Its syntax and
3455 meaning varies depending on the control file in which it
3460 When it appears in the <file>.dsc</file> file, it lists binary
3461 packages which a source package can produce, separated by
3463 A space after each comma is conventional.
3464 </footnote>. It may span multiple lines. The source package
3465 does not necessarily produce all of these binary packages for
3466 every architecture. The source control file doesn't contain
3467 details of which architectures are appropriate for which of
3468 the binary packages.
3472 When it appears in a <file>.changes</file> file, it lists the
3473 names of the binary packages being uploaded, separated by
3474 whitespace (not commas). It may span multiple lines.
3478 <sect1 id="f-Installed-Size">
3479 <heading><tt>Installed-Size</tt></heading>
3482 This field appears in the control files of binary packages,
3483 and in the <file>Packages</file> files. It gives an estimate
3484 of the total amount of disk space required to install the
3485 named package. Actual installed size may vary based on block
3486 size, file system properties, or actions taken by package
3491 The disk space is given as the integer value of the estimated
3492 installed size in bytes, divided by 1024 and rounded up.
3496 <sect1 id="f-Files">
3497 <heading><tt>Files</tt></heading>
3500 This field contains a list of files with information about
3501 each one. The exact information and syntax varies with
3506 In all cases, Files is a multiline field. The first line of
3507 the field value (the part on the same line as <tt>Files:</tt>)
3508 is always empty. The content of the field is expressed as
3509 continuation lines, one line per file. Each line must be
3510 indented by one space and contain a number of sub-fields,
3511 separated by spaces, as described below.
3515 In the <file>.dsc</file> file, each line contains the MD5
3516 checksum, size and filename of the tar file and (if
3517 applicable) diff file which make up the remainder of the
3518 source package<footnote>
3519 That is, the parts which are not the <tt>.dsc</tt>.
3520 </footnote>. For example:
3523 c6f698f19f2a2aa07dbb9bbda90a2754 571925 example_1.2.orig.tar.gz
3524 938512f08422f3509ff36f125f5873ba 6220 example_1.2-1.diff.gz
3526 The exact forms of the filenames are described
3527 in <ref id="pkg-sourcearchives">.
3531 In the <file>.changes</file> file this contains one line per
3532 file being uploaded. Each line contains the MD5 checksum,
3533 size, section and priority and the filename. For example:
3536 4c31ab7bfc40d3cf49d7811987390357 1428 text extra example_1.2-1.dsc
3537 c6f698f19f2a2aa07dbb9bbda90a2754 571925 text extra example_1.2.orig.tar.gz
3538 938512f08422f3509ff36f125f5873ba 6220 text extra example_1.2-1.diff.gz
3539 7c98fe853b3bbb47a00e5cd129b6cb56 703542 text extra example_1.2-1_i386.deb
3541 The <qref id="f-Section">section</qref>
3542 and <qref id="f-Priority">priority</qref> are the values of
3543 the corresponding fields in the main source control file. If
3544 no section or priority is specified then <tt>-</tt> should be
3545 used, though section and priority values must be specified for
3546 new packages to be installed properly.
3550 The special value <tt>byhand</tt> for the section in a
3551 <tt>.changes</tt> file indicates that the file in question
3552 is not an ordinary package file and must by installed by
3553 hand by the distribution maintainers. If the section is
3554 <tt>byhand</tt> the priority should be <tt>-</tt>.
3558 If a new Debian revision of a package is being shipped and
3559 no new original source archive is being distributed the
3560 <tt>.dsc</tt> must still contain the <tt>Files</tt> field
3561 entry for the original source archive
3562 <file><var>package</var>_<var>upstream-version</var>.orig.tar.gz</file>,
3563 but the <file>.changes</file> file should leave it out. In
3564 this case the original source archive on the distribution
3565 site must match exactly, byte-for-byte, the original
3566 source archive which was used to generate the
3567 <file>.dsc</file> file and diff which are being uploaded.</p>
3570 <sect1 id="f-Closes">
3571 <heading><tt>Closes</tt></heading>
3574 A space-separated list of bug report numbers that the upload
3575 governed by the .changes file closes.
3579 <sect1 id="f-Homepage">
3580 <heading><tt>Homepage</tt></heading>
3583 The URL of the web site for this package, preferably (when
3584 applicable) the site from which the original source can be
3585 obtained and any additional upstream documentation or
3586 information may be found. The content of this field is a
3587 simple URL without any surrounding characters such as
3592 <sect1 id="f-Checksums">
3593 <heading><tt>Checksums-Sha1</tt>
3594 and <tt>Checksums-Sha256</tt></heading>
3597 These fields contain a list of files with a checksum and size
3598 for each one. Both <tt>Checksums-Sha1</tt>
3599 and <tt>Checksums-Sha256</tt> have the same syntax and differ
3600 only in the checksum algorithm used: SHA-1
3601 for <tt>Checksums-Sha1</tt> and SHA-256
3602 for <tt>Checksums-Sha256</tt>.
3606 <tt>Checksums-Sha1</tt> and <tt>Checksums-Sha256</tt> are
3607 multiline fields. The first line of the field value (the part
3608 on the same line as <tt>Checksums-Sha1:</tt>
3609 or <tt>Checksums-Sha256:</tt>) is always empty. The content
3610 of the field is expressed as continuation lines, one line per
3611 file. Each line consists of the checksum, a space, the file
3612 size, a space, and the file name. For example (from
3613 a <file>.changes</file> file):
3616 1f418afaa01464e63cc1ee8a66a05f0848bd155c 1276 example_1.0-1.dsc
3617 a0ed1456fad61116f868b1855530dbe948e20f06 171602 example_1.0.orig.tar.gz
3618 5e86ecf0671e113b63388dac81dd8d00e00ef298 6137 example_1.0-1.debian.tar.gz
3619 71a0ff7da0faaf608481195f9cf30974b142c183 548402 example_1.0-1_i386.deb
3621 ac9d57254f7e835bed299926fd51bf6f534597cc3fcc52db01c4bffedae81272 1276 example_1.0-1.dsc
3622 0d123be7f51e61c4bf15e5c492b484054be7e90f3081608a5517007bfb1fd128 171602 example_1.0.orig.tar.gz
3623 f54ae966a5f580571ae7d9ef5e1df0bd42d63e27cb505b27957351a495bc6288 6137 example_1.0-1.debian.tar.gz
3624 3bec05c03974fdecd11d020fc2e8250de8404867a8a2ce865160c250eb723664 548402 example_1.0-1_i386.deb
3629 In the <file>.dsc</file> file, these fields should list all
3630 files that make up the source package. In
3631 the <file>.changes</file> file, these fields should list all
3632 files being uploaded. The list of files in these fields
3633 must match the list of files in the <tt>Files</tt> field.
3637 <sect1 id="f-DM-Upload-Allowed">
3638 <heading><tt>DM-Upload-Allowed</tt></heading>
3641 The most recent version of a package uploaded to unstable or
3642 experimental must include the field <tt>DM-Upload-Allowed:
3643 yes</tt> in the source section of its source control file for
3644 the Debian archive to accept uploads signed with a key in the
3645 Debian Maintainer keyring. See the General
3646 Resolution <url id="http://www.debian.org/vote/2007/vote_003"
3647 name="Endorse the concept of Debian Maintainers"> for more
3654 <heading>User-defined fields</heading>
3657 Additional user-defined fields may be added to the
3658 source package control file. Such fields will be
3659 ignored, and not copied to (for example) binary or
3660 source package control files or upload control files.
3664 If you wish to add additional unsupported fields to
3665 these output files you should use the mechanism
3670 Fields in the main source control information file with
3671 names starting <tt>X</tt>, followed by one or more of
3672 the letters <tt>BCS</tt> and a hyphen <tt>-</tt>, will
3673 be copied to the output files. Only the part of the
3674 field name after the hyphen will be used in the output
3675 file. Where the letter <tt>B</tt> is used the field
3676 will appear in binary package control files, where the
3677 letter <tt>S</tt> is used in source package control
3678 files and where <tt>C</tt> is used in upload control
3679 (<tt>.changes</tt>) files.
3683 For example, if the main source information control file
3686 XBS-Comment: I stand between the candle and the star.
3688 then the binary and source package control files will contain the
3691 Comment: I stand between the candle and the star.
3700 <chapt id="maintainerscripts">
3701 <heading>Package maintainer scripts and installation procedure</heading>
3704 <heading>Introduction to package maintainer scripts</heading>
3707 It is possible to supply scripts as part of a package which
3708 the package management system will run for you when your
3709 package is installed, upgraded or removed.
3713 These scripts are the control information
3714 files <prgn>preinst</prgn>, <prgn>postinst</prgn>, <prgn>prerm</prgn>
3715 and <prgn>postrm</prgn>. They must be proper executable files;
3716 if they are scripts (which is recommended), they must start with
3717 the usual <tt>#!</tt> convention. They should be readable and
3718 executable by anyone, and must not be world-writable.
3722 The package management system looks at the exit status from
3723 these scripts. It is important that they exit with a
3724 non-zero status if there is an error, so that the package
3725 management system can stop its processing. For shell
3726 scripts this means that you <em>almost always</em> need to
3727 use <tt>set -e</tt> (this is usually true when writing shell
3728 scripts, in fact). It is also important, of course, that
3729 they exit with a zero status if everything went well.
3733 Additionally, packages interacting with users
3734 using <prgn>debconf</prgn> in the <prgn>postinst</prgn> script
3735 should install a <prgn>config</prgn> script as a control
3736 information file. See <ref id="maintscriptprompt"> for details.
3740 When a package is upgraded a combination of the scripts from
3741 the old and new packages is called during the upgrade
3742 procedure. If your scripts are going to be at all
3743 complicated you need to be aware of this, and may need to
3744 check the arguments to your scripts.
3748 Broadly speaking the <prgn>preinst</prgn> is called before
3749 (a particular version of) a package is unpacked, and the
3750 <prgn>postinst</prgn> afterwards; the <prgn>prerm</prgn>
3751 before (a version of) a package is removed and the
3752 <prgn>postrm</prgn> afterwards.
3756 Programs called from maintainer scripts should not normally
3757 have a path prepended to them. Before installation is
3758 started, the package management system checks to see if the
3759 programs <prgn>ldconfig</prgn>,
3760 <prgn>start-stop-daemon</prgn>, <prgn>install-info</prgn>,
3761 and <prgn>update-rc.d</prgn> can be found via the
3762 <tt>PATH</tt> environment variable. Those programs, and any
3763 other program that one would expect to be in the
3764 <tt>PATH</tt>, should thus be invoked without an absolute
3765 pathname. Maintainer scripts should also not reset the
3766 <tt>PATH</tt>, though they might choose to modify it by
3767 prepending or appending package-specific directories. These
3768 considerations really apply to all shell scripts.</p>
3771 <sect id="idempotency">
3772 <heading>Maintainer scripts idempotency</heading>
3775 It is necessary for the error recovery procedures that the
3776 scripts be idempotent. This means that if it is run
3777 successfully, and then it is called again, it doesn't bomb
3778 out or cause any harm, but just ensures that everything is
3779 the way it ought to be. If the first call failed, or
3780 aborted half way through for some reason, the second call
3781 should merely do the things that were left undone the first
3782 time, if any, and exit with a success status if everything
3784 This is so that if an error occurs, the user interrupts
3785 <prgn>dpkg</prgn> or some other unforeseen circumstance
3786 happens you don't leave the user with a badly-broken
3787 package when <prgn>dpkg</prgn> attempts to repeat the
3793 <sect id="controllingterminal">
3794 <heading>Controlling terminal for maintainer scripts</heading>
3797 Maintainer scripts are not guaranteed to run with a controlling
3798 terminal and may not be able to interact with the user. They
3799 must be able to fall back to noninteractive behavior if no
3800 controlling terminal is available. Maintainer scripts that
3801 prompt via a program conforming to the Debian Configuration
3802 Management Specification (see <ref id="maintscriptprompt">) may
3803 assume that program will handle falling back to noninteractive
3808 For high-priority prompts without a reasonable default answer,
3809 maintainer scripts may abort if there is no controlling
3810 terminal. However, this situation should be avoided if at all
3811 possible, since it prevents automated or unattended installs.
3812 In most cases, users will consider this to be a bug in the
3817 <sect id="exitstatus">
3818 <heading>Exit status</heading>
3821 Each script must return a zero exit status for
3822 success, or a nonzero one for failure, since the package
3823 management system looks for the exit status of these scripts
3824 and determines what action to take next based on that datum.
3828 <sect id="mscriptsinstact"><heading>Summary of ways maintainer
3833 What follows is a summary of all the ways in which maintainer
3834 scripts may be called along with what facilities those scripts
3835 may rely on being available at that time. Script names preceded
3836 by <var>new-</var> are the scripts from the new version of a
3837 package being installed, upgraded to, or downgraded to. Script
3838 names preceded by <var>old-</var> are the scripts from the old
3839 version of a package that is being upgraded from or downgraded
3844 The <prgn>preinst</prgn> script may be called in the following
3847 <tag><var>new-preinst</var> <tt>install</tt></tag>
3848 <tag><var>new-preinst</var> <tt>install</tt>
3849 <var>old-version</var></tag>
3850 <tag><var>new-preinst</var> <tt>upgrade</tt>
3851 <var>old-version</var></tag>
3853 The package will not yet be unpacked, so
3854 the <prgn>preinst</prgn> script cannot rely on any files
3855 included in its package. Only essential packages and
3856 pre-dependencies (<tt>Pre-Depends</tt>) may be assumed to be
3857 available. Pre-dependencies will have been configured at
3858 least once, but at the time the <prgn>preinst</prgn> is
3859 called they may only be in an unpacked or "Half-Configured"
3860 state if a previous version of the pre-dependency was
3861 completely configured and has not been removed since then.
3864 <tag><var>old-preinst</var> <tt>abort-upgrade</tt>
3865 <var>new-version</var></tag>
3867 Called during error handling of an upgrade that failed after
3868 unpacking the new package because the <tt>postrm
3869 upgrade</tt> action failed. The unpacked files may be
3870 partly from the new version or partly missing, so the script
3871 cannot rely on files included in the package. Package
3872 dependencies may not be available. Pre-dependencies will be
3873 at least unpacked following the same rules as above, except
3874 they may be only "Half-Installed" if an upgrade of the
3875 pre-dependency failed.<footnote>
3876 This can happen if the new version of the package no
3877 longer pre-depends on a package that had been partially
3885 The <prgn>postinst</prgn> script may be called in the following
3888 <tag><var>postinst</var> <tt>configure</tt>
3889 <var>most-recently-configured-version</var></tag>
3891 The files contained in the package will be unpacked. All
3892 package dependencies will at least be unpacked. If there
3893 are no circular dependencies involved, all package
3894 dependencies will be configured. For behavior in the case
3895 of circular dependencies, see the discussion
3896 in <ref id="binarydeps">.
3899 <tag><var>old-postinst</var> <tt>abort-upgrade</tt>
3900 <var>new-version</var></tag>
3901 <tag><var>conflictor's-postinst</var> <tt>abort-remove</tt>
3902 <tt>in-favour</tt> <var>package</var>
3903 <var>new-version</var></tag>
3904 <tag><var>postinst</var> <tt>abort-remove</tt></tag>
3905 <tag><var>deconfigured's-postinst</var>
3906 <tt>abort-deconfigure</tt> <tt>in-favour</tt>
3907 <var>failed-install-package</var> <var>version</var>
3908 [<tt>removing</tt> <var>conflicting-package</var>
3909 <var>version</var>]</tag>
3911 The files contained in the package will be unpacked. All
3912 package dependencies will at least be "Half-Installed" and
3913 will have previously been configured and not removed.
3914 However, dependencies may not be configured or even fully
3915 unpacked in some error situations.<footnote>
3916 For example, suppose packages foo and bar are installed
3917 with foo depending on bar. If an upgrade of bar were
3918 started and then aborted, and then an attempt to remove
3919 foo failed because its <prgn>prerm</prgn> script failed,
3920 foo's <tt>postinst abort-remove</tt> would be called with
3921 bar only "Half-Installed".
3923 The <prgn>postinst</prgn> should still attempt any actions
3924 for which its dependencies are required, since they will
3925 normally be available, but consider the correct error
3926 handling approach if those actions fail. Aborting
3927 the <prgn>postinst</prgn> action if commands or facilities
3928 from the package dependencies are not available is often the
3935 The <prgn>prerm</prgn> script may be called in the following
3938 <tag><var>prerm</var> <tt>remove</tt></tag>
3939 <tag><var>old-prerm</var>
3940 <tt>upgrade</tt><var>new-version</var></tag>
3941 <tag><var>conflictor's-prerm</var> <tt>remove</tt>
3942 <tt>in-favour</tt> <var>package</var>
3943 <var>new-version</var></tag>
3944 <tag><var>deconfigured's-prerm</var> <tt>deconfigure</tt>
3945 <tt>in-favour</tt> <var>package-being-installed</var>
3946 <var>version</var> [<tt>removing</tt>
3947 <var>conflicting-package</var> <var>version</var>]</tag>
3949 The package whose <prgn>prerm</prgn> is being called will be
3950 at least "Half-Installed". All package dependencies will at
3951 least be "Half-Installed" and will have previously been
3952 configured and not removed. If there was no error, all
3953 dependencies will at least be unpacked, but these actions
3954 may be called in various error states where dependencies are
3955 only "Half-Installed" due to a partial upgrade.
3958 <tag><var>new-prerm</var> <tt>failed-upgrade</tt>
3959 <var>old-version</var></tag>
3961 Called during error handling when <tt>prerm upgrade</tt>
3962 fails. The new package will not yet be unpacked, and all
3963 the same constraints as for <tt>preinst upgrade</tt> apply.
3969 The <prgn>postrm</prgn> script may be called in the following
3972 <tag><var>postrm</var> <tt>remove</tt></tag>
3973 <tag><var>postrm</var> <tt>purge</tt></tag>
3974 <tag><var>old-postrm</var> <tt>upgrade</tt>
3975 <var>new-version</var></tag>
3976 <tag><var>disappearer's-postrm</var> <tt>disappear</tt>
3977 <var>overwriter</var> <var>overwriter-version</var></tag>
3979 The <prgn>postrm</prgn> script is called after the package's
3980 files have been removed or replaced. The package
3981 whose <prgn>postrm</prgn> is being called may have
3982 previously been deconfigured and only be unpacked, at which
3983 point subsequent package changes do not consider its
3984 dependencies. Therefore, all <prgn>postrm</prgn> actions
3985 may only rely on essential packages and must gracefully skip
3986 any actions that require the package's dependencies if those
3987 dependencies are unavailable.<footnote>
3988 This is often done by checking whether the command or
3989 facility the <prgn>postrm</prgn> intends to call is
3990 available before calling it. For example:
3992 if [ "$1" = purge ] && [ -e /usr/share/debconf/confmodule ]; then
3993 . /usr/share/debconf/confmodule
3997 in <prgn>postrm</prgn> purges the <prgn>debconf</prgn>
3998 configuration for the package
3999 if <package>debconf</package> is installed.
4003 <tag><var>new-postrm</var> <tt>failed-upgrade</tt>
4004 <var>old-version</var></tag>
4006 Called when the old <tt>postrm upgrade</tt> action fails.
4007 The new package will be unpacked, but only essential
4008 packages and pre-dependencies can be relied on.
4009 Pre-dependencies will either be configured or will be
4010 "Unpacked" or "Half-Configured" but previously had been
4011 configured and was never removed.
4014 <tag><var>new-postrm</var> <tt>abort-install</tt></tag>
4015 <tag><var>new-postrm</var> <tt>abort-install</tt>
4016 <var>old-version</var></tag>
4017 <tag><var>new-postrm</var> <tt>abort-upgrade</tt>
4018 <var>old-version</var></tag>
4020 Called before unpacking the new package as part of the
4021 error handling of <prgn>preinst</prgn> failures. May assume
4022 the same state as <prgn>preinst</prgn> can assume.
4028 <sect id="unpackphase">
4029 <heading>Details of unpack phase of installation or upgrade</heading>
4032 The procedure on installation/upgrade/overwrite/disappear
4033 (i.e., when running <tt>dpkg --unpack</tt>, or the unpack
4034 stage of <tt>dpkg --install</tt>) is as follows. In each
4035 case, if a major error occurs (unless listed below) the
4036 actions are, in general, run backwards - this means that the
4037 maintainer scripts are run with different arguments in
4038 reverse order. These are the "error unwind" calls listed
4045 If a version of the package is already installed, call
4046 <example compact="compact">
4047 <var>old-prerm</var> upgrade <var>new-version</var>
4051 If the script runs but exits with a non-zero
4052 exit status, <prgn>dpkg</prgn> will attempt:
4053 <example compact="compact">
4054 <var>new-prerm</var> failed-upgrade <var>old-version</var>
4056 If this works, the upgrade continues. If this
4057 does not work, the error unwind:
4058 <example compact="compact">
4059 <var>old-postinst</var> abort-upgrade <var>new-version</var>
4061 If this works, then the old-version is
4062 "Installed", if not, the old version is in a
4063 "Half-Configured" state.
4069 If a "conflicting" package is being removed at the same time,
4070 or if any package will be broken (due to <tt>Breaks</tt>):
4073 If <tt>--auto-deconfigure</tt> is
4074 specified, call, for each package to be deconfigured
4075 due to <tt>Breaks</tt>:
4076 <example compact="compact">
4077 <var>deconfigured's-prerm</var> deconfigure \
4078 in-favour <var>package-being-installed</var> <var>version</var>
4081 <example compact="compact">
4082 <var>deconfigured's-postinst</var> abort-deconfigure \
4083 in-favour <var>package-being-installed-but-failed</var> <var>version</var>
4085 The deconfigured packages are marked as
4086 requiring configuration, so that if
4087 <tt>--install</tt> is used they will be
4088 configured again if possible.
4091 If any packages depended on a conflicting
4092 package being removed and <tt>--auto-deconfigure</tt> is
4093 specified, call, for each such package:
4094 <example compact="compact">
4095 <var>deconfigured's-prerm</var> deconfigure \
4096 in-favour <var>package-being-installed</var> <var>version</var> \
4097 removing <var>conflicting-package</var> <var>version</var>
4100 <example compact="compact">
4101 <var>deconfigured's-postinst</var> abort-deconfigure \
4102 in-favour <var>package-being-installed-but-failed</var> <var>version</var> \
4103 removing <var>conflicting-package</var> <var>version</var>
4105 The deconfigured packages are marked as
4106 requiring configuration, so that if
4107 <tt>--install</tt> is used they will be
4108 configured again if possible.
4111 To prepare for removal of each conflicting package, call:
4112 <example compact="compact">
4113 <var>conflictor's-prerm</var> remove \
4114 in-favour <var>package</var> <var>new-version</var>
4117 <example compact="compact">
4118 <var>conflictor's-postinst</var> abort-remove \
4119 in-favour <var>package</var> <var>new-version</var>
4128 If the package is being upgraded, call:
4129 <example compact="compact">
4130 <var>new-preinst</var> upgrade <var>old-version</var>
4132 If this fails, we call:
4134 <var>new-postrm</var> abort-upgrade <var>old-version</var>
4141 <var>old-postinst</var> abort-upgrade <var>new-version</var>
4143 is called. If this works, then the old version
4144 is in an "Installed" state, or else it is left
4145 in an "Unpacked" state.
4150 If it fails, then the old version is left
4151 in an "Half-Installed" state.
4158 Otherwise, if the package had some configuration
4159 files from a previous version installed (i.e., it
4160 is in the "configuration files only" state):
4161 <example compact="compact">
4162 <var>new-preinst</var> install <var>old-version</var>
4166 <var>new-postrm</var> abort-install <var>old-version</var>
4168 If this fails, the package is left in a
4169 "Half-Installed" state, which requires a
4170 reinstall. If it works, the packages is left in
4171 a "Config-Files" state.
4174 Otherwise (i.e., the package was completely purged):
4175 <example compact="compact">
4176 <var>new-preinst</var> install
4179 <example compact="compact">
4180 <var>new-postrm</var> abort-install
4182 If the error-unwind fails, the package is in a
4183 "Half-Installed" phase, and requires a
4184 reinstall. If the error unwind works, the
4185 package is in a not installed state.
4192 The new package's files are unpacked, overwriting any
4193 that may be on the system already, for example any
4194 from the old version of the same package or from
4195 another package. Backups of the old files are kept
4196 temporarily, and if anything goes wrong the package
4197 management system will attempt to put them back as
4198 part of the error unwind.
4202 It is an error for a package to contain files which
4203 are on the system in another package, unless
4204 <tt>Replaces</tt> is used (see <ref id="replaces">).
4206 The following paragraph is not currently the case:
4207 Currently the <tt>- - force-overwrite</tt> flag is
4208 enabled, downgrading it to a warning, but this may not
4214 It is a more serious error for a package to contain a
4215 plain file or other kind of non-directory where another
4216 package has a directory (again, unless
4217 <tt>Replaces</tt> is used). This error can be
4218 overridden if desired using
4219 <tt>--force-overwrite-dir</tt>, but this is not
4224 Packages which overwrite each other's files produce
4225 behavior which, though deterministic, is hard for the
4226 system administrator to understand. It can easily
4227 lead to "missing" programs if, for example, a package
4228 is unpacked which overwrites a file from another
4229 package, and is then removed again.<footnote>
4230 Part of the problem is due to what is arguably a
4231 bug in <prgn>dpkg</prgn>.
4236 A directory will never be replaced by a symbolic link
4237 to a directory or vice versa; instead, the existing
4238 state (symlink or not) will be left alone and
4239 <prgn>dpkg</prgn> will follow the symlink if there is
4248 If the package is being upgraded, call
4249 <example compact="compact">
4250 <var>old-postrm</var> upgrade <var>new-version</var>
4254 If this fails, <prgn>dpkg</prgn> will attempt:
4255 <example compact="compact">
4256 <var>new-postrm</var> failed-upgrade <var>old-version</var>
4258 If this works, installation continues. If not,
4260 <example compact="compact">
4261 <var>old-preinst</var> abort-upgrade <var>new-version</var>
4263 If this fails, the old version is left in a
4264 "Half-Installed" state. If it works, dpkg now
4266 <example compact="compact">
4267 <var>new-postrm</var> abort-upgrade <var>old-version</var>
4269 If this fails, the old version is left in a
4270 "Half-Installed" state. If it works, dpkg now
4272 <example compact="compact">
4273 <var>old-postinst</var> abort-upgrade <var>new-version</var>
4275 If this fails, the old version is in an
4282 This is the point of no return - if
4283 <prgn>dpkg</prgn> gets this far, it won't back off
4284 past this point if an error occurs. This will
4285 leave the package in a fairly bad state, which
4286 will require a successful re-installation to clear
4287 up, but it's when <prgn>dpkg</prgn> starts doing
4288 things that are irreversible.
4293 Any files which were in the old version of the package
4294 but not in the new are removed.
4298 The new file list replaces the old.
4302 The new maintainer scripts replace the old.
4306 Any packages all of whose files have been overwritten
4307 during the installation, and which aren't required for
4308 dependencies, are considered to have been removed.
4309 For each such package
4312 <prgn>dpkg</prgn> calls:
4313 <example compact="compact">
4314 <var>disappearer's-postrm</var> disappear \
4315 <var>overwriter</var> <var>overwriter-version</var>
4319 The package's maintainer scripts are removed.
4322 It is noted in the status database as being in a
4323 sane state, namely not installed (any conffiles
4324 it may have are ignored, rather than being
4325 removed by <prgn>dpkg</prgn>). Note that
4326 disappearing packages do not have their prerm
4327 called, because <prgn>dpkg</prgn> doesn't know
4328 in advance that the package is going to
4335 Any files in the package we're unpacking that are also
4336 listed in the file lists of other packages are removed
4337 from those lists. (This will lobotomize the file list
4338 of the "conflicting" package if there is one.)
4342 The backup files made during installation, above, are
4348 The new package's status is now sane, and recorded as
4353 Here is another point of no return - if the
4354 conflicting package's removal fails we do not unwind
4355 the rest of the installation; the conflicting package
4356 is left in a half-removed limbo.
4361 If there was a conflicting package we go and do the
4362 removal actions (described below), starting with the
4363 removal of the conflicting package's files (any that
4364 are also in the package being unpacked have already
4365 been removed from the conflicting package's file list,
4366 and so do not get removed now).
4372 <sect id="configdetails"><heading>Details of configuration</heading>
4375 When we configure a package (this happens with <tt>dpkg
4376 --install</tt> and <tt>dpkg --configure</tt>), we first
4377 update any <tt>conffile</tt>s and then call:
4378 <example compact="compact">
4379 <var>postinst</var> configure <var>most-recently-configured-version</var>
4384 No attempt is made to unwind after errors during
4385 configuration. If the configuration fails, the package is in
4386 a "Failed Config" state, and an error message is generated.
4390 If there is no most recently configured version
4391 <prgn>dpkg</prgn> will pass a null argument.
4394 Historical note: Truly ancient (pre-1997) versions of
4395 <prgn>dpkg</prgn> passed <tt><unknown></tt>
4396 (including the angle brackets) in this case. Even older
4397 ones did not pass a second argument at all, under any
4398 circumstance. Note that upgrades using such an old dpkg
4399 version are unlikely to work for other reasons, even if
4400 this old argument behavior is handled by your postinst script.
4406 <sect id="removedetails"><heading>Details of removal and/or
4407 configuration purging</heading>
4413 <example compact="compact">
4414 <var>prerm</var> remove
4418 If prerm fails during replacement due to conflict
4420 <var>conflictor's-postinst</var> abort-remove \
4421 in-favour <var>package</var> <var>new-version</var>
4425 <var>postinst</var> abort-remove
4429 If this fails, the package is in a "Half-Configured"
4430 state, or else it remains "Installed".
4434 The package's files are removed (except <tt>conffile</tt>s).
4437 <example compact="compact">
4438 <var>postrm</var> remove
4442 If it fails, there's no error unwind, and the package is in
4443 an "Half-Installed" state.
