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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>Julian Gilbey</item>
223 <item>Branden Robinson</item>
224 <item>Josip Rodin</item>
225 <item>Manoj Srivastava</item>
230 While the authors of this document have tried hard to avoid
231 typos and other errors, these do still occur. If you discover
232 an error in this manual or if you want to give any
233 comments, suggestions, or criticisms please send an email to
234 the Debian Policy List,
235 <email>debian-policy@lists.debian.org</email>, or submit a
236 bug report against the <tt>debian-policy</tt> package.
240 Please do not try to reach the individual authors or maintainers
241 of the Policy Manual regarding changes to the Policy.
246 <heading>Related documents</heading>
249 There are several other documents other than this Policy Manual
250 that are necessary to fully understand some Debian policies and
255 The external "sub-policy" documents are referred to in:
256 <list compact="compact">
257 <item><ref id="fhs"></item>
258 <item><ref id="virtual_pkg"></item>
259 <item><ref id="menus"></item>
260 <item><ref id="mime"></item>
261 <item><ref id="perl"></item>
262 <item><ref id="maintscriptprompt"></item>
263 <item><ref id="emacs"></item>
268 In addition to those, which carry the weight of policy, there
269 is the Debian Developer's Reference. This document describes
270 procedures and resources for Debian developers, but it is
271 <em>not</em> normative; rather, it includes things that don't
272 belong in the Policy, such as best practices for developers.
276 The Developer's Reference is available in the
277 <package>developers-reference</package> package.
278 It's also available from the Debian web mirrors at
279 <tt><url name="/doc/developers-reference/"
280 id="http://www.debian.org/doc/developers-reference/"></tt>.
284 <sect id="definitions">
285 <heading>Definitions</heading>
288 The following terms are used in this Policy Manual:
292 The character encoding specified by ANSI X3.4-1986 and its
293 predecessor standards, referred to in MIME as US-ASCII, and
294 corresponding to an encoding in eight bits per character of
295 the first 128 <url id="http://www.unicode.org/"
296 name="Unicode"> characters, with the eighth bit always zero.
300 The transformation format (sometimes called encoding) of
301 <url id="http://www.unicode.org/" name="Unicode"> defined by
302 <url id="http://www.rfc-editor.org/rfc/rfc3629.txt"
303 name="RFC 3629">. UTF-8 has the useful property of having
304 ASCII as a subset, so any text encoded in ASCII is trivially
314 <heading>The Debian Archive</heading>
317 The Debian system is maintained and distributed as a
318 collection of <em>packages</em>. Since there are so many of
319 them (currently well over 15000), they are split into
320 <em>sections</em> and given <em>priorities</em> to simplify
321 the handling of them.
325 The effort of the Debian project is to build a free operating
326 system, but not every package we want to make accessible is
327 <em>free</em> in our sense (see the Debian Free Software
328 Guidelines, below), or may be imported/exported without
329 restrictions. Thus, the archive is split into areas<footnote>
330 The Debian archive software uses the term "component" internally
331 and in the Release file format to refer to the division of an
332 archive. The Debian Social Contract simply refers to "areas."
333 This document uses terminology similar to the Social Contract.
334 </footnote> based on their licenses and other restrictions.
338 The aims of this are:
340 <list compact="compact">
341 <item>to allow us to make as much software available as we can</item>
342 <item>to allow us to encourage everyone to write free software,
344 <item>to allow us to make it easy for people to produce
345 CD-ROMs of our system without violating any licenses,
346 import/export restrictions, or any other laws.</item>
351 The <em>main</em> archive area forms the <em>Debian distribution</em>.
355 Packages in the other archive areas (<tt>contrib</tt>,
356 <tt>non-free</tt>) are not considered to be part of the Debian
357 distribution, although we support their use and provide
358 infrastructure for them (such as our bug-tracking system and
359 mailing lists). This Debian Policy Manual applies to these
364 <heading>The Debian Free Software Guidelines</heading>
366 The Debian Free Software Guidelines (DFSG) form our
367 definition of "free software". These are:
369 <tag>1. Free Redistribution
372 The license of a Debian component may not restrict any
373 party from selling or giving away the software as a
374 component of an aggregate software distribution
375 containing programs from several different
376 sources. The license may not require a royalty or
377 other fee for such sale.
382 The program must include source code, and must allow
383 distribution in source code as well as compiled form.
385 <tag>3. Derived Works
388 The license must allow modifications and derived
389 works, and must allow them to be distributed under the
390 same terms as the license of the original software.
392 <tag>4. Integrity of The Author's Source Code
395 The license may restrict source-code from being
396 distributed in modified form <em>only</em> if the
397 license allows the distribution of "patch files"
398 with the source code for the purpose of modifying the
399 program at build time. The license must explicitly
400 permit distribution of software built from modified
401 source code. The license may require derived works to
402 carry a different name or version number from the
403 original software. (This is a compromise. The Debian
404 Project encourages all authors to not restrict any
405 files, source or binary, from being modified.)
407 <tag>5. No Discrimination Against Persons or Groups
410 The license must not discriminate against any person
413 <tag>6. No Discrimination Against Fields of Endeavor
416 The license must not restrict anyone from making use
417 of the program in a specific field of endeavor. For
418 example, it may not restrict the program from being
419 used in a business, or from being used for genetic
422 <tag>7. Distribution of License
425 The rights attached to the program must apply to all
426 to whom the program is redistributed without the need
427 for execution of an additional license by those
430 <tag>8. License Must Not Be Specific to Debian
433 The rights attached to the program must not depend on
434 the program's being part of a Debian system. If the
435 program is extracted from Debian and used or
436 distributed without Debian but otherwise within the
437 terms of the program's license, all parties to whom
438 the program is redistributed must have the same
439 rights as those that are granted in conjunction with
442 <tag>9. License Must Not Contaminate Other Software
445 The license must not place restrictions on other
446 software that is distributed along with the licensed
447 software. For example, the license must not insist
448 that all other programs distributed on the same medium
449 must be free software.
451 <tag>10. Example Licenses
454 The "GPL," "BSD," and "Artistic" licenses are examples of
455 licenses that we consider <em>free</em>.
462 <heading>Archive areas</heading>
465 <heading>The main archive area</heading>
468 Every package in <em>main</em> must comply with the DFSG
469 (Debian Free Software Guidelines).
473 In addition, the packages in <em>main</em>
474 <list compact="compact">
476 must not require a package outside of <em>main</em>
477 for compilation or execution (thus, the package must
478 not declare a "Depends", "Recommends", or
479 "Build-Depends" relationship on a non-<em>main</em>
483 must not be so buggy that we refuse to support them,
487 must meet all policy requirements presented in this
496 <heading>The contrib archive area</heading>
499 Every package in <em>contrib</em> must comply with the DFSG.
503 In addition, the packages in <em>contrib</em>
504 <list compact="compact">
506 must not be so buggy that we refuse to support them,
510 must meet all policy requirements presented in this
518 Examples of packages which would be included in
519 <em>contrib</em> are:
520 <list compact="compact">
522 free packages which require <em>contrib</em>,
523 <em>non-free</em> packages or packages which are not
524 in our archive at all for compilation or execution,
528 wrapper packages or other sorts of free accessories for
535 <sect1 id="non-free">
536 <heading>The non-free archive area</heading>
539 Packages must be placed in <em>non-free</em> if they are
540 not compliant with the DFSG or are encumbered by patents
541 or other legal issues that make their distribution
546 In addition, the packages in <em>non-free</em>
547 <list compact="compact">
549 must not be so buggy that we refuse to support them,
553 must meet all policy requirements presented in this
554 manual that it is possible for them to meet.
556 It is possible that there are policy
557 requirements which the package is unable to
558 meet, for example, if the source is
559 unavailable. These situations will need to be
560 handled on a case-by-case basis.
569 <sect id="pkgcopyright">
570 <heading>Copyright considerations</heading>
573 Every package must be accompanied by a verbatim copy of its
574 copyright information and distribution license in the file
575 <file>/usr/share/doc/<var>package</var>/copyright</file>
576 (see <ref id="copyrightfile"> for further details).
580 We reserve the right to restrict files from being included
581 anywhere in our archives if
582 <list compact="compact">
584 their use or distribution would break a law,
587 there is an ethical conflict in their distribution or
591 we would have to sign a license for them, or
594 their distribution would conflict with other project
601 Programs whose authors encourage the user to make
602 donations are fine for the main distribution, provided
603 that the authors do not claim that not donating is
604 immoral, unethical, illegal or something similar; in such
605 a case they must go in <em>non-free</em>.
609 Packages whose copyright permission notices (or patent
610 problems) do not even allow redistribution of binaries
611 only, and where no special permission has been obtained,
612 must not be placed on the Debian FTP site and its mirrors
617 Note that under international copyright law (this applies
618 in the United States, too), <em>no</em> distribution or
619 modification of a work is allowed without an explicit
620 notice saying so. Therefore a program without a copyright
621 notice <em>is</em> copyrighted and you may not do anything
622 to it without risking being sued! Likewise if a program
623 has a copyright notice but no statement saying what is
624 permitted then nothing is permitted.
628 Many authors are unaware of the problems that restrictive
629 copyrights (or lack of copyright notices) can cause for
630 the users of their supposedly-free software. It is often
631 worthwhile contacting such authors diplomatically to ask
632 them to modify their license terms. However, this can be a
633 politically difficult thing to do and you should ask for
634 advice on the <tt>debian-legal</tt> mailing list first, as
639 When in doubt about a copyright, send mail to
640 <email>debian-legal@lists.debian.org</email>. Be prepared
641 to provide us with the copyright statement. Software
642 covered by the GPL, public domain software and BSD-like
643 copyrights are safe; be wary of the phrases "commercial
644 use prohibited" and "distribution restricted".
648 <sect id="subsections">
649 <heading>Sections</heading>
652 The packages in the archive areas <em>main</em>,
653 <em>contrib</em> and <em>non-free</em> are grouped further into
654 <em>sections</em> to simplify handling.
658 The archive area and section for each package should be
659 specified in the package's <tt>Section</tt> control record (see
660 <ref id="f-Section">). However, the maintainer of the Debian
661 archive may override this selection to ensure the consistency of
662 the Debian distribution. The <tt>Section</tt> field should be
664 <list compact="compact">
666 <em>section</em> if the package is in the
667 <em>main</em> archive area,
670 <em>area/section</em> if the package is in
671 the <em>contrib</em> or <em>non-free</em>
678 The Debian archive maintainers provide the authoritative
679 list of sections. At present, they are:
680 <em>admin</em>, <em>cli-mono</em>, <em>comm</em>, <em>database</em>,
681 <em>devel</em>, <em>debug</em>, <em>doc</em>, <em>editors</em>,
682 <em>electronics</em>, <em>embedded</em>, <em>fonts</em>,
683 <em>games</em>, <em>gnome</em>, <em>graphics</em>, <em>gnu-r</em>,
684 <em>gnustep</em>, <em>hamradio</em>, <em>haskell</em>,
685 <em>httpd</em>, <em>interpreters</em>, <em>java</em>, <em>kde</em>,
686 <em>kernel</em>, <em>libs</em>, <em>libdevel</em>, <em>lisp</em>,
687 <em>localization</em>, <em>mail</em>, <em>math</em>, <em>misc</em>,
688 <em>net</em>, <em>news</em>, <em>ocaml</em>, <em>oldlibs</em>,
689 <em>otherosfs</em>, <em>perl</em>, <em>php</em>, <em>python</em>,
690 <em>ruby</em>, <em>science</em>, <em>shells</em>, <em>sound</em>,
691 <em>tex</em>, <em>text</em>, <em>utils</em>, <em>vcs</em>,
692 <em>video</em>, <em>web</em>, <em>x11</em>, <em>xfce</em>,
693 <em>zope</em>. The additional section <em>debian-installer</em>
694 contains special packages used by the installer and is not used
695 for normal Debian packages.
699 For more information about the sections and their definitions,
700 see the <url id="http://packages.debian.org/unstable/"
701 name="list of sections in unstable">.
705 <sect id="priorities">
706 <heading>Priorities</heading>
709 Each package should have a <em>priority</em> value, which is
710 included in the package's <em>control record</em>
711 (see <ref id="f-Priority">).
712 This information is used by the Debian package management tools to
713 separate high-priority packages from less-important packages.
717 The following <em>priority levels</em> are recognized by the
718 Debian package management tools.
720 <tag><tt>required</tt></tag>
722 Packages which are necessary for the proper
723 functioning of the system (usually, this means that
724 dpkg functionality depends on these packages).
725 Removing a <tt>required</tt> package may cause your
726 system to become totally broken and you may not even
727 be able to use <prgn>dpkg</prgn> to put things back,
728 so only do so if you know what you are doing. Systems
729 with only the <tt>required</tt> packages are probably
730 unusable, but they do have enough functionality to
731 allow the sysadmin to boot and install more software.
733 <tag><tt>important</tt></tag>
735 Important programs, including those which one would
736 expect to find on any Unix-like system. If the
737 expectation is that an experienced Unix person who
738 found it missing would say "What on earth is going on,
739 where is <prgn>foo</prgn>?", it must be an
740 <tt>important</tt> package.<footnote>
741 This is an important criterion because we are
742 trying to produce, amongst other things, a free
745 Other packages without which the system will not run
746 well or be usable must also have priority
747 <tt>important</tt>. This does
748 <em>not</em> include Emacs, the X Window System, TeX
749 or any other large applications. The
750 <tt>important</tt> packages are just a bare minimum of
751 commonly-expected and necessary tools.
753 <tag><tt>standard</tt></tag>
755 These packages provide a reasonably small but not too
756 limited character-mode system. This is what will be
757 installed by default if the user doesn't select anything
758 else. It doesn't include many large applications.
760 <tag><tt>optional</tt></tag>
762 (In a sense everything that isn't required is
763 optional, but that's not what is meant here.) This is
764 all the software that you might reasonably want to
765 install if you didn't know what it was and don't have
766 specialized requirements. This is a much larger system
767 and includes the X Window System, a full TeX
768 distribution, and many applications. Note that
769 optional packages should not conflict with each other.
771 <tag><tt>extra</tt></tag>
773 This contains all packages that conflict with others
774 with required, important, standard or optional
775 priorities, or are only likely to be useful if you
776 already know what they are or have specialized
777 requirements (such as packages containing only detached
784 Packages must not depend on packages with lower priority
785 values (excluding build-time dependencies). In order to
786 ensure this, the priorities of one or more packages may need
795 <heading>Binary packages</heading>
798 The Debian distribution is based on the Debian
799 package management system, called <prgn>dpkg</prgn>. Thus,
800 all packages in the Debian distribution must be provided
801 in the <tt>.deb</tt> file format.
805 A <tt>.deb</tt> package contains two sets of files: a set of files
806 to install on the system when the package is installed, and a set
807 of files that provide additional metadata about the package or
808 which are executed when the package is installed or removed. This
809 second set of files is called <em>control information files</em>.
810 Among those files are the package maintainer scripts
811 and <file>control</file>, the <qref id="binarycontrolfiles">binary
812 package control file</qref> that contains the control fields for
813 the package. Other control information files
814 include <qref id="sharedlibs-shlibdeps">the <file>shlibs</file>
815 file</qref> used to store shared library dependency information
816 and the <file>conffiles</file> file that lists the package's
817 configuration files (described in <ref id="config-files">).
821 There is unfortunately a collision of terminology here between
822 control information files and files in the Debian control file
823 format. Throughout this document, a <em>control file</em> refers
824 to a file in the Debian control file format. These files are
825 documented in <ref id="controlfields">. Only files referred to
826 specifically as <em>control information files</em> are the files
827 included in the control information file member of
828 the <file>.deb</file> file format used by binary packages. Most
829 control information files are not in the Debian control file
834 <heading>The package name</heading>
837 Every package must have a name that's unique within the Debian
842 The package name is included in the control field
843 <tt>Package</tt>, the format of which is described
844 in <ref id="f-Package">.
845 The package name is also included as a part of the file name
846 of the <tt>.deb</tt> file.
851 <heading>The version of a package</heading>
854 Every package has a version number recorded in its
855 <tt>Version</tt> control file field, described in
856 <ref id="f-Version">.
860 The package management system imposes an ordering on version
861 numbers, so that it can tell whether packages are being up- or
862 downgraded and so that package system front end applications
863 can tell whether a package it finds available is newer than
864 the one installed on the system. The version number format
865 has the most significant parts (as far as comparison is
866 concerned) at the beginning.
870 If an upstream package has problematic version numbers they
871 should be converted to a sane form for use in the
872 <tt>Version</tt> field.
876 <heading>Version numbers based on dates</heading>
879 In general, Debian packages should use the same version
880 numbers as the upstream sources. However, upstream version
881 numbers based on some date formats (sometimes used for
882 development or "snapshot" releases) will not be ordered
883 correctly by the package management software. For
884 example, <prgn>dpkg</prgn> will consider "96May01" to be
885 greater than "96Dec24".
889 To prevent having to use epochs for every new upstream
890 version, the date-based portion of any upstream version number
891 should be given in a way that sorts correctly: four-digit year
892 first, followed by a two-digit numeric month, followed by a
893 two-digit numeric date, possibly with punctuation between the
898 Native Debian packages (i.e., packages which have been written
899 especially for Debian) whose version numbers include dates
900 should also follow these rules. If punctuation is desired
901 between the date components, remember that hyphen (<tt>-</tt>)
902 cannot be used in native package versions. Period
903 (<tt>.</tt>) is normally a good choice.
909 <sect id="maintainer">
910 <heading>The maintainer of a package</heading>
913 Every package must have a maintainer, except for orphaned
914 packages as described below. The maintainer may be one person
915 or a group of people reachable from a common email address, such
916 as a mailing list. The maintainer is responsible for
917 maintaining the Debian packaging files, evaluating and
918 responding appropriately to reported bugs, uploading new
919 versions of the package (either directly or through a sponsor),
920 ensuring that the package is placed in the appropriate archive
921 area and included in Debian releases as appropriate for the
922 stability and utility of the package, and requesting removal of
923 the package from the Debian distribution if it is no longer
924 useful or maintainable.
928 The maintainer must be specified in the <tt>Maintainer</tt>
929 control field with their correct name and a working email
930 address. The email address given in the <tt>Maintainer</tt>
931 control field must accept mail from those role accounts in
932 Debian used to send automated mails regarding the package. This
933 includes non-spam mail from the bug-tracking system, all mail
934 from the Debian archive maintenance software, and other role
935 accounts or automated processes that are commonly agreed on by
936 the project.<footnote>
937 A sample implementation of such a whitelist written for the
938 Mailman mailing list management software is used for mailing
939 lists hosted by alioth.debian.org.
941 If one person or team maintains several packages, they should
942 use the same form of their name and email address in
943 the <tt>Maintainer</tt> fields of those packages.
947 The format of the <tt>Maintainer</tt> control field is
948 described in <ref id="f-Maintainer">.
952 If the maintainer of the package is a team of people with a
953 shared email address, the <tt>Uploaders</tt> control field must
954 be present and must contain at least one human with their
955 personal email address. See <ref id="f-Uploaders"> for the
956 syntax of that field.
960 An orphaned package is one with no current maintainer. Orphaned
961 packages should have their <tt>Maintainer</tt> control field set
962 to <tt>Debian QA Group <packages@qa.debian.org></tt>.
963 These packages are considered maintained by the Debian project
964 as a whole until someone else volunteers to take over
965 maintenance.<footnote>
966 The detailed procedure for gracefully orphaning a package can
967 be found in the Debian Developer's Reference
968 (see <ref id="related">).
973 <sect id="descriptions">
974 <heading>The description of a package</heading>
977 Every Debian package must have a <tt>Description</tt> control
978 field which contains a synopsis and extended description of the
979 package. Technical information about the format of the
980 <tt>Description</tt> field is in <ref id="f-Description">.
984 The description should describe the package (the program) to a
985 user (system administrator) who has never met it before so that
986 they have enough information to decide whether they want to
987 install it. This description should not just be copied verbatim
988 from the program's documentation.
992 Put important information first, both in the synopsis and
993 extended description. Sometimes only the first part of the
994 synopsis or of the description will be displayed. You can
995 assume that there will usually be a way to see the whole
996 extended description.
1000 The description should also give information about the
1001 significant dependencies and conflicts between this package
1002 and others, so that the user knows why these dependencies and
1003 conflicts have been declared.
1007 Instructions for configuring or using the package should
1008 not be included (that is what installation scripts,
1009 manual pages, info files, etc., are for). Copyright
1010 statements and other administrivia should not be included
1011 either (that is what the copyright file is for).
1014 <sect1 id="synopsis"><heading>The single line synopsis</heading>
1017 The single line synopsis should be kept brief - certainly
1018 under 80 characters.
1022 Do not include the package name in the synopsis line. The
1023 display software knows how to display this already, and you
1024 do not need to state it. Remember that in many situations
1025 the user may only see the synopsis line - make it as
1026 informative as you can.
1031 <sect1 id="extendeddesc"><heading>The extended description</heading>
1034 Do not try to continue the single line synopsis into the
1035 extended description. This will not work correctly when
1036 the full description is displayed, and makes no sense
1037 where only the summary (the single line synopsis) is
1042 The extended description should describe what the package
1043 does and how it relates to the rest of the system (in terms
1044 of, for example, which subsystem it is which part of).
1048 The description field needs to make sense to anyone, even
1049 people who have no idea about any of the things the
1050 package deals with.<footnote>
1051 The blurb that comes with a program in its
1052 announcements and/or <prgn>README</prgn> files is
1053 rarely suitable for use in a description. It is
1054 usually aimed at people who are already in the
1055 community where the package is used.
1064 <heading>Dependencies</heading>
1067 Every package must specify the dependency information
1068 about other packages that are required for the first to
1073 For example, a dependency entry must be provided for any
1074 shared libraries required by a dynamically-linked executable
1075 binary in a package.
1079 Packages are not required to declare any dependencies they
1080 have on other packages which are marked <tt>Essential</tt>
1081 (see below), and should not do so unless they depend on a
1082 particular version of that package.<footnote>
1084 Essential is needed in part to avoid unresolvable dependency
1085 loops on upgrade. If packages add unnecessary dependencies
1086 on packages in this set, the chances that there
1087 <strong>will</strong> be an unresolvable dependency loop
1088 caused by forcing these Essential packages to be configured
1089 first before they need to be is greatly increased. It also
1090 increases the chances that frontends will be unable to
1091 <strong>calculate</strong> an upgrade path, even if one
1095 Also, functionality is rarely ever removed from the
1096 Essential set, but <em>packages</em> have been removed from
1097 the Essential set when the functionality moved to a
1098 different package. So depending on these packages <em>just
1099 in case</em> they stop being essential does way more harm
1106 Sometimes, a package requires another package to be installed
1107 <em>and</em> configured before it can be installed. In this
1108 case, you must specify a <tt>Pre-Depends</tt> entry for
1113 You should not specify a <tt>Pre-Depends</tt> entry for a
1114 package before this has been discussed on the
1115 <tt>debian-devel</tt> mailing list and a consensus about
1116 doing that has been reached.
1120 The format of the package interrelationship control fields is
1121 described in <ref id="relationships">.
1125 <sect id="virtual_pkg">
1126 <heading>Virtual packages</heading>
1129 Sometimes, there are several packages which offer
1130 more-or-less the same functionality. In this case, it's
1131 useful to define a <em>virtual package</em> whose name
1132 describes that common functionality. (The virtual
1133 packages only exist logically, not physically; that's why
1134 they are called <em>virtual</em>.) The packages with this
1135 particular function will then <em>provide</em> the virtual
1136 package. Thus, any other package requiring that function
1137 can simply depend on the virtual package without having to
1138 specify all possible packages individually.
1142 All packages should use virtual package names where
1143 appropriate, and arrange to create new ones if necessary.
1144 They should not use virtual package names (except privately,
1145 amongst a cooperating group of packages) unless they have
1146 been agreed upon and appear in the list of virtual package
1147 names. (See also <ref id="virtual">)
1151 The latest version of the authoritative list of virtual
1152 package names can be found in the <tt>debian-policy</tt> package.
1153 It is also available from the Debian web mirrors at
1154 <tt><url name="/doc/packaging-manuals/virtual-package-names-list.txt"
1155 id="http://www.debian.org/doc/packaging-manuals/virtual-package-names-list.txt"></tt>.
1159 The procedure for updating the list is described in the preface
1166 <heading>Base system</heading>
1169 The <tt>base system</tt> is a minimum subset of the Debian
1170 system that is installed before everything else
1171 on a new system. Only very few packages are allowed to form
1172 part of the base system, in order to keep the required disk
1177 The base system consists of all those packages with priority
1178 <tt>required</tt> or <tt>important</tt>. Many of them will
1179 be tagged <tt>essential</tt> (see below).
1184 <heading>Essential packages</heading>
1187 Essential is defined as the minimal set of functionality that
1188 must be available and usable on the system at all times, even
1189 when packages are in an unconfigured (but unpacked) state.
1190 Packages are tagged <tt>essential</tt> for a system using the
1191 <tt>Essential</tt> control field. The format of the
1192 <tt>Essential</tt> control field is described in <ref
1197 Since these packages cannot be easily removed (one has to
1198 specify an extra <em>force option</em> to
1199 <prgn>dpkg</prgn> to do so), this flag must not be used
1200 unless absolutely necessary. A shared library package
1201 must not be tagged <tt>essential</tt>; dependencies will
1202 prevent its premature removal, and we need to be able to
1203 remove it when it has been superseded.
1207 Since dpkg will not prevent upgrading of other packages
1208 while an <tt>essential</tt> package is in an unconfigured
1209 state, all <tt>essential</tt> packages must supply all of
1210 their core functionality even when unconfigured. If the
1211 package cannot satisfy this requirement it must not be
1212 tagged as essential, and any packages depending on this
1213 package must instead have explicit dependency fields as
1218 Maintainers should take great care in adding any programs,
1219 interfaces, or functionality to <tt>essential</tt> packages.
1220 Packages may assume that functionality provided by
1221 <tt>essential</tt> packages is always available without
1222 declaring explicit dependencies, which means that removing
1223 functionality from the Essential set is very difficult and is
1224 almost never done. Any capability added to an
1225 <tt>essential</tt> package therefore creates an obligation to
1226 support that capability as part of the Essential set in
1231 You must not tag any packages <tt>essential</tt> before
1232 this has been discussed on the <tt>debian-devel</tt>
1233 mailing list and a consensus about doing that has been
1238 <sect id="maintscripts">
1239 <heading>Maintainer Scripts</heading>
1242 The package installation scripts should avoid producing
1243 output which is unnecessary for the user to see and
1244 should rely on <prgn>dpkg</prgn> to stave off boredom on
1245 the part of a user installing many packages. This means,
1246 amongst other things, using the <tt>--quiet</tt> option on
1247 <prgn>install-info</prgn>.
1251 Errors which occur during the execution of an installation
1252 script must be checked and the installation must not
1253 continue after an error.
1257 Note that in general <ref id="scripts"> applies to package
1258 maintainer scripts, too.
1262 You should not use <prgn>dpkg-divert</prgn> on a file belonging
1263 to another package without consulting the maintainer of that
1264 package first. When adding or removing diversions, package
1265 maintainer scripts must provide the <tt>--package</tt> flag
1266 to <prgn>dpkg-divert</prgn> and must not use <tt>--local</tt>.
1270 All packages which supply an instance of a common command
1271 name (or, in general, filename) should generally use
1272 <prgn>update-alternatives</prgn>, so that they may be
1273 installed together. If <prgn>update-alternatives</prgn>
1274 is not used, then each package must use
1275 <tt>Conflicts</tt> to ensure that other packages are
1276 de-installed. (In this case, it may be appropriate to
1277 specify a conflict against earlier versions of something
1278 that previously did not use
1279 <prgn>update-alternatives</prgn>; this is an exception to
1280 the usual rule that versioned conflicts should be
1284 <sect1 id="maintscriptprompt">
1285 <heading>Prompting in maintainer scripts</heading>
1287 Package maintainer scripts may prompt the user if
1288 necessary. Prompting must be done by communicating
1289 through a program, such as <prgn>debconf</prgn>, which
1290 conforms to the Debian Configuration Management
1291 Specification, version 2 or higher.
1295 Packages which are essential, or which are dependencies of
1296 essential packages, may fall back on another prompting method
1297 if no such interface is available when they are executed.
1301 The Debian Configuration Management Specification is included
1302 in the <file>debconf_specification</file> files in the
1303 <package>debian-policy</package> package.
1304 It is also available from the Debian web mirrors at
1305 <tt><url name="/doc/packaging-manuals/debconf_specification.html"
1306 id="http://www.debian.org/doc/packaging-manuals/debconf_specification.html"></tt>.
1310 Packages which use the Debian Configuration Management
1311 Specification may contain the additional control information
1312 files <file>config</file>
1313 and <file>templates</file>. <file>config</file> is an
1314 additional maintainer script used for package configuration,
1315 and <file>templates</file> contains templates used for user
1316 prompting. The <prgn>config</prgn> script might be run before
1317 the <prgn>preinst</prgn> script and before the package is
1318 unpacked or any of its dependencies or pre-dependencies are
1319 satisfied. Therefore it must work using only the tools
1320 present in <em>essential</em> packages.<footnote>
1321 <package>Debconf</package> or another tool that
1322 implements the Debian Configuration Management
1323 Specification will also be installed, and any
1324 versioned dependencies on it will be satisfied
1325 before preconfiguration begins.
1330 Packages which use the Debian Configuration Management
1331 Specification must allow for translation of their user-visible
1332 messages by using a gettext-based system such as the one
1333 provided by the <package>po-debconf</package> package.
1337 Packages should try to minimize the amount of prompting
1338 they need to do, and they should ensure that the user
1339 will only ever be asked each question once. This means
1340 that packages should try to use appropriate shared
1341 configuration files (such as <file>/etc/papersize</file> and
1342 <file>/etc/news/server</file>), and shared
1343 <package>debconf</package> variables rather than each
1344 prompting for their own list of required pieces of
1349 It also means that an upgrade should not ask the same
1350 questions again, unless the user has used
1351 <tt>dpkg --purge</tt> to remove the package's configuration.
1352 The answers to configuration questions should be stored in an
1353 appropriate place in <file>/etc</file> so that the user can
1354 modify them, and how this has been done should be
1359 If a package has a vitally important piece of
1360 information to pass to the user (such as "don't run me
1361 as I am, you must edit the following configuration files
1362 first or you risk your system emitting badly-formatted
1363 messages"), it should display this in the
1364 <prgn>config</prgn> or <prgn>postinst</prgn> script and
1365 prompt the user to hit return to acknowledge the
1366 message. Copyright messages do not count as vitally
1367 important (they belong in
1368 <file>/usr/share/doc/<var>package</var>/copyright</file>);
1369 neither do instructions on how to use a program (these
1370 should be in on-line documentation, where all the users
1375 Any necessary prompting should almost always be confined
1376 to the <prgn>config</prgn> or <prgn>postinst</prgn>
1377 script. If it is done in the <prgn>postinst</prgn>, it
1378 should be protected with a conditional so that
1379 unnecessary prompting doesn't happen if a package's
1380 installation fails and the <prgn>postinst</prgn> is
1381 called with <tt>abort-upgrade</tt>,
1382 <tt>abort-remove</tt> or <tt>abort-deconfigure</tt>.
1392 <heading>Source packages</heading>
1394 <sect id="standardsversion">
1395 <heading>Standards conformance</heading>
1398 Source packages should specify the most recent version number
1399 of this policy document with which your package complied
1400 when it was last updated.
1404 This information may be used to file bug reports
1405 automatically if your package becomes too much out of date.
1409 The version is specified in the <tt>Standards-Version</tt>
1411 The format of the <tt>Standards-Version</tt> field is
1412 described in <ref id="f-Standards-Version">.
1416 You should regularly, and especially if your package has
1417 become out of date, check for the newest Policy Manual
1418 available and update your package, if necessary. When your
1419 package complies with the new standards you should update the
1420 <tt>Standards-Version</tt> source package field and
1421 release it.<footnote>
1422 See the file <file>upgrading-checklist</file> for
1423 information about policy which has changed between
1424 different versions of this document.
1430 <sect id="pkg-relations">
1431 <heading>Package relationships</heading>
1434 Source packages should specify which binary packages they
1435 require to be installed or not to be installed in order to
1436 build correctly. For example, if building a package
1437 requires a certain compiler, then the compiler should be
1438 specified as a build-time dependency.
1442 It is not necessary to explicitly specify build-time
1443 relationships on a minimal set of packages that are always
1444 needed to compile, link and put in a Debian package a
1445 standard "Hello World!" program written in C or C++. The
1446 required packages are called <em>build-essential</em>, and
1447 an informational list can be found in
1448 <file>/usr/share/doc/build-essential/list</file> (which is
1449 contained in the <tt>build-essential</tt>
1452 <list compact="compact">
1454 This allows maintaining the list separately
1455 from the policy documents (the list does not
1456 need the kind of control that the policy
1460 Having a separate package allows one to install
1461 the build-essential packages on a machine, as
1462 well as allowing other packages such as tasks to
1463 require installation of the build-essential
1464 packages using the depends relation.
1467 The separate package allows bug reports against
1468 the list to be categorized separately from
1469 the policy management process in the BTS.
1476 When specifying the set of build-time dependencies, one
1477 should list only those packages explicitly required by the
1478 build. It is not necessary to list packages which are
1479 required merely because some other package in the list of
1480 build-time dependencies depends on them.<footnote>
1481 The reason for this is that dependencies change, and
1482 you should list all those packages, and <em>only</em>
1483 those packages that <em>you</em> need directly. What
1484 others need is their business. For example, if you
1485 only link against <file>libimlib</file>, you will need to
1486 build-depend on <package>libimlib2-dev</package> but
1487 not against any <tt>libjpeg*</tt> packages, even
1488 though <tt>libimlib2-dev</tt> currently depends on
1489 them: installation of <package>libimlib2-dev</package>
1490 will automatically ensure that all of its run-time
1491 dependencies are satisfied.
1496 If build-time dependencies are specified, it must be
1497 possible to build the package and produce working binaries
1498 on a system with only essential and build-essential
1499 packages installed and also those required to satisfy the
1500 build-time relationships (including any implied
1501 relationships). In particular, this means that version
1502 clauses should be used rigorously in build-time
1503 relationships so that one cannot produce bad or
1504 inconsistently configured packages when the relationships
1505 are properly satisfied.
1509 <ref id="relationships"> explains the technical details.
1514 <heading>Changes to the upstream sources</heading>
1517 If changes to the source code are made that are not
1518 specific to the needs of the Debian system, they should be
1519 sent to the upstream authors in whatever form they prefer
1520 so as to be included in the upstream version of the
1525 If you need to configure the package differently for
1526 Debian or for Linux, and the upstream source doesn't
1527 provide a way to do so, you should add such configuration
1528 facilities (for example, a new <prgn>autoconf</prgn> test
1529 or <tt>#define</tt>) and send the patch to the upstream
1530 authors, with the default set to the way they originally
1531 had it. You can then easily override the default in your
1532 <file>debian/rules</file> or wherever is appropriate.
1536 You should make sure that the <prgn>configure</prgn> utility
1537 detects the correct architecture specification string
1538 (refer to <ref id="arch-spec"> for details).
1542 If you need to edit a <prgn>Makefile</prgn> where GNU-style
1543 <prgn>configure</prgn> scripts are used, you should edit the
1544 <file>.in</file> files rather than editing the
1545 <prgn>Makefile</prgn> directly. This allows the user to
1546 reconfigure the package if necessary. You should
1547 <em>not</em> configure the package and edit the generated
1548 <prgn>Makefile</prgn>! This makes it impossible for someone
1549 else to later reconfigure the package without losing the
1555 <sect id="dpkgchangelog">
1556 <heading>Debian changelog: <file>debian/changelog</file></heading>
1559 Changes in the Debian version of the package should be
1560 briefly explained in the Debian changelog file
1561 <file>debian/changelog</file>.<footnote>
1563 Mistakes in changelogs are usually best rectified by
1564 making a new changelog entry rather than "rewriting
1565 history" by editing old changelog entries.
1568 This includes modifications
1569 made in the Debian package compared to the upstream one
1570 as well as other changes and updates to the package.
1572 Although there is nothing stopping an author who is also
1573 the Debian maintainer from using this changelog for all
1574 their changes, it will have to be renamed if the Debian
1575 and upstream maintainers become different people. In such
1576 a case, however, it might be better to maintain the package
1577 as a non-native package.
1582 The format of the <file>debian/changelog</file> allows the
1583 package building tools to discover which version of the package
1584 is being built and find out other release-specific information.
1588 That format is a series of entries like this:
1590 <example compact="compact">
1591 <var>package</var> (<var>version</var>) <var>distribution(s)</var>; urgency=<var>urgency</var>
1593 [optional blank line(s), stripped]
1595 * <var>change details</var>
1596 <var>more change details</var>
1598 [blank line(s), included in output of dpkg-parsechangelog]
1600 * <var>even more change details</var>
1602 [optional blank line(s), stripped]
1604 -- <var>maintainer name</var> <<var>email address</var>><var>[two spaces]</var> <var>date</var>
1609 <var>package</var> and <var>version</var> are the source
1610 package name and version number.
1614 <var>distribution(s)</var> lists the distributions where
1615 this version should be installed when it is uploaded - it
1616 is copied to the <tt>Distribution</tt> field in the
1617 <file>.changes</file> file. See <ref id="f-Distribution">.
1621 <var>urgency</var> is the value for the <tt>Urgency</tt>
1622 field in the <file>.changes</file> file for the upload
1623 (see <ref id="f-Urgency">). It is not possible to specify
1624 an urgency containing commas; commas are used to separate
1625 <tt><var>keyword</var>=<var>value</var></tt> settings in the
1626 <prgn>dpkg</prgn> changelog format (though there is
1627 currently only one useful <var>keyword</var>,
1632 The change details may in fact be any series of lines
1633 starting with at least two spaces, but conventionally each
1634 change starts with an asterisk and a separating space and
1635 continuation lines are indented so as to bring them in
1636 line with the start of the text above. Blank lines may be
1637 used here to separate groups of changes, if desired.
1641 If this upload resolves bugs recorded in the Bug Tracking
1642 System (BTS), they may be automatically closed on the
1643 inclusion of this package into the Debian archive by
1644 including the string: <tt>closes: Bug#<var>nnnnn</var></tt>
1645 in the change details.<footnote>
1646 To be precise, the string should match the following
1647 Perl regular expression:
1649 /closes:\s*(?:bug)?\#?\s?\d+(?:,\s*(?:bug)?\#?\s?\d+)*/i
1651 Then all of the bug numbers listed will be closed by the
1652 archive maintenance script (<prgn>katie</prgn>) using the
1653 <var>version</var> of the changelog entry.
1655 This information is conveyed via the <tt>Closes</tt> field
1656 in the <tt>.changes</tt> file (see <ref id="f-Closes">).
1660 The maintainer name and email address used in the changelog
1661 should be the details of the person uploading <em>this</em>
1662 version. They are <em>not</em> necessarily those of the
1663 usual package maintainer.<footnote>
1664 If the developer uploading the package is not one of the usual
1665 maintainers of the package (as listed in
1666 the <qref id="f-Maintainer"><tt>Maintainer</tt></qref>
1667 or <qref id="f-Uploaders"><tt>Uploaders</tt></qref> control
1668 fields of the package), the first line of the changelog is
1669 conventionally used to explain why a non-maintainer is
1670 uploading the package. The Debian Developer's Reference
1671 (see <ref id="related">) documents the conventions
1673 The information here will be copied to the <tt>Changed-By</tt>
1674 field in the <tt>.changes</tt> file
1675 (see <ref id="f-Changed-By">), and then later used to send an
1676 acknowledgement when the upload has been installed.
1680 The <var>date</var> has the following format<footnote>
1681 This is the same as the format generated by <tt>date
1683 </footnote> (compatible and with the same semantics of
1684 RFC 2822 and RFC 5322):
1685 <example>day-of-week, dd month yyyy hh:mm:ss +zzzz</example>
1687 <list compact="compact">
1689 day-of week is one of: Mon, Tue, Wed, Thu, Fri, Sat, Sun
1692 dd is a one- or two-digit day of the month (01-31)
1695 month is one of: Jan, Feb, Mar, Apr, May, Jun, Jul, Aug,
1698 <item>yyyy is the four-digit year (e.g. 2010)</item>
1699 <item>hh is the two-digit hour (00-23)</item>
1700 <item>mm is the two-digit minutes (00-59)</item>
1701 <item>ss is the two-digit seconds (00-60)</item>
1703 +zzzz or -zzzz is the the time zone offset from Coordinated
1704 Universal Time (UTC). "+" indicates that the time is ahead
1705 of (i.e., east of) UTC and "-" indicates that the time is
1706 behind (i.e., west of) UTC. The first two digits indicate
1707 the hour difference from UTC and the last two digits
1708 indicate the number of additional minutes difference from
1709 UTC. The last two digits must be in the range 00-59.
1715 The first "title" line with the package name must start
1716 at the left hand margin. The "trailer" line with the
1717 maintainer and date details must be preceded by exactly
1718 one space. The maintainer details and the date must be
1719 separated by exactly two spaces.
