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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>Russ Allbery</item>
223 <item>Bill Allombert</item>
224 <item>Andrew McMillan</item>
225 <item>Manoj Srivastava</item>
226 <item>Colin Watson</item>
231 While the authors of this document have tried hard to avoid
232 typos and other errors, these do still occur. If you discover
233 an error in this manual or if you want to give any
234 comments, suggestions, or criticisms please send an email to
235 the Debian Policy List,
236 <email>debian-policy@lists.debian.org</email>, or submit a
237 bug report against the <tt>debian-policy</tt> package.
241 Please do not try to reach the individual authors or maintainers
242 of the Policy Manual regarding changes to the Policy.
247 <heading>Related documents</heading>
250 There are several other documents other than this Policy Manual
251 that are necessary to fully understand some Debian policies and
256 The external "sub-policy" documents are referred to in:
257 <list compact="compact">
258 <item><ref id="fhs"></item>
259 <item><ref id="virtual_pkg"></item>
260 <item><ref id="menus"></item>
261 <item><ref id="mime"></item>
262 <item><ref id="perl"></item>
263 <item><ref id="maintscriptprompt"></item>
264 <item><ref id="emacs"></item>
269 In addition to those, which carry the weight of policy, there
270 is the Debian Developer's Reference. This document describes
271 procedures and resources for Debian developers, but it is
272 <em>not</em> normative; rather, it includes things that don't
273 belong in the Policy, such as best practices for developers.
277 The Developer's Reference is available in the
278 <package>developers-reference</package> package.
279 It's also available from the Debian web mirrors at
280 <tt><url name="/doc/developers-reference/"
281 id="http://www.debian.org/doc/developers-reference/"></tt>.
285 <sect id="definitions">
286 <heading>Definitions</heading>
289 The following terms are used in this Policy Manual:
293 The character encoding specified by ANSI X3.4-1986 and its
294 predecessor standards, referred to in MIME as US-ASCII, and
295 corresponding to an encoding in eight bits per character of
296 the first 128 <url id="http://www.unicode.org/"
297 name="Unicode"> characters, with the eighth bit always zero.
301 The transformation format (sometimes called encoding) of
302 <url id="http://www.unicode.org/" name="Unicode"> defined by
303 <url id="http://www.rfc-editor.org/rfc/rfc3629.txt"
304 name="RFC 3629">. UTF-8 has the useful property of having
305 ASCII as a subset, so any text encoded in ASCII is trivially
315 <heading>The Debian Archive</heading>
318 The Debian system is maintained and distributed as a
319 collection of <em>packages</em>. Since there are so many of
320 them (currently well over 15000), they are split into
321 <em>sections</em> and given <em>priorities</em> to simplify
322 the handling of them.
326 The effort of the Debian project is to build a free operating
327 system, but not every package we want to make accessible is
328 <em>free</em> in our sense (see the Debian Free Software
329 Guidelines, below), or may be imported/exported without
330 restrictions. Thus, the archive is split into areas<footnote>
331 The Debian archive software uses the term "component" internally
332 and in the Release file format to refer to the division of an
333 archive. The Debian Social Contract simply refers to "areas."
334 This document uses terminology similar to the Social Contract.
335 </footnote> based on their licenses and other restrictions.
339 The aims of this are:
341 <list compact="compact">
342 <item>to allow us to make as much software available as we can</item>
343 <item>to allow us to encourage everyone to write free software,
345 <item>to allow us to make it easy for people to produce
346 CD-ROMs of our system without violating any licenses,
347 import/export restrictions, or any other laws.</item>
352 The <em>main</em> archive area forms the <em>Debian distribution</em>.
356 Packages in the other archive areas (<tt>contrib</tt>,
357 <tt>non-free</tt>) are not considered to be part of the Debian
358 distribution, although we support their use and provide
359 infrastructure for them (such as our bug-tracking system and
360 mailing lists). This Debian Policy Manual applies to these
365 <heading>The Debian Free Software Guidelines</heading>
367 The Debian Free Software Guidelines (DFSG) form our
368 definition of "free software". These are:
370 <tag>1. Free Redistribution
373 The license of a Debian component may not restrict any
374 party from selling or giving away the software as a
375 component of an aggregate software distribution
376 containing programs from several different
377 sources. The license may not require a royalty or
378 other fee for such sale.
383 The program must include source code, and must allow
384 distribution in source code as well as compiled form.
386 <tag>3. Derived Works
389 The license must allow modifications and derived
390 works, and must allow them to be distributed under the
391 same terms as the license of the original software.
393 <tag>4. Integrity of The Author's Source Code
396 The license may restrict source-code from being
397 distributed in modified form <em>only</em> if the
398 license allows the distribution of "patch files"
399 with the source code for the purpose of modifying the
400 program at build time. The license must explicitly
401 permit distribution of software built from modified
402 source code. The license may require derived works to
403 carry a different name or version number from the
404 original software. (This is a compromise. The Debian
405 Project encourages all authors to not restrict any
406 files, source or binary, from being modified.)
408 <tag>5. No Discrimination Against Persons or Groups
411 The license must not discriminate against any person
414 <tag>6. No Discrimination Against Fields of Endeavor
417 The license must not restrict anyone from making use
418 of the program in a specific field of endeavor. For
419 example, it may not restrict the program from being
420 used in a business, or from being used for genetic
423 <tag>7. Distribution of License
426 The rights attached to the program must apply to all
427 to whom the program is redistributed without the need
428 for execution of an additional license by those
431 <tag>8. License Must Not Be Specific to Debian
434 The rights attached to the program must not depend on
435 the program's being part of a Debian system. If the
436 program is extracted from Debian and used or
437 distributed without Debian but otherwise within the
438 terms of the program's license, all parties to whom
439 the program is redistributed must have the same
440 rights as those that are granted in conjunction with
443 <tag>9. License Must Not Contaminate Other Software
446 The license must not place restrictions on other
447 software that is distributed along with the licensed
448 software. For example, the license must not insist
449 that all other programs distributed on the same medium
450 must be free software.
452 <tag>10. Example Licenses
455 The "GPL," "BSD," and "Artistic" licenses are examples of
456 licenses that we consider <em>free</em>.
463 <heading>Archive areas</heading>
466 <heading>The main archive area</heading>
469 The <em>main</em> archive area comprises the Debian
470 distribution. Only the packages in this area are considered
471 part of the distribution. None of the packages in
472 the <em>main</em> archive area require software outside of
473 that area to function. Anyone may use, share, modify and
474 redistribute the packages in this archive area
476 See <url id="http://www.debian.org/intro/free"
477 name="What Does Free Mean?"> for
478 more about what we mean by free software.
483 Every package in <em>main</em> must comply with the DFSG
484 (Debian Free Software Guidelines).
488 In addition, the packages in <em>main</em>
489 <list compact="compact">
491 must not require a package outside of <em>main</em>
492 for compilation or execution (thus, the package must
493 not declare a "Depends", "Recommends", or
494 "Build-Depends" relationship on a non-<em>main</em>
498 must not be so buggy that we refuse to support them,
502 must meet all policy requirements presented in this
511 <heading>The contrib archive area</heading>
514 The <em>contrib</em> archive area contains supplemental
515 packages intended to work with the Debian distribution, but
516 which require software outside of the distribution to either
521 Every package in <em>contrib</em> must comply with the DFSG.
525 In addition, the packages in <em>contrib</em>
526 <list compact="compact">
528 must not be so buggy that we refuse to support them,
532 must meet all policy requirements presented in this
539 Examples of packages which would be included in
540 <em>contrib</em> are:
541 <list compact="compact">
543 free packages which require <em>contrib</em>,
544 <em>non-free</em> packages or packages which are not
545 in our archive at all for compilation or execution,
549 wrapper packages or other sorts of free accessories for
556 <sect1 id="non-free">
557 <heading>The non-free archive area</heading>
560 The <em>non-free</em> archive area contains supplemental
561 packages intended to work with the Debian distribution that do
562 not comply with the DFSG or have other problems that make
563 their distribution problematic. They may not comply with all
564 of the policy requirements in this manual due to restrictions
565 on modifications or other limitations.
569 Packages must be placed in <em>non-free</em> if they are
570 not compliant with the DFSG or are encumbered by patents
571 or other legal issues that make their distribution
576 In addition, the packages in <em>non-free</em>
577 <list compact="compact">
579 must not be so buggy that we refuse to support them,
583 must meet all policy requirements presented in this
584 manual that it is possible for them to meet.
586 It is possible that there are policy
587 requirements which the package is unable to
588 meet, for example, if the source is
589 unavailable. These situations will need to be
590 handled on a case-by-case basis.
599 <sect id="pkgcopyright">
600 <heading>Copyright considerations</heading>
603 Every package must be accompanied by a verbatim copy of its
604 copyright information and distribution license in the file
605 <file>/usr/share/doc/<var>package</var>/copyright</file>
606 (see <ref id="copyrightfile"> for further details).
610 We reserve the right to restrict files from being included
611 anywhere in our archives if
612 <list compact="compact">
614 their use or distribution would break a law,
617 there is an ethical conflict in their distribution or
621 we would have to sign a license for them, or
624 their distribution would conflict with other project
631 Programs whose authors encourage the user to make
632 donations are fine for the main distribution, provided
633 that the authors do not claim that not donating is
634 immoral, unethical, illegal or something similar; in such
635 a case they must go in <em>non-free</em>.
639 Packages whose copyright permission notices (or patent
640 problems) do not even allow redistribution of binaries
641 only, and where no special permission has been obtained,
642 must not be placed on the Debian FTP site and its mirrors
647 Note that under international copyright law (this applies
648 in the United States, too), <em>no</em> distribution or
649 modification of a work is allowed without an explicit
650 notice saying so. Therefore a program without a copyright
651 notice <em>is</em> copyrighted and you may not do anything
652 to it without risking being sued! Likewise if a program
653 has a copyright notice but no statement saying what is
654 permitted then nothing is permitted.
658 Many authors are unaware of the problems that restrictive
659 copyrights (or lack of copyright notices) can cause for
660 the users of their supposedly-free software. It is often
661 worthwhile contacting such authors diplomatically to ask
662 them to modify their license terms. However, this can be a
663 politically difficult thing to do and you should ask for
664 advice on the <tt>debian-legal</tt> mailing list first, as
669 When in doubt about a copyright, send mail to
670 <email>debian-legal@lists.debian.org</email>. Be prepared
671 to provide us with the copyright statement. Software
672 covered by the GPL, public domain software and BSD-like
673 copyrights are safe; be wary of the phrases "commercial
674 use prohibited" and "distribution restricted".
678 <sect id="subsections">
679 <heading>Sections</heading>
682 The packages in the archive areas <em>main</em>,
683 <em>contrib</em> and <em>non-free</em> are grouped further into
684 <em>sections</em> to simplify handling.
688 The archive area and section for each package should be
689 specified in the package's <tt>Section</tt> control record (see
690 <ref id="f-Section">). However, the maintainer of the Debian
691 archive may override this selection to ensure the consistency of
692 the Debian distribution. The <tt>Section</tt> field should be
694 <list compact="compact">
696 <em>section</em> if the package is in the
697 <em>main</em> archive area,
700 <em>area/section</em> if the package is in
701 the <em>contrib</em> or <em>non-free</em>
708 The Debian archive maintainers provide the authoritative
709 list of sections. At present, they are:
710 <em>admin</em>, <em>cli-mono</em>, <em>comm</em>, <em>database</em>,
711 <em>devel</em>, <em>debug</em>, <em>doc</em>, <em>editors</em>,
712 <em>electronics</em>, <em>embedded</em>, <em>fonts</em>,
713 <em>games</em>, <em>gnome</em>, <em>graphics</em>, <em>gnu-r</em>,
714 <em>gnustep</em>, <em>hamradio</em>, <em>haskell</em>,
715 <em>httpd</em>, <em>interpreters</em>, <em>java</em>, <em>kde</em>,
716 <em>kernel</em>, <em>libs</em>, <em>libdevel</em>, <em>lisp</em>,
717 <em>localization</em>, <em>mail</em>, <em>math</em>, <em>misc</em>,
718 <em>net</em>, <em>news</em>, <em>ocaml</em>, <em>oldlibs</em>,
719 <em>otherosfs</em>, <em>perl</em>, <em>php</em>, <em>python</em>,
720 <em>ruby</em>, <em>science</em>, <em>shells</em>, <em>sound</em>,
721 <em>tex</em>, <em>text</em>, <em>utils</em>, <em>vcs</em>,
722 <em>video</em>, <em>web</em>, <em>x11</em>, <em>xfce</em>,
723 <em>zope</em>. The additional section <em>debian-installer</em>
724 contains special packages used by the installer and is not used
725 for normal Debian packages.
729 For more information about the sections and their definitions,
730 see the <url id="http://packages.debian.org/unstable/"
731 name="list of sections in unstable">.
735 <sect id="priorities">
736 <heading>Priorities</heading>
739 Each package should have a <em>priority</em> value, which is
740 included in the package's <em>control record</em>
741 (see <ref id="f-Priority">).
742 This information is used by the Debian package management tools to
743 separate high-priority packages from less-important packages.
747 The following <em>priority levels</em> are recognized by the
748 Debian package management tools.
750 <tag><tt>required</tt></tag>
752 Packages which are necessary for the proper
753 functioning of the system (usually, this means that
754 dpkg functionality depends on these packages).
755 Removing a <tt>required</tt> package may cause your
756 system to become totally broken and you may not even
757 be able to use <prgn>dpkg</prgn> to put things back,
758 so only do so if you know what you are doing. Systems
759 with only the <tt>required</tt> packages are probably
760 unusable, but they do have enough functionality to
761 allow the sysadmin to boot and install more software.
763 <tag><tt>important</tt></tag>
765 Important programs, including those which one would
766 expect to find on any Unix-like system. If the
767 expectation is that an experienced Unix person who
768 found it missing would say "What on earth is going on,
769 where is <prgn>foo</prgn>?", it must be an
770 <tt>important</tt> package.<footnote>
771 This is an important criterion because we are
772 trying to produce, amongst other things, a free
775 Other packages without which the system will not run
776 well or be usable must also have priority
777 <tt>important</tt>. This does
778 <em>not</em> include Emacs, the X Window System, TeX
779 or any other large applications. The
780 <tt>important</tt> packages are just a bare minimum of
781 commonly-expected and necessary tools.
783 <tag><tt>standard</tt></tag>
785 These packages provide a reasonably small but not too
786 limited character-mode system. This is what will be
787 installed by default if the user doesn't select anything
788 else. It doesn't include many large applications.
790 <tag><tt>optional</tt></tag>
792 (In a sense everything that isn't required is
793 optional, but that's not what is meant here.) This is
794 all the software that you might reasonably want to
795 install if you didn't know what it was and don't have
796 specialized requirements. This is a much larger system
797 and includes the X Window System, a full TeX
798 distribution, and many applications. Note that
799 optional packages should not conflict with each other.
801 <tag><tt>extra</tt></tag>
803 This contains all packages that conflict with others
804 with required, important, standard or optional
805 priorities, or are only likely to be useful if you
806 already know what they are or have specialized
807 requirements (such as packages containing only detached
814 Packages must not depend on packages with lower priority
815 values (excluding build-time dependencies). In order to
816 ensure this, the priorities of one or more packages may need
825 <heading>Binary packages</heading>
828 The Debian distribution is based on the Debian
829 package management system, called <prgn>dpkg</prgn>. Thus,
830 all packages in the Debian distribution must be provided
831 in the <tt>.deb</tt> file format.
835 A <tt>.deb</tt> package contains two sets of files: a set of files
836 to install on the system when the package is installed, and a set
837 of files that provide additional metadata about the package or
838 which are executed when the package is installed or removed. This
839 second set of files is called <em>control information files</em>.
840 Among those files are the package maintainer scripts
841 and <file>control</file>, the <qref id="binarycontrolfiles">binary
842 package control file</qref> that contains the control fields for
843 the package. Other control information files
844 include <qref id="sharedlibs-shlibdeps">the <file>shlibs</file>
845 file</qref> used to store shared library dependency information
846 and the <file>conffiles</file> file that lists the package's
847 configuration files (described in <ref id="config-files">).
851 There is unfortunately a collision of terminology here between
852 control information files and files in the Debian control file
853 format. Throughout this document, a <em>control file</em> refers
854 to a file in the Debian control file format. These files are
855 documented in <ref id="controlfields">. Only files referred to
856 specifically as <em>control information files</em> are the files
857 included in the control information file member of
858 the <file>.deb</file> file format used by binary packages. Most
859 control information files are not in the Debian control file
864 <heading>The package name</heading>
867 Every package must have a name that's unique within the Debian
872 The package name is included in the control field
873 <tt>Package</tt>, the format of which is described
874 in <ref id="f-Package">.
875 The package name is also included as a part of the file name
876 of the <tt>.deb</tt> file.
881 <heading>The version of a package</heading>
884 Every package has a version number recorded in its
885 <tt>Version</tt> control file field, described in
886 <ref id="f-Version">.
890 The package management system imposes an ordering on version
891 numbers, so that it can tell whether packages are being up- or
892 downgraded and so that package system front end applications
893 can tell whether a package it finds available is newer than
894 the one installed on the system. The version number format
895 has the most significant parts (as far as comparison is
896 concerned) at the beginning.
900 If an upstream package has problematic version numbers they
901 should be converted to a sane form for use in the
902 <tt>Version</tt> field.
906 <heading>Version numbers based on dates</heading>
909 In general, Debian packages should use the same version
910 numbers as the upstream sources. However, upstream version
911 numbers based on some date formats (sometimes used for
912 development or "snapshot" releases) will not be ordered
913 correctly by the package management software. For
914 example, <prgn>dpkg</prgn> will consider "96May01" to be
915 greater than "96Dec24".
919 To prevent having to use epochs for every new upstream
920 version, the date-based portion of any upstream version number
921 should be given in a way that sorts correctly: four-digit year
922 first, followed by a two-digit numeric month, followed by a
923 two-digit numeric date, possibly with punctuation between the
928 Native Debian packages (i.e., packages which have been written
929 especially for Debian) whose version numbers include dates
930 should also follow these rules. If punctuation is desired
931 between the date components, remember that hyphen (<tt>-</tt>)
932 cannot be used in native package versions. Period
933 (<tt>.</tt>) is normally a good choice.
939 <sect id="maintainer">
940 <heading>The maintainer of a package</heading>
943 Every package must have a maintainer, except for orphaned
944 packages as described below. The maintainer may be one person
945 or a group of people reachable from a common email address, such
946 as a mailing list. The maintainer is responsible for
947 maintaining the Debian packaging files, evaluating and
948 responding appropriately to reported bugs, uploading new
949 versions of the package (either directly or through a sponsor),
950 ensuring that the package is placed in the appropriate archive
951 area and included in Debian releases as appropriate for the
952 stability and utility of the package, and requesting removal of
953 the package from the Debian distribution if it is no longer
954 useful or maintainable.
958 The maintainer must be specified in the <tt>Maintainer</tt>
959 control field with their correct name and a working email
960 address. The email address given in the <tt>Maintainer</tt>
961 control field must accept mail from those role accounts in
962 Debian used to send automated mails regarding the package. This
963 includes non-spam mail from the bug-tracking system, all mail
964 from the Debian archive maintenance software, and other role
965 accounts or automated processes that are commonly agreed on by
966 the project.<footnote>
967 A sample implementation of such a whitelist written for the
968 Mailman mailing list management software is used for mailing
969 lists hosted by alioth.debian.org.
971 If one person or team maintains several packages, they should
972 use the same form of their name and email address in
973 the <tt>Maintainer</tt> fields of those packages.
977 The format of the <tt>Maintainer</tt> control field is
978 described in <ref id="f-Maintainer">.
982 If the maintainer of the package is a team of people with a
983 shared email address, the <tt>Uploaders</tt> control field must
984 be present and must contain at least one human with their
985 personal email address. See <ref id="f-Uploaders"> for the
986 syntax of that field.
990 An orphaned package is one with no current maintainer. Orphaned
991 packages should have their <tt>Maintainer</tt> control field set
992 to <tt>Debian QA Group <packages@qa.debian.org></tt>.
993 These packages are considered maintained by the Debian project
994 as a whole until someone else volunteers to take over
995 maintenance.<footnote>
996 The detailed procedure for gracefully orphaning a package can
997 be found in the Debian Developer's Reference
998 (see <ref id="related">).
1003 <sect id="descriptions">
1004 <heading>The description of a package</heading>
1007 Every Debian package must have a <tt>Description</tt> control
1008 field which contains a synopsis and extended description of the
1009 package. Technical information about the format of the
1010 <tt>Description</tt> field is in <ref id="f-Description">.
1014 The description should describe the package (the program) to a
1015 user (system administrator) who has never met it before so that
1016 they have enough information to decide whether they want to
1017 install it. This description should not just be copied verbatim
1018 from the program's documentation.
1022 Put important information first, both in the synopsis and
1023 extended description. Sometimes only the first part of the
1024 synopsis or of the description will be displayed. You can
1025 assume that there will usually be a way to see the whole
1026 extended description.
1030 The description should also give information about the
1031 significant dependencies and conflicts between this package
1032 and others, so that the user knows why these dependencies and
1033 conflicts have been declared.
1037 Instructions for configuring or using the package should
1038 not be included (that is what installation scripts,
1039 manual pages, info files, etc., are for). Copyright
1040 statements and other administrivia should not be included
1041 either (that is what the copyright file is for).
1044 <sect1 id="synopsis"><heading>The single line synopsis</heading>
1047 The single line synopsis should be kept brief - certainly
1048 under 80 characters.
1052 Do not include the package name in the synopsis line. The
1053 display software knows how to display this already, and you
1054 do not need to state it. Remember that in many situations
1055 the user may only see the synopsis line - make it as
1056 informative as you can.
1061 <sect1 id="extendeddesc"><heading>The extended description</heading>
1064 Do not try to continue the single line synopsis into the
1065 extended description. This will not work correctly when
1066 the full description is displayed, and makes no sense
1067 where only the summary (the single line synopsis) is
1072 The extended description should describe what the package
1073 does and how it relates to the rest of the system (in terms
1074 of, for example, which subsystem it is which part of).
1078 The description field needs to make sense to anyone, even
1079 people who have no idea about any of the things the
1080 package deals with.<footnote>
1081 The blurb that comes with a program in its
1082 announcements and/or <prgn>README</prgn> files is
1083 rarely suitable for use in a description. It is
1084 usually aimed at people who are already in the
1085 community where the package is used.
1093 <sect id="dependencies">
1094 <heading>Dependencies</heading>
1097 Every package must specify the dependency information
1098 about other packages that are required for the first to
1103 For example, a dependency entry must be provided for any
1104 shared libraries required by a dynamically-linked executable
1105 binary in a package.
1109 Packages are not required to declare any dependencies they
1110 have on other packages which are marked <tt>Essential</tt>
1111 (see below), and should not do so unless they depend on a
1112 particular version of that package.<footnote>
1114 Essential is needed in part to avoid unresolvable dependency
1115 loops on upgrade. If packages add unnecessary dependencies
1116 on packages in this set, the chances that there
1117 <strong>will</strong> be an unresolvable dependency loop
1118 caused by forcing these Essential packages to be configured
1119 first before they need to be is greatly increased. It also
1120 increases the chances that frontends will be unable to
1121 <strong>calculate</strong> an upgrade path, even if one
1125 Also, functionality is rarely ever removed from the
1126 Essential set, but <em>packages</em> have been removed from
1127 the Essential set when the functionality moved to a
1128 different package. So depending on these packages <em>just
1129 in case</em> they stop being essential does way more harm
1136 Sometimes, unpacking one package requires that another package
1137 be first unpacked <em>and</em> configured. In this case, the
1138 depending package must specify this dependency in
1139 the <tt>Pre-Depends</tt> control field.
1143 You should not specify a <tt>Pre-Depends</tt> entry for a
1144 package before this has been discussed on the
1145 <tt>debian-devel</tt> mailing list and a consensus about
1146 doing that has been reached.
1150 The format of the package interrelationship control fields is
1151 described in <ref id="relationships">.
1155 <sect id="virtual_pkg">
1156 <heading>Virtual packages</heading>
1159 Sometimes, there are several packages which offer
1160 more-or-less the same functionality. In this case, it's
1161 useful to define a <em>virtual package</em> whose name
1162 describes that common functionality. (The virtual
1163 packages only exist logically, not physically; that's why
1164 they are called <em>virtual</em>.) The packages with this
1165 particular function will then <em>provide</em> the virtual
1166 package. Thus, any other package requiring that function
1167 can simply depend on the virtual package without having to
1168 specify all possible packages individually.
1172 All packages should use virtual package names where
1173 appropriate, and arrange to create new ones if necessary.
1174 They should not use virtual package names (except privately,
1175 amongst a cooperating group of packages) unless they have
1176 been agreed upon and appear in the list of virtual package
1177 names. (See also <ref id="virtual">)
1181 The latest version of the authoritative list of virtual
1182 package names can be found in the <tt>debian-policy</tt> package.
1183 It is also available from the Debian web mirrors at
1184 <tt><url name="/doc/packaging-manuals/virtual-package-names-list.txt"
1185 id="http://www.debian.org/doc/packaging-manuals/virtual-package-names-list.txt"></tt>.
1189 The procedure for updating the list is described in the preface
1196 <heading>Base system</heading>
1199 The <tt>base system</tt> is a minimum subset of the Debian
1200 system that is installed before everything else
1201 on a new system. Only very few packages are allowed to form
1202 part of the base system, in order to keep the required disk
1207 The base system consists of all those packages with priority
1208 <tt>required</tt> or <tt>important</tt>. Many of them will
1209 be tagged <tt>essential</tt> (see below).
1214 <heading>Essential packages</heading>
1217 Essential is defined as the minimal set of functionality that
1218 must be available and usable on the system at all times, even
1219 when packages are in an unconfigured (but unpacked) state.
1220 Packages are tagged <tt>essential</tt> for a system using the
1221 <tt>Essential</tt> control field. The format of the
1222 <tt>Essential</tt> control field is described in <ref
1227 Since these packages cannot be easily removed (one has to
1228 specify an extra <em>force option</em> to
1229 <prgn>dpkg</prgn> to do so), this flag must not be used
1230 unless absolutely necessary. A shared library package
1231 must not be tagged <tt>essential</tt>; dependencies will
1232 prevent its premature removal, and we need to be able to
1233 remove it when it has been superseded.
1237 Since dpkg will not prevent upgrading of other packages
1238 while an <tt>essential</tt> package is in an unconfigured
1239 state, all <tt>essential</tt> packages must supply all of
1240 their core functionality even when unconfigured. If the
1241 package cannot satisfy this requirement it must not be
1242 tagged as essential, and any packages depending on this
1243 package must instead have explicit dependency fields as
1248 Maintainers should take great care in adding any programs,
1249 interfaces, or functionality to <tt>essential</tt> packages.
1250 Packages may assume that functionality provided by
1251 <tt>essential</tt> packages is always available without
1252 declaring explicit dependencies, which means that removing
1253 functionality from the Essential set is very difficult and is
1254 almost never done. Any capability added to an
1255 <tt>essential</tt> package therefore creates an obligation to
1256 support that capability as part of the Essential set in
1261 You must not tag any packages <tt>essential</tt> before
1262 this has been discussed on the <tt>debian-devel</tt>
1263 mailing list and a consensus about doing that has been
1268 <sect id="maintscripts">
1269 <heading>Maintainer Scripts</heading>
1272 The package installation scripts should avoid producing
1273 output which is unnecessary for the user to see and
1274 should rely on <prgn>dpkg</prgn> to stave off boredom on
1275 the part of a user installing many packages. This means,
1276 amongst other things, using the <tt>--quiet</tt> option on
1277 <prgn>install-info</prgn>.
1281 Errors which occur during the execution of an installation
1282 script must be checked and the installation must not
1283 continue after an error.
1287 Note that in general <ref id="scripts"> applies to package
1288 maintainer scripts, too.
1292 You should not use <prgn>dpkg-divert</prgn> on a file belonging
1293 to another package without consulting the maintainer of that
1294 package first. When adding or removing diversions, package
1295 maintainer scripts must provide the <tt>--package</tt> flag
1296 to <prgn>dpkg-divert</prgn> and must not use <tt>--local</tt>.
1300 All packages which supply an instance of a common command
1301 name (or, in general, filename) should generally use
1302 <prgn>update-alternatives</prgn>, so that they may be
1303 installed together. If <prgn>update-alternatives</prgn>
1304 is not used, then each package must use
1305 <tt>Conflicts</tt> to ensure that other packages are
1306 de-installed. (In this case, it may be appropriate to
1307 specify a conflict against earlier versions of something
1308 that previously did not use
1309 <prgn>update-alternatives</prgn>; this is an exception to
1310 the usual rule that versioned conflicts should be
1314 <sect1 id="maintscriptprompt">
1315 <heading>Prompting in maintainer scripts</heading>
1317 Package maintainer scripts may prompt the user if
1318 necessary. Prompting must be done by communicating
1319 through a program, such as <prgn>debconf</prgn>, which
1320 conforms to the Debian Configuration Management
1321 Specification, version 2 or higher.
1325 Packages which are essential, or which are dependencies of
1326 essential packages, may fall back on another prompting method
1327 if no such interface is available when they are executed.
1331 The Debian Configuration Management Specification is included
1332 in the <file>debconf_specification</file> files in the
1333 <package>debian-policy</package> package.
1334 It is also available from the Debian web mirrors at
1335 <tt><url name="/doc/packaging-manuals/debconf_specification.html"
1336 id="http://www.debian.org/doc/packaging-manuals/debconf_specification.html"></tt>.
1340 Packages which use the Debian Configuration Management
1341 Specification may contain the additional control information
1342 files <file>config</file>
1343 and <file>templates</file>. <file>config</file> is an
1344 additional maintainer script used for package configuration,
1345 and <file>templates</file> contains templates used for user
1346 prompting. The <prgn>config</prgn> script might be run before
1347 the <prgn>preinst</prgn> script and before the package is
1348 unpacked or any of its dependencies or pre-dependencies are
1349 satisfied. Therefore it must work using only the tools
1350 present in <em>essential</em> packages.<footnote>
1351 <package>Debconf</package> or another tool that
1352 implements the Debian Configuration Management
1353 Specification will also be installed, and any
1354 versioned dependencies on it will be satisfied
1355 before preconfiguration begins.
1360 Packages which use the Debian Configuration Management
1361 Specification must allow for translation of their user-visible
1362 messages by using a gettext-based system such as the one
1363 provided by the <package>po-debconf</package> package.
1367 Packages should try to minimize the amount of prompting
1368 they need to do, and they should ensure that the user
1369 will only ever be asked each question once. This means
1370 that packages should try to use appropriate shared
1371 configuration files (such as <file>/etc/papersize</file> and
1372 <file>/etc/news/server</file>), and shared
1373 <package>debconf</package> variables rather than each
1374 prompting for their own list of required pieces of
1379 It also means that an upgrade should not ask the same
1380 questions again, unless the user has used
1381 <tt>dpkg --purge</tt> to remove the package's configuration.
1382 The answers to configuration questions should be stored in an
1383 appropriate place in <file>/etc</file> so that the user can
1384 modify them, and how this has been done should be
1389 If a package has a vitally important piece of
1390 information to pass to the user (such as "don't run me
1391 as I am, you must edit the following configuration files
1392 first or you risk your system emitting badly-formatted
1393 messages"), it should display this in the
1394 <prgn>config</prgn> or <prgn>postinst</prgn> script and
1395 prompt the user to hit return to acknowledge the
1396 message. Copyright messages do not count as vitally
1397 important (they belong in
1398 <file>/usr/share/doc/<var>package</var>/copyright</file>);
1399 neither do instructions on how to use a program (these
1400 should be in on-line documentation, where all the users
1405 Any necessary prompting should almost always be confined
1406 to the <prgn>config</prgn> or <prgn>postinst</prgn>
1407 script. If it is done in the <prgn>postinst</prgn>, it
1408 should be protected with a conditional so that
1409 unnecessary prompting doesn't happen if a package's
1410 installation fails and the <prgn>postinst</prgn> is
1411 called with <tt>abort-upgrade</tt>,
1412 <tt>abort-remove</tt> or <tt>abort-deconfigure</tt>.
1422 <heading>Source packages</heading>
1424 <sect id="standardsversion">
1425 <heading>Standards conformance</heading>
1428 Source packages should specify the most recent version number
1429 of this policy document with which your package complied
1430 when it was last updated.
1434 This information may be used to file bug reports
1435 automatically if your package becomes too much out of date.
1439 The version is specified in the <tt>Standards-Version</tt>
1441 The format of the <tt>Standards-Version</tt> field is
1442 described in <ref id="f-Standards-Version">.
1446 You should regularly, and especially if your package has
1447 become out of date, check for the newest Policy Manual
1448 available and update your package, if necessary. When your
1449 package complies with the new standards you should update the
1450 <tt>Standards-Version</tt> source package field and
1451 release it.<footnote>
1452 See the file <file>upgrading-checklist</file> for
1453 information about policy which has changed between
1454 different versions of this document.
1460 <sect id="pkg-relations">
1461 <heading>Package relationships</heading>
1464 Source packages should specify which binary packages they
1465 require to be installed or not to be installed in order to
1466 build correctly. For example, if building a package
1467 requires a certain compiler, then the compiler should be
1468 specified as a build-time dependency.
1472 It is not necessary to explicitly specify build-time
1473 relationships on a minimal set of packages that are always
1474 needed to compile, link and put in a Debian package a
1475 standard "Hello World!" program written in C or C++. The
1476 required packages are called <em>build-essential</em>, and
1477 an informational list can be found in
1478 <file>/usr/share/doc/build-essential/list</file> (which is
1479 contained in the <tt>build-essential</tt>
1482 <list compact="compact">
1484 This allows maintaining the list separately
1485 from the policy documents (the list does not
1486 need the kind of control that the policy
1490 Having a separate package allows one to install
1491 the build-essential packages on a machine, as
1492 well as allowing other packages such as tasks to
1493 require installation of the build-essential
1494 packages using the depends relation.
1497 The separate package allows bug reports against
1498 the list to be categorized separately from
1499 the policy management process in the BTS.
1506 When specifying the set of build-time dependencies, one
1507 should list only those packages explicitly required by the
1508 build. It is not necessary to list packages which are
1509 required merely because some other package in the list of
1510 build-time dependencies depends on them.<footnote>
1511 The reason for this is that dependencies change, and
1512 you should list all those packages, and <em>only</em>
1513 those packages that <em>you</em> need directly. What
1514 others need is their business. For example, if you
1515 only link against <file>libimlib</file>, you will need to
1516 build-depend on <package>libimlib2-dev</package> but
1517 not against any <tt>libjpeg*</tt> packages, even
1518 though <tt>libimlib2-dev</tt> currently depends on
1519 them: installation of <package>libimlib2-dev</package>
1520 will automatically ensure that all of its run-time
1521 dependencies are satisfied.
1526 If build-time dependencies are specified, it must be
1527 possible to build the package and produce working binaries
1528 on a system with only essential and build-essential
1529 packages installed and also those required to satisfy the
1530 build-time relationships (including any implied
1531 relationships). In particular, this means that version
1532 clauses should be used rigorously in build-time
1533 relationships so that one cannot produce bad or
1534 inconsistently configured packages when the relationships
1535 are properly satisfied.
1539 <ref id="relationships"> explains the technical details.
1544 <heading>Changes to the upstream sources</heading>
1547 If changes to the source code are made that are not
1548 specific to the needs of the Debian system, they should be
1549 sent to the upstream authors in whatever form they prefer
1550 so as to be included in the upstream version of the
1555 If you need to configure the package differently for
1556 Debian or for Linux, and the upstream source doesn't
1557 provide a way to do so, you should add such configuration
1558 facilities (for example, a new <prgn>autoconf</prgn> test
1559 or <tt>#define</tt>) and send the patch to the upstream
1560 authors, with the default set to the way they originally
1561 had it. You can then easily override the default in your
1562 <file>debian/rules</file> or wherever is appropriate.
1566 You should make sure that the <prgn>configure</prgn> utility
1567 detects the correct architecture specification string
1568 (refer to <ref id="arch-spec"> for details).
1572 If you need to edit a <prgn>Makefile</prgn> where GNU-style
1573 <prgn>configure</prgn> scripts are used, you should edit the
1574 <file>.in</file> files rather than editing the
1575 <prgn>Makefile</prgn> directly. This allows the user to
1576 reconfigure the package if necessary. You should
1577 <em>not</em> configure the package and edit the generated
1578 <prgn>Makefile</prgn>! This makes it impossible for someone
1579 else to later reconfigure the package without losing the
1585 <sect id="dpkgchangelog">
1586 <heading>Debian changelog: <file>debian/changelog</file></heading>
1589 Changes in the Debian version of the package should be
1590 briefly explained in the Debian changelog file
1591 <file>debian/changelog</file>.<footnote>
1593 Mistakes in changelogs are usually best rectified by
1594 making a new changelog entry rather than "rewriting
1595 history" by editing old changelog entries.
1598 This includes modifications
1599 made in the Debian package compared to the upstream one
1600 as well as other changes and updates to the package.
1602 Although there is nothing stopping an author who is also
1603 the Debian maintainer from using this changelog for all
1604 their changes, it will have to be renamed if the Debian
1605 and upstream maintainers become different people. In such
1606 a case, however, it might be better to maintain the package
1607 as a non-native package.
1612 The format of the <file>debian/changelog</file> allows the
1613 package building tools to discover which version of the package
1614 is being built and find out other release-specific information.
1618 That format is a series of entries like this:
1620 <example compact="compact">
1621 <var>package</var> (<var>version</var>) <var>distribution(s)</var>; urgency=<var>urgency</var>
1623 [optional blank line(s), stripped]
1625 * <var>change details</var>
1626 <var>more change details</var>
1628 [blank line(s), included in output of dpkg-parsechangelog]
1630 * <var>even more change details</var>
1632 [optional blank line(s), stripped]
1634 -- <var>maintainer name</var> <<var>email address</var>><var>[two spaces]</var> <var>date</var>
1639 <var>package</var> and <var>version</var> are the source
1640 package name and version number.
1644 <var>distribution(s)</var> lists the distributions where
1645 this version should be installed when it is uploaded - it
1646 is copied to the <tt>Distribution</tt> field in the
1647 <file>.changes</file> file. See <ref id="f-Distribution">.
1651 <var>urgency</var> is the value for the <tt>Urgency</tt>
1652 field in the <file>.changes</file> file for the upload
1653 (see <ref id="f-Urgency">). It is not possible to specify
1654 an urgency containing commas; commas are used to separate
1655 <tt><var>keyword</var>=<var>value</var></tt> settings in the
1656 <prgn>dpkg</prgn> changelog format (though there is
1657 currently only one useful <var>keyword</var>,
1662 The change details may in fact be any series of lines
1663 starting with at least two spaces, but conventionally each
1664 change starts with an asterisk and a separating space and
1665 continuation lines are indented so as to bring them in
1666 line with the start of the text above. Blank lines may be
1667 used here to separate groups of changes, if desired.
1671 If this upload resolves bugs recorded in the Bug Tracking
1672 System (BTS), they may be automatically closed on the
1673 inclusion of this package into the Debian archive by
1674 including the string: <tt>closes: Bug#<var>nnnnn</var></tt>
1675 in the change details.<footnote>
1676 To be precise, the string should match the following
1677 Perl regular expression:
1679 /closes:\s*(?:bug)?\#?\s?\d+(?:,\s*(?:bug)?\#?\s?\d+)*/i
1681 Then all of the bug numbers listed will be closed by the
1682 archive maintenance script (<prgn>katie</prgn>) using the
1683 <var>version</var> of the changelog entry.
1685 This information is conveyed via the <tt>Closes</tt> field
1686 in the <tt>.changes</tt> file (see <ref id="f-Closes">).
1690 The maintainer name and email address used in the changelog
1691 should be the details of the person uploading <em>this</em>
1692 version. They are <em>not</em> necessarily those of the
1693 usual package maintainer.<footnote>
1694 If the developer uploading the package is not one of the usual
1695 maintainers of the package (as listed in
1696 the <qref id="f-Maintainer"><tt>Maintainer</tt></qref>
1697 or <qref id="f-Uploaders"><tt>Uploaders</tt></qref> control
1698 fields of the package), the first line of the changelog is
1699 conventionally used to explain why a non-maintainer is
1700 uploading the package. The Debian Developer's Reference
1701 (see <ref id="related">) documents the conventions
1703 The information here will be copied to the <tt>Changed-By</tt>
1704 field in the <tt>.changes</tt> file
1705 (see <ref id="f-Changed-By">), and then later used to send an
1706 acknowledgement when the upload has been installed.
1710 The <var>date</var> has the following format<footnote>
1711 This is the same as the format generated by <tt>date
1713 </footnote> (compatible and with the same semantics of
1714 RFC 2822 and RFC 5322):
1715 <example>day-of-week, dd month yyyy hh:mm:ss +zzzz</example>
1717 <list compact="compact">
1719 day-of week is one of: Mon, Tue, Wed, Thu, Fri, Sat, Sun
1722 dd is a one- or two-digit day of the month (01-31)
1725 month is one of: Jan, Feb, Mar, Apr, May, Jun, Jul, Aug,
1728 <item>yyyy is the four-digit year (e.g. 2010)</item>
1729 <item>hh is the two-digit hour (00-23)</item>
1730 <item>mm is the two-digit minutes (00-59)</item>
1731 <item>ss is the two-digit seconds (00-60)</item>
1733 +zzzz or -zzzz is the the time zone offset from Coordinated
1734 Universal Time (UTC). "+" indicates that the time is ahead
1735 of (i.e., east of) UTC and "-" indicates that the time is
1736 behind (i.e., west of) UTC. The first two digits indicate
1737 the hour difference from UTC and the last two digits
1738 indicate the number of additional minutes difference from
1739 UTC. The last two digits must be in the range 00-59.
1745 The first "title" line with the package name must start
1746 at the left hand margin. The "trailer" line with the
1747 maintainer and date details must be preceded by exactly
1748 one space. The maintainer details and the date must be
1749 separated by exactly two spaces.
