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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 GNU/Linux 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 GNU/Linux
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 GNU/Linux 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 GNU/Linux 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 GNU/Linux
356 Packages in the other archive areas (<tt>contrib</tt>,
357 <tt>non-free</tt>) are not considered to be part of the Debian
358 distribution, although we support their use and provide
359 infrastructure for them (such as our bug-tracking system and
360 mailing lists). This Debian Policy Manual applies to these
365 <heading>The Debian Free Software Guidelines</heading>
367 The Debian Free Software Guidelines (DFSG) form our
368 definition of "free software". These are:
370 <tag>1. Free Redistribution
373 The license of a Debian component may not restrict any
374 party from selling or giving away the software as a
375 component of an aggregate software distribution
376 containing programs from several different
377 sources. The license may not require a royalty or
378 other fee for such sale.
383 The program must include source code, and must allow
384 distribution in source code as well as compiled form.
386 <tag>3. Derived Works
389 The license must allow modifications and derived
390 works, and must allow them to be distributed under the
391 same terms as the license of the original software.
393 <tag>4. Integrity of The Author's Source Code
396 The license may restrict source-code from being
397 distributed in modified form <em>only</em> if the
398 license allows the distribution of "patch files"
399 with the source code for the purpose of modifying the
400 program at build time. The license must explicitly
401 permit distribution of software built from modified
402 source code. The license may require derived works to
403 carry a different name or version number from the
404 original software. (This is a compromise. The Debian
405 Project encourages all authors to not restrict any
406 files, source or binary, from being modified.)
408 <tag>5. No Discrimination Against Persons or Groups
411 The license must not discriminate against any person
414 <tag>6. No Discrimination Against Fields of Endeavor
417 The license must not restrict anyone from making use
418 of the program in a specific field of endeavor. For
419 example, it may not restrict the program from being
420 used in a business, or from being used for genetic
423 <tag>7. Distribution of License
426 The rights attached to the program must apply to all
427 to whom the program is redistributed without the need
428 for execution of an additional license by those
431 <tag>8. License Must Not Be Specific to Debian
434 The rights attached to the program must not depend on
435 the program's being part of a Debian system. If the
436 program is extracted from Debian and used or
437 distributed without Debian but otherwise within the
438 terms of the program's license, all parties to whom
439 the program is redistributed must have the same
440 rights as those that are granted in conjunction with
443 <tag>9. License Must Not Contaminate Other Software
446 The license must not place restrictions on other
447 software that is distributed along with the licensed
448 software. For example, the license must not insist
449 that all other programs distributed on the same medium
450 must be free software.
452 <tag>10. Example Licenses
455 The "GPL," "BSD," and "Artistic" licenses are examples of
456 licenses that we consider <em>free</em>.
463 <heading>Archive areas</heading>
466 <heading>The main archive area</heading>
469 Every package in <em>main</em> must comply with the DFSG
470 (Debian Free Software Guidelines).
474 In addition, the packages in <em>main</em>
475 <list compact="compact">
477 must not require a package outside of <em>main</em>
478 for compilation or execution (thus, the package must
479 not declare a "Depends", "Recommends", or
480 "Build-Depends" relationship on a non-<em>main</em>
484 must not be so buggy that we refuse to support them,
488 must meet all policy requirements presented in this
497 <heading>The contrib archive area</heading>
500 Every package in <em>contrib</em> must comply with the DFSG.
504 In addition, the packages in <em>contrib</em>
505 <list compact="compact">
507 must not be so buggy that we refuse to support them,
511 must meet all policy requirements presented in this
519 Examples of packages which would be included in
520 <em>contrib</em> are:
521 <list compact="compact">
523 free packages which require <em>contrib</em>,
524 <em>non-free</em> packages or packages which are not
525 in our archive at all for compilation or execution,
529 wrapper packages or other sorts of free accessories for
536 <sect1 id="non-free">
537 <heading>The non-free archive area</heading>
540 Packages must be placed in <em>non-free</em> if they are
541 not compliant with the DFSG or are encumbered by patents
542 or other legal issues that make their distribution
547 In addition, the packages in <em>non-free</em>
548 <list compact="compact">
550 must not be so buggy that we refuse to support them,
554 must meet all policy requirements presented in this
555 manual that it is possible for them to meet.
557 It is possible that there are policy
558 requirements which the package is unable to
559 meet, for example, if the source is
560 unavailable. These situations will need to be
561 handled on a case-by-case basis.
570 <sect id="pkgcopyright">
571 <heading>Copyright considerations</heading>
574 Every package must be accompanied by a verbatim copy of its
575 copyright information and distribution license in the file
576 <file>/usr/share/doc/<var>package</var>/copyright</file>
577 (see <ref id="copyrightfile"> for further details).
581 We reserve the right to restrict files from being included
582 anywhere in our archives if
583 <list compact="compact">
585 their use or distribution would break a law,
588 there is an ethical conflict in their distribution or
592 we would have to sign a license for them, or
595 their distribution would conflict with other project
602 Programs whose authors encourage the user to make
603 donations are fine for the main distribution, provided
604 that the authors do not claim that not donating is
605 immoral, unethical, illegal or something similar; in such
606 a case they must go in <em>non-free</em>.
610 Packages whose copyright permission notices (or patent
611 problems) do not even allow redistribution of binaries
612 only, and where no special permission has been obtained,
613 must not be placed on the Debian FTP site and its mirrors
618 Note that under international copyright law (this applies
619 in the United States, too), <em>no</em> distribution or
620 modification of a work is allowed without an explicit
621 notice saying so. Therefore a program without a copyright
622 notice <em>is</em> copyrighted and you may not do anything
623 to it without risking being sued! Likewise if a program
624 has a copyright notice but no statement saying what is
625 permitted then nothing is permitted.
629 Many authors are unaware of the problems that restrictive
630 copyrights (or lack of copyright notices) can cause for
631 the users of their supposedly-free software. It is often
632 worthwhile contacting such authors diplomatically to ask
633 them to modify their license terms. However, this can be a
634 politically difficult thing to do and you should ask for
635 advice on the <tt>debian-legal</tt> mailing list first, as
640 When in doubt about a copyright, send mail to
641 <email>debian-legal@lists.debian.org</email>. Be prepared
642 to provide us with the copyright statement. Software
643 covered by the GPL, public domain software and BSD-like
644 copyrights are safe; be wary of the phrases "commercial
645 use prohibited" and "distribution restricted".
649 <sect id="subsections">
650 <heading>Sections</heading>
653 The packages in the archive areas <em>main</em>,
654 <em>contrib</em> and <em>non-free</em> are grouped further into
655 <em>sections</em> to simplify handling.
659 The archive area and section for each package should be
660 specified in the package's <tt>Section</tt> control record (see
661 <ref id="f-Section">). However, the maintainer of the Debian
662 archive may override this selection to ensure the consistency of
663 the Debian distribution. The <tt>Section</tt> field should be
665 <list compact="compact">
667 <em>section</em> if the package is in the
668 <em>main</em> archive area,
671 <em>area/section</em> if the package is in
672 the <em>contrib</em> or <em>non-free</em>
679 The Debian archive maintainers provide the authoritative
680 list of sections. At present, they are:
681 <em>admin</em>, <em>cli-mono</em>, <em>comm</em>, <em>database</em>,
682 <em>devel</em>, <em>debug</em>, <em>doc</em>, <em>editors</em>,
683 <em>electronics</em>, <em>embedded</em>, <em>fonts</em>,
684 <em>games</em>, <em>gnome</em>, <em>graphics</em>, <em>gnu-r</em>,
685 <em>gnustep</em>, <em>hamradio</em>, <em>haskell</em>,
686 <em>httpd</em>, <em>interpreters</em>, <em>java</em>, <em>kde</em>,
687 <em>kernel</em>, <em>libs</em>, <em>libdevel</em>, <em>lisp</em>,
688 <em>localization</em>, <em>mail</em>, <em>math</em>, <em>misc</em>,
689 <em>net</em>, <em>news</em>, <em>ocaml</em>, <em>oldlibs</em>,
690 <em>otherosfs</em>, <em>perl</em>, <em>php</em>, <em>python</em>,
691 <em>ruby</em>, <em>science</em>, <em>shells</em>, <em>sound</em>,
692 <em>tex</em>, <em>text</em>, <em>utils</em>, <em>vcs</em>,
693 <em>video</em>, <em>web</em>, <em>x11</em>, <em>xfce</em>,
694 <em>zope</em>. The additional section <em>debian-installer</em>
695 contains special packages used by the installer and is not used
696 for normal Debian packages.
700 For more information about the sections and their definitions,
701 see the <url id="http://packages.debian.org/unstable/"
702 name="list of sections in unstable">.
706 <sect id="priorities">
707 <heading>Priorities</heading>
710 Each package should have a <em>priority</em> value, which is
711 included in the package's <em>control record</em>
712 (see <ref id="f-Priority">).
713 This information is used by the Debian package management tools to
714 separate high-priority packages from less-important packages.
718 The following <em>priority levels</em> are recognized by the
719 Debian package management tools.
721 <tag><tt>required</tt></tag>
723 Packages which are necessary for the proper
724 functioning of the system (usually, this means that
725 dpkg functionality depends on these packages).
726 Removing a <tt>required</tt> package may cause your
727 system to become totally broken and you may not even
728 be able to use <prgn>dpkg</prgn> to put things back,
729 so only do so if you know what you are doing. Systems
730 with only the <tt>required</tt> packages are probably
731 unusable, but they do have enough functionality to
732 allow the sysadmin to boot and install more software.
734 <tag><tt>important</tt></tag>
736 Important programs, including those which one would
737 expect to find on any Unix-like system. If the
738 expectation is that an experienced Unix person who
739 found it missing would say "What on earth is going on,
740 where is <prgn>foo</prgn>?", it must be an
741 <tt>important</tt> package.<footnote>
742 This is an important criterion because we are
743 trying to produce, amongst other things, a free
746 Other packages without which the system will not run
747 well or be usable must also have priority
748 <tt>important</tt>. This does
749 <em>not</em> include Emacs, the X Window System, TeX
750 or any other large applications. The
751 <tt>important</tt> packages are just a bare minimum of
752 commonly-expected and necessary tools.
754 <tag><tt>standard</tt></tag>
756 These packages provide a reasonably small but not too
757 limited character-mode system. This is what will be
758 installed by default if the user doesn't select anything
759 else. It doesn't include many large applications.
761 <tag><tt>optional</tt></tag>
763 (In a sense everything that isn't required is
764 optional, but that's not what is meant here.) This is
765 all the software that you might reasonably want to
766 install if you didn't know what it was and don't have
767 specialized requirements. This is a much larger system
768 and includes the X Window System, a full TeX
769 distribution, and many applications. Note that
770 optional packages should not conflict with each other.
772 <tag><tt>extra</tt></tag>
774 This contains all packages that conflict with others
775 with required, important, standard or optional
776 priorities, or are only likely to be useful if you
777 already know what they are or have specialized
778 requirements (such as packages containing only detached
785 Packages must not depend on packages with lower priority
786 values (excluding build-time dependencies). In order to
787 ensure this, the priorities of one or more packages may need
796 <heading>Binary packages</heading>
799 The Debian GNU/Linux distribution is based on the Debian
800 package management system, called <prgn>dpkg</prgn>. Thus,
801 all packages in the Debian distribution must be provided
802 in the <tt>.deb</tt> file format.
806 A <tt>.deb</tt> package contains two sets of files: a set of files
807 to install on the system when the package is installed, and a set
808 of files that provide additional metadata about the package or
809 which are executed when the package is installed or removed. This
810 second set of files is called <em>control information files</em>.
811 Among those files are the package maintainer scripts
812 and <file>control</file>, the <qref id="binarycontrolfiles">binary
813 package control file</qref> that contains the control fields for
814 the package. Other control information files
815 include <qref id="sharedlibs-shlibdeps">the <file>shlibs</file>
816 file</qref> used to store shared library dependency information
817 and the <file>conffiles</file> file that lists the package's
818 configuration files (described in <ref id="config-files">).
822 There is unfortunately a collision of terminology here between
823 control information files and files in the Debian control file
824 format. Throughout this document, a <em>control file</em> refers
825 to a file in the Debian control file format. These files are
826 documented in <ref id="controlfields">. Only files referred to
827 specifically as <em>control information files</em> are the files
828 included in the control information file member of
829 the <file>.deb</file> file format used by binary packages. Most
830 control information files are not in the Debian control file
835 <heading>The package name</heading>
838 Every package must have a name that's unique within the Debian
843 The package name is included in the control field
844 <tt>Package</tt>, the format of which is described
845 in <ref id="f-Package">.
846 The package name is also included as a part of the file name
847 of the <tt>.deb</tt> file.
852 <heading>The version of a package</heading>
855 Every package has a version number recorded in its
856 <tt>Version</tt> control file field, described in
857 <ref id="f-Version">.
861 The package management system imposes an ordering on version
862 numbers, so that it can tell whether packages are being up- or
863 downgraded and so that package system front end applications
864 can tell whether a package it finds available is newer than
865 the one installed on the system. The version number format
866 has the most significant parts (as far as comparison is
867 concerned) at the beginning.
871 If an upstream package has problematic version numbers they
872 should be converted to a sane form for use in the
873 <tt>Version</tt> field.
877 <heading>Version numbers based on dates</heading>
880 In general, Debian packages should use the same version
881 numbers as the upstream sources. However, upstream version
882 numbers based on some date formats (sometimes used for
883 development or "snapshot" releases) will not be ordered
884 correctly by the package management software. For
885 example, <prgn>dpkg</prgn> will consider "96May01" to be
886 greater than "96Dec24".
890 To prevent having to use epochs for every new upstream
891 version, the date-based portion of any upstream version number
892 should be given in a way that sorts correctly: four-digit year
893 first, followed by a two-digit numeric month, followed by a
894 two-digit numeric date, possibly with punctuation between the
899 Native Debian packages (i.e., packages which have been written
900 especially for Debian) whose version numbers include dates
901 should also follow these rules. If punctuation is desired
902 between the date components, remember that hyphen (<tt>-</tt>)
903 cannot be used in native package versions. Period
904 (<tt>.</tt>) is normally a good choice.
910 <sect id="maintainer">
911 <heading>The maintainer of a package</heading>
914 Every package must have a maintainer, except for orphaned
915 packages as described below. The maintainer may be one person
916 or a group of people reachable from a common email address, such
917 as a mailing list. The maintainer is responsible for
918 maintaining the Debian packaging files, evaluating and
919 responding appropriately to reported bugs, uploading new
920 versions of the package (either directly or through a sponsor),
921 ensuring that the package is placed in the appropriate archive
922 area and included in Debian releases as appropriate for the
923 stability and utility of the package, and requesting removal of
924 the package from the Debian distribution if it is no longer
925 useful or maintainable.
929 The maintainer must be specified in the <tt>Maintainer</tt>
930 control field with their correct name and a working email
931 address. The email address given in the <tt>Maintainer</tt>
932 control field must accept mail from those role accounts in
933 Debian used to send automated mails regarding the package. This
934 includes non-spam mail from the bug-tracking system, all mail
935 from the Debian archive maintenance software, and other role
936 accounts or automated processes that are commonly agreed on by
937 the project.<footnote>
938 A sample implementation of such a whitelist written for the
939 Mailman mailing list management software is used for mailing
940 lists hosted by alioth.debian.org.
942 If one person or team maintains several packages, they should
943 use the same form of their name and email address in
944 the <tt>Maintainer</tt> fields of those packages.
948 The format of the <tt>Maintainer</tt> control field is
949 described in <ref id="f-Maintainer">.
953 If the maintainer of the package is a team of people with a
954 shared email address, the <tt>Uploaders</tt> control field must
955 be present and must contain at least one human with their
956 personal email address. See <ref id="f-Uploaders"> for the
957 syntax of that field.
961 An orphaned package is one with no current maintainer. Orphaned
962 packages should have their <tt>Maintainer</tt> control field set
963 to <tt>Debian QA Group <packages@qa.debian.org></tt>.
964 These packages are considered maintained by the Debian project
965 as a whole until someone else volunteers to take over
966 maintenance.<footnote>
967 The detailed procedure for gracefully orphaning a package can
968 be found in the Debian Developer's Reference
969 (see <ref id="related">).
974 <sect id="descriptions">
975 <heading>The description of a package</heading>
978 Every Debian package must have a <tt>Description</tt> control
979 field which contains a synopsis and extended description of the
980 package. Technical information about the format of the
981 <tt>Description</tt> field is in <ref id="f-Description">.
985 The description should describe the package (the program) to a
986 user (system administrator) who has never met it before so that
987 they have enough information to decide whether they want to
988 install it. This description should not just be copied verbatim
989 from the program's documentation.
993 Put important information first, both in the synopsis and
994 extended description. Sometimes only the first part of the
995 synopsis or of the description will be displayed. You can
996 assume that there will usually be a way to see the whole
997 extended description.
1001 The description should also give information about the
1002 significant dependencies and conflicts between this package
1003 and others, so that the user knows why these dependencies and
1004 conflicts have been declared.
1008 Instructions for configuring or using the package should
1009 not be included (that is what installation scripts,
1010 manual pages, info files, etc., are for). Copyright
1011 statements and other administrivia should not be included
1012 either (that is what the copyright file is for).
1015 <sect1 id="synopsis"><heading>The single line synopsis</heading>
1018 The single line synopsis should be kept brief - certainly
1019 under 80 characters.
1023 Do not include the package name in the synopsis line. The
1024 display software knows how to display this already, and you
1025 do not need to state it. Remember that in many situations
1026 the user may only see the synopsis line - make it as
1027 informative as you can.
1032 <sect1 id="extendeddesc"><heading>The extended description</heading>
1035 Do not try to continue the single line synopsis into the
1036 extended description. This will not work correctly when
1037 the full description is displayed, and makes no sense
1038 where only the summary (the single line synopsis) is
1043 The extended description should describe what the package
1044 does and how it relates to the rest of the system (in terms
1045 of, for example, which subsystem it is which part of).
1049 The description field needs to make sense to anyone, even
1050 people who have no idea about any of the things the
1051 package deals with.<footnote>
1052 The blurb that comes with a program in its
1053 announcements and/or <prgn>README</prgn> files is
1054 rarely suitable for use in a description. It is
1055 usually aimed at people who are already in the
1056 community where the package is used.
1065 <heading>Dependencies</heading>
1068 Every package must specify the dependency information
1069 about other packages that are required for the first to
1074 For example, a dependency entry must be provided for any
1075 shared libraries required by a dynamically-linked executable
1076 binary in a package.
1080 Packages are not required to declare any dependencies they
1081 have on other packages which are marked <tt>Essential</tt>
1082 (see below), and should not do so unless they depend on a
1083 particular version of that package.<footnote>
1085 Essential is needed in part to avoid unresolvable dependency
1086 loops on upgrade. If packages add unnecessary dependencies
1087 on packages in this set, the chances that there
1088 <strong>will</strong> be an unresolvable dependency loop
1089 caused by forcing these Essential packages to be configured
1090 first before they need to be is greatly increased. It also
1091 increases the chances that frontends will be unable to
1092 <strong>calculate</strong> an upgrade path, even if one
1096 Also, functionality is rarely ever removed from the
1097 Essential set, but <em>packages</em> have been removed from
1098 the Essential set when the functionality moved to a
1099 different package. So depending on these packages <em>just
1100 in case</em> they stop being essential does way more harm
1107 Sometimes, a package requires another package to be installed
1108 <em>and</em> configured before it can be installed. In this
1109 case, you must specify a <tt>Pre-Depends</tt> entry for
1114 You should not specify a <tt>Pre-Depends</tt> entry for a
1115 package before this has been discussed on the
1116 <tt>debian-devel</tt> mailing list and a consensus about
1117 doing that has been reached.
1121 The format of the package interrelationship control fields is
1122 described in <ref id="relationships">.
1126 <sect id="virtual_pkg">
1127 <heading>Virtual packages</heading>
1130 Sometimes, there are several packages which offer
1131 more-or-less the same functionality. In this case, it's
1132 useful to define a <em>virtual package</em> whose name
1133 describes that common functionality. (The virtual
1134 packages only exist logically, not physically; that's why
1135 they are called <em>virtual</em>.) The packages with this
1136 particular function will then <em>provide</em> the virtual
1137 package. Thus, any other package requiring that function
1138 can simply depend on the virtual package without having to
1139 specify all possible packages individually.
1143 All packages should use virtual package names where
1144 appropriate, and arrange to create new ones if necessary.
1145 They should not use virtual package names (except privately,
1146 amongst a cooperating group of packages) unless they have
1147 been agreed upon and appear in the list of virtual package
1148 names. (See also <ref id="virtual">)
1152 The latest version of the authoritative list of virtual
1153 package names can be found in the <tt>debian-policy</tt> package.
1154 It is also available from the Debian web mirrors at
1155 <tt><url name="/doc/packaging-manuals/virtual-package-names-list.txt"
1156 id="http://www.debian.org/doc/packaging-manuals/virtual-package-names-list.txt"></tt>.
1160 The procedure for updating the list is described in the preface
1167 <heading>Base system</heading>
1170 The <tt>base system</tt> is a minimum subset of the Debian
1171 GNU/Linux system that is installed before everything else
1172 on a new system. Only very few packages are allowed to form
1173 part of the base system, in order to keep the required disk
1178 The base system consists of all those packages with priority
1179 <tt>required</tt> or <tt>important</tt>. Many of them will
1180 be tagged <tt>essential</tt> (see below).
1185 <heading>Essential packages</heading>
1188 Essential is defined as the minimal set of functionality that
1189 must be available and usable on the system at all times, even
1190 when packages are in an unconfigured (but unpacked) state.
1191 Packages are tagged <tt>essential</tt> for a system using the
1192 <tt>Essential</tt> control field. The format of the
1193 <tt>Essential</tt> control field is described in <ref
1198 Since these packages cannot be easily removed (one has to
1199 specify an extra <em>force option</em> to
1200 <prgn>dpkg</prgn> to do so), this flag must not be used
1201 unless absolutely necessary. A shared library package
1202 must not be tagged <tt>essential</tt>; dependencies will
1203 prevent its premature removal, and we need to be able to
1204 remove it when it has been superseded.
1208 Since dpkg will not prevent upgrading of other packages
1209 while an <tt>essential</tt> package is in an unconfigured
1210 state, all <tt>essential</tt> packages must supply all of
1211 their core functionality even when unconfigured. If the
1212 package cannot satisfy this requirement it must not be
1213 tagged as essential, and any packages depending on this
1214 package must instead have explicit dependency fields as
1219 Maintainers should take great care in adding any programs,
1220 interfaces, or functionality to <tt>essential</tt> packages.
1221 Packages may assume that functionality provided by
1222 <tt>essential</tt> packages is always available without
1223 declaring explicit dependencies, which means that removing
1224 functionality from the Essential set is very difficult and is
1225 almost never done. Any capability added to an
1226 <tt>essential</tt> package therefore creates an obligation to
1227 support that capability as part of the Essential set in
1232 You must not tag any packages <tt>essential</tt> before
1233 this has been discussed on the <tt>debian-devel</tt>
1234 mailing list and a consensus about doing that has been
1239 <sect id="maintscripts">
1240 <heading>Maintainer Scripts</heading>
1243 The package installation scripts should avoid producing
1244 output which is unnecessary for the user to see and
1245 should rely on <prgn>dpkg</prgn> to stave off boredom on
1246 the part of a user installing many packages. This means,
1247 amongst other things, using the <tt>--quiet</tt> option on
1248 <prgn>install-info</prgn>.
1252 Errors which occur during the execution of an installation
1253 script must be checked and the installation must not
1254 continue after an error.
1258 Note that in general <ref id="scripts"> applies to package
1259 maintainer scripts, too.
1263 You should not use <prgn>dpkg-divert</prgn> on a file belonging
1264 to another package without consulting the maintainer of that
1265 package first. When adding or removing diversions, package
1266 maintainer scripts must provide the <tt>--package</tt> flag
1267 to <prgn>dpkg-divert</prgn> and must not use <tt>--local</tt>.
1271 All packages which supply an instance of a common command
1272 name (or, in general, filename) should generally use
1273 <prgn>update-alternatives</prgn>, so that they may be
1274 installed together. If <prgn>update-alternatives</prgn>
1275 is not used, then each package must use
1276 <tt>Conflicts</tt> to ensure that other packages are
1277 de-installed. (In this case, it may be appropriate to
1278 specify a conflict against earlier versions of something
1279 that previously did not use
1280 <prgn>update-alternatives</prgn>; this is an exception to
1281 the usual rule that versioned conflicts should be
1285 <sect1 id="maintscriptprompt">
1286 <heading>Prompting in maintainer scripts</heading>
1288 Package maintainer scripts may prompt the user if
1289 necessary. Prompting must be done by communicating
1290 through a program, such as <prgn>debconf</prgn>, which
1291 conforms to the Debian Configuration Management
1292 Specification, version 2 or higher.
1296 Packages which are essential, or which are dependencies of
1297 essential packages, may fall back on another prompting method
1298 if no such interface is available when they are executed.
1302 The Debian Configuration Management Specification is included
1303 in the <file>debconf_specification</file> files in the
1304 <package>debian-policy</package> package.
1305 It is also available from the Debian web mirrors at
1306 <tt><url name="/doc/packaging-manuals/debconf_specification.html"
1307 id="http://www.debian.org/doc/packaging-manuals/debconf_specification.html"></tt>.
1311 Packages which use the Debian Configuration Management
1312 Specification may contain the additional control information
1313 files <file>config</file>
1314 and <file>templates</file>. <file>config</file> is an
1315 additional maintainer script used for package configuration,
1316 and <file>templates</file> contains templates used for user
1317 prompting. The <prgn>config</prgn> script might be run before
1318 the <prgn>preinst</prgn> script and before the package is
1319 unpacked or any of its dependencies or pre-dependencies are
1320 satisfied. Therefore it must work using only the tools
1321 present in <em>essential</em> packages.<footnote>
1322 <package>Debconf</package> or another tool that
1323 implements the Debian Configuration Management
1324 Specification will also be installed, and any
1325 versioned dependencies on it will be satisfied
1326 before preconfiguration begins.
1331 Packages which use the Debian Configuration Management
1332 Specification must allow for translation of their user-visible
1333 messages by using a gettext-based system such as the one
1334 provided by the <package>po-debconf</package> package.
1338 Packages should try to minimize the amount of prompting
1339 they need to do, and they should ensure that the user
1340 will only ever be asked each question once. This means
1341 that packages should try to use appropriate shared
1342 configuration files (such as <file>/etc/papersize</file> and
1343 <file>/etc/news/server</file>), and shared
1344 <package>debconf</package> variables rather than each
1345 prompting for their own list of required pieces of
1350 It also means that an upgrade should not ask the same
1351 questions again, unless the user has used
1352 <tt>dpkg --purge</tt> to remove the package's configuration.
1353 The answers to configuration questions should be stored in an
1354 appropriate place in <file>/etc</file> so that the user can
1355 modify them, and how this has been done should be
1360 If a package has a vitally important piece of
1361 information to pass to the user (such as "don't run me
1362 as I am, you must edit the following configuration files
1363 first or you risk your system emitting badly-formatted
1364 messages"), it should display this in the
1365 <prgn>config</prgn> or <prgn>postinst</prgn> script and
1366 prompt the user to hit return to acknowledge the
1367 message. Copyright messages do not count as vitally
1368 important (they belong in
1369 <file>/usr/share/doc/<var>package</var>/copyright</file>);
1370 neither do instructions on how to use a program (these
1371 should be in on-line documentation, where all the users
1376 Any necessary prompting should almost always be confined
1377 to the <prgn>config</prgn> or <prgn>postinst</prgn>
1378 script. If it is done in the <prgn>postinst</prgn>, it
1379 should be protected with a conditional so that
1380 unnecessary prompting doesn't happen if a package's
1381 installation fails and the <prgn>postinst</prgn> is
1382 called with <tt>abort-upgrade</tt>,
1383 <tt>abort-remove</tt> or <tt>abort-deconfigure</tt>.
1393 <heading>Source packages</heading>
1395 <sect id="standardsversion">
1396 <heading>Standards conformance</heading>
1399 Source packages should specify the most recent version number
1400 of this policy document with which your package complied
1401 when it was last updated.
1405 This information may be used to file bug reports
1406 automatically if your package becomes too much out of date.
1410 The version is specified in the <tt>Standards-Version</tt>
1412 The format of the <tt>Standards-Version</tt> field is
1413 described in <ref id="f-Standards-Version">.
1417 You should regularly, and especially if your package has
1418 become out of date, check for the newest Policy Manual
1419 available and update your package, if necessary. When your
1420 package complies with the new standards you should update the
1421 <tt>Standards-Version</tt> source package field and
1422 release it.<footnote>
1423 See the file <file>upgrading-checklist</file> for
1424 information about policy which has changed between
1425 different versions of this document.
1431 <sect id="pkg-relations">
1432 <heading>Package relationships</heading>
1435 Source packages should specify which binary packages they
1436 require to be installed or not to be installed in order to
1437 build correctly. For example, if building a package
1438 requires a certain compiler, then the compiler should be
1439 specified as a build-time dependency.
1443 It is not necessary to explicitly specify build-time
1444 relationships on a minimal set of packages that are always
1445 needed to compile, link and put in a Debian package a
1446 standard "Hello World!" program written in C or C++. The
1447 required packages are called <em>build-essential</em>, and
1448 an informational list can be found in
1449 <file>/usr/share/doc/build-essential/list</file> (which is
1450 contained in the <tt>build-essential</tt>
1453 <list compact="compact">
1455 This allows maintaining the list separately
1456 from the policy documents (the list does not
1457 need the kind of control that the policy
1461 Having a separate package allows one to install
1462 the build-essential packages on a machine, as
1463 well as allowing other packages such as tasks to
1464 require installation of the build-essential
1465 packages using the depends relation.
1468 The separate package allows bug reports against
1469 the list to be categorized separately from
1470 the policy management process in the BTS.
1477 When specifying the set of build-time dependencies, one
1478 should list only those packages explicitly required by the
1479 build. It is not necessary to list packages which are
1480 required merely because some other package in the list of
1481 build-time dependencies depends on them.<footnote>
1482 The reason for this is that dependencies change, and
1483 you should list all those packages, and <em>only</em>
1484 those packages that <em>you</em> need directly. What
1485 others need is their business. For example, if you
1486 only link against <file>libimlib</file>, you will need to
1487 build-depend on <package>libimlib2-dev</package> but
1488 not against any <tt>libjpeg*</tt> packages, even
1489 though <tt>libimlib2-dev</tt> currently depends on
1490 them: installation of <package>libimlib2-dev</package>
1491 will automatically ensure that all of its run-time
1492 dependencies are satisfied.
1497 If build-time dependencies are specified, it must be
1498 possible to build the package and produce working binaries
1499 on a system with only essential and build-essential
1500 packages installed and also those required to satisfy the
1501 build-time relationships (including any implied
1502 relationships). In particular, this means that version
1503 clauses should be used rigorously in build-time
1504 relationships so that one cannot produce bad or
1505 inconsistently configured packages when the relationships
1506 are properly satisfied.
1510 <ref id="relationships"> explains the technical details.
1515 <heading>Changes to the upstream sources</heading>
1518 If changes to the source code are made that are not
1519 specific to the needs of the Debian system, they should be
1520 sent to the upstream authors in whatever form they prefer
1521 so as to be included in the upstream version of the
1526 If you need to configure the package differently for
1527 Debian or for Linux, and the upstream source doesn't
1528 provide a way to do so, you should add such configuration
1529 facilities (for example, a new <prgn>autoconf</prgn> test
1530 or <tt>#define</tt>) and send the patch to the upstream
1531 authors, with the default set to the way they originally
1532 had it. You can then easily override the default in your
1533 <file>debian/rules</file> or wherever is appropriate.
1537 You should make sure that the <prgn>configure</prgn> utility
1538 detects the correct architecture specification string
1539 (refer to <ref id="arch-spec"> for details).
1543 If you need to edit a <prgn>Makefile</prgn> where GNU-style
1544 <prgn>configure</prgn> scripts are used, you should edit the
1545 <file>.in</file> files rather than editing the
1546 <prgn>Makefile</prgn> directly. This allows the user to
1547 reconfigure the package if necessary. You should
1548 <em>not</em> configure the package and edit the generated
1549 <prgn>Makefile</prgn>! This makes it impossible for someone
1550 else to later reconfigure the package without losing the
1556 <sect id="dpkgchangelog">
1557 <heading>Debian changelog: <file>debian/changelog</file></heading>
1560 Changes in the Debian version of the package should be
1561 briefly explained in the Debian changelog file
1562 <file>debian/changelog</file>.<footnote>
1564 Mistakes in changelogs are usually best rectified by
1565 making a new changelog entry rather than "rewriting
1566 history" by editing old changelog entries.
1569 This includes modifications
1570 made in the Debian package compared to the upstream one
1571 as well as other changes and updates to the package.
1573 Although there is nothing stopping an author who is also
1574 the Debian maintainer from using this changelog for all
1575 their changes, it will have to be renamed if the Debian
1576 and upstream maintainers become different people. In such
1577 a case, however, it might be better to maintain the package
1578 as a non-native package.
1583 The format of the <file>debian/changelog</file> allows the
1584 package building tools to discover which version of the package
1585 is being built and find out other release-specific information.
1589 That format is a series of entries like this:
1591 <example compact="compact">
1592 <var>package</var> (<var>version</var>) <var>distribution(s)</var>; urgency=<var>urgency</var>
1594 [optional blank line(s), stripped]
1596 * <var>change details</var>
1597 <var>more change details</var>
1599 [blank line(s), included in output of dpkg-parsechangelog]
1601 * <var>even more change details</var>
1603 [optional blank line(s), stripped]
1605 -- <var>maintainer name</var> <<var>email address</var>><var>[two spaces]</var> <var>date</var>
1610 <var>package</var> and <var>version</var> are the source
1611 package name and version number.
1615 <var>distribution(s)</var> lists the distributions where
1616 this version should be installed when it is uploaded - it
1617 is copied to the <tt>Distribution</tt> field in the
1618 <file>.changes</file> file. See <ref id="f-Distribution">.
1622 <var>urgency</var> is the value for the <tt>Urgency</tt>
1623 field in the <file>.changes</file> file for the upload
1624 (see <ref id="f-Urgency">). It is not possible to specify
1625 an urgency containing commas; commas are used to separate
1626 <tt><var>keyword</var>=<var>value</var></tt> settings in the
1627 <prgn>dpkg</prgn> changelog format (though there is
1628 currently only one useful <var>keyword</var>,
1633 The change details may in fact be any series of lines
1634 starting with at least two spaces, but conventionally each
1635 change starts with an asterisk and a separating space and
1636 continuation lines are indented so as to bring them in
1637 line with the start of the text above. Blank lines may be
1638 used here to separate groups of changes, if desired.
1642 If this upload resolves bugs recorded in the Bug Tracking
1643 System (BTS), they may be automatically closed on the
1644 inclusion of this package into the Debian archive by
1645 including the string: <tt>closes: Bug#<var>nnnnn</var></tt>
1646 in the change details.<footnote>
1647 To be precise, the string should match the following
1648 Perl regular expression:
1650 /closes:\s*(?:bug)?\#?\s?\d+(?:,\s*(?:bug)?\#?\s?\d+)*/i
1652 Then all of the bug numbers listed will be closed by the
1653 archive maintenance script (<prgn>katie</prgn>) using the
1654 <var>version</var> of the changelog entry.
1656 This information is conveyed via the <tt>Closes</tt> field
1657 in the <tt>.changes</tt> file (see <ref id="f-Closes">).
1661 The maintainer name and email address used in the changelog
1662 should be the details of the person uploading <em>this</em>
1663 version. They are <em>not</em> necessarily those of the
1664 usual package maintainer.<footnote>
1665 If the developer uploading the package is not one of the usual
1666 maintainers of the package (as listed in
1667 the <qref id="f-Maintainer"><tt>Maintainer</tt></qref>
1668 or <qref id="f-Uploaders"><tt>Uploaders</tt></qref> control
1669 fields of the package), the first line of the changelog is
1670 conventionally used to explain why a non-maintainer is
1671 uploading the package. The Debian Developer's Reference
1672 (see <ref id="related">) documents the conventions
1674 The information here will be copied to the <tt>Changed-By</tt>
1675 field in the <tt>.changes</tt> file
1676 (see <ref id="f-Changed-By">), and then later used to send an
1677 acknowledgement when the upload has been installed.
1681 The <var>date</var> has the following format<footnote>
1682 This is the same as the format generated by <tt>date
1684 </footnote> (compatible and with the same semantics of
1685 RFC 2822 and RFC 5322):
1686 <example>day-of-week, dd month yyyy hh:mm:ss +zzzz</example>
1688 <list compact="compact">
1690 day-of week is one of: Mon, Tue, Wed, Thu, Fri, Sat, Sun
1693 dd is a one- or two-digit day of the month (01-31)
1696 month is one of: Jan, Feb, Mar, Apr, May, Jun, Jul, Aug,
1699 <item>yyyy is the four-digit year (e.g. 2010)</item>
1700 <item>hh is the two-digit hour (00-23)</item>
1701 <item>mm is the two-digit minutes (00-59)</item>
1702 <item>ss is the two-digit seconds (00-60)</item>
1704 +zzzz or -zzzz is the the time zone offset from Coordinated
1705 Universal Time (UTC). "+" indicates that the time is ahead
1706 of (i.e., east of) UTC and "-" indicates that the time is
1707 behind (i.e., west of) UTC. The first two digits indicate
1708 the hour difference from UTC and the last two digits
1709 indicate the number of additional minutes difference from
1710 UTC. The last two digits must be in the range 00-59.
1716 The first "title" line with the package name must start
1717 at the left hand margin. The "trailer" line with the
1718 maintainer and date details must be preceded by exactly
1719 one space. The maintainer details and the date must be
1720 separated by exactly two spaces.
1724 The entire changelog must be encoded in UTF-8.
1728 For more information on placement of the changelog files
1729 within binary packages, please see <ref id="changelogs">.
1733 <sect id="dpkgcopyright">
1734 <heading>Copyright: <file>debian/copyright</file></heading>
1736 Every package must be accompanied by a verbatim copy of its
1737 copyright information and distribution license in the file
1738 <file>/usr/share/doc/<var>package</var>/copyright</file>
1739 (see <ref id="copyrightfile"> for further details). Also see
1740 <ref id="pkgcopyright"> for further considerations related
1741 to copyrights for packages.
1745 <heading>Error trapping in makefiles</heading>
1748 When <prgn>make</prgn> invokes a command in a makefile
1749 (including your package's upstream makefiles and
1750 <file>debian/rules</file>), it does so using <prgn>sh</prgn>. This
1751 means that <prgn>sh</prgn>'s usual bad error handling
1752 properties apply: if you include a miniature script as one
1753 of the commands in your makefile you'll find that if you
1754 don't do anything about it then errors are not detected
1755 and <prgn>make</prgn> will blithely continue after
1760 Every time you put more than one shell command (this
1761 includes using a loop) in a makefile command you
1762 must make sure that errors are trapped. For
1763 simple compound commands, such as changing directory and
1764 then running a program, using <tt>&&</tt> rather
1765 than semicolon as a command separator is sufficient. For
1766 more complex commands including most loops and
1767 conditionals you should include a separate <tt>set -e</tt>
1768 command at the start of every makefile command that's
1769 actually one of these miniature shell scripts.
1773 <sect id="timestamps">
1774 <heading>Time Stamps</heading>
1776 Maintainers should preserve the modification times of the
1777 upstream source files in a package, as far as is reasonably
1779 The rationale is that there is some information conveyed
1780 by knowing the age of the file, for example, you could
1781 recognize that some documentation is very old by looking
1782 at the modification time, so it would be nice if the
1783 modification time of the upstream source would be
1789 <sect id="restrictions">
1790 <heading>Restrictions on objects in source packages</heading>
1793 The source package may not contain any hard links<footnote>
1795 This is not currently detected when building source
1796 packages, but only when extracting
1800 Hard links may be permitted at some point in the
1801 future, but would require a fair amount of
1804 </footnote>, device special files, sockets or setuid or
1805 setgid files.<footnote>
1806 Setgid directories are allowed.
1811 <sect id="debianrules">
1812 <heading>Main building script: <file>debian/rules</file></heading>
1815 This file must be an executable makefile, and contains the
1816 package-specific recipes for compiling the package and
1817 building binary package(s) from the source.