1723 The entire changelog must be encoded in UTF-8.
1727 For more information on placement of the changelog files
1728 within binary packages, please see <ref id="changelogs">.
1732 <sect id="dpkgcopyright">
1733 <heading>Copyright: <file>debian/copyright</file></heading>
1735 Every package must be accompanied by a verbatim copy of its
1736 copyright information and distribution license in the file
1737 <file>/usr/share/doc/<var>package</var>/copyright</file>
1738 (see <ref id="copyrightfile"> for further details). Also see
1739 <ref id="pkgcopyright"> for further considerations related
1740 to copyrights for packages.
1744 <heading>Error trapping in makefiles</heading>
1747 When <prgn>make</prgn> invokes a command in a makefile
1748 (including your package's upstream makefiles and
1749 <file>debian/rules</file>), it does so using <prgn>sh</prgn>. This
1750 means that <prgn>sh</prgn>'s usual bad error handling
1751 properties apply: if you include a miniature script as one
1752 of the commands in your makefile you'll find that if you
1753 don't do anything about it then errors are not detected
1754 and <prgn>make</prgn> will blithely continue after
1759 Every time you put more than one shell command (this
1760 includes using a loop) in a makefile command you
1761 must make sure that errors are trapped. For
1762 simple compound commands, such as changing directory and
1763 then running a program, using <tt>&&</tt> rather
1764 than semicolon as a command separator is sufficient. For
1765 more complex commands including most loops and
1766 conditionals you should include a separate <tt>set -e</tt>
1767 command at the start of every makefile command that's
1768 actually one of these miniature shell scripts.
1772 <sect id="timestamps">
1773 <heading>Time Stamps</heading>
1775 Maintainers should preserve the modification times of the
1776 upstream source files in a package, as far as is reasonably
1778 The rationale is that there is some information conveyed
1779 by knowing the age of the file, for example, you could
1780 recognize that some documentation is very old by looking
1781 at the modification time, so it would be nice if the
1782 modification time of the upstream source would be
1788 <sect id="restrictions">
1789 <heading>Restrictions on objects in source packages</heading>
1792 The source package may not contain any hard links<footnote>
1794 This is not currently detected when building source
1795 packages, but only when extracting
1799 Hard links may be permitted at some point in the
1800 future, but would require a fair amount of
1803 </footnote>, device special files, sockets or setuid or
1804 setgid files.<footnote>
1805 Setgid directories are allowed.
1810 <sect id="debianrules">
1811 <heading>Main building script: <file>debian/rules</file></heading>
1814 This file must be an executable makefile, and contains the
1815 package-specific recipes for compiling the package and
1816 building binary package(s) from the source.
1820 It must start with the line <tt>#!/usr/bin/make -f</tt>,
1821 so that it can be invoked by saying its name rather than
1822 invoking <prgn>make</prgn> explicitly. That is, invoking
1823 either of <tt>make -f debian/rules <em>args...</em></tt>
1824 or <tt>./debian/rules <em>args...</em></tt> must result in
1829 The following targets are required and must be implemented
1830 by <file>debian/rules</file>: <tt>clean</tt>, <tt>binary</tt>,
1831 <tt>binary-arch</tt>, <tt>binary-indep</tt>, and <tt>build</tt>.
1832 These are the targets called by <prgn>dpkg-buildpackage</prgn>.
1836 Since an interactive <file>debian/rules</file> script makes it
1837 impossible to auto-compile that package and also makes it hard
1838 for other people to reproduce the same binary package, all
1839 required targets must be non-interactive. It also follows that
1840 any target that these targets depend on must also be
1845 The targets are as follows:
1847 <tag><tt>build</tt> (required)</tag>
1850 The <tt>build</tt> target should perform all the
1851 configuration and compilation of the package.
1852 If a package has an interactive pre-build
1853 configuration routine, the Debian source package
1854 must either be built after this has taken place (so
1855 that the binary package can be built without rerunning
1856 the configuration) or the configuration routine
1857 modified to become non-interactive. (The latter is
1858 preferable if there are architecture-specific features
1859 detected by the configuration routine.)
1863 For some packages, notably ones where the same
1864 source tree is compiled in different ways to produce
1865 two binary packages, the <tt>build</tt> target
1866 does not make much sense. For these packages it is
1867 good enough to provide two (or more) targets
1868 (<tt>build-a</tt> and <tt>build-b</tt> or whatever)
1869 for each of the ways of building the package, and a
1870 <tt>build</tt> target that does nothing. The
1871 <tt>binary</tt> target will have to build the
1872 package in each of the possible ways and make the
1873 binary package out of each.
1877 The <tt>build</tt> target must not do anything
1878 that might require root privilege.
1882 The <tt>build</tt> target may need to run the
1883 <tt>clean</tt> target first - see below.
1887 When a package has a configuration and build routine
1888 which takes a long time, or when the makefiles are
1889 poorly designed, or when <tt>build</tt> needs to
1890 run <tt>clean</tt> first, it is a good idea to
1891 <tt>touch build</tt> when the build process is
1892 complete. This will ensure that if <tt>debian/rules
1893 build</tt> is run again it will not rebuild the whole
1895 Another common way to do this is for <tt>build</tt>
1896 to depend on <prgn>build-stamp</prgn> and to do
1897 nothing else, and for the <prgn>build-stamp</prgn>
1898 target to do the building and to <tt>touch
1899 build-stamp</tt> on completion. This is
1900 especially useful if the build routine creates a
1901 file or directory called <tt>build</tt>; in such a
1902 case, <tt>build</tt> will need to be listed as
1903 a phony target (i.e., as a dependency of the
1904 <tt>.PHONY</tt> target). See the documentation of
1905 <prgn>make</prgn> for more information on phony
1911 <tag><tt>build-arch</tt> (optional),
1912 <tt>build-indep</tt> (optional)
1916 A package may also provide both of the targets
1917 <tt>build-arch</tt> and <tt>build-indep</tt>.
1918 The <tt>build-arch</tt> target, if provided, should
1919 perform all the configuration and compilation required for
1920 producing all architecture-dependant binary packages
1921 (those packages for which the body of the
1922 <tt>Architecture</tt> field in <tt>debian/control</tt> is
1923 not <tt>all</tt>). Similarly, the <tt>build-indep</tt>
1924 target, if provided, should perform all the configuration
1925 and compilation required for producing all
1926 architecture-independent binary packages (those packages
1927 for which the body of the <tt>Architecture</tt> field
1928 in <tt>debian/control</tt> is <tt>all</tt>).
1929 The <tt>build</tt> target should depend on those of the
1930 targets <tt>build-arch</tt> and <tt>build-indep</tt> that
1931 are provided in the rules file.<footnote>
1932 The intent of this split is so that binary-only builds
1933 need not install the dependencies required for
1934 the <tt>build-indep</tt> target. However, this is not
1935 yet used in practice since <tt>dpkg-buildpackage
1936 -B</tt>, and therefore the autobuilders,
1937 invoke <tt>build</tt> rather than <tt>build-arch</tt>
1938 due to the difficulties in determining whether the
1939 optional <tt>build-arch</tt> target exists.
1944 If one or both of the targets <tt>build-arch</tt> and
1945 <tt>build-indep</tt> are not provided, then invoking
1946 <file>debian/rules</file> with one of the not-provided
1947 targets as arguments should produce a exit status code
1948 of 2. Usually this is provided automatically by make
1949 if the target is missing.
1953 The <tt>build-arch</tt> and <tt>build-indep</tt> targets
1954 must not do anything that might require root privilege.
1958 <tag><tt>binary</tt> (required), <tt>binary-arch</tt>
1959 (required), <tt>binary-indep</tt> (required)
1963 The <tt>binary</tt> target must be all that is
1964 necessary for the user to build the binary package(s)
1965 produced from this source package. It is
1966 split into two parts: <prgn>binary-arch</prgn> builds
1967 the binary packages which are specific to a particular
1968 architecture, and <tt>binary-indep</tt> builds
1969 those which are not.
1972 <tt>binary</tt> may be (and commonly is) a target with
1973 no commands which simply depends on
1974 <tt>binary-arch</tt> and <tt>binary-indep</tt>.
1977 Both <tt>binary-*</tt> targets should depend on the
1978 <tt>build</tt> target, or on the appropriate
1979 <tt>build-arch</tt> or <tt>build-indep</tt> target, if
1980 provided, so that the package is built if it has not
1981 been already. It should then create the relevant
1982 binary package(s), using <prgn>dpkg-gencontrol</prgn> to
1983 make their control files and <prgn>dpkg-deb</prgn> to
1984 build them and place them in the parent of the top
1989 Both the <tt>binary-arch</tt> and
1990 <tt>binary-indep</tt> targets <em>must</em> exist.
1991 If one of them has nothing to do (which will always be
1992 the case if the source generates only a single binary
1993 package, whether architecture-dependent or not), it
1994 must still exist and must always succeed.
1998 The <tt>binary</tt> targets must be invoked as
2000 The <prgn>fakeroot</prgn> package often allows one
2001 to build a package correctly even without being
2007 <tag><tt>clean</tt> (required)</tag>
2010 This must undo any effects that the <tt>build</tt>
2011 and <tt>binary</tt> targets may have had, except
2012 that it should leave alone any output files created in
2013 the parent directory by a run of a <tt>binary</tt>
2018 If a <tt>build</tt> file is touched at the end of
2019 the <tt>build</tt> target, as suggested above, it
2020 should be removed as the first action that
2021 <tt>clean</tt> performs, so that running
2022 <tt>build</tt> again after an interrupted
2023 <tt>clean</tt> doesn't think that everything is
2028 The <tt>clean</tt> target may need to be
2029 invoked as root if <tt>binary</tt> has been
2030 invoked since the last <tt>clean</tt>, or if
2031 <tt>build</tt> has been invoked as root (since
2032 <tt>build</tt> may create directories, for
2037 <tag><tt>get-orig-source</tt> (optional)</tag>
2040 This target fetches the most recent version of the
2041 original source package from a canonical archive site
2042 (via FTP or WWW, for example), does any necessary
2043 rearrangement to turn it into the original source
2044 tar file format described below, and leaves it in the
2049 This target may be invoked in any directory, and
2050 should take care to clean up any temporary files it
2055 This target is optional, but providing it if
2056 possible is a good idea.
2060 <tag><tt>patch</tt> (optional)</tag>
2063 This target performs whatever additional actions are
2064 required to make the source ready for editing (unpacking
2065 additional upstream archives, applying patches, etc.).
2066 It is recommended to be implemented for any package where
2067 <tt>dpkg-source -x</tt> does not result in source ready
2068 for additional modification. See
2069 <ref id="readmesource">.
2075 The <tt>build</tt>, <tt>binary</tt> and
2076 <tt>clean</tt> targets must be invoked with the current
2077 directory being the package's top-level directory.
2082 Additional targets may exist in <file>debian/rules</file>,
2083 either as published or undocumented interfaces or for the
2084 package's internal use.
2088 The architectures we build on and build for are determined
2089 by <prgn>make</prgn> variables using the
2090 utility <qref id="pkg-dpkg-architecture"><prgn>dpkg-architecture</prgn></qref>.
2091 You can determine the Debian architecture and the GNU style
2092 architecture specification string for the build architecture as
2093 well as for the host architecture. The build architecture is
2094 the architecture on which <file>debian/rules</file> is run and
2095 the package build is performed. The host architecture is the
2096 architecture on which the resulting package will be installed
2097 and run. These are normally the same, but may be different in
2098 the case of cross-compilation (building packages for one
2099 architecture on machines of a different architecture).
2103 Here is a list of supported <prgn>make</prgn> variables:
2104 <list compact="compact">
2106 <tt>DEB_*_ARCH</tt> (the Debian architecture)
2109 <tt>DEB_*_ARCH_CPU</tt> (the Debian CPU name)
2112 <tt>DEB_*_ARCH_OS</tt> (the Debian System name)
2115 <tt>DEB_*_GNU_TYPE</tt> (the GNU style architecture
2116 specification string)
2119 <tt>DEB_*_GNU_CPU</tt> (the CPU part of
2120 <tt>DEB_*_GNU_TYPE</tt>)
2123 <tt>DEB_*_GNU_SYSTEM</tt> (the System part of
2124 <tt>DEB_*_GNU_TYPE</tt>)
2126 where <tt>*</tt> is either <tt>BUILD</tt> for specification of
2127 the build architecture or <tt>HOST</tt> for specification of the
2132 Backward compatibility can be provided in the rules file
2133 by setting the needed variables to suitable default
2134 values; please refer to the documentation of
2135 <prgn>dpkg-architecture</prgn> for details.
2139 It is important to understand that the <tt>DEB_*_ARCH</tt>
2140 string only determines which Debian architecture we are
2141 building on or for. It should not be used to get the CPU
2142 or system information; the <tt>DEB_*_ARCH_CPU</tt> and
2143 <tt>DEB_*_ARCH_OS</tt> variables should be used for that.
2144 GNU style variables should generally only be used with upstream
2148 <sect1 id="debianrules-options">
2149 <heading><file>debian/rules</file> and
2150 <tt>DEB_BUILD_OPTIONS</tt></heading>
2153 Supporting the standardized environment variable
2154 <tt>DEB_BUILD_OPTIONS</tt> is recommended. This variable can
2155 contain several flags to change how a package is compiled and
2156 built. Each flag must be in the form <var>flag</var> or
2157 <var>flag</var>=<var>options</var>. If multiple flags are
2158 given, they must be separated by whitespace.<footnote>
2159 Some packages support any delimiter, but whitespace is the
2160 easiest to parse inside a makefile and avoids ambiguity with
2161 flag values that contain commas.
2163 <var>flag</var> must start with a lowercase letter
2164 (<tt>a-z</tt>) and consist only of lowercase letters,
2165 numbers (<tt>0-9</tt>), and the characters
2166 <tt>-</tt> and <tt>_</tt> (hyphen and underscore).
2167 <var>options</var> must not contain whitespace. The same
2168 tag should not be given multiple times with conflicting
2169 values. Package maintainers may assume that
2170 <tt>DEB_BUILD_OPTIONS</tt> will not contain conflicting tags.
2174 The meaning of the following tags has been standardized:
2178 This tag says to not run any build-time test suite
2179 provided by the package.
2183 The presence of this tag means that the package should
2184 be compiled with a minimum of optimization. For C
2185 programs, it is best to add <tt>-O0</tt> to
2186 <tt>CFLAGS</tt> (although this is usually the default).
2187 Some programs might fail to build or run at this level
2188 of optimization; it may be necessary to use
2189 <tt>-O1</tt>, for example.
2193 This tag means that the debugging symbols should not be
2194 stripped from the binary during installation, so that
2195 debugging information may be included in the package.
2197 <tag>parallel=n</tag>
2199 This tag means that the package should be built using up
2200 to <tt>n</tt> parallel processes if the package build
2201 system supports this.<footnote>
2202 Packages built with <tt>make</tt> can often implement
2203 this by passing the <tt>-j</tt><var>n</var> option to
2206 If the package build system does not support parallel
2207 builds, this string must be ignored. If the package
2208 build system only supports a lower level of concurrency
2209 than <var>n</var>, the package should be built using as
2210 many parallel processes as the package build system
2211 supports. It is up to the package maintainer to decide
2212 whether the package build times are long enough and the
2213 package build system is robust enough to make supporting
2214 parallel builds worthwhile.
2220 Unknown flags must be ignored by <file>debian/rules</file>.
2224 The following makefile snippet is an example of how one may
2225 implement the build options; you will probably have to
2226 massage this example in order to make it work for your
2228 <example compact="compact">
2231 INSTALL_FILE = $(INSTALL) -p -o root -g root -m 644
2232 INSTALL_PROGRAM = $(INSTALL) -p -o root -g root -m 755
2233 INSTALL_SCRIPT = $(INSTALL) -p -o root -g root -m 755
2234 INSTALL_DIR = $(INSTALL) -p -d -o root -g root -m 755
2236 ifneq (,$(filter noopt,$(DEB_BUILD_OPTIONS)))
2241 ifeq (,$(filter nostrip,$(DEB_BUILD_OPTIONS)))
2242 INSTALL_PROGRAM += -s
2244 ifneq (,$(filter parallel=%,$(DEB_BUILD_OPTIONS)))
2245 NUMJOBS = $(patsubst parallel=%,%,$(filter parallel=%,$(DEB_BUILD_OPTIONS)))
2246 MAKEFLAGS += -j$(NUMJOBS)
2251 ifeq (,$(filter nocheck,$(DEB_BUILD_OPTIONS)))
2252 # Code to run the package test suite.
2259 <!-- FIXME: section pkg-srcsubstvars is the same as substvars -->
2260 <sect id="substvars">
2261 <heading>Variable substitutions: <file>debian/substvars</file></heading>
2264 When <prgn>dpkg-gencontrol</prgn>
2265 generates <qref id="binarycontrolfiles">binary package control
2266 files</qref> (<file>DEBIAN/control</file>), it performs variable
2267 substitutions on its output just before writing it. Variable
2268 substitutions have the form <tt>${<var>variable</var>}</tt>.
2269 The optional file <file>debian/substvars</file> contains
2270 variable substitutions to be used; variables can also be set
2271 directly from <file>debian/rules</file> using the <tt>-V</tt>
2272 option to the source packaging commands, and certain predefined
2273 variables are also available.
2277 The <file>debian/substvars</file> file is usually generated and
2278 modified dynamically by <file>debian/rules</file> targets, in
2279 which case it must be removed by the <tt>clean</tt> target.
2283 See <manref name="deb-substvars" section="5"> for full
2284 details about source variable substitutions, including the
2285 format of <file>debian/substvars</file>.</p>
2288 <sect id="debianwatch">
2289 <heading>Optional upstream source location: <file>debian/watch</file></heading>
2292 This is an optional, recommended configuration file for the
2293 <tt>uscan</tt> utility which defines how to automatically scan
2294 ftp or http sites for newly available updates of the
2295 package. This is used
2296 by <url id="http://dehs.alioth.debian.org/"> and other Debian QA
2297 tools to help with quality control and maintenance of the
2298 distribution as a whole.
2303 <sect id="debianfiles">
2304 <heading>Generated files list: <file>debian/files</file></heading>
2307 This file is not a permanent part of the source tree; it
2308 is used while building packages to record which files are
2309 being generated. <prgn>dpkg-genchanges</prgn> uses it
2310 when it generates a <file>.changes</file> file.
2314 It should not exist in a shipped source package, and so it
2315 (and any backup files or temporary files such as
2316 <file>files.new</file><footnote>
2317 <file>files.new</file> is used as a temporary file by
2318 <prgn>dpkg-gencontrol</prgn> and
2319 <prgn>dpkg-distaddfile</prgn> - they write a new
2320 version of <tt>files</tt> here before renaming it,
2321 to avoid leaving a corrupted copy if an error
2323 </footnote>) should be removed by the
2324 <tt>clean</tt> target. It may also be wise to
2325 ensure a fresh start by emptying or removing it at the
2326 start of the <tt>binary</tt> target.
2330 When <prgn>dpkg-gencontrol</prgn> is run for a binary
2331 package, it adds an entry to <file>debian/files</file> for the
2332 <file>.deb</file> file that will be created when <tt>dpkg-deb
2333 --build</tt> is run for that binary package. So for most
2334 packages all that needs to be done with this file is to
2335 delete it in the <tt>clean</tt> target.
2339 If a package upload includes files besides the source
2340 package and any binary packages whose control files were
2341 made with <prgn>dpkg-gencontrol</prgn> then they should be
2342 placed in the parent of the package's top-level directory
2343 and <prgn>dpkg-distaddfile</prgn> should be called to add
2344 the file to the list in <file>debian/files</file>.</p>
2347 <sect id="embeddedfiles">
2348 <heading>Convenience copies of code</heading>
2351 Some software packages include in their distribution convenience
2352 copies of code from other software packages, generally so that
2353 users compiling from source don't have to download multiple
2354 packages. Debian packages should not make use of these
2355 convenience copies unless the included package is explicitly
2356 intended to be used in this way.<footnote>
2357 For example, parts of the GNU build system work like this.
2359 If the included code is already in the Debian archive in the
2360 form of a library, the Debian packaging should ensure that
2361 binary packages reference the libraries already in Debian and
2362 the convenience copy is not used. If the included code is not
2363 already in Debian, it should be packaged separately as a
2364 prerequisite if possible.
2366 Having multiple copies of the same code in Debian is
2367 inefficient, often creates either static linking or shared
2368 library conflicts, and, most importantly, increases the
2369 difficulty of handling security vulnerabilities in the
2375 <sect id="readmesource">
2376 <heading>Source package handling:
2377 <file>debian/README.source</file></heading>
2380 If running <prgn>dpkg-source -x</prgn> on a source package
2381 doesn't produce the source of the package, ready for editing,
2382 and allow one to make changes and run
2383 <prgn>dpkg-buildpackage</prgn> to produce a modified package
2384 without taking any additional steps, creating a
2385 <file>debian/README.source</file> documentation file is
2386 recommended. This file should explain how to do all of the
2389 <item>Generate the fully patched source, in a form ready for
2390 editing, that would be built to create Debian
2391 packages. Doing this with a <tt>patch</tt> target in
2392 <file>debian/rules</file> is recommended; see
2393 <ref id="debianrules">.</item>
2394 <item>Modify the source and save those modifications so that
2395 they will be applied when building the package.</item>
2396 <item>Remove source modifications that are currently being
2397 applied when building the package.</item>
2398 <item>Optionally, document what steps are necessary to
2399 upgrade the Debian source package to a new upstream version,
2400 if applicable.</item>
2402 This explanation should include specific commands and mention
2403 any additional required Debian packages. It should not assume
2404 familiarity with any specific Debian packaging system or patch
2409 This explanation may refer to a documentation file installed by
2410 one of the package's build dependencies provided that the
2411 referenced documentation clearly explains these tasks and is not
2412 a general reference manual.
2416 <file>debian/README.source</file> may also include any other
2417 information that would be helpful to someone modifying the
2418 source package. Even if the package doesn't fit the above
2419 description, maintainers are encouraged to document in a
2420 <file>debian/README.source</file> file any source package with a
2421 particularly complex or unintuitive source layout or build
2422 system (for example, a package that builds the same source
2423 multiple times to generate different binary packages).
2429 <chapt id="controlfields">
2430 <heading>Control files and their fields</heading>
2433 The package management system manipulates data represented in
2434 a common format, known as <em>control data</em>, stored in
2435 <em>control files</em>.
2436 Control files are used for source packages, binary packages and
2437 the <file>.changes</file> files which control the installation
2438 of uploaded files<footnote>
2439 <prgn>dpkg</prgn>'s internal databases are in a similar
2444 <sect id="controlsyntax">
2445 <heading>Syntax of control files</heading>
2448 A control file consists of one or more paragraphs of
2450 The paragraphs are also sometimes referred to as stanzas.
2452 The paragraphs are separated by blank lines. Some control
2453 files allow only one paragraph; others allow several, in
2454 which case each paragraph usually refers to a different
2455 package. (For example, in source packages, the first
2456 paragraph refers to the source package, and later paragraphs
2457 refer to binary packages generated from the source.)
2461 Each paragraph consists of a series of data fields; each
2462 field consists of the field name, followed by a colon and
2463 then the data/value associated with that field. It ends at
2464 the end of the (logical) line. Horizontal whitespace
2465 (spaces and tabs) may occur immediately before or after the
2466 value and is ignored there; it is conventional to put a
2467 single space after the colon. For example, a field might
2469 <example compact="compact">
2472 the field name is <tt>Package</tt> and the field value
2477 A paragraph must not contain more than one instance of a
2478 particular field name.
2482 Many fields' values may span several lines; in this case
2483 each continuation line must start with a space or a tab.
2484 Any trailing spaces or tabs at the end of individual
2485 lines of a field value are ignored.
2489 In fields where it is specified that lines may not wrap,
2490 only a single line of data is allowed and whitespace is not
2491 significant in a field body. Whitespace must not appear
2492 inside names (of packages, architectures, files or anything
2493 else) or version numbers, or between the characters of
2494 multi-character version relationships.
2498 Field names are not case-sensitive, but it is usual to
2499 capitalize the field names using mixed case as shown below.
2500 Field values are case-sensitive unless the description of the
2501 field says otherwise.
2505 Blank lines, or lines consisting only of spaces and tabs,
2506 are not allowed within field values or between fields - that
2507 would mean a new paragraph.
2511 All control files must be encoded in UTF-8.
2515 <sect id="sourcecontrolfiles">
2516 <heading>Source package control files -- <file>debian/control</file></heading>
2519 The <file>debian/control</file> file contains the most vital
2520 (and version-independent) information about the source package
2521 and about the binary packages it creates.
2525 The first paragraph of the control file contains information about
2526 the source package in general. The subsequent sets each describe a
2527 binary package that the source tree builds.
2531 The fields in the general paragraph (the first one, for the source
2534 <list compact="compact">
2535 <item><qref id="f-Source"><tt>Source</tt></qref> (mandatory)</item>
2536 <item><qref id="f-Maintainer"><tt>Maintainer</tt></qref> (mandatory)</item>
2537 <item><qref id="f-Uploaders"><tt>Uploaders</tt></qref></item>
2538 <item><qref id="f-DM-Upload-Allowed"<tt>DM-Upload-Allowed</tt></qref></item>
2539 <item><qref id="f-Section"><tt>Section</tt></qref> (recommended)</item>
2540 <item><qref id="f-Priority"><tt>Priority</tt></qref> (recommended)</item>
2541 <item><qref id="sourcebinarydeps"><tt>Build-Depends</tt> et al</qref></item>
2542 <item><qref id="f-Standards-Version"><tt>Standards-Version</tt></qref> (recommended)</item>
2543 <item><qref id="f-Homepage"><tt>Homepage</tt></qref></item>
2548 The fields in the binary package paragraphs are:
2550 <list compact="compact">
2551 <item><qref id="f-Package"><tt>Package</tt></qref> (mandatory)</item>
2552 <item><qref id="f-Architecture"><tt>Architecture</tt></qref> (mandatory)</item>
2553 <item><qref id="f-Section"><tt>Section</tt></qref> (recommended)</item>
2554 <item><qref id="f-Priority"><tt>Priority</tt></qref> (recommended)</item>
2555 <item><qref id="f-Essential"><tt>Essential</tt></qref></item>
2556 <item><qref id="binarydeps"><tt>Depends</tt> et al</qref></item>
2557 <item><qref id="f-Description"><tt>Description</tt></qref> (mandatory)</item>
2558 <item><qref id="f-Homepage"><tt>Homepage</tt></qref></item>
2563 The syntax and semantics of the fields are described below.
2567 These fields are used by <prgn>dpkg-gencontrol</prgn> to
2568 generate control files for binary packages (see below), by
2569 <prgn>dpkg-genchanges</prgn> to generate the
2570 <file>.changes</file> file to accompany the upload, and by
2571 <prgn>dpkg-source</prgn> when it creates the
2572 <file>.dsc</file> source control file as part of a source
2573 archive. Many fields are permitted to span multiple lines in
2574 <file>debian/control</file> but not in any other control
2575 file. These tools are responsible for removing the line
2576 breaks from such fields when using fields from
2577 <file>debian/control</file> to generate other control files.
2581 The fields here may contain variable references - their
2582 values will be substituted by <prgn>dpkg-gencontrol</prgn>,
2583 <prgn>dpkg-genchanges</prgn> or <prgn>dpkg-source</prgn>
2584 when they generate output control files.
2585 See <ref id="substvars"> for details.
2589 In addition to the control file syntax described <qref
2590 id="controlsyntax">above</qref>, this file may also contain
2591 comment lines starting with <tt>#</tt> without any preceding
2592 whitespace. All such lines are ignored, even in the middle of
2593 continuation lines for a multiline field, and do not end a
2599 <sect id="binarycontrolfiles">
2600 <heading>Binary package control files -- <file>DEBIAN/control</file></heading>
2603 The <file>DEBIAN/control</file> file contains the most vital
2604 (and version-dependent) information about a binary package. It
2605 consists of a single paragraph.
2609 The fields in this file are:
2611 <list compact="compact">
2612 <item><qref id="f-Package"><tt>Package</tt></qref> (mandatory)</item>
2613 <item><qref id="f-Source"><tt>Source</tt></qref></item>
2614 <item><qref id="f-Version"><tt>Version</tt></qref> (mandatory)</item>
2615 <item><qref id="f-Section"><tt>Section</tt></qref> (recommended)</item>
2616 <item><qref id="f-Priority"><tt>Priority</tt></qref> (recommended)</item>
2617 <item><qref id="f-Architecture"><tt>Architecture</tt></qref> (mandatory)</item>
2618 <item><qref id="f-Essential"><tt>Essential</tt></qref></item>
2619 <item><qref id="binarydeps"><tt>Depends</tt> et al</qref></item>
2620 <item><qref id="f-Installed-Size"><tt>Installed-Size</tt></qref></item>
2621 <item><qref id="f-Maintainer"><tt>Maintainer</tt></qref> (mandatory)</item>
2622 <item><qref id="f-Description"><tt>Description</tt></qref> (mandatory)</item>
2623 <item><qref id="f-Homepage"><tt>Homepage</tt></qref></item>
2628 <sect id="debiansourcecontrolfiles">
2629 <heading>Debian source control files -- <tt>.dsc</tt></heading>
2632 This file consists of a single paragraph, possibly surrounded by
2633 a PGP signature. The fields of that paragraph are listed below.
2634 Their syntax is described above, in <ref id="pkg-controlfields">.
2636 <list compact="compact">
2637 <item><qref id="f-Format"><tt>Format</tt></qref> (mandatory)</item>
2638 <item><qref id="f-Source"><tt>Source</tt></qref> (mandatory)</item>
2639 <item><qref id="f-Binary"><tt>Binary</tt></qref></item>
2640 <item><qref id="f-Architecture"><tt>Architecture</tt></qref></item>
2641 <item><qref id="f-Version"><tt>Version</tt></qref> (mandatory)</item>
2642 <item><qref id="f-Maintainer"><tt>Maintainer</tt></qref> (mandatory)</item>
2643 <item><qref id="f-Uploaders"><tt>Uploaders</tt></qref></item>
2644 <item><qref id="f-DM-Upload-Allowed"<tt>DM-Upload-Allowed</tt></qref></item>
2645 <item><qref id="f-Homepage"><tt>Homepage</tt></qref></item>
2646 <item><qref id="f-Standards-Version"><tt>Standards-Version</tt></qref> (recommended)</item>
2647 <item><qref id="sourcebinarydeps"><tt>Build-Depends</tt> et al</qref></item>
2648 <item><qref id="f-Checksums"><tt>Checksums-Sha1</tt>
2649 and <tt>Checksums-Sha256</tt></qref> (recommended)</item>
2650 <item><qref id="f-Files"><tt>Files</tt></qref> (mandatory)</item>
2655 The source package control file is generated by
2656 <prgn>dpkg-source</prgn> when it builds the source
2657 archive, from other files in the source package,
2658 described above. When unpacking, it is checked against
2659 the files and directories in the other parts of the
2665 <sect id="debianchangesfiles">
2666 <heading>Debian changes files -- <file>.changes</file></heading>
2669 The <file>.changes</file> files are used by the Debian archive
2670 maintenance software to process updates to packages. They
2671 consist of a single paragraph, possibly surrounded by a PGP
2672 signature. That paragraph contains information from the
2673 <file>debian/control</file> file and other data about the
2674 source package gathered via <file>debian/changelog</file>
2675 and <file>debian/rules</file>.
2679 <file>.changes</file> files have a format version that is
2680 incremented whenever the documented fields or their meaning
2681 change. This document describes format &changesversion;.
2685 The fields in this file are:
2687 <list compact="compact">
2688 <item><qref id="f-Format"><tt>Format</tt></qref> (mandatory)</item>
2689 <item><qref id="f-Date"><tt>Date</tt></qref> (mandatory)</item>
2690 <item><qref id="f-Source"><tt>Source</tt></qref> (mandatory)</item>
2691 <item><qref id="f-Binary"><tt>Binary</tt></qref> (mandatory)</item>
2692 <item><qref id="f-Architecture"><tt>Architecture</tt></qref> (mandatory)</item>
2693 <item><qref id="f-Version"><tt>Version</tt></qref> (mandatory)</item>
2694 <item><qref id="f-Distribution"><tt>Distribution</tt></qref> (mandatory)</item>
2695 <item><qref id="f-Urgency"><tt>Urgency</tt></qref> (recommended)</item>
2696 <item><qref id="f-Maintainer"><tt>Maintainer</tt></qref> (mandatory)</item>
2697 <item><qref id="f-Changed-By"><tt>Changed-By</tt></qref></item>
2698 <item><qref id="f-Description"><tt>Description</tt></qref> (mandatory)</item>
2699 <item><qref id="f-Closes"><tt>Closes</tt></qref></item>
2700 <item><qref id="f-Changes"><tt>Changes</tt></qref> (mandatory)</item>
2701 <item><qref id="f-Checksums"><tt>Checksums-Sha1</tt>
2702 and <tt>Checksums-Sha256</tt></qref> (recommended)</item>
2703 <item><qref id="f-Files"><tt>Files</tt></qref> (mandatory)</item>
2708 <sect id="controlfieldslist">
2709 <heading>List of fields</heading>
2711 <sect1 id="f-Source">
2712 <heading><tt>Source</tt></heading>
2715 This field identifies the source package name.
2719 In <file>debian/control</file> or a <file>.dsc</file> file,
2720 this field must contain only the name of the source package.
2724 In a binary package control file or a <file>.changes</file>
2725 file, the source package name may be followed by a version
2726 number in parentheses<footnote>
2727 It is customary to leave a space after the package name
2728 if a version number is specified.
2730 This version number may be omitted (and is, by
2731 <prgn>dpkg-gencontrol</prgn>) if it has the same value as
2732 the <tt>Version</tt> field of the binary package in
2733 question. The field itself may be omitted from a binary
2734 package control file when the source package has the same
2735 name and version as the binary package.
2739 Package names (both source and binary,
2740 see <ref id="f-Package">) must consist only of lower case
2741 letters (<tt>a-z</tt>), digits (<tt>0-9</tt>), plus
2742 (<tt>+</tt>) and minus (<tt>-</tt>) signs, and periods
2743 (<tt>.</tt>). They must be at least two characters long and
2744 must start with an alphanumeric character.
2748 <sect1 id="f-Maintainer">
2749 <heading><tt>Maintainer</tt></heading>
2752 The package maintainer's name and email address. The name
2753 must come first, then the email address inside angle
2754 brackets <tt><></tt> (in RFC822 format).
2758 If the maintainer's name contains a full stop then the
2759 whole field will not work directly as an email address due
2760 to a misfeature in the syntax specified in RFC822; a
2761 program using this field as an address must check for this
2762 and correct the problem if necessary (for example by
2763 putting the name in round brackets and moving it to the
2764 end, and bringing the email address forward).
2768 See <ref id="maintainer"> for additional requirements and
2769 information about package maintainers.
2773 <sect1 id="f-Uploaders">
2774 <heading><tt>Uploaders</tt></heading>
2777 List of the names and email addresses of co-maintainers of the
2778 package, if any. If the package has other maintainers besides
2779 the one named in the <qref id="f-Maintainer">Maintainer
2780 field</qref>, their names and email addresses should be listed
2781 here. The format of each entry is the same as that of the
2782 Maintainer field, and multiple entries must be comma
2787 This is normally an optional field, but if
2788 the <tt>Maintainer</tt> control field names a group of people
2789 and a shared email address, the <tt>Uploaders</tt> field must
2790 be present and must contain at least one human with their
2791 personal email address.
2795 Any parser that interprets the Uploaders field in
2796 <file>debian/control</file> must permit it to span multiple
2797 lines. Line breaks in an Uploaders field that spans multiple
2798 lines are not significant and the semantics of the field are
2799 the same as if the line breaks had not been present.
2803 <sect1 id="f-DM-Upload-Allowed">
2804 <heading><tt>DM-Upload-Allowed</tt></heading>
2807 The most recent version of a package uploaded to unstable or
2808 experimental must include the field "DM-Upload-Allowed: yes" in the
2809 source section of its source control file for the Debian archive to
2810 accept uploads signed with a key in the Debian Maintainer keyring.
2811 See the General Resolution <url id="http://www.debian.org/vote/2007/vote_003"
2812 name="Endorse the concept of Debian Maintainers"> for more details.
2816 <sect1 id="f-Changed-By">
2817 <heading><tt>Changed-By</tt></heading>
2820 The name and email address of the person who prepared this
2821 version of the package, usually a maintainer. The syntax is
2822 the same as for the <qref id="f-Maintainer">Maintainer
2827 <sect1 id="f-Section">
2828 <heading><tt>Section</tt></heading>
2831 This field specifies an application area into which the package
2832 has been classified. See <ref id="subsections">.
2836 When it appears in the <file>debian/control</file> file,
2837 it gives the value for the subfield of the same name in
2838 the <tt>Files</tt> field of the <file>.changes</file> file.
2839 It also gives the default for the same field in the binary
2844 <sect1 id="f-Priority">
2845 <heading><tt>Priority</tt></heading>
2848 This field represents how important it is that the user
2849 have the package installed. See <ref id="priorities">.
2853 When it appears in the <file>debian/control</file> file,
2854 it gives the value for the subfield of the same name in
2855 the <tt>Files</tt> field of the <file>.changes</file> file.
2856 It also gives the default for the same field in the binary
2861 <sect1 id="f-Package">
2862 <heading><tt>Package</tt></heading>
2865 The name of the binary package.
2869 Binary package names must follow the same syntax and
2870 restrictions as source package names. See <ref id="f-Source">
2875 <sect1 id="f-Architecture">
2876 <heading><tt>Architecture</tt></heading>
2879 Depending on context and the control file used, the
2880 <tt>Architecture</tt> field can include the following sets of
2884 A unique single word identifying a Debian machine
2885 architecture as described in <ref id="arch-spec">.
2888 An architecture wildcard identifying a set of Debian
2889 machine architectures, see <ref id="arch-wildcard-spec">.
2890 <tt>any</tt> matches all Debian machine architectures
2891 and is the most frequently used.
2894 <tt>all</tt>, which indicates an
2895 architecture-independent package.
2898 <tt>source</tt>, which indicates a source package.
2904 In the main <file>debian/control</file> file in the source
2905 package, this field may contain the special
2906 value <tt>all</tt>, the special architecture
2907 wildcard <tt>any</tt>, or a list of specific and wildcard
2908 architectures separated by spaces. If <tt>all</tt>
2909 or <tt>any</tt> appears, that value must be the entire
2910 contents of the field. Most packages will use
2911 either <tt>all</tt> or <tt>any</tt>.
2915 Specifying a specific list of architectures indicates that the
2916 source will build an architecture-dependent package only on
2917 architectures included in the list. Specifying a list of
2918 architecture wildcards indicates that the source will build an
2919 architecture-dependent package on only those architectures
2920 that match any of the specified architecture wildcards.
2921 Specifying a list of architectures or architecture wildcards
2922 other than <tt>any</tt> is for the minority of cases where a
2923 program is not portable or is not useful on some
2924 architectures. Where possible, the program should be made
2929 In the source package control file <file>.dsc</file>, this
2930 field may contain either the architecture
2931 wildcard <tt>any</tt> or a list of architectures and
2932 architecture wildcards separated by spaces. If a list is
2933 given, it may include (or consist solely of) the special
2934 value <tt>all</tt>. In other words, in <file>.dsc</file>
2935 files unlike the <file>debian/control</file>, <tt>all</tt> may
2936 occur in combination with specific architectures.
2937 The <tt>Architecture</tt> field in the source package control
2938 file <file>.dsc</file> is generally constructed from
2939 the <tt>Architecture</tt> fields in
2940 the <file>debian/control</file> in the source package.
2944 Specifying <tt>any</tt> indicates that the source package
2945 isn't dependent on any particular architecture and should
2946 compile fine on any one. The produced binary package(s)
2947 will either be specific to whatever the current build
2948 architecture is or will be architecture-independent.
2952 Specifying only <tt>all</tt> indicates that the source package
2953 will only build architecture-independent packages. If this is
2954 the case, <tt>all</tt> must be used rather than <tt>any</tt>;
2955 <tt>any</tt> implies that the source package will build at
2956 least one architecture-dependent package.
2960 Specifying a list of architectures or architecture wildcards
2961 indicates that the source will build an architecture-dependent
2962 package, and will only work correctly on the listed or
2963 matching architectures. If the source package also builds at
2964 least one architecture-independent package, <tt>all</tt> will
2965 also be included in the list.
2969 In a <file>.changes</file> file, the <tt>Architecture</tt>
2970 field lists the architecture(s) of the package(s) currently
2971 being uploaded. This will be a list; if the source for the
2972 package is also being uploaded, the special
2973 entry <tt>source</tt> is also present. <tt>all</tt> will be
2974 present if any architecture-independent packages are being
2975 uploaded. Architecture wildcards such as <tt>any</tt> must
2976 never occur in the <tt>Architecture</tt> field in
2977 the <file>.changes</file> file.