4448 All the maintainer scripts except the <prgn>postrm</prgn>
4453 If we aren't purging the package we stop here. Note
4454 that packages which have no <prgn>postrm</prgn> and no
4455 <tt>conffile</tt>s are automatically purged when
4456 removed, as there is no difference except for the
4457 <prgn>dpkg</prgn> status.
4461 The <tt>conffile</tt>s and any backup files
4462 (<tt>~</tt>-files, <tt>#*#</tt> files,
4463 <tt>%</tt>-files, <tt>.dpkg-{old,new,tmp}</tt>, etc.)
4468 <example compact="compact">
4469 <var>postrm</var> purge
4473 If this fails, the package remains in a "Config-Files"
4478 The package's file list is removed.
4487 <chapt id="relationships">
4488 <heading>Declaring relationships between packages</heading>
4490 <sect id="depsyntax">
4491 <heading>Syntax of relationship fields</heading>
4494 These fields all have a uniform syntax. They are a list of
4495 package names separated by commas.
4499 In the <tt>Depends</tt>, <tt>Recommends</tt>,
4500 <tt>Suggests</tt>, <tt>Pre-Depends</tt>,
4501 <tt>Build-Depends</tt> and <tt>Build-Depends-Indep</tt>
4502 control fields of the package, which declare
4503 dependencies on other packages, the package names listed may
4504 also include lists of alternative package names, separated
4505 by vertical bar (pipe) symbols <tt>|</tt>. In such a case,
4506 if any one of the alternative packages is installed, that
4507 part of the dependency is considered to be satisfied.
4511 All of the fields except for <tt>Provides</tt> may restrict
4512 their applicability to particular versions of each named
4513 package. This is done in parentheses after each individual
4514 package name; the parentheses should contain a relation from
4515 the list below followed by a version number, in the format
4516 described in <ref id="f-Version">.
4520 The relations allowed are <tt><<</tt>, <tt><=</tt>,
4521 <tt>=</tt>, <tt>>=</tt> and <tt>>></tt> for
4522 strictly earlier, earlier or equal, exactly equal, later or
4523 equal and strictly later, respectively. The deprecated
4524 forms <tt><</tt> and <tt>></tt> were used to mean
4525 earlier/later or equal, rather than strictly earlier/later,
4526 so they should not appear in new packages (though
4527 <prgn>dpkg</prgn> still supports them).
4531 Whitespace may appear at any point in the version
4532 specification subject to the rules in <ref
4533 id="controlsyntax">, and must appear where it's necessary to
4534 disambiguate; it is not otherwise significant. All of the
4535 relationship fields may span multiple lines. For
4536 consistency and in case of future changes to
4537 <prgn>dpkg</prgn> it is recommended that a single space be
4538 used after a version relationship and before a version
4539 number; it is also conventional to put a single space after
4540 each comma, on either side of each vertical bar, and before
4541 each open parenthesis. When wrapping a relationship field, it
4542 is conventional to do so after a comma and before the space
4543 following that comma.
4547 For example, a list of dependencies might appear as:
4548 <example compact="compact">
4551 Depends: libc6 (>= 2.2.1), exim | mail-transport-agent
4556 Relationships may be restricted to a certain set of
4557 architectures. This is indicated in brackets after each
4558 individual package name and the optional version specification.
4559 The brackets enclose a list of Debian architecture names
4560 separated by whitespace. Exclamation marks may be prepended to
4561 each of the names. (It is not permitted for some names to be
4562 prepended with exclamation marks while others aren't.)
4566 For build relationship fields
4567 (<tt>Build-Depends</tt>, <tt>Build-Depends-Indep</tt>,
4568 <tt>Build-Conflicts</tt> and <tt>Build-Conflicts-Indep</tt>), if
4569 the current Debian host architecture is not in this list and
4570 there are no exclamation marks in the list, or it is in the list
4571 with a prepended exclamation mark, the package name and the
4572 associated version specification are ignored completely for the
4573 purposes of defining the relationships.
4578 <example compact="compact">
4580 Build-Depends-Indep: texinfo
4581 Build-Depends: kernel-headers-2.2.10 [!hurd-i386],
4582 hurd-dev [hurd-i386], gnumach-dev [hurd-i386]
4584 requires <tt>kernel-headers-2.2.10</tt> on all architectures
4585 other than hurd-i386 and requires <tt>hurd-dev</tt> and
4586 <tt>gnumach-dev</tt> only on hurd-i386.
4590 For binary relationship fields, the architecture restriction
4591 syntax is only supported in the source package control
4592 file <file>debian/control</file>. When the corresponding binary
4593 package control file is generated, the relationship will either
4594 be omitted or included without the architecture restriction
4595 based on the architecture of the binary package. This means
4596 that architecture restrictions must not be used in binary
4597 relationship fields for architecture-independent packages
4598 (<tt>Architecture: all</tt>).
4603 <example compact="compact">
4604 Depends: foo [i386], bar [amd64]
4606 becomes <tt>Depends: foo</tt> when the package is built on
4607 the <tt>i386</tt> architecture, <tt>Depends: bar</tt> when the
4608 package is built on the <tt>amd64</tt> architecture, and omitted
4609 entirely in binary packages built on all other architectures.
4613 If the architecture-restricted dependency is part of a set of
4614 alternatives using <tt>|</tt>, that alternative is ignored
4615 completely on architectures that do not match the restriction.
4617 <example compact="compact">
4618 Build-Depends: foo [!i386] | bar [!amd64]
4620 is equivalent to <tt>bar</tt> on the i386 architecture, to
4621 <tt>foo</tt> on the amd64 architecture, and to <tt>foo |
4622 bar</tt> on all other architectures.
4626 Relationships may also be restricted to a certain set of
4627 architectures using architecture wildcards. The syntax for
4628 declaring such restrictions is the same as declaring
4629 restrictions using a certain set of architectures without
4630 architecture wildcards. For example:
4631 <example compact="compact">
4632 Build-Depends: foo [linux-any], bar [any-i386], baz [!linux-any]
4634 is equivalent to <tt>foo</tt> on architectures using the Linux
4635 kernel and any cpu, <tt>bar</tt> on architectures using any
4636 kernel and an i386 cpu, and <tt>baz</tt> on any architecture
4637 using a kernel other than Linux.
4641 Note that the binary package relationship fields such as
4642 <tt>Depends</tt> appear in one of the binary package
4643 sections of the control file, whereas the build-time
4644 relationships such as <tt>Build-Depends</tt> appear in the
4645 source package section of the control file (which is the
4650 <sect id="binarydeps">
4651 <heading>Binary Dependencies - <tt>Depends</tt>,
4652 <tt>Recommends</tt>, <tt>Suggests</tt>, <tt>Enhances</tt>,
4653 <tt>Pre-Depends</tt>
4657 Packages can declare in their control file that they have
4658 certain relationships to other packages - for example, that
4659 they may not be installed at the same time as certain other
4660 packages, and/or that they depend on the presence of others.
4664 This is done using the <tt>Depends</tt>, <tt>Pre-Depends</tt>,
4665 <tt>Recommends</tt>, <tt>Suggests</tt>, <tt>Enhances</tt>,
4666 <tt>Breaks</tt> and <tt>Conflicts</tt> control fields.
4667 <tt>Breaks</tt> is described in <ref id="breaks">, and
4668 <tt>Conflicts</tt> is described in <ref id="conflicts">. The
4669 rest are described below.
4673 These seven fields are used to declare a dependency
4674 relationship by one package on another. Except for
4675 <tt>Enhances</tt> and <tt>Breaks</tt>, they appear in the
4676 depending (binary) package's control file.
4677 (<tt>Enhances</tt> appears in the recommending package's
4678 control file, and <tt>Breaks</tt> appears in the version of
4679 depended-on package which causes the named package to
4684 A <tt>Depends</tt> field takes effect <em>only</em> when a
4685 package is to be configured. It does not prevent a package
4686 being on the system in an unconfigured state while its
4687 dependencies are unsatisfied, and it is possible to replace
4688 a package whose dependencies are satisfied and which is
4689 properly installed with a different version whose
4690 dependencies are not and cannot be satisfied; when this is
4691 done the depending package will be left unconfigured (since
4692 attempts to configure it will give errors) and will not
4693 function properly. If it is necessary, a
4694 <tt>Pre-Depends</tt> field can be used, which has a partial
4695 effect even when a package is being unpacked, as explained
4696 in detail below. (The other three dependency fields,
4697 <tt>Recommends</tt>, <tt>Suggests</tt> and
4698 <tt>Enhances</tt>, are only used by the various front-ends
4699 to <prgn>dpkg</prgn> such as <prgn>apt-get</prgn>,
4700 <prgn>aptitude</prgn>, and <prgn>dselect</prgn>.)
4704 Since <tt>Depends</tt> only places requirements on the order in
4705 which packages are configured, packages in an installation run
4706 are usually all unpacked first and all configured later.
4708 This approach makes dependency resolution easier. If two
4709 packages A and B are being upgraded, the installed package A
4710 depends on exactly the installed package B, and the new
4711 package A depends on exactly the new package B (a common
4712 situation when upgrading shared libraries and their
4713 corresponding development packages), satisfying the
4714 dependencies at every stage of the upgrade would be
4715 impossible. This relaxed restriction means that both new
4716 packages can be unpacked together and then configured in their
4722 If there is a circular dependency among packages being installed
4723 or removed, installation or removal order honoring the
4724 dependency order is impossible, requiring the dependency loop be
4725 broken at some point and the dependency requirements violated
4726 for at least one package. Packages involved in circular
4727 dependencies may not be able to rely on their dependencies being
4728 configured before they themselves are configured, depending on
4729 which side of the break of the circular dependency loop they
4730 happen to be on. If one of the packages in the loop has
4731 no <prgn>postinst</prgn> script, then the cycle will be broken
4732 at that package; this ensures that all <prgn>postinst</prgn>
4733 scripts are run with their dependencies properly configured if
4734 this is possible. Otherwise the breaking point is arbitrary.
4735 Packages should therefore avoid circular dependencies where
4736 possible, particularly if they have <prgn>postinst</prgn>
4741 The meaning of the five dependency fields is as follows:
4743 <tag><tt>Depends</tt></tag>
4746 This declares an absolute dependency. A package will
4747 not be configured unless all of the packages listed in
4748 its <tt>Depends</tt> field have been correctly
4749 configured (unless there is a circular dependency as
4754 The <tt>Depends</tt> field should be used if the
4755 depended-on package is required for the depending
4756 package to provide a significant amount of
4761 The <tt>Depends</tt> field should also be used if the
4762 <prgn>postinst</prgn> or <prgn>prerm</prgn> scripts
4763 require the depended-on package to be unpacked or
4764 configured in order to run. In the case of <tt>postinst
4765 configure</tt>, the depended-on packages will be unpacked
4766 and configured first. (If both packages are involved in a
4767 dependency loop, this might not work as expected; see the
4768 explanation a few paragraphs back.) In the case
4769 of <prgn>prerm</prgn> or other <prgn>postinst</prgn>
4770 actions, the package dependencies will normally be at
4771 least unpacked, but they may be only "Half-Installed" if a
4772 previous upgrade of the dependency failed.
4776 Finally, the <tt>Depends</tt> field should be used if the
4777 depended-on package is needed by the <prgn>postrm</prgn>
4778 script to fully clean up after the package removal. There
4779 is no guarantee that package dependencies will be
4780 available when <prgn>postrm</prgn> is run, but the
4781 depended-on package is more likely to be available if the
4782 package declares a dependency (particularly in the case
4783 of <tt>postrm remove</tt>). The <prgn>postrm</prgn>
4784 script must gracefully skip actions that require a
4785 dependency if that dependency isn't available.
4789 <tag><tt>Recommends</tt></tag>
4792 This declares a strong, but not absolute, dependency.
4796 The <tt>Recommends</tt> field should list packages
4797 that would be found together with this one in all but
4798 unusual installations.
4802 <tag><tt>Suggests</tt></tag>
4804 This is used to declare that one package may be more
4805 useful with one or more others. Using this field
4806 tells the packaging system and the user that the
4807 listed packages are related to this one and can
4808 perhaps enhance its usefulness, but that installing
4809 this one without them is perfectly reasonable.
4812 <tag><tt>Enhances</tt></tag>
4814 This field is similar to Suggests but works in the
4815 opposite direction. It is used to declare that a
4816 package can enhance the functionality of another
4820 <tag><tt>Pre-Depends</tt></tag>
4823 This field is like <tt>Depends</tt>, except that it
4824 also forces <prgn>dpkg</prgn> to complete installation
4825 of the packages named before even starting the
4826 installation of the package which declares the
4827 pre-dependency, as follows:
4831 When a package declaring a pre-dependency is about to
4832 be <em>unpacked</em> the pre-dependency can be
4833 satisfied if the depended-on package is either fully
4834 configured, <em>or even if</em> the depended-on
4835 package(s) are only unpacked or in the "Half-Configured"
4836 state, provided that they have been configured
4837 correctly at some point in the past (and not removed
4838 or partially removed since). In this case, both the
4839 previously-configured and currently unpacked or
4840 "Half-Configured" versions must satisfy any version
4841 clause in the <tt>Pre-Depends</tt> field.
4845 When the package declaring a pre-dependency is about to
4846 be <em>configured</em>, the pre-dependency will be treated
4847 as a normal <tt>Depends</tt>. It will be considered
4848 satisfied only if the depended-on package has been
4849 correctly configured. However, unlike
4850 with <tt>Depends</tt>, <tt>Pre-Depends</tt> does not
4851 permit circular dependencies to be broken. If a circular
4852 dependency is encountered while attempting to honor
4853 <tt>Pre-Depends</tt>, the installation will be aborted.
4857 <tt>Pre-Depends</tt> are also required if the
4858 <prgn>preinst</prgn> script depends on the named package.
4859 It is best to avoid this situation if possible.
4863 <tt>Pre-Depends</tt> should be used sparingly,
4864 preferably only by packages whose premature upgrade or
4865 installation would hamper the ability of the system to
4866 continue with any upgrade that might be in progress.
4873 When selecting which level of dependency to use you should
4874 consider how important the depended-on package is to the
4875 functionality of the one declaring the dependency. Some
4876 packages are composed of components of varying degrees of
4877 importance. Such a package should list using
4878 <tt>Depends</tt> the package(s) which are required by the
4879 more important components. The other components'
4880 requirements may be mentioned as Suggestions or
4881 Recommendations, as appropriate to the components' relative
4887 <heading>Packages which break other packages - <tt>Breaks</tt></heading>
4890 When one binary package declares that it breaks another,
4891 <prgn>dpkg</prgn> will refuse to allow the package which
4892 declares <tt>Breaks</tt> to be unpacked unless the broken
4893 package is deconfigured first, and it will refuse to
4894 allow the broken package to be reconfigured.
4898 A package will not be regarded as causing breakage merely
4899 because its configuration files are still installed; it must
4900 be at least "Half-Installed".
4904 A special exception is made for packages which declare that
4905 they break their own package name or a virtual package which
4906 they provide (see below): this does not count as a real
4911 Normally a <tt>Breaks</tt> entry will have an "earlier than"
4912 version clause; such a <tt>Breaks</tt> is introduced in the
4913 version of an (implicit or explicit) dependency which violates
4914 an assumption or reveals a bug in earlier versions of the broken
4915 package, or which takes over a file from earlier versions of the
4916 package named in <tt>Breaks</tt>. This use of <tt>Breaks</tt>
4917 will inform higher-level package management tools that the
4918 broken package must be upgraded before the new one.
4922 If the breaking package also overwrites some files from the
4923 older package, it should use <tt>Replaces</tt> to ensure this
4924 goes smoothly. See <ref id="replaces"> for a full discussion
4925 of taking over files from other packages, including how to
4926 use <tt>Breaks</tt> in those cases.
4930 Many of the cases where <tt>Breaks</tt> should be used were
4931 previously handled with <tt>Conflicts</tt>
4932 because <tt>Breaks</tt> did not yet exist.
4933 Many <tt>Conflicts</tt> fields should now be <tt>Breaks</tt>.
4934 See <ref id="conflicts"> for more information about the
4939 <sect id="conflicts">
4940 <heading>Conflicting binary packages - <tt>Conflicts</tt></heading>
4943 When one binary package declares a conflict with another using
4944 a <tt>Conflicts</tt> field, <prgn>dpkg</prgn> will refuse to
4945 allow them to be unpacked on the system at the same time. This
4946 is a stronger restriction than <tt>Breaks</tt>, which prevents
4947 the broken package from being configured while the breaking
4948 package is in the "Unpacked" state but allows both packages to
4949 be unpacked at the same time.
4953 If one package is to be unpacked, the other must be removed
4954 first. If the package being unpacked is marked as replacing
4955 (see <ref id="replaces">, but note that <tt>Breaks</tt> should
4956 normally be used in this case) the one on the system, or the one
4957 on the system is marked as deselected, or both packages are
4958 marked <tt>Essential</tt>, then <prgn>dpkg</prgn> will
4959 automatically remove the package which is causing the conflict.
4960 Otherwise, it will halt the installation of the new package with
4961 an error. This mechanism is specifically designed to produce an
4962 error when the installed package is <tt>Essential</tt>, but the
4967 A package will not cause a conflict merely because its
4968 configuration files are still installed; it must be at least
4973 A special exception is made for packages which declare a
4974 conflict with their own package name, or with a virtual
4975 package which they provide (see below): this does not
4976 prevent their installation, and allows a package to conflict
4977 with others providing a replacement for it. You use this
4978 feature when you want the package in question to be the only
4979 package providing some feature.
4983 Normally, <tt>Breaks</tt> should be used instead
4984 of <tt>Conflicts</tt> since <tt>Conflicts</tt> imposes a
4985 stronger restriction on the ordering of package installation or
4986 upgrade and can make it more difficult for the package manager
4987 to find a correct solution to an upgrade or installation
4988 problem. <tt>Breaks</tt> should be used
4990 <item>when moving a file from one package to another (see
4991 <ref id="replaces">),</item>
4992 <item>when splitting a package (a special case of the previous
4994 <item>when the breaking package exposes a bug in or interacts
4995 badly with particular versions of the broken
4998 <tt>Conflicts</tt> should be used
5000 <item>when two packages provide the same file and will
5001 continue to do so,</item>
5002 <item>in conjunction with <tt>Provides</tt> when only one
5003 package providing a given virtual facility may be unpacked
5004 at a time (see <ref id="virtual">),</item>
5005 <item>in other cases where one must prevent simultaneous
5006 installation of two packages for reasons that are ongoing
5007 (not fixed in a later version of one of the packages) or
5008 that must prevent both packages from being unpacked at the
5009 same time, not just configured.</item>
5011 Be aware that adding <tt>Conflicts</tt> is normally not the best
5012 solution when two packages provide the same files. Depending on
5013 the reason for that conflict, using alternatives or renaming the
5014 files is often a better approach. See, for
5015 example, <ref id="binaries">.
5019 Neither <tt>Breaks</tt> nor <tt>Conflicts</tt> should be used
5020 unless two packages cannot be installed at the same time or
5021 installing them both causes one of them to be broken or
5022 unusable. Having similar functionality or performing the same
5023 tasks as another package is not sufficient reason to
5024 declare <tt>Breaks</tt> or <tt>Conflicts</tt> with that package.
5028 A <tt>Conflicts</tt> entry may have an "earlier than" version
5029 clause if the reason for the conflict is corrected in a later
5030 version of one of the packages. However, normally the presence
5031 of an "earlier than" version clause is a sign
5032 that <tt>Breaks</tt> should have been used instead. An "earlier
5033 than" version clause in <tt>Conflicts</tt>
5034 prevents <prgn>dpkg</prgn> from upgrading or installing the
5035 package which declares such a conflict until the upgrade or
5036 removal of the conflicted-with package has been completed, which
5037 is a strong restriction.
5041 <sect id="virtual"><heading>Virtual packages - <tt>Provides</tt>
5045 As well as the names of actual ("concrete") packages, the
5046 package relationship fields <tt>Depends</tt>,
5047 <tt>Recommends</tt>, <tt>Suggests</tt>, <tt>Enhances</tt>,
5048 <tt>Pre-Depends</tt>, <tt>Breaks</tt>, <tt>Conflicts</tt>,
5049 <tt>Build-Depends</tt>, <tt>Build-Depends-Indep</tt>,
5050 <tt>Build-Conflicts</tt> and <tt>Build-Conflicts-Indep</tt>
5051 may mention "virtual packages".
5055 A <em>virtual package</em> is one which appears in the
5056 <tt>Provides</tt> control field of another package. The effect
5057 is as if the package(s) which provide a particular virtual
5058 package name had been listed by name everywhere the virtual
5059 package name appears. (See also <ref id="virtual_pkg">)
5063 If there are both concrete and virtual packages of the same
5064 name, then the dependency may be satisfied (or the conflict
5065 caused) by either the concrete package with the name in
5066 question or any other concrete package which provides the
5067 virtual package with the name in question. This is so that,
5068 for example, supposing we have
5069 <example compact="compact">
5072 </example> and someone else releases an enhanced version of
5073 the <tt>bar</tt> package they can say:
5074 <example compact="compact">
5078 and the <tt>bar-plus</tt> package will now also satisfy the
5079 dependency for the <tt>foo</tt> package.
5083 If a relationship field has a version number attached, only real
5084 packages will be considered to see whether the relationship is
5085 satisfied (or the prohibition violated, for a conflict or
5086 breakage). In other words, if a version number is specified,
5087 this is a request to ignore all <tt>Provides</tt> for that
5088 package name and consider only real packages. The package
5089 manager will assume that a package providing that virtual
5090 package is not of the "right" version. A <tt>Provides</tt>
5091 field may not contain version numbers, and the version number of
5092 the concrete package which provides a particular virtual package
5093 will not be considered when considering a dependency on or
5094 conflict with the virtual package name.<footnote>
5095 It is possible that a future release of <prgn>dpkg</prgn> may
5096 add the ability to specify a version number for each virtual
5097 package it provides. This feature is not yet present,
5098 however, and is expected to be used only infrequently.
5103 To specify which of a set of real packages should be the default
5104 to satisfy a particular dependency on a virtual package, list
5105 the real package as an alternative before the virtual one.
5109 If the virtual package represents a facility that can only be
5110 provided by one real package at a time, such as
5111 the <package>mail-transport-agent</package> virtual package that
5112 requires installation of a binary that would conflict with all
5113 other providers of that virtual package (see
5114 <ref id="mail-transport-agents">), all packages providing that
5115 virtual package should also declare a conflict with it
5116 using <tt>Conflicts</tt>. This will ensure that at most one
5117 provider of that virtual package is unpacked or installed at a
5122 <sect id="replaces"><heading>Overwriting files and replacing
5123 packages - <tt>Replaces</tt></heading>
5126 Packages can declare in their control file that they should
5127 overwrite files in certain other packages, or completely replace
5128 other packages. The <tt>Replaces</tt> control field has these
5129 two distinct purposes.
5132 <sect1><heading>Overwriting files in other packages</heading>
5135 It is usually an error for a package to contain files which
5136 are on the system in another package. However, if the
5137 overwriting package declares that it <tt>Replaces</tt> the one
5138 containing the file being overwritten, then <prgn>dpkg</prgn>
5139 will replace the file from the old package with that from the
5140 new. The file will no longer be listed as "owned" by the old
5141 package and will be taken over by the new package.
5142 Normally, <tt>Breaks</tt> should be used in conjunction
5143 with <tt>Replaces</tt>.<footnote>
5144 To see why <tt>Breaks</tt> is normally needed in addition
5145 to <tt>Replaces</tt>, consider the case of a file in the
5146 package <package>foo</package> being taken over by the
5147 package <package>foo-data</package>.
5148 <tt>Replaces</tt> will allow <package>foo-data</package> to
5149 be installed and take over that file. However,
5150 without <tt>Breaks</tt>, nothing
5151 requires <package>foo</package> to be upgraded to a newer
5152 version that knows it does not include that file and instead
5153 depends on <package>foo-data</package>. Nothing would
5154 prevent the new <package>foo-data</package> package from
5155 being installed and then removed, removing the file that it
5156 took over from <package>foo</package>. After that
5157 operation, the package manager would think the system was in
5158 a consistent state, but the <package>foo</package> package
5159 would be missing one of its files.
5164 For example, if a package <package>foo</package> is split
5165 into <package>foo</package> and <package>foo-data</package>
5166 starting at version 1.2-3, <package>foo-data</package> would
5168 <example compact="compact">
5169 Replaces: foo (<< 1.2-3)
5170 Breaks: foo (<< 1.2-3)
5172 in its control file. The new version of the
5173 package <package>foo</package> would normally have the field
5174 <example compact="compact">
5175 Depends: foo-data (>= 1.2-3)
5177 (or possibly <tt>Recommends</tt> or even <tt>Suggests</tt> if
5178 the files moved into <package>foo-data</package> are not
5179 required for normal operation).
5183 If a package is completely replaced in this way, so that
5184 <prgn>dpkg</prgn> does not know of any files it still
5185 contains, it is considered to have "disappeared". It will
5186 be marked as not wanted on the system (selected for
5187 removal) and not installed. Any <tt>conffile</tt>s
5188 details noted for the package will be ignored, as they
5189 will have been taken over by the overwriting package. The
5190 package's <prgn>postrm</prgn> script will be run with a
5191 special argument to allow the package to do any final
5192 cleanup required. See <ref id="mscriptsinstact">.
5194 Replaces is a one way relationship. You have to install
5195 the replacing package after the replaced package.
5200 For this usage of <tt>Replaces</tt>, virtual packages (see
5201 <ref id="virtual">) are not considered when looking at a
5202 <tt>Replaces</tt> field. The packages declared as being
5203 replaced must be mentioned by their real names.
5207 This usage of <tt>Replaces</tt> only takes effect when both
5208 packages are at least partially on the system at once. It is
5209 not relevant if the packages conflict unless the conflict has
5214 <sect1><heading>Replacing whole packages, forcing their
5218 Second, <tt>Replaces</tt> allows the packaging system to
5219 resolve which package should be removed when there is a
5220 conflict (see <ref id="conflicts">). This usage only takes
5221 effect when the two packages <em>do</em> conflict, so that the
5222 two usages of this field do not interfere with each other.
5226 In this situation, the package declared as being replaced
5227 can be a virtual package, so for example, all mail
5228 transport agents (MTAs) would have the following fields in
5229 their control files:
5230 <example compact="compact">
5231 Provides: mail-transport-agent
5232 Conflicts: mail-transport-agent
5233 Replaces: mail-transport-agent
5235 ensuring that only one MTA can be unpacked at any one
5236 time. See <ref id="virtual"> for more information about this
5241 <sect id="sourcebinarydeps">
5242 <heading>Relationships between source and binary packages -
5243 <tt>Build-Depends</tt>, <tt>Build-Depends-Indep</tt>,
5244 <tt>Build-Conflicts</tt>, <tt>Build-Conflicts-Indep</tt>
5248 Source packages that require certain binary packages to be
5249 installed or absent at the time of building the package
5250 can declare relationships to those binary packages.
5254 This is done using the <tt>Build-Depends</tt>,
5255 <tt>Build-Depends-Indep</tt>, <tt>Build-Conflicts</tt> and
5256 <tt>Build-Conflicts-Indep</tt> control fields.
5260 Build-dependencies on "build-essential" binary packages can be
5261 omitted. Please see <ref id="pkg-relations"> for more information.
5265 The dependencies and conflicts they define must be satisfied
5266 (as defined earlier for binary packages) in order to invoke
5267 the targets in <tt>debian/rules</tt>, as follows:<footnote>
5269 There is no Build-Depends-Arch; this role is essentially
5270 met with Build-Depends. Anyone building the
5271 <tt>build-indep</tt> and <tt>binary-indep</tt> targets is
5272 assumed to be building the whole package, and therefore
5273 installation of all build dependencies is required.
5276 The autobuilders use <tt>dpkg-buildpackage -B</tt>, which
5277 calls <tt>build</tt>, not <tt>build-arch</tt> since it does
5278 not yet know how to check for its existence, and
5279 <tt>binary-arch</tt>. The purpose of the original split
5280 between <tt>Build-Depends</tt> and
5281 <tt>Build-Depends-Indep</tt> was so that the autobuilders
5282 wouldn't need to install extra packages needed only for the
5283 binary-indep targets. But without a build-arch/build-indep
5284 split, this didn't work, since most of the work is done in
5285 the build target, not in the binary target.
5289 <tag><tt>clean</tt>, <tt>build-arch</tt>, and
5290 <tt>binary-arch</tt></tag>
5292 Only the <tt>Build-Depends</tt> and <tt>Build-Conflicts</tt>
5293 fields must be satisfied when these targets are invoked.
5295 <tag><tt>build</tt>, <tt>build-indep</tt>, <tt>binary</tt>,
5296 and <tt>binary-indep</tt></tag>
5298 The <tt>Build-Depends</tt>, <tt>Build-Conflicts</tt>,
5299 <tt>Build-Depends-Indep</tt>, and
5300 <tt>Build-Conflicts-Indep</tt> fields must be satisfied when
5301 these targets are invoked.
5309 <chapt id="sharedlibs"><heading>Shared libraries</heading>
5312 Packages containing shared libraries must be constructed with
5313 a little care to make sure that the shared library is always
5314 available. This is especially important for packages whose
5315 shared libraries are vitally important, such as the C library
5316 (currently <tt>libc6</tt>).
5320 This section deals only with public shared libraries: shared
5321 libraries that are placed in directories searched by the dynamic
5322 linker by default or which are intended to be linked against
5323 normally and possibly used by other, independent packages. Shared
5324 libraries that are internal to a particular package or that are
5325 only loaded as dynamic modules are not covered by this section and
5326 are not subject to its requirements.
5330 A shared library is identified by the <tt>SONAME</tt> attribute
5331 stored in its dynamic section. When a binary is linked against a
5332 shared library, the <tt>SONAME</tt> of the shared library is
5333 recorded in the binary's <tt>NEEDED</tt> section so that the
5334 dynamic linker knows that library must be loaded at runtime. The
5335 shared library file's full name (which usually contains additional
5336 version information not needed in the <tt>SONAME</tt>) is
5337 therefore normally not referenced directly. Instead, the shared
5338 library is loaded by its <tt>SONAME</tt>, which exists on the file
5339 system as a symlink pointing to the full name of the shared
5340 library. This symlink must be provided by the
5341 package. <ref id="sharedlibs-runtime"> describes how to do this.