1821 It must start with the line <tt>#!/usr/bin/make -f</tt>,
1822 so that it can be invoked by saying its name rather than
1823 invoking <prgn>make</prgn> explicitly. That is, invoking
1824 either of <tt>make -f debian/rules <em>args...</em></tt>
1825 or <tt>./debian/rules <em>args...</em></tt> must result in
1830 Since an interactive <file>debian/rules</file> script makes it
1831 impossible to auto-compile that package and also makes it
1832 hard for other people to reproduce the same binary
1833 package, all <em>required targets</em> must be
1834 non-interactive. At a minimum, required targets are the
1835 ones called by <prgn>dpkg-buildpackage</prgn>, namely,
1836 <em>clean</em>, <em>binary</em>, <em>binary-arch</em>,
1837 <em>binary-indep</em>, and <em>build</em>. It also follows
1838 that any target that these targets depend on must also be
1843 The targets are as follows (required unless stated otherwise):
1845 <tag><tt>build</tt></tag>
1848 The <tt>build</tt> target should perform all the
1849 configuration and compilation of the package.
1850 If a package has an interactive pre-build
1851 configuration routine, the Debian source package
1852 must either be built after this has taken place (so
1853 that the binary package can be built without rerunning
1854 the configuration) or the configuration routine
1855 modified to become non-interactive. (The latter is
1856 preferable if there are architecture-specific features
1857 detected by the configuration routine.)
1861 For some packages, notably ones where the same
1862 source tree is compiled in different ways to produce
1863 two binary packages, the <tt>build</tt> target
1864 does not make much sense. For these packages it is
1865 good enough to provide two (or more) targets
1866 (<tt>build-a</tt> and <tt>build-b</tt> or whatever)
1867 for each of the ways of building the package, and a
1868 <tt>build</tt> target that does nothing. The
1869 <tt>binary</tt> target will have to build the
1870 package in each of the possible ways and make the
1871 binary package out of each.
1875 The <tt>build</tt> target must not do anything
1876 that might require root privilege.
1880 The <tt>build</tt> target may need to run the
1881 <tt>clean</tt> target first - see below.
1885 When a package has a configuration and build routine
1886 which takes a long time, or when the makefiles are
1887 poorly designed, or when <tt>build</tt> needs to
1888 run <tt>clean</tt> first, it is a good idea to
1889 <tt>touch build</tt> when the build process is
1890 complete. This will ensure that if <tt>debian/rules
1891 build</tt> is run again it will not rebuild the whole
1893 Another common way to do this is for <tt>build</tt>
1894 to depend on <prgn>build-stamp</prgn> and to do
1895 nothing else, and for the <prgn>build-stamp</prgn>
1896 target to do the building and to <tt>touch
1897 build-stamp</tt> on completion. This is
1898 especially useful if the build routine creates a
1899 file or directory called <tt>build</tt>; in such a
1900 case, <tt>build</tt> will need to be listed as
1901 a phony target (i.e., as a dependency of the
1902 <tt>.PHONY</tt> target). See the documentation of
1903 <prgn>make</prgn> for more information on phony
1909 <tag><tt>build-arch</tt> (optional),
1910 <tt>build-indep</tt> (optional)
1914 A package may also provide both of the targets
1915 <tt>build-arch</tt> and <tt>build-indep</tt>.
1916 The <tt>build-arch</tt> target, if provided, should
1917 perform all the configuration and compilation required for
1918 producing all architecture-dependant binary packages
1919 (those packages for which the body of the
1920 <tt>Architecture</tt> field in <tt>debian/control</tt> is
1921 not <tt>all</tt>). Similarly, the <tt>build-indep</tt>
1922 target, if provided, should perform all the configuration
1923 and compilation required for producing all
1924 architecture-independent binary packages (those packages
1925 for which the body of the <tt>Architecture</tt> field
1926 in <tt>debian/control</tt> is <tt>all</tt>).
1927 The <tt>build</tt> target should depend on those of the
1928 targets <tt>build-arch</tt> and <tt>build-indep</tt> that
1929 are provided in the rules file.<footnote>
1930 The intent of this split is so that binary-only builds
1931 need not install the dependencies required for
1932 the <tt>build-indep</tt> target. However, this is not
1933 yet used in practice since <tt>dpkg-buildpackage
1934 -B</tt>, and therefore the autobuilders,
1935 invoke <tt>build</tt> rather than <tt>build-arch</tt>
1936 due to the difficulties in determining whether the
1937 optional <tt>build-arch</tt> target exists.
1942 If one or both of the targets <tt>build-arch</tt> and
1943 <tt>build-indep</tt> are not provided, then invoking
1944 <file>debian/rules</file> with one of the not-provided
1945 targets as arguments should produce a exit status code
1946 of 2. Usually this is provided automatically by make
1947 if the target is missing.
1951 The <tt>build-arch</tt> and <tt>build-indep</tt> targets
1952 must not do anything that might require root privilege.
1956 <tag><tt>binary</tt>, <tt>binary-arch</tt>,
1957 <tt>binary-indep</tt>
1961 The <tt>binary</tt> target must be all that is
1962 necessary for the user to build the binary package(s)
1963 produced from this source package. It is
1964 split into two parts: <prgn>binary-arch</prgn> builds
1965 the binary packages which are specific to a particular
1966 architecture, and <tt>binary-indep</tt> builds
1967 those which are not.
1970 <tt>binary</tt> may be (and commonly is) a target with
1971 no commands which simply depends on
1972 <tt>binary-arch</tt> and <tt>binary-indep</tt>.
1975 Both <tt>binary-*</tt> targets should depend on the
1976 <tt>build</tt> target, or on the appropriate
1977 <tt>build-arch</tt> or <tt>build-indep</tt> target, if
1978 provided, so that the package is built if it has not
1979 been already. It should then create the relevant
1980 binary package(s), using <prgn>dpkg-gencontrol</prgn> to
1981 make their control files and <prgn>dpkg-deb</prgn> to
1982 build them and place them in the parent of the top
1987 Both the <tt>binary-arch</tt> and
1988 <tt>binary-indep</tt> targets <em>must</em> exist.
1989 If one of them has nothing to do (which will always be
1990 the case if the source generates only a single binary
1991 package, whether architecture-dependent or not), it
1992 must still exist and must always succeed.
1996 The <tt>binary</tt> targets must be invoked as
1998 The <prgn>fakeroot</prgn> package often allows one
1999 to build a package correctly even without being
2005 <tag><tt>clean</tt></tag>
2008 This must undo any effects that the <tt>build</tt>
2009 and <tt>binary</tt> targets may have had, except
2010 that it should leave alone any output files created in
2011 the parent directory by a run of a <tt>binary</tt>
2016 If a <tt>build</tt> file is touched at the end of
2017 the <tt>build</tt> target, as suggested above, it
2018 should be removed as the first action that
2019 <tt>clean</tt> performs, so that running
2020 <tt>build</tt> again after an interrupted
2021 <tt>clean</tt> doesn't think that everything is
2026 The <tt>clean</tt> target may need to be
2027 invoked as root if <tt>binary</tt> has been
2028 invoked since the last <tt>clean</tt>, or if
2029 <tt>build</tt> has been invoked as root (since
2030 <tt>build</tt> may create directories, for
2035 <tag><tt>get-orig-source</tt> (optional)</tag>
2038 This target fetches the most recent version of the
2039 original source package from a canonical archive site
2040 (via FTP or WWW, for example), does any necessary
2041 rearrangement to turn it into the original source
2042 tar file format described below, and leaves it in the
2047 This target may be invoked in any directory, and
2048 should take care to clean up any temporary files it
2053 This target is optional, but providing it if
2054 possible is a good idea.
2058 <tag><tt>patch</tt> (optional)</tag>
2061 This target performs whatever additional actions are
2062 required to make the source ready for editing (unpacking
2063 additional upstream archives, applying patches, etc.).
2064 It is recommended to be implemented for any package where
2065 <tt>dpkg-source -x</tt> does not result in source ready
2066 for additional modification. See
2067 <ref id="readmesource">.
2073 The <tt>build</tt>, <tt>binary</tt> and
2074 <tt>clean</tt> targets must be invoked with the current
2075 directory being the package's top-level directory.
2080 Additional targets may exist in <file>debian/rules</file>,
2081 either as published or undocumented interfaces or for the
2082 package's internal use.
2086 The architectures we build on and build for are determined
2087 by <prgn>make</prgn> variables using the utility
2088 <qref id="pkg-dpkg-architecture"><prgn>dpkg-architecture</prgn></qref>.
2089 You can determine the
2090 Debian architecture and the GNU style architecture
2091 specification string for the build machine (the machine type
2092 we are building on) as well as for the host machine (the
2093 machine type we are building for). Here is a list of
2094 supported <prgn>make</prgn> variables:
2095 <list compact="compact">
2097 <tt>DEB_*_ARCH</tt> (the Debian architecture)
2100 <tt>DEB_*_ARCH_CPU</tt> (the Debian CPU name)
2103 <tt>DEB_*_ARCH_OS</tt> (the Debian System name)
2106 <tt>DEB_*_GNU_TYPE</tt> (the GNU style architecture
2107 specification string)
2110 <tt>DEB_*_GNU_CPU</tt> (the CPU part of
2111 <tt>DEB_*_GNU_TYPE</tt>)
2114 <tt>DEB_*_GNU_SYSTEM</tt> (the System part of
2115 <tt>DEB_*_GNU_TYPE</tt>)
2117 where <tt>*</tt> is either <tt>BUILD</tt> for specification of
2118 the build machine or <tt>HOST</tt> for specification of the
2123 Backward compatibility can be provided in the rules file
2124 by setting the needed variables to suitable default
2125 values; please refer to the documentation of
2126 <prgn>dpkg-architecture</prgn> for details.
2130 It is important to understand that the <tt>DEB_*_ARCH</tt>
2131 string only determines which Debian architecture we are
2132 building on or for. It should not be used to get the CPU
2133 or system information; the <tt>DEB_*_ARCH_CPU</tt> and
2134 <tt>DEB_*_ARCH_OS</tt> variables should be used for that.
2135 GNU style variables should generally only be used with upstream
2139 <sect1 id="debianrules-options">
2140 <heading><file>debian/rules</file> and
2141 <tt>DEB_BUILD_OPTIONS</tt></heading>
2144 Supporting the standardized environment variable
2145 <tt>DEB_BUILD_OPTIONS</tt> is recommended. This variable can
2146 contain several flags to change how a package is compiled and
2147 built. Each flag must be in the form <var>flag</var> or
2148 <var>flag</var>=<var>options</var>. If multiple flags are
2149 given, they must be separated by whitespace.<footnote>
2150 Some packages support any delimiter, but whitespace is the
2151 easiest to parse inside a makefile and avoids ambiguity with
2152 flag values that contain commas.
2154 <var>flag</var> must start with a lowercase letter
2155 (<tt>a-z</tt>) and consist only of lowercase letters,
2156 numbers (<tt>0-9</tt>), and the characters
2157 <tt>-</tt> and <tt>_</tt> (hyphen and underscore).
2158 <var>options</var> must not contain whitespace. The same
2159 tag should not be given multiple times with conflicting
2160 values. Package maintainers may assume that
2161 <tt>DEB_BUILD_OPTIONS</tt> will not contain conflicting tags.
2165 The meaning of the following tags has been standardized:
2169 This tag says to not run any build-time test suite
2170 provided by the package.
2174 The presence of this tag means that the package should
2175 be compiled with a minimum of optimization. For C
2176 programs, it is best to add <tt>-O0</tt> to
2177 <tt>CFLAGS</tt> (although this is usually the default).
2178 Some programs might fail to build or run at this level
2179 of optimization; it may be necessary to use
2180 <tt>-O1</tt>, for example.
2184 This tag means that the debugging symbols should not be
2185 stripped from the binary during installation, so that
2186 debugging information may be included in the package.
2188 <tag>parallel=n</tag>
2190 This tag means that the package should be built using up
2191 to <tt>n</tt> parallel processes if the package build
2192 system supports this.<footnote>
2193 Packages built with <tt>make</tt> can often implement
2194 this by passing the <tt>-j</tt><var>n</var> option to
2197 If the package build system does not support parallel
2198 builds, this string must be ignored. If the package
2199 build system only supports a lower level of concurrency
2200 than <var>n</var>, the package should be built using as
2201 many parallel processes as the package build system
2202 supports. It is up to the package maintainer to decide
2203 whether the package build times are long enough and the
2204 package build system is robust enough to make supporting
2205 parallel builds worthwhile.
2211 Unknown flags must be ignored by <file>debian/rules</file>.
2215 The following makefile snippet is an example of how one may
2216 implement the build options; you will probably have to
2217 massage this example in order to make it work for your
2219 <example compact="compact">
2222 INSTALL_FILE = $(INSTALL) -p -o root -g root -m 644
2223 INSTALL_PROGRAM = $(INSTALL) -p -o root -g root -m 755
2224 INSTALL_SCRIPT = $(INSTALL) -p -o root -g root -m 755
2225 INSTALL_DIR = $(INSTALL) -p -d -o root -g root -m 755
2227 ifneq (,$(filter noopt,$(DEB_BUILD_OPTIONS)))
2232 ifeq (,$(filter nostrip,$(DEB_BUILD_OPTIONS)))
2233 INSTALL_PROGRAM += -s
2235 ifneq (,$(filter parallel=%,$(DEB_BUILD_OPTIONS)))
2236 NUMJOBS = $(patsubst parallel=%,%,$(filter parallel=%,$(DEB_BUILD_OPTIONS)))
2237 MAKEFLAGS += -j$(NUMJOBS)
2242 ifeq (,$(filter nocheck,$(DEB_BUILD_OPTIONS)))
2243 # Code to run the package test suite.
2250 <!-- FIXME: section pkg-srcsubstvars is the same as substvars -->
2251 <sect id="substvars">
2252 <heading>Variable substitutions: <file>debian/substvars</file></heading>
2255 When <prgn>dpkg-gencontrol</prgn>
2256 generates <qref id="binarycontrolfiles">binary package control
2257 files</qref> (<file>DEBIAN/control</file>), it performs variable
2258 substitutions on its output just before writing it. Variable
2259 substitutions have the form <tt>${<var>variable</var>}</tt>.
2260 The optional file <file>debian/substvars</file> contains
2261 variable substitutions to be used; variables can also be set
2262 directly from <file>debian/rules</file> using the <tt>-V</tt>
2263 option to the source packaging commands, and certain predefined
2264 variables are also available.
2268 The <file>debian/substvars</file> file is usually generated and
2269 modified dynamically by <file>debian/rules</file> targets, in
2270 which case it must be removed by the <tt>clean</tt> target.
2274 See <manref name="deb-substvars" section="5"> for full
2275 details about source variable substitutions, including the
2276 format of <file>debian/substvars</file>.</p>
2279 <sect id="debianwatch">
2280 <heading>Optional upstream source location: <file>debian/watch</file></heading>
2283 This is an optional, recommended configuration file for the
2284 <tt>uscan</tt> utility which defines how to automatically scan
2285 ftp or http sites for newly available updates of the
2286 package. This is used
2287 by <url id="http://dehs.alioth.debian.org/"> and other Debian QA
2288 tools to help with quality control and maintenance of the
2289 distribution as a whole.
2294 <sect id="debianfiles">
2295 <heading>Generated files list: <file>debian/files</file></heading>
2298 This file is not a permanent part of the source tree; it
2299 is used while building packages to record which files are
2300 being generated. <prgn>dpkg-genchanges</prgn> uses it
2301 when it generates a <file>.changes</file> file.
2305 It should not exist in a shipped source package, and so it
2306 (and any backup files or temporary files such as
2307 <file>files.new</file><footnote>
2308 <file>files.new</file> is used as a temporary file by
2309 <prgn>dpkg-gencontrol</prgn> and
2310 <prgn>dpkg-distaddfile</prgn> - they write a new
2311 version of <tt>files</tt> here before renaming it,
2312 to avoid leaving a corrupted copy if an error
2314 </footnote>) should be removed by the
2315 <tt>clean</tt> target. It may also be wise to
2316 ensure a fresh start by emptying or removing it at the
2317 start of the <tt>binary</tt> target.
2321 When <prgn>dpkg-gencontrol</prgn> is run for a binary
2322 package, it adds an entry to <file>debian/files</file> for the
2323 <file>.deb</file> file that will be created when <tt>dpkg-deb
2324 --build</tt> is run for that binary package. So for most
2325 packages all that needs to be done with this file is to
2326 delete it in the <tt>clean</tt> target.
2330 If a package upload includes files besides the source
2331 package and any binary packages whose control files were
2332 made with <prgn>dpkg-gencontrol</prgn> then they should be
2333 placed in the parent of the package's top-level directory
2334 and <prgn>dpkg-distaddfile</prgn> should be called to add
2335 the file to the list in <file>debian/files</file>.</p>
2338 <sect id="embeddedfiles">
2339 <heading>Convenience copies of code</heading>
2342 Some software packages include in their distribution convenience
2343 copies of code from other software packages, generally so that
2344 users compiling from source don't have to download multiple
2345 packages. Debian packages should not make use of these
2346 convenience copies unless the included package is explicitly
2347 intended to be used in this way.<footnote>
2348 For example, parts of the GNU build system work like this.
2350 If the included code is already in the Debian archive in the
2351 form of a library, the Debian packaging should ensure that
2352 binary packages reference the libraries already in Debian and
2353 the convenience copy is not used. If the included code is not
2354 already in Debian, it should be packaged separately as a
2355 prerequisite if possible.
2357 Having multiple copies of the same code in Debian is
2358 inefficient, often creates either static linking or shared
2359 library conflicts, and, most importantly, increases the
2360 difficulty of handling security vulnerabilities in the
2366 <sect id="readmesource">
2367 <heading>Source package handling:
2368 <file>debian/README.source</file></heading>
2371 If running <prgn>dpkg-source -x</prgn> on a source package
2372 doesn't produce the source of the package, ready for editing,
2373 and allow one to make changes and run
2374 <prgn>dpkg-buildpackage</prgn> to produce a modified package
2375 without taking any additional steps, creating a
2376 <file>debian/README.source</file> documentation file is
2377 recommended. This file should explain how to do all of the
2380 <item>Generate the fully patched source, in a form ready for
2381 editing, that would be built to create Debian
2382 packages. Doing this with a <tt>patch</tt> target in
2383 <file>debian/rules</file> is recommended; see
2384 <ref id="debianrules">.</item>
2385 <item>Modify the source and save those modifications so that
2386 they will be applied when building the package.</item>
2387 <item>Remove source modifications that are currently being
2388 applied when building the package.</item>
2389 <item>Optionally, document what steps are necessary to
2390 upgrade the Debian source package to a new upstream version,
2391 if applicable.</item>
2393 This explanation should include specific commands and mention
2394 any additional required Debian packages. It should not assume
2395 familiarity with any specific Debian packaging system or patch
2400 This explanation may refer to a documentation file installed by
2401 one of the package's build dependencies provided that the
2402 referenced documentation clearly explains these tasks and is not
2403 a general reference manual.
2407 <file>debian/README.source</file> may also include any other
2408 information that would be helpful to someone modifying the
2409 source package. Even if the package doesn't fit the above
2410 description, maintainers are encouraged to document in a
2411 <file>debian/README.source</file> file any source package with a
2412 particularly complex or unintuitive source layout or build
2413 system (for example, a package that builds the same source
2414 multiple times to generate different binary packages).
2420 <chapt id="controlfields">
2421 <heading>Control files and their fields</heading>
2424 The package management system manipulates data represented in
2425 a common format, known as <em>control data</em>, stored in
2426 <em>control files</em>.
2427 Control files are used for source packages, binary packages and
2428 the <file>.changes</file> files which control the installation
2429 of uploaded files<footnote>
2430 <prgn>dpkg</prgn>'s internal databases are in a similar
2435 <sect id="controlsyntax">
2436 <heading>Syntax of control files</heading>
2439 A control file consists of one or more paragraphs of
2441 The paragraphs are also sometimes referred to as stanzas.
2443 The paragraphs are separated by blank lines. Some control
2444 files allow only one paragraph; others allow several, in
2445 which case each paragraph usually refers to a different
2446 package. (For example, in source packages, the first
2447 paragraph refers to the source package, and later paragraphs
2448 refer to binary packages generated from the source.)
2452 Each paragraph consists of a series of data fields; each
2453 field consists of the field name, followed by a colon and
2454 then the data/value associated with that field. It ends at
2455 the end of the (logical) line. Horizontal whitespace
2456 (spaces and tabs) may occur immediately before or after the
2457 value and is ignored there; it is conventional to put a
2458 single space after the colon. For example, a field might
2460 <example compact="compact">
2463 the field name is <tt>Package</tt> and the field value
2468 A paragraph must not contain more than one instance of a
2469 particular field name.
2473 Many fields' values may span several lines; in this case
2474 each continuation line must start with a space or a tab.
2475 Any trailing spaces or tabs at the end of individual
2476 lines of a field value are ignored.
2480 In fields where it is specified that lines may not wrap,
2481 only a single line of data is allowed and whitespace is not
2482 significant in a field body. Whitespace must not appear
2483 inside names (of packages, architectures, files or anything
2484 else) or version numbers, or between the characters of
2485 multi-character version relationships.
2489 Field names are not case-sensitive, but it is usual to
2490 capitalize the field names using mixed case as shown below.
2491 Field values are case-sensitive unless the description of the
2492 field says otherwise.
2496 Blank lines, or lines consisting only of spaces and tabs,
2497 are not allowed within field values or between fields - that
2498 would mean a new paragraph.
2502 All control files must be encoded in UTF-8.
2506 <sect id="sourcecontrolfiles">
2507 <heading>Source package control files -- <file>debian/control</file></heading>
2510 The <file>debian/control</file> file contains the most vital
2511 (and version-independent) information about the source package
2512 and about the binary packages it creates.
2516 The first paragraph of the control file contains information about
2517 the source package in general. The subsequent sets each describe a
2518 binary package that the source tree builds.
2522 The fields in the general paragraph (the first one, for the source
2525 <list compact="compact">
2526 <item><qref id="f-Source"><tt>Source</tt></qref> (mandatory)</item>
2527 <item><qref id="f-Maintainer"><tt>Maintainer</tt></qref> (mandatory)</item>
2528 <item><qref id="f-Uploaders"><tt>Uploaders</tt></qref></item>
2529 <item><qref id="f-Section"><tt>Section</tt></qref> (recommended)</item>
2530 <item><qref id="f-Priority"><tt>Priority</tt></qref> (recommended)</item>
2531 <item><qref id="sourcebinarydeps"><tt>Build-Depends</tt> et al</qref></item>
2532 <item><qref id="f-Standards-Version"><tt>Standards-Version</tt></qref> (recommended)</item>
2533 <item><qref id="f-Homepage"><tt>Homepage</tt></qref></item>
2538 The fields in the binary package paragraphs are:
2540 <list compact="compact">
2541 <item><qref id="f-Package"><tt>Package</tt></qref> (mandatory)</item>
2542 <item><qref id="f-Architecture"><tt>Architecture</tt></qref> (mandatory)</item>
2543 <item><qref id="f-Section"><tt>Section</tt></qref> (recommended)</item>
2544 <item><qref id="f-Priority"><tt>Priority</tt></qref> (recommended)</item>
2545 <item><qref id="f-Essential"><tt>Essential</tt></qref></item>
2546 <item><qref id="binarydeps"><tt>Depends</tt> et al</qref></item>
2547 <item><qref id="f-Description"><tt>Description</tt></qref> (mandatory)</item>
2548 <item><qref id="f-Homepage"><tt>Homepage</tt></qref></item>
2553 The syntax and semantics of the fields are described below.
2557 These fields are used by <prgn>dpkg-gencontrol</prgn> to
2558 generate control files for binary packages (see below), by
2559 <prgn>dpkg-genchanges</prgn> to generate the
2560 <file>.changes</file> file to accompany the upload, and by
2561 <prgn>dpkg-source</prgn> when it creates the
2562 <file>.dsc</file> source control file as part of a source
2563 archive. Many fields are permitted to span multiple lines in
2564 <file>debian/control</file> but not in any other control
2565 file. These tools are responsible for removing the line
2566 breaks from such fields when using fields from
2567 <file>debian/control</file> to generate other control files.
2571 The fields here may contain variable references - their
2572 values will be substituted by <prgn>dpkg-gencontrol</prgn>,
2573 <prgn>dpkg-genchanges</prgn> or <prgn>dpkg-source</prgn>
2574 when they generate output control files.
2575 See <ref id="substvars"> for details.
2579 In addition to the control file syntax described <qref
2580 id="controlsyntax">above</qref>, this file may also contain
2581 comment lines starting with <tt>#</tt> without any preceding
2582 whitespace. All such lines are ignored, even in the middle of
2583 continuation lines for a multiline field, and do not end a
2589 <sect id="binarycontrolfiles">
2590 <heading>Binary package control files -- <file>DEBIAN/control</file></heading>
2593 The <file>DEBIAN/control</file> file contains the most vital
2594 (and version-dependent) information about a binary package. It
2595 consists of a single paragraph.
2599 The fields in this file are:
2601 <list compact="compact">
2602 <item><qref id="f-Package"><tt>Package</tt></qref> (mandatory)</item>
2603 <item><qref id="f-Source"><tt>Source</tt></qref></item>
2604 <item><qref id="f-Version"><tt>Version</tt></qref> (mandatory)</item>
2605 <item><qref id="f-Section"><tt>Section</tt></qref> (recommended)</item>
2606 <item><qref id="f-Priority"><tt>Priority</tt></qref> (recommended)</item>
2607 <item><qref id="f-Architecture"><tt>Architecture</tt></qref> (mandatory)</item>
2608 <item><qref id="f-Essential"><tt>Essential</tt></qref></item>
2609 <item><qref id="binarydeps"><tt>Depends</tt> et al</qref></item>
2610 <item><qref id="f-Installed-Size"><tt>Installed-Size</tt></qref></item>
2611 <item><qref id="f-Maintainer"><tt>Maintainer</tt></qref> (mandatory)</item>
2612 <item><qref id="f-Description"><tt>Description</tt></qref> (mandatory)</item>
2613 <item><qref id="f-Homepage"><tt>Homepage</tt></qref></item>
2618 <sect id="debiansourcecontrolfiles">
2619 <heading>Debian source control files -- <tt>.dsc</tt></heading>
2622 This file consists of a single paragraph, possibly surrounded by
2623 a PGP signature. The fields of that paragraph are listed below.
2624 Their syntax is described above, in <ref id="pkg-controlfields">.
2626 <list compact="compact">
2627 <item><qref id="f-Format"><tt>Format</tt></qref> (mandatory)</item>
2628 <item><qref id="f-Source"><tt>Source</tt></qref> (mandatory)</item>
2629 <item><qref id="f-Binary"><tt>Binary</tt></qref></item>
2630 <item><qref id="f-Architecture"><tt>Architecture</tt></qref></item>
2631 <item><qref id="f-Version"><tt>Version</tt></qref> (mandatory)</item>
2632 <item><qref id="f-Maintainer"><tt>Maintainer</tt></qref> (mandatory)</item>
2633 <item><qref id="f-Uploaders"><tt>Uploaders</tt></qref></item>
2634 <item><qref id="f-Homepage"><tt>Homepage</tt></qref></item>
2635 <item><qref id="f-Standards-Version"><tt>Standards-Version</tt></qref> (recommended)</item>
2636 <item><qref id="sourcebinarydeps"><tt>Build-Depends</tt> et al</qref></item>
2637 <item><qref id="f-Checksums"><tt>Checksums-Sha1</tt>
2638 and <tt>Checksums-Sha256</tt></qref> (recommended)</item>
2639 <item><qref id="f-Files"><tt>Files</tt></qref> (mandatory)</item>
2644 The source package control file is generated by
2645 <prgn>dpkg-source</prgn> when it builds the source
2646 archive, from other files in the source package,
2647 described above. When unpacking, it is checked against
2648 the files and directories in the other parts of the
2654 <sect id="debianchangesfiles">
2655 <heading>Debian changes files -- <file>.changes</file></heading>
2658 The <file>.changes</file> files are used by the Debian archive
2659 maintenance software to process updates to packages. They
2660 consist of a single paragraph, possibly surrounded by a PGP
2661 signature. That paragraph contains information from the
2662 <file>debian/control</file> file and other data about the
2663 source package gathered via <file>debian/changelog</file>
2664 and <file>debian/rules</file>.
2668 <file>.changes</file> files have a format version that is
2669 incremented whenever the documented fields or their meaning
2670 change. This document describes format &changesversion;.
2674 The fields in this file are:
2676 <list compact="compact">
2677 <item><qref id="f-Format"><tt>Format</tt></qref> (mandatory)</item>
2678 <item><qref id="f-Date"><tt>Date</tt></qref> (mandatory)</item>
2679 <item><qref id="f-Source"><tt>Source</tt></qref> (mandatory)</item>
2680 <item><qref id="f-Binary"><tt>Binary</tt></qref> (mandatory)</item>
2681 <item><qref id="f-Architecture"><tt>Architecture</tt></qref> (mandatory)</item>
2682 <item><qref id="f-Version"><tt>Version</tt></qref> (mandatory)</item>
2683 <item><qref id="f-Distribution"><tt>Distribution</tt></qref> (mandatory)</item>
2684 <item><qref id="f-Urgency"><tt>Urgency</tt></qref> (recommended)</item>
2685 <item><qref id="f-Maintainer"><tt>Maintainer</tt></qref> (mandatory)</item>
2686 <item><qref id="f-Changed-By"><tt>Changed-By</tt></qref></item>
2687 <item><qref id="f-Description"><tt>Description</tt></qref> (mandatory)</item>
2688 <item><qref id="f-Closes"><tt>Closes</tt></qref></item>
2689 <item><qref id="f-Changes"><tt>Changes</tt></qref> (mandatory)</item>
2690 <item><qref id="f-Checksums"><tt>Checksums-Sha1</tt>
2691 and <tt>Checksums-Sha256</tt></qref> (recommended)</item>
2692 <item><qref id="f-Files"><tt>Files</tt></qref> (mandatory)</item>
2697 <sect id="controlfieldslist">
2698 <heading>List of fields</heading>
2700 <sect1 id="f-Source">
2701 <heading><tt>Source</tt></heading>
2704 This field identifies the source package name.
2708 In <file>debian/control</file> or a <file>.dsc</file> file,
2709 this field must contain only the name of the source package.
2713 In a binary package control file or a <file>.changes</file>
2714 file, the source package name may be followed by a version
2715 number in parentheses<footnote>
2716 It is customary to leave a space after the package name
2717 if a version number is specified.
2719 This version number may be omitted (and is, by
2720 <prgn>dpkg-gencontrol</prgn>) if it has the same value as
2721 the <tt>Version</tt> field of the binary package in
2722 question. The field itself may be omitted from a binary
2723 package control file when the source package has the same
2724 name and version as the binary package.
2728 Package names (both source and binary,
2729 see <ref id="f-Package">) must consist only of lower case
2730 letters (<tt>a-z</tt>), digits (<tt>0-9</tt>), plus
2731 (<tt>+</tt>) and minus (<tt>-</tt>) signs, and periods
2732 (<tt>.</tt>). They must be at least two characters long and
2733 must start with an alphanumeric character.
2737 <sect1 id="f-Maintainer">
2738 <heading><tt>Maintainer</tt></heading>
2741 The package maintainer's name and email address. The name
2742 must come first, then the email address inside angle
2743 brackets <tt><></tt> (in RFC822 format).
2747 If the maintainer's name contains a full stop then the
2748 whole field will not work directly as an email address due
2749 to a misfeature in the syntax specified in RFC822; a
2750 program using this field as an address must check for this
2751 and correct the problem if necessary (for example by
2752 putting the name in round brackets and moving it to the
2753 end, and bringing the email address forward).
2757 See <ref id="maintainer"> for additional requirements and
2758 information about package maintainers.
2762 <sect1 id="f-Uploaders">
2763 <heading><tt>Uploaders</tt></heading>
2766 List of the names and email addresses of co-maintainers of the
2767 package, if any. If the package has other maintainers besides
2768 the one named in the <qref id="f-Maintainer">Maintainer
2769 field</qref>, their names and email addresses should be listed
2770 here. The format of each entry is the same as that of the
2771 Maintainer field, and multiple entries must be comma
2776 This is normally an optional field, but if
2777 the <tt>Maintainer</tt> control field names a group of people
2778 and a shared email address, the <tt>Uploaders</tt> field must
2779 be present and must contain at least one human with their
2780 personal email address.
2784 Any parser that interprets the Uploaders field in
2785 <file>debian/control</file> must permit it to span multiple
2786 lines. Line breaks in an Uploaders field that spans multiple
2787 lines are not significant and the semantics of the field are
2788 the same as if the line breaks had not been present.
2792 <sect1 id="f-Changed-By">
2793 <heading><tt>Changed-By</tt></heading>
2796 The name and email address of the person who prepared this
2797 version of the package, usually a maintainer. The syntax is
2798 the same as for the <qref id="f-Maintainer">Maintainer
2803 <sect1 id="f-Section">
2804 <heading><tt>Section</tt></heading>
2807 This field specifies an application area into which the package
2808 has been classified. See <ref id="subsections">.
2812 When it appears in the <file>debian/control</file> file,
2813 it gives the value for the subfield of the same name in
2814 the <tt>Files</tt> field of the <file>.changes</file> file.
2815 It also gives the default for the same field in the binary
2820 <sect1 id="f-Priority">
2821 <heading><tt>Priority</tt></heading>
2824 This field represents how important it is that the user
2825 have the package installed. See <ref id="priorities">.
2829 When it appears in the <file>debian/control</file> file,
2830 it gives the value for the subfield of the same name in
2831 the <tt>Files</tt> field of the <file>.changes</file> file.
2832 It also gives the default for the same field in the binary
2837 <sect1 id="f-Package">
2838 <heading><tt>Package</tt></heading>
2841 The name of the binary package.
2845 Binary package names must follow the same syntax and
2846 restrictions as source package names. See <ref id="f-Source">
2851 <sect1 id="f-Architecture">
2852 <heading><tt>Architecture</tt></heading>
2855 Depending on context and the control file used, the
2856 <tt>Architecture</tt> field can include the following sets of
2860 A unique single word identifying a Debian machine
2861 architecture as described in <ref id="arch-spec">.
2864 An architecture wildcard identifying a set of Debian
2865 machine architectures, see <ref id="arch-wildcard-spec">.
2866 <tt>any</tt> matches all Debian machine architectures
2867 and is the most frequently used.
2870 <tt>all</tt>, which indicates an
2871 architecture-independent package.
2874 <tt>source</tt>, which indicates a source package.
2880 In the main <file>debian/control</file> file in the source
2881 package, this field may contain the special
2882 value <tt>all</tt>, the special architecture
2883 wildcard <tt>any</tt>, or a list of specific and wildcard
2884 architectures separated by spaces. If <tt>all</tt>
2885 or <tt>any</tt> appears, that value must be the entire
2886 contents of the field. Most packages will use
2887 either <tt>all</tt> or <tt>any</tt>.
2891 Specifying a specific list of architectures indicates that the
2892 source will build an architecture-dependent package only on
2893 architectures included in the list. Specifying a list of
2894 architecture wildcards indicates that the source will build an
2895 architecture-dependent package on only those architectures
2896 that match any of the specified architecture wildcards.
2897 Specifying a list of architectures or architecture wildcards
2898 other than <tt>any</tt> is for the minority of cases where a
2899 program is not portable or is not useful on some
2900 architectures. Where possible, the program should be made
2905 In the source package control file <file>.dsc</file>, this
2906 field may contain either the architecture
2907 wildcard <tt>any</tt> or a list of architectures and
2908 architecture wildcards separated by spaces. If a list is
2909 given, it may include (or consist solely of) the special
2910 value <tt>all</tt>. In other words, in <file>.dsc</file>
2911 files unlike the <file>debian/control</file>, <tt>all</tt> may
2912 occur in combination with specific architectures.
2913 The <tt>Architecture</tt> field in the source package control
2914 file <file>.dsc</file> is generally constructed from
2915 the <tt>Architecture</tt> fields in
2916 the <file>debian/control</file> in the source package.
2920 Specifying <tt>any</tt> indicates that the source package
2921 isn't dependent on any particular architecture and should
2922 compile fine on any one. The produced binary package(s)
2923 will either be specific to whatever the current build
2924 architecture is or will be architecture-independent.
2928 Specifying only <tt>all</tt> indicates that the source package
2929 will only build architecture-independent packages. If this is
2930 the case, <tt>all</tt> must be used rather than <tt>any</tt>;
2931 <tt>any</tt> implies that the source package will build at
2932 least one architecture-dependent package.
2936 Specifying a list of architectures or architecture wildcards
2937 indicates that the source will build an architecture-dependent
2938 package, and will only work correctly on the listed or
2939 matching architectures. If the source package also builds at
2940 least one architecture-independent package, <tt>all</tt> will
2941 also be included in the list.
2945 In a <file>.changes</file> file, the <tt>Architecture</tt>
2946 field lists the architecture(s) of the package(s) currently
2947 being uploaded. This will be a list; if the source for the
2948 package is also being uploaded, the special
2949 entry <tt>source</tt> is also present. <tt>all</tt> will be
2950 present if any architecture-independent packages are being
2951 uploaded. Architecture wildcards such as <tt>any</tt> must
2952 never occur in the <tt>Architecture</tt> field in
2953 the <file>.changes</file> file.
2957 See <ref id="debianrules"> for information on how to get
2958 the architecture for the build process.
2962 <sect1 id="f-Essential">
2963 <heading><tt>Essential</tt></heading>
2966 This is a boolean field which may occur only in the
2967 control file of a binary package or in a per-package fields
2968 paragraph of a main source control data file.
2972 If set to <tt>yes</tt> then the package management system
2973 will refuse to remove the package (upgrading and replacing
2974 it is still possible). The other possible value is <tt>no</tt>,
2975 which is the same as not having the field at all.
2980 <heading>Package interrelationship fields:
2981 <tt>Depends</tt>, <tt>Pre-Depends</tt>,
2982 <tt>Recommends</tt>, <tt>Suggests</tt>,
2983 <tt>Breaks</tt>, <tt>Conflicts</tt>,
2984 <tt>Provides</tt>, <tt>Replaces</tt>, <tt>Enhances</tt>
2988 These fields describe the package's relationships with
2989 other packages. Their syntax and semantics are described
2990 in <ref id="relationships">.</p>
2993 <sect1 id="f-Standards-Version">
2994 <heading><tt>Standards-Version</tt></heading>
2997 The most recent version of the standards (the policy
2998 manual and associated texts) with which the package
3003 The version number has four components: major and minor
3004 version number and major and minor patch level. When the
3005 standards change in a way that requires every package to
3006 change the major number will be changed. Significant
3007 changes that will require work in many packages will be
3008 signaled by a change to the minor number. The major patch
3009 level will be changed for any change to the meaning of the
3010 standards, however small; the minor patch level will be
3011 changed when only cosmetic, typographical or other edits
3012 are made which neither change the meaning of the document
3013 nor affect the contents of packages.
3017 Thus only the first three components of the policy version
3018 are significant in the <em>Standards-Version</em> control
3019 field, and so either these three components or all four
3020 components may be specified.<footnote>
3021 In the past, people specified the full version number
3022 in the Standards-Version field, for example "2.3.0.0".
3023 Since minor patch-level changes don't introduce new
3024 policy, it was thought it would be better to relax
3025 policy and only require the first 3 components to be
3026 specified, in this example "2.3.0". All four
3027 components may still be used if someone wishes to do so.
3033 <sect1 id="f-Version">
3034 <heading><tt>Version</tt></heading>
3037 The version number of a package. The format is:
3038 [<var>epoch</var><tt>:</tt>]<var>upstream_version</var>[<tt>-</tt><var>debian_revision</var>]
3042 The three components here are:
3044 <tag><var>epoch</var></tag>
3047 This is a single (generally small) unsigned integer. It
3048 may be omitted, in which case zero is assumed. If it is
3049 omitted then the <var>upstream_version</var> may not
3054 It is provided to allow mistakes in the version numbers
3055 of older versions of a package, and also a package's
3056 previous version numbering schemes, to be left behind.
3060 <tag><var>upstream_version</var></tag>
3063 This is the main part of the version number. It is
3064 usually the version number of the original ("upstream")
3065 package from which the <file>.deb</file> file has been made,
3066 if this is applicable. Usually this will be in the same
3067 format as that specified by the upstream author(s);
3068 however, it may need to be reformatted to fit into the
3069 package management system's format and comparison
3074 The comparison behavior of the package management system
3075 with respect to the <var>upstream_version</var> is
3076 described below. The <var>upstream_version</var>
3077 portion of the version number is mandatory.