1753 The entire changelog must be encoded in UTF-8.
1757 For more information on placement of the changelog files
1758 within binary packages, please see <ref id="changelogs">.
1762 <sect id="dpkgcopyright">
1763 <heading>Copyright: <file>debian/copyright</file></heading>
1765 Every package must be accompanied by a verbatim copy of its
1766 copyright information and distribution license in the file
1767 <file>/usr/share/doc/<var>package</var>/copyright</file>
1768 (see <ref id="copyrightfile"> for further details). Also see
1769 <ref id="pkgcopyright"> for further considerations related
1770 to copyrights for packages.
1774 <heading>Error trapping in makefiles</heading>
1777 When <prgn>make</prgn> invokes a command in a makefile
1778 (including your package's upstream makefiles and
1779 <file>debian/rules</file>), it does so using <prgn>sh</prgn>. This
1780 means that <prgn>sh</prgn>'s usual bad error handling
1781 properties apply: if you include a miniature script as one
1782 of the commands in your makefile you'll find that if you
1783 don't do anything about it then errors are not detected
1784 and <prgn>make</prgn> will blithely continue after
1789 Every time you put more than one shell command (this
1790 includes using a loop) in a makefile command you
1791 must make sure that errors are trapped. For
1792 simple compound commands, such as changing directory and
1793 then running a program, using <tt>&&</tt> rather
1794 than semicolon as a command separator is sufficient. For
1795 more complex commands including most loops and
1796 conditionals you should include a separate <tt>set -e</tt>
1797 command at the start of every makefile command that's
1798 actually one of these miniature shell scripts.
1802 <sect id="timestamps">
1803 <heading>Time Stamps</heading>
1805 Maintainers should preserve the modification times of the
1806 upstream source files in a package, as far as is reasonably
1808 The rationale is that there is some information conveyed
1809 by knowing the age of the file, for example, you could
1810 recognize that some documentation is very old by looking
1811 at the modification time, so it would be nice if the
1812 modification time of the upstream source would be
1818 <sect id="restrictions">
1819 <heading>Restrictions on objects in source packages</heading>
1822 The source package may not contain any hard links<footnote>
1824 This is not currently detected when building source
1825 packages, but only when extracting
1829 Hard links may be permitted at some point in the
1830 future, but would require a fair amount of
1833 </footnote>, device special files, sockets or setuid or
1834 setgid files.<footnote>
1835 Setgid directories are allowed.
1840 <sect id="debianrules">
1841 <heading>Main building script: <file>debian/rules</file></heading>
1844 This file must be an executable makefile, and contains the
1845 package-specific recipes for compiling the package and
1846 building binary package(s) from the source.
1850 It must start with the line <tt>#!/usr/bin/make -f</tt>,
1851 so that it can be invoked by saying its name rather than
1852 invoking <prgn>make</prgn> explicitly. That is, invoking
1853 either of <tt>make -f debian/rules <em>args...</em></tt>
1854 or <tt>./debian/rules <em>args...</em></tt> must result in
1859 The following targets are required and must be implemented
1860 by <file>debian/rules</file>: <tt>clean</tt>, <tt>binary</tt>,
1861 <tt>binary-arch</tt>, <tt>binary-indep</tt>, and <tt>build</tt>.
1862 These are the targets called by <prgn>dpkg-buildpackage</prgn>.
1866 Since an interactive <file>debian/rules</file> script makes it
1867 impossible to auto-compile that package and also makes it hard
1868 for other people to reproduce the same binary package, all
1869 required targets must be non-interactive. It also follows that
1870 any target that these targets depend on must also be
1875 The targets are as follows:
1877 <tag><tt>build</tt> (required)</tag>
1880 The <tt>build</tt> target should perform all the
1881 configuration and compilation of the package.
1882 If a package has an interactive pre-build
1883 configuration routine, the Debian source package
1884 must either be built after this has taken place (so
1885 that the binary package can be built without rerunning
1886 the configuration) or the configuration routine
1887 modified to become non-interactive. (The latter is
1888 preferable if there are architecture-specific features
1889 detected by the configuration routine.)
1893 For some packages, notably ones where the same
1894 source tree is compiled in different ways to produce
1895 two binary packages, the <tt>build</tt> target
1896 does not make much sense. For these packages it is
1897 good enough to provide two (or more) targets
1898 (<tt>build-a</tt> and <tt>build-b</tt> or whatever)
1899 for each of the ways of building the package, and a
1900 <tt>build</tt> target that does nothing. The
1901 <tt>binary</tt> target will have to build the
1902 package in each of the possible ways and make the
1903 binary package out of each.
1907 The <tt>build</tt> target must not do anything
1908 that might require root privilege.
1912 The <tt>build</tt> target may need to run the
1913 <tt>clean</tt> target first - see below.
1917 When a package has a configuration and build routine
1918 which takes a long time, or when the makefiles are
1919 poorly designed, or when <tt>build</tt> needs to
1920 run <tt>clean</tt> first, it is a good idea to
1921 <tt>touch build</tt> when the build process is
1922 complete. This will ensure that if <tt>debian/rules
1923 build</tt> is run again it will not rebuild the whole
1925 Another common way to do this is for <tt>build</tt>
1926 to depend on <prgn>build-stamp</prgn> and to do
1927 nothing else, and for the <prgn>build-stamp</prgn>
1928 target to do the building and to <tt>touch
1929 build-stamp</tt> on completion. This is
1930 especially useful if the build routine creates a
1931 file or directory called <tt>build</tt>; in such a
1932 case, <tt>build</tt> will need to be listed as
1933 a phony target (i.e., as a dependency of the
1934 <tt>.PHONY</tt> target). See the documentation of
1935 <prgn>make</prgn> for more information on phony
1941 <tag><tt>build-arch</tt> (optional),
1942 <tt>build-indep</tt> (optional)
1946 A package may also provide both of the targets
1947 <tt>build-arch</tt> and <tt>build-indep</tt>.
1948 The <tt>build-arch</tt> target, if provided, should
1949 perform all the configuration and compilation required for
1950 producing all architecture-dependant binary packages
1951 (those packages for which the body of the
1952 <tt>Architecture</tt> field in <tt>debian/control</tt> is
1953 not <tt>all</tt>). Similarly, the <tt>build-indep</tt>
1954 target, if provided, should perform all the configuration
1955 and compilation required for producing all
1956 architecture-independent binary packages (those packages
1957 for which the body of the <tt>Architecture</tt> field
1958 in <tt>debian/control</tt> is <tt>all</tt>).
1959 The <tt>build</tt> target should depend on those of the
1960 targets <tt>build-arch</tt> and <tt>build-indep</tt> that
1961 are provided in the rules file.<footnote>
1962 The intent of this split is so that binary-only builds
1963 need not install the dependencies required for
1964 the <tt>build-indep</tt> target. However, this is not
1965 yet used in practice since <tt>dpkg-buildpackage
1966 -B</tt>, and therefore the autobuilders,
1967 invoke <tt>build</tt> rather than <tt>build-arch</tt>
1968 due to the difficulties in determining whether the
1969 optional <tt>build-arch</tt> target exists.
1974 If one or both of the targets <tt>build-arch</tt> and
1975 <tt>build-indep</tt> are not provided, then invoking
1976 <file>debian/rules</file> with one of the not-provided
1977 targets as arguments should produce a exit status code
1978 of 2. Usually this is provided automatically by make
1979 if the target is missing.
1983 The <tt>build-arch</tt> and <tt>build-indep</tt> targets
1984 must not do anything that might require root privilege.
1988 <tag><tt>binary</tt> (required), <tt>binary-arch</tt>
1989 (required), <tt>binary-indep</tt> (required)
1993 The <tt>binary</tt> target must be all that is
1994 necessary for the user to build the binary package(s)
1995 produced from this source package. It is
1996 split into two parts: <prgn>binary-arch</prgn> builds
1997 the binary packages which are specific to a particular
1998 architecture, and <tt>binary-indep</tt> builds
1999 those which are not.
2002 <tt>binary</tt> may be (and commonly is) a target with
2003 no commands which simply depends on
2004 <tt>binary-arch</tt> and <tt>binary-indep</tt>.
2007 Both <tt>binary-*</tt> targets should depend on the
2008 <tt>build</tt> target, or on the appropriate
2009 <tt>build-arch</tt> or <tt>build-indep</tt> target, if
2010 provided, so that the package is built if it has not
2011 been already. It should then create the relevant
2012 binary package(s), using <prgn>dpkg-gencontrol</prgn> to
2013 make their control files and <prgn>dpkg-deb</prgn> to
2014 build them and place them in the parent of the top
2019 Both the <tt>binary-arch</tt> and
2020 <tt>binary-indep</tt> targets <em>must</em> exist.
2021 If one of them has nothing to do (which will always be
2022 the case if the source generates only a single binary
2023 package, whether architecture-dependent or not), it
2024 must still exist and must always succeed.
2028 The <tt>binary</tt> targets must be invoked as
2030 The <prgn>fakeroot</prgn> package often allows one
2031 to build a package correctly even without being
2037 <tag><tt>clean</tt> (required)</tag>
2040 This must undo any effects that the <tt>build</tt>
2041 and <tt>binary</tt> targets may have had, except
2042 that it should leave alone any output files created in
2043 the parent directory by a run of a <tt>binary</tt>
2048 If a <tt>build</tt> file is touched at the end of
2049 the <tt>build</tt> target, as suggested above, it
2050 should be removed as the first action that
2051 <tt>clean</tt> performs, so that running
2052 <tt>build</tt> again after an interrupted
2053 <tt>clean</tt> doesn't think that everything is
2058 The <tt>clean</tt> target may need to be
2059 invoked as root if <tt>binary</tt> has been
2060 invoked since the last <tt>clean</tt>, or if
2061 <tt>build</tt> has been invoked as root (since
2062 <tt>build</tt> may create directories, for
2067 <tag><tt>get-orig-source</tt> (optional)</tag>
2070 This target fetches the most recent version of the
2071 original source package from a canonical archive site
2072 (via FTP or WWW, for example), does any necessary
2073 rearrangement to turn it into the original source
2074 tar file format described below, and leaves it in the
2079 This target may be invoked in any directory, and
2080 should take care to clean up any temporary files it
2085 This target is optional, but providing it if
2086 possible is a good idea.
2090 <tag><tt>patch</tt> (optional)</tag>
2093 This target performs whatever additional actions are
2094 required to make the source ready for editing (unpacking
2095 additional upstream archives, applying patches, etc.).
2096 It is recommended to be implemented for any package where
2097 <tt>dpkg-source -x</tt> does not result in source ready
2098 for additional modification. See
2099 <ref id="readmesource">.
2105 The <tt>build</tt>, <tt>binary</tt> and
2106 <tt>clean</tt> targets must be invoked with the current
2107 directory being the package's top-level directory.
2112 Additional targets may exist in <file>debian/rules</file>,
2113 either as published or undocumented interfaces or for the
2114 package's internal use.
2118 The architectures we build on and build for are determined
2119 by <prgn>make</prgn> variables using the
2120 utility <qref id="pkg-dpkg-architecture"><prgn>dpkg-architecture</prgn></qref>.
2121 You can determine the Debian architecture and the GNU style
2122 architecture specification string for the build architecture as
2123 well as for the host architecture. The build architecture is
2124 the architecture on which <file>debian/rules</file> is run and
2125 the package build is performed. The host architecture is the
2126 architecture on which the resulting package will be installed
2127 and run. These are normally the same, but may be different in
2128 the case of cross-compilation (building packages for one
2129 architecture on machines of a different architecture).
2133 Here is a list of supported <prgn>make</prgn> variables:
2134 <list compact="compact">
2136 <tt>DEB_*_ARCH</tt> (the Debian architecture)
2139 <tt>DEB_*_ARCH_CPU</tt> (the Debian CPU name)
2142 <tt>DEB_*_ARCH_OS</tt> (the Debian System name)
2145 <tt>DEB_*_GNU_TYPE</tt> (the GNU style architecture
2146 specification string)
2149 <tt>DEB_*_GNU_CPU</tt> (the CPU part of
2150 <tt>DEB_*_GNU_TYPE</tt>)
2153 <tt>DEB_*_GNU_SYSTEM</tt> (the System part of
2154 <tt>DEB_*_GNU_TYPE</tt>)
2156 where <tt>*</tt> is either <tt>BUILD</tt> for specification of
2157 the build architecture or <tt>HOST</tt> for specification of the
2162 Backward compatibility can be provided in the rules file
2163 by setting the needed variables to suitable default
2164 values; please refer to the documentation of
2165 <prgn>dpkg-architecture</prgn> for details.
2169 It is important to understand that the <tt>DEB_*_ARCH</tt>
2170 string only determines which Debian architecture we are
2171 building on or for. It should not be used to get the CPU
2172 or system information; the <tt>DEB_*_ARCH_CPU</tt> and
2173 <tt>DEB_*_ARCH_OS</tt> variables should be used for that.
2174 GNU style variables should generally only be used with upstream
2178 <sect1 id="debianrules-options">
2179 <heading><file>debian/rules</file> and
2180 <tt>DEB_BUILD_OPTIONS</tt></heading>
2183 Supporting the standardized environment variable
2184 <tt>DEB_BUILD_OPTIONS</tt> is recommended. This variable can
2185 contain several flags to change how a package is compiled and
2186 built. Each flag must be in the form <var>flag</var> or
2187 <var>flag</var>=<var>options</var>. If multiple flags are
2188 given, they must be separated by whitespace.<footnote>
2189 Some packages support any delimiter, but whitespace is the
2190 easiest to parse inside a makefile and avoids ambiguity with
2191 flag values that contain commas.
2193 <var>flag</var> must start with a lowercase letter
2194 (<tt>a-z</tt>) and consist only of lowercase letters,
2195 numbers (<tt>0-9</tt>), and the characters
2196 <tt>-</tt> and <tt>_</tt> (hyphen and underscore).
2197 <var>options</var> must not contain whitespace. The same
2198 tag should not be given multiple times with conflicting
2199 values. Package maintainers may assume that
2200 <tt>DEB_BUILD_OPTIONS</tt> will not contain conflicting tags.
2204 The meaning of the following tags has been standardized:
2208 This tag says to not run any build-time test suite
2209 provided by the package.
2213 The presence of this tag means that the package should
2214 be compiled with a minimum of optimization. For C
2215 programs, it is best to add <tt>-O0</tt> to
2216 <tt>CFLAGS</tt> (although this is usually the default).
2217 Some programs might fail to build or run at this level
2218 of optimization; it may be necessary to use
2219 <tt>-O1</tt>, for example.
2223 This tag means that the debugging symbols should not be
2224 stripped from the binary during installation, so that
2225 debugging information may be included in the package.
2227 <tag>parallel=n</tag>
2229 This tag means that the package should be built using up
2230 to <tt>n</tt> parallel processes if the package build
2231 system supports this.<footnote>
2232 Packages built with <tt>make</tt> can often implement
2233 this by passing the <tt>-j</tt><var>n</var> option to
2236 If the package build system does not support parallel
2237 builds, this string must be ignored. If the package
2238 build system only supports a lower level of concurrency
2239 than <var>n</var>, the package should be built using as
2240 many parallel processes as the package build system
2241 supports. It is up to the package maintainer to decide
2242 whether the package build times are long enough and the
2243 package build system is robust enough to make supporting
2244 parallel builds worthwhile.
2250 Unknown flags must be ignored by <file>debian/rules</file>.
2254 The following makefile snippet is an example of how one may
2255 implement the build options; you will probably have to
2256 massage this example in order to make it work for your
2258 <example compact="compact">
2261 INSTALL_FILE = $(INSTALL) -p -o root -g root -m 644
2262 INSTALL_PROGRAM = $(INSTALL) -p -o root -g root -m 755
2263 INSTALL_SCRIPT = $(INSTALL) -p -o root -g root -m 755
2264 INSTALL_DIR = $(INSTALL) -p -d -o root -g root -m 755
2266 ifneq (,$(filter noopt,$(DEB_BUILD_OPTIONS)))
2271 ifeq (,$(filter nostrip,$(DEB_BUILD_OPTIONS)))
2272 INSTALL_PROGRAM += -s
2274 ifneq (,$(filter parallel=%,$(DEB_BUILD_OPTIONS)))
2275 NUMJOBS = $(patsubst parallel=%,%,$(filter parallel=%,$(DEB_BUILD_OPTIONS)))
2276 MAKEFLAGS += -j$(NUMJOBS)
2281 ifeq (,$(filter nocheck,$(DEB_BUILD_OPTIONS)))
2282 # Code to run the package test suite.
2289 <!-- FIXME: section pkg-srcsubstvars is the same as substvars -->
2290 <sect id="substvars">
2291 <heading>Variable substitutions: <file>debian/substvars</file></heading>
2294 When <prgn>dpkg-gencontrol</prgn>
2295 generates <qref id="binarycontrolfiles">binary package control
2296 files</qref> (<file>DEBIAN/control</file>), it performs variable
2297 substitutions on its output just before writing it. Variable
2298 substitutions have the form <tt>${<var>variable</var>}</tt>.
2299 The optional file <file>debian/substvars</file> contains
2300 variable substitutions to be used; variables can also be set
2301 directly from <file>debian/rules</file> using the <tt>-V</tt>
2302 option to the source packaging commands, and certain predefined
2303 variables are also available.
2307 The <file>debian/substvars</file> file is usually generated and
2308 modified dynamically by <file>debian/rules</file> targets, in
2309 which case it must be removed by the <tt>clean</tt> target.
2313 See <manref name="deb-substvars" section="5"> for full
2314 details about source variable substitutions, including the
2315 format of <file>debian/substvars</file>.</p>
2318 <sect id="debianwatch">
2319 <heading>Optional upstream source location: <file>debian/watch</file></heading>
2322 This is an optional, recommended configuration file for the
2323 <tt>uscan</tt> utility which defines how to automatically scan
2324 ftp or http sites for newly available updates of the
2325 package. This is used
2326 by <url id="http://dehs.alioth.debian.org/"> and other Debian QA
2327 tools to help with quality control and maintenance of the
2328 distribution as a whole.
2333 <sect id="debianfiles">
2334 <heading>Generated files list: <file>debian/files</file></heading>
2337 This file is not a permanent part of the source tree; it
2338 is used while building packages to record which files are
2339 being generated. <prgn>dpkg-genchanges</prgn> uses it
2340 when it generates a <file>.changes</file> file.
2344 It should not exist in a shipped source package, and so it
2345 (and any backup files or temporary files such as
2346 <file>files.new</file><footnote>
2347 <file>files.new</file> is used as a temporary file by
2348 <prgn>dpkg-gencontrol</prgn> and
2349 <prgn>dpkg-distaddfile</prgn> - they write a new
2350 version of <tt>files</tt> here before renaming it,
2351 to avoid leaving a corrupted copy if an error
2353 </footnote>) should be removed by the
2354 <tt>clean</tt> target. It may also be wise to
2355 ensure a fresh start by emptying or removing it at the
2356 start of the <tt>binary</tt> target.
2360 When <prgn>dpkg-gencontrol</prgn> is run for a binary
2361 package, it adds an entry to <file>debian/files</file> for the
2362 <file>.deb</file> file that will be created when <tt>dpkg-deb
2363 --build</tt> is run for that binary package. So for most
2364 packages all that needs to be done with this file is to
2365 delete it in the <tt>clean</tt> target.
2369 If a package upload includes files besides the source
2370 package and any binary packages whose control files were
2371 made with <prgn>dpkg-gencontrol</prgn> then they should be
2372 placed in the parent of the package's top-level directory
2373 and <prgn>dpkg-distaddfile</prgn> should be called to add
2374 the file to the list in <file>debian/files</file>.</p>
2377 <sect id="embeddedfiles">
2378 <heading>Convenience copies of code</heading>
2381 Some software packages include in their distribution convenience
2382 copies of code from other software packages, generally so that
2383 users compiling from source don't have to download multiple
2384 packages. Debian packages should not make use of these
2385 convenience copies unless the included package is explicitly
2386 intended to be used in this way.<footnote>
2387 For example, parts of the GNU build system work like this.
2389 If the included code is already in the Debian archive in the
2390 form of a library, the Debian packaging should ensure that
2391 binary packages reference the libraries already in Debian and
2392 the convenience copy is not used. If the included code is not
2393 already in Debian, it should be packaged separately as a
2394 prerequisite if possible.
2396 Having multiple copies of the same code in Debian is
2397 inefficient, often creates either static linking or shared
2398 library conflicts, and, most importantly, increases the
2399 difficulty of handling security vulnerabilities in the
2405 <sect id="readmesource">
2406 <heading>Source package handling:
2407 <file>debian/README.source</file></heading>
2410 If running <prgn>dpkg-source -x</prgn> on a source package
2411 doesn't produce the source of the package, ready for editing,
2412 and allow one to make changes and run
2413 <prgn>dpkg-buildpackage</prgn> to produce a modified package
2414 without taking any additional steps, creating a
2415 <file>debian/README.source</file> documentation file is
2416 recommended. This file should explain how to do all of the
2419 <item>Generate the fully patched source, in a form ready for
2420 editing, that would be built to create Debian
2421 packages. Doing this with a <tt>patch</tt> target in
2422 <file>debian/rules</file> is recommended; see
2423 <ref id="debianrules">.</item>
2424 <item>Modify the source and save those modifications so that
2425 they will be applied when building the package.</item>
2426 <item>Remove source modifications that are currently being
2427 applied when building the package.</item>
2428 <item>Optionally, document what steps are necessary to
2429 upgrade the Debian source package to a new upstream version,
2430 if applicable.</item>
2432 This explanation should include specific commands and mention
2433 any additional required Debian packages. It should not assume
2434 familiarity with any specific Debian packaging system or patch
2439 This explanation may refer to a documentation file installed by
2440 one of the package's build dependencies provided that the
2441 referenced documentation clearly explains these tasks and is not
2442 a general reference manual.
2446 <file>debian/README.source</file> may also include any other
2447 information that would be helpful to someone modifying the
2448 source package. Even if the package doesn't fit the above
2449 description, maintainers are encouraged to document in a
2450 <file>debian/README.source</file> file any source package with a
2451 particularly complex or unintuitive source layout or build
2452 system (for example, a package that builds the same source
2453 multiple times to generate different binary packages).
2459 <chapt id="controlfields">
2460 <heading>Control files and their fields</heading>
2463 The package management system manipulates data represented in
2464 a common format, known as <em>control data</em>, stored in
2465 <em>control files</em>.
2466 Control files are used for source packages, binary packages and
2467 the <file>.changes</file> files which control the installation
2468 of uploaded files<footnote>
2469 <prgn>dpkg</prgn>'s internal databases are in a similar
2474 <sect id="controlsyntax">
2475 <heading>Syntax of control files</heading>
2478 A control file consists of one or more paragraphs of
2480 The paragraphs are also sometimes referred to as stanzas.
2482 The paragraphs are separated by empty lines. Parsers may accept
2483 lines consisting solely of spaces and tabs as paragraph
2484 separators, but control files should use empty lines. Some control
2485 files allow only one paragraph; others allow several, in
2486 which case each paragraph usually refers to a different
2487 package. (For example, in source packages, the first
2488 paragraph refers to the source package, and later paragraphs
2489 refer to binary packages generated from the source.) The
2490 ordering of the paragraphs in control files is significant.
2494 Each paragraph consists of a series of data fields; each
2495 field consists of the field name, followed by a colon and
2496 then the data/value associated with that field. The field
2497 name is composed of printable ASCII characters (i.e.,
2498 characters that have values between 33 and 126, inclusive)
2499 except colon and must not with a begin with #. The
2500 field ends at the end of the line or at the end of the
2501 last continuation line (see below). Horizontal whitespace
2502 (spaces and tabs) may occur immediately before or after the
2503 value and is ignored there; it is conventional to put a
2504 single space after the colon. For example, a field might
2506 <example compact="compact">
2509 the field name is <tt>Package</tt> and the field value
2514 A paragraph must not contain more than one instance of a
2515 particular field name.
2519 There are three types of fields:
2523 The field, including its value, must be a single line. Folding
2524 of the field is not permitted. This is the default field type
2525 if the definition of the field does not specify a different
2530 The value of a folded field is a logical line that may span
2531 several lines. The lines after the first are called
2532 continuation lines and must start with a space or a tab.
2533 Whitespace, including any newlines, is not significant in the
2534 field values of folded fields.<footnote>
2535 This folding method is similar to RFC 5322, allowing control
2536 files that contain only one paragraph and no multiline fields
2537 to be read by parsers written for RFC 5322.
2540 <tag>multiline</tag>
2542 The value of a multiline field may comprise multiple continuation
2543 lines. The first line of the value, the part on the same line as
2544 the field name, often has special significance or may have to be
2545 empty. Other lines are added following the same syntax as the
2546 continuation lines of the folded fields. Whitespace, including newlines,
2547 is significant in the values of multiline fields.
2553 Whitespace must not appear
2554 inside names (of packages, architectures, files or anything
2555 else) or version numbers, or between the characters of
2556 multi-character version relationships.
2560 The presence and purpose of a field, and the syntax of its
2561 value may differ between types of control files.
2565 Field names are not case-sensitive, but it is usual to
2566 capitalize the field names using mixed case as shown below.
2567 Field values are case-sensitive unless the description of the
2568 field says otherwise.
2572 Paragraph separators (empty lines) and lines consisting only of
2573 spaces and tabs are not allowed within field values or between
2574 fields. Empty lines in field values are usually escaped by
2575 representing them by a space followed by a dot.
2579 Lines starting with # without any preceding whitespace are comments
2580 lines that are only permitted in source package control files
2581 (<file>debian/control</file>). These comment lines are ignored, even
2582 between two continuation lines. They do not end logical lines.
2586 All control files must be encoded in UTF-8.
2590 <sect id="sourcecontrolfiles">
2591 <heading>Source package control files -- <file>debian/control</file></heading>
2594 The <file>debian/control</file> file contains the most vital
2595 (and version-independent) information about the source package
2596 and about the binary packages it creates.
2600 The first paragraph of the control file contains information about
2601 the source package in general. The subsequent sets each describe a
2602 binary package that the source tree builds.
2606 The fields in the general paragraph (the first one, for the source
2609 <list compact="compact">
2610 <item><qref id="f-Source"><tt>Source</tt></qref> (mandatory)</item>
2611 <item><qref id="f-Maintainer"><tt>Maintainer</tt></qref> (mandatory)</item>
2612 <item><qref id="f-Uploaders"><tt>Uploaders</tt></qref></item>
2613 <item><qref id="f-DM-Upload-Allowed"><tt>DM-Upload-Allowed</tt></qref></item>
2614 <item><qref id="f-Section"><tt>Section</tt></qref> (recommended)</item>
2615 <item><qref id="f-Priority"><tt>Priority</tt></qref> (recommended)</item>
2616 <item><qref id="sourcebinarydeps"><tt>Build-Depends</tt> et al</qref></item>
2617 <item><qref id="f-Standards-Version"><tt>Standards-Version</tt></qref> (recommended)</item>
2618 <item><qref id="f-Homepage"><tt>Homepage</tt></qref></item>
2623 The fields in the binary package paragraphs are:
2625 <list compact="compact">
2626 <item><qref id="f-Package"><tt>Package</tt></qref> (mandatory)</item>
2627 <item><qref id="f-Architecture"><tt>Architecture</tt></qref> (mandatory)</item>
2628 <item><qref id="f-Section"><tt>Section</tt></qref> (recommended)</item>
2629 <item><qref id="f-Priority"><tt>Priority</tt></qref> (recommended)</item>
2630 <item><qref id="f-Essential"><tt>Essential</tt></qref></item>
2631 <item><qref id="binarydeps"><tt>Depends</tt> et al</qref></item>
2632 <item><qref id="f-Description"><tt>Description</tt></qref> (mandatory)</item>
2633 <item><qref id="f-Homepage"><tt>Homepage</tt></qref></item>
2638 The syntax and semantics of the fields are described below.
2642 These fields are used by <prgn>dpkg-gencontrol</prgn> to
2643 generate control files for binary packages (see below), by
2644 <prgn>dpkg-genchanges</prgn> to generate the
2645 <file>.changes</file> file to accompany the upload, and by
2646 <prgn>dpkg-source</prgn> when it creates the
2647 <file>.dsc</file> source control file as part of a source
2648 archive. Some fields are folded in <file>debian/control</file>,
2649 but not in any other control
2650 file. These tools are responsible for removing the line
2651 breaks from such fields when using fields from
2652 <file>debian/control</file> to generate other control files.
2656 The fields here may contain variable references - their
2657 values will be substituted by <prgn>dpkg-gencontrol</prgn>,
2658 <prgn>dpkg-genchanges</prgn> or <prgn>dpkg-source</prgn>
2659 when they generate output control files.
2660 See <ref id="substvars"> for details.
2664 <sect id="binarycontrolfiles">
2665 <heading>Binary package control files -- <file>DEBIAN/control</file></heading>
2668 The <file>DEBIAN/control</file> file contains the most vital
2669 (and version-dependent) information about a binary package. It
2670 consists of a single paragraph.
2674 The fields in this file are:
2676 <list compact="compact">
2677 <item><qref id="f-Package"><tt>Package</tt></qref> (mandatory)</item>
2678 <item><qref id="f-Source"><tt>Source</tt></qref></item>
2679 <item><qref id="f-Version"><tt>Version</tt></qref> (mandatory)</item>
2680 <item><qref id="f-Section"><tt>Section</tt></qref> (recommended)</item>
2681 <item><qref id="f-Priority"><tt>Priority</tt></qref> (recommended)</item>
2682 <item><qref id="f-Architecture"><tt>Architecture</tt></qref> (mandatory)</item>
2683 <item><qref id="f-Essential"><tt>Essential</tt></qref></item>
2684 <item><qref id="binarydeps"><tt>Depends</tt> et al</qref></item>
2685 <item><qref id="f-Installed-Size"><tt>Installed-Size</tt></qref></item>
2686 <item><qref id="f-Maintainer"><tt>Maintainer</tt></qref> (mandatory)</item>
2687 <item><qref id="f-Description"><tt>Description</tt></qref> (mandatory)</item>
2688 <item><qref id="f-Homepage"><tt>Homepage</tt></qref></item>
2693 <sect id="debiansourcecontrolfiles">
2694 <heading>Debian source control files -- <tt>.dsc</tt></heading>
2697 This file consists of a single paragraph, possibly surrounded by
2698 a PGP signature. The fields of that paragraph are listed below.
2699 Their syntax is described above, in <ref id="pkg-controlfields">.
2701 <list compact="compact">
2702 <item><qref id="f-Format"><tt>Format</tt></qref> (mandatory)</item>
2703 <item><qref id="f-Source"><tt>Source</tt></qref> (mandatory)</item>
2704 <item><qref id="f-Binary"><tt>Binary</tt></qref></item>
2705 <item><qref id="f-Architecture"><tt>Architecture</tt></qref></item>
2706 <item><qref id="f-Version"><tt>Version</tt></qref> (mandatory)</item>
2707 <item><qref id="f-Maintainer"><tt>Maintainer</tt></qref> (mandatory)</item>
2708 <item><qref id="f-Uploaders"><tt>Uploaders</tt></qref></item>
2709 <item><qref id="f-DM-Upload-Allowed"><tt>DM-Upload-Allowed</tt></qref></item>
2710 <item><qref id="f-Homepage"><tt>Homepage</tt></qref></item>
2711 <item><qref id="f-Standards-Version"><tt>Standards-Version</tt></qref> (recommended)</item>
2712 <item><qref id="sourcebinarydeps"><tt>Build-Depends</tt> et al</qref></item>
2713 <item><qref id="f-Checksums"><tt>Checksums-Sha1</tt>
2714 and <tt>Checksums-Sha256</tt></qref> (recommended)</item>
2715 <item><qref id="f-Files"><tt>Files</tt></qref> (mandatory)</item>
2720 The Debian source control file is generated by
2721 <prgn>dpkg-source</prgn> when it builds the source
2722 archive, from other files in the source package,
2723 described above. When unpacking, it is checked against
2724 the files and directories in the other parts of the
2730 <sect id="debianchangesfiles">
2731 <heading>Debian changes files -- <file>.changes</file></heading>
2734 The <file>.changes</file> files are used by the Debian archive
2735 maintenance software to process updates to packages. They
2736 consist of a single paragraph, possibly surrounded by a PGP
2737 signature. That paragraph contains information from the
2738 <file>debian/control</file> file and other data about the
2739 source package gathered via <file>debian/changelog</file>
2740 and <file>debian/rules</file>.
2744 <file>.changes</file> files have a format version that is
2745 incremented whenever the documented fields or their meaning
2746 change. This document describes format &changesversion;.
2750 The fields in this file are:
2752 <list compact="compact">
2753 <item><qref id="f-Format"><tt>Format</tt></qref> (mandatory)</item>
2754 <item><qref id="f-Date"><tt>Date</tt></qref> (mandatory)</item>
2755 <item><qref id="f-Source"><tt>Source</tt></qref> (mandatory)</item>
2756 <item><qref id="f-Binary"><tt>Binary</tt></qref> (mandatory)</item>
2757 <item><qref id="f-Architecture"><tt>Architecture</tt></qref> (mandatory)</item>
2758 <item><qref id="f-Version"><tt>Version</tt></qref> (mandatory)</item>
2759 <item><qref id="f-Distribution"><tt>Distribution</tt></qref> (mandatory)</item>
2760 <item><qref id="f-Urgency"><tt>Urgency</tt></qref> (recommended)</item>
2761 <item><qref id="f-Maintainer"><tt>Maintainer</tt></qref> (mandatory)</item>
2762 <item><qref id="f-Changed-By"><tt>Changed-By</tt></qref></item>
2763 <item><qref id="f-Description"><tt>Description</tt></qref> (mandatory)</item>
2764 <item><qref id="f-Closes"><tt>Closes</tt></qref></item>
2765 <item><qref id="f-Changes"><tt>Changes</tt></qref> (mandatory)</item>
2766 <item><qref id="f-Checksums"><tt>Checksums-Sha1</tt>
2767 and <tt>Checksums-Sha256</tt></qref> (recommended)</item>
2768 <item><qref id="f-Files"><tt>Files</tt></qref> (mandatory)</item>
2773 <sect id="controlfieldslist">
2774 <heading>List of fields</heading>
2776 <sect1 id="f-Source">
2777 <heading><tt>Source</tt></heading>
2780 This field identifies the source package name.
2784 In <file>debian/control</file> or a <file>.dsc</file> file,
2785 this field must contain only the name of the source package.
2789 In a binary package control file or a <file>.changes</file>
2790 file, the source package name may be followed by a version
2791 number in parentheses<footnote>
2792 It is customary to leave a space after the package name
2793 if a version number is specified.
2795 This version number may be omitted (and is, by
2796 <prgn>dpkg-gencontrol</prgn>) if it has the same value as
2797 the <tt>Version</tt> field of the binary package in
2798 question. The field itself may be omitted from a binary
2799 package control file when the source package has the same
2800 name and version as the binary package.
2804 Package names (both source and binary,
2805 see <ref id="f-Package">) must consist only of lower case
2806 letters (<tt>a-z</tt>), digits (<tt>0-9</tt>), plus
2807 (<tt>+</tt>) and minus (<tt>-</tt>) signs, and periods
2808 (<tt>.</tt>). They must be at least two characters long and
2809 must start with an alphanumeric character.
2813 <sect1 id="f-Maintainer">
2814 <heading><tt>Maintainer</tt></heading>
2817 The package maintainer's name and email address. The name
2818 must come first, then the email address inside angle
2819 brackets <tt><></tt> (in RFC822 format).
2823 If the maintainer's name contains a full stop then the
2824 whole field will not work directly as an email address due
2825 to a misfeature in the syntax specified in RFC822; a
2826 program using this field as an address must check for this
2827 and correct the problem if necessary (for example by
2828 putting the name in round brackets and moving it to the
2829 end, and bringing the email address forward).
2833 See <ref id="maintainer"> for additional requirements and
2834 information about package maintainers.
2838 <sect1 id="f-Uploaders">
2839 <heading><tt>Uploaders</tt></heading>
2842 List of the names and email addresses of co-maintainers of the
2843 package, if any. If the package has other maintainers besides
2844 the one named in the <qref id="f-Maintainer">Maintainer
2845 field</qref>, their names and email addresses should be listed
2846 here. The format of each entry is the same as that of the
2847 Maintainer field, and multiple entries must be comma
2852 This is normally an optional field, but if
2853 the <tt>Maintainer</tt> control field names a group of people
2854 and a shared email address, the <tt>Uploaders</tt> field must
2855 be present and must contain at least one human with their
2856 personal email address.
2860 The Uploaders field in <file>debian/control</file> can be folded.
2864 <sect1 id="f-Changed-By">
2865 <heading><tt>Changed-By</tt></heading>
2868 The name and email address of the person who prepared this
2869 version of the package, usually a maintainer. The syntax is
2870 the same as for the <qref id="f-Maintainer">Maintainer
2875 <sect1 id="f-Section">
2876 <heading><tt>Section</tt></heading>
2879 This field specifies an application area into which the package
2880 has been classified. See <ref id="subsections">.
2884 When it appears in the <file>debian/control</file> file,
2885 it gives the value for the subfield of the same name in
2886 the <tt>Files</tt> field of the <file>.changes</file> file.
2887 It also gives the default for the same field in the binary
2892 <sect1 id="f-Priority">
2893 <heading><tt>Priority</tt></heading>
2896 This field represents how important it is that the user
2897 have the package installed. See <ref id="priorities">.
2901 When it appears in the <file>debian/control</file> file,
2902 it gives the value for the subfield of the same name in
2903 the <tt>Files</tt> field of the <file>.changes</file> file.
2904 It also gives the default for the same field in the binary
2909 <sect1 id="f-Package">
2910 <heading><tt>Package</tt></heading>
2913 The name of the binary package.
2917 Binary package names must follow the same syntax and
2918 restrictions as source package names. See <ref id="f-Source">
2923 <sect1 id="f-Architecture">
2924 <heading><tt>Architecture</tt></heading>
2927 Depending on context and the control file used, the
2928 <tt>Architecture</tt> field can include the following sets of
2932 A unique single word identifying a Debian machine
2933 architecture as described in <ref id="arch-spec">.
2936 An architecture wildcard identifying a set of Debian
2937 machine architectures, see <ref id="arch-wildcard-spec">.
2938 <tt>any</tt> matches all Debian machine architectures
2939 and is the most frequently used.
2942 <tt>all</tt>, which indicates an
2943 architecture-independent package.
2946 <tt>source</tt>, which indicates a source package.
2952 In the main <file>debian/control</file> file in the source
2953 package, this field may contain the special
2954 value <tt>all</tt>, the special architecture
2955 wildcard <tt>any</tt>, or a list of specific and wildcard
2956 architectures separated by spaces. If <tt>all</tt>
2957 or <tt>any</tt> appears, that value must be the entire
2958 contents of the field. Most packages will use
2959 either <tt>all</tt> or <tt>any</tt>.
2963 Specifying a specific list of architectures indicates that the
2964 source will build an architecture-dependent package only on
2965 architectures included in the list. Specifying a list of
2966 architecture wildcards indicates that the source will build an
2967 architecture-dependent package on only those architectures
2968 that match any of the specified architecture wildcards.
2969 Specifying a list of architectures or architecture wildcards
2970 other than <tt>any</tt> is for the minority of cases where a
2971 program is not portable or is not useful on some
2972 architectures. Where possible, the program should be made
2977 In the Debian source control file <file>.dsc</file>, this
2978 field contains a list of architectures and architecture
2979 wildcards separated by spaces. When the list contains the
2980 architecture wildcard <tt>any</tt>, the only other value
2981 allowed in the list is <tt>all</tt>.
2985 The list may include (or consist solely of) the special
2986 value <tt>all</tt>. In other words, in <file>.dsc</file>
2987 files unlike the <file>debian/control</file>, <tt>all</tt> may
2988 occur in combination with specific architectures.
2989 The <tt>Architecture</tt> field in the Debian source control
2990 file <file>.dsc</file> is generally constructed from
2991 the <tt>Architecture</tt> fields in
2992 the <file>debian/control</file> in the source package.
2996 Specifying only <tt>any</tt> indicates that the source package
2997 isn't dependent on any particular architecture and should
2998 compile fine on any one. The produced binary package(s)
2999 will be specific to whatever the current build architecture is.
3003 Specifying only <tt>all</tt> indicates that the source package
3004 will only build architecture-independent packages.
3008 Specifying <tt>any all</tt> indicates that the source package
3009 isn't dependent on any particular architecture. The set of
3010 produced binary packages will include at least one
3011 architecture-dependant package and one architecture-independent
3016 Specifying a list of architectures or architecture wildcards
3017 indicates that the source will build an architecture-dependent
3018 package, and will only work correctly on the listed or
3019 matching architectures. If the source package also builds at
3020 least one architecture-independent package, <tt>all</tt> will
3021 also be included in the list.
3025 In a <file>.changes</file> file, the <tt>Architecture</tt>
3026 field lists the architecture(s) of the package(s) currently
3027 being uploaded. This will be a list; if the source for the
3028 package is also being uploaded, the special
3029 entry <tt>source</tt> is also present. <tt>all</tt> will be
3030 present if any architecture-independent packages are being
3031 uploaded. Architecture wildcards such as <tt>any</tt> must
3032 never occur in the <tt>Architecture</tt> field in
3033 the <file>.changes</file> file.
3037 See <ref id="debianrules"> for information on how to get
3038 the architecture for the build process.
3042 <sect1 id="f-Essential">
3043 <heading><tt>Essential</tt></heading>
3046 This is a boolean field which may occur only in the
3047 control file of a binary package or in a per-package fields
3048 paragraph of a source package control file.
3052 If set to <tt>yes</tt> then the package management system
3053 will refuse to remove the package (upgrading and replacing
3054 it is still possible). The other possible value is <tt>no</tt>,
3055 which is the same as not having the field at all.