2981 See <ref id="debianrules"> for information on how to get
2982 the architecture for the build process.
2986 <sect1 id="f-Essential">
2987 <heading><tt>Essential</tt></heading>
2990 This is a boolean field which may occur only in the
2991 control file of a binary package or in a per-package fields
2992 paragraph of a main source control data file.
2996 If set to <tt>yes</tt> then the package management system
2997 will refuse to remove the package (upgrading and replacing
2998 it is still possible). The other possible value is <tt>no</tt>,
2999 which is the same as not having the field at all.
3004 <heading>Package interrelationship fields:
3005 <tt>Depends</tt>, <tt>Pre-Depends</tt>,
3006 <tt>Recommends</tt>, <tt>Suggests</tt>,
3007 <tt>Breaks</tt>, <tt>Conflicts</tt>,
3008 <tt>Provides</tt>, <tt>Replaces</tt>, <tt>Enhances</tt>
3012 These fields describe the package's relationships with
3013 other packages. Their syntax and semantics are described
3014 in <ref id="relationships">.</p>
3017 <sect1 id="f-Standards-Version">
3018 <heading><tt>Standards-Version</tt></heading>
3021 The most recent version of the standards (the policy
3022 manual and associated texts) with which the package
3027 The version number has four components: major and minor
3028 version number and major and minor patch level. When the
3029 standards change in a way that requires every package to
3030 change the major number will be changed. Significant
3031 changes that will require work in many packages will be
3032 signaled by a change to the minor number. The major patch
3033 level will be changed for any change to the meaning of the
3034 standards, however small; the minor patch level will be
3035 changed when only cosmetic, typographical or other edits
3036 are made which neither change the meaning of the document
3037 nor affect the contents of packages.
3041 Thus only the first three components of the policy version
3042 are significant in the <em>Standards-Version</em> control
3043 field, and so either these three components or all four
3044 components may be specified.<footnote>
3045 In the past, people specified the full version number
3046 in the Standards-Version field, for example "2.3.0.0".
3047 Since minor patch-level changes don't introduce new
3048 policy, it was thought it would be better to relax
3049 policy and only require the first 3 components to be
3050 specified, in this example "2.3.0". All four
3051 components may still be used if someone wishes to do so.
3057 <sect1 id="f-Version">
3058 <heading><tt>Version</tt></heading>
3061 The version number of a package. The format is:
3062 [<var>epoch</var><tt>:</tt>]<var>upstream_version</var>[<tt>-</tt><var>debian_revision</var>]
3066 The three components here are:
3068 <tag><var>epoch</var></tag>
3071 This is a single (generally small) unsigned integer. It
3072 may be omitted, in which case zero is assumed. If it is
3073 omitted then the <var>upstream_version</var> may not
3078 It is provided to allow mistakes in the version numbers
3079 of older versions of a package, and also a package's
3080 previous version numbering schemes, to be left behind.
3084 <tag><var>upstream_version</var></tag>
3087 This is the main part of the version number. It is
3088 usually the version number of the original ("upstream")
3089 package from which the <file>.deb</file> file has been made,
3090 if this is applicable. Usually this will be in the same
3091 format as that specified by the upstream author(s);
3092 however, it may need to be reformatted to fit into the
3093 package management system's format and comparison
3098 The comparison behavior of the package management system
3099 with respect to the <var>upstream_version</var> is
3100 described below. The <var>upstream_version</var>
3101 portion of the version number is mandatory.
3105 The <var>upstream_version</var> may contain only
3106 alphanumerics<footnote>
3107 Alphanumerics are <tt>A-Za-z0-9</tt> only.
3109 and the characters <tt>.</tt> <tt>+</tt> <tt>-</tt>
3110 <tt>:</tt> <tt>~</tt> (full stop, plus, hyphen, colon,
3111 tilde) and should start with a digit. If there is no
3112 <var>debian_revision</var> then hyphens are not allowed;
3113 if there is no <var>epoch</var> then colons are not
3118 <tag><var>debian_revision</var></tag>
3121 This part of the version number specifies the version of
3122 the Debian package based on the upstream version. It
3123 may contain only alphanumerics and the characters
3124 <tt>+</tt> <tt>.</tt> <tt>~</tt> (plus, full stop,
3125 tilde) and is compared in the same way as the
3126 <var>upstream_version</var> is.
3130 It is optional; if it isn't present then the
3131 <var>upstream_version</var> may not contain a hyphen.
3132 This format represents the case where a piece of
3133 software was written specifically to be a Debian
3134 package, where the Debian package source must always
3135 be identical to the pristine source and therefore no
3136 revision indication is required.
3140 It is conventional to restart the
3141 <var>debian_revision</var> at <tt>1</tt> each time the
3142 <var>upstream_version</var> is increased.
3146 The package management system will break the version
3147 number apart at the last hyphen in the string (if there
3148 is one) to determine the <var>upstream_version</var> and
3149 <var>debian_revision</var>. The absence of a
3150 <var>debian_revision</var> is equivalent to a
3151 <var>debian_revision</var> of <tt>0</tt>.
3158 When comparing two version numbers, first the <var>epoch</var>
3159 of each are compared, then the <var>upstream_version</var> if
3160 <var>epoch</var> is equal, and then <var>debian_revision</var>
3161 if <var>upstream_version</var> is also equal.
3162 <var>epoch</var> is compared numerically. The
3163 <var>upstream_version</var> and <var>debian_revision</var>
3164 parts are compared by the package management system using the
3165 following algorithm:
3169 The strings are compared from left to right.
3173 First the initial part of each string consisting entirely of
3174 non-digit characters is determined. These two parts (one of
3175 which may be empty) are compared lexically. If a difference
3176 is found it is returned. The lexical comparison is a
3177 comparison of ASCII values modified so that all the letters
3178 sort earlier than all the non-letters and so that a tilde
3179 sorts before anything, even the end of a part. For example,
3180 the following parts are in sorted order from earliest to
3181 latest: <tt>~~</tt>, <tt>~~a</tt>, <tt>~</tt>, the empty part,
3182 <tt>a</tt>.<footnote>
3183 One common use of <tt>~</tt> is for upstream pre-releases.
3184 For example, <tt>1.0~beta1~svn1245</tt> sorts earlier than
3185 <tt>1.0~beta1</tt>, which sorts earlier than <tt>1.0</tt>.
3190 Then the initial part of the remainder of each string which
3191 consists entirely of digit characters is determined. The
3192 numerical values of these two parts are compared, and any
3193 difference found is returned as the result of the comparison.
3194 For these purposes an empty string (which can only occur at
3195 the end of one or both version strings being compared) counts
3200 These two steps (comparing and removing initial non-digit
3201 strings and initial digit strings) are repeated until a
3202 difference is found or both strings are exhausted.
3206 Note that the purpose of epochs is to allow us to leave behind
3207 mistakes in version numbering, and to cope with situations
3208 where the version numbering scheme changes. It is
3209 <em>not</em> intended to cope with version numbers containing
3210 strings of letters which the package management system cannot
3211 interpret (such as <tt>ALPHA</tt> or <tt>pre-</tt>), or with
3212 silly orderings.<footnote>
3213 The author of this manual has heard of a package whose
3214 versions went <tt>1.1</tt>, <tt>1.2</tt>, <tt>1.3</tt>,
3215 <tt>1</tt>, <tt>2.1</tt>, <tt>2.2</tt>, <tt>2</tt> and so
3221 <sect1 id="f-Description">
3222 <heading><tt>Description</tt></heading>
3225 In a source or binary control file, the <tt>Description</tt>
3226 field contains a description of the binary package, consisting
3227 of two parts, the synopsis or the short description, and the
3228 long description. The field's format is as follows:
3233 Description: <single line synopsis>
3234 <extended description over several lines>
3239 The lines in the extended description can have these formats:
3245 Those starting with a single space are part of a paragraph.
3246 Successive lines of this form will be word-wrapped when
3247 displayed. The leading space will usually be stripped off.
3251 Those starting with two or more spaces. These will be
3252 displayed verbatim. If the display cannot be panned
3253 horizontally, the displaying program will line wrap them "hard"
3254 (i.e., without taking account of word breaks). If it can they
3255 will be allowed to trail off to the right. None, one or two
3256 initial spaces may be deleted, but the number of spaces
3257 deleted from each line will be the same (so that you can have
3258 indenting work correctly, for example).
3262 Those containing a single space followed by a single full stop
3263 character. These are rendered as blank lines. This is the
3264 <em>only</em> way to get a blank line<footnote>
3265 Completely empty lines will not be rendered as blank lines.
3266 Instead, they will cause the parser to think you're starting
3267 a whole new record in the control file, and will therefore
3268 likely abort with an error.
3273 Those containing a space, a full stop and some more characters.
3274 These are for future expansion. Do not use them.
3280 Do not use tab characters. Their effect is not predictable.
3284 See <ref id="descriptions"> for further information on this.
3288 In a <file>.changes</file> file, the <tt>Description</tt>
3289 field contains a summary of the descriptions for the packages
3290 being uploaded. For this case, the first line of the field
3291 value (the part on the same line as <tt>Description:</tt>) is
3292 always empty. The content of the field is expressed as
3293 continuation lines, one line per package. Each line is
3294 indented by one space and contains the name of a binary
3295 package, a space, a hyphen (<tt>-</tt>), a space, and the
3296 short description line from that package.
3300 <sect1 id="f-Distribution">
3301 <heading><tt>Distribution</tt></heading>
3304 In a <file>.changes</file> file or parsed changelog output
3305 this contains the (space-separated) name(s) of the
3306 distribution(s) where this version of the package should
3307 be installed. Valid distributions are determined by the
3308 archive maintainers.<footnote>
3309 Example distribution names in the Debian archive used in
3310 <file>.changes</file> files are:
3311 <taglist compact="compact">
3312 <tag><em>unstable</em></tag>
3314 This distribution value refers to the
3315 <em>developmental</em> part of the Debian distribution
3316 tree. Most new packages, new upstream versions of
3317 packages and bug fixes go into the <em>unstable</em>
3321 <tag><em>experimental</em></tag>
3323 The packages with this distribution value are deemed
3324 by their maintainers to be high risk. Oftentimes they
3325 represent early beta or developmental packages from
3326 various sources that the maintainers want people to
3327 try, but are not ready to be a part of the other parts
3328 of the Debian distribution tree.
3333 Others are used for updating stable releases or for
3334 security uploads. More information is available in the
3335 Debian Developer's Reference, section "The Debian
3339 The Debian archive software only supports listing a single
3340 distribution. Migration of packages to other distributions is
3341 handled outside of the upload process.
3346 <heading><tt>Date</tt></heading>
3349 This field includes the date the package was built or last
3350 edited. It must be in the same format as the <var>date</var>
3351 in a <file>debian/changelog</file> entry.
3355 The value of this field is usually extracted from the
3356 <file>debian/changelog</file> file - see
3357 <ref id="dpkgchangelog">).
3361 <sect1 id="f-Format">
3362 <heading><tt>Format</tt></heading>
3365 In <qref id="debianchangesfiles"><file>.changes</file></qref>
3366 files, this field declares the format version of that file.
3367 The syntax of the field value is the same as that of
3368 a <qref id="f-Version">package version number</qref> except
3369 that no epoch or Debian revision is allowed. The format
3370 described in this document is <tt>&changesversion;</tt>.
3374 In <qref id="debiansourcecontrolfiles"><file>.dsc</file>
3375 Debian source control</qref> files, this field declares the
3376 format of the source package. The field value is used by
3377 programs acting on a source package to interpret the list of
3378 files in the source package and determine how to unpack it.
3379 The syntax of the field value is a numeric major revision, a
3380 period, a numeric minor revision, and then an optional subtype
3381 after whitespace, which if specified is an alphanumeric word
3382 in parentheses. The subtype is optional in the syntax but may
3383 be mandatory for particular source format revisions.
3385 The source formats currently supported by the Debian archive
3386 software are <tt>1.0</tt>, <tt>3.0 (native)</tt>,
3387 and <tt>3.0 (quilt)</tt>.
3392 <sect1 id="f-Urgency">
3393 <heading><tt>Urgency</tt></heading>
3396 This is a description of how important it is to upgrade to
3397 this version from previous ones. It consists of a single
3398 keyword taking one of the values <tt>low</tt>,
3399 <tt>medium</tt>, <tt>high</tt>, <tt>emergency</tt>, or
3400 <tt>critical</tt><footnote>
3401 Other urgency values are supported with configuration
3402 changes in the archive software but are not used in Debian.
3403 The urgency affects how quickly a package will be considered
3404 for inclusion into the <tt>testing</tt> distribution and
3405 gives an indication of the importance of any fixes included
3406 in the upload. <tt>Emergency</tt> and <tt>critical</tt> are
3407 treated as synonymous.
3408 </footnote> (not case-sensitive) followed by an optional
3409 commentary (separated by a space) which is usually in
3410 parentheses. For example:
3413 Urgency: low (HIGH for users of diversions)
3419 The value of this field is usually extracted from the
3420 <file>debian/changelog</file> file - see
3421 <ref id="dpkgchangelog">.
3425 <sect1 id="f-Changes">
3426 <heading><tt>Changes</tt></heading>
3429 This field contains the human-readable changes data, describing
3430 the differences between the last version and the current one.
3434 The first line of the field value (the part on the same line
3435 as <tt>Changes:</tt>) is always empty. The content of the
3436 field is expressed as continuation lines, with each line
3437 indented by at least one space. Blank lines must be
3438 represented by a line consisting only of a space and a full
3443 The value of this field is usually extracted from the
3444 <file>debian/changelog</file> file - see
3445 <ref id="dpkgchangelog">).
3449 Each version's change information should be preceded by a
3450 "title" line giving at least the version, distribution(s)
3451 and urgency, in a human-readable way.
3455 If data from several versions is being returned the entry
3456 for the most recent version should be returned first, and
3457 entries should be separated by the representation of a
3458 blank line (the "title" line may also be followed by the
3459 representation of a blank line).
3463 <sect1 id="f-Binary">
3464 <heading><tt>Binary</tt></heading>
3467 This field is a list of binary packages. Its syntax and
3468 meaning varies depending on the control file in which it
3473 When it appears in the <file>.dsc</file> file, it lists binary
3474 packages which a source package can produce, separated by
3476 A space after each comma is conventional.
3477 </footnote>. It may span multiple lines. The source package
3478 does not necessarily produce all of these binary packages for
3479 every architecture. The source control file doesn't contain
3480 details of which architectures are appropriate for which of
3481 the binary packages.
3485 When it appears in a <file>.changes</file> file, it lists the
3486 names of the binary packages being uploaded, separated by
3487 whitespace (not commas). It may span multiple lines.
3491 <sect1 id="f-Installed-Size">
3492 <heading><tt>Installed-Size</tt></heading>
3495 This field appears in the control files of binary packages,
3496 and in the <file>Packages</file> files. It gives an estimate
3497 of the total amount of disk space required to install the
3498 named package. Actual installed size may vary based on block
3499 size, file system properties, or actions taken by package
3504 The disk space is given as the integer value of the estimated
3505 installed size in bytes, divided by 1024 and rounded up.
3509 <sect1 id="f-Files">
3510 <heading><tt>Files</tt></heading>
3513 This field contains a list of files with information about
3514 each one. The exact information and syntax varies with
3519 In all cases, Files is a multiline field. The first line of
3520 the field value (the part on the same line as <tt>Files:</tt>)
3521 is always empty. The content of the field is expressed as
3522 continuation lines, one line per file. Each line must be
3523 indented by one space and contain a number of sub-fields,
3524 separated by spaces, as described below.
3528 In the <file>.dsc</file> file, each line contains the MD5
3529 checksum, size and filename of the tar file and (if
3530 applicable) diff file which make up the remainder of the
3531 source package<footnote>
3532 That is, the parts which are not the <tt>.dsc</tt>.
3533 </footnote>. For example:
3536 c6f698f19f2a2aa07dbb9bbda90a2754 571925 example_1.2.orig.tar.gz
3537 938512f08422f3509ff36f125f5873ba 6220 example_1.2-1.diff.gz
3539 The exact forms of the filenames are described
3540 in <ref id="pkg-sourcearchives">.
3544 In the <file>.changes</file> file this contains one line per
3545 file being uploaded. Each line contains the MD5 checksum,
3546 size, section and priority and the filename. For example:
3549 4c31ab7bfc40d3cf49d7811987390357 1428 text extra example_1.2-1.dsc
3550 c6f698f19f2a2aa07dbb9bbda90a2754 571925 text extra example_1.2.orig.tar.gz
3551 938512f08422f3509ff36f125f5873ba 6220 text extra example_1.2-1.diff.gz
3552 7c98fe853b3bbb47a00e5cd129b6cb56 703542 text extra example_1.2-1_i386.deb
3554 The <qref id="f-Section">section</qref>
3555 and <qref id="f-Priority">priority</qref> are the values of
3556 the corresponding fields in the main source control file. If
3557 no section or priority is specified then <tt>-</tt> should be
3558 used, though section and priority values must be specified for
3559 new packages to be installed properly.
3563 The special value <tt>byhand</tt> for the section in a
3564 <tt>.changes</tt> file indicates that the file in question
3565 is not an ordinary package file and must by installed by
3566 hand by the distribution maintainers. If the section is
3567 <tt>byhand</tt> the priority should be <tt>-</tt>.
3571 If a new Debian revision of a package is being shipped and
3572 no new original source archive is being distributed the
3573 <tt>.dsc</tt> must still contain the <tt>Files</tt> field
3574 entry for the original source archive
3575 <file><var>package</var>_<var>upstream-version</var>.orig.tar.gz</file>,
3576 but the <file>.changes</file> file should leave it out. In
3577 this case the original source archive on the distribution
3578 site must match exactly, byte-for-byte, the original
3579 source archive which was used to generate the
3580 <file>.dsc</file> file and diff which are being uploaded.</p>
3583 <sect1 id="f-Closes">
3584 <heading><tt>Closes</tt></heading>
3587 A space-separated list of bug report numbers that the upload
3588 governed by the .changes file closes.
3592 <sect1 id="f-Homepage">
3593 <heading><tt>Homepage</tt></heading>
3596 The URL of the web site for this package, preferably (when
3597 applicable) the site from which the original source can be
3598 obtained and any additional upstream documentation or
3599 information may be found. The content of this field is a
3600 simple URL without any surrounding characters such as
3605 <sect1 id="f-Checksums">
3606 <heading><tt>Checksums-Sha1</tt>
3607 and <tt>Checksums-Sha256</tt></heading>
3610 These fields contain a list of files with a checksum and size
3611 for each one. Both <tt>Checksums-Sha1</tt>
3612 and <tt>Checksums-Sha256</tt> have the same syntax and differ
3613 only in the checksum algorithm used: SHA-1
3614 for <tt>Checksums-Sha1</tt> and SHA-256
3615 for <tt>Checksums-Sha256</tt>.
3619 <tt>Checksums-Sha1</tt> and <tt>Checksums-Sha256</tt> are
3620 multiline fields. The first line of the field value (the part
3621 on the same line as <tt>Checksums-Sha1:</tt>
3622 or <tt>Checksums-Sha256:</tt>) is always empty. The content
3623 of the field is expressed as continuation lines, one line per
3624 file. Each line consists of the checksum, a space, the file
3625 size, a space, and the file name. For example (from
3626 a <file>.changes</file> file):
3629 1f418afaa01464e63cc1ee8a66a05f0848bd155c 1276 example_1.0-1.dsc
3630 a0ed1456fad61116f868b1855530dbe948e20f06 171602 example_1.0.orig.tar.gz
3631 5e86ecf0671e113b63388dac81dd8d00e00ef298 6137 example_1.0-1.debian.tar.gz
3632 71a0ff7da0faaf608481195f9cf30974b142c183 548402 example_1.0-1_i386.deb
3634 ac9d57254f7e835bed299926fd51bf6f534597cc3fcc52db01c4bffedae81272 1276 example_1.0-1.dsc
3635 0d123be7f51e61c4bf15e5c492b484054be7e90f3081608a5517007bfb1fd128 171602 example_1.0.orig.tar.gz
3636 f54ae966a5f580571ae7d9ef5e1df0bd42d63e27cb505b27957351a495bc6288 6137 example_1.0-1.debian.tar.gz
3637 3bec05c03974fdecd11d020fc2e8250de8404867a8a2ce865160c250eb723664 548402 example_1.0-1_i386.deb
3642 In the <file>.dsc</file> file, these fields should list all
3643 files that make up the source package. In
3644 the <file>.changes</file> file, these fields should list all
3645 files being uploaded. The list of files in these fields
3646 must match the list of files in the <tt>Files</tt> field.
3652 <heading>User-defined fields</heading>
3655 Additional user-defined fields may be added to the
3656 source package control file. Such fields will be
3657 ignored, and not copied to (for example) binary or
3658 source package control files or upload control files.
3662 If you wish to add additional unsupported fields to
3663 these output files you should use the mechanism
3668 Fields in the main source control information file with
3669 names starting <tt>X</tt>, followed by one or more of
3670 the letters <tt>BCS</tt> and a hyphen <tt>-</tt>, will
3671 be copied to the output files. Only the part of the
3672 field name after the hyphen will be used in the output
3673 file. Where the letter <tt>B</tt> is used the field
3674 will appear in binary package control files, where the
3675 letter <tt>S</tt> is used in source package control
3676 files and where <tt>C</tt> is used in upload control
3677 (<tt>.changes</tt>) files.
3681 For example, if the main source information control file
3684 XBS-Comment: I stand between the candle and the star.
3686 then the binary and source package control files will contain the
3689 Comment: I stand between the candle and the star.
3698 <chapt id="maintainerscripts">
3699 <heading>Package maintainer scripts and installation procedure</heading>
3702 <heading>Introduction to package maintainer scripts</heading>
3705 It is possible to supply scripts as part of a package which
3706 the package management system will run for you when your
3707 package is installed, upgraded or removed.
3711 These scripts are the control information
3712 files <prgn>preinst</prgn>, <prgn>postinst</prgn>, <prgn>prerm</prgn>
3713 and <prgn>postrm</prgn>. They must be proper executable files;
3714 if they are scripts (which is recommended), they must start with
3715 the usual <tt>#!</tt> convention. They should be readable and
3716 executable by anyone, and must not be world-writable.
3720 The package management system looks at the exit status from
3721 these scripts. It is important that they exit with a
3722 non-zero status if there is an error, so that the package
3723 management system can stop its processing. For shell
3724 scripts this means that you <em>almost always</em> need to
3725 use <tt>set -e</tt> (this is usually true when writing shell
3726 scripts, in fact). It is also important, of course, that
3727 they exit with a zero status if everything went well.
3731 Additionally, packages interacting with users
3732 using <prgn>debconf</prgn> in the <prgn>postinst</prgn> script
3733 should install a <prgn>config</prgn> script as a control
3734 information file. See <ref id="maintscriptprompt"> for details.
3738 When a package is upgraded a combination of the scripts from
3739 the old and new packages is called during the upgrade
3740 procedure. If your scripts are going to be at all
3741 complicated you need to be aware of this, and may need to
3742 check the arguments to your scripts.
3746 Broadly speaking the <prgn>preinst</prgn> is called before
3747 (a particular version of) a package is installed, and the
3748 <prgn>postinst</prgn> afterwards; the <prgn>prerm</prgn>
3749 before (a version of) a package is removed and the
3750 <prgn>postrm</prgn> afterwards.
3754 Programs called from maintainer scripts should not normally
3755 have a path prepended to them. Before installation is
3756 started, the package management system checks to see if the
3757 programs <prgn>ldconfig</prgn>,
3758 <prgn>start-stop-daemon</prgn>, <prgn>install-info</prgn>,
3759 and <prgn>update-rc.d</prgn> can be found via the
3760 <tt>PATH</tt> environment variable. Those programs, and any
3761 other program that one would expect to be in the
3762 <tt>PATH</tt>, should thus be invoked without an absolute
3763 pathname. Maintainer scripts should also not reset the
3764 <tt>PATH</tt>, though they might choose to modify it by
3765 prepending or appending package-specific directories. These
3766 considerations really apply to all shell scripts.</p>
3769 <sect id="idempotency">
3770 <heading>Maintainer scripts idempotency</heading>
3773 It is necessary for the error recovery procedures that the
3774 scripts be idempotent. This means that if it is run
3775 successfully, and then it is called again, it doesn't bomb
3776 out or cause any harm, but just ensures that everything is
3777 the way it ought to be. If the first call failed, or
3778 aborted half way through for some reason, the second call
3779 should merely do the things that were left undone the first
3780 time, if any, and exit with a success status if everything
3782 This is so that if an error occurs, the user interrupts
3783 <prgn>dpkg</prgn> or some other unforeseen circumstance
3784 happens you don't leave the user with a badly-broken
3785 package when <prgn>dpkg</prgn> attempts to repeat the
3791 <sect id="controllingterminal">
3792 <heading>Controlling terminal for maintainer scripts</heading>
3795 Maintainer scripts are not guaranteed to run with a controlling
3796 terminal and may not be able to interact with the user. They
3797 must be able to fall back to noninteractive behavior if no
3798 controlling terminal is available. Maintainer scripts that
3799 prompt via a program conforming to the Debian Configuration
3800 Management Specification (see <ref id="maintscriptprompt">) may
3801 assume that program will handle falling back to noninteractive
3806 For high-priority prompts without a reasonable default answer,
3807 maintainer scripts may abort if there is no controlling
3808 terminal. However, this situation should be avoided if at all
3809 possible, since it prevents automated or unattended installs.
3810 In most cases, users will consider this to be a bug in the
3815 <sect id="exitstatus">
3816 <heading>Exit status</heading>
3819 Each script must return a zero exit status for
3820 success, or a nonzero one for failure, since the package
3821 management system looks for the exit status of these scripts
3822 and determines what action to take next based on that datum.
3826 <sect id="mscriptsinstact"><heading>Summary of ways maintainer
3831 <list compact="compact">
3833 <var>new-preinst</var> <tt>install</tt>
3836 <var>new-preinst</var> <tt>install</tt> <var>old-version</var>
3839 <var>new-preinst</var> <tt>upgrade</tt> <var>old-version</var>
3842 <var>old-preinst</var> <tt>abort-upgrade</tt>
3843 <var>new-version</var>
3848 <list compact="compact">
3850 <var>postinst</var> <tt>configure</tt>
3851 <var>most-recently-configured-version</var>
3854 <var>old-postinst</var> <tt>abort-upgrade</tt>
3855 <var>new-version</var>
3858 <var>conflictor's-postinst</var> <tt>abort-remove</tt>
3859 <tt>in-favour</tt> <var>package</var>
3860 <var>new-version</var>
3863 <var>postinst</var> <tt>abort-remove</tt>
3866 <var>deconfigured's-postinst</var>
3867 <tt>abort-deconfigure</tt> <tt>in-favour</tt>
3868 <var>failed-install-package</var> <var>version</var>
3869 [<tt>removing</tt> <var>conflicting-package</var>
3875 <list compact="compact">
3877 <var>prerm</var> <tt>remove</tt>
3880 <var>old-prerm</var> <tt>upgrade</tt>
3881 <var>new-version</var>
3884 <var>new-prerm</var> <tt>failed-upgrade</tt>
3885 <var>old-version</var>
3888 <var>conflictor's-prerm</var> <tt>remove</tt>
3889 <tt>in-favour</tt> <var>package</var>
3890 <var>new-version</var>
3893 <var>deconfigured's-prerm</var> <tt>deconfigure</tt>
3894 <tt>in-favour</tt> <var>package-being-installed</var>
3895 <var>version</var> [<tt>removing</tt>
3896 <var>conflicting-package</var>
3902 <list compact="compact">
3904 <var>postrm</var> <tt>remove</tt>
3907 <var>postrm</var> <tt>purge</tt>
3910 <var>old-postrm</var> <tt>upgrade</tt>
3911 <var>new-version</var>
3914 <var>new-postrm</var> <tt>failed-upgrade</tt>
3915 <var>old-version</var>
3918 <var>new-postrm</var> <tt>abort-install</tt>
3921 <var>new-postrm</var> <tt>abort-install</tt>
3922 <var>old-version</var>
3925 <var>new-postrm</var> <tt>abort-upgrade</tt>
3926 <var>old-version</var>
3929 <var>disappearer's-postrm</var> <tt>disappear</tt>
3930 <var>overwriter</var>
3931 <var>overwriter-version</var>
3937 <sect id="unpackphase">
3938 <heading>Details of unpack phase of installation or upgrade</heading>
3941 The procedure on installation/upgrade/overwrite/disappear
3942 (i.e., when running <tt>dpkg --unpack</tt>, or the unpack
3943 stage of <tt>dpkg --install</tt>) is as follows. In each
3944 case, if a major error occurs (unless listed below) the
3945 actions are, in general, run backwards - this means that the
3946 maintainer scripts are run with different arguments in
3947 reverse order. These are the "error unwind" calls listed
3954 If a version of the package is already installed, call
3955 <example compact="compact">
3956 <var>old-prerm</var> upgrade <var>new-version</var>
3960 If the script runs but exits with a non-zero
3961 exit status, <prgn>dpkg</prgn> will attempt:
3962 <example compact="compact">
3963 <var>new-prerm</var> failed-upgrade <var>old-version</var>
3965 If this works, the upgrade continues. If this
3966 does not work, the error unwind:
3967 <example compact="compact">
3968 <var>old-postinst</var> abort-upgrade <var>new-version</var>
3970 If this works, then the old-version is
3971 "Installed", if not, the old version is in a
3972 "Half-Configured" state.
3978 If a "conflicting" package is being removed at the same time,
3979 or if any package will be broken (due to <tt>Breaks</tt>):
3982 If <tt>--auto-deconfigure</tt> is
3983 specified, call, for each package to be deconfigured
3984 due to <tt>Breaks</tt>:
3985 <example compact="compact">
3986 <var>deconfigured's-prerm</var> deconfigure \
3987 in-favour <var>package-being-installed</var> <var>version</var>
3990 <example compact="compact">
3991 <var>deconfigured's-postinst</var> abort-deconfigure \
3992 in-favour <var>package-being-installed-but-failed</var> <var>version</var>
3994 The deconfigured packages are marked as
3995 requiring configuration, so that if
3996 <tt>--install</tt> is used they will be
3997 configured again if possible.
4000 If any packages depended on a conflicting
4001 package being removed and <tt>--auto-deconfigure</tt> is
4002 specified, call, for each such package:
4003 <example compact="compact">
4004 <var>deconfigured's-prerm</var> deconfigure \
4005 in-favour <var>package-being-installed</var> <var>version</var> \
4006 removing <var>conflicting-package</var> <var>version</var>
4009 <example compact="compact">
4010 <var>deconfigured's-postinst</var> abort-deconfigure \
4011 in-favour <var>package-being-installed-but-failed</var> <var>version</var> \
4012 removing <var>conflicting-package</var> <var>version</var>
4014 The deconfigured packages are marked as
4015 requiring configuration, so that if
4016 <tt>--install</tt> is used they will be
4017 configured again if possible.
4020 To prepare for removal of each conflicting package, call:
4021 <example compact="compact">
4022 <var>conflictor's-prerm</var> remove \
4023 in-favour <var>package</var> <var>new-version</var>
4026 <example compact="compact">
4027 <var>conflictor's-postinst</var> abort-remove \
4028 in-favour <var>package</var> <var>new-version</var>
4037 If the package is being upgraded, call:
4038 <example compact="compact">
4039 <var>new-preinst</var> upgrade <var>old-version</var>
4041 If this fails, we call:
4043 <var>new-postrm</var> abort-upgrade <var>old-version</var>
4050 <var>old-postinst</var> abort-upgrade <var>new-version</var>
4052 is called. If this works, then the old version
4053 is in an "Installed" state, or else it is left
4054 in an "Unpacked" state.
4059 If it fails, then the old version is left
4060 in an "Half-Installed" state.
4067 Otherwise, if the package had some configuration
4068 files from a previous version installed (i.e., it
4069 is in the "configuration files only" state):
4070 <example compact="compact">
4071 <var>new-preinst</var> install <var>old-version</var>
4075 <var>new-postrm</var> abort-install <var>old-version</var>
4077 If this fails, the package is left in a
4078 "Half-Installed" state, which requires a
4079 reinstall. If it works, the packages is left in
4080 a "Config-Files" state.
4083 Otherwise (i.e., the package was completely purged):
4084 <example compact="compact">
4085 <var>new-preinst</var> install
4088 <example compact="compact">
4089 <var>new-postrm</var> abort-install
4091 If the error-unwind fails, the package is in a
4092 "Half-Installed" phase, and requires a
4093 reinstall. If the error unwind works, the
4094 package is in a not installed state.
4101 The new package's files are unpacked, overwriting any
4102 that may be on the system already, for example any
4103 from the old version of the same package or from
4104 another package. Backups of the old files are kept
4105 temporarily, and if anything goes wrong the package
4106 management system will attempt to put them back as
4107 part of the error unwind.
4111 It is an error for a package to contain files which
4112 are on the system in another package, unless
4113 <tt>Replaces</tt> is used (see <ref id="replaces">).
4115 The following paragraph is not currently the case:
4116 Currently the <tt>- - force-overwrite</tt> flag is
4117 enabled, downgrading it to a warning, but this may not
4123 It is a more serious error for a package to contain a
4124 plain file or other kind of non-directory where another
4125 package has a directory (again, unless
4126 <tt>Replaces</tt> is used). This error can be
4127 overridden if desired using
4128 <tt>--force-overwrite-dir</tt>, but this is not
4133 Packages which overwrite each other's files produce
4134 behavior which, though deterministic, is hard for the
4135 system administrator to understand. It can easily
4136 lead to "missing" programs if, for example, a package
4137 is installed which overwrites a file from another
4138 package, and is then removed again.<footnote>
4139 Part of the problem is due to what is arguably a
4140 bug in <prgn>dpkg</prgn>.
4145 A directory will never be replaced by a symbolic link
4146 to a directory or vice versa; instead, the existing
4147 state (symlink or not) will be left alone and
4148 <prgn>dpkg</prgn> will follow the symlink if there is
4157 If the package is being upgraded, call
4158 <example compact="compact">
4159 <var>old-postrm</var> upgrade <var>new-version</var>
4163 If this fails, <prgn>dpkg</prgn> will attempt:
4164 <example compact="compact">
4165 <var>new-postrm</var> failed-upgrade <var>old-version</var>
4167 If this works, installation continues. If not,
4169 <example compact="compact">
4170 <var>old-preinst</var> abort-upgrade <var>new-version</var>
4172 If this fails, the old version is left in a
4173 "Half-Installed" state. If it works, dpkg now
4175 <example compact="compact">
4176 <var>new-postrm</var> abort-upgrade <var>old-version</var>
4178 If this fails, the old version is left in a
4179 "Half-Installed" state. If it works, dpkg now
4181 <example compact="compact">
4182 <var>old-postinst</var> abort-upgrade <var>new-version</var>
4184 If this fails, the old version is in an
4191 This is the point of no return - if
4192 <prgn>dpkg</prgn> gets this far, it won't back off
4193 past this point if an error occurs. This will
4194 leave the package in a fairly bad state, which
4195 will require a successful re-installation to clear
4196 up, but it's when <prgn>dpkg</prgn> starts doing
4197 things that are irreversible.
4202 Any files which were in the old version of the package
4203 but not in the new are removed.
4207 The new file list replaces the old.
4211 The new maintainer scripts replace the old.
4215 Any packages all of whose files have been overwritten
4216 during the installation, and which aren't required for
4217 dependencies, are considered to have been removed.
4218 For each such package
4221 <prgn>dpkg</prgn> calls:
4222 <example compact="compact">
4223 <var>disappearer's-postrm</var> disappear \
4224 <var>overwriter</var> <var>overwriter-version</var>
4228 The package's maintainer scripts are removed.
4231 It is noted in the status database as being in a
4232 sane state, namely not installed (any conffiles
4233 it may have are ignored, rather than being
4234 removed by <prgn>dpkg</prgn>). Note that
4235 disappearing packages do not have their prerm
4236 called, because <prgn>dpkg</prgn> doesn't know
4237 in advance that the package is going to
4244 Any files in the package we're unpacking that are also
4245 listed in the file lists of other packages are removed
4246 from those lists. (This will lobotomize the file list
4247 of the "conflicting" package if there is one.)
4251 The backup files made during installation, above, are
4257 The new package's status is now sane, and recorded as
4262 Here is another point of no return - if the
4263 conflicting package's removal fails we do not unwind
4264 the rest of the installation; the conflicting package
4265 is left in a half-removed limbo.
4270 If there was a conflicting package we go and do the
4271 removal actions (described below), starting with the
4272 removal of the conflicting package's files (any that
4273 are also in the package being installed have already
4274 been removed from the conflicting package's file list,
4275 and so do not get removed now).
4281 <sect id="configdetails"><heading>Details of configuration</heading>
4284 When we configure a package (this happens with <tt>dpkg
4285 --install</tt> and <tt>dpkg --configure</tt>), we first
4286 update any <tt>conffile</tt>s and then call:
4287 <example compact="compact">
4288 <var>postinst</var> configure <var>most-recently-configured-version</var>
4293 No attempt is made to unwind after errors during
4294 configuration. If the configuration fails, the package is in
4295 a "Failed Config" state, and an error message is generated.
4299 If there is no most recently configured version
4300 <prgn>dpkg</prgn> will pass a null argument.
4303 Historical note: Truly ancient (pre-1997) versions of
4304 <prgn>dpkg</prgn> passed <tt><unknown></tt>
4305 (including the angle brackets) in this case. Even older
4306 ones did not pass a second argument at all, under any
4307 circumstance. Note that upgrades using such an old dpkg
4308 version are unlikely to work for other reasons, even if
4309 this old argument behavior is handled by your postinst script.
4315 <sect id="removedetails"><heading>Details of removal and/or
4316 configuration purging</heading>
4322 <example compact="compact">
4323 <var>prerm</var> remove
4327 If prerm fails during replacement due to conflict
4329 <var>conflictor's-postinst</var> abort-remove \
4330 in-favour <var>package</var> <var>new-version</var>
4334 <var>postinst</var> abort-remove
4338 If this fails, the package is in a "Half-Configured"
4339 state, or else it remains "Installed".
4343 The package's files are removed (except <tt>conffile</tt>s).
4346 <example compact="compact">
4347 <var>postrm</var> remove
4351 If it fails, there's no error unwind, and the package is in
4352 an "Half-Installed" state.
4357 All the maintainer scripts except the <prgn>postrm</prgn>
4362 If we aren't purging the package we stop here. Note
4363 that packages which have no <prgn>postrm</prgn> and no
4364 <tt>conffile</tt>s are automatically purged when
4365 removed, as there is no difference except for the
4366 <prgn>dpkg</prgn> status.
4370 The <tt>conffile</tt>s and any backup files
4371 (<tt>~</tt>-files, <tt>#*#</tt> files,
4372 <tt>%</tt>-files, <tt>.dpkg-{old,new,tmp}</tt>, etc.)
4377 <example compact="compact">
4378 <var>postrm</var> purge
4382 If this fails, the package remains in a "Config-Files"
4387 The package's file list is removed.
4396 <chapt id="relationships">
4397 <heading>Declaring relationships between packages</heading>
4399 <sect id="depsyntax">
4400 <heading>Syntax of relationship fields</heading>
4403 These fields all have a uniform syntax. They are a list of
4404 package names separated by commas.
4408 In the <tt>Depends</tt>, <tt>Recommends</tt>,
4409 <tt>Suggests</tt>, <tt>Pre-Depends</tt>,
4410 <tt>Build-Depends</tt> and <tt>Build-Depends-Indep</tt>
4411 control fields of the package, which declare
4412 dependencies on other packages, the package names listed may
4413 also include lists of alternative package names, separated
4414 by vertical bar (pipe) symbols <tt>|</tt>. In such a case,
4415 if any one of the alternative packages is installed, that
4416 part of the dependency is considered to be satisfied.
4420 All of the fields except for <tt>Provides</tt> may restrict
4421 their applicability to particular versions of each named
4422 package. This is done in parentheses after each individual
4423 package name; the parentheses should contain a relation from
4424 the list below followed by a version number, in the format
4425 described in <ref id="f-Version">.
4429 The relations allowed are <tt><<</tt>, <tt><=</tt>,
4430 <tt>=</tt>, <tt>>=</tt> and <tt>>></tt> for
4431 strictly earlier, earlier or equal, exactly equal, later or
4432 equal and strictly later, respectively. The deprecated
4433 forms <tt><</tt> and <tt>></tt> were used to mean
4434 earlier/later or equal, rather than strictly earlier/later,
4435 so they should not appear in new packages (though
4436 <prgn>dpkg</prgn> still supports them).
4440 Whitespace may appear at any point in the version
4441 specification subject to the rules in <ref
4442 id="controlsyntax">, and must appear where it's necessary to
4443 disambiguate; it is not otherwise significant. All of the
4444 relationship fields may span multiple lines. For
4445 consistency and in case of future changes to
4446 <prgn>dpkg</prgn> it is recommended that a single space be
4447 used after a version relationship and before a version
4448 number; it is also conventional to put a single space after
4449 each comma, on either side of each vertical bar, and before
4450 each open parenthesis. When wrapping a relationship field, it
4451 is conventional to do so after a comma and before the space
4452 following that comma.
