1 <!doctype debiandoc system [
2 <!-- include version information so we don't have to hard code it
3 within the document -->
4 <!entity % versiondata SYSTEM "version.ent"> %versiondata;
5 <!-- current Debian changes file format -->
6 <!entity changesversion "1.8">
12 <title>Debian Policy Manual</title>
13 <author><qref id="authors">The Debian Policy Mailing List</qref></author>
14 <version>version &version;, &date;</version>
17 This manual describes the policy requirements for the Debian
18 distribution. This includes the structure and
19 contents of the Debian archive and several design issues of
20 the operating system, as well as technical requirements that
21 each package must satisfy to be included in the distribution.
26 Copyright © 1996,1997,1998 Ian Jackson
27 and Christian Schwarz.
30 These are the copyright dates of the original Policy manual.
31 Since then, this manual has been updated by many others. No
32 comprehensive collection of copyright notices for subsequent
37 This manual is free software; you may redistribute it and/or
38 modify it under the terms of the GNU General Public License
39 as published by the Free Software Foundation; either version
40 2, or (at your option) any later version.
44 This is distributed in the hope that it will be useful, but
45 <em>without any warranty</em>; without even the implied
46 warranty of merchantability or fitness for a particular
47 purpose. See the GNU General Public License for more
52 A copy of the GNU General Public License is available as
53 <file>/usr/share/common-licenses/GPL</file> in the Debian
54 distribution or on the World Wide Web at
55 <url id="http://www.gnu.org/copyleft/gpl.html"
56 name="the GNU General Public Licence">. You can also
57 obtain it by writing to the Free Software Foundation, Inc.,
58 51 Franklin St, Fifth Floor, Boston, MA 02110-1301, USA.
66 <heading>About this manual</heading>
68 <heading>Scope</heading>
70 This manual describes the policy requirements for the Debian
71 distribution. This includes the structure and
72 contents of the Debian archive and several design issues of the
73 operating system, as well as technical requirements that
74 each package must satisfy to be included in the
79 This manual also describes Debian policy as it relates to
80 creating Debian packages. It is not a tutorial on how to build
81 packages, nor is it exhaustive where it comes to describing
82 the behavior of the packaging system. Instead, this manual
83 attempts to define the interface to the package management
84 system that the developers have to be conversant with.<footnote>
85 Informally, the criteria used for inclusion is that the
86 material meet one of the following requirements:
87 <taglist compact="compact">
88 <tag>Standard interfaces</tag>
90 The material presented represents an interface to
91 the packaging system that is mandated for use, and
92 is used by, a significant number of packages, and
93 therefore should not be changed without peer
94 review. Package maintainers can then rely on this
95 interface not changing, and the package management
96 software authors need to ensure compatibility with
97 this interface definition. (Control file and
98 changelog file formats are examples.)
100 <tag>Chosen Convention</tag>
102 If there are a number of technically viable choices
103 that can be made, but one needs to select one of
104 these options for inter-operability. The version
105 number format is one example.
108 Please note that these are not mutually exclusive;
109 selected conventions often become parts of standard
115 The footnotes present in this manual are
116 merely informative, and are not part of Debian policy itself.
120 The appendices to this manual are not necessarily normative,
121 either. Please see <ref id="pkg-scope"> for more information.
125 In the normative part of this manual,
126 the words <em>must</em>, <em>should</em> and
127 <em>may</em>, and the adjectives <em>required</em>,
128 <em>recommended</em> and <em>optional</em>, are used to
129 distinguish the significance of the various guidelines in
130 this policy document. Packages that do not conform to the
131 guidelines denoted by <em>must</em> (or <em>required</em>)
132 will generally not be considered acceptable for the Debian
133 distribution. Non-conformance with guidelines denoted by
134 <em>should</em> (or <em>recommended</em>) will generally be
135 considered a bug, but will not necessarily render a package
136 unsuitable for distribution. Guidelines denoted by
137 <em>may</em> (or <em>optional</em>) are truly optional and
138 adherence is left to the maintainer's discretion.
142 These classifications are roughly equivalent to the bug
143 severities <em>serious</em> (for <em>must</em> or
144 <em>required</em> directive violations), <em>minor</em>,
145 <em>normal</em> or <em>important</em>
146 (for <em>should</em> or <em>recommended</em> directive
147 violations) and <em>wishlist</em> (for <em>optional</em>
150 Compare RFC 2119. Note, however, that these words are
151 used in a different way in this document.
156 Much of the information presented in this manual will be
157 useful even when building a package which is to be
158 distributed in some other way or is intended for local use
164 <heading>New versions of this document</heading>
167 This manual is distributed via the Debian package
168 <package><url name="debian-policy"
169 id="http://packages.debian.org/debian-policy"></package>
170 (<httpsite>packages.debian.org</httpsite>
171 <httppath>/debian-policy</httppath>).
175 The current version of this document is also available from
176 the Debian web mirrors at
177 <tt><url name="/doc/debian-policy/"
178 id="http://www.debian.org/doc/debian-policy/"></tt>.