3060 <heading>Package interrelationship fields:
3061 <tt>Depends</tt>, <tt>Pre-Depends</tt>,
3062 <tt>Recommends</tt>, <tt>Suggests</tt>,
3063 <tt>Breaks</tt>, <tt>Conflicts</tt>,
3064 <tt>Provides</tt>, <tt>Replaces</tt>, <tt>Enhances</tt>
3068 These fields describe the package's relationships with
3069 other packages. Their syntax and semantics are described
3070 in <ref id="relationships">.</p>
3073 <sect1 id="f-Standards-Version">
3074 <heading><tt>Standards-Version</tt></heading>
3077 The most recent version of the standards (the policy
3078 manual and associated texts) with which the package
3083 The version number has four components: major and minor
3084 version number and major and minor patch level. When the
3085 standards change in a way that requires every package to
3086 change the major number will be changed. Significant
3087 changes that will require work in many packages will be
3088 signaled by a change to the minor number. The major patch
3089 level will be changed for any change to the meaning of the
3090 standards, however small; the minor patch level will be
3091 changed when only cosmetic, typographical or other edits
3092 are made which neither change the meaning of the document
3093 nor affect the contents of packages.
3097 Thus only the first three components of the policy version
3098 are significant in the <em>Standards-Version</em> control
3099 field, and so either these three components or all four
3100 components may be specified.<footnote>
3101 In the past, people specified the full version number
3102 in the Standards-Version field, for example "2.3.0.0".
3103 Since minor patch-level changes don't introduce new
3104 policy, it was thought it would be better to relax
3105 policy and only require the first 3 components to be
3106 specified, in this example "2.3.0". All four
3107 components may still be used if someone wishes to do so.
3113 <sect1 id="f-Version">
3114 <heading><tt>Version</tt></heading>
3117 The version number of a package. The format is:
3118 [<var>epoch</var><tt>:</tt>]<var>upstream_version</var>[<tt>-</tt><var>debian_revision</var>]
3122 The three components here are:
3124 <tag><var>epoch</var></tag>
3127 This is a single (generally small) unsigned integer. It
3128 may be omitted, in which case zero is assumed. If it is
3129 omitted then the <var>upstream_version</var> may not
3134 It is provided to allow mistakes in the version numbers
3135 of older versions of a package, and also a package's
3136 previous version numbering schemes, to be left behind.
3140 <tag><var>upstream_version</var></tag>
3143 This is the main part of the version number. It is
3144 usually the version number of the original ("upstream")
3145 package from which the <file>.deb</file> file has been made,
3146 if this is applicable. Usually this will be in the same
3147 format as that specified by the upstream author(s);
3148 however, it may need to be reformatted to fit into the
3149 package management system's format and comparison
3154 The comparison behavior of the package management system
3155 with respect to the <var>upstream_version</var> is
3156 described below. The <var>upstream_version</var>
3157 portion of the version number is mandatory.
3161 The <var>upstream_version</var> may contain only
3162 alphanumerics<footnote>
3163 Alphanumerics are <tt>A-Za-z0-9</tt> only.
3165 and the characters <tt>.</tt> <tt>+</tt> <tt>-</tt>
3166 <tt>:</tt> <tt>~</tt> (full stop, plus, hyphen, colon,
3167 tilde) and should start with a digit. If there is no
3168 <var>debian_revision</var> then hyphens are not allowed;
3169 if there is no <var>epoch</var> then colons are not
3174 <tag><var>debian_revision</var></tag>
3177 This part of the version number specifies the version of
3178 the Debian package based on the upstream version. It
3179 may contain only alphanumerics and the characters
3180 <tt>+</tt> <tt>.</tt> <tt>~</tt> (plus, full stop,
3181 tilde) and is compared in the same way as the
3182 <var>upstream_version</var> is.
3186 It is optional; if it isn't present then the
3187 <var>upstream_version</var> may not contain a hyphen.
3188 This format represents the case where a piece of
3189 software was written specifically to be a Debian
3190 package, where the Debian package source must always
3191 be identical to the pristine source and therefore no
3192 revision indication is required.
3196 It is conventional to restart the
3197 <var>debian_revision</var> at <tt>1</tt> each time the
3198 <var>upstream_version</var> is increased.
3202 The package management system will break the version
3203 number apart at the last hyphen in the string (if there
3204 is one) to determine the <var>upstream_version</var> and
3205 <var>debian_revision</var>. The absence of a
3206 <var>debian_revision</var> is equivalent to a
3207 <var>debian_revision</var> of <tt>0</tt>.
3214 When comparing two version numbers, first the <var>epoch</var>
3215 of each are compared, then the <var>upstream_version</var> if
3216 <var>epoch</var> is equal, and then <var>debian_revision</var>
3217 if <var>upstream_version</var> is also equal.
3218 <var>epoch</var> is compared numerically. The
3219 <var>upstream_version</var> and <var>debian_revision</var>
3220 parts are compared by the package management system using the
3221 following algorithm:
3225 The strings are compared from left to right.
3229 First the initial part of each string consisting entirely of
3230 non-digit characters is determined. These two parts (one of
3231 which may be empty) are compared lexically. If a difference
3232 is found it is returned. The lexical comparison is a
3233 comparison of ASCII values modified so that all the letters
3234 sort earlier than all the non-letters and so that a tilde
3235 sorts before anything, even the end of a part. For example,
3236 the following parts are in sorted order from earliest to
3237 latest: <tt>~~</tt>, <tt>~~a</tt>, <tt>~</tt>, the empty part,
3238 <tt>a</tt>.<footnote>
3239 One common use of <tt>~</tt> is for upstream pre-releases.
3240 For example, <tt>1.0~beta1~svn1245</tt> sorts earlier than
3241 <tt>1.0~beta1</tt>, which sorts earlier than <tt>1.0</tt>.
3246 Then the initial part of the remainder of each string which
3247 consists entirely of digit characters is determined. The
3248 numerical values of these two parts are compared, and any
3249 difference found is returned as the result of the comparison.
3250 For these purposes an empty string (which can only occur at
3251 the end of one or both version strings being compared) counts
3256 These two steps (comparing and removing initial non-digit
3257 strings and initial digit strings) are repeated until a
3258 difference is found or both strings are exhausted.
3262 Note that the purpose of epochs is to allow us to leave behind
3263 mistakes in version numbering, and to cope with situations
3264 where the version numbering scheme changes. It is
3265 <em>not</em> intended to cope with version numbers containing
3266 strings of letters which the package management system cannot
3267 interpret (such as <tt>ALPHA</tt> or <tt>pre-</tt>), or with
3268 silly orderings.<footnote>
3269 The author of this manual has heard of a package whose
3270 versions went <tt>1.1</tt>, <tt>1.2</tt>, <tt>1.3</tt>,
3271 <tt>1</tt>, <tt>2.1</tt>, <tt>2.2</tt>, <tt>2</tt> and so
3277 <sect1 id="f-Description">
3278 <heading><tt>Description</tt></heading>
3281 In a source or binary control file, the <tt>Description</tt>
3282 field contains a description of the binary package, consisting
3283 of two parts, the synopsis or the short description, and the
3284 long description. It is a multiline field with the following
3290 Description: <single line synopsis>
3291 <extended description over several lines>
3296 The lines in the extended description can have these formats:
3302 Those starting with a single space are part of a paragraph.
3303 Successive lines of this form will be word-wrapped when
3304 displayed. The leading space will usually be stripped off.
3308 Those starting with two or more spaces. These will be
3309 displayed verbatim. If the display cannot be panned
3310 horizontally, the displaying program will line wrap them "hard"
3311 (i.e., without taking account of word breaks). If it can they
3312 will be allowed to trail off to the right. None, one or two
3313 initial spaces may be deleted, but the number of spaces
3314 deleted from each line will be the same (so that you can have
3315 indenting work correctly, for example).
3319 Those containing a single space followed by a single full stop
3320 character. These are rendered as blank lines. This is the
3321 <em>only</em> way to get a blank line<footnote>
3322 Completely empty lines will not be rendered as blank lines.
3323 Instead, they will cause the parser to think you're starting
3324 a whole new record in the control file, and will therefore
3325 likely abort with an error.
3330 Those containing a space, a full stop and some more characters.
3331 These are for future expansion. Do not use them.
3337 Do not use tab characters. Their effect is not predictable.
3341 See <ref id="descriptions"> for further information on this.
3345 In a <file>.changes</file> file, the <tt>Description</tt>
3346 field contains a summary of the descriptions for the packages
3347 being uploaded. For this case, the first line of the field
3348 value (the part on the same line as <tt>Description:</tt>) is
3349 always empty. It is a multiline field, with one
3350 line per package. Each line is
3351 indented by one space and contains the name of a binary
3352 package, a space, a hyphen (<tt>-</tt>), a space, and the
3353 short description line from that package.
3357 <sect1 id="f-Distribution">
3358 <heading><tt>Distribution</tt></heading>
3361 In a <file>.changes</file> file or parsed changelog output
3362 this contains the (space-separated) name(s) of the
3363 distribution(s) where this version of the package should
3364 be installed. Valid distributions are determined by the
3365 archive maintainers.<footnote>
3366 Example distribution names in the Debian archive used in
3367 <file>.changes</file> files are:
3368 <taglist compact="compact">
3369 <tag><em>unstable</em></tag>
3371 This distribution value refers to the
3372 <em>developmental</em> part of the Debian distribution
3373 tree. Most new packages, new upstream versions of
3374 packages and bug fixes go into the <em>unstable</em>
3378 <tag><em>experimental</em></tag>
3380 The packages with this distribution value are deemed
3381 by their maintainers to be high risk. Oftentimes they
3382 represent early beta or developmental packages from
3383 various sources that the maintainers want people to
3384 try, but are not ready to be a part of the other parts
3385 of the Debian distribution tree.
3390 Others are used for updating stable releases or for
3391 security uploads. More information is available in the
3392 Debian Developer's Reference, section "The Debian
3396 The Debian archive software only supports listing a single
3397 distribution. Migration of packages to other distributions is
3398 handled outside of the upload process.
3403 <heading><tt>Date</tt></heading>
3406 This field includes the date the package was built or last
3407 edited. It must be in the same format as the <var>date</var>
3408 in a <file>debian/changelog</file> entry.
3412 The value of this field is usually extracted from the
3413 <file>debian/changelog</file> file - see
3414 <ref id="dpkgchangelog">).
3418 <sect1 id="f-Format">
3419 <heading><tt>Format</tt></heading>
3422 In <qref id="debianchangesfiles"><file>.changes</file></qref>
3423 files, this field declares the format version of that file.
3424 The syntax of the field value is the same as that of
3425 a <qref id="f-Version">package version number</qref> except
3426 that no epoch or Debian revision is allowed. The format
3427 described in this document is <tt>&changesversion;</tt>.
3431 In <qref id="debiansourcecontrolfiles"><file>.dsc</file>
3432 Debian source control</qref> files, this field declares the
3433 format of the source package. The field value is used by
3434 programs acting on a source package to interpret the list of
3435 files in the source package and determine how to unpack it.
3436 The syntax of the field value is a numeric major revision, a
3437 period, a numeric minor revision, and then an optional subtype
3438 after whitespace, which if specified is an alphanumeric word
3439 in parentheses. The subtype is optional in the syntax but may
3440 be mandatory for particular source format revisions.
3442 The source formats currently supported by the Debian archive
3443 software are <tt>1.0</tt>, <tt>3.0 (native)</tt>,
3444 and <tt>3.0 (quilt)</tt>.
3449 <sect1 id="f-Urgency">
3450 <heading><tt>Urgency</tt></heading>
3453 This is a description of how important it is to upgrade to
3454 this version from previous ones. It consists of a single
3455 keyword taking one of the values <tt>low</tt>,
3456 <tt>medium</tt>, <tt>high</tt>, <tt>emergency</tt>, or
3457 <tt>critical</tt><footnote>
3458 Other urgency values are supported with configuration
3459 changes in the archive software but are not used in Debian.
3460 The urgency affects how quickly a package will be considered
3461 for inclusion into the <tt>testing</tt> distribution and
3462 gives an indication of the importance of any fixes included
3463 in the upload. <tt>Emergency</tt> and <tt>critical</tt> are
3464 treated as synonymous.
3465 </footnote> (not case-sensitive) followed by an optional
3466 commentary (separated by a space) which is usually in
3467 parentheses. For example:
3470 Urgency: low (HIGH for users of diversions)
3476 The value of this field is usually extracted from the
3477 <file>debian/changelog</file> file - see
3478 <ref id="dpkgchangelog">.
3482 <sect1 id="f-Changes">
3483 <heading><tt>Changes</tt></heading>
3486 This multiline field contains the human-readable changes data, describing
3487 the differences between the last version and the current one.
3491 The first line of the field value (the part on the same line
3492 as <tt>Changes:</tt>) is always empty. The content of the
3493 field is expressed as continuation lines, with each line
3494 indented by at least one space. Blank lines must be
3495 represented by a line consisting only of a space and a full
3500 The value of this field is usually extracted from the
3501 <file>debian/changelog</file> file - see
3502 <ref id="dpkgchangelog">).
3506 Each version's change information should be preceded by a
3507 "title" line giving at least the version, distribution(s)
3508 and urgency, in a human-readable way.
3512 If data from several versions is being returned the entry
3513 for the most recent version should be returned first, and
3514 entries should be separated by the representation of a
3515 blank line (the "title" line may also be followed by the
3516 representation of a blank line).
3520 <sect1 id="f-Binary">
3521 <heading><tt>Binary</tt></heading>
3524 This folded field is a list of binary packages. Its syntax and
3525 meaning varies depending on the control file in which it
3530 When it appears in the <file>.dsc</file> file, it lists binary
3531 packages which a source package can produce, separated by
3533 A space after each comma is conventional.
3534 </footnote>. The source package
3535 does not necessarily produce all of these binary packages for
3536 every architecture. The source control file doesn't contain
3537 details of which architectures are appropriate for which of
3538 the binary packages.
3542 When it appears in a <file>.changes</file> file, it lists the
3543 names of the binary packages being uploaded, separated by
3544 whitespace (not commas).
3548 <sect1 id="f-Installed-Size">
3549 <heading><tt>Installed-Size</tt></heading>
3552 This field appears in the control files of binary packages,
3553 and in the <file>Packages</file> files. It gives an estimate
3554 of the total amount of disk space required to install the
3555 named package. Actual installed size may vary based on block
3556 size, file system properties, or actions taken by package
3561 The disk space is given as the integer value of the estimated
3562 installed size in bytes, divided by 1024 and rounded up.
3566 <sect1 id="f-Files">
3567 <heading><tt>Files</tt></heading>
3570 This field contains a list of files with information about
3571 each one. The exact information and syntax varies with
3576 In all cases, Files is a multiline field. The first line of
3577 the field value (the part on the same line as <tt>Files:</tt>)
3578 is always empty. The content of the field is expressed as
3579 continuation lines, one line per file. Each line must be
3580 indented by one space and contain a number of sub-fields,
3581 separated by spaces, as described below.
3585 In the <file>.dsc</file> file, each line contains the MD5
3586 checksum, size and filename of the tar file and (if
3587 applicable) diff file which make up the remainder of the
3588 source package<footnote>
3589 That is, the parts which are not the <tt>.dsc</tt>.
3590 </footnote>. For example:
3593 c6f698f19f2a2aa07dbb9bbda90a2754 571925 example_1.2.orig.tar.gz
3594 938512f08422f3509ff36f125f5873ba 6220 example_1.2-1.diff.gz
3596 The exact forms of the filenames are described
3597 in <ref id="pkg-sourcearchives">.
3601 In the <file>.changes</file> file this contains one line per
3602 file being uploaded. Each line contains the MD5 checksum,
3603 size, section and priority and the filename. For example:
3606 4c31ab7bfc40d3cf49d7811987390357 1428 text extra example_1.2-1.dsc
3607 c6f698f19f2a2aa07dbb9bbda90a2754 571925 text extra example_1.2.orig.tar.gz
3608 938512f08422f3509ff36f125f5873ba 6220 text extra example_1.2-1.diff.gz
3609 7c98fe853b3bbb47a00e5cd129b6cb56 703542 text extra example_1.2-1_i386.deb
3611 The <qref id="f-Section">section</qref>
3612 and <qref id="f-Priority">priority</qref> are the values of
3613 the corresponding fields in the main source control file. If
3614 no section or priority is specified then <tt>-</tt> should be
3615 used, though section and priority values must be specified for
3616 new packages to be installed properly.
3620 The special value <tt>byhand</tt> for the section in a
3621 <tt>.changes</tt> file indicates that the file in question
3622 is not an ordinary package file and must by installed by
3623 hand by the distribution maintainers. If the section is
3624 <tt>byhand</tt> the priority should be <tt>-</tt>.
3628 If a new Debian revision of a package is being shipped and
3629 no new original source archive is being distributed the
3630 <tt>.dsc</tt> must still contain the <tt>Files</tt> field
3631 entry for the original source archive
3632 <file><var>package</var>_<var>upstream-version</var>.orig.tar.gz</file>,
3633 but the <file>.changes</file> file should leave it out. In
3634 this case the original source archive on the distribution
3635 site must match exactly, byte-for-byte, the original
3636 source archive which was used to generate the
3637 <file>.dsc</file> file and diff which are being uploaded.</p>
3640 <sect1 id="f-Closes">
3641 <heading><tt>Closes</tt></heading>
3644 A space-separated list of bug report numbers that the upload
3645 governed by the .changes file closes.
3649 <sect1 id="f-Homepage">
3650 <heading><tt>Homepage</tt></heading>
3653 The URL of the web site for this package, preferably (when
3654 applicable) the site from which the original source can be
3655 obtained and any additional upstream documentation or
3656 information may be found. The content of this field is a
3657 simple URL without any surrounding characters such as
3662 <sect1 id="f-Checksums">
3663 <heading><tt>Checksums-Sha1</tt>
3664 and <tt>Checksums-Sha256</tt></heading>
3667 These multiline fields contain a list of files with a checksum and size
3668 for each one. Both <tt>Checksums-Sha1</tt>
3669 and <tt>Checksums-Sha256</tt> have the same syntax and differ
3670 only in the checksum algorithm used: SHA-1
3671 for <tt>Checksums-Sha1</tt> and SHA-256
3672 for <tt>Checksums-Sha256</tt>.
3676 <tt>Checksums-Sha1</tt> and <tt>Checksums-Sha256</tt> are
3677 multiline fields. The first line of the field value (the part
3678 on the same line as <tt>Checksums-Sha1:</tt>
3679 or <tt>Checksums-Sha256:</tt>) is always empty. The content
3680 of the field is expressed as continuation lines, one line per
3681 file. Each line consists of the checksum, a space, the file
3682 size, a space, and the file name. For example (from
3683 a <file>.changes</file> file):
3686 1f418afaa01464e63cc1ee8a66a05f0848bd155c 1276 example_1.0-1.dsc
3687 a0ed1456fad61116f868b1855530dbe948e20f06 171602 example_1.0.orig.tar.gz
3688 5e86ecf0671e113b63388dac81dd8d00e00ef298 6137 example_1.0-1.debian.tar.gz
3689 71a0ff7da0faaf608481195f9cf30974b142c183 548402 example_1.0-1_i386.deb
3691 ac9d57254f7e835bed299926fd51bf6f534597cc3fcc52db01c4bffedae81272 1276 example_1.0-1.dsc
3692 0d123be7f51e61c4bf15e5c492b484054be7e90f3081608a5517007bfb1fd128 171602 example_1.0.orig.tar.gz
3693 f54ae966a5f580571ae7d9ef5e1df0bd42d63e27cb505b27957351a495bc6288 6137 example_1.0-1.debian.tar.gz
3694 3bec05c03974fdecd11d020fc2e8250de8404867a8a2ce865160c250eb723664 548402 example_1.0-1_i386.deb
3699 In the <file>.dsc</file> file, these fields should list all
3700 files that make up the source package. In
3701 the <file>.changes</file> file, these fields should list all
3702 files being uploaded. The list of files in these fields
3703 must match the list of files in the <tt>Files</tt> field.
3707 <sect1 id="f-DM-Upload-Allowed">
3708 <heading><tt>DM-Upload-Allowed</tt></heading>
3711 The most recent version of a package uploaded to unstable or
3712 experimental must include the field <tt>DM-Upload-Allowed:
3713 yes</tt> in the source section of its source control file for
3714 the Debian archive to accept uploads signed with a key in the
3715 Debian Maintainer keyring. See the General
3716 Resolution <url id="http://www.debian.org/vote/2007/vote_003"
3717 name="Endorse the concept of Debian Maintainers"> for more
3724 <heading>User-defined fields</heading>
3727 Additional user-defined fields may be added to the
3728 source package control file. Such fields will be
3729 ignored, and not copied to (for example) binary or
3730 Debian source control files or upload control files.
3734 If you wish to add additional unsupported fields to
3735 these output files you should use the mechanism
3740 Fields in the main source control information file with
3741 names starting <tt>X</tt>, followed by one or more of
3742 the letters <tt>BCS</tt> and a hyphen <tt>-</tt>, will
3743 be copied to the output files. Only the part of the
3744 field name after the hyphen will be used in the output
3745 file. Where the letter <tt>B</tt> is used the field
3746 will appear in binary package control files, where the
3747 letter <tt>S</tt> is used in Debian source control
3748 files and where <tt>C</tt> is used in upload control
3749 (<tt>.changes</tt>) files.
3753 For example, if the main source information control file
3756 XBS-Comment: I stand between the candle and the star.
3758 then the binary and Debian source control files will contain the
3761 Comment: I stand between the candle and the star.
3770 <chapt id="maintainerscripts">
3771 <heading>Package maintainer scripts and installation procedure</heading>
3774 <heading>Introduction to package maintainer scripts</heading>
3777 It is possible to supply scripts as part of a package which
3778 the package management system will run for you when your
3779 package is installed, upgraded or removed.
3783 These scripts are the control information
3784 files <prgn>preinst</prgn>, <prgn>postinst</prgn>, <prgn>prerm</prgn>
3785 and <prgn>postrm</prgn>. They must be proper executable files;
3786 if they are scripts (which is recommended), they must start with
3787 the usual <tt>#!</tt> convention. They should be readable and
3788 executable by anyone, and must not be world-writable.
3792 The package management system looks at the exit status from
3793 these scripts. It is important that they exit with a
3794 non-zero status if there is an error, so that the package
3795 management system can stop its processing. For shell
3796 scripts this means that you <em>almost always</em> need to
3797 use <tt>set -e</tt> (this is usually true when writing shell
3798 scripts, in fact). It is also important, of course, that
3799 they exit with a zero status if everything went well.
3803 Additionally, packages interacting with users
3804 using <prgn>debconf</prgn> in the <prgn>postinst</prgn> script
3805 should install a <prgn>config</prgn> script as a control
3806 information file. See <ref id="maintscriptprompt"> for details.
3810 When a package is upgraded a combination of the scripts from
3811 the old and new packages is called during the upgrade
3812 procedure. If your scripts are going to be at all
3813 complicated you need to be aware of this, and may need to
3814 check the arguments to your scripts.
3818 Broadly speaking the <prgn>preinst</prgn> is called before
3819 (a particular version of) a package is unpacked, and the
3820 <prgn>postinst</prgn> afterwards; the <prgn>prerm</prgn>
3821 before (a version of) a package is removed and the
3822 <prgn>postrm</prgn> afterwards.
3826 Programs called from maintainer scripts should not normally
3827 have a path prepended to them. Before installation is
3828 started, the package management system checks to see if the
3829 programs <prgn>ldconfig</prgn>,
3830 <prgn>start-stop-daemon</prgn>, <prgn>install-info</prgn>,
3831 and <prgn>update-rc.d</prgn> can be found via the
3832 <tt>PATH</tt> environment variable. Those programs, and any
3833 other program that one would expect to be in the
3834 <tt>PATH</tt>, should thus be invoked without an absolute
3835 pathname. Maintainer scripts should also not reset the
3836 <tt>PATH</tt>, though they might choose to modify it by
3837 prepending or appending package-specific directories. These
3838 considerations really apply to all shell scripts.</p>
3841 <sect id="idempotency">
3842 <heading>Maintainer scripts idempotency</heading>
3845 It is necessary for the error recovery procedures that the
3846 scripts be idempotent. This means that if it is run
3847 successfully, and then it is called again, it doesn't bomb
3848 out or cause any harm, but just ensures that everything is
3849 the way it ought to be. If the first call failed, or
3850 aborted half way through for some reason, the second call
3851 should merely do the things that were left undone the first
3852 time, if any, and exit with a success status if everything
3854 This is so that if an error occurs, the user interrupts
3855 <prgn>dpkg</prgn> or some other unforeseen circumstance
3856 happens you don't leave the user with a badly-broken
3857 package when <prgn>dpkg</prgn> attempts to repeat the
3863 <sect id="controllingterminal">
3864 <heading>Controlling terminal for maintainer scripts</heading>
3867 Maintainer scripts are not guaranteed to run with a controlling
3868 terminal and may not be able to interact with the user. They
3869 must be able to fall back to noninteractive behavior if no
3870 controlling terminal is available. Maintainer scripts that
3871 prompt via a program conforming to the Debian Configuration
3872 Management Specification (see <ref id="maintscriptprompt">) may
3873 assume that program will handle falling back to noninteractive
3878 For high-priority prompts without a reasonable default answer,
3879 maintainer scripts may abort if there is no controlling
3880 terminal. However, this situation should be avoided if at all
3881 possible, since it prevents automated or unattended installs.
3882 In most cases, users will consider this to be a bug in the
3887 <sect id="exitstatus">
3888 <heading>Exit status</heading>
3891 Each script must return a zero exit status for
3892 success, or a nonzero one for failure, since the package
3893 management system looks for the exit status of these scripts
3894 and determines what action to take next based on that datum.
3898 <sect id="mscriptsinstact"><heading>Summary of ways maintainer
3903 What follows is a summary of all the ways in which maintainer
3904 scripts may be called along with what facilities those scripts
3905 may rely on being available at that time. Script names preceded
3906 by <var>new-</var> are the scripts from the new version of a
3907 package being installed, upgraded to, or downgraded to. Script
3908 names preceded by <var>old-</var> are the scripts from the old
3909 version of a package that is being upgraded from or downgraded
3914 The <prgn>preinst</prgn> script may be called in the following
3917 <tag><var>new-preinst</var> <tt>install</tt></tag>
3918 <tag><var>new-preinst</var> <tt>install</tt>
3919 <var>old-version</var></tag>
3920 <tag><var>new-preinst</var> <tt>upgrade</tt>
3921 <var>old-version</var></tag>
3923 The package will not yet be unpacked, so
3924 the <prgn>preinst</prgn> script cannot rely on any files
3925 included in its package. Only essential packages and
3926 pre-dependencies (<tt>Pre-Depends</tt>) may be assumed to be
3927 available. Pre-dependencies will have been configured at
3928 least once, but at the time the <prgn>preinst</prgn> is
3929 called they may only be in an unpacked or "Half-Configured"
3930 state if a previous version of the pre-dependency was
3931 completely configured and has not been removed since then.
3934 <tag><var>old-preinst</var> <tt>abort-upgrade</tt>
3935 <var>new-version</var></tag>
3937 Called during error handling of an upgrade that failed after
3938 unpacking the new package because the <tt>postrm
3939 upgrade</tt> action failed. The unpacked files may be
3940 partly from the new version or partly missing, so the script
3941 cannot rely on files included in the package. Package
3942 dependencies may not be available. Pre-dependencies will be
3943 at least unpacked following the same rules as above, except
3944 they may be only "Half-Installed" if an upgrade of the
3945 pre-dependency failed.<footnote>
3946 This can happen if the new version of the package no
3947 longer pre-depends on a package that had been partially
3955 The <prgn>postinst</prgn> script may be called in the following
3958 <tag><var>postinst</var> <tt>configure</tt>
3959 <var>most-recently-configured-version</var></tag>
3961 The files contained in the package will be unpacked. All
3962 package dependencies will at least be unpacked. If there
3963 are no circular dependencies involved, all package
3964 dependencies will be configured. For behavior in the case
3965 of circular dependencies, see the discussion
3966 in <ref id="binarydeps">.
3969 <tag><var>old-postinst</var> <tt>abort-upgrade</tt>
3970 <var>new-version</var></tag>
3971 <tag><var>conflictor's-postinst</var> <tt>abort-remove</tt>
3972 <tt>in-favour</tt> <var>package</var>
3973 <var>new-version</var></tag>
3974 <tag><var>postinst</var> <tt>abort-remove</tt></tag>
3975 <tag><var>deconfigured's-postinst</var>
3976 <tt>abort-deconfigure</tt> <tt>in-favour</tt>
3977 <var>failed-install-package</var> <var>version</var>
3978 [<tt>removing</tt> <var>conflicting-package</var>
3979 <var>version</var>]</tag>
3981 The files contained in the package will be unpacked. All
3982 package dependencies will at least be "Half-Installed" and
3983 will have previously been configured and not removed.
3984 However, dependencies may not be configured or even fully
3985 unpacked in some error situations.<footnote>
3986 For example, suppose packages foo and bar are installed
3987 with foo depending on bar. If an upgrade of bar were
3988 started and then aborted, and then an attempt to remove
3989 foo failed because its <prgn>prerm</prgn> script failed,
3990 foo's <tt>postinst abort-remove</tt> would be called with
3991 bar only "Half-Installed".
3993 The <prgn>postinst</prgn> should still attempt any actions
3994 for which its dependencies are required, since they will
3995 normally be available, but consider the correct error
3996 handling approach if those actions fail. Aborting
3997 the <prgn>postinst</prgn> action if commands or facilities
3998 from the package dependencies are not available is often the
4005 The <prgn>prerm</prgn> script may be called in the following
4008 <tag><var>prerm</var> <tt>remove</tt></tag>
4009 <tag><var>old-prerm</var>
4010 <tt>upgrade</tt><var>new-version</var></tag>
4011 <tag><var>conflictor's-prerm</var> <tt>remove</tt>
4012 <tt>in-favour</tt> <var>package</var>
4013 <var>new-version</var></tag>
4014 <tag><var>deconfigured's-prerm</var> <tt>deconfigure</tt>
4015 <tt>in-favour</tt> <var>package-being-installed</var>
4016 <var>version</var> [<tt>removing</tt>
4017 <var>conflicting-package</var> <var>version</var>]</tag>
4019 The package whose <prgn>prerm</prgn> is being called will be
4020 at least "Half-Installed". All package dependencies will at
4021 least be "Half-Installed" and will have previously been
4022 configured and not removed. If there was no error, all
4023 dependencies will at least be unpacked, but these actions
4024 may be called in various error states where dependencies are
4025 only "Half-Installed" due to a partial upgrade.
4028 <tag><var>new-prerm</var> <tt>failed-upgrade</tt>
4029 <var>old-version</var></tag>
4031 Called during error handling when <tt>prerm upgrade</tt>
4032 fails. The new package will not yet be unpacked, and all
4033 the same constraints as for <tt>preinst upgrade</tt> apply.
4039 The <prgn>postrm</prgn> script may be called in the following
4042 <tag><var>postrm</var> <tt>remove</tt></tag>
4043 <tag><var>postrm</var> <tt>purge</tt></tag>
4044 <tag><var>old-postrm</var> <tt>upgrade</tt>
4045 <var>new-version</var></tag>
4046 <tag><var>disappearer's-postrm</var> <tt>disappear</tt>
4047 <var>overwriter</var> <var>overwriter-version</var></tag>
4049 The <prgn>postrm</prgn> script is called after the package's
4050 files have been removed or replaced. The package
4051 whose <prgn>postrm</prgn> is being called may have
4052 previously been deconfigured and only be unpacked, at which
4053 point subsequent package changes do not consider its
4054 dependencies. Therefore, all <prgn>postrm</prgn> actions
4055 may only rely on essential packages and must gracefully skip
4056 any actions that require the package's dependencies if those
4057 dependencies are unavailable.<footnote>
4058 This is often done by checking whether the command or
4059 facility the <prgn>postrm</prgn> intends to call is
4060 available before calling it. For example:
4062 if [ "$1" = purge ] && [ -e /usr/share/debconf/confmodule ]; then
4063 . /usr/share/debconf/confmodule
4067 in <prgn>postrm</prgn> purges the <prgn>debconf</prgn>
4068 configuration for the package
4069 if <package>debconf</package> is installed.
4073 <tag><var>new-postrm</var> <tt>failed-upgrade</tt>
4074 <var>old-version</var></tag>
4076 Called when the old <tt>postrm upgrade</tt> action fails.
4077 The new package will be unpacked, but only essential
4078 packages and pre-dependencies can be relied on.
4079 Pre-dependencies will either be configured or will be
4080 "Unpacked" or "Half-Configured" but previously had been
4081 configured and was never removed.
4084 <tag><var>new-postrm</var> <tt>abort-install</tt></tag>
4085 <tag><var>new-postrm</var> <tt>abort-install</tt>
4086 <var>old-version</var></tag>
4087 <tag><var>new-postrm</var> <tt>abort-upgrade</tt>
4088 <var>old-version</var></tag>
4090 Called before unpacking the new package as part of the
4091 error handling of <prgn>preinst</prgn> failures. May assume
4092 the same state as <prgn>preinst</prgn> can assume.
4098 <sect id="unpackphase">
4099 <heading>Details of unpack phase of installation or upgrade</heading>
4102 The procedure on installation/upgrade/overwrite/disappear
4103 (i.e., when running <tt>dpkg --unpack</tt>, or the unpack
4104 stage of <tt>dpkg --install</tt>) is as follows. In each
4105 case, if a major error occurs (unless listed below) the
4106 actions are, in general, run backwards - this means that the
4107 maintainer scripts are run with different arguments in
4108 reverse order. These are the "error unwind" calls listed
4115 If a version of the package is already installed, call
4116 <example compact="compact">
4117 <var>old-prerm</var> upgrade <var>new-version</var>
4121 If the script runs but exits with a non-zero
4122 exit status, <prgn>dpkg</prgn> will attempt:
4123 <example compact="compact">
4124 <var>new-prerm</var> failed-upgrade <var>old-version</var>
4126 If this works, the upgrade continues. If this
4127 does not work, the error unwind:
4128 <example compact="compact">
4129 <var>old-postinst</var> abort-upgrade <var>new-version</var>
4131 If this works, then the old-version is
4132 "Installed", if not, the old version is in a
4133 "Half-Configured" state.
4139 If a "conflicting" package is being removed at the same time,
4140 or if any package will be broken (due to <tt>Breaks</tt>):
4143 If <tt>--auto-deconfigure</tt> is
4144 specified, call, for each package to be deconfigured
4145 due to <tt>Breaks</tt>:
4146 <example compact="compact">
4147 <var>deconfigured's-prerm</var> deconfigure \
4148 in-favour <var>package-being-installed</var> <var>version</var>
4151 <example compact="compact">
4152 <var>deconfigured's-postinst</var> abort-deconfigure \
4153 in-favour <var>package-being-installed-but-failed</var> <var>version</var>
4155 The deconfigured packages are marked as
4156 requiring configuration, so that if
4157 <tt>--install</tt> is used they will be
4158 configured again if possible.
4161 If any packages depended on a conflicting
4162 package being removed and <tt>--auto-deconfigure</tt> is
4163 specified, call, for each such package:
4164 <example compact="compact">
4165 <var>deconfigured's-prerm</var> deconfigure \
4166 in-favour <var>package-being-installed</var> <var>version</var> \
4167 removing <var>conflicting-package</var> <var>version</var>
4170 <example compact="compact">
4171 <var>deconfigured's-postinst</var> abort-deconfigure \
4172 in-favour <var>package-being-installed-but-failed</var> <var>version</var> \
4173 removing <var>conflicting-package</var> <var>version</var>
4175 The deconfigured packages are marked as
4176 requiring configuration, so that if
4177 <tt>--install</tt> is used they will be
4178 configured again if possible.
4181 To prepare for removal of each conflicting package, call:
4182 <example compact="compact">
4183 <var>conflictor's-prerm</var> remove \
4184 in-favour <var>package</var> <var>new-version</var>
4187 <example compact="compact">
4188 <var>conflictor's-postinst</var> abort-remove \
4189 in-favour <var>package</var> <var>new-version</var>
4198 If the package is being upgraded, call:
4199 <example compact="compact">
4200 <var>new-preinst</var> upgrade <var>old-version</var>
4202 If this fails, we call:
4204 <var>new-postrm</var> abort-upgrade <var>old-version</var>
4211 <var>old-postinst</var> abort-upgrade <var>new-version</var>
4213 is called. If this works, then the old version
4214 is in an "Installed" state, or else it is left
4215 in an "Unpacked" state.
4220 If it fails, then the old version is left
4221 in an "Half-Installed" state.
4228 Otherwise, if the package had some configuration
4229 files from a previous version installed (i.e., it
4230 is in the "configuration files only" state):
4231 <example compact="compact">
4232 <var>new-preinst</var> install <var>old-version</var>
4236 <var>new-postrm</var> abort-install <var>old-version</var>
4238 If this fails, the package is left in a
4239 "Half-Installed" state, which requires a
4240 reinstall. If it works, the packages is left in
4241 a "Config-Files" state.
4244 Otherwise (i.e., the package was completely purged):
4245 <example compact="compact">
4246 <var>new-preinst</var> install
4249 <example compact="compact">
4250 <var>new-postrm</var> abort-install
4252 If the error-unwind fails, the package is in a
4253 "Half-Installed" phase, and requires a
4254 reinstall. If the error unwind works, the
4255 package is in a not installed state.
4262 The new package's files are unpacked, overwriting any
4263 that may be on the system already, for example any
4264 from the old version of the same package or from
4265 another package. Backups of the old files are kept
4266 temporarily, and if anything goes wrong the package
4267 management system will attempt to put them back as
4268 part of the error unwind.
4272 It is an error for a package to contain files which
4273 are on the system in another package, unless
4274 <tt>Replaces</tt> is used (see <ref id="replaces">).
4276 The following paragraph is not currently the case:
4277 Currently the <tt>- - force-overwrite</tt> flag is
4278 enabled, downgrading it to a warning, but this may not
4284 It is a more serious error for a package to contain a
4285 plain file or other kind of non-directory where another
4286 package has a directory (again, unless
4287 <tt>Replaces</tt> is used). This error can be
4288 overridden if desired using
4289 <tt>--force-overwrite-dir</tt>, but this is not
4294 Packages which overwrite each other's files produce
4295 behavior which, though deterministic, is hard for the
4296 system administrator to understand. It can easily
4297 lead to "missing" programs if, for example, a package
4298 is unpacked which overwrites a file from another
4299 package, and is then removed again.<footnote>
4300 Part of the problem is due to what is arguably a
4301 bug in <prgn>dpkg</prgn>.
4306 A directory will never be replaced by a symbolic link
4307 to a directory or vice versa; instead, the existing
4308 state (symlink or not) will be left alone and
4309 <prgn>dpkg</prgn> will follow the symlink if there is
4318 If the package is being upgraded, call
4319 <example compact="compact">
4320 <var>old-postrm</var> upgrade <var>new-version</var>
4324 If this fails, <prgn>dpkg</prgn> will attempt:
4325 <example compact="compact">
4326 <var>new-postrm</var> failed-upgrade <var>old-version</var>
4328 If this works, installation continues. If not,
4330 <example compact="compact">
4331 <var>old-preinst</var> abort-upgrade <var>new-version</var>
4333 If this fails, the old version is left in a
4334 "Half-Installed" state. If it works, dpkg now
4336 <example compact="compact">
4337 <var>new-postrm</var> abort-upgrade <var>old-version</var>
4339 If this fails, the old version is left in a
4340 "Half-Installed" state. If it works, dpkg now
4342 <example compact="compact">
4343 <var>old-postinst</var> abort-upgrade <var>new-version</var>
4345 If this fails, the old version is in an
4352 This is the point of no return - if
4353 <prgn>dpkg</prgn> gets this far, it won't back off
4354 past this point if an error occurs. This will
4355 leave the package in a fairly bad state, which
4356 will require a successful re-installation to clear
4357 up, but it's when <prgn>dpkg</prgn> starts doing
4358 things that are irreversible.
4363 Any files which were in the old version of the package
4364 but not in the new are removed.
4368 The new file list replaces the old.
4372 The new maintainer scripts replace the old.
4376 Any packages all of whose files have been overwritten
4377 during the installation, and which aren't required for
4378 dependencies, are considered to have been removed.
4379 For each such package
4382 <prgn>dpkg</prgn> calls:
4383 <example compact="compact">
4384 <var>disappearer's-postrm</var> disappear \
4385 <var>overwriter</var> <var>overwriter-version</var>
4389 The package's maintainer scripts are removed.
4392 It is noted in the status database as being in a
4393 sane state, namely not installed (any conffiles
4394 it may have are ignored, rather than being
4395 removed by <prgn>dpkg</prgn>). Note that
4396 disappearing packages do not have their prerm
4397 called, because <prgn>dpkg</prgn> doesn't know
4398 in advance that the package is going to
4405 Any files in the package we're unpacking that are also
4406 listed in the file lists of other packages are removed
4407 from those lists. (This will lobotomize the file list
4408 of the "conflicting" package if there is one.)
4412 The backup files made during installation, above, are
4418 The new package's status is now sane, and recorded as
4423 Here is another point of no return - if the
4424 conflicting package's removal fails we do not unwind
4425 the rest of the installation; the conflicting package
4426 is left in a half-removed limbo.
4431 If there was a conflicting package we go and do the
4432 removal actions (described below), starting with the
4433 removal of the conflicting package's files (any that
4434 are also in the package being unpacked have already
4435 been removed from the conflicting package's file list,
4436 and so do not get removed now).
4442 <sect id="configdetails"><heading>Details of configuration</heading>
4445 When we configure a package (this happens with <tt>dpkg
4446 --install</tt> and <tt>dpkg --configure</tt>), we first
4447 update any <tt>conffile</tt>s and then call:
4448 <example compact="compact">
4449 <var>postinst</var> configure <var>most-recently-configured-version</var>
4454 No attempt is made to unwind after errors during
4455 configuration. If the configuration fails, the package is in
4456 a "Failed Config" state, and an error message is generated.