4456 For example, a list of dependencies might appear as:
4457 <example compact="compact">
4460 Depends: libc6 (>= 2.2.1), exim | mail-transport-agent
4465 Relationships may be restricted to a certain set of
4466 architectures. This is indicated in brackets after each
4467 individual package name and the optional version specification.
4468 The brackets enclose a list of Debian architecture names
4469 separated by whitespace. Exclamation marks may be prepended to
4470 each of the names. (It is not permitted for some names to be
4471 prepended with exclamation marks while others aren't.)
4475 For build relationship fields
4476 (<tt>Build-Depends</tt>, <tt>Build-Depends-Indep</tt>,
4477 <tt>Build-Conflicts</tt> and <tt>Build-Conflicts-Indep</tt>), if
4478 the current Debian host architecture is not in this list and
4479 there are no exclamation marks in the list, or it is in the list
4480 with a prepended exclamation mark, the package name and the
4481 associated version specification are ignored completely for the
4482 purposes of defining the relationships.
4487 <example compact="compact">
4489 Build-Depends-Indep: texinfo
4490 Build-Depends: kernel-headers-2.2.10 [!hurd-i386],
4491 hurd-dev [hurd-i386], gnumach-dev [hurd-i386]
4493 requires <tt>kernel-headers-2.2.10</tt> on all architectures
4494 other than hurd-i386 and requires <tt>hurd-dev</tt> and
4495 <tt>gnumach-dev</tt> only on hurd-i386.
4499 For binary relationship fields, the architecture restriction
4500 syntax is only supported in the source package control
4501 file <file>debian/control</file>. When the corresponding binary
4502 package control file is generated, the relationship will either
4503 be omitted or included without the architecture restriction
4504 based on the architecture of the binary package. This means
4505 that architecture restrictions must not be used in binary
4506 relationship fields for architecture-independent packages
4507 (<tt>Architecture: all</tt>).
4512 <example compact="compact">
4513 Depends: foo [i386], bar [amd64]
4515 becomes <tt>Depends: foo</tt> when the package is built on
4516 the <tt>i386</tt> architecture, <tt>Depends: bar</tt> when the
4517 package is built on the <tt>amd64</tt> architecture, and omitted
4518 entirely in binary packages built on all other architectures.
4522 If the architecture-restricted dependency is part of a set of
4523 alternatives using <tt>|</tt>, that alternative is ignored
4524 completely on architectures that do not match the restriction.
4526 <example compact="compact">
4527 Build-Depends: foo [!i386] | bar [!amd64]
4529 is equivalent to <tt>bar</tt> on the i386 architecture, to
4530 <tt>foo</tt> on the amd64 architecture, and to <tt>foo |
4531 bar</tt> on all other architectures.
4535 Relationships may also be restricted to a certain set of
4536 architectures using architecture wildcards. The syntax for
4537 declaring such restrictions is the same as declaring
4538 restrictions using a certain set of architectures without
4539 architecture wildcards. For example:
4540 <example compact="compact">
4541 Build-Depends: foo [linux-any], bar [any-i386], baz [!linux-any]
4543 is equivalent to <tt>foo</tt> on architectures using the Linux
4544 kernel and any cpu, <tt>bar</tt> on architectures using any
4545 kernel and an i386 cpu, and <tt>baz</tt> on any architecture
4546 using a kernel other than Linux.
4550 Note that the binary package relationship fields such as
4551 <tt>Depends</tt> appear in one of the binary package
4552 sections of the control file, whereas the build-time
4553 relationships such as <tt>Build-Depends</tt> appear in the
4554 source package section of the control file (which is the
4559 <sect id="binarydeps">
4560 <heading>Binary Dependencies - <tt>Depends</tt>,
4561 <tt>Recommends</tt>, <tt>Suggests</tt>, <tt>Enhances</tt>,
4562 <tt>Pre-Depends</tt>
4566 Packages can declare in their control file that they have
4567 certain relationships to other packages - for example, that
4568 they may not be installed at the same time as certain other
4569 packages, and/or that they depend on the presence of others.
4573 This is done using the <tt>Depends</tt>, <tt>Pre-Depends</tt>,
4574 <tt>Recommends</tt>, <tt>Suggests</tt>, <tt>Enhances</tt>,
4575 <tt>Breaks</tt> and <tt>Conflicts</tt> control fields.
4576 <tt>Breaks</tt> is described in <ref id="breaks">, and
4577 <tt>Conflicts</tt> is described in <ref id="conflicts">. The
4578 rest are described below.
4582 These seven fields are used to declare a dependency
4583 relationship by one package on another. Except for
4584 <tt>Enhances</tt> and <tt>Breaks</tt>, they appear in the
4585 depending (binary) package's control file.
4586 (<tt>Enhances</tt> appears in the recommending package's
4587 control file, and <tt>Breaks</tt> appears in the version of
4588 depended-on package which causes the named package to
4593 A <tt>Depends</tt> field takes effect <em>only</em> when a
4594 package is to be configured. It does not prevent a package
4595 being on the system in an unconfigured state while its
4596 dependencies are unsatisfied, and it is possible to replace
4597 a package whose dependencies are satisfied and which is
4598 properly installed with a different version whose
4599 dependencies are not and cannot be satisfied; when this is
4600 done the depending package will be left unconfigured (since
4601 attempts to configure it will give errors) and will not
4602 function properly. If it is necessary, a
4603 <tt>Pre-Depends</tt> field can be used, which has a partial
4604 effect even when a package is being unpacked, as explained
4605 in detail below. (The other three dependency fields,
4606 <tt>Recommends</tt>, <tt>Suggests</tt> and
4607 <tt>Enhances</tt>, are only used by the various front-ends
4608 to <prgn>dpkg</prgn> such as <prgn>apt-get</prgn>,
4609 <prgn>aptitude</prgn>, and <prgn>dselect</prgn>.)
4613 For this reason packages in an installation run are usually
4614 all unpacked first and all configured later; this gives
4615 later versions of packages with dependencies on later
4616 versions of other packages the opportunity to have their
4617 dependencies satisfied.
4621 In case of circular dependencies, since installation or
4622 removal order honoring the dependency order can't be
4623 established, dependency loops are broken at some point
4624 (based on rules below), and some packages may not be able to
4625 rely on their dependencies being present when being
4626 installed or removed, depending on which side of the break
4627 of the circular dependency loop they happen to be on. If one
4628 of the packages in the loop has no postinst script, then the
4629 cycle will be broken at that package, so as to ensure that
4630 all postinst scripts run with the dependencies properly
4631 configured if this is possible. Otherwise the breaking point
4636 The <tt>Depends</tt> field thus allows package maintainers
4637 to impose an order in which packages should be configured.
4641 The meaning of the five dependency fields is as follows:
4643 <tag><tt>Depends</tt></tag>
4646 This declares an absolute dependency. A package will
4647 not be configured unless all of the packages listed in
4648 its <tt>Depends</tt> field have been correctly
4653 The <tt>Depends</tt> field should be used if the
4654 depended-on package is required for the depending
4655 package to provide a significant amount of
4660 The <tt>Depends</tt> field should also be used if the
4661 <prgn>postinst</prgn>, <prgn>prerm</prgn> or
4662 <prgn>postrm</prgn> scripts require the package to be
4663 present in order to run. Note, however, that the
4664 <prgn>postrm</prgn> cannot rely on any non-essential
4665 packages to be present during the <tt>purge</tt>
4669 <tag><tt>Recommends</tt></tag>
4672 This declares a strong, but not absolute, dependency.
4676 The <tt>Recommends</tt> field should list packages
4677 that would be found together with this one in all but
4678 unusual installations.
4682 <tag><tt>Suggests</tt></tag>
4684 This is used to declare that one package may be more
4685 useful with one or more others. Using this field
4686 tells the packaging system and the user that the
4687 listed packages are related to this one and can
4688 perhaps enhance its usefulness, but that installing
4689 this one without them is perfectly reasonable.
4692 <tag><tt>Enhances</tt></tag>
4694 This field is similar to Suggests but works in the
4695 opposite direction. It is used to declare that a
4696 package can enhance the functionality of another
4700 <tag><tt>Pre-Depends</tt></tag>
4703 This field is like <tt>Depends</tt>, except that it
4704 also forces <prgn>dpkg</prgn> to complete installation
4705 of the packages named before even starting the
4706 installation of the package which declares the
4707 pre-dependency, as follows:
4711 When a package declaring a pre-dependency is about to
4712 be <em>unpacked</em> the pre-dependency can be
4713 satisfied if the depended-on package is either fully
4714 configured, <em>or even if</em> the depended-on
4715 package(s) are only unpacked or in the "Half-Configured"
4716 state, provided that they have been configured
4717 correctly at some point in the past (and not removed
4718 or partially removed since). In this case, both the
4719 previously-configured and currently unpacked or
4720 "Half-Configured" versions must satisfy any version
4721 clause in the <tt>Pre-Depends</tt> field.
4725 When the package declaring a pre-dependency is about
4726 to be <em>configured</em>, the pre-dependency will be
4727 treated as a normal <tt>Depends</tt>, that is, it will
4728 be considered satisfied only if the depended-on
4729 package has been correctly configured.
4733 <tt>Pre-Depends</tt> should be used sparingly,
4734 preferably only by packages whose premature upgrade or
4735 installation would hamper the ability of the system to
4736 continue with any upgrade that might be in progress.
4740 <tt>Pre-Depends</tt> are also required if the
4741 <prgn>preinst</prgn> script depends on the named
4742 package. It is best to avoid this situation if
4750 When selecting which level of dependency to use you should
4751 consider how important the depended-on package is to the
4752 functionality of the one declaring the dependency. Some
4753 packages are composed of components of varying degrees of
4754 importance. Such a package should list using
4755 <tt>Depends</tt> the package(s) which are required by the
4756 more important components. The other components'
4757 requirements may be mentioned as Suggestions or
4758 Recommendations, as appropriate to the components' relative
4764 <heading>Packages which break other packages - <tt>Breaks</tt></heading>
4767 When one binary package declares that it breaks another,
4768 <prgn>dpkg</prgn> will refuse to allow the package which
4769 declares <tt>Breaks</tt> be installed unless the broken
4770 package is deconfigured first, and it will refuse to
4771 allow the broken package to be reconfigured.
4775 A package will not be regarded as causing breakage merely
4776 because its configuration files are still installed; it must
4777 be at least "Half-Installed".
4781 A special exception is made for packages which declare that
4782 they break their own package name or a virtual package which
4783 they provide (see below): this does not count as a real
4788 Normally a <tt>Breaks</tt> entry will have an "earlier than"
4789 version clause; such a <tt>Breaks</tt> is introduced in the
4790 version of an (implicit or explicit) dependency which violates
4791 an assumption or reveals a bug in earlier versions of the broken
4792 package, or which takes over a file from earlier versions of the
4793 package named in <tt>Breaks</tt>. This use of <tt>Breaks</tt>
4794 will inform higher-level package management tools that the
4795 broken package must be upgraded before the new one.
4799 If the breaking package also overwrites some files from the
4800 older package, it should use <tt>Replaces</tt> to ensure this
4801 goes smoothly. See <ref id="replaces"> for a full discussion
4802 of taking over files from other packages, including how to
4803 use <tt>Breaks</tt> in those cases.
4807 Many of the cases where <tt>Breaks</tt> should be used were
4808 previously handled with <tt>Conflicts</tt>
4809 because <tt>Breaks</tt> did not yet exist.
4810 Many <tt>Conflicts</tt> fields should now be <tt>Breaks</tt>.
4811 See <ref id="conflicts"> for more information about the
4816 <sect id="conflicts">
4817 <heading>Conflicting binary packages - <tt>Conflicts</tt></heading>
4820 When one binary package declares a conflict with another
4821 using a <tt>Conflicts</tt> field, <prgn>dpkg</prgn> will
4822 refuse to allow them to be installed on the system at the
4823 same time. This is a stronger restriction than <tt>Breaks</tt>,
4824 which just prevents both packages from being configured at the
4825 same time. Conflicting packages cannot be unpacked on the
4826 system at the same time.
4830 If one package is to be installed, the other must be removed
4831 first. If the package being installed is marked as replacing
4832 (see <ref id="replaces">, but note that <tt>Breaks</tt> should
4833 normally be used in this case) the one on the system, or the one
4834 on the system is marked as deselected, or both packages are
4835 marked <tt>Essential</tt>, then <prgn>dpkg</prgn> will
4836 automatically remove the package which is causing the conflict.
4837 Otherwise, it will halt the installation of the new package with
4838 an error. This mechanism is specifically designed to produce an
4839 error when the installed package is <tt>Essential</tt>, but the
4844 A package will not cause a conflict merely because its
4845 configuration files are still installed; it must be at least
4850 A special exception is made for packages which declare a
4851 conflict with their own package name, or with a virtual
4852 package which they provide (see below): this does not
4853 prevent their installation, and allows a package to conflict
4854 with others providing a replacement for it. You use this
4855 feature when you want the package in question to be the only
4856 package providing some feature.
4860 Normally, <tt>Breaks</tt> should be used instead
4861 of <tt>Conflicts</tt> since <tt>Conflicts</tt> imposes a
4862 stronger restriction on the ordering of package installation or
4863 upgrade and can make it more difficult for the package manager
4864 to find a correct solution to an upgrade or installation
4865 problem. <tt>Breaks</tt> should be used
4867 <item>when moving a file from one package to another (see
4868 <ref id="replaces">),</item>
4869 <item>when splitting a package (a special case of the previous
4871 <item>when the breaking package exposes a bug in or interacts
4872 badly with particular versions of the broken
4875 <tt>Conflicts</tt> should be used
4877 <item>when two packages provide the same file and will
4878 continue to do so,</item>
4879 <item>in conjunction with <tt>Provides</tt> when only one
4880 package providing a given virtual facility may be installed
4881 at a time (see <ref id="virtual">),</item>
4882 <item>in other cases where one must prevent simultaneous
4883 installation of two packages for reasons that are ongoing
4884 (not fixed in a later version of one of the packages) or
4885 that must prevent both packages from being unpacked at the
4886 same time, not just configured.</item>
4888 Be aware that adding <tt>Conflicts</tt> is normally not the best
4889 solution when two packages provide the same files. Depending on
4890 the reason for that conflict, using alternatives or renaming the
4891 files is often a better approach. See, for
4892 example, <ref id="binaries">.
4896 Neither <tt>Breaks</tt> nor <tt>Conflicts</tt> should be used
4897 unless two packages cannot be installed at the same time or
4898 installing them both causes one of them to be broken or
4899 unusable. Having similar functionality or performing the same
4900 tasks as another package is not sufficient reason to
4901 declare <tt>Breaks</tt> or <tt>Conflicts</tt> with that package.
4905 A <tt>Conflicts</tt> entry may have an "earlier than" version
4906 clause if the reason for the conflict is corrected in a later
4907 version of one of the packages. However, normally the presence
4908 of an "earlier than" version clause is a sign
4909 that <tt>Breaks</tt> should have been used instead. An "earlier
4910 than" version clause in <tt>Conflicts</tt>
4911 prevents <prgn>dpkg</prgn> from upgrading or installing the
4912 package which declares such a conflict until the upgrade or
4913 removal of the conflicted-with package has been completed, which
4914 is a strong restriction.
4918 <sect id="virtual"><heading>Virtual packages - <tt>Provides</tt>
4922 As well as the names of actual ("concrete") packages, the
4923 package relationship fields <tt>Depends</tt>,
4924 <tt>Recommends</tt>, <tt>Suggests</tt>, <tt>Enhances</tt>,
4925 <tt>Pre-Depends</tt>, <tt>Breaks</tt>, <tt>Conflicts</tt>,
4926 <tt>Build-Depends</tt>, <tt>Build-Depends-Indep</tt>,
4927 <tt>Build-Conflicts</tt> and <tt>Build-Conflicts-Indep</tt>
4928 may mention "virtual packages".
4932 A <em>virtual package</em> is one which appears in the
4933 <tt>Provides</tt> control field of another package. The effect
4934 is as if the package(s) which provide a particular virtual
4935 package name had been listed by name everywhere the virtual
4936 package name appears. (See also <ref id="virtual_pkg">)
4940 If there are both concrete and virtual packages of the same
4941 name, then the dependency may be satisfied (or the conflict
4942 caused) by either the concrete package with the name in
4943 question or any other concrete package which provides the
4944 virtual package with the name in question. This is so that,
4945 for example, supposing we have
4946 <example compact="compact">
4949 </example> and someone else releases an enhanced version of
4950 the <tt>bar</tt> package they can say:
4951 <example compact="compact">
4955 and the <tt>bar-plus</tt> package will now also satisfy the
4956 dependency for the <tt>foo</tt> package.
4960 If a relationship field has a version number attached, only real
4961 packages will be considered to see whether the relationship is
4962 satisfied (or the prohibition violated, for a conflict or
4963 breakage). In other words, if a version number is specified,
4964 this is a request to ignore all <tt>Provides</tt> for that
4965 package name and consider only real packages. The package
4966 manager will assume that a package providing that virtual
4967 package is not of the "right" version. A <tt>Provides</tt>
4968 field may not contain version numbers, and the version number of
4969 the concrete package which provides a particular virtual package
4970 will not be considered when considering a dependency on or
4971 conflict with the virtual package name.<footnote>
4972 It is possible that a future release of <prgn>dpkg</prgn> may
4973 add the ability to specify a version number for each virtual
4974 package it provides. This feature is not yet present,
4975 however, and is expected to be used only infrequently.
4980 To specify which of a set of real packages should be the default
4981 to satisfy a particular dependency on a virtual package, list
4982 the real package as an alternative before the virtual one.
4986 If the virtual package represents a facility that can only be
4987 provided by one real package at a time, such as
4988 the <package>mail-transport-agent</package> virtual package that
4989 requires installation of a binary that would conflict with all
4990 other providers of that virtual package (see
4991 <ref id="mail-transport-agents">), all packages providing that
4992 virtual package should also declare a conflict with it
4993 using <tt>Conflicts</tt>. This will ensure that at most one
4994 provider of that virtual package is unpacked or installed at a
4999 <sect id="replaces"><heading>Overwriting files and replacing
5000 packages - <tt>Replaces</tt></heading>
5003 Packages can declare in their control file that they should
5004 overwrite files in certain other packages, or completely replace
5005 other packages. The <tt>Replaces</tt> control field has these
5006 two distinct purposes.
5009 <sect1><heading>Overwriting files in other packages</heading>
5012 It is usually an error for a package to contain files which
5013 are on the system in another package. However, if the
5014 overwriting package declares that it <tt>Replaces</tt> the one
5015 containing the file being overwritten, then <prgn>dpkg</prgn>
5016 will replace the file from the old package with that from the
5017 new. The file will no longer be listed as "owned" by the old
5018 package and will be taken over by the new package.
5019 Normally, <tt>Breaks</tt> should be used in conjunction
5020 with <tt>Replaces</tt>.<footnote>
5021 To see why <tt>Breaks</tt> is normally needed in addition
5022 to <tt>Replaces</tt>, consider the case of a file in the
5023 package <package>foo</package> being taken over by the
5024 package <package>foo-data</package>.
5025 <tt>Replaces</tt> will allow <package>foo-data</package> to
5026 be installed and take over that file. However,
5027 without <tt>Breaks</tt>, nothing
5028 requires <package>foo</package> to be upgraded to a newer
5029 version that knows it does not include that file and instead
5030 depends on <package>foo-data</package>. Nothing would
5031 prevent the new <package>foo-data</package> package from
5032 being installed and then removed, removing the file that it
5033 took over from <package>foo</package>. After that
5034 operation, the package manager would think the system was in
5035 a consistent state, but the <package>foo</package> package
5036 would be missing one of its files.
5041 For example, if a package <package>foo</package> is split
5042 into <package>foo</package> and <package>foo-data</package>
5043 starting at version 1.2-3, <package>foo-data</package> would
5045 <example compact="compact">
5046 Replaces: foo (<< 1.2-3)
5047 Breaks: foo (<< 1.2-3)
5049 in its control file. The new version of the
5050 package <package>foo</package> would normally have the field
5051 <example compact="compact">
5052 Depends: foo-data (>= 1.2-3)
5054 (or possibly <tt>Recommends</tt> or even <tt>Suggests</tt> if
5055 the files moved into <package>foo-data</package> are not
5056 required for normal operation).
5060 If a package is completely replaced in this way, so that
5061 <prgn>dpkg</prgn> does not know of any files it still
5062 contains, it is considered to have "disappeared". It will
5063 be marked as not wanted on the system (selected for
5064 removal) and not installed. Any <tt>conffile</tt>s
5065 details noted for the package will be ignored, as they
5066 will have been taken over by the overwriting package. The
5067 package's <prgn>postrm</prgn> script will be run with a
5068 special argument to allow the package to do any final
5069 cleanup required. See <ref id="mscriptsinstact">.
5071 Replaces is a one way relationship. You have to install
5072 the replacing package after the replaced package.
5077 For this usage of <tt>Replaces</tt>, virtual packages (see
5078 <ref id="virtual">) are not considered when looking at a
5079 <tt>Replaces</tt> field. The packages declared as being
5080 replaced must be mentioned by their real names.
5084 This usage of <tt>Replaces</tt> only takes effect when both
5085 packages are at least partially on the system at once. It is
5086 not relevant if the packages conflict unless the conflict has
5091 <sect1><heading>Replacing whole packages, forcing their
5095 Second, <tt>Replaces</tt> allows the packaging system to
5096 resolve which package should be removed when there is a
5097 conflict (see <ref id="conflicts">). This usage only takes
5098 effect when the two packages <em>do</em> conflict, so that the
5099 two usages of this field do not interfere with each other.
5103 In this situation, the package declared as being replaced
5104 can be a virtual package, so for example, all mail
5105 transport agents (MTAs) would have the following fields in
5106 their control files:
5107 <example compact="compact">
5108 Provides: mail-transport-agent
5109 Conflicts: mail-transport-agent
5110 Replaces: mail-transport-agent
5112 ensuring that only one MTA can be installed at any one
5113 time. See <ref id="virtual"> for more information about this
5118 <sect id="sourcebinarydeps">
5119 <heading>Relationships between source and binary packages -
5120 <tt>Build-Depends</tt>, <tt>Build-Depends-Indep</tt>,
5121 <tt>Build-Conflicts</tt>, <tt>Build-Conflicts-Indep</tt>
5125 Source packages that require certain binary packages to be
5126 installed or absent at the time of building the package
5127 can declare relationships to those binary packages.
5131 This is done using the <tt>Build-Depends</tt>,
5132 <tt>Build-Depends-Indep</tt>, <tt>Build-Conflicts</tt> and
5133 <tt>Build-Conflicts-Indep</tt> control fields.
5137 Build-dependencies on "build-essential" binary packages can be
5138 omitted. Please see <ref id="pkg-relations"> for more information.
5142 The dependencies and conflicts they define must be satisfied
5143 (as defined earlier for binary packages) in order to invoke
5144 the targets in <tt>debian/rules</tt>, as follows:<footnote>
5146 There is no Build-Depends-Arch; this role is essentially
5147 met with Build-Depends. Anyone building the
5148 <tt>build-indep</tt> and <tt>binary-indep</tt> targets is
5149 assumed to be building the whole package, and therefore
5150 installation of all build dependencies is required.
5153 The autobuilders use <tt>dpkg-buildpackage -B</tt>, which
5154 calls <tt>build</tt>, not <tt>build-arch</tt> since it does
5155 not yet know how to check for its existence, and
5156 <tt>binary-arch</tt>. The purpose of the original split
5157 between <tt>Build-Depends</tt> and
5158 <tt>Build-Depends-Indep</tt> was so that the autobuilders
5159 wouldn't need to install extra packages needed only for the
5160 binary-indep targets. But without a build-arch/build-indep
5161 split, this didn't work, since most of the work is done in
5162 the build target, not in the binary target.
5166 <tag><tt>clean</tt>, <tt>build-arch</tt>, and
5167 <tt>binary-arch</tt></tag>
5169 Only the <tt>Build-Depends</tt> and <tt>Build-Conflicts</tt>
5170 fields must be satisfied when these targets are invoked.
5172 <tag><tt>build</tt>, <tt>build-indep</tt>, <tt>binary</tt>,
5173 and <tt>binary-indep</tt></tag>
5175 The <tt>Build-Depends</tt>, <tt>Build-Conflicts</tt>,
5176 <tt>Build-Depends-Indep</tt>, and
5177 <tt>Build-Conflicts-Indep</tt> fields must be satisfied when
5178 these targets are invoked.
5186 <chapt id="sharedlibs"><heading>Shared libraries</heading>
5189 Packages containing shared libraries must be constructed with
5190 a little care to make sure that the shared library is always
5191 available. This is especially important for packages whose
5192 shared libraries are vitally important, such as the C library
5193 (currently <tt>libc6</tt>).
5197 This section deals only with public shared libraries: shared
5198 libraries that are placed in directories searched by the dynamic
5199 linker by default or which are intended to be linked against
5200 normally and possibly used by other, independent packages. Shared
5201 libraries that are internal to a particular package or that are
5202 only loaded as dynamic modules are not covered by this section and
5203 are not subject to its requirements.
5207 A shared library is identified by the <tt>SONAME</tt> attribute
5208 stored in its dynamic section. When a binary is linked against a
5209 shared library, the <tt>SONAME</tt> of the shared library is
5210 recorded in the binary's <tt>NEEDED</tt> section so that the
5211 dynamic linker knows that library must be loaded at runtime. The
5212 shared library file's full name (which usually contains additional
5213 version information not needed in the <tt>SONAME</tt>) is
5214 therefore normally not referenced directly. Instead, the shared
5215 library is loaded by its <tt>SONAME</tt>, which exists on the file
5216 system as a symlink pointing to the full name of the shared
5217 library. This symlink must be provided by the
5218 package. <ref id="sharedlibs-runtime"> describes how to do this.
5220 This is a convention of shared library versioning, but not a
5221 requirement. Some libraries use the <tt>SONAME</tt> as the full
5222 library file name instead and therefore do not need a symlink.
5223 Most, however, encode additional information about
5224 backwards-compatible revisions as a minor version number in the
5225 file name. The <tt>SONAME</tt> itself only changes when
5226 binaries linked with the earlier version of the shared library
5227 may no longer work, but the filename may change with each
5228 release of the library. See <ref id="sharedlibs-runtime"> for
5234 When linking a binary or another shared library against a shared
5235 library, the <tt>SONAME</tt> for that shared library is not yet
5236 known. Instead, the shared library is found by looking for a file
5237 matching the library name with <tt>.so</tt> appended. This file
5238 exists on the file system as a symlink pointing to the shared
5243 Shared libraries are normally split into several binary packages.
5244 The <tt>SONAME</tt> symlink is installed by the runtime shared
5245 library package, and the bare <tt>.so</tt> symlink is installed in
5246 the development package since it's only used when linking binaries
5247 or shared libraries. However, there are some exceptions for
5248 unusual shared libraries or for shared libraries that are also
5249 loaded as dynamic modules by other programs.
5253 This section is primarily concerned with how the separation of
5254 shared libraries into multiple packages should be done and how
5255 dependencies on and between shared library binary packages are
5256 managed in Debian. <ref id="libraries"> should be read in
5257 conjunction with this section and contains additional rules for
5258 the files contained in the shared library packages.
5261 <sect id="sharedlibs-runtime">
5262 <heading>Run-time shared libraries</heading>
5265 The run-time shared library must be placed in a package
5266 whose name changes whenever the <tt>SONAME</tt> of the shared
5267 library changes. This allows several versions of the shared
5268 library to be installed at the same time, allowing installation
5269 of the new version of the shared library without immediately
5270 breaking binaries that depend on the old version. Normally, the
5271 run-time shared library and its <tt>SONAME</tt> symlink should
5272 be placed in a package named
5273 <package><var>libraryname</var><var>soversion</var></package>,
5274 where <var>soversion</var> is the version number in
5275 the <tt>SONAME</tt> of the shared library.
5276 See <ref id="shlibs"> for detailed information on how to
5277 determine this version. Alternatively, if it would be confusing
5278 to directly append <var>soversion</var>
5279 to <var>libraryname</var> (if, for example, <var>libraryname</var>
5280 itself ends in a number), you should use
5281 <package><var>libraryname</var>-<var>soversion</var></package>
5286 If you have several shared libraries built from the same source
5287 tree, you may lump them all together into a single shared
5288 library package provided that all of their <tt>SONAME</tt>s will
5289 always change together. Be aware that this is not normally the
5290 case, and if the <tt>SONAME</tt>s do not change together,
5291 upgrading such a merged shared library package will be
5292 unnecessarily difficult because of file conflicts with the old
5293 version of the package. When in doubt, always split shared
5294 library packages so that each binary package installs a single
5299 Every time the shared library ABI changes in a way that may
5300 break binaries linked against older versions of the shared
5301 library, the <tt>SONAME</tt> of the library and the
5302 corresponding name for the binary package containing the runtime
5303 shared library should change. Normally, this means
5304 the <tt>SONAME</tt> should change any time an interface is
5305 removed from the shared library or the signature of an interface
5306 (the number of parameters or the types of parameters that it
5307 takes, for example) is changed. This practice is vital to
5308 allowing clean upgrades from older versions of the package and
5309 clean transitions between the old ABI and new ABI without having
5310 to upgrade every affected package simultaneously.
5314 The <tt>SONAME</tt> and binary package name need not, and indeed
5315 normally should not, change if new interfaces are added but none
5316 are removed or changed, since this will not break binaries
5317 linked against the old shared library. Correct versioning of
5318 dependencies on the newer shared library by binaries that use
5319 the new interfaces is handled via
5320 the <qref id="sharedlibs-shlibdeps"><tt>shlibs</tt>
5321 system</qref> or via symbols files (see
5322 <manref name="deb-symbols" section="5">).
5326 The package should install the shared libraries under
5327 their normal names. For example, the <package>libgdbm3</package>
5328 package should install <file>libgdbm.so.3.0.0</file> as
5329 <file>/usr/lib/libgdbm.so.3.0.0</file>. The files should not be
5330 renamed or re-linked by any <prgn>prerm</prgn> or
5331 <prgn>postrm</prgn> scripts; <prgn>dpkg</prgn> will take care
5332 of renaming things safely without affecting running programs,
5333 and attempts to interfere with this are likely to lead to
5338 Shared libraries should not be installed executable, since
5339 the dynamic linker does not require this and trying to
5340 execute a shared library usually results in a core dump.
5344 The run-time library package should include the symbolic link for
5345 the <tt>SONAME</tt> that <prgn>ldconfig</prgn> would create for
5346 the shared libraries. For example,
5347 the <package>libgdbm3</package> package should include a symbolic
5348 link from <file>/usr/lib/libgdbm.so.3</file> to
5349 <file>libgdbm.so.3.0.0</file>. This is needed so that the dynamic
5350 linker (for example <prgn>ld.so</prgn> or
5351 <prgn>ld-linux.so.*</prgn>) can find the library between the
5352 time that <prgn>dpkg</prgn> installs it and the time that
5353 <prgn>ldconfig</prgn> is run in the <prgn>postinst</prgn>
5355 The package management system requires the library to be
5356 placed before the symbolic link pointing to it in the
5357 <file>.deb</file> file. This is so that when
5358 <prgn>dpkg</prgn> comes to install the symlink
5359 (overwriting the previous symlink pointing at an older
5360 version of the library), the new shared library is already
5361 in place. In the past, this was achieved by creating the
5362 library in the temporary packaging directory before
5363 creating the symlink. Unfortunately, this was not always
5364 effective, since the building of the tar file in the
5365 <file>.deb</file> depended on the behavior of the underlying
5366 file system. Some file systems (such as reiserfs) reorder
5367 the files so that the order of creation is forgotten.
5368 Since version 1.7.0, <prgn>dpkg</prgn>
5369 reorders the files itself as necessary when building a
5370 package. Thus it is no longer important to concern
5371 oneself with the order of file creation.
5375 <sect1 id="ldconfig">
5376 <heading><tt>ldconfig</tt></heading>
5379 Any package installing shared libraries in one of the default
5380 library directories of the dynamic linker (which are currently
5381 <file>/usr/lib</file> and <file>/lib</file>) or a directory that is
5382 listed in <file>/etc/ld.so.conf</file><footnote>
5383 These are currently <file>/usr/local/lib</file> plus
5384 directories under <file>/lib</file> and <file>/usr/lib</file>
5385 matching the multiarch triplet for the system architecture.
5387 must use <prgn>ldconfig</prgn> to update the shared library
5392 The package maintainer scripts must only call
5393 <prgn>ldconfig</prgn> under these circumstances:
5394 <list compact="compact">
5395 <item>When the <prgn>postinst</prgn> script is run with a
5396 first argument of <tt>configure</tt>, the script must call
5397 <prgn>ldconfig</prgn>, and may optionally invoke
5398 <prgn>ldconfig</prgn> at other times.
5400 <item>When the <prgn>postrm</prgn> script is run with a
5401 first argument of <tt>remove</tt>, the script should call
5402 <prgn>ldconfig</prgn>.
5407 During install or upgrade, the preinst is called before
5408 the new files are installed, so calling "ldconfig" is
5409 pointless. The preinst of an existing package can also be
5410 called if an upgrade fails. However, this happens during
5411 the critical time when a shared libs may exist on-disk
5412 under a temporary name. Thus, it is dangerous and
5413 forbidden by current policy to call "ldconfig" at this
5418 When a package is installed or upgraded, "postinst
5419 configure" runs after the new files are safely on-disk.
5420 Since it is perfectly safe to invoke ldconfig
5421 unconditionally in a postinst, it is OK for a package to
5422 simply put ldconfig in its postinst without checking the
5423 argument. The postinst can also be called to recover from
5424 a failed upgrade. This happens before any new files are
5425 unpacked, so there is no reason to call "ldconfig" at this
5430 For a package that is being removed, prerm is
5431 called with all the files intact, so calling ldconfig is
5432 useless. The other calls to "prerm" happen in the case of
5433 upgrade at a time when all the files of the old package
5434 are on-disk, so again calling "ldconfig" is pointless.
5438 postrm, on the other hand, is called with the "remove"
5439 argument just after the files are removed, so this is
5440 the proper time to call "ldconfig" to notify the system
5441 of the fact that the shared libraries from the package
5442 are removed. The postrm can be called at several other
5443 times. At the time of "postrm purge", "postrm
5444 abort-install", or "postrm abort-upgrade", calling
5445 "ldconfig" is useless because the shared lib files are
5446 not on-disk. However, when "postrm" is invoked with
5447 arguments "upgrade", "failed-upgrade", or "disappear", a
5448 shared lib may exist on-disk under a temporary filename.
5456 <sect id="sharedlibs-support-files">
5457 <heading>Shared library support files</heading>
5460 If your package contains files whose names do not change with
5461 each change in the library shared object version, you must not
5462 put them in the shared library package. Otherwise, several
5463 versions of the shared library cannot be installed at the same
5464 time without filename clashes, making upgrades and transitions
5465 unnecessarily difficult.
5469 It is recommended that supporting files and run-time support
5470 programs that do not need to be invoked manually by users, but
5471 are nevertheless required for the package to function, be placed
5472 (if they are binary) in a subdirectory of <file>/usr/lib</file>,
5473 preferably under <file>/usr/lib/</file><var>package-name</var>.
5474 If the program or file is architecture independent, the
5475 recommendation is for it to be placed in a subdirectory of
5476 <file>/usr/share</file> instead, preferably under
5477 <file>/usr/share/</file><var>package-name</var>. Following the
5478 <var>package-name</var> naming convention ensures that the file
5479 names change when the shared object version changes.
5483 Run-time support programs that use the shared library but are
5484 not required for the library to function or files used by the
5485 shared library that can be used by any version of the shared
5486 library package should instead be put in a separate package.
5487 This package might typically be named
5488 <package><var>libraryname</var>-tools</package>; note the
5489 absence of the <var>soversion</var> in the package name.
5493 Files and support programs only useful when compiling software
5494 against the library should be included in the development
5495 package for the library.<footnote>
5496 For example, a <file><var>package-name</var>-config</file>
5497 script or <package>pkg-config</package> configuration files.
5502 <sect id="sharedlibs-static">
5503 <heading>Static libraries</heading>
5506 The static library (<file><var>libraryname.a</var></file>)
5507 is usually provided in addition to the shared version.
5508 It is placed into the development package (see below).
5512 In some cases, it is acceptable for a library to be
5513 available in static form only; these cases include:
5515 <item>libraries for languages whose shared library support
5516 is immature or unstable</item>
5517 <item>libraries whose interfaces are in flux or under
5518 development (commonly the case when the library's
5519 major version number is zero, or where the ABI breaks
5520 across patchlevels)</item>
5521 <item>libraries which are explicitly intended to be
5522 available only in static form by their upstream
5527 <sect id="sharedlibs-dev">
5528 <heading>Development files</heading>
5531 If there are development files associated with a shared library,
5532 the source package needs to generate a binary development package
5533 named <package><var>libraryname</var><var>soversion</var>-dev</package>,
5534 or if you prefer only to support one development version at a
5535 time, <package><var>libraryname</var>-dev</package>. Installing
5536 the development package must result in installation of all the
5537 development files necessary for compiling programs against that
5538 shared library.<footnote>
5539 This wording allows the development files to be split into
5540 several packages, such as a separate architecture-independent
5541 <package><var>libraryname</var>-headers</package>, provided that
5542 the development package depends on all the required additional
5548 In case several development versions of a library exist, you may
5549 need to use <prgn>dpkg</prgn>'s Conflicts mechanism (see
5550 <ref id="conflicts">) to ensure that the user only installs one
5551 development version at a time (as different development versions are
5552 likely to have the same header files in them, which would cause a
5553 filename clash if both were installed).
5557 The development package should contain a symlink for the associated
5558 shared library without a version number. For example, the
5559 <package>libgdbm-dev</package> package should include a symlink
5560 from <file>/usr/lib/libgdbm.so</file> to
5561 <file>libgdbm.so.3.0.0</file>. This symlink is needed by the linker
5562 (<prgn>ld</prgn>) when compiling packages, as it will only look for
5563 <file>libgdbm.so</file> when compiling dynamically.
5567 If the package provides Ada Library Information
5568 (<file>*.ali</file>) files for use with GNAT, these files must be
5569 installed read-only (mode 0444) so that GNAT will not attempt to
5570 recompile them. This overrides the normal file mode requirements
5571 given in <ref id="permissions-owners">.
5575 <sect id="sharedlibs-intradeps">
5576 <heading>Dependencies between the packages of the same library</heading>
5579 Typically the development version should have an exact
5580 version dependency on the runtime library, to make sure that
5581 compilation and linking happens correctly. The
5582 <tt>${binary:Version}</tt> substitution variable can be
5583 useful for this purpose.
5585 Previously, <tt>${Source-Version}</tt> was used, but its name
5586 was confusing and it has been deprecated since dpkg 1.13.19.
5591 <sect id="sharedlibs-shlibdeps">
5592 <heading>Dependencies between the library and other packages -
5593 the <tt>shlibs</tt> system</heading>
5596 If a package contains a binary or library which links to a
5597 shared library, we must ensure that when the package is
5598 installed on the system, all of the libraries needed are
5599 also installed. This requirement led to the creation of the
5600 <tt>shlibs</tt> system, which is very simple in its design:
5601 any package which <em>provides</em> a shared library also
5602 provides information on the package dependencies required to
5603 ensure the presence of this library, and any package which
5604 <em>uses</em> a shared library uses this information to
5605 determine the dependencies it requires. The files which
5606 contain the mapping from shared libraries to the necessary
5607 dependency information are called <file>shlibs</file> files.
5611 When a package is built which contains any shared libraries, it
5612 must provide a <file>shlibs</file> file for other packages to
5613 use. When a package is built which contains any shared
5614 libraries or compiled binaries, it must run
5615 <qref id="pkg-dpkg-shlibdeps"><prgn>dpkg-shlibdeps</prgn></qref>
5616 on these to determine the libraries used and hence the
5617 dependencies needed by this package.<footnote>
5619 <prgn>dpkg-shlibdeps</prgn> will use a program
5620 like <prgn>objdump</prgn> or <prgn>readelf</prgn> to find
5621 the libraries directly needed by the binaries or shared
5622 libraries in the package.
5626 We say that a binary <tt>foo</tt> <em>directly</em> uses
5627 a library <tt>libbar</tt> if it is explicitly linked
5628 with that library (that is, the library is listed in the ELF
5629 <tt>NEEDED</tt> attribute, caused by adding <tt>-lbar</tt>
5630 to the link line when the binary is created). Other
5631 libraries that are needed by <tt>libbar</tt> are linked
5632 <em>indirectly</em> to <tt>foo</tt>, and the dynamic
5633 linker will load them automatically when it loads
5634 <tt>libbar</tt>. A package should depend on the libraries
5635 it directly uses, but not the libraries it indirectly uses.
5636 The dependencies for those libraries will automatically pull
5637 in the other libraries.