180 <httpsite>www.debian.org</httpsite>
181 <httppath>/doc/debian-policy/</httppath>)
182 Also available from the same directory are several other
183 formats: <file>policy.html.tar.gz</file>
184 (<httppath>/doc/debian-policy/policy.html.tar.gz</httppath>),
185 <file>policy.pdf.gz</file>
186 (<httppath>/doc/debian-policy/policy.pdf.gz</httppath>)
187 and <file>policy.ps.gz</file>
188 (<httppath>/doc/debian-policy/policy.ps.gz</httppath>).
192 The <package>debian-policy</package> package also includes the file
193 <file>upgrading-checklist.txt.gz</file> which indicates policy
194 changes between versions of this document.
199 <heading>Authors and Maintainers</heading>
202 Originally called "Debian GNU/Linux Policy Manual", this
203 manual was initially written in 1996 by Ian Jackson.
204 It was revised on November 27th, 1996 by David A. Morris.
205 Christian Schwarz added new sections on March 15th, 1997,
206 and reworked/restructured it in April-July 1997.
207 Christoph Lameter contributed the "Web Standard".
208 Julian Gilbey largely restructured it in 2001.
212 Since September 1998, the responsibility for the contents of
213 this document lies on the <url name="debian-policy mailing list"
214 id="mailto:debian-policy@lists.debian.org">. Proposals
215 are discussed there and inserted into policy after a certain
216 consensus is established.
217 <!-- insert shameless policy-process plug here eventually -->
218 The actual editing is done by a group of maintainers that have
219 no editorial powers. These are the current maintainers:
222 <item>Julian Gilbey</item>
223 <item>Branden Robinson</item>
224 <item>Josip Rodin</item>
225 <item>Manoj Srivastava</item>
230 While the authors of this document have tried hard to avoid
231 typos and other errors, these do still occur. If you discover
232 an error in this manual or if you want to give any
233 comments, suggestions, or criticisms please send an email to
234 the Debian Policy List,
235 <email>debian-policy@lists.debian.org</email>, or submit a
236 bug report against the <tt>debian-policy</tt> package.
240 Please do not try to reach the individual authors or maintainers
241 of the Policy Manual regarding changes to the Policy.
246 <heading>Related documents</heading>
249 There are several other documents other than this Policy Manual
250 that are necessary to fully understand some Debian policies and
255 The external "sub-policy" documents are referred to in:
256 <list compact="compact">
257 <item><ref id="fhs"></item>
258 <item><ref id="virtual_pkg"></item>
259 <item><ref id="menus"></item>
260 <item><ref id="mime"></item>
261 <item><ref id="perl"></item>
262 <item><ref id="maintscriptprompt"></item>
263 <item><ref id="emacs"></item>
268 In addition to those, which carry the weight of policy, there
269 is the Debian Developer's Reference. This document describes
270 procedures and resources for Debian developers, but it is
271 <em>not</em> normative; rather, it includes things that don't
272 belong in the Policy, such as best practices for developers.
276 The Developer's Reference is available in the
277 <package>developers-reference</package> package.
278 It's also available from the Debian web mirrors at
279 <tt><url name="/doc/developers-reference/"
280 id="http://www.debian.org/doc/developers-reference/"></tt>.
284 <sect id="definitions">
285 <heading>Definitions</heading>
288 The following terms are used in this Policy Manual:
292 The character encoding specified by ANSI X3.4-1986 and its
293 predecessor standards, referred to in MIME as US-ASCII, and
294 corresponding to an encoding in eight bits per character of
295 the first 128 <url id="http://www.unicode.org/"
296 name="Unicode"> characters, with the eighth bit always zero.
300 The transformation format (sometimes called encoding) of
301 <url id="http://www.unicode.org/" name="Unicode"> defined by
302 <url id="http://www.rfc-editor.org/rfc/rfc3629.txt"
303 name="RFC 3629">. UTF-8 has the useful property of having
304 ASCII as a subset, so any text encoded in ASCII is trivially
314 <heading>The Debian Archive</heading>
317 The Debian system is maintained and distributed as a
318 collection of <em>packages</em>. Since there are so many of
319 them (currently well over 15000), they are split into
320 <em>sections</em> and given <em>priorities</em> to simplify
321 the handling of them.
325 The effort of the Debian project is to build a free operating
326 system, but not every package we want to make accessible is
327 <em>free</em> in our sense (see the Debian Free Software
328 Guidelines, below), or may be imported/exported without
329 restrictions. Thus, the archive is split into areas<footnote>
330 The Debian archive software uses the term "component" internally
331 and in the Release file format to refer to the division of an
332 archive. The Debian Social Contract simply refers to "areas."
333 This document uses terminology similar to the Social Contract.
334 </footnote> based on their licenses and other restrictions.
338 The aims of this are:
340 <list compact="compact">
341 <item>to allow us to make as much software available as we can</item>
342 <item>to allow us to encourage everyone to write free software,
344 <item>to allow us to make it easy for people to produce
345 CD-ROMs of our system without violating any licenses,
346 import/export restrictions, or any other laws.</item>
351 The <em>main</em> archive area forms the <em>Debian distribution</em>.
355 Packages in the other archive areas (<tt>contrib</tt>,
356 <tt>non-free</tt>) are not considered to be part of the Debian
357 distribution, although we support their use and provide
358 infrastructure for them (such as our bug-tracking system and
359 mailing lists). This Debian Policy Manual applies to these
364 <heading>The Debian Free Software Guidelines</heading>
366 The Debian Free Software Guidelines (DFSG) form our
367 definition of "free software". These are:
369 <tag>1. Free Redistribution
372 The license of a Debian component may not restrict any
373 party from selling or giving away the software as a
374 component of an aggregate software distribution
375 containing programs from several different
376 sources. The license may not require a royalty or
377 other fee for such sale.