4460 If there is no most recently configured version
4461 <prgn>dpkg</prgn> will pass a null argument.
4464 Historical note: Truly ancient (pre-1997) versions of
4465 <prgn>dpkg</prgn> passed <tt><unknown></tt>
4466 (including the angle brackets) in this case. Even older
4467 ones did not pass a second argument at all, under any
4468 circumstance. Note that upgrades using such an old dpkg
4469 version are unlikely to work for other reasons, even if
4470 this old argument behavior is handled by your postinst script.
4476 <sect id="removedetails"><heading>Details of removal and/or
4477 configuration purging</heading>
4483 <example compact="compact">
4484 <var>prerm</var> remove
4488 If prerm fails during replacement due to conflict
4490 <var>conflictor's-postinst</var> abort-remove \
4491 in-favour <var>package</var> <var>new-version</var>
4495 <var>postinst</var> abort-remove
4499 If this fails, the package is in a "Half-Configured"
4500 state, or else it remains "Installed".
4504 The package's files are removed (except <tt>conffile</tt>s).
4507 <example compact="compact">
4508 <var>postrm</var> remove
4512 If it fails, there's no error unwind, and the package is in
4513 an "Half-Installed" state.
4518 All the maintainer scripts except the <prgn>postrm</prgn>
4523 If we aren't purging the package we stop here. Note
4524 that packages which have no <prgn>postrm</prgn> and no
4525 <tt>conffile</tt>s are automatically purged when
4526 removed, as there is no difference except for the
4527 <prgn>dpkg</prgn> status.
4531 The <tt>conffile</tt>s and any backup files
4532 (<tt>~</tt>-files, <tt>#*#</tt> files,
4533 <tt>%</tt>-files, <tt>.dpkg-{old,new,tmp}</tt>, etc.)
4538 <example compact="compact">
4539 <var>postrm</var> purge
4543 If this fails, the package remains in a "Config-Files"
4548 The package's file list is removed.
4557 <chapt id="relationships">
4558 <heading>Declaring relationships between packages</heading>
4560 <sect id="depsyntax">
4561 <heading>Syntax of relationship fields</heading>
4564 These fields all have a uniform syntax. They are a list of
4565 package names separated by commas.
4569 In the <tt>Depends</tt>, <tt>Recommends</tt>,
4570 <tt>Suggests</tt>, <tt>Pre-Depends</tt>,
4571 <tt>Build-Depends</tt> and <tt>Build-Depends-Indep</tt>
4572 control fields of the package, which declare
4573 dependencies on other packages, the package names listed may
4574 also include lists of alternative package names, separated
4575 by vertical bar (pipe) symbols <tt>|</tt>. In such a case,
4576 if any one of the alternative packages is installed, that
4577 part of the dependency is considered to be satisfied.
4581 All of the fields except for <tt>Provides</tt> may restrict
4582 their applicability to particular versions of each named
4583 package. This is done in parentheses after each individual
4584 package name; the parentheses should contain a relation from
4585 the list below followed by a version number, in the format
4586 described in <ref id="f-Version">.
4590 The relations allowed are <tt><<</tt>, <tt><=</tt>,
4591 <tt>=</tt>, <tt>>=</tt> and <tt>>></tt> for
4592 strictly earlier, earlier or equal, exactly equal, later or
4593 equal and strictly later, respectively. The deprecated
4594 forms <tt><</tt> and <tt>></tt> were used to mean
4595 earlier/later or equal, rather than strictly earlier/later,
4596 so they should not appear in new packages (though
4597 <prgn>dpkg</prgn> still supports them).
4601 Whitespace may appear at any point in the version
4602 specification subject to the rules in <ref
4603 id="controlsyntax">, and must appear where it's necessary to
4604 disambiguate; it is not otherwise significant. All of the
4605 relationship fields can only be folded in source package control files. For
4606 consistency and in case of future changes to
4607 <prgn>dpkg</prgn> it is recommended that a single space be
4608 used after a version relationship and before a version
4609 number; it is also conventional to put a single space after
4610 each comma, on either side of each vertical bar, and before
4611 each open parenthesis. When opening a continuation line in a relationship field, it
4612 is conventional to do so after a comma and before the space
4613 following that comma.
4617 For example, a list of dependencies might appear as:
4618 <example compact="compact">
4621 Depends: libc6 (>= 2.2.1), exim | mail-transport-agent
4626 Relationships may be restricted to a certain set of
4627 architectures. This is indicated in brackets after each
4628 individual package name and the optional version specification.
4629 The brackets enclose a list of Debian architecture names
4630 in the format described in <ref id="arch-spec">,
4631 separated by whitespace. Exclamation marks may be prepended to
4632 each of the names. (It is not permitted for some names to be
4633 prepended with exclamation marks while others aren't.)
4637 For build relationship fields
4638 (<tt>Build-Depends</tt>, <tt>Build-Depends-Indep</tt>,
4639 <tt>Build-Conflicts</tt> and <tt>Build-Conflicts-Indep</tt>), if
4640 the current Debian host architecture is not in this list and
4641 there are no exclamation marks in the list, or it is in the list
4642 with a prepended exclamation mark, the package name and the
4643 associated version specification are ignored completely for the
4644 purposes of defining the relationships.
4649 <example compact="compact">
4651 Build-Depends-Indep: texinfo
4652 Build-Depends: kernel-headers-2.2.10 [!hurd-i386],
4653 hurd-dev [hurd-i386], gnumach-dev [hurd-i386]
4655 requires <tt>kernel-headers-2.2.10</tt> on all architectures
4656 other than hurd-i386 and requires <tt>hurd-dev</tt> and
4657 <tt>gnumach-dev</tt> only on hurd-i386.
4661 For binary relationship fields, the architecture restriction
4662 syntax is only supported in the source package control
4663 file <file>debian/control</file>. When the corresponding binary
4664 package control file is generated, the relationship will either
4665 be omitted or included without the architecture restriction
4666 based on the architecture of the binary package. This means
4667 that architecture restrictions must not be used in binary
4668 relationship fields for architecture-independent packages
4669 (<tt>Architecture: all</tt>).
4674 <example compact="compact">
4675 Depends: foo [i386], bar [amd64]
4677 becomes <tt>Depends: foo</tt> when the package is built on
4678 the <tt>i386</tt> architecture, <tt>Depends: bar</tt> when the
4679 package is built on the <tt>amd64</tt> architecture, and omitted
4680 entirely in binary packages built on all other architectures.
4684 If the architecture-restricted dependency is part of a set of
4685 alternatives using <tt>|</tt>, that alternative is ignored
4686 completely on architectures that do not match the restriction.
4688 <example compact="compact">
4689 Build-Depends: foo [!i386] | bar [!amd64]
4691 is equivalent to <tt>bar</tt> on the i386 architecture, to
4692 <tt>foo</tt> on the amd64 architecture, and to <tt>foo |
4693 bar</tt> on all other architectures.
4697 Relationships may also be restricted to a certain set of
4698 architectures using architecture wildcards in the format
4699 described in <ref id="arch-wildcard-spec">. The syntax for
4700 declaring such restrictions is the same as declaring
4701 restrictions using a certain set of architectures without
4702 architecture wildcards. For example:
4703 <example compact="compact">
4704 Build-Depends: foo [linux-any], bar [any-i386], baz [!linux-any]
4706 is equivalent to <tt>foo</tt> on architectures using the Linux
4707 kernel and any cpu, <tt>bar</tt> on architectures using any
4708 kernel and an i386 cpu, and <tt>baz</tt> on any architecture
4709 using a kernel other than Linux.
4713 Note that the binary package relationship fields such as
4714 <tt>Depends</tt> appear in one of the binary package
4715 sections of the control file, whereas the build-time
4716 relationships such as <tt>Build-Depends</tt> appear in the
4717 source package section of the control file (which is the
4722 <sect id="binarydeps">
4723 <heading>Binary Dependencies - <tt>Depends</tt>,
4724 <tt>Recommends</tt>, <tt>Suggests</tt>, <tt>Enhances</tt>,
4725 <tt>Pre-Depends</tt>
4729 Packages can declare in their control file that they have
4730 certain relationships to other packages - for example, that
4731 they may not be installed at the same time as certain other
4732 packages, and/or that they depend on the presence of others.
4736 This is done using the <tt>Depends</tt>, <tt>Pre-Depends</tt>,
4737 <tt>Recommends</tt>, <tt>Suggests</tt>, <tt>Enhances</tt>,
4738 <tt>Breaks</tt> and <tt>Conflicts</tt> control fields.
4739 <tt>Breaks</tt> is described in <ref id="breaks">, and
4740 <tt>Conflicts</tt> is described in <ref id="conflicts">. The
4741 rest are described below.
4745 These seven fields are used to declare a dependency
4746 relationship by one package on another. Except for
4747 <tt>Enhances</tt> and <tt>Breaks</tt>, they appear in the
4748 depending (binary) package's control file.
4749 (<tt>Enhances</tt> appears in the recommending package's
4750 control file, and <tt>Breaks</tt> appears in the version of
4751 depended-on package which causes the named package to
4756 A <tt>Depends</tt> field takes effect <em>only</em> when a
4757 package is to be configured. It does not prevent a package
4758 being on the system in an unconfigured state while its
4759 dependencies are unsatisfied, and it is possible to replace
4760 a package whose dependencies are satisfied and which is
4761 properly installed with a different version whose
4762 dependencies are not and cannot be satisfied; when this is
4763 done the depending package will be left unconfigured (since
4764 attempts to configure it will give errors) and will not
4765 function properly. If it is necessary, a
4766 <tt>Pre-Depends</tt> field can be used, which has a partial
4767 effect even when a package is being unpacked, as explained
4768 in detail below. (The other three dependency fields,
4769 <tt>Recommends</tt>, <tt>Suggests</tt> and
4770 <tt>Enhances</tt>, are only used by the various front-ends
4771 to <prgn>dpkg</prgn> such as <prgn>apt-get</prgn>,
4772 <prgn>aptitude</prgn>, and <prgn>dselect</prgn>.)
4776 Since <tt>Depends</tt> only places requirements on the order in
4777 which packages are configured, packages in an installation run
4778 are usually all unpacked first and all configured later.
4780 This approach makes dependency resolution easier. If two
4781 packages A and B are being upgraded, the installed package A
4782 depends on exactly the installed package B, and the new
4783 package A depends on exactly the new package B (a common
4784 situation when upgrading shared libraries and their
4785 corresponding development packages), satisfying the
4786 dependencies at every stage of the upgrade would be
4787 impossible. This relaxed restriction means that both new
4788 packages can be unpacked together and then configured in their
4794 If there is a circular dependency among packages being installed
4795 or removed, installation or removal order honoring the
4796 dependency order is impossible, requiring the dependency loop be
4797 broken at some point and the dependency requirements violated
4798 for at least one package. Packages involved in circular
4799 dependencies may not be able to rely on their dependencies being
4800 configured before they themselves are configured, depending on
4801 which side of the break of the circular dependency loop they
4802 happen to be on. If one of the packages in the loop has
4803 no <prgn>postinst</prgn> script, then the cycle will be broken
4804 at that package; this ensures that all <prgn>postinst</prgn>
4805 scripts are run with their dependencies properly configured if
4806 this is possible. Otherwise the breaking point is arbitrary.
4807 Packages should therefore avoid circular dependencies where
4808 possible, particularly if they have <prgn>postinst</prgn>
4813 The meaning of the five dependency fields is as follows:
4815 <tag><tt>Depends</tt></tag>
4818 This declares an absolute dependency. A package will
4819 not be configured unless all of the packages listed in
4820 its <tt>Depends</tt> field have been correctly
4821 configured (unless there is a circular dependency as
4826 The <tt>Depends</tt> field should be used if the
4827 depended-on package is required for the depending
4828 package to provide a significant amount of
4833 The <tt>Depends</tt> field should also be used if the
4834 <prgn>postinst</prgn> or <prgn>prerm</prgn> scripts
4835 require the depended-on package to be unpacked or
4836 configured in order to run. In the case of <tt>postinst
4837 configure</tt>, the depended-on packages will be unpacked
4838 and configured first. (If both packages are involved in a
4839 dependency loop, this might not work as expected; see the
4840 explanation a few paragraphs back.) In the case
4841 of <prgn>prerm</prgn> or other <prgn>postinst</prgn>
4842 actions, the package dependencies will normally be at
4843 least unpacked, but they may be only "Half-Installed" if a
4844 previous upgrade of the dependency failed.
4848 Finally, the <tt>Depends</tt> field should be used if the
4849 depended-on package is needed by the <prgn>postrm</prgn>
4850 script to fully clean up after the package removal. There
4851 is no guarantee that package dependencies will be
4852 available when <prgn>postrm</prgn> is run, but the
4853 depended-on package is more likely to be available if the
4854 package declares a dependency (particularly in the case
4855 of <tt>postrm remove</tt>). The <prgn>postrm</prgn>
4856 script must gracefully skip actions that require a
4857 dependency if that dependency isn't available.
4861 <tag><tt>Recommends</tt></tag>
4864 This declares a strong, but not absolute, dependency.
4868 The <tt>Recommends</tt> field should list packages
4869 that would be found together with this one in all but
4870 unusual installations.
4874 <tag><tt>Suggests</tt></tag>
4876 This is used to declare that one package may be more
4877 useful with one or more others. Using this field
4878 tells the packaging system and the user that the
4879 listed packages are related to this one and can
4880 perhaps enhance its usefulness, but that installing
4881 this one without them is perfectly reasonable.
4884 <tag><tt>Enhances</tt></tag>
4886 This field is similar to Suggests but works in the
4887 opposite direction. It is used to declare that a
4888 package can enhance the functionality of another
4892 <tag><tt>Pre-Depends</tt></tag>
4895 This field is like <tt>Depends</tt>, except that it
4896 also forces <prgn>dpkg</prgn> to complete installation
4897 of the packages named before even starting the
4898 installation of the package which declares the
4899 pre-dependency, as follows:
4903 When a package declaring a pre-dependency is about to
4904 be <em>unpacked</em> the pre-dependency can be
4905 satisfied if the depended-on package is either fully
4906 configured, <em>or even if</em> the depended-on
4907 package(s) are only unpacked or in the "Half-Configured"
4908 state, provided that they have been configured
4909 correctly at some point in the past (and not removed
4910 or partially removed since). In this case, both the
4911 previously-configured and currently unpacked or
4912 "Half-Configured" versions must satisfy any version
4913 clause in the <tt>Pre-Depends</tt> field.
4917 When the package declaring a pre-dependency is about to
4918 be <em>configured</em>, the pre-dependency will be treated
4919 as a normal <tt>Depends</tt>. It will be considered
4920 satisfied only if the depended-on package has been
4921 correctly configured. However, unlike
4922 with <tt>Depends</tt>, <tt>Pre-Depends</tt> does not
4923 permit circular dependencies to be broken. If a circular
4924 dependency is encountered while attempting to honor
4925 <tt>Pre-Depends</tt>, the installation will be aborted.
4929 <tt>Pre-Depends</tt> are also required if the
4930 <prgn>preinst</prgn> script depends on the named package.
4931 It is best to avoid this situation if possible.
4935 <tt>Pre-Depends</tt> should be used sparingly,
4936 preferably only by packages whose premature upgrade or
4937 installation would hamper the ability of the system to
4938 continue with any upgrade that might be in progress.
4942 You should not specify a <tt>Pre-Depends</tt> entry for a
4943 package before this has been discussed on the
4944 <tt>debian-devel</tt> mailing list and a consensus about
4945 doing that has been reached. See <ref id="dependencies">.
4952 When selecting which level of dependency to use you should
4953 consider how important the depended-on package is to the
4954 functionality of the one declaring the dependency. Some
4955 packages are composed of components of varying degrees of
4956 importance. Such a package should list using
4957 <tt>Depends</tt> the package(s) which are required by the
4958 more important components. The other components'
4959 requirements may be mentioned as Suggestions or
4960 Recommendations, as appropriate to the components' relative
4966 <heading>Packages which break other packages - <tt>Breaks</tt></heading>
4969 When one binary package declares that it breaks another,
4970 <prgn>dpkg</prgn> will refuse to allow the package which
4971 declares <tt>Breaks</tt> to be unpacked unless the broken
4972 package is deconfigured first, and it will refuse to
4973 allow the broken package to be reconfigured.
4977 A package will not be regarded as causing breakage merely
4978 because its configuration files are still installed; it must
4979 be at least "Half-Installed".
4983 A special exception is made for packages which declare that
4984 they break their own package name or a virtual package which
4985 they provide (see below): this does not count as a real
4990 Normally a <tt>Breaks</tt> entry will have an "earlier than"
4991 version clause; such a <tt>Breaks</tt> is introduced in the
4992 version of an (implicit or explicit) dependency which violates
4993 an assumption or reveals a bug in earlier versions of the broken
4994 package, or which takes over a file from earlier versions of the
4995 package named in <tt>Breaks</tt>. This use of <tt>Breaks</tt>
4996 will inform higher-level package management tools that the
4997 broken package must be upgraded before the new one.
5001 If the breaking package also overwrites some files from the
5002 older package, it should use <tt>Replaces</tt> to ensure this
5003 goes smoothly. See <ref id="replaces"> for a full discussion
5004 of taking over files from other packages, including how to
5005 use <tt>Breaks</tt> in those cases.
5009 Many of the cases where <tt>Breaks</tt> should be used were
5010 previously handled with <tt>Conflicts</tt>
5011 because <tt>Breaks</tt> did not yet exist.
5012 Many <tt>Conflicts</tt> fields should now be <tt>Breaks</tt>.
5013 See <ref id="conflicts"> for more information about the
5018 <sect id="conflicts">
5019 <heading>Conflicting binary packages - <tt>Conflicts</tt></heading>
5022 When one binary package declares a conflict with another using
5023 a <tt>Conflicts</tt> field, <prgn>dpkg</prgn> will refuse to
5024 allow them to be unpacked on the system at the same time. This
5025 is a stronger restriction than <tt>Breaks</tt>, which prevents
5026 the broken package from being configured while the breaking
5027 package is in the "Unpacked" state but allows both packages to
5028 be unpacked at the same time.
5032 If one package is to be unpacked, the other must be removed
5033 first. If the package being unpacked is marked as replacing
5034 (see <ref id="replaces">, but note that <tt>Breaks</tt> should
5035 normally be used in this case) the one on the system, or the one
5036 on the system is marked as deselected, or both packages are
5037 marked <tt>Essential</tt>, then <prgn>dpkg</prgn> will
5038 automatically remove the package which is causing the conflict.
5039 Otherwise, it will halt the installation of the new package with
5040 an error. This mechanism is specifically designed to produce an
5041 error when the installed package is <tt>Essential</tt>, but the
5046 A package will not cause a conflict merely because its
5047 configuration files are still installed; it must be at least
5052 A special exception is made for packages which declare a
5053 conflict with their own package name, or with a virtual
5054 package which they provide (see below): this does not
5055 prevent their installation, and allows a package to conflict
5056 with others providing a replacement for it. You use this
5057 feature when you want the package in question to be the only
5058 package providing some feature.
5062 Normally, <tt>Breaks</tt> should be used instead
5063 of <tt>Conflicts</tt> since <tt>Conflicts</tt> imposes a
5064 stronger restriction on the ordering of package installation or
5065 upgrade and can make it more difficult for the package manager
5066 to find a correct solution to an upgrade or installation
5067 problem. <tt>Breaks</tt> should be used
5069 <item>when moving a file from one package to another (see
5070 <ref id="replaces">),</item>
5071 <item>when splitting a package (a special case of the previous
5073 <item>when the breaking package exposes a bug in or interacts
5074 badly with particular versions of the broken
5077 <tt>Conflicts</tt> should be used
5079 <item>when two packages provide the same file and will
5080 continue to do so,</item>
5081 <item>in conjunction with <tt>Provides</tt> when only one
5082 package providing a given virtual facility may be unpacked
5083 at a time (see <ref id="virtual">),</item>
5084 <item>in other cases where one must prevent simultaneous
5085 installation of two packages for reasons that are ongoing
5086 (not fixed in a later version of one of the packages) or
5087 that must prevent both packages from being unpacked at the
5088 same time, not just configured.</item>
5090 Be aware that adding <tt>Conflicts</tt> is normally not the best
5091 solution when two packages provide the same files. Depending on
5092 the reason for that conflict, using alternatives or renaming the
5093 files is often a better approach. See, for
5094 example, <ref id="binaries">.
5098 Neither <tt>Breaks</tt> nor <tt>Conflicts</tt> should be used
5099 unless two packages cannot be installed at the same time or
5100 installing them both causes one of them to be broken or
5101 unusable. Having similar functionality or performing the same
5102 tasks as another package is not sufficient reason to
5103 declare <tt>Breaks</tt> or <tt>Conflicts</tt> with that package.
5107 A <tt>Conflicts</tt> entry may have an "earlier than" version
5108 clause if the reason for the conflict is corrected in a later
5109 version of one of the packages. However, normally the presence
5110 of an "earlier than" version clause is a sign
5111 that <tt>Breaks</tt> should have been used instead. An "earlier
5112 than" version clause in <tt>Conflicts</tt>
5113 prevents <prgn>dpkg</prgn> from upgrading or installing the
5114 package which declares such a conflict until the upgrade or
5115 removal of the conflicted-with package has been completed, which
5116 is a strong restriction.
5120 <sect id="virtual"><heading>Virtual packages - <tt>Provides</tt>
5124 As well as the names of actual ("concrete") packages, the
5125 package relationship fields <tt>Depends</tt>,
5126 <tt>Recommends</tt>, <tt>Suggests</tt>, <tt>Enhances</tt>,
5127 <tt>Pre-Depends</tt>, <tt>Breaks</tt>, <tt>Conflicts</tt>,
5128 <tt>Build-Depends</tt>, <tt>Build-Depends-Indep</tt>,
5129 <tt>Build-Conflicts</tt> and <tt>Build-Conflicts-Indep</tt>
5130 may mention "virtual packages".
5134 A <em>virtual package</em> is one which appears in the
5135 <tt>Provides</tt> control field of another package. The effect
5136 is as if the package(s) which provide a particular virtual
5137 package name had been listed by name everywhere the virtual
5138 package name appears. (See also <ref id="virtual_pkg">)
5142 If there are both concrete and virtual packages of the same
5143 name, then the dependency may be satisfied (or the conflict
5144 caused) by either the concrete package with the name in
5145 question or any other concrete package which provides the
5146 virtual package with the name in question. This is so that,
5147 for example, supposing we have
5148 <example compact="compact">
5151 </example> and someone else releases an enhanced version of
5152 the <tt>bar</tt> package they can say:
5153 <example compact="compact">
5157 and the <tt>bar-plus</tt> package will now also satisfy the
5158 dependency for the <tt>foo</tt> package.
5162 If a relationship field has a version number attached, only real
5163 packages will be considered to see whether the relationship is
5164 satisfied (or the prohibition violated, for a conflict or
5165 breakage). In other words, if a version number is specified,
5166 this is a request to ignore all <tt>Provides</tt> for that
5167 package name and consider only real packages. The package
5168 manager will assume that a package providing that virtual
5169 package is not of the "right" version. A <tt>Provides</tt>
5170 field may not contain version numbers, and the version number of
5171 the concrete package which provides a particular virtual package
5172 will not be considered when considering a dependency on or
5173 conflict with the virtual package name.<footnote>
5174 It is possible that a future release of <prgn>dpkg</prgn> may
5175 add the ability to specify a version number for each virtual
5176 package it provides. This feature is not yet present,
5177 however, and is expected to be used only infrequently.
5182 To specify which of a set of real packages should be the default
5183 to satisfy a particular dependency on a virtual package, list
5184 the real package as an alternative before the virtual one.
5188 If the virtual package represents a facility that can only be
5189 provided by one real package at a time, such as
5190 the <package>mail-transport-agent</package> virtual package that
5191 requires installation of a binary that would conflict with all
5192 other providers of that virtual package (see
5193 <ref id="mail-transport-agents">), all packages providing that
5194 virtual package should also declare a conflict with it
5195 using <tt>Conflicts</tt>. This will ensure that at most one
5196 provider of that virtual package is unpacked or installed at a
5201 <sect id="replaces"><heading>Overwriting files and replacing
5202 packages - <tt>Replaces</tt></heading>
5205 Packages can declare in their control file that they should
5206 overwrite files in certain other packages, or completely replace
5207 other packages. The <tt>Replaces</tt> control field has these
5208 two distinct purposes.
5211 <sect1><heading>Overwriting files in other packages</heading>
5214 It is usually an error for a package to contain files which
5215 are on the system in another package. However, if the
5216 overwriting package declares that it <tt>Replaces</tt> the one
5217 containing the file being overwritten, then <prgn>dpkg</prgn>
5218 will replace the file from the old package with that from the
5219 new. The file will no longer be listed as "owned" by the old
5220 package and will be taken over by the new package.
5221 Normally, <tt>Breaks</tt> should be used in conjunction
5222 with <tt>Replaces</tt>.<footnote>
5223 To see why <tt>Breaks</tt> is normally needed in addition
5224 to <tt>Replaces</tt>, consider the case of a file in the
5225 package <package>foo</package> being taken over by the
5226 package <package>foo-data</package>.
5227 <tt>Replaces</tt> will allow <package>foo-data</package> to
5228 be installed and take over that file. However,
5229 without <tt>Breaks</tt>, nothing
5230 requires <package>foo</package> to be upgraded to a newer
5231 version that knows it does not include that file and instead
5232 depends on <package>foo-data</package>. Nothing would
5233 prevent the new <package>foo-data</package> package from
5234 being installed and then removed, removing the file that it
5235 took over from <package>foo</package>. After that
5236 operation, the package manager would think the system was in
5237 a consistent state, but the <package>foo</package> package
5238 would be missing one of its files.
5243 For example, if a package <package>foo</package> is split
5244 into <package>foo</package> and <package>foo-data</package>
5245 starting at version 1.2-3, <package>foo-data</package> would
5247 <example compact="compact">
5248 Replaces: foo (<< 1.2-3)
5249 Breaks: foo (<< 1.2-3)
5251 in its control file. The new version of the
5252 package <package>foo</package> would normally have the field
5253 <example compact="compact">
5254 Depends: foo-data (>= 1.2-3)
5256 (or possibly <tt>Recommends</tt> or even <tt>Suggests</tt> if
5257 the files moved into <package>foo-data</package> are not
5258 required for normal operation).
5262 If a package is completely replaced in this way, so that
5263 <prgn>dpkg</prgn> does not know of any files it still
5264 contains, it is considered to have "disappeared". It will
5265 be marked as not wanted on the system (selected for
5266 removal) and not installed. Any <tt>conffile</tt>s
5267 details noted for the package will be ignored, as they
5268 will have been taken over by the overwriting package. The
5269 package's <prgn>postrm</prgn> script will be run with a
5270 special argument to allow the package to do any final
5271 cleanup required. See <ref id="mscriptsinstact">.
5273 Replaces is a one way relationship. You have to install
5274 the replacing package after the replaced package.
5279 For this usage of <tt>Replaces</tt>, virtual packages (see
5280 <ref id="virtual">) are not considered when looking at a
5281 <tt>Replaces</tt> field. The packages declared as being
5282 replaced must be mentioned by their real names.
5286 This usage of <tt>Replaces</tt> only takes effect when both
5287 packages are at least partially on the system at once. It is
5288 not relevant if the packages conflict unless the conflict has
5293 <sect1><heading>Replacing whole packages, forcing their
5297 Second, <tt>Replaces</tt> allows the packaging system to
5298 resolve which package should be removed when there is a
5299 conflict (see <ref id="conflicts">). This usage only takes
5300 effect when the two packages <em>do</em> conflict, so that the
5301 two usages of this field do not interfere with each other.
5305 In this situation, the package declared as being replaced
5306 can be a virtual package, so for example, all mail
5307 transport agents (MTAs) would have the following fields in
5308 their control files:
5309 <example compact="compact">
5310 Provides: mail-transport-agent
5311 Conflicts: mail-transport-agent
5312 Replaces: mail-transport-agent
5314 ensuring that only one MTA can be unpacked at any one
5315 time. See <ref id="virtual"> for more information about this
5320 <sect id="sourcebinarydeps">
5321 <heading>Relationships between source and binary packages -
5322 <tt>Build-Depends</tt>, <tt>Build-Depends-Indep</tt>,
5323 <tt>Build-Conflicts</tt>, <tt>Build-Conflicts-Indep</tt>
5327 Source packages that require certain binary packages to be
5328 installed or absent at the time of building the package
5329 can declare relationships to those binary packages.
5333 This is done using the <tt>Build-Depends</tt>,
5334 <tt>Build-Depends-Indep</tt>, <tt>Build-Conflicts</tt> and
5335 <tt>Build-Conflicts-Indep</tt> control fields.
5339 Build-dependencies on "build-essential" binary packages can be
5340 omitted. Please see <ref id="pkg-relations"> for more information.
5344 The dependencies and conflicts they define must be satisfied
5345 (as defined earlier for binary packages) in order to invoke
5346 the targets in <tt>debian/rules</tt>, as follows:<footnote>
5348 There is no Build-Depends-Arch; this role is essentially
5349 met with Build-Depends. Anyone building the
5350 <tt>build-indep</tt> and <tt>binary-indep</tt> targets is
5351 assumed to be building the whole package, and therefore
5352 installation of all build dependencies is required.
5355 The autobuilders use <tt>dpkg-buildpackage -B</tt>, which
5356 calls <tt>build</tt>, not <tt>build-arch</tt> since it does
5357 not yet know how to check for its existence, and
5358 <tt>binary-arch</tt>. The purpose of the original split
5359 between <tt>Build-Depends</tt> and
5360 <tt>Build-Depends-Indep</tt> was so that the autobuilders
5361 wouldn't need to install extra packages needed only for the
5362 binary-indep targets. But without a build-arch/build-indep
5363 split, this didn't work, since most of the work is done in
5364 the build target, not in the binary target.
5368 <tag><tt>clean</tt>, <tt>build-arch</tt>, and
5369 <tt>binary-arch</tt></tag>
5371 Only the <tt>Build-Depends</tt> and <tt>Build-Conflicts</tt>
5372 fields must be satisfied when these targets are invoked.
5374 <tag><tt>build</tt>, <tt>build-indep</tt>, <tt>binary</tt>,
5375 and <tt>binary-indep</tt></tag>
5377 The <tt>Build-Depends</tt>, <tt>Build-Conflicts</tt>,
5378 <tt>Build-Depends-Indep</tt>, and
5379 <tt>Build-Conflicts-Indep</tt> fields must be satisfied when
5380 these targets are invoked.
5388 <chapt id="sharedlibs"><heading>Shared libraries</heading>
5391 Packages containing shared libraries must be constructed with
5392 a little care to make sure that the shared library is always
5393 available. This is especially important for packages whose
5394 shared libraries are vitally important, such as the C library
5395 (currently <tt>libc6</tt>).
5399 This section deals only with public shared libraries: shared
5400 libraries that are placed in directories searched by the dynamic
5401 linker by default or which are intended to be linked against
5402 normally and possibly used by other, independent packages. Shared
5403 libraries that are internal to a particular package or that are
5404 only loaded as dynamic modules are not covered by this section and
5405 are not subject to its requirements.
5409 A shared library is identified by the <tt>SONAME</tt> attribute
5410 stored in its dynamic section. When a binary is linked against a
5411 shared library, the <tt>SONAME</tt> of the shared library is
5412 recorded in the binary's <tt>NEEDED</tt> section so that the
5413 dynamic linker knows that library must be loaded at runtime. The
5414 shared library file's full name (which usually contains additional
5415 version information not needed in the <tt>SONAME</tt>) is
5416 therefore normally not referenced directly. Instead, the shared
5417 library is loaded by its <tt>SONAME</tt>, which exists on the file
5418 system as a symlink pointing to the full name of the shared
5419 library. This symlink must be provided by the
5420 package. <ref id="sharedlibs-runtime"> describes how to do this.
5422 This is a convention of shared library versioning, but not a
5423 requirement. Some libraries use the <tt>SONAME</tt> as the full
5424 library file name instead and therefore do not need a symlink.
5425 Most, however, encode additional information about
5426 backwards-compatible revisions as a minor version number in the
5427 file name. The <tt>SONAME</tt> itself only changes when
5428 binaries linked with the earlier version of the shared library
5429 may no longer work, but the filename may change with each
5430 release of the library. See <ref id="sharedlibs-runtime"> for
5436 When linking a binary or another shared library against a shared
5437 library, the <tt>SONAME</tt> for that shared library is not yet
5438 known. Instead, the shared library is found by looking for a file
5439 matching the library name with <tt>.so</tt> appended. This file
5440 exists on the file system as a symlink pointing to the shared
5445 Shared libraries are normally split into several binary packages.
5446 The <tt>SONAME</tt> symlink is installed by the runtime shared
5447 library package, and the bare <tt>.so</tt> symlink is installed in
5448 the development package since it's only used when linking binaries
5449 or shared libraries. However, there are some exceptions for
5450 unusual shared libraries or for shared libraries that are also
5451 loaded as dynamic modules by other programs.
5455 This section is primarily concerned with how the separation of
5456 shared libraries into multiple packages should be done and how
5457 dependencies on and between shared library binary packages are
5458 managed in Debian. <ref id="libraries"> should be read in
5459 conjunction with this section and contains additional rules for
5460 the files contained in the shared library packages.
5463 <sect id="sharedlibs-runtime">
5464 <heading>Run-time shared libraries</heading>
5467 The run-time shared library must be placed in a package
5468 whose name changes whenever the <tt>SONAME</tt> of the shared
5469 library changes. This allows several versions of the shared
5470 library to be installed at the same time, allowing installation
5471 of the new version of the shared library without immediately
5472 breaking binaries that depend on the old version. Normally, the
5473 run-time shared library and its <tt>SONAME</tt> symlink should
5474 be placed in a package named
5475 <package><var>libraryname</var><var>soversion</var></package>,
5476 where <var>soversion</var> is the version number in
5477 the <tt>SONAME</tt> of the shared library.
5478 See <ref id="shlibs"> for detailed information on how to
5479 determine this version. Alternatively, if it would be confusing
5480 to directly append <var>soversion</var>
5481 to <var>libraryname</var> (if, for example, <var>libraryname</var>
5482 itself ends in a number), you should use
5483 <package><var>libraryname</var>-<var>soversion</var></package>
5488 If you have several shared libraries built from the same source
5489 tree, you may lump them all together into a single shared
5490 library package provided that all of their <tt>SONAME</tt>s will
5491 always change together. Be aware that this is not normally the
5492 case, and if the <tt>SONAME</tt>s do not change together,
5493 upgrading such a merged shared library package will be
5494 unnecessarily difficult because of file conflicts with the old
5495 version of the package. When in doubt, always split shared
5496 library packages so that each binary package installs a single
5501 Every time the shared library ABI changes in a way that may
5502 break binaries linked against older versions of the shared
5503 library, the <tt>SONAME</tt> of the library and the
5504 corresponding name for the binary package containing the runtime
5505 shared library should change. Normally, this means
5506 the <tt>SONAME</tt> should change any time an interface is
5507 removed from the shared library or the signature of an interface
5508 (the number of parameters or the types of parameters that it
5509 takes, for example) is changed. This practice is vital to
5510 allowing clean upgrades from older versions of the package and
5511 clean transitions between the old ABI and new ABI without having
5512 to upgrade every affected package simultaneously.
5516 The <tt>SONAME</tt> and binary package name need not, and indeed
5517 normally should not, change if new interfaces are added but none
5518 are removed or changed, since this will not break binaries
5519 linked against the old shared library. Correct versioning of
5520 dependencies on the newer shared library by binaries that use
5521 the new interfaces is handled via
5522 the <qref id="sharedlibs-shlibdeps"><tt>shlibs</tt>
5523 system</qref> or via symbols files (see
5524 <manref name="deb-symbols" section="5">).
5528 The package should install the shared libraries under
5529 their normal names. For example, the <package>libgdbm3</package>
5530 package should install <file>libgdbm.so.3.0.0</file> as
5531 <file>/usr/lib/libgdbm.so.3.0.0</file>. The files should not be
5532 renamed or re-linked by any <prgn>prerm</prgn> or
5533 <prgn>postrm</prgn> scripts; <prgn>dpkg</prgn> will take care
5534 of renaming things safely without affecting running programs,
5535 and attempts to interfere with this are likely to lead to
5540 Shared libraries should not be installed executable, since
5541 the dynamic linker does not require this and trying to
5542 execute a shared library usually results in a core dump.
5546 The run-time library package should include the symbolic link for
5547 the <tt>SONAME</tt> that <prgn>ldconfig</prgn> would create for
5548 the shared libraries. For example,
5549 the <package>libgdbm3</package> package should include a symbolic
5550 link from <file>/usr/lib/libgdbm.so.3</file> to
5551 <file>libgdbm.so.3.0.0</file>. This is needed so that the dynamic
5552 linker (for example <prgn>ld.so</prgn> or
5553 <prgn>ld-linux.so.*</prgn>) can find the library between the
5554 time that <prgn>dpkg</prgn> installs it and the time that
5555 <prgn>ldconfig</prgn> is run in the <prgn>postinst</prgn>
5557 The package management system requires the library to be
5558 placed before the symbolic link pointing to it in the
5559 <file>.deb</file> file. This is so that when
5560 <prgn>dpkg</prgn> comes to install the symlink
5561 (overwriting the previous symlink pointing at an older
5562 version of the library), the new shared library is already
5563 in place. In the past, this was achieved by creating the
5564 library in the temporary packaging directory before
5565 creating the symlink. Unfortunately, this was not always
5566 effective, since the building of the tar file in the
5567 <file>.deb</file> depended on the behavior of the underlying
5568 file system. Some file systems (such as reiserfs) reorder
5569 the files so that the order of creation is forgotten.
5570 Since version 1.7.0, <prgn>dpkg</prgn>
5571 reorders the files itself as necessary when building a
5572 package. Thus it is no longer important to concern
5573 oneself with the order of file creation.
5577 <sect1 id="ldconfig">
5578 <heading><tt>ldconfig</tt></heading>
5581 Any package installing shared libraries in one of the default
5582 library directories of the dynamic linker (which are currently
5583 <file>/usr/lib</file> and <file>/lib</file>) or a directory that is
5584 listed in <file>/etc/ld.so.conf</file><footnote>
5585 These are currently <file>/usr/local/lib</file> plus
5586 directories under <file>/lib</file> and <file>/usr/lib</file>
5587 matching the multiarch triplet for the system architecture.
5589 must use <prgn>ldconfig</prgn> to update the shared library
5594 The package maintainer scripts must only call
5595 <prgn>ldconfig</prgn> under these circumstances:
5596 <list compact="compact">
5597 <item>When the <prgn>postinst</prgn> script is run with a
5598 first argument of <tt>configure</tt>, the script must call
5599 <prgn>ldconfig</prgn>, and may optionally invoke
5600 <prgn>ldconfig</prgn> at other times.
5602 <item>When the <prgn>postrm</prgn> script is run with a
5603 first argument of <tt>remove</tt>, the script should call
5604 <prgn>ldconfig</prgn>.
5609 During install or upgrade, the preinst is called before
5610 the new files are unpacked, so calling "ldconfig" is
5611 pointless. The preinst of an existing package can also be
5612 called if an upgrade fails. However, this happens during
5613 the critical time when a shared libs may exist on-disk
5614 under a temporary name. Thus, it is dangerous and
5615 forbidden by current policy to call "ldconfig" at this
5620 When a package is installed or upgraded, "postinst
5621 configure" runs after the new files are safely on-disk.
5622 Since it is perfectly safe to invoke ldconfig
5623 unconditionally in a postinst, it is OK for a package to
5624 simply put ldconfig in its postinst without checking the
5625 argument. The postinst can also be called to recover from
5626 a failed upgrade. This happens before any new files are
5627 unpacked, so there is no reason to call "ldconfig" at this
5632 For a package that is being removed, prerm is
5633 called with all the files intact, so calling ldconfig is
5634 useless. The other calls to "prerm" happen in the case of
5635 upgrade at a time when all the files of the old package
5636 are on-disk, so again calling "ldconfig" is pointless.
5640 postrm, on the other hand, is called with the "remove"
5641 argument just after the files are removed, so this is
5642 the proper time to call "ldconfig" to notify the system
5643 of the fact that the shared libraries from the package
5644 are removed. The postrm can be called at several other
5645 times. At the time of "postrm purge", "postrm
5646 abort-install", or "postrm abort-upgrade", calling
5647 "ldconfig" is useless because the shared lib files are
5648 not on-disk. However, when "postrm" is invoked with
5649 arguments "upgrade", "failed-upgrade", or "disappear", a
5650 shared lib may exist on-disk under a temporary filename.
5658 <sect id="sharedlibs-support-files">
5659 <heading>Shared library support files</heading>
5662 If your package contains files whose names do not change with
5663 each change in the library shared object version, you must not
5664 put them in the shared library package. Otherwise, several
5665 versions of the shared library cannot be installed at the same
5666 time without filename clashes, making upgrades and transitions
5667 unnecessarily difficult.
5671 It is recommended that supporting files and run-time support
5672 programs that do not need to be invoked manually by users, but
5673 are nevertheless required for the package to function, be placed
5674 (if they are binary) in a subdirectory of <file>/usr/lib</file>,
5675 preferably under <file>/usr/lib/</file><var>package-name</var>.
5676 If the program or file is architecture independent, the
5677 recommendation is for it to be placed in a subdirectory of
5678 <file>/usr/share</file> instead, preferably under
5679 <file>/usr/share/</file><var>package-name</var>. Following the
5680 <var>package-name</var> naming convention ensures that the file
5681 names change when the shared object version changes.
5685 Run-time support programs that use the shared library but are
5686 not required for the library to function or files used by the
5687 shared library that can be used by any version of the shared
5688 library package should instead be put in a separate package.
5689 This package might typically be named
5690 <package><var>libraryname</var>-tools</package>; note the
5691 absence of the <var>soversion</var> in the package name.