5343 This is a convention of shared library versioning, but not a
5344 requirement. Some libraries use the <tt>SONAME</tt> as the full
5345 library file name instead and therefore do not need a symlink.
5346 Most, however, encode additional information about
5347 backwards-compatible revisions as a minor version number in the
5348 file name. The <tt>SONAME</tt> itself only changes when
5349 binaries linked with the earlier version of the shared library
5350 may no longer work, but the filename may change with each
5351 release of the library. See <ref id="sharedlibs-runtime"> for
5357 When linking a binary or another shared library against a shared
5358 library, the <tt>SONAME</tt> for that shared library is not yet
5359 known. Instead, the shared library is found by looking for a file
5360 matching the library name with <tt>.so</tt> appended. This file
5361 exists on the file system as a symlink pointing to the shared
5366 Shared libraries are normally split into several binary packages.
5367 The <tt>SONAME</tt> symlink is installed by the runtime shared
5368 library package, and the bare <tt>.so</tt> symlink is installed in
5369 the development package since it's only used when linking binaries
5370 or shared libraries. However, there are some exceptions for
5371 unusual shared libraries or for shared libraries that are also
5372 loaded as dynamic modules by other programs.
5376 This section is primarily concerned with how the separation of
5377 shared libraries into multiple packages should be done and how
5378 dependencies on and between shared library binary packages are
5379 managed in Debian. <ref id="libraries"> should be read in
5380 conjunction with this section and contains additional rules for
5381 the files contained in the shared library packages.
5384 <sect id="sharedlibs-runtime">
5385 <heading>Run-time shared libraries</heading>
5388 The run-time shared library must be placed in a package
5389 whose name changes whenever the <tt>SONAME</tt> of the shared
5390 library changes. This allows several versions of the shared
5391 library to be installed at the same time, allowing installation
5392 of the new version of the shared library without immediately
5393 breaking binaries that depend on the old version. Normally, the
5394 run-time shared library and its <tt>SONAME</tt> symlink should
5395 be placed in a package named
5396 <package><var>libraryname</var><var>soversion</var></package>,
5397 where <var>soversion</var> is the version number in
5398 the <tt>SONAME</tt> of the shared library.
5399 See <ref id="shlibs"> for detailed information on how to
5400 determine this version. Alternatively, if it would be confusing
5401 to directly append <var>soversion</var>
5402 to <var>libraryname</var> (if, for example, <var>libraryname</var>
5403 itself ends in a number), you should use
5404 <package><var>libraryname</var>-<var>soversion</var></package>
5409 If you have several shared libraries built from the same source
5410 tree, you may lump them all together into a single shared
5411 library package provided that all of their <tt>SONAME</tt>s will
5412 always change together. Be aware that this is not normally the
5413 case, and if the <tt>SONAME</tt>s do not change together,
5414 upgrading such a merged shared library package will be
5415 unnecessarily difficult because of file conflicts with the old
5416 version of the package. When in doubt, always split shared
5417 library packages so that each binary package installs a single
5422 Every time the shared library ABI changes in a way that may
5423 break binaries linked against older versions of the shared
5424 library, the <tt>SONAME</tt> of the library and the
5425 corresponding name for the binary package containing the runtime
5426 shared library should change. Normally, this means
5427 the <tt>SONAME</tt> should change any time an interface is
5428 removed from the shared library or the signature of an interface
5429 (the number of parameters or the types of parameters that it
5430 takes, for example) is changed. This practice is vital to
5431 allowing clean upgrades from older versions of the package and
5432 clean transitions between the old ABI and new ABI without having
5433 to upgrade every affected package simultaneously.
5437 The <tt>SONAME</tt> and binary package name need not, and indeed
5438 normally should not, change if new interfaces are added but none
5439 are removed or changed, since this will not break binaries
5440 linked against the old shared library. Correct versioning of
5441 dependencies on the newer shared library by binaries that use
5442 the new interfaces is handled via
5443 the <qref id="sharedlibs-shlibdeps"><tt>shlibs</tt>
5444 system</qref> or via symbols files (see
5445 <manref name="deb-symbols" section="5">).
5449 The package should install the shared libraries under
5450 their normal names. For example, the <package>libgdbm3</package>
5451 package should install <file>libgdbm.so.3.0.0</file> as
5452 <file>/usr/lib/libgdbm.so.3.0.0</file>. The files should not be
5453 renamed or re-linked by any <prgn>prerm</prgn> or
5454 <prgn>postrm</prgn> scripts; <prgn>dpkg</prgn> will take care
5455 of renaming things safely without affecting running programs,
5456 and attempts to interfere with this are likely to lead to
5461 Shared libraries should not be installed executable, since
5462 the dynamic linker does not require this and trying to
5463 execute a shared library usually results in a core dump.
5467 The run-time library package should include the symbolic link for
5468 the <tt>SONAME</tt> that <prgn>ldconfig</prgn> would create for
5469 the shared libraries. For example,
5470 the <package>libgdbm3</package> package should include a symbolic
5471 link from <file>/usr/lib/libgdbm.so.3</file> to
5472 <file>libgdbm.so.3.0.0</file>. This is needed so that the dynamic
5473 linker (for example <prgn>ld.so</prgn> or
5474 <prgn>ld-linux.so.*</prgn>) can find the library between the
5475 time that <prgn>dpkg</prgn> installs it and the time that
5476 <prgn>ldconfig</prgn> is run in the <prgn>postinst</prgn>
5478 The package management system requires the library to be
5479 placed before the symbolic link pointing to it in the
5480 <file>.deb</file> file. This is so that when
5481 <prgn>dpkg</prgn> comes to install the symlink
5482 (overwriting the previous symlink pointing at an older
5483 version of the library), the new shared library is already
5484 in place. In the past, this was achieved by creating the
5485 library in the temporary packaging directory before
5486 creating the symlink. Unfortunately, this was not always
5487 effective, since the building of the tar file in the
5488 <file>.deb</file> depended on the behavior of the underlying
5489 file system. Some file systems (such as reiserfs) reorder
5490 the files so that the order of creation is forgotten.
5491 Since version 1.7.0, <prgn>dpkg</prgn>
5492 reorders the files itself as necessary when building a
5493 package. Thus it is no longer important to concern
5494 oneself with the order of file creation.
5498 <sect1 id="ldconfig">
5499 <heading><tt>ldconfig</tt></heading>
5502 Any package installing shared libraries in one of the default
5503 library directories of the dynamic linker (which are currently
5504 <file>/usr/lib</file> and <file>/lib</file>) or a directory that is
5505 listed in <file>/etc/ld.so.conf</file><footnote>
5506 These are currently <file>/usr/local/lib</file> plus
5507 directories under <file>/lib</file> and <file>/usr/lib</file>
5508 matching the multiarch triplet for the system architecture.
5510 must use <prgn>ldconfig</prgn> to update the shared library
5515 The package maintainer scripts must only call
5516 <prgn>ldconfig</prgn> under these circumstances:
5517 <list compact="compact">
5518 <item>When the <prgn>postinst</prgn> script is run with a
5519 first argument of <tt>configure</tt>, the script must call
5520 <prgn>ldconfig</prgn>, and may optionally invoke
5521 <prgn>ldconfig</prgn> at other times.
5523 <item>When the <prgn>postrm</prgn> script is run with a
5524 first argument of <tt>remove</tt>, the script should call
5525 <prgn>ldconfig</prgn>.
5530 During install or upgrade, the preinst is called before
5531 the new files are unpacked, so calling "ldconfig" is
5532 pointless. The preinst of an existing package can also be
5533 called if an upgrade fails. However, this happens during
5534 the critical time when a shared libs may exist on-disk
5535 under a temporary name. Thus, it is dangerous and
5536 forbidden by current policy to call "ldconfig" at this
5541 When a package is installed or upgraded, "postinst
5542 configure" runs after the new files are safely on-disk.
5543 Since it is perfectly safe to invoke ldconfig
5544 unconditionally in a postinst, it is OK for a package to
5545 simply put ldconfig in its postinst without checking the
5546 argument. The postinst can also be called to recover from
5547 a failed upgrade. This happens before any new files are
5548 unpacked, so there is no reason to call "ldconfig" at this
5553 For a package that is being removed, prerm is
5554 called with all the files intact, so calling ldconfig is
5555 useless. The other calls to "prerm" happen in the case of
5556 upgrade at a time when all the files of the old package
5557 are on-disk, so again calling "ldconfig" is pointless.
5561 postrm, on the other hand, is called with the "remove"
5562 argument just after the files are removed, so this is
5563 the proper time to call "ldconfig" to notify the system
5564 of the fact that the shared libraries from the package
5565 are removed. The postrm can be called at several other
5566 times. At the time of "postrm purge", "postrm
5567 abort-install", or "postrm abort-upgrade", calling
5568 "ldconfig" is useless because the shared lib files are
5569 not on-disk. However, when "postrm" is invoked with
5570 arguments "upgrade", "failed-upgrade", or "disappear", a
5571 shared lib may exist on-disk under a temporary filename.
5579 <sect id="sharedlibs-support-files">
5580 <heading>Shared library support files</heading>
5583 If your package contains files whose names do not change with
5584 each change in the library shared object version, you must not
5585 put them in the shared library package. Otherwise, several
5586 versions of the shared library cannot be installed at the same
5587 time without filename clashes, making upgrades and transitions
5588 unnecessarily difficult.
5592 It is recommended that supporting files and run-time support
5593 programs that do not need to be invoked manually by users, but
5594 are nevertheless required for the package to function, be placed
5595 (if they are binary) in a subdirectory of <file>/usr/lib</file>,
5596 preferably under <file>/usr/lib/</file><var>package-name</var>.
5597 If the program or file is architecture independent, the
5598 recommendation is for it to be placed in a subdirectory of
5599 <file>/usr/share</file> instead, preferably under
5600 <file>/usr/share/</file><var>package-name</var>. Following the
5601 <var>package-name</var> naming convention ensures that the file
5602 names change when the shared object version changes.
5606 Run-time support programs that use the shared library but are
5607 not required for the library to function or files used by the
5608 shared library that can be used by any version of the shared
5609 library package should instead be put in a separate package.
5610 This package might typically be named
5611 <package><var>libraryname</var>-tools</package>; note the
5612 absence of the <var>soversion</var> in the package name.
5616 Files and support programs only useful when compiling software
5617 against the library should be included in the development
5618 package for the library.<footnote>
5619 For example, a <file><var>package-name</var>-config</file>
5620 script or <package>pkg-config</package> configuration files.
5625 <sect id="sharedlibs-static">
5626 <heading>Static libraries</heading>
5629 The static library (<file><var>libraryname.a</var></file>)
5630 is usually provided in addition to the shared version.
5631 It is placed into the development package (see below).
5635 In some cases, it is acceptable for a library to be
5636 available in static form only; these cases include:
5638 <item>libraries for languages whose shared library support
5639 is immature or unstable</item>
5640 <item>libraries whose interfaces are in flux or under
5641 development (commonly the case when the library's
5642 major version number is zero, or where the ABI breaks
5643 across patchlevels)</item>
5644 <item>libraries which are explicitly intended to be
5645 available only in static form by their upstream
5650 <sect id="sharedlibs-dev">
5651 <heading>Development files</heading>
5654 If there are development files associated with a shared library,
5655 the source package needs to generate a binary development package
5656 named <package><var>libraryname</var><var>soversion</var>-dev</package>,
5657 or if you prefer only to support one development version at a
5658 time, <package><var>libraryname</var>-dev</package>. Installing
5659 the development package must result in installation of all the
5660 development files necessary for compiling programs against that
5661 shared library.<footnote>
5662 This wording allows the development files to be split into
5663 several packages, such as a separate architecture-independent
5664 <package><var>libraryname</var>-headers</package>, provided that
5665 the development package depends on all the required additional
5671 In case several development versions of a library exist, you may
5672 need to use <prgn>dpkg</prgn>'s Conflicts mechanism (see
5673 <ref id="conflicts">) to ensure that the user only installs one
5674 development version at a time (as different development versions are
5675 likely to have the same header files in them, which would cause a
5676 filename clash if both were unpacked).
5680 The development package should contain a symlink for the associated
5681 shared library without a version number. For example, the
5682 <package>libgdbm-dev</package> package should include a symlink
5683 from <file>/usr/lib/libgdbm.so</file> to
5684 <file>libgdbm.so.3.0.0</file>. This symlink is needed by the linker
5685 (<prgn>ld</prgn>) when compiling packages, as it will only look for
5686 <file>libgdbm.so</file> when compiling dynamically.
5690 If the package provides Ada Library Information
5691 (<file>*.ali</file>) files for use with GNAT, these files must be
5692 installed read-only (mode 0444) so that GNAT will not attempt to
5693 recompile them. This overrides the normal file mode requirements
5694 given in <ref id="permissions-owners">.
5698 <sect id="sharedlibs-intradeps">
5699 <heading>Dependencies between the packages of the same library</heading>
5702 Typically the development version should have an exact
5703 version dependency on the runtime library, to make sure that
5704 compilation and linking happens correctly. The
5705 <tt>${binary:Version}</tt> substitution variable can be
5706 useful for this purpose.
5708 Previously, <tt>${Source-Version}</tt> was used, but its name
5709 was confusing and it has been deprecated since dpkg 1.13.19.
5714 <sect id="sharedlibs-shlibdeps">
5715 <heading>Dependencies between the library and other packages -
5716 the <tt>shlibs</tt> system</heading>
5719 If a package contains a binary or library which links to a
5720 shared library, we must ensure that when the package is
5721 installed on the system, all of the libraries needed are
5722 also installed. This requirement led to the creation of the
5723 <tt>shlibs</tt> system, which is very simple in its design:
5724 any package which <em>provides</em> a shared library also
5725 provides information on the package dependencies required to
5726 ensure the presence of this library, and any package which
5727 <em>uses</em> a shared library uses this information to
5728 determine the dependencies it requires. The files which
5729 contain the mapping from shared libraries to the necessary
5730 dependency information are called <file>shlibs</file> files.
5734 When a package is built which contains any shared libraries, it
5735 must provide a <file>shlibs</file> file for other packages to
5736 use. When a package is built which contains any shared
5737 libraries or compiled binaries, it must run
5738 <qref id="pkg-dpkg-shlibdeps"><prgn>dpkg-shlibdeps</prgn></qref>
5739 on these to determine the libraries used and hence the
5740 dependencies needed by this package.<footnote>
5742 <prgn>dpkg-shlibdeps</prgn> will use a program
5743 like <prgn>objdump</prgn> or <prgn>readelf</prgn> to find
5744 the libraries directly needed by the binaries or shared
5745 libraries in the package.
5749 We say that a binary <tt>foo</tt> <em>directly</em> uses
5750 a library <tt>libbar</tt> if it is explicitly linked
5751 with that library (that is, the library is listed in the ELF
5752 <tt>NEEDED</tt> attribute, caused by adding <tt>-lbar</tt>
5753 to the link line when the binary is created). Other
5754 libraries that are needed by <tt>libbar</tt> are linked
5755 <em>indirectly</em> to <tt>foo</tt>, and the dynamic
5756 linker will load them automatically when it loads
5757 <tt>libbar</tt>. A package should depend on the libraries
5758 it directly uses, but not the libraries it indirectly uses.
5759 The dependencies for those libraries will automatically pull
5760 in the other libraries.
5764 A good example of where this helps is the following. We
5765 could update <tt>libimlib</tt> with a new version that
5766 supports a new graphics format called dgf (but retaining the
5767 same major version number) and depends on <tt>libdgf</tt>.
5768 If we used <prgn>ldd</prgn> to add dependencies for every
5769 library directly or indirectly linked with a binary, every
5770 package that uses <tt>libimlib</tt> would need to be
5771 recompiled so it would also depend on <tt>libdgf</tt> or it
5772 wouldn't run due to missing symbols. Since dependencies are
5773 only added based on ELF <tt>NEEDED</tt> attribute, packages
5774 using <tt>libimlib</tt> can rely on <tt>libimlib</tt> itself
5775 having the dependency on <tt>libdgf</tt> and so they would
5776 not need rebuilding.
5782 In the following sections, we will first describe where the
5783 various <tt>shlibs</tt> files are to be found, then how to
5784 use <prgn>dpkg-shlibdeps</prgn>, and finally the <tt>shlibs</tt>
5785 file format and how to create them if your package contains a
5790 <heading>The <tt>shlibs</tt> files present on the system</heading>
5793 There are several places where <tt>shlibs</tt> files are
5794 found. The following list gives them in the order in which
5796 <qref id="pkg-dpkg-shlibdeps"><prgn>dpkg-shlibdeps</prgn></qref>.
5797 (The first one which gives the required information is used.)
5803 <p><file>debian/shlibs.local</file></p>
5806 This lists overrides for this package. This file should
5807 normally not be used, but may be needed temporarily in
5808 unusual situations to work around bugs in other packages,
5809 or in unusual cases where the normally declared dependency
5810 information in the installed <file>shlibs</file> file for
5811 a library cannot be used. This file overrides information
5812 obtained from any other source.
5817 <p><file>/etc/dpkg/shlibs.override</file></p>
5820 This lists global overrides. This list is normally
5821 empty. It is maintained by the local system
5827 <p><file>DEBIAN/shlibs</file> files in the "build directory"</p>
5830 When packages are being built,
5831 any <file>debian/shlibs</file> files are copied into the
5832 control information file area of the temporary build
5833 directory and given the name <file>shlibs</file>. These
5834 files give details of any shared libraries included in the
5835 same package.<footnote>
5836 An example may help here. Let us say that the source
5837 package <tt>foo</tt> generates two binary
5838 packages, <tt>libfoo2</tt> and <tt>foo-runtime</tt>.
5839 When building the binary packages, the two packages are
5840 created in the directories <file>debian/libfoo2</file>
5841 and <file>debian/foo-runtime</file> respectively.
5842 (<file>debian/tmp</file> could be used instead of one of
5843 these.) Since <tt>libfoo2</tt> provides the
5844 <tt>libfoo</tt> shared library, it will require a
5845 <tt>shlibs</tt> file, which will be installed in
5846 <file>debian/libfoo2/DEBIAN/shlibs</file>, eventually to
5847 become <file>/var/lib/dpkg/info/libfoo2.shlibs</file>.
5848 When <prgn>dpkg-shlibdeps</prgn> is run on the
5849 executable <file>debian/foo-runtime/usr/bin/foo-prog</file>,
5851 the <file>debian/libfoo2/DEBIAN/shlibs</file> file to
5852 determine whether <tt>foo-prog</tt>'s library
5853 dependencies are satisfied by any of the libraries
5854 provided by <tt>libfoo2</tt>. For this reason,
5855 <prgn>dpkg-shlibdeps</prgn> must only be run once all of
5856 the individual binary packages' <tt>shlibs</tt> files
5857 have been installed into the build directory.
5863 <p><file>/var/lib/dpkg/info/*.shlibs</file></p>
5866 These are the <file>shlibs</file> files corresponding to
5867 all of the packages installed on the system, and are
5868 maintained by the relevant package maintainers.
5873 <p><file>/etc/dpkg/shlibs.default</file></p>
5876 This file lists any shared libraries whose packages
5877 have failed to provide correct <file>shlibs</file> files.
5878 It was used when the <file>shlibs</file> setup was first
5879 introduced, but it is now normally empty. It is
5880 maintained by the <tt>dpkg</tt> maintainer.
5888 <heading>How to use <prgn>dpkg-shlibdeps</prgn> and the
5889 <file>shlibs</file> files</heading>
5893 <qref id="pkg-dpkg-shlibdeps"><prgn>dpkg-shlibdeps</prgn></qref>
5894 into your <file>debian/rules</file> file. If your package
5895 contains only compiled binaries and libraries (but no scripts),
5896 you can use a command such as:
5897 <example compact="compact">
5898 dpkg-shlibdeps debian/tmp/usr/bin/* debian/tmp/usr/sbin/* \
5899 debian/tmp/usr/lib/*
5901 Otherwise, you will need to explicitly list the compiled
5902 binaries and libraries.<footnote>
5903 If you are using <tt>debhelper</tt>, the
5904 <prgn>dh_shlibdeps</prgn> program will do this work for you.
5905 It will also correctly handle multi-binary packages.
5910 This command puts the dependency information into the
5911 <file>debian/substvars</file> file, which is then used by
5912 <prgn>dpkg-gencontrol</prgn>. You will need to place a
5913 <tt>${shlibs:Depends}</tt> variable in the <tt>Depends</tt>
5914 field in the control file for this to work.
5918 If you have multiple binary packages, you will need to call
5919 <prgn>dpkg-shlibdeps</prgn> on each one which contains
5920 compiled libraries or binaries. In such a case, you will
5921 need to use the <tt>-T</tt> option to the <tt>dpkg</tt>
5922 utilities to specify a different <file>substvars</file> file.
5926 If you are creating a udeb for use in the Debian Installer,
5927 you will need to specify that <prgn>dpkg-shlibdeps</prgn>
5928 should use the dependency line of type <tt>udeb</tt> by
5929 adding the <tt>-tudeb</tt> option<footnote>
5930 <prgn>dh_shlibdeps</prgn> from the <tt>debhelper</tt> suite
5931 will automatically add this option if it knows it is
5933 </footnote>. If there is no dependency line of
5934 type <tt>udeb</tt> in the <file>shlibs</file>
5935 file, <prgn>dpkg-shlibdeps</prgn> will fall back to the regular
5940 For more details on <prgn>dpkg-shlibdeps</prgn>, please see
5941 <ref id="pkg-dpkg-shlibdeps"> and
5942 <manref name="dpkg-shlibdeps" section="1">.
5947 <heading>The <file>shlibs</file> File Format</heading>
5950 Each <file>shlibs</file> file has the same format. Lines
5951 beginning with <tt>#</tt> are considered to be comments and
5952 are ignored. Each line is of the form:
5953 <example compact="compact">
5954 [<var>type</var>: ]<var>library-name</var> <var>soname-version</var> <var>dependencies ...</var>
5959 We will explain this by reference to the example of the
5960 <tt>zlib1g</tt> package, which (at the time of writing)
5961 installs the shared library <file>/usr/lib/libz.so.1.1.3</file>.
5965 <var>type</var> is an optional element that indicates the type
5966 of package for which the line is valid. The only type currently
5967 in use is <tt>udeb</tt>. The colon and space after the type are
5972 <var>library-name</var> is the name of the shared library,
5973 in this case <tt>libz</tt>. (This must match the name part
5974 of the soname, see below.)
5978 <var>soname-version</var> is the version part of the soname of
5979 the library. The soname is the thing that must exactly match
5980 for the library to be recognized by the dynamic linker, and is
5982 <tt><var>name</var>.so.<var>major-version</var></tt>, in our
5983 example, <tt>libz.so.1</tt>.<footnote>
5984 This can be determined using the command
5985 <example compact="compact">
5986 objdump -p /usr/lib/libz.so.1.1.3 | grep SONAME
5989 The version part is the part which comes after
5990 <tt>.so.</tt>, so in our case, it is <tt>1</tt>. The soname may
5991 instead be of the form
5992 <tt><var>name</var>-<var>major-version</var>.so</tt>, such
5993 as <tt>libdb-4.8.so</tt>, in which case the name would
5994 be <tt>libdb</tt> and the version would be <tt>4.8</tt>.
5998 <var>dependencies</var> has the same syntax as a dependency
5999 field in a binary package control file. It should give
6000 details of which packages are required to satisfy a binary
6001 built against the version of the library contained in the
6002 package. See <ref id="depsyntax"> for details.
6006 In our example, if the first version of the <tt>zlib1g</tt>
6007 package which contained a minor number of at least
6008 <tt>1.3</tt> was <var>1:1.1.3-1</var>, then the
6009 <tt>shlibs</tt> entry for this library could say:
6010 <example compact="compact">
6011 libz 1 zlib1g (>= 1:1.1.3)
6013 The version-specific dependency is to avoid warnings from
6014 the dynamic linker about using older shared libraries with
6019 As zlib1g also provides a udeb containing the shared library,
6020 there would also be a second line:
6021 <example compact="compact">
6022 udeb: libz 1 zlib1g-udeb (>= 1:1.1.3)
6028 <heading>Providing a <file>shlibs</file> file</heading>
6031 If your package provides a shared library, you need to create
6032 a <file>shlibs</file> file following the format described above.
6033 It is usual to call this file <file>debian/shlibs</file> (but if
6034 you have multiple binary packages, you might want to call it
6035 <file>debian/shlibs.<var>package</var></file> instead). Then
6036 let <file>debian/rules</file> install it in the control
6037 information file area:
6038 <example compact="compact">
6039 install -m644 debian/shlibs debian/tmp/DEBIAN
6041 or, in the case of a multi-binary package:
6042 <example compact="compact">
6043 install -m644 debian/shlibs.<var>package</var> debian/<var>package</var>/DEBIAN/shlibs
6045 An alternative way of doing this is to create the
6046 <file>shlibs</file> file in the control information file area
6047 directly from <file>debian/rules</file> without using
6048 a <file>debian/shlibs</file> file at all,<footnote>
6049 This is what <prgn>dh_makeshlibs</prgn> in
6050 the <package>debhelper</package> suite does. If your package
6051 also has a udeb that provides a shared
6052 library, <prgn>dh_makeshlibs</prgn> can automatically generate
6053 the <tt>udeb:</tt> lines if you specify the name of the udeb
6054 with the <tt>--add-udeb</tt> option.
6056 since the <file>debian/shlibs</file> file itself is ignored by
6057 <prgn>dpkg-shlibdeps</prgn>.
6061 As <prgn>dpkg-shlibdeps</prgn> reads the
6062 <file>DEBIAN/shlibs</file> files in all of the binary packages
6063 being built from this source package, all of the
6064 <file>DEBIAN/shlibs</file> files should be installed before
6065 <prgn>dpkg-shlibdeps</prgn> is called on any of the binary
6073 <chapt id="opersys"><heading>The Operating System</heading>
6076 <heading>File system hierarchy</heading>
6080 <heading>File System Structure</heading>
6083 The location of all installed files and directories must
6084 comply with the Filesystem Hierarchy Standard (FHS),
6085 version 2.3, with the exceptions noted below, and except
6086 where doing so would violate other terms of Debian
6087 Policy. The following exceptions to the FHS apply:
6092 The optional rules related to user specific
6093 configuration files for applications are stored in
6094 the user's home directory are relaxed. It is
6095 recommended that such files start with the
6096 '<tt>.</tt>' character (a "dot file"), and if an
6097 application needs to create more than one dot file
6098 then the preferred placement is in a subdirectory
6099 with a name starting with a '.' character, (a "dot
6100 directory"). In this case it is recommended the
6101 configuration files not start with the '.'
6107 The requirement for amd64 to use <file>/lib64</file>
6108 for 64 bit binaries is removed.
6113 The requirement for object files, internal binaries, and
6114 libraries, including <file>libc.so.*</file>, to be located
6115 directly under <file>/lib{,32}</file> and
6116 <file>/usr/lib{,32}</file> is amended, permitting files
6117 to instead be installed to
6118 <file>/lib/<var>triplet</var></file> and
6119 <file>/usr/lib/<var>triplet</var></file>, where
6120 <tt><var>triplet</var></tt> is the value returned by
6121 <tt>dpkg-architecture -qDEB_HOST_GNU_TYPE</tt> for the
6122 architecture of the package. Packages may <em>not</em>
6123 install files to any <var>triplet</var> path other
6124 than the one matching the architecture of that package;
6125 for instance, an <tt>Architecture: amd64</tt> package
6126 containing 32-bit x86 libraries may not install these
6127 libraries to <file>/usr/lib/i486-linux-gnu</file>.
6129 This is necessary in order to reserve the directories for
6130 use in cross-installation of library packages from other
6131 architectures, as part of the planned deployment of
6136 Applications may also use a single subdirectory under
6137 <file>/usr/lib/<var>triplet</var></file>.
6140 The execution time linker/loader, ld*, must still be made
6141 available in the existing location under /lib or /lib64
6142 since this is part of the ELF ABI for the architecture.
6147 The requirement that
6148 <file>/usr/local/share/man</file> be "synonymous"
6149 with <file>/usr/local/man</file> is relaxed to a
6154 The requirement that windowmanagers with a single
6155 configuration file call it <file>system.*wmrc</file>
6156 is removed, as is the restriction that the window
6157 manager subdirectory be named identically to the
6158 window manager name itself.
6163 The requirement that boot manager configuration
6164 files live in <file>/etc</file>, or at least are
6165 symlinked there, is relaxed to a recommendation.
6170 The following directories in the root filesystem are
6171 additionally allowed: <file>/sys</file> and
6172 <file>/selinux</file>. <footnote>These directories
6173 are used as mount points to mount virtual filesystems
6174 to get access to kernel information.</footnote>
6179 On GNU/Hurd systems, the following additional
6180 directories are allowed in the root
6181 filesystem: <file>/hurd</file>
6182 and <file>/servers</file>.<footnote>
6183 These directories are used to store translators and as
6184 a set of standard names for mount points,
6193 The version of this document referred here can be
6194 found in the <tt>debian-policy</tt> package or on <url
6195 id="http://www.debian.org/doc/packaging-manuals/fhs/"
6196 name="FHS (Debian copy)"> alongside this manual (or, if
6197 you have the <package>debian-policy</package> installed,
6199 id="file:///usr/share/doc/debian-policy/fhs/" name="FHS
6200 (local copy)">). The
6201 latest version, which may be a more recent version, may
6203 <url id="http://www.pathname.com/fhs/" name="FHS (upstream)">.
6204 Specific questions about following the standard may be
6205 asked on the <tt>debian-devel</tt> mailing list, or
6206 referred to the FHS mailing list (see the
6207 <url id="http://www.pathname.com/fhs/" name="FHS web site"> for
6213 <heading>Site-specific programs</heading>
6216 As mandated by the FHS, packages must not place any
6217 files in <file>/usr/local</file>, either by putting them in
6218 the file system archive to be unpacked by <prgn>dpkg</prgn>
6219 or by manipulating them in their maintainer scripts.