5641 A good example of where this helps is the following. We
5642 could update <tt>libimlib</tt> with a new version that
5643 supports a new graphics format called dgf (but retaining the
5644 same major version number) and depends on <tt>libdgf</tt>.
5645 If we used <prgn>ldd</prgn> to add dependencies for every
5646 library directly or indirectly linked with a binary, every
5647 package that uses <tt>libimlib</tt> would need to be
5648 recompiled so it would also depend on <tt>libdgf</tt> or it
5649 wouldn't run due to missing symbols. Since dependencies are
5650 only added based on ELF <tt>NEEDED</tt> attribute, packages
5651 using <tt>libimlib</tt> can rely on <tt>libimlib</tt> itself
5652 having the dependency on <tt>libdgf</tt> and so they would
5653 not need rebuilding.
5659 In the following sections, we will first describe where the
5660 various <tt>shlibs</tt> files are to be found, then how to
5661 use <prgn>dpkg-shlibdeps</prgn>, and finally the <tt>shlibs</tt>
5662 file format and how to create them if your package contains a
5667 <heading>The <tt>shlibs</tt> files present on the system</heading>
5670 There are several places where <tt>shlibs</tt> files are
5671 found. The following list gives them in the order in which
5673 <qref id="pkg-dpkg-shlibdeps"><prgn>dpkg-shlibdeps</prgn></qref>.
5674 (The first one which gives the required information is used.)
5680 <p><file>debian/shlibs.local</file></p>
5683 This lists overrides for this package. This file should
5684 normally not be used, but may be needed temporarily in
5685 unusual situations to work around bugs in other packages,
5686 or in unusual cases where the normally declared dependency
5687 information in the installed <file>shlibs</file> file for
5688 a library cannot be used. This file overrides information
5689 obtained from any other source.
5694 <p><file>/etc/dpkg/shlibs.override</file></p>
5697 This lists global overrides. This list is normally
5698 empty. It is maintained by the local system
5704 <p><file>DEBIAN/shlibs</file> files in the "build directory"</p>
5707 When packages are being built,
5708 any <file>debian/shlibs</file> files are copied into the
5709 control information file area of the temporary build
5710 directory and given the name <file>shlibs</file>. These
5711 files give details of any shared libraries included in the
5712 same package.<footnote>
5713 An example may help here. Let us say that the source
5714 package <tt>foo</tt> generates two binary
5715 packages, <tt>libfoo2</tt> and <tt>foo-runtime</tt>.
5716 When building the binary packages, the two packages are
5717 created in the directories <file>debian/libfoo2</file>
5718 and <file>debian/foo-runtime</file> respectively.
5719 (<file>debian/tmp</file> could be used instead of one of
5720 these.) Since <tt>libfoo2</tt> provides the
5721 <tt>libfoo</tt> shared library, it will require a
5722 <tt>shlibs</tt> file, which will be installed in
5723 <file>debian/libfoo2/DEBIAN/shlibs</file>, eventually to
5724 become <file>/var/lib/dpkg/info/libfoo2.shlibs</file>.
5725 When <prgn>dpkg-shlibdeps</prgn> is run on the
5726 executable <file>debian/foo-runtime/usr/bin/foo-prog</file>,
5728 the <file>debian/libfoo2/DEBIAN/shlibs</file> file to
5729 determine whether <tt>foo-prog</tt>'s library
5730 dependencies are satisfied by any of the libraries
5731 provided by <tt>libfoo2</tt>. For this reason,
5732 <prgn>dpkg-shlibdeps</prgn> must only be run once all of
5733 the individual binary packages' <tt>shlibs</tt> files
5734 have been installed into the build directory.
5740 <p><file>/var/lib/dpkg/info/*.shlibs</file></p>
5743 These are the <file>shlibs</file> files corresponding to
5744 all of the packages installed on the system, and are
5745 maintained by the relevant package maintainers.
5750 <p><file>/etc/dpkg/shlibs.default</file></p>
5753 This file lists any shared libraries whose packages
5754 have failed to provide correct <file>shlibs</file> files.
5755 It was used when the <file>shlibs</file> setup was first
5756 introduced, but it is now normally empty. It is
5757 maintained by the <tt>dpkg</tt> maintainer.
5765 <heading>How to use <prgn>dpkg-shlibdeps</prgn> and the
5766 <file>shlibs</file> files</heading>
5770 <qref id="pkg-dpkg-shlibdeps"><prgn>dpkg-shlibdeps</prgn></qref>
5771 into your <file>debian/rules</file> file. If your package
5772 contains only compiled binaries and libraries (but no scripts),
5773 you can use a command such as:
5774 <example compact="compact">
5775 dpkg-shlibdeps debian/tmp/usr/bin/* debian/tmp/usr/sbin/* \
5776 debian/tmp/usr/lib/*
5778 Otherwise, you will need to explicitly list the compiled
5779 binaries and libraries.<footnote>
5780 If you are using <tt>debhelper</tt>, the
5781 <prgn>dh_shlibdeps</prgn> program will do this work for you.
5782 It will also correctly handle multi-binary packages.
5787 This command puts the dependency information into the
5788 <file>debian/substvars</file> file, which is then used by
5789 <prgn>dpkg-gencontrol</prgn>. You will need to place a
5790 <tt>${shlibs:Depends}</tt> variable in the <tt>Depends</tt>
5791 field in the control file for this to work.
5795 If you have multiple binary packages, you will need to call
5796 <prgn>dpkg-shlibdeps</prgn> on each one which contains
5797 compiled libraries or binaries. In such a case, you will
5798 need to use the <tt>-T</tt> option to the <tt>dpkg</tt>
5799 utilities to specify a different <file>substvars</file> file.
5803 If you are creating a udeb for use in the Debian Installer,
5804 you will need to specify that <prgn>dpkg-shlibdeps</prgn>
5805 should use the dependency line of type <tt>udeb</tt> by
5806 adding the <tt>-tudeb</tt> option<footnote>
5807 <prgn>dh_shlibdeps</prgn> from the <tt>debhelper</tt> suite
5808 will automatically add this option if it knows it is
5810 </footnote>. If there is no dependency line of
5811 type <tt>udeb</tt> in the <file>shlibs</file>
5812 file, <prgn>dpkg-shlibdeps</prgn> will fall back to the regular
5817 For more details on <prgn>dpkg-shlibdeps</prgn>, please see
5818 <ref id="pkg-dpkg-shlibdeps"> and
5819 <manref name="dpkg-shlibdeps" section="1">.
5824 <heading>The <file>shlibs</file> File Format</heading>
5827 Each <file>shlibs</file> file has the same format. Lines
5828 beginning with <tt>#</tt> are considered to be comments and
5829 are ignored. Each line is of the form:
5830 <example compact="compact">
5831 [<var>type</var>: ]<var>library-name</var> <var>soname-version</var> <var>dependencies ...</var>
5836 We will explain this by reference to the example of the
5837 <tt>zlib1g</tt> package, which (at the time of writing)
5838 installs the shared library <file>/usr/lib/libz.so.1.1.3</file>.
5842 <var>type</var> is an optional element that indicates the type
5843 of package for which the line is valid. The only type currently
5844 in use is <tt>udeb</tt>. The colon and space after the type are
5849 <var>library-name</var> is the name of the shared library,
5850 in this case <tt>libz</tt>. (This must match the name part
5851 of the soname, see below.)
5855 <var>soname-version</var> is the version part of the soname of
5856 the library. The soname is the thing that must exactly match
5857 for the library to be recognized by the dynamic linker, and is
5859 <tt><var>name</var>.so.<var>major-version</var></tt>, in our
5860 example, <tt>libz.so.1</tt>.<footnote>
5861 This can be determined using the command
5862 <example compact="compact">
5863 objdump -p /usr/lib/libz.so.1.1.3 | grep SONAME
5866 The version part is the part which comes after
5867 <tt>.so.</tt>, so in our case, it is <tt>1</tt>. The soname may
5868 instead be of the form
5869 <tt><var>name</var>-<var>major-version</var>.so</tt>, such
5870 as <tt>libdb-4.8.so</tt>, in which case the name would
5871 be <tt>libdb</tt> and the version would be <tt>4.8</tt>.
5875 <var>dependencies</var> has the same syntax as a dependency
5876 field in a binary package control file. It should give
5877 details of which packages are required to satisfy a binary
5878 built against the version of the library contained in the
5879 package. See <ref id="depsyntax"> for details.
5883 In our example, if the first version of the <tt>zlib1g</tt>
5884 package which contained a minor number of at least
5885 <tt>1.3</tt> was <var>1:1.1.3-1</var>, then the
5886 <tt>shlibs</tt> entry for this library could say:
5887 <example compact="compact">
5888 libz 1 zlib1g (>= 1:1.1.3)
5890 The version-specific dependency is to avoid warnings from
5891 the dynamic linker about using older shared libraries with
5896 As zlib1g also provides a udeb containing the shared library,
5897 there would also be a second line:
5898 <example compact="compact">
5899 udeb: libz 1 zlib1g-udeb (>= 1:1.1.3)
5905 <heading>Providing a <file>shlibs</file> file</heading>
5908 If your package provides a shared library, you need to create
5909 a <file>shlibs</file> file following the format described above.
5910 It is usual to call this file <file>debian/shlibs</file> (but if
5911 you have multiple binary packages, you might want to call it
5912 <file>debian/shlibs.<var>package</var></file> instead). Then
5913 let <file>debian/rules</file> install it in the control
5914 information file area:
5915 <example compact="compact">
5916 install -m644 debian/shlibs debian/tmp/DEBIAN
5918 or, in the case of a multi-binary package:
5919 <example compact="compact">
5920 install -m644 debian/shlibs.<var>package</var> debian/<var>package</var>/DEBIAN/shlibs
5922 An alternative way of doing this is to create the
5923 <file>shlibs</file> file in the control information file area
5924 directly from <file>debian/rules</file> without using
5925 a <file>debian/shlibs</file> file at all,<footnote>
5926 This is what <prgn>dh_makeshlibs</prgn> in
5927 the <package>debhelper</package> suite does. If your package
5928 also has a udeb that provides a shared
5929 library, <prgn>dh_makeshlibs</prgn> can automatically generate
5930 the <tt>udeb:</tt> lines if you specify the name of the udeb
5931 with the <tt>--add-udeb</tt> option.
5933 since the <file>debian/shlibs</file> file itself is ignored by
5934 <prgn>dpkg-shlibdeps</prgn>.
5938 As <prgn>dpkg-shlibdeps</prgn> reads the
5939 <file>DEBIAN/shlibs</file> files in all of the binary packages
5940 being built from this source package, all of the
5941 <file>DEBIAN/shlibs</file> files should be installed before
5942 <prgn>dpkg-shlibdeps</prgn> is called on any of the binary
5950 <chapt id="opersys"><heading>The Operating System</heading>
5953 <heading>File system hierarchy</heading>
5957 <heading>File System Structure</heading>
5960 The location of all installed files and directories must
5961 comply with the Filesystem Hierarchy Standard (FHS),
5962 version 2.3, with the exceptions noted below, and except
5963 where doing so would violate other terms of Debian
5964 Policy. The following exceptions to the FHS apply:
5969 The optional rules related to user specific
5970 configuration files for applications are stored in
5971 the user's home directory are relaxed. It is
5972 recommended that such files start with the
5973 '<tt>.</tt>' character (a "dot file"), and if an
5974 application needs to create more than one dot file
5975 then the preferred placement is in a subdirectory
5976 with a name starting with a '.' character, (a "dot
5977 directory"). In this case it is recommended the
5978 configuration files not start with the '.'
5984 The requirement for amd64 to use <file>/lib64</file>
5985 for 64 bit binaries is removed.
5990 The requirement for object files, internal binaries, and
5991 libraries, including <file>libc.so.*</file>, to be located
5992 directly under <file>/lib{,32}</file> and
5993 <file>/usr/lib{,32}</file> is amended, permitting files
5994 to instead be installed to
5995 <file>/lib/<var>triplet</var></file> and
5996 <file>/usr/lib/<var>triplet</var></file>, where
5997 <tt><var>triplet</var></tt> is the value returned by
5998 <tt>dpkg-architecture -qDEB_HOST_GNU_TYPE</tt> for the
5999 architecture of the package. Packages may <em>not</em>
6000 install files to any <var>triplet</var> path other
6001 than the one matching the architecture of that package;
6002 for instance, an <tt>Architecture: amd64</tt> package
6003 containing 32-bit x86 libraries may not install these
6004 libraries to <file>/usr/lib/i486-linux-gnu</file>.
6006 This is necessary in order to reserve the directories for
6007 use in cross-installation of library packages from other
6008 architectures, as part of the planned deployment of
6013 Applications may also use a single subdirectory under
6014 <file>/usr/lib/<var>triplet</var></file>.
6017 The execution time linker/loader, ld*, must still be made
6018 available in the existing location under /lib or /lib64
6019 since this is part of the ELF ABI for the architecture.
6024 The requirement that
6025 <file>/usr/local/share/man</file> be "synonymous"
6026 with <file>/usr/local/man</file> is relaxed to a
6031 The requirement that windowmanagers with a single
6032 configuration file call it <file>system.*wmrc</file>
6033 is removed, as is the restriction that the window
6034 manager subdirectory be named identically to the
6035 window manager name itself.
6040 The requirement that boot manager configuration
6041 files live in <file>/etc</file>, or at least are
6042 symlinked there, is relaxed to a recommendation.
6047 The following directories in the root filesystem are
6048 additionally allowed: <file>/sys</file> and
6049 <file>/selinux</file>. <footnote>These directories
6050 are used as mount points to mount virtual filesystems
6051 to get access to kernel information.</footnote>
6056 On GNU/Hurd systems, the following additional
6057 directories are allowed in the root
6058 filesystem: <file>/hurd</file>
6059 and <file>/servers</file>.<footnote>
6060 These directories are used to store translators and as
6061 a set of standard names for mount points,
6070 The version of this document referred here can be
6071 found in the <tt>debian-policy</tt> package or on <url
6072 id="http://www.debian.org/doc/packaging-manuals/fhs/"
6073 name="FHS (Debian copy)"> alongside this manual (or, if
6074 you have the <package>debian-policy</package> installed,
6076 id="file:///usr/share/doc/debian-policy/fhs/" name="FHS
6077 (local copy)">). The
6078 latest version, which may be a more recent version, may
6080 <url id="http://www.pathname.com/fhs/" name="FHS (upstream)">.
6081 Specific questions about following the standard may be
6082 asked on the <tt>debian-devel</tt> mailing list, or
6083 referred to the FHS mailing list (see the
6084 <url id="http://www.pathname.com/fhs/" name="FHS web site"> for
6090 <heading>Site-specific programs</heading>
6093 As mandated by the FHS, packages must not place any
6094 files in <file>/usr/local</file>, either by putting them in
6095 the file system archive to be unpacked by <prgn>dpkg</prgn>
6096 or by manipulating them in their maintainer scripts.
6100 However, the package may create empty directories below
6101 <file>/usr/local</file> so that the system administrator knows
6102 where to place site-specific files. These are not
6103 directories <em>in</em> <file>/usr/local</file>, but are
6104 children of directories in <file>/usr/local</file>. These
6105 directories (<file>/usr/local/*/dir/</file>)
6106 should be removed on package removal if they are
6111 Note that this applies only to
6112 directories <em>below</em> <file>/usr/local</file>,
6113 not <em>in</em> <file>/usr/local</file>. Packages must
6114 not create sub-directories in the
6115 directory <file>/usr/local</file> itself, except those
6116 listed in FHS, section 4.5. However, you may create
6117 directories below them as you wish. You must not remove
6118 any of the directories listed in 4.5, even if you created
6123 Since <file>/usr/local</file> can be mounted read-only from a
6124 remote server, these directories must be created and
6125 removed by the <prgn>postinst</prgn> and <prgn>prerm</prgn>
6126 maintainer scripts and not be included in the
6127 <file>.deb</file> archive. These scripts must not fail if
6128 either of these operations fail.
6132 For example, the <tt>emacsen-common</tt> package could
6133 contain something like
6134 <example compact="compact">
6135 if [ ! -e /usr/local/share/emacs ]
6137 if mkdir /usr/local/share/emacs 2>/dev/null
6139 chown root:staff /usr/local/share/emacs
6140 chmod 2775 /usr/local/share/emacs
6144 in its <prgn>postinst</prgn> script, and
6145 <example compact="compact">
6146 rmdir /usr/local/share/emacs/site-lisp 2>/dev/null || true
6147 rmdir /usr/local/share/emacs 2>/dev/null || true
6149 in the <prgn>prerm</prgn> script. (Note that this form is
6150 used to ensure that if the script is interrupted, the
6151 directory <file>/usr/local/share/emacs</file> will still be
6156 If you do create a directory in <file>/usr/local</file> for
6157 local additions to a package, you should ensure that
6158 settings in <file>/usr/local</file> take precedence over the
6159 equivalents in <file>/usr</file>.
6163 However, because <file>/usr/local</file> and its contents are
6164 for exclusive use of the local administrator, a package
6165 must not rely on the presence or absence of files or
6166 directories in <file>/usr/local</file> for normal operation.
6170 The <file>/usr/local</file> directory itself and all the
6171 subdirectories created by the package should (by default) have
6172 permissions 2775 (group-writable and set-group-id) and be
6173 owned by <tt>root:staff</tt>.
6178 <heading>The system-wide mail directory</heading>
6180 The system-wide mail directory
6181 is <file>/var/mail</file>. This directory is part of the
6182 base system and should not be owned by any particular mail
6183 agents. The use of the old
6184 location <file>/var/spool/mail</file> is deprecated, even
6185 though the spool may still be physically located there.
6191 <heading>Users and groups</heading>
6194 <heading>Introduction</heading>
6196 The Debian system can be configured to use either plain or
6201 Some user ids (UIDs) and group ids (GIDs) are reserved
6202 globally for use by certain packages. Because some
6203 packages need to include files which are owned by these
6204 users or groups, or need the ids compiled into binaries,
6205 these ids must be used on any Debian system only for the
6206 purpose for which they are allocated. This is a serious
6207 restriction, and we should avoid getting in the way of
6208 local administration policies. In particular, many sites
6209 allocate users and/or local system groups starting at 100.
6213 Apart from this we should have dynamically allocated ids,
6214 which should by default be arranged in some sensible
6215 order, but the behavior should be configurable.
6219 Packages other than <tt>base-passwd</tt> must not modify
6220 <file>/etc/passwd</file>, <file>/etc/shadow</file>,
6221 <file>/etc/group</file> or <file>/etc/gshadow</file>.
6226 <heading>UID and GID classes</heading>
6228 The UID and GID numbers are divided into classes as
6234 Globally allocated by the Debian project, the same
6235 on every Debian system. These ids will appear in
6236 the <file>passwd</file> and <file>group</file> files of all
6237 Debian systems, new ids in this range being added
6238 automatically as the <tt>base-passwd</tt> package is
6243 Packages which need a single statically allocated
6244 uid or gid should use one of these; their
6245 maintainers should ask the <tt>base-passwd</tt>
6253 Dynamically allocated system users and groups.
6254 Packages which need a user or group, but can have
6255 this user or group allocated dynamically and
6256 differently on each system, should use <tt>adduser
6257 --system</tt> to create the group and/or user.
6258 <prgn>adduser</prgn> will check for the existence of
6259 the user or group, and if necessary choose an unused
6260 id based on the ranges specified in
6261 <file>adduser.conf</file>.
6265 <tag>1000-59999:</tag>
6268 Dynamically allocated user accounts. By default
6269 <prgn>adduser</prgn> will choose UIDs and GIDs for
6270 user accounts in this range, though
6271 <file>adduser.conf</file> may be used to modify this
6276 <tag>60000-64999:</tag>
6279 Globally allocated by the Debian project, but only
6280 created on demand. The ids are allocated centrally
6281 and statically, but the actual accounts are only
6282 created on users' systems on demand.
6286 These ids are for packages which are obscure or
6287 which require many statically-allocated ids. These
6288 packages should check for and create the accounts in
6289 <file>/etc/passwd</file> or <file>/etc/group</file> (using
6290 <prgn>adduser</prgn> if it has this facility) if
6291 necessary. Packages which are likely to require
6292 further allocations should have a "hole" left after
6293 them in the allocation, to give them room to
6298 <tag>65000-65533:</tag>
6306 User <tt>nobody</tt>. The corresponding gid refers
6307 to the group <tt>nogroup</tt>.
6314 <tt>(uid_t)(-1) == (gid_t)(-1)</tt> <em>must
6315 not</em> be used, because it is the error return
6324 <sect id="sysvinit">
6325 <heading>System run levels and <file>init.d</file> scripts</heading>
6327 <sect1 id="/etc/init.d">
6328 <heading>Introduction</heading>
6331 The <file>/etc/init.d</file> directory contains the scripts
6332 executed by <prgn>init</prgn> at boot time and when the
6333 init state (or "runlevel") is changed (see <manref
6334 name="init" section="8">).
6338 There are at least two different, yet functionally
6339 equivalent, ways of handling these scripts. For the sake
6340 of simplicity, this document describes only the symbolic
6341 link method. However, it must not be assumed by maintainer
6342 scripts that this method is being used, and any automated
6343 manipulation of the various runlevel behaviors by
6344 maintainer scripts must be performed using
6345 <prgn>update-rc.d</prgn> as described below and not by
6346 manually installing or removing symlinks. For information
6347 on the implementation details of the other method,
6348 implemented in the <tt>file-rc</tt> package, please refer
6349 to the documentation of that package.
6353 These scripts are referenced by symbolic links in the
6354 <file>/etc/rc<var>n</var>.d</file> directories. When changing
6355 runlevels, <prgn>init</prgn> looks in the directory
6356 <file>/etc/rc<var>n</var>.d</file> for the scripts it should
6357 execute, where <tt><var>n</var></tt> is the runlevel that
6358 is being changed to, or <tt>S</tt> for the boot-up
6363 The names of the links all have the form
6364 <file>S<var>mm</var><var>script</var></file> or
6365 <file>K<var>mm</var><var>script</var></file> where
6366 <var>mm</var> is a two-digit number and <var>script</var>
6367 is the name of the script (this should be the same as the
6368 name of the actual script in <file>/etc/init.d</file>).
6372 When <prgn>init</prgn> changes runlevel first the targets
6373 of the links whose names start with a <tt>K</tt> are
6374 executed, each with the single argument <tt>stop</tt>,
6375 followed by the scripts prefixed with an <tt>S</tt>, each
6376 with the single argument <tt>start</tt>. (The links are
6377 those in the <file>/etc/rc<var>n</var>.d</file> directory
6378 corresponding to the new runlevel.) The <tt>K</tt> links
6379 are responsible for killing services and the <tt>S</tt>
6380 link for starting services upon entering the runlevel.
6384 For example, if we are changing from runlevel 2 to
6385 runlevel 3, init will first execute all of the <tt>K</tt>
6386 prefixed scripts it finds in <file>/etc/rc3.d</file>, and then
6387 all of the <tt>S</tt> prefixed scripts in that directory.
6388 The links starting with <tt>K</tt> will cause the
6389 referred-to file to be executed with an argument of
6390 <tt>stop</tt>, and the <tt>S</tt> links with an argument
6395 The two-digit number <var>mm</var> is used to determine
6396 the order in which to run the scripts: low-numbered links
6397 have their scripts run first. For example, the
6398 <tt>K20</tt> scripts will be executed before the
6399 <tt>K30</tt> scripts. This is used when a certain service
6400 must be started before another. For example, the name
6401 server <prgn>bind</prgn> might need to be started before
6402 the news server <prgn>inn</prgn> so that <prgn>inn</prgn>
6403 can set up its access lists. In this case, the script
6404 that starts <prgn>bind</prgn> would have a lower number
6405 than the script that starts <prgn>inn</prgn> so that it
6407 <example compact="compact">
6414 The two runlevels 0 (halt) and 6 (reboot) are slightly
6415 different. In these runlevels, the links with an
6416 <tt>S</tt> prefix are still called after those with a
6417 <tt>K</tt> prefix, but they too are called with the single
6418 argument <tt>stop</tt>.
6422 <sect1 id="writing-init">
6423 <heading>Writing the scripts</heading>
6426 Packages that include daemons for system services should
6427 place scripts in <file>/etc/init.d</file> to start or stop
6428 services at boot time or during a change of runlevel.
6429 These scripts should be named
6430 <file>/etc/init.d/<var>package</var></file>, and they should
6431 accept one argument, saying what to do:
6434 <tag><tt>start</tt></tag>
6435 <item>start the service,</item>
6437 <tag><tt>stop</tt></tag>
6438 <item>stop the service,</item>
6440 <tag><tt>restart</tt></tag>
6441 <item>stop and restart the service if it's already running,
6442 otherwise start the service</item>
6444 <tag><tt>reload</tt></tag>
6445 <item><p>cause the configuration of the service to be
6446 reloaded without actually stopping and restarting
6449 <tag><tt>force-reload</tt></tag>
6450 <item>cause the configuration to be reloaded if the
6451 service supports this, otherwise restart the
6455 The <tt>start</tt>, <tt>stop</tt>, <tt>restart</tt>, and
6456 <tt>force-reload</tt> options should be supported by all
6457 scripts in <file>/etc/init.d</file>, the <tt>reload</tt>
6462 The <file>init.d</file> scripts must ensure that they will
6463 behave sensibly (i.e., returning success and not starting
6464 multiple copies of a service) if invoked with <tt>start</tt>
6465 when the service is already running, or with <tt>stop</tt>
6466 when it isn't, and that they don't kill unfortunately-named
6467 user processes. The best way to achieve this is usually to
6468 use <prgn>start-stop-daemon</prgn> with the <tt>--oknodo</tt>
6473 Be careful of using <tt>set -e</tt> in <file>init.d</file>
6474 scripts. Writing correct <file>init.d</file> scripts requires
6475 accepting various error exit statuses when daemons are already
6476 running or already stopped without aborting
6477 the <file>init.d</file> script, and common <file>init.d</file>
6478 function libraries are not safe to call with <tt>set -e</tt>
6480 <tt>/lib/lsb/init-functions</tt>, which assists in writing
6481 LSB-compliant init scripts, may fail if <tt>set -e</tt> is
6482 in effect and echoing status messages to the console fails,
6484 </footnote>. For <tt>init.d</tt> scripts, it's often easier
6485 to not use <tt>set -e</tt> and instead check the result of
6486 each command separately.
6490 If a service reloads its configuration automatically (as
6491 in the case of <prgn>cron</prgn>, for example), the
6492 <tt>reload</tt> option of the <file>init.d</file> script
6493 should behave as if the configuration has been reloaded
6498 The <file>/etc/init.d</file> scripts must be treated as
6499 configuration files, either (if they are present in the
6500 package, that is, in the .deb file) by marking them as
6501 <tt>conffile</tt>s, or, (if they do not exist in the .deb)
6502 by managing them correctly in the maintainer scripts (see
6503 <ref id="config-files">). This is important since we want
6504 to give the local system administrator the chance to adapt
6505 the scripts to the local system, e.g., to disable a
6506 service without de-installing the package, or to specify
6507 some special command line options when starting a service,
6508 while making sure their changes aren't lost during the next
6513 These scripts should not fail obscurely when the
6514 configuration files remain but the package has been
6515 removed, as configuration files remain on the system after
6516 the package has been removed. Only when <prgn>dpkg</prgn>
6517 is executed with the <tt>--purge</tt> option will
6518 configuration files be removed. In particular, as the
6519 <file>/etc/init.d/<var>package</var></file> script itself is
6520 usually a <tt>conffile</tt>, it will remain on the system
6521 if the package is removed but not purged. Therefore, you
6522 should include a <tt>test</tt> statement at the top of the
6524 <example compact="compact">
6525 test -f <var>program-executed-later-in-script</var> || exit 0
6530 Often there are some variables in the <file>init.d</file>
6531 scripts whose values control the behavior of the scripts,
6532 and which a system administrator is likely to want to
6533 change. As the scripts themselves are frequently
6534 <tt>conffile</tt>s, modifying them requires that the
6535 administrator merge in their changes each time the package
6536 is upgraded and the <tt>conffile</tt> changes. To ease
6537 the burden on the system administrator, such configurable
6538 values should not be placed directly in the script.
6539 Instead, they should be placed in a file in
6540 <file>/etc/default</file>, which typically will have the same
6541 base name as the <file>init.d</file> script. This extra file
6542 should be sourced by the script when the script runs. It
6543 must contain only variable settings and comments in SUSv3
6544 <prgn>sh</prgn> format. It may either be a
6545 <tt>conffile</tt> or a configuration file maintained by
6546 the package maintainer scripts. See <ref id="config-files">
6551 To ensure that vital configurable values are always
6552 available, the <file>init.d</file> script should set default
6553 values for each of the shell variables it uses, either
6554 before sourcing the <file>/etc/default/</file> file or
6555 afterwards using something like the <tt>:
6556 ${VAR:=default}</tt> syntax. Also, the <file>init.d</file>
6557 script must behave sensibly and not fail if the
6558 <file>/etc/default</file> file is deleted.
6562 <file>/var/run</file> and <file>/var/lock</file> may be mounted
6563 as temporary filesystems<footnote>
6564 For example, using the <tt>RAMRUN</tt> and <tt>RAMLOCK</tt>
6565 options in <file>/etc/default/rcS</file>.
6566 </footnote>, so the <file>init.d</file> scripts must handle this
6567 correctly. This will typically amount to creating any required
6568 subdirectories dynamically when the <file>init.d</file> script
6569 is run, rather than including them in the package and relying on
6570 <prgn>dpkg</prgn> to create them.
6575 <heading>Interfacing with the initscript system</heading>
6578 Maintainers should use the abstraction layer provided by
6579 the <prgn>update-rc.d</prgn> and <prgn>invoke-rc.d</prgn>
6580 programs to deal with initscripts in their packages'
6581 scripts such as <prgn>postinst</prgn>, <prgn>prerm</prgn>
6582 and <prgn>postrm</prgn>.
6586 Directly managing the /etc/rc?.d links and directly
6587 invoking the <file>/etc/init.d/</file> initscripts should
6588 be done only by packages providing the initscript
6589 subsystem (such as <prgn>sysv-rc</prgn> and
6590 <prgn>file-rc</prgn>).
6594 <heading>Managing the links</heading>
6597 The program <prgn>update-rc.d</prgn> is provided for
6598 package maintainers to arrange for the proper creation and
6599 removal of <file>/etc/rc<var>n</var>.d</file> symbolic links,
6600 or their functional equivalent if another method is being
6601 used. This may be used by maintainers in their packages'
6602 <prgn>postinst</prgn> and <prgn>postrm</prgn> scripts.
6606 You must not include any <file>/etc/rc<var>n</var>.d</file>
6607 symbolic links in the actual archive or manually create or
6608 remove the symbolic links in maintainer scripts; you must
6609 use the <prgn>update-rc.d</prgn> program instead. (The
6610 former will fail if an alternative method of maintaining
6611 runlevel information is being used.) You must not include
6612 the <file>/etc/rc<var>n</var>.d</file> directories themselves
6613 in the archive either. (Only the <tt>sysvinit</tt>
6618 By default <prgn>update-rc.d</prgn> will start services in
6619 each of the multi-user state runlevels (2, 3, 4, and 5)
6620 and stop them in the halt runlevel (0), the single-user
6621 runlevel (1) and the reboot runlevel (6). The system
6622 administrator will have the opportunity to customize
6623 runlevels by simply adding, moving, or removing the
6624 symbolic links in <file>/etc/rc<var>n</var>.d</file> if
6625 symbolic links are being used, or by modifying
6626 <file>/etc/runlevel.conf</file> if the <tt>file-rc</tt> method
6631 To get the default behavior for your package, put in your
6632 <prgn>postinst</prgn> script
6633 <example compact="compact">
6634 update-rc.d <var>package</var> defaults
6636 and in your <prgn>postrm</prgn>
6637 <example compact="compact">
6638 if [ "$1" = purge ]; then
6639 update-rc.d <var>package</var> remove
6641 </example>. Note that if your package changes runlevels
6642 or priority, you may have to remove and recreate the links,
6643 since otherwise the old links may persist. Refer to the
6644 documentation of <prgn>update-rc.d</prgn>.
6648 This will use a default sequence number of 20. If it does
6649 not matter when or in which order the <file>init.d</file>
6650 script is run, use this default. If it does, then you
6651 should talk to the maintainer of the <prgn>sysvinit</prgn>
6652 package or post to <tt>debian-devel</tt>, and they will
6653 help you choose a number.
6657 For more information about using <tt>update-rc.d</tt>,
6658 please consult its man page <manref name="update-rc.d"
6664 <heading>Running initscripts</heading>
6666 The program <prgn>invoke-rc.d</prgn> is provided to make
6667 it easier for package maintainers to properly invoke an
6668 initscript, obeying runlevel and other locally-defined
6669 constraints that might limit a package's right to start,
6670 stop and otherwise manage services. This program may be
6671 used by maintainers in their packages' scripts.
6675 The package maintainer scripts must use
6676 <prgn>invoke-rc.d</prgn> to invoke the
6677 <file>/etc/init.d/*</file> initscripts, instead of
6678 calling them directly.
6682 By default, <prgn>invoke-rc.d</prgn> will pass any
6683 action requests (start, stop, reload, restart...) to the
6684 <file>/etc/init.d</file> script, filtering out requests
6685 to start or restart a service out of its intended
6690 Most packages will simply need to change:
6691 <example compact="compact">/etc/init.d/<package>
6692 <action></example> in their <prgn>postinst</prgn>
6693 and <prgn>prerm</prgn> scripts to:
6694 <example compact="compact">
6695 if which invoke-rc.d >/dev/null 2>&1; then
6696 invoke-rc.d <var>package</var> <action>
6698 /etc/init.d/<var>package</var> <action>
6704 A package should register its initscript services using
6705 <prgn>update-rc.d</prgn> before it tries to invoke them
6706 using <prgn>invoke-rc.d</prgn>. Invocation of
6707 unregistered services may fail.
6711 For more information about using
6712 <prgn>invoke-rc.d</prgn>, please consult its man page
6713 <manref name="invoke-rc.d" section="8">.
6719 <heading>Boot-time initialization</heading>
6722 There used to be another directory, <file>/etc/rc.boot</file>,
6723 which contained scripts which were run once per machine
6724 boot. This has been deprecated in favour of links from
6725 <file>/etc/rcS.d</file> to files in <file>/etc/init.d</file> as
6726 described in <ref id="/etc/init.d">. Packages must not
6727 place files in <file>/etc/rc.boot</file>.
6732 <heading>Example</heading>
6735 An example on which you can base your
6736 <file>/etc/init.d</file> scripts is found in
6737 <file>/etc/init.d/skeleton</file>.
6744 <heading>Console messages from <file>init.d</file> scripts</heading>
6747 This section describes the formats to be used for messages
6748 written to standard output by the <file>/etc/init.d</file>
6749 scripts. The intent is to improve the consistency of
6750 Debian's startup and shutdown look and feel. For this
6751 reason, please look very carefully at the details. We want
6752 the messages to have the same format in terms of wording,
6753 spaces, punctuation and case of letters.
6757 Here is a list of overall rules that should be used for
6758 messages generated by <file>/etc/init.d</file> scripts.
6764 The message should fit in one line (fewer than 80
6765 characters), start with a capital letter and end with
6766 a period (<tt>.</tt>) and line feed (<tt>"\n"</tt>).
6770 If the script is performing some time consuming task in
6771 the background (not merely starting or stopping a
6772 program, for instance), an ellipsis (three dots:
6773 <tt>...</tt>) should be output to the screen, with no
6774 leading or tailing whitespace or line feeds.
6778 The messages should appear as if the computer is telling
6779 the user what it is doing (politely :-), but should not
6780 mention "it" directly. For example, instead of:
6781 <example compact="compact">
6782 I'm starting network daemons: nfsd mountd.
6784 the message should say
6785 <example compact="compact">
6786 Starting network daemons: nfsd mountd.
6793 <tt>init.d</tt> script should use the following standard
6794 message formats for the situations enumerated below.
6800 <p>When daemons are started</p>
6803 If the script starts one or more daemons, the output
6804 should look like this (a single line, no leading
6806 <example compact="compact">
6807 Starting <var>description</var>: <var>daemon-1</var> ... <var>daemon-n</var>.
6809 The <var>description</var> should describe the
6810 subsystem the daemon or set of daemons are part of,
6811 while <var>daemon-1</var> up to <var>daemon-n</var>
6812 denote each daemon's name (typically the file name of
6817 For example, the output of <file>/etc/init.d/lpd</file>
6819 <example compact="compact">
6820 Starting printer spooler: lpd.
6825 This can be achieved by saying
6826 <example compact="compact">
6827 echo -n "Starting printer spooler: lpd"
6828 start-stop-daemon --start --quiet --exec /usr/sbin/lpd
6831 in the script. If there are more than one daemon to
6832 start, the output should look like this:
6833 <example compact="compact">
6834 echo -n "Starting remote file system services:"
6835 echo -n " nfsd"; start-stop-daemon --start --quiet nfsd
6836 echo -n " mountd"; start-stop-daemon --start --quiet mountd
6837 echo -n " ugidd"; start-stop-daemon --start --quiet ugidd
6840 This makes it possible for the user to see what is
6841 happening and when the final daemon has been started.
6842 Care should be taken in the placement of white spaces:
6843 in the example above the system administrators can
6844 easily comment out a line if they don't want to start
6845 a specific daemon, while the displayed message still
6851 <p>When a system parameter is being set</p>
6854 If you have to set up different system parameters
6855 during the system boot, you should use this format:
6856 <example compact="compact">
6857 Setting <var>parameter</var> to "<var>value</var>".
6862 You can use a statement such as the following to get
6864 <example compact="compact">
6865 echo "Setting DNS domainname to \"$domainname\"."
6870 Note that the same symbol (<tt>"</tt>) <!-- " --> is used
6871 for the left and right quotation marks. A grave accent
6872 (<tt>`</tt>) is not a quote character; neither is an
6873 apostrophe (<tt>'</tt>).
6878 <p>When a daemon is stopped or restarted</p>
6881 When you stop or restart a daemon, you should issue a
6882 message identical to the startup message, except that
6883 <tt>Starting</tt> is replaced with <tt>Stopping</tt>
6884 or <tt>Restarting</tt> respectively.
6888 For example, stopping the printer daemon will look like
6890 <example compact="compact">
6891 Stopping printer spooler: lpd.
6897 <p>When something is executed</p>
6900 There are several examples where you have to run a
6901 program at system startup or shutdown to perform a
6902 specific task, for example, setting the system's clock
6903 using <prgn>netdate</prgn> or killing all processes
6904 when the system shuts down. Your message should look
6906 <example compact="compact">
6907 Doing something very useful...done.
6909 You should print the <tt>done.</tt> immediately after
6910 the job has been completed, so that the user is
6911 informed why they have to wait. You can get this
6913 <example compact="compact">
6914 echo -n "Doing something very useful..."
6923 <p>When the configuration is reloaded</p>
6926 When a daemon is forced to reload its configuration
6927 files you should use the following format:
6928 <example compact="compact">
6929 Reloading <var>description</var> configuration...done.
6931 where <var>description</var> is the same as in the
6932 daemon starting message.
6940 <heading>Cron jobs</heading>
6943 Packages must not modify the configuration file
6944 <file>/etc/crontab</file>, and they must not modify the files in
6945 <file>/var/spool/cron/crontabs</file>.</p>
6948 If a package wants to install a job that has to be executed
6949 via cron, it should place a file with the name of the
6950 package in one or more of the following directories:
6951 <example compact="compact">
6957 As these directory names imply, the files within them are
6958 executed on an hourly, daily, weekly, or monthly basis,
6959 respectively. The exact times are listed in
6960 <file>/etc/crontab</file>.</p>
6963 All files installed in any of these directories must be
6964 scripts (e.g., shell scripts or Perl scripts) so that they
6965 can easily be modified by the local system administrator.
6966 In addition, they must be treated as configuration files.
6970 If a certain job has to be executed at some other frequency or
6971 at a specific time, the package should install a file
6972 <file>/etc/cron.d/<var>package</var></file>. This file uses the
6973 same syntax as <file>/etc/crontab</file> and is processed by
6974 <prgn>cron</prgn> automatically. The file must also be
6975 treated as a configuration file. (Note that entries in the
6976 <file>/etc/cron.d</file> directory are not handled by
6977 <prgn>anacron</prgn>. Thus, you should only use this
6978 directory for jobs which may be skipped if the system is not
6981 Unlike <file>crontab</file> files described in the IEEE Std
6982 1003.1-2008 (POSIX.1) available from
6983 <url id="http://www.opengroup.org/onlinepubs/9699919799/"
6984 name="The Open Group">, the files in
6985 <file>/etc/cron.d</file> and the file
6986 <file>/etc/crontab</file> have seven fields; namely:
6988 <item>Minute [0,59]</item>
6989 <item>Hour [0,23]</item>
6990 <item>Day of the month [1,31]</item>
6991 <item>Month of the year [1,12]</item>
6992 <item>Day of the week ([0,6] with 0=Sunday)</item>
6993 <item>Username</item>
6994 <item>Command to be run</item>
6996 Ranges of numbers are allowed. Ranges are two numbers
6997 separated with a hyphen. The specified range is inclusive.