3081 The <var>upstream_version</var> may contain only
3082 alphanumerics<footnote>
3083 Alphanumerics are <tt>A-Za-z0-9</tt> only.
3085 and the characters <tt>.</tt> <tt>+</tt> <tt>-</tt>
3086 <tt>:</tt> <tt>~</tt> (full stop, plus, hyphen, colon,
3087 tilde) and should start with a digit. If there is no
3088 <var>debian_revision</var> then hyphens are not allowed;
3089 if there is no <var>epoch</var> then colons are not
3094 <tag><var>debian_revision</var></tag>
3097 This part of the version number specifies the version of
3098 the Debian package based on the upstream version. It
3099 may contain only alphanumerics and the characters
3100 <tt>+</tt> <tt>.</tt> <tt>~</tt> (plus, full stop,
3101 tilde) and is compared in the same way as the
3102 <var>upstream_version</var> is.
3106 It is optional; if it isn't present then the
3107 <var>upstream_version</var> may not contain a hyphen.
3108 This format represents the case where a piece of
3109 software was written specifically to be a Debian
3110 package, where the Debian package source must always
3111 be identical to the pristine source and therefore no
3112 revision indication is required.
3116 It is conventional to restart the
3117 <var>debian_revision</var> at <tt>1</tt> each time the
3118 <var>upstream_version</var> is increased.
3122 The package management system will break the version
3123 number apart at the last hyphen in the string (if there
3124 is one) to determine the <var>upstream_version</var> and
3125 <var>debian_revision</var>. The absence of a
3126 <var>debian_revision</var> is equivalent to a
3127 <var>debian_revision</var> of <tt>0</tt>.
3134 When comparing two version numbers, first the <var>epoch</var>
3135 of each are compared, then the <var>upstream_version</var> if
3136 <var>epoch</var> is equal, and then <var>debian_revision</var>
3137 if <var>upstream_version</var> is also equal.
3138 <var>epoch</var> is compared numerically. The
3139 <var>upstream_version</var> and <var>debian_revision</var>
3140 parts are compared by the package management system using the
3141 following algorithm:
3145 The strings are compared from left to right.
3149 First the initial part of each string consisting entirely of
3150 non-digit characters is determined. These two parts (one of
3151 which may be empty) are compared lexically. If a difference
3152 is found it is returned. The lexical comparison is a
3153 comparison of ASCII values modified so that all the letters
3154 sort earlier than all the non-letters and so that a tilde
3155 sorts before anything, even the end of a part. For example,
3156 the following parts are in sorted order from earliest to
3157 latest: <tt>~~</tt>, <tt>~~a</tt>, <tt>~</tt>, the empty part,
3158 <tt>a</tt>.<footnote>
3159 One common use of <tt>~</tt> is for upstream pre-releases.
3160 For example, <tt>1.0~beta1~svn1245</tt> sorts earlier than
3161 <tt>1.0~beta1</tt>, which sorts earlier than <tt>1.0</tt>.
3166 Then the initial part of the remainder of each string which
3167 consists entirely of digit characters is determined. The
3168 numerical values of these two parts are compared, and any
3169 difference found is returned as the result of the comparison.
3170 For these purposes an empty string (which can only occur at
3171 the end of one or both version strings being compared) counts
3176 These two steps (comparing and removing initial non-digit
3177 strings and initial digit strings) are repeated until a
3178 difference is found or both strings are exhausted.
3182 Note that the purpose of epochs is to allow us to leave behind
3183 mistakes in version numbering, and to cope with situations
3184 where the version numbering scheme changes. It is
3185 <em>not</em> intended to cope with version numbers containing
3186 strings of letters which the package management system cannot
3187 interpret (such as <tt>ALPHA</tt> or <tt>pre-</tt>), or with
3188 silly orderings.<footnote>
3189 The author of this manual has heard of a package whose
3190 versions went <tt>1.1</tt>, <tt>1.2</tt>, <tt>1.3</tt>,
3191 <tt>1</tt>, <tt>2.1</tt>, <tt>2.2</tt>, <tt>2</tt> and so
3197 <sect1 id="f-Description">
3198 <heading><tt>Description</tt></heading>
3201 In a source or binary control file, the <tt>Description</tt>
3202 field contains a description of the binary package, consisting
3203 of two parts, the synopsis or the short description, and the
3204 long description. The field's format is as follows:
3209 Description: <single line synopsis>
3210 <extended description over several lines>
3215 The lines in the extended description can have these formats:
3221 Those starting with a single space are part of a paragraph.
3222 Successive lines of this form will be word-wrapped when
3223 displayed. The leading space will usually be stripped off.
3227 Those starting with two or more spaces. These will be
3228 displayed verbatim. If the display cannot be panned
3229 horizontally, the displaying program will line wrap them "hard"
3230 (i.e., without taking account of word breaks). If it can they
3231 will be allowed to trail off to the right. None, one or two
3232 initial spaces may be deleted, but the number of spaces
3233 deleted from each line will be the same (so that you can have
3234 indenting work correctly, for example).
3238 Those containing a single space followed by a single full stop
3239 character. These are rendered as blank lines. This is the
3240 <em>only</em> way to get a blank line<footnote>
3241 Completely empty lines will not be rendered as blank lines.
3242 Instead, they will cause the parser to think you're starting
3243 a whole new record in the control file, and will therefore
3244 likely abort with an error.
3249 Those containing a space, a full stop and some more characters.
3250 These are for future expansion. Do not use them.
3256 Do not use tab characters. Their effect is not predictable.
3260 See <ref id="descriptions"> for further information on this.
3264 In a <file>.changes</file> file, the <tt>Description</tt>
3265 field contains a summary of the descriptions for the packages
3266 being uploaded. For this case, the first line of the field
3267 value (the part on the same line as <tt>Description:</tt>) is
3268 always empty. The content of the field is expressed as
3269 continuation lines, one line per package. Each line is
3270 indented by one space and contains the name of a binary
3271 package, a space, a hyphen (<tt>-</tt>), a space, and the
3272 short description line from that package.
3276 <sect1 id="f-Distribution">
3277 <heading><tt>Distribution</tt></heading>
3280 In a <file>.changes</file> file or parsed changelog output
3281 this contains the (space-separated) name(s) of the
3282 distribution(s) where this version of the package should
3283 be installed. Valid distributions are determined by the
3284 archive maintainers.<footnote>
3285 Example distribution names in the Debian archive used in
3286 <file>.changes</file> files are:
3287 <taglist compact="compact">
3288 <tag><em>unstable</em></tag>
3290 This distribution value refers to the
3291 <em>developmental</em> part of the Debian distribution
3292 tree. Most new packages, new upstream versions of
3293 packages and bug fixes go into the <em>unstable</em>
3297 <tag><em>experimental</em></tag>
3299 The packages with this distribution value are deemed
3300 by their maintainers to be high risk. Oftentimes they
3301 represent early beta or developmental packages from
3302 various sources that the maintainers want people to
3303 try, but are not ready to be a part of the other parts
3304 of the Debian distribution tree.
3309 Others are used for updating stable releases or for
3310 security uploads. More information is available in the
3311 Debian Developer's Reference, section "The Debian
3315 The Debian archive software only supports listing a single
3316 distribution. Migration of packages to other distributions is
3317 handled outside of the upload process.
3322 <heading><tt>Date</tt></heading>
3325 This field includes the date the package was built or last
3326 edited. It must be in the same format as the <var>date</var>
3327 in a <file>debian/changelog</file> entry.
3331 The value of this field is usually extracted from the
3332 <file>debian/changelog</file> file - see
3333 <ref id="dpkgchangelog">).
3337 <sect1 id="f-Format">
3338 <heading><tt>Format</tt></heading>
3341 In <qref id="debianchangesfiles"><file>.changes</file></qref>
3342 files, this field declares the format version of that file.
3343 The syntax of the field value is the same as that of
3344 a <qref id="f-Version">package version number</qref> except
3345 that no epoch or Debian revision is allowed. The format
3346 described in this document is <tt>&changesversion;</tt>.
3350 In <qref id="debiansourcecontrolfiles"><file>.dsc</file>
3351 Debian source control</qref> files, this field declares the
3352 format of the source package. The field value is used by
3353 programs acting on a source package to interpret the list of
3354 files in the source package and determine how to unpack it.
3355 The syntax of the field value is a numeric major revision, a
3356 period, a numeric minor revision, and then an optional subtype
3357 after whitespace, which if specified is an alphanumeric word
3358 in parentheses. The subtype is optional in the syntax but may
3359 be mandatory for particular source format revisions.
3361 The source formats currently supported by the Debian archive
3362 software are <tt>1.0</tt>, <tt>3.0 (native)</tt>,
3363 and <tt>3.0 (quilt)</tt>.
3368 <sect1 id="f-Urgency">
3369 <heading><tt>Urgency</tt></heading>
3372 This is a description of how important it is to upgrade to
3373 this version from previous ones. It consists of a single
3374 keyword taking one of the values <tt>low</tt>,
3375 <tt>medium</tt>, <tt>high</tt>, <tt>emergency</tt>, or
3376 <tt>critical</tt><footnote>
3377 Other urgency values are supported with configuration
3378 changes in the archive software but are not used in Debian.
3379 The urgency affects how quickly a package will be considered
3380 for inclusion into the <tt>testing</tt> distribution and
3381 gives an indication of the importance of any fixes included
3382 in the upload. <tt>Emergency</tt> and <tt>critical</tt> are
3383 treated as synonymous.
3384 </footnote> (not case-sensitive) followed by an optional
3385 commentary (separated by a space) which is usually in
3386 parentheses. For example:
3389 Urgency: low (HIGH for users of diversions)
3395 The value of this field is usually extracted from the
3396 <file>debian/changelog</file> file - see
3397 <ref id="dpkgchangelog">.
3401 <sect1 id="f-Changes">
3402 <heading><tt>Changes</tt></heading>
3405 This field contains the human-readable changes data, describing
3406 the differences between the last version and the current one.
3410 The first line of the field value (the part on the same line
3411 as <tt>Changes:</tt>) is always empty. The content of the
3412 field is expressed as continuation lines, with each line
3413 indented by at least one space. Blank lines must be
3414 represented by a line consisting only of a space and a full
3419 The value of this field is usually extracted from the
3420 <file>debian/changelog</file> file - see
3421 <ref id="dpkgchangelog">).
3425 Each version's change information should be preceded by a
3426 "title" line giving at least the version, distribution(s)
3427 and urgency, in a human-readable way.
3431 If data from several versions is being returned the entry
3432 for the most recent version should be returned first, and
3433 entries should be separated by the representation of a
3434 blank line (the "title" line may also be followed by the
3435 representation of a blank line).
3439 <sect1 id="f-Binary">
3440 <heading><tt>Binary</tt></heading>
3443 This field is a list of binary packages. Its syntax and
3444 meaning varies depending on the control file in which it
3449 When it appears in the <file>.dsc</file> file, it lists binary
3450 packages which a source package can produce, separated by
3452 A space after each comma is conventional.
3453 </footnote>. It may span multiple lines. The source package
3454 does not necessarily produce all of these binary packages for
3455 every architecture. The source control file doesn't contain
3456 details of which architectures are appropriate for which of
3457 the binary packages.
3461 When it appears in a <file>.changes</file> file, it lists the
3462 names of the binary packages being uploaded, separated by
3463 whitespace (not commas). It may span multiple lines.
3467 <sect1 id="f-Installed-Size">
3468 <heading><tt>Installed-Size</tt></heading>
3471 This field appears in the control files of binary packages,
3472 and in the <file>Packages</file> files. It gives an estimate
3473 of the total amount of disk space required to install the
3474 named package. Actual installed size may vary based on block
3475 size, file system properties, or actions taken by package
3480 The disk space is given as the integer value of the estimated
3481 installed size in bytes, divided by 1024 and rounded up.
3485 <sect1 id="f-Files">
3486 <heading><tt>Files</tt></heading>
3489 This field contains a list of files with information about
3490 each one. The exact information and syntax varies with
3495 In all cases, Files is a multiline field. The first line of
3496 the field value (the part on the same line as <tt>Files:</tt>)
3497 is always empty. The content of the field is expressed as
3498 continuation lines, one line per file. Each line must be
3499 indented by one space and contain a number of sub-fields,
3500 separated by spaces, as described below.
3504 In the <file>.dsc</file> file, each line contains the MD5
3505 checksum, size and filename of the tar file and (if
3506 applicable) diff file which make up the remainder of the
3507 source package<footnote>
3508 That is, the parts which are not the <tt>.dsc</tt>.
3509 </footnote>. For example:
3512 c6f698f19f2a2aa07dbb9bbda90a2754 571925 example_1.2.orig.tar.gz
3513 938512f08422f3509ff36f125f5873ba 6220 example_1.2-1.diff.gz
3515 The exact forms of the filenames are described
3516 in <ref id="pkg-sourcearchives">.
3520 In the <file>.changes</file> file this contains one line per
3521 file being uploaded. Each line contains the MD5 checksum,
3522 size, section and priority and the filename. For example:
3525 4c31ab7bfc40d3cf49d7811987390357 1428 text extra example_1.2-1.dsc
3526 c6f698f19f2a2aa07dbb9bbda90a2754 571925 text extra example_1.2.orig.tar.gz
3527 938512f08422f3509ff36f125f5873ba 6220 text extra example_1.2-1.diff.gz
3528 7c98fe853b3bbb47a00e5cd129b6cb56 703542 text extra example_1.2-1_i386.deb
3530 The <qref id="f-Section">section</qref>
3531 and <qref id="f-Priority">priority</qref> are the values of
3532 the corresponding fields in the main source control file. If
3533 no section or priority is specified then <tt>-</tt> should be
3534 used, though section and priority values must be specified for
3535 new packages to be installed properly.
3539 The special value <tt>byhand</tt> for the section in a
3540 <tt>.changes</tt> file indicates that the file in question
3541 is not an ordinary package file and must by installed by
3542 hand by the distribution maintainers. If the section is
3543 <tt>byhand</tt> the priority should be <tt>-</tt>.
3547 If a new Debian revision of a package is being shipped and
3548 no new original source archive is being distributed the
3549 <tt>.dsc</tt> must still contain the <tt>Files</tt> field
3550 entry for the original source archive
3551 <file><var>package</var>_<var>upstream-version</var>.orig.tar.gz</file>,
3552 but the <file>.changes</file> file should leave it out. In
3553 this case the original source archive on the distribution
3554 site must match exactly, byte-for-byte, the original
3555 source archive which was used to generate the
3556 <file>.dsc</file> file and diff which are being uploaded.</p>
3559 <sect1 id="f-Closes">
3560 <heading><tt>Closes</tt></heading>
3563 A space-separated list of bug report numbers that the upload
3564 governed by the .changes file closes.
3568 <sect1 id="f-Homepage">
3569 <heading><tt>Homepage</tt></heading>
3572 The URL of the web site for this package, preferably (when
3573 applicable) the site from which the original source can be
3574 obtained and any additional upstream documentation or
3575 information may be found. The content of this field is a
3576 simple URL without any surrounding characters such as
3581 <sect1 id="f-Checksums">
3582 <heading><tt>Checksums-Sha1</tt>
3583 and <tt>Checksums-Sha256</tt></heading>
3586 These fields contain a list of files with a checksum and size
3587 for each one. Both <tt>Checksums-Sha1</tt>
3588 and <tt>Checksums-Sha256</tt> have the same syntax and differ
3589 only in the checksum algorithm used: SHA-1
3590 for <tt>Checksums-Sha1</tt> and SHA-256
3591 for <tt>Checksums-Sha256</tt>.
3595 <tt>Checksums-Sha1</tt> and <tt>Checksums-Sha256</tt> are
3596 multiline fields. The first line of the field value (the part
3597 on the same line as <tt>Checksums-Sha1:</tt>
3598 or <tt>Checksums-Sha256:</tt>) is always empty. The content
3599 of the field is expressed as continuation lines, one line per
3600 file. Each line consists of the checksum, a space, the file
3601 size, a space, and the file name. For example (from
3602 a <file>.changes</file> file):
3605 1f418afaa01464e63cc1ee8a66a05f0848bd155c 1276 example_1.0-1.dsc
3606 a0ed1456fad61116f868b1855530dbe948e20f06 171602 example_1.0.orig.tar.gz
3607 5e86ecf0671e113b63388dac81dd8d00e00ef298 6137 example_1.0-1.debian.tar.gz
3608 71a0ff7da0faaf608481195f9cf30974b142c183 548402 example_1.0-1_i386.deb
3610 ac9d57254f7e835bed299926fd51bf6f534597cc3fcc52db01c4bffedae81272 1276 example_1.0-1.dsc
3611 0d123be7f51e61c4bf15e5c492b484054be7e90f3081608a5517007bfb1fd128 171602 example_1.0.orig.tar.gz
3612 f54ae966a5f580571ae7d9ef5e1df0bd42d63e27cb505b27957351a495bc6288 6137 example_1.0-1.debian.tar.gz
3613 3bec05c03974fdecd11d020fc2e8250de8404867a8a2ce865160c250eb723664 548402 example_1.0-1_i386.deb
3618 In the <file>.dsc</file> file, these fields should list all
3619 files that make up the source package. In
3620 the <file>.changes</file> file, these fields should list all
3621 files being uploaded. The list of files in these fields
3622 must match the list of files in the <tt>Files</tt> field.
3628 <heading>User-defined fields</heading>
3631 Additional user-defined fields may be added to the
3632 source package control file. Such fields will be
3633 ignored, and not copied to (for example) binary or
3634 source package control files or upload control files.
3638 If you wish to add additional unsupported fields to
3639 these output files you should use the mechanism
3644 Fields in the main source control information file with
3645 names starting <tt>X</tt>, followed by one or more of
3646 the letters <tt>BCS</tt> and a hyphen <tt>-</tt>, will
3647 be copied to the output files. Only the part of the
3648 field name after the hyphen will be used in the output
3649 file. Where the letter <tt>B</tt> is used the field
3650 will appear in binary package control files, where the
3651 letter <tt>S</tt> is used in source package control
3652 files and where <tt>C</tt> is used in upload control
3653 (<tt>.changes</tt>) files.
3657 For example, if the main source information control file
3660 XBS-Comment: I stand between the candle and the star.
3662 then the binary and source package control files will contain the
3665 Comment: I stand between the candle and the star.
3674 <chapt id="maintainerscripts">
3675 <heading>Package maintainer scripts and installation procedure</heading>
3678 <heading>Introduction to package maintainer scripts</heading>
3681 It is possible to supply scripts as part of a package which
3682 the package management system will run for you when your
3683 package is installed, upgraded or removed.
3687 These scripts are the control information
3688 files <prgn>preinst</prgn>, <prgn>postinst</prgn>, <prgn>prerm</prgn>
3689 and <prgn>postrm</prgn>. They must be proper executable files;
3690 if they are scripts (which is recommended), they must start with
3691 the usual <tt>#!</tt> convention. They should be readable and
3692 executable by anyone, and must not be world-writable.
3696 The package management system looks at the exit status from
3697 these scripts. It is important that they exit with a
3698 non-zero status if there is an error, so that the package
3699 management system can stop its processing. For shell
3700 scripts this means that you <em>almost always</em> need to
3701 use <tt>set -e</tt> (this is usually true when writing shell
3702 scripts, in fact). It is also important, of course, that
3703 they exit with a zero status if everything went well.
3707 Additionally, packages interacting with users
3708 using <prgn>debconf</prgn> in the <prgn>postinst</prgn> script
3709 should install a <prgn>config</prgn> script as a control
3710 information file. See <ref id="maintscriptprompt"> for details.
3714 When a package is upgraded a combination of the scripts from
3715 the old and new packages is called during the upgrade
3716 procedure. If your scripts are going to be at all
3717 complicated you need to be aware of this, and may need to
3718 check the arguments to your scripts.
3722 Broadly speaking the <prgn>preinst</prgn> is called before
3723 (a particular version of) a package is installed, and the
3724 <prgn>postinst</prgn> afterwards; the <prgn>prerm</prgn>
3725 before (a version of) a package is removed and the
3726 <prgn>postrm</prgn> afterwards.
3730 Programs called from maintainer scripts should not normally
3731 have a path prepended to them. Before installation is
3732 started, the package management system checks to see if the
3733 programs <prgn>ldconfig</prgn>,
3734 <prgn>start-stop-daemon</prgn>, <prgn>install-info</prgn>,
3735 and <prgn>update-rc.d</prgn> can be found via the
3736 <tt>PATH</tt> environment variable. Those programs, and any
3737 other program that one would expect to be in the
3738 <tt>PATH</tt>, should thus be invoked without an absolute
3739 pathname. Maintainer scripts should also not reset the
3740 <tt>PATH</tt>, though they might choose to modify it by
3741 prepending or appending package-specific directories. These
3742 considerations really apply to all shell scripts.</p>
3745 <sect id="idempotency">
3746 <heading>Maintainer scripts idempotency</heading>
3749 It is necessary for the error recovery procedures that the
3750 scripts be idempotent. This means that if it is run
3751 successfully, and then it is called again, it doesn't bomb
3752 out or cause any harm, but just ensures that everything is
3753 the way it ought to be. If the first call failed, or
3754 aborted half way through for some reason, the second call
3755 should merely do the things that were left undone the first
3756 time, if any, and exit with a success status if everything
3758 This is so that if an error occurs, the user interrupts
3759 <prgn>dpkg</prgn> or some other unforeseen circumstance
3760 happens you don't leave the user with a badly-broken
3761 package when <prgn>dpkg</prgn> attempts to repeat the
3767 <sect id="controllingterminal">
3768 <heading>Controlling terminal for maintainer scripts</heading>
3771 Maintainer scripts are not guaranteed to run with a controlling
3772 terminal and may not be able to interact with the user. They
3773 must be able to fall back to noninteractive behavior if no
3774 controlling terminal is available. Maintainer scripts that
3775 prompt via a program conforming to the Debian Configuration
3776 Management Specification (see <ref id="maintscriptprompt">) may
3777 assume that program will handle falling back to noninteractive
3782 For high-priority prompts without a reasonable default answer,
3783 maintainer scripts may abort if there is no controlling
3784 terminal. However, this situation should be avoided if at all
3785 possible, since it prevents automated or unattended installs.
3786 In most cases, users will consider this to be a bug in the
3791 <sect id="exitstatus">
3792 <heading>Exit status</heading>
3795 Each script must return a zero exit status for
3796 success, or a nonzero one for failure, since the package
3797 management system looks for the exit status of these scripts
3798 and determines what action to take next based on that datum.
3802 <sect id="mscriptsinstact"><heading>Summary of ways maintainer
3807 <list compact="compact">
3809 <var>new-preinst</var> <tt>install</tt>
3812 <var>new-preinst</var> <tt>install</tt> <var>old-version</var>
3815 <var>new-preinst</var> <tt>upgrade</tt> <var>old-version</var>
3818 <var>old-preinst</var> <tt>abort-upgrade</tt>
3819 <var>new-version</var>
3824 <list compact="compact">
3826 <var>postinst</var> <tt>configure</tt>
3827 <var>most-recently-configured-version</var>
3830 <var>old-postinst</var> <tt>abort-upgrade</tt>
3831 <var>new-version</var>
3834 <var>conflictor's-postinst</var> <tt>abort-remove</tt>
3835 <tt>in-favour</tt> <var>package</var>
3836 <var>new-version</var>
3839 <var>postinst</var> <tt>abort-remove</tt>
3842 <var>deconfigured's-postinst</var>
3843 <tt>abort-deconfigure</tt> <tt>in-favour</tt>
3844 <var>failed-install-package</var> <var>version</var>
3845 [<tt>removing</tt> <var>conflicting-package</var>
3851 <list compact="compact">
3853 <var>prerm</var> <tt>remove</tt>
3856 <var>old-prerm</var> <tt>upgrade</tt>
3857 <var>new-version</var>
3860 <var>new-prerm</var> <tt>failed-upgrade</tt>
3861 <var>old-version</var>
3864 <var>conflictor's-prerm</var> <tt>remove</tt>
3865 <tt>in-favour</tt> <var>package</var>
3866 <var>new-version</var>
3869 <var>deconfigured's-prerm</var> <tt>deconfigure</tt>
3870 <tt>in-favour</tt> <var>package-being-installed</var>
3871 <var>version</var> [<tt>removing</tt>
3872 <var>conflicting-package</var>
3878 <list compact="compact">
3880 <var>postrm</var> <tt>remove</tt>
3883 <var>postrm</var> <tt>purge</tt>
3886 <var>old-postrm</var> <tt>upgrade</tt>
3887 <var>new-version</var>
3890 <var>new-postrm</var> <tt>failed-upgrade</tt>
3891 <var>old-version</var>
3894 <var>new-postrm</var> <tt>abort-install</tt>
3897 <var>new-postrm</var> <tt>abort-install</tt>
3898 <var>old-version</var>
3901 <var>new-postrm</var> <tt>abort-upgrade</tt>
3902 <var>old-version</var>
3905 <var>disappearer's-postrm</var> <tt>disappear</tt>
3906 <var>overwriter</var>
3907 <var>overwriter-version</var>
3913 <sect id="unpackphase">
3914 <heading>Details of unpack phase of installation or upgrade</heading>
3917 The procedure on installation/upgrade/overwrite/disappear
3918 (i.e., when running <tt>dpkg --unpack</tt>, or the unpack
3919 stage of <tt>dpkg --install</tt>) is as follows. In each
3920 case, if a major error occurs (unless listed below) the
3921 actions are, in general, run backwards - this means that the
3922 maintainer scripts are run with different arguments in
3923 reverse order. These are the "error unwind" calls listed
3930 If a version of the package is already installed, call
3931 <example compact="compact">
3932 <var>old-prerm</var> upgrade <var>new-version</var>
3936 If the script runs but exits with a non-zero
3937 exit status, <prgn>dpkg</prgn> will attempt:
3938 <example compact="compact">
3939 <var>new-prerm</var> failed-upgrade <var>old-version</var>
3941 If this works, the upgrade continues. If this
3942 does not work, the error unwind:
3943 <example compact="compact">
3944 <var>old-postinst</var> abort-upgrade <var>new-version</var>
3946 If this works, then the old-version is
3947 "Installed", if not, the old version is in a
3948 "Half-Configured" state.
3954 If a "conflicting" package is being removed at the same time,
3955 or if any package will be broken (due to <tt>Breaks</tt>):
3958 If <tt>--auto-deconfigure</tt> is
3959 specified, call, for each package to be deconfigured
3960 due to <tt>Breaks</tt>:
3961 <example compact="compact">
3962 <var>deconfigured's-prerm</var> deconfigure \
3963 in-favour <var>package-being-installed</var> <var>version</var>
3966 <example compact="compact">
3967 <var>deconfigured's-postinst</var> abort-deconfigure \
3968 in-favour <var>package-being-installed-but-failed</var> <var>version</var>
3970 The deconfigured packages are marked as
3971 requiring configuration, so that if
3972 <tt>--install</tt> is used they will be
3973 configured again if possible.
3976 If any packages depended on a conflicting
3977 package being removed and <tt>--auto-deconfigure</tt> is
3978 specified, call, for each such package:
3979 <example compact="compact">
3980 <var>deconfigured's-prerm</var> deconfigure \
3981 in-favour <var>package-being-installed</var> <var>version</var> \
3982 removing <var>conflicting-package</var> <var>version</var>
3985 <example compact="compact">
3986 <var>deconfigured's-postinst</var> abort-deconfigure \
3987 in-favour <var>package-being-installed-but-failed</var> <var>version</var> \
3988 removing <var>conflicting-package</var> <var>version</var>
3990 The deconfigured packages are marked as
3991 requiring configuration, so that if
3992 <tt>--install</tt> is used they will be
3993 configured again if possible.
3996 To prepare for removal of each conflicting package, call:
3997 <example compact="compact">
3998 <var>conflictor's-prerm</var> remove \
3999 in-favour <var>package</var> <var>new-version</var>
4002 <example compact="compact">
4003 <var>conflictor's-postinst</var> abort-remove \
4004 in-favour <var>package</var> <var>new-version</var>
4013 If the package is being upgraded, call:
4014 <example compact="compact">
4015 <var>new-preinst</var> upgrade <var>old-version</var>
4017 If this fails, we call:
4019 <var>new-postrm</var> abort-upgrade <var>old-version</var>
4026 <var>old-postinst</var> abort-upgrade <var>new-version</var>
4028 is called. If this works, then the old version
4029 is in an "Installed" state, or else it is left
4030 in an "Unpacked" state.
4035 If it fails, then the old version is left
4036 in an "Half-Installed" state.
4043 Otherwise, if the package had some configuration
4044 files from a previous version installed (i.e., it
4045 is in the "configuration files only" state):
4046 <example compact="compact">
4047 <var>new-preinst</var> install <var>old-version</var>
4051 <var>new-postrm</var> abort-install <var>old-version</var>
4053 If this fails, the package is left in a
4054 "Half-Installed" state, which requires a
4055 reinstall. If it works, the packages is left in
4056 a "Config-Files" state.
4059 Otherwise (i.e., the package was completely purged):
4060 <example compact="compact">
4061 <var>new-preinst</var> install
4064 <example compact="compact">
4065 <var>new-postrm</var> abort-install
4067 If the error-unwind fails, the package is in a
4068 "Half-Installed" phase, and requires a
4069 reinstall. If the error unwind works, the
4070 package is in a not installed state.
4077 The new package's files are unpacked, overwriting any
4078 that may be on the system already, for example any
4079 from the old version of the same package or from
4080 another package. Backups of the old files are kept
4081 temporarily, and if anything goes wrong the package
4082 management system will attempt to put them back as
4083 part of the error unwind.
4087 It is an error for a package to contain files which
4088 are on the system in another package, unless
4089 <tt>Replaces</tt> is used (see <ref id="replaces">).
4091 The following paragraph is not currently the case:
4092 Currently the <tt>- - force-overwrite</tt> flag is
4093 enabled, downgrading it to a warning, but this may not
4099 It is a more serious error for a package to contain a
4100 plain file or other kind of non-directory where another
4101 package has a directory (again, unless
4102 <tt>Replaces</tt> is used). This error can be
4103 overridden if desired using
4104 <tt>--force-overwrite-dir</tt>, but this is not
4109 Packages which overwrite each other's files produce
4110 behavior which, though deterministic, is hard for the
4111 system administrator to understand. It can easily
4112 lead to "missing" programs if, for example, a package
4113 is installed which overwrites a file from another
4114 package, and is then removed again.<footnote>
4115 Part of the problem is due to what is arguably a
4116 bug in <prgn>dpkg</prgn>.
4121 A directory will never be replaced by a symbolic link
4122 to a directory or vice versa; instead, the existing
4123 state (symlink or not) will be left alone and
4124 <prgn>dpkg</prgn> will follow the symlink if there is
4133 If the package is being upgraded, call
4134 <example compact="compact">
4135 <var>old-postrm</var> upgrade <var>new-version</var>
4139 If this fails, <prgn>dpkg</prgn> will attempt:
4140 <example compact="compact">
4141 <var>new-postrm</var> failed-upgrade <var>old-version</var>
4143 If this works, installation continues. If not,
4145 <example compact="compact">
4146 <var>old-preinst</var> abort-upgrade <var>new-version</var>
4148 If this fails, the old version is left in a
4149 "Half-Installed" state. If it works, dpkg now
4151 <example compact="compact">
4152 <var>new-postrm</var> abort-upgrade <var>old-version</var>
4154 If this fails, the old version is left in a
4155 "Half-Installed" state. If it works, dpkg now
4157 <example compact="compact">
4158 <var>old-postinst</var> abort-upgrade <var>new-version</var>
4160 If this fails, the old version is in an
4167 This is the point of no return - if
4168 <prgn>dpkg</prgn> gets this far, it won't back off
4169 past this point if an error occurs. This will
4170 leave the package in a fairly bad state, which
4171 will require a successful re-installation to clear
4172 up, but it's when <prgn>dpkg</prgn> starts doing
4173 things that are irreversible.
4178 Any files which were in the old version of the package
4179 but not in the new are removed.
4183 The new file list replaces the old.
4187 The new maintainer scripts replace the old.
4191 Any packages all of whose files have been overwritten
4192 during the installation, and which aren't required for
4193 dependencies, are considered to have been removed.
4194 For each such package
4197 <prgn>dpkg</prgn> calls:
4198 <example compact="compact">
4199 <var>disappearer's-postrm</var> disappear \
4200 <var>overwriter</var> <var>overwriter-version</var>
4204 The package's maintainer scripts are removed.
4207 It is noted in the status database as being in a
4208 sane state, namely not installed (any conffiles
4209 it may have are ignored, rather than being
4210 removed by <prgn>dpkg</prgn>). Note that
4211 disappearing packages do not have their prerm
4212 called, because <prgn>dpkg</prgn> doesn't know
4213 in advance that the package is going to
4220 Any files in the package we're unpacking that are also
4221 listed in the file lists of other packages are removed
4222 from those lists. (This will lobotomize the file list
4223 of the "conflicting" package if there is one.)
4227 The backup files made during installation, above, are
4233 The new package's status is now sane, and recorded as
4238 Here is another point of no return - if the
4239 conflicting package's removal fails we do not unwind
4240 the rest of the installation; the conflicting package
4241 is left in a half-removed limbo.
4246 If there was a conflicting package we go and do the
4247 removal actions (described below), starting with the
4248 removal of the conflicting package's files (any that
4249 are also in the package being installed have already
4250 been removed from the conflicting package's file list,
4251 and so do not get removed now).
4257 <sect id="configdetails"><heading>Details of configuration</heading>
4260 When we configure a package (this happens with <tt>dpkg
4261 --install</tt> and <tt>dpkg --configure</tt>), we first
4262 update any <tt>conffile</tt>s and then call:
4263 <example compact="compact">
4264 <var>postinst</var> configure <var>most-recently-configured-version</var>
4269 No attempt is made to unwind after errors during
4270 configuration. If the configuration fails, the package is in
4271 a "Failed Config" state, and an error message is generated.
4275 If there is no most recently configured version
4276 <prgn>dpkg</prgn> will pass a null argument.
4279 Historical note: Truly ancient (pre-1997) versions of
4280 <prgn>dpkg</prgn> passed <tt><unknown></tt>
4281 (including the angle brackets) in this case. Even older
4282 ones did not pass a second argument at all, under any
4283 circumstance. Note that upgrades using such an old dpkg
4284 version are unlikely to work for other reasons, even if
4285 this old argument behavior is handled by your postinst script.
4291 <sect id="removedetails"><heading>Details of removal and/or
4292 configuration purging</heading>
4298 <example compact="compact">
4299 <var>prerm</var> remove
4303 If prerm fails during replacement due to conflict
4305 <var>conflictor's-postinst</var> abort-remove \
4306 in-favour <var>package</var> <var>new-version</var>
4310 <var>postinst</var> abort-remove
4314 If this fails, the package is in a "Half-Configured"
4315 state, or else it remains "Installed".
4319 The package's files are removed (except <tt>conffile</tt>s).
4322 <example compact="compact">
4323 <var>postrm</var> remove
4327 If it fails, there's no error unwind, and the package is in
4328 an "Half-Installed" state.
4333 All the maintainer scripts except the <prgn>postrm</prgn>
4338 If we aren't purging the package we stop here. Note
4339 that packages which have no <prgn>postrm</prgn> and no
4340 <tt>conffile</tt>s are automatically purged when
4341 removed, as there is no difference except for the
4342 <prgn>dpkg</prgn> status.
4346 The <tt>conffile</tt>s and any backup files
4347 (<tt>~</tt>-files, <tt>#*#</tt> files,
4348 <tt>%</tt>-files, <tt>.dpkg-{old,new,tmp}</tt>, etc.)
4353 <example compact="compact">
4354 <var>postrm</var> purge
4358 If this fails, the package remains in a "Config-Files"
4363 The package's file list is removed.
4372 <chapt id="relationships">
4373 <heading>Declaring relationships between packages</heading>
4375 <sect id="depsyntax">
4376 <heading>Syntax of relationship fields</heading>
4379 These fields all have a uniform syntax. They are a list of
4380 package names separated by commas.
4384 In the <tt>Depends</tt>, <tt>Recommends</tt>,
4385 <tt>Suggests</tt>, <tt>Pre-Depends</tt>,
4386 <tt>Build-Depends</tt> and <tt>Build-Depends-Indep</tt>
4387 control fields of the package, which declare
4388 dependencies on other packages, the package names listed may
4389 also include lists of alternative package names, separated
4390 by vertical bar (pipe) symbols <tt>|</tt>. In such a case,
4391 if any one of the alternative packages is installed, that
4392 part of the dependency is considered to be satisfied.
4396 All of the fields except for <tt>Provides</tt> may restrict
4397 their applicability to particular versions of each named
4398 package. This is done in parentheses after each individual
4399 package name; the parentheses should contain a relation from
4400 the list below followed by a version number, in the format
4401 described in <ref id="f-Version">.
4405 The relations allowed are <tt><<</tt>, <tt><=</tt>,
4406 <tt>=</tt>, <tt>>=</tt> and <tt>>></tt> for
4407 strictly earlier, earlier or equal, exactly equal, later or
4408 equal and strictly later, respectively. The deprecated
4409 forms <tt><</tt> and <tt>></tt> were used to mean
4410 earlier/later or equal, rather than strictly earlier/later,
4411 so they should not appear in new packages (though
4412 <prgn>dpkg</prgn> still supports them).
4416 Whitespace may appear at any point in the version
4417 specification subject to the rules in <ref
4418 id="controlsyntax">, and must appear where it's necessary to
4419 disambiguate; it is not otherwise significant. All of the
4420 relationship fields may span multiple lines. For
4421 consistency and in case of future changes to
4422 <prgn>dpkg</prgn> it is recommended that a single space be
4423 used after a version relationship and before a version
4424 number; it is also conventional to put a single space after
4425 each comma, on either side of each vertical bar, and before
4426 each open parenthesis. When wrapping a relationship field, it
4427 is conventional to do so after a comma and before the space
4428 following that comma.
4432 For example, a list of dependencies might appear as:
4433 <example compact="compact">
4436 Depends: libc6 (>= 2.2.1), exim | mail-transport-agent
4441 Relationships may be restricted to a certain set of
4442 architectures. This is indicated in brackets after each
4443 individual package name and the optional version specification.
4444 The brackets enclose a list of Debian architecture names
4445 separated by whitespace. Exclamation marks may be prepended to
4446 each of the names. (It is not permitted for some names to be
4447 prepended with exclamation marks while others aren't.)
4451 For build relationship fields
4452 (<tt>Build-Depends</tt>, <tt>Build-Depends-Indep</tt>,
4453 <tt>Build-Conflicts</tt> and <tt>Build-Conflicts-Indep</tt>), if
4454 the current Debian host architecture is not in this list and
4455 there are no exclamation marks in the list, or it is in the list
4456 with a prepended exclamation mark, the package name and the
4457 associated version specification are ignored completely for the
4458 purposes of defining the relationships.
4463 <example compact="compact">
4465 Build-Depends-Indep: texinfo
4466 Build-Depends: kernel-headers-2.2.10 [!hurd-i386],
4467 hurd-dev [hurd-i386], gnumach-dev [hurd-i386]
4469 requires <tt>kernel-headers-2.2.10</tt> on all architectures
4470 other than hurd-i386 and requires <tt>hurd-dev</tt> and
4471 <tt>gnumach-dev</tt> only on hurd-i386.
4475 For binary relationship fields, the architecture restriction
4476 syntax is only supported in the source package control
4477 file <file>debian/control</file>. When the corresponding binary
4478 package control file is generated, the relationship will either
4479 be omitted or included without the architecture restriction
4480 based on the architecture of the binary package. This means
4481 that architecture restrictions must not be used in binary
4482 relationship fields for architecture-independent packages
4483 (<tt>Architecture: all</tt>).
4488 <example compact="compact">
4489 Depends: foo [i386], bar [amd64]
4491 becomes <tt>Depends: foo</tt> when the package is built on
4492 the <tt>i386</tt> architecture, <tt>Depends: bar</tt> when the
4493 package is built on the <tt>amd64</tt> architecture, and omitted
4494 entirely in binary packages built on all other architectures.
4498 If the architecture-restricted dependency is part of a set of
4499 alternatives using <tt>|</tt>, that alternative is ignored
4500 completely on architectures that do not match the restriction.