6223 However, the package may create empty directories below
6224 <file>/usr/local</file> so that the system administrator knows
6225 where to place site-specific files. These are not
6226 directories <em>in</em> <file>/usr/local</file>, but are
6227 children of directories in <file>/usr/local</file>. These
6228 directories (<file>/usr/local/*/dir/</file>)
6229 should be removed on package removal if they are
6234 Note that this applies only to
6235 directories <em>below</em> <file>/usr/local</file>,
6236 not <em>in</em> <file>/usr/local</file>. Packages must
6237 not create sub-directories in the
6238 directory <file>/usr/local</file> itself, except those
6239 listed in FHS, section 4.5. However, you may create
6240 directories below them as you wish. You must not remove
6241 any of the directories listed in 4.5, even if you created
6246 Since <file>/usr/local</file> can be mounted read-only from a
6247 remote server, these directories must be created and
6248 removed by the <prgn>postinst</prgn> and <prgn>prerm</prgn>
6249 maintainer scripts and not be included in the
6250 <file>.deb</file> archive. These scripts must not fail if
6251 either of these operations fail.
6255 For example, the <tt>emacsen-common</tt> package could
6256 contain something like
6257 <example compact="compact">
6258 if [ ! -e /usr/local/share/emacs ]
6260 if mkdir /usr/local/share/emacs 2>/dev/null
6262 chown root:staff /usr/local/share/emacs
6263 chmod 2775 /usr/local/share/emacs
6267 in its <prgn>postinst</prgn> script, and
6268 <example compact="compact">
6269 rmdir /usr/local/share/emacs/site-lisp 2>/dev/null || true
6270 rmdir /usr/local/share/emacs 2>/dev/null || true
6272 in the <prgn>prerm</prgn> script. (Note that this form is
6273 used to ensure that if the script is interrupted, the
6274 directory <file>/usr/local/share/emacs</file> will still be
6279 If you do create a directory in <file>/usr/local</file> for
6280 local additions to a package, you should ensure that
6281 settings in <file>/usr/local</file> take precedence over the
6282 equivalents in <file>/usr</file>.
6286 However, because <file>/usr/local</file> and its contents are
6287 for exclusive use of the local administrator, a package
6288 must not rely on the presence or absence of files or
6289 directories in <file>/usr/local</file> for normal operation.
6293 The <file>/usr/local</file> directory itself and all the
6294 subdirectories created by the package should (by default) have
6295 permissions 2775 (group-writable and set-group-id) and be
6296 owned by <tt>root:staff</tt>.
6301 <heading>The system-wide mail directory</heading>
6303 The system-wide mail directory
6304 is <file>/var/mail</file>. This directory is part of the
6305 base system and should not be owned by any particular mail
6306 agents. The use of the old
6307 location <file>/var/spool/mail</file> is deprecated, even
6308 though the spool may still be physically located there.
6314 <heading>Users and groups</heading>
6317 <heading>Introduction</heading>
6319 The Debian system can be configured to use either plain or
6324 Some user ids (UIDs) and group ids (GIDs) are reserved
6325 globally for use by certain packages. Because some
6326 packages need to include files which are owned by these
6327 users or groups, or need the ids compiled into binaries,
6328 these ids must be used on any Debian system only for the
6329 purpose for which they are allocated. This is a serious
6330 restriction, and we should avoid getting in the way of
6331 local administration policies. In particular, many sites
6332 allocate users and/or local system groups starting at 100.
6336 Apart from this we should have dynamically allocated ids,
6337 which should by default be arranged in some sensible
6338 order, but the behavior should be configurable.
6342 Packages other than <tt>base-passwd</tt> must not modify
6343 <file>/etc/passwd</file>, <file>/etc/shadow</file>,
6344 <file>/etc/group</file> or <file>/etc/gshadow</file>.
6349 <heading>UID and GID classes</heading>
6351 The UID and GID numbers are divided into classes as
6357 Globally allocated by the Debian project, the same
6358 on every Debian system. These ids will appear in
6359 the <file>passwd</file> and <file>group</file> files of all
6360 Debian systems, new ids in this range being added
6361 automatically as the <tt>base-passwd</tt> package is
6366 Packages which need a single statically allocated
6367 uid or gid should use one of these; their
6368 maintainers should ask the <tt>base-passwd</tt>
6376 Dynamically allocated system users and groups.
6377 Packages which need a user or group, but can have
6378 this user or group allocated dynamically and
6379 differently on each system, should use <tt>adduser
6380 --system</tt> to create the group and/or user.
6381 <prgn>adduser</prgn> will check for the existence of
6382 the user or group, and if necessary choose an unused
6383 id based on the ranges specified in
6384 <file>adduser.conf</file>.
6388 <tag>1000-59999:</tag>
6391 Dynamically allocated user accounts. By default
6392 <prgn>adduser</prgn> will choose UIDs and GIDs for
6393 user accounts in this range, though
6394 <file>adduser.conf</file> may be used to modify this
6399 <tag>60000-64999:</tag>
6402 Globally allocated by the Debian project, but only
6403 created on demand. The ids are allocated centrally
6404 and statically, but the actual accounts are only
6405 created on users' systems on demand.
6409 These ids are for packages which are obscure or
6410 which require many statically-allocated ids. These
6411 packages should check for and create the accounts in
6412 <file>/etc/passwd</file> or <file>/etc/group</file> (using
6413 <prgn>adduser</prgn> if it has this facility) if
6414 necessary. Packages which are likely to require
6415 further allocations should have a "hole" left after
6416 them in the allocation, to give them room to
6421 <tag>65000-65533:</tag>
6429 User <tt>nobody</tt>. The corresponding gid refers
6430 to the group <tt>nogroup</tt>.
6437 <tt>(uid_t)(-1) == (gid_t)(-1)</tt> <em>must
6438 not</em> be used, because it is the error return
6447 <sect id="sysvinit">
6448 <heading>System run levels and <file>init.d</file> scripts</heading>
6450 <sect1 id="/etc/init.d">
6451 <heading>Introduction</heading>
6454 The <file>/etc/init.d</file> directory contains the scripts
6455 executed by <prgn>init</prgn> at boot time and when the
6456 init state (or "runlevel") is changed (see <manref
6457 name="init" section="8">).
6461 There are at least two different, yet functionally
6462 equivalent, ways of handling these scripts. For the sake
6463 of simplicity, this document describes only the symbolic
6464 link method. However, it must not be assumed by maintainer
6465 scripts that this method is being used, and any automated
6466 manipulation of the various runlevel behaviors by
6467 maintainer scripts must be performed using
6468 <prgn>update-rc.d</prgn> as described below and not by
6469 manually installing or removing symlinks. For information
6470 on the implementation details of the other method,
6471 implemented in the <tt>file-rc</tt> package, please refer
6472 to the documentation of that package.
6476 These scripts are referenced by symbolic links in the
6477 <file>/etc/rc<var>n</var>.d</file> directories. When changing
6478 runlevels, <prgn>init</prgn> looks in the directory
6479 <file>/etc/rc<var>n</var>.d</file> for the scripts it should
6480 execute, where <tt><var>n</var></tt> is the runlevel that
6481 is being changed to, or <tt>S</tt> for the boot-up
6486 The names of the links all have the form
6487 <file>S<var>mm</var><var>script</var></file> or
6488 <file>K<var>mm</var><var>script</var></file> where
6489 <var>mm</var> is a two-digit number and <var>script</var>
6490 is the name of the script (this should be the same as the
6491 name of the actual script in <file>/etc/init.d</file>).
6495 When <prgn>init</prgn> changes runlevel first the targets
6496 of the links whose names start with a <tt>K</tt> are
6497 executed, each with the single argument <tt>stop</tt>,
6498 followed by the scripts prefixed with an <tt>S</tt>, each
6499 with the single argument <tt>start</tt>. (The links are
6500 those in the <file>/etc/rc<var>n</var>.d</file> directory
6501 corresponding to the new runlevel.) The <tt>K</tt> links
6502 are responsible for killing services and the <tt>S</tt>
6503 link for starting services upon entering the runlevel.
6507 For example, if we are changing from runlevel 2 to
6508 runlevel 3, init will first execute all of the <tt>K</tt>
6509 prefixed scripts it finds in <file>/etc/rc3.d</file>, and then
6510 all of the <tt>S</tt> prefixed scripts in that directory.
6511 The links starting with <tt>K</tt> will cause the
6512 referred-to file to be executed with an argument of
6513 <tt>stop</tt>, and the <tt>S</tt> links with an argument
6518 The two-digit number <var>mm</var> is used to determine
6519 the order in which to run the scripts: low-numbered links
6520 have their scripts run first. For example, the
6521 <tt>K20</tt> scripts will be executed before the
6522 <tt>K30</tt> scripts. This is used when a certain service
6523 must be started before another. For example, the name
6524 server <prgn>bind</prgn> might need to be started before
6525 the news server <prgn>inn</prgn> so that <prgn>inn</prgn>
6526 can set up its access lists. In this case, the script
6527 that starts <prgn>bind</prgn> would have a lower number
6528 than the script that starts <prgn>inn</prgn> so that it
6530 <example compact="compact">
6537 The two runlevels 0 (halt) and 6 (reboot) are slightly
6538 different. In these runlevels, the links with an
6539 <tt>S</tt> prefix are still called after those with a
6540 <tt>K</tt> prefix, but they too are called with the single
6541 argument <tt>stop</tt>.
6545 <sect1 id="writing-init">
6546 <heading>Writing the scripts</heading>
6549 Packages that include daemons for system services should
6550 place scripts in <file>/etc/init.d</file> to start or stop
6551 services at boot time or during a change of runlevel.
6552 These scripts should be named
6553 <file>/etc/init.d/<var>package</var></file>, and they should
6554 accept one argument, saying what to do:
6557 <tag><tt>start</tt></tag>
6558 <item>start the service,</item>
6560 <tag><tt>stop</tt></tag>
6561 <item>stop the service,</item>
6563 <tag><tt>restart</tt></tag>
6564 <item>stop and restart the service if it's already running,
6565 otherwise start the service</item>
6567 <tag><tt>reload</tt></tag>
6568 <item><p>cause the configuration of the service to be
6569 reloaded without actually stopping and restarting
6572 <tag><tt>force-reload</tt></tag>
6573 <item>cause the configuration to be reloaded if the
6574 service supports this, otherwise restart the
6578 The <tt>start</tt>, <tt>stop</tt>, <tt>restart</tt>, and
6579 <tt>force-reload</tt> options should be supported by all
6580 scripts in <file>/etc/init.d</file>, the <tt>reload</tt>
6585 The <file>init.d</file> scripts must ensure that they will
6586 behave sensibly (i.e., returning success and not starting
6587 multiple copies of a service) if invoked with <tt>start</tt>
6588 when the service is already running, or with <tt>stop</tt>
6589 when it isn't, and that they don't kill unfortunately-named
6590 user processes. The best way to achieve this is usually to
6591 use <prgn>start-stop-daemon</prgn> with the <tt>--oknodo</tt>
6596 Be careful of using <tt>set -e</tt> in <file>init.d</file>
6597 scripts. Writing correct <file>init.d</file> scripts requires
6598 accepting various error exit statuses when daemons are already
6599 running or already stopped without aborting
6600 the <file>init.d</file> script, and common <file>init.d</file>
6601 function libraries are not safe to call with <tt>set -e</tt>
6603 <tt>/lib/lsb/init-functions</tt>, which assists in writing
6604 LSB-compliant init scripts, may fail if <tt>set -e</tt> is
6605 in effect and echoing status messages to the console fails,
6607 </footnote>. For <tt>init.d</tt> scripts, it's often easier
6608 to not use <tt>set -e</tt> and instead check the result of
6609 each command separately.
6613 If a service reloads its configuration automatically (as
6614 in the case of <prgn>cron</prgn>, for example), the
6615 <tt>reload</tt> option of the <file>init.d</file> script
6616 should behave as if the configuration has been reloaded
6621 The <file>/etc/init.d</file> scripts must be treated as
6622 configuration files, either (if they are present in the
6623 package, that is, in the .deb file) by marking them as
6624 <tt>conffile</tt>s, or, (if they do not exist in the .deb)
6625 by managing them correctly in the maintainer scripts (see
6626 <ref id="config-files">). This is important since we want
6627 to give the local system administrator the chance to adapt
6628 the scripts to the local system, e.g., to disable a
6629 service without de-installing the package, or to specify
6630 some special command line options when starting a service,
6631 while making sure their changes aren't lost during the next
6636 These scripts should not fail obscurely when the
6637 configuration files remain but the package has been
6638 removed, as configuration files remain on the system after
6639 the package has been removed. Only when <prgn>dpkg</prgn>
6640 is executed with the <tt>--purge</tt> option will
6641 configuration files be removed. In particular, as the
6642 <file>/etc/init.d/<var>package</var></file> script itself is
6643 usually a <tt>conffile</tt>, it will remain on the system
6644 if the package is removed but not purged. Therefore, you
6645 should include a <tt>test</tt> statement at the top of the
6647 <example compact="compact">
6648 test -f <var>program-executed-later-in-script</var> || exit 0
6653 Often there are some variables in the <file>init.d</file>
6654 scripts whose values control the behavior of the scripts,
6655 and which a system administrator is likely to want to
6656 change. As the scripts themselves are frequently
6657 <tt>conffile</tt>s, modifying them requires that the
6658 administrator merge in their changes each time the package
6659 is upgraded and the <tt>conffile</tt> changes. To ease
6660 the burden on the system administrator, such configurable
6661 values should not be placed directly in the script.
6662 Instead, they should be placed in a file in
6663 <file>/etc/default</file>, which typically will have the same
6664 base name as the <file>init.d</file> script. This extra file
6665 should be sourced by the script when the script runs. It
6666 must contain only variable settings and comments in SUSv3
6667 <prgn>sh</prgn> format. It may either be a
6668 <tt>conffile</tt> or a configuration file maintained by
6669 the package maintainer scripts. See <ref id="config-files">
6674 To ensure that vital configurable values are always
6675 available, the <file>init.d</file> script should set default
6676 values for each of the shell variables it uses, either
6677 before sourcing the <file>/etc/default/</file> file or
6678 afterwards using something like the <tt>:
6679 ${VAR:=default}</tt> syntax. Also, the <file>init.d</file>
6680 script must behave sensibly and not fail if the
6681 <file>/etc/default</file> file is deleted.
6685 <file>/var/run</file> and <file>/var/lock</file> may be mounted
6686 as temporary filesystems<footnote>
6687 For example, using the <tt>RAMRUN</tt> and <tt>RAMLOCK</tt>
6688 options in <file>/etc/default/rcS</file>.
6689 </footnote>, so the <file>init.d</file> scripts must handle this
6690 correctly. This will typically amount to creating any required
6691 subdirectories dynamically when the <file>init.d</file> script
6692 is run, rather than including them in the package and relying on
6693 <prgn>dpkg</prgn> to create them.
6698 <heading>Interfacing with the initscript system</heading>
6701 Maintainers should use the abstraction layer provided by
6702 the <prgn>update-rc.d</prgn> and <prgn>invoke-rc.d</prgn>
6703 programs to deal with initscripts in their packages'
6704 scripts such as <prgn>postinst</prgn>, <prgn>prerm</prgn>
6705 and <prgn>postrm</prgn>.
6709 Directly managing the /etc/rc?.d links and directly
6710 invoking the <file>/etc/init.d/</file> initscripts should
6711 be done only by packages providing the initscript
6712 subsystem (such as <prgn>sysv-rc</prgn> and
6713 <prgn>file-rc</prgn>).
6717 <heading>Managing the links</heading>
6720 The program <prgn>update-rc.d</prgn> is provided for
6721 package maintainers to arrange for the proper creation and
6722 removal of <file>/etc/rc<var>n</var>.d</file> symbolic links,
6723 or their functional equivalent if another method is being
6724 used. This may be used by maintainers in their packages'
6725 <prgn>postinst</prgn> and <prgn>postrm</prgn> scripts.
6729 You must not include any <file>/etc/rc<var>n</var>.d</file>
6730 symbolic links in the actual archive or manually create or
6731 remove the symbolic links in maintainer scripts; you must
6732 use the <prgn>update-rc.d</prgn> program instead. (The
6733 former will fail if an alternative method of maintaining
6734 runlevel information is being used.) You must not include
6735 the <file>/etc/rc<var>n</var>.d</file> directories themselves
6736 in the archive either. (Only the <tt>sysvinit</tt>
6741 By default <prgn>update-rc.d</prgn> will start services in
6742 each of the multi-user state runlevels (2, 3, 4, and 5)
6743 and stop them in the halt runlevel (0), the single-user
6744 runlevel (1) and the reboot runlevel (6). The system
6745 administrator will have the opportunity to customize
6746 runlevels by simply adding, moving, or removing the
6747 symbolic links in <file>/etc/rc<var>n</var>.d</file> if
6748 symbolic links are being used, or by modifying
6749 <file>/etc/runlevel.conf</file> if the <tt>file-rc</tt> method
6754 To get the default behavior for your package, put in your
6755 <prgn>postinst</prgn> script
6756 <example compact="compact">
6757 update-rc.d <var>package</var> defaults
6759 and in your <prgn>postrm</prgn>
6760 <example compact="compact">
6761 if [ "$1" = purge ]; then
6762 update-rc.d <var>package</var> remove
6764 </example>. Note that if your package changes runlevels
6765 or priority, you may have to remove and recreate the links,
6766 since otherwise the old links may persist. Refer to the
6767 documentation of <prgn>update-rc.d</prgn>.
6771 This will use a default sequence number of 20. If it does
6772 not matter when or in which order the <file>init.d</file>
6773 script is run, use this default. If it does, then you
6774 should talk to the maintainer of the <prgn>sysvinit</prgn>
6775 package or post to <tt>debian-devel</tt>, and they will
6776 help you choose a number.
6780 For more information about using <tt>update-rc.d</tt>,
6781 please consult its man page <manref name="update-rc.d"
6787 <heading>Running initscripts</heading>
6789 The program <prgn>invoke-rc.d</prgn> is provided to make
6790 it easier for package maintainers to properly invoke an
6791 initscript, obeying runlevel and other locally-defined
6792 constraints that might limit a package's right to start,
6793 stop and otherwise manage services. This program may be
6794 used by maintainers in their packages' scripts.
6798 The package maintainer scripts must use
6799 <prgn>invoke-rc.d</prgn> to invoke the
6800 <file>/etc/init.d/*</file> initscripts, instead of
6801 calling them directly.
6805 By default, <prgn>invoke-rc.d</prgn> will pass any
6806 action requests (start, stop, reload, restart...) to the
6807 <file>/etc/init.d</file> script, filtering out requests
6808 to start or restart a service out of its intended
6813 Most packages will simply need to change:
6814 <example compact="compact">/etc/init.d/<package>
6815 <action></example> in their <prgn>postinst</prgn>
6816 and <prgn>prerm</prgn> scripts to:
6817 <example compact="compact">
6818 if which invoke-rc.d >/dev/null 2>&1; then
6819 invoke-rc.d <var>package</var> <action>
6821 /etc/init.d/<var>package</var> <action>
6827 A package should register its initscript services using
6828 <prgn>update-rc.d</prgn> before it tries to invoke them
6829 using <prgn>invoke-rc.d</prgn>. Invocation of
6830 unregistered services may fail.
6834 For more information about using
6835 <prgn>invoke-rc.d</prgn>, please consult its man page
6836 <manref name="invoke-rc.d" section="8">.
6842 <heading>Boot-time initialization</heading>
6845 There used to be another directory, <file>/etc/rc.boot</file>,
6846 which contained scripts which were run once per machine
6847 boot. This has been deprecated in favour of links from
6848 <file>/etc/rcS.d</file> to files in <file>/etc/init.d</file> as
6849 described in <ref id="/etc/init.d">. Packages must not
6850 place files in <file>/etc/rc.boot</file>.
6855 <heading>Example</heading>
6858 An example on which you can base your
6859 <file>/etc/init.d</file> scripts is found in
6860 <file>/etc/init.d/skeleton</file>.
6867 <heading>Console messages from <file>init.d</file> scripts</heading>
6870 This section describes the formats to be used for messages
6871 written to standard output by the <file>/etc/init.d</file>
6872 scripts. The intent is to improve the consistency of
6873 Debian's startup and shutdown look and feel. For this
6874 reason, please look very carefully at the details. We want
6875 the messages to have the same format in terms of wording,
6876 spaces, punctuation and case of letters.
6880 Here is a list of overall rules that should be used for
6881 messages generated by <file>/etc/init.d</file> scripts.
6887 The message should fit in one line (fewer than 80
6888 characters), start with a capital letter and end with
6889 a period (<tt>.</tt>) and line feed (<tt>"\n"</tt>).
6893 If the script is performing some time consuming task in
6894 the background (not merely starting or stopping a
6895 program, for instance), an ellipsis (three dots:
6896 <tt>...</tt>) should be output to the screen, with no
6897 leading or tailing whitespace or line feeds.
6901 The messages should appear as if the computer is telling
6902 the user what it is doing (politely :-), but should not
6903 mention "it" directly. For example, instead of:
6904 <example compact="compact">
6905 I'm starting network daemons: nfsd mountd.
6907 the message should say
6908 <example compact="compact">
6909 Starting network daemons: nfsd mountd.
6916 <tt>init.d</tt> script should use the following standard
6917 message formats for the situations enumerated below.
6923 <p>When daemons are started</p>
6926 If the script starts one or more daemons, the output
6927 should look like this (a single line, no leading
6929 <example compact="compact">
6930 Starting <var>description</var>: <var>daemon-1</var> ... <var>daemon-n</var>.
6932 The <var>description</var> should describe the
6933 subsystem the daemon or set of daemons are part of,
6934 while <var>daemon-1</var> up to <var>daemon-n</var>
6935 denote each daemon's name (typically the file name of
6940 For example, the output of <file>/etc/init.d/lpd</file>
6942 <example compact="compact">
6943 Starting printer spooler: lpd.
6948 This can be achieved by saying
6949 <example compact="compact">
6950 echo -n "Starting printer spooler: lpd"
6951 start-stop-daemon --start --quiet --exec /usr/sbin/lpd
6954 in the script. If there are more than one daemon to
6955 start, the output should look like this:
6956 <example compact="compact">
6957 echo -n "Starting remote file system services:"
6958 echo -n " nfsd"; start-stop-daemon --start --quiet nfsd
6959 echo -n " mountd"; start-stop-daemon --start --quiet mountd
6960 echo -n " ugidd"; start-stop-daemon --start --quiet ugidd
6963 This makes it possible for the user to see what is
6964 happening and when the final daemon has been started.
6965 Care should be taken in the placement of white spaces:
6966 in the example above the system administrators can
6967 easily comment out a line if they don't want to start
6968 a specific daemon, while the displayed message still
6974 <p>When a system parameter is being set</p>
6977 If you have to set up different system parameters
6978 during the system boot, you should use this format:
6979 <example compact="compact">
6980 Setting <var>parameter</var> to "<var>value</var>".
6985 You can use a statement such as the following to get
6987 <example compact="compact">
6988 echo "Setting DNS domainname to \"$domainname\"."
6993 Note that the same symbol (<tt>"</tt>) <!-- " --> is used
6994 for the left and right quotation marks. A grave accent
6995 (<tt>`</tt>) is not a quote character; neither is an
6996 apostrophe (<tt>'</tt>).
7001 <p>When a daemon is stopped or restarted</p>
7004 When you stop or restart a daemon, you should issue a
7005 message identical to the startup message, except that
7006 <tt>Starting</tt> is replaced with <tt>Stopping</tt>
7007 or <tt>Restarting</tt> respectively.
7011 For example, stopping the printer daemon will look like
7013 <example compact="compact">
7014 Stopping printer spooler: lpd.
7020 <p>When something is executed</p>
7023 There are several examples where you have to run a
7024 program at system startup or shutdown to perform a
7025 specific task, for example, setting the system's clock
7026 using <prgn>netdate</prgn> or killing all processes
7027 when the system shuts down. Your message should look
7029 <example compact="compact">
7030 Doing something very useful...done.
7032 You should print the <tt>done.</tt> immediately after
7033 the job has been completed, so that the user is
7034 informed why they have to wait. You can get this
7036 <example compact="compact">
7037 echo -n "Doing something very useful..."
7046 <p>When the configuration is reloaded</p>
7049 When a daemon is forced to reload its configuration
7050 files you should use the following format:
7051 <example compact="compact">
7052 Reloading <var>description</var> configuration...done.
7054 where <var>description</var> is the same as in the
7055 daemon starting message.
7063 <heading>Cron jobs</heading>
7066 Packages must not modify the configuration file
7067 <file>/etc/crontab</file>, and they must not modify the files in
7068 <file>/var/spool/cron/crontabs</file>.</p>
7071 If a package wants to install a job that has to be executed
7072 via cron, it should place a file with the name of the
7073 package in one or more of the following directories:
7074 <example compact="compact">
7080 As these directory names imply, the files within them are
7081 executed on an hourly, daily, weekly, or monthly basis,
7082 respectively. The exact times are listed in
7083 <file>/etc/crontab</file>.</p>
7086 All files installed in any of these directories must be
7087 scripts (e.g., shell scripts or Perl scripts) so that they
7088 can easily be modified by the local system administrator.
7089 In addition, they must be treated as configuration files.
7093 If a certain job has to be executed at some other frequency or
7094 at a specific time, the package should install a file
7095 <file>/etc/cron.d/<var>package</var></file>. This file uses the
7096 same syntax as <file>/etc/crontab</file> and is processed by
7097 <prgn>cron</prgn> automatically. The file must also be
7098 treated as a configuration file. (Note that entries in the
7099 <file>/etc/cron.d</file> directory are not handled by
7100 <prgn>anacron</prgn>. Thus, you should only use this
7101 directory for jobs which may be skipped if the system is not
7104 Unlike <file>crontab</file> files described in the IEEE Std
7105 1003.1-2008 (POSIX.1) available from
7106 <url id="http://www.opengroup.org/onlinepubs/9699919799/"
7107 name="The Open Group">, the files in
7108 <file>/etc/cron.d</file> and the file
7109 <file>/etc/crontab</file> have seven fields; namely:
7111 <item>Minute [0,59]</item>
7112 <item>Hour [0,23]</item>
7113 <item>Day of the month [1,31]</item>
7114 <item>Month of the year [1,12]</item>
7115 <item>Day of the week ([0,6] with 0=Sunday)</item>
7116 <item>Username</item>
7117 <item>Command to be run</item>
7119 Ranges of numbers are allowed. Ranges are two numbers
7120 separated with a hyphen. The specified range is inclusive.
7121 Lists are allowed. A list is a set of numbers (or ranges)
7122 separated by commas. Step values can be used in conjunction
7127 The scripts or <tt>crontab</tt> entries in these directories should
7128 check if all necessary programs are installed before they
7129 try to execute them. Otherwise, problems will arise when a
7130 package was removed but not purged since configuration files
7131 are kept on the system in this situation.
7135 Any <tt>cron</tt> daemon must provide
7136 <file>/usr/bin/crontab</file> and support normal
7137 <tt>crontab</tt> entries as specified in POSIX. The daemon
7138 must also support names for days and months, ranges, and
7139 step values. It has to support <file>/etc/crontab</file>,
7140 and correctly execute the scripts in
7141 <file>/etc/cron.d</file>. The daemon must also correctly
7143 <file>/etc/cron.{hourly,daily,weekly,monthly}</file>.
7148 <heading>Menus</heading>
7151 The Debian <tt>menu</tt> package provides a standard
7152 interface between packages providing applications and
7153 <em>menu programs</em> (either X window managers or
7154 text-based menu programs such as <prgn>pdmenu</prgn>).
7158 All packages that provide applications that need not be
7159 passed any special command line arguments for normal
7160 operation should register a menu entry for those
7161 applications, so that users of the <tt>menu</tt> package
7162 will automatically get menu entries in their window
7163 managers, as well in shells like <tt>pdmenu</tt>.
7167 Menu entries should follow the current menu policy.
7171 The menu policy can be found in the <tt>menu-policy</tt>
7172 files in the <tt>debian-policy</tt> package.
7173 It is also available from the Debian web mirrors at
7174 <tt><url name="/doc/packaging-manuals/menu-policy/"
7175 id="http://www.debian.org/doc/packaging-manuals/menu-policy/"></tt>.
7179 Please also refer to the <em>Debian Menu System</em>
7180 documentation that comes with the <package>menu</package>
7181 package for information about how to register your
7187 <heading>Multimedia handlers</heading>
7190 MIME (Multipurpose Internet Mail Extensions, RFCs 2045-2049)
7191 is a mechanism for encoding files and data streams and
7192 providing meta-information about them, in particular their
7193 type (e.g. audio or video) and format (e.g. PNG, HTML,
7198 Registration of MIME type handlers allows programs like mail
7199 user agents and web browsers to invoke these handlers to
7200 view, edit or display MIME types they don't support directly.
7204 Packages which provide the ability to view/show/play,
7205 compose, edit or print MIME types should register themselves
7206 as such following the current MIME support policy.
7210 The MIME support policy can be found in the <tt>mime-policy</tt>
7211 files in the <tt>debian-policy</tt> package.
7212 It is also available from the Debian web mirrors at
7213 <tt><url name="/doc/packaging-manuals/mime-policy/"
7214 id="http://www.debian.org/doc/packaging-manuals/mime-policy/"></tt>.
7220 <heading>Keyboard configuration</heading>
7223 To achieve a consistent keyboard configuration so that all
7224 applications interpret a keyboard event the same way, all
7225 programs in the Debian distribution must be configured to
7226 comply with the following guidelines.