382 The program must include source code, and must allow
383 distribution in source code as well as compiled form.
385 <tag>3. Derived Works
388 The license must allow modifications and derived
389 works, and must allow them to be distributed under the
390 same terms as the license of the original software.
392 <tag>4. Integrity of The Author's Source Code
395 The license may restrict source-code from being
396 distributed in modified form <em>only</em> if the
397 license allows the distribution of "patch files"
398 with the source code for the purpose of modifying the
399 program at build time. The license must explicitly
400 permit distribution of software built from modified
401 source code. The license may require derived works to
402 carry a different name or version number from the
403 original software. (This is a compromise. The Debian
404 Project encourages all authors to not restrict any
405 files, source or binary, from being modified.)
407 <tag>5. No Discrimination Against Persons or Groups
410 The license must not discriminate against any person
413 <tag>6. No Discrimination Against Fields of Endeavor
416 The license must not restrict anyone from making use
417 of the program in a specific field of endeavor. For
418 example, it may not restrict the program from being
419 used in a business, or from being used for genetic
422 <tag>7. Distribution of License
425 The rights attached to the program must apply to all
426 to whom the program is redistributed without the need
427 for execution of an additional license by those
430 <tag>8. License Must Not Be Specific to Debian
433 The rights attached to the program must not depend on
434 the program's being part of a Debian system. If the
435 program is extracted from Debian and used or
436 distributed without Debian but otherwise within the
437 terms of the program's license, all parties to whom
438 the program is redistributed must have the same
439 rights as those that are granted in conjunction with
442 <tag>9. License Must Not Contaminate Other Software
445 The license must not place restrictions on other
446 software that is distributed along with the licensed
447 software. For example, the license must not insist
448 that all other programs distributed on the same medium
449 must be free software.
451 <tag>10. Example Licenses
454 The "GPL," "BSD," and "Artistic" licenses are examples of
455 licenses that we consider <em>free</em>.
462 <heading>Archive areas</heading>
465 <heading>The main archive area</heading>
468 The <em>main</em> archive area comprises the Debian
469 distribution. Only the packages in this area are considered
470 part of the distribution. None of the packages in
471 the <em>main</em> archive area require software outside of
472 that area to function. Anyone may use, share, modify and
473 redistribute the packages in this archive area
475 See <url id="http://www.debian.org/intro/free"
476 name="What Does Free Mean?"> for
477 more about what we mean by free software.
482 Every package in <em>main</em> must comply with the DFSG
483 (Debian Free Software Guidelines).
487 In addition, the packages in <em>main</em>
488 <list compact="compact">
490 must not require a package outside of <em>main</em>
491 for compilation or execution (thus, the package must
492 not declare a "Depends", "Recommends", or
493 "Build-Depends" relationship on a non-<em>main</em>
497 must not be so buggy that we refuse to support them,
501 must meet all policy requirements presented in this
510 <heading>The contrib archive area</heading>
513 The <em>contrib</em> archive area contains supplemental
514 packages intended to work with the Debian distribution, but
515 which require software outside of the distribution to either
520 Every package in <em>contrib</em> must comply with the DFSG.
524 In addition, the packages in <em>contrib</em>
525 <list compact="compact">
527 must not be so buggy that we refuse to support them,
531 must meet all policy requirements presented in this
538 Examples of packages which would be included in
539 <em>contrib</em> are:
540 <list compact="compact">
542 free packages which require <em>contrib</em>,
543 <em>non-free</em> packages or packages which are not
544 in our archive at all for compilation or execution,
548 wrapper packages or other sorts of free accessories for
555 <sect1 id="non-free">
556 <heading>The non-free archive area</heading>
559 The <em>non-free</em> archive area contains supplemental
560 packages intended to work with the Debian distribution that do
561 not comply with the DFSG or have other problems that make
562 their distribution problematic. They may not comply with all
563 of the policy requirements in this manual due to restrictions
564 on modifications or other limitations.
568 Packages must be placed in <em>non-free</em> if they are
569 not compliant with the DFSG or are encumbered by patents
570 or other legal issues that make their distribution
575 In addition, the packages in <em>non-free</em>
576 <list compact="compact">
578 must not be so buggy that we refuse to support them,
582 must meet all policy requirements presented in this
583 manual that it is possible for them to meet.
585 It is possible that there are policy
586 requirements which the package is unable to
587 meet, for example, if the source is
588 unavailable. These situations will need to be
589 handled on a case-by-case basis.
598 <sect id="pkgcopyright">
599 <heading>Copyright considerations</heading>
602 Every package must be accompanied by a verbatim copy of its
603 copyright information and distribution license in the file
604 <file>/usr/share/doc/<var>package</var>/copyright</file>
605 (see <ref id="copyrightfile"> for further details).