4502 <example compact="compact">
4503 Build-Depends: foo [!i386] | bar [!amd64]
4505 is equivalent to <tt>bar</tt> on the i386 architecture, to
4506 <tt>foo</tt> on the amd64 architecture, and to <tt>foo |
4507 bar</tt> on all other architectures.
4511 Relationships may also be restricted to a certain set of
4512 architectures using architecture wildcards. The syntax for
4513 declaring such restrictions is the same as declaring
4514 restrictions using a certain set of architectures without
4515 architecture wildcards. For example:
4516 <example compact="compact">
4517 Build-Depends: foo [linux-any], bar [any-i386], baz [!linux-any]
4519 is equivalent to <tt>foo</tt> on architectures using the Linux
4520 kernel and any cpu, <tt>bar</tt> on architectures using any
4521 kernel and an i386 cpu, and <tt>baz</tt> on any architecture
4522 using a kernel other than Linux.
4526 Note that the binary package relationship fields such as
4527 <tt>Depends</tt> appear in one of the binary package
4528 sections of the control file, whereas the build-time
4529 relationships such as <tt>Build-Depends</tt> appear in the
4530 source package section of the control file (which is the
4535 <sect id="binarydeps">
4536 <heading>Binary Dependencies - <tt>Depends</tt>,
4537 <tt>Recommends</tt>, <tt>Suggests</tt>, <tt>Enhances</tt>,
4538 <tt>Pre-Depends</tt>
4542 Packages can declare in their control file that they have
4543 certain relationships to other packages - for example, that
4544 they may not be installed at the same time as certain other
4545 packages, and/or that they depend on the presence of others.
4549 This is done using the <tt>Depends</tt>, <tt>Pre-Depends</tt>,
4550 <tt>Recommends</tt>, <tt>Suggests</tt>, <tt>Enhances</tt>,
4551 <tt>Breaks</tt> and <tt>Conflicts</tt> control fields.
4552 <tt>Breaks</tt> is described in <ref id="breaks">, and
4553 <tt>Conflicts</tt> is described in <ref id="conflicts">. The
4554 rest are described below.
4558 These seven fields are used to declare a dependency
4559 relationship by one package on another. Except for
4560 <tt>Enhances</tt> and <tt>Breaks</tt>, they appear in the
4561 depending (binary) package's control file.
4562 (<tt>Enhances</tt> appears in the recommending package's
4563 control file, and <tt>Breaks</tt> appears in the version of
4564 depended-on package which causes the named package to
4569 A <tt>Depends</tt> field takes effect <em>only</em> when a
4570 package is to be configured. It does not prevent a package
4571 being on the system in an unconfigured state while its
4572 dependencies are unsatisfied, and it is possible to replace
4573 a package whose dependencies are satisfied and which is
4574 properly installed with a different version whose
4575 dependencies are not and cannot be satisfied; when this is
4576 done the depending package will be left unconfigured (since
4577 attempts to configure it will give errors) and will not
4578 function properly. If it is necessary, a
4579 <tt>Pre-Depends</tt> field can be used, which has a partial
4580 effect even when a package is being unpacked, as explained
4581 in detail below. (The other three dependency fields,
4582 <tt>Recommends</tt>, <tt>Suggests</tt> and
4583 <tt>Enhances</tt>, are only used by the various front-ends
4584 to <prgn>dpkg</prgn> such as <prgn>apt-get</prgn>,
4585 <prgn>aptitude</prgn>, and <prgn>dselect</prgn>.)
4589 For this reason packages in an installation run are usually
4590 all unpacked first and all configured later; this gives
4591 later versions of packages with dependencies on later
4592 versions of other packages the opportunity to have their
4593 dependencies satisfied.
4597 In case of circular dependencies, since installation or
4598 removal order honoring the dependency order can't be
4599 established, dependency loops are broken at some point
4600 (based on rules below), and some packages may not be able to
4601 rely on their dependencies being present when being
4602 installed or removed, depending on which side of the break
4603 of the circular dependency loop they happen to be on. If one
4604 of the packages in the loop has no postinst script, then the
4605 cycle will be broken at that package, so as to ensure that
4606 all postinst scripts run with the dependencies properly
4607 configured if this is possible. Otherwise the breaking point
4612 The <tt>Depends</tt> field thus allows package maintainers
4613 to impose an order in which packages should be configured.
4617 The meaning of the five dependency fields is as follows:
4619 <tag><tt>Depends</tt></tag>
4622 This declares an absolute dependency. A package will
4623 not be configured unless all of the packages listed in
4624 its <tt>Depends</tt> field have been correctly
4629 The <tt>Depends</tt> field should be used if the
4630 depended-on package is required for the depending
4631 package to provide a significant amount of
4636 The <tt>Depends</tt> field should also be used if the
4637 <prgn>postinst</prgn>, <prgn>prerm</prgn> or
4638 <prgn>postrm</prgn> scripts require the package to be
4639 present in order to run. Note, however, that the
4640 <prgn>postrm</prgn> cannot rely on any non-essential
4641 packages to be present during the <tt>purge</tt>
4645 <tag><tt>Recommends</tt></tag>
4648 This declares a strong, but not absolute, dependency.
4652 The <tt>Recommends</tt> field should list packages
4653 that would be found together with this one in all but
4654 unusual installations.
4658 <tag><tt>Suggests</tt></tag>
4660 This is used to declare that one package may be more
4661 useful with one or more others. Using this field
4662 tells the packaging system and the user that the
4663 listed packages are related to this one and can
4664 perhaps enhance its usefulness, but that installing
4665 this one without them is perfectly reasonable.
4668 <tag><tt>Enhances</tt></tag>
4670 This field is similar to Suggests but works in the
4671 opposite direction. It is used to declare that a
4672 package can enhance the functionality of another
4676 <tag><tt>Pre-Depends</tt></tag>
4679 This field is like <tt>Depends</tt>, except that it
4680 also forces <prgn>dpkg</prgn> to complete installation
4681 of the packages named before even starting the
4682 installation of the package which declares the
4683 pre-dependency, as follows:
4687 When a package declaring a pre-dependency is about to
4688 be <em>unpacked</em> the pre-dependency can be
4689 satisfied if the depended-on package is either fully
4690 configured, <em>or even if</em> the depended-on
4691 package(s) are only unpacked or in the "Half-Configured"
4692 state, provided that they have been configured
4693 correctly at some point in the past (and not removed
4694 or partially removed since). In this case, both the
4695 previously-configured and currently unpacked or
4696 "Half-Configured" versions must satisfy any version
4697 clause in the <tt>Pre-Depends</tt> field.
4701 When the package declaring a pre-dependency is about
4702 to be <em>configured</em>, the pre-dependency will be
4703 treated as a normal <tt>Depends</tt>, that is, it will
4704 be considered satisfied only if the depended-on
4705 package has been correctly configured.
4709 <tt>Pre-Depends</tt> should be used sparingly,
4710 preferably only by packages whose premature upgrade or
4711 installation would hamper the ability of the system to
4712 continue with any upgrade that might be in progress.
4716 <tt>Pre-Depends</tt> are also required if the
4717 <prgn>preinst</prgn> script depends on the named
4718 package. It is best to avoid this situation if
4726 When selecting which level of dependency to use you should
4727 consider how important the depended-on package is to the
4728 functionality of the one declaring the dependency. Some
4729 packages are composed of components of varying degrees of
4730 importance. Such a package should list using
4731 <tt>Depends</tt> the package(s) which are required by the
4732 more important components. The other components'
4733 requirements may be mentioned as Suggestions or
4734 Recommendations, as appropriate to the components' relative
4740 <heading>Packages which break other packages - <tt>Breaks</tt></heading>
4743 When one binary package declares that it breaks another,
4744 <prgn>dpkg</prgn> will refuse to allow the package which
4745 declares <tt>Breaks</tt> be installed unless the broken
4746 package is deconfigured first, and it will refuse to
4747 allow the broken package to be reconfigured.
4751 A package will not be regarded as causing breakage merely
4752 because its configuration files are still installed; it must
4753 be at least "Half-Installed".
4757 A special exception is made for packages which declare that
4758 they break their own package name or a virtual package which
4759 they provide (see below): this does not count as a real
4764 Normally a <tt>Breaks</tt> entry will have an "earlier than"
4765 version clause; such a <tt>Breaks</tt> is introduced in the
4766 version of an (implicit or explicit) dependency which violates
4767 an assumption or reveals a bug in earlier versions of the broken
4768 package, or which takes over a file from earlier versions of the
4769 package named in <tt>Breaks</tt>. This use of <tt>Breaks</tt>
4770 will inform higher-level package management tools that the
4771 broken package must be upgraded before the new one.
4775 If the breaking package also overwrites some files from the
4776 older package, it should use <tt>Replaces</tt> to ensure this
4777 goes smoothly. See <ref id="replaces"> for a full discussion
4778 of taking over files from other packages, including how to
4779 use <tt>Breaks</tt> in those cases.
4783 Many of the cases where <tt>Breaks</tt> should be used were
4784 previously handled with <tt>Conflicts</tt>
4785 because <tt>Breaks</tt> did not yet exist.
4786 Many <tt>Conflicts</tt> fields should now be <tt>Breaks</tt>.
4787 See <ref id="conflicts"> for more information about the
4792 <sect id="conflicts">
4793 <heading>Conflicting binary packages - <tt>Conflicts</tt></heading>
4796 When one binary package declares a conflict with another
4797 using a <tt>Conflicts</tt> field, <prgn>dpkg</prgn> will
4798 refuse to allow them to be installed on the system at the
4799 same time. This is a stronger restriction than <tt>Breaks</tt>,
4800 which just prevents both packages from being configured at the
4801 same time. Conflicting packages cannot be unpacked on the
4802 system at the same time.
4806 If one package is to be installed, the other must be removed
4807 first. If the package being installed is marked as replacing
4808 (see <ref id="replaces">, but note that <tt>Breaks</tt> should
4809 normally be used in this case) the one on the system, or the one
4810 on the system is marked as deselected, or both packages are
4811 marked <tt>Essential</tt>, then <prgn>dpkg</prgn> will
4812 automatically remove the package which is causing the conflict.
4813 Otherwise, it will halt the installation of the new package with
4814 an error. This mechanism is specifically designed to produce an
4815 error when the installed package is <tt>Essential</tt>, but the
4820 A package will not cause a conflict merely because its
4821 configuration files are still installed; it must be at least
4826 A special exception is made for packages which declare a
4827 conflict with their own package name, or with a virtual
4828 package which they provide (see below): this does not
4829 prevent their installation, and allows a package to conflict
4830 with others providing a replacement for it. You use this
4831 feature when you want the package in question to be the only
4832 package providing some feature.
4836 Normally, <tt>Breaks</tt> should be used instead
4837 of <tt>Conflicts</tt> since <tt>Conflicts</tt> imposes a
4838 stronger restriction on the ordering of package installation or
4839 upgrade and can make it more difficult for the package manager
4840 to find a correct solution to an upgrade or installation
4841 problem. <tt>Breaks</tt> should be used
4843 <item>when moving a file from one package to another (see
4844 <ref id="replaces">),</item>
4845 <item>when splitting a package (a special case of the previous
4847 <item>when the breaking package exposes a bug in or interacts
4848 badly with particular versions of the broken
4851 <tt>Conflicts</tt> should be used
4853 <item>when two packages provide the same file and will
4854 continue to do so,</item>
4855 <item>in conjunction with <tt>Provides</tt> when only one
4856 package providing a given virtual facility may be installed
4857 at a time (see <ref id="virtual">),</item>
4858 <item>in other cases where one must prevent simultaneous
4859 installation of two packages for reasons that are ongoing
4860 (not fixed in a later version of one of the packages) or
4861 that must prevent both packages from being unpacked at the
4862 same time, not just configured.</item>
4864 Be aware that adding <tt>Conflicts</tt> is normally not the best
4865 solution when two packages provide the same files. Depending on
4866 the reason for that conflict, using alternatives or renaming the
4867 files is often a better approach. See, for
4868 example, <ref id="binaries">.
4872 Neither <tt>Breaks</tt> nor <tt>Conflicts</tt> should be used
4873 unless two packages cannot be installed at the same time or
4874 installing them both causes one of them to be broken or
4875 unusable. Having similar functionality or performing the same
4876 tasks as another package is not sufficient reason to
4877 declare <tt>Breaks</tt> or <tt>Conflicts</tt> with that package.
4881 A <tt>Conflicts</tt> entry may have an "earlier than" version
4882 clause if the reason for the conflict is corrected in a later
4883 version of one of the packages. However, normally the presence
4884 of an "earlier than" version clause is a sign
4885 that <tt>Breaks</tt> should have been used instead. An "earlier
4886 than" version clause in <tt>Conflicts</tt>
4887 prevents <prgn>dpkg</prgn> from upgrading or installing the
4888 package which declares such a conflict until the upgrade or
4889 removal of the conflicted-with package has been completed, which
4890 is a strong restriction.
4894 <sect id="virtual"><heading>Virtual packages - <tt>Provides</tt>
4898 As well as the names of actual ("concrete") packages, the
4899 package relationship fields <tt>Depends</tt>,
4900 <tt>Recommends</tt>, <tt>Suggests</tt>, <tt>Enhances</tt>,
4901 <tt>Pre-Depends</tt>, <tt>Breaks</tt>, <tt>Conflicts</tt>,
4902 <tt>Build-Depends</tt>, <tt>Build-Depends-Indep</tt>,
4903 <tt>Build-Conflicts</tt> and <tt>Build-Conflicts-Indep</tt>
4904 may mention "virtual packages".
4908 A <em>virtual package</em> is one which appears in the
4909 <tt>Provides</tt> control field of another package. The effect
4910 is as if the package(s) which provide a particular virtual
4911 package name had been listed by name everywhere the virtual
4912 package name appears. (See also <ref id="virtual_pkg">)
4916 If there are both concrete and virtual packages of the same
4917 name, then the dependency may be satisfied (or the conflict
4918 caused) by either the concrete package with the name in
4919 question or any other concrete package which provides the
4920 virtual package with the name in question. This is so that,
4921 for example, supposing we have
4922 <example compact="compact">
4925 </example> and someone else releases an enhanced version of
4926 the <tt>bar</tt> package they can say:
4927 <example compact="compact">
4931 and the <tt>bar-plus</tt> package will now also satisfy the
4932 dependency for the <tt>foo</tt> package.
4936 If a relationship field has a version number attached, only real
4937 packages will be considered to see whether the relationship is
4938 satisfied (or the prohibition violated, for a conflict or
4939 breakage). In other words, if a version number is specified,
4940 this is a request to ignore all <tt>Provides</tt> for that
4941 package name and consider only real packages. The package
4942 manager will assume that a package providing that virtual
4943 package is not of the "right" version. A <tt>Provides</tt>
4944 field may not contain version numbers, and the version number of
4945 the concrete package which provides a particular virtual package
4946 will not be considered when considering a dependency on or
4947 conflict with the virtual package name.<footnote>
4948 It is possible that a future release of <prgn>dpkg</prgn> may
4949 add the ability to specify a version number for each virtual
4950 package it provides. This feature is not yet present,
4951 however, and is expected to be used only infrequently.
4956 To specify which of a set of real packages should be the default
4957 to satisfy a particular dependency on a virtual package, list
4958 the real package as an alternative before the virtual one.
4962 If the virtual package represents a facility that can only be
4963 provided by one real package at a time, such as
4964 the <package>mail-transport-agent</package> virtual package that
4965 requires installation of a binary that would conflict with all
4966 other providers of that virtual package (see
4967 <ref id="mail-transport-agents">), all packages providing that
4968 virtual package should also declare a conflict with it
4969 using <tt>Conflicts</tt>. This will ensure that at most one
4970 provider of that virtual package is unpacked or installed at a
4975 <sect id="replaces"><heading>Overwriting files and replacing
4976 packages - <tt>Replaces</tt></heading>
4979 Packages can declare in their control file that they should
4980 overwrite files in certain other packages, or completely replace
4981 other packages. The <tt>Replaces</tt> control field has these
4982 two distinct purposes.
4985 <sect1><heading>Overwriting files in other packages</heading>
4988 It is usually an error for a package to contain files which
4989 are on the system in another package. However, if the
4990 overwriting package declares that it <tt>Replaces</tt> the one
4991 containing the file being overwritten, then <prgn>dpkg</prgn>
4992 will replace the file from the old package with that from the
4993 new. The file will no longer be listed as "owned" by the old
4994 package and will be taken over by the new package.
4995 Normally, <tt>Breaks</tt> should be used in conjunction
4996 with <tt>Replaces</tt>.<footnote>
4997 To see why <tt>Breaks</tt> is normally needed in addition
4998 to <tt>Replaces</tt>, consider the case of a file in the
4999 package <package>foo</package> being taken over by the
5000 package <package>foo-data</package>.
5001 <tt>Replaces</tt> will allow <package>foo-data</package> to
5002 be installed and take over that file. However,
5003 without <tt>Breaks</tt>, nothing
5004 requires <package>foo</package> to be upgraded to a newer
5005 version that knows it does not include that file and instead
5006 depends on <package>foo-data</package>. Nothing would
5007 prevent the new <package>foo-data</package> package from
5008 being installed and then removed, removing the file that it
5009 took over from <package>foo</package>. After that
5010 operation, the package manager would think the system was in
5011 a consistent state, but the <package>foo</package> package
5012 would be missing one of its files.
5017 For example, if a package <package>foo</package> is split
5018 into <package>foo</package> and <package>foo-data</package>
5019 starting at version 1.2-3, <package>foo-data</package> would
5021 <example compact="compact">
5022 Replaces: foo (<< 1.2-3)
5023 Breaks: foo (<< 1.2-3)
5025 in its control file. The new version of the
5026 package <package>foo</package> would normally have the field
5027 <example compact="compact">
5028 Depends: foo-data (>= 1.2-3)
5030 (or possibly <tt>Recommends</tt> or even <tt>Suggests</tt> if
5031 the files moved into <package>foo-data</package> are not
5032 required for normal operation).
5036 If a package is completely replaced in this way, so that
5037 <prgn>dpkg</prgn> does not know of any files it still
5038 contains, it is considered to have "disappeared". It will
5039 be marked as not wanted on the system (selected for
5040 removal) and not installed. Any <tt>conffile</tt>s
5041 details noted for the package will be ignored, as they
5042 will have been taken over by the overwriting package. The
5043 package's <prgn>postrm</prgn> script will be run with a
5044 special argument to allow the package to do any final
5045 cleanup required. See <ref id="mscriptsinstact">.
5047 Replaces is a one way relationship. You have to install
5048 the replacing package after the replaced package.
5053 For this usage of <tt>Replaces</tt>, virtual packages (see
5054 <ref id="virtual">) are not considered when looking at a
5055 <tt>Replaces</tt> field. The packages declared as being
5056 replaced must be mentioned by their real names.
5060 This usage of <tt>Replaces</tt> only takes effect when both
5061 packages are at least partially on the system at once. It is
5062 not relevant if the packages conflict unless the conflict has
5067 <sect1><heading>Replacing whole packages, forcing their
5071 Second, <tt>Replaces</tt> allows the packaging system to
5072 resolve which package should be removed when there is a
5073 conflict (see <ref id="conflicts">). This usage only takes
5074 effect when the two packages <em>do</em> conflict, so that the
5075 two usages of this field do not interfere with each other.
5079 In this situation, the package declared as being replaced
5080 can be a virtual package, so for example, all mail
5081 transport agents (MTAs) would have the following fields in
5082 their control files:
5083 <example compact="compact">
5084 Provides: mail-transport-agent
5085 Conflicts: mail-transport-agent
5086 Replaces: mail-transport-agent
5088 ensuring that only one MTA can be installed at any one
5089 time. See <ref id="virtual"> for more information about this
5094 <sect id="sourcebinarydeps">
5095 <heading>Relationships between source and binary packages -
5096 <tt>Build-Depends</tt>, <tt>Build-Depends-Indep</tt>,
5097 <tt>Build-Conflicts</tt>, <tt>Build-Conflicts-Indep</tt>
5101 Source packages that require certain binary packages to be
5102 installed or absent at the time of building the package
5103 can declare relationships to those binary packages.
5107 This is done using the <tt>Build-Depends</tt>,
5108 <tt>Build-Depends-Indep</tt>, <tt>Build-Conflicts</tt> and
5109 <tt>Build-Conflicts-Indep</tt> control fields.
5113 Build-dependencies on "build-essential" binary packages can be
5114 omitted. Please see <ref id="pkg-relations"> for more information.
5118 The dependencies and conflicts they define must be satisfied
5119 (as defined earlier for binary packages) in order to invoke
5120 the targets in <tt>debian/rules</tt>, as follows:<footnote>
5122 There is no Build-Depends-Arch; this role is essentially
5123 met with Build-Depends. Anyone building the
5124 <tt>build-indep</tt> and <tt>binary-indep</tt> targets is
5125 assumed to be building the whole package, and therefore
5126 installation of all build dependencies is required.
5129 The autobuilders use <tt>dpkg-buildpackage -B</tt>, which
5130 calls <tt>build</tt>, not <tt>build-arch</tt> since it does
5131 not yet know how to check for its existence, and
5132 <tt>binary-arch</tt>. The purpose of the original split
5133 between <tt>Build-Depends</tt> and
5134 <tt>Build-Depends-Indep</tt> was so that the autobuilders
5135 wouldn't need to install extra packages needed only for the
5136 binary-indep targets. But without a build-arch/build-indep
5137 split, this didn't work, since most of the work is done in
5138 the build target, not in the binary target.
5142 <tag><tt>clean</tt>, <tt>build-arch</tt>, and
5143 <tt>binary-arch</tt></tag>
5145 Only the <tt>Build-Depends</tt> and <tt>Build-Conflicts</tt>
5146 fields must be satisfied when these targets are invoked.
5148 <tag><tt>build</tt>, <tt>build-indep</tt>, <tt>binary</tt>,
5149 and <tt>binary-indep</tt></tag>
5151 The <tt>Build-Depends</tt>, <tt>Build-Conflicts</tt>,
5152 <tt>Build-Depends-Indep</tt>, and
5153 <tt>Build-Conflicts-Indep</tt> fields must be satisfied when
5154 these targets are invoked.
5162 <chapt id="sharedlibs"><heading>Shared libraries</heading>
5165 Packages containing shared libraries must be constructed with
5166 a little care to make sure that the shared library is always
5167 available. This is especially important for packages whose
5168 shared libraries are vitally important, such as the C library
5169 (currently <tt>libc6</tt>).
5173 This section deals only with public shared libraries: shared
5174 libraries that are placed in directories searched by the dynamic
5175 linker by default or which are intended to be linked against
5176 normally and possibly used by other, independent packages. Shared
5177 libraries that are internal to a particular package or that are
5178 only loaded as dynamic modules are not covered by this section and
5179 are not subject to its requirements.
5183 A shared library is identified by the <tt>SONAME</tt> attribute
5184 stored in its dynamic section. When a binary is linked against a
5185 shared library, the <tt>SONAME</tt> of the shared library is
5186 recorded in the binary's <tt>NEEDED</tt> section so that the
5187 dynamic linker knows that library must be loaded at runtime. The
5188 shared library file's full name (which usually contains additional
5189 version information not needed in the <tt>SONAME</tt>) is
5190 therefore normally not referenced directly. Instead, the shared
5191 library is loaded by its <tt>SONAME</tt>, which exists on the file
5192 system as a symlink pointing to the full name of the shared
5193 library. This symlink must be provided by the
5194 package. <ref id="sharedlibs-runtime"> describes how to do this.
5196 This is a convention of shared library versioning, but not a
5197 requirement. Some libraries use the <tt>SONAME</tt> as the full
5198 library file name instead and therefore do not need a symlink.
5199 Most, however, encode additional information about
5200 backwards-compatible revisions as a minor version number in the
5201 file name. The <tt>SONAME</tt> itself only changes when
5202 binaries linked with the earlier version of the shared library
5203 may no longer work, but the filename may change with each
5204 release of the library. See <ref id="sharedlibs-runtime"> for
5210 When linking a binary or another shared library against a shared
5211 library, the <tt>SONAME</tt> for that shared library is not yet
5212 known. Instead, the shared library is found by looking for a file
5213 matching the library name with <tt>.so</tt> appended. This file
5214 exists on the file system as a symlink pointing to the shared
5219 Shared libraries are normally split into several binary packages.
5220 The <tt>SONAME</tt> symlink is installed by the runtime shared
5221 library package, and the bare <tt>.so</tt> symlink is installed in
5222 the development package since it's only used when linking binaries
5223 or shared libraries. However, there are some exceptions for
5224 unusual shared libraries or for shared libraries that are also
5225 loaded as dynamic modules by other programs.
5229 This section is primarily concerned with how the separation of
5230 shared libraries into multiple packages should be done and how
5231 dependencies on and between shared library binary packages are
5232 managed in Debian. <ref id="libraries"> should be read in
5233 conjunction with this section and contains additional rules for
5234 the files contained in the shared library packages.
5237 <sect id="sharedlibs-runtime">
5238 <heading>Run-time shared libraries</heading>
5241 The run-time shared library must be placed in a package
5242 whose name changes whenever the <tt>SONAME</tt> of the shared
5243 library changes. This allows several versions of the shared
5244 library to be installed at the same time, allowing installation
5245 of the new version of the shared library without immediately
5246 breaking binaries that depend on the old version. Normally, the
5247 run-time shared library and its <tt>SONAME</tt> symlink should
5248 be placed in a package named
5249 <package><var>libraryname</var><var>soversion</var></package>,
5250 where <var>soversion</var> is the version number in
5251 the <tt>SONAME</tt> of the shared library.
5252 See <ref id="shlibs"> for detailed information on how to
5253 determine this version. Alternatively, if it would be confusing
5254 to directly append <var>soversion</var>
5255 to <var>libraryname</var> (if, for example, <var>libraryname</var>
5256 itself ends in a number), you should use
5257 <package><var>libraryname</var>-<var>soversion</var></package>
5262 If you have several shared libraries built from the same source
5263 tree, you may lump them all together into a single shared
5264 library package provided that all of their <tt>SONAME</tt>s will
5265 always change together. Be aware that this is not normally the
5266 case, and if the <tt>SONAME</tt>s do not change together,
5267 upgrading such a merged shared library package will be
5268 unnecessarily difficult because of file conflicts with the old
5269 version of the package. When in doubt, always split shared
5270 library packages so that each binary package installs a single
5275 Every time the shared library ABI changes in a way that may
5276 break binaries linked against older versions of the shared
5277 library, the <tt>SONAME</tt> of the library and the
5278 corresponding name for the binary package containing the runtime
5279 shared library should change. Normally, this means
5280 the <tt>SONAME</tt> should change any time an interface is
5281 removed from the shared library or the signature of an interface
5282 (the number of parameters or the types of parameters that it
5283 takes, for example) is changed. This practice is vital to
5284 allowing clean upgrades from older versions of the package and
5285 clean transitions between the old ABI and new ABI without having
5286 to upgrade every affected package simultaneously.
5290 The <tt>SONAME</tt> and binary package name need not, and indeed
5291 normally should not, change if new interfaces are added but none
5292 are removed or changed, since this will not break binaries
5293 linked against the old shared library. Correct versioning of
5294 dependencies on the newer shared library by binaries that use
5295 the new interfaces is handled via
5296 the <qref id="sharedlibs-shlibdeps"><tt>shlibs</tt>
5297 system</qref> or via symbols files (see
5298 <manref name="deb-symbols" section="5">).
5302 The package should install the shared libraries under
5303 their normal names. For example, the <package>libgdbm3</package>
5304 package should install <file>libgdbm.so.3.0.0</file> as
5305 <file>/usr/lib/libgdbm.so.3.0.0</file>. The files should not be
5306 renamed or re-linked by any <prgn>prerm</prgn> or
5307 <prgn>postrm</prgn> scripts; <prgn>dpkg</prgn> will take care
5308 of renaming things safely without affecting running programs,
5309 and attempts to interfere with this are likely to lead to
5314 Shared libraries should not be installed executable, since
5315 the dynamic linker does not require this and trying to
5316 execute a shared library usually results in a core dump.
5320 The run-time library package should include the symbolic link for
5321 the <tt>SONAME</tt> that <prgn>ldconfig</prgn> would create for
5322 the shared libraries. For example,
5323 the <package>libgdbm3</package> package should include a symbolic
5324 link from <file>/usr/lib/libgdbm.so.3</file> to
5325 <file>libgdbm.so.3.0.0</file>. This is needed so that the dynamic
5326 linker (for example <prgn>ld.so</prgn> or
5327 <prgn>ld-linux.so.*</prgn>) can find the library between the
5328 time that <prgn>dpkg</prgn> installs it and the time that
5329 <prgn>ldconfig</prgn> is run in the <prgn>postinst</prgn>
5331 The package management system requires the library to be
5332 placed before the symbolic link pointing to it in the
5333 <file>.deb</file> file. This is so that when
5334 <prgn>dpkg</prgn> comes to install the symlink
5335 (overwriting the previous symlink pointing at an older
5336 version of the library), the new shared library is already
5337 in place. In the past, this was achieved by creating the
5338 library in the temporary packaging directory before
5339 creating the symlink. Unfortunately, this was not always
5340 effective, since the building of the tar file in the
5341 <file>.deb</file> depended on the behavior of the underlying
5342 file system. Some file systems (such as reiserfs) reorder
5343 the files so that the order of creation is forgotten.
5344 Since version 1.7.0, <prgn>dpkg</prgn>
5345 reorders the files itself as necessary when building a
5346 package. Thus it is no longer important to concern
5347 oneself with the order of file creation.
5351 <sect1 id="ldconfig">
5352 <heading><tt>ldconfig</tt></heading>
5355 Any package installing shared libraries in one of the default
5356 library directories of the dynamic linker (which are currently
5357 <file>/usr/lib</file> and <file>/lib</file>) or a directory that is
5358 listed in <file>/etc/ld.so.conf</file><footnote>
5360 <list compact="compact">
5361 <item>/usr/local/lib</item>
5362 <item>/usr/lib/libc5-compat</item>
5363 <item>/lib/libc5-compat</item>
5366 must use <prgn>ldconfig</prgn> to update the shared library
5371 The package maintainer scripts must only call
5372 <prgn>ldconfig</prgn> under these circumstances:
5373 <list compact="compact">
5374 <item>When the <prgn>postinst</prgn> script is run with a
5375 first argument of <tt>configure</tt>, the script must call
5376 <prgn>ldconfig</prgn>, and may optionally invoke
5377 <prgn>ldconfig</prgn> at other times.
5379 <item>When the <prgn>postrm</prgn> script is run with a
5380 first argument of <tt>remove</tt>, the script should call
5381 <prgn>ldconfig</prgn>.
5386 During install or upgrade, the preinst is called before
5387 the new files are installed, so calling "ldconfig" is
5388 pointless. The preinst of an existing package can also be
5389 called if an upgrade fails. However, this happens during
5390 the critical time when a shared libs may exist on-disk
5391 under a temporary name. Thus, it is dangerous and
5392 forbidden by current policy to call "ldconfig" at this
5397 When a package is installed or upgraded, "postinst
5398 configure" runs after the new files are safely on-disk.
5399 Since it is perfectly safe to invoke ldconfig
5400 unconditionally in a postinst, it is OK for a package to
5401 simply put ldconfig in its postinst without checking the
5402 argument. The postinst can also be called to recover from
5403 a failed upgrade. This happens before any new files are
5404 unpacked, so there is no reason to call "ldconfig" at this
5409 For a package that is being removed, prerm is
5410 called with all the files intact, so calling ldconfig is
5411 useless. The other calls to "prerm" happen in the case of
5412 upgrade at a time when all the files of the old package
5413 are on-disk, so again calling "ldconfig" is pointless.
5417 postrm, on the other hand, is called with the "remove"
5418 argument just after the files are removed, so this is
5419 the proper time to call "ldconfig" to notify the system
5420 of the fact that the shared libraries from the package
5421 are removed. The postrm can be called at several other
5422 times. At the time of "postrm purge", "postrm
5423 abort-install", or "postrm abort-upgrade", calling
5424 "ldconfig" is useless because the shared lib files are
5425 not on-disk. However, when "postrm" is invoked with
5426 arguments "upgrade", "failed-upgrade", or "disappear", a
5427 shared lib may exist on-disk under a temporary filename.
5435 <sect id="sharedlibs-support-files">
5436 <heading>Shared library support files</heading>
5439 If your package contains files whose names do not change with
5440 each change in the library shared object version, you must not
5441 put them in the shared library package. Otherwise, several
5442 versions of the shared library cannot be installed at the same
5443 time without filename clashes, making upgrades and transitions
5444 unnecessarily difficult.
5448 It is recommended that supporting files and run-time support
5449 programs that do not need to be invoked manually by users, but
5450 are nevertheless required for the package to function, be placed
5451 (if they are binary) in a subdirectory of <file>/usr/lib</file>,
5452 preferably under <file>/usr/lib/</file><var>package-name</var>.
5453 If the program or file is architecture independent, the
5454 recommendation is for it to be placed in a subdirectory of
5455 <file>/usr/share</file> instead, preferably under
5456 <file>/usr/share/</file><var>package-name</var>. Following the
5457 <var>package-name</var> naming convention ensures that the file
5458 names change when the shared object version changes.
5462 Run-time support programs that use the shared library but are
5463 not required for the library to function or files used by the
5464 shared library that can be used by any version of the shared
5465 library package should instead be put in a separate package.
5466 This package might typically be named
5467 <package><var>libraryname</var>-tools</package>; note the
5468 absence of the <var>soversion</var> in the package name.
5472 Files and support programs only useful when compiling software
5473 against the library should be included in the development
5474 package for the library.<footnote>
5475 For example, a <file><var>package-name</var>-config</file>
5476 script or <package>pkg-config</package> configuration files.
5481 <sect id="sharedlibs-static">
5482 <heading>Static libraries</heading>
5485 The static library (<file><var>libraryname.a</var></file>)
5486 is usually provided in addition to the shared version.
5487 It is placed into the development package (see below).
5491 In some cases, it is acceptable for a library to be
5492 available in static form only; these cases include:
5494 <item>libraries for languages whose shared library support
5495 is immature or unstable</item>
5496 <item>libraries whose interfaces are in flux or under
5497 development (commonly the case when the library's
5498 major version number is zero, or where the ABI breaks
5499 across patchlevels)</item>
5500 <item>libraries which are explicitly intended to be
5501 available only in static form by their upstream
5506 <sect id="sharedlibs-dev">
5507 <heading>Development files</heading>
5510 If there are development files associated with a shared library,
5511 the source package needs to generate a binary development package
5512 named <package><var>libraryname</var><var>soversion</var>-dev</package>,
5513 or if you prefer only to support one development version at a
5514 time, <package><var>libraryname</var>-dev</package>. Installing
5515 the development package must result in installation of all the
5516 development files necessary for compiling programs against that
5517 shared library.<footnote>
5518 This wording allows the development files to be split into
5519 several packages, such as a separate architecture-independent
5520 <package><var>libraryname</var>-headers</package>, provided that
5521 the development package depends on all the required additional
5527 In case several development versions of a library exist, you may
5528 need to use <prgn>dpkg</prgn>'s Conflicts mechanism (see
5529 <ref id="conflicts">) to ensure that the user only installs one
5530 development version at a time (as different development versions are
5531 likely to have the same header files in them, which would cause a
5532 filename clash if both were installed).
5536 The development package should contain a symlink for the associated
5537 shared library without a version number. For example, the
5538 <package>libgdbm-dev</package> package should include a symlink
5539 from <file>/usr/lib/libgdbm.so</file> to
5540 <file>libgdbm.so.3.0.0</file>. This symlink is needed by the linker
5541 (<prgn>ld</prgn>) when compiling packages, as it will only look for
5542 <file>libgdbm.so</file> when compiling dynamically.
5546 If the package provides Ada Library Information
5547 (<file>*.ali</file>) files for use with GNAT, these files must be
5548 installed read-only (mode 0444) so that GNAT will not attempt to
5549 recompile them. This overrides the normal file mode requirements
5550 given in <ref id="permissions-owners">.
5554 <sect id="sharedlibs-intradeps">
5555 <heading>Dependencies between the packages of the same library</heading>
5558 Typically the development version should have an exact
5559 version dependency on the runtime library, to make sure that
5560 compilation and linking happens correctly. The
5561 <tt>${binary:Version}</tt> substitution variable can be
5562 useful for this purpose.
5564 Previously, <tt>${Source-Version}</tt> was used, but its name
5565 was confusing and it has been deprecated since dpkg 1.13.19.
5570 <sect id="sharedlibs-shlibdeps">
5571 <heading>Dependencies between the library and other packages -
5572 the <tt>shlibs</tt> system</heading>
5575 If a package contains a binary or library which links to a
5576 shared library, we must ensure that when the package is
5577 installed on the system, all of the libraries needed are
5578 also installed. This requirement led to the creation of the
5579 <tt>shlibs</tt> system, which is very simple in its design:
5580 any package which <em>provides</em> a shared library also
5581 provides information on the package dependencies required to
5582 ensure the presence of this library, and any package which
5583 <em>uses</em> a shared library uses this information to
5584 determine the dependencies it requires. The files which
5585 contain the mapping from shared libraries to the necessary
5586 dependency information are called <file>shlibs</file> files.
5590 When a package is built which contains any shared libraries, it
5591 must provide a <file>shlibs</file> file for other packages to
5592 use. When a package is built which contains any shared
5593 libraries or compiled binaries, it must run
5594 <qref id="pkg-dpkg-shlibdeps"><prgn>dpkg-shlibdeps</prgn></qref>
5595 on these to determine the libraries used and hence the
5596 dependencies needed by this package.<footnote>
5598 <prgn>dpkg-shlibdeps</prgn> will use a program
5599 like <prgn>objdump</prgn> or <prgn>readelf</prgn> to find
5600 the libraries directly needed by the binaries or shared
5601 libraries in the package.
5605 We say that a binary <tt>foo</tt> <em>directly</em> uses
5606 a library <tt>libbar</tt> if it is explicitly linked
5607 with that library (that is, the library is listed in the ELF
5608 <tt>NEEDED</tt> attribute, caused by adding <tt>-lbar</tt>
5609 to the link line when the binary is created). Other
5610 libraries that are needed by <tt>libbar</tt> are linked
5611 <em>indirectly</em> to <tt>foo</tt>, and the dynamic
5612 linker will load them automatically when it loads
5613 <tt>libbar</tt>. A package should depend on the libraries
5614 it directly uses, but not the libraries it indirectly uses.
5615 The dependencies for those libraries will automatically pull
5616 in the other libraries.
5620 A good example of where this helps is the following. We
5621 could update <tt>libimlib</tt> with a new version that
5622 supports a new graphics format called dgf (but retaining the
5623 same major version number) and depends on <tt>libdgf</tt>.
5624 If we used <prgn>ldd</prgn> to add dependencies for every
5625 library directly or indirectly linked with a binary, every
5626 package that uses <tt>libimlib</tt> would need to be
5627 recompiled so it would also depend on <tt>libdgf</tt> or it
5628 wouldn't run due to missing symbols. Since dependencies are
5629 only added based on ELF <tt>NEEDED</tt> attribute, packages
5630 using <tt>libimlib</tt> can rely on <tt>libimlib</tt> itself
5631 having the dependency on <tt>libdgf</tt> and so they would
5632 not need rebuilding.
5638 In the following sections, we will first describe where the
5639 various <tt>shlibs</tt> files are to be found, then how to
5640 use <prgn>dpkg-shlibdeps</prgn>, and finally the <tt>shlibs</tt>
5641 file format and how to create them if your package contains a
5646 <heading>The <tt>shlibs</tt> files present on the system</heading>
5649 There are several places where <tt>shlibs</tt> files are
5650 found. The following list gives them in the order in which
5652 <qref id="pkg-dpkg-shlibdeps"><prgn>dpkg-shlibdeps</prgn></qref>.
5653 (The first one which gives the required information is used.)
5659 <p><file>debian/shlibs.local</file></p>
5662 This lists overrides for this package. This file should
5663 normally not be used, but may be needed temporarily in
5664 unusual situations to work around bugs in other packages,
5665 or in unusual cases where the normally declared dependency
5666 information in the installed <file>shlibs</file> file for
5667 a library cannot be used. This file overrides information
5668 obtained from any other source.