6998 Lists are allowed. A list is a set of numbers (or ranges)
6999 separated by commas. Step values can be used in conjunction
7004 The scripts or <tt>crontab</tt> entries in these directories should
7005 check if all necessary programs are installed before they
7006 try to execute them. Otherwise, problems will arise when a
7007 package was removed but not purged since configuration files
7008 are kept on the system in this situation.
7012 Any <tt>cron</tt> daemon must provide
7013 <file>/usr/bin/crontab</file> and support normal
7014 <tt>crontab</tt> entries as specified in POSIX. The daemon
7015 must also support names for days and months, ranges, and
7016 step values. It has to support <file>/etc/crontab</file>,
7017 and correctly execute the scripts in
7018 <file>/etc/cron.d</file>. The daemon must also correctly
7020 <file>/etc/cron.{hourly,daily,weekly,monthly}</file>.
7025 <heading>Menus</heading>
7028 The Debian <tt>menu</tt> package provides a standard
7029 interface between packages providing applications and
7030 <em>menu programs</em> (either X window managers or
7031 text-based menu programs such as <prgn>pdmenu</prgn>).
7035 All packages that provide applications that need not be
7036 passed any special command line arguments for normal
7037 operation should register a menu entry for those
7038 applications, so that users of the <tt>menu</tt> package
7039 will automatically get menu entries in their window
7040 managers, as well in shells like <tt>pdmenu</tt>.
7044 Menu entries should follow the current menu policy.
7048 The menu policy can be found in the <tt>menu-policy</tt>
7049 files in the <tt>debian-policy</tt> package.
7050 It is also available from the Debian web mirrors at
7051 <tt><url name="/doc/packaging-manuals/menu-policy/"
7052 id="http://www.debian.org/doc/packaging-manuals/menu-policy/"></tt>.
7056 Please also refer to the <em>Debian Menu System</em>
7057 documentation that comes with the <package>menu</package>
7058 package for information about how to register your
7064 <heading>Multimedia handlers</heading>
7067 MIME (Multipurpose Internet Mail Extensions, RFCs 2045-2049)
7068 is a mechanism for encoding files and data streams and
7069 providing meta-information about them, in particular their
7070 type (e.g. audio or video) and format (e.g. PNG, HTML,
7075 Registration of MIME type handlers allows programs like mail
7076 user agents and web browsers to invoke these handlers to
7077 view, edit or display MIME types they don't support directly.
7081 Packages which provide the ability to view/show/play,
7082 compose, edit or print MIME types should register themselves
7083 as such following the current MIME support policy.
7087 The MIME support policy can be found in the <tt>mime-policy</tt>
7088 files in the <tt>debian-policy</tt> package.
7089 It is also available from the Debian web mirrors at
7090 <tt><url name="/doc/packaging-manuals/mime-policy/"
7091 id="http://www.debian.org/doc/packaging-manuals/mime-policy/"></tt>.
7097 <heading>Keyboard configuration</heading>
7100 To achieve a consistent keyboard configuration so that all
7101 applications interpret a keyboard event the same way, all
7102 programs in the Debian distribution must be configured to
7103 comply with the following guidelines.
7107 The following keys must have the specified interpretations:
7110 <tag><tt><--</tt></tag>
7111 <item>delete the character to the left of the cursor</item>
7113 <tag><tt>Delete</tt></tag>
7114 <item>delete the character to the right of the cursor</item>
7116 <tag><tt>Control+H</tt></tag>
7117 <item>emacs: the help prefix</item>
7120 The interpretation of any keyboard events should be
7121 independent of the terminal that is used, be it a virtual
7122 console, an X terminal emulator, an rlogin/telnet session,
7127 The following list explains how the different programs
7128 should be set up to achieve this:
7134 <tt><--</tt> generates <tt>KB_BackSpace</tt> in X.
7138 <tt>Delete</tt> generates <tt>KB_Delete</tt> in X.
7142 X translations are set up to make
7143 <tt>KB_Backspace</tt> generate ASCII DEL, and to make
7144 <tt>KB_Delete</tt> generate <tt>ESC [ 3 ~</tt> (this
7145 is the vt220 escape code for the "delete character"
7146 key). This must be done by loading the X resources
7147 using <prgn>xrdb</prgn> on all local X displays, not
7148 using the application defaults, so that the
7149 translation resources used correspond to the
7150 <prgn>xmodmap</prgn> settings.
7154 The Linux console is configured to make
7155 <tt><--</tt> generate DEL, and <tt>Delete</tt>
7156 generate <tt>ESC [ 3 ~</tt>.
7160 X applications are configured so that <tt><</tt>
7161 deletes left, and <tt>Delete</tt> deletes right. Motif
7162 applications already work like this.
7166 Terminals should have <tt>stty erase ^?</tt> .
7170 The <tt>xterm</tt> terminfo entry should have <tt>ESC
7171 [ 3 ~</tt> for <tt>kdch1</tt>, just as for
7172 <tt>TERM=linux</tt> and <tt>TERM=vt220</tt>.
7176 Emacs is programmed to map <tt>KB_Backspace</tt> or
7177 the <tt>stty erase</tt> character to
7178 <tt>delete-backward-char</tt>, and <tt>KB_Delete</tt>
7179 or <tt>kdch1</tt> to <tt>delete-forward-char</tt>, and
7180 <tt>^H</tt> to <tt>help</tt> as always.
7184 Other applications use the <tt>stty erase</tt>
7185 character and <tt>kdch1</tt> for the two delete keys,
7186 with ASCII DEL being "delete previous character" and
7187 <tt>kdch1</tt> being "delete character under
7195 This will solve the problem except for the following
7202 Some terminals have a <tt><--</tt> key that cannot
7203 be made to produce anything except <tt>^H</tt>. On
7204 these terminals Emacs help will be unavailable on
7205 <tt>^H</tt> (assuming that the <tt>stty erase</tt>
7206 character takes precedence in Emacs, and has been set
7207 correctly). <tt>M-x help</tt> or <tt>F1</tt> (if
7208 available) can be used instead.
7212 Some operating systems use <tt>^H</tt> for <tt>stty
7213 erase</tt>. However, modern telnet versions and all
7214 rlogin versions propagate <tt>stty</tt> settings, and
7215 almost all UNIX versions honour <tt>stty erase</tt>.
7216 Where the <tt>stty</tt> settings are not propagated
7217 correctly, things can be made to work by using
7218 <tt>stty</tt> manually.
7222 Some systems (including previous Debian versions) use
7223 <prgn>xmodmap</prgn> to arrange for both
7224 <tt><--</tt> and <tt>Delete</tt> to generate
7225 <tt>KB_Delete</tt>. We can change the behavior of
7226 their X clients using the same X resources that we use
7227 to do it for our own clients, or configure our clients
7228 using their resources when things are the other way
7229 around. On displays configured like this
7230 <tt>Delete</tt> will not work, but <tt><--</tt>
7235 Some operating systems have different <tt>kdch1</tt>
7236 settings in their <tt>terminfo</tt> database for
7237 <tt>xterm</tt> and others. On these systems the
7238 <tt>Delete</tt> key will not work correctly when you
7239 log in from a system conforming to our policy, but
7240 <tt><--</tt> will.
7247 <heading>Environment variables</heading>
7250 A program must not depend on environment variables to get
7251 reasonable defaults. (That's because these environment
7252 variables would have to be set in a system-wide
7253 configuration file like <file>/etc/profile</file>, which is not
7254 supported by all shells.)
7258 If a program usually depends on environment variables for its
7259 configuration, the program should be changed to fall back to
7260 a reasonable default configuration if these environment
7261 variables are not present. If this cannot be done easily
7262 (e.g., if the source code of a non-free program is not
7263 available), the program must be replaced by a small
7264 "wrapper" shell script which sets the environment variables
7265 if they are not already defined, and calls the original program.
7269 Here is an example of a wrapper script for this purpose:
7271 <example compact="compact">
7273 BAR=${BAR:-/var/lib/fubar}
7275 exec /usr/lib/foo/foo "$@"
7280 Furthermore, as <file>/etc/profile</file> is a configuration
7281 file of the <prgn>base-files</prgn> package, other packages must
7282 not put any environment variables or other commands into that
7287 <sect id="doc-base">
7288 <heading>Registering Documents using doc-base</heading>
7291 The <package>doc-base</package> package implements a
7292 flexible mechanism for handling and presenting
7293 documentation. The recommended practice is for every Debian
7294 package that provides online documentation (other than just
7295 manual pages) to register these documents with
7296 <package>doc-base</package> by installing a
7297 <package>doc-base</package> control file via the
7298 <prgn/install-docs/ script at installation time and
7299 de-register the manuals again when the package is removed.
7302 Please refer to the documentation that comes with the
7303 <package>doc-base</package> package for information and
7312 <heading>Files</heading>
7314 <sect id="binaries">
7315 <heading>Binaries</heading>
7318 Two different packages must not install programs with
7319 different functionality but with the same filenames. (The
7320 case of two programs having the same functionality but
7321 different implementations is handled via "alternatives" or
7322 the "Conflicts" mechanism. See <ref id="maintscripts"> and
7323 <ref id="conflicts"> respectively.) If this case happens,
7324 one of the programs must be renamed. The maintainers should
7325 report this to the <tt>debian-devel</tt> mailing list and
7326 try to find a consensus about which program will have to be
7327 renamed. If a consensus cannot be reached, <em>both</em>
7328 programs must be renamed.
7332 By default, when a package is being built, any binaries
7333 created should include debugging information, as well as
7334 being compiled with optimization. You should also turn on
7335 as many reasonable compilation warnings as possible; this
7336 makes life easier for porters, who can then look at build
7337 logs for possible problems. For the C programming language,
7338 this means the following compilation parameters should be
7340 <example compact="compact">
7342 CFLAGS = -O2 -g -Wall # sane warning options vary between programs
7344 INSTALL = install -s # (or use strip on the files in debian/tmp)
7349 Note that by default all installed binaries should be stripped,
7350 either by using the <tt>-s</tt> flag to
7351 <prgn>install</prgn>, or by calling <prgn>strip</prgn> on
7352 the binaries after they have been copied into
7353 <file>debian/tmp</file> but before the tree is made into a
7358 Although binaries in the build tree should be compiled with
7359 debugging information by default, it can often be difficult to
7360 debug programs if they are also subjected to compiler
7361 optimization. For this reason, it is recommended to support the
7362 standardized environment variable <tt>DEB_BUILD_OPTIONS</tt>
7363 (see <ref id="debianrules-options">). This variable can contain
7364 several flags to change how a package is compiled and built.
7368 It is up to the package maintainer to decide what
7369 compilation options are best for the package. Certain
7370 binaries (such as computationally-intensive programs) will
7371 function better with certain flags (<tt>-O3</tt>, for
7372 example); feel free to use them. Please use good judgment
7373 here. Don't use flags for the sake of it; only use them
7374 if there is good reason to do so. Feel free to override
7375 the upstream author's ideas about which compilation
7376 options are best: they are often inappropriate for our
7382 <sect id="libraries">
7383 <heading>Libraries</heading>
7386 If the package is <strong>architecture: any</strong>, then
7387 the shared library compilation and linking flags must have
7388 <tt>-fPIC</tt>, or the package shall not build on some of
7389 the supported architectures<footnote>
7391 If you are using GCC, <tt>-fPIC</tt> produces code with
7392 relocatable position independent code, which is required for
7393 most architectures to create a shared library, with i386 and
7394 perhaps some others where non position independent code is
7395 permitted in a shared library.
7398 Position independent code may have a performance penalty,
7399 especially on <tt>i386</tt>. However, in most cases the
7400 speed penalty must be measured against the memory wasted on
7401 the few architectures where non position independent code is
7404 </footnote>. Any exception to this rule must be discussed on
7405 the mailing list <em>debian-devel@lists.debian.org</em>, and
7406 a rough consensus obtained. The reasons for not compiling
7407 with <tt>-fPIC</tt> flag must be recorded in the file
7408 <tt>README.Debian</tt>, and care must be taken to either
7409 restrict the architecture or arrange for <tt>-fPIC</tt> to
7410 be used on architectures where it is required.<footnote>
7412 Some of the reasons why this might be required is if the
7413 library contains hand crafted assembly code that is not
7414 relocatable, the speed penalty is excessive for compute
7415 intensive libs, and similar reasons.
7420 As to the static libraries, the common case is not to have
7421 relocatable code, since there is no benefit, unless in specific
7422 cases; therefore the static version must not be compiled
7423 with the <tt>-fPIC</tt> flag. Any exception to this rule
7424 should be discussed on the mailing list
7425 <em>debian-devel@lists.debian.org</em>, and the reasons for
7426 compiling with the <tt>-fPIC</tt> flag must be recorded in
7427 the file <tt>README.Debian</tt>. <footnote>
7429 Some of the reasons for linking static libraries with
7430 the <tt>-fPIC</tt> flag are if, for example, one needs a
7431 Perl API for a library that is under rapid development,
7432 and has an unstable API, so shared libraries are
7433 pointless at this phase of the library's development. In
7434 that case, since Perl needs a library with relocatable
7435 code, it may make sense to create a static library with
7436 relocatable code. Another reason cited is if you are
7437 distilling various libraries into a common shared
7438 library, like <tt>mklibs</tt> does in the Debian
7444 In other words, if both a shared and a static library is
7445 being built, each source unit (<tt>*.c</tt>, for example,
7446 for C files) will need to be compiled twice, for the normal
7451 Libraries should be built with threading support and to be
7452 thread-safe if the library supports this.
7456 Although not enforced by the build tools, shared libraries
7457 must be linked against all libraries that they use symbols from
7458 in the same way that binaries are. This ensures the correct
7459 functioning of the <qref id="sharedlibs-shlibdeps">shlibs</qref>
7460 system and guarantees that all libraries can be safely opened
7461 with <tt>dlopen()</tt>. Packagers may wish to use the gcc
7462 option <tt>-Wl,-z,defs</tt> when building a shared library.
7463 Since this option enforces symbol resolution at build time,
7464 a missing library reference will be caught early as a fatal
7469 All installed shared libraries should be stripped with
7470 <example compact="compact">
7471 strip --strip-unneeded <var>your-lib</var>
7473 (The option <tt>--strip-unneeded</tt> makes
7474 <prgn>strip</prgn> remove only the symbols which aren't
7475 needed for relocation processing.) Shared libraries can
7476 function perfectly well when stripped, since the symbols for
7477 dynamic linking are in a separate part of the ELF object
7479 You might also want to use the options
7480 <tt>--remove-section=.comment</tt> and
7481 <tt>--remove-section=.note</tt> on both shared libraries
7482 and executables, and <tt>--strip-debug</tt> on static
7488 Note that under some circumstances it may be useful to
7489 install a shared library unstripped, for example when
7490 building a separate package to support debugging.
7494 Shared object files (often <file>.so</file> files) that are not
7495 public libraries, that is, they are not meant to be linked
7496 to by third party executables (binaries of other packages),
7497 should be installed in subdirectories of the
7498 <file>/usr/lib</file> directory. Such files are exempt from the
7499 rules that govern ordinary shared libraries, except that
7500 they must not be installed executable and should be
7502 A common example are the so-called "plug-ins",
7503 internal shared objects that are dynamically loaded by
7504 programs using <manref name="dlopen" section="3">.
7509 Packages that use <prgn>libtool</prgn> to create and install
7510 their shared libraries install a file containing additional
7511 metadata (ending in <file>.la</file>) alongside the library.
7512 For public libraries intended for use by other packages, these
7513 files normally should not be included in the Debian package,
7514 since the information they include is not necessary to link with
7515 the shared library on Debian and can add unnecessary additional
7516 dependencies to other programs or libraries.<footnote>
7517 These files store, among other things, all libraries on which
7518 that shared library depends. Unfortunately, if
7519 the <file>.la</file> file is present and contains that
7520 dependency information, using <prgn>libtool</prgn> when
7521 linking against that library will cause the resulting program
7522 or library to be linked against those dependencies as well,
7523 even if this is unnecessary. This can create unneeded
7524 dependencies on shared library packages that would otherwise
7525 be hidden behind the library ABI, and can make library
7526 transitions to new SONAMEs unnecessarily complicated and
7527 difficult to manage.
7529 If the <file>.la</file> file is required for that library (if,
7530 for instance, it's loaded via <tt>libltdl</tt> in a way that
7531 requires that meta-information), the <tt>dependency_libs</tt>
7532 setting in the <file>.la</file> file should normally be set to
7533 the empty string. If the shared library development package has
7534 historically included the <file>.la</file>, it must be retained
7535 in the development package (with <tt>dependency_libs</tt>
7536 emptied) until all libraries that depend on it have removed or
7537 emptied <tt>dependency_libs</tt> in their <file>.la</file>
7538 files to prevent linking with those other libraries
7539 using <prgn>libtool</prgn> from failing.
7543 If the <file>.la</file> must be included, it should be included
7544 in the development (<tt>-dev</tt>) package, unless the library
7545 will be loaded by <prgn>libtool</prgn>'s <tt>libltdl</tt>
7546 library. If it is intended for use with <tt>libltdl</tt>,
7547 the <file>.la</file> files must go in the run-time library
7552 These requirements for handling of <file>.la</file> files do not
7553 apply to loadable modules or libraries not installed in
7554 directories searched by default by the dynamic linker. Packages
7555 installing loadable modules will frequently need to install
7556 the <file>.la</file> files alongside the modules so that they
7557 can be loaded by <tt>libltdl</tt>. <tt>dependency_libs</tt>
7558 does not need to be modified for libraries or modules that are
7559 not installed in directories searched by the dynamic linker by
7560 default and not intended for use by other packages.
7564 You must make sure that you use only released versions of
7565 shared libraries to build your packages; otherwise other
7566 users will not be able to run your binaries
7567 properly. Producing source packages that depend on
7568 unreleased compilers is also usually a bad
7575 <heading>Shared libraries</heading>
7577 This section has moved to <ref id="sharedlibs">.
7583 <heading>Scripts</heading>
7586 All command scripts, including the package maintainer
7587 scripts inside the package and used by <prgn>dpkg</prgn>,
7588 should have a <tt>#!</tt> line naming the shell to be used
7593 In the case of Perl scripts this should be
7594 <tt>#!/usr/bin/perl</tt>.
7598 When scripts are installed into a directory in the system
7599 PATH, the script name should not include an extension such
7600 as <tt>.sh</tt> or <tt>.pl</tt> that denotes the scripting
7601 language currently used to implement it.
7604 Shell scripts (<prgn>sh</prgn> and <prgn>bash</prgn>) other than
7605 <file>init.d</file> scripts should almost certainly start
7606 with <tt>set -e</tt> so that errors are detected.
7607 <file>init.d</file> scripts are something of a special case, due
7608 to how frequently they need to call commands that are allowed to
7609 fail, and it may instead be easier to check the exit status of
7610 commands directly. See <ref id="writing-init"> for more
7611 information about writing <file>init.d</file> scripts.
7614 Every script should use <tt>set -e</tt> or check the exit status
7615 of <em>every</em> command.
7618 Scripts may assume that <file>/bin/sh</file> implements the
7619 SUSv3 Shell Command Language<footnote>
7620 Single UNIX Specification, version 3, which is also IEEE
7621 1003.1-2004 (POSIX), and is available on the World Wide Web
7622 from <url id="http://www.unix.org/version3/online.html"
7623 name="The Open Group"> after free
7624 registration.</footnote>
7625 plus the following additional features not mandated by
7627 These features are in widespread use in the Linux community
7628 and are implemented in all of bash, dash, and ksh, the most
7629 common shells users may wish to use as <file>/bin/sh</file>.
7632 <item><tt>echo -n</tt>, if implemented as a shell built-in,
7633 must not generate a newline.</item>
7634 <item><tt>test</tt>, if implemented as a shell built-in, must
7635 support <tt>-a</tt> and <tt>-o</tt> as binary logical
7637 <item><tt>local</tt> to create a scoped variable must be
7638 supported, including listing multiple variables in a single
7639 local command and assigning a value to a variable at the
7640 same time as localizing it. <tt>local</tt> may or
7641 may not preserve the variable value from an outer scope if
7642 no assignment is present. Uses such as:
7646 # ... use a, b, c, d ...
7649 must be supported and must set the value of <tt>c</tt> to
7652 <item>The XSI extension to <prgn>kill</prgn> allowing <tt>kill
7653 -<var>signal</var></tt>, where <var>signal</var> is either
7654 the name of a signal or one of the numeric signals listed in
7655 the XSI extension (0, 1, 2, 3, 6, 9, 14, and 15), must be
7656 supported if <prgn>kill</prgn> is implemented as a shell
7659 <item>The XSI extension to <prgn>trap</prgn> allowing numeric
7660 signals must be supported. In addition to the signal
7661 numbers listed in the extension, which are the same as for
7662 <prgn>kill</prgn> above, 13 (SIGPIPE) must be allowed.
7665 If a shell script requires non-SUSv3 features from the shell
7666 interpreter other than those listed above, the appropriate shell
7667 must be specified in the first line of the script (e.g.,
7668 <tt>#!/bin/bash</tt>) and the package must depend on the package
7669 providing the shell (unless the shell package is marked
7670 "Essential", as in the case of <prgn>bash</prgn>).
7674 You may wish to restrict your script to SUSv3 features plus the
7675 above set when possible so that it may use <file>/bin/sh</file>
7676 as its interpreter. If your script works with <prgn>dash</prgn>
7677 (originally called <prgn>ash</prgn>), it probably complies with
7678 the above requirements, but if you are in doubt, use
7679 <file>/bin/bash</file>.
7683 Perl scripts should check for errors when making any
7684 system calls, including <tt>open</tt>, <tt>print</tt>,
7685 <tt>close</tt>, <tt>rename</tt> and <tt>system</tt>.
7689 <prgn>csh</prgn> and <prgn>tcsh</prgn> should be avoided as
7690 scripting languages. See <em>Csh Programming Considered
7691 Harmful</em>, one of the <tt>comp.unix.*</tt> FAQs, which
7692 can be found at <url id="http://www.faqs.org/faqs/unix-faq/shell/csh-whynot/">.
7693 If an upstream package comes with <prgn>csh</prgn> scripts
7694 then you must make sure that they start with
7695 <tt>#!/bin/csh</tt> and make your package depend on the
7696 <prgn>c-shell</prgn> virtual package.
7700 Any scripts which create files in world-writeable
7701 directories (e.g., in <file>/tmp</file>) must use a
7702 mechanism which will fail atomically if a file with the same
7703 name already exists.
7707 The Debian base system provides the <prgn>tempfile</prgn>
7708 and <prgn>mktemp</prgn> utilities for use by scripts for
7715 <heading>Symbolic links</heading>
7718 In general, symbolic links within a top-level directory
7719 should be relative, and symbolic links pointing from one
7720 top-level directory into another should be absolute. (A
7721 top-level directory is a sub-directory of the root
7722 directory <file>/</file>.)
7726 In addition, symbolic links should be specified as short as
7727 possible, i.e., link targets like <file>foo/../bar</file> are
7732 Note that when creating a relative link using
7733 <prgn>ln</prgn> it is not necessary for the target of the
7734 link to exist relative to the working directory you're
7735 running <prgn>ln</prgn> from, nor is it necessary to change
7736 directory to the directory where the link is to be made.
7737 Simply include the string that should appear as the target
7738 of the link (this will be a pathname relative to the
7739 directory in which the link resides) as the first argument
7744 For example, in your <prgn>Makefile</prgn> or
7745 <file>debian/rules</file>, you can do things like:
7746 <example compact="compact">
7747 ln -fs gcc $(prefix)/bin/cc
7748 ln -fs gcc debian/tmp/usr/bin/cc
7749 ln -fs ../sbin/sendmail $(prefix)/bin/runq
7750 ln -fs ../sbin/sendmail debian/tmp/usr/bin/runq
7755 A symbolic link pointing to a compressed file should always
7756 have the same file extension as the referenced file. (For
7757 example, if a file <file>foo.gz</file> is referenced by a
7758 symbolic link, the filename of the link has to end with
7759 "<file>.gz</file>" too, as in <file>bar.gz</file>.)
7764 <heading>Device files</heading>
7767 Packages must not include device files or named pipes in the
7772 If a package needs any special device files that are not
7773 included in the base system, it must call
7774 <prgn>MAKEDEV</prgn> in the <prgn>postinst</prgn> script,
7775 after notifying the user<footnote>
7776 This notification could be done via a (low-priority)
7777 debconf message, or an echo (printf) statement.
7782 Packages must not remove any device files in the
7783 <prgn>postrm</prgn> or any other script. This is left to the
7784 system administrator.
7788 Debian uses the serial devices
7789 <file>/dev/ttyS*</file>. Programs using the old
7790 <file>/dev/cu*</file> devices should be changed to use
7791 <file>/dev/ttyS*</file>.
7795 Named pipes needed by the package must be created in
7796 the <prgn>postinst</prgn> script<footnote>
7797 It's better to use <prgn>mkfifo</prgn> rather
7798 than <prgn>mknod</prgn> to create named pipes so that
7799 automated checks for packages incorrectly creating device
7800 files with <prgn>mknod</prgn> won't have false positives.
7801 </footnote> and removed in
7802 the <prgn>prerm</prgn> or <prgn>postrm</prgn> script as
7807 <sect id="config-files">
7808 <heading>Configuration files</heading>
7811 <heading>Definitions</heading>
7815 <tag>configuration file</tag>
7817 A file that affects the operation of a program, or
7818 provides site- or host-specific information, or
7819 otherwise customizes the behavior of a program.
7820 Typically, configuration files are intended to be
7821 modified by the system administrator (if needed or
7822 desired) to conform to local policy or to provide
7823 more useful site-specific behavior.
7826 <tag><tt>conffile</tt></tag>
7828 A file listed in a package's <tt>conffiles</tt>
7829 file, and is treated specially by <prgn>dpkg</prgn>
7830 (see <ref id="configdetails">).
7836 The distinction between these two is important; they are
7837 not interchangeable concepts. Almost all
7838 <tt>conffile</tt>s are configuration files, but many
7839 configuration files are not <tt>conffiles</tt>.
7843 As noted elsewhere, <file>/etc/init.d</file> scripts,
7844 <file>/etc/default</file> files, scripts installed in
7845 <file>/etc/cron.{hourly,daily,weekly,monthly}</file>, and cron
7846 configuration installed in <file>/etc/cron.d</file> must be
7847 treated as configuration files. In general, any script that
7848 embeds configuration information is de-facto a configuration
7849 file and should be treated as such.
7854 <heading>Location</heading>
7857 Any configuration files created or used by your package
7858 must reside in <file>/etc</file>. If there are several,
7859 consider creating a subdirectory of <file>/etc</file>
7860 named after your package.
7864 If your package creates or uses configuration files
7865 outside of <file>/etc</file>, and it is not feasible to modify
7866 the package to use <file>/etc</file> directly, put the files
7867 in <file>/etc</file> and create symbolic links to those files
7868 from the location that the package requires.
7873 <heading>Behavior</heading>
7876 Configuration file handling must conform to the following
7878 <list compact="compact">
7880 local changes must be preserved during a package
7884 configuration files must be preserved when the
7885 package is removed, and only deleted when the
7889 Obsolete configuration files without local changes may be
7890 removed by the package during upgrade.
7894 The easy way to achieve this behavior is to make the
7895 configuration file a <tt>conffile</tt>. This is
7896 appropriate only if it is possible to distribute a default
7897 version that will work for most installations, although
7898 some system administrators may choose to modify it. This
7899 implies that the default version will be part of the
7900 package distribution, and must not be modified by the
7901 maintainer scripts during installation (or at any other
7906 In order to ensure that local changes are preserved
7907 correctly, no package may contain or make hard links to
7908 conffiles.<footnote>
7909 Rationale: There are two problems with hard links.
7910 The first is that some editors break the link while
7911 editing one of the files, so that the two files may
7912 unwittingly become unlinked and different. The second
7913 is that <prgn>dpkg</prgn> might break the hard link
7914 while upgrading <tt>conffile</tt>s.
7919 The other way to do it is via the maintainer scripts. In
7920 this case, the configuration file must not be listed as a
7921 <tt>conffile</tt> and must not be part of the package
7922 distribution. If the existence of a file is required for
7923 the package to be sensibly configured it is the
7924 responsibility of the package maintainer to provide
7925 maintainer scripts which correctly create, update and
7926 maintain the file and remove it on purge. (See <ref
7927 id="maintainerscripts"> for more information.) These
7928 scripts must be idempotent (i.e., must work correctly if
7929 <prgn>dpkg</prgn> needs to re-run them due to errors
7930 during installation or removal), must cope with all the
7931 variety of ways <prgn>dpkg</prgn> can call maintainer
7932 scripts, must not overwrite or otherwise mangle the user's
7933 configuration without asking, must not ask unnecessary
7934 questions (particularly during upgrades), and must
7935 otherwise be good citizens.
7939 The scripts are not required to configure every possible
7940 option for the package, but only those necessary to get
7941 the package running on a given system. Ideally the
7942 sysadmin should not have to do any configuration other
7943 than that done (semi-)automatically by the
7944 <prgn>postinst</prgn> script.
7948 A common practice is to create a script called
7949 <file><var>package</var>-configure</file> and have the
7950 package's <prgn>postinst</prgn> call it if and only if the
7951 configuration file does not already exist. In certain
7952 cases it is useful for there to be an example or template
7953 file which the maintainer scripts use. Such files should
7954 be in <file>/usr/share/<var>package</var></file> or
7955 <file>/usr/lib/<var>package</var></file> (depending on whether
7956 they are architecture-independent or not). There should
7957 be symbolic links to them from
7958 <file>/usr/share/doc/<var>package</var>/examples</file> if
7959 they are examples, and should be perfectly ordinary
7960 <prgn>dpkg</prgn>-handled files (<em>not</em>
7961 configuration files).
7965 These two styles of configuration file handling must
7966 not be mixed, for that way lies madness:
7967 <prgn>dpkg</prgn> will ask about overwriting the file
7968 every time the package is upgraded.
7973 <heading>Sharing configuration files</heading>
7976 Packages which specify the same file as a
7977 <tt>conffile</tt> must be tagged as <em>conflicting</em>
7978 with each other. (This is an instance of the general rule
7979 about not sharing files. Note that neither alternatives
7980 nor diversions are likely to be appropriate in this case;
7981 in particular, <prgn>dpkg</prgn> does not handle diverted
7982 <tt>conffile</tt>s well.)
7986 The maintainer scripts must not alter a <tt>conffile</tt>
7987 of <em>any</em> package, including the one the scripts
7992 If two or more packages use the same configuration file
7993 and it is reasonable for both to be installed at the same
7994 time, one of these packages must be defined as
7995 <em>owner</em> of the configuration file, i.e., it will be
7996 the package which handles that file as a configuration
7997 file. Other packages that use the configuration file must
7998 depend on the owning package if they require the
7999 configuration file to operate. If the other package will
8000 use the configuration file if present, but is capable of
8001 operating without it, no dependency need be declared.
8005 If it is desirable for two or more related packages to
8006 share a configuration file <em>and</em> for all of the
8007 related packages to be able to modify that configuration
8008 file, then the following should be done:
8009 <enumlist compact="compact">
8011 One of the related packages (the "owning" package)
8012 will manage the configuration file with maintainer
8013 scripts as described in the previous section.
8016 The owning package should also provide a program
8017 that the other packages may use to modify the
8021 The related packages must use the provided program
8022 to make any desired modifications to the
8023 configuration file. They should either depend on
8024 the core package to guarantee that the configuration
8025 modifier program is available or accept gracefully
8026 that they cannot modify the configuration file if it
8027 is not. (This is in addition to the fact that the
8028 configuration file may not even be present in the
8035 Sometimes it's appropriate to create a new package which
8036 provides the basic infrastructure for the other packages
8037 and which manages the shared configuration files. (The
8038 <tt>sgml-base</tt> package is a good example.)
8043 <heading>User configuration files ("dotfiles")</heading>
8046 The files in <file>/etc/skel</file> will automatically be
8047 copied into new user accounts by <prgn>adduser</prgn>.
8048 No other program should reference the files in
8049 <file>/etc/skel</file>.
8053 Therefore, if a program needs a dotfile to exist in
8054 advance in <file>$HOME</file> to work sensibly, that dotfile
8055 should be installed in <file>/etc/skel</file> and treated as a
8060 However, programs that require dotfiles in order to
8061 operate sensibly are a bad thing, unless they do create
8062 the dotfiles themselves automatically.
8066 Furthermore, programs should be configured by the Debian
8067 default installation to behave as closely to the upstream
8068 default behavior as possible.
8072 Therefore, if a program in a Debian package needs to be
8073 configured in some way in order to operate sensibly, that
8074 should be done using a site-wide configuration file placed
8075 in <file>/etc</file>. Only if the program doesn't support a
8076 site-wide default configuration and the package maintainer
8077 doesn't have time to add it may a default per-user file be
8078 placed in <file>/etc/skel</file>.
8082 <file>/etc/skel</file> should be as empty as we can make it.
8083 This is particularly true because there is no easy (or
8084 necessarily desirable) mechanism for ensuring that the
8085 appropriate dotfiles are copied into the accounts of
8086 existing users when a package is installed.
8092 <heading>Log files</heading>
8094 Log files should usually be named
8095 <file>/var/log/<var>package</var>.log</file>. If you have many
8096 log files, or need a separate directory for permission
8097 reasons (<file>/var/log</file> is writable only by
8098 <file>root</file>), you should usually create a directory named
8099 <file>/var/log/<var>package</var></file> and place your log
8104 Log files must be rotated occasionally so that they don't grow
8105 indefinitely. The best way to do this is to install a log
8106 rotation configuration file in the
8107 directory <file>/etc/logrotate.d</file>, normally
8108 named <file>/etc/logrotate.d/<var>package</var></file>, and use
8109 the facilities provided by <prgn>logrotate</prgn>.
8112 The traditional approach to log files has been to set up
8113 <em>ad hoc</em> log rotation schemes using simple shell
8114 scripts and cron. While this approach is highly
8115 customizable, it requires quite a lot of sysadmin work.
8116 Even though the original Debian system helped a little
8117 by automatically installing a system which can be used
8118 as a template, this was deemed not enough.
8122 The use of <prgn>logrotate</prgn>, a program developed
8123 by Red Hat, is better, as it centralizes log management.
8124 It has both a configuration file
8125 (<file>/etc/logrotate.conf</file>) and a directory where
8126 packages can drop their individual log rotation
8127 configurations (<file>/etc/logrotate.d</file>).
8130 Here is a good example for a logrotate config
8131 file (for more information see <manref name="logrotate"
8133 <example compact="compact">
8134 /var/log/foo/*.log {
8140 start-stop-daemon -K -p /var/run/foo.pid -s HUP -x /usr/sbin/foo -q
8144 This rotates all files under <file>/var/log/foo</file>, saves 12
8145 compressed generations, and tells the daemon to reopen its log
8146 files after the log rotation. It skips this log rotation
8147 (via <tt>missingok</tt>) if no such log file is present, which
8148 avoids errors if the package is removed but not purged.
8152 Log files should be removed when the package is
8153 purged (but not when it is only removed). This should be
8154 done by the <prgn>postrm</prgn> script when it is called
8155 with the argument <tt>purge</tt> (see <ref
8156 id="removedetails">).
8160 <sect id="permissions-owners">
8161 <heading>Permissions and owners</heading>
8164 The rules in this section are guidelines for general use.
8165 If necessary you may deviate from the details below.
8166 However, if you do so you must make sure that what is done
8167 is secure and you should try to be as consistent as possible
8168 with the rest of the system. You should probably also
8169 discuss it on <prgn>debian-devel</prgn> first.
8173 Files should be owned by <tt>root:root</tt>, and made
8174 writable only by the owner and universally readable (and
8175 executable, if appropriate), that is mode 644 or 755.
8179 Directories should be mode 755 or (for group-writability)
8180 mode 2775. The ownership of the directory should be
8181 consistent with its mode: if a directory is mode 2775, it
8182 should be owned by the group that needs write access to
8185 When a package is upgraded, and the owner or permissions
8186 of a file included in the package has changed, dpkg
8187 arranges for the ownership and permissions to be
8188 correctly set upon installation. However, this does not
8189 extend to directories; the permissions and ownership of
8190 directories already on the system does not change on
8191 install or upgrade of packages. This makes sense, since
8192 otherwise common directories like <tt>/usr</tt> would
8193 always be in flux. To correctly change permissions of a
8194 directory the package owns, explicit action is required,
8195 usually in the <tt>postinst</tt> script. Care must be
8196 taken to handle downgrades as well, in that case.
8202 Control information files should be owned by <tt>root:root</tt>
8203 and either mode 644 (for most files) or mode 755 (for
8204 executables such as <qref id="maintscripts">maintainer
8209 Setuid and setgid executables should be mode 4755 or 2755
8210 respectively, and owned by the appropriate user or group.
8211 They should not be made unreadable (modes like 4711 or
8212 2711 or even 4111); doing so achieves no extra security,
8213 because anyone can find the binary in the freely available
8214 Debian package; it is merely inconvenient. For the same
8215 reason you should not restrict read or execute permissions
8216 on non-set-id executables.
8220 Some setuid programs need to be restricted to particular
8221 sets of users, using file permissions. In this case they
8222 should be owned by the uid to which they are set-id, and by
8223 the group which should be allowed to execute them. They
8224 should have mode 4754; again there is no point in making
8225 them unreadable to those users who must not be allowed to
8230 It is possible to arrange that the system administrator can
8231 reconfigure the package to correspond to their local
8232 security policy by changing the permissions on a binary:
8233 they can do this by using <prgn>dpkg-statoverride</prgn>, as
8234 described below.<footnote>
8235 Ordinary files installed by <prgn>dpkg</prgn> (as
8236 opposed to <tt>conffile</tt>s and other similar objects)
8237 normally have their permissions reset to the distributed
8238 permissions when the package is reinstalled. However,
8239 the use of <prgn>dpkg-statoverride</prgn> overrides this
8242 Another method you should consider is to create a group for
8243 people allowed to use the program(s) and make any setuid
8244 executables executable only by that group.
8248 If you need to create a new user or group for your package
8249 there are two possibilities. Firstly, you may need to
8250 make some files in the binary package be owned by this
8251 user or group, or you may need to compile the user or
8252 group id (rather than just the name) into the binary
8253 (though this latter should be avoided if possible, as in
8254 this case you need a statically allocated id).</p>
8257 If you need a statically allocated id, you must ask for a
8258 user or group id from the <tt>base-passwd</tt> maintainer,
8259 and must not release the package until you have been
8260 allocated one. Once you have been allocated one you must
8261 either make the package depend on a version of the
8262 <tt>base-passwd</tt> package with the id present in
8263 <file>/etc/passwd</file> or <file>/etc/group</file>, or arrange for
8264 your package to create the user or group itself with the
8265 correct id (using <tt>adduser</tt>) in its
8266 <prgn>preinst</prgn> or <prgn>postinst</prgn>. (Doing it in
8267 the <prgn>postinst</prgn> is to be preferred if it is
8268 possible, otherwise a pre-dependency will be needed on the
8269 <tt>adduser</tt> package.)
8273 On the other hand, the program might be able to determine
8274 the uid or gid from the user or group name at runtime, so
8275 that a dynamically allocated id can be used. In this case
8276 you should choose an appropriate user or group name,
8277 discussing this on <prgn>debian-devel</prgn> and checking
8278 with the <package/base-passwd/ maintainer that it is unique and that
8279 they do not wish you to use a statically allocated id
8280 instead. When this has been checked you must arrange for
8281 your package to create the user or group if necessary using
8282 <prgn>adduser</prgn> in the <prgn>preinst</prgn> or
8283 <prgn>postinst</prgn> script (again, the latter is to be
8284 preferred if it is possible).
8288 Note that changing the numeric value of an id associated
8289 with a name is very difficult, and involves searching the
8290 file system for all appropriate files. You need to think
8291 carefully whether a static or dynamic id is required, since
8292 changing your mind later will cause problems.
8295 <sect1><heading>The use of <prgn>dpkg-statoverride</prgn></heading>
8297 This section is not intended as policy, but as a
8298 description of the use of <prgn>dpkg-statoverride</prgn>.
8302 If a system administrator wishes to have a file (or
8303 directory or other such thing) installed with owner and
8304 permissions different from those in the distributed Debian
8305 package, they can use the <prgn>dpkg-statoverride</prgn>
8306 program to instruct <prgn>dpkg</prgn> to use the different
8307 settings every time the file is installed. Thus the
8308 package maintainer should distribute the files with their
8309 normal permissions, and leave it for the system
8310 administrator to make any desired changes. For example, a
8311 daemon which is normally required to be setuid root, but
8312 in certain situations could be used without being setuid,
8313 should be installed setuid in the <tt>.deb</tt>. Then the
8314 local system administrator can change this if they wish.