609 We reserve the right to restrict files from being included
610 anywhere in our archives if
611 <list compact="compact">
613 their use or distribution would break a law,
616 there is an ethical conflict in their distribution or
620 we would have to sign a license for them, or
623 their distribution would conflict with other project
630 Programs whose authors encourage the user to make
631 donations are fine for the main distribution, provided
632 that the authors do not claim that not donating is
633 immoral, unethical, illegal or something similar; in such
634 a case they must go in <em>non-free</em>.
638 Packages whose copyright permission notices (or patent
639 problems) do not even allow redistribution of binaries
640 only, and where no special permission has been obtained,
641 must not be placed on the Debian FTP site and its mirrors
646 Note that under international copyright law (this applies
647 in the United States, too), <em>no</em> distribution or
648 modification of a work is allowed without an explicit
649 notice saying so. Therefore a program without a copyright
650 notice <em>is</em> copyrighted and you may not do anything
651 to it without risking being sued! Likewise if a program
652 has a copyright notice but no statement saying what is
653 permitted then nothing is permitted.
657 Many authors are unaware of the problems that restrictive
658 copyrights (or lack of copyright notices) can cause for
659 the users of their supposedly-free software. It is often
660 worthwhile contacting such authors diplomatically to ask
661 them to modify their license terms. However, this can be a
662 politically difficult thing to do and you should ask for
663 advice on the <tt>debian-legal</tt> mailing list first, as
668 When in doubt about a copyright, send mail to
669 <email>debian-legal@lists.debian.org</email>. Be prepared
670 to provide us with the copyright statement. Software
671 covered by the GPL, public domain software and BSD-like
672 copyrights are safe; be wary of the phrases "commercial
673 use prohibited" and "distribution restricted".
677 <sect id="subsections">
678 <heading>Sections</heading>
681 The packages in the archive areas <em>main</em>,
682 <em>contrib</em> and <em>non-free</em> are grouped further into
683 <em>sections</em> to simplify handling.
687 The archive area and section for each package should be
688 specified in the package's <tt>Section</tt> control record (see
689 <ref id="f-Section">). However, the maintainer of the Debian
690 archive may override this selection to ensure the consistency of
691 the Debian distribution. The <tt>Section</tt> field should be
693 <list compact="compact">
695 <em>section</em> if the package is in the
696 <em>main</em> archive area,
699 <em>area/section</em> if the package is in
700 the <em>contrib</em> or <em>non-free</em>
707 The Debian archive maintainers provide the authoritative
708 list of sections. At present, they are:
709 <em>admin</em>, <em>cli-mono</em>, <em>comm</em>, <em>database</em>,
710 <em>devel</em>, <em>debug</em>, <em>doc</em>, <em>editors</em>,
711 <em>electronics</em>, <em>embedded</em>, <em>fonts</em>,
712 <em>games</em>, <em>gnome</em>, <em>graphics</em>, <em>gnu-r</em>,
713 <em>gnustep</em>, <em>hamradio</em>, <em>haskell</em>,
714 <em>httpd</em>, <em>interpreters</em>, <em>java</em>, <em>kde</em>,
715 <em>kernel</em>, <em>libs</em>, <em>libdevel</em>, <em>lisp</em>,
716 <em>localization</em>, <em>mail</em>, <em>math</em>, <em>misc</em>,
717 <em>net</em>, <em>news</em>, <em>ocaml</em>, <em>oldlibs</em>,
718 <em>otherosfs</em>, <em>perl</em>, <em>php</em>, <em>python</em>,
719 <em>ruby</em>, <em>science</em>, <em>shells</em>, <em>sound</em>,
720 <em>tex</em>, <em>text</em>, <em>utils</em>, <em>vcs</em>,
721 <em>video</em>, <em>web</em>, <em>x11</em>, <em>xfce</em>,
722 <em>zope</em>. The additional section <em>debian-installer</em>
723 contains special packages used by the installer and is not used
724 for normal Debian packages.
728 For more information about the sections and their definitions,
729 see the <url id="http://packages.debian.org/unstable/"
730 name="list of sections in unstable">.
734 <sect id="priorities">
735 <heading>Priorities</heading>
738 Each package should have a <em>priority</em> value, which is
739 included in the package's <em>control record</em>
740 (see <ref id="f-Priority">).
741 This information is used by the Debian package management tools to
742 separate high-priority packages from less-important packages.
746 The following <em>priority levels</em> are recognized by the
747 Debian package management tools.
749 <tag><tt>required</tt></tag>
751 Packages which are necessary for the proper
752 functioning of the system (usually, this means that
753 dpkg functionality depends on these packages).
754 Removing a <tt>required</tt> package may cause your
755 system to become totally broken and you may not even
756 be able to use <prgn>dpkg</prgn> to put things back,
757 so only do so if you know what you are doing. Systems
758 with only the <tt>required</tt> packages are probably
759 unusable, but they do have enough functionality to
760 allow the sysadmin to boot and install more software.
762 <tag><tt>important</tt></tag>
764 Important programs, including those which one would
765 expect to find on any Unix-like system. If the
766 expectation is that an experienced Unix person who
767 found it missing would say "What on earth is going on,
768 where is <prgn>foo</prgn>?", it must be an
769 <tt>important</tt> package.<footnote>
770 This is an important criterion because we are
771 trying to produce, amongst other things, a free
774 Other packages without which the system will not run
775 well or be usable must also have priority
776 <tt>important</tt>. This does
777 <em>not</em> include Emacs, the X Window System, TeX
778 or any other large applications. The
779 <tt>important</tt> packages are just a bare minimum of
780 commonly-expected and necessary tools.