7230 The following keys must have the specified interpretations:
7233 <tag><tt><--</tt></tag>
7234 <item>delete the character to the left of the cursor</item>
7236 <tag><tt>Delete</tt></tag>
7237 <item>delete the character to the right of the cursor</item>
7239 <tag><tt>Control+H</tt></tag>
7240 <item>emacs: the help prefix</item>
7243 The interpretation of any keyboard events should be
7244 independent of the terminal that is used, be it a virtual
7245 console, an X terminal emulator, an rlogin/telnet session,
7250 The following list explains how the different programs
7251 should be set up to achieve this:
7257 <tt><--</tt> generates <tt>KB_BackSpace</tt> in X.
7261 <tt>Delete</tt> generates <tt>KB_Delete</tt> in X.
7265 X translations are set up to make
7266 <tt>KB_Backspace</tt> generate ASCII DEL, and to make
7267 <tt>KB_Delete</tt> generate <tt>ESC [ 3 ~</tt> (this
7268 is the vt220 escape code for the "delete character"
7269 key). This must be done by loading the X resources
7270 using <prgn>xrdb</prgn> on all local X displays, not
7271 using the application defaults, so that the
7272 translation resources used correspond to the
7273 <prgn>xmodmap</prgn> settings.
7277 The Linux console is configured to make
7278 <tt><--</tt> generate DEL, and <tt>Delete</tt>
7279 generate <tt>ESC [ 3 ~</tt>.
7283 X applications are configured so that <tt><</tt>
7284 deletes left, and <tt>Delete</tt> deletes right. Motif
7285 applications already work like this.
7289 Terminals should have <tt>stty erase ^?</tt> .
7293 The <tt>xterm</tt> terminfo entry should have <tt>ESC
7294 [ 3 ~</tt> for <tt>kdch1</tt>, just as for
7295 <tt>TERM=linux</tt> and <tt>TERM=vt220</tt>.
7299 Emacs is programmed to map <tt>KB_Backspace</tt> or
7300 the <tt>stty erase</tt> character to
7301 <tt>delete-backward-char</tt>, and <tt>KB_Delete</tt>
7302 or <tt>kdch1</tt> to <tt>delete-forward-char</tt>, and
7303 <tt>^H</tt> to <tt>help</tt> as always.
7307 Other applications use the <tt>stty erase</tt>
7308 character and <tt>kdch1</tt> for the two delete keys,
7309 with ASCII DEL being "delete previous character" and
7310 <tt>kdch1</tt> being "delete character under
7318 This will solve the problem except for the following
7325 Some terminals have a <tt><--</tt> key that cannot
7326 be made to produce anything except <tt>^H</tt>. On
7327 these terminals Emacs help will be unavailable on
7328 <tt>^H</tt> (assuming that the <tt>stty erase</tt>
7329 character takes precedence in Emacs, and has been set
7330 correctly). <tt>M-x help</tt> or <tt>F1</tt> (if
7331 available) can be used instead.
7335 Some operating systems use <tt>^H</tt> for <tt>stty
7336 erase</tt>. However, modern telnet versions and all
7337 rlogin versions propagate <tt>stty</tt> settings, and
7338 almost all UNIX versions honour <tt>stty erase</tt>.
7339 Where the <tt>stty</tt> settings are not propagated
7340 correctly, things can be made to work by using
7341 <tt>stty</tt> manually.
7345 Some systems (including previous Debian versions) use
7346 <prgn>xmodmap</prgn> to arrange for both
7347 <tt><--</tt> and <tt>Delete</tt> to generate
7348 <tt>KB_Delete</tt>. We can change the behavior of
7349 their X clients using the same X resources that we use
7350 to do it for our own clients, or configure our clients
7351 using their resources when things are the other way
7352 around. On displays configured like this
7353 <tt>Delete</tt> will not work, but <tt><--</tt>
7358 Some operating systems have different <tt>kdch1</tt>
7359 settings in their <tt>terminfo</tt> database for
7360 <tt>xterm</tt> and others. On these systems the
7361 <tt>Delete</tt> key will not work correctly when you
7362 log in from a system conforming to our policy, but
7363 <tt><--</tt> will.
7370 <heading>Environment variables</heading>
7373 A program must not depend on environment variables to get
7374 reasonable defaults. (That's because these environment
7375 variables would have to be set in a system-wide
7376 configuration file like <file>/etc/profile</file>, which is not
7377 supported by all shells.)
7381 If a program usually depends on environment variables for its
7382 configuration, the program should be changed to fall back to
7383 a reasonable default configuration if these environment
7384 variables are not present. If this cannot be done easily
7385 (e.g., if the source code of a non-free program is not
7386 available), the program must be replaced by a small
7387 "wrapper" shell script which sets the environment variables
7388 if they are not already defined, and calls the original program.
7392 Here is an example of a wrapper script for this purpose:
7394 <example compact="compact">
7396 BAR=${BAR:-/var/lib/fubar}
7398 exec /usr/lib/foo/foo "$@"
7403 Furthermore, as <file>/etc/profile</file> is a configuration
7404 file of the <prgn>base-files</prgn> package, other packages must
7405 not put any environment variables or other commands into that
7410 <sect id="doc-base">
7411 <heading>Registering Documents using doc-base</heading>
7414 The <package>doc-base</package> package implements a
7415 flexible mechanism for handling and presenting
7416 documentation. The recommended practice is for every Debian
7417 package that provides online documentation (other than just
7418 manual pages) to register these documents with
7419 <package>doc-base</package> by installing a
7420 <package>doc-base</package> control file via the
7421 <prgn/install-docs/ script at installation time and
7422 de-register the manuals again when the package is removed.
7425 Please refer to the documentation that comes with the
7426 <package>doc-base</package> package for information and
7435 <heading>Files</heading>
7437 <sect id="binaries">
7438 <heading>Binaries</heading>
7441 Two different packages must not install programs with
7442 different functionality but with the same filenames. (The
7443 case of two programs having the same functionality but
7444 different implementations is handled via "alternatives" or
7445 the "Conflicts" mechanism. See <ref id="maintscripts"> and
7446 <ref id="conflicts"> respectively.) If this case happens,
7447 one of the programs must be renamed. The maintainers should
7448 report this to the <tt>debian-devel</tt> mailing list and
7449 try to find a consensus about which program will have to be
7450 renamed. If a consensus cannot be reached, <em>both</em>
7451 programs must be renamed.
7455 By default, when a package is being built, any binaries
7456 created should include debugging information, as well as
7457 being compiled with optimization. You should also turn on
7458 as many reasonable compilation warnings as possible; this
7459 makes life easier for porters, who can then look at build
7460 logs for possible problems. For the C programming language,
7461 this means the following compilation parameters should be
7463 <example compact="compact">
7465 CFLAGS = -O2 -g -Wall # sane warning options vary between programs
7467 INSTALL = install -s # (or use strip on the files in debian/tmp)
7472 Note that by default all installed binaries should be stripped,
7473 either by using the <tt>-s</tt> flag to
7474 <prgn>install</prgn>, or by calling <prgn>strip</prgn> on
7475 the binaries after they have been copied into
7476 <file>debian/tmp</file> but before the tree is made into a
7481 Although binaries in the build tree should be compiled with
7482 debugging information by default, it can often be difficult to
7483 debug programs if they are also subjected to compiler
7484 optimization. For this reason, it is recommended to support the
7485 standardized environment variable <tt>DEB_BUILD_OPTIONS</tt>
7486 (see <ref id="debianrules-options">). This variable can contain
7487 several flags to change how a package is compiled and built.
7491 It is up to the package maintainer to decide what
7492 compilation options are best for the package. Certain
7493 binaries (such as computationally-intensive programs) will
7494 function better with certain flags (<tt>-O3</tt>, for
7495 example); feel free to use them. Please use good judgment
7496 here. Don't use flags for the sake of it; only use them
7497 if there is good reason to do so. Feel free to override
7498 the upstream author's ideas about which compilation
7499 options are best: they are often inappropriate for our
7505 <sect id="libraries">
7506 <heading>Libraries</heading>
7509 If the package is <strong>architecture: any</strong>, then
7510 the shared library compilation and linking flags must have
7511 <tt>-fPIC</tt>, or the package shall not build on some of
7512 the supported architectures<footnote>
7514 If you are using GCC, <tt>-fPIC</tt> produces code with
7515 relocatable position independent code, which is required for
7516 most architectures to create a shared library, with i386 and
7517 perhaps some others where non position independent code is
7518 permitted in a shared library.
7521 Position independent code may have a performance penalty,
7522 especially on <tt>i386</tt>. However, in most cases the
7523 speed penalty must be measured against the memory wasted on
7524 the few architectures where non position independent code is
7527 </footnote>. Any exception to this rule must be discussed on
7528 the mailing list <em>debian-devel@lists.debian.org</em>, and
7529 a rough consensus obtained. The reasons for not compiling
7530 with <tt>-fPIC</tt> flag must be recorded in the file
7531 <tt>README.Debian</tt>, and care must be taken to either
7532 restrict the architecture or arrange for <tt>-fPIC</tt> to
7533 be used on architectures where it is required.<footnote>
7535 Some of the reasons why this might be required is if the
7536 library contains hand crafted assembly code that is not
7537 relocatable, the speed penalty is excessive for compute
7538 intensive libs, and similar reasons.
7543 As to the static libraries, the common case is not to have
7544 relocatable code, since there is no benefit, unless in specific
7545 cases; therefore the static version must not be compiled
7546 with the <tt>-fPIC</tt> flag. Any exception to this rule
7547 should be discussed on the mailing list
7548 <em>debian-devel@lists.debian.org</em>, and the reasons for
7549 compiling with the <tt>-fPIC</tt> flag must be recorded in
7550 the file <tt>README.Debian</tt>. <footnote>
7552 Some of the reasons for linking static libraries with
7553 the <tt>-fPIC</tt> flag are if, for example, one needs a
7554 Perl API for a library that is under rapid development,
7555 and has an unstable API, so shared libraries are
7556 pointless at this phase of the library's development. In
7557 that case, since Perl needs a library with relocatable
7558 code, it may make sense to create a static library with
7559 relocatable code. Another reason cited is if you are
7560 distilling various libraries into a common shared
7561 library, like <tt>mklibs</tt> does in the Debian
7567 In other words, if both a shared and a static library is
7568 being built, each source unit (<tt>*.c</tt>, for example,
7569 for C files) will need to be compiled twice, for the normal
7574 Libraries should be built with threading support and to be
7575 thread-safe if the library supports this.
7579 Although not enforced by the build tools, shared libraries
7580 must be linked against all libraries that they use symbols from
7581 in the same way that binaries are. This ensures the correct
7582 functioning of the <qref id="sharedlibs-shlibdeps">shlibs</qref>
7583 system and guarantees that all libraries can be safely opened
7584 with <tt>dlopen()</tt>. Packagers may wish to use the gcc
7585 option <tt>-Wl,-z,defs</tt> when building a shared library.
7586 Since this option enforces symbol resolution at build time,
7587 a missing library reference will be caught early as a fatal
7592 All installed shared libraries should be stripped with
7593 <example compact="compact">
7594 strip --strip-unneeded <var>your-lib</var>
7596 (The option <tt>--strip-unneeded</tt> makes
7597 <prgn>strip</prgn> remove only the symbols which aren't
7598 needed for relocation processing.) Shared libraries can
7599 function perfectly well when stripped, since the symbols for
7600 dynamic linking are in a separate part of the ELF object
7602 You might also want to use the options
7603 <tt>--remove-section=.comment</tt> and
7604 <tt>--remove-section=.note</tt> on both shared libraries
7605 and executables, and <tt>--strip-debug</tt> on static
7611 Note that under some circumstances it may be useful to
7612 install a shared library unstripped, for example when
7613 building a separate package to support debugging.
7617 Shared object files (often <file>.so</file> files) that are not
7618 public libraries, that is, they are not meant to be linked
7619 to by third party executables (binaries of other packages),
7620 should be installed in subdirectories of the
7621 <file>/usr/lib</file> directory. Such files are exempt from the
7622 rules that govern ordinary shared libraries, except that
7623 they must not be installed executable and should be
7625 A common example are the so-called "plug-ins",
7626 internal shared objects that are dynamically loaded by
7627 programs using <manref name="dlopen" section="3">.
7632 Packages that use <prgn>libtool</prgn> to create and install
7633 their shared libraries install a file containing additional
7634 metadata (ending in <file>.la</file>) alongside the library.
7635 For public libraries intended for use by other packages, these
7636 files normally should not be included in the Debian package,
7637 since the information they include is not necessary to link with
7638 the shared library on Debian and can add unnecessary additional
7639 dependencies to other programs or libraries.<footnote>
7640 These files store, among other things, all libraries on which
7641 that shared library depends. Unfortunately, if
7642 the <file>.la</file> file is present and contains that
7643 dependency information, using <prgn>libtool</prgn> when
7644 linking against that library will cause the resulting program
7645 or library to be linked against those dependencies as well,
7646 even if this is unnecessary. This can create unneeded
7647 dependencies on shared library packages that would otherwise
7648 be hidden behind the library ABI, and can make library
7649 transitions to new SONAMEs unnecessarily complicated and
7650 difficult to manage.
7652 If the <file>.la</file> file is required for that library (if,
7653 for instance, it's loaded via <tt>libltdl</tt> in a way that
7654 requires that meta-information), the <tt>dependency_libs</tt>
7655 setting in the <file>.la</file> file should normally be set to
7656 the empty string. If the shared library development package has
7657 historically included the <file>.la</file>, it must be retained
7658 in the development package (with <tt>dependency_libs</tt>
7659 emptied) until all libraries that depend on it have removed or
7660 emptied <tt>dependency_libs</tt> in their <file>.la</file>
7661 files to prevent linking with those other libraries
7662 using <prgn>libtool</prgn> from failing.
7666 If the <file>.la</file> must be included, it should be included
7667 in the development (<tt>-dev</tt>) package, unless the library
7668 will be loaded by <prgn>libtool</prgn>'s <tt>libltdl</tt>
7669 library. If it is intended for use with <tt>libltdl</tt>,
7670 the <file>.la</file> files must go in the run-time library
7675 These requirements for handling of <file>.la</file> files do not
7676 apply to loadable modules or libraries not installed in
7677 directories searched by default by the dynamic linker. Packages
7678 installing loadable modules will frequently need to install
7679 the <file>.la</file> files alongside the modules so that they
7680 can be loaded by <tt>libltdl</tt>. <tt>dependency_libs</tt>
7681 does not need to be modified for libraries or modules that are
7682 not installed in directories searched by the dynamic linker by
7683 default and not intended for use by other packages.
7687 You must make sure that you use only released versions of
7688 shared libraries to build your packages; otherwise other
7689 users will not be able to run your binaries
7690 properly. Producing source packages that depend on
7691 unreleased compilers is also usually a bad
7698 <heading>Shared libraries</heading>
7700 This section has moved to <ref id="sharedlibs">.
7706 <heading>Scripts</heading>
7709 All command scripts, including the package maintainer
7710 scripts inside the package and used by <prgn>dpkg</prgn>,
7711 should have a <tt>#!</tt> line naming the shell to be used
7716 In the case of Perl scripts this should be
7717 <tt>#!/usr/bin/perl</tt>.
7721 When scripts are installed into a directory in the system
7722 PATH, the script name should not include an extension such
7723 as <tt>.sh</tt> or <tt>.pl</tt> that denotes the scripting
7724 language currently used to implement it.
7727 Shell scripts (<prgn>sh</prgn> and <prgn>bash</prgn>) other than
7728 <file>init.d</file> scripts should almost certainly start
7729 with <tt>set -e</tt> so that errors are detected.
7730 <file>init.d</file> scripts are something of a special case, due
7731 to how frequently they need to call commands that are allowed to
7732 fail, and it may instead be easier to check the exit status of
7733 commands directly. See <ref id="writing-init"> for more
7734 information about writing <file>init.d</file> scripts.
7737 Every script should use <tt>set -e</tt> or check the exit status
7738 of <em>every</em> command.
7741 Scripts may assume that <file>/bin/sh</file> implements the
7742 SUSv3 Shell Command Language<footnote>
7743 Single UNIX Specification, version 3, which is also IEEE
7744 1003.1-2004 (POSIX), and is available on the World Wide Web
7745 from <url id="http://www.unix.org/version3/online.html"
7746 name="The Open Group"> after free
7747 registration.</footnote>
7748 plus the following additional features not mandated by
7750 These features are in widespread use in the Linux community
7751 and are implemented in all of bash, dash, and ksh, the most
7752 common shells users may wish to use as <file>/bin/sh</file>.
7755 <item><tt>echo -n</tt>, if implemented as a shell built-in,
7756 must not generate a newline.</item>
7757 <item><tt>test</tt>, if implemented as a shell built-in, must
7758 support <tt>-a</tt> and <tt>-o</tt> as binary logical
7760 <item><tt>local</tt> to create a scoped variable must be
7761 supported, including listing multiple variables in a single
7762 local command and assigning a value to a variable at the
7763 same time as localizing it. <tt>local</tt> may or
7764 may not preserve the variable value from an outer scope if
7765 no assignment is present. Uses such as:
7769 # ... use a, b, c, d ...
7772 must be supported and must set the value of <tt>c</tt> to
7775 <item>The XSI extension to <prgn>kill</prgn> allowing <tt>kill
7776 -<var>signal</var></tt>, where <var>signal</var> is either
7777 the name of a signal or one of the numeric signals listed in
7778 the XSI extension (0, 1, 2, 3, 6, 9, 14, and 15), must be
7779 supported if <prgn>kill</prgn> is implemented as a shell
7782 <item>The XSI extension to <prgn>trap</prgn> allowing numeric
7783 signals must be supported. In addition to the signal
7784 numbers listed in the extension, which are the same as for
7785 <prgn>kill</prgn> above, 13 (SIGPIPE) must be allowed.
7788 If a shell script requires non-SUSv3 features from the shell
7789 interpreter other than those listed above, the appropriate shell
7790 must be specified in the first line of the script (e.g.,
7791 <tt>#!/bin/bash</tt>) and the package must depend on the package
7792 providing the shell (unless the shell package is marked
7793 "Essential", as in the case of <prgn>bash</prgn>).
7797 You may wish to restrict your script to SUSv3 features plus the
7798 above set when possible so that it may use <file>/bin/sh</file>
7799 as its interpreter. If your script works with <prgn>dash</prgn>
7800 (originally called <prgn>ash</prgn>), it probably complies with
7801 the above requirements, but if you are in doubt, use
7802 <file>/bin/bash</file>.
7806 Perl scripts should check for errors when making any
7807 system calls, including <tt>open</tt>, <tt>print</tt>,
7808 <tt>close</tt>, <tt>rename</tt> and <tt>system</tt>.
7812 <prgn>csh</prgn> and <prgn>tcsh</prgn> should be avoided as
7813 scripting languages. See <em>Csh Programming Considered
7814 Harmful</em>, one of the <tt>comp.unix.*</tt> FAQs, which
7815 can be found at <url id="http://www.faqs.org/faqs/unix-faq/shell/csh-whynot/">.
7816 If an upstream package comes with <prgn>csh</prgn> scripts
7817 then you must make sure that they start with
7818 <tt>#!/bin/csh</tt> and make your package depend on the
7819 <prgn>c-shell</prgn> virtual package.
7823 Any scripts which create files in world-writeable
7824 directories (e.g., in <file>/tmp</file>) must use a
7825 mechanism which will fail atomically if a file with the same
7826 name already exists.
7830 The Debian base system provides the <prgn>tempfile</prgn>
7831 and <prgn>mktemp</prgn> utilities for use by scripts for
7838 <heading>Symbolic links</heading>
7841 In general, symbolic links within a top-level directory
7842 should be relative, and symbolic links pointing from one
7843 top-level directory into another should be absolute. (A
7844 top-level directory is a sub-directory of the root
7845 directory <file>/</file>.)
7849 In addition, symbolic links should be specified as short as
7850 possible, i.e., link targets like <file>foo/../bar</file> are
7855 Note that when creating a relative link using
7856 <prgn>ln</prgn> it is not necessary for the target of the
7857 link to exist relative to the working directory you're
7858 running <prgn>ln</prgn> from, nor is it necessary to change
7859 directory to the directory where the link is to be made.
7860 Simply include the string that should appear as the target
7861 of the link (this will be a pathname relative to the
7862 directory in which the link resides) as the first argument
7867 For example, in your <prgn>Makefile</prgn> or
7868 <file>debian/rules</file>, you can do things like:
7869 <example compact="compact">
7870 ln -fs gcc $(prefix)/bin/cc
7871 ln -fs gcc debian/tmp/usr/bin/cc
7872 ln -fs ../sbin/sendmail $(prefix)/bin/runq
7873 ln -fs ../sbin/sendmail debian/tmp/usr/bin/runq
7878 A symbolic link pointing to a compressed file should always
7879 have the same file extension as the referenced file. (For
7880 example, if a file <file>foo.gz</file> is referenced by a
7881 symbolic link, the filename of the link has to end with
7882 "<file>.gz</file>" too, as in <file>bar.gz</file>.)
7887 <heading>Device files</heading>
7890 Packages must not include device files or named pipes in the
7895 If a package needs any special device files that are not
7896 included in the base system, it must call
7897 <prgn>MAKEDEV</prgn> in the <prgn>postinst</prgn> script,
7898 after notifying the user<footnote>
7899 This notification could be done via a (low-priority)
7900 debconf message, or an echo (printf) statement.
7905 Packages must not remove any device files in the
7906 <prgn>postrm</prgn> or any other script. This is left to the
7907 system administrator.
7911 Debian uses the serial devices
7912 <file>/dev/ttyS*</file>. Programs using the old
7913 <file>/dev/cu*</file> devices should be changed to use
7914 <file>/dev/ttyS*</file>.
7918 Named pipes needed by the package must be created in
7919 the <prgn>postinst</prgn> script<footnote>
7920 It's better to use <prgn>mkfifo</prgn> rather
7921 than <prgn>mknod</prgn> to create named pipes so that
7922 automated checks for packages incorrectly creating device
7923 files with <prgn>mknod</prgn> won't have false positives.
7924 </footnote> and removed in
7925 the <prgn>prerm</prgn> or <prgn>postrm</prgn> script as
7930 <sect id="config-files">
7931 <heading>Configuration files</heading>
7934 <heading>Definitions</heading>
7938 <tag>configuration file</tag>
7940 A file that affects the operation of a program, or
7941 provides site- or host-specific information, or
7942 otherwise customizes the behavior of a program.
7943 Typically, configuration files are intended to be
7944 modified by the system administrator (if needed or
7945 desired) to conform to local policy or to provide
7946 more useful site-specific behavior.
7949 <tag><tt>conffile</tt></tag>
7951 A file listed in a package's <tt>conffiles</tt>
7952 file, and is treated specially by <prgn>dpkg</prgn>
7953 (see <ref id="configdetails">).
7959 The distinction between these two is important; they are
7960 not interchangeable concepts. Almost all
7961 <tt>conffile</tt>s are configuration files, but many
7962 configuration files are not <tt>conffiles</tt>.
7966 As noted elsewhere, <file>/etc/init.d</file> scripts,
7967 <file>/etc/default</file> files, scripts installed in
7968 <file>/etc/cron.{hourly,daily,weekly,monthly}</file>, and cron
7969 configuration installed in <file>/etc/cron.d</file> must be
7970 treated as configuration files. In general, any script that
7971 embeds configuration information is de-facto a configuration
7972 file and should be treated as such.
7977 <heading>Location</heading>
7980 Any configuration files created or used by your package
7981 must reside in <file>/etc</file>. If there are several,
7982 consider creating a subdirectory of <file>/etc</file>
7983 named after your package.
7987 If your package creates or uses configuration files
7988 outside of <file>/etc</file>, and it is not feasible to modify
7989 the package to use <file>/etc</file> directly, put the files
7990 in <file>/etc</file> and create symbolic links to those files
7991 from the location that the package requires.
7996 <heading>Behavior</heading>
7999 Configuration file handling must conform to the following
8001 <list compact="compact">
8003 local changes must be preserved during a package
8007 configuration files must be preserved when the
8008 package is removed, and only deleted when the
8012 Obsolete configuration files without local changes may be
8013 removed by the package during upgrade.
8017 The easy way to achieve this behavior is to make the
8018 configuration file a <tt>conffile</tt>. This is
8019 appropriate only if it is possible to distribute a default
8020 version that will work for most installations, although
8021 some system administrators may choose to modify it. This
8022 implies that the default version will be part of the
8023 package distribution, and must not be modified by the
8024 maintainer scripts during installation (or at any other
8029 In order to ensure that local changes are preserved
8030 correctly, no package may contain or make hard links to
8031 conffiles.<footnote>
8032 Rationale: There are two problems with hard links.
8033 The first is that some editors break the link while
8034 editing one of the files, so that the two files may
8035 unwittingly become unlinked and different. The second
8036 is that <prgn>dpkg</prgn> might break the hard link
8037 while upgrading <tt>conffile</tt>s.
8042 The other way to do it is via the maintainer scripts. In
8043 this case, the configuration file must not be listed as a
8044 <tt>conffile</tt> and must not be part of the package
8045 distribution. If the existence of a file is required for
8046 the package to be sensibly configured it is the
8047 responsibility of the package maintainer to provide
8048 maintainer scripts which correctly create, update and
8049 maintain the file and remove it on purge. (See <ref
8050 id="maintainerscripts"> for more information.) These
8051 scripts must be idempotent (i.e., must work correctly if
8052 <prgn>dpkg</prgn> needs to re-run them due to errors
8053 during installation or removal), must cope with all the
8054 variety of ways <prgn>dpkg</prgn> can call maintainer
8055 scripts, must not overwrite or otherwise mangle the user's
8056 configuration without asking, must not ask unnecessary
8057 questions (particularly during upgrades), and must
8058 otherwise be good citizens.
8062 The scripts are not required to configure every possible
8063 option for the package, but only those necessary to get
8064 the package running on a given system. Ideally the
8065 sysadmin should not have to do any configuration other
8066 than that done (semi-)automatically by the
8067 <prgn>postinst</prgn> script.
8071 A common practice is to create a script called
8072 <file><var>package</var>-configure</file> and have the
8073 package's <prgn>postinst</prgn> call it if and only if the
8074 configuration file does not already exist. In certain
8075 cases it is useful for there to be an example or template
8076 file which the maintainer scripts use. Such files should
8077 be in <file>/usr/share/<var>package</var></file> or
8078 <file>/usr/lib/<var>package</var></file> (depending on whether
8079 they are architecture-independent or not). There should
8080 be symbolic links to them from
8081 <file>/usr/share/doc/<var>package</var>/examples</file> if
8082 they are examples, and should be perfectly ordinary
8083 <prgn>dpkg</prgn>-handled files (<em>not</em>
8084 configuration files).
8088 These two styles of configuration file handling must
8089 not be mixed, for that way lies madness:
8090 <prgn>dpkg</prgn> will ask about overwriting the file
8091 every time the package is upgraded.
8096 <heading>Sharing configuration files</heading>
8099 Packages which specify the same file as a
8100 <tt>conffile</tt> must be tagged as <em>conflicting</em>
8101 with each other. (This is an instance of the general rule
8102 about not sharing files. Note that neither alternatives
8103 nor diversions are likely to be appropriate in this case;
8104 in particular, <prgn>dpkg</prgn> does not handle diverted
8105 <tt>conffile</tt>s well.)
8109 The maintainer scripts must not alter a <tt>conffile</tt>
8110 of <em>any</em> package, including the one the scripts
8115 If two or more packages use the same configuration file
8116 and it is reasonable for both to be installed at the same
8117 time, one of these packages must be defined as
8118 <em>owner</em> of the configuration file, i.e., it will be
8119 the package which handles that file as a configuration
8120 file. Other packages that use the configuration file must
8121 depend on the owning package if they require the
8122 configuration file to operate. If the other package will
8123 use the configuration file if present, but is capable of
8124 operating without it, no dependency need be declared.
8128 If it is desirable for two or more related packages to
8129 share a configuration file <em>and</em> for all of the
8130 related packages to be able to modify that configuration
8131 file, then the following should be done:
8132 <enumlist compact="compact">
8134 One of the related packages (the "owning" package)
8135 will manage the configuration file with maintainer
8136 scripts as described in the previous section.
8139 The owning package should also provide a program
8140 that the other packages may use to modify the
8144 The related packages must use the provided program
8145 to make any desired modifications to the
8146 configuration file. They should either depend on
8147 the core package to guarantee that the configuration
8148 modifier program is available or accept gracefully
8149 that they cannot modify the configuration file if it
8150 is not. (This is in addition to the fact that the
8151 configuration file may not even be present in the
8158 Sometimes it's appropriate to create a new package which
8159 provides the basic infrastructure for the other packages
8160 and which manages the shared configuration files. (The
8161 <tt>sgml-base</tt> package is a good example.)
8166 <heading>User configuration files ("dotfiles")</heading>
8169 The files in <file>/etc/skel</file> will automatically be
8170 copied into new user accounts by <prgn>adduser</prgn>.
8171 No other program should reference the files in
8172 <file>/etc/skel</file>.
8176 Therefore, if a program needs a dotfile to exist in
8177 advance in <file>$HOME</file> to work sensibly, that dotfile
8178 should be installed in <file>/etc/skel</file> and treated as a
8183 However, programs that require dotfiles in order to
8184 operate sensibly are a bad thing, unless they do create
8185 the dotfiles themselves automatically.
8189 Furthermore, programs should be configured by the Debian
8190 default installation to behave as closely to the upstream
8191 default behavior as possible.
8195 Therefore, if a program in a Debian package needs to be
8196 configured in some way in order to operate sensibly, that
8197 should be done using a site-wide configuration file placed
8198 in <file>/etc</file>. Only if the program doesn't support a
8199 site-wide default configuration and the package maintainer
8200 doesn't have time to add it may a default per-user file be
8201 placed in <file>/etc/skel</file>.
8205 <file>/etc/skel</file> should be as empty as we can make it.
8206 This is particularly true because there is no easy (or
8207 necessarily desirable) mechanism for ensuring that the
8208 appropriate dotfiles are copied into the accounts of
8209 existing users when a package is installed.