5673 <p><file>/etc/dpkg/shlibs.override</file></p>
5676 This lists global overrides. This list is normally
5677 empty. It is maintained by the local system
5683 <p><file>DEBIAN/shlibs</file> files in the "build directory"</p>
5686 When packages are being built,
5687 any <file>debian/shlibs</file> files are copied into the
5688 control information file area of the temporary build
5689 directory and given the name <file>shlibs</file>. These
5690 files give details of any shared libraries included in the
5691 same package.<footnote>
5692 An example may help here. Let us say that the source
5693 package <tt>foo</tt> generates two binary
5694 packages, <tt>libfoo2</tt> and <tt>foo-runtime</tt>.
5695 When building the binary packages, the two packages are
5696 created in the directories <file>debian/libfoo2</file>
5697 and <file>debian/foo-runtime</file> respectively.
5698 (<file>debian/tmp</file> could be used instead of one of
5699 these.) Since <tt>libfoo2</tt> provides the
5700 <tt>libfoo</tt> shared library, it will require a
5701 <tt>shlibs</tt> file, which will be installed in
5702 <file>debian/libfoo2/DEBIAN/shlibs</file>, eventually to
5703 become <file>/var/lib/dpkg/info/libfoo2.shlibs</file>.
5704 When <prgn>dpkg-shlibdeps</prgn> is run on the
5705 executable <file>debian/foo-runtime/usr/bin/foo-prog</file>,
5707 the <file>debian/libfoo2/DEBIAN/shlibs</file> file to
5708 determine whether <tt>foo-prog</tt>'s library
5709 dependencies are satisfied by any of the libraries
5710 provided by <tt>libfoo2</tt>. For this reason,
5711 <prgn>dpkg-shlibdeps</prgn> must only be run once all of
5712 the individual binary packages' <tt>shlibs</tt> files
5713 have been installed into the build directory.
5719 <p><file>/var/lib/dpkg/info/*.shlibs</file></p>
5722 These are the <file>shlibs</file> files corresponding to
5723 all of the packages installed on the system, and are
5724 maintained by the relevant package maintainers.
5729 <p><file>/etc/dpkg/shlibs.default</file></p>
5732 This file lists any shared libraries whose packages
5733 have failed to provide correct <file>shlibs</file> files.
5734 It was used when the <file>shlibs</file> setup was first
5735 introduced, but it is now normally empty. It is
5736 maintained by the <tt>dpkg</tt> maintainer.
5744 <heading>How to use <prgn>dpkg-shlibdeps</prgn> and the
5745 <file>shlibs</file> files</heading>
5749 <qref id="pkg-dpkg-shlibdeps"><prgn>dpkg-shlibdeps</prgn></qref>
5750 into your <file>debian/rules</file> file. If your package
5751 contains only compiled binaries and libraries (but no scripts),
5752 you can use a command such as:
5753 <example compact="compact">
5754 dpkg-shlibdeps debian/tmp/usr/bin/* debian/tmp/usr/sbin/* \
5755 debian/tmp/usr/lib/*
5757 Otherwise, you will need to explicitly list the compiled
5758 binaries and libraries.<footnote>
5759 If you are using <tt>debhelper</tt>, the
5760 <prgn>dh_shlibdeps</prgn> program will do this work for you.
5761 It will also correctly handle multi-binary packages.
5766 This command puts the dependency information into the
5767 <file>debian/substvars</file> file, which is then used by
5768 <prgn>dpkg-gencontrol</prgn>. You will need to place a
5769 <tt>${shlibs:Depends}</tt> variable in the <tt>Depends</tt>
5770 field in the control file for this to work.
5774 If you have multiple binary packages, you will need to call
5775 <prgn>dpkg-shlibdeps</prgn> on each one which contains
5776 compiled libraries or binaries. In such a case, you will
5777 need to use the <tt>-T</tt> option to the <tt>dpkg</tt>
5778 utilities to specify a different <file>substvars</file> file.
5782 If you are creating a udeb for use in the Debian Installer,
5783 you will need to specify that <prgn>dpkg-shlibdeps</prgn>
5784 should use the dependency line of type <tt>udeb</tt> by
5785 adding the <tt>-tudeb</tt> option<footnote>
5786 <prgn>dh_shlibdeps</prgn> from the <tt>debhelper</tt> suite
5787 will automatically add this option if it knows it is
5789 </footnote>. If there is no dependency line of
5790 type <tt>udeb</tt> in the <file>shlibs</file>
5791 file, <prgn>dpkg-shlibdeps</prgn> will fall back to the regular
5796 For more details on <prgn>dpkg-shlibdeps</prgn>, please see
5797 <ref id="pkg-dpkg-shlibdeps"> and
5798 <manref name="dpkg-shlibdeps" section="1">.
5803 <heading>The <file>shlibs</file> File Format</heading>
5806 Each <file>shlibs</file> file has the same format. Lines
5807 beginning with <tt>#</tt> are considered to be comments and
5808 are ignored. Each line is of the form:
5809 <example compact="compact">
5810 [<var>type</var>: ]<var>library-name</var> <var>soname-version</var> <var>dependencies ...</var>
5815 We will explain this by reference to the example of the
5816 <tt>zlib1g</tt> package, which (at the time of writing)
5817 installs the shared library <file>/usr/lib/libz.so.1.1.3</file>.
5821 <var>type</var> is an optional element that indicates the type
5822 of package for which the line is valid. The only type currently
5823 in use is <tt>udeb</tt>. The colon and space after the type are
5828 <var>library-name</var> is the name of the shared library,
5829 in this case <tt>libz</tt>. (This must match the name part
5830 of the soname, see below.)
5834 <var>soname-version</var> is the version part of the soname of
5835 the library. The soname is the thing that must exactly match
5836 for the library to be recognized by the dynamic linker, and is
5838 <tt><var>name</var>.so.<var>major-version</var></tt>, in our
5839 example, <tt>libz.so.1</tt>.<footnote>
5840 This can be determined using the command
5841 <example compact="compact">
5842 objdump -p /usr/lib/libz.so.1.1.3 | grep SONAME
5845 The version part is the part which comes after
5846 <tt>.so.</tt>, so in our case, it is <tt>1</tt>. The soname may
5847 instead be of the form
5848 <tt><var>name</var>-<var>major-version</var>.so</tt>, such
5849 as <tt>libdb-4.8.so</tt>, in which case the name would
5850 be <tt>libdb</tt> and the version would be <tt>4.8</tt>.
5854 <var>dependencies</var> has the same syntax as a dependency
5855 field in a binary package control file. It should give
5856 details of which packages are required to satisfy a binary
5857 built against the version of the library contained in the
5858 package. See <ref id="depsyntax"> for details.
5862 In our example, if the first version of the <tt>zlib1g</tt>
5863 package which contained a minor number of at least
5864 <tt>1.3</tt> was <var>1:1.1.3-1</var>, then the
5865 <tt>shlibs</tt> entry for this library could say:
5866 <example compact="compact">
5867 libz 1 zlib1g (>= 1:1.1.3)
5869 The version-specific dependency is to avoid warnings from
5870 the dynamic linker about using older shared libraries with
5875 As zlib1g also provides a udeb containing the shared library,
5876 there would also be a second line:
5877 <example compact="compact">
5878 udeb: libz 1 zlib1g-udeb (>= 1:1.1.3)
5884 <heading>Providing a <file>shlibs</file> file</heading>
5887 If your package provides a shared library, you need to create
5888 a <file>shlibs</file> file following the format described above.
5889 It is usual to call this file <file>debian/shlibs</file> (but if
5890 you have multiple binary packages, you might want to call it
5891 <file>debian/shlibs.<var>package</var></file> instead). Then
5892 let <file>debian/rules</file> install it in the control
5893 information file area:
5894 <example compact="compact">
5895 install -m644 debian/shlibs debian/tmp/DEBIAN
5897 or, in the case of a multi-binary package:
5898 <example compact="compact">
5899 install -m644 debian/shlibs.<var>package</var> debian/<var>package</var>/DEBIAN/shlibs
5901 An alternative way of doing this is to create the
5902 <file>shlibs</file> file in the control information file area
5903 directly from <file>debian/rules</file> without using
5904 a <file>debian/shlibs</file> file at all,<footnote>
5905 This is what <prgn>dh_makeshlibs</prgn> in
5906 the <package>debhelper</package> suite does. If your package
5907 also has a udeb that provides a shared
5908 library, <prgn>dh_makeshlibs</prgn> can automatically generate
5909 the <tt>udeb:</tt> lines if you specify the name of the udeb
5910 with the <tt>--add-udeb</tt> option.
5912 since the <file>debian/shlibs</file> file itself is ignored by
5913 <prgn>dpkg-shlibdeps</prgn>.
5917 As <prgn>dpkg-shlibdeps</prgn> reads the
5918 <file>DEBIAN/shlibs</file> files in all of the binary packages
5919 being built from this source package, all of the
5920 <file>DEBIAN/shlibs</file> files should be installed before
5921 <prgn>dpkg-shlibdeps</prgn> is called on any of the binary
5929 <chapt id="opersys"><heading>The Operating System</heading>
5932 <heading>File system hierarchy</heading>
5936 <heading>File System Structure</heading>
5939 The location of all installed files and directories must
5940 comply with the Filesystem Hierarchy Standard (FHS),
5941 version 2.3, with the exceptions noted below, and except
5942 where doing so would violate other terms of Debian
5943 Policy. The following exceptions to the FHS apply:
5948 The optional rules related to user specific
5949 configuration files for applications are stored in
5950 the user's home directory are relaxed. It is
5951 recommended that such files start with the
5952 '<tt>.</tt>' character (a "dot file"), and if an
5953 application needs to create more than one dot file
5954 then the preferred placement is in a subdirectory
5955 with a name starting with a '.' character, (a "dot
5956 directory"). In this case it is recommended the
5957 configuration files not start with the '.'
5963 The requirement for amd64 to use <file>/lib64</file>
5964 for 64 bit binaries is removed.
5969 The requirement for object files, internal binaries, and
5970 libraries, including <file>libc.so.*</file>, to be located
5971 directly under <file>/lib{,32}</file> and
5972 <file>/usr/lib{,32}</file> is amended, permitting files
5973 to instead be installed to
5974 <file>/lib/<var>triplet</var></file> and
5975 <file>/usr/lib/<var>triplet</var></file>, where
5976 <tt><var>triplet</var></tt> is the value returned by
5977 <tt>dpkg-architecture -qDEB_HOST_GNU_TYPE</tt> for the
5978 architecture of the package. Packages may <em>not</em>
5979 install files to any <var>triplet</var> path other
5980 than the one matching the architecture of that package;
5981 for instance, an <tt>Architecture: amd64</tt> package
5982 containing 32-bit x86 libraries may not install these
5983 libraries to <file>/usr/lib/i486-linux-gnu</file>.
5985 This is necessary in order to reserve the directories for
5986 use in cross-installation of library packages from other
5987 architectures, as part of the planned deployment of
5992 Applications may also use a single subdirectory under
5993 <file>/usr/lib/<var>triplet</var></file>.
5996 The execution time linker/loader, ld*, must still be made
5997 available in the existing location under /lib or /lib64
5998 since this is part of the ELF ABI for the architecture.
6003 The requirement that
6004 <file>/usr/local/share/man</file> be "synonymous"
6005 with <file>/usr/local/man</file> is relaxed to a
6010 The requirement that windowmanagers with a single
6011 configuration file call it <file>system.*wmrc</file>
6012 is removed, as is the restriction that the window
6013 manager subdirectory be named identically to the
6014 window manager name itself.
6019 The requirement that boot manager configuration
6020 files live in <file>/etc</file>, or at least are
6021 symlinked there, is relaxed to a recommendation.
6026 The following directories in the root filesystem are
6027 additionally allowed: <file>/sys</file> and
6028 <file>/selinux</file>. <footnote>These directories
6029 are used as mount points to mount virtual filesystems
6030 to get access to kernel information.</footnote>
6037 The version of this document referred here can be
6038 found in the <tt>debian-policy</tt> package or on <url
6039 id="http://www.debian.org/doc/packaging-manuals/fhs/"
6040 name="FHS (Debian copy)"> alongside this manual (or, if
6041 you have the <package>debian-policy</package> installed,
6043 id="file:///usr/share/doc/debian-policy/fhs/" name="FHS
6044 (local copy)">). The
6045 latest version, which may be a more recent version, may
6047 <url id="http://www.pathname.com/fhs/" name="FHS (upstream)">.
6048 Specific questions about following the standard may be
6049 asked on the <tt>debian-devel</tt> mailing list, or
6050 referred to the FHS mailing list (see the
6051 <url id="http://www.pathname.com/fhs/" name="FHS web site"> for
6057 <heading>Site-specific programs</heading>
6060 As mandated by the FHS, packages must not place any
6061 files in <file>/usr/local</file>, either by putting them in
6062 the file system archive to be unpacked by <prgn>dpkg</prgn>
6063 or by manipulating them in their maintainer scripts.
6067 However, the package may create empty directories below
6068 <file>/usr/local</file> so that the system administrator knows
6069 where to place site-specific files. These are not
6070 directories <em>in</em> <file>/usr/local</file>, but are
6071 children of directories in <file>/usr/local</file>. These
6072 directories (<file>/usr/local/*/dir/</file>)
6073 should be removed on package removal if they are
6078 Note that this applies only to
6079 directories <em>below</em> <file>/usr/local</file>,
6080 not <em>in</em> <file>/usr/local</file>. Packages must
6081 not create sub-directories in the
6082 directory <file>/usr/local</file> itself, except those
6083 listed in FHS, section 4.5. However, you may create
6084 directories below them as you wish. You must not remove
6085 any of the directories listed in 4.5, even if you created
6090 Since <file>/usr/local</file> can be mounted read-only from a
6091 remote server, these directories must be created and
6092 removed by the <prgn>postinst</prgn> and <prgn>prerm</prgn>
6093 maintainer scripts and not be included in the
6094 <file>.deb</file> archive. These scripts must not fail if
6095 either of these operations fail.
6099 For example, the <tt>emacsen-common</tt> package could
6100 contain something like
6101 <example compact="compact">
6102 if [ ! -e /usr/local/share/emacs ]
6104 if mkdir /usr/local/share/emacs 2>/dev/null
6106 chown root:staff /usr/local/share/emacs
6107 chmod 2775 /usr/local/share/emacs
6111 in its <prgn>postinst</prgn> script, and
6112 <example compact="compact">
6113 rmdir /usr/local/share/emacs/site-lisp 2>/dev/null || true
6114 rmdir /usr/local/share/emacs 2>/dev/null || true
6116 in the <prgn>prerm</prgn> script. (Note that this form is
6117 used to ensure that if the script is interrupted, the
6118 directory <file>/usr/local/share/emacs</file> will still be
6123 If you do create a directory in <file>/usr/local</file> for
6124 local additions to a package, you should ensure that
6125 settings in <file>/usr/local</file> take precedence over the
6126 equivalents in <file>/usr</file>.
6130 However, because <file>/usr/local</file> and its contents are
6131 for exclusive use of the local administrator, a package
6132 must not rely on the presence or absence of files or
6133 directories in <file>/usr/local</file> for normal operation.
6137 The <file>/usr/local</file> directory itself and all the
6138 subdirectories created by the package should (by default) have
6139 permissions 2775 (group-writable and set-group-id) and be
6140 owned by <tt>root:staff</tt>.
6145 <heading>The system-wide mail directory</heading>
6147 The system-wide mail directory
6148 is <file>/var/mail</file>. This directory is part of the
6149 base system and should not be owned by any particular mail
6150 agents. The use of the old
6151 location <file>/var/spool/mail</file> is deprecated, even
6152 though the spool may still be physically located there.
6158 <heading>Users and groups</heading>
6161 <heading>Introduction</heading>
6163 The Debian system can be configured to use either plain or
6168 Some user ids (UIDs) and group ids (GIDs) are reserved
6169 globally for use by certain packages. Because some
6170 packages need to include files which are owned by these
6171 users or groups, or need the ids compiled into binaries,
6172 these ids must be used on any Debian system only for the
6173 purpose for which they are allocated. This is a serious
6174 restriction, and we should avoid getting in the way of
6175 local administration policies. In particular, many sites
6176 allocate users and/or local system groups starting at 100.
6180 Apart from this we should have dynamically allocated ids,
6181 which should by default be arranged in some sensible
6182 order, but the behavior should be configurable.
6186 Packages other than <tt>base-passwd</tt> must not modify
6187 <file>/etc/passwd</file>, <file>/etc/shadow</file>,
6188 <file>/etc/group</file> or <file>/etc/gshadow</file>.
6193 <heading>UID and GID classes</heading>
6195 The UID and GID numbers are divided into classes as
6201 Globally allocated by the Debian project, the same
6202 on every Debian system. These ids will appear in
6203 the <file>passwd</file> and <file>group</file> files of all
6204 Debian systems, new ids in this range being added
6205 automatically as the <tt>base-passwd</tt> package is
6210 Packages which need a single statically allocated
6211 uid or gid should use one of these; their
6212 maintainers should ask the <tt>base-passwd</tt>
6220 Dynamically allocated system users and groups.
6221 Packages which need a user or group, but can have
6222 this user or group allocated dynamically and
6223 differently on each system, should use <tt>adduser
6224 --system</tt> to create the group and/or user.
6225 <prgn>adduser</prgn> will check for the existence of
6226 the user or group, and if necessary choose an unused
6227 id based on the ranges specified in
6228 <file>adduser.conf</file>.
6232 <tag>1000-59999:</tag>
6235 Dynamically allocated user accounts. By default
6236 <prgn>adduser</prgn> will choose UIDs and GIDs for
6237 user accounts in this range, though
6238 <file>adduser.conf</file> may be used to modify this
6243 <tag>60000-64999:</tag>
6246 Globally allocated by the Debian project, but only
6247 created on demand. The ids are allocated centrally
6248 and statically, but the actual accounts are only
6249 created on users' systems on demand.
6253 These ids are for packages which are obscure or
6254 which require many statically-allocated ids. These
6255 packages should check for and create the accounts in
6256 <file>/etc/passwd</file> or <file>/etc/group</file> (using
6257 <prgn>adduser</prgn> if it has this facility) if
6258 necessary. Packages which are likely to require
6259 further allocations should have a "hole" left after
6260 them in the allocation, to give them room to
6265 <tag>65000-65533:</tag>
6273 User <tt>nobody</tt>. The corresponding gid refers
6274 to the group <tt>nogroup</tt>.
6281 <tt>(uid_t)(-1) == (gid_t)(-1)</tt> <em>must
6282 not</em> be used, because it is the error return
6291 <sect id="sysvinit">
6292 <heading>System run levels and <file>init.d</file> scripts</heading>
6294 <sect1 id="/etc/init.d">
6295 <heading>Introduction</heading>
6298 The <file>/etc/init.d</file> directory contains the scripts
6299 executed by <prgn>init</prgn> at boot time and when the
6300 init state (or "runlevel") is changed (see <manref
6301 name="init" section="8">).
6305 There are at least two different, yet functionally
6306 equivalent, ways of handling these scripts. For the sake
6307 of simplicity, this document describes only the symbolic
6308 link method. However, it must not be assumed by maintainer
6309 scripts that this method is being used, and any automated
6310 manipulation of the various runlevel behaviors by
6311 maintainer scripts must be performed using
6312 <prgn>update-rc.d</prgn> as described below and not by
6313 manually installing or removing symlinks. For information
6314 on the implementation details of the other method,
6315 implemented in the <tt>file-rc</tt> package, please refer
6316 to the documentation of that package.
6320 These scripts are referenced by symbolic links in the
6321 <file>/etc/rc<var>n</var>.d</file> directories. When changing
6322 runlevels, <prgn>init</prgn> looks in the directory
6323 <file>/etc/rc<var>n</var>.d</file> for the scripts it should
6324 execute, where <tt><var>n</var></tt> is the runlevel that
6325 is being changed to, or <tt>S</tt> for the boot-up
6330 The names of the links all have the form
6331 <file>S<var>mm</var><var>script</var></file> or
6332 <file>K<var>mm</var><var>script</var></file> where
6333 <var>mm</var> is a two-digit number and <var>script</var>
6334 is the name of the script (this should be the same as the
6335 name of the actual script in <file>/etc/init.d</file>).
6339 When <prgn>init</prgn> changes runlevel first the targets
6340 of the links whose names start with a <tt>K</tt> are
6341 executed, each with the single argument <tt>stop</tt>,
6342 followed by the scripts prefixed with an <tt>S</tt>, each
6343 with the single argument <tt>start</tt>. (The links are
6344 those in the <file>/etc/rc<var>n</var>.d</file> directory
6345 corresponding to the new runlevel.) The <tt>K</tt> links
6346 are responsible for killing services and the <tt>S</tt>
6347 link for starting services upon entering the runlevel.
6351 For example, if we are changing from runlevel 2 to
6352 runlevel 3, init will first execute all of the <tt>K</tt>
6353 prefixed scripts it finds in <file>/etc/rc3.d</file>, and then
6354 all of the <tt>S</tt> prefixed scripts in that directory.
6355 The links starting with <tt>K</tt> will cause the
6356 referred-to file to be executed with an argument of
6357 <tt>stop</tt>, and the <tt>S</tt> links with an argument
6362 The two-digit number <var>mm</var> is used to determine
6363 the order in which to run the scripts: low-numbered links
6364 have their scripts run first. For example, the
6365 <tt>K20</tt> scripts will be executed before the
6366 <tt>K30</tt> scripts. This is used when a certain service
6367 must be started before another. For example, the name
6368 server <prgn>bind</prgn> might need to be started before
6369 the news server <prgn>inn</prgn> so that <prgn>inn</prgn>
6370 can set up its access lists. In this case, the script
6371 that starts <prgn>bind</prgn> would have a lower number
6372 than the script that starts <prgn>inn</prgn> so that it
6374 <example compact="compact">
6381 The two runlevels 0 (halt) and 6 (reboot) are slightly
6382 different. In these runlevels, the links with an
6383 <tt>S</tt> prefix are still called after those with a
6384 <tt>K</tt> prefix, but they too are called with the single
6385 argument <tt>stop</tt>.
6389 <sect1 id="writing-init">
6390 <heading>Writing the scripts</heading>
6393 Packages that include daemons for system services should
6394 place scripts in <file>/etc/init.d</file> to start or stop
6395 services at boot time or during a change of runlevel.
6396 These scripts should be named
6397 <file>/etc/init.d/<var>package</var></file>, and they should
6398 accept one argument, saying what to do:
6401 <tag><tt>start</tt></tag>
6402 <item>start the service,</item>
6404 <tag><tt>stop</tt></tag>
6405 <item>stop the service,</item>
6407 <tag><tt>restart</tt></tag>
6408 <item>stop and restart the service if it's already running,
6409 otherwise start the service</item>
6411 <tag><tt>reload</tt></tag>
6412 <item><p>cause the configuration of the service to be
6413 reloaded without actually stopping and restarting
6416 <tag><tt>force-reload</tt></tag>
6417 <item>cause the configuration to be reloaded if the
6418 service supports this, otherwise restart the
6422 The <tt>start</tt>, <tt>stop</tt>, <tt>restart</tt>, and
6423 <tt>force-reload</tt> options should be supported by all
6424 scripts in <file>/etc/init.d</file>, the <tt>reload</tt>
6429 The <file>init.d</file> scripts must ensure that they will
6430 behave sensibly (i.e., returning success and not starting
6431 multiple copies of a service) if invoked with <tt>start</tt>
6432 when the service is already running, or with <tt>stop</tt>
6433 when it isn't, and that they don't kill unfortunately-named
6434 user processes. The best way to achieve this is usually to
6435 use <prgn>start-stop-daemon</prgn> with the <tt>--oknodo</tt>
6440 Be careful of using <tt>set -e</tt> in <file>init.d</file>
6441 scripts. Writing correct <file>init.d</file> scripts requires
6442 accepting various error exit statuses when daemons are already
6443 running or already stopped without aborting
6444 the <file>init.d</file> script, and common <file>init.d</file>
6445 function libraries are not safe to call with <tt>set -e</tt>
6447 <tt>/lib/lsb/init-functions</tt>, which assists in writing
6448 LSB-compliant init scripts, may fail if <tt>set -e</tt> is
6449 in effect and echoing status messages to the console fails,
6451 </footnote>. For <tt>init.d</tt> scripts, it's often easier
6452 to not use <tt>set -e</tt> and instead check the result of
6453 each command separately.
6457 If a service reloads its configuration automatically (as
6458 in the case of <prgn>cron</prgn>, for example), the
6459 <tt>reload</tt> option of the <file>init.d</file> script
6460 should behave as if the configuration has been reloaded
6465 The <file>/etc/init.d</file> scripts must be treated as
6466 configuration files, either (if they are present in the
6467 package, that is, in the .deb file) by marking them as
6468 <tt>conffile</tt>s, or, (if they do not exist in the .deb)
6469 by managing them correctly in the maintainer scripts (see
6470 <ref id="config-files">). This is important since we want
6471 to give the local system administrator the chance to adapt
6472 the scripts to the local system, e.g., to disable a
6473 service without de-installing the package, or to specify
6474 some special command line options when starting a service,
6475 while making sure their changes aren't lost during the next
6480 These scripts should not fail obscurely when the
6481 configuration files remain but the package has been
6482 removed, as configuration files remain on the system after
6483 the package has been removed. Only when <prgn>dpkg</prgn>
6484 is executed with the <tt>--purge</tt> option will
6485 configuration files be removed. In particular, as the
6486 <file>/etc/init.d/<var>package</var></file> script itself is
6487 usually a <tt>conffile</tt>, it will remain on the system
6488 if the package is removed but not purged. Therefore, you
6489 should include a <tt>test</tt> statement at the top of the
6491 <example compact="compact">
6492 test -f <var>program-executed-later-in-script</var> || exit 0
6497 Often there are some variables in the <file>init.d</file>
6498 scripts whose values control the behavior of the scripts,
6499 and which a system administrator is likely to want to
6500 change. As the scripts themselves are frequently
6501 <tt>conffile</tt>s, modifying them requires that the
6502 administrator merge in their changes each time the package
6503 is upgraded and the <tt>conffile</tt> changes. To ease
6504 the burden on the system administrator, such configurable
6505 values should not be placed directly in the script.
6506 Instead, they should be placed in a file in
6507 <file>/etc/default</file>, which typically will have the same
6508 base name as the <file>init.d</file> script. This extra file
6509 should be sourced by the script when the script runs. It
6510 must contain only variable settings and comments in SUSv3
6511 <prgn>sh</prgn> format. It may either be a
6512 <tt>conffile</tt> or a configuration file maintained by
6513 the package maintainer scripts. See <ref id="config-files">
6518 To ensure that vital configurable values are always
6519 available, the <file>init.d</file> script should set default
6520 values for each of the shell variables it uses, either
6521 before sourcing the <file>/etc/default/</file> file or
6522 afterwards using something like the <tt>:
6523 ${VAR:=default}</tt> syntax. Also, the <file>init.d</file>
6524 script must behave sensibly and not fail if the
6525 <file>/etc/default</file> file is deleted.
6529 <file>/var/run</file> and <file>/var/lock</file> may be mounted
6530 as temporary filesystems<footnote>
6531 For example, using the <tt>RAMRUN</tt> and <tt>RAMLOCK</tt>
6532 options in <file>/etc/default/rcS</file>.
6533 </footnote>, so the <file>init.d</file> scripts must handle this
6534 correctly. This will typically amount to creating any required
6535 subdirectories dynamically when the <file>init.d</file> script
6536 is run, rather than including them in the package and relying on
6537 <prgn>dpkg</prgn> to create them.
6542 <heading>Interfacing with the initscript system</heading>
6545 Maintainers should use the abstraction layer provided by
6546 the <prgn>update-rc.d</prgn> and <prgn>invoke-rc.d</prgn>
6547 programs to deal with initscripts in their packages'
6548 scripts such as <prgn>postinst</prgn>, <prgn>prerm</prgn>
6549 and <prgn>postrm</prgn>.
6553 Directly managing the /etc/rc?.d links and directly
6554 invoking the <file>/etc/init.d/</file> initscripts should
6555 be done only by packages providing the initscript
6556 subsystem (such as <prgn>sysv-rc</prgn> and
6557 <prgn>file-rc</prgn>).
6561 <heading>Managing the links</heading>
6564 The program <prgn>update-rc.d</prgn> is provided for
6565 package maintainers to arrange for the proper creation and
6566 removal of <file>/etc/rc<var>n</var>.d</file> symbolic links,
6567 or their functional equivalent if another method is being
6568 used. This may be used by maintainers in their packages'
6569 <prgn>postinst</prgn> and <prgn>postrm</prgn> scripts.
6573 You must not include any <file>/etc/rc<var>n</var>.d</file>
6574 symbolic links in the actual archive or manually create or
6575 remove the symbolic links in maintainer scripts; you must
6576 use the <prgn>update-rc.d</prgn> program instead. (The
6577 former will fail if an alternative method of maintaining
6578 runlevel information is being used.) You must not include
6579 the <file>/etc/rc<var>n</var>.d</file> directories themselves
6580 in the archive either. (Only the <tt>sysvinit</tt>
6585 By default <prgn>update-rc.d</prgn> will start services in
6586 each of the multi-user state runlevels (2, 3, 4, and 5)
6587 and stop them in the halt runlevel (0), the single-user
6588 runlevel (1) and the reboot runlevel (6). The system
6589 administrator will have the opportunity to customize
6590 runlevels by simply adding, moving, or removing the
6591 symbolic links in <file>/etc/rc<var>n</var>.d</file> if
6592 symbolic links are being used, or by modifying
6593 <file>/etc/runlevel.conf</file> if the <tt>file-rc</tt> method
6598 To get the default behavior for your package, put in your
6599 <prgn>postinst</prgn> script
6600 <example compact="compact">
6601 update-rc.d <var>package</var> defaults
6603 and in your <prgn>postrm</prgn>
6604 <example compact="compact">
6605 if [ "$1" = purge ]; then
6606 update-rc.d <var>package</var> remove
6608 </example>. Note that if your package changes runlevels
6609 or priority, you may have to remove and recreate the links,
6610 since otherwise the old links may persist. Refer to the
6611 documentation of <prgn>update-rc.d</prgn>.
6615 This will use a default sequence number of 20. If it does
6616 not matter when or in which order the <file>init.d</file>
6617 script is run, use this default. If it does, then you
6618 should talk to the maintainer of the <prgn>sysvinit</prgn>
6619 package or post to <tt>debian-devel</tt>, and they will
6620 help you choose a number.
6624 For more information about using <tt>update-rc.d</tt>,
6625 please consult its man page <manref name="update-rc.d"
6631 <heading>Running initscripts</heading>
6633 The program <prgn>invoke-rc.d</prgn> is provided to make
6634 it easier for package maintainers to properly invoke an
6635 initscript, obeying runlevel and other locally-defined
6636 constraints that might limit a package's right to start,
6637 stop and otherwise manage services. This program may be
6638 used by maintainers in their packages' scripts.
6642 The package maintainer scripts must use
6643 <prgn>invoke-rc.d</prgn> to invoke the
6644 <file>/etc/init.d/*</file> initscripts, instead of
6645 calling them directly.
6649 By default, <prgn>invoke-rc.d</prgn> will pass any
6650 action requests (start, stop, reload, restart...) to the
6651 <file>/etc/init.d</file> script, filtering out requests
6652 to start or restart a service out of its intended
6657 Most packages will simply need to change:
6658 <example compact="compact">/etc/init.d/<package>
6659 <action></example> in their <prgn>postinst</prgn>
6660 and <prgn>prerm</prgn> scripts to:
6661 <example compact="compact">
6662 if which invoke-rc.d >/dev/null 2>&1; then
6663 invoke-rc.d <var>package</var> <action>
6665 /etc/init.d/<var>package</var> <action>
6671 A package should register its initscript services using
6672 <prgn>update-rc.d</prgn> before it tries to invoke them
6673 using <prgn>invoke-rc.d</prgn>. Invocation of
6674 unregistered services may fail.
6678 For more information about using
6679 <prgn>invoke-rc.d</prgn>, please consult its man page
6680 <manref name="invoke-rc.d" section="8">.
6686 <heading>Boot-time initialization</heading>
6689 There used to be another directory, <file>/etc/rc.boot</file>,
6690 which contained scripts which were run once per machine
6691 boot. This has been deprecated in favour of links from
6692 <file>/etc/rcS.d</file> to files in <file>/etc/init.d</file> as
6693 described in <ref id="/etc/init.d">. Packages must not
6694 place files in <file>/etc/rc.boot</file>.
6699 <heading>Example</heading>
6702 An example on which you can base your
6703 <file>/etc/init.d</file> scripts is found in
6704 <file>/etc/init.d/skeleton</file>.
6711 <heading>Console messages from <file>init.d</file> scripts</heading>
6714 This section describes the formats to be used for messages
6715 written to standard output by the <file>/etc/init.d</file>
6716 scripts. The intent is to improve the consistency of
6717 Debian's startup and shutdown look and feel. For this
6718 reason, please look very carefully at the details. We want
6719 the messages to have the same format in terms of wording,
6720 spaces, punctuation and case of letters.
6724 Here is a list of overall rules that should be used for
6725 messages generated by <file>/etc/init.d</file> scripts.
6731 The message should fit in one line (fewer than 80
6732 characters), start with a capital letter and end with
6733 a period (<tt>.</tt>) and line feed (<tt>"\n"</tt>).
6737 If the script is performing some time consuming task in
6738 the background (not merely starting or stopping a
6739 program, for instance), an ellipsis (three dots:
6740 <tt>...</tt>) should be output to the screen, with no
6741 leading or tailing whitespace or line feeds.
6745 The messages should appear as if the computer is telling
6746 the user what it is doing (politely :-), but should not
6747 mention "it" directly. For example, instead of:
6748 <example compact="compact">
6749 I'm starting network daemons: nfsd mountd.
6751 the message should say
6752 <example compact="compact">
6753 Starting network daemons: nfsd mountd.
6760 <tt>init.d</tt> script should use the following standard
6761 message formats for the situations enumerated below.
6767 <p>When daemons are started</p>
6770 If the script starts one or more daemons, the output
6771 should look like this (a single line, no leading
6773 <example compact="compact">
6774 Starting <var>description</var>: <var>daemon-1</var> ... <var>daemon-n</var>.
6776 The <var>description</var> should describe the
6777 subsystem the daemon or set of daemons are part of,
6778 while <var>daemon-1</var> up to <var>daemon-n</var>
6779 denote each daemon's name (typically the file name of
6784 For example, the output of <file>/etc/init.d/lpd</file>
6786 <example compact="compact">
6787 Starting printer spooler: lpd.
6792 This can be achieved by saying
6793 <example compact="compact">
6794 echo -n "Starting printer spooler: lpd"
6795 start-stop-daemon --start --quiet --exec /usr/sbin/lpd
6798 in the script. If there are more than one daemon to
6799 start, the output should look like this:
6800 <example compact="compact">
6801 echo -n "Starting remote file system services:"
6802 echo -n " nfsd"; start-stop-daemon --start --quiet nfsd
6803 echo -n " mountd"; start-stop-daemon --start --quiet mountd
6804 echo -n " ugidd"; start-stop-daemon --start --quiet ugidd
6807 This makes it possible for the user to see what is
6808 happening and when the final daemon has been started.
6809 Care should be taken in the placement of white spaces:
6810 in the example above the system administrators can
6811 easily comment out a line if they don't want to start
6812 a specific daemon, while the displayed message still
6818 <p>When a system parameter is being set</p>
6821 If you have to set up different system parameters
6822 during the system boot, you should use this format:
6823 <example compact="compact">
6824 Setting <var>parameter</var> to "<var>value</var>".
6829 You can use a statement such as the following to get
6831 <example compact="compact">
6832 echo "Setting DNS domainname to \"$domainname\"."
6837 Note that the same symbol (<tt>"</tt>) <!-- " --> is used
6838 for the left and right quotation marks. A grave accent
6839 (<tt>`</tt>) is not a quote character; neither is an
6840 apostrophe (<tt>'</tt>).
6845 <p>When a daemon is stopped or restarted</p>
6848 When you stop or restart a daemon, you should issue a
6849 message identical to the startup message, except that
6850 <tt>Starting</tt> is replaced with <tt>Stopping</tt>
6851 or <tt>Restarting</tt> respectively.
6855 For example, stopping the printer daemon will look like
6857 <example compact="compact">
6858 Stopping printer spooler: lpd.
6864 <p>When something is executed</p>
6867 There are several examples where you have to run a
6868 program at system startup or shutdown to perform a
6869 specific task, for example, setting the system's clock
6870 using <prgn>netdate</prgn> or killing all processes
6871 when the system shuts down. Your message should look
6873 <example compact="compact">
6874 Doing something very useful...done.
6876 You should print the <tt>done.</tt> immediately after
6877 the job has been completed, so that the user is
6878 informed why they have to wait. You can get this
6880 <example compact="compact">
6881 echo -n "Doing something very useful..."
6890 <p>When the configuration is reloaded</p>
6893 When a daemon is forced to reload its configuration
6894 files you should use the following format:
6895 <example compact="compact">
6896 Reloading <var>description</var> configuration...done.
6898 where <var>description</var> is the same as in the
6899 daemon starting message.
6907 <heading>Cron jobs</heading>
6910 Packages must not modify the configuration file
6911 <file>/etc/crontab</file>, and they must not modify the files in
6912 <file>/var/spool/cron/crontabs</file>.</p>
6915 If a package wants to install a job that has to be executed
6916 via cron, it should place a file with the name of the
6917 package in one or more of the following directories:
6918 <example compact="compact">
6924 As these directory names imply, the files within them are
6925 executed on an hourly, daily, weekly, or monthly basis,
6926 respectively. The exact times are listed in
6927 <file>/etc/crontab</file>.</p>
6930 All files installed in any of these directories must be
6931 scripts (e.g., shell scripts or Perl scripts) so that they
6932 can easily be modified by the local system administrator.
6933 In addition, they must be treated as configuration files.
6937 If a certain job has to be executed at some other frequency or
6938 at a specific time, the package should install a file
6939 <file>/etc/cron.d/<var>package</var></file>. This file uses the
6940 same syntax as <file>/etc/crontab</file> and is processed by
6941 <prgn>cron</prgn> automatically. The file must also be
6942 treated as a configuration file. (Note that entries in the
6943 <file>/etc/cron.d</file> directory are not handled by
6944 <prgn>anacron</prgn>. Thus, you should only use this
6945 directory for jobs which may be skipped if the system is not
6948 Unlike <file>crontab</file> files described in the IEEE Std
6949 1003.1-2008 (POSIX.1) available from
6950 <url id="http://www.opengroup.org/onlinepubs/9699919799/"
6951 name="The Open Group">, the files in
6952 <file>/etc/cron.d</file> and the file
6953 <file>/etc/crontab</file> have seven fields; namely:
6955 <item>Minute [0,59]</item>
6956 <item>Hour [0,23]</item>
6957 <item>Day of the month [1,31]</item>
6958 <item>Month of the year [1,12]</item>
6959 <item>Day of the week ([0,6] with 0=Sunday)</item>
6960 <item>Username</item>
6961 <item>Command to be run</item>
6963 Ranges of numbers are allowed. Ranges are two numbers
6964 separated with a hyphen. The specified range is inclusive.
6965 Lists are allowed. A list is a set of numbers (or ranges)
6966 separated by commas. Step values can be used in conjunction
6971 The scripts or <tt>crontab</tt> entries in these directories should
6972 check if all necessary programs are installed before they
6973 try to execute them. Otherwise, problems will arise when a
6974 package was removed but not purged since configuration files
6975 are kept on the system in this situation.
6979 Any <tt>cron</tt> daemon must provide
6980 <file>/usr/bin/crontab</file> and support normal
6981 <tt>crontab</tt> entries as specified in POSIX. The daemon
6982 must also support names for days and months, ranges, and
6983 step values. It has to support <file>/etc/crontab</file>,
6984 and correctly execute the scripts in
6985 <file>/etc/cron.d</file>. The daemon must also correctly
6987 <file>/etc/cron.{hourly,daily,weekly,monthly}</file>.
6992 <heading>Menus</heading>
6995 The Debian <tt>menu</tt> package provides a standard
6996 interface between packages providing applications and
6997 <em>menu programs</em> (either X window managers or
6998 text-based menu programs such as <prgn>pdmenu</prgn>).
7002 All packages that provide applications that need not be
7003 passed any special command line arguments for normal
7004 operation should register a menu entry for those
7005 applications, so that users of the <tt>menu</tt> package
7006 will automatically get menu entries in their window
7007 managers, as well in shells like <tt>pdmenu</tt>.
7011 Menu entries should follow the current menu policy.
7015 The menu policy can be found in the <tt>menu-policy</tt>
7016 files in the <tt>debian-policy</tt> package.