782 <tag><tt>standard</tt></tag>
784 These packages provide a reasonably small but not too
785 limited character-mode system. This is what will be
786 installed by default if the user doesn't select anything
787 else. It doesn't include many large applications.
789 <tag><tt>optional</tt></tag>
791 (In a sense everything that isn't required is
792 optional, but that's not what is meant here.) This is
793 all the software that you might reasonably want to
794 install if you didn't know what it was and don't have
795 specialized requirements. This is a much larger system
796 and includes the X Window System, a full TeX
797 distribution, and many applications. Note that
798 optional packages should not conflict with each other.
800 <tag><tt>extra</tt></tag>
802 This contains all packages that conflict with others
803 with required, important, standard or optional
804 priorities, or are only likely to be useful if you
805 already know what they are or have specialized
806 requirements (such as packages containing only detached
813 Packages must not depend on packages with lower priority
814 values (excluding build-time dependencies). In order to
815 ensure this, the priorities of one or more packages may need
824 <heading>Binary packages</heading>
827 The Debian distribution is based on the Debian
828 package management system, called <prgn>dpkg</prgn>. Thus,
829 all packages in the Debian distribution must be provided
830 in the <tt>.deb</tt> file format.
834 A <tt>.deb</tt> package contains two sets of files: a set of files
835 to install on the system when the package is installed, and a set
836 of files that provide additional metadata about the package or
837 which are executed when the package is installed or removed. This
838 second set of files is called <em>control information files</em>.
839 Among those files are the package maintainer scripts
840 and <file>control</file>, the <qref id="binarycontrolfiles">binary
841 package control file</qref> that contains the control fields for
842 the package. Other control information files
843 include <qref id="sharedlibs-shlibdeps">the <file>shlibs</file>
844 file</qref> used to store shared library dependency information
845 and the <file>conffiles</file> file that lists the package's
846 configuration files (described in <ref id="config-files">).
850 There is unfortunately a collision of terminology here between
851 control information files and files in the Debian control file
852 format. Throughout this document, a <em>control file</em> refers
853 to a file in the Debian control file format. These files are
854 documented in <ref id="controlfields">. Only files referred to
855 specifically as <em>control information files</em> are the files
856 included in the control information file member of
857 the <file>.deb</file> file format used by binary packages. Most
858 control information files are not in the Debian control file
863 <heading>The package name</heading>
866 Every package must have a name that's unique within the Debian
871 The package name is included in the control field
872 <tt>Package</tt>, the format of which is described
873 in <ref id="f-Package">.
874 The package name is also included as a part of the file name
875 of the <tt>.deb</tt> file.
880 <heading>The version of a package</heading>
883 Every package has a version number recorded in its
884 <tt>Version</tt> control file field, described in
885 <ref id="f-Version">.
889 The package management system imposes an ordering on version
890 numbers, so that it can tell whether packages are being up- or
891 downgraded and so that package system front end applications
892 can tell whether a package it finds available is newer than
893 the one installed on the system. The version number format
894 has the most significant parts (as far as comparison is
895 concerned) at the beginning.
899 If an upstream package has problematic version numbers they
900 should be converted to a sane form for use in the
901 <tt>Version</tt> field.
905 <heading>Version numbers based on dates</heading>
908 In general, Debian packages should use the same version
909 numbers as the upstream sources. However, upstream version
910 numbers based on some date formats (sometimes used for
911 development or "snapshot" releases) will not be ordered
912 correctly by the package management software. For
913 example, <prgn>dpkg</prgn> will consider "96May01" to be
914 greater than "96Dec24".
918 To prevent having to use epochs for every new upstream
919 version, the date-based portion of any upstream version number
920 should be given in a way that sorts correctly: four-digit year
921 first, followed by a two-digit numeric month, followed by a
922 two-digit numeric date, possibly with punctuation between the
927 Native Debian packages (i.e., packages which have been written
928 especially for Debian) whose version numbers include dates
929 should also follow these rules. If punctuation is desired
930 between the date components, remember that hyphen (<tt>-</tt>)
931 cannot be used in native package versions. Period
932 (<tt>.</tt>) is normally a good choice.
938 <sect id="maintainer">
939 <heading>The maintainer of a package</heading>
942 Every package must have a maintainer, except for orphaned
943 packages as described below. The maintainer may be one person
944 or a group of people reachable from a common email address, such
945 as a mailing list. The maintainer is responsible for
946 maintaining the Debian packaging files, evaluating and
947 responding appropriately to reported bugs, uploading new
948 versions of the package (either directly or through a sponsor),
949 ensuring that the package is placed in the appropriate archive
950 area and included in Debian releases as appropriate for the
951 stability and utility of the package, and requesting removal of
952 the package from the Debian distribution if it is no longer
953 useful or maintainable.
957 The maintainer must be specified in the <tt>Maintainer</tt>
958 control field with their correct name and a working email
959 address. The email address given in the <tt>Maintainer</tt>
960 control field must accept mail from those role accounts in
961 Debian used to send automated mails regarding the package. This
962 includes non-spam mail from the bug-tracking system, all mail
963 from the Debian archive maintenance software, and other role
964 accounts or automated processes that are commonly agreed on by
965 the project.<footnote>
966 A sample implementation of such a whitelist written for the
967 Mailman mailing list management software is used for mailing
968 lists hosted by alioth.debian.org.