8215 <heading>Log files</heading>
8217 Log files should usually be named
8218 <file>/var/log/<var>package</var>.log</file>. If you have many
8219 log files, or need a separate directory for permission
8220 reasons (<file>/var/log</file> is writable only by
8221 <file>root</file>), you should usually create a directory named
8222 <file>/var/log/<var>package</var></file> and place your log
8227 Log files must be rotated occasionally so that they don't grow
8228 indefinitely. The best way to do this is to install a log
8229 rotation configuration file in the
8230 directory <file>/etc/logrotate.d</file>, normally
8231 named <file>/etc/logrotate.d/<var>package</var></file>, and use
8232 the facilities provided by <prgn>logrotate</prgn>.
8235 The traditional approach to log files has been to set up
8236 <em>ad hoc</em> log rotation schemes using simple shell
8237 scripts and cron. While this approach is highly
8238 customizable, it requires quite a lot of sysadmin work.
8239 Even though the original Debian system helped a little
8240 by automatically installing a system which can be used
8241 as a template, this was deemed not enough.
8245 The use of <prgn>logrotate</prgn>, a program developed
8246 by Red Hat, is better, as it centralizes log management.
8247 It has both a configuration file
8248 (<file>/etc/logrotate.conf</file>) and a directory where
8249 packages can drop their individual log rotation
8250 configurations (<file>/etc/logrotate.d</file>).
8253 Here is a good example for a logrotate config
8254 file (for more information see <manref name="logrotate"
8256 <example compact="compact">
8257 /var/log/foo/*.log {
8263 start-stop-daemon -K -p /var/run/foo.pid -s HUP -x /usr/sbin/foo -q
8267 This rotates all files under <file>/var/log/foo</file>, saves 12
8268 compressed generations, and tells the daemon to reopen its log
8269 files after the log rotation. It skips this log rotation
8270 (via <tt>missingok</tt>) if no such log file is present, which
8271 avoids errors if the package is removed but not purged.
8275 Log files should be removed when the package is
8276 purged (but not when it is only removed). This should be
8277 done by the <prgn>postrm</prgn> script when it is called
8278 with the argument <tt>purge</tt> (see <ref
8279 id="removedetails">).
8283 <sect id="permissions-owners">
8284 <heading>Permissions and owners</heading>
8287 The rules in this section are guidelines for general use.
8288 If necessary you may deviate from the details below.
8289 However, if you do so you must make sure that what is done
8290 is secure and you should try to be as consistent as possible
8291 with the rest of the system. You should probably also
8292 discuss it on <prgn>debian-devel</prgn> first.
8296 Files should be owned by <tt>root:root</tt>, and made
8297 writable only by the owner and universally readable (and
8298 executable, if appropriate), that is mode 644 or 755.
8302 Directories should be mode 755 or (for group-writability)
8303 mode 2775. The ownership of the directory should be
8304 consistent with its mode: if a directory is mode 2775, it
8305 should be owned by the group that needs write access to
8308 When a package is upgraded, and the owner or permissions
8309 of a file included in the package has changed, dpkg
8310 arranges for the ownership and permissions to be
8311 correctly set upon installation. However, this does not
8312 extend to directories; the permissions and ownership of
8313 directories already on the system does not change on
8314 install or upgrade of packages. This makes sense, since
8315 otherwise common directories like <tt>/usr</tt> would
8316 always be in flux. To correctly change permissions of a
8317 directory the package owns, explicit action is required,
8318 usually in the <tt>postinst</tt> script. Care must be
8319 taken to handle downgrades as well, in that case.
8325 Control information files should be owned by <tt>root:root</tt>
8326 and either mode 644 (for most files) or mode 755 (for
8327 executables such as <qref id="maintscripts">maintainer
8332 Setuid and setgid executables should be mode 4755 or 2755
8333 respectively, and owned by the appropriate user or group.
8334 They should not be made unreadable (modes like 4711 or
8335 2711 or even 4111); doing so achieves no extra security,
8336 because anyone can find the binary in the freely available
8337 Debian package; it is merely inconvenient. For the same
8338 reason you should not restrict read or execute permissions
8339 on non-set-id executables.
8343 Some setuid programs need to be restricted to particular
8344 sets of users, using file permissions. In this case they
8345 should be owned by the uid to which they are set-id, and by
8346 the group which should be allowed to execute them. They
8347 should have mode 4754; again there is no point in making
8348 them unreadable to those users who must not be allowed to
8353 It is possible to arrange that the system administrator can
8354 reconfigure the package to correspond to their local
8355 security policy by changing the permissions on a binary:
8356 they can do this by using <prgn>dpkg-statoverride</prgn>, as
8357 described below.<footnote>
8358 Ordinary files installed by <prgn>dpkg</prgn> (as
8359 opposed to <tt>conffile</tt>s and other similar objects)
8360 normally have their permissions reset to the distributed
8361 permissions when the package is reinstalled. However,
8362 the use of <prgn>dpkg-statoverride</prgn> overrides this
8365 Another method you should consider is to create a group for
8366 people allowed to use the program(s) and make any setuid
8367 executables executable only by that group.
8371 If you need to create a new user or group for your package
8372 there are two possibilities. Firstly, you may need to
8373 make some files in the binary package be owned by this
8374 user or group, or you may need to compile the user or
8375 group id (rather than just the name) into the binary
8376 (though this latter should be avoided if possible, as in
8377 this case you need a statically allocated id).</p>
8380 If you need a statically allocated id, you must ask for a
8381 user or group id from the <tt>base-passwd</tt> maintainer,
8382 and must not release the package until you have been
8383 allocated one. Once you have been allocated one you must
8384 either make the package depend on a version of the
8385 <tt>base-passwd</tt> package with the id present in
8386 <file>/etc/passwd</file> or <file>/etc/group</file>, or arrange for
8387 your package to create the user or group itself with the
8388 correct id (using <tt>adduser</tt>) in its
8389 <prgn>preinst</prgn> or <prgn>postinst</prgn>. (Doing it in
8390 the <prgn>postinst</prgn> is to be preferred if it is
8391 possible, otherwise a pre-dependency will be needed on the
8392 <tt>adduser</tt> package.)
8396 On the other hand, the program might be able to determine
8397 the uid or gid from the user or group name at runtime, so
8398 that a dynamically allocated id can be used. In this case
8399 you should choose an appropriate user or group name,
8400 discussing this on <prgn>debian-devel</prgn> and checking
8401 with the <package/base-passwd/ maintainer that it is unique and that
8402 they do not wish you to use a statically allocated id
8403 instead. When this has been checked you must arrange for
8404 your package to create the user or group if necessary using
8405 <prgn>adduser</prgn> in the <prgn>preinst</prgn> or
8406 <prgn>postinst</prgn> script (again, the latter is to be
8407 preferred if it is possible).
8411 Note that changing the numeric value of an id associated
8412 with a name is very difficult, and involves searching the
8413 file system for all appropriate files. You need to think
8414 carefully whether a static or dynamic id is required, since
8415 changing your mind later will cause problems.
8418 <sect1><heading>The use of <prgn>dpkg-statoverride</prgn></heading>
8420 This section is not intended as policy, but as a
8421 description of the use of <prgn>dpkg-statoverride</prgn>.
8425 If a system administrator wishes to have a file (or
8426 directory or other such thing) installed with owner and
8427 permissions different from those in the distributed Debian
8428 package, they can use the <prgn>dpkg-statoverride</prgn>
8429 program to instruct <prgn>dpkg</prgn> to use the different
8430 settings every time the file is installed. Thus the
8431 package maintainer should distribute the files with their
8432 normal permissions, and leave it for the system
8433 administrator to make any desired changes. For example, a
8434 daemon which is normally required to be setuid root, but
8435 in certain situations could be used without being setuid,
8436 should be installed setuid in the <tt>.deb</tt>. Then the
8437 local system administrator can change this if they wish.
8438 If there are two standard ways of doing it, the package
8439 maintainer can use <tt>debconf</tt> to find out the
8440 preference, and call <prgn>dpkg-statoverride</prgn> in the
8441 maintainer script if necessary to accommodate the system
8442 administrator's choice. Care must be taken during
8443 upgrades to not override an existing setting.
8447 Given the above, <prgn>dpkg-statoverride</prgn> is
8448 essentially a tool for system administrators and would not
8449 normally be needed in the maintainer scripts. There is
8450 one type of situation, though, where calls to
8451 <prgn>dpkg-statoverride</prgn> would be needed in the
8452 maintainer scripts, and that involves packages which use
8453 dynamically allocated user or group ids. In such a
8454 situation, something like the following idiom can be very
8455 helpful in the package's <prgn>postinst</prgn>, where
8456 <tt>sysuser</tt> is a dynamically allocated id:
8458 for i in /usr/bin/foo /usr/sbin/bar
8460 # only do something when no setting exists
8461 if ! dpkg-statoverride --list $i >/dev/null 2>&1
8463 #include: debconf processing, question about foo and bar
8464 if [ "$RET" = "true" ] ; then
8465 dpkg-statoverride --update --add sysuser root 4755 $i
8470 The corresponding code to remove the override when the package
8473 for i in /usr/bin/foo /usr/sbin/bar
8475 if dpkg-statoverride --list $i >/dev/null 2>&1
8477 dpkg-statoverride --remove $i
8487 <chapt id="customized-programs">
8488 <heading>Customized programs</heading>
8490 <sect id="arch-spec">
8491 <heading>Architecture specification strings</heading>
8494 If a program needs to specify an <em>architecture specification
8495 string</em> in some place, it should select one of the strings
8496 provided by <tt>dpkg-architecture -L</tt>. The strings are in
8497 the format <tt><var>os</var>-<var>arch</var></tt>, though the OS
8498 part is sometimes elided, as when the OS is Linux.
8502 Note that we don't want to use
8503 <tt><var>arch</var>-debian-linux</tt> to apply to the rule
8504 <tt><var>architecture</var>-<var>vendor</var>-<var>os</var></tt>
8505 since this would make our programs incompatible with other
8506 Linux distributions. We also don't use something like
8507 <tt><var>arch</var>-unknown-linux</tt>, since the
8508 <tt>unknown</tt> does not look very good.
8511 <sect1 id="arch-wildcard-spec">
8512 <heading>Architecture wildcards</heading>
8515 A package may specify an architecture wildcard. Architecture
8516 wildcards are in the format <tt>any</tt> (which matches every
8517 architecture), <tt><var>os</var></tt>-any, or
8518 any-<tt><var>cpu</var></tt>. <footnote>
8519 Internally, the package system normalizes the GNU triplets
8520 and the Debian arches into Debian arch triplets (which are
8521 kind of inverted GNU triplets), with the first component of
8522 the triplet representing the libc and ABI in use, and then
8523 does matching against those triplets. However, such
8524 triplets are an internal implementation detail that should
8525 not be used by packages directly. The libc and ABI portion
8526 is handled internally by the package system based on
8527 the <var>os</var> and <var>cpu</var>.
8534 <heading>Daemons</heading>
8537 The configuration files <file>/etc/services</file>,
8538 <file>/etc/protocols</file>, and <file>/etc/rpc</file> are managed
8539 by the <prgn>netbase</prgn> package and must not be modified
8544 If a package requires a new entry in one of these files, the
8545 maintainer should get in contact with the
8546 <prgn>netbase</prgn> maintainer, who will add the entries
8547 and release a new version of the <prgn>netbase</prgn>
8552 The configuration file <file>/etc/inetd.conf</file> must not be
8553 modified by the package's scripts except via the
8554 <prgn>update-inetd</prgn> script or the
8555 <file>DebianNet.pm</file> Perl module. See their documentation
8556 for details on how to add entries.
8560 If a package wants to install an example entry into
8561 <file>/etc/inetd.conf</file>, the entry must be preceded with
8562 exactly one hash character (<tt>#</tt>). Such lines are
8563 treated as "commented out by user" by the
8564 <prgn>update-inetd</prgn> script and are not changed or
8565 activated during package updates.
8570 <heading>Using pseudo-ttys and modifying wtmp, utmp and
8574 Some programs need to create pseudo-ttys. This should be done
8575 using Unix98 ptys if the C library supports it. The resulting
8576 program must not be installed setuid root, unless that
8577 is required for other functionality.
8581 The files <file>/var/run/utmp</file>, <file>/var/log/wtmp</file> and
8582 <file>/var/log/lastlog</file> must be installed writable by
8583 group <tt>utmp</tt>. Programs which need to modify those
8584 files must be installed setgid <tt>utmp</tt>.
8589 <heading>Editors and pagers</heading>
8592 Some programs have the ability to launch an editor or pager
8593 program to edit or display a text document. Since there are
8594 lots of different editors and pagers available in the Debian
8595 distribution, the system administrator and each user should
8596 have the possibility to choose their preferred editor and
8601 In addition, every program should choose a good default
8602 editor/pager if none is selected by the user or system
8607 Thus, every program that launches an editor or pager must
8608 use the EDITOR or PAGER environment variable to determine
8609 the editor or pager the user wishes to use. If these
8610 variables are not set, the programs <file>/usr/bin/editor</file>
8611 and <file>/usr/bin/pager</file> should be used, respectively.
8615 These two files are managed through the <prgn>dpkg</prgn>
8616 "alternatives" mechanism. Every package providing an editor or
8617 pager must call the <prgn>update-alternatives</prgn> script to
8618 register as an alternative for <file>/usr/bin/editor</file>
8619 or <file>/usr/bin/pager</file> as appropriate. The alternative
8620 should have a slave alternative
8621 for <file>/usr/share/man/man1/editor.1.gz</file>
8622 or <file>/usr/share/man/man1/pager.1.gz</file> pointing to the
8623 corresponding manual page.
8627 If it is very hard to adapt a program to make use of the
8628 EDITOR or PAGER variables, that program may be configured to
8629 use <file>/usr/bin/sensible-editor</file> and
8630 <file>/usr/bin/sensible-pager</file> as the editor or pager
8631 program respectively. These are two scripts provided in the
8632 <package>sensible-utils</package> package that check the EDITOR
8633 and PAGER variables and launch the appropriate program, and fall
8634 back to <file>/usr/bin/editor</file>
8635 and <file>/usr/bin/pager</file> if the variable is not set.
8639 A program may also use the VISUAL environment variable to
8640 determine the user's choice of editor. If it exists, it
8641 should take precedence over EDITOR. This is in fact what
8642 <file>/usr/bin/sensible-editor</file> does.
8646 It is not required for a package to depend on
8647 <tt>editor</tt> and <tt>pager</tt>, nor is it required for a
8648 package to provide such virtual packages.<footnote>
8649 The Debian base system already provides an editor and a
8655 <sect id="web-appl">
8656 <heading>Web servers and applications</heading>
8659 This section describes the locations and URLs that should
8660 be used by all web servers and web applications in the
8667 Cgi-bin executable files are installed in the
8669 <example compact="compact">
8670 /usr/lib/cgi-bin/<var>cgi-bin-name</var>
8672 or a subdirectory of that directory, and should be
8674 <example compact="compact">
8675 http://localhost/cgi-bin/<var>cgi-bin-name</var>
8677 (possibly with a subdirectory name
8678 before <var>cgi-bin-name</var>).
8682 <p>Access to HTML documents</p>
8685 HTML documents for a package are stored in
8686 <file>/usr/share/doc/<var>package</var></file>
8687 and can be referred to as
8688 <example compact="compact">
8689 http://localhost/doc/<var>package</var>/<var>filename</var>
8694 The web server should restrict access to the document
8695 tree so that only clients on the same host can read
8696 the documents. If the web server does not support such
8697 access controls, then it should not provide access at
8698 all, or ask about providing access during installation.
8703 <p>Access to images</p>
8705 It is recommended that images for a package be stored
8706 in <tt>/usr/share/images/<var>package</var></tt> and
8707 may be referred to through an alias <tt>/images/</tt>
8710 http://localhost/images/<package>/<filename>
8717 <p>Web Document Root</p>
8720 Web Applications should try to avoid storing files in
8721 the Web Document Root. Instead they should use the
8722 /usr/share/doc/<var>package</var> directory for
8723 documents and register the Web Application via the
8724 <package>doc-base</package> package. If access to the
8725 web document root is unavoidable then use
8726 <example compact="compact">
8729 as the Document Root. This might be just a symbolic
8730 link to the location where the system administrator
8731 has put the real document root.
8734 <item><p>Providing httpd and/or httpd-cgi</p>
8736 All web servers should provide the virtual package
8737 <tt>httpd</tt>. If a web server has CGI support it should
8738 provide <tt>httpd-cgi</tt> additionally.
8741 All web applications which do not contain CGI scripts should
8742 depend on <tt>httpd</tt>, all those web applications which
8743 <tt>do</tt> contain CGI scripts, should depend on
8751 <sect id="mail-transport-agents">
8752 <heading>Mail transport, delivery and user agents</heading>
8755 Debian packages which process electronic mail, whether mail
8756 user agents (MUAs) or mail transport agents (MTAs), must
8757 ensure that they are compatible with the configuration
8758 decisions below. Failure to do this may result in lost
8759 mail, broken <tt>From:</tt> lines, and other serious brain
8764 The mail spool is <file>/var/mail</file> and the interface to
8765 send a mail message is <file>/usr/sbin/sendmail</file> (as per
8766 the FHS). On older systems, the mail spool may be
8767 physically located in <file>/var/spool/mail</file>, but all
8768 access to the mail spool should be via the
8769 <file>/var/mail</file> symlink. The mail spool is part of the
8770 base system and not part of the MTA package.
8774 All Debian MUAs, MTAs, MDAs and other mailbox accessing
8775 programs (such as IMAP daemons) must lock the mailbox in an
8776 NFS-safe way. This means that <tt>fcntl()</tt> locking must
8777 be combined with dot locking. To avoid deadlocks, a program
8778 should use <tt>fcntl()</tt> first and dot locking after
8779 this, or alternatively implement the two locking methods in
8780 a non blocking way<footnote>
8781 If it is not possible to establish both locks, the
8782 system shouldn't wait for the second lock to be
8783 established, but remove the first lock, wait a (random)
8784 time, and start over locking again.
8785 </footnote>. Using the functions <tt>maillock</tt> and
8786 <tt>mailunlock</tt> provided by the
8787 <tt>liblockfile*</tt><footnote>
8788 You will need to depend on <tt>liblockfile1 (>>1.01)</tt>
8789 to use these functions.
8790 </footnote> packages is the recommended way to realize this.
8794 Mailboxes are generally either mode 600 and owned by
8795 <var>user</var> or mode 660 and owned by
8796 <tt><var>user</var>:mail</tt><footnote>
8797 There are two traditional permission schemes for mail spools:
8798 mode 600 with all mail delivery done by processes running as
8799 the destination user, or mode 660 and owned by group mail with
8800 mail delivery done by a process running as a system user in
8801 group mail. Historically, Debian required mode 660 mail
8802 spools to enable the latter model, but that model has become
8803 increasingly uncommon and the principle of least privilege
8804 indicates that mail systems that use the first model should
8805 use permissions of 600. If delivery to programs is permitted,
8806 it's easier to keep the mail system secure if the delivery
8807 agent runs as the destination user. Debian Policy therefore
8808 permits either scheme.
8809 </footnote>. The local system administrator may choose a
8810 different permission scheme; packages should not make
8811 assumptions about the permission and ownership of mailboxes
8812 unless required (such as when creating a new mailbox). A MUA
8813 may remove a mailbox (unless it has nonstandard permissions) in
8814 which case the MTA or another MUA must recreate it if needed.
8818 The mail spool is 2775 <tt>root:mail</tt>, and MUAs should
8819 be setgid mail to do the locking mentioned above (and
8820 must obviously avoid accessing other users' mailboxes
8821 using this privilege).</p>
8824 <file>/etc/aliases</file> is the source file for the system mail
8825 aliases (e.g., postmaster, usenet, etc.), it is the one
8826 which the sysadmin and <prgn>postinst</prgn> scripts may
8827 edit. After <file>/etc/aliases</file> is edited the program or
8828 human editing it must call <prgn>newaliases</prgn>. All MTA
8829 packages must come with a <prgn>newaliases</prgn> program,
8830 even if it does nothing, but older MTA packages did not do
8831 this so programs should not fail if <prgn>newaliases</prgn>
8832 cannot be found. Note that because of this, all MTA
8833 packages must have <tt>Provides</tt>, <tt>Conflicts</tt> and
8834 <tt>Replaces: mail-transport-agent</tt> control fields.
8838 The convention of writing <tt>forward to
8839 <var>address</var></tt> in the mailbox itself is not
8840 supported. Use a <tt>.forward</tt> file instead.</p>
8843 The <prgn>rmail</prgn> program used by UUCP
8844 for incoming mail should be <file>/usr/sbin/rmail</file>.
8845 Likewise, <prgn>rsmtp</prgn>, for receiving
8846 batch-SMTP-over-UUCP, should be <file>/usr/sbin/rsmtp</file> if it
8850 If your package needs to know what hostname to use on (for
8851 example) outgoing news and mail messages which are generated
8852 locally, you should use the file <file>/etc/mailname</file>. It
8853 will contain the portion after the username and <tt>@</tt>
8854 (at) sign for email addresses of users on the machine
8855 (followed by a newline).
8859 Such a package should check for the existence of this file
8860 when it is being configured. If it exists, it should be
8861 used without comment, although an MTA's configuration script
8862 may wish to prompt the user even if it finds that this file
8863 exists. If the file does not exist, the package should
8864 prompt the user for the value (preferably using
8865 <prgn>debconf</prgn>) and store it in <file>/etc/mailname</file>
8866 as well as using it in the package's configuration. The
8867 prompt should make it clear that the name will not just be
8868 used by that package. For example, in this situation the
8869 <tt>inn</tt> package could say something like:
8870 <example compact="compact">
8871 Please enter the "mail name" of your system. This is the
8872 hostname portion of the address to be shown on outgoing
8873 news and mail messages. The default is
8874 <var>syshostname</var>, your system's host name. Mail
8875 name ["<var>syshostname</var>"]:
8877 where <var>syshostname</var> is the output of <tt>hostname
8883 <heading>News system configuration</heading>
8886 All the configuration files related to the NNTP (news)
8887 servers and clients should be located under
8888 <file>/etc/news</file>.</p>
8891 There are some configuration issues that apply to a number
8892 of news clients and server packages on the machine. These
8896 <tag><file>/etc/news/organization</file></tag>
8898 A string which should appear as the
8899 organization header for all messages posted
8900 by NNTP clients on the machine
8903 <tag><file>/etc/news/server</file></tag>
8905 Contains the FQDN of the upstream NNTP
8906 server, or localhost if the local machine is
8911 Other global files may be added as required for cross-package news
8918 <heading>Programs for the X Window System</heading>
8921 <heading>Providing X support and package priorities</heading>
8924 Programs that can be configured with support for the X
8925 Window System must be configured to do so and must declare
8926 any package dependencies necessary to satisfy their
8927 runtime requirements when using the X Window System. If
8928 such a package is of higher priority than the X packages
8929 on which it depends, it is required that either the
8930 X-specific components be split into a separate package, or
8931 that an alternative version of the package, which includes
8932 X support, be provided, or that the package's priority be
8938 <heading>Packages providing an X server</heading>
8941 Packages that provide an X server that, directly or
8942 indirectly, communicates with real input and display
8943 hardware should declare in their <tt>Provides</tt> control
8944 field that they provide the virtual
8945 package <tt>xserver</tt>.<footnote>
8946 This implements current practice, and provides an
8947 actual policy for usage of the <tt>xserver</tt>
8948 virtual package which appears in the virtual packages
8949 list. In a nutshell, X servers that interface
8950 directly with the display and input hardware or via
8951 another subsystem (e.g., GGI) should provide
8952 <tt>xserver</tt>. Things like <tt>Xvfb</tt>,
8953 <tt>Xnest</tt>, and <tt>Xprt</tt> should not.
8959 <heading>Packages providing a terminal emulator</heading>
8962 Packages that provide a terminal emulator for the X Window
8963 System which meet the criteria listed below should declare in
8964 their <tt>Provides</tt> control field that they provide the
8965 virtual package <tt>x-terminal-emulator</tt>. They should
8966 also register themselves as an alternative for
8967 <file>/usr/bin/x-terminal-emulator</file>, with a priority of
8968 20. That alternative should have a slave alternative
8969 for <file>/usr/share/man/man1/x-terminal-emulator.1.gz</file>
8970 pointing to the corresponding manual page.
8974 To be an <tt>x-terminal-emulator</tt>, a program must:
8975 <list compact="compact">
8977 Be able to emulate a DEC VT100 terminal, or a
8978 compatible terminal.
8982 Support the command-line option <tt>-e
8983 <var>command</var></tt>, which creates a new
8984 terminal window<footnote>
8985 "New terminal window" does not necessarily mean
8986 a new top-level X window directly parented by
8987 the window manager; it could, if the terminal
8988 emulator application were so coded, be a new
8989 "view" in a multiple-document interface (MDI).
8991 and runs the specified <var>command</var>,
8992 interpreting the entirety of the rest of the command
8993 line as a command to pass straight to exec, in the
8994 manner that <tt>xterm</tt> does.
8998 Support the command-line option <tt>-T
8999 <var>title</var></tt>, which creates a new terminal
9000 window with the window title <var>title</var>.
9007 <heading>Packages providing a window manager</heading>
9010 Packages that provide a window manager should declare in
9011 their <tt>Provides</tt> control field that they provide the
9012 virtual package <tt>x-window-manager</tt>. They should also
9013 register themselves as an alternative for
9014 <file>/usr/bin/x-window-manager</file>, with a priority
9015 calculated as follows:
9016 <list compact="compact">
9018 Start with a priority of 20.
9022 If the window manager supports the Debian menu
9023 system, add 20 points if this support is available
9024 in the package's default configuration (i.e., no
9025 configuration files belonging to the system or user
9026 have to be edited to activate the feature); if
9027 configuration files must be modified, add only 10
9033 If the window manager complies with <url
9034 id="http://www.freedesktop.org/Standards/wm-spec"
9035 name="The Window Manager Specification Project">,
9036 written by the <url id="http://www.freedesktop.org/"
9037 name="Free Desktop Group">, add 40 points.
9041 If the window manager permits the X session to be
9042 restarted using a <em>different</em> window manager
9043 (without killing the X server) in its default
9044 configuration, add 10 points; otherwise add none.
9047 That alternative should have a slave alternative
9048 for <file>/usr/share/man/man1/x-window-manager.1.gz</file>
9049 pointing to the corresponding manual page.
9054 <heading>Packages providing fonts</heading>
9057 Packages that provide fonts for the X Window
9059 For the purposes of Debian Policy, a "font for the X
9060 Window System" is one which is accessed via X protocol
9061 requests. Fonts for the Linux console, for PostScript
9062 renderer, or any other purpose, do not fit this
9063 definition. Any tool which makes such fonts available
9064 to the X Window System, however, must abide by this
9067 must do a number of things to ensure that they are both
9068 available without modification of the X or font server
9069 configuration, and that they do not corrupt files used by
9070 other font packages to register information about
9074 Fonts of any type supported by the X Window System
9075 must be in a separate binary package from any
9076 executables, libraries, or documentation (except
9077 that specific to the fonts shipped, such as their
9078 license information). If one or more of the fonts
9079 so packaged are necessary for proper operation of
9080 the package with which they are associated the font
9081 package may be Recommended; if the fonts merely
9082 provide an enhancement, a Suggests relationship may
9083 be used. Packages must not Depend on font
9085 This is because the X server may retrieve fonts
9086 from the local file system or over the network
9087 from an X font server; the Debian package system
9088 is empowered to deal only with the local
9094 BDF fonts must be converted to PCF fonts with the
9095 <prgn>bdftopcf</prgn> utility (available in the
9096 <tt>xfonts-utils</tt> package, <prgn>gzip</prgn>ped, and
9097 placed in a directory that corresponds to their
9099 <list compact="compact">
9101 100 dpi fonts must be placed in
9102 <file>/usr/share/fonts/X11/100dpi/</file>.
9106 75 dpi fonts must be placed in
9107 <file>/usr/share/fonts/X11/75dpi/</file>.
9111 Character-cell fonts, cursor fonts, and other
9112 low-resolution fonts must be placed in
9113 <file>/usr/share/fonts/X11/misc/</file>.
9119 Type 1 fonts must be placed in
9120 <file>/usr/share/fonts/X11/Type1/</file>. If font
9121 metric files are available, they must be placed here
9126 Subdirectories of <file>/usr/share/fonts/X11/</file>
9127 other than those listed above must be neither
9128 created nor used. (The <file>PEX</file>, <file>CID</file>,
9129 <file>Speedo</file>, and <file>cyrillic</file> directories
9130 are excepted for historical reasons, but installation of
9131 files into these directories remains discouraged.)
9135 Font packages may, instead of placing files directly
9136 in the X font directories listed above, provide
9137 symbolic links in that font directory pointing to
9138 the files' actual location in the filesystem. Such
9139 a location must comply with the FHS.
9143 Font packages should not contain both 75dpi and
9144 100dpi versions of a font. If both are available,
9145 they should be provided in separate binary packages
9146 with <tt>-75dpi</tt> or <tt>-100dpi</tt> appended to
9147 the names of the packages containing the
9148 corresponding fonts.
9152 Fonts destined for the <file>misc</file> subdirectory
9153 should not be included in the same package as 75dpi
9154 or 100dpi fonts; instead, they should be provided in
9155 a separate package with <tt>-misc</tt> appended to
9160 Font packages must not provide the files
9161 <file>fonts.dir</file>, <file>fonts.alias</file>, or
9162 <file>fonts.scale</file> in a font directory:
9165 <file>fonts.dir</file> files must not be provided at all.
9169 <file>fonts.alias</file> and <file>fonts.scale</file>
9170 files, if needed, should be provided in the
9172 <file>/etc/X11/fonts/<var>fontdir</var>/<var>package</var>.<var>extension</var></file>,
9173 where <var>fontdir</var> is the name of the
9175 <file>/usr/share/fonts/X11/</file> where the
9176 package's corresponding fonts are stored
9177 (e.g., <tt>75dpi</tt> or <tt>misc</tt>),
9178 <var>package</var> is the name of the package
9179 that provides these fonts, and
9180 <var>extension</var> is either <tt>scale</tt>
9181 or <tt>alias</tt>, whichever corresponds to
9188 Font packages must declare a dependency on
9189 <tt>xfonts-utils</tt> in their <tt>Depends</tt>
9190 or <tt>Pre-Depends</tt> control field.