5695 Files and support programs only useful when compiling software
5696 against the library should be included in the development
5697 package for the library.<footnote>
5698 For example, a <file><var>package-name</var>-config</file>
5699 script or <package>pkg-config</package> configuration files.
5704 <sect id="sharedlibs-static">
5705 <heading>Static libraries</heading>
5708 The static library (<file><var>libraryname.a</var></file>)
5709 is usually provided in addition to the shared version.
5710 It is placed into the development package (see below).
5714 In some cases, it is acceptable for a library to be
5715 available in static form only; these cases include:
5717 <item>libraries for languages whose shared library support
5718 is immature or unstable</item>
5719 <item>libraries whose interfaces are in flux or under
5720 development (commonly the case when the library's
5721 major version number is zero, or where the ABI breaks
5722 across patchlevels)</item>
5723 <item>libraries which are explicitly intended to be
5724 available only in static form by their upstream
5729 <sect id="sharedlibs-dev">
5730 <heading>Development files</heading>
5733 If there are development files associated with a shared library,
5734 the source package needs to generate a binary development package
5735 named <package><var>libraryname</var><var>soversion</var>-dev</package>,
5736 or if you prefer only to support one development version at a
5737 time, <package><var>libraryname</var>-dev</package>. Installing
5738 the development package must result in installation of all the
5739 development files necessary for compiling programs against that
5740 shared library.<footnote>
5741 This wording allows the development files to be split into
5742 several packages, such as a separate architecture-independent
5743 <package><var>libraryname</var>-headers</package>, provided that
5744 the development package depends on all the required additional
5750 In case several development versions of a library exist, you may
5751 need to use <prgn>dpkg</prgn>'s Conflicts mechanism (see
5752 <ref id="conflicts">) to ensure that the user only installs one
5753 development version at a time (as different development versions are
5754 likely to have the same header files in them, which would cause a
5755 filename clash if both were unpacked).
5759 The development package should contain a symlink for the associated
5760 shared library without a version number. For example, the
5761 <package>libgdbm-dev</package> package should include a symlink
5762 from <file>/usr/lib/libgdbm.so</file> to
5763 <file>libgdbm.so.3.0.0</file>. This symlink is needed by the linker
5764 (<prgn>ld</prgn>) when compiling packages, as it will only look for
5765 <file>libgdbm.so</file> when compiling dynamically.
5769 If the package provides Ada Library Information
5770 (<file>*.ali</file>) files for use with GNAT, these files must be
5771 installed read-only (mode 0444) so that GNAT will not attempt to
5772 recompile them. This overrides the normal file mode requirements
5773 given in <ref id="permissions-owners">.
5777 <sect id="sharedlibs-intradeps">
5778 <heading>Dependencies between the packages of the same library</heading>
5781 Typically the development version should have an exact
5782 version dependency on the runtime library, to make sure that
5783 compilation and linking happens correctly. The
5784 <tt>${binary:Version}</tt> substitution variable can be
5785 useful for this purpose.
5787 Previously, <tt>${Source-Version}</tt> was used, but its name
5788 was confusing and it has been deprecated since dpkg 1.13.19.
5793 <sect id="sharedlibs-shlibdeps">
5794 <heading>Dependencies between the library and other packages -
5795 the <tt>shlibs</tt> system</heading>
5798 If a package contains a binary or library which links to a
5799 shared library, we must ensure that when the package is
5800 installed on the system, all of the libraries needed are
5801 also installed. This requirement led to the creation of the
5802 <tt>shlibs</tt> system, which is very simple in its design:
5803 any package which <em>provides</em> a shared library also
5804 provides information on the package dependencies required to
5805 ensure the presence of this library, and any package which
5806 <em>uses</em> a shared library uses this information to
5807 determine the dependencies it requires. The files which
5808 contain the mapping from shared libraries to the necessary
5809 dependency information are called <file>shlibs</file> files.
5813 When a package is built which contains any shared libraries, it
5814 must provide a <file>shlibs</file> file for other packages to
5815 use. When a package is built which contains any shared
5816 libraries or compiled binaries, it must run
5817 <qref id="pkg-dpkg-shlibdeps"><prgn>dpkg-shlibdeps</prgn></qref>
5818 on these to determine the libraries used and hence the
5819 dependencies needed by this package.<footnote>
5821 <prgn>dpkg-shlibdeps</prgn> will use a program
5822 like <prgn>objdump</prgn> or <prgn>readelf</prgn> to find
5823 the libraries directly needed by the binaries or shared
5824 libraries in the package.
5828 We say that a binary <tt>foo</tt> <em>directly</em> uses
5829 a library <tt>libbar</tt> if it is explicitly linked
5830 with that library (that is, the library is listed in the ELF
5831 <tt>NEEDED</tt> attribute, caused by adding <tt>-lbar</tt>
5832 to the link line when the binary is created). Other
5833 libraries that are needed by <tt>libbar</tt> are linked
5834 <em>indirectly</em> to <tt>foo</tt>, and the dynamic
5835 linker will load them automatically when it loads
5836 <tt>libbar</tt>. A package should depend on the libraries
5837 it directly uses, but not the libraries it indirectly uses.
5838 The dependencies for those libraries will automatically pull
5839 in the other libraries.
5843 A good example of where this helps is the following. We
5844 could update <tt>libimlib</tt> with a new version that
5845 supports a new graphics format called dgf (but retaining the
5846 same major version number) and depends on <tt>libdgf</tt>.
5847 If we used <prgn>ldd</prgn> to add dependencies for every
5848 library directly or indirectly linked with a binary, every
5849 package that uses <tt>libimlib</tt> would need to be
5850 recompiled so it would also depend on <tt>libdgf</tt> or it
5851 wouldn't run due to missing symbols. Since dependencies are
5852 only added based on ELF <tt>NEEDED</tt> attribute, packages
5853 using <tt>libimlib</tt> can rely on <tt>libimlib</tt> itself
5854 having the dependency on <tt>libdgf</tt> and so they would
5855 not need rebuilding.
5861 In the following sections, we will first describe where the
5862 various <tt>shlibs</tt> files are to be found, then how to
5863 use <prgn>dpkg-shlibdeps</prgn>, and finally the <tt>shlibs</tt>
5864 file format and how to create them if your package contains a
5869 <heading>The <tt>shlibs</tt> files present on the system</heading>
5872 There are several places where <tt>shlibs</tt> files are
5873 found. The following list gives them in the order in which
5875 <qref id="pkg-dpkg-shlibdeps"><prgn>dpkg-shlibdeps</prgn></qref>.
5876 (The first one which gives the required information is used.)
5882 <p><file>debian/shlibs.local</file></p>
5885 This lists overrides for this package. This file should
5886 normally not be used, but may be needed temporarily in
5887 unusual situations to work around bugs in other packages,
5888 or in unusual cases where the normally declared dependency
5889 information in the installed <file>shlibs</file> file for
5890 a library cannot be used. This file overrides information
5891 obtained from any other source.
5896 <p><file>/etc/dpkg/shlibs.override</file></p>
5899 This lists global overrides. This list is normally
5900 empty. It is maintained by the local system
5906 <p><file>DEBIAN/shlibs</file> files in the "build directory"</p>
5909 When packages are being built,
5910 any <file>debian/shlibs</file> files are copied into the
5911 control information file area of the temporary build
5912 directory and given the name <file>shlibs</file>. These
5913 files give details of any shared libraries included in the
5914 same package.<footnote>
5915 An example may help here. Let us say that the source
5916 package <tt>foo</tt> generates two binary
5917 packages, <tt>libfoo2</tt> and <tt>foo-runtime</tt>.
5918 When building the binary packages, the two packages are
5919 created in the directories <file>debian/libfoo2</file>
5920 and <file>debian/foo-runtime</file> respectively.
5921 (<file>debian/tmp</file> could be used instead of one of
5922 these.) Since <tt>libfoo2</tt> provides the
5923 <tt>libfoo</tt> shared library, it will require a
5924 <tt>shlibs</tt> file, which will be installed in
5925 <file>debian/libfoo2/DEBIAN/shlibs</file>, eventually to
5926 become <file>/var/lib/dpkg/info/libfoo2.shlibs</file>.
5927 When <prgn>dpkg-shlibdeps</prgn> is run on the
5928 executable <file>debian/foo-runtime/usr/bin/foo-prog</file>,
5930 the <file>debian/libfoo2/DEBIAN/shlibs</file> file to
5931 determine whether <tt>foo-prog</tt>'s library
5932 dependencies are satisfied by any of the libraries
5933 provided by <tt>libfoo2</tt>. For this reason,
5934 <prgn>dpkg-shlibdeps</prgn> must only be run once all of
5935 the individual binary packages' <tt>shlibs</tt> files
5936 have been installed into the build directory.
5942 <p><file>/var/lib/dpkg/info/*.shlibs</file></p>
5945 These are the <file>shlibs</file> files corresponding to
5946 all of the packages installed on the system, and are
5947 maintained by the relevant package maintainers.
5952 <p><file>/etc/dpkg/shlibs.default</file></p>
5955 This file lists any shared libraries whose packages
5956 have failed to provide correct <file>shlibs</file> files.
5957 It was used when the <file>shlibs</file> setup was first
5958 introduced, but it is now normally empty. It is
5959 maintained by the <tt>dpkg</tt> maintainer.
5967 <heading>How to use <prgn>dpkg-shlibdeps</prgn> and the
5968 <file>shlibs</file> files</heading>
5972 <qref id="pkg-dpkg-shlibdeps"><prgn>dpkg-shlibdeps</prgn></qref>
5973 into your <file>debian/rules</file> file. If your package
5974 contains only compiled binaries and libraries (but no scripts),
5975 you can use a command such as:
5976 <example compact="compact">
5977 dpkg-shlibdeps debian/tmp/usr/bin/* debian/tmp/usr/sbin/* \
5978 debian/tmp/usr/lib/*
5980 Otherwise, you will need to explicitly list the compiled
5981 binaries and libraries.<footnote>
5982 If you are using <tt>debhelper</tt>, the
5983 <prgn>dh_shlibdeps</prgn> program will do this work for you.
5984 It will also correctly handle multi-binary packages.
5989 This command puts the dependency information into the
5990 <file>debian/substvars</file> file, which is then used by
5991 <prgn>dpkg-gencontrol</prgn>. You will need to place a
5992 <tt>${shlibs:Depends}</tt> variable in the <tt>Depends</tt>
5993 field in the control file for this to work.
5997 If you have multiple binary packages, you will need to call
5998 <prgn>dpkg-shlibdeps</prgn> on each one which contains
5999 compiled libraries or binaries. In such a case, you will
6000 need to use the <tt>-T</tt> option to the <tt>dpkg</tt>
6001 utilities to specify a different <file>substvars</file> file.
6005 If you are creating a udeb for use in the Debian Installer,
6006 you will need to specify that <prgn>dpkg-shlibdeps</prgn>
6007 should use the dependency line of type <tt>udeb</tt> by
6008 adding the <tt>-tudeb</tt> option<footnote>
6009 <prgn>dh_shlibdeps</prgn> from the <tt>debhelper</tt> suite
6010 will automatically add this option if it knows it is
6012 </footnote>. If there is no dependency line of
6013 type <tt>udeb</tt> in the <file>shlibs</file>
6014 file, <prgn>dpkg-shlibdeps</prgn> will fall back to the regular
6019 For more details on <prgn>dpkg-shlibdeps</prgn>, please see
6020 <ref id="pkg-dpkg-shlibdeps"> and
6021 <manref name="dpkg-shlibdeps" section="1">.
6026 <heading>The <file>shlibs</file> File Format</heading>
6029 Each <file>shlibs</file> file has the same format. Lines
6030 beginning with <tt>#</tt> are considered to be comments and
6031 are ignored. Each line is of the form:
6032 <example compact="compact">
6033 [<var>type</var>: ]<var>library-name</var> <var>soname-version</var> <var>dependencies ...</var>
6038 We will explain this by reference to the example of the
6039 <tt>zlib1g</tt> package, which (at the time of writing)
6040 installs the shared library <file>/usr/lib/libz.so.1.1.3</file>.
6044 <var>type</var> is an optional element that indicates the type
6045 of package for which the line is valid. The only type currently
6046 in use is <tt>udeb</tt>. The colon and space after the type are
6051 <var>library-name</var> is the name of the shared library,
6052 in this case <tt>libz</tt>. (This must match the name part
6053 of the soname, see below.)
6057 <var>soname-version</var> is the version part of the soname of
6058 the library. The soname is the thing that must exactly match
6059 for the library to be recognized by the dynamic linker, and is
6061 <tt><var>name</var>.so.<var>major-version</var></tt>, in our
6062 example, <tt>libz.so.1</tt>.<footnote>
6063 This can be determined using the command
6064 <example compact="compact">
6065 objdump -p /usr/lib/libz.so.1.1.3 | grep SONAME
6068 The version part is the part which comes after
6069 <tt>.so.</tt>, so in our case, it is <tt>1</tt>. The soname may
6070 instead be of the form
6071 <tt><var>name</var>-<var>major-version</var>.so</tt>, such
6072 as <tt>libdb-4.8.so</tt>, in which case the name would
6073 be <tt>libdb</tt> and the version would be <tt>4.8</tt>.
6077 <var>dependencies</var> has the same syntax as a dependency
6078 field in a binary package control file. It should give
6079 details of which packages are required to satisfy a binary
6080 built against the version of the library contained in the
6081 package. See <ref id="depsyntax"> for details.
6085 In our example, if the first version of the <tt>zlib1g</tt>
6086 package which contained a minor number of at least
6087 <tt>1.3</tt> was <var>1:1.1.3-1</var>, then the
6088 <tt>shlibs</tt> entry for this library could say:
6089 <example compact="compact">
6090 libz 1 zlib1g (>= 1:1.1.3)
6092 The version-specific dependency is to avoid warnings from
6093 the dynamic linker about using older shared libraries with
6098 As zlib1g also provides a udeb containing the shared library,
6099 there would also be a second line:
6100 <example compact="compact">
6101 udeb: libz 1 zlib1g-udeb (>= 1:1.1.3)
6107 <heading>Providing a <file>shlibs</file> file</heading>
6110 If your package provides a shared library, you need to create
6111 a <file>shlibs</file> file following the format described above.
6112 It is usual to call this file <file>debian/shlibs</file> (but if
6113 you have multiple binary packages, you might want to call it
6114 <file>debian/shlibs.<var>package</var></file> instead). Then
6115 let <file>debian/rules</file> install it in the control
6116 information file area:
6117 <example compact="compact">
6118 install -m644 debian/shlibs debian/tmp/DEBIAN
6120 or, in the case of a multi-binary package:
6121 <example compact="compact">
6122 install -m644 debian/shlibs.<var>package</var> debian/<var>package</var>/DEBIAN/shlibs
6124 An alternative way of doing this is to create the
6125 <file>shlibs</file> file in the control information file area
6126 directly from <file>debian/rules</file> without using
6127 a <file>debian/shlibs</file> file at all,<footnote>
6128 This is what <prgn>dh_makeshlibs</prgn> in
6129 the <package>debhelper</package> suite does. If your package
6130 also has a udeb that provides a shared
6131 library, <prgn>dh_makeshlibs</prgn> can automatically generate
6132 the <tt>udeb:</tt> lines if you specify the name of the udeb
6133 with the <tt>--add-udeb</tt> option.
6135 since the <file>debian/shlibs</file> file itself is ignored by
6136 <prgn>dpkg-shlibdeps</prgn>.
6140 As <prgn>dpkg-shlibdeps</prgn> reads the
6141 <file>DEBIAN/shlibs</file> files in all of the binary packages
6142 being built from this source package, all of the
6143 <file>DEBIAN/shlibs</file> files should be installed before
6144 <prgn>dpkg-shlibdeps</prgn> is called on any of the binary
6152 <chapt id="opersys"><heading>The Operating System</heading>
6155 <heading>File system hierarchy</heading>
6159 <heading>File System Structure</heading>
6162 The location of all installed files and directories must
6163 comply with the Filesystem Hierarchy Standard (FHS),
6164 version 2.3, with the exceptions noted below, and except
6165 where doing so would violate other terms of Debian
6166 Policy. The following exceptions to the FHS apply:
6171 The optional rules related to user specific
6172 configuration files for applications are stored in
6173 the user's home directory are relaxed. It is
6174 recommended that such files start with the
6175 '<tt>.</tt>' character (a "dot file"), and if an
6176 application needs to create more than one dot file
6177 then the preferred placement is in a subdirectory
6178 with a name starting with a '.' character, (a "dot
6179 directory"). In this case it is recommended the
6180 configuration files not start with the '.'
6186 The requirement for amd64 to use <file>/lib64</file>
6187 for 64 bit binaries is removed.
6192 The requirement for object files, internal binaries, and
6193 libraries, including <file>libc.so.*</file>, to be located
6194 directly under <file>/lib{,32}</file> and
6195 <file>/usr/lib{,32}</file> is amended, permitting files
6196 to instead be installed to
6197 <file>/lib/<var>triplet</var></file> and
6198 <file>/usr/lib/<var>triplet</var></file>, where
6199 <tt><var>triplet</var></tt> is the value returned by
6200 <tt>dpkg-architecture -qDEB_HOST_MULTIARCH</tt> for the
6201 architecture of the package. Packages may <em>not</em>
6202 install files to any <var>triplet</var> path other
6203 than the one matching the architecture of that package;
6204 for instance, an <tt>Architecture: amd64</tt> package
6205 containing 32-bit x86 libraries may not install these
6206 libraries to <file>/usr/lib/i386-linux-gnu</file>.
6208 This is necessary in order to reserve the directories for
6209 use in cross-installation of library packages from other
6210 architectures, as part of the planned deployment of
6215 Applications may also use a single subdirectory under
6216 <file>/usr/lib/<var>triplet</var></file>.
6219 The execution time linker/loader, ld*, must still be made
6220 available in the existing location under /lib or /lib64
6221 since this is part of the ELF ABI for the architecture.
6226 The requirement that
6227 <file>/usr/local/share/man</file> be "synonymous"
6228 with <file>/usr/local/man</file> is relaxed to a
6233 The requirement that windowmanagers with a single
6234 configuration file call it <file>system.*wmrc</file>
6235 is removed, as is the restriction that the window
6236 manager subdirectory be named identically to the
6237 window manager name itself.
6242 The requirement that boot manager configuration
6243 files live in <file>/etc</file>, or at least are
6244 symlinked there, is relaxed to a recommendation.
6249 The following directories in the root filesystem are
6250 additionally allowed: <file>/sys</file> and
6251 <file>/selinux</file>. <footnote>These directories
6252 are used as mount points to mount virtual filesystems
6253 to get access to kernel information.</footnote>
6258 On GNU/Hurd systems, the following additional
6259 directories are allowed in the root
6260 filesystem: <file>/hurd</file>
6261 and <file>/servers</file>.<footnote>
6262 These directories are used to store translators and as
6263 a set of standard names for mount points,
6272 The version of this document referred here can be
6273 found in the <tt>debian-policy</tt> package or on <url
6274 id="http://www.debian.org/doc/packaging-manuals/fhs/"
6275 name="FHS (Debian copy)"> alongside this manual (or, if
6276 you have the <package>debian-policy</package> installed,
6278 id="file:///usr/share/doc/debian-policy/fhs/" name="FHS
6279 (local copy)">). The
6280 latest version, which may be a more recent version, may
6282 <url id="http://www.pathname.com/fhs/" name="FHS (upstream)">.
6283 Specific questions about following the standard may be
6284 asked on the <tt>debian-devel</tt> mailing list, or
6285 referred to the FHS mailing list (see the
6286 <url id="http://www.pathname.com/fhs/" name="FHS web site"> for
6292 <heading>Site-specific programs</heading>
6295 As mandated by the FHS, packages must not place any
6296 files in <file>/usr/local</file>, either by putting them in
6297 the file system archive to be unpacked by <prgn>dpkg</prgn>
6298 or by manipulating them in their maintainer scripts.
6302 However, the package may create empty directories below
6303 <file>/usr/local</file> so that the system administrator knows
6304 where to place site-specific files. These are not
6305 directories <em>in</em> <file>/usr/local</file>, but are
6306 children of directories in <file>/usr/local</file>. These
6307 directories (<file>/usr/local/*/dir/</file>)
6308 should be removed on package removal if they are
6313 Note that this applies only to
6314 directories <em>below</em> <file>/usr/local</file>,
6315 not <em>in</em> <file>/usr/local</file>. Packages must
6316 not create sub-directories in the
6317 directory <file>/usr/local</file> itself, except those
6318 listed in FHS, section 4.5. However, you may create
6319 directories below them as you wish. You must not remove
6320 any of the directories listed in 4.5, even if you created
6325 Since <file>/usr/local</file> can be mounted read-only from a
6326 remote server, these directories must be created and
6327 removed by the <prgn>postinst</prgn> and <prgn>prerm</prgn>
6328 maintainer scripts and not be included in the
6329 <file>.deb</file> archive. These scripts must not fail if
6330 either of these operations fail.
6334 For example, the <tt>emacsen-common</tt> package could
6335 contain something like
6336 <example compact="compact">
6337 if [ ! -e /usr/local/share/emacs ]
6339 if mkdir /usr/local/share/emacs 2>/dev/null
6341 chown root:staff /usr/local/share/emacs
6342 chmod 2775 /usr/local/share/emacs
6346 in its <prgn>postinst</prgn> script, and
6347 <example compact="compact">
6348 rmdir /usr/local/share/emacs/site-lisp 2>/dev/null || true
6349 rmdir /usr/local/share/emacs 2>/dev/null || true
6351 in the <prgn>prerm</prgn> script. (Note that this form is
6352 used to ensure that if the script is interrupted, the
6353 directory <file>/usr/local/share/emacs</file> will still be
6358 If you do create a directory in <file>/usr/local</file> for
6359 local additions to a package, you should ensure that
6360 settings in <file>/usr/local</file> take precedence over the
6361 equivalents in <file>/usr</file>.
6365 However, because <file>/usr/local</file> and its contents are
6366 for exclusive use of the local administrator, a package
6367 must not rely on the presence or absence of files or
6368 directories in <file>/usr/local</file> for normal operation.
6372 The <file>/usr/local</file> directory itself and all the
6373 subdirectories created by the package should (by default) have
6374 permissions 2775 (group-writable and set-group-id) and be
6375 owned by <tt>root:staff</tt>.
6380 <heading>The system-wide mail directory</heading>
6382 The system-wide mail directory
6383 is <file>/var/mail</file>. This directory is part of the
6384 base system and should not be owned by any particular mail
6385 agents. The use of the old
6386 location <file>/var/spool/mail</file> is deprecated, even
6387 though the spool may still be physically located there.
6393 <heading>Users and groups</heading>
6396 <heading>Introduction</heading>
6398 The Debian system can be configured to use either plain or
6403 Some user ids (UIDs) and group ids (GIDs) are reserved
6404 globally for use by certain packages. Because some
6405 packages need to include files which are owned by these
6406 users or groups, or need the ids compiled into binaries,
6407 these ids must be used on any Debian system only for the
6408 purpose for which they are allocated. This is a serious
6409 restriction, and we should avoid getting in the way of
6410 local administration policies. In particular, many sites
6411 allocate users and/or local system groups starting at 100.
6415 Apart from this we should have dynamically allocated ids,
6416 which should by default be arranged in some sensible
6417 order, but the behavior should be configurable.
6421 Packages other than <tt>base-passwd</tt> must not modify
6422 <file>/etc/passwd</file>, <file>/etc/shadow</file>,
6423 <file>/etc/group</file> or <file>/etc/gshadow</file>.
6428 <heading>UID and GID classes</heading>
6430 The UID and GID numbers are divided into classes as
6436 Globally allocated by the Debian project, the same
6437 on every Debian system. These ids will appear in
6438 the <file>passwd</file> and <file>group</file> files of all
6439 Debian systems, new ids in this range being added
6440 automatically as the <tt>base-passwd</tt> package is
6445 Packages which need a single statically allocated
6446 uid or gid should use one of these; their
6447 maintainers should ask the <tt>base-passwd</tt>
6455 Dynamically allocated system users and groups.
6456 Packages which need a user or group, but can have
6457 this user or group allocated dynamically and
6458 differently on each system, should use <tt>adduser
6459 --system</tt> to create the group and/or user.
6460 <prgn>adduser</prgn> will check for the existence of
6461 the user or group, and if necessary choose an unused
6462 id based on the ranges specified in
6463 <file>adduser.conf</file>.
6467 <tag>1000-59999:</tag>
6470 Dynamically allocated user accounts. By default
6471 <prgn>adduser</prgn> will choose UIDs and GIDs for
6472 user accounts in this range, though
6473 <file>adduser.conf</file> may be used to modify this
6478 <tag>60000-64999:</tag>
6481 Globally allocated by the Debian project, but only
6482 created on demand. The ids are allocated centrally
6483 and statically, but the actual accounts are only
6484 created on users' systems on demand.
6488 These ids are for packages which are obscure or
6489 which require many statically-allocated ids. These
6490 packages should check for and create the accounts in
6491 <file>/etc/passwd</file> or <file>/etc/group</file> (using
6492 <prgn>adduser</prgn> if it has this facility) if
6493 necessary. Packages which are likely to require
6494 further allocations should have a "hole" left after
6495 them in the allocation, to give them room to
6500 <tag>65000-65533:</tag>
6508 User <tt>nobody</tt>. The corresponding gid refers
6509 to the group <tt>nogroup</tt>.
6516 <tt>(uid_t)(-1) == (gid_t)(-1)</tt> <em>must
6517 not</em> be used, because it is the error return
6526 <sect id="sysvinit">
6527 <heading>System run levels and <file>init.d</file> scripts</heading>
6529 <sect1 id="/etc/init.d">
6530 <heading>Introduction</heading>
6533 The <file>/etc/init.d</file> directory contains the scripts
6534 executed by <prgn>init</prgn> at boot time and when the
6535 init state (or "runlevel") is changed (see <manref
6536 name="init" section="8">).
6540 There are at least two different, yet functionally
6541 equivalent, ways of handling these scripts. For the sake
6542 of simplicity, this document describes only the symbolic
6543 link method. However, it must not be assumed by maintainer
6544 scripts that this method is being used, and any automated
6545 manipulation of the various runlevel behaviors by
6546 maintainer scripts must be performed using
6547 <prgn>update-rc.d</prgn> as described below and not by
6548 manually installing or removing symlinks. For information
6549 on the implementation details of the other method,
6550 implemented in the <tt>file-rc</tt> package, please refer
6551 to the documentation of that package.
6555 These scripts are referenced by symbolic links in the
6556 <file>/etc/rc<var>n</var>.d</file> directories. When changing
6557 runlevels, <prgn>init</prgn> looks in the directory
6558 <file>/etc/rc<var>n</var>.d</file> for the scripts it should
6559 execute, where <tt><var>n</var></tt> is the runlevel that
6560 is being changed to, or <tt>S</tt> for the boot-up
6565 The names of the links all have the form
6566 <file>S<var>mm</var><var>script</var></file> or
6567 <file>K<var>mm</var><var>script</var></file> where
6568 <var>mm</var> is a two-digit number and <var>script</var>
6569 is the name of the script (this should be the same as the
6570 name of the actual script in <file>/etc/init.d</file>).
6574 When <prgn>init</prgn> changes runlevel first the targets
6575 of the links whose names start with a <tt>K</tt> are
6576 executed, each with the single argument <tt>stop</tt>,
6577 followed by the scripts prefixed with an <tt>S</tt>, each
6578 with the single argument <tt>start</tt>. (The links are
6579 those in the <file>/etc/rc<var>n</var>.d</file> directory
6580 corresponding to the new runlevel.) The <tt>K</tt> links
6581 are responsible for killing services and the <tt>S</tt>
6582 link for starting services upon entering the runlevel.
6586 For example, if we are changing from runlevel 2 to
6587 runlevel 3, init will first execute all of the <tt>K</tt>
6588 prefixed scripts it finds in <file>/etc/rc3.d</file>, and then
6589 all of the <tt>S</tt> prefixed scripts in that directory.
6590 The links starting with <tt>K</tt> will cause the
6591 referred-to file to be executed with an argument of
6592 <tt>stop</tt>, and the <tt>S</tt> links with an argument
6597 The two-digit number <var>mm</var> is used to determine
6598 the order in which to run the scripts: low-numbered links
6599 have their scripts run first. For example, the
6600 <tt>K20</tt> scripts will be executed before the
6601 <tt>K30</tt> scripts. This is used when a certain service
6602 must be started before another. For example, the name
6603 server <prgn>bind</prgn> might need to be started before
6604 the news server <prgn>inn</prgn> so that <prgn>inn</prgn>
6605 can set up its access lists. In this case, the script
6606 that starts <prgn>bind</prgn> would have a lower number
6607 than the script that starts <prgn>inn</prgn> so that it
6609 <example compact="compact">
6616 The two runlevels 0 (halt) and 6 (reboot) are slightly
6617 different. In these runlevels, the links with an
6618 <tt>S</tt> prefix are still called after those with a
6619 <tt>K</tt> prefix, but they too are called with the single
6620 argument <tt>stop</tt>.
6624 <sect1 id="writing-init">
6625 <heading>Writing the scripts</heading>
6628 Packages that include daemons for system services should
6629 place scripts in <file>/etc/init.d</file> to start or stop
6630 services at boot time or during a change of runlevel.
6631 These scripts should be named
6632 <file>/etc/init.d/<var>package</var></file>, and they should
6633 accept one argument, saying what to do:
6636 <tag><tt>start</tt></tag>
6637 <item>start the service,</item>
6639 <tag><tt>stop</tt></tag>
6640 <item>stop the service,</item>
6642 <tag><tt>restart</tt></tag>
6643 <item>stop and restart the service if it's already running,
6644 otherwise start the service</item>
6646 <tag><tt>reload</tt></tag>
6647 <item><p>cause the configuration of the service to be
6648 reloaded without actually stopping and restarting
6651 <tag><tt>force-reload</tt></tag>
6652 <item>cause the configuration to be reloaded if the
6653 service supports this, otherwise restart the
6657 The <tt>start</tt>, <tt>stop</tt>, <tt>restart</tt>, and
6658 <tt>force-reload</tt> options should be supported by all
6659 scripts in <file>/etc/init.d</file>, the <tt>reload</tt>
6664 The <file>init.d</file> scripts must ensure that they will
6665 behave sensibly (i.e., returning success and not starting
6666 multiple copies of a service) if invoked with <tt>start</tt>
6667 when the service is already running, or with <tt>stop</tt>
6668 when it isn't, and that they don't kill unfortunately-named
6669 user processes. The best way to achieve this is usually to
6670 use <prgn>start-stop-daemon</prgn> with the <tt>--oknodo</tt>
6675 Be careful of using <tt>set -e</tt> in <file>init.d</file>
6676 scripts. Writing correct <file>init.d</file> scripts requires
6677 accepting various error exit statuses when daemons are already
6678 running or already stopped without aborting
6679 the <file>init.d</file> script, and common <file>init.d</file>
6680 function libraries are not safe to call with <tt>set -e</tt>
6682 <tt>/lib/lsb/init-functions</tt>, which assists in writing
6683 LSB-compliant init scripts, may fail if <tt>set -e</tt> is
6684 in effect and echoing status messages to the console fails,
6686 </footnote>. For <tt>init.d</tt> scripts, it's often easier
6687 to not use <tt>set -e</tt> and instead check the result of
6688 each command separately.
6692 If a service reloads its configuration automatically (as
6693 in the case of <prgn>cron</prgn>, for example), the
6694 <tt>reload</tt> option of the <file>init.d</file> script
6695 should behave as if the configuration has been reloaded
6700 The <file>/etc/init.d</file> scripts must be treated as
6701 configuration files, either (if they are present in the
6702 package, that is, in the .deb file) by marking them as
6703 <tt>conffile</tt>s, or, (if they do not exist in the .deb)
6704 by managing them correctly in the maintainer scripts (see
6705 <ref id="config-files">). This is important since we want
6706 to give the local system administrator the chance to adapt
6707 the scripts to the local system, e.g., to disable a
6708 service without de-installing the package, or to specify
6709 some special command line options when starting a service,
6710 while making sure their changes aren't lost during the next
6715 These scripts should not fail obscurely when the
6716 configuration files remain but the package has been
6717 removed, as configuration files remain on the system after
6718 the package has been removed. Only when <prgn>dpkg</prgn>
6719 is executed with the <tt>--purge</tt> option will
6720 configuration files be removed. In particular, as the
6721 <file>/etc/init.d/<var>package</var></file> script itself is
6722 usually a <tt>conffile</tt>, it will remain on the system
6723 if the package is removed but not purged. Therefore, you
6724 should include a <tt>test</tt> statement at the top of the
6726 <example compact="compact">
6727 test -f <var>program-executed-later-in-script</var> || exit 0
6732 Often there are some variables in the <file>init.d</file>
6733 scripts whose values control the behavior of the scripts,
6734 and which a system administrator is likely to want to
6735 change. As the scripts themselves are frequently
6736 <tt>conffile</tt>s, modifying them requires that the
6737 administrator merge in their changes each time the package
6738 is upgraded and the <tt>conffile</tt> changes. To ease
6739 the burden on the system administrator, such configurable
6740 values should not be placed directly in the script.
6741 Instead, they should be placed in a file in
6742 <file>/etc/default</file>, which typically will have the same
6743 base name as the <file>init.d</file> script. This extra file
6744 should be sourced by the script when the script runs. It
6745 must contain only variable settings and comments in SUSv3
6746 <prgn>sh</prgn> format. It may either be a
6747 <tt>conffile</tt> or a configuration file maintained by
6748 the package maintainer scripts. See <ref id="config-files">
6753 To ensure that vital configurable values are always
6754 available, the <file>init.d</file> script should set default
6755 values for each of the shell variables it uses, either
6756 before sourcing the <file>/etc/default/</file> file or
6757 afterwards using something like the <tt>:
6758 ${VAR:=default}</tt> syntax. Also, the <file>init.d</file>
6759 script must behave sensibly and not fail if the
6760 <file>/etc/default</file> file is deleted.
6764 <file>/var/run</file> and <file>/var/lock</file> may be mounted
6765 as temporary filesystems<footnote>
6766 For example, using the <tt>RAMRUN</tt> and <tt>RAMLOCK</tt>
6767 options in <file>/etc/default/rcS</file>.
6768 </footnote>, so the <file>init.d</file> scripts must handle this
6769 correctly. This will typically amount to creating any required
6770 subdirectories dynamically when the <file>init.d</file> script
6771 is run, rather than including them in the package and relying on
6772 <prgn>dpkg</prgn> to create them.
6777 <heading>Interfacing with the initscript system</heading>
6780 Maintainers should use the abstraction layer provided by
6781 the <prgn>update-rc.d</prgn> and <prgn>invoke-rc.d</prgn>
6782 programs to deal with initscripts in their packages'
6783 scripts such as <prgn>postinst</prgn>, <prgn>prerm</prgn>
6784 and <prgn>postrm</prgn>.
6788 Directly managing the /etc/rc?.d links and directly
6789 invoking the <file>/etc/init.d/</file> initscripts should
6790 be done only by packages providing the initscript
6791 subsystem (such as <prgn>sysv-rc</prgn> and
6792 <prgn>file-rc</prgn>).
6796 <heading>Managing the links</heading>
6799 The program <prgn>update-rc.d</prgn> is provided for
6800 package maintainers to arrange for the proper creation and
6801 removal of <file>/etc/rc<var>n</var>.d</file> symbolic links,
6802 or their functional equivalent if another method is being
6803 used. This may be used by maintainers in their packages'
6804 <prgn>postinst</prgn> and <prgn>postrm</prgn> scripts.
6808 You must not include any <file>/etc/rc<var>n</var>.d</file>
6809 symbolic links in the actual archive or manually create or
6810 remove the symbolic links in maintainer scripts; you must
6811 use the <prgn>update-rc.d</prgn> program instead. (The
6812 former will fail if an alternative method of maintaining
6813 runlevel information is being used.) You must not include
6814 the <file>/etc/rc<var>n</var>.d</file> directories themselves
6815 in the archive either. (Only the <tt>sysvinit</tt>
6820 By default <prgn>update-rc.d</prgn> will start services in
6821 each of the multi-user state runlevels (2, 3, 4, and 5)
6822 and stop them in the halt runlevel (0), the single-user
6823 runlevel (1) and the reboot runlevel (6). The system
6824 administrator will have the opportunity to customize
6825 runlevels by simply adding, moving, or removing the
6826 symbolic links in <file>/etc/rc<var>n</var>.d</file> if
6827 symbolic links are being used, or by modifying
6828 <file>/etc/runlevel.conf</file> if the <tt>file-rc</tt> method
6833 To get the default behavior for your package, put in your
6834 <prgn>postinst</prgn> script
6835 <example compact="compact">
6836 update-rc.d <var>package</var> defaults
6838 and in your <prgn>postrm</prgn>
6839 <example compact="compact">
6840 if [ "$1" = purge ]; then
6841 update-rc.d <var>package</var> remove
6843 </example>. Note that if your package changes runlevels
6844 or priority, you may have to remove and recreate the links,
6845 since otherwise the old links may persist. Refer to the
6846 documentation of <prgn>update-rc.d</prgn>.
6850 This will use a default sequence number of 20. If it does
6851 not matter when or in which order the <file>init.d</file>
6852 script is run, use this default. If it does, then you
6853 should talk to the maintainer of the <prgn>sysvinit</prgn>
6854 package or post to <tt>debian-devel</tt>, and they will
6855 help you choose a number.
6859 For more information about using <tt>update-rc.d</tt>,
6860 please consult its man page <manref name="update-rc.d"
6866 <heading>Running initscripts</heading>
6868 The program <prgn>invoke-rc.d</prgn> is provided to make
6869 it easier for package maintainers to properly invoke an
6870 initscript, obeying runlevel and other locally-defined
6871 constraints that might limit a package's right to start,
6872 stop and otherwise manage services. This program may be
6873 used by maintainers in their packages' scripts.
6877 The package maintainer scripts must use
6878 <prgn>invoke-rc.d</prgn> to invoke the
6879 <file>/etc/init.d/*</file> initscripts, instead of
6880 calling them directly.
6884 By default, <prgn>invoke-rc.d</prgn> will pass any
6885 action requests (start, stop, reload, restart...) to the
6886 <file>/etc/init.d</file> script, filtering out requests
6887 to start or restart a service out of its intended
6892 Most packages will simply need to change:
6893 <example compact="compact">/etc/init.d/<package>
6894 <action></example> in their <prgn>postinst</prgn>
6895 and <prgn>prerm</prgn> scripts to:
6896 <example compact="compact">
6897 if which invoke-rc.d >/dev/null 2>&1; then
6898 invoke-rc.d <var>package</var> <action>
6900 /etc/init.d/<var>package</var> <action>
6906 A package should register its initscript services using
6907 <prgn>update-rc.d</prgn> before it tries to invoke them
6908 using <prgn>invoke-rc.d</prgn>. Invocation of
6909 unregistered services may fail.
6913 For more information about using
6914 <prgn>invoke-rc.d</prgn>, please consult its man page
6915 <manref name="invoke-rc.d" section="8">.
6921 <heading>Boot-time initialization</heading>
6924 There used to be another directory, <file>/etc/rc.boot</file>,
6925 which contained scripts which were run once per machine
6926 boot. This has been deprecated in favour of links from
6927 <file>/etc/rcS.d</file> to files in <file>/etc/init.d</file> as
6928 described in <ref id="/etc/init.d">. Packages must not
6929 place files in <file>/etc/rc.boot</file>.
6934 <heading>Example</heading>
6937 An example on which you can base your
6938 <file>/etc/init.d</file> scripts is found in
6939 <file>/etc/init.d/skeleton</file>.
6946 <heading>Console messages from <file>init.d</file> scripts</heading>
6949 This section describes the formats to be used for messages
6950 written to standard output by the <file>/etc/init.d</file>
6951 scripts. The intent is to improve the consistency of
6952 Debian's startup and shutdown look and feel. For this
6953 reason, please look very carefully at the details. We want
6954 the messages to have the same format in terms of wording,
6955 spaces, punctuation and case of letters.
6959 Here is a list of overall rules that should be used for
6960 messages generated by <file>/etc/init.d</file> scripts.
6966 The message should fit in one line (fewer than 80
6967 characters), start with a capital letter and end with
6968 a period (<tt>.</tt>) and line feed (<tt>"\n"</tt>).
6972 If the script is performing some time consuming task in
6973 the background (not merely starting or stopping a
6974 program, for instance), an ellipsis (three dots:
6975 <tt>...</tt>) should be output to the screen, with no
6976 leading or tailing whitespace or line feeds.
6980 The messages should appear as if the computer is telling
6981 the user what it is doing (politely :-), but should not
6982 mention "it" directly. For example, instead of:
6983 <example compact="compact">
6984 I'm starting network daemons: nfsd mountd.
6986 the message should say
6987 <example compact="compact">
6988 Starting network daemons: nfsd mountd.
6995 <tt>init.d</tt> script should use the following standard
6996 message formats for the situations enumerated below.
7002 <p>When daemons are started</p>
7005 If the script starts one or more daemons, the output
7006 should look like this (a single line, no leading
7008 <example compact="compact">
7009 Starting <var>description</var>: <var>daemon-1</var> ... <var>daemon-n</var>.
7011 The <var>description</var> should describe the
7012 subsystem the daemon or set of daemons are part of,
7013 while <var>daemon-1</var> up to <var>daemon-n</var>
7014 denote each daemon's name (typically the file name of
7019 For example, the output of <file>/etc/init.d/lpd</file>
7021 <example compact="compact">
7022 Starting printer spooler: lpd.
7027 This can be achieved by saying
7028 <example compact="compact">
7029 echo -n "Starting printer spooler: lpd"
7030 start-stop-daemon --start --quiet --exec /usr/sbin/lpd
7033 in the script. If there are more than one daemon to
7034 start, the output should look like this:
7035 <example compact="compact">
7036 echo -n "Starting remote file system services:"
7037 echo -n " nfsd"; start-stop-daemon --start --quiet nfsd
7038 echo -n " mountd"; start-stop-daemon --start --quiet mountd
7039 echo -n " ugidd"; start-stop-daemon --start --quiet ugidd
7042 This makes it possible for the user to see what is
7043 happening and when the final daemon has been started.