970 If one person or team maintains several packages, they should
971 use the same form of their name and email address in
972 the <tt>Maintainer</tt> fields of those packages.
976 The format of the <tt>Maintainer</tt> control field is
977 described in <ref id="f-Maintainer">.
981 If the maintainer of the package is a team of people with a
982 shared email address, the <tt>Uploaders</tt> control field must
983 be present and must contain at least one human with their
984 personal email address. See <ref id="f-Uploaders"> for the
985 syntax of that field.
989 An orphaned package is one with no current maintainer. Orphaned
990 packages should have their <tt>Maintainer</tt> control field set
991 to <tt>Debian QA Group <packages@qa.debian.org></tt>.
992 These packages are considered maintained by the Debian project
993 as a whole until someone else volunteers to take over
994 maintenance.<footnote>
995 The detailed procedure for gracefully orphaning a package can
996 be found in the Debian Developer's Reference
997 (see <ref id="related">).
1002 <sect id="descriptions">
1003 <heading>The description of a package</heading>
1006 Every Debian package must have a <tt>Description</tt> control
1007 field which contains a synopsis and extended description of the
1008 package. Technical information about the format of the
1009 <tt>Description</tt> field is in <ref id="f-Description">.
1013 The description should describe the package (the program) to a
1014 user (system administrator) who has never met it before so that
1015 they have enough information to decide whether they want to
1016 install it. This description should not just be copied verbatim
1017 from the program's documentation.
1021 Put important information first, both in the synopsis and
1022 extended description. Sometimes only the first part of the
1023 synopsis or of the description will be displayed. You can
1024 assume that there will usually be a way to see the whole
1025 extended description.
1029 The description should also give information about the
1030 significant dependencies and conflicts between this package
1031 and others, so that the user knows why these dependencies and
1032 conflicts have been declared.
1036 Instructions for configuring or using the package should
1037 not be included (that is what installation scripts,
1038 manual pages, info files, etc., are for). Copyright
1039 statements and other administrivia should not be included
1040 either (that is what the copyright file is for).
1043 <sect1 id="synopsis"><heading>The single line synopsis</heading>
1046 The single line synopsis should be kept brief - certainly
1047 under 80 characters.
1051 Do not include the package name in the synopsis line. The
1052 display software knows how to display this already, and you
1053 do not need to state it. Remember that in many situations
1054 the user may only see the synopsis line - make it as
1055 informative as you can.
1060 <sect1 id="extendeddesc"><heading>The extended description</heading>
1063 Do not try to continue the single line synopsis into the
1064 extended description. This will not work correctly when
1065 the full description is displayed, and makes no sense
1066 where only the summary (the single line synopsis) is
1071 The extended description should describe what the package
1072 does and how it relates to the rest of the system (in terms
1073 of, for example, which subsystem it is which part of).
1077 The description field needs to make sense to anyone, even
1078 people who have no idea about any of the things the
1079 package deals with.<footnote>
1080 The blurb that comes with a program in its
1081 announcements and/or <prgn>README</prgn> files is
1082 rarely suitable for use in a description. It is
1083 usually aimed at people who are already in the
1084 community where the package is used.
1093 <heading>Dependencies</heading>
1096 Every package must specify the dependency information
1097 about other packages that are required for the first to
1102 For example, a dependency entry must be provided for any
1103 shared libraries required by a dynamically-linked executable
1104 binary in a package.
1108 Packages are not required to declare any dependencies they
1109 have on other packages which are marked <tt>Essential</tt>
1110 (see below), and should not do so unless they depend on a
1111 particular version of that package.<footnote>
1113 Essential is needed in part to avoid unresolvable dependency
1114 loops on upgrade. If packages add unnecessary dependencies
1115 on packages in this set, the chances that there
1116 <strong>will</strong> be an unresolvable dependency loop
1117 caused by forcing these Essential packages to be configured
1118 first before they need to be is greatly increased. It also
1119 increases the chances that frontends will be unable to
1120 <strong>calculate</strong> an upgrade path, even if one
1124 Also, functionality is rarely ever removed from the
1125 Essential set, but <em>packages</em> have been removed from
1126 the Essential set when the functionality moved to a
1127 different package. So depending on these packages <em>just
1128 in case</em> they stop being essential does way more harm
1135 Sometimes, a package requires another package to be installed
1136 <em>and</em> configured before it can be installed. In this
1137 case, you must specify a <tt>Pre-Depends</tt> entry for
1142 You should not specify a <tt>Pre-Depends</tt> entry for a
1143 package before this has been discussed on the
1144 <tt>debian-devel</tt> mailing list and a consensus about
1145 doing that has been reached.
1149 The format of the package interrelationship control fields is
1150 described in <ref id="relationships">.
1154 <sect id="virtual_pkg">
1155 <heading>Virtual packages</heading>
1158 Sometimes, there are several packages which offer
1159 more-or-less the same functionality. In this case, it's
1160 useful to define a <em>virtual package</em> whose name
1161 describes that common functionality. (The virtual
1162 packages only exist logically, not physically; that's why
1163 they are called <em>virtual</em>.) The packages with this
1164 particular function will then <em>provide</em> the virtual
1165 package. Thus, any other package requiring that function
1166 can simply depend on the virtual package without having to
1167 specify all possible packages individually.