9194 Font packages that provide one or more
9195 <file>fonts.scale</file> files as described above must
9196 invoke <prgn>update-fonts-scale</prgn> on each
9197 directory into which they installed fonts
9198 <em>before</em> invoking
9199 <prgn>update-fonts-dir</prgn> on that directory.
9200 This invocation must occur in both the
9201 <prgn>postinst</prgn> (for all arguments) and
9202 <prgn>postrm</prgn> (for all arguments except
9203 <tt>upgrade</tt>) scripts.
9207 Font packages that provide one or more
9208 <file>fonts.alias</file> files as described above must
9209 invoke <prgn>update-fonts-alias</prgn> on each
9210 directory into which they installed fonts. This
9211 invocation must occur in both the
9212 <prgn>postinst</prgn> (for all arguments) and
9213 <prgn>postrm</prgn> (for all arguments except
9214 <tt>upgrade</tt>) scripts.
9218 Font packages must invoke
9219 <prgn>update-fonts-dir</prgn> on each directory into
9220 which they installed fonts. This invocation must
9221 occur in both the <prgn>postinst</prgn> (for all
9222 arguments) and <prgn>postrm</prgn> (for all
9223 arguments except <tt>upgrade</tt>) scripts.
9227 Font packages must not provide alias names for the
9228 fonts they include which collide with alias names
9229 already in use by fonts already packaged.
9233 Font packages must not provide fonts with the same
9234 XLFD registry name as another font already packaged.
9240 <sect1 id="appdefaults">
9241 <heading>Application defaults files</heading>
9244 Application defaults files must be installed in the
9245 directory <file>/etc/X11/app-defaults/</file> (use of a
9246 localized subdirectory of <file>/etc/X11/</file> as described
9247 in the <em>X Toolkit Intrinsics - C Language
9248 Interface</em> manual is also permitted). They must be
9249 registered as <tt>conffile</tt>s or handled as
9250 configuration files.
9254 Customization of programs' X resources may also be
9255 supported with the provision of a file with the same name
9256 as that of the package placed in
9257 the <file>/etc/X11/Xresources/</file> directory, which
9258 must be registered as a <tt>conffile</tt> or handled as a
9259 configuration file.<footnote>
9260 Note that this mechanism is not the same as using
9261 app-defaults; app-defaults are tied to the client
9262 binary on the local file system, whereas X resources
9263 are stored in the X server and affect all connecting
9270 <heading>Installation directory issues</heading>
9273 Historically, packages using the X Window System used a
9274 separate set of installation directories from other packages.
9275 This practice has been discontinued and packages using the X
9276 Window System should now generally be installed in the same
9277 directories as any other package. Specifically, packages must
9278 not install files under the <file>/usr/X11R6/</file> directory
9279 and the <file>/usr/X11R6/</file> directory hierarchy should be
9280 regarded as obsolete.
9284 Include files previously installed under
9285 <file>/usr/X11R6/include/X11/</file> should be installed into
9286 <file>/usr/include/X11/</file>. For files previously
9287 installed into subdirectories of
9288 <file>/usr/X11R6/lib/X11/</file>, package maintainers should
9289 determine if subdirectories of <file>/usr/lib/</file> and
9290 <file>/usr/share/</file> can be used. If not, a subdirectory
9291 of <file>/usr/lib/X11/</file> should be used.
9295 Configuration files for window, display, or session managers
9296 or other applications that are tightly integrated with the X
9297 Window System may be placed in a subdirectory
9298 of <file>/etc/X11/</file> corresponding to the package name.
9299 Other X Window System applications should use
9300 the <file>/etc/</file> directory unless otherwise mandated by
9301 policy (such as for <ref id="appdefaults">).
9306 <heading>The OSF/Motif and OpenMotif libraries</heading>
9309 <em>Programs that require the non-DFSG-compliant OSF/Motif or
9310 OpenMotif libraries</em><footnote>
9311 OSF/Motif and OpenMotif are collectively referred to as
9312 "Motif" in this policy document.
9314 should be compiled against and tested with LessTif (a free
9315 re-implementation of Motif) instead. If the maintainer
9316 judges that the program or programs do not work
9317 sufficiently well with LessTif to be distributed and
9318 supported, but do so when compiled against Motif, then two
9319 versions of the package should be created; one linked
9320 statically against Motif and with <tt>-smotif</tt>
9321 appended to the package name, and one linked dynamically
9322 against Motif and with <tt>-dmotif</tt> appended to the
9327 Both Motif-linked versions are dependent
9328 upon non-DFSG-compliant software and thus cannot be
9329 uploaded to the <em>main</em> distribution; if the
9330 software is itself DFSG-compliant it may be uploaded to
9331 the <em>contrib</em> distribution. While known existing
9332 versions of Motif permit unlimited redistribution of
9333 binaries linked against the library (whether statically or
9334 dynamically), it is the package maintainer's
9335 responsibility to determine whether this is permitted by
9336 the license of the copy of Motif in their possession.
9342 <heading>Perl programs and modules</heading>
9345 Perl programs and modules should follow the current Perl policy.
9349 The Perl policy can be found in the <tt>perl-policy</tt>
9350 files in the <tt>debian-policy</tt> package.
9351 It is also available from the Debian web mirrors at
9352 <tt><url name="/doc/packaging-manuals/perl-policy/"
9353 id="http://www.debian.org/doc/packaging-manuals/perl-policy/"></tt>.
9358 <heading>Emacs lisp programs</heading>
9361 Please refer to the "Debian Emacs Policy" for details of how to
9362 package emacs lisp programs.
9366 The Emacs policy is available in
9367 <file>debian-emacs-policy.gz</file> of the
9368 <package>emacsen-common</package> package.
9369 It is also available from the Debian web mirrors at
9370 <tt><url name="/doc/packaging-manuals/debian-emacs-policy"
9371 id="http://www.debian.org/doc/packaging-manuals/debian-emacs-policy"></tt>.
9376 <heading>Games</heading>
9379 The permissions on <file>/var/games</file> are mode 755, owner
9380 <tt>root</tt> and group <tt>root</tt>.
9384 Each game decides on its own security policy.</p>
9387 Games which require protected, privileged access to
9388 high-score files, saved games, etc., may be made
9389 set-<em>group</em>-id (mode 2755) and owned by
9390 <tt>root:games</tt>, and use files and directories with
9391 appropriate permissions (770 <tt>root:games</tt>, for
9392 example). They must not be made
9393 set-<em>user</em>-id, as this causes security problems. (If
9394 an attacker can subvert any set-user-id game they can
9395 overwrite the executable of any other, causing other players
9396 of these games to run a Trojan horse program. With a
9397 set-group-id game the attacker only gets access to less
9398 important game data, and if they can get at the other
9399 players' accounts at all it will take considerably more
9403 Some packages, for example some fortune cookie programs, are
9404 configured by the upstream authors to install with their
9405 data files or other static information made unreadable so
9406 that they can only be accessed through set-id programs
9407 provided. You should not do this in a Debian package: anyone can
9408 download the <file>.deb</file> file and read the data from it,
9409 so there is no point making the files unreadable. Not
9410 making the files unreadable also means that you don't have
9411 to make so many programs set-id, which reduces the risk of a
9415 As described in the FHS, binaries of games should be
9416 installed in the directory <file>/usr/games</file>. This also
9417 applies to games that use the X Window System. Manual pages
9418 for games (X and non-X games) should be installed in
9419 <file>/usr/share/man/man6</file>.</p>
9425 <heading>Documentation</heading>
9428 <heading>Manual pages</heading>
9431 You should install manual pages in <prgn>nroff</prgn> source
9432 form, in appropriate places under <file>/usr/share/man</file>.
9433 You should only use sections 1 to 9 (see the FHS for more
9434 details). You must not install a pre-formatted "cat page".
9438 Each program, utility, and function should have an
9439 associated manual page included in the same package. It is
9440 suggested that all configuration files also have a manual
9441 page included as well. Manual pages for protocols and other
9442 auxiliary things are optional.
9446 If no manual page is available, this is considered as a bug
9447 and should be reported to the Debian Bug Tracking System (the
9448 maintainer of the package is allowed to write this bug report
9449 themselves, if they so desire). Do not close the bug report
9450 until a proper man page is available.<footnote>
9451 It is not very hard to write a man page. See the
9452 <url id="http://www.schweikhardt.net/man_page_howto.html"
9453 name="Man-Page-HOWTO">,
9454 <manref name="man" section="7">, the examples
9455 created by <prgn>debmake</prgn> or <prgn>dh_make</prgn>,
9456 the helper program <prgn>help2man</prgn>, or the
9457 directory <file>/usr/share/doc/man-db/examples</file>.
9462 You may forward a complaint about a missing man page to the
9463 upstream authors, and mark the bug as forwarded in the
9464 Debian bug tracking system. Even though the GNU Project do
9465 not in general consider the lack of a man page to be a bug,
9466 we do; if they tell you that they don't consider it a bug
9467 you should leave the bug in our bug tracking system open
9472 Manual pages should be installed compressed using <tt>gzip -9</tt>.
9476 If one man page needs to be accessible via several names it
9477 is better to use a symbolic link than the <file>.so</file>
9478 feature, but there is no need to fiddle with the relevant
9479 parts of the upstream source to change from <file>.so</file> to
9480 symlinks: don't do it unless it's easy. You should not
9481 create hard links in the manual page directories, nor put
9482 absolute filenames in <file>.so</file> directives. The filename
9483 in a <file>.so</file> in a man page should be relative to the
9484 base of the man page tree (usually
9485 <file>/usr/share/man</file>). If you do not create any links
9486 (whether symlinks, hard links, or <tt>.so</tt> directives)
9487 in the file system to the alternate names of the man page,
9488 then you should not rely on <prgn>man</prgn> finding your
9489 man page under those names based solely on the information in
9490 the man page's header.<footnote>
9491 Supporting this in <prgn>man</prgn> often requires
9492 unreasonable processing time to find a manual page or to
9493 report that none exists, and moves knowledge into man's
9494 database that would be better left in the file system.
9495 This support is therefore deprecated and will cease to
9496 be present in the future.
9501 Manual pages in locale-specific subdirectories of
9502 <file>/usr/share/man</file> should use either UTF-8 or the usual
9503 legacy encoding for that language (normally the one corresponding
9504 to the shortest relevant locale name in
9505 <file>/usr/share/i18n/SUPPORTED</file>). For example, pages under
9506 <file>/usr/share/man/fr</file> should use either UTF-8 or
9507 ISO-8859-1.<footnote>
9508 <prgn>man</prgn> will automatically detect whether UTF-8 is in
9509 use. In future, all manual pages will be required to use
9515 A country name (the <tt>DE</tt> in <tt>de_DE</tt>) should not be
9516 included in the subdirectory name unless it indicates a
9517 significant difference in the language, as this excludes
9518 speakers of the language in other countries.<footnote>
9519 At the time of writing, Chinese and Portuguese are the main
9520 languages with such differences, so <file>pt_BR</file>,
9521 <file>zh_CN</file>, and <file>zh_TW</file> are all allowed.
9526 If a localized version of a manual page is provided, it should
9527 either be up-to-date or it should be obvious to the reader that
9528 it is outdated and the original manual page should be used
9529 instead. This can be done either by a note at the beginning of
9530 the manual page or by showing the missing or changed portions in
9531 the original language instead of the target language.
9536 <heading>Info documents</heading>
9539 Info documents should be installed in <file>/usr/share/info</file>.
9540 They should be compressed with <tt>gzip -9</tt>.
9544 The <prgn>install-info</prgn> program maintains a directory of
9545 installed info documents in <file>/usr/share/info/dir</file> for
9546 the use of info readers.<footnote>
9547 It was previously necessary for packages installing info
9548 documents to run <prgn>install-info</prgn> from maintainer
9549 scripts. This is no longer necessary. The installation
9550 system now uses dpkg triggers.
9552 This file must not be included in packages. Packages containing
9553 info documents should depend on <tt>dpkg (>= 1.15.4) |
9554 install-info</tt> to ensure that the directory file is properly
9555 rebuilt during partial upgrades from Debian 5.0 (lenny) and
9560 Info documents should contain section and directory entry
9561 information in the document for the use
9562 of <prgn>install-info</prgn>. The section should be specified
9563 via a line starting with <tt>INFO-DIR-SECTION</tt> followed by a
9564 space and the section of this info page. The directory entry or
9565 entries should be included between
9566 a <tt>START-INFO-DIR-ENTRY</tt> line and
9567 an <tt>END-INFO-DIR-ENTRY</tt> line. For example:
9569 INFO-DIR-SECTION Individual utilities
9570 START-INFO-DIR-ENTRY
9571 * example: (example). An example info directory entry.
9574 To determine which section to use, you should look
9575 at <file>/usr/share/info/dir</file> on your system and choose
9576 the most relevant (or create a new section if none of the
9577 current sections are relevant).<footnote>
9578 Normally, info documents are generated from Texinfo source.
9579 To include this information in the generated info document, if
9580 it is absent, add commands like:
9582 @dircategory Individual utilities
9584 * example: (example). An example info directory entry.
9587 to the Texinfo source of the document and ensure that the info
9588 documents are rebuilt from source during the package build.
9594 <heading>Additional documentation</heading>
9597 Any additional documentation that comes with the package may
9598 be installed at the discretion of the package maintainer.
9599 Plain text documentation should be installed in the directory
9600 <file>/usr/share/doc/<var>package</var></file>, where
9601 <var>package</var> is the name of the package, and
9602 compressed with <tt>gzip -9</tt> unless it is small.
9606 If a package comes with large amounts of documentation which
9607 many users of the package will not require you should create
9608 a separate binary package to contain it, so that it does not
9609 take up disk space on the machines of users who do not need
9610 or want it installed.</p>
9613 It is often a good idea to put text information files
9614 (<file>README</file>s, changelogs, and so forth) that come with
9615 the source package in <file>/usr/share/doc/<var>package</var></file>
9616 in the binary package. However, you don't need to install
9617 the instructions for building and installing the package, of
9621 Packages must not require the existence of any files in
9622 <file>/usr/share/doc/</file> in order to function
9624 The system administrator should be able to
9625 delete files in <file>/usr/share/doc/</file> without causing
9626 any programs to break.
9628 Any files that are referenced by programs but are also
9629 useful as stand alone documentation should be installed under
9630 <file>/usr/share/<var>package</var>/</file> with symbolic links from
9631 <file>/usr/share/doc/<var>package</var></file>.
9635 <file>/usr/share/doc/<var>package</var></file> may be a symbolic
9636 link to another directory in <file>/usr/share/doc</file> only if
9637 the two packages both come from the same source and the
9638 first package Depends on the second.<footnote>
9640 Please note that this does not override the section on
9641 changelog files below, so the file
9642 <file>/usr/share/doc/<var>package</var>/changelog.Debian.gz</file>
9643 must refer to the changelog for the current version of
9644 <var>package</var> in question. In practice, this means
9645 that the sources of the target and the destination of the
9646 symlink must be the same (same source package and
9653 Former Debian releases placed all additional documentation
9654 in <file>/usr/doc/<var>package</var></file>. This has been
9655 changed to <file>/usr/share/doc/<var>package</var></file>,
9656 and packages must not put documentation in the directory
9657 <file>/usr/doc/<var>package</var></file>. <footnote>
9658 At this phase of the transition, we no longer require a
9659 symbolic link in <file>/usr/doc/</file>. At a later point,
9660 policy shall change to make the symbolic links a bug.
9666 <heading>Preferred documentation formats</heading>
9669 The unification of Debian documentation is being carried out
9673 If your package comes with extensive documentation in a
9674 markup format that can be converted to various other formats
9675 you should if possible ship HTML versions in a binary
9676 package, in the directory
9677 <file>/usr/share/doc/<var>appropriate-package</var></file> or
9678 its subdirectories.<footnote>
9679 The rationale: The important thing here is that HTML
9680 docs should be available in <em>some</em> package, not
9681 necessarily in the main binary package.
9686 Other formats such as PostScript may be provided at the
9687 package maintainer's discretion.
9691 <sect id="copyrightfile">
9692 <heading>Copyright information</heading>
9695 Every package must be accompanied by a verbatim copy of its
9696 copyright information and distribution license in the file
9697 <file>/usr/share/doc/<var>package</var>/copyright</file>. This
9698 file must neither be compressed nor be a symbolic link.
9702 In addition, the copyright file must say where the upstream
9703 sources (if any) were obtained. It should name the original
9704 authors of the package and the Debian maintainer(s) who were
9705 involved with its creation.
9709 Packages in the <em>contrib</em> or <em>non-free</em> archive
9710 areas should state in the copyright file that the package is not
9711 part of the Debian distribution and briefly explain why.
9715 A copy of the file which will be installed in
9716 <file>/usr/share/doc/<var>package</var>/copyright</file> should
9717 be in <file>debian/copyright</file> in the source package.
9721 <file>/usr/share/doc/<var>package</var></file> may be a symbolic
9722 link to another directory in <file>/usr/share/doc</file> only if
9723 the two packages both come from the same source and the
9724 first package Depends on the second. These rules are
9725 important because copyrights must be extractable by
9730 Packages distributed under the Apache license (version 2.0), the
9731 Artistic license, the GNU GPL (versions 1, 2, or 3), the GNU
9732 LGPL (versions 2, 2.1, or 3), and the GNU FDL (versions 1.2 or
9733 1.3) should refer to the corresponding files
9734 under <file>/usr/share/common-licenses</file>,<footnote>
9737 <file>/usr/share/common-licenses/Apache-2.0</file>,
9738 <file>/usr/share/common-licenses/Artistic</file>,
9739 <file>/usr/share/common-licenses/GPL-1</file>,
9740 <file>/usr/share/common-licenses/GPL-2</file>,
9741 <file>/usr/share/common-licenses/GPL-3</file>,
9742 <file>/usr/share/common-licenses/LGPL-2</file>,
9743 <file>/usr/share/common-licenses/LGPL-2.1</file>,
9744 <file>/usr/share/common-licenses/LGPL-3</file>,
9745 <file>/usr/share/common-licenses/GFDL-1.2</file>, and
9746 <file>/usr/share/common-licenses/GFDL-1.3</file>
9747 respectively. The University of California BSD license is
9748 also included in <package>base-files</package> as
9749 <file>/usr/share/common-licenses/BSD</file>, but given the
9750 brevity of this license, its specificity to code whose
9751 copyright is held by the Regents of the University of
9752 California, and the frequency of minor wording changes, its
9753 text should be included in the copyright file rather than
9754 referencing this file.
9756 </footnote> rather than quoting them in the copyright
9761 You should not use the copyright file as a general <file>README</file>
9762 file. If your package has such a file it should be
9763 installed in <file>/usr/share/doc/<var>package</var>/README</file> or
9764 <file>README.Debian</file> or some other appropriate place.</p>
9768 <heading>Examples</heading>
9771 Any examples (configurations, source files, whatever),
9772 should be installed in a directory
9773 <file>/usr/share/doc/<var>package</var>/examples</file>. These
9774 files should not be referenced by any program: they're there
9775 for the benefit of the system administrator and users as
9776 documentation only. Architecture-specific example files
9777 should be installed in a directory
9778 <file>/usr/lib/<var>package</var>/examples</file> with symbolic
9780 <file>/usr/share/doc/<var>package</var>/examples</file>, or the
9781 latter directory itself may be a symbolic link to the
9786 If the purpose of a package is to provide examples, then the
9787 example files may be installed into
9788 <file>/usr/share/doc/<var>package</var></file>.
9792 <sect id="changelogs">
9793 <heading>Changelog files</heading>
9796 Packages that are not Debian-native must contain a
9797 compressed copy of the <file>debian/changelog</file> file from
9798 the Debian source tree in
9799 <file>/usr/share/doc/<var>package</var></file> with the name
9800 <file>changelog.Debian.gz</file>.
9804 If an upstream changelog is available, it should be accessible as
9805 <file>/usr/share/doc/<var>package</var>/changelog.gz</file> in
9806 plain text. If the upstream changelog is distributed in
9807 HTML, it should be made available in that form as
9808 <file>/usr/share/doc/<var>package</var>/changelog.html.gz</file>
9809 and a plain text <file>changelog.gz</file> should be generated
9810 from it using, for example, <tt>lynx -dump -nolist</tt>. If
9811 the upstream changelog files do not already conform to this
9812 naming convention, then this may be achieved either by
9813 renaming the files, or by adding a symbolic link, at the
9814 maintainer's discretion.<footnote>
9815 Rationale: People should not have to look in places for
9816 upstream changelogs merely because they are given
9817 different names or are distributed in HTML format.
9822 All of these files should be installed compressed using
9823 <tt>gzip -9</tt>, as they will become large with time even
9824 if they start out small.
9828 If the package has only one changelog which is used both as
9829 the Debian changelog and the upstream one because there is
9830 no separate upstream maintainer then that changelog should
9831 usually be installed as
9832 <file>/usr/share/doc/<var>package</var>/changelog.gz</file>; if
9833 there is a separate upstream maintainer, but no upstream
9834 changelog, then the Debian changelog should still be called
9835 <file>changelog.Debian.gz</file>.
9839 For details about the format and contents of the Debian
9840 changelog file, please see <ref id="dpkgchangelog">.
9845 <appendix id="pkg-scope">
9846 <heading>Introduction and scope of these appendices</heading>
9849 These appendices are taken essentially verbatim from the
9850 now-deprecated Packaging Manual, version 3.2.1.0. They are
9851 the chapters which are likely to be of use to package
9852 maintainers and which have not already been included in the
9853 policy document itself. Most of these sections are very likely
9854 not relevant to policy; they should be treated as
9855 documentation for the packaging system. Please note that these
9856 appendices are included for convenience, and for historical
9857 reasons: they used to be part of policy package, and they have
9858 not yet been incorporated into dpkg documentation. However,
9859 they still have value, and hence they are presented here.
9863 They have not yet been checked to ensure that they are
9864 compatible with the contents of policy, and if there are any
9865 contradictions, the version in the main policy document takes
9866 precedence. The remaining chapters of the old Packaging
9867 Manual have also not been read in detail to ensure that there
9868 are not parts which have been left out. Both of these will be
9873 Certain parts of the Packaging manual were integrated into the
9874 Policy Manual proper, and removed from the appendices. Links
9875 have been placed from the old locations to the new ones.
9879 <prgn>dpkg</prgn> is a suite of programs for creating binary
9880 package files and installing and removing them on Unix
9882 <prgn>dpkg</prgn> is targeted primarily at Debian, but may
9883 work on or be ported to other systems.
9888 The binary packages are designed for the management of
9889 installed executable programs (usually compiled binaries) and
9890 their associated data, though source code examples and
9891 documentation are provided as part of some packages.</p>
9894 This manual describes the technical aspects of creating Debian
9895 binary packages (<file>.deb</file> files). It documents the
9896 behavior of the package management programs
9897 <prgn>dpkg</prgn>, <prgn>dselect</prgn> et al. and the way
9898 they interact with packages.</p>
9901 It also documents the interaction between
9902 <prgn>dselect</prgn>'s core and the access method scripts it
9903 uses to actually install the selected packages, and describes
9904 how to create a new access method.</p>
9907 This manual does not go into detail about the options and
9908 usage of the package building and installation tools. It
9909 should therefore be read in conjunction with those programs'
9914 The utility programs which are provided with <prgn>dpkg</prgn>
9915 for managing various system configuration and similar issues,
9916 such as <prgn>update-rc.d</prgn> and
9917 <prgn>install-info</prgn>, are not described in detail here -
9918 please see their man pages.
9922 It is assumed that the reader is reasonably familiar with the
9923 <prgn>dpkg</prgn> System Administrators' manual.
9924 Unfortunately this manual does not yet exist.
9928 The Debian version of the FSF's GNU hello program is provided
9929 as an example for people wishing to create Debian
9930 packages. The Debian <prgn>debmake</prgn> package is
9931 recommended as a very helpful tool in creating and maintaining
9932 Debian packages. However, while the tools and examples are
9933 helpful, they do not replace the need to read and follow the
9934 Policy and Programmer's Manual.</p>
9937 <appendix id="pkg-binarypkg">
9938 <heading>Binary packages (from old Packaging Manual)</heading>
9941 The binary package has two main sections. The first part
9942 consists of various control information files and scripts used
9943 by <prgn>dpkg</prgn> when installing and removing. See <ref
9944 id="pkg-controlarea">.
9948 The second part is an archive containing the files and
9949 directories to be installed.
9953 In the future binary packages may also contain other
9954 components, such as checksums and digital signatures. The
9955 format for the archive is described in full in the
9956 <file>deb(5)</file> man page.
9960 <sect id="pkg-bincreating"><heading>Creating package files -
9961 <prgn>dpkg-deb</prgn>
9965 All manipulation of binary package files is done by
9966 <prgn>dpkg-deb</prgn>; it's the only program that has
9967 knowledge of the format. (<prgn>dpkg-deb</prgn> may be
9968 invoked by calling <prgn>dpkg</prgn>, as <prgn>dpkg</prgn>
9969 will spot that the options requested are appropriate to
9970 <prgn>dpkg-deb</prgn> and invoke that instead with the same
9975 In order to create a binary package you must make a
9976 directory tree which contains all the files and directories
9977 you want to have in the file system data part of the package.
9978 In Debian-format source packages this directory is usually
9979 <file>debian/tmp</file>, relative to the top of the package's
9984 They should have the locations (relative to the root of the
9985 directory tree you're constructing) ownerships and
9986 permissions which you want them to have on the system when
9991 With current versions of <prgn>dpkg</prgn> the uid/username
9992 and gid/groupname mappings for the users and groups being
9993 used should be the same on the system where the package is
9994 built and the one where it is installed.
9998 You need to add one special directory to the root of the
9999 miniature file system tree you're creating:
10000 <prgn>DEBIAN</prgn>. It should contain the control
10001 information files, notably the binary package control file
10002 (see <ref id="pkg-controlfile">).
10006 The <prgn>DEBIAN</prgn> directory will not appear in the
10007 file system archive of the package, and so won't be installed
10008 by <prgn>dpkg</prgn> when the package is unpacked.
10012 When you've prepared the package, you should invoke:
10014 dpkg --build <var>directory</var>
10019 This will build the package in
10020 <file><var>directory</var>.deb</file>. (<prgn>dpkg</prgn> knows
10021 that <tt>--build</tt> is a <prgn>dpkg-deb</prgn> option, so
10022 it invokes <prgn>dpkg-deb</prgn> with the same arguments to
10023 build the package.)
10027 See the man page <manref name="dpkg-deb" section="8"> for details of how
10028 to examine the contents of this newly-created file. You may find the
10029 output of following commands enlightening:
10031 dpkg-deb --info <var>filename</var>.deb
10032 dpkg-deb --contents <var>filename</var>.deb
10033 dpkg --contents <var>filename</var>.deb
10035 To view the copyright file for a package you could use this command:
10037 dpkg --fsys-tarfile <var>filename</var>.deb | tar xOf - --wildcards \*/copyright | pager
10042 <sect id="pkg-controlarea">
10043 <heading>Package control information files</heading>
10046 The control information portion of a binary package is a
10047 collection of files with names known to <prgn>dpkg</prgn>.
10048 It will treat the contents of these files specially - some
10049 of them contain information used by <prgn>dpkg</prgn> when
10050 installing or removing the package; others are scripts which
10051 the package maintainer wants <prgn>dpkg</prgn> to run.
10055 It is possible to put other files in the package control
10056 information file area, but this is not generally a good idea
10057 (though they will largely be ignored).
10061 Here is a brief list of the control information files supported
10062 by <prgn>dpkg</prgn> and a summary of what they're used for.
10067 <tag><tt>control</tt>
10070 This is the key description file used by
10071 <prgn>dpkg</prgn>. It specifies the package's name
10072 and version, gives its description for the user,
10073 states its relationships with other packages, and so
10074 forth. See <ref id="sourcecontrolfiles"> and
10075 <ref id="binarycontrolfiles">.
10079 It is usually generated automatically from information
10080 in the source package by the
10081 <prgn>dpkg-gencontrol</prgn> program, and with
10082 assistance from <prgn>dpkg-shlibdeps</prgn>.
10083 See <ref id="pkg-sourcetools">.
10087 <tag><tt>postinst</tt>, <tt>preinst</tt>, <tt>postrm</tt>,
10092 These are executable files (usually scripts) which
10093 <prgn>dpkg</prgn> runs during installation, upgrade
10094 and removal of packages. They allow the package to
10095 deal with matters which are particular to that package
10096 or require more complicated processing than that
10097 provided by <prgn>dpkg</prgn>. Details of when and
10098 how they are called are in <ref id="maintainerscripts">.
10102 It is very important to make these scripts idempotent.
10103 See <ref id="idempotency">.
10107 The maintainer scripts are not guaranteed to run with a
10108 controlling terminal and may not be able to interact with
10109 the user. See <ref id="controllingterminal">.
10113 <tag><tt>conffiles</tt>
10116 This file contains a list of configuration files which
10117 are to be handled automatically by <prgn>dpkg</prgn>
10118 (see <ref id="pkg-conffiles">). Note that not necessarily
10119 every configuration file should be listed here.
10122 <tag><tt>shlibs</tt>
10125 This file contains a list of the shared libraries
10126 supplied by the package, with dependency details for
10127 each. This is used by <prgn>dpkg-shlibdeps</prgn>
10128 when it determines what dependencies are required in a
10129 package control file. The <tt>shlibs</tt> file format
10130 is described on <ref id="shlibs">.
10135 <sect id="pkg-controlfile">
10136 <heading>The main control information file: <tt>control</tt></heading>
10139 The most important control information file used by
10140 <prgn>dpkg</prgn> when it installs a package is
10141 <tt>control</tt>. It contains all the package's "vital
10146 The binary package control files of packages built from
10147 Debian sources are made by a special tool,
10148 <prgn>dpkg-gencontrol</prgn>, which reads
10149 <file>debian/control</file> and <file>debian/changelog</file> to
10150 find the information it needs. See <ref id="pkg-sourcepkg"> for
10155 The fields in binary package control files are listed in
10156 <ref id="binarycontrolfiles">.