7044 Care should be taken in the placement of white spaces:
7045 in the example above the system administrators can
7046 easily comment out a line if they don't want to start
7047 a specific daemon, while the displayed message still
7053 <p>When a system parameter is being set</p>
7056 If you have to set up different system parameters
7057 during the system boot, you should use this format:
7058 <example compact="compact">
7059 Setting <var>parameter</var> to "<var>value</var>".
7064 You can use a statement such as the following to get
7066 <example compact="compact">
7067 echo "Setting DNS domainname to \"$domainname\"."
7072 Note that the same symbol (<tt>"</tt>) <!-- " --> is used
7073 for the left and right quotation marks. A grave accent
7074 (<tt>`</tt>) is not a quote character; neither is an
7075 apostrophe (<tt>'</tt>).
7080 <p>When a daemon is stopped or restarted</p>
7083 When you stop or restart a daemon, you should issue a
7084 message identical to the startup message, except that
7085 <tt>Starting</tt> is replaced with <tt>Stopping</tt>
7086 or <tt>Restarting</tt> respectively.
7090 For example, stopping the printer daemon will look like
7092 <example compact="compact">
7093 Stopping printer spooler: lpd.
7099 <p>When something is executed</p>
7102 There are several examples where you have to run a
7103 program at system startup or shutdown to perform a
7104 specific task, for example, setting the system's clock
7105 using <prgn>netdate</prgn> or killing all processes
7106 when the system shuts down. Your message should look
7108 <example compact="compact">
7109 Doing something very useful...done.
7111 You should print the <tt>done.</tt> immediately after
7112 the job has been completed, so that the user is
7113 informed why they have to wait. You can get this
7115 <example compact="compact">
7116 echo -n "Doing something very useful..."
7125 <p>When the configuration is reloaded</p>
7128 When a daemon is forced to reload its configuration
7129 files you should use the following format:
7130 <example compact="compact">
7131 Reloading <var>description</var> configuration...done.
7133 where <var>description</var> is the same as in the
7134 daemon starting message.
7142 <heading>Cron jobs</heading>
7145 Packages must not modify the configuration file
7146 <file>/etc/crontab</file>, and they must not modify the files in
7147 <file>/var/spool/cron/crontabs</file>.</p>
7150 If a package wants to install a job that has to be executed
7151 via cron, it should place a file with the name of the
7152 package in one or more of the following directories:
7153 <example compact="compact">
7159 As these directory names imply, the files within them are
7160 executed on an hourly, daily, weekly, or monthly basis,
7161 respectively. The exact times are listed in
7162 <file>/etc/crontab</file>.</p>
7165 All files installed in any of these directories must be
7166 scripts (e.g., shell scripts or Perl scripts) so that they
7167 can easily be modified by the local system administrator.
7168 In addition, they must be treated as configuration files.
7172 If a certain job has to be executed at some other frequency or
7173 at a specific time, the package should install a file
7174 <file>/etc/cron.d/<var>package</var></file>. This file uses the
7175 same syntax as <file>/etc/crontab</file> and is processed by
7176 <prgn>cron</prgn> automatically. The file must also be
7177 treated as a configuration file. (Note that entries in the
7178 <file>/etc/cron.d</file> directory are not handled by
7179 <prgn>anacron</prgn>. Thus, you should only use this
7180 directory for jobs which may be skipped if the system is not
7183 Unlike <file>crontab</file> files described in the IEEE Std
7184 1003.1-2008 (POSIX.1) available from
7185 <url id="http://www.opengroup.org/onlinepubs/9699919799/"
7186 name="The Open Group">, the files in
7187 <file>/etc/cron.d</file> and the file
7188 <file>/etc/crontab</file> have seven fields; namely:
7190 <item>Minute [0,59]</item>
7191 <item>Hour [0,23]</item>
7192 <item>Day of the month [1,31]</item>
7193 <item>Month of the year [1,12]</item>
7194 <item>Day of the week ([0,6] with 0=Sunday)</item>
7195 <item>Username</item>
7196 <item>Command to be run</item>
7198 Ranges of numbers are allowed. Ranges are two numbers
7199 separated with a hyphen. The specified range is inclusive.
7200 Lists are allowed. A list is a set of numbers (or ranges)
7201 separated by commas. Step values can be used in conjunction
7206 The scripts or <tt>crontab</tt> entries in these directories should
7207 check if all necessary programs are installed before they
7208 try to execute them. Otherwise, problems will arise when a
7209 package was removed but not purged since configuration files
7210 are kept on the system in this situation.
7214 Any <tt>cron</tt> daemon must provide
7215 <file>/usr/bin/crontab</file> and support normal
7216 <tt>crontab</tt> entries as specified in POSIX. The daemon
7217 must also support names for days and months, ranges, and
7218 step values. It has to support <file>/etc/crontab</file>,
7219 and correctly execute the scripts in
7220 <file>/etc/cron.d</file>. The daemon must also correctly
7222 <file>/etc/cron.{hourly,daily,weekly,monthly}</file>.
7227 <heading>Menus</heading>
7230 The Debian <tt>menu</tt> package provides a standard
7231 interface between packages providing applications and
7232 <em>menu programs</em> (either X window managers or
7233 text-based menu programs such as <prgn>pdmenu</prgn>).
7237 All packages that provide applications that need not be
7238 passed any special command line arguments for normal
7239 operation should register a menu entry for those
7240 applications, so that users of the <tt>menu</tt> package
7241 will automatically get menu entries in their window
7242 managers, as well in shells like <tt>pdmenu</tt>.
7246 Menu entries should follow the current menu policy.
7250 The menu policy can be found in the <tt>menu-policy</tt>
7251 files in the <tt>debian-policy</tt> package.
7252 It is also available from the Debian web mirrors at
7253 <tt><url name="/doc/packaging-manuals/menu-policy/"
7254 id="http://www.debian.org/doc/packaging-manuals/menu-policy/"></tt>.
7258 Please also refer to the <em>Debian Menu System</em>
7259 documentation that comes with the <package>menu</package>
7260 package for information about how to register your
7266 <heading>Multimedia handlers</heading>
7269 MIME (Multipurpose Internet Mail Extensions, RFCs 2045-2049)
7270 is a mechanism for encoding files and data streams and
7271 providing meta-information about them, in particular their
7272 type (e.g. audio or video) and format (e.g. PNG, HTML,
7277 Registration of MIME type handlers allows programs like mail
7278 user agents and web browsers to invoke these handlers to
7279 view, edit or display MIME types they don't support directly.
7283 Packages which provide the ability to view/show/play,
7284 compose, edit or print MIME types should register themselves
7285 as such following the current MIME support policy.
7289 The MIME support policy can be found in the <tt>mime-policy</tt>
7290 files in the <tt>debian-policy</tt> package.
7291 It is also available from the Debian web mirrors at
7292 <tt><url name="/doc/packaging-manuals/mime-policy/"
7293 id="http://www.debian.org/doc/packaging-manuals/mime-policy/"></tt>.
7299 <heading>Keyboard configuration</heading>
7302 To achieve a consistent keyboard configuration so that all
7303 applications interpret a keyboard event the same way, all
7304 programs in the Debian distribution must be configured to
7305 comply with the following guidelines.
7309 The following keys must have the specified interpretations:
7312 <tag><tt><--</tt></tag>
7313 <item>delete the character to the left of the cursor</item>
7315 <tag><tt>Delete</tt></tag>
7316 <item>delete the character to the right of the cursor</item>
7318 <tag><tt>Control+H</tt></tag>
7319 <item>emacs: the help prefix</item>
7322 The interpretation of any keyboard events should be
7323 independent of the terminal that is used, be it a virtual
7324 console, an X terminal emulator, an rlogin/telnet session,
7329 The following list explains how the different programs
7330 should be set up to achieve this:
7336 <tt><--</tt> generates <tt>KB_BackSpace</tt> in X.
7340 <tt>Delete</tt> generates <tt>KB_Delete</tt> in X.
7344 X translations are set up to make
7345 <tt>KB_Backspace</tt> generate ASCII DEL, and to make
7346 <tt>KB_Delete</tt> generate <tt>ESC [ 3 ~</tt> (this
7347 is the vt220 escape code for the "delete character"
7348 key). This must be done by loading the X resources
7349 using <prgn>xrdb</prgn> on all local X displays, not
7350 using the application defaults, so that the
7351 translation resources used correspond to the
7352 <prgn>xmodmap</prgn> settings.
7356 The Linux console is configured to make
7357 <tt><--</tt> generate DEL, and <tt>Delete</tt>
7358 generate <tt>ESC [ 3 ~</tt>.
7362 X applications are configured so that <tt><</tt>
7363 deletes left, and <tt>Delete</tt> deletes right. Motif
7364 applications already work like this.
7368 Terminals should have <tt>stty erase ^?</tt> .
7372 The <tt>xterm</tt> terminfo entry should have <tt>ESC
7373 [ 3 ~</tt> for <tt>kdch1</tt>, just as for
7374 <tt>TERM=linux</tt> and <tt>TERM=vt220</tt>.
7378 Emacs is programmed to map <tt>KB_Backspace</tt> or
7379 the <tt>stty erase</tt> character to
7380 <tt>delete-backward-char</tt>, and <tt>KB_Delete</tt>
7381 or <tt>kdch1</tt> to <tt>delete-forward-char</tt>, and
7382 <tt>^H</tt> to <tt>help</tt> as always.
7386 Other applications use the <tt>stty erase</tt>
7387 character and <tt>kdch1</tt> for the two delete keys,
7388 with ASCII DEL being "delete previous character" and
7389 <tt>kdch1</tt> being "delete character under
7397 This will solve the problem except for the following
7404 Some terminals have a <tt><--</tt> key that cannot
7405 be made to produce anything except <tt>^H</tt>. On
7406 these terminals Emacs help will be unavailable on
7407 <tt>^H</tt> (assuming that the <tt>stty erase</tt>
7408 character takes precedence in Emacs, and has been set
7409 correctly). <tt>M-x help</tt> or <tt>F1</tt> (if
7410 available) can be used instead.
7414 Some operating systems use <tt>^H</tt> for <tt>stty
7415 erase</tt>. However, modern telnet versions and all
7416 rlogin versions propagate <tt>stty</tt> settings, and
7417 almost all UNIX versions honour <tt>stty erase</tt>.
7418 Where the <tt>stty</tt> settings are not propagated
7419 correctly, things can be made to work by using
7420 <tt>stty</tt> manually.
7424 Some systems (including previous Debian versions) use
7425 <prgn>xmodmap</prgn> to arrange for both
7426 <tt><--</tt> and <tt>Delete</tt> to generate
7427 <tt>KB_Delete</tt>. We can change the behavior of
7428 their X clients using the same X resources that we use
7429 to do it for our own clients, or configure our clients
7430 using their resources when things are the other way
7431 around. On displays configured like this
7432 <tt>Delete</tt> will not work, but <tt><--</tt>
7437 Some operating systems have different <tt>kdch1</tt>
7438 settings in their <tt>terminfo</tt> database for
7439 <tt>xterm</tt> and others. On these systems the
7440 <tt>Delete</tt> key will not work correctly when you
7441 log in from a system conforming to our policy, but
7442 <tt><--</tt> will.
7449 <heading>Environment variables</heading>
7452 A program must not depend on environment variables to get
7453 reasonable defaults. (That's because these environment
7454 variables would have to be set in a system-wide
7455 configuration file like <file>/etc/profile</file>, which is not
7456 supported by all shells.)
7460 If a program usually depends on environment variables for its
7461 configuration, the program should be changed to fall back to
7462 a reasonable default configuration if these environment
7463 variables are not present. If this cannot be done easily
7464 (e.g., if the source code of a non-free program is not
7465 available), the program must be replaced by a small
7466 "wrapper" shell script which sets the environment variables
7467 if they are not already defined, and calls the original program.
7471 Here is an example of a wrapper script for this purpose:
7473 <example compact="compact">
7475 BAR=${BAR:-/var/lib/fubar}
7477 exec /usr/lib/foo/foo "$@"
7482 Furthermore, as <file>/etc/profile</file> is a configuration
7483 file of the <prgn>base-files</prgn> package, other packages must
7484 not put any environment variables or other commands into that
7489 <sect id="doc-base">
7490 <heading>Registering Documents using doc-base</heading>
7493 The <package>doc-base</package> package implements a
7494 flexible mechanism for handling and presenting
7495 documentation. The recommended practice is for every Debian
7496 package that provides online documentation (other than just
7497 manual pages) to register these documents with
7498 <package>doc-base</package> by installing a
7499 <package>doc-base</package> control file via the
7500 <prgn/install-docs/ script at installation time and
7501 de-register the manuals again when the package is removed.
7504 Please refer to the documentation that comes with the
7505 <package>doc-base</package> package for information and
7514 <heading>Files</heading>
7516 <sect id="binaries">
7517 <heading>Binaries</heading>
7520 Two different packages must not install programs with
7521 different functionality but with the same filenames. (The
7522 case of two programs having the same functionality but
7523 different implementations is handled via "alternatives" or
7524 the "Conflicts" mechanism. See <ref id="maintscripts"> and
7525 <ref id="conflicts"> respectively.) If this case happens,
7526 one of the programs must be renamed. The maintainers should
7527 report this to the <tt>debian-devel</tt> mailing list and
7528 try to find a consensus about which program will have to be
7529 renamed. If a consensus cannot be reached, <em>both</em>
7530 programs must be renamed.
7534 By default, when a package is being built, any binaries
7535 created should include debugging information, as well as
7536 being compiled with optimization. You should also turn on
7537 as many reasonable compilation warnings as possible; this
7538 makes life easier for porters, who can then look at build
7539 logs for possible problems. For the C programming language,
7540 this means the following compilation parameters should be
7542 <example compact="compact">
7544 CFLAGS = -O2 -g -Wall # sane warning options vary between programs
7546 INSTALL = install -s # (or use strip on the files in debian/tmp)
7551 Note that by default all installed binaries should be stripped,
7552 either by using the <tt>-s</tt> flag to
7553 <prgn>install</prgn>, or by calling <prgn>strip</prgn> on
7554 the binaries after they have been copied into
7555 <file>debian/tmp</file> but before the tree is made into a
7560 Although binaries in the build tree should be compiled with
7561 debugging information by default, it can often be difficult to
7562 debug programs if they are also subjected to compiler
7563 optimization. For this reason, it is recommended to support the
7564 standardized environment variable <tt>DEB_BUILD_OPTIONS</tt>
7565 (see <ref id="debianrules-options">). This variable can contain
7566 several flags to change how a package is compiled and built.
7570 It is up to the package maintainer to decide what
7571 compilation options are best for the package. Certain
7572 binaries (such as computationally-intensive programs) will
7573 function better with certain flags (<tt>-O3</tt>, for
7574 example); feel free to use them. Please use good judgment
7575 here. Don't use flags for the sake of it; only use them
7576 if there is good reason to do so. Feel free to override
7577 the upstream author's ideas about which compilation
7578 options are best: they are often inappropriate for our
7584 <sect id="libraries">
7585 <heading>Libraries</heading>
7588 If the package is <strong>architecture: any</strong>, then
7589 the shared library compilation and linking flags must have
7590 <tt>-fPIC</tt>, or the package shall not build on some of
7591 the supported architectures<footnote>
7593 If you are using GCC, <tt>-fPIC</tt> produces code with
7594 relocatable position independent code, which is required for
7595 most architectures to create a shared library, with i386 and
7596 perhaps some others where non position independent code is
7597 permitted in a shared library.
7600 Position independent code may have a performance penalty,
7601 especially on <tt>i386</tt>. However, in most cases the
7602 speed penalty must be measured against the memory wasted on
7603 the few architectures where non position independent code is
7606 </footnote>. Any exception to this rule must be discussed on
7607 the mailing list <em>debian-devel@lists.debian.org</em>, and
7608 a rough consensus obtained. The reasons for not compiling
7609 with <tt>-fPIC</tt> flag must be recorded in the file
7610 <tt>README.Debian</tt>, and care must be taken to either
7611 restrict the architecture or arrange for <tt>-fPIC</tt> to
7612 be used on architectures where it is required.<footnote>
7614 Some of the reasons why this might be required is if the
7615 library contains hand crafted assembly code that is not
7616 relocatable, the speed penalty is excessive for compute
7617 intensive libs, and similar reasons.
7622 As to the static libraries, the common case is not to have
7623 relocatable code, since there is no benefit, unless in specific
7624 cases; therefore the static version must not be compiled
7625 with the <tt>-fPIC</tt> flag. Any exception to this rule
7626 should be discussed on the mailing list
7627 <em>debian-devel@lists.debian.org</em>, and the reasons for
7628 compiling with the <tt>-fPIC</tt> flag must be recorded in
7629 the file <tt>README.Debian</tt>. <footnote>
7631 Some of the reasons for linking static libraries with
7632 the <tt>-fPIC</tt> flag are if, for example, one needs a
7633 Perl API for a library that is under rapid development,
7634 and has an unstable API, so shared libraries are
7635 pointless at this phase of the library's development. In
7636 that case, since Perl needs a library with relocatable
7637 code, it may make sense to create a static library with
7638 relocatable code. Another reason cited is if you are
7639 distilling various libraries into a common shared
7640 library, like <tt>mklibs</tt> does in the Debian
7646 In other words, if both a shared and a static library is
7647 being built, each source unit (<tt>*.c</tt>, for example,
7648 for C files) will need to be compiled twice, for the normal
7653 Libraries should be built with threading support and to be
7654 thread-safe if the library supports this.
7658 Although not enforced by the build tools, shared libraries
7659 must be linked against all libraries that they use symbols from
7660 in the same way that binaries are. This ensures the correct
7661 functioning of the <qref id="sharedlibs-shlibdeps">shlibs</qref>
7662 system and guarantees that all libraries can be safely opened
7663 with <tt>dlopen()</tt>. Packagers may wish to use the gcc
7664 option <tt>-Wl,-z,defs</tt> when building a shared library.
7665 Since this option enforces symbol resolution at build time,
7666 a missing library reference will be caught early as a fatal
7671 All installed shared libraries should be stripped with
7672 <example compact="compact">
7673 strip --strip-unneeded <var>your-lib</var>
7675 (The option <tt>--strip-unneeded</tt> makes
7676 <prgn>strip</prgn> remove only the symbols which aren't
7677 needed for relocation processing.) Shared libraries can
7678 function perfectly well when stripped, since the symbols for
7679 dynamic linking are in a separate part of the ELF object
7681 You might also want to use the options
7682 <tt>--remove-section=.comment</tt> and
7683 <tt>--remove-section=.note</tt> on both shared libraries
7684 and executables, and <tt>--strip-debug</tt> on static
7690 Note that under some circumstances it may be useful to
7691 install a shared library unstripped, for example when
7692 building a separate package to support debugging.
7696 Shared object files (often <file>.so</file> files) that are not
7697 public libraries, that is, they are not meant to be linked
7698 to by third party executables (binaries of other packages),
7699 should be installed in subdirectories of the
7700 <file>/usr/lib</file> directory. Such files are exempt from the
7701 rules that govern ordinary shared libraries, except that
7702 they must not be installed executable and should be
7704 A common example are the so-called "plug-ins",
7705 internal shared objects that are dynamically loaded by
7706 programs using <manref name="dlopen" section="3">.
7711 Packages that use <prgn>libtool</prgn> to create and install
7712 their shared libraries install a file containing additional
7713 metadata (ending in <file>.la</file>) alongside the library.
7714 For public libraries intended for use by other packages, these
7715 files normally should not be included in the Debian package,
7716 since the information they include is not necessary to link with
7717 the shared library on Debian and can add unnecessary additional
7718 dependencies to other programs or libraries.<footnote>
7719 These files store, among other things, all libraries on which
7720 that shared library depends. Unfortunately, if
7721 the <file>.la</file> file is present and contains that
7722 dependency information, using <prgn>libtool</prgn> when
7723 linking against that library will cause the resulting program
7724 or library to be linked against those dependencies as well,
7725 even if this is unnecessary. This can create unneeded
7726 dependencies on shared library packages that would otherwise
7727 be hidden behind the library ABI, and can make library
7728 transitions to new SONAMEs unnecessarily complicated and
7729 difficult to manage.
7731 If the <file>.la</file> file is required for that library (if,
7732 for instance, it's loaded via <tt>libltdl</tt> in a way that
7733 requires that meta-information), the <tt>dependency_libs</tt>
7734 setting in the <file>.la</file> file should normally be set to
7735 the empty string. If the shared library development package has
7736 historically included the <file>.la</file>, it must be retained
7737 in the development package (with <tt>dependency_libs</tt>
7738 emptied) until all libraries that depend on it have removed or
7739 emptied <tt>dependency_libs</tt> in their <file>.la</file>
7740 files to prevent linking with those other libraries
7741 using <prgn>libtool</prgn> from failing.
7745 If the <file>.la</file> must be included, it should be included
7746 in the development (<tt>-dev</tt>) package, unless the library
7747 will be loaded by <prgn>libtool</prgn>'s <tt>libltdl</tt>
7748 library. If it is intended for use with <tt>libltdl</tt>,
7749 the <file>.la</file> files must go in the run-time library
7754 These requirements for handling of <file>.la</file> files do not
7755 apply to loadable modules or libraries not installed in
7756 directories searched by default by the dynamic linker. Packages
7757 installing loadable modules will frequently need to install
7758 the <file>.la</file> files alongside the modules so that they
7759 can be loaded by <tt>libltdl</tt>. <tt>dependency_libs</tt>
7760 does not need to be modified for libraries or modules that are
7761 not installed in directories searched by the dynamic linker by
7762 default and not intended for use by other packages.
7766 You must make sure that you use only released versions of
7767 shared libraries to build your packages; otherwise other
7768 users will not be able to run your binaries
7769 properly. Producing source packages that depend on
7770 unreleased compilers is also usually a bad
7777 <heading>Shared libraries</heading>
7779 This section has moved to <ref id="sharedlibs">.
7785 <heading>Scripts</heading>
7788 All command scripts, including the package maintainer
7789 scripts inside the package and used by <prgn>dpkg</prgn>,
7790 should have a <tt>#!</tt> line naming the shell to be used
7795 In the case of Perl scripts this should be
7796 <tt>#!/usr/bin/perl</tt>.
7800 When scripts are installed into a directory in the system
7801 PATH, the script name should not include an extension such
7802 as <tt>.sh</tt> or <tt>.pl</tt> that denotes the scripting
7803 language currently used to implement it.
7806 Shell scripts (<prgn>sh</prgn> and <prgn>bash</prgn>) other than
7807 <file>init.d</file> scripts should almost certainly start
7808 with <tt>set -e</tt> so that errors are detected.
7809 <file>init.d</file> scripts are something of a special case, due
7810 to how frequently they need to call commands that are allowed to
7811 fail, and it may instead be easier to check the exit status of
7812 commands directly. See <ref id="writing-init"> for more
7813 information about writing <file>init.d</file> scripts.
7816 Every script should use <tt>set -e</tt> or check the exit status
7817 of <em>every</em> command.
7820 Scripts may assume that <file>/bin/sh</file> implements the
7821 SUSv3 Shell Command Language<footnote>
7822 Single UNIX Specification, version 3, which is also IEEE
7823 1003.1-2004 (POSIX), and is available on the World Wide Web
7824 from <url id="http://www.unix.org/version3/online.html"
7825 name="The Open Group"> after free
7826 registration.</footnote>
7827 plus the following additional features not mandated by
7829 These features are in widespread use in the Linux community
7830 and are implemented in all of bash, dash, and ksh, the most
7831 common shells users may wish to use as <file>/bin/sh</file>.
7834 <item><tt>echo -n</tt>, if implemented as a shell built-in,
7835 must not generate a newline.</item>
7836 <item><tt>test</tt>, if implemented as a shell built-in, must
7837 support <tt>-a</tt> and <tt>-o</tt> as binary logical
7839 <item><tt>local</tt> to create a scoped variable must be
7840 supported, including listing multiple variables in a single
7841 local command and assigning a value to a variable at the
7842 same time as localizing it. <tt>local</tt> may or
7843 may not preserve the variable value from an outer scope if
7844 no assignment is present. Uses such as:
7848 # ... use a, b, c, d ...
7851 must be supported and must set the value of <tt>c</tt> to
7854 <item>The XSI extension to <prgn>kill</prgn> allowing <tt>kill
7855 -<var>signal</var></tt>, where <var>signal</var> is either
7856 the name of a signal or one of the numeric signals listed in
7857 the XSI extension (0, 1, 2, 3, 6, 9, 14, and 15), must be
7858 supported if <prgn>kill</prgn> is implemented as a shell
7861 <item>The XSI extension to <prgn>trap</prgn> allowing numeric
7862 signals must be supported. In addition to the signal
7863 numbers listed in the extension, which are the same as for
7864 <prgn>kill</prgn> above, 13 (SIGPIPE) must be allowed.
7867 If a shell script requires non-SUSv3 features from the shell
7868 interpreter other than those listed above, the appropriate shell
7869 must be specified in the first line of the script (e.g.,
7870 <tt>#!/bin/bash</tt>) and the package must depend on the package
7871 providing the shell (unless the shell package is marked
7872 "Essential", as in the case of <prgn>bash</prgn>).
7876 You may wish to restrict your script to SUSv3 features plus the
7877 above set when possible so that it may use <file>/bin/sh</file>
7878 as its interpreter. If your script works with <prgn>dash</prgn>
7879 (originally called <prgn>ash</prgn>), it probably complies with
7880 the above requirements, but if you are in doubt, use
7881 <file>/bin/bash</file>.
7885 Perl scripts should check for errors when making any
7886 system calls, including <tt>open</tt>, <tt>print</tt>,
7887 <tt>close</tt>, <tt>rename</tt> and <tt>system</tt>.
7891 <prgn>csh</prgn> and <prgn>tcsh</prgn> should be avoided as
7892 scripting languages. See <em>Csh Programming Considered
7893 Harmful</em>, one of the <tt>comp.unix.*</tt> FAQs, which
7894 can be found at <url id="http://www.faqs.org/faqs/unix-faq/shell/csh-whynot/">.
7895 If an upstream package comes with <prgn>csh</prgn> scripts
7896 then you must make sure that they start with
7897 <tt>#!/bin/csh</tt> and make your package depend on the
7898 <prgn>c-shell</prgn> virtual package.
7902 Any scripts which create files in world-writeable
7903 directories (e.g., in <file>/tmp</file>) must use a
7904 mechanism which will fail atomically if a file with the same
7905 name already exists.
7909 The Debian base system provides the <prgn>tempfile</prgn>
7910 and <prgn>mktemp</prgn> utilities for use by scripts for
7917 <heading>Symbolic links</heading>
7920 In general, symbolic links within a top-level directory
7921 should be relative, and symbolic links pointing from one
7922 top-level directory into another should be absolute. (A
7923 top-level directory is a sub-directory of the root
7924 directory <file>/</file>.)
7928 In addition, symbolic links should be specified as short as
7929 possible, i.e., link targets like <file>foo/../bar</file> are
7934 Note that when creating a relative link using
7935 <prgn>ln</prgn> it is not necessary for the target of the
7936 link to exist relative to the working directory you're
7937 running <prgn>ln</prgn> from, nor is it necessary to change
7938 directory to the directory where the link is to be made.
7939 Simply include the string that should appear as the target
7940 of the link (this will be a pathname relative to the
7941 directory in which the link resides) as the first argument
7946 For example, in your <prgn>Makefile</prgn> or
7947 <file>debian/rules</file>, you can do things like:
7948 <example compact="compact">
7949 ln -fs gcc $(prefix)/bin/cc
7950 ln -fs gcc debian/tmp/usr/bin/cc
7951 ln -fs ../sbin/sendmail $(prefix)/bin/runq
7952 ln -fs ../sbin/sendmail debian/tmp/usr/bin/runq
7957 A symbolic link pointing to a compressed file should always
7958 have the same file extension as the referenced file. (For
7959 example, if a file <file>foo.gz</file> is referenced by a
7960 symbolic link, the filename of the link has to end with
7961 "<file>.gz</file>" too, as in <file>bar.gz</file>.)
7966 <heading>Device files</heading>
7969 Packages must not include device files or named pipes in the
7974 If a package needs any special device files that are not
7975 included in the base system, it must call
7976 <prgn>MAKEDEV</prgn> in the <prgn>postinst</prgn> script,
7977 after notifying the user<footnote>
7978 This notification could be done via a (low-priority)
7979 debconf message, or an echo (printf) statement.
7984 Packages must not remove any device files in the
7985 <prgn>postrm</prgn> or any other script. This is left to the
7986 system administrator.
7990 Debian uses the serial devices
7991 <file>/dev/ttyS*</file>. Programs using the old
7992 <file>/dev/cu*</file> devices should be changed to use
7993 <file>/dev/ttyS*</file>.
7997 Named pipes needed by the package must be created in
7998 the <prgn>postinst</prgn> script<footnote>
7999 It's better to use <prgn>mkfifo</prgn> rather
8000 than <prgn>mknod</prgn> to create named pipes so that
8001 automated checks for packages incorrectly creating device
8002 files with <prgn>mknod</prgn> won't have false positives.
8003 </footnote> and removed in
8004 the <prgn>prerm</prgn> or <prgn>postrm</prgn> script as
8009 <sect id="config-files">
8010 <heading>Configuration files</heading>
8013 <heading>Definitions</heading>
8017 <tag>configuration file</tag>
8019 A file that affects the operation of a program, or
8020 provides site- or host-specific information, or
8021 otherwise customizes the behavior of a program.
8022 Typically, configuration files are intended to be
8023 modified by the system administrator (if needed or
8024 desired) to conform to local policy or to provide
8025 more useful site-specific behavior.
8028 <tag><tt>conffile</tt></tag>
8030 A file listed in a package's <tt>conffiles</tt>
8031 file, and is treated specially by <prgn>dpkg</prgn>
8032 (see <ref id="configdetails">).
8038 The distinction between these two is important; they are
8039 not interchangeable concepts. Almost all
8040 <tt>conffile</tt>s are configuration files, but many
8041 configuration files are not <tt>conffiles</tt>.
8045 As noted elsewhere, <file>/etc/init.d</file> scripts,
8046 <file>/etc/default</file> files, scripts installed in
8047 <file>/etc/cron.{hourly,daily,weekly,monthly}</file>, and cron
8048 configuration installed in <file>/etc/cron.d</file> must be
8049 treated as configuration files. In general, any script that
8050 embeds configuration information is de-facto a configuration
8051 file and should be treated as such.
8056 <heading>Location</heading>
8059 Any configuration files created or used by your package
8060 must reside in <file>/etc</file>. If there are several,
8061 consider creating a subdirectory of <file>/etc</file>
8062 named after your package.
8066 If your package creates or uses configuration files
8067 outside of <file>/etc</file>, and it is not feasible to modify
8068 the package to use <file>/etc</file> directly, put the files
8069 in <file>/etc</file> and create symbolic links to those files
8070 from the location that the package requires.
8075 <heading>Behavior</heading>
8078 Configuration file handling must conform to the following
8080 <list compact="compact">
8082 local changes must be preserved during a package
8086 configuration files must be preserved when the
8087 package is removed, and only deleted when the
8091 Obsolete configuration files without local changes may be
8092 removed by the package during upgrade.
8096 The easy way to achieve this behavior is to make the
8097 configuration file a <tt>conffile</tt>. This is
8098 appropriate only if it is possible to distribute a default
8099 version that will work for most installations, although
8100 some system administrators may choose to modify it. This
8101 implies that the default version will be part of the
8102 package distribution, and must not be modified by the
8103 maintainer scripts during installation (or at any other
8108 In order to ensure that local changes are preserved
8109 correctly, no package may contain or make hard links to
8110 conffiles.<footnote>
8111 Rationale: There are two problems with hard links.
8112 The first is that some editors break the link while
8113 editing one of the files, so that the two files may
8114 unwittingly become unlinked and different. The second
8115 is that <prgn>dpkg</prgn> might break the hard link
8116 while upgrading <tt>conffile</tt>s.
8121 The other way to do it is via the maintainer scripts. In
8122 this case, the configuration file must not be listed as a
8123 <tt>conffile</tt> and must not be part of the package
8124 distribution. If the existence of a file is required for
8125 the package to be sensibly configured it is the
8126 responsibility of the package maintainer to provide
8127 maintainer scripts which correctly create, update and
8128 maintain the file and remove it on purge. (See <ref
8129 id="maintainerscripts"> for more information.) These
8130 scripts must be idempotent (i.e., must work correctly if
8131 <prgn>dpkg</prgn> needs to re-run them due to errors
8132 during installation or removal), must cope with all the
8133 variety of ways <prgn>dpkg</prgn> can call maintainer
8134 scripts, must not overwrite or otherwise mangle the user's
8135 configuration without asking, must not ask unnecessary
8136 questions (particularly during upgrades), and must
8137 otherwise be good citizens.
8141 The scripts are not required to configure every possible
8142 option for the package, but only those necessary to get
8143 the package running on a given system. Ideally the
8144 sysadmin should not have to do any configuration other
8145 than that done (semi-)automatically by the
8146 <prgn>postinst</prgn> script.
8150 A common practice is to create a script called
8151 <file><var>package</var>-configure</file> and have the
8152 package's <prgn>postinst</prgn> call it if and only if the
8153 configuration file does not already exist. In certain
8154 cases it is useful for there to be an example or template
8155 file which the maintainer scripts use. Such files should
8156 be in <file>/usr/share/<var>package</var></file> or
8157 <file>/usr/lib/<var>package</var></file> (depending on whether
8158 they are architecture-independent or not). There should
8159 be symbolic links to them from
8160 <file>/usr/share/doc/<var>package</var>/examples</file> if
8161 they are examples, and should be perfectly ordinary
8162 <prgn>dpkg</prgn>-handled files (<em>not</em>
8163 configuration files).
8167 These two styles of configuration file handling must
8168 not be mixed, for that way lies madness:
8169 <prgn>dpkg</prgn> will ask about overwriting the file
8170 every time the package is upgraded.
8175 <heading>Sharing configuration files</heading>
8178 Packages which specify the same file as a
8179 <tt>conffile</tt> must be tagged as <em>conflicting</em>
8180 with each other. (This is an instance of the general rule
8181 about not sharing files. Note that neither alternatives
8182 nor diversions are likely to be appropriate in this case;
8183 in particular, <prgn>dpkg</prgn> does not handle diverted
8184 <tt>conffile</tt>s well.)
8188 The maintainer scripts must not alter a <tt>conffile</tt>
8189 of <em>any</em> package, including the one the scripts
8194 If two or more packages use the same configuration file
8195 and it is reasonable for both to be installed at the same
8196 time, one of these packages must be defined as
8197 <em>owner</em> of the configuration file, i.e., it will be
8198 the package which handles that file as a configuration
8199 file. Other packages that use the configuration file must
8200 depend on the owning package if they require the
8201 configuration file to operate. If the other package will
8202 use the configuration file if present, but is capable of
8203 operating without it, no dependency need be declared.
8207 If it is desirable for two or more related packages to
8208 share a configuration file <em>and</em> for all of the
8209 related packages to be able to modify that configuration
8210 file, then the following should be done:
8211 <enumlist compact="compact">
8213 One of the related packages (the "owning" package)
8214 will manage the configuration file with maintainer
8215 scripts as described in the previous section.
8218 The owning package should also provide a program
8219 that the other packages may use to modify the
8223 The related packages must use the provided program
8224 to make any desired modifications to the
8225 configuration file. They should either depend on
8226 the core package to guarantee that the configuration
8227 modifier program is available or accept gracefully
8228 that they cannot modify the configuration file if it
8229 is not. (This is in addition to the fact that the
8230 configuration file may not even be present in the
8237 Sometimes it's appropriate to create a new package which
8238 provides the basic infrastructure for the other packages
8239 and which manages the shared configuration files. (The
8240 <tt>sgml-base</tt> package is a good example.)
8245 <heading>User configuration files ("dotfiles")</heading>
8248 The files in <file>/etc/skel</file> will automatically be
8249 copied into new user accounts by <prgn>adduser</prgn>.
8250 No other program should reference the files in
8251 <file>/etc/skel</file>.
8255 Therefore, if a program needs a dotfile to exist in
8256 advance in <file>$HOME</file> to work sensibly, that dotfile
8257 should be installed in <file>/etc/skel</file> and treated as a
8262 However, programs that require dotfiles in order to
8263 operate sensibly are a bad thing, unless they do create
8264 the dotfiles themselves automatically.
8268 Furthermore, programs should be configured by the Debian
8269 default installation to behave as closely to the upstream
8270 default behavior as possible.
8274 Therefore, if a program in a Debian package needs to be
8275 configured in some way in order to operate sensibly, that
8276 should be done using a site-wide configuration file placed
8277 in <file>/etc</file>. Only if the program doesn't support a
8278 site-wide default configuration and the package maintainer
8279 doesn't have time to add it may a default per-user file be
8280 placed in <file>/etc/skel</file>.
8284 <file>/etc/skel</file> should be as empty as we can make it.
8285 This is particularly true because there is no easy (or
8286 necessarily desirable) mechanism for ensuring that the
8287 appropriate dotfiles are copied into the accounts of
8288 existing users when a package is installed.
8294 <heading>Log files</heading>
8296 Log files should usually be named
8297 <file>/var/log/<var>package</var>.log</file>. If you have many
8298 log files, or need a separate directory for permission
8299 reasons (<file>/var/log</file> is writable only by
8300 <file>root</file>), you should usually create a directory named
8301 <file>/var/log/<var>package</var></file> and place your log
8306 Log files must be rotated occasionally so that they don't grow
8307 indefinitely. The best way to do this is to install a log
8308 rotation configuration file in the
8309 directory <file>/etc/logrotate.d</file>, normally
8310 named <file>/etc/logrotate.d/<var>package</var></file>, and use
8311 the facilities provided by <prgn>logrotate</prgn>.
8314 The traditional approach to log files has been to set up
8315 <em>ad hoc</em> log rotation schemes using simple shell
8316 scripts and cron. While this approach is highly
8317 customizable, it requires quite a lot of sysadmin work.
8318 Even though the original Debian system helped a little
8319 by automatically installing a system which can be used
8320 as a template, this was deemed not enough.
8324 The use of <prgn>logrotate</prgn>, a program developed
8325 by Red Hat, is better, as it centralizes log management.
8326 It has both a configuration file
8327 (<file>/etc/logrotate.conf</file>) and a directory where
8328 packages can drop their individual log rotation
8329 configurations (<file>/etc/logrotate.d</file>).
8332 Here is a good example for a logrotate config
8333 file (for more information see <manref name="logrotate"
8335 <example compact="compact">
8336 /var/log/foo/*.log {
8342 start-stop-daemon -K -p /var/run/foo.pid -s HUP -x /usr/sbin/foo -q
8346 This rotates all files under <file>/var/log/foo</file>, saves 12
8347 compressed generations, and tells the daemon to reopen its log
8348 files after the log rotation. It skips this log rotation
8349 (via <tt>missingok</tt>) if no such log file is present, which
8350 avoids errors if the package is removed but not purged.
8354 Log files should be removed when the package is
8355 purged (but not when it is only removed). This should be
8356 done by the <prgn>postrm</prgn> script when it is called
8357 with the argument <tt>purge</tt> (see <ref
8358 id="removedetails">).
8362 <sect id="permissions-owners">
8363 <heading>Permissions and owners</heading>
8366 The rules in this section are guidelines for general use.
8367 If necessary you may deviate from the details below.
8368 However, if you do so you must make sure that what is done
8369 is secure and you should try to be as consistent as possible
8370 with the rest of the system. You should probably also
8371 discuss it on <prgn>debian-devel</prgn> first.
8375 Files should be owned by <tt>root:root</tt>, and made
8376 writable only by the owner and universally readable (and
8377 executable, if appropriate), that is mode 644 or 755.
8381 Directories should be mode 755 or (for group-writability)
8382 mode 2775. The ownership of the directory should be
8383 consistent with its mode: if a directory is mode 2775, it
8384 should be owned by the group that needs write access to
8387 When a package is upgraded, and the owner or permissions
8388 of a file included in the package has changed, dpkg
8389 arranges for the ownership and permissions to be
8390 correctly set upon installation. However, this does not
8391 extend to directories; the permissions and ownership of
8392 directories already on the system does not change on
8393 install or upgrade of packages. This makes sense, since
8394 otherwise common directories like <tt>/usr</tt> would
8395 always be in flux. To correctly change permissions of a
8396 directory the package owns, explicit action is required,
8397 usually in the <tt>postinst</tt> script. Care must be
8398 taken to handle downgrades as well, in that case.
8404 Control information files should be owned by <tt>root:root</tt>
8405 and either mode 644 (for most files) or mode 755 (for
8406 executables such as <qref id="maintscripts">maintainer
8411 Setuid and setgid executables should be mode 4755 or 2755
8412 respectively, and owned by the appropriate user or group.
8413 They should not be made unreadable (modes like 4711 or
8414 2711 or even 4111); doing so achieves no extra security,
8415 because anyone can find the binary in the freely available
8416 Debian package; it is merely inconvenient. For the same
8417 reason you should not restrict read or execute permissions
8418 on non-set-id executables.
8422 Some setuid programs need to be restricted to particular
8423 sets of users, using file permissions. In this case they
8424 should be owned by the uid to which they are set-id, and by
8425 the group which should be allowed to execute them. They
8426 should have mode 4754; again there is no point in making
8427 them unreadable to those users who must not be allowed to
8432 It is possible to arrange that the system administrator can
8433 reconfigure the package to correspond to their local
8434 security policy by changing the permissions on a binary:
8435 they can do this by using <prgn>dpkg-statoverride</prgn>, as
8436 described below.<footnote>
8437 Ordinary files installed by <prgn>dpkg</prgn> (as
8438 opposed to <tt>conffile</tt>s and other similar objects)
8439 normally have their permissions reset to the distributed
8440 permissions when the package is reinstalled. However,
8441 the use of <prgn>dpkg-statoverride</prgn> overrides this
8444 Another method you should consider is to create a group for
8445 people allowed to use the program(s) and make any setuid
8446 executables executable only by that group.