7017 It is also available from the Debian web mirrors at
7018 <tt><url name="/doc/packaging-manuals/menu-policy/"
7019 id="http://www.debian.org/doc/packaging-manuals/menu-policy/"></tt>.
7023 Please also refer to the <em>Debian Menu System</em>
7024 documentation that comes with the <package>menu</package>
7025 package for information about how to register your
7031 <heading>Multimedia handlers</heading>
7034 MIME (Multipurpose Internet Mail Extensions, RFCs 2045-2049)
7035 is a mechanism for encoding files and data streams and
7036 providing meta-information about them, in particular their
7037 type (e.g. audio or video) and format (e.g. PNG, HTML,
7042 Registration of MIME type handlers allows programs like mail
7043 user agents and web browsers to invoke these handlers to
7044 view, edit or display MIME types they don't support directly.
7048 Packages which provide the ability to view/show/play,
7049 compose, edit or print MIME types should register themselves
7050 as such following the current MIME support policy.
7054 The MIME support policy can be found in the <tt>mime-policy</tt>
7055 files in the <tt>debian-policy</tt> package.
7056 It is also available from the Debian web mirrors at
7057 <tt><url name="/doc/packaging-manuals/mime-policy/"
7058 id="http://www.debian.org/doc/packaging-manuals/mime-policy/"></tt>.
7064 <heading>Keyboard configuration</heading>
7067 To achieve a consistent keyboard configuration so that all
7068 applications interpret a keyboard event the same way, all
7069 programs in the Debian distribution must be configured to
7070 comply with the following guidelines.
7074 The following keys must have the specified interpretations:
7077 <tag><tt><--</tt></tag>
7078 <item>delete the character to the left of the cursor</item>
7080 <tag><tt>Delete</tt></tag>
7081 <item>delete the character to the right of the cursor</item>
7083 <tag><tt>Control+H</tt></tag>
7084 <item>emacs: the help prefix</item>
7087 The interpretation of any keyboard events should be
7088 independent of the terminal that is used, be it a virtual
7089 console, an X terminal emulator, an rlogin/telnet session,
7094 The following list explains how the different programs
7095 should be set up to achieve this:
7101 <tt><--</tt> generates <tt>KB_BackSpace</tt> in X.
7105 <tt>Delete</tt> generates <tt>KB_Delete</tt> in X.
7109 X translations are set up to make
7110 <tt>KB_Backspace</tt> generate ASCII DEL, and to make
7111 <tt>KB_Delete</tt> generate <tt>ESC [ 3 ~</tt> (this
7112 is the vt220 escape code for the "delete character"
7113 key). This must be done by loading the X resources
7114 using <prgn>xrdb</prgn> on all local X displays, not
7115 using the application defaults, so that the
7116 translation resources used correspond to the
7117 <prgn>xmodmap</prgn> settings.
7121 The Linux console is configured to make
7122 <tt><--</tt> generate DEL, and <tt>Delete</tt>
7123 generate <tt>ESC [ 3 ~</tt>.
7127 X applications are configured so that <tt><</tt>
7128 deletes left, and <tt>Delete</tt> deletes right. Motif
7129 applications already work like this.
7133 Terminals should have <tt>stty erase ^?</tt> .
7137 The <tt>xterm</tt> terminfo entry should have <tt>ESC
7138 [ 3 ~</tt> for <tt>kdch1</tt>, just as for
7139 <tt>TERM=linux</tt> and <tt>TERM=vt220</tt>.
7143 Emacs is programmed to map <tt>KB_Backspace</tt> or
7144 the <tt>stty erase</tt> character to
7145 <tt>delete-backward-char</tt>, and <tt>KB_Delete</tt>
7146 or <tt>kdch1</tt> to <tt>delete-forward-char</tt>, and
7147 <tt>^H</tt> to <tt>help</tt> as always.
7151 Other applications use the <tt>stty erase</tt>
7152 character and <tt>kdch1</tt> for the two delete keys,
7153 with ASCII DEL being "delete previous character" and
7154 <tt>kdch1</tt> being "delete character under
7162 This will solve the problem except for the following
7169 Some terminals have a <tt><--</tt> key that cannot
7170 be made to produce anything except <tt>^H</tt>. On
7171 these terminals Emacs help will be unavailable on
7172 <tt>^H</tt> (assuming that the <tt>stty erase</tt>
7173 character takes precedence in Emacs, and has been set
7174 correctly). <tt>M-x help</tt> or <tt>F1</tt> (if
7175 available) can be used instead.
7179 Some operating systems use <tt>^H</tt> for <tt>stty
7180 erase</tt>. However, modern telnet versions and all
7181 rlogin versions propagate <tt>stty</tt> settings, and
7182 almost all UNIX versions honour <tt>stty erase</tt>.
7183 Where the <tt>stty</tt> settings are not propagated
7184 correctly, things can be made to work by using
7185 <tt>stty</tt> manually.
7189 Some systems (including previous Debian versions) use
7190 <prgn>xmodmap</prgn> to arrange for both
7191 <tt><--</tt> and <tt>Delete</tt> to generate
7192 <tt>KB_Delete</tt>. We can change the behavior of
7193 their X clients using the same X resources that we use
7194 to do it for our own clients, or configure our clients
7195 using their resources when things are the other way
7196 around. On displays configured like this
7197 <tt>Delete</tt> will not work, but <tt><--</tt>
7202 Some operating systems have different <tt>kdch1</tt>
7203 settings in their <tt>terminfo</tt> database for
7204 <tt>xterm</tt> and others. On these systems the
7205 <tt>Delete</tt> key will not work correctly when you
7206 log in from a system conforming to our policy, but
7207 <tt><--</tt> will.
7214 <heading>Environment variables</heading>
7217 A program must not depend on environment variables to get
7218 reasonable defaults. (That's because these environment
7219 variables would have to be set in a system-wide
7220 configuration file like <file>/etc/profile</file>, which is not
7221 supported by all shells.)
7225 If a program usually depends on environment variables for its
7226 configuration, the program should be changed to fall back to
7227 a reasonable default configuration if these environment
7228 variables are not present. If this cannot be done easily
7229 (e.g., if the source code of a non-free program is not
7230 available), the program must be replaced by a small
7231 "wrapper" shell script which sets the environment variables
7232 if they are not already defined, and calls the original program.
7236 Here is an example of a wrapper script for this purpose:
7238 <example compact="compact">
7240 BAR=${BAR:-/var/lib/fubar}
7242 exec /usr/lib/foo/foo "$@"
7247 Furthermore, as <file>/etc/profile</file> is a configuration
7248 file of the <prgn>base-files</prgn> package, other packages must
7249 not put any environment variables or other commands into that
7254 <sect id="doc-base">
7255 <heading>Registering Documents using doc-base</heading>
7258 The <package>doc-base</package> package implements a
7259 flexible mechanism for handling and presenting
7260 documentation. The recommended practice is for every Debian
7261 package that provides online documentation (other than just
7262 manual pages) to register these documents with
7263 <package>doc-base</package> by installing a
7264 <package>doc-base</package> control file via the
7265 <prgn/install-docs/ script at installation time and
7266 de-register the manuals again when the package is removed.
7269 Please refer to the documentation that comes with the
7270 <package>doc-base</package> package for information and
7279 <heading>Files</heading>
7281 <sect id="binaries">
7282 <heading>Binaries</heading>
7285 Two different packages must not install programs with
7286 different functionality but with the same filenames. (The
7287 case of two programs having the same functionality but
7288 different implementations is handled via "alternatives" or
7289 the "Conflicts" mechanism. See <ref id="maintscripts"> and
7290 <ref id="conflicts"> respectively.) If this case happens,
7291 one of the programs must be renamed. The maintainers should
7292 report this to the <tt>debian-devel</tt> mailing list and
7293 try to find a consensus about which program will have to be
7294 renamed. If a consensus cannot be reached, <em>both</em>
7295 programs must be renamed.
7299 By default, when a package is being built, any binaries
7300 created should include debugging information, as well as
7301 being compiled with optimization. You should also turn on
7302 as many reasonable compilation warnings as possible; this
7303 makes life easier for porters, who can then look at build
7304 logs for possible problems. For the C programming language,
7305 this means the following compilation parameters should be
7307 <example compact="compact">
7309 CFLAGS = -O2 -g -Wall # sane warning options vary between programs
7311 INSTALL = install -s # (or use strip on the files in debian/tmp)
7316 Note that by default all installed binaries should be stripped,
7317 either by using the <tt>-s</tt> flag to
7318 <prgn>install</prgn>, or by calling <prgn>strip</prgn> on
7319 the binaries after they have been copied into
7320 <file>debian/tmp</file> but before the tree is made into a
7325 Although binaries in the build tree should be compiled with
7326 debugging information by default, it can often be difficult to
7327 debug programs if they are also subjected to compiler
7328 optimization. For this reason, it is recommended to support the
7329 standardized environment variable <tt>DEB_BUILD_OPTIONS</tt>
7330 (see <ref id="debianrules-options">). This variable can contain
7331 several flags to change how a package is compiled and built.
7335 It is up to the package maintainer to decide what
7336 compilation options are best for the package. Certain
7337 binaries (such as computationally-intensive programs) will
7338 function better with certain flags (<tt>-O3</tt>, for
7339 example); feel free to use them. Please use good judgment
7340 here. Don't use flags for the sake of it; only use them
7341 if there is good reason to do so. Feel free to override
7342 the upstream author's ideas about which compilation
7343 options are best: they are often inappropriate for our
7349 <sect id="libraries">
7350 <heading>Libraries</heading>
7353 If the package is <strong>architecture: any</strong>, then
7354 the shared library compilation and linking flags must have
7355 <tt>-fPIC</tt>, or the package shall not build on some of
7356 the supported architectures<footnote>
7358 If you are using GCC, <tt>-fPIC</tt> produces code with
7359 relocatable position independent code, which is required for
7360 most architectures to create a shared library, with i386 and
7361 perhaps some others where non position independent code is
7362 permitted in a shared library.
7365 Position independent code may have a performance penalty,
7366 especially on <tt>i386</tt>. However, in most cases the
7367 speed penalty must be measured against the memory wasted on
7368 the few architectures where non position independent code is
7371 </footnote>. Any exception to this rule must be discussed on
7372 the mailing list <em>debian-devel@lists.debian.org</em>, and
7373 a rough consensus obtained. The reasons for not compiling
7374 with <tt>-fPIC</tt> flag must be recorded in the file
7375 <tt>README.Debian</tt>, and care must be taken to either
7376 restrict the architecture or arrange for <tt>-fPIC</tt> to
7377 be used on architectures where it is required.<footnote>
7379 Some of the reasons why this might be required is if the
7380 library contains hand crafted assembly code that is not
7381 relocatable, the speed penalty is excessive for compute
7382 intensive libs, and similar reasons.
7387 As to the static libraries, the common case is not to have
7388 relocatable code, since there is no benefit, unless in specific
7389 cases; therefore the static version must not be compiled
7390 with the <tt>-fPIC</tt> flag. Any exception to this rule
7391 should be discussed on the mailing list
7392 <em>debian-devel@lists.debian.org</em>, and the reasons for
7393 compiling with the <tt>-fPIC</tt> flag must be recorded in
7394 the file <tt>README.Debian</tt>. <footnote>
7396 Some of the reasons for linking static libraries with
7397 the <tt>-fPIC</tt> flag are if, for example, one needs a
7398 Perl API for a library that is under rapid development,
7399 and has an unstable API, so shared libraries are
7400 pointless at this phase of the library's development. In
7401 that case, since Perl needs a library with relocatable
7402 code, it may make sense to create a static library with
7403 relocatable code. Another reason cited is if you are
7404 distilling various libraries into a common shared
7405 library, like <tt>mklibs</tt> does in the Debian
7411 In other words, if both a shared and a static library is
7412 being built, each source unit (<tt>*.c</tt>, for example,
7413 for C files) will need to be compiled twice, for the normal
7418 Libraries should be built with threading support and to be
7419 thread-safe if the library supports this.
7423 Although not enforced by the build tools, shared libraries
7424 must be linked against all libraries that they use symbols from
7425 in the same way that binaries are. This ensures the correct
7426 functioning of the <qref id="sharedlibs-shlibdeps">shlibs</qref>
7427 system and guarantees that all libraries can be safely opened
7428 with <tt>dlopen()</tt>. Packagers may wish to use the gcc
7429 option <tt>-Wl,-z,defs</tt> when building a shared library.
7430 Since this option enforces symbol resolution at build time,
7431 a missing library reference will be caught early as a fatal
7436 All installed shared libraries should be stripped with
7437 <example compact="compact">
7438 strip --strip-unneeded <var>your-lib</var>
7440 (The option <tt>--strip-unneeded</tt> makes
7441 <prgn>strip</prgn> remove only the symbols which aren't
7442 needed for relocation processing.) Shared libraries can
7443 function perfectly well when stripped, since the symbols for
7444 dynamic linking are in a separate part of the ELF object
7446 You might also want to use the options
7447 <tt>--remove-section=.comment</tt> and
7448 <tt>--remove-section=.note</tt> on both shared libraries
7449 and executables, and <tt>--strip-debug</tt> on static
7455 Note that under some circumstances it may be useful to
7456 install a shared library unstripped, for example when
7457 building a separate package to support debugging.
7461 Shared object files (often <file>.so</file> files) that are not
7462 public libraries, that is, they are not meant to be linked
7463 to by third party executables (binaries of other packages),
7464 should be installed in subdirectories of the
7465 <file>/usr/lib</file> directory. Such files are exempt from the
7466 rules that govern ordinary shared libraries, except that
7467 they must not be installed executable and should be
7469 A common example are the so-called "plug-ins",
7470 internal shared objects that are dynamically loaded by
7471 programs using <manref name="dlopen" section="3">.
7476 Packages that use <prgn>libtool</prgn> to create and install
7477 their shared libraries install a file containing additional
7478 metadata (ending in <file>.la</file>) alongside the library.
7479 For public libraries intended for use by other packages, these
7480 files normally should not be included in the Debian package,
7481 since the information they include is not necessary to link with
7482 the shared library on Debian and can add unnecessary additional
7483 dependencies to other programs or libraries.<footnote>
7484 These files store, among other things, all libraries on which
7485 that shared library depends. Unfortunately, if
7486 the <file>.la</file> file is present and contains that
7487 dependency information, using <prgn>libtool</prgn> when
7488 linking against that library will cause the resulting program
7489 or library to be linked against those dependencies as well,
7490 even if this is unnecessary. This can create unneeded
7491 dependencies on shared library packages that would otherwise
7492 be hidden behind the library ABI, and can make library
7493 transitions to new SONAMEs unnecessarily complicated and
7494 difficult to manage.
7496 If the <file>.la</file> file is required for that library (if,
7497 for instance, it's loaded via <tt>libltdl</tt> in a way that
7498 requires that meta-information), the <tt>dependency_libs</tt>
7499 setting in the <file>.la</file> file should normally be set to
7500 the empty string. If the shared library development package has
7501 historically included the <file>.la</file>, it must be retained
7502 in the development package (with <tt>dependency_libs</tt>
7503 emptied) until all libraries that depend on it have removed or
7504 emptied <tt>dependency_libs</tt> in their <file>.la</file>
7505 files to prevent linking with those other libraries
7506 using <prgn>libtool</prgn> from failing.
7510 If the <file>.la</file> must be included, it should be included
7511 in the development (<tt>-dev</tt>) package, unless the library
7512 will be loaded by <prgn>libtool</prgn>'s <tt>libltdl</tt>
7513 library. If it is intended for use with <tt>libltdl</tt>,
7514 the <file>.la</file> files must go in the run-time library
7519 These requirements for handling of <file>.la</file> files do not
7520 apply to loadable modules or libraries not installed in
7521 directories searched by default by the dynamic linker. Packages
7522 installing loadable modules will frequently need to install
7523 the <file>.la</file> files alongside the modules so that they
7524 can be loaded by <tt>libltdl</tt>. <tt>dependency_libs</tt>
7525 does not need to be modified for libraries or modules that are
7526 not installed in directories searched by the dynamic linker by
7527 default and not intended for use by other packages.
7531 You must make sure that you use only released versions of
7532 shared libraries to build your packages; otherwise other
7533 users will not be able to run your binaries
7534 properly. Producing source packages that depend on
7535 unreleased compilers is also usually a bad
7542 <heading>Shared libraries</heading>
7544 This section has moved to <ref id="sharedlibs">.
7550 <heading>Scripts</heading>
7553 All command scripts, including the package maintainer
7554 scripts inside the package and used by <prgn>dpkg</prgn>,
7555 should have a <tt>#!</tt> line naming the shell to be used
7560 In the case of Perl scripts this should be
7561 <tt>#!/usr/bin/perl</tt>.
7565 When scripts are installed into a directory in the system
7566 PATH, the script name should not include an extension such
7567 as <tt>.sh</tt> or <tt>.pl</tt> that denotes the scripting
7568 language currently used to implement it.
7571 Shell scripts (<prgn>sh</prgn> and <prgn>bash</prgn>) other than
7572 <file>init.d</file> scripts should almost certainly start
7573 with <tt>set -e</tt> so that errors are detected.
7574 <file>init.d</file> scripts are something of a special case, due
7575 to how frequently they need to call commands that are allowed to
7576 fail, and it may instead be easier to check the exit status of
7577 commands directly. See <ref id="writing-init"> for more
7578 information about writing <file>init.d</file> scripts.
7581 Every script should use <tt>set -e</tt> or check the exit status
7582 of <em>every</em> command.
7585 Scripts may assume that <file>/bin/sh</file> implements the
7586 SUSv3 Shell Command Language<footnote>
7587 Single UNIX Specification, version 3, which is also IEEE
7588 1003.1-2004 (POSIX), and is available on the World Wide Web
7589 from <url id="http://www.unix.org/version3/online.html"
7590 name="The Open Group"> after free
7591 registration.</footnote>
7592 plus the following additional features not mandated by
7594 These features are in widespread use in the Linux community
7595 and are implemented in all of bash, dash, and ksh, the most
7596 common shells users may wish to use as <file>/bin/sh</file>.
7599 <item><tt>echo -n</tt>, if implemented as a shell built-in,
7600 must not generate a newline.</item>
7601 <item><tt>test</tt>, if implemented as a shell built-in, must
7602 support <tt>-a</tt> and <tt>-o</tt> as binary logical
7604 <item><tt>local</tt> to create a scoped variable must be
7605 supported, including listing multiple variables in a single
7606 local command and assigning a value to a variable at the
7607 same time as localizing it. <tt>local</tt> may or
7608 may not preserve the variable value from an outer scope if
7609 no assignment is present. Uses such as:
7613 # ... use a, b, c, d ...
7616 must be supported and must set the value of <tt>c</tt> to
7619 <item>The XSI extension to <prgn>kill</prgn> allowing <tt>kill
7620 -<var>signal</var></tt>, where <var>signal</var> is either
7621 the name of a signal or one of the numeric signals listed in
7622 the XSI extension (0, 1, 2, 3, 6, 9, 14, and 15), must be
7623 supported if <prgn>kill</prgn> is implemented as a shell
7626 <item>The XSI extension to <prgn>trap</prgn> allowing numeric
7627 signals must be supported. In addition to the signal
7628 numbers listed in the extension, which are the same as for
7629 <prgn>kill</prgn> above, 13 (SIGPIPE) must be allowed.
7632 If a shell script requires non-SUSv3 features from the shell
7633 interpreter other than those listed above, the appropriate shell
7634 must be specified in the first line of the script (e.g.,
7635 <tt>#!/bin/bash</tt>) and the package must depend on the package
7636 providing the shell (unless the shell package is marked
7637 "Essential", as in the case of <prgn>bash</prgn>).
7641 You may wish to restrict your script to SUSv3 features plus the
7642 above set when possible so that it may use <file>/bin/sh</file>
7643 as its interpreter. If your script works with <prgn>dash</prgn>
7644 (originally called <prgn>ash</prgn>), it probably complies with
7645 the above requirements, but if you are in doubt, use
7646 <file>/bin/bash</file>.
7650 Perl scripts should check for errors when making any
7651 system calls, including <tt>open</tt>, <tt>print</tt>,
7652 <tt>close</tt>, <tt>rename</tt> and <tt>system</tt>.
7656 <prgn>csh</prgn> and <prgn>tcsh</prgn> should be avoided as
7657 scripting languages. See <em>Csh Programming Considered
7658 Harmful</em>, one of the <tt>comp.unix.*</tt> FAQs, which
7659 can be found at <url id="http://www.faqs.org/faqs/unix-faq/shell/csh-whynot/">.
7660 If an upstream package comes with <prgn>csh</prgn> scripts
7661 then you must make sure that they start with
7662 <tt>#!/bin/csh</tt> and make your package depend on the
7663 <prgn>c-shell</prgn> virtual package.
7667 Any scripts which create files in world-writeable
7668 directories (e.g., in <file>/tmp</file>) must use a
7669 mechanism which will fail atomically if a file with the same
7670 name already exists.
7674 The Debian base system provides the <prgn>tempfile</prgn>
7675 and <prgn>mktemp</prgn> utilities for use by scripts for
7682 <heading>Symbolic links</heading>
7685 In general, symbolic links within a top-level directory
7686 should be relative, and symbolic links pointing from one
7687 top-level directory into another should be absolute. (A
7688 top-level directory is a sub-directory of the root
7689 directory <file>/</file>.)
7693 In addition, symbolic links should be specified as short as
7694 possible, i.e., link targets like <file>foo/../bar</file> are
7699 Note that when creating a relative link using
7700 <prgn>ln</prgn> it is not necessary for the target of the
7701 link to exist relative to the working directory you're
7702 running <prgn>ln</prgn> from, nor is it necessary to change
7703 directory to the directory where the link is to be made.
7704 Simply include the string that should appear as the target
7705 of the link (this will be a pathname relative to the
7706 directory in which the link resides) as the first argument
7711 For example, in your <prgn>Makefile</prgn> or
7712 <file>debian/rules</file>, you can do things like:
7713 <example compact="compact">
7714 ln -fs gcc $(prefix)/bin/cc
7715 ln -fs gcc debian/tmp/usr/bin/cc
7716 ln -fs ../sbin/sendmail $(prefix)/bin/runq
7717 ln -fs ../sbin/sendmail debian/tmp/usr/bin/runq
7722 A symbolic link pointing to a compressed file should always
7723 have the same file extension as the referenced file. (For
7724 example, if a file <file>foo.gz</file> is referenced by a
7725 symbolic link, the filename of the link has to end with
7726 "<file>.gz</file>" too, as in <file>bar.gz</file>.)
7731 <heading>Device files</heading>
7734 Packages must not include device files or named pipes in the
7739 If a package needs any special device files that are not
7740 included in the base system, it must call
7741 <prgn>MAKEDEV</prgn> in the <prgn>postinst</prgn> script,
7742 after notifying the user<footnote>
7743 This notification could be done via a (low-priority)
7744 debconf message, or an echo (printf) statement.
7749 Packages must not remove any device files in the
7750 <prgn>postrm</prgn> or any other script. This is left to the
7751 system administrator.
7755 Debian uses the serial devices
7756 <file>/dev/ttyS*</file>. Programs using the old
7757 <file>/dev/cu*</file> devices should be changed to use
7758 <file>/dev/ttyS*</file>.
7762 Named pipes needed by the package must be created in
7763 the <prgn>postinst</prgn> script<footnote>
7764 It's better to use <prgn>mkfifo</prgn> rather
7765 than <prgn>mknod</prgn> to create named pipes so that
7766 automated checks for packages incorrectly creating device
7767 files with <prgn>mknod</prgn> won't have false positives.
7768 </footnote> and removed in
7769 the <prgn>prerm</prgn> or <prgn>postrm</prgn> script as
7774 <sect id="config-files">
7775 <heading>Configuration files</heading>
7778 <heading>Definitions</heading>
7782 <tag>configuration file</tag>
7784 A file that affects the operation of a program, or
7785 provides site- or host-specific information, or
7786 otherwise customizes the behavior of a program.
7787 Typically, configuration files are intended to be
7788 modified by the system administrator (if needed or
7789 desired) to conform to local policy or to provide
7790 more useful site-specific behavior.
7793 <tag><tt>conffile</tt></tag>
7795 A file listed in a package's <tt>conffiles</tt>
7796 file, and is treated specially by <prgn>dpkg</prgn>
7797 (see <ref id="configdetails">).
7803 The distinction between these two is important; they are
7804 not interchangeable concepts. Almost all
7805 <tt>conffile</tt>s are configuration files, but many
7806 configuration files are not <tt>conffiles</tt>.
7810 As noted elsewhere, <file>/etc/init.d</file> scripts,
7811 <file>/etc/default</file> files, scripts installed in
7812 <file>/etc/cron.{hourly,daily,weekly,monthly}</file>, and cron
7813 configuration installed in <file>/etc/cron.d</file> must be
7814 treated as configuration files. In general, any script that
7815 embeds configuration information is de-facto a configuration
7816 file and should be treated as such.
7821 <heading>Location</heading>
7824 Any configuration files created or used by your package
7825 must reside in <file>/etc</file>. If there are several,
7826 consider creating a subdirectory of <file>/etc</file>
7827 named after your package.
7831 If your package creates or uses configuration files
7832 outside of <file>/etc</file>, and it is not feasible to modify
7833 the package to use <file>/etc</file> directly, put the files
7834 in <file>/etc</file> and create symbolic links to those files
7835 from the location that the package requires.
7840 <heading>Behavior</heading>
7843 Configuration file handling must conform to the following
7845 <list compact="compact">
7847 local changes must be preserved during a package
7851 configuration files must be preserved when the
7852 package is removed, and only deleted when the
7856 Obsolete configuration files without local changes may be
7857 removed by the package during upgrade.
7861 The easy way to achieve this behavior is to make the
7862 configuration file a <tt>conffile</tt>. This is
7863 appropriate only if it is possible to distribute a default
7864 version that will work for most installations, although
7865 some system administrators may choose to modify it. This
7866 implies that the default version will be part of the
7867 package distribution, and must not be modified by the
7868 maintainer scripts during installation (or at any other
7873 In order to ensure that local changes are preserved
7874 correctly, no package may contain or make hard links to
7875 conffiles.<footnote>
7876 Rationale: There are two problems with hard links.
7877 The first is that some editors break the link while
7878 editing one of the files, so that the two files may
7879 unwittingly become unlinked and different. The second
7880 is that <prgn>dpkg</prgn> might break the hard link
7881 while upgrading <tt>conffile</tt>s.
7886 The other way to do it is via the maintainer scripts. In
7887 this case, the configuration file must not be listed as a
7888 <tt>conffile</tt> and must not be part of the package
7889 distribution. If the existence of a file is required for
7890 the package to be sensibly configured it is the
7891 responsibility of the package maintainer to provide
7892 maintainer scripts which correctly create, update and
7893 maintain the file and remove it on purge. (See <ref
7894 id="maintainerscripts"> for more information.) These
7895 scripts must be idempotent (i.e., must work correctly if
7896 <prgn>dpkg</prgn> needs to re-run them due to errors
7897 during installation or removal), must cope with all the
7898 variety of ways <prgn>dpkg</prgn> can call maintainer
7899 scripts, must not overwrite or otherwise mangle the user's
7900 configuration without asking, must not ask unnecessary
7901 questions (particularly during upgrades), and must
7902 otherwise be good citizens.
7906 The scripts are not required to configure every possible
7907 option for the package, but only those necessary to get
7908 the package running on a given system. Ideally the
7909 sysadmin should not have to do any configuration other
7910 than that done (semi-)automatically by the
7911 <prgn>postinst</prgn> script.
7915 A common practice is to create a script called
7916 <file><var>package</var>-configure</file> and have the
7917 package's <prgn>postinst</prgn> call it if and only if the
7918 configuration file does not already exist. In certain
7919 cases it is useful for there to be an example or template
7920 file which the maintainer scripts use. Such files should
7921 be in <file>/usr/share/<var>package</var></file> or
7922 <file>/usr/lib/<var>package</var></file> (depending on whether
7923 they are architecture-independent or not). There should
7924 be symbolic links to them from
7925 <file>/usr/share/doc/<var>package</var>/examples</file> if
7926 they are examples, and should be perfectly ordinary
7927 <prgn>dpkg</prgn>-handled files (<em>not</em>
7928 configuration files).
7932 These two styles of configuration file handling must
7933 not be mixed, for that way lies madness:
7934 <prgn>dpkg</prgn> will ask about overwriting the file
7935 every time the package is upgraded.
7940 <heading>Sharing configuration files</heading>
7943 Packages which specify the same file as a
7944 <tt>conffile</tt> must be tagged as <em>conflicting</em>
7945 with each other. (This is an instance of the general rule
7946 about not sharing files. Note that neither alternatives
7947 nor diversions are likely to be appropriate in this case;
7948 in particular, <prgn>dpkg</prgn> does not handle diverted
7949 <tt>conffile</tt>s well.)
7953 The maintainer scripts must not alter a <tt>conffile</tt>
7954 of <em>any</em> package, including the one the scripts
7959 If two or more packages use the same configuration file
7960 and it is reasonable for both to be installed at the same
7961 time, one of these packages must be defined as
7962 <em>owner</em> of the configuration file, i.e., it will be
7963 the package which handles that file as a configuration
7964 file. Other packages that use the configuration file must
7965 depend on the owning package if they require the
7966 configuration file to operate. If the other package will
7967 use the configuration file if present, but is capable of
7968 operating without it, no dependency need be declared.
7972 If it is desirable for two or more related packages to
7973 share a configuration file <em>and</em> for all of the
7974 related packages to be able to modify that configuration
7975 file, then the following should be done:
7976 <enumlist compact="compact">
7978 One of the related packages (the "owning" package)
7979 will manage the configuration file with maintainer
7980 scripts as described in the previous section.
7983 The owning package should also provide a program
7984 that the other packages may use to modify the
7988 The related packages must use the provided program
7989 to make any desired modifications to the
7990 configuration file. They should either depend on
7991 the core package to guarantee that the configuration
7992 modifier program is available or accept gracefully
7993 that they cannot modify the configuration file if it
7994 is not. (This is in addition to the fact that the
7995 configuration file may not even be present in the
8002 Sometimes it's appropriate to create a new package which
8003 provides the basic infrastructure for the other packages
8004 and which manages the shared configuration files. (The
8005 <tt>sgml-base</tt> package is a good example.)
8010 <heading>User configuration files ("dotfiles")</heading>
8013 The files in <file>/etc/skel</file> will automatically be
8014 copied into new user accounts by <prgn>adduser</prgn>.
8015 No other program should reference the files in
8016 <file>/etc/skel</file>.
8020 Therefore, if a program needs a dotfile to exist in
8021 advance in <file>$HOME</file> to work sensibly, that dotfile
8022 should be installed in <file>/etc/skel</file> and treated as a
8027 However, programs that require dotfiles in order to
8028 operate sensibly are a bad thing, unless they do create
8029 the dotfiles themselves automatically.
8033 Furthermore, programs should be configured by the Debian
8034 default installation to behave as closely to the upstream
8035 default behavior as possible.
8039 Therefore, if a program in a Debian package needs to be
8040 configured in some way in order to operate sensibly, that
8041 should be done using a site-wide configuration file placed
8042 in <file>/etc</file>. Only if the program doesn't support a
8043 site-wide default configuration and the package maintainer
8044 doesn't have time to add it may a default per-user file be
8045 placed in <file>/etc/skel</file>.
8049 <file>/etc/skel</file> should be as empty as we can make it.
8050 This is particularly true because there is no easy (or
8051 necessarily desirable) mechanism for ensuring that the
8052 appropriate dotfiles are copied into the accounts of
8053 existing users when a package is installed.
8059 <heading>Log files</heading>
8061 Log files should usually be named
8062 <file>/var/log/<var>package</var>.log</file>. If you have many
8063 log files, or need a separate directory for permission
8064 reasons (<file>/var/log</file> is writable only by
8065 <file>root</file>), you should usually create a directory named
8066 <file>/var/log/<var>package</var></file> and place your log
8071 Log files must be rotated occasionally so that they don't grow
8072 indefinitely. The best way to do this is to install a log
8073 rotation configuration file in the
8074 directory <file>/etc/logrotate.d</file>, normally
8075 named <file>/etc/logrotate.d/<var>package</var></file>, and use
8076 the facilities provided by <prgn>logrotate</prgn>.
8079 The traditional approach to log files has been to set up
8080 <em>ad hoc</em> log rotation schemes using simple shell
8081 scripts and cron. While this approach is highly
8082 customizable, it requires quite a lot of sysadmin work.
8083 Even though the original Debian system helped a little
8084 by automatically installing a system which can be used
8085 as a template, this was deemed not enough.
8089 The use of <prgn>logrotate</prgn>, a program developed
8090 by Red Hat, is better, as it centralizes log management.
8091 It has both a configuration file
8092 (<file>/etc/logrotate.conf</file>) and a directory where
8093 packages can drop their individual log rotation
8094 configurations (<file>/etc/logrotate.d</file>).
8097 Here is a good example for a logrotate config
8098 file (for more information see <manref name="logrotate"
8100 <example compact="compact">
8101 /var/log/foo/*.log {
8107 start-stop-daemon -K -p /var/run/foo.pid -s HUP -x /usr/sbin/foo -q
8111 This rotates all files under <file>/var/log/foo</file>, saves 12
8112 compressed generations, and tells the daemon to reopen its log
8113 files after the log rotation. It skips this log rotation
8114 (via <tt>missingok</tt>) if no such log file is present, which
8115 avoids errors if the package is removed but not purged.
8119 Log files should be removed when the package is
8120 purged (but not when it is only removed). This should be
8121 done by the <prgn>postrm</prgn> script when it is called
8122 with the argument <tt>purge</tt> (see <ref
8123 id="removedetails">).
8127 <sect id="permissions-owners">
8128 <heading>Permissions and owners</heading>
8131 The rules in this section are guidelines for general use.
8132 If necessary you may deviate from the details below.
8133 However, if you do so you must make sure that what is done
8134 is secure and you should try to be as consistent as possible
8135 with the rest of the system. You should probably also
8136 discuss it on <prgn>debian-devel</prgn> first.
8140 Files should be owned by <tt>root:root</tt>, and made
8141 writable only by the owner and universally readable (and
8142 executable, if appropriate), that is mode 644 or 755.
8146 Directories should be mode 755 or (for group-writability)
8147 mode 2775. The ownership of the directory should be
8148 consistent with its mode: if a directory is mode 2775, it
8149 should be owned by the group that needs write access to
8152 When a package is upgraded, and the owner or permissions
8153 of a file included in the package has changed, dpkg
8154 arranges for the ownership and permissions to be
8155 correctly set upon installation. However, this does not
8156 extend to directories; the permissions and ownership of
8157 directories already on the system does not change on
8158 install or upgrade of packages. This makes sense, since
8159 otherwise common directories like <tt>/usr</tt> would
8160 always be in flux. To correctly change permissions of a
8161 directory the package owns, explicit action is required,
8162 usually in the <tt>postinst</tt> script. Care must be
8163 taken to handle downgrades as well, in that case.
8169 Control information files should be owned by <tt>root:root</tt>
8170 and either mode 644 (for most files) or mode 755 (for
8171 executables such as <qref id="maintscripts">maintainer
8176 Setuid and setgid executables should be mode 4755 or 2755
8177 respectively, and owned by the appropriate user or group.
8178 They should not be made unreadable (modes like 4711 or
8179 2711 or even 4111); doing so achieves no extra security,
8180 because anyone can find the binary in the freely available
8181 Debian package; it is merely inconvenient. For the same
8182 reason you should not restrict read or execute permissions
8183 on non-set-id executables.
8187 Some setuid programs need to be restricted to particular
8188 sets of users, using file permissions. In this case they
8189 should be owned by the uid to which they are set-id, and by
8190 the group which should be allowed to execute them. They
8191 should have mode 4754; again there is no point in making
8192 them unreadable to those users who must not be allowed to
8197 It is possible to arrange that the system administrator can
8198 reconfigure the package to correspond to their local
8199 security policy by changing the permissions on a binary:
8200 they can do this by using <prgn>dpkg-statoverride</prgn>, as
8201 described below.<footnote>
8202 Ordinary files installed by <prgn>dpkg</prgn> (as
8203 opposed to <tt>conffile</tt>s and other similar objects)
8204 normally have their permissions reset to the distributed
8205 permissions when the package is reinstalled. However,
8206 the use of <prgn>dpkg-statoverride</prgn> overrides this
8209 Another method you should consider is to create a group for
8210 people allowed to use the program(s) and make any setuid
8211 executables executable only by that group.
8215 If you need to create a new user or group for your package
8216 there are two possibilities. Firstly, you may need to
8217 make some files in the binary package be owned by this
8218 user or group, or you may need to compile the user or
8219 group id (rather than just the name) into the binary
8220 (though this latter should be avoided if possible, as in
8221 this case you need a statically allocated id).</p>
8224 If you need a statically allocated id, you must ask for a
8225 user or group id from the <tt>base-passwd</tt> maintainer,
8226 and must not release the package until you have been
8227 allocated one. Once you have been allocated one you must
8228 either make the package depend on a version of the
8229 <tt>base-passwd</tt> package with the id present in
8230 <file>/etc/passwd</file> or <file>/etc/group</file>, or arrange for
8231 your package to create the user or group itself with the
8232 correct id (using <tt>adduser</tt>) in its
8233 <prgn>preinst</prgn> or <prgn>postinst</prgn>. (Doing it in
8234 the <prgn>postinst</prgn> is to be preferred if it is
8235 possible, otherwise a pre-dependency will be needed on the
8236 <tt>adduser</tt> package.)
8240 On the other hand, the program might be able to determine
8241 the uid or gid from the user or group name at runtime, so
8242 that a dynamically allocated id can be used. In this case
8243 you should choose an appropriate user or group name,
8244 discussing this on <prgn>debian-devel</prgn> and checking
8245 with the <package/base-passwd/ maintainer that it is unique and that
8246 they do not wish you to use a statically allocated id
8247 instead. When this has been checked you must arrange for
8248 your package to create the user or group if necessary using
8249 <prgn>adduser</prgn> in the <prgn>preinst</prgn> or
8250 <prgn>postinst</prgn> script (again, the latter is to be
8251 preferred if it is possible).
8255 Note that changing the numeric value of an id associated
8256 with a name is very difficult, and involves searching the
8257 file system for all appropriate files. You need to think
8258 carefully whether a static or dynamic id is required, since
8259 changing your mind later will cause problems.
8262 <sect1><heading>The use of <prgn>dpkg-statoverride</prgn></heading>
8264 This section is not intended as policy, but as a
8265 description of the use of <prgn>dpkg-statoverride</prgn>.
8269 If a system administrator wishes to have a file (or
8270 directory or other such thing) installed with owner and
8271 permissions different from those in the distributed Debian
8272 package, they can use the <prgn>dpkg-statoverride</prgn>
8273 program to instruct <prgn>dpkg</prgn> to use the different
8274 settings every time the file is installed. Thus the
8275 package maintainer should distribute the files with their
8276 normal permissions, and leave it for the system
8277 administrator to make any desired changes. For example, a
8278 daemon which is normally required to be setuid root, but
8279 in certain situations could be used without being setuid,
8280 should be installed setuid in the <tt>.deb</tt>. Then the
8281 local system administrator can change this if they wish.
8282 If there are two standard ways of doing it, the package
8283 maintainer can use <tt>debconf</tt> to find out the
8284 preference, and call <prgn>dpkg-statoverride</prgn> in the
8285 maintainer script if necessary to accommodate the system
8286 administrator's choice. Care must be taken during
8287 upgrades to not override an existing setting.
8291 Given the above, <prgn>dpkg-statoverride</prgn> is
8292 essentially a tool for system administrators and would not
8293 normally be needed in the maintainer scripts. There is
8294 one type of situation, though, where calls to
8295 <prgn>dpkg-statoverride</prgn> would be needed in the
8296 maintainer scripts, and that involves packages which use
8297 dynamically allocated user or group ids. In such a
8298 situation, something like the following idiom can be very
8299 helpful in the package's <prgn>postinst</prgn>, where
8300 <tt>sysuser</tt> is a dynamically allocated id:
8302 for i in /usr/bin/foo /usr/sbin/bar
8304 # only do something when no setting exists
8305 if ! dpkg-statoverride --list $i >/dev/null 2>&1
8307 #include: debconf processing, question about foo and bar
8308 if [ "$RET" = "true" ] ; then
8309 dpkg-statoverride --update --add sysuser root 4755 $i
8314 The corresponding code to remove the override when the package
8317 for i in /usr/bin/foo /usr/sbin/bar
8319 if dpkg-statoverride --list $i >/dev/null 2>&1
8321 dpkg-statoverride --remove $i
8331 <chapt id="customized-programs">
8332 <heading>Customized programs</heading>
8334 <sect id="arch-spec">
8335 <heading>Architecture specification strings</heading>
8338 If a program needs to specify an <em>architecture specification
8339 string</em> in some place, it should select one of the strings
8340 provided by <tt>dpkg-architecture -L</tt>. The strings are in
8341 the format <tt><var>os</var>-<var>arch</var></tt>, though the OS
8342 part is sometimes elided, as when the OS is Linux.