10160 A description of the syntax of control files and the purpose
10161 of the fields is available in <ref id="controlfields">.
10166 <heading>Time Stamps</heading>
10169 See <ref id="timestamps">.
10174 <appendix id="pkg-sourcepkg">
10175 <heading>Source packages (from old Packaging Manual) </heading>
10178 The Debian binary packages in the distribution are generated
10179 from Debian sources, which are in a special format to assist
10180 the easy and automatic building of binaries.
10183 <sect id="pkg-sourcetools">
10184 <heading>Tools for processing source packages</heading>
10187 Various tools are provided for manipulating source packages;
10188 they pack and unpack sources and help build of binary
10189 packages and help manage the distribution of new versions.
10193 They are introduced and typical uses described here; see
10194 <manref name="dpkg-source" section="1"> for full
10195 documentation about their arguments and operation.
10199 For examples of how to construct a Debian source package,
10200 and how to use those utilities that are used by Debian
10201 source packages, please see the <prgn>hello</prgn> example
10205 <sect1 id="pkg-dpkg-source">
10207 <prgn>dpkg-source</prgn> - packs and unpacks Debian source
10212 This program is frequently used by hand, and is also
10213 called from package-independent automated building scripts
10214 such as <prgn>dpkg-buildpackage</prgn>.
10218 To unpack a package it is typically invoked with
10220 dpkg-source -x <var>.../path/to/filename</var>.dsc
10225 with the <file><var>filename</var>.tar.gz</file> and
10226 <file><var>filename</var>.diff.gz</file> (if applicable) in
10227 the same directory. It unpacks into
10228 <file><var>package</var>-<var>version</var></file>, and if
10230 <file><var>package</var>-<var>version</var>.orig</file>, in
10231 the current directory.
10235 To create a packed source archive it is typically invoked:
10237 dpkg-source -b <var>package</var>-<var>version</var>
10242 This will create the <file>.dsc</file>, <file>.tar.gz</file> and
10243 <file>.diff.gz</file> (if appropriate) in the current
10244 directory. <prgn>dpkg-source</prgn> does not clean the
10245 source tree first - this must be done separately if it is
10250 See also <ref id="pkg-sourcearchives">.</p>
10254 <sect1 id="pkg-dpkg-buildpackage">
10256 <prgn>dpkg-buildpackage</prgn> - overall package-building
10261 <prgn>dpkg-buildpackage</prgn> is a script which invokes
10262 <prgn>dpkg-source</prgn>, the <file>debian/rules</file>
10263 targets <tt>clean</tt>, <tt>build</tt> and
10264 <tt>binary</tt>, <prgn>dpkg-genchanges</prgn> and
10265 <prgn>gpg</prgn> (or <prgn>pgp</prgn>) to build a signed
10266 source and binary package upload.
10270 It is usually invoked by hand from the top level of the
10271 built or unbuilt source directory. It may be invoked with
10272 no arguments; useful arguments include:
10273 <taglist compact="compact">
10274 <tag><tt>-uc</tt>, <tt>-us</tt></tag>
10277 Do not sign the <tt>.changes</tt> file or the
10278 source package <tt>.dsc</tt> file, respectively.</p>
10280 <tag><tt>-p<var>sign-command</var></tt></tag>
10283 Invoke <var>sign-command</var> instead of finding
10284 <tt>gpg</tt> or <tt>pgp</tt> on the <prgn>PATH</prgn>.
10285 <var>sign-command</var> must behave just like
10286 <prgn>gpg</prgn> or <tt>pgp</tt>.</p>
10288 <tag><tt>-r<var>root-command</var></tt></tag>
10291 When root privilege is required, invoke the command
10292 <var>root-command</var>. <var>root-command</var>
10293 should invoke its first argument as a command, from
10294 the <prgn>PATH</prgn> if necessary, and pass its
10295 second and subsequent arguments to the command it
10296 calls. If no <var>root-command</var> is supplied
10297 then <var>dpkg-buildpackage</var> will take no
10298 special action to gain root privilege, so that for
10299 most packages it will have to be invoked as root to
10302 <tag><tt>-b</tt>, <tt>-B</tt></tag>
10305 Two types of binary-only build and upload - see
10306 <manref name="dpkg-source" section="1">.
10313 <sect1 id="pkg-dpkg-gencontrol">
10315 <prgn>dpkg-gencontrol</prgn> - generates binary package
10320 This program is usually called from <file>debian/rules</file>
10321 (see <ref id="pkg-sourcetree">) in the top level of the source
10326 This is usually done just before the files and directories in the
10327 temporary directory tree where the package is being built have their
10328 permissions and ownerships set and the package is constructed using
10329 <prgn>dpkg-deb/</prgn>
10331 This is so that the control file which is produced has
10332 the right permissions
10337 <prgn>dpkg-gencontrol</prgn> must be called after all the
10338 files which are to go into the package have been placed in
10339 the temporary build directory, so that its calculation of
10340 the installed size of a package is correct.
10344 It is also necessary for <prgn>dpkg-gencontrol</prgn> to
10345 be run after <prgn>dpkg-shlibdeps</prgn> so that the
10346 variable substitutions created by
10347 <prgn>dpkg-shlibdeps</prgn> in <file>debian/substvars</file>
10352 For a package which generates only one binary package, and
10353 which builds it in <file>debian/tmp</file> relative to the top
10354 of the source package, it is usually sufficient to call
10355 <prgn>dpkg-gencontrol</prgn>.
10359 Sources which build several binaries will typically need
10362 dpkg-gencontrol -Pdebian/tmp-<var>pkg</var> -p<var>package</var>
10363 </example> The <tt>-P</tt> tells
10364 <prgn>dpkg-gencontrol</prgn> that the package is being
10365 built in a non-default directory, and the <tt>-p</tt>
10366 tells it which package's control file should be generated.
10370 <prgn>dpkg-gencontrol</prgn> also adds information to the
10371 list of files in <file>debian/files</file>, for the benefit of
10372 (for example) a future invocation of
10373 <prgn>dpkg-genchanges</prgn>.</p>
10376 <sect1 id="pkg-dpkg-shlibdeps">
10378 <prgn>dpkg-shlibdeps</prgn> - calculates shared library
10383 This program is usually called from <file>debian/rules</file>
10384 just before <prgn>dpkg-gencontrol</prgn> (see <ref
10385 id="pkg-sourcetree">), in the top level of the source tree.
10389 Its arguments are executables and shared libraries
10392 They may be specified either in the locations in the
10393 source tree where they are created or in the locations
10394 in the temporary build tree where they are installed
10395 prior to binary package creation.
10397 </footnote> for which shared library dependencies should
10398 be included in the binary package's control file.
10402 If some of the found shared libraries should only
10403 warrant a <tt>Recommends</tt> or <tt>Suggests</tt>, or if
10404 some warrant a <tt>Pre-Depends</tt>, this can be achieved
10405 by using the <tt>-d<var>dependency-field</var></tt> option
10406 before those executable(s). (Each <tt>-d</tt> option
10407 takes effect until the next <tt>-d</tt>.)
10411 <prgn>dpkg-shlibdeps</prgn> does not directly cause the
10412 output control file to be modified. Instead by default it
10413 adds to the <file>debian/substvars</file> file variable
10414 settings like <tt>shlibs:Depends</tt>. These variable
10415 settings must be referenced in dependency fields in the
10416 appropriate per-binary-package sections of the source
10421 For example, a package that generates an essential part
10422 which requires dependencies, and optional parts that
10423 which only require a recommendation, would separate those
10424 two sets of dependencies into two different fields.<footnote>
10425 At the time of writing, an example for this was the
10426 <package/xmms/ package, with Depends used for the xmms
10427 executable, Recommends for the plug-ins and Suggests for
10428 even more optional features provided by unzip.
10430 It can say in its <file>debian/rules</file>:
10432 dpkg-shlibdeps -dDepends <var>program anotherprogram ...</var> \
10433 -dRecommends <var>optionalpart anotheroptionalpart</var>
10435 and then in its main control file <file>debian/control</file>:
10438 Depends: ${shlibs:Depends}
10439 Recommends: ${shlibs:Recommends}
10445 Sources which produce several binary packages with
10446 different shared library dependency requirements can use
10447 the <tt>-p<var>varnameprefix</var></tt> option to override
10448 the default <tt>shlibs:</tt> prefix (one invocation of
10449 <prgn>dpkg-shlibdeps</prgn> per setting of this option).
10450 They can thus produce several sets of dependency
10451 variables, each of the form
10452 <tt><var>varnameprefix</var>:<var>dependencyfield</var></tt>,
10453 which can be referred to in the appropriate parts of the
10454 binary package control files.
10459 <sect1 id="pkg-dpkg-distaddfile">
10461 <prgn>dpkg-distaddfile</prgn> - adds a file to
10462 <file>debian/files</file>
10466 Some packages' uploads need to include files other than
10467 the source and binary package files.
10471 <prgn>dpkg-distaddfile</prgn> adds a file to the
10472 <file>debian/files</file> file so that it will be included in
10473 the <file>.changes</file> file when
10474 <prgn>dpkg-genchanges</prgn> is run.
10478 It is usually invoked from the <tt>binary</tt> target of
10479 <file>debian/rules</file>:
10481 dpkg-distaddfile <var>filename</var> <var>section</var> <var>priority</var>
10483 The <var>filename</var> is relative to the directory where
10484 <prgn>dpkg-genchanges</prgn> will expect to find it - this
10485 is usually the directory above the top level of the source
10486 tree. The <file>debian/rules</file> target should put the
10487 file there just before or just after calling
10488 <prgn>dpkg-distaddfile</prgn>.
10492 The <var>section</var> and <var>priority</var> are passed
10493 unchanged into the resulting <file>.changes</file> file.
10498 <sect1 id="pkg-dpkg-genchanges">
10500 <prgn>dpkg-genchanges</prgn> - generates a <file>.changes</file>
10501 upload control file
10505 This program is usually called by package-independent
10506 automatic building scripts such as
10507 <prgn>dpkg-buildpackage</prgn>, but it may also be called
10512 It is usually called in the top level of a built source
10513 tree, and when invoked with no arguments will print out a
10514 straightforward <file>.changes</file> file based on the
10515 information in the source package's changelog and control
10516 file and the binary and source packages which should have
10522 <sect1 id="pkg-dpkg-parsechangelog">
10524 <prgn>dpkg-parsechangelog</prgn> - produces parsed
10525 representation of a changelog
10529 This program is used internally by
10530 <prgn>dpkg-source</prgn> et al. It may also occasionally
10531 be useful in <file>debian/rules</file> and elsewhere. It
10532 parses a changelog, <file>debian/changelog</file> by default,
10533 and prints a control-file format representation of the
10534 information in it to standard output.
10538 <sect1 id="pkg-dpkg-architecture">
10540 <prgn>dpkg-architecture</prgn> - information about the build and
10545 This program can be used manually, but is also invoked by
10546 <tt>dpkg-buildpackage</tt> or <file>debian/rules</file> to set
10547 environment or make variables which specify the build and host
10548 architecture for the package building process.
10553 <sect id="pkg-sourcetree">
10554 <heading>The Debian package source tree</heading>
10557 The source archive scheme described later is intended to
10558 allow a Debian package source tree with some associated
10559 control information to be reproduced and transported easily.
10560 The Debian package source tree is a version of the original
10561 program with certain files added for the benefit of the
10562 packaging process, and with any other changes required
10563 made to the rest of the source code and installation
10568 The extra files created for Debian are in the subdirectory
10569 <file>debian</file> of the top level of the Debian package
10570 source tree. They are described below.
10573 <sect1 id="pkg-debianrules">
10574 <heading><file>debian/rules</file> - the main building script</heading>
10577 See <ref id="debianrules">.
10581 <sect1 id="pkg-srcsubstvars">
10582 <heading><file>debian/substvars</file> and variable substitutions</heading>
10585 See <ref id="substvars">.
10591 <heading><file>debian/files</file></heading>
10594 See <ref id="debianfiles">.
10598 <sect1><heading><file>debian/tmp</file>
10602 This is the canonical temporary location for the
10603 construction of binary packages by the <tt>binary</tt>
10604 target. The directory <file>tmp</file> serves as the root of
10605 the file system tree as it is being constructed (for
10606 example, by using the package's upstream makefiles install
10607 targets and redirecting the output there), and it also
10608 contains the <tt>DEBIAN</tt> subdirectory. See <ref
10609 id="pkg-bincreating">.
10613 If several binary packages are generated from the same
10614 source tree it is usual to use several
10615 <file>debian/tmp<var>something</var></file> directories, for
10616 example <file>tmp-a</file> or <file>tmp-doc</file>.
10620 Whatever <file>tmp</file> directories are created and used by
10621 <tt>binary</tt> must of course be removed by the
10622 <tt>clean</tt> target.</p></sect1>
10626 <sect id="pkg-sourcearchives"><heading>Source packages as archives
10630 As it exists on the FTP site, a Debian source package
10631 consists of three related files. You must have the right
10632 versions of all three to be able to use them.
10637 <tag>Debian source control file - <tt>.dsc</tt></tag>
10639 This file is a control file used by <prgn>dpkg-source</prgn>
10640 to extract a source package.
10641 See <ref id="debiansourcecontrolfiles">.
10645 Original source archive -
10647 <var>package</var>_<var>upstream-version</var>.orig.tar.gz
10653 This is a compressed (with <tt>gzip -9</tt>)
10654 <prgn>tar</prgn> file containing the source code from
10655 the upstream authors of the program.
10660 Debian package diff -
10662 <var>package</var>_<var>upstream_version-revision</var>.diff.gz
10668 This is a unified context diff (<tt>diff -u</tt>)
10669 giving the changes which are required to turn the
10670 original source into the Debian source. These changes
10671 may only include editing and creating plain files.
10672 The permissions of files, the targets of symbolic
10673 links and the characteristics of special files or
10674 pipes may not be changed and no files may be removed
10679 All the directories in the diff must exist, except the
10680 <file>debian</file> subdirectory of the top of the source
10681 tree, which will be created by
10682 <prgn>dpkg-source</prgn> if necessary when unpacking.
10686 The <prgn>dpkg-source</prgn> program will
10687 automatically make the <file>debian/rules</file> file
10688 executable (see below).</p></item>
10693 If there is no original source code - for example, if the
10694 package is specially prepared for Debian or the Debian
10695 maintainer is the same as the upstream maintainer - the
10696 format is slightly different: then there is no diff, and the
10698 <file><var>package</var>_<var>version</var>.tar.gz</file>,
10699 and preferably contains a directory named
10700 <file><var>package</var>-<var>version</var></file>.
10705 <heading>Unpacking a Debian source package without <prgn>dpkg-source</prgn></heading>
10708 <tt>dpkg-source -x</tt> is the recommended way to unpack a
10709 Debian source package. However, if it is not available it
10710 is possible to unpack a Debian source archive as follows:
10711 <enumlist compact="compact">
10714 Untar the tarfile, which will create a <file>.orig</file>
10718 <p>Rename the <file>.orig</file> directory to
10719 <file><var>package</var>-<var>version</var></file>.</p>
10723 Create the subdirectory <file>debian</file> at the top of
10724 the source tree.</p>
10726 <item><p>Apply the diff using <tt>patch -p0</tt>.</p>
10728 <item><p>Untar the tarfile again if you want a copy of the original
10729 source code alongside the Debian version.</p>
10734 It is not possible to generate a valid Debian source archive
10735 without using <prgn>dpkg-source</prgn>. In particular,
10736 attempting to use <prgn>diff</prgn> directly to generate the
10737 <file>.diff.gz</file> file will not work.
10741 <heading>Restrictions on objects in source packages</heading>
10744 The source package may not contain any hard links
10746 This is not currently detected when building source
10747 packages, but only when extracting
10751 Hard links may be permitted at some point in the
10752 future, but would require a fair amount of
10754 </footnote>, device special files, sockets or setuid or
10757 Setgid directories are allowed.
10762 The source packaging tools manage the changes between the
10763 original and Debian source using <prgn>diff</prgn> and
10764 <prgn>patch</prgn>. Turning the original source tree as
10765 included in the <file>.orig.tar.gz</file> into the Debian
10766 package source must not involve any changes which cannot be
10767 handled by these tools. Problematic changes which cause
10768 <prgn>dpkg-source</prgn> to halt with an error when
10769 building the source package are:
10770 <list compact="compact">
10771 <item><p>Adding or removing symbolic links, sockets or pipes.</p>
10773 <item><p>Changing the targets of symbolic links.</p>
10775 <item><p>Creating directories, other than <file>debian</file>.</p>
10777 <item><p>Changes to the contents of binary files.</p></item>
10778 </list> Changes which cause <prgn>dpkg-source</prgn> to
10779 print a warning but continue anyway are:
10780 <list compact="compact">
10783 Removing files, directories or symlinks.
10785 Renaming a file is not treated specially - it is
10786 seen as the removal of the old file (which
10787 generates a warning, but is otherwise ignored),
10788 and the creation of the new one.
10794 Changed text files which are missing the usual final
10795 newline (either in the original or the modified
10800 Changes which are not represented, but which are not detected by
10801 <prgn>dpkg-source</prgn>, are:
10802 <list compact="compact">
10803 <item><p>Changing the permissions of files (other than
10804 <file>debian/rules</file>) and directories.</p></item>
10809 The <file>debian</file> directory and <file>debian/rules</file>
10810 are handled specially by <prgn>dpkg-source</prgn> - before
10811 applying the changes it will create the <file>debian</file>
10812 directory, and afterwards it will make
10813 <file>debian/rules</file> world-executable.
10819 <appendix id="pkg-controlfields">
10820 <heading>Control files and their fields (from old Packaging Manual)</heading>
10823 Many of the tools in the <prgn>dpkg</prgn> suite manipulate
10824 data in a common format, known as control files. Binary and
10825 source packages have control data as do the <file>.changes</file>
10826 files which control the installation of uploaded files, and
10827 <prgn>dpkg</prgn>'s internal databases are in a similar
10832 <heading>Syntax of control files</heading>
10835 See <ref id="controlsyntax">.
10839 It is important to note that there are several fields which
10840 are optional as far as <prgn>dpkg</prgn> and the related
10841 tools are concerned, but which must appear in every Debian
10842 package, or whose omission may cause problems.
10847 <heading>List of fields</heading>
10850 See <ref id="controlfieldslist">.
10854 This section now contains only the fields that didn't belong
10855 to the Policy manual.
10858 <sect1 id="pkg-f-Filename">
10859 <heading><tt>Filename</tt> and <tt>MSDOS-Filename</tt></heading>
10862 These fields in <tt>Packages</tt> files give the
10863 filename(s) of (the parts of) a package in the
10864 distribution directories, relative to the root of the
10865 Debian hierarchy. If the package has been split into
10866 several parts the parts are all listed in order, separated
10871 <sect1 id="pkg-f-Size">
10872 <heading><tt>Size</tt> and <tt>MD5sum</tt></heading>
10875 These fields in <file>Packages</file> files give the size (in
10876 bytes, expressed in decimal) and MD5 checksum of the
10877 file(s) which make(s) up a binary package in the
10878 distribution. If the package is split into several parts
10879 the values for the parts are listed in order, separated by
10884 <sect1 id="pkg-f-Status">
10885 <heading><tt>Status</tt></heading>
10888 This field in <prgn>dpkg</prgn>'s status file records
10889 whether the user wants a package installed, removed or
10890 left alone, whether it is broken (requiring
10891 re-installation) or not and what its current state on the
10892 system is. Each of these pieces of information is a
10897 <sect1 id="pkg-f-Config-Version">
10898 <heading><tt>Config-Version</tt></heading>
10901 If a package is not installed or not configured, this
10902 field in <prgn>dpkg</prgn>'s status file records the last
10903 version of the package which was successfully
10908 <sect1 id="pkg-f-Conffiles">
10909 <heading><tt>Conffiles</tt></heading>
10912 This field in <prgn>dpkg</prgn>'s status file contains
10913 information about the automatically-managed configuration
10914 files held by a package. This field should <em>not</em>
10915 appear anywhere in a package!
10920 <heading>Obsolete fields</heading>
10923 These are still recognized by <prgn>dpkg</prgn> but should
10924 not appear anywhere any more.
10926 <taglist compact="compact">
10928 <tag><tt>Revision</tt></tag>
10929 <tag><tt>Package-Revision</tt></tag>
10930 <tag><tt>Package_Revision</tt></tag>
10932 The Debian revision part of the package version was
10933 at one point in a separate control field. This
10934 field went through several names.
10937 <tag><tt>Recommended</tt></tag>
10938 <item>Old name for <tt>Recommends</tt>.</item>
10940 <tag><tt>Optional</tt></tag>
10941 <item>Old name for <tt>Suggests</tt>.</item>
10943 <tag><tt>Class</tt></tag>
10944 <item>Old name for <tt>Priority</tt>.</item>
10953 <appendix id="pkg-conffiles">
10954 <heading>Configuration file handling (from old Packaging Manual)</heading>
10957 <prgn>dpkg</prgn> can do a certain amount of automatic
10958 handling of package configuration files.
10962 Whether this mechanism is appropriate depends on a number of
10963 factors, but basically there are two approaches to any
10964 particular configuration file.
10968 The easy method is to ship a best-effort configuration in the
10969 package, and use <prgn>dpkg</prgn>'s conffile mechanism to
10970 handle updates. If the user is unlikely to want to edit the
10971 file, but you need them to be able to without losing their
10972 changes, and a new package with a changed version of the file
10973 is only released infrequently, this is a good approach.
10977 The hard method is to build the configuration file from
10978 scratch in the <prgn>postinst</prgn> script, and to take the
10979 responsibility for fixing any mistakes made in earlier
10980 versions of the package automatically. This will be
10981 appropriate if the file is likely to need to be different on
10985 <sect><heading>Automatic handling of configuration files by
10990 A package may contain a control information file called
10991 <tt>conffiles</tt>. This file should be a list of filenames
10992 of configuration files needing automatic handling, separated
10993 by newlines. The filenames should be absolute pathnames,
10994 and the files referred to should actually exist in the
10999 When a package is upgraded <prgn>dpkg</prgn> will process
11000 the configuration files during the configuration stage,
11001 shortly before it runs the package's <prgn>postinst</prgn>
11006 For each file it checks to see whether the version of the
11007 file included in the package is the same as the one that was
11008 included in the last version of the package (the one that is
11009 being upgraded from); it also compares the version currently
11010 installed on the system with the one shipped with the last
11015 If neither the user nor the package maintainer has changed
11016 the file, it is left alone. If one or the other has changed
11017 their version, then the changed version is preferred - i.e.,
11018 if the user edits their file, but the package maintainer
11019 doesn't ship a different version, the user's changes will
11020 stay, silently, but if the maintainer ships a new version
11021 and the user hasn't edited it the new version will be
11022 installed (with an informative message). If both have
11023 changed their version the user is prompted about the problem
11024 and must resolve the differences themselves.
11028 The comparisons are done by calculating the MD5 message
11029 digests of the files, and storing the MD5 of the file as it
11030 was included in the most recent version of the package.
11034 When a package is installed for the first time
11035 <prgn>dpkg</prgn> will install the file that comes with it,
11036 unless that would mean overwriting a file already on the
11041 However, note that <prgn>dpkg</prgn> will <em>not</em>
11042 replace a conffile that was removed by the user (or by a
11043 script). This is necessary because with some programs a
11044 missing file produces an effect hard or impossible to
11045 achieve in another way, so that a missing file needs to be
11046 kept that way if the user did it.
11050 Note that a package should <em>not</em> modify a
11051 <prgn>dpkg</prgn>-handled conffile in its maintainer
11052 scripts. Doing this will lead to <prgn>dpkg</prgn> giving
11053 the user confusing and possibly dangerous options for
11054 conffile update when the package is upgraded.</p>
11057 <sect><heading>Fully-featured maintainer script configuration
11062 For files which contain site-specific information such as
11063 the hostname and networking details and so forth, it is
11064 better to create the file in the package's
11065 <prgn>postinst</prgn> script.
11069 This will typically involve examining the state of the rest
11070 of the system to determine values and other information, and
11071 may involve prompting the user for some information which
11072 can't be obtained some other way.
11076 When using this method there are a couple of important
11077 issues which should be considered:
11081 If you discover a bug in the program which generates the
11082 configuration file, or if the format of the file changes
11083 from one version to the next, you will have to arrange for
11084 the postinst script to do something sensible - usually this
11085 will mean editing the installed configuration file to remove
11086 the problem or change the syntax. You will have to do this
11087 very carefully, since the user may have changed the file,
11088 perhaps to fix the very problem that your script is trying
11089 to deal with - you will have to detect these situations and
11090 deal with them correctly.
11094 If you do go down this route it's probably a good idea to
11095 make the program that generates the configuration file(s) a
11096 separate program in <file>/usr/sbin</file>, by convention called
11097 <file><var>package</var>config</file> and then run that if
11098 appropriate from the post-installation script. The
11099 <tt><var>package</var>config</tt> program should not
11100 unquestioningly overwrite an existing configuration - if its
11101 mode of operation is geared towards setting up a package for
11102 the first time (rather than any arbitrary reconfiguration
11103 later) you should have it check whether the configuration
11104 already exists, and require a <tt>--force</tt> flag to
11105 overwrite it.</p></sect>
11108 <appendix id="pkg-alternatives"><heading>Alternative versions of
11109 an interface - <prgn>update-alternatives</prgn> (from old
11114 When several packages all provide different versions of the
11115 same program or file it is useful to have the system select a
11116 default, but to allow the system administrator to change it
11117 and have their decisions respected.
11121 For example, there are several versions of the <prgn>vi</prgn>
11122 editor, and there is no reason to prevent all of them from
11123 being installed at once, each under their own name
11124 (<prgn>nvi</prgn>, <prgn>vim</prgn> or whatever).
11125 Nevertheless it is desirable to have the name <tt>vi</tt>
11126 refer to something, at least by default.
11130 If all the packages involved cooperate, this can be done with
11131 <prgn>update-alternatives</prgn>.
11135 Each package provides its own version under its own name, and
11136 calls <prgn>update-alternatives</prgn> in its postinst to
11137 register its version (and again in its prerm to deregister
11142 See the man page <manref name="update-alternatives"
11143 section="8"> for details.
11147 If <prgn>update-alternatives</prgn> does not seem appropriate
11148 you may wish to consider using diversions instead.</p>
11151 <appendix id="pkg-diversions"><heading>Diversions - overriding a
11152 package's version of a file (from old Packaging Manual)
11156 It is possible to have <prgn>dpkg</prgn> not overwrite a file
11157 when it reinstalls the package it belongs to, and to have it
11158 put the file from the package somewhere else instead.
11162 This can be used locally to override a package's version of a
11163 file, or by one package to override another's version (or
11164 provide a wrapper for it).
11168 Before deciding to use a diversion, read <ref
11169 id="pkg-alternatives"> to see if you really want a diversion
11170 rather than several alternative versions of a program.
11174 There is a diversion list, which is read by <prgn>dpkg</prgn>,
11175 and updated by a special program <prgn>dpkg-divert</prgn>.
11176 Please see <manref name="dpkg-divert" section="8"> for full
11177 details of its operation.
11181 When a package wishes to divert a file from another, it should
11182 call <prgn>dpkg-divert</prgn> in its preinst to add the
11183 diversion and rename the existing file. For example,
11184 supposing that a <prgn>smailwrapper</prgn> package wishes to
11185 install a wrapper around <file>/usr/sbin/smail</file>:
11187 dpkg-divert --package smailwrapper --add --rename \
11188 --divert /usr/sbin/smail.real /usr/sbin/smail
11189 </example> The <tt>--package smailwrapper</tt> ensures that
11190 <prgn>smailwrapper</prgn>'s copy of <file>/usr/sbin/smail</file>
11191 can bypass the diversion and get installed as the true version.
11192 It's safe to add the diversion unconditionally on upgrades since
11193 it will be left unchanged if it already exists, but
11194 <prgn>dpkg-divert</prgn> will display a message. To suppress that
11195 message, make the command conditional on the version from which
11196 the package is being upgraded:
11198 if [ upgrade != "$1" ] || dpkg --compare-versions "$2" lt 1.0-2; then
11199 dpkg-divert --package smailwrapper --add --rename \
11200 --divert /usr/sbin/smail.real /usr/sbin/smail
11202 </example> where <tt>1.0-2</tt> is the version at which the
11203 diversion was first added to the package. Running the command
11204 during abort-upgrade is pointless but harmless.
11208 The postrm has to do the reverse:
11210 if [ remove = "$1" -o abort-install = "$1" -o disappear = "$1" ]; then
11211 dpkg-divert --package smailwrapper --remove --rename \
11212 --divert /usr/sbin/smail.real /usr/sbin/smail
11214 </example> If the diversion was added at a particular version, the
11215 postrm should also handle the failure case of upgrading from an
11216 older version (unless the older version is so old that direct
11217 upgrades are no longer supported):
11219 if [ abort-upgrade = "$1" ] && dpkg --compare-versions "$2" lt 1.0-2; then
11220 dpkg-divert --package smailwrapper --remove --rename \
11221 --divert /usr/sbin/smail.real /usr/sbin/smail
11223 </example> where <tt>1.02-2</tt> is the version at which the
11224 diversion was first added to the package. The postrm should not
11225 remove the diversion on upgrades both because there's no reason to
11226 remove the diversion only to immediately re-add it and since the
11227 postrm of the old package is run after unpacking so the removal of
11228 the diversion will fail.
11232 Do not attempt to divert a file which is vitally important for
11233 the system's operation - when using <prgn>dpkg-divert</prgn>
11234 there is a time, after it has been diverted but before
11235 <prgn>dpkg</prgn> has installed the new version, when the file
11236 does not exist.</p>
11241 <!-- Local variables: -->
11242 <!-- indent-tabs-mode: t -->
11244 <!-- vim:set ai et sts=2 sw=2 tw=76: -->