8450 If you need to create a new user or group for your package
8451 there are two possibilities. Firstly, you may need to
8452 make some files in the binary package be owned by this
8453 user or group, or you may need to compile the user or
8454 group id (rather than just the name) into the binary
8455 (though this latter should be avoided if possible, as in
8456 this case you need a statically allocated id).</p>
8459 If you need a statically allocated id, you must ask for a
8460 user or group id from the <tt>base-passwd</tt> maintainer,
8461 and must not release the package until you have been
8462 allocated one. Once you have been allocated one you must
8463 either make the package depend on a version of the
8464 <tt>base-passwd</tt> package with the id present in
8465 <file>/etc/passwd</file> or <file>/etc/group</file>, or arrange for
8466 your package to create the user or group itself with the
8467 correct id (using <tt>adduser</tt>) in its
8468 <prgn>preinst</prgn> or <prgn>postinst</prgn>. (Doing it in
8469 the <prgn>postinst</prgn> is to be preferred if it is
8470 possible, otherwise a pre-dependency will be needed on the
8471 <tt>adduser</tt> package.)
8475 On the other hand, the program might be able to determine
8476 the uid or gid from the user or group name at runtime, so
8477 that a dynamically allocated id can be used. In this case
8478 you should choose an appropriate user or group name,
8479 discussing this on <prgn>debian-devel</prgn> and checking
8480 with the <package/base-passwd/ maintainer that it is unique and that
8481 they do not wish you to use a statically allocated id
8482 instead. When this has been checked you must arrange for
8483 your package to create the user or group if necessary using
8484 <prgn>adduser</prgn> in the <prgn>preinst</prgn> or
8485 <prgn>postinst</prgn> script (again, the latter is to be
8486 preferred if it is possible).
8490 Note that changing the numeric value of an id associated
8491 with a name is very difficult, and involves searching the
8492 file system for all appropriate files. You need to think
8493 carefully whether a static or dynamic id is required, since
8494 changing your mind later will cause problems.
8497 <sect1><heading>The use of <prgn>dpkg-statoverride</prgn></heading>
8499 This section is not intended as policy, but as a
8500 description of the use of <prgn>dpkg-statoverride</prgn>.
8504 If a system administrator wishes to have a file (or
8505 directory or other such thing) installed with owner and
8506 permissions different from those in the distributed Debian
8507 package, they can use the <prgn>dpkg-statoverride</prgn>
8508 program to instruct <prgn>dpkg</prgn> to use the different
8509 settings every time the file is installed. Thus the
8510 package maintainer should distribute the files with their
8511 normal permissions, and leave it for the system
8512 administrator to make any desired changes. For example, a
8513 daemon which is normally required to be setuid root, but
8514 in certain situations could be used without being setuid,
8515 should be installed setuid in the <tt>.deb</tt>. Then the
8516 local system administrator can change this if they wish.
8517 If there are two standard ways of doing it, the package
8518 maintainer can use <tt>debconf</tt> to find out the
8519 preference, and call <prgn>dpkg-statoverride</prgn> in the
8520 maintainer script if necessary to accommodate the system
8521 administrator's choice. Care must be taken during
8522 upgrades to not override an existing setting.
8526 Given the above, <prgn>dpkg-statoverride</prgn> is
8527 essentially a tool for system administrators and would not
8528 normally be needed in the maintainer scripts. There is
8529 one type of situation, though, where calls to
8530 <prgn>dpkg-statoverride</prgn> would be needed in the
8531 maintainer scripts, and that involves packages which use
8532 dynamically allocated user or group ids. In such a
8533 situation, something like the following idiom can be very
8534 helpful in the package's <prgn>postinst</prgn>, where
8535 <tt>sysuser</tt> is a dynamically allocated id:
8537 for i in /usr/bin/foo /usr/sbin/bar
8539 # only do something when no setting exists
8540 if ! dpkg-statoverride --list $i >/dev/null 2>&1
8542 #include: debconf processing, question about foo and bar
8543 if [ "$RET" = "true" ] ; then
8544 dpkg-statoverride --update --add sysuser root 4755 $i
8549 The corresponding code to remove the override when the package
8552 for i in /usr/bin/foo /usr/sbin/bar
8554 if dpkg-statoverride --list $i >/dev/null 2>&1
8556 dpkg-statoverride --remove $i
8566 <chapt id="customized-programs">
8567 <heading>Customized programs</heading>
8569 <sect id="arch-spec">
8570 <heading>Architecture specification strings</heading>
8573 If a program needs to specify an <em>architecture specification
8574 string</em> in some place, it should select one of the strings
8575 provided by <tt>dpkg-architecture -L</tt>. The strings are in
8576 the format <tt><var>os</var>-<var>arch</var></tt>, though the OS
8577 part is sometimes elided, as when the OS is Linux.
8581 Note that we don't want to use
8582 <tt><var>arch</var>-debian-linux</tt> to apply to the rule
8583 <tt><var>architecture</var>-<var>vendor</var>-<var>os</var></tt>
8584 since this would make our programs incompatible with other
8585 Linux distributions. We also don't use something like
8586 <tt><var>arch</var>-unknown-linux</tt>, since the
8587 <tt>unknown</tt> does not look very good.
8590 <sect1 id="arch-wildcard-spec">
8591 <heading>Architecture wildcards</heading>
8594 A package may specify an architecture wildcard. Architecture
8595 wildcards are in the format <tt>any</tt> (which matches every
8596 architecture), <tt><var>os</var></tt>-any, or
8597 any-<tt><var>cpu</var></tt>. <footnote>
8598 Internally, the package system normalizes the GNU triplets
8599 and the Debian arches into Debian arch triplets (which are
8600 kind of inverted GNU triplets), with the first component of
8601 the triplet representing the libc and ABI in use, and then
8602 does matching against those triplets. However, such
8603 triplets are an internal implementation detail that should
8604 not be used by packages directly. The libc and ABI portion
8605 is handled internally by the package system based on
8606 the <var>os</var> and <var>cpu</var>.
8613 <heading>Daemons</heading>
8616 The configuration files <file>/etc/services</file>,
8617 <file>/etc/protocols</file>, and <file>/etc/rpc</file> are managed
8618 by the <prgn>netbase</prgn> package and must not be modified
8623 If a package requires a new entry in one of these files, the
8624 maintainer should get in contact with the
8625 <prgn>netbase</prgn> maintainer, who will add the entries
8626 and release a new version of the <prgn>netbase</prgn>
8631 The configuration file <file>/etc/inetd.conf</file> must not be
8632 modified by the package's scripts except via the
8633 <prgn>update-inetd</prgn> script or the
8634 <file>DebianNet.pm</file> Perl module. See their documentation
8635 for details on how to add entries.
8639 If a package wants to install an example entry into
8640 <file>/etc/inetd.conf</file>, the entry must be preceded with
8641 exactly one hash character (<tt>#</tt>). Such lines are
8642 treated as "commented out by user" by the
8643 <prgn>update-inetd</prgn> script and are not changed or
8644 activated during package updates.
8649 <heading>Using pseudo-ttys and modifying wtmp, utmp and
8653 Some programs need to create pseudo-ttys. This should be done
8654 using Unix98 ptys if the C library supports it. The resulting
8655 program must not be installed setuid root, unless that
8656 is required for other functionality.
8660 The files <file>/var/run/utmp</file>, <file>/var/log/wtmp</file> and
8661 <file>/var/log/lastlog</file> must be installed writable by
8662 group <tt>utmp</tt>. Programs which need to modify those
8663 files must be installed setgid <tt>utmp</tt>.
8668 <heading>Editors and pagers</heading>
8671 Some programs have the ability to launch an editor or pager
8672 program to edit or display a text document. Since there are
8673 lots of different editors and pagers available in the Debian
8674 distribution, the system administrator and each user should
8675 have the possibility to choose their preferred editor and
8680 In addition, every program should choose a good default
8681 editor/pager if none is selected by the user or system
8686 Thus, every program that launches an editor or pager must
8687 use the EDITOR or PAGER environment variable to determine
8688 the editor or pager the user wishes to use. If these
8689 variables are not set, the programs <file>/usr/bin/editor</file>
8690 and <file>/usr/bin/pager</file> should be used, respectively.
8694 These two files are managed through the <prgn>dpkg</prgn>
8695 "alternatives" mechanism. Every package providing an editor or
8696 pager must call the <prgn>update-alternatives</prgn> script to
8697 register as an alternative for <file>/usr/bin/editor</file>
8698 or <file>/usr/bin/pager</file> as appropriate. The alternative
8699 should have a slave alternative
8700 for <file>/usr/share/man/man1/editor.1.gz</file>
8701 or <file>/usr/share/man/man1/pager.1.gz</file> pointing to the
8702 corresponding manual page.
8706 If it is very hard to adapt a program to make use of the
8707 EDITOR or PAGER variables, that program may be configured to
8708 use <file>/usr/bin/sensible-editor</file> and
8709 <file>/usr/bin/sensible-pager</file> as the editor or pager
8710 program respectively. These are two scripts provided in the
8711 <package>sensible-utils</package> package that check the EDITOR
8712 and PAGER variables and launch the appropriate program, and fall
8713 back to <file>/usr/bin/editor</file>
8714 and <file>/usr/bin/pager</file> if the variable is not set.
8718 A program may also use the VISUAL environment variable to
8719 determine the user's choice of editor. If it exists, it
8720 should take precedence over EDITOR. This is in fact what
8721 <file>/usr/bin/sensible-editor</file> does.
8725 It is not required for a package to depend on
8726 <tt>editor</tt> and <tt>pager</tt>, nor is it required for a
8727 package to provide such virtual packages.<footnote>
8728 The Debian base system already provides an editor and a
8734 <sect id="web-appl">
8735 <heading>Web servers and applications</heading>
8738 This section describes the locations and URLs that should
8739 be used by all web servers and web applications in the
8746 Cgi-bin executable files are installed in the
8748 <example compact="compact">
8749 /usr/lib/cgi-bin/<var>cgi-bin-name</var>
8751 or a subdirectory of that directory, and should be
8753 <example compact="compact">
8754 http://localhost/cgi-bin/<var>cgi-bin-name</var>
8756 (possibly with a subdirectory name
8757 before <var>cgi-bin-name</var>).
8761 <p>Access to HTML documents</p>
8764 HTML documents for a package are stored in
8765 <file>/usr/share/doc/<var>package</var></file>
8766 and can be referred to as
8767 <example compact="compact">
8768 http://localhost/doc/<var>package</var>/<var>filename</var>
8773 The web server should restrict access to the document
8774 tree so that only clients on the same host can read
8775 the documents. If the web server does not support such
8776 access controls, then it should not provide access at
8777 all, or ask about providing access during installation.
8782 <p>Access to images</p>
8784 It is recommended that images for a package be stored
8785 in <tt>/usr/share/images/<var>package</var></tt> and
8786 may be referred to through an alias <tt>/images/</tt>
8789 http://localhost/images/<package>/<filename>
8796 <p>Web Document Root</p>
8799 Web Applications should try to avoid storing files in
8800 the Web Document Root. Instead they should use the
8801 /usr/share/doc/<var>package</var> directory for
8802 documents and register the Web Application via the
8803 <package>doc-base</package> package. If access to the
8804 web document root is unavoidable then use
8805 <example compact="compact">
8808 as the Document Root. This might be just a symbolic
8809 link to the location where the system administrator
8810 has put the real document root.
8813 <item><p>Providing httpd and/or httpd-cgi</p>
8815 All web servers should provide the virtual package
8816 <tt>httpd</tt>. If a web server has CGI support it should
8817 provide <tt>httpd-cgi</tt> additionally.
8820 All web applications which do not contain CGI scripts should
8821 depend on <tt>httpd</tt>, all those web applications which
8822 <tt>do</tt> contain CGI scripts, should depend on
8830 <sect id="mail-transport-agents">
8831 <heading>Mail transport, delivery and user agents</heading>
8834 Debian packages which process electronic mail, whether mail
8835 user agents (MUAs) or mail transport agents (MTAs), must
8836 ensure that they are compatible with the configuration
8837 decisions below. Failure to do this may result in lost
8838 mail, broken <tt>From:</tt> lines, and other serious brain
8843 The mail spool is <file>/var/mail</file> and the interface to
8844 send a mail message is <file>/usr/sbin/sendmail</file> (as per
8845 the FHS). On older systems, the mail spool may be
8846 physically located in <file>/var/spool/mail</file>, but all
8847 access to the mail spool should be via the
8848 <file>/var/mail</file> symlink. The mail spool is part of the
8849 base system and not part of the MTA package.
8853 All Debian MUAs, MTAs, MDAs and other mailbox accessing
8854 programs (such as IMAP daemons) must lock the mailbox in an
8855 NFS-safe way. This means that <tt>fcntl()</tt> locking must
8856 be combined with dot locking. To avoid deadlocks, a program
8857 should use <tt>fcntl()</tt> first and dot locking after
8858 this, or alternatively implement the two locking methods in
8859 a non blocking way<footnote>
8860 If it is not possible to establish both locks, the
8861 system shouldn't wait for the second lock to be
8862 established, but remove the first lock, wait a (random)
8863 time, and start over locking again.
8864 </footnote>. Using the functions <tt>maillock</tt> and
8865 <tt>mailunlock</tt> provided by the
8866 <tt>liblockfile*</tt><footnote>
8867 You will need to depend on <tt>liblockfile1 (>>1.01)</tt>
8868 to use these functions.
8869 </footnote> packages is the recommended way to realize this.
8873 Mailboxes are generally either mode 600 and owned by
8874 <var>user</var> or mode 660 and owned by
8875 <tt><var>user</var>:mail</tt><footnote>
8876 There are two traditional permission schemes for mail spools:
8877 mode 600 with all mail delivery done by processes running as
8878 the destination user, or mode 660 and owned by group mail with
8879 mail delivery done by a process running as a system user in
8880 group mail. Historically, Debian required mode 660 mail
8881 spools to enable the latter model, but that model has become
8882 increasingly uncommon and the principle of least privilege
8883 indicates that mail systems that use the first model should
8884 use permissions of 600. If delivery to programs is permitted,
8885 it's easier to keep the mail system secure if the delivery
8886 agent runs as the destination user. Debian Policy therefore
8887 permits either scheme.
8888 </footnote>. The local system administrator may choose a
8889 different permission scheme; packages should not make
8890 assumptions about the permission and ownership of mailboxes
8891 unless required (such as when creating a new mailbox). A MUA
8892 may remove a mailbox (unless it has nonstandard permissions) in
8893 which case the MTA or another MUA must recreate it if needed.
8897 The mail spool is 2775 <tt>root:mail</tt>, and MUAs should
8898 be setgid mail to do the locking mentioned above (and
8899 must obviously avoid accessing other users' mailboxes
8900 using this privilege).</p>
8903 <file>/etc/aliases</file> is the source file for the system mail
8904 aliases (e.g., postmaster, usenet, etc.), it is the one
8905 which the sysadmin and <prgn>postinst</prgn> scripts may
8906 edit. After <file>/etc/aliases</file> is edited the program or
8907 human editing it must call <prgn>newaliases</prgn>. All MTA
8908 packages must come with a <prgn>newaliases</prgn> program,
8909 even if it does nothing, but older MTA packages did not do
8910 this so programs should not fail if <prgn>newaliases</prgn>
8911 cannot be found. Note that because of this, all MTA
8912 packages must have <tt>Provides</tt>, <tt>Conflicts</tt> and
8913 <tt>Replaces: mail-transport-agent</tt> control fields.
8917 The convention of writing <tt>forward to
8918 <var>address</var></tt> in the mailbox itself is not
8919 supported. Use a <tt>.forward</tt> file instead.</p>
8922 The <prgn>rmail</prgn> program used by UUCP
8923 for incoming mail should be <file>/usr/sbin/rmail</file>.
8924 Likewise, <prgn>rsmtp</prgn>, for receiving
8925 batch-SMTP-over-UUCP, should be <file>/usr/sbin/rsmtp</file> if it
8929 If your package needs to know what hostname to use on (for
8930 example) outgoing news and mail messages which are generated
8931 locally, you should use the file <file>/etc/mailname</file>. It
8932 will contain the portion after the username and <tt>@</tt>
8933 (at) sign for email addresses of users on the machine
8934 (followed by a newline).
8938 Such a package should check for the existence of this file
8939 when it is being configured. If it exists, it should be
8940 used without comment, although an MTA's configuration script
8941 may wish to prompt the user even if it finds that this file
8942 exists. If the file does not exist, the package should
8943 prompt the user for the value (preferably using
8944 <prgn>debconf</prgn>) and store it in <file>/etc/mailname</file>
8945 as well as using it in the package's configuration. The
8946 prompt should make it clear that the name will not just be
8947 used by that package. For example, in this situation the
8948 <tt>inn</tt> package could say something like:
8949 <example compact="compact">
8950 Please enter the "mail name" of your system. This is the
8951 hostname portion of the address to be shown on outgoing
8952 news and mail messages. The default is
8953 <var>syshostname</var>, your system's host name. Mail
8954 name ["<var>syshostname</var>"]:
8956 where <var>syshostname</var> is the output of <tt>hostname
8962 <heading>News system configuration</heading>
8965 All the configuration files related to the NNTP (news)
8966 servers and clients should be located under
8967 <file>/etc/news</file>.</p>
8970 There are some configuration issues that apply to a number
8971 of news clients and server packages on the machine. These
8975 <tag><file>/etc/news/organization</file></tag>
8977 A string which should appear as the
8978 organization header for all messages posted
8979 by NNTP clients on the machine
8982 <tag><file>/etc/news/server</file></tag>
8984 Contains the FQDN of the upstream NNTP
8985 server, or localhost if the local machine is
8990 Other global files may be added as required for cross-package news
8997 <heading>Programs for the X Window System</heading>
9000 <heading>Providing X support and package priorities</heading>
9003 Programs that can be configured with support for the X
9004 Window System must be configured to do so and must declare
9005 any package dependencies necessary to satisfy their
9006 runtime requirements when using the X Window System. If
9007 such a package is of higher priority than the X packages
9008 on which it depends, it is required that either the
9009 X-specific components be split into a separate package, or
9010 that an alternative version of the package, which includes
9011 X support, be provided, or that the package's priority be
9017 <heading>Packages providing an X server</heading>
9020 Packages that provide an X server that, directly or
9021 indirectly, communicates with real input and display
9022 hardware should declare in their <tt>Provides</tt> control
9023 field that they provide the virtual
9024 package <tt>xserver</tt>.<footnote>
9025 This implements current practice, and provides an
9026 actual policy for usage of the <tt>xserver</tt>
9027 virtual package which appears in the virtual packages
9028 list. In a nutshell, X servers that interface
9029 directly with the display and input hardware or via
9030 another subsystem (e.g., GGI) should provide
9031 <tt>xserver</tt>. Things like <tt>Xvfb</tt>,
9032 <tt>Xnest</tt>, and <tt>Xprt</tt> should not.
9038 <heading>Packages providing a terminal emulator</heading>
9041 Packages that provide a terminal emulator for the X Window
9042 System which meet the criteria listed below should declare in
9043 their <tt>Provides</tt> control field that they provide the
9044 virtual package <tt>x-terminal-emulator</tt>. They should
9045 also register themselves as an alternative for
9046 <file>/usr/bin/x-terminal-emulator</file>, with a priority of
9047 20. That alternative should have a slave alternative
9048 for <file>/usr/share/man/man1/x-terminal-emulator.1.gz</file>
9049 pointing to the corresponding manual page.
9053 To be an <tt>x-terminal-emulator</tt>, a program must:
9054 <list compact="compact">
9056 Be able to emulate a DEC VT100 terminal, or a
9057 compatible terminal.
9061 Support the command-line option <tt>-e
9062 <var>command</var></tt>, which creates a new
9063 terminal window<footnote>
9064 "New terminal window" does not necessarily mean
9065 a new top-level X window directly parented by
9066 the window manager; it could, if the terminal
9067 emulator application were so coded, be a new
9068 "view" in a multiple-document interface (MDI).
9070 and runs the specified <var>command</var>,
9071 interpreting the entirety of the rest of the command
9072 line as a command to pass straight to exec, in the
9073 manner that <tt>xterm</tt> does.
9077 Support the command-line option <tt>-T
9078 <var>title</var></tt>, which creates a new terminal
9079 window with the window title <var>title</var>.
9086 <heading>Packages providing a window manager</heading>
9089 Packages that provide a window manager should declare in
9090 their <tt>Provides</tt> control field that they provide the
9091 virtual package <tt>x-window-manager</tt>. They should also
9092 register themselves as an alternative for
9093 <file>/usr/bin/x-window-manager</file>, with a priority
9094 calculated as follows:
9095 <list compact="compact">
9097 Start with a priority of 20.
9101 If the window manager supports the Debian menu
9102 system, add 20 points if this support is available
9103 in the package's default configuration (i.e., no
9104 configuration files belonging to the system or user
9105 have to be edited to activate the feature); if
9106 configuration files must be modified, add only 10
9112 If the window manager complies with <url
9113 id="http://www.freedesktop.org/wiki/Specifications/wm-spec"
9114 name="The Window Manager Specification Project">,
9115 written by the <url id="http://www.freedesktop.org/wiki/"
9116 name="Free Desktop Group">, add 40 points.
9120 If the window manager permits the X session to be
9121 restarted using a <em>different</em> window manager
9122 (without killing the X server) in its default
9123 configuration, add 10 points; otherwise add none.
9126 That alternative should have a slave alternative
9127 for <file>/usr/share/man/man1/x-window-manager.1.gz</file>
9128 pointing to the corresponding manual page.
9133 <heading>Packages providing fonts</heading>
9136 Packages that provide fonts for the X Window
9138 For the purposes of Debian Policy, a "font for the X
9139 Window System" is one which is accessed via X protocol
9140 requests. Fonts for the Linux console, for PostScript
9141 renderer, or any other purpose, do not fit this
9142 definition. Any tool which makes such fonts available
9143 to the X Window System, however, must abide by this
9146 must do a number of things to ensure that they are both
9147 available without modification of the X or font server
9148 configuration, and that they do not corrupt files used by
9149 other font packages to register information about
9153 Fonts of any type supported by the X Window System
9154 must be in a separate binary package from any
9155 executables, libraries, or documentation (except
9156 that specific to the fonts shipped, such as their
9157 license information). If one or more of the fonts
9158 so packaged are necessary for proper operation of
9159 the package with which they are associated the font
9160 package may be Recommended; if the fonts merely
9161 provide an enhancement, a Suggests relationship may
9162 be used. Packages must not Depend on font
9164 This is because the X server may retrieve fonts
9165 from the local file system or over the network
9166 from an X font server; the Debian package system
9167 is empowered to deal only with the local
9173 BDF fonts must be converted to PCF fonts with the
9174 <prgn>bdftopcf</prgn> utility (available in the
9175 <tt>xfonts-utils</tt> package, <prgn>gzip</prgn>ped, and
9176 placed in a directory that corresponds to their
9178 <list compact="compact">
9180 100 dpi fonts must be placed in
9181 <file>/usr/share/fonts/X11/100dpi/</file>.
9185 75 dpi fonts must be placed in
9186 <file>/usr/share/fonts/X11/75dpi/</file>.
9190 Character-cell fonts, cursor fonts, and other
9191 low-resolution fonts must be placed in
9192 <file>/usr/share/fonts/X11/misc/</file>.
9198 Type 1 fonts must be placed in
9199 <file>/usr/share/fonts/X11/Type1/</file>. If font
9200 metric files are available, they must be placed here
9205 Subdirectories of <file>/usr/share/fonts/X11/</file>
9206 other than those listed above must be neither
9207 created nor used. (The <file>PEX</file>, <file>CID</file>,
9208 <file>Speedo</file>, and <file>cyrillic</file> directories
9209 are excepted for historical reasons, but installation of
9210 files into these directories remains discouraged.)
9214 Font packages may, instead of placing files directly
9215 in the X font directories listed above, provide
9216 symbolic links in that font directory pointing to
9217 the files' actual location in the filesystem. Such
9218 a location must comply with the FHS.
9222 Font packages should not contain both 75dpi and
9223 100dpi versions of a font. If both are available,
9224 they should be provided in separate binary packages
9225 with <tt>-75dpi</tt> or <tt>-100dpi</tt> appended to
9226 the names of the packages containing the
9227 corresponding fonts.
9231 Fonts destined for the <file>misc</file> subdirectory
9232 should not be included in the same package as 75dpi
9233 or 100dpi fonts; instead, they should be provided in
9234 a separate package with <tt>-misc</tt> appended to
9239 Font packages must not provide the files
9240 <file>fonts.dir</file>, <file>fonts.alias</file>, or
9241 <file>fonts.scale</file> in a font directory:
9244 <file>fonts.dir</file> files must not be provided at all.
9248 <file>fonts.alias</file> and <file>fonts.scale</file>
9249 files, if needed, should be provided in the
9251 <file>/etc/X11/fonts/<var>fontdir</var>/<var>package</var>.<var>extension</var></file>,
9252 where <var>fontdir</var> is the name of the
9254 <file>/usr/share/fonts/X11/</file> where the
9255 package's corresponding fonts are stored
9256 (e.g., <tt>75dpi</tt> or <tt>misc</tt>),
9257 <var>package</var> is the name of the package
9258 that provides these fonts, and
9259 <var>extension</var> is either <tt>scale</tt>
9260 or <tt>alias</tt>, whichever corresponds to
9267 Font packages must declare a dependency on
9268 <tt>xfonts-utils</tt> in their <tt>Depends</tt>
9269 or <tt>Pre-Depends</tt> control field.
9273 Font packages that provide one or more
9274 <file>fonts.scale</file> files as described above must
9275 invoke <prgn>update-fonts-scale</prgn> on each
9276 directory into which they installed fonts
9277 <em>before</em> invoking
9278 <prgn>update-fonts-dir</prgn> on that directory.
9279 This invocation must occur in both the
9280 <prgn>postinst</prgn> (for all arguments) and
9281 <prgn>postrm</prgn> (for all arguments except
9282 <tt>upgrade</tt>) scripts.
9286 Font packages that provide one or more
9287 <file>fonts.alias</file> files as described above must
9288 invoke <prgn>update-fonts-alias</prgn> on each
9289 directory into which they installed fonts. This
9290 invocation must occur in both the
9291 <prgn>postinst</prgn> (for all arguments) and
9292 <prgn>postrm</prgn> (for all arguments except
9293 <tt>upgrade</tt>) scripts.
9297 Font packages must invoke
9298 <prgn>update-fonts-dir</prgn> on each directory into
9299 which they installed fonts. This invocation must
9300 occur in both the <prgn>postinst</prgn> (for all
9301 arguments) and <prgn>postrm</prgn> (for all
9302 arguments except <tt>upgrade</tt>) scripts.
9306 Font packages must not provide alias names for the
9307 fonts they include which collide with alias names
9308 already in use by fonts already packaged.
9312 Font packages must not provide fonts with the same
9313 XLFD registry name as another font already packaged.
9319 <sect1 id="appdefaults">
9320 <heading>Application defaults files</heading>
9323 Application defaults files must be installed in the
9324 directory <file>/etc/X11/app-defaults/</file> (use of a
9325 localized subdirectory of <file>/etc/X11/</file> as described
9326 in the <em>X Toolkit Intrinsics - C Language
9327 Interface</em> manual is also permitted). They must be
9328 registered as <tt>conffile</tt>s or handled as
9329 configuration files.
9333 Customization of programs' X resources may also be
9334 supported with the provision of a file with the same name
9335 as that of the package placed in
9336 the <file>/etc/X11/Xresources/</file> directory, which
9337 must be registered as a <tt>conffile</tt> or handled as a
9338 configuration file.<footnote>
9339 Note that this mechanism is not the same as using
9340 app-defaults; app-defaults are tied to the client
9341 binary on the local file system, whereas X resources
9342 are stored in the X server and affect all connecting
9349 <heading>Installation directory issues</heading>
9352 Historically, packages using the X Window System used a
9353 separate set of installation directories from other packages.
9354 This practice has been discontinued and packages using the X
9355 Window System should now generally be installed in the same
9356 directories as any other package. Specifically, packages must
9357 not install files under the <file>/usr/X11R6/</file> directory
9358 and the <file>/usr/X11R6/</file> directory hierarchy should be
9359 regarded as obsolete.
9363 Include files previously installed under
9364 <file>/usr/X11R6/include/X11/</file> should be installed into
9365 <file>/usr/include/X11/</file>. For files previously
9366 installed into subdirectories of
9367 <file>/usr/X11R6/lib/X11/</file>, package maintainers should
9368 determine if subdirectories of <file>/usr/lib/</file> and
9369 <file>/usr/share/</file> can be used. If not, a subdirectory
9370 of <file>/usr/lib/X11/</file> should be used.
9374 Configuration files for window, display, or session managers
9375 or other applications that are tightly integrated with the X
9376 Window System may be placed in a subdirectory
9377 of <file>/etc/X11/</file> corresponding to the package name.
9378 Other X Window System applications should use
9379 the <file>/etc/</file> directory unless otherwise mandated by
9380 policy (such as for <ref id="appdefaults">).
9386 <heading>Perl programs and modules</heading>
9389 Perl programs and modules should follow the current Perl policy.
9393 The Perl policy can be found in the <tt>perl-policy</tt>
9394 files in the <tt>debian-policy</tt> package.
9395 It is also available from the Debian web mirrors at
9396 <tt><url name="/doc/packaging-manuals/perl-policy/"
9397 id="http://www.debian.org/doc/packaging-manuals/perl-policy/"></tt>.
9402 <heading>Emacs lisp programs</heading>
9405 Please refer to the "Debian Emacs Policy" for details of how to
9406 package emacs lisp programs.
9410 The Emacs policy is available in
9411 <file>debian-emacs-policy.gz</file> of the
9412 <package>emacsen-common</package> package.
9413 It is also available from the Debian web mirrors at
9414 <tt><url name="/doc/packaging-manuals/debian-emacs-policy"
9415 id="http://www.debian.org/doc/packaging-manuals/debian-emacs-policy"></tt>.
9420 <heading>Games</heading>
9423 The permissions on <file>/var/games</file> are mode 755, owner
9424 <tt>root</tt> and group <tt>root</tt>.
9428 Each game decides on its own security policy.</p>
9431 Games which require protected, privileged access to
9432 high-score files, saved games, etc., may be made
9433 set-<em>group</em>-id (mode 2755) and owned by
9434 <tt>root:games</tt>, and use files and directories with
9435 appropriate permissions (770 <tt>root:games</tt>, for
9436 example). They must not be made
9437 set-<em>user</em>-id, as this causes security problems. (If
9438 an attacker can subvert any set-user-id game they can
9439 overwrite the executable of any other, causing other players
9440 of these games to run a Trojan horse program. With a
9441 set-group-id game the attacker only gets access to less
9442 important game data, and if they can get at the other
9443 players' accounts at all it will take considerably more
9447 Some packages, for example some fortune cookie programs, are
9448 configured by the upstream authors to install with their
9449 data files or other static information made unreadable so
9450 that they can only be accessed through set-id programs
9451 provided. You should not do this in a Debian package: anyone can
9452 download the <file>.deb</file> file and read the data from it,
9453 so there is no point making the files unreadable. Not
9454 making the files unreadable also means that you don't have
9455 to make so many programs set-id, which reduces the risk of a
9459 As described in the FHS, binaries of games should be
9460 installed in the directory <file>/usr/games</file>. This also
9461 applies to games that use the X Window System. Manual pages
9462 for games (X and non-X games) should be installed in
9463 <file>/usr/share/man/man6</file>.</p>
9469 <heading>Documentation</heading>
9472 <heading>Manual pages</heading>
9475 You should install manual pages in <prgn>nroff</prgn> source
9476 form, in appropriate places under <file>/usr/share/man</file>.
9477 You should only use sections 1 to 9 (see the FHS for more
9478 details). You must not install a pre-formatted "cat page".
9482 Each program, utility, and function should have an
9483 associated manual page included in the same package. It is
9484 suggested that all configuration files also have a manual
9485 page included as well. Manual pages for protocols and other
9486 auxiliary things are optional.
9490 If no manual page is available, this is considered as a bug
9491 and should be reported to the Debian Bug Tracking System (the
9492 maintainer of the package is allowed to write this bug report
9493 themselves, if they so desire). Do not close the bug report
9494 until a proper man page is available.<footnote>
9495 It is not very hard to write a man page. See the
9496 <url id="http://www.schweikhardt.net/man_page_howto.html"
9497 name="Man-Page-HOWTO">,
9498 <manref name="man" section="7">, the examples created
9499 by <prgn>dh_make</prgn>, the helper
9500 program <prgn>help2man</prgn>, or the
9501 directory <file>/usr/share/doc/man-db/examples</file>.
9506 You may forward a complaint about a missing man page to the
9507 upstream authors, and mark the bug as forwarded in the
9508 Debian bug tracking system. Even though the GNU Project do
9509 not in general consider the lack of a man page to be a bug,
9510 we do; if they tell you that they don't consider it a bug
9511 you should leave the bug in our bug tracking system open
9516 Manual pages should be installed compressed using <tt>gzip -9</tt>.
9520 If one man page needs to be accessible via several names it
9521 is better to use a symbolic link than the <file>.so</file>
9522 feature, but there is no need to fiddle with the relevant
9523 parts of the upstream source to change from <file>.so</file> to
9524 symlinks: don't do it unless it's easy. You should not
9525 create hard links in the manual page directories, nor put
9526 absolute filenames in <file>.so</file> directives. The filename
9527 in a <file>.so</file> in a man page should be relative to the
9528 base of the man page tree (usually
9529 <file>/usr/share/man</file>). If you do not create any links
9530 (whether symlinks, hard links, or <tt>.so</tt> directives)
9531 in the file system to the alternate names of the man page,
9532 then you should not rely on <prgn>man</prgn> finding your
9533 man page under those names based solely on the information in
9534 the man page's header.<footnote>
9535 Supporting this in <prgn>man</prgn> often requires
9536 unreasonable processing time to find a manual page or to
9537 report that none exists, and moves knowledge into man's
9538 database that would be better left in the file system.
9539 This support is therefore deprecated and will cease to
9540 be present in the future.
9545 Manual pages in locale-specific subdirectories of
9546 <file>/usr/share/man</file> should use either UTF-8 or the usual
9547 legacy encoding for that language (normally the one corresponding
9548 to the shortest relevant locale name in
9549 <file>/usr/share/i18n/SUPPORTED</file>). For example, pages under
9550 <file>/usr/share/man/fr</file> should use either UTF-8 or
9551 ISO-8859-1.<footnote>
9552 <prgn>man</prgn> will automatically detect whether UTF-8 is in
9553 use. In future, all manual pages will be required to use
9559 A country name (the <tt>DE</tt> in <tt>de_DE</tt>) should not be
9560 included in the subdirectory name unless it indicates a
9561 significant difference in the language, as this excludes
9562 speakers of the language in other countries.<footnote>
9563 At the time of writing, Chinese and Portuguese are the main
9564 languages with such differences, so <file>pt_BR</file>,
9565 <file>zh_CN</file>, and <file>zh_TW</file> are all allowed.
9570 If a localized version of a manual page is provided, it should
9571 either be up-to-date or it should be obvious to the reader that
9572 it is outdated and the original manual page should be used
9573 instead. This can be done either by a note at the beginning of
9574 the manual page or by showing the missing or changed portions in
9575 the original language instead of the target language.
9580 <heading>Info documents</heading>
9583 Info documents should be installed in <file>/usr/share/info</file>.
9584 They should be compressed with <tt>gzip -9</tt>.
9588 The <prgn>install-info</prgn> program maintains a directory of
9589 installed info documents in <file>/usr/share/info/dir</file> for
9590 the use of info readers.<footnote>
9591 It was previously necessary for packages installing info
9592 documents to run <prgn>install-info</prgn> from maintainer
9593 scripts. This is no longer necessary. The installation
9594 system now uses dpkg triggers.
9596 This file must not be included in packages. Packages containing
9597 info documents should depend on <tt>dpkg (>= 1.15.4) |
9598 install-info</tt> to ensure that the directory file is properly
9599 rebuilt during partial upgrades from Debian 5.0 (lenny) and
9604 Info documents should contain section and directory entry
9605 information in the document for the use
9606 of <prgn>install-info</prgn>. The section should be specified
9607 via a line starting with <tt>INFO-DIR-SECTION</tt> followed by a
9608 space and the section of this info page. The directory entry or
9609 entries should be included between
9610 a <tt>START-INFO-DIR-ENTRY</tt> line and
9611 an <tt>END-INFO-DIR-ENTRY</tt> line. For example:
9613 INFO-DIR-SECTION Individual utilities
9614 START-INFO-DIR-ENTRY
9615 * example: (example). An example info directory entry.
9618 To determine which section to use, you should look
9619 at <file>/usr/share/info/dir</file> on your system and choose
9620 the most relevant (or create a new section if none of the
9621 current sections are relevant).<footnote>
9622 Normally, info documents are generated from Texinfo source.
9623 To include this information in the generated info document, if
9624 it is absent, add commands like:
9626 @dircategory Individual utilities
9628 * example: (example). An example info directory entry.
9631 to the Texinfo source of the document and ensure that the info
9632 documents are rebuilt from source during the package build.
9638 <heading>Additional documentation</heading>
9641 Any additional documentation that comes with the package may
9642 be installed at the discretion of the package maintainer.
9643 Plain text documentation should be installed in the directory
9644 <file>/usr/share/doc/<var>package</var></file>, where
9645 <var>package</var> is the name of the package, and
9646 compressed with <tt>gzip -9</tt> unless it is small.
9650 If a package comes with large amounts of documentation which
9651 many users of the package will not require you should create
9652 a separate binary package to contain it, so that it does not
9653 take up disk space on the machines of users who do not need
9654 or want it installed.</p>
9657 It is often a good idea to put text information files
9658 (<file>README</file>s, changelogs, and so forth) that come with
9659 the source package in <file>/usr/share/doc/<var>package</var></file>
9660 in the binary package. However, you don't need to install
9661 the instructions for building and installing the package, of
9665 Packages must not require the existence of any files in
9666 <file>/usr/share/doc/</file> in order to function
9668 The system administrator should be able to
9669 delete files in <file>/usr/share/doc/</file> without causing
9670 any programs to break.
9672 Any files that are referenced by programs but are also
9673 useful as stand alone documentation should be installed under
9674 <file>/usr/share/<var>package</var>/</file> with symbolic links from
9675 <file>/usr/share/doc/<var>package</var></file>.
9679 <file>/usr/share/doc/<var>package</var></file> may be a symbolic
9680 link to another directory in <file>/usr/share/doc</file> only if
9681 the two packages both come from the same source and the
9682 first package Depends on the second.<footnote>
9684 Please note that this does not override the section on
9685 changelog files below, so the file
9686 <file>/usr/share/doc/<var>package</var>/changelog.Debian.gz</file>
9687 must refer to the changelog for the current version of
9688 <var>package</var> in question. In practice, this means
9689 that the sources of the target and the destination of the
9690 symlink must be the same (same source package and
9697 Former Debian releases placed all additional documentation
9698 in <file>/usr/doc/<var>package</var></file>. This has been
9699 changed to <file>/usr/share/doc/<var>package</var></file>,
9700 and packages must not put documentation in the directory
9701 <file>/usr/doc/<var>package</var></file>. <footnote>
9702 At this phase of the transition, we no longer require a
9703 symbolic link in <file>/usr/doc/</file>. At a later point,
9704 policy shall change to make the symbolic links a bug.
9710 <heading>Preferred documentation formats</heading>
9713 The unification of Debian documentation is being carried out
9717 If your package comes with extensive documentation in a
9718 markup format that can be converted to various other formats
9719 you should if possible ship HTML versions in a binary
9720 package, in the directory
9721 <file>/usr/share/doc/<var>appropriate-package</var></file> or
9722 its subdirectories.<footnote>
9723 The rationale: The important thing here is that HTML
9724 docs should be available in <em>some</em> package, not
9725 necessarily in the main binary package.
9730 Other formats such as PostScript may be provided at the
9731 package maintainer's discretion.
9735 <sect id="copyrightfile">
9736 <heading>Copyright information</heading>
9739 Every package must be accompanied by a verbatim copy of its
9740 copyright information and distribution license in the file
9741 <file>/usr/share/doc/<var>package</var>/copyright</file>. This
9742 file must neither be compressed nor be a symbolic link.
9746 In addition, the copyright file must say where the upstream
9747 sources (if any) were obtained. It should name the original
9748 authors of the package and the Debian maintainer(s) who were
9749 involved with its creation.
9753 Packages in the <em>contrib</em> or <em>non-free</em> archive
9754 areas should state in the copyright file that the package is not
9755 part of the Debian distribution and briefly explain why.
9759 A copy of the file which will be installed in
9760 <file>/usr/share/doc/<var>package</var>/copyright</file> should
9761 be in <file>debian/copyright</file> in the source package.