8346 Note that we don't want to use
8347 <tt><var>arch</var>-debian-linux</tt> to apply to the rule
8348 <tt><var>architecture</var>-<var>vendor</var>-<var>os</var></tt>
8349 since this would make our programs incompatible with other
8350 Linux distributions. We also don't use something like
8351 <tt><var>arch</var>-unknown-linux</tt>, since the
8352 <tt>unknown</tt> does not look very good.
8355 <sect1 id="arch-wildcard-spec">
8356 <heading>Architecture wildcards</heading>
8359 A package may specify an architecture wildcard. Architecture
8360 wildcards are in the format <tt>any</tt> (which matches every
8361 architecture), <tt><var>os</var></tt>-any, or
8362 any-<tt><var>cpu</var></tt>. <footnote>
8363 Internally, the package system normalizes the GNU triplets
8364 and the Debian arches into Debian arch triplets (which are
8365 kind of inverted GNU triplets), with the first component of
8366 the triplet representing the libc and ABI in use, and then
8367 does matching against those triplets. However, such
8368 triplets are an internal implementation detail that should
8369 not be used by packages directly. The libc and ABI portion
8370 is handled internally by the package system based on
8371 the <var>os</var> and <var>cpu</var>.
8378 <heading>Daemons</heading>
8381 The configuration files <file>/etc/services</file>,
8382 <file>/etc/protocols</file>, and <file>/etc/rpc</file> are managed
8383 by the <prgn>netbase</prgn> package and must not be modified
8388 If a package requires a new entry in one of these files, the
8389 maintainer should get in contact with the
8390 <prgn>netbase</prgn> maintainer, who will add the entries
8391 and release a new version of the <prgn>netbase</prgn>
8396 The configuration file <file>/etc/inetd.conf</file> must not be
8397 modified by the package's scripts except via the
8398 <prgn>update-inetd</prgn> script or the
8399 <file>DebianNet.pm</file> Perl module. See their documentation
8400 for details on how to add entries.
8404 If a package wants to install an example entry into
8405 <file>/etc/inetd.conf</file>, the entry must be preceded with
8406 exactly one hash character (<tt>#</tt>). Such lines are
8407 treated as "commented out by user" by the
8408 <prgn>update-inetd</prgn> script and are not changed or
8409 activated during package updates.
8414 <heading>Using pseudo-ttys and modifying wtmp, utmp and
8418 Some programs need to create pseudo-ttys. This should be done
8419 using Unix98 ptys if the C library supports it. The resulting
8420 program must not be installed setuid root, unless that
8421 is required for other functionality.
8425 The files <file>/var/run/utmp</file>, <file>/var/log/wtmp</file> and
8426 <file>/var/log/lastlog</file> must be installed writable by
8427 group <tt>utmp</tt>. Programs which need to modify those
8428 files must be installed setgid <tt>utmp</tt>.
8433 <heading>Editors and pagers</heading>
8436 Some programs have the ability to launch an editor or pager
8437 program to edit or display a text document. Since there are
8438 lots of different editors and pagers available in the Debian
8439 distribution, the system administrator and each user should
8440 have the possibility to choose their preferred editor and
8445 In addition, every program should choose a good default
8446 editor/pager if none is selected by the user or system
8451 Thus, every program that launches an editor or pager must
8452 use the EDITOR or PAGER environment variable to determine
8453 the editor or pager the user wishes to use. If these
8454 variables are not set, the programs <file>/usr/bin/editor</file>
8455 and <file>/usr/bin/pager</file> should be used, respectively.
8459 These two files are managed through the <prgn>dpkg</prgn>
8460 "alternatives" mechanism. Every package providing an editor or
8461 pager must call the <prgn>update-alternatives</prgn> script to
8462 register as an alternative for <file>/usr/bin/editor</file>
8463 or <file>/usr/bin/pager</file> as appropriate. The alternative
8464 should have a slave alternative
8465 for <file>/usr/share/man/man1/editor.1.gz</file>
8466 or <file>/usr/share/man/man1/pager.1.gz</file> pointing to the
8467 corresponding manual page.
8471 If it is very hard to adapt a program to make use of the
8472 EDITOR or PAGER variables, that program may be configured to
8473 use <file>/usr/bin/sensible-editor</file> and
8474 <file>/usr/bin/sensible-pager</file> as the editor or pager
8475 program respectively. These are two scripts provided in the
8476 <package>sensible-utils</package> package that check the EDITOR
8477 and PAGER variables and launch the appropriate program, and fall
8478 back to <file>/usr/bin/editor</file>
8479 and <file>/usr/bin/pager</file> if the variable is not set.
8483 A program may also use the VISUAL environment variable to
8484 determine the user's choice of editor. If it exists, it
8485 should take precedence over EDITOR. This is in fact what
8486 <file>/usr/bin/sensible-editor</file> does.
8490 It is not required for a package to depend on
8491 <tt>editor</tt> and <tt>pager</tt>, nor is it required for a
8492 package to provide such virtual packages.<footnote>
8493 The Debian base system already provides an editor and a
8499 <sect id="web-appl">
8500 <heading>Web servers and applications</heading>
8503 This section describes the locations and URLs that should
8504 be used by all web servers and web applications in the
8511 Cgi-bin executable files are installed in the
8513 <example compact="compact">
8514 /usr/lib/cgi-bin/<var>cgi-bin-name</var>
8516 or a subdirectory of that directory, and should be
8518 <example compact="compact">
8519 http://localhost/cgi-bin/<var>cgi-bin-name</var>
8521 (possibly with a subdirectory name
8522 before <var>cgi-bin-name</var>).
8526 <p>Access to HTML documents</p>
8529 HTML documents for a package are stored in
8530 <file>/usr/share/doc/<var>package</var></file>
8531 and can be referred to as
8532 <example compact="compact">
8533 http://localhost/doc/<var>package</var>/<var>filename</var>
8538 The web server should restrict access to the document
8539 tree so that only clients on the same host can read
8540 the documents. If the web server does not support such
8541 access controls, then it should not provide access at
8542 all, or ask about providing access during installation.
8547 <p>Access to images</p>
8549 It is recommended that images for a package be stored
8550 in <tt>/usr/share/images/<var>package</var></tt> and
8551 may be referred to through an alias <tt>/images/</tt>
8554 http://localhost/images/<package>/<filename>
8561 <p>Web Document Root</p>
8564 Web Applications should try to avoid storing files in
8565 the Web Document Root. Instead they should use the
8566 /usr/share/doc/<var>package</var> directory for
8567 documents and register the Web Application via the
8568 <package>doc-base</package> package. If access to the
8569 web document root is unavoidable then use
8570 <example compact="compact">
8573 as the Document Root. This might be just a symbolic
8574 link to the location where the system administrator
8575 has put the real document root.
8578 <item><p>Providing httpd and/or httpd-cgi</p>
8580 All web servers should provide the virtual package
8581 <tt>httpd</tt>. If a web server has CGI support it should
8582 provide <tt>httpd-cgi</tt> additionally.
8585 All web applications which do not contain CGI scripts should
8586 depend on <tt>httpd</tt>, all those web applications which
8587 <tt>do</tt> contain CGI scripts, should depend on
8595 <sect id="mail-transport-agents">
8596 <heading>Mail transport, delivery and user agents</heading>
8599 Debian packages which process electronic mail, whether mail
8600 user agents (MUAs) or mail transport agents (MTAs), must
8601 ensure that they are compatible with the configuration
8602 decisions below. Failure to do this may result in lost
8603 mail, broken <tt>From:</tt> lines, and other serious brain
8608 The mail spool is <file>/var/mail</file> and the interface to
8609 send a mail message is <file>/usr/sbin/sendmail</file> (as per
8610 the FHS). On older systems, the mail spool may be
8611 physically located in <file>/var/spool/mail</file>, but all
8612 access to the mail spool should be via the
8613 <file>/var/mail</file> symlink. The mail spool is part of the
8614 base system and not part of the MTA package.
8618 All Debian MUAs, MTAs, MDAs and other mailbox accessing
8619 programs (such as IMAP daemons) must lock the mailbox in an
8620 NFS-safe way. This means that <tt>fcntl()</tt> locking must
8621 be combined with dot locking. To avoid deadlocks, a program
8622 should use <tt>fcntl()</tt> first and dot locking after
8623 this, or alternatively implement the two locking methods in
8624 a non blocking way<footnote>
8625 If it is not possible to establish both locks, the
8626 system shouldn't wait for the second lock to be
8627 established, but remove the first lock, wait a (random)
8628 time, and start over locking again.
8629 </footnote>. Using the functions <tt>maillock</tt> and
8630 <tt>mailunlock</tt> provided by the
8631 <tt>liblockfile*</tt><footnote>
8632 You will need to depend on <tt>liblockfile1 (>>1.01)</tt>
8633 to use these functions.
8634 </footnote> packages is the recommended way to realize this.
8638 Mailboxes are generally either mode 600 and owned by
8639 <var>user</var> or mode 660 and owned by
8640 <tt><var>user</var>:mail</tt><footnote>
8641 There are two traditional permission schemes for mail spools:
8642 mode 600 with all mail delivery done by processes running as
8643 the destination user, or mode 660 and owned by group mail with
8644 mail delivery done by a process running as a system user in
8645 group mail. Historically, Debian required mode 660 mail
8646 spools to enable the latter model, but that model has become
8647 increasingly uncommon and the principle of least privilege
8648 indicates that mail systems that use the first model should
8649 use permissions of 600. If delivery to programs is permitted,
8650 it's easier to keep the mail system secure if the delivery
8651 agent runs as the destination user. Debian Policy therefore
8652 permits either scheme.
8653 </footnote>. The local system administrator may choose a
8654 different permission scheme; packages should not make
8655 assumptions about the permission and ownership of mailboxes
8656 unless required (such as when creating a new mailbox). A MUA
8657 may remove a mailbox (unless it has nonstandard permissions) in
8658 which case the MTA or another MUA must recreate it if needed.
8662 The mail spool is 2775 <tt>root:mail</tt>, and MUAs should
8663 be setgid mail to do the locking mentioned above (and
8664 must obviously avoid accessing other users' mailboxes
8665 using this privilege).</p>
8668 <file>/etc/aliases</file> is the source file for the system mail
8669 aliases (e.g., postmaster, usenet, etc.), it is the one
8670 which the sysadmin and <prgn>postinst</prgn> scripts may
8671 edit. After <file>/etc/aliases</file> is edited the program or
8672 human editing it must call <prgn>newaliases</prgn>. All MTA
8673 packages must come with a <prgn>newaliases</prgn> program,
8674 even if it does nothing, but older MTA packages did not do
8675 this so programs should not fail if <prgn>newaliases</prgn>
8676 cannot be found. Note that because of this, all MTA
8677 packages must have <tt>Provides</tt>, <tt>Conflicts</tt> and
8678 <tt>Replaces: mail-transport-agent</tt> control fields.
8682 The convention of writing <tt>forward to
8683 <var>address</var></tt> in the mailbox itself is not
8684 supported. Use a <tt>.forward</tt> file instead.</p>
8687 The <prgn>rmail</prgn> program used by UUCP
8688 for incoming mail should be <file>/usr/sbin/rmail</file>.
8689 Likewise, <prgn>rsmtp</prgn>, for receiving
8690 batch-SMTP-over-UUCP, should be <file>/usr/sbin/rsmtp</file> if it
8694 If your package needs to know what hostname to use on (for
8695 example) outgoing news and mail messages which are generated
8696 locally, you should use the file <file>/etc/mailname</file>. It
8697 will contain the portion after the username and <tt>@</tt>
8698 (at) sign for email addresses of users on the machine
8699 (followed by a newline).
8703 Such a package should check for the existence of this file
8704 when it is being configured. If it exists, it should be
8705 used without comment, although an MTA's configuration script
8706 may wish to prompt the user even if it finds that this file
8707 exists. If the file does not exist, the package should
8708 prompt the user for the value (preferably using
8709 <prgn>debconf</prgn>) and store it in <file>/etc/mailname</file>
8710 as well as using it in the package's configuration. The
8711 prompt should make it clear that the name will not just be
8712 used by that package. For example, in this situation the
8713 <tt>inn</tt> package could say something like:
8714 <example compact="compact">
8715 Please enter the "mail name" of your system. This is the
8716 hostname portion of the address to be shown on outgoing
8717 news and mail messages. The default is
8718 <var>syshostname</var>, your system's host name. Mail
8719 name ["<var>syshostname</var>"]:
8721 where <var>syshostname</var> is the output of <tt>hostname
8727 <heading>News system configuration</heading>
8730 All the configuration files related to the NNTP (news)
8731 servers and clients should be located under
8732 <file>/etc/news</file>.</p>
8735 There are some configuration issues that apply to a number
8736 of news clients and server packages on the machine. These
8740 <tag><file>/etc/news/organization</file></tag>
8742 A string which should appear as the
8743 organization header for all messages posted
8744 by NNTP clients on the machine
8747 <tag><file>/etc/news/server</file></tag>
8749 Contains the FQDN of the upstream NNTP
8750 server, or localhost if the local machine is
8755 Other global files may be added as required for cross-package news
8762 <heading>Programs for the X Window System</heading>
8765 <heading>Providing X support and package priorities</heading>
8768 Programs that can be configured with support for the X
8769 Window System must be configured to do so and must declare
8770 any package dependencies necessary to satisfy their
8771 runtime requirements when using the X Window System. If
8772 such a package is of higher priority than the X packages
8773 on which it depends, it is required that either the
8774 X-specific components be split into a separate package, or
8775 that an alternative version of the package, which includes
8776 X support, be provided, or that the package's priority be
8782 <heading>Packages providing an X server</heading>
8785 Packages that provide an X server that, directly or
8786 indirectly, communicates with real input and display
8787 hardware should declare in their <tt>Provides</tt> control
8788 field that they provide the virtual
8789 package <tt>xserver</tt>.<footnote>
8790 This implements current practice, and provides an
8791 actual policy for usage of the <tt>xserver</tt>
8792 virtual package which appears in the virtual packages
8793 list. In a nutshell, X servers that interface
8794 directly with the display and input hardware or via
8795 another subsystem (e.g., GGI) should provide
8796 <tt>xserver</tt>. Things like <tt>Xvfb</tt>,
8797 <tt>Xnest</tt>, and <tt>Xprt</tt> should not.
8803 <heading>Packages providing a terminal emulator</heading>
8806 Packages that provide a terminal emulator for the X Window
8807 System which meet the criteria listed below should declare in
8808 their <tt>Provides</tt> control field that they provide the
8809 virtual package <tt>x-terminal-emulator</tt>. They should
8810 also register themselves as an alternative for
8811 <file>/usr/bin/x-terminal-emulator</file>, with a priority of
8812 20. That alternative should have a slave alternative
8813 for <file>/usr/share/man/man1/x-terminal-emulator.1.gz</file>
8814 pointing to the corresponding manual page.
8818 To be an <tt>x-terminal-emulator</tt>, a program must:
8819 <list compact="compact">
8821 Be able to emulate a DEC VT100 terminal, or a
8822 compatible terminal.
8826 Support the command-line option <tt>-e
8827 <var>command</var></tt>, which creates a new
8828 terminal window<footnote>
8829 "New terminal window" does not necessarily mean
8830 a new top-level X window directly parented by
8831 the window manager; it could, if the terminal
8832 emulator application were so coded, be a new
8833 "view" in a multiple-document interface (MDI).
8835 and runs the specified <var>command</var>,
8836 interpreting the entirety of the rest of the command
8837 line as a command to pass straight to exec, in the
8838 manner that <tt>xterm</tt> does.
8842 Support the command-line option <tt>-T
8843 <var>title</var></tt>, which creates a new terminal
8844 window with the window title <var>title</var>.
8851 <heading>Packages providing a window manager</heading>
8854 Packages that provide a window manager should declare in
8855 their <tt>Provides</tt> control field that they provide the
8856 virtual package <tt>x-window-manager</tt>. They should also
8857 register themselves as an alternative for
8858 <file>/usr/bin/x-window-manager</file>, with a priority
8859 calculated as follows:
8860 <list compact="compact">
8862 Start with a priority of 20.
8866 If the window manager supports the Debian menu
8867 system, add 20 points if this support is available
8868 in the package's default configuration (i.e., no
8869 configuration files belonging to the system or user
8870 have to be edited to activate the feature); if
8871 configuration files must be modified, add only 10
8877 If the window manager complies with <url
8878 id="http://www.freedesktop.org/Standards/wm-spec"
8879 name="The Window Manager Specification Project">,
8880 written by the <url id="http://www.freedesktop.org/"
8881 name="Free Desktop Group">, add 40 points.
8885 If the window manager permits the X session to be
8886 restarted using a <em>different</em> window manager
8887 (without killing the X server) in its default
8888 configuration, add 10 points; otherwise add none.
8891 That alternative should have a slave alternative
8892 for <file>/usr/share/man/man1/x-window-manager.1.gz</file>
8893 pointing to the corresponding manual page.
8898 <heading>Packages providing fonts</heading>
8901 Packages that provide fonts for the X Window
8903 For the purposes of Debian Policy, a "font for the X
8904 Window System" is one which is accessed via X protocol
8905 requests. Fonts for the Linux console, for PostScript
8906 renderer, or any other purpose, do not fit this
8907 definition. Any tool which makes such fonts available
8908 to the X Window System, however, must abide by this
8911 must do a number of things to ensure that they are both
8912 available without modification of the X or font server
8913 configuration, and that they do not corrupt files used by
8914 other font packages to register information about
8918 Fonts of any type supported by the X Window System
8919 must be in a separate binary package from any
8920 executables, libraries, or documentation (except
8921 that specific to the fonts shipped, such as their
8922 license information). If one or more of the fonts
8923 so packaged are necessary for proper operation of
8924 the package with which they are associated the font
8925 package may be Recommended; if the fonts merely
8926 provide an enhancement, a Suggests relationship may
8927 be used. Packages must not Depend on font
8929 This is because the X server may retrieve fonts
8930 from the local file system or over the network
8931 from an X font server; the Debian package system
8932 is empowered to deal only with the local
8938 BDF fonts must be converted to PCF fonts with the
8939 <prgn>bdftopcf</prgn> utility (available in the
8940 <tt>xfonts-utils</tt> package, <prgn>gzip</prgn>ped, and
8941 placed in a directory that corresponds to their
8943 <list compact="compact">
8945 100 dpi fonts must be placed in
8946 <file>/usr/share/fonts/X11/100dpi/</file>.
8950 75 dpi fonts must be placed in
8951 <file>/usr/share/fonts/X11/75dpi/</file>.
8955 Character-cell fonts, cursor fonts, and other
8956 low-resolution fonts must be placed in
8957 <file>/usr/share/fonts/X11/misc/</file>.
8963 Type 1 fonts must be placed in
8964 <file>/usr/share/fonts/X11/Type1/</file>. If font
8965 metric files are available, they must be placed here
8970 Subdirectories of <file>/usr/share/fonts/X11/</file>
8971 other than those listed above must be neither
8972 created nor used. (The <file>PEX</file>, <file>CID</file>,
8973 <file>Speedo</file>, and <file>cyrillic</file> directories
8974 are excepted for historical reasons, but installation of
8975 files into these directories remains discouraged.)
8979 Font packages may, instead of placing files directly
8980 in the X font directories listed above, provide
8981 symbolic links in that font directory pointing to
8982 the files' actual location in the filesystem. Such
8983 a location must comply with the FHS.
8987 Font packages should not contain both 75dpi and
8988 100dpi versions of a font. If both are available,
8989 they should be provided in separate binary packages
8990 with <tt>-75dpi</tt> or <tt>-100dpi</tt> appended to
8991 the names of the packages containing the
8992 corresponding fonts.
8996 Fonts destined for the <file>misc</file> subdirectory
8997 should not be included in the same package as 75dpi
8998 or 100dpi fonts; instead, they should be provided in
8999 a separate package with <tt>-misc</tt> appended to
9004 Font packages must not provide the files
9005 <file>fonts.dir</file>, <file>fonts.alias</file>, or
9006 <file>fonts.scale</file> in a font directory:
9009 <file>fonts.dir</file> files must not be provided at all.
9013 <file>fonts.alias</file> and <file>fonts.scale</file>
9014 files, if needed, should be provided in the
9016 <file>/etc/X11/fonts/<var>fontdir</var>/<var>package</var>.<var>extension</var></file>,
9017 where <var>fontdir</var> is the name of the
9019 <file>/usr/share/fonts/X11/</file> where the
9020 package's corresponding fonts are stored
9021 (e.g., <tt>75dpi</tt> or <tt>misc</tt>),
9022 <var>package</var> is the name of the package
9023 that provides these fonts, and
9024 <var>extension</var> is either <tt>scale</tt>
9025 or <tt>alias</tt>, whichever corresponds to
9032 Font packages must declare a dependency on
9033 <tt>xfonts-utils</tt> in their <tt>Depends</tt>
9034 or <tt>Pre-Depends</tt> control field.
9038 Font packages that provide one or more
9039 <file>fonts.scale</file> files as described above must
9040 invoke <prgn>update-fonts-scale</prgn> on each
9041 directory into which they installed fonts
9042 <em>before</em> invoking
9043 <prgn>update-fonts-dir</prgn> on that directory.
9044 This invocation must occur in both the
9045 <prgn>postinst</prgn> (for all arguments) and
9046 <prgn>postrm</prgn> (for all arguments except
9047 <tt>upgrade</tt>) scripts.
9051 Font packages that provide one or more
9052 <file>fonts.alias</file> files as described above must
9053 invoke <prgn>update-fonts-alias</prgn> on each
9054 directory into which they installed fonts. This
9055 invocation must occur in both the
9056 <prgn>postinst</prgn> (for all arguments) and
9057 <prgn>postrm</prgn> (for all arguments except
9058 <tt>upgrade</tt>) scripts.
9062 Font packages must invoke
9063 <prgn>update-fonts-dir</prgn> on each directory into
9064 which they installed fonts. This invocation must
9065 occur in both the <prgn>postinst</prgn> (for all
9066 arguments) and <prgn>postrm</prgn> (for all
9067 arguments except <tt>upgrade</tt>) scripts.
9071 Font packages must not provide alias names for the
9072 fonts they include which collide with alias names
9073 already in use by fonts already packaged.
9077 Font packages must not provide fonts with the same
9078 XLFD registry name as another font already packaged.
9084 <sect1 id="appdefaults">
9085 <heading>Application defaults files</heading>
9088 Application defaults files must be installed in the
9089 directory <file>/etc/X11/app-defaults/</file> (use of a
9090 localized subdirectory of <file>/etc/X11/</file> as described
9091 in the <em>X Toolkit Intrinsics - C Language
9092 Interface</em> manual is also permitted). They must be
9093 registered as <tt>conffile</tt>s or handled as
9094 configuration files.
9098 Customization of programs' X resources may also be
9099 supported with the provision of a file with the same name
9100 as that of the package placed in
9101 the <file>/etc/X11/Xresources/</file> directory, which
9102 must be registered as a <tt>conffile</tt> or handled as a
9103 configuration file.<footnote>
9104 Note that this mechanism is not the same as using
9105 app-defaults; app-defaults are tied to the client
9106 binary on the local file system, whereas X resources
9107 are stored in the X server and affect all connecting
9114 <heading>Installation directory issues</heading>
9117 Historically, packages using the X Window System used a
9118 separate set of installation directories from other packages.
9119 This practice has been discontinued and packages using the X
9120 Window System should now generally be installed in the same
9121 directories as any other package. Specifically, packages must
9122 not install files under the <file>/usr/X11R6/</file> directory
9123 and the <file>/usr/X11R6/</file> directory hierarchy should be
9124 regarded as obsolete.
9128 Include files previously installed under
9129 <file>/usr/X11R6/include/X11/</file> should be installed into
9130 <file>/usr/include/X11/</file>. For files previously
9131 installed into subdirectories of
9132 <file>/usr/X11R6/lib/X11/</file>, package maintainers should
9133 determine if subdirectories of <file>/usr/lib/</file> and
9134 <file>/usr/share/</file> can be used. If not, a subdirectory
9135 of <file>/usr/lib/X11/</file> should be used.
9139 Configuration files for window, display, or session managers
9140 or other applications that are tightly integrated with the X
9141 Window System may be placed in a subdirectory
9142 of <file>/etc/X11/</file> corresponding to the package name.
9143 Other X Window System applications should use
9144 the <file>/etc/</file> directory unless otherwise mandated by
9145 policy (such as for <ref id="appdefaults">).
9150 <heading>The OSF/Motif and OpenMotif libraries</heading>
9153 <em>Programs that require the non-DFSG-compliant OSF/Motif or
9154 OpenMotif libraries</em><footnote>
9155 OSF/Motif and OpenMotif are collectively referred to as
9156 "Motif" in this policy document.
9158 should be compiled against and tested with LessTif (a free
9159 re-implementation of Motif) instead. If the maintainer
9160 judges that the program or programs do not work
9161 sufficiently well with LessTif to be distributed and
9162 supported, but do so when compiled against Motif, then two
9163 versions of the package should be created; one linked
9164 statically against Motif and with <tt>-smotif</tt>
9165 appended to the package name, and one linked dynamically
9166 against Motif and with <tt>-dmotif</tt> appended to the
9171 Both Motif-linked versions are dependent
9172 upon non-DFSG-compliant software and thus cannot be
9173 uploaded to the <em>main</em> distribution; if the
9174 software is itself DFSG-compliant it may be uploaded to
9175 the <em>contrib</em> distribution. While known existing
9176 versions of Motif permit unlimited redistribution of
9177 binaries linked against the library (whether statically or
9178 dynamically), it is the package maintainer's
9179 responsibility to determine whether this is permitted by
9180 the license of the copy of Motif in their possession.
9186 <heading>Perl programs and modules</heading>
9189 Perl programs and modules should follow the current Perl policy.
9193 The Perl policy can be found in the <tt>perl-policy</tt>
9194 files in the <tt>debian-policy</tt> package.
9195 It is also available from the Debian web mirrors at
9196 <tt><url name="/doc/packaging-manuals/perl-policy/"
9197 id="http://www.debian.org/doc/packaging-manuals/perl-policy/"></tt>.
9202 <heading>Emacs lisp programs</heading>
9205 Please refer to the "Debian Emacs Policy" for details of how to
9206 package emacs lisp programs.
9210 The Emacs policy is available in
9211 <file>debian-emacs-policy.gz</file> of the
9212 <package>emacsen-common</package> package.
9213 It is also available from the Debian web mirrors at
9214 <tt><url name="/doc/packaging-manuals/debian-emacs-policy"
9215 id="http://www.debian.org/doc/packaging-manuals/debian-emacs-policy"></tt>.
9220 <heading>Games</heading>
9223 The permissions on <file>/var/games</file> are mode 755, owner
9224 <tt>root</tt> and group <tt>root</tt>.
9228 Each game decides on its own security policy.</p>
9231 Games which require protected, privileged access to
9232 high-score files, saved games, etc., may be made
9233 set-<em>group</em>-id (mode 2755) and owned by
9234 <tt>root:games</tt>, and use files and directories with
9235 appropriate permissions (770 <tt>root:games</tt>, for
9236 example). They must not be made
9237 set-<em>user</em>-id, as this causes security problems. (If
9238 an attacker can subvert any set-user-id game they can
9239 overwrite the executable of any other, causing other players
9240 of these games to run a Trojan horse program. With a
9241 set-group-id game the attacker only gets access to less
9242 important game data, and if they can get at the other
9243 players' accounts at all it will take considerably more
9247 Some packages, for example some fortune cookie programs, are
9248 configured by the upstream authors to install with their
9249 data files or other static information made unreadable so
9250 that they can only be accessed through set-id programs
9251 provided. You should not do this in a Debian package: anyone can
9252 download the <file>.deb</file> file and read the data from it,
9253 so there is no point making the files unreadable. Not
9254 making the files unreadable also means that you don't have
9255 to make so many programs set-id, which reduces the risk of a
9259 As described in the FHS, binaries of games should be
9260 installed in the directory <file>/usr/games</file>. This also
9261 applies to games that use the X Window System. Manual pages
9262 for games (X and non-X games) should be installed in
9263 <file>/usr/share/man/man6</file>.</p>
9269 <heading>Documentation</heading>
9272 <heading>Manual pages</heading>
9275 You should install manual pages in <prgn>nroff</prgn> source
9276 form, in appropriate places under <file>/usr/share/man</file>.
9277 You should only use sections 1 to 9 (see the FHS for more
9278 details). You must not install a pre-formatted "cat page".
9282 Each program, utility, and function should have an
9283 associated manual page included in the same package. It is
9284 suggested that all configuration files also have a manual
9285 page included as well. Manual pages for protocols and other
9286 auxiliary things are optional.
9290 If no manual page is available, this is considered as a bug
9291 and should be reported to the Debian Bug Tracking System (the
9292 maintainer of the package is allowed to write this bug report
9293 themselves, if they so desire). Do not close the bug report
9294 until a proper man page is available.<footnote>
9295 It is not very hard to write a man page. See the
9296 <url id="http://www.schweikhardt.net/man_page_howto.html"
9297 name="Man-Page-HOWTO">,
9298 <manref name="man" section="7">, the examples
9299 created by <prgn>debmake</prgn> or <prgn>dh_make</prgn>,
9300 the helper program <prgn>help2man</prgn>, or the
9301 directory <file>/usr/share/doc/man-db/examples</file>.
9306 You may forward a complaint about a missing man page to the
9307 upstream authors, and mark the bug as forwarded in the
9308 Debian bug tracking system. Even though the GNU Project do
9309 not in general consider the lack of a man page to be a bug,
9310 we do; if they tell you that they don't consider it a bug
9311 you should leave the bug in our bug tracking system open
9316 Manual pages should be installed compressed using <tt>gzip -9</tt>.
9320 If one man page needs to be accessible via several names it
9321 is better to use a symbolic link than the <file>.so</file>
9322 feature, but there is no need to fiddle with the relevant
9323 parts of the upstream source to change from <file>.so</file> to
9324 symlinks: don't do it unless it's easy. You should not
9325 create hard links in the manual page directories, nor put
9326 absolute filenames in <file>.so</file> directives. The filename
9327 in a <file>.so</file> in a man page should be relative to the
9328 base of the man page tree (usually
9329 <file>/usr/share/man</file>). If you do not create any links
9330 (whether symlinks, hard links, or <tt>.so</tt> directives)
9331 in the file system to the alternate names of the man page,
9332 then you should not rely on <prgn>man</prgn> finding your
9333 man page under those names based solely on the information in
9334 the man page's header.<footnote>
9335 Supporting this in <prgn>man</prgn> often requires
9336 unreasonable processing time to find a manual page or to
9337 report that none exists, and moves knowledge into man's
9338 database that would be better left in the file system.
9339 This support is therefore deprecated and will cease to
9340 be present in the future.
9345 Manual pages in locale-specific subdirectories of
9346 <file>/usr/share/man</file> should use either UTF-8 or the usual
9347 legacy encoding for that language (normally the one corresponding
9348 to the shortest relevant locale name in
9349 <file>/usr/share/i18n/SUPPORTED</file>). For example, pages under
9350 <file>/usr/share/man/fr</file> should use either UTF-8 or
9351 ISO-8859-1.<footnote>
9352 <prgn>man</prgn> will automatically detect whether UTF-8 is in
9353 use. In future, all manual pages will be required to use
9359 A country name (the <tt>DE</tt> in <tt>de_DE</tt>) should not be
9360 included in the subdirectory name unless it indicates a
9361 significant difference in the language, as this excludes
9362 speakers of the language in other countries.<footnote>
9363 At the time of writing, Chinese and Portuguese are the main
9364 languages with such differences, so <file>pt_BR</file>,
9365 <file>zh_CN</file>, and <file>zh_TW</file> are all allowed.
9370 If a localized version of a manual page is provided, it should
9371 either be up-to-date or it should be obvious to the reader that
9372 it is outdated and the original manual page should be used
9373 instead. This can be done either by a note at the beginning of
9374 the manual page or by showing the missing or changed portions in
9375 the original language instead of the target language.
9380 <heading>Info documents</heading>
9383 Info documents should be installed in <file>/usr/share/info</file>.
9384 They should be compressed with <tt>gzip -9</tt>.
9388 The <prgn>install-info</prgn> program maintains a directory of
9389 installed info documents in <file>/usr/share/info/dir</file> for
9390 the use of info readers.<footnote>
9391 It was previously necessary for packages installing info
9392 documents to run <prgn>install-info</prgn> from maintainer
9393 scripts. This is no longer necessary. The installation
9394 system now uses dpkg triggers.
9396 This file must not be included in packages. Packages containing
9397 info documents should depend on <tt>dpkg (>= 1.15.4) |
9398 install-info</tt> to ensure that the directory file is properly
9399 rebuilt during partial upgrades from Debian 5.0 (lenny) and
9404 Info documents should contain section and directory entry
9405 information in the document for the use
9406 of <prgn>install-info</prgn>. The section should be specified
9407 via a line starting with <tt>INFO-DIR-SECTION</tt> followed by a
9408 space and the section of this info page. The directory entry or
9409 entries should be included between
9410 a <tt>START-INFO-DIR-ENTRY</tt> line and
9411 an <tt>END-INFO-DIR-ENTRY</tt> line. For example:
9413 INFO-DIR-SECTION Individual utilities
9414 START-INFO-DIR-ENTRY
9415 * example: (example). An example info directory entry.
9418 To determine which section to use, you should look
9419 at <file>/usr/share/info/dir</file> on your system and choose
9420 the most relevant (or create a new section if none of the
9421 current sections are relevant).<footnote>
9422 Normally, info documents are generated from Texinfo source.
9423 To include this information in the generated info document, if
9424 it is absent, add commands like:
9426 @dircategory Individual utilities
9428 * example: (example). An example info directory entry.
9431 to the Texinfo source of the document and ensure that the info
9432 documents are rebuilt from source during the package build.
9438 <heading>Additional documentation</heading>
9441 Any additional documentation that comes with the package may
9442 be installed at the discretion of the package maintainer.
9443 Plain text documentation should be installed in the directory
9444 <file>/usr/share/doc/<var>package</var></file>, where
9445 <var>package</var> is the name of the package, and
9446 compressed with <tt>gzip -9</tt> unless it is small.
9450 If a package comes with large amounts of documentation which
9451 many users of the package will not require you should create
9452 a separate binary package to contain it, so that it does not
9453 take up disk space on the machines of users who do not need
9454 or want it installed.</p>
9457 It is often a good idea to put text information files
9458 (<file>README</file>s, changelogs, and so forth) that come with
9459 the source package in <file>/usr/share/doc/<var>package</var></file>
9460 in the binary package. However, you don't need to install
9461 the instructions for building and installing the package, of
9465 Packages must not require the existence of any files in
9466 <file>/usr/share/doc/</file> in order to function
9468 The system administrator should be able to
9469 delete files in <file>/usr/share/doc/</file> without causing
9470 any programs to break.
9472 Any files that are referenced by programs but are also
9473 useful as stand alone documentation should be installed under
9474 <file>/usr/share/<var>package</var>/</file> with symbolic links from
9475 <file>/usr/share/doc/<var>package</var></file>.
9479 <file>/usr/share/doc/<var>package</var></file> may be a symbolic
9480 link to another directory in <file>/usr/share/doc</file> only if
9481 the two packages both come from the same source and the
9482 first package Depends on the second.<footnote>
9484 Please note that this does not override the section on
9485 changelog files below, so the file
9486 <file>/usr/share/doc/<var>package</var>/changelog.Debian.gz</file>
9487 must refer to the changelog for the current version of
9488 <var>package</var> in question. In practice, this means
9489 that the sources of the target and the destination of the
9490 symlink must be the same (same source package and
9497 Former Debian releases placed all additional documentation
9498 in <file>/usr/doc/<var>package</var></file>. This has been
9499 changed to <file>/usr/share/doc/<var>package</var></file>,
9500 and packages must not put documentation in the directory
9501 <file>/usr/doc/<var>package</var></file>. <footnote>
9502 At this phase of the transition, we no longer require a
9503 symbolic link in <file>/usr/doc/</file>. At a later point,
9504 policy shall change to make the symbolic links a bug.
9510 <heading>Preferred documentation formats</heading>
9513 The unification of Debian documentation is being carried out
9517 If your package comes with extensive documentation in a
9518 markup format that can be converted to various other formats
9519 you should if possible ship HTML versions in a binary
9520 package, in the directory
9521 <file>/usr/share/doc/<var>appropriate-package</var></file> or
9522 its subdirectories.<footnote>
9523 The rationale: The important thing here is that HTML
9524 docs should be available in <em>some</em> package, not
9525 necessarily in the main binary package.
9530 Other formats such as PostScript may be provided at the
9531 package maintainer's discretion.
9535 <sect id="copyrightfile">
9536 <heading>Copyright information</heading>
9539 Every package must be accompanied by a verbatim copy of its
9540 copyright information and distribution license in the file
9541 <file>/usr/share/doc/<var>package</var>/copyright</file>. This
9542 file must neither be compressed nor be a symbolic link.
9546 In addition, the copyright file must say where the upstream
9547 sources (if any) were obtained. It should name the original
9548 authors of the package and the Debian maintainer(s) who were
9549 involved with its creation.
9553 Packages in the <em>contrib</em> or <em>non-free</em> archive
9554 areas should state in the copyright file that the package is not
9555 part of the Debian GNU/Linux distribution and briefly explain
9560 A copy of the file which will be installed in
9561 <file>/usr/share/doc/<var>package</var>/copyright</file> should
9562 be in <file>debian/copyright</file> in the source package.
9566 <file>/usr/share/doc/<var>package</var></file> may be a symbolic
9567 link to another directory in <file>/usr/share/doc</file> only if
9568 the two packages both come from the same source and the
9569 first package Depends on the second. These rules are
9570 important because copyrights must be extractable by
9575 Packages distributed under the Apache license (version 2.0), the
9576 Artistic license, the GNU GPL (versions 1, 2, or 3), the GNU
9577 LGPL (versions 2, 2.1, or 3), and the GNU FDL (versions 1.2 or
9578 1.3) should refer to the corresponding files
9579 under <file>/usr/share/common-licenses</file>,<footnote>
9582 <file>/usr/share/common-licenses/Apache-2.0</file>,
9583 <file>/usr/share/common-licenses/Artistic</file>,
9584 <file>/usr/share/common-licenses/GPL-1</file>,
9585 <file>/usr/share/common-licenses/GPL-2</file>,
9586 <file>/usr/share/common-licenses/GPL-3</file>,
9587 <file>/usr/share/common-licenses/LGPL-2</file>,
9588 <file>/usr/share/common-licenses/LGPL-2.1</file>,
9589 <file>/usr/share/common-licenses/LGPL-3</file>,
9590 <file>/usr/share/common-licenses/GFDL-1.2</file>, and
9591 <file>/usr/share/common-licenses/GFDL-1.3</file>
9592 respectively. The University of California BSD license is
9593 also included in <package>base-files</package> as
9594 <file>/usr/share/common-licenses/BSD</file>, but given the
9595 brevity of this license, its specificity to code whose
9596 copyright is held by the Regents of the University of
9597 California, and the frequency of minor wording changes, its
9598 text should be included in the copyright file rather than
9599 referencing this file.
9601 </footnote> rather than quoting them in the copyright
9606 You should not use the copyright file as a general <file>README</file>
9607 file. If your package has such a file it should be
9608 installed in <file>/usr/share/doc/<var>package</var>/README</file> or
9609 <file>README.Debian</file> or some other appropriate place.</p>
9613 <heading>Examples</heading>
9616 Any examples (configurations, source files, whatever),
9617 should be installed in a directory
9618 <file>/usr/share/doc/<var>package</var>/examples</file>. These
9619 files should not be referenced by any program: they're there
9620 for the benefit of the system administrator and users as
9621 documentation only. Architecture-specific example files
9622 should be installed in a directory
9623 <file>/usr/lib/<var>package</var>/examples</file> with symbolic
9625 <file>/usr/share/doc/<var>package</var>/examples</file>, or the
9626 latter directory itself may be a symbolic link to the
9631 If the purpose of a package is to provide examples, then the
9632 example files may be installed into
9633 <file>/usr/share/doc/<var>package</var></file>.