8315 If there are two standard ways of doing it, the package
8316 maintainer can use <tt>debconf</tt> to find out the
8317 preference, and call <prgn>dpkg-statoverride</prgn> in the
8318 maintainer script if necessary to accommodate the system
8319 administrator's choice. Care must be taken during
8320 upgrades to not override an existing setting.
8324 Given the above, <prgn>dpkg-statoverride</prgn> is
8325 essentially a tool for system administrators and would not
8326 normally be needed in the maintainer scripts. There is
8327 one type of situation, though, where calls to
8328 <prgn>dpkg-statoverride</prgn> would be needed in the
8329 maintainer scripts, and that involves packages which use
8330 dynamically allocated user or group ids. In such a
8331 situation, something like the following idiom can be very
8332 helpful in the package's <prgn>postinst</prgn>, where
8333 <tt>sysuser</tt> is a dynamically allocated id:
8335 for i in /usr/bin/foo /usr/sbin/bar
8337 # only do something when no setting exists
8338 if ! dpkg-statoverride --list $i >/dev/null 2>&1
8340 #include: debconf processing, question about foo and bar
8341 if [ "$RET" = "true" ] ; then
8342 dpkg-statoverride --update --add sysuser root 4755 $i
8347 The corresponding code to remove the override when the package
8350 for i in /usr/bin/foo /usr/sbin/bar
8352 if dpkg-statoverride --list $i >/dev/null 2>&1
8354 dpkg-statoverride --remove $i
8364 <chapt id="customized-programs">
8365 <heading>Customized programs</heading>
8367 <sect id="arch-spec">
8368 <heading>Architecture specification strings</heading>
8371 If a program needs to specify an <em>architecture specification
8372 string</em> in some place, it should select one of the strings
8373 provided by <tt>dpkg-architecture -L</tt>. The strings are in
8374 the format <tt><var>os</var>-<var>arch</var></tt>, though the OS
8375 part is sometimes elided, as when the OS is Linux.
8379 Note that we don't want to use
8380 <tt><var>arch</var>-debian-linux</tt> to apply to the rule
8381 <tt><var>architecture</var>-<var>vendor</var>-<var>os</var></tt>
8382 since this would make our programs incompatible with other
8383 Linux distributions. We also don't use something like
8384 <tt><var>arch</var>-unknown-linux</tt>, since the
8385 <tt>unknown</tt> does not look very good.
8388 <sect1 id="arch-wildcard-spec">
8389 <heading>Architecture wildcards</heading>
8392 A package may specify an architecture wildcard. Architecture
8393 wildcards are in the format <tt>any</tt> (which matches every
8394 architecture), <tt><var>os</var></tt>-any, or
8395 any-<tt><var>cpu</var></tt>. <footnote>
8396 Internally, the package system normalizes the GNU triplets
8397 and the Debian arches into Debian arch triplets (which are
8398 kind of inverted GNU triplets), with the first component of
8399 the triplet representing the libc and ABI in use, and then
8400 does matching against those triplets. However, such
8401 triplets are an internal implementation detail that should
8402 not be used by packages directly. The libc and ABI portion
8403 is handled internally by the package system based on
8404 the <var>os</var> and <var>cpu</var>.
8411 <heading>Daemons</heading>
8414 The configuration files <file>/etc/services</file>,
8415 <file>/etc/protocols</file>, and <file>/etc/rpc</file> are managed
8416 by the <prgn>netbase</prgn> package and must not be modified
8421 If a package requires a new entry in one of these files, the
8422 maintainer should get in contact with the
8423 <prgn>netbase</prgn> maintainer, who will add the entries
8424 and release a new version of the <prgn>netbase</prgn>
8429 The configuration file <file>/etc/inetd.conf</file> must not be
8430 modified by the package's scripts except via the
8431 <prgn>update-inetd</prgn> script or the
8432 <file>DebianNet.pm</file> Perl module. See their documentation
8433 for details on how to add entries.
8437 If a package wants to install an example entry into
8438 <file>/etc/inetd.conf</file>, the entry must be preceded with
8439 exactly one hash character (<tt>#</tt>). Such lines are
8440 treated as "commented out by user" by the
8441 <prgn>update-inetd</prgn> script and are not changed or
8442 activated during package updates.
8447 <heading>Using pseudo-ttys and modifying wtmp, utmp and
8451 Some programs need to create pseudo-ttys. This should be done
8452 using Unix98 ptys if the C library supports it. The resulting
8453 program must not be installed setuid root, unless that
8454 is required for other functionality.
8458 The files <file>/var/run/utmp</file>, <file>/var/log/wtmp</file> and
8459 <file>/var/log/lastlog</file> must be installed writable by
8460 group <tt>utmp</tt>. Programs which need to modify those
8461 files must be installed setgid <tt>utmp</tt>.
8466 <heading>Editors and pagers</heading>
8469 Some programs have the ability to launch an editor or pager
8470 program to edit or display a text document. Since there are
8471 lots of different editors and pagers available in the Debian
8472 distribution, the system administrator and each user should
8473 have the possibility to choose their preferred editor and
8478 In addition, every program should choose a good default
8479 editor/pager if none is selected by the user or system
8484 Thus, every program that launches an editor or pager must
8485 use the EDITOR or PAGER environment variable to determine
8486 the editor or pager the user wishes to use. If these
8487 variables are not set, the programs <file>/usr/bin/editor</file>
8488 and <file>/usr/bin/pager</file> should be used, respectively.
8492 These two files are managed through the <prgn>dpkg</prgn>
8493 "alternatives" mechanism. Every package providing an editor or
8494 pager must call the <prgn>update-alternatives</prgn> script to
8495 register as an alternative for <file>/usr/bin/editor</file>
8496 or <file>/usr/bin/pager</file> as appropriate. The alternative
8497 should have a slave alternative
8498 for <file>/usr/share/man/man1/editor.1.gz</file>
8499 or <file>/usr/share/man/man1/pager.1.gz</file> pointing to the
8500 corresponding manual page.
8504 If it is very hard to adapt a program to make use of the
8505 EDITOR or PAGER variables, that program may be configured to
8506 use <file>/usr/bin/sensible-editor</file> and
8507 <file>/usr/bin/sensible-pager</file> as the editor or pager
8508 program respectively. These are two scripts provided in the
8509 <package>sensible-utils</package> package that check the EDITOR
8510 and PAGER variables and launch the appropriate program, and fall
8511 back to <file>/usr/bin/editor</file>
8512 and <file>/usr/bin/pager</file> if the variable is not set.
8516 A program may also use the VISUAL environment variable to
8517 determine the user's choice of editor. If it exists, it
8518 should take precedence over EDITOR. This is in fact what
8519 <file>/usr/bin/sensible-editor</file> does.
8523 It is not required for a package to depend on
8524 <tt>editor</tt> and <tt>pager</tt>, nor is it required for a
8525 package to provide such virtual packages.<footnote>
8526 The Debian base system already provides an editor and a
8532 <sect id="web-appl">
8533 <heading>Web servers and applications</heading>
8536 This section describes the locations and URLs that should
8537 be used by all web servers and web applications in the
8544 Cgi-bin executable files are installed in the
8546 <example compact="compact">
8547 /usr/lib/cgi-bin/<var>cgi-bin-name</var>
8549 or a subdirectory of that directory, and should be
8551 <example compact="compact">
8552 http://localhost/cgi-bin/<var>cgi-bin-name</var>
8554 (possibly with a subdirectory name
8555 before <var>cgi-bin-name</var>).
8559 <p>Access to HTML documents</p>
8562 HTML documents for a package are stored in
8563 <file>/usr/share/doc/<var>package</var></file>
8564 and can be referred to as
8565 <example compact="compact">
8566 http://localhost/doc/<var>package</var>/<var>filename</var>
8571 The web server should restrict access to the document
8572 tree so that only clients on the same host can read
8573 the documents. If the web server does not support such
8574 access controls, then it should not provide access at
8575 all, or ask about providing access during installation.
8580 <p>Access to images</p>
8582 It is recommended that images for a package be stored
8583 in <tt>/usr/share/images/<var>package</var></tt> and
8584 may be referred to through an alias <tt>/images/</tt>
8587 http://localhost/images/<package>/<filename>
8594 <p>Web Document Root</p>
8597 Web Applications should try to avoid storing files in
8598 the Web Document Root. Instead they should use the
8599 /usr/share/doc/<var>package</var> directory for
8600 documents and register the Web Application via the
8601 <package>doc-base</package> package. If access to the
8602 web document root is unavoidable then use
8603 <example compact="compact">
8606 as the Document Root. This might be just a symbolic
8607 link to the location where the system administrator
8608 has put the real document root.
8611 <item><p>Providing httpd and/or httpd-cgi</p>
8613 All web servers should provide the virtual package
8614 <tt>httpd</tt>. If a web server has CGI support it should
8615 provide <tt>httpd-cgi</tt> additionally.
8618 All web applications which do not contain CGI scripts should
8619 depend on <tt>httpd</tt>, all those web applications which
8620 <tt>do</tt> contain CGI scripts, should depend on
8628 <sect id="mail-transport-agents">
8629 <heading>Mail transport, delivery and user agents</heading>
8632 Debian packages which process electronic mail, whether mail
8633 user agents (MUAs) or mail transport agents (MTAs), must
8634 ensure that they are compatible with the configuration
8635 decisions below. Failure to do this may result in lost
8636 mail, broken <tt>From:</tt> lines, and other serious brain
8641 The mail spool is <file>/var/mail</file> and the interface to
8642 send a mail message is <file>/usr/sbin/sendmail</file> (as per
8643 the FHS). On older systems, the mail spool may be
8644 physically located in <file>/var/spool/mail</file>, but all
8645 access to the mail spool should be via the
8646 <file>/var/mail</file> symlink. The mail spool is part of the
8647 base system and not part of the MTA package.
8651 All Debian MUAs, MTAs, MDAs and other mailbox accessing
8652 programs (such as IMAP daemons) must lock the mailbox in an
8653 NFS-safe way. This means that <tt>fcntl()</tt> locking must
8654 be combined with dot locking. To avoid deadlocks, a program
8655 should use <tt>fcntl()</tt> first and dot locking after
8656 this, or alternatively implement the two locking methods in
8657 a non blocking way<footnote>
8658 If it is not possible to establish both locks, the
8659 system shouldn't wait for the second lock to be
8660 established, but remove the first lock, wait a (random)
8661 time, and start over locking again.
8662 </footnote>. Using the functions <tt>maillock</tt> and
8663 <tt>mailunlock</tt> provided by the
8664 <tt>liblockfile*</tt><footnote>
8665 You will need to depend on <tt>liblockfile1 (>>1.01)</tt>
8666 to use these functions.
8667 </footnote> packages is the recommended way to realize this.
8671 Mailboxes are generally either mode 600 and owned by
8672 <var>user</var> or mode 660 and owned by
8673 <tt><var>user</var>:mail</tt><footnote>
8674 There are two traditional permission schemes for mail spools:
8675 mode 600 with all mail delivery done by processes running as
8676 the destination user, or mode 660 and owned by group mail with
8677 mail delivery done by a process running as a system user in
8678 group mail. Historically, Debian required mode 660 mail
8679 spools to enable the latter model, but that model has become
8680 increasingly uncommon and the principle of least privilege
8681 indicates that mail systems that use the first model should
8682 use permissions of 600. If delivery to programs is permitted,
8683 it's easier to keep the mail system secure if the delivery
8684 agent runs as the destination user. Debian Policy therefore
8685 permits either scheme.
8686 </footnote>. The local system administrator may choose a
8687 different permission scheme; packages should not make
8688 assumptions about the permission and ownership of mailboxes
8689 unless required (such as when creating a new mailbox). A MUA
8690 may remove a mailbox (unless it has nonstandard permissions) in
8691 which case the MTA or another MUA must recreate it if needed.
8695 The mail spool is 2775 <tt>root:mail</tt>, and MUAs should
8696 be setgid mail to do the locking mentioned above (and
8697 must obviously avoid accessing other users' mailboxes
8698 using this privilege).</p>
8701 <file>/etc/aliases</file> is the source file for the system mail
8702 aliases (e.g., postmaster, usenet, etc.), it is the one
8703 which the sysadmin and <prgn>postinst</prgn> scripts may
8704 edit. After <file>/etc/aliases</file> is edited the program or
8705 human editing it must call <prgn>newaliases</prgn>. All MTA
8706 packages must come with a <prgn>newaliases</prgn> program,
8707 even if it does nothing, but older MTA packages did not do
8708 this so programs should not fail if <prgn>newaliases</prgn>
8709 cannot be found. Note that because of this, all MTA
8710 packages must have <tt>Provides</tt>, <tt>Conflicts</tt> and
8711 <tt>Replaces: mail-transport-agent</tt> control fields.
8715 The convention of writing <tt>forward to
8716 <var>address</var></tt> in the mailbox itself is not
8717 supported. Use a <tt>.forward</tt> file instead.</p>
8720 The <prgn>rmail</prgn> program used by UUCP
8721 for incoming mail should be <file>/usr/sbin/rmail</file>.
8722 Likewise, <prgn>rsmtp</prgn>, for receiving
8723 batch-SMTP-over-UUCP, should be <file>/usr/sbin/rsmtp</file> if it
8727 If your package needs to know what hostname to use on (for
8728 example) outgoing news and mail messages which are generated
8729 locally, you should use the file <file>/etc/mailname</file>. It
8730 will contain the portion after the username and <tt>@</tt>
8731 (at) sign for email addresses of users on the machine
8732 (followed by a newline).
8736 Such a package should check for the existence of this file
8737 when it is being configured. If it exists, it should be
8738 used without comment, although an MTA's configuration script
8739 may wish to prompt the user even if it finds that this file
8740 exists. If the file does not exist, the package should
8741 prompt the user for the value (preferably using
8742 <prgn>debconf</prgn>) and store it in <file>/etc/mailname</file>
8743 as well as using it in the package's configuration. The
8744 prompt should make it clear that the name will not just be
8745 used by that package. For example, in this situation the
8746 <tt>inn</tt> package could say something like:
8747 <example compact="compact">
8748 Please enter the "mail name" of your system. This is the
8749 hostname portion of the address to be shown on outgoing
8750 news and mail messages. The default is
8751 <var>syshostname</var>, your system's host name. Mail
8752 name ["<var>syshostname</var>"]:
8754 where <var>syshostname</var> is the output of <tt>hostname
8760 <heading>News system configuration</heading>
8763 All the configuration files related to the NNTP (news)
8764 servers and clients should be located under
8765 <file>/etc/news</file>.</p>
8768 There are some configuration issues that apply to a number
8769 of news clients and server packages on the machine. These
8773 <tag><file>/etc/news/organization</file></tag>
8775 A string which should appear as the
8776 organization header for all messages posted
8777 by NNTP clients on the machine
8780 <tag><file>/etc/news/server</file></tag>
8782 Contains the FQDN of the upstream NNTP
8783 server, or localhost if the local machine is
8788 Other global files may be added as required for cross-package news
8795 <heading>Programs for the X Window System</heading>
8798 <heading>Providing X support and package priorities</heading>
8801 Programs that can be configured with support for the X
8802 Window System must be configured to do so and must declare
8803 any package dependencies necessary to satisfy their
8804 runtime requirements when using the X Window System. If
8805 such a package is of higher priority than the X packages
8806 on which it depends, it is required that either the
8807 X-specific components be split into a separate package, or
8808 that an alternative version of the package, which includes
8809 X support, be provided, or that the package's priority be
8815 <heading>Packages providing an X server</heading>
8818 Packages that provide an X server that, directly or
8819 indirectly, communicates with real input and display
8820 hardware should declare in their <tt>Provides</tt> control
8821 field that they provide the virtual
8822 package <tt>xserver</tt>.<footnote>
8823 This implements current practice, and provides an
8824 actual policy for usage of the <tt>xserver</tt>
8825 virtual package which appears in the virtual packages
8826 list. In a nutshell, X servers that interface
8827 directly with the display and input hardware or via
8828 another subsystem (e.g., GGI) should provide
8829 <tt>xserver</tt>. Things like <tt>Xvfb</tt>,
8830 <tt>Xnest</tt>, and <tt>Xprt</tt> should not.
8836 <heading>Packages providing a terminal emulator</heading>
8839 Packages that provide a terminal emulator for the X Window
8840 System which meet the criteria listed below should declare in
8841 their <tt>Provides</tt> control field that they provide the
8842 virtual package <tt>x-terminal-emulator</tt>. They should
8843 also register themselves as an alternative for
8844 <file>/usr/bin/x-terminal-emulator</file>, with a priority of
8845 20. That alternative should have a slave alternative
8846 for <file>/usr/share/man/man1/x-terminal-emulator.1.gz</file>
8847 pointing to the corresponding manual page.
8851 To be an <tt>x-terminal-emulator</tt>, a program must:
8852 <list compact="compact">
8854 Be able to emulate a DEC VT100 terminal, or a
8855 compatible terminal.
8859 Support the command-line option <tt>-e
8860 <var>command</var></tt>, which creates a new
8861 terminal window<footnote>
8862 "New terminal window" does not necessarily mean
8863 a new top-level X window directly parented by
8864 the window manager; it could, if the terminal
8865 emulator application were so coded, be a new
8866 "view" in a multiple-document interface (MDI).
8868 and runs the specified <var>command</var>,
8869 interpreting the entirety of the rest of the command
8870 line as a command to pass straight to exec, in the
8871 manner that <tt>xterm</tt> does.
8875 Support the command-line option <tt>-T
8876 <var>title</var></tt>, which creates a new terminal
8877 window with the window title <var>title</var>.
8884 <heading>Packages providing a window manager</heading>
8887 Packages that provide a window manager should declare in
8888 their <tt>Provides</tt> control field that they provide the
8889 virtual package <tt>x-window-manager</tt>. They should also
8890 register themselves as an alternative for
8891 <file>/usr/bin/x-window-manager</file>, with a priority
8892 calculated as follows:
8893 <list compact="compact">
8895 Start with a priority of 20.
8899 If the window manager supports the Debian menu
8900 system, add 20 points if this support is available
8901 in the package's default configuration (i.e., no
8902 configuration files belonging to the system or user
8903 have to be edited to activate the feature); if
8904 configuration files must be modified, add only 10
8910 If the window manager complies with <url
8911 id="http://www.freedesktop.org/Standards/wm-spec"
8912 name="The Window Manager Specification Project">,
8913 written by the <url id="http://www.freedesktop.org/"
8914 name="Free Desktop Group">, add 40 points.
8918 If the window manager permits the X session to be
8919 restarted using a <em>different</em> window manager
8920 (without killing the X server) in its default
8921 configuration, add 10 points; otherwise add none.
8924 That alternative should have a slave alternative
8925 for <file>/usr/share/man/man1/x-window-manager.1.gz</file>
8926 pointing to the corresponding manual page.
8931 <heading>Packages providing fonts</heading>
8934 Packages that provide fonts for the X Window
8936 For the purposes of Debian Policy, a "font for the X
8937 Window System" is one which is accessed via X protocol
8938 requests. Fonts for the Linux console, for PostScript
8939 renderer, or any other purpose, do not fit this
8940 definition. Any tool which makes such fonts available
8941 to the X Window System, however, must abide by this
8944 must do a number of things to ensure that they are both
8945 available without modification of the X or font server
8946 configuration, and that they do not corrupt files used by
8947 other font packages to register information about
8951 Fonts of any type supported by the X Window System
8952 must be in a separate binary package from any
8953 executables, libraries, or documentation (except
8954 that specific to the fonts shipped, such as their
8955 license information). If one or more of the fonts
8956 so packaged are necessary for proper operation of
8957 the package with which they are associated the font
8958 package may be Recommended; if the fonts merely
8959 provide an enhancement, a Suggests relationship may
8960 be used. Packages must not Depend on font
8962 This is because the X server may retrieve fonts
8963 from the local file system or over the network
8964 from an X font server; the Debian package system
8965 is empowered to deal only with the local
8971 BDF fonts must be converted to PCF fonts with the
8972 <prgn>bdftopcf</prgn> utility (available in the
8973 <tt>xfonts-utils</tt> package, <prgn>gzip</prgn>ped, and
8974 placed in a directory that corresponds to their
8976 <list compact="compact">
8978 100 dpi fonts must be placed in
8979 <file>/usr/share/fonts/X11/100dpi/</file>.
8983 75 dpi fonts must be placed in
8984 <file>/usr/share/fonts/X11/75dpi/</file>.
8988 Character-cell fonts, cursor fonts, and other
8989 low-resolution fonts must be placed in
8990 <file>/usr/share/fonts/X11/misc/</file>.
8996 Type 1 fonts must be placed in
8997 <file>/usr/share/fonts/X11/Type1/</file>. If font
8998 metric files are available, they must be placed here
9003 Subdirectories of <file>/usr/share/fonts/X11/</file>
9004 other than those listed above must be neither
9005 created nor used. (The <file>PEX</file>, <file>CID</file>,
9006 <file>Speedo</file>, and <file>cyrillic</file> directories
9007 are excepted for historical reasons, but installation of
9008 files into these directories remains discouraged.)
9012 Font packages may, instead of placing files directly
9013 in the X font directories listed above, provide
9014 symbolic links in that font directory pointing to
9015 the files' actual location in the filesystem. Such
9016 a location must comply with the FHS.
9020 Font packages should not contain both 75dpi and
9021 100dpi versions of a font. If both are available,
9022 they should be provided in separate binary packages
9023 with <tt>-75dpi</tt> or <tt>-100dpi</tt> appended to
9024 the names of the packages containing the
9025 corresponding fonts.
9029 Fonts destined for the <file>misc</file> subdirectory
9030 should not be included in the same package as 75dpi
9031 or 100dpi fonts; instead, they should be provided in
9032 a separate package with <tt>-misc</tt> appended to
9037 Font packages must not provide the files
9038 <file>fonts.dir</file>, <file>fonts.alias</file>, or
9039 <file>fonts.scale</file> in a font directory:
9042 <file>fonts.dir</file> files must not be provided at all.
9046 <file>fonts.alias</file> and <file>fonts.scale</file>
9047 files, if needed, should be provided in the
9049 <file>/etc/X11/fonts/<var>fontdir</var>/<var>package</var>.<var>extension</var></file>,
9050 where <var>fontdir</var> is the name of the
9052 <file>/usr/share/fonts/X11/</file> where the
9053 package's corresponding fonts are stored
9054 (e.g., <tt>75dpi</tt> or <tt>misc</tt>),
9055 <var>package</var> is the name of the package
9056 that provides these fonts, and
9057 <var>extension</var> is either <tt>scale</tt>
9058 or <tt>alias</tt>, whichever corresponds to
9065 Font packages must declare a dependency on
9066 <tt>xfonts-utils</tt> in their <tt>Depends</tt>
9067 or <tt>Pre-Depends</tt> control field.
9071 Font packages that provide one or more
9072 <file>fonts.scale</file> files as described above must
9073 invoke <prgn>update-fonts-scale</prgn> on each
9074 directory into which they installed fonts
9075 <em>before</em> invoking
9076 <prgn>update-fonts-dir</prgn> on that directory.
9077 This invocation must occur in both the
9078 <prgn>postinst</prgn> (for all arguments) and
9079 <prgn>postrm</prgn> (for all arguments except
9080 <tt>upgrade</tt>) scripts.
9084 Font packages that provide one or more
9085 <file>fonts.alias</file> files as described above must
9086 invoke <prgn>update-fonts-alias</prgn> on each
9087 directory into which they installed fonts. This
9088 invocation must occur in both the
9089 <prgn>postinst</prgn> (for all arguments) and
9090 <prgn>postrm</prgn> (for all arguments except
9091 <tt>upgrade</tt>) scripts.
9095 Font packages must invoke
9096 <prgn>update-fonts-dir</prgn> on each directory into
9097 which they installed fonts. This invocation must
9098 occur in both the <prgn>postinst</prgn> (for all
9099 arguments) and <prgn>postrm</prgn> (for all
9100 arguments except <tt>upgrade</tt>) scripts.
9104 Font packages must not provide alias names for the
9105 fonts they include which collide with alias names
9106 already in use by fonts already packaged.
9110 Font packages must not provide fonts with the same
9111 XLFD registry name as another font already packaged.
9117 <sect1 id="appdefaults">
9118 <heading>Application defaults files</heading>
9121 Application defaults files must be installed in the
9122 directory <file>/etc/X11/app-defaults/</file> (use of a
9123 localized subdirectory of <file>/etc/X11/</file> as described
9124 in the <em>X Toolkit Intrinsics - C Language
9125 Interface</em> manual is also permitted). They must be
9126 registered as <tt>conffile</tt>s or handled as
9127 configuration files.
9131 Customization of programs' X resources may also be
9132 supported with the provision of a file with the same name
9133 as that of the package placed in
9134 the <file>/etc/X11/Xresources/</file> directory, which
9135 must be registered as a <tt>conffile</tt> or handled as a
9136 configuration file.<footnote>
9137 Note that this mechanism is not the same as using
9138 app-defaults; app-defaults are tied to the client
9139 binary on the local file system, whereas X resources
9140 are stored in the X server and affect all connecting
9147 <heading>Installation directory issues</heading>
9150 Historically, packages using the X Window System used a
9151 separate set of installation directories from other packages.
9152 This practice has been discontinued and packages using the X
9153 Window System should now generally be installed in the same
9154 directories as any other package. Specifically, packages must
9155 not install files under the <file>/usr/X11R6/</file> directory
9156 and the <file>/usr/X11R6/</file> directory hierarchy should be
9157 regarded as obsolete.
9161 Include files previously installed under
9162 <file>/usr/X11R6/include/X11/</file> should be installed into
9163 <file>/usr/include/X11/</file>. For files previously
9164 installed into subdirectories of
9165 <file>/usr/X11R6/lib/X11/</file>, package maintainers should
9166 determine if subdirectories of <file>/usr/lib/</file> and
9167 <file>/usr/share/</file> can be used. If not, a subdirectory
9168 of <file>/usr/lib/X11/</file> should be used.
9172 Configuration files for window, display, or session managers
9173 or other applications that are tightly integrated with the X
9174 Window System may be placed in a subdirectory
9175 of <file>/etc/X11/</file> corresponding to the package name.
9176 Other X Window System applications should use
9177 the <file>/etc/</file> directory unless otherwise mandated by
9178 policy (such as for <ref id="appdefaults">).
9183 <heading>The OSF/Motif and OpenMotif libraries</heading>
9186 <em>Programs that require the non-DFSG-compliant OSF/Motif or
9187 OpenMotif libraries</em><footnote>
9188 OSF/Motif and OpenMotif are collectively referred to as
9189 "Motif" in this policy document.
9191 should be compiled against and tested with LessTif (a free
9192 re-implementation of Motif) instead. If the maintainer
9193 judges that the program or programs do not work
9194 sufficiently well with LessTif to be distributed and
9195 supported, but do so when compiled against Motif, then two
9196 versions of the package should be created; one linked
9197 statically against Motif and with <tt>-smotif</tt>
9198 appended to the package name, and one linked dynamically
9199 against Motif and with <tt>-dmotif</tt> appended to the
9204 Both Motif-linked versions are dependent
9205 upon non-DFSG-compliant software and thus cannot be
9206 uploaded to the <em>main</em> distribution; if the
9207 software is itself DFSG-compliant it may be uploaded to
9208 the <em>contrib</em> distribution. While known existing
9209 versions of Motif permit unlimited redistribution of
9210 binaries linked against the library (whether statically or
9211 dynamically), it is the package maintainer's
9212 responsibility to determine whether this is permitted by
9213 the license of the copy of Motif in their possession.
9219 <heading>Perl programs and modules</heading>
9222 Perl programs and modules should follow the current Perl policy.
9226 The Perl policy can be found in the <tt>perl-policy</tt>
9227 files in the <tt>debian-policy</tt> package.
9228 It is also available from the Debian web mirrors at
9229 <tt><url name="/doc/packaging-manuals/perl-policy/"
9230 id="http://www.debian.org/doc/packaging-manuals/perl-policy/"></tt>.
9235 <heading>Emacs lisp programs</heading>
9238 Please refer to the "Debian Emacs Policy" for details of how to
9239 package emacs lisp programs.
9243 The Emacs policy is available in
9244 <file>debian-emacs-policy.gz</file> of the
9245 <package>emacsen-common</package> package.
9246 It is also available from the Debian web mirrors at
9247 <tt><url name="/doc/packaging-manuals/debian-emacs-policy"
9248 id="http://www.debian.org/doc/packaging-manuals/debian-emacs-policy"></tt>.
9253 <heading>Games</heading>
9256 The permissions on <file>/var/games</file> are mode 755, owner
9257 <tt>root</tt> and group <tt>root</tt>.
9261 Each game decides on its own security policy.</p>
9264 Games which require protected, privileged access to
9265 high-score files, saved games, etc., may be made
9266 set-<em>group</em>-id (mode 2755) and owned by
9267 <tt>root:games</tt>, and use files and directories with
9268 appropriate permissions (770 <tt>root:games</tt>, for
9269 example). They must not be made
9270 set-<em>user</em>-id, as this causes security problems. (If
9271 an attacker can subvert any set-user-id game they can
9272 overwrite the executable of any other, causing other players
9273 of these games to run a Trojan horse program. With a
9274 set-group-id game the attacker only gets access to less
9275 important game data, and if they can get at the other
9276 players' accounts at all it will take considerably more
9280 Some packages, for example some fortune cookie programs, are
9281 configured by the upstream authors to install with their
9282 data files or other static information made unreadable so
9283 that they can only be accessed through set-id programs
9284 provided. You should not do this in a Debian package: anyone can
9285 download the <file>.deb</file> file and read the data from it,
9286 so there is no point making the files unreadable. Not
9287 making the files unreadable also means that you don't have
9288 to make so many programs set-id, which reduces the risk of a
9292 As described in the FHS, binaries of games should be
9293 installed in the directory <file>/usr/games</file>. This also
9294 applies to games that use the X Window System. Manual pages
9295 for games (X and non-X games) should be installed in
9296 <file>/usr/share/man/man6</file>.</p>
9302 <heading>Documentation</heading>
9305 <heading>Manual pages</heading>
9308 You should install manual pages in <prgn>nroff</prgn> source
9309 form, in appropriate places under <file>/usr/share/man</file>.
9310 You should only use sections 1 to 9 (see the FHS for more
9311 details). You must not install a pre-formatted "cat page".
9315 Each program, utility, and function should have an
9316 associated manual page included in the same package. It is
9317 suggested that all configuration files also have a manual
9318 page included as well. Manual pages for protocols and other
9319 auxiliary things are optional.
9323 If no manual page is available, this is considered as a bug
9324 and should be reported to the Debian Bug Tracking System (the
9325 maintainer of the package is allowed to write this bug report
9326 themselves, if they so desire). Do not close the bug report
9327 until a proper man page is available.<footnote>
9328 It is not very hard to write a man page. See the
9329 <url id="http://www.schweikhardt.net/man_page_howto.html"
9330 name="Man-Page-HOWTO">,
9331 <manref name="man" section="7">, the examples
9332 created by <prgn>debmake</prgn> or <prgn>dh_make</prgn>,
9333 the helper program <prgn>help2man</prgn>, or the
9334 directory <file>/usr/share/doc/man-db/examples</file>.
9339 You may forward a complaint about a missing man page to the
9340 upstream authors, and mark the bug as forwarded in the
9341 Debian bug tracking system. Even though the GNU Project do
9342 not in general consider the lack of a man page to be a bug,
9343 we do; if they tell you that they don't consider it a bug
9344 you should leave the bug in our bug tracking system open
9349 Manual pages should be installed compressed using <tt>gzip -9</tt>.
9353 If one man page needs to be accessible via several names it
9354 is better to use a symbolic link than the <file>.so</file>
9355 feature, but there is no need to fiddle with the relevant
9356 parts of the upstream source to change from <file>.so</file> to
9357 symlinks: don't do it unless it's easy. You should not
9358 create hard links in the manual page directories, nor put
9359 absolute filenames in <file>.so</file> directives. The filename
9360 in a <file>.so</file> in a man page should be relative to the
9361 base of the man page tree (usually
9362 <file>/usr/share/man</file>). If you do not create any links
9363 (whether symlinks, hard links, or <tt>.so</tt> directives)
9364 in the file system to the alternate names of the man page,
9365 then you should not rely on <prgn>man</prgn> finding your
9366 man page under those names based solely on the information in
9367 the man page's header.<footnote>
9368 Supporting this in <prgn>man</prgn> often requires
9369 unreasonable processing time to find a manual page or to
9370 report that none exists, and moves knowledge into man's
9371 database that would be better left in the file system.
9372 This support is therefore deprecated and will cease to
9373 be present in the future.
9378 Manual pages in locale-specific subdirectories of
9379 <file>/usr/share/man</file> should use either UTF-8 or the usual
9380 legacy encoding for that language (normally the one corresponding
9381 to the shortest relevant locale name in
9382 <file>/usr/share/i18n/SUPPORTED</file>). For example, pages under
9383 <file>/usr/share/man/fr</file> should use either UTF-8 or
9384 ISO-8859-1.<footnote>
9385 <prgn>man</prgn> will automatically detect whether UTF-8 is in
9386 use. In future, all manual pages will be required to use
9392 A country name (the <tt>DE</tt> in <tt>de_DE</tt>) should not be
9393 included in the subdirectory name unless it indicates a
9394 significant difference in the language, as this excludes
9395 speakers of the language in other countries.<footnote>
9396 At the time of writing, Chinese and Portuguese are the main
9397 languages with such differences, so <file>pt_BR</file>,
9398 <file>zh_CN</file>, and <file>zh_TW</file> are all allowed.
9403 If a localized version of a manual page is provided, it should
9404 either be up-to-date or it should be obvious to the reader that
9405 it is outdated and the original manual page should be used
9406 instead. This can be done either by a note at the beginning of
9407 the manual page or by showing the missing or changed portions in
9408 the original language instead of the target language.
9413 <heading>Info documents</heading>
9416 Info documents should be installed in <file>/usr/share/info</file>.
9417 They should be compressed with <tt>gzip -9</tt>.
9421 The <prgn>install-info</prgn> program maintains a directory of
9422 installed info documents in <file>/usr/share/info/dir</file> for
9423 the use of info readers.<footnote>
9424 It was previously necessary for packages installing info
9425 documents to run <prgn>install-info</prgn> from maintainer
9426 scripts. This is no longer necessary. The installation
9427 system now uses dpkg triggers.
9429 This file must not be included in packages. Packages containing
9430 info documents should depend on <tt>dpkg (>= 1.15.4) |
9431 install-info</tt> to ensure that the directory file is properly
9432 rebuilt during partial upgrades from Debian 5.0 (lenny) and
9437 Info documents should contain section and directory entry
9438 information in the document for the use
9439 of <prgn>install-info</prgn>. The section should be specified
9440 via a line starting with <tt>INFO-DIR-SECTION</tt> followed by a
9441 space and the section of this info page. The directory entry or
9442 entries should be included between
9443 a <tt>START-INFO-DIR-ENTRY</tt> line and
9444 an <tt>END-INFO-DIR-ENTRY</tt> line. For example:
9446 INFO-DIR-SECTION Individual utilities
9447 START-INFO-DIR-ENTRY
9448 * example: (example). An example info directory entry.
9451 To determine which section to use, you should look
9452 at <file>/usr/share/info/dir</file> on your system and choose
9453 the most relevant (or create a new section if none of the
9454 current sections are relevant).<footnote>
9455 Normally, info documents are generated from Texinfo source.
9456 To include this information in the generated info document, if
9457 it is absent, add commands like:
9459 @dircategory Individual utilities
9461 * example: (example). An example info directory entry.
9464 to the Texinfo source of the document and ensure that the info
9465 documents are rebuilt from source during the package build.
9471 <heading>Additional documentation</heading>
9474 Any additional documentation that comes with the package may
9475 be installed at the discretion of the package maintainer.
9476 Plain text documentation should be installed in the directory
9477 <file>/usr/share/doc/<var>package</var></file>, where
9478 <var>package</var> is the name of the package, and
9479 compressed with <tt>gzip -9</tt> unless it is small.
9483 If a package comes with large amounts of documentation which
9484 many users of the package will not require you should create
9485 a separate binary package to contain it, so that it does not
9486 take up disk space on the machines of users who do not need
9487 or want it installed.</p>
9490 It is often a good idea to put text information files
9491 (<file>README</file>s, changelogs, and so forth) that come with
9492 the source package in <file>/usr/share/doc/<var>package</var></file>
9493 in the binary package. However, you don't need to install
9494 the instructions for building and installing the package, of
9498 Packages must not require the existence of any files in
9499 <file>/usr/share/doc/</file> in order to function
9501 The system administrator should be able to
9502 delete files in <file>/usr/share/doc/</file> without causing
9503 any programs to break.
9505 Any files that are referenced by programs but are also
9506 useful as stand alone documentation should be installed under
9507 <file>/usr/share/<var>package</var>/</file> with symbolic links from
9508 <file>/usr/share/doc/<var>package</var></file>.
9512 <file>/usr/share/doc/<var>package</var></file> may be a symbolic
9513 link to another directory in <file>/usr/share/doc</file> only if
9514 the two packages both come from the same source and the
9515 first package Depends on the second.<footnote>
9517 Please note that this does not override the section on
9518 changelog files below, so the file
9519 <file>/usr/share/doc/<var>package</var>/changelog.Debian.gz</file>
9520 must refer to the changelog for the current version of
9521 <var>package</var> in question. In practice, this means
9522 that the sources of the target and the destination of the
9523 symlink must be the same (same source package and
9530 Former Debian releases placed all additional documentation
9531 in <file>/usr/doc/<var>package</var></file>. This has been
9532 changed to <file>/usr/share/doc/<var>package</var></file>,
9533 and packages must not put documentation in the directory
9534 <file>/usr/doc/<var>package</var></file>. <footnote>
9535 At this phase of the transition, we no longer require a
9536 symbolic link in <file>/usr/doc/</file>. At a later point,
9537 policy shall change to make the symbolic links a bug.
9543 <heading>Preferred documentation formats</heading>
9546 The unification of Debian documentation is being carried out
9550 If your package comes with extensive documentation in a
9551 markup format that can be converted to various other formats
9552 you should if possible ship HTML versions in a binary
9553 package, in the directory
9554 <file>/usr/share/doc/<var>appropriate-package</var></file> or
9555 its subdirectories.<footnote>
9556 The rationale: The important thing here is that HTML
9557 docs should be available in <em>some</em> package, not
9558 necessarily in the main binary package.
9563 Other formats such as PostScript may be provided at the
9564 package maintainer's discretion.
9568 <sect id="copyrightfile">
9569 <heading>Copyright information</heading>
9572 Every package must be accompanied by a verbatim copy of its
9573 copyright information and distribution license in the file
9574 <file>/usr/share/doc/<var>package</var>/copyright</file>. This
9575 file must neither be compressed nor be a symbolic link.
9579 In addition, the copyright file must say where the upstream
9580 sources (if any) were obtained. It should name the original
9581 authors of the package and the Debian maintainer(s) who were
9582 involved with its creation.
9586 Packages in the <em>contrib</em> or <em>non-free</em> archive
9587 areas should state in the copyright file that the package is not
9588 part of the Debian distribution and briefly explain why.
9592 A copy of the file which will be installed in
9593 <file>/usr/share/doc/<var>package</var>/copyright</file> should
9594 be in <file>debian/copyright</file> in the source package.
9598 <file>/usr/share/doc/<var>package</var></file> may be a symbolic
9599 link to another directory in <file>/usr/share/doc</file> only if
9600 the two packages both come from the same source and the
9601 first package Depends on the second. These rules are
9602 important because copyrights must be extractable by
9607 Packages distributed under the Apache license (version 2.0), the
9608 Artistic license, the GNU GPL (versions 1, 2, or 3), the GNU
9609 LGPL (versions 2, 2.1, or 3), and the GNU FDL (versions 1.2 or
9610 1.3) should refer to the corresponding files
9611 under <file>/usr/share/common-licenses</file>,<footnote>
9614 <file>/usr/share/common-licenses/Apache-2.0</file>,
9615 <file>/usr/share/common-licenses/Artistic</file>,
9616 <file>/usr/share/common-licenses/GPL-1</file>,
9617 <file>/usr/share/common-licenses/GPL-2</file>,
9618 <file>/usr/share/common-licenses/GPL-3</file>,
9619 <file>/usr/share/common-licenses/LGPL-2</file>,
9620 <file>/usr/share/common-licenses/LGPL-2.1</file>,
9621 <file>/usr/share/common-licenses/LGPL-3</file>,
9622 <file>/usr/share/common-licenses/GFDL-1.2</file>, and
9623 <file>/usr/share/common-licenses/GFDL-1.3</file>
9624 respectively. The University of California BSD license is
9625 also included in <package>base-files</package> as
9626 <file>/usr/share/common-licenses/BSD</file>, but given the
9627 brevity of this license, its specificity to code whose
9628 copyright is held by the Regents of the University of
9629 California, and the frequency of minor wording changes, its
9630 text should be included in the copyright file rather than
9631 referencing this file.