9765 <file>/usr/share/doc/<var>package</var></file> may be a symbolic
9766 link to another directory in <file>/usr/share/doc</file> only if
9767 the two packages both come from the same source and the
9768 first package Depends on the second. These rules are important
9769 because <file>copyright</file> files must be extractable by
9774 Packages distributed under the Apache license (version 2.0), the
9775 Artistic license, the GNU GPL (versions 1, 2, or 3), the GNU
9776 LGPL (versions 2, 2.1, or 3), and the GNU FDL (versions 1.2 or
9777 1.3) should refer to the corresponding files
9778 under <file>/usr/share/common-licenses</file>,<footnote>
9781 <file>/usr/share/common-licenses/Apache-2.0</file>,
9782 <file>/usr/share/common-licenses/Artistic</file>,
9783 <file>/usr/share/common-licenses/GPL-1</file>,
9784 <file>/usr/share/common-licenses/GPL-2</file>,
9785 <file>/usr/share/common-licenses/GPL-3</file>,
9786 <file>/usr/share/common-licenses/LGPL-2</file>,
9787 <file>/usr/share/common-licenses/LGPL-2.1</file>,
9788 <file>/usr/share/common-licenses/LGPL-3</file>,
9789 <file>/usr/share/common-licenses/GFDL-1.2</file>, and
9790 <file>/usr/share/common-licenses/GFDL-1.3</file>
9791 respectively. The University of California BSD license is
9792 also included in <package>base-files</package> as
9793 <file>/usr/share/common-licenses/BSD</file>, but given the
9794 brevity of this license, its specificity to code whose
9795 copyright is held by the Regents of the University of
9796 California, and the frequency of minor wording changes, its
9797 text should be included in the copyright file rather than
9798 referencing this file.
9800 </footnote> rather than quoting them in the copyright
9805 You should not use the copyright file as a general <file>README</file>
9806 file. If your package has such a file it should be
9807 installed in <file>/usr/share/doc/<var>package</var>/README</file> or
9808 <file>README.Debian</file> or some other appropriate place.</p>
9812 <heading>Examples</heading>
9815 Any examples (configurations, source files, whatever),
9816 should be installed in a directory
9817 <file>/usr/share/doc/<var>package</var>/examples</file>. These
9818 files should not be referenced by any program: they're there
9819 for the benefit of the system administrator and users as
9820 documentation only. Architecture-specific example files
9821 should be installed in a directory
9822 <file>/usr/lib/<var>package</var>/examples</file> with symbolic
9824 <file>/usr/share/doc/<var>package</var>/examples</file>, or the
9825 latter directory itself may be a symbolic link to the
9830 If the purpose of a package is to provide examples, then the
9831 example files may be installed into
9832 <file>/usr/share/doc/<var>package</var></file>.
9836 <sect id="changelogs">
9837 <heading>Changelog files</heading>
9840 Packages that are not Debian-native must contain a
9841 compressed copy of the <file>debian/changelog</file> file from
9842 the Debian source tree in
9843 <file>/usr/share/doc/<var>package</var></file> with the name
9844 <file>changelog.Debian.gz</file>.
9848 If an upstream changelog is available, it should be accessible as
9849 <file>/usr/share/doc/<var>package</var>/changelog.gz</file> in
9850 plain text. If the upstream changelog is distributed in
9851 HTML, it should be made available in that form as
9852 <file>/usr/share/doc/<var>package</var>/changelog.html.gz</file>
9853 and a plain text <file>changelog.gz</file> should be generated
9854 from it using, for example, <tt>lynx -dump -nolist</tt>. If
9855 the upstream changelog files do not already conform to this
9856 naming convention, then this may be achieved either by
9857 renaming the files, or by adding a symbolic link, at the
9858 maintainer's discretion.<footnote>
9859 Rationale: People should not have to look in places for
9860 upstream changelogs merely because they are given
9861 different names or are distributed in HTML format.
9866 All of these files should be installed compressed using
9867 <tt>gzip -9</tt>, as they will become large with time even
9868 if they start out small.
9872 If the package has only one changelog which is used both as
9873 the Debian changelog and the upstream one because there is
9874 no separate upstream maintainer then that changelog should
9875 usually be installed as
9876 <file>/usr/share/doc/<var>package</var>/changelog.gz</file>; if
9877 there is a separate upstream maintainer, but no upstream
9878 changelog, then the Debian changelog should still be called
9879 <file>changelog.Debian.gz</file>.
9883 For details about the format and contents of the Debian
9884 changelog file, please see <ref id="dpkgchangelog">.
9889 <appendix id="pkg-scope">
9890 <heading>Introduction and scope of these appendices</heading>
9893 These appendices are taken essentially verbatim from the
9894 now-deprecated Packaging Manual, version 3.2.1.0. They are
9895 the chapters which are likely to be of use to package
9896 maintainers and which have not already been included in the
9897 policy document itself. Most of these sections are very likely
9898 not relevant to policy; they should be treated as
9899 documentation for the packaging system. Please note that these
9900 appendices are included for convenience, and for historical
9901 reasons: they used to be part of policy package, and they have
9902 not yet been incorporated into dpkg documentation. However,
9903 they still have value, and hence they are presented here.
9907 They have not yet been checked to ensure that they are
9908 compatible with the contents of policy, and if there are any
9909 contradictions, the version in the main policy document takes
9910 precedence. The remaining chapters of the old Packaging
9911 Manual have also not been read in detail to ensure that there
9912 are not parts which have been left out. Both of these will be
9917 Certain parts of the Packaging manual were integrated into the
9918 Policy Manual proper, and removed from the appendices. Links
9919 have been placed from the old locations to the new ones.
9923 <prgn>dpkg</prgn> is a suite of programs for creating binary
9924 package files and installing and removing them on Unix
9926 <prgn>dpkg</prgn> is targeted primarily at Debian, but may
9927 work on or be ported to other systems.
9932 The binary packages are designed for the management of
9933 installed executable programs (usually compiled binaries) and
9934 their associated data, though source code examples and
9935 documentation are provided as part of some packages.</p>
9938 This manual describes the technical aspects of creating Debian
9939 binary packages (<file>.deb</file> files). It documents the
9940 behavior of the package management programs
9941 <prgn>dpkg</prgn>, <prgn>dselect</prgn> et al. and the way
9942 they interact with packages.</p>
9945 It also documents the interaction between
9946 <prgn>dselect</prgn>'s core and the access method scripts it
9947 uses to actually install the selected packages, and describes
9948 how to create a new access method.</p>
9951 This manual does not go into detail about the options and
9952 usage of the package building and installation tools. It
9953 should therefore be read in conjunction with those programs'
9958 The utility programs which are provided with <prgn>dpkg</prgn>
9959 for managing various system configuration and similar issues,
9960 such as <prgn>update-rc.d</prgn> and
9961 <prgn>install-info</prgn>, are not described in detail here -
9962 please see their man pages.
9966 It is assumed that the reader is reasonably familiar with the
9967 <prgn>dpkg</prgn> System Administrators' manual.
9968 Unfortunately this manual does not yet exist.
9972 The Debian version of the FSF's GNU hello program is provided as
9973 an example for people wishing to create Debian packages. However,
9974 while the examples are helpful, they do not replace the need to
9975 read and follow the Policy and Programmer's Manual.</p>
9978 <appendix id="pkg-binarypkg">
9979 <heading>Binary packages (from old Packaging Manual)</heading>
9982 The binary package has two main sections. The first part
9983 consists of various control information files and scripts used
9984 by <prgn>dpkg</prgn> when installing and removing. See <ref
9985 id="pkg-controlarea">.
9989 The second part is an archive containing the files and
9990 directories to be installed.
9994 In the future binary packages may also contain other
9995 components, such as checksums and digital signatures. The
9996 format for the archive is described in full in the
9997 <file>deb(5)</file> man page.
10001 <sect id="pkg-bincreating"><heading>Creating package files -
10002 <prgn>dpkg-deb</prgn>
10006 All manipulation of binary package files is done by
10007 <prgn>dpkg-deb</prgn>; it's the only program that has
10008 knowledge of the format. (<prgn>dpkg-deb</prgn> may be
10009 invoked by calling <prgn>dpkg</prgn>, as <prgn>dpkg</prgn>
10010 will spot that the options requested are appropriate to
10011 <prgn>dpkg-deb</prgn> and invoke that instead with the same
10016 In order to create a binary package you must make a
10017 directory tree which contains all the files and directories
10018 you want to have in the file system data part of the package.
10019 In Debian-format source packages this directory is usually
10020 <file>debian/tmp</file>, relative to the top of the package's
10025 They should have the locations (relative to the root of the
10026 directory tree you're constructing) ownerships and
10027 permissions which you want them to have on the system when
10028 they are installed.
10032 With current versions of <prgn>dpkg</prgn> the uid/username
10033 and gid/groupname mappings for the users and groups being
10034 used should be the same on the system where the package is
10035 built and the one where it is installed.
10039 You need to add one special directory to the root of the
10040 miniature file system tree you're creating:
10041 <prgn>DEBIAN</prgn>. It should contain the control
10042 information files, notably the binary package control file
10043 (see <ref id="pkg-controlfile">).
10047 The <prgn>DEBIAN</prgn> directory will not appear in the
10048 file system archive of the package, and so won't be installed
10049 by <prgn>dpkg</prgn> when the package is unpacked.
10053 When you've prepared the package, you should invoke:
10055 dpkg --build <var>directory</var>
10060 This will build the package in
10061 <file><var>directory</var>.deb</file>. (<prgn>dpkg</prgn> knows
10062 that <tt>--build</tt> is a <prgn>dpkg-deb</prgn> option, so
10063 it invokes <prgn>dpkg-deb</prgn> with the same arguments to
10064 build the package.)
10068 See the man page <manref name="dpkg-deb" section="8"> for details of how
10069 to examine the contents of this newly-created file. You may find the
10070 output of following commands enlightening:
10072 dpkg-deb --info <var>filename</var>.deb
10073 dpkg-deb --contents <var>filename</var>.deb
10074 dpkg --contents <var>filename</var>.deb
10076 To view the copyright file for a package you could use this command:
10078 dpkg --fsys-tarfile <var>filename</var>.deb | tar xOf - --wildcards \*/copyright | pager
10083 <sect id="pkg-controlarea">
10084 <heading>Package control information files</heading>
10087 The control information portion of a binary package is a
10088 collection of files with names known to <prgn>dpkg</prgn>.
10089 It will treat the contents of these files specially - some
10090 of them contain information used by <prgn>dpkg</prgn> when
10091 installing or removing the package; others are scripts which
10092 the package maintainer wants <prgn>dpkg</prgn> to run.
10096 It is possible to put other files in the package control
10097 information file area, but this is not generally a good idea
10098 (though they will largely be ignored).
10102 Here is a brief list of the control information files supported
10103 by <prgn>dpkg</prgn> and a summary of what they're used for.
10108 <tag><tt>control</tt>
10111 This is the key description file used by
10112 <prgn>dpkg</prgn>. It specifies the package's name
10113 and version, gives its description for the user,
10114 states its relationships with other packages, and so
10115 forth. See <ref id="sourcecontrolfiles"> and
10116 <ref id="binarycontrolfiles">.
10120 It is usually generated automatically from information
10121 in the source package by the
10122 <prgn>dpkg-gencontrol</prgn> program, and with
10123 assistance from <prgn>dpkg-shlibdeps</prgn>.
10124 See <ref id="pkg-sourcetools">.
10128 <tag><tt>postinst</tt>, <tt>preinst</tt>, <tt>postrm</tt>,
10133 These are executable files (usually scripts) which
10134 <prgn>dpkg</prgn> runs during installation, upgrade
10135 and removal of packages. They allow the package to
10136 deal with matters which are particular to that package
10137 or require more complicated processing than that
10138 provided by <prgn>dpkg</prgn>. Details of when and
10139 how they are called are in <ref id="maintainerscripts">.
10143 It is very important to make these scripts idempotent.
10144 See <ref id="idempotency">.
10148 The maintainer scripts are not guaranteed to run with a
10149 controlling terminal and may not be able to interact with
10150 the user. See <ref id="controllingterminal">.
10154 <tag><tt>conffiles</tt>
10157 This file contains a list of configuration files which
10158 are to be handled automatically by <prgn>dpkg</prgn>
10159 (see <ref id="pkg-conffiles">). Note that not necessarily
10160 every configuration file should be listed here.
10163 <tag><tt>shlibs</tt>
10166 This file contains a list of the shared libraries
10167 supplied by the package, with dependency details for
10168 each. This is used by <prgn>dpkg-shlibdeps</prgn>
10169 when it determines what dependencies are required in a
10170 package control file. The <tt>shlibs</tt> file format
10171 is described on <ref id="shlibs">.
10176 <sect id="pkg-controlfile">
10177 <heading>The main control information file: <tt>control</tt></heading>
10180 The most important control information file used by
10181 <prgn>dpkg</prgn> when it installs a package is
10182 <tt>control</tt>. It contains all the package's "vital
10187 The binary package control files of packages built from
10188 Debian sources are made by a special tool,
10189 <prgn>dpkg-gencontrol</prgn>, which reads
10190 <file>debian/control</file> and <file>debian/changelog</file> to
10191 find the information it needs. See <ref id="pkg-sourcepkg"> for
10196 The fields in binary package control files are listed in
10197 <ref id="binarycontrolfiles">.
10201 A description of the syntax of control files and the purpose
10202 of the fields is available in <ref id="controlfields">.
10207 <heading>Time Stamps</heading>
10210 See <ref id="timestamps">.
10215 <appendix id="pkg-sourcepkg">
10216 <heading>Source packages (from old Packaging Manual) </heading>
10219 The Debian binary packages in the distribution are generated
10220 from Debian sources, which are in a special format to assist
10221 the easy and automatic building of binaries.
10224 <sect id="pkg-sourcetools">
10225 <heading>Tools for processing source packages</heading>
10228 Various tools are provided for manipulating source packages;
10229 they pack and unpack sources and help build of binary
10230 packages and help manage the distribution of new versions.
10234 They are introduced and typical uses described here; see
10235 <manref name="dpkg-source" section="1"> for full
10236 documentation about their arguments and operation.
10240 For examples of how to construct a Debian source package,
10241 and how to use those utilities that are used by Debian
10242 source packages, please see the <prgn>hello</prgn> example
10246 <sect1 id="pkg-dpkg-source">
10248 <prgn>dpkg-source</prgn> - packs and unpacks Debian source
10253 This program is frequently used by hand, and is also
10254 called from package-independent automated building scripts
10255 such as <prgn>dpkg-buildpackage</prgn>.
10259 To unpack a package it is typically invoked with
10261 dpkg-source -x <var>.../path/to/filename</var>.dsc
10266 with the <file><var>filename</var>.tar.gz</file> and
10267 <file><var>filename</var>.diff.gz</file> (if applicable) in
10268 the same directory. It unpacks into
10269 <file><var>package</var>-<var>version</var></file>, and if
10271 <file><var>package</var>-<var>version</var>.orig</file>, in
10272 the current directory.
10276 To create a packed source archive it is typically invoked:
10278 dpkg-source -b <var>package</var>-<var>version</var>
10283 This will create the <file>.dsc</file>, <file>.tar.gz</file> and
10284 <file>.diff.gz</file> (if appropriate) in the current
10285 directory. <prgn>dpkg-source</prgn> does not clean the
10286 source tree first - this must be done separately if it is
10291 See also <ref id="pkg-sourcearchives">.</p>
10295 <sect1 id="pkg-dpkg-buildpackage">
10297 <prgn>dpkg-buildpackage</prgn> - overall package-building
10302 <prgn>dpkg-buildpackage</prgn> is a script which invokes
10303 <prgn>dpkg-source</prgn>, the <file>debian/rules</file>
10304 targets <tt>clean</tt>, <tt>build</tt> and
10305 <tt>binary</tt>, <prgn>dpkg-genchanges</prgn> and
10306 <prgn>gpg</prgn> (or <prgn>pgp</prgn>) to build a signed
10307 source and binary package upload.
10311 It is usually invoked by hand from the top level of the
10312 built or unbuilt source directory. It may be invoked with
10313 no arguments; useful arguments include:
10314 <taglist compact="compact">
10315 <tag><tt>-uc</tt>, <tt>-us</tt></tag>
10318 Do not sign the <tt>.changes</tt> file or the
10319 source package <tt>.dsc</tt> file, respectively.</p>
10321 <tag><tt>-p<var>sign-command</var></tt></tag>
10324 Invoke <var>sign-command</var> instead of finding
10325 <tt>gpg</tt> or <tt>pgp</tt> on the <prgn>PATH</prgn>.
10326 <var>sign-command</var> must behave just like
10327 <prgn>gpg</prgn> or <tt>pgp</tt>.</p>
10329 <tag><tt>-r<var>root-command</var></tt></tag>
10332 When root privilege is required, invoke the command
10333 <var>root-command</var>. <var>root-command</var>
10334 should invoke its first argument as a command, from
10335 the <prgn>PATH</prgn> if necessary, and pass its
10336 second and subsequent arguments to the command it
10337 calls. If no <var>root-command</var> is supplied
10338 then <var>dpkg-buildpackage</var> will take no
10339 special action to gain root privilege, so that for
10340 most packages it will have to be invoked as root to
10343 <tag><tt>-b</tt>, <tt>-B</tt></tag>
10346 Two types of binary-only build and upload - see
10347 <manref name="dpkg-source" section="1">.
10354 <sect1 id="pkg-dpkg-gencontrol">
10356 <prgn>dpkg-gencontrol</prgn> - generates binary package
10361 This program is usually called from <file>debian/rules</file>
10362 (see <ref id="pkg-sourcetree">) in the top level of the source
10367 This is usually done just before the files and directories in the
10368 temporary directory tree where the package is being built have their
10369 permissions and ownerships set and the package is constructed using
10370 <prgn>dpkg-deb/</prgn>
10372 This is so that the control file which is produced has
10373 the right permissions
10378 <prgn>dpkg-gencontrol</prgn> must be called after all the
10379 files which are to go into the package have been placed in
10380 the temporary build directory, so that its calculation of
10381 the installed size of a package is correct.
10385 It is also necessary for <prgn>dpkg-gencontrol</prgn> to
10386 be run after <prgn>dpkg-shlibdeps</prgn> so that the
10387 variable substitutions created by
10388 <prgn>dpkg-shlibdeps</prgn> in <file>debian/substvars</file>
10393 For a package which generates only one binary package, and
10394 which builds it in <file>debian/tmp</file> relative to the top
10395 of the source package, it is usually sufficient to call
10396 <prgn>dpkg-gencontrol</prgn>.
10400 Sources which build several binaries will typically need
10403 dpkg-gencontrol -Pdebian/tmp-<var>pkg</var> -p<var>package</var>
10404 </example> The <tt>-P</tt> tells
10405 <prgn>dpkg-gencontrol</prgn> that the package is being
10406 built in a non-default directory, and the <tt>-p</tt>
10407 tells it which package's control file should be generated.
10411 <prgn>dpkg-gencontrol</prgn> also adds information to the
10412 list of files in <file>debian/files</file>, for the benefit of
10413 (for example) a future invocation of
10414 <prgn>dpkg-genchanges</prgn>.</p>
10417 <sect1 id="pkg-dpkg-shlibdeps">
10419 <prgn>dpkg-shlibdeps</prgn> - calculates shared library
10424 This program is usually called from <file>debian/rules</file>
10425 just before <prgn>dpkg-gencontrol</prgn> (see <ref
10426 id="pkg-sourcetree">), in the top level of the source tree.
10430 Its arguments are executables and shared libraries
10433 They may be specified either in the locations in the
10434 source tree where they are created or in the locations
10435 in the temporary build tree where they are installed
10436 prior to binary package creation.
10438 </footnote> for which shared library dependencies should
10439 be included in the binary package's control file.
10443 If some of the found shared libraries should only
10444 warrant a <tt>Recommends</tt> or <tt>Suggests</tt>, or if
10445 some warrant a <tt>Pre-Depends</tt>, this can be achieved
10446 by using the <tt>-d<var>dependency-field</var></tt> option
10447 before those executable(s). (Each <tt>-d</tt> option
10448 takes effect until the next <tt>-d</tt>.)
10452 <prgn>dpkg-shlibdeps</prgn> does not directly cause the
10453 output control file to be modified. Instead by default it
10454 adds to the <file>debian/substvars</file> file variable
10455 settings like <tt>shlibs:Depends</tt>. These variable
10456 settings must be referenced in dependency fields in the
10457 appropriate per-binary-package sections of the source
10462 For example, a package that generates an essential part
10463 which requires dependencies, and optional parts that
10464 which only require a recommendation, would separate those
10465 two sets of dependencies into two different fields.<footnote>
10466 At the time of writing, an example for this was the
10467 <package/xmms/ package, with Depends used for the xmms
10468 executable, Recommends for the plug-ins and Suggests for
10469 even more optional features provided by unzip.
10471 It can say in its <file>debian/rules</file>:
10473 dpkg-shlibdeps -dDepends <var>program anotherprogram ...</var> \
10474 -dRecommends <var>optionalpart anotheroptionalpart</var>
10476 and then in its main control file <file>debian/control</file>:
10479 Depends: ${shlibs:Depends}
10480 Recommends: ${shlibs:Recommends}
10486 Sources which produce several binary packages with
10487 different shared library dependency requirements can use
10488 the <tt>-p<var>varnameprefix</var></tt> option to override
10489 the default <tt>shlibs:</tt> prefix (one invocation of
10490 <prgn>dpkg-shlibdeps</prgn> per setting of this option).
10491 They can thus produce several sets of dependency
10492 variables, each of the form
10493 <tt><var>varnameprefix</var>:<var>dependencyfield</var></tt>,
10494 which can be referred to in the appropriate parts of the
10495 binary package control files.
10500 <sect1 id="pkg-dpkg-distaddfile">
10502 <prgn>dpkg-distaddfile</prgn> - adds a file to
10503 <file>debian/files</file>
10507 Some packages' uploads need to include files other than
10508 the source and binary package files.
10512 <prgn>dpkg-distaddfile</prgn> adds a file to the
10513 <file>debian/files</file> file so that it will be included in
10514 the <file>.changes</file> file when
10515 <prgn>dpkg-genchanges</prgn> is run.
10519 It is usually invoked from the <tt>binary</tt> target of
10520 <file>debian/rules</file>:
10522 dpkg-distaddfile <var>filename</var> <var>section</var> <var>priority</var>
10524 The <var>filename</var> is relative to the directory where
10525 <prgn>dpkg-genchanges</prgn> will expect to find it - this
10526 is usually the directory above the top level of the source
10527 tree. The <file>debian/rules</file> target should put the
10528 file there just before or just after calling
10529 <prgn>dpkg-distaddfile</prgn>.
10533 The <var>section</var> and <var>priority</var> are passed
10534 unchanged into the resulting <file>.changes</file> file.
10539 <sect1 id="pkg-dpkg-genchanges">
10541 <prgn>dpkg-genchanges</prgn> - generates a <file>.changes</file>
10542 upload control file
10546 This program is usually called by package-independent
10547 automatic building scripts such as
10548 <prgn>dpkg-buildpackage</prgn>, but it may also be called
10553 It is usually called in the top level of a built source
10554 tree, and when invoked with no arguments will print out a
10555 straightforward <file>.changes</file> file based on the
10556 information in the source package's changelog and control
10557 file and the binary and source packages which should have
10563 <sect1 id="pkg-dpkg-parsechangelog">
10565 <prgn>dpkg-parsechangelog</prgn> - produces parsed
10566 representation of a changelog
10570 This program is used internally by
10571 <prgn>dpkg-source</prgn> et al. It may also occasionally
10572 be useful in <file>debian/rules</file> and elsewhere. It
10573 parses a changelog, <file>debian/changelog</file> by default,
10574 and prints a control-file format representation of the
10575 information in it to standard output.
10579 <sect1 id="pkg-dpkg-architecture">
10581 <prgn>dpkg-architecture</prgn> - information about the build and
10586 This program can be used manually, but is also invoked by
10587 <tt>dpkg-buildpackage</tt> or <file>debian/rules</file> to set
10588 environment or make variables which specify the build and host
10589 architecture for the package building process.
10594 <sect id="pkg-sourcetree">
10595 <heading>The Debian package source tree</heading>
10598 The source archive scheme described later is intended to
10599 allow a Debian package source tree with some associated
10600 control information to be reproduced and transported easily.
10601 The Debian package source tree is a version of the original
10602 program with certain files added for the benefit of the
10603 packaging process, and with any other changes required
10604 made to the rest of the source code and installation
10609 The extra files created for Debian are in the subdirectory
10610 <file>debian</file> of the top level of the Debian package
10611 source tree. They are described below.
10614 <sect1 id="pkg-debianrules">
10615 <heading><file>debian/rules</file> - the main building script</heading>
10618 See <ref id="debianrules">.
10622 <sect1 id="pkg-srcsubstvars">
10623 <heading><file>debian/substvars</file> and variable substitutions</heading>
10626 See <ref id="substvars">.
10632 <heading><file>debian/files</file></heading>
10635 See <ref id="debianfiles">.
10639 <sect1><heading><file>debian/tmp</file>
10643 This is the canonical temporary location for the
10644 construction of binary packages by the <tt>binary</tt>
10645 target. The directory <file>tmp</file> serves as the root of
10646 the file system tree as it is being constructed (for
10647 example, by using the package's upstream makefiles install
10648 targets and redirecting the output there), and it also
10649 contains the <tt>DEBIAN</tt> subdirectory. See <ref
10650 id="pkg-bincreating">.
10654 If several binary packages are generated from the same
10655 source tree it is usual to use several
10656 <file>debian/tmp<var>something</var></file> directories, for
10657 example <file>tmp-a</file> or <file>tmp-doc</file>.
10661 Whatever <file>tmp</file> directories are created and used by
10662 <tt>binary</tt> must of course be removed by the
10663 <tt>clean</tt> target.</p></sect1>
10667 <sect id="pkg-sourcearchives"><heading>Source packages as archives
10671 As it exists on the FTP site, a Debian source package
10672 consists of three related files. You must have the right
10673 versions of all three to be able to use them.
10678 <tag>Debian source control file - <tt>.dsc</tt></tag>
10680 This file is a control file used by <prgn>dpkg-source</prgn>
10681 to extract a source package.
10682 See <ref id="debiansourcecontrolfiles">.
10686 Original source archive -
10688 <var>package</var>_<var>upstream-version</var>.orig.tar.gz
10694 This is a compressed (with <tt>gzip -9</tt>)
10695 <prgn>tar</prgn> file containing the source code from
10696 the upstream authors of the program.
10701 Debian package diff -
10703 <var>package</var>_<var>upstream_version-revision</var>.diff.gz
10709 This is a unified context diff (<tt>diff -u</tt>)
10710 giving the changes which are required to turn the
10711 original source into the Debian source. These changes
10712 may only include editing and creating plain files.
10713 The permissions of files, the targets of symbolic
10714 links and the characteristics of special files or
10715 pipes may not be changed and no files may be removed
10720 All the directories in the diff must exist, except the
10721 <file>debian</file> subdirectory of the top of the source
10722 tree, which will be created by
10723 <prgn>dpkg-source</prgn> if necessary when unpacking.
10727 The <prgn>dpkg-source</prgn> program will
10728 automatically make the <file>debian/rules</file> file
10729 executable (see below).</p></item>
10734 If there is no original source code - for example, if the
10735 package is specially prepared for Debian or the Debian
10736 maintainer is the same as the upstream maintainer - the
10737 format is slightly different: then there is no diff, and the
10739 <file><var>package</var>_<var>version</var>.tar.gz</file>,
10740 and preferably contains a directory named
10741 <file><var>package</var>-<var>version</var></file>.
10746 <heading>Unpacking a Debian source package without <prgn>dpkg-source</prgn></heading>
10749 <tt>dpkg-source -x</tt> is the recommended way to unpack a
10750 Debian source package. However, if it is not available it
10751 is possible to unpack a Debian source archive as follows:
10752 <enumlist compact="compact">
10755 Untar the tarfile, which will create a <file>.orig</file>
10759 <p>Rename the <file>.orig</file> directory to
10760 <file><var>package</var>-<var>version</var></file>.</p>
10764 Create the subdirectory <file>debian</file> at the top of
10765 the source tree.</p>
10767 <item><p>Apply the diff using <tt>patch -p0</tt>.</p>
10769 <item><p>Untar the tarfile again if you want a copy of the original
10770 source code alongside the Debian version.</p>
10775 It is not possible to generate a valid Debian source archive
10776 without using <prgn>dpkg-source</prgn>. In particular,
10777 attempting to use <prgn>diff</prgn> directly to generate the
10778 <file>.diff.gz</file> file will not work.
10782 <heading>Restrictions on objects in source packages</heading>
10785 The source package may not contain any hard links
10787 This is not currently detected when building source
10788 packages, but only when extracting
10792 Hard links may be permitted at some point in the
10793 future, but would require a fair amount of
10795 </footnote>, device special files, sockets or setuid or
10798 Setgid directories are allowed.
10803 The source packaging tools manage the changes between the
10804 original and Debian source using <prgn>diff</prgn> and
10805 <prgn>patch</prgn>. Turning the original source tree as
10806 included in the <file>.orig.tar.gz</file> into the Debian
10807 package source must not involve any changes which cannot be
10808 handled by these tools. Problematic changes which cause
10809 <prgn>dpkg-source</prgn> to halt with an error when
10810 building the source package are:
10811 <list compact="compact">
10812 <item><p>Adding or removing symbolic links, sockets or pipes.</p>
10814 <item><p>Changing the targets of symbolic links.</p>
10816 <item><p>Creating directories, other than <file>debian</file>.</p>
10818 <item><p>Changes to the contents of binary files.</p></item>
10819 </list> Changes which cause <prgn>dpkg-source</prgn> to
10820 print a warning but continue anyway are:
10821 <list compact="compact">
10824 Removing files, directories or symlinks.
10826 Renaming a file is not treated specially - it is
10827 seen as the removal of the old file (which
10828 generates a warning, but is otherwise ignored),
10829 and the creation of the new one.
10835 Changed text files which are missing the usual final
10836 newline (either in the original or the modified
10841 Changes which are not represented, but which are not detected by
10842 <prgn>dpkg-source</prgn>, are:
10843 <list compact="compact">
10844 <item><p>Changing the permissions of files (other than
10845 <file>debian/rules</file>) and directories.</p></item>
10850 The <file>debian</file> directory and <file>debian/rules</file>
10851 are handled specially by <prgn>dpkg-source</prgn> - before
10852 applying the changes it will create the <file>debian</file>
10853 directory, and afterwards it will make
10854 <file>debian/rules</file> world-executable.
10860 <appendix id="pkg-controlfields">
10861 <heading>Control files and their fields (from old Packaging Manual)</heading>
10864 Many of the tools in the <prgn>dpkg</prgn> suite manipulate
10865 data in a common format, known as control files. Binary and
10866 source packages have control data as do the <file>.changes</file>
10867 files which control the installation of uploaded files, and
10868 <prgn>dpkg</prgn>'s internal databases are in a similar
10873 <heading>Syntax of control files</heading>
10876 See <ref id="controlsyntax">.
10880 It is important to note that there are several fields which
10881 are optional as far as <prgn>dpkg</prgn> and the related
10882 tools are concerned, but which must appear in every Debian
10883 package, or whose omission may cause problems.
10888 <heading>List of fields</heading>
10891 See <ref id="controlfieldslist">.
10895 This section now contains only the fields that didn't belong
10896 to the Policy manual.
10899 <sect1 id="pkg-f-Filename">
10900 <heading><tt>Filename</tt> and <tt>MSDOS-Filename</tt></heading>
10903 These fields in <tt>Packages</tt> files give the
10904 filename(s) of (the parts of) a package in the
10905 distribution directories, relative to the root of the
10906 Debian hierarchy. If the package has been split into
10907 several parts the parts are all listed in order, separated
10912 <sect1 id="pkg-f-Size">
10913 <heading><tt>Size</tt> and <tt>MD5sum</tt></heading>
10916 These fields in <file>Packages</file> files give the size (in
10917 bytes, expressed in decimal) and MD5 checksum of the
10918 file(s) which make(s) up a binary package in the
10919 distribution. If the package is split into several parts
10920 the values for the parts are listed in order, separated by
10925 <sect1 id="pkg-f-Status">
10926 <heading><tt>Status</tt></heading>
10929 This field in <prgn>dpkg</prgn>'s status file records
10930 whether the user wants a package installed, removed or
10931 left alone, whether it is broken (requiring
10932 re-installation) or not and what its current state on the
10933 system is. Each of these pieces of information is a
10938 <sect1 id="pkg-f-Config-Version">
10939 <heading><tt>Config-Version</tt></heading>
10942 If a package is not installed or not configured, this
10943 field in <prgn>dpkg</prgn>'s status file records the last
10944 version of the package which was successfully
10949 <sect1 id="pkg-f-Conffiles">
10950 <heading><tt>Conffiles</tt></heading>
10953 This field in <prgn>dpkg</prgn>'s status file contains
10954 information about the automatically-managed configuration
10955 files held by a package. This field should <em>not</em>
10956 appear anywhere in a package!
10961 <heading>Obsolete fields</heading>
10964 These are still recognized by <prgn>dpkg</prgn> but should
10965 not appear anywhere any more.
10967 <taglist compact="compact">
10969 <tag><tt>Revision</tt></tag>
10970 <tag><tt>Package-Revision</tt></tag>
10971 <tag><tt>Package_Revision</tt></tag>
10973 The Debian revision part of the package version was
10974 at one point in a separate control field. This
10975 field went through several names.
10978 <tag><tt>Recommended</tt></tag>
10979 <item>Old name for <tt>Recommends</tt>.</item>
10981 <tag><tt>Optional</tt></tag>
10982 <item>Old name for <tt>Suggests</tt>.</item>
10984 <tag><tt>Class</tt></tag>
10985 <item>Old name for <tt>Priority</tt>.</item>
10994 <appendix id="pkg-conffiles">
10995 <heading>Configuration file handling (from old Packaging Manual)</heading>
10998 <prgn>dpkg</prgn> can do a certain amount of automatic
10999 handling of package configuration files.
11003 Whether this mechanism is appropriate depends on a number of
11004 factors, but basically there are two approaches to any
11005 particular configuration file.
11009 The easy method is to ship a best-effort configuration in the
11010 package, and use <prgn>dpkg</prgn>'s conffile mechanism to
11011 handle updates. If the user is unlikely to want to edit the
11012 file, but you need them to be able to without losing their
11013 changes, and a new package with a changed version of the file
11014 is only released infrequently, this is a good approach.
11018 The hard method is to build the configuration file from
11019 scratch in the <prgn>postinst</prgn> script, and to take the
11020 responsibility for fixing any mistakes made in earlier
11021 versions of the package automatically. This will be
11022 appropriate if the file is likely to need to be different on
11026 <sect><heading>Automatic handling of configuration files by
11031 A package may contain a control information file called
11032 <tt>conffiles</tt>. This file should be a list of filenames
11033 of configuration files needing automatic handling, separated
11034 by newlines. The filenames should be absolute pathnames,
11035 and the files referred to should actually exist in the
11040 When a package is upgraded <prgn>dpkg</prgn> will process
11041 the configuration files during the configuration stage,
11042 shortly before it runs the package's <prgn>postinst</prgn>
11047 For each file it checks to see whether the version of the
11048 file included in the package is the same as the one that was
11049 included in the last version of the package (the one that is
11050 being upgraded from); it also compares the version currently
11051 installed on the system with the one shipped with the last
11056 If neither the user nor the package maintainer has changed
11057 the file, it is left alone. If one or the other has changed
11058 their version, then the changed version is preferred - i.e.,
11059 if the user edits their file, but the package maintainer
11060 doesn't ship a different version, the user's changes will
11061 stay, silently, but if the maintainer ships a new version
11062 and the user hasn't edited it the new version will be
11063 installed (with an informative message). If both have
11064 changed their version the user is prompted about the problem
11065 and must resolve the differences themselves.
11069 The comparisons are done by calculating the MD5 message
11070 digests of the files, and storing the MD5 of the file as it
11071 was included in the most recent version of the package.
11075 When a package is installed for the first time
11076 <prgn>dpkg</prgn> will install the file that comes with it,
11077 unless that would mean overwriting a file already on the
11082 However, note that <prgn>dpkg</prgn> will <em>not</em>
11083 replace a conffile that was removed by the user (or by a
11084 script). This is necessary because with some programs a
11085 missing file produces an effect hard or impossible to
11086 achieve in another way, so that a missing file needs to be
11087 kept that way if the user did it.
11091 Note that a package should <em>not</em> modify a
11092 <prgn>dpkg</prgn>-handled conffile in its maintainer
11093 scripts. Doing this will lead to <prgn>dpkg</prgn> giving
11094 the user confusing and possibly dangerous options for
11095 conffile update when the package is upgraded.</p>
11098 <sect><heading>Fully-featured maintainer script configuration
11103 For files which contain site-specific information such as
11104 the hostname and networking details and so forth, it is
11105 better to create the file in the package's
11106 <prgn>postinst</prgn> script.
11110 This will typically involve examining the state of the rest
11111 of the system to determine values and other information, and
11112 may involve prompting the user for some information which
11113 can't be obtained some other way.
11117 When using this method there are a couple of important
11118 issues which should be considered:
11122 If you discover a bug in the program which generates the
11123 configuration file, or if the format of the file changes
11124 from one version to the next, you will have to arrange for
11125 the postinst script to do something sensible - usually this
11126 will mean editing the installed configuration file to remove
11127 the problem or change the syntax. You will have to do this
11128 very carefully, since the user may have changed the file,
11129 perhaps to fix the very problem that your script is trying
11130 to deal with - you will have to detect these situations and
11131 deal with them correctly.
11135 If you do go down this route it's probably a good idea to
11136 make the program that generates the configuration file(s) a
11137 separate program in <file>/usr/sbin</file>, by convention called
11138 <file><var>package</var>config</file> and then run that if
11139 appropriate from the post-installation script. The
11140 <tt><var>package</var>config</tt> program should not
11141 unquestioningly overwrite an existing configuration - if its
11142 mode of operation is geared towards setting up a package for
11143 the first time (rather than any arbitrary reconfiguration
11144 later) you should have it check whether the configuration
11145 already exists, and require a <tt>--force</tt> flag to
11146 overwrite it.</p></sect>
11149 <appendix id="pkg-alternatives"><heading>Alternative versions of
11150 an interface - <prgn>update-alternatives</prgn> (from old
11155 When several packages all provide different versions of the
11156 same program or file it is useful to have the system select a
11157 default, but to allow the system administrator to change it
11158 and have their decisions respected.
11162 For example, there are several versions of the <prgn>vi</prgn>
11163 editor, and there is no reason to prevent all of them from
11164 being installed at once, each under their own name
11165 (<prgn>nvi</prgn>, <prgn>vim</prgn> or whatever).
11166 Nevertheless it is desirable to have the name <tt>vi</tt>
11167 refer to something, at least by default.
11171 If all the packages involved cooperate, this can be done with
11172 <prgn>update-alternatives</prgn>.
11176 Each package provides its own version under its own name, and
11177 calls <prgn>update-alternatives</prgn> in its postinst to
11178 register its version (and again in its prerm to deregister
11183 See the man page <manref name="update-alternatives"
11184 section="8"> for details.
11188 If <prgn>update-alternatives</prgn> does not seem appropriate
11189 you may wish to consider using diversions instead.</p>
11192 <appendix id="pkg-diversions"><heading>Diversions - overriding a
11193 package's version of a file (from old Packaging Manual)
11197 It is possible to have <prgn>dpkg</prgn> not overwrite a file
11198 when it reinstalls the package it belongs to, and to have it
11199 put the file from the package somewhere else instead.
11203 This can be used locally to override a package's version of a
11204 file, or by one package to override another's version (or
11205 provide a wrapper for it).
11209 Before deciding to use a diversion, read <ref
11210 id="pkg-alternatives"> to see if you really want a diversion
11211 rather than several alternative versions of a program.
11215 There is a diversion list, which is read by <prgn>dpkg</prgn>,
11216 and updated by a special program <prgn>dpkg-divert</prgn>.
11217 Please see <manref name="dpkg-divert" section="8"> for full
11218 details of its operation.
11222 When a package wishes to divert a file from another, it should
11223 call <prgn>dpkg-divert</prgn> in its preinst to add the
11224 diversion and rename the existing file. For example,
11225 supposing that a <prgn>smailwrapper</prgn> package wishes to
11226 install a wrapper around <file>/usr/sbin/smail</file>:
11228 dpkg-divert --package smailwrapper --add --rename \
11229 --divert /usr/sbin/smail.real /usr/sbin/smail
11230 </example> The <tt>--package smailwrapper</tt> ensures that
11231 <prgn>smailwrapper</prgn>'s copy of <file>/usr/sbin/smail</file>
11232 can bypass the diversion and get installed as the true version.
11233 It's safe to add the diversion unconditionally on upgrades since
11234 it will be left unchanged if it already exists, but
11235 <prgn>dpkg-divert</prgn> will display a message. To suppress that
11236 message, make the command conditional on the version from which
11237 the package is being upgraded:
11239 if [ upgrade != "$1" ] || dpkg --compare-versions "$2" lt 1.0-2; then
11240 dpkg-divert --package smailwrapper --add --rename \
11241 --divert /usr/sbin/smail.real /usr/sbin/smail
11243 </example> where <tt>1.0-2</tt> is the version at which the
11244 diversion was first added to the package. Running the command
11245 during abort-upgrade is pointless but harmless.
11249 The postrm has to do the reverse:
11251 if [ remove = "$1" -o abort-install = "$1" -o disappear = "$1" ]; then
11252 dpkg-divert --package smailwrapper --remove --rename \
11253 --divert /usr/sbin/smail.real /usr/sbin/smail
11255 </example> If the diversion was added at a particular version, the
11256 postrm should also handle the failure case of upgrading from an
11257 older version (unless the older version is so old that direct
11258 upgrades are no longer supported):
11260 if [ abort-upgrade = "$1" ] && dpkg --compare-versions "$2" lt 1.0-2; then
11261 dpkg-divert --package smailwrapper --remove --rename \
11262 --divert /usr/sbin/smail.real /usr/sbin/smail
11264 </example> where <tt>1.02-2</tt> is the version at which the
11265 diversion was first added to the package. The postrm should not
11266 remove the diversion on upgrades both because there's no reason to
11267 remove the diversion only to immediately re-add it and since the
11268 postrm of the old package is run after unpacking so the removal of
11269 the diversion will fail.
11273 Do not attempt to divert a file which is vitally important for
11274 the system's operation - when using <prgn>dpkg-divert</prgn>
11275 there is a time, after it has been diverted but before
11276 <prgn>dpkg</prgn> has installed the new version, when the file
11277 does not exist.</p>
11282 <!-- Local variables: -->
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