1171 All packages should use virtual package names where
1172 appropriate, and arrange to create new ones if necessary.
1173 They should not use virtual package names (except privately,
1174 amongst a cooperating group of packages) unless they have
1175 been agreed upon and appear in the list of virtual package
1176 names. (See also <ref id="virtual">)
1180 The latest version of the authoritative list of virtual
1181 package names can be found in the <tt>debian-policy</tt> package.
1182 It is also available from the Debian web mirrors at
1183 <tt><url name="/doc/packaging-manuals/virtual-package-names-list.txt"
1184 id="http://www.debian.org/doc/packaging-manuals/virtual-package-names-list.txt"></tt>.
1188 The procedure for updating the list is described in the preface
1195 <heading>Base system</heading>
1198 The <tt>base system</tt> is a minimum subset of the Debian
1199 system that is installed before everything else
1200 on a new system. Only very few packages are allowed to form
1201 part of the base system, in order to keep the required disk
1206 The base system consists of all those packages with priority
1207 <tt>required</tt> or <tt>important</tt>. Many of them will
1208 be tagged <tt>essential</tt> (see below).
1213 <heading>Essential packages</heading>
1216 Essential is defined as the minimal set of functionality that
1217 must be available and usable on the system at all times, even
1218 when packages are in an unconfigured (but unpacked) state.
1219 Packages are tagged <tt>essential</tt> for a system using the
1220 <tt>Essential</tt> control field. The format of the
1221 <tt>Essential</tt> control field is described in <ref
1226 Since these packages cannot be easily removed (one has to
1227 specify an extra <em>force option</em> to
1228 <prgn>dpkg</prgn> to do so), this flag must not be used
1229 unless absolutely necessary. A shared library package
1230 must not be tagged <tt>essential</tt>; dependencies will
1231 prevent its premature removal, and we need to be able to
1232 remove it when it has been superseded.
1236 Since dpkg will not prevent upgrading of other packages
1237 while an <tt>essential</tt> package is in an unconfigured
1238 state, all <tt>essential</tt> packages must supply all of
1239 their core functionality even when unconfigured. If the
1240 package cannot satisfy this requirement it must not be
1241 tagged as essential, and any packages depending on this
1242 package must instead have explicit dependency fields as
1247 Maintainers should take great care in adding any programs,
1248 interfaces, or functionality to <tt>essential</tt> packages.
1249 Packages may assume that functionality provided by
1250 <tt>essential</tt> packages is always available without
1251 declaring explicit dependencies, which means that removing
1252 functionality from the Essential set is very difficult and is
1253 almost never done. Any capability added to an
1254 <tt>essential</tt> package therefore creates an obligation to
1255 support that capability as part of the Essential set in
1260 You must not tag any packages <tt>essential</tt> before
1261 this has been discussed on the <tt>debian-devel</tt>
1262 mailing list and a consensus about doing that has been
1267 <sect id="maintscripts">
1268 <heading>Maintainer Scripts</heading>
1271 The package installation scripts should avoid producing
1272 output which is unnecessary for the user to see and
1273 should rely on <prgn>dpkg</prgn> to stave off boredom on
1274 the part of a user installing many packages. This means,
1275 amongst other things, using the <tt>--quiet</tt> option on
1276 <prgn>install-info</prgn>.
1280 Errors which occur during the execution of an installation
1281 script must be checked and the installation must not
1282 continue after an error.
1286 Note that in general <ref id="scripts"> applies to package
1287 maintainer scripts, too.
1291 You should not use <prgn>dpkg-divert</prgn> on a file belonging
1292 to another package without consulting the maintainer of that
1293 package first. When adding or removing diversions, package
1294 maintainer scripts must provide the <tt>--package</tt> flag
1295 to <prgn>dpkg-divert</prgn> and must not use <tt>--local</tt>.
1299 All packages which supply an instance of a common command
1300 name (or, in general, filename) should generally use
1301 <prgn>update-alternatives</prgn>, so that they may be
1302 installed together. If <prgn>update-alternatives</prgn>
1303 is not used, then each package must use
1304 <tt>Conflicts</tt> to ensure that other packages are
1305 de-installed. (In this case, it may be appropriate to
1306 specify a conflict against earlier versions of something
1307 that previously did not use
1308 <prgn>update-alternatives</prgn>; this is an exception to
1309 the usual rule that versioned conflicts should be
1313 <sect1 id="maintscriptprompt">
1314 <heading>Prompting in maintainer scripts</heading>
1316 Package maintainer scripts may prompt the user if
1317 necessary. Prompting must be done by communicating
1318 through a program, such as <prgn>debconf</prgn>, which
1319 conforms to the Debian Configuration Management
1320 Specification, version 2 or higher.
1324 Packages which are essential, or which are dependencies of
1325 essential packages, may fall back on another prompting method
1326 if no such interface is available when they are executed.
1330 The Debian Configuration Management Specification is included
1331 in the <file>debconf_specification</file> files in the
1332 <package>debian-policy</package> package.