9637 <sect id="changelogs">
9638 <heading>Changelog files</heading>
9641 Packages that are not Debian-native must contain a
9642 compressed copy of the <file>debian/changelog</file> file from
9643 the Debian source tree in
9644 <file>/usr/share/doc/<var>package</var></file> with the name
9645 <file>changelog.Debian.gz</file>.
9649 If an upstream changelog is available, it should be accessible as
9650 <file>/usr/share/doc/<var>package</var>/changelog.gz</file> in
9651 plain text. If the upstream changelog is distributed in
9652 HTML, it should be made available in that form as
9653 <file>/usr/share/doc/<var>package</var>/changelog.html.gz</file>
9654 and a plain text <file>changelog.gz</file> should be generated
9655 from it using, for example, <tt>lynx -dump -nolist</tt>. If
9656 the upstream changelog files do not already conform to this
9657 naming convention, then this may be achieved either by
9658 renaming the files, or by adding a symbolic link, at the
9659 maintainer's discretion.<footnote>
9660 Rationale: People should not have to look in places for
9661 upstream changelogs merely because they are given
9662 different names or are distributed in HTML format.
9667 All of these files should be installed compressed using
9668 <tt>gzip -9</tt>, as they will become large with time even
9669 if they start out small.
9673 If the package has only one changelog which is used both as
9674 the Debian changelog and the upstream one because there is
9675 no separate upstream maintainer then that changelog should
9676 usually be installed as
9677 <file>/usr/share/doc/<var>package</var>/changelog.gz</file>; if
9678 there is a separate upstream maintainer, but no upstream
9679 changelog, then the Debian changelog should still be called
9680 <file>changelog.Debian.gz</file>.
9684 For details about the format and contents of the Debian
9685 changelog file, please see <ref id="dpkgchangelog">.
9690 <appendix id="pkg-scope">
9691 <heading>Introduction and scope of these appendices</heading>
9694 These appendices are taken essentially verbatim from the
9695 now-deprecated Packaging Manual, version 3.2.1.0. They are
9696 the chapters which are likely to be of use to package
9697 maintainers and which have not already been included in the
9698 policy document itself. Most of these sections are very likely
9699 not relevant to policy; they should be treated as
9700 documentation for the packaging system. Please note that these
9701 appendices are included for convenience, and for historical
9702 reasons: they used to be part of policy package, and they have
9703 not yet been incorporated into dpkg documentation. However,
9704 they still have value, and hence they are presented here.
9708 They have not yet been checked to ensure that they are
9709 compatible with the contents of policy, and if there are any
9710 contradictions, the version in the main policy document takes
9711 precedence. The remaining chapters of the old Packaging
9712 Manual have also not been read in detail to ensure that there
9713 are not parts which have been left out. Both of these will be
9718 Certain parts of the Packaging manual were integrated into the
9719 Policy Manual proper, and removed from the appendices. Links
9720 have been placed from the old locations to the new ones.
9724 <prgn>dpkg</prgn> is a suite of programs for creating binary
9725 package files and installing and removing them on Unix
9727 <prgn>dpkg</prgn> is targeted primarily at Debian
9728 GNU/Linux, but may work on or be ported to other
9734 The binary packages are designed for the management of
9735 installed executable programs (usually compiled binaries) and
9736 their associated data, though source code examples and
9737 documentation are provided as part of some packages.</p>
9740 This manual describes the technical aspects of creating Debian
9741 binary packages (<file>.deb</file> files). It documents the
9742 behavior of the package management programs
9743 <prgn>dpkg</prgn>, <prgn>dselect</prgn> et al. and the way
9744 they interact with packages.</p>
9747 It also documents the interaction between
9748 <prgn>dselect</prgn>'s core and the access method scripts it
9749 uses to actually install the selected packages, and describes
9750 how to create a new access method.</p>
9753 This manual does not go into detail about the options and
9754 usage of the package building and installation tools. It
9755 should therefore be read in conjunction with those programs'
9760 The utility programs which are provided with <prgn>dpkg</prgn>
9761 for managing various system configuration and similar issues,
9762 such as <prgn>update-rc.d</prgn> and
9763 <prgn>install-info</prgn>, are not described in detail here -
9764 please see their man pages.
9768 It is assumed that the reader is reasonably familiar with the
9769 <prgn>dpkg</prgn> System Administrators' manual.
9770 Unfortunately this manual does not yet exist.
9774 The Debian version of the FSF's GNU hello program is provided
9775 as an example for people wishing to create Debian
9776 packages. The Debian <prgn>debmake</prgn> package is
9777 recommended as a very helpful tool in creating and maintaining
9778 Debian packages. However, while the tools and examples are
9779 helpful, they do not replace the need to read and follow the
9780 Policy and Programmer's Manual.</p>
9783 <appendix id="pkg-binarypkg">
9784 <heading>Binary packages (from old Packaging Manual)</heading>
9787 The binary package has two main sections. The first part
9788 consists of various control information files and scripts used
9789 by <prgn>dpkg</prgn> when installing and removing. See <ref
9790 id="pkg-controlarea">.
9794 The second part is an archive containing the files and
9795 directories to be installed.
9799 In the future binary packages may also contain other
9800 components, such as checksums and digital signatures. The
9801 format for the archive is described in full in the
9802 <file>deb(5)</file> man page.
9806 <sect id="pkg-bincreating"><heading>Creating package files -
9807 <prgn>dpkg-deb</prgn>
9811 All manipulation of binary package files is done by
9812 <prgn>dpkg-deb</prgn>; it's the only program that has
9813 knowledge of the format. (<prgn>dpkg-deb</prgn> may be
9814 invoked by calling <prgn>dpkg</prgn>, as <prgn>dpkg</prgn>
9815 will spot that the options requested are appropriate to
9816 <prgn>dpkg-deb</prgn> and invoke that instead with the same
9821 In order to create a binary package you must make a
9822 directory tree which contains all the files and directories
9823 you want to have in the file system data part of the package.
9824 In Debian-format source packages this directory is usually
9825 <file>debian/tmp</file>, relative to the top of the package's
9830 They should have the locations (relative to the root of the
9831 directory tree you're constructing) ownerships and
9832 permissions which you want them to have on the system when
9837 With current versions of <prgn>dpkg</prgn> the uid/username
9838 and gid/groupname mappings for the users and groups being
9839 used should be the same on the system where the package is
9840 built and the one where it is installed.
9844 You need to add one special directory to the root of the
9845 miniature file system tree you're creating:
9846 <prgn>DEBIAN</prgn>. It should contain the control
9847 information files, notably the binary package control file
9848 (see <ref id="pkg-controlfile">).
9852 The <prgn>DEBIAN</prgn> directory will not appear in the
9853 file system archive of the package, and so won't be installed
9854 by <prgn>dpkg</prgn> when the package is installed.
9858 When you've prepared the package, you should invoke:
9860 dpkg --build <var>directory</var>
9865 This will build the package in
9866 <file><var>directory</var>.deb</file>. (<prgn>dpkg</prgn> knows
9867 that <tt>--build</tt> is a <prgn>dpkg-deb</prgn> option, so
9868 it invokes <prgn>dpkg-deb</prgn> with the same arguments to
9873 See the man page <manref name="dpkg-deb" section="8"> for details of how
9874 to examine the contents of this newly-created file. You may find the
9875 output of following commands enlightening:
9877 dpkg-deb --info <var>filename</var>.deb
9878 dpkg-deb --contents <var>filename</var>.deb
9879 dpkg --contents <var>filename</var>.deb
9881 To view the copyright file for a package you could use this command:
9883 dpkg --fsys-tarfile <var>filename</var>.deb | tar xOf - --wildcards \*/copyright | pager
9888 <sect id="pkg-controlarea">
9889 <heading>Package control information files</heading>
9892 The control information portion of a binary package is a
9893 collection of files with names known to <prgn>dpkg</prgn>.
9894 It will treat the contents of these files specially - some
9895 of them contain information used by <prgn>dpkg</prgn> when
9896 installing or removing the package; others are scripts which
9897 the package maintainer wants <prgn>dpkg</prgn> to run.
9901 It is possible to put other files in the package control
9902 information file area, but this is not generally a good idea
9903 (though they will largely be ignored).
9907 Here is a brief list of the control information files supported
9908 by <prgn>dpkg</prgn> and a summary of what they're used for.
9913 <tag><tt>control</tt>
9916 This is the key description file used by
9917 <prgn>dpkg</prgn>. It specifies the package's name
9918 and version, gives its description for the user,
9919 states its relationships with other packages, and so
9920 forth. See <ref id="sourcecontrolfiles"> and
9921 <ref id="binarycontrolfiles">.
9925 It is usually generated automatically from information
9926 in the source package by the
9927 <prgn>dpkg-gencontrol</prgn> program, and with
9928 assistance from <prgn>dpkg-shlibdeps</prgn>.
9929 See <ref id="pkg-sourcetools">.
9933 <tag><tt>postinst</tt>, <tt>preinst</tt>, <tt>postrm</tt>,
9938 These are executable files (usually scripts) which
9939 <prgn>dpkg</prgn> runs during installation, upgrade
9940 and removal of packages. They allow the package to
9941 deal with matters which are particular to that package
9942 or require more complicated processing than that
9943 provided by <prgn>dpkg</prgn>. Details of when and
9944 how they are called are in <ref id="maintainerscripts">.
9948 It is very important to make these scripts idempotent.
9949 See <ref id="idempotency">.
9953 The maintainer scripts are not guaranteed to run with a
9954 controlling terminal and may not be able to interact with
9955 the user. See <ref id="controllingterminal">.
9959 <tag><tt>conffiles</tt>
9962 This file contains a list of configuration files which
9963 are to be handled automatically by <prgn>dpkg</prgn>
9964 (see <ref id="pkg-conffiles">). Note that not necessarily
9965 every configuration file should be listed here.
9968 <tag><tt>shlibs</tt>
9971 This file contains a list of the shared libraries
9972 supplied by the package, with dependency details for
9973 each. This is used by <prgn>dpkg-shlibdeps</prgn>
9974 when it determines what dependencies are required in a
9975 package control file. The <tt>shlibs</tt> file format
9976 is described on <ref id="shlibs">.
9981 <sect id="pkg-controlfile">
9982 <heading>The main control information file: <tt>control</tt></heading>
9985 The most important control information file used by
9986 <prgn>dpkg</prgn> when it installs a package is
9987 <tt>control</tt>. It contains all the package's "vital
9992 The binary package control files of packages built from
9993 Debian sources are made by a special tool,
9994 <prgn>dpkg-gencontrol</prgn>, which reads
9995 <file>debian/control</file> and <file>debian/changelog</file> to
9996 find the information it needs. See <ref id="pkg-sourcepkg"> for
10001 The fields in binary package control files are listed in
10002 <ref id="binarycontrolfiles">.
10006 A description of the syntax of control files and the purpose
10007 of the fields is available in <ref id="controlfields">.
10012 <heading>Time Stamps</heading>
10015 See <ref id="timestamps">.
10020 <appendix id="pkg-sourcepkg">
10021 <heading>Source packages (from old Packaging Manual) </heading>
10024 The Debian binary packages in the distribution are generated
10025 from Debian sources, which are in a special format to assist
10026 the easy and automatic building of binaries.
10029 <sect id="pkg-sourcetools">
10030 <heading>Tools for processing source packages</heading>
10033 Various tools are provided for manipulating source packages;
10034 they pack and unpack sources and help build of binary
10035 packages and help manage the distribution of new versions.
10039 They are introduced and typical uses described here; see
10040 <manref name="dpkg-source" section="1"> for full
10041 documentation about their arguments and operation.
10045 For examples of how to construct a Debian source package,
10046 and how to use those utilities that are used by Debian
10047 source packages, please see the <prgn>hello</prgn> example
10051 <sect1 id="pkg-dpkg-source">
10053 <prgn>dpkg-source</prgn> - packs and unpacks Debian source
10058 This program is frequently used by hand, and is also
10059 called from package-independent automated building scripts
10060 such as <prgn>dpkg-buildpackage</prgn>.
10064 To unpack a package it is typically invoked with
10066 dpkg-source -x <var>.../path/to/filename</var>.dsc
10071 with the <file><var>filename</var>.tar.gz</file> and
10072 <file><var>filename</var>.diff.gz</file> (if applicable) in
10073 the same directory. It unpacks into
10074 <file><var>package</var>-<var>version</var></file>, and if
10076 <file><var>package</var>-<var>version</var>.orig</file>, in
10077 the current directory.
10081 To create a packed source archive it is typically invoked:
10083 dpkg-source -b <var>package</var>-<var>version</var>
10088 This will create the <file>.dsc</file>, <file>.tar.gz</file> and
10089 <file>.diff.gz</file> (if appropriate) in the current
10090 directory. <prgn>dpkg-source</prgn> does not clean the
10091 source tree first - this must be done separately if it is
10096 See also <ref id="pkg-sourcearchives">.</p>
10100 <sect1 id="pkg-dpkg-buildpackage">
10102 <prgn>dpkg-buildpackage</prgn> - overall package-building
10107 <prgn>dpkg-buildpackage</prgn> is a script which invokes
10108 <prgn>dpkg-source</prgn>, the <file>debian/rules</file>
10109 targets <tt>clean</tt>, <tt>build</tt> and
10110 <tt>binary</tt>, <prgn>dpkg-genchanges</prgn> and
10111 <prgn>gpg</prgn> (or <prgn>pgp</prgn>) to build a signed
10112 source and binary package upload.
10116 It is usually invoked by hand from the top level of the
10117 built or unbuilt source directory. It may be invoked with
10118 no arguments; useful arguments include:
10119 <taglist compact="compact">
10120 <tag><tt>-uc</tt>, <tt>-us</tt></tag>
10123 Do not sign the <tt>.changes</tt> file or the
10124 source package <tt>.dsc</tt> file, respectively.</p>
10126 <tag><tt>-p<var>sign-command</var></tt></tag>
10129 Invoke <var>sign-command</var> instead of finding
10130 <tt>gpg</tt> or <tt>pgp</tt> on the <prgn>PATH</prgn>.
10131 <var>sign-command</var> must behave just like
10132 <prgn>gpg</prgn> or <tt>pgp</tt>.</p>
10134 <tag><tt>-r<var>root-command</var></tt></tag>
10137 When root privilege is required, invoke the command
10138 <var>root-command</var>. <var>root-command</var>
10139 should invoke its first argument as a command, from
10140 the <prgn>PATH</prgn> if necessary, and pass its
10141 second and subsequent arguments to the command it
10142 calls. If no <var>root-command</var> is supplied
10143 then <var>dpkg-buildpackage</var> will take no
10144 special action to gain root privilege, so that for
10145 most packages it will have to be invoked as root to
10148 <tag><tt>-b</tt>, <tt>-B</tt></tag>
10151 Two types of binary-only build and upload - see
10152 <manref name="dpkg-source" section="1">.
10159 <sect1 id="pkg-dpkg-gencontrol">
10161 <prgn>dpkg-gencontrol</prgn> - generates binary package
10166 This program is usually called from <file>debian/rules</file>
10167 (see <ref id="pkg-sourcetree">) in the top level of the source
10172 This is usually done just before the files and directories in the
10173 temporary directory tree where the package is being built have their
10174 permissions and ownerships set and the package is constructed using
10175 <prgn>dpkg-deb/</prgn>
10177 This is so that the control file which is produced has
10178 the right permissions
10183 <prgn>dpkg-gencontrol</prgn> must be called after all the
10184 files which are to go into the package have been placed in
10185 the temporary build directory, so that its calculation of
10186 the installed size of a package is correct.
10190 It is also necessary for <prgn>dpkg-gencontrol</prgn> to
10191 be run after <prgn>dpkg-shlibdeps</prgn> so that the
10192 variable substitutions created by
10193 <prgn>dpkg-shlibdeps</prgn> in <file>debian/substvars</file>
10198 For a package which generates only one binary package, and
10199 which builds it in <file>debian/tmp</file> relative to the top
10200 of the source package, it is usually sufficient to call
10201 <prgn>dpkg-gencontrol</prgn>.
10205 Sources which build several binaries will typically need
10208 dpkg-gencontrol -Pdebian/tmp-<var>pkg</var> -p<var>package</var>
10209 </example> The <tt>-P</tt> tells
10210 <prgn>dpkg-gencontrol</prgn> that the package is being
10211 built in a non-default directory, and the <tt>-p</tt>
10212 tells it which package's control file should be generated.
10216 <prgn>dpkg-gencontrol</prgn> also adds information to the
10217 list of files in <file>debian/files</file>, for the benefit of
10218 (for example) a future invocation of
10219 <prgn>dpkg-genchanges</prgn>.</p>
10222 <sect1 id="pkg-dpkg-shlibdeps">
10224 <prgn>dpkg-shlibdeps</prgn> - calculates shared library
10229 This program is usually called from <file>debian/rules</file>
10230 just before <prgn>dpkg-gencontrol</prgn> (see <ref
10231 id="pkg-sourcetree">), in the top level of the source tree.
10235 Its arguments are executables and shared libraries
10238 They may be specified either in the locations in the
10239 source tree where they are created or in the locations
10240 in the temporary build tree where they are installed
10241 prior to binary package creation.
10243 </footnote> for which shared library dependencies should
10244 be included in the binary package's control file.
10248 If some of the found shared libraries should only
10249 warrant a <tt>Recommends</tt> or <tt>Suggests</tt>, or if
10250 some warrant a <tt>Pre-Depends</tt>, this can be achieved
10251 by using the <tt>-d<var>dependency-field</var></tt> option
10252 before those executable(s). (Each <tt>-d</tt> option
10253 takes effect until the next <tt>-d</tt>.)
10257 <prgn>dpkg-shlibdeps</prgn> does not directly cause the
10258 output control file to be modified. Instead by default it
10259 adds to the <file>debian/substvars</file> file variable
10260 settings like <tt>shlibs:Depends</tt>. These variable
10261 settings must be referenced in dependency fields in the
10262 appropriate per-binary-package sections of the source
10267 For example, a package that generates an essential part
10268 which requires dependencies, and optional parts that
10269 which only require a recommendation, would separate those
10270 two sets of dependencies into two different fields.<footnote>
10271 At the time of writing, an example for this was the
10272 <package/xmms/ package, with Depends used for the xmms
10273 executable, Recommends for the plug-ins and Suggests for
10274 even more optional features provided by unzip.
10276 It can say in its <file>debian/rules</file>:
10278 dpkg-shlibdeps -dDepends <var>program anotherprogram ...</var> \
10279 -dRecommends <var>optionalpart anotheroptionalpart</var>
10281 and then in its main control file <file>debian/control</file>:
10284 Depends: ${shlibs:Depends}
10285 Recommends: ${shlibs:Recommends}
10291 Sources which produce several binary packages with
10292 different shared library dependency requirements can use
10293 the <tt>-p<var>varnameprefix</var></tt> option to override
10294 the default <tt>shlibs:</tt> prefix (one invocation of
10295 <prgn>dpkg-shlibdeps</prgn> per setting of this option).
10296 They can thus produce several sets of dependency
10297 variables, each of the form
10298 <tt><var>varnameprefix</var>:<var>dependencyfield</var></tt>,
10299 which can be referred to in the appropriate parts of the
10300 binary package control files.
10305 <sect1 id="pkg-dpkg-distaddfile">
10307 <prgn>dpkg-distaddfile</prgn> - adds a file to
10308 <file>debian/files</file>
10312 Some packages' uploads need to include files other than
10313 the source and binary package files.
10317 <prgn>dpkg-distaddfile</prgn> adds a file to the
10318 <file>debian/files</file> file so that it will be included in
10319 the <file>.changes</file> file when
10320 <prgn>dpkg-genchanges</prgn> is run.
10324 It is usually invoked from the <tt>binary</tt> target of
10325 <file>debian/rules</file>:
10327 dpkg-distaddfile <var>filename</var> <var>section</var> <var>priority</var>
10329 The <var>filename</var> is relative to the directory where
10330 <prgn>dpkg-genchanges</prgn> will expect to find it - this
10331 is usually the directory above the top level of the source
10332 tree. The <file>debian/rules</file> target should put the
10333 file there just before or just after calling
10334 <prgn>dpkg-distaddfile</prgn>.
10338 The <var>section</var> and <var>priority</var> are passed
10339 unchanged into the resulting <file>.changes</file> file.
10344 <sect1 id="pkg-dpkg-genchanges">
10346 <prgn>dpkg-genchanges</prgn> - generates a <file>.changes</file>
10347 upload control file
10351 This program is usually called by package-independent
10352 automatic building scripts such as
10353 <prgn>dpkg-buildpackage</prgn>, but it may also be called
10358 It is usually called in the top level of a built source
10359 tree, and when invoked with no arguments will print out a
10360 straightforward <file>.changes</file> file based on the
10361 information in the source package's changelog and control
10362 file and the binary and source packages which should have
10368 <sect1 id="pkg-dpkg-parsechangelog">
10370 <prgn>dpkg-parsechangelog</prgn> - produces parsed
10371 representation of a changelog
10375 This program is used internally by
10376 <prgn>dpkg-source</prgn> et al. It may also occasionally
10377 be useful in <file>debian/rules</file> and elsewhere. It
10378 parses a changelog, <file>debian/changelog</file> by default,
10379 and prints a control-file format representation of the
10380 information in it to standard output.
10384 <sect1 id="pkg-dpkg-architecture">
10386 <prgn>dpkg-architecture</prgn> - information about the build and
10391 This program can be used manually, but is also invoked by
10392 <tt>dpkg-buildpackage</tt> or <file>debian/rules</file> to set
10393 environment or make variables which specify the build and host
10394 architecture for the package building process.
10399 <sect id="pkg-sourcetree">
10400 <heading>The Debian package source tree</heading>
10403 The source archive scheme described later is intended to
10404 allow a Debian package source tree with some associated
10405 control information to be reproduced and transported easily.
10406 The Debian package source tree is a version of the original
10407 program with certain files added for the benefit of the
10408 packaging process, and with any other changes required
10409 made to the rest of the source code and installation
10414 The extra files created for Debian are in the subdirectory
10415 <file>debian</file> of the top level of the Debian package
10416 source tree. They are described below.
10419 <sect1 id="pkg-debianrules">
10420 <heading><file>debian/rules</file> - the main building script</heading>
10423 See <ref id="debianrules">.
10427 <sect1 id="pkg-srcsubstvars">
10428 <heading><file>debian/substvars</file> and variable substitutions</heading>
10431 See <ref id="substvars">.
10437 <heading><file>debian/files</file></heading>
10440 See <ref id="debianfiles">.
10444 <sect1><heading><file>debian/tmp</file>
10448 This is the canonical temporary location for the
10449 construction of binary packages by the <tt>binary</tt>
10450 target. The directory <file>tmp</file> serves as the root of
10451 the file system tree as it is being constructed (for
10452 example, by using the package's upstream makefiles install
10453 targets and redirecting the output there), and it also
10454 contains the <tt>DEBIAN</tt> subdirectory. See <ref
10455 id="pkg-bincreating">.
10459 If several binary packages are generated from the same
10460 source tree it is usual to use several
10461 <file>debian/tmp<var>something</var></file> directories, for
10462 example <file>tmp-a</file> or <file>tmp-doc</file>.
10466 Whatever <file>tmp</file> directories are created and used by
10467 <tt>binary</tt> must of course be removed by the
10468 <tt>clean</tt> target.</p></sect1>
10472 <sect id="pkg-sourcearchives"><heading>Source packages as archives
10476 As it exists on the FTP site, a Debian source package
10477 consists of three related files. You must have the right
10478 versions of all three to be able to use them.
10483 <tag>Debian source control file - <tt>.dsc</tt></tag>
10485 This file is a control file used by <prgn>dpkg-source</prgn>
10486 to extract a source package.
10487 See <ref id="debiansourcecontrolfiles">.
10491 Original source archive -
10493 <var>package</var>_<var>upstream-version</var>.orig.tar.gz
10499 This is a compressed (with <tt>gzip -9</tt>)
10500 <prgn>tar</prgn> file containing the source code from
10501 the upstream authors of the program.
10506 Debian package diff -
10508 <var>package</var>_<var>upstream_version-revision</var>.diff.gz
10514 This is a unified context diff (<tt>diff -u</tt>)
10515 giving the changes which are required to turn the
10516 original source into the Debian source. These changes
10517 may only include editing and creating plain files.
10518 The permissions of files, the targets of symbolic
10519 links and the characteristics of special files or
10520 pipes may not be changed and no files may be removed
10525 All the directories in the diff must exist, except the
10526 <file>debian</file> subdirectory of the top of the source
10527 tree, which will be created by
10528 <prgn>dpkg-source</prgn> if necessary when unpacking.
10532 The <prgn>dpkg-source</prgn> program will
10533 automatically make the <file>debian/rules</file> file
10534 executable (see below).</p></item>
10539 If there is no original source code - for example, if the
10540 package is specially prepared for Debian or the Debian
10541 maintainer is the same as the upstream maintainer - the
10542 format is slightly different: then there is no diff, and the
10544 <file><var>package</var>_<var>version</var>.tar.gz</file>,
10545 and preferably contains a directory named
10546 <file><var>package</var>-<var>version</var></file>.
10551 <heading>Unpacking a Debian source package without <prgn>dpkg-source</prgn></heading>
10554 <tt>dpkg-source -x</tt> is the recommended way to unpack a
10555 Debian source package. However, if it is not available it
10556 is possible to unpack a Debian source archive as follows:
10557 <enumlist compact="compact">
10560 Untar the tarfile, which will create a <file>.orig</file>
10564 <p>Rename the <file>.orig</file> directory to
10565 <file><var>package</var>-<var>version</var></file>.</p>
10569 Create the subdirectory <file>debian</file> at the top of
10570 the source tree.</p>
10572 <item><p>Apply the diff using <tt>patch -p0</tt>.</p>
10574 <item><p>Untar the tarfile again if you want a copy of the original
10575 source code alongside the Debian version.</p>
10580 It is not possible to generate a valid Debian source archive
10581 without using <prgn>dpkg-source</prgn>. In particular,
10582 attempting to use <prgn>diff</prgn> directly to generate the
10583 <file>.diff.gz</file> file will not work.
10587 <heading>Restrictions on objects in source packages</heading>
10590 The source package may not contain any hard links
10592 This is not currently detected when building source
10593 packages, but only when extracting
10597 Hard links may be permitted at some point in the
10598 future, but would require a fair amount of
10600 </footnote>, device special files, sockets or setuid or
10603 Setgid directories are allowed.
10608 The source packaging tools manage the changes between the
10609 original and Debian source using <prgn>diff</prgn> and
10610 <prgn>patch</prgn>. Turning the original source tree as
10611 included in the <file>.orig.tar.gz</file> into the Debian
10612 package source must not involve any changes which cannot be
10613 handled by these tools. Problematic changes which cause
10614 <prgn>dpkg-source</prgn> to halt with an error when
10615 building the source package are:
10616 <list compact="compact">
10617 <item><p>Adding or removing symbolic links, sockets or pipes.</p>
10619 <item><p>Changing the targets of symbolic links.</p>
10621 <item><p>Creating directories, other than <file>debian</file>.</p>
10623 <item><p>Changes to the contents of binary files.</p></item>
10624 </list> Changes which cause <prgn>dpkg-source</prgn> to
10625 print a warning but continue anyway are:
10626 <list compact="compact">
10629 Removing files, directories or symlinks.
10631 Renaming a file is not treated specially - it is
10632 seen as the removal of the old file (which
10633 generates a warning, but is otherwise ignored),
10634 and the creation of the new one.
10640 Changed text files which are missing the usual final
10641 newline (either in the original or the modified
10646 Changes which are not represented, but which are not detected by
10647 <prgn>dpkg-source</prgn>, are:
10648 <list compact="compact">
10649 <item><p>Changing the permissions of files (other than
10650 <file>debian/rules</file>) and directories.</p></item>
10655 The <file>debian</file> directory and <file>debian/rules</file>
10656 are handled specially by <prgn>dpkg-source</prgn> - before
10657 applying the changes it will create the <file>debian</file>
10658 directory, and afterwards it will make
10659 <file>debian/rules</file> world-executable.
10665 <appendix id="pkg-controlfields">
10666 <heading>Control files and their fields (from old Packaging Manual)</heading>
10669 Many of the tools in the <prgn>dpkg</prgn> suite manipulate
10670 data in a common format, known as control files. Binary and
10671 source packages have control data as do the <file>.changes</file>
10672 files which control the installation of uploaded files, and
10673 <prgn>dpkg</prgn>'s internal databases are in a similar
10678 <heading>Syntax of control files</heading>
10681 See <ref id="controlsyntax">.
10685 It is important to note that there are several fields which
10686 are optional as far as <prgn>dpkg</prgn> and the related
10687 tools are concerned, but which must appear in every Debian
10688 package, or whose omission may cause problems.
10693 <heading>List of fields</heading>
10696 See <ref id="controlfieldslist">.
10700 This section now contains only the fields that didn't belong
10701 to the Policy manual.
10704 <sect1 id="pkg-f-Filename">
10705 <heading><tt>Filename</tt> and <tt>MSDOS-Filename</tt></heading>
10708 These fields in <tt>Packages</tt> files give the
10709 filename(s) of (the parts of) a package in the
10710 distribution directories, relative to the root of the
10711 Debian hierarchy. If the package has been split into
10712 several parts the parts are all listed in order, separated
10717 <sect1 id="pkg-f-Size">
10718 <heading><tt>Size</tt> and <tt>MD5sum</tt></heading>
10721 These fields in <file>Packages</file> files give the size (in
10722 bytes, expressed in decimal) and MD5 checksum of the
10723 file(s) which make(s) up a binary package in the
10724 distribution. If the package is split into several parts
10725 the values for the parts are listed in order, separated by
10730 <sect1 id="pkg-f-Status">
10731 <heading><tt>Status</tt></heading>
10734 This field in <prgn>dpkg</prgn>'s status file records
10735 whether the user wants a package installed, removed or
10736 left alone, whether it is broken (requiring
10737 re-installation) or not and what its current state on the
10738 system is. Each of these pieces of information is a
10743 <sect1 id="pkg-f-Config-Version">
10744 <heading><tt>Config-Version</tt></heading>
10747 If a package is not installed or not configured, this
10748 field in <prgn>dpkg</prgn>'s status file records the last
10749 version of the package which was successfully
10754 <sect1 id="pkg-f-Conffiles">
10755 <heading><tt>Conffiles</tt></heading>
10758 This field in <prgn>dpkg</prgn>'s status file contains
10759 information about the automatically-managed configuration
10760 files held by a package. This field should <em>not</em>
10761 appear anywhere in a package!
10766 <heading>Obsolete fields</heading>
10769 These are still recognized by <prgn>dpkg</prgn> but should
10770 not appear anywhere any more.
10772 <taglist compact="compact">
10774 <tag><tt>Revision</tt></tag>
10775 <tag><tt>Package-Revision</tt></tag>
10776 <tag><tt>Package_Revision</tt></tag>
10778 The Debian revision part of the package version was
10779 at one point in a separate control field. This
10780 field went through several names.
10783 <tag><tt>Recommended</tt></tag>
10784 <item>Old name for <tt>Recommends</tt>.</item>
10786 <tag><tt>Optional</tt></tag>
10787 <item>Old name for <tt>Suggests</tt>.</item>
10789 <tag><tt>Class</tt></tag>
10790 <item>Old name for <tt>Priority</tt>.</item>
10799 <appendix id="pkg-conffiles">
10800 <heading>Configuration file handling (from old Packaging Manual)</heading>
10803 <prgn>dpkg</prgn> can do a certain amount of automatic
10804 handling of package configuration files.
10808 Whether this mechanism is appropriate depends on a number of
10809 factors, but basically there are two approaches to any
10810 particular configuration file.
10814 The easy method is to ship a best-effort configuration in the
10815 package, and use <prgn>dpkg</prgn>'s conffile mechanism to
10816 handle updates. If the user is unlikely to want to edit the
10817 file, but you need them to be able to without losing their
10818 changes, and a new package with a changed version of the file
10819 is only released infrequently, this is a good approach.
10823 The hard method is to build the configuration file from
10824 scratch in the <prgn>postinst</prgn> script, and to take the
10825 responsibility for fixing any mistakes made in earlier
10826 versions of the package automatically. This will be
10827 appropriate if the file is likely to need to be different on
10831 <sect><heading>Automatic handling of configuration files by
10836 A package may contain a control information file called
10837 <tt>conffiles</tt>. This file should be a list of filenames
10838 of configuration files needing automatic handling, separated
10839 by newlines. The filenames should be absolute pathnames,
10840 and the files referred to should actually exist in the
10845 When a package is upgraded <prgn>dpkg</prgn> will process
10846 the configuration files during the configuration stage,
10847 shortly before it runs the package's <prgn>postinst</prgn>
10852 For each file it checks to see whether the version of the
10853 file included in the package is the same as the one that was
10854 included in the last version of the package (the one that is
10855 being upgraded from); it also compares the version currently
10856 installed on the system with the one shipped with the last
10861 If neither the user nor the package maintainer has changed
10862 the file, it is left alone. If one or the other has changed
10863 their version, then the changed version is preferred - i.e.,
10864 if the user edits their file, but the package maintainer
10865 doesn't ship a different version, the user's changes will
10866 stay, silently, but if the maintainer ships a new version
10867 and the user hasn't edited it the new version will be
10868 installed (with an informative message). If both have
10869 changed their version the user is prompted about the problem
10870 and must resolve the differences themselves.
10874 The comparisons are done by calculating the MD5 message
10875 digests of the files, and storing the MD5 of the file as it
10876 was included in the most recent version of the package.
10880 When a package is installed for the first time
10881 <prgn>dpkg</prgn> will install the file that comes with it,
10882 unless that would mean overwriting a file already on the
10887 However, note that <prgn>dpkg</prgn> will <em>not</em>
10888 replace a conffile that was removed by the user (or by a
10889 script). This is necessary because with some programs a
10890 missing file produces an effect hard or impossible to
10891 achieve in another way, so that a missing file needs to be
10892 kept that way if the user did it.
10896 Note that a package should <em>not</em> modify a
10897 <prgn>dpkg</prgn>-handled conffile in its maintainer
10898 scripts. Doing this will lead to <prgn>dpkg</prgn> giving
10899 the user confusing and possibly dangerous options for
10900 conffile update when the package is upgraded.</p>
10903 <sect><heading>Fully-featured maintainer script configuration
10908 For files which contain site-specific information such as
10909 the hostname and networking details and so forth, it is
10910 better to create the file in the package's
10911 <prgn>postinst</prgn> script.
10915 This will typically involve examining the state of the rest
10916 of the system to determine values and other information, and
10917 may involve prompting the user for some information which
10918 can't be obtained some other way.
10922 When using this method there are a couple of important
10923 issues which should be considered:
10927 If you discover a bug in the program which generates the
10928 configuration file, or if the format of the file changes
10929 from one version to the next, you will have to arrange for
10930 the postinst script to do something sensible - usually this
10931 will mean editing the installed configuration file to remove
10932 the problem or change the syntax. You will have to do this
10933 very carefully, since the user may have changed the file,
10934 perhaps to fix the very problem that your script is trying
10935 to deal with - you will have to detect these situations and
10936 deal with them correctly.
10940 If you do go down this route it's probably a good idea to
10941 make the program that generates the configuration file(s) a
10942 separate program in <file>/usr/sbin</file>, by convention called
10943 <file><var>package</var>config</file> and then run that if
10944 appropriate from the post-installation script. The
10945 <tt><var>package</var>config</tt> program should not
10946 unquestioningly overwrite an existing configuration - if its
10947 mode of operation is geared towards setting up a package for
10948 the first time (rather than any arbitrary reconfiguration
10949 later) you should have it check whether the configuration
10950 already exists, and require a <tt>--force</tt> flag to
10951 overwrite it.</p></sect>
10954 <appendix id="pkg-alternatives"><heading>Alternative versions of
10955 an interface - <prgn>update-alternatives</prgn> (from old
10960 When several packages all provide different versions of the
10961 same program or file it is useful to have the system select a
10962 default, but to allow the system administrator to change it
10963 and have their decisions respected.
10967 For example, there are several versions of the <prgn>vi</prgn>
10968 editor, and there is no reason to prevent all of them from
10969 being installed at once, each under their own name
10970 (<prgn>nvi</prgn>, <prgn>vim</prgn> or whatever).
10971 Nevertheless it is desirable to have the name <tt>vi</tt>
10972 refer to something, at least by default.
10976 If all the packages involved cooperate, this can be done with
10977 <prgn>update-alternatives</prgn>.
10981 Each package provides its own version under its own name, and
10982 calls <prgn>update-alternatives</prgn> in its postinst to
10983 register its version (and again in its prerm to deregister
10988 See the man page <manref name="update-alternatives"
10989 section="8"> for details.
10993 If <prgn>update-alternatives</prgn> does not seem appropriate
10994 you may wish to consider using diversions instead.</p>
10997 <appendix id="pkg-diversions"><heading>Diversions - overriding a
10998 package's version of a file (from old Packaging Manual)
11002 It is possible to have <prgn>dpkg</prgn> not overwrite a file
11003 when it reinstalls the package it belongs to, and to have it
11004 put the file from the package somewhere else instead.
11008 This can be used locally to override a package's version of a
11009 file, or by one package to override another's version (or
11010 provide a wrapper for it).
11014 Before deciding to use a diversion, read <ref
11015 id="pkg-alternatives"> to see if you really want a diversion
11016 rather than several alternative versions of a program.
11020 There is a diversion list, which is read by <prgn>dpkg</prgn>,
11021 and updated by a special program <prgn>dpkg-divert</prgn>.
11022 Please see <manref name="dpkg-divert" section="8"> for full
11023 details of its operation.
11027 When a package wishes to divert a file from another, it should
11028 call <prgn>dpkg-divert</prgn> in its preinst to add the
11029 diversion and rename the existing file. For example,
11030 supposing that a <prgn>smailwrapper</prgn> package wishes to
11031 install a wrapper around <file>/usr/sbin/smail</file>:
11033 dpkg-divert --package smailwrapper --add --rename \
11034 --divert /usr/sbin/smail.real /usr/sbin/smail
11035 </example> The <tt>--package smailwrapper</tt> ensures that
11036 <prgn>smailwrapper</prgn>'s copy of <file>/usr/sbin/smail</file>
11037 can bypass the diversion and get installed as the true version.
11038 It's safe to add the diversion unconditionally on upgrades since
11039 it will be left unchanged if it already exists, but
11040 <prgn>dpkg-divert</prgn> will display a message. To suppress that
11041 message, make the command conditional on the version from which
11042 the package is being upgraded:
11044 if [ upgrade != "$1" ] || dpkg --compare-versions "$2" lt 1.0-2; then
11045 dpkg-divert --package smailwrapper --add --rename \
11046 --divert /usr/sbin/smail.real /usr/sbin/smail
11048 </example> where <tt>1.0-2</tt> is the version at which the
11049 diversion was first added to the package. Running the command
11050 during abort-upgrade is pointless but harmless.
11054 The postrm has to do the reverse:
11056 if [ remove = "$1" -o abort-install = "$1" -o disappear = "$1" ]; then
11057 dpkg-divert --package smailwrapper --remove --rename \
11058 --divert /usr/sbin/smail.real /usr/sbin/smail
11060 </example> If the diversion was added at a particular version, the
11061 postrm should also handle the failure case of upgrading from an
11062 older version (unless the older version is so old that direct
11063 upgrades are no longer supported):
11065 if [ abort-upgrade = "$1" ] && dpkg --compare-versions "$2" lt 1.0-2; then
11066 dpkg-divert --package smailwrapper --remove --rename \
11067 --divert /usr/sbin/smail.real /usr/sbin/smail
11069 </example> where <tt>1.02-2</tt> is the version at which the
11070 diversion was first added to the package. The postrm should not
11071 remove the diversion on upgrades both because there's no reason to
11072 remove the diversion only to immediately re-add it and since the
11073 postrm of the old package is run after unpacking so the removal of
11074 the diversion will fail.
11078 Do not attempt to divert a file which is vitally important for
11079 the system's operation - when using <prgn>dpkg-divert</prgn>
11080 there is a time, after it has been diverted but before
11081 <prgn>dpkg</prgn> has installed the new version, when the file
11082 does not exist.</p>
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