9633 </footnote> rather than quoting them in the copyright
9638 You should not use the copyright file as a general <file>README</file>
9639 file. If your package has such a file it should be
9640 installed in <file>/usr/share/doc/<var>package</var>/README</file> or
9641 <file>README.Debian</file> or some other appropriate place.</p>
9645 <heading>Examples</heading>
9648 Any examples (configurations, source files, whatever),
9649 should be installed in a directory
9650 <file>/usr/share/doc/<var>package</var>/examples</file>. These
9651 files should not be referenced by any program: they're there
9652 for the benefit of the system administrator and users as
9653 documentation only. Architecture-specific example files
9654 should be installed in a directory
9655 <file>/usr/lib/<var>package</var>/examples</file> with symbolic
9657 <file>/usr/share/doc/<var>package</var>/examples</file>, or the
9658 latter directory itself may be a symbolic link to the
9663 If the purpose of a package is to provide examples, then the
9664 example files may be installed into
9665 <file>/usr/share/doc/<var>package</var></file>.
9669 <sect id="changelogs">
9670 <heading>Changelog files</heading>
9673 Packages that are not Debian-native must contain a
9674 compressed copy of the <file>debian/changelog</file> file from
9675 the Debian source tree in
9676 <file>/usr/share/doc/<var>package</var></file> with the name
9677 <file>changelog.Debian.gz</file>.
9681 If an upstream changelog is available, it should be accessible as
9682 <file>/usr/share/doc/<var>package</var>/changelog.gz</file> in
9683 plain text. If the upstream changelog is distributed in
9684 HTML, it should be made available in that form as
9685 <file>/usr/share/doc/<var>package</var>/changelog.html.gz</file>
9686 and a plain text <file>changelog.gz</file> should be generated
9687 from it using, for example, <tt>lynx -dump -nolist</tt>. If
9688 the upstream changelog files do not already conform to this
9689 naming convention, then this may be achieved either by
9690 renaming the files, or by adding a symbolic link, at the
9691 maintainer's discretion.<footnote>
9692 Rationale: People should not have to look in places for
9693 upstream changelogs merely because they are given
9694 different names or are distributed in HTML format.
9699 All of these files should be installed compressed using
9700 <tt>gzip -9</tt>, as they will become large with time even
9701 if they start out small.
9705 If the package has only one changelog which is used both as
9706 the Debian changelog and the upstream one because there is
9707 no separate upstream maintainer then that changelog should
9708 usually be installed as
9709 <file>/usr/share/doc/<var>package</var>/changelog.gz</file>; if
9710 there is a separate upstream maintainer, but no upstream
9711 changelog, then the Debian changelog should still be called
9712 <file>changelog.Debian.gz</file>.
9716 For details about the format and contents of the Debian
9717 changelog file, please see <ref id="dpkgchangelog">.
9722 <appendix id="pkg-scope">
9723 <heading>Introduction and scope of these appendices</heading>
9726 These appendices are taken essentially verbatim from the
9727 now-deprecated Packaging Manual, version 3.2.1.0. They are
9728 the chapters which are likely to be of use to package
9729 maintainers and which have not already been included in the
9730 policy document itself. Most of these sections are very likely
9731 not relevant to policy; they should be treated as
9732 documentation for the packaging system. Please note that these
9733 appendices are included for convenience, and for historical
9734 reasons: they used to be part of policy package, and they have
9735 not yet been incorporated into dpkg documentation. However,
9736 they still have value, and hence they are presented here.
9740 They have not yet been checked to ensure that they are
9741 compatible with the contents of policy, and if there are any
9742 contradictions, the version in the main policy document takes
9743 precedence. The remaining chapters of the old Packaging
9744 Manual have also not been read in detail to ensure that there
9745 are not parts which have been left out. Both of these will be
9750 Certain parts of the Packaging manual were integrated into the
9751 Policy Manual proper, and removed from the appendices. Links
9752 have been placed from the old locations to the new ones.
9756 <prgn>dpkg</prgn> is a suite of programs for creating binary
9757 package files and installing and removing them on Unix
9759 <prgn>dpkg</prgn> is targeted primarily at Debian, but may
9760 work on or be ported to other systems.
9765 The binary packages are designed for the management of
9766 installed executable programs (usually compiled binaries) and
9767 their associated data, though source code examples and
9768 documentation are provided as part of some packages.</p>
9771 This manual describes the technical aspects of creating Debian
9772 binary packages (<file>.deb</file> files). It documents the
9773 behavior of the package management programs
9774 <prgn>dpkg</prgn>, <prgn>dselect</prgn> et al. and the way
9775 they interact with packages.</p>
9778 It also documents the interaction between
9779 <prgn>dselect</prgn>'s core and the access method scripts it
9780 uses to actually install the selected packages, and describes
9781 how to create a new access method.</p>
9784 This manual does not go into detail about the options and
9785 usage of the package building and installation tools. It
9786 should therefore be read in conjunction with those programs'
9791 The utility programs which are provided with <prgn>dpkg</prgn>
9792 for managing various system configuration and similar issues,
9793 such as <prgn>update-rc.d</prgn> and
9794 <prgn>install-info</prgn>, are not described in detail here -
9795 please see their man pages.
9799 It is assumed that the reader is reasonably familiar with the
9800 <prgn>dpkg</prgn> System Administrators' manual.
9801 Unfortunately this manual does not yet exist.
9805 The Debian version of the FSF's GNU hello program is provided
9806 as an example for people wishing to create Debian
9807 packages. The Debian <prgn>debmake</prgn> package is
9808 recommended as a very helpful tool in creating and maintaining
9809 Debian packages. However, while the tools and examples are
9810 helpful, they do not replace the need to read and follow the
9811 Policy and Programmer's Manual.</p>
9814 <appendix id="pkg-binarypkg">
9815 <heading>Binary packages (from old Packaging Manual)</heading>
9818 The binary package has two main sections. The first part
9819 consists of various control information files and scripts used
9820 by <prgn>dpkg</prgn> when installing and removing. See <ref
9821 id="pkg-controlarea">.
9825 The second part is an archive containing the files and
9826 directories to be installed.
9830 In the future binary packages may also contain other
9831 components, such as checksums and digital signatures. The
9832 format for the archive is described in full in the
9833 <file>deb(5)</file> man page.
9837 <sect id="pkg-bincreating"><heading>Creating package files -
9838 <prgn>dpkg-deb</prgn>
9842 All manipulation of binary package files is done by
9843 <prgn>dpkg-deb</prgn>; it's the only program that has
9844 knowledge of the format. (<prgn>dpkg-deb</prgn> may be
9845 invoked by calling <prgn>dpkg</prgn>, as <prgn>dpkg</prgn>
9846 will spot that the options requested are appropriate to
9847 <prgn>dpkg-deb</prgn> and invoke that instead with the same
9852 In order to create a binary package you must make a
9853 directory tree which contains all the files and directories
9854 you want to have in the file system data part of the package.
9855 In Debian-format source packages this directory is usually
9856 <file>debian/tmp</file>, relative to the top of the package's
9861 They should have the locations (relative to the root of the
9862 directory tree you're constructing) ownerships and
9863 permissions which you want them to have on the system when
9868 With current versions of <prgn>dpkg</prgn> the uid/username
9869 and gid/groupname mappings for the users and groups being
9870 used should be the same on the system where the package is
9871 built and the one where it is installed.
9875 You need to add one special directory to the root of the
9876 miniature file system tree you're creating:
9877 <prgn>DEBIAN</prgn>. It should contain the control
9878 information files, notably the binary package control file
9879 (see <ref id="pkg-controlfile">).
9883 The <prgn>DEBIAN</prgn> directory will not appear in the
9884 file system archive of the package, and so won't be installed
9885 by <prgn>dpkg</prgn> when the package is installed.
9889 When you've prepared the package, you should invoke:
9891 dpkg --build <var>directory</var>
9896 This will build the package in
9897 <file><var>directory</var>.deb</file>. (<prgn>dpkg</prgn> knows
9898 that <tt>--build</tt> is a <prgn>dpkg-deb</prgn> option, so
9899 it invokes <prgn>dpkg-deb</prgn> with the same arguments to
9904 See the man page <manref name="dpkg-deb" section="8"> for details of how
9905 to examine the contents of this newly-created file. You may find the
9906 output of following commands enlightening:
9908 dpkg-deb --info <var>filename</var>.deb
9909 dpkg-deb --contents <var>filename</var>.deb
9910 dpkg --contents <var>filename</var>.deb
9912 To view the copyright file for a package you could use this command:
9914 dpkg --fsys-tarfile <var>filename</var>.deb | tar xOf - --wildcards \*/copyright | pager
9919 <sect id="pkg-controlarea">
9920 <heading>Package control information files</heading>
9923 The control information portion of a binary package is a
9924 collection of files with names known to <prgn>dpkg</prgn>.
9925 It will treat the contents of these files specially - some
9926 of them contain information used by <prgn>dpkg</prgn> when
9927 installing or removing the package; others are scripts which
9928 the package maintainer wants <prgn>dpkg</prgn> to run.
9932 It is possible to put other files in the package control
9933 information file area, but this is not generally a good idea
9934 (though they will largely be ignored).
9938 Here is a brief list of the control information files supported
9939 by <prgn>dpkg</prgn> and a summary of what they're used for.
9944 <tag><tt>control</tt>
9947 This is the key description file used by
9948 <prgn>dpkg</prgn>. It specifies the package's name
9949 and version, gives its description for the user,
9950 states its relationships with other packages, and so
9951 forth. See <ref id="sourcecontrolfiles"> and
9952 <ref id="binarycontrolfiles">.
9956 It is usually generated automatically from information
9957 in the source package by the
9958 <prgn>dpkg-gencontrol</prgn> program, and with
9959 assistance from <prgn>dpkg-shlibdeps</prgn>.
9960 See <ref id="pkg-sourcetools">.
9964 <tag><tt>postinst</tt>, <tt>preinst</tt>, <tt>postrm</tt>,
9969 These are executable files (usually scripts) which
9970 <prgn>dpkg</prgn> runs during installation, upgrade
9971 and removal of packages. They allow the package to
9972 deal with matters which are particular to that package
9973 or require more complicated processing than that
9974 provided by <prgn>dpkg</prgn>. Details of when and
9975 how they are called are in <ref id="maintainerscripts">.
9979 It is very important to make these scripts idempotent.
9980 See <ref id="idempotency">.
9984 The maintainer scripts are not guaranteed to run with a
9985 controlling terminal and may not be able to interact with
9986 the user. See <ref id="controllingterminal">.
9990 <tag><tt>conffiles</tt>
9993 This file contains a list of configuration files which
9994 are to be handled automatically by <prgn>dpkg</prgn>
9995 (see <ref id="pkg-conffiles">). Note that not necessarily
9996 every configuration file should be listed here.
9999 <tag><tt>shlibs</tt>
10002 This file contains a list of the shared libraries
10003 supplied by the package, with dependency details for
10004 each. This is used by <prgn>dpkg-shlibdeps</prgn>
10005 when it determines what dependencies are required in a
10006 package control file. The <tt>shlibs</tt> file format
10007 is described on <ref id="shlibs">.
10012 <sect id="pkg-controlfile">
10013 <heading>The main control information file: <tt>control</tt></heading>
10016 The most important control information file used by
10017 <prgn>dpkg</prgn> when it installs a package is
10018 <tt>control</tt>. It contains all the package's "vital
10023 The binary package control files of packages built from
10024 Debian sources are made by a special tool,
10025 <prgn>dpkg-gencontrol</prgn>, which reads
10026 <file>debian/control</file> and <file>debian/changelog</file> to
10027 find the information it needs. See <ref id="pkg-sourcepkg"> for
10032 The fields in binary package control files are listed in
10033 <ref id="binarycontrolfiles">.
10037 A description of the syntax of control files and the purpose
10038 of the fields is available in <ref id="controlfields">.
10043 <heading>Time Stamps</heading>
10046 See <ref id="timestamps">.
10051 <appendix id="pkg-sourcepkg">
10052 <heading>Source packages (from old Packaging Manual) </heading>
10055 The Debian binary packages in the distribution are generated
10056 from Debian sources, which are in a special format to assist
10057 the easy and automatic building of binaries.
10060 <sect id="pkg-sourcetools">
10061 <heading>Tools for processing source packages</heading>
10064 Various tools are provided for manipulating source packages;
10065 they pack and unpack sources and help build of binary
10066 packages and help manage the distribution of new versions.
10070 They are introduced and typical uses described here; see
10071 <manref name="dpkg-source" section="1"> for full
10072 documentation about their arguments and operation.
10076 For examples of how to construct a Debian source package,
10077 and how to use those utilities that are used by Debian
10078 source packages, please see the <prgn>hello</prgn> example
10082 <sect1 id="pkg-dpkg-source">
10084 <prgn>dpkg-source</prgn> - packs and unpacks Debian source
10089 This program is frequently used by hand, and is also
10090 called from package-independent automated building scripts
10091 such as <prgn>dpkg-buildpackage</prgn>.
10095 To unpack a package it is typically invoked with
10097 dpkg-source -x <var>.../path/to/filename</var>.dsc
10102 with the <file><var>filename</var>.tar.gz</file> and
10103 <file><var>filename</var>.diff.gz</file> (if applicable) in
10104 the same directory. It unpacks into
10105 <file><var>package</var>-<var>version</var></file>, and if
10107 <file><var>package</var>-<var>version</var>.orig</file>, in
10108 the current directory.
10112 To create a packed source archive it is typically invoked:
10114 dpkg-source -b <var>package</var>-<var>version</var>
10119 This will create the <file>.dsc</file>, <file>.tar.gz</file> and
10120 <file>.diff.gz</file> (if appropriate) in the current
10121 directory. <prgn>dpkg-source</prgn> does not clean the
10122 source tree first - this must be done separately if it is
10127 See also <ref id="pkg-sourcearchives">.</p>
10131 <sect1 id="pkg-dpkg-buildpackage">
10133 <prgn>dpkg-buildpackage</prgn> - overall package-building
10138 <prgn>dpkg-buildpackage</prgn> is a script which invokes
10139 <prgn>dpkg-source</prgn>, the <file>debian/rules</file>
10140 targets <tt>clean</tt>, <tt>build</tt> and
10141 <tt>binary</tt>, <prgn>dpkg-genchanges</prgn> and
10142 <prgn>gpg</prgn> (or <prgn>pgp</prgn>) to build a signed
10143 source and binary package upload.
10147 It is usually invoked by hand from the top level of the
10148 built or unbuilt source directory. It may be invoked with
10149 no arguments; useful arguments include:
10150 <taglist compact="compact">
10151 <tag><tt>-uc</tt>, <tt>-us</tt></tag>
10154 Do not sign the <tt>.changes</tt> file or the
10155 source package <tt>.dsc</tt> file, respectively.</p>
10157 <tag><tt>-p<var>sign-command</var></tt></tag>
10160 Invoke <var>sign-command</var> instead of finding
10161 <tt>gpg</tt> or <tt>pgp</tt> on the <prgn>PATH</prgn>.
10162 <var>sign-command</var> must behave just like
10163 <prgn>gpg</prgn> or <tt>pgp</tt>.</p>
10165 <tag><tt>-r<var>root-command</var></tt></tag>
10168 When root privilege is required, invoke the command
10169 <var>root-command</var>. <var>root-command</var>
10170 should invoke its first argument as a command, from
10171 the <prgn>PATH</prgn> if necessary, and pass its
10172 second and subsequent arguments to the command it
10173 calls. If no <var>root-command</var> is supplied
10174 then <var>dpkg-buildpackage</var> will take no
10175 special action to gain root privilege, so that for
10176 most packages it will have to be invoked as root to
10179 <tag><tt>-b</tt>, <tt>-B</tt></tag>
10182 Two types of binary-only build and upload - see
10183 <manref name="dpkg-source" section="1">.
10190 <sect1 id="pkg-dpkg-gencontrol">
10192 <prgn>dpkg-gencontrol</prgn> - generates binary package
10197 This program is usually called from <file>debian/rules</file>
10198 (see <ref id="pkg-sourcetree">) in the top level of the source
10203 This is usually done just before the files and directories in the
10204 temporary directory tree where the package is being built have their
10205 permissions and ownerships set and the package is constructed using
10206 <prgn>dpkg-deb/</prgn>
10208 This is so that the control file which is produced has
10209 the right permissions
10214 <prgn>dpkg-gencontrol</prgn> must be called after all the
10215 files which are to go into the package have been placed in
10216 the temporary build directory, so that its calculation of
10217 the installed size of a package is correct.
10221 It is also necessary for <prgn>dpkg-gencontrol</prgn> to
10222 be run after <prgn>dpkg-shlibdeps</prgn> so that the
10223 variable substitutions created by
10224 <prgn>dpkg-shlibdeps</prgn> in <file>debian/substvars</file>
10229 For a package which generates only one binary package, and
10230 which builds it in <file>debian/tmp</file> relative to the top
10231 of the source package, it is usually sufficient to call
10232 <prgn>dpkg-gencontrol</prgn>.
10236 Sources which build several binaries will typically need
10239 dpkg-gencontrol -Pdebian/tmp-<var>pkg</var> -p<var>package</var>
10240 </example> The <tt>-P</tt> tells
10241 <prgn>dpkg-gencontrol</prgn> that the package is being
10242 built in a non-default directory, and the <tt>-p</tt>
10243 tells it which package's control file should be generated.
10247 <prgn>dpkg-gencontrol</prgn> also adds information to the
10248 list of files in <file>debian/files</file>, for the benefit of
10249 (for example) a future invocation of
10250 <prgn>dpkg-genchanges</prgn>.</p>
10253 <sect1 id="pkg-dpkg-shlibdeps">
10255 <prgn>dpkg-shlibdeps</prgn> - calculates shared library
10260 This program is usually called from <file>debian/rules</file>
10261 just before <prgn>dpkg-gencontrol</prgn> (see <ref
10262 id="pkg-sourcetree">), in the top level of the source tree.
10266 Its arguments are executables and shared libraries
10269 They may be specified either in the locations in the
10270 source tree where they are created or in the locations
10271 in the temporary build tree where they are installed
10272 prior to binary package creation.
10274 </footnote> for which shared library dependencies should
10275 be included in the binary package's control file.
10279 If some of the found shared libraries should only
10280 warrant a <tt>Recommends</tt> or <tt>Suggests</tt>, or if
10281 some warrant a <tt>Pre-Depends</tt>, this can be achieved
10282 by using the <tt>-d<var>dependency-field</var></tt> option
10283 before those executable(s). (Each <tt>-d</tt> option
10284 takes effect until the next <tt>-d</tt>.)
10288 <prgn>dpkg-shlibdeps</prgn> does not directly cause the
10289 output control file to be modified. Instead by default it
10290 adds to the <file>debian/substvars</file> file variable
10291 settings like <tt>shlibs:Depends</tt>. These variable
10292 settings must be referenced in dependency fields in the
10293 appropriate per-binary-package sections of the source
10298 For example, a package that generates an essential part
10299 which requires dependencies, and optional parts that
10300 which only require a recommendation, would separate those
10301 two sets of dependencies into two different fields.<footnote>
10302 At the time of writing, an example for this was the
10303 <package/xmms/ package, with Depends used for the xmms
10304 executable, Recommends for the plug-ins and Suggests for
10305 even more optional features provided by unzip.
10307 It can say in its <file>debian/rules</file>:
10309 dpkg-shlibdeps -dDepends <var>program anotherprogram ...</var> \
10310 -dRecommends <var>optionalpart anotheroptionalpart</var>
10312 and then in its main control file <file>debian/control</file>:
10315 Depends: ${shlibs:Depends}
10316 Recommends: ${shlibs:Recommends}
10322 Sources which produce several binary packages with
10323 different shared library dependency requirements can use
10324 the <tt>-p<var>varnameprefix</var></tt> option to override
10325 the default <tt>shlibs:</tt> prefix (one invocation of
10326 <prgn>dpkg-shlibdeps</prgn> per setting of this option).
10327 They can thus produce several sets of dependency
10328 variables, each of the form
10329 <tt><var>varnameprefix</var>:<var>dependencyfield</var></tt>,
10330 which can be referred to in the appropriate parts of the
10331 binary package control files.
10336 <sect1 id="pkg-dpkg-distaddfile">
10338 <prgn>dpkg-distaddfile</prgn> - adds a file to
10339 <file>debian/files</file>
10343 Some packages' uploads need to include files other than
10344 the source and binary package files.
10348 <prgn>dpkg-distaddfile</prgn> adds a file to the
10349 <file>debian/files</file> file so that it will be included in
10350 the <file>.changes</file> file when
10351 <prgn>dpkg-genchanges</prgn> is run.
10355 It is usually invoked from the <tt>binary</tt> target of
10356 <file>debian/rules</file>:
10358 dpkg-distaddfile <var>filename</var> <var>section</var> <var>priority</var>
10360 The <var>filename</var> is relative to the directory where
10361 <prgn>dpkg-genchanges</prgn> will expect to find it - this
10362 is usually the directory above the top level of the source
10363 tree. The <file>debian/rules</file> target should put the
10364 file there just before or just after calling
10365 <prgn>dpkg-distaddfile</prgn>.
10369 The <var>section</var> and <var>priority</var> are passed
10370 unchanged into the resulting <file>.changes</file> file.
10375 <sect1 id="pkg-dpkg-genchanges">
10377 <prgn>dpkg-genchanges</prgn> - generates a <file>.changes</file>
10378 upload control file
10382 This program is usually called by package-independent
10383 automatic building scripts such as
10384 <prgn>dpkg-buildpackage</prgn>, but it may also be called
10389 It is usually called in the top level of a built source
10390 tree, and when invoked with no arguments will print out a
10391 straightforward <file>.changes</file> file based on the
10392 information in the source package's changelog and control
10393 file and the binary and source packages which should have
10399 <sect1 id="pkg-dpkg-parsechangelog">
10401 <prgn>dpkg-parsechangelog</prgn> - produces parsed
10402 representation of a changelog
10406 This program is used internally by
10407 <prgn>dpkg-source</prgn> et al. It may also occasionally
10408 be useful in <file>debian/rules</file> and elsewhere. It
10409 parses a changelog, <file>debian/changelog</file> by default,
10410 and prints a control-file format representation of the
10411 information in it to standard output.
10415 <sect1 id="pkg-dpkg-architecture">
10417 <prgn>dpkg-architecture</prgn> - information about the build and
10422 This program can be used manually, but is also invoked by
10423 <tt>dpkg-buildpackage</tt> or <file>debian/rules</file> to set
10424 environment or make variables which specify the build and host
10425 architecture for the package building process.
10430 <sect id="pkg-sourcetree">
10431 <heading>The Debian package source tree</heading>
10434 The source archive scheme described later is intended to
10435 allow a Debian package source tree with some associated
10436 control information to be reproduced and transported easily.
10437 The Debian package source tree is a version of the original
10438 program with certain files added for the benefit of the
10439 packaging process, and with any other changes required
10440 made to the rest of the source code and installation
10445 The extra files created for Debian are in the subdirectory
10446 <file>debian</file> of the top level of the Debian package
10447 source tree. They are described below.
10450 <sect1 id="pkg-debianrules">
10451 <heading><file>debian/rules</file> - the main building script</heading>
10454 See <ref id="debianrules">.
10458 <sect1 id="pkg-srcsubstvars">
10459 <heading><file>debian/substvars</file> and variable substitutions</heading>
10462 See <ref id="substvars">.
10468 <heading><file>debian/files</file></heading>
10471 See <ref id="debianfiles">.
10475 <sect1><heading><file>debian/tmp</file>
10479 This is the canonical temporary location for the
10480 construction of binary packages by the <tt>binary</tt>
10481 target. The directory <file>tmp</file> serves as the root of
10482 the file system tree as it is being constructed (for
10483 example, by using the package's upstream makefiles install
10484 targets and redirecting the output there), and it also
10485 contains the <tt>DEBIAN</tt> subdirectory. See <ref
10486 id="pkg-bincreating">.
10490 If several binary packages are generated from the same
10491 source tree it is usual to use several
10492 <file>debian/tmp<var>something</var></file> directories, for
10493 example <file>tmp-a</file> or <file>tmp-doc</file>.
10497 Whatever <file>tmp</file> directories are created and used by
10498 <tt>binary</tt> must of course be removed by the
10499 <tt>clean</tt> target.</p></sect1>
10503 <sect id="pkg-sourcearchives"><heading>Source packages as archives
10507 As it exists on the FTP site, a Debian source package
10508 consists of three related files. You must have the right
10509 versions of all three to be able to use them.
10514 <tag>Debian source control file - <tt>.dsc</tt></tag>
10516 This file is a control file used by <prgn>dpkg-source</prgn>
10517 to extract a source package.
10518 See <ref id="debiansourcecontrolfiles">.
10522 Original source archive -
10524 <var>package</var>_<var>upstream-version</var>.orig.tar.gz
10530 This is a compressed (with <tt>gzip -9</tt>)
10531 <prgn>tar</prgn> file containing the source code from
10532 the upstream authors of the program.
10537 Debian package diff -
10539 <var>package</var>_<var>upstream_version-revision</var>.diff.gz
10545 This is a unified context diff (<tt>diff -u</tt>)
10546 giving the changes which are required to turn the
10547 original source into the Debian source. These changes
10548 may only include editing and creating plain files.
10549 The permissions of files, the targets of symbolic
10550 links and the characteristics of special files or
10551 pipes may not be changed and no files may be removed
10556 All the directories in the diff must exist, except the
10557 <file>debian</file> subdirectory of the top of the source
10558 tree, which will be created by
10559 <prgn>dpkg-source</prgn> if necessary when unpacking.
10563 The <prgn>dpkg-source</prgn> program will
10564 automatically make the <file>debian/rules</file> file
10565 executable (see below).</p></item>
10570 If there is no original source code - for example, if the
10571 package is specially prepared for Debian or the Debian
10572 maintainer is the same as the upstream maintainer - the
10573 format is slightly different: then there is no diff, and the
10575 <file><var>package</var>_<var>version</var>.tar.gz</file>,
10576 and preferably contains a directory named
10577 <file><var>package</var>-<var>version</var></file>.
10582 <heading>Unpacking a Debian source package without <prgn>dpkg-source</prgn></heading>
10585 <tt>dpkg-source -x</tt> is the recommended way to unpack a
10586 Debian source package. However, if it is not available it
10587 is possible to unpack a Debian source archive as follows:
10588 <enumlist compact="compact">
10591 Untar the tarfile, which will create a <file>.orig</file>
10595 <p>Rename the <file>.orig</file> directory to
10596 <file><var>package</var>-<var>version</var></file>.</p>
10600 Create the subdirectory <file>debian</file> at the top of
10601 the source tree.</p>
10603 <item><p>Apply the diff using <tt>patch -p0</tt>.</p>
10605 <item><p>Untar the tarfile again if you want a copy of the original
10606 source code alongside the Debian version.</p>
10611 It is not possible to generate a valid Debian source archive
10612 without using <prgn>dpkg-source</prgn>. In particular,
10613 attempting to use <prgn>diff</prgn> directly to generate the
10614 <file>.diff.gz</file> file will not work.
10618 <heading>Restrictions on objects in source packages</heading>
10621 The source package may not contain any hard links
10623 This is not currently detected when building source
10624 packages, but only when extracting
10628 Hard links may be permitted at some point in the
10629 future, but would require a fair amount of
10631 </footnote>, device special files, sockets or setuid or
10634 Setgid directories are allowed.
10639 The source packaging tools manage the changes between the
10640 original and Debian source using <prgn>diff</prgn> and
10641 <prgn>patch</prgn>. Turning the original source tree as
10642 included in the <file>.orig.tar.gz</file> into the Debian
10643 package source must not involve any changes which cannot be
10644 handled by these tools. Problematic changes which cause
10645 <prgn>dpkg-source</prgn> to halt with an error when
10646 building the source package are:
10647 <list compact="compact">
10648 <item><p>Adding or removing symbolic links, sockets or pipes.</p>
10650 <item><p>Changing the targets of symbolic links.</p>
10652 <item><p>Creating directories, other than <file>debian</file>.</p>
10654 <item><p>Changes to the contents of binary files.</p></item>
10655 </list> Changes which cause <prgn>dpkg-source</prgn> to
10656 print a warning but continue anyway are:
10657 <list compact="compact">
10660 Removing files, directories or symlinks.
10662 Renaming a file is not treated specially - it is
10663 seen as the removal of the old file (which
10664 generates a warning, but is otherwise ignored),
10665 and the creation of the new one.
10671 Changed text files which are missing the usual final
10672 newline (either in the original or the modified
10677 Changes which are not represented, but which are not detected by
10678 <prgn>dpkg-source</prgn>, are:
10679 <list compact="compact">
10680 <item><p>Changing the permissions of files (other than
10681 <file>debian/rules</file>) and directories.</p></item>
10686 The <file>debian</file> directory and <file>debian/rules</file>
10687 are handled specially by <prgn>dpkg-source</prgn> - before
10688 applying the changes it will create the <file>debian</file>
10689 directory, and afterwards it will make
10690 <file>debian/rules</file> world-executable.
10696 <appendix id="pkg-controlfields">
10697 <heading>Control files and their fields (from old Packaging Manual)</heading>
10700 Many of the tools in the <prgn>dpkg</prgn> suite manipulate
10701 data in a common format, known as control files. Binary and
10702 source packages have control data as do the <file>.changes</file>
10703 files which control the installation of uploaded files, and
10704 <prgn>dpkg</prgn>'s internal databases are in a similar
10709 <heading>Syntax of control files</heading>
10712 See <ref id="controlsyntax">.
10716 It is important to note that there are several fields which
10717 are optional as far as <prgn>dpkg</prgn> and the related
10718 tools are concerned, but which must appear in every Debian
10719 package, or whose omission may cause problems.
10724 <heading>List of fields</heading>
10727 See <ref id="controlfieldslist">.
10731 This section now contains only the fields that didn't belong
10732 to the Policy manual.
10735 <sect1 id="pkg-f-Filename">
10736 <heading><tt>Filename</tt> and <tt>MSDOS-Filename</tt></heading>
10739 These fields in <tt>Packages</tt> files give the
10740 filename(s) of (the parts of) a package in the
10741 distribution directories, relative to the root of the
10742 Debian hierarchy. If the package has been split into
10743 several parts the parts are all listed in order, separated
10748 <sect1 id="pkg-f-Size">
10749 <heading><tt>Size</tt> and <tt>MD5sum</tt></heading>
10752 These fields in <file>Packages</file> files give the size (in
10753 bytes, expressed in decimal) and MD5 checksum of the
10754 file(s) which make(s) up a binary package in the
10755 distribution. If the package is split into several parts
10756 the values for the parts are listed in order, separated by
10761 <sect1 id="pkg-f-Status">
10762 <heading><tt>Status</tt></heading>
10765 This field in <prgn>dpkg</prgn>'s status file records
10766 whether the user wants a package installed, removed or
10767 left alone, whether it is broken (requiring
10768 re-installation) or not and what its current state on the
10769 system is. Each of these pieces of information is a
10774 <sect1 id="pkg-f-Config-Version">
10775 <heading><tt>Config-Version</tt></heading>
10778 If a package is not installed or not configured, this
10779 field in <prgn>dpkg</prgn>'s status file records the last
10780 version of the package which was successfully
10785 <sect1 id="pkg-f-Conffiles">
10786 <heading><tt>Conffiles</tt></heading>
10789 This field in <prgn>dpkg</prgn>'s status file contains
10790 information about the automatically-managed configuration
10791 files held by a package. This field should <em>not</em>
10792 appear anywhere in a package!
10797 <heading>Obsolete fields</heading>
10800 These are still recognized by <prgn>dpkg</prgn> but should
10801 not appear anywhere any more.
10803 <taglist compact="compact">
10805 <tag><tt>Revision</tt></tag>
10806 <tag><tt>Package-Revision</tt></tag>
10807 <tag><tt>Package_Revision</tt></tag>
10809 The Debian revision part of the package version was
10810 at one point in a separate control field. This
10811 field went through several names.
10814 <tag><tt>Recommended</tt></tag>
10815 <item>Old name for <tt>Recommends</tt>.</item>
10817 <tag><tt>Optional</tt></tag>
10818 <item>Old name for <tt>Suggests</tt>.</item>
10820 <tag><tt>Class</tt></tag>
10821 <item>Old name for <tt>Priority</tt>.</item>
10830 <appendix id="pkg-conffiles">
10831 <heading>Configuration file handling (from old Packaging Manual)</heading>
10834 <prgn>dpkg</prgn> can do a certain amount of automatic
10835 handling of package configuration files.
10839 Whether this mechanism is appropriate depends on a number of
10840 factors, but basically there are two approaches to any
10841 particular configuration file.
10845 The easy method is to ship a best-effort configuration in the
10846 package, and use <prgn>dpkg</prgn>'s conffile mechanism to
10847 handle updates. If the user is unlikely to want to edit the
10848 file, but you need them to be able to without losing their
10849 changes, and a new package with a changed version of the file
10850 is only released infrequently, this is a good approach.
10854 The hard method is to build the configuration file from
10855 scratch in the <prgn>postinst</prgn> script, and to take the
10856 responsibility for fixing any mistakes made in earlier
10857 versions of the package automatically. This will be
10858 appropriate if the file is likely to need to be different on
10862 <sect><heading>Automatic handling of configuration files by
10867 A package may contain a control information file called
10868 <tt>conffiles</tt>. This file should be a list of filenames
10869 of configuration files needing automatic handling, separated
10870 by newlines. The filenames should be absolute pathnames,
10871 and the files referred to should actually exist in the
10876 When a package is upgraded <prgn>dpkg</prgn> will process
10877 the configuration files during the configuration stage,
10878 shortly before it runs the package's <prgn>postinst</prgn>
10883 For each file it checks to see whether the version of the
10884 file included in the package is the same as the one that was
10885 included in the last version of the package (the one that is
10886 being upgraded from); it also compares the version currently
10887 installed on the system with the one shipped with the last
10892 If neither the user nor the package maintainer has changed
10893 the file, it is left alone. If one or the other has changed
10894 their version, then the changed version is preferred - i.e.,
10895 if the user edits their file, but the package maintainer
10896 doesn't ship a different version, the user's changes will
10897 stay, silently, but if the maintainer ships a new version
10898 and the user hasn't edited it the new version will be
10899 installed (with an informative message). If both have
10900 changed their version the user is prompted about the problem
10901 and must resolve the differences themselves.
10905 The comparisons are done by calculating the MD5 message
10906 digests of the files, and storing the MD5 of the file as it
10907 was included in the most recent version of the package.
10911 When a package is installed for the first time
10912 <prgn>dpkg</prgn> will install the file that comes with it,
10913 unless that would mean overwriting a file already on the
10918 However, note that <prgn>dpkg</prgn> will <em>not</em>
10919 replace a conffile that was removed by the user (or by a
10920 script). This is necessary because with some programs a
10921 missing file produces an effect hard or impossible to
10922 achieve in another way, so that a missing file needs to be
10923 kept that way if the user did it.
10927 Note that a package should <em>not</em> modify a
10928 <prgn>dpkg</prgn>-handled conffile in its maintainer
10929 scripts. Doing this will lead to <prgn>dpkg</prgn> giving
10930 the user confusing and possibly dangerous options for
10931 conffile update when the package is upgraded.</p>
10934 <sect><heading>Fully-featured maintainer script configuration
10939 For files which contain site-specific information such as
10940 the hostname and networking details and so forth, it is
10941 better to create the file in the package's
10942 <prgn>postinst</prgn> script.
10946 This will typically involve examining the state of the rest
10947 of the system to determine values and other information, and
10948 may involve prompting the user for some information which
10949 can't be obtained some other way.
10953 When using this method there are a couple of important
10954 issues which should be considered:
10958 If you discover a bug in the program which generates the
10959 configuration file, or if the format of the file changes
10960 from one version to the next, you will have to arrange for
10961 the postinst script to do something sensible - usually this
10962 will mean editing the installed configuration file to remove
10963 the problem or change the syntax. You will have to do this
10964 very carefully, since the user may have changed the file,
10965 perhaps to fix the very problem that your script is trying
10966 to deal with - you will have to detect these situations and
10967 deal with them correctly.
10971 If you do go down this route it's probably a good idea to
10972 make the program that generates the configuration file(s) a
10973 separate program in <file>/usr/sbin</file>, by convention called
10974 <file><var>package</var>config</file> and then run that if
10975 appropriate from the post-installation script. The
10976 <tt><var>package</var>config</tt> program should not
10977 unquestioningly overwrite an existing configuration - if its
10978 mode of operation is geared towards setting up a package for
10979 the first time (rather than any arbitrary reconfiguration
10980 later) you should have it check whether the configuration
10981 already exists, and require a <tt>--force</tt> flag to
10982 overwrite it.</p></sect>
10985 <appendix id="pkg-alternatives"><heading>Alternative versions of
10986 an interface - <prgn>update-alternatives</prgn> (from old
10991 When several packages all provide different versions of the
10992 same program or file it is useful to have the system select a
10993 default, but to allow the system administrator to change it
10994 and have their decisions respected.
10998 For example, there are several versions of the <prgn>vi</prgn>
10999 editor, and there is no reason to prevent all of them from
11000 being installed at once, each under their own name
11001 (<prgn>nvi</prgn>, <prgn>vim</prgn> or whatever).
11002 Nevertheless it is desirable to have the name <tt>vi</tt>
11003 refer to something, at least by default.
11007 If all the packages involved cooperate, this can be done with
11008 <prgn>update-alternatives</prgn>.
11012 Each package provides its own version under its own name, and
11013 calls <prgn>update-alternatives</prgn> in its postinst to
11014 register its version (and again in its prerm to deregister
11019 See the man page <manref name="update-alternatives"
11020 section="8"> for details.
11024 If <prgn>update-alternatives</prgn> does not seem appropriate
11025 you may wish to consider using diversions instead.</p>
11028 <appendix id="pkg-diversions"><heading>Diversions - overriding a
11029 package's version of a file (from old Packaging Manual)
11033 It is possible to have <prgn>dpkg</prgn> not overwrite a file
11034 when it reinstalls the package it belongs to, and to have it
11035 put the file from the package somewhere else instead.
11039 This can be used locally to override a package's version of a
11040 file, or by one package to override another's version (or
11041 provide a wrapper for it).
11045 Before deciding to use a diversion, read <ref
11046 id="pkg-alternatives"> to see if you really want a diversion
11047 rather than several alternative versions of a program.
11051 There is a diversion list, which is read by <prgn>dpkg</prgn>,
11052 and updated by a special program <prgn>dpkg-divert</prgn>.
11053 Please see <manref name="dpkg-divert" section="8"> for full
11054 details of its operation.
11058 When a package wishes to divert a file from another, it should
11059 call <prgn>dpkg-divert</prgn> in its preinst to add the
11060 diversion and rename the existing file. For example,
11061 supposing that a <prgn>smailwrapper</prgn> package wishes to
11062 install a wrapper around <file>/usr/sbin/smail</file>:
11064 dpkg-divert --package smailwrapper --add --rename \
11065 --divert /usr/sbin/smail.real /usr/sbin/smail
11066 </example> The <tt>--package smailwrapper</tt> ensures that
11067 <prgn>smailwrapper</prgn>'s copy of <file>/usr/sbin/smail</file>
11068 can bypass the diversion and get installed as the true version.
11069 It's safe to add the diversion unconditionally on upgrades since
11070 it will be left unchanged if it already exists, but
11071 <prgn>dpkg-divert</prgn> will display a message. To suppress that
11072 message, make the command conditional on the version from which
11073 the package is being upgraded:
11075 if [ upgrade != "$1" ] || dpkg --compare-versions "$2" lt 1.0-2; then
11076 dpkg-divert --package smailwrapper --add --rename \
11077 --divert /usr/sbin/smail.real /usr/sbin/smail
11079 </example> where <tt>1.0-2</tt> is the version at which the
11080 diversion was first added to the package. Running the command
11081 during abort-upgrade is pointless but harmless.
11085 The postrm has to do the reverse:
11087 if [ remove = "$1" -o abort-install = "$1" -o disappear = "$1" ]; then
11088 dpkg-divert --package smailwrapper --remove --rename \
11089 --divert /usr/sbin/smail.real /usr/sbin/smail
11091 </example> If the diversion was added at a particular version, the
11092 postrm should also handle the failure case of upgrading from an
11093 older version (unless the older version is so old that direct
11094 upgrades are no longer supported):
11096 if [ abort-upgrade = "$1" ] && dpkg --compare-versions "$2" lt 1.0-2; then
11097 dpkg-divert --package smailwrapper --remove --rename \
11098 --divert /usr/sbin/smail.real /usr/sbin/smail
11100 </example> where <tt>1.02-2</tt> is the version at which the
11101 diversion was first added to the package. The postrm should not
11102 remove the diversion on upgrades both because there's no reason to
11103 remove the diversion only to immediately re-add it and since the
11104 postrm of the old package is run after unpacking so the removal of
11105 the diversion will fail.
11109 Do not attempt to divert a file which is vitally important for
11110 the system's operation - when using <prgn>dpkg-divert</prgn>
11111 there is a time, after it has been diverted but before
11112 <prgn>dpkg</prgn> has installed the new version, when the file
11113 does not exist.</p>
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