1333 It is also available from the Debian web mirrors at
1334 <tt><url name="/doc/packaging-manuals/debconf_specification.html"
1335 id="http://www.debian.org/doc/packaging-manuals/debconf_specification.html"></tt>.
1339 Packages which use the Debian Configuration Management
1340 Specification may contain the additional control information
1341 files <file>config</file>
1342 and <file>templates</file>. <file>config</file> is an
1343 additional maintainer script used for package configuration,
1344 and <file>templates</file> contains templates used for user
1345 prompting. The <prgn>config</prgn> script might be run before
1346 the <prgn>preinst</prgn> script and before the package is
1347 unpacked or any of its dependencies or pre-dependencies are
1348 satisfied. Therefore it must work using only the tools
1349 present in <em>essential</em> packages.<footnote>
1350 <package>Debconf</package> or another tool that
1351 implements the Debian Configuration Management
1352 Specification will also be installed, and any
1353 versioned dependencies on it will be satisfied
1354 before preconfiguration begins.
1359 Packages which use the Debian Configuration Management
1360 Specification must allow for translation of their user-visible
1361 messages by using a gettext-based system such as the one
1362 provided by the <package>po-debconf</package> package.
1366 Packages should try to minimize the amount of prompting
1367 they need to do, and they should ensure that the user
1368 will only ever be asked each question once. This means
1369 that packages should try to use appropriate shared
1370 configuration files (such as <file>/etc/papersize</file> and
1371 <file>/etc/news/server</file>), and shared
1372 <package>debconf</package> variables rather than each
1373 prompting for their own list of required pieces of
1378 It also means that an upgrade should not ask the same
1379 questions again, unless the user has used
1380 <tt>dpkg --purge</tt> to remove the package's configuration.
1381 The answers to configuration questions should be stored in an
1382 appropriate place in <file>/etc</file> so that the user can
1383 modify them, and how this has been done should be
1388 If a package has a vitally important piece of
1389 information to pass to the user (such as "don't run me
1390 as I am, you must edit the following configuration files
1391 first or you risk your system emitting badly-formatted
1392 messages"), it should display this in the
1393 <prgn>config</prgn> or <prgn>postinst</prgn> script and
1394 prompt the user to hit return to acknowledge the
1395 message. Copyright messages do not count as vitally
1396 important (they belong in
1397 <file>/usr/share/doc/<var>package</var>/copyright</file>);
1398 neither do instructions on how to use a program (these
1399 should be in on-line documentation, where all the users
1404 Any necessary prompting should almost always be confined
1405 to the <prgn>config</prgn> or <prgn>postinst</prgn>
1406 script. If it is done in the <prgn>postinst</prgn>, it
1407 should be protected with a conditional so that
1408 unnecessary prompting doesn't happen if a package's
1409 installation fails and the <prgn>postinst</prgn> is
1410 called with <tt>abort-upgrade</tt>,
1411 <tt>abort-remove</tt> or <tt>abort-deconfigure</tt>.
1421 <heading>Source packages</heading>
1423 <sect id="standardsversion">
1424 <heading>Standards conformance</heading>
1427 Source packages should specify the most recent version number
1428 of this policy document with which your package complied
1429 when it was last updated.
1433 This information may be used to file bug reports
1434 automatically if your package becomes too much out of date.
1438 The version is specified in the <tt>Standards-Version</tt>
1440 The format of the <tt>Standards-Version</tt> field is
1441 described in <ref id="f-Standards-Version">.
1445 You should regularly, and especially if your package has
1446 become out of date, check for the newest Policy Manual
1447 available and update your package, if necessary. When your
1448 package complies with the new standards you should update the
1449 <tt>Standards-Version</tt> source package field and
1450 release it.<footnote>
1451 See the file <file>upgrading-checklist</file> for
1452 information about policy which has changed between
1453 different versions of this document.
1459 <sect id="pkg-relations">
1460 <heading>Package relationships</heading>
1463 Source packages should specify which binary packages they
1464 require to be installed or not to be installed in order to
1465 build correctly. For example, if building a package
1466 requires a certain compiler, then the compiler should be
1467 specified as a build-time dependency.
1471 It is not necessary to explicitly specify build-time
1472 relationships on a minimal set of packages that are always
1473 needed to compile, link and put in a Debian package a
1474 standard "Hello World!" program written in C or C++. The
1475 required packages are called <em>build-essential</em>, and
1476 an informational list can be found in
1477 <file>/usr/share/doc/build-essential/list</file> (which is
1478 contained in the <tt>build-essential</tt>
1481 <list compact="compact">
1483 This allows maintaining the list separately
1484 from the policy documents (the list does not
1485 need the kind of control that the policy
1489 Having a separate package allows one to install
1490 the build-essential packages on a machine, as
1491 well as allowing other packages such as tasks to
1492 require installation of the build-essential
1493 packages using the depends relation.
1496 The separate package allows bug reports against
1497 the list to be categorized separately from
1498 the policy management process in the BTS.
1505 When specifying the set of build-time dependencies, one
1506 should list only those packages explicitly required by the
1507 build. It is not necessary to list packages which are
1508 required merely because some other package in the list of
1509 build-time dependencies depends on them.<footnote>
1510 The reason for this is that dependencies change, and
1511 you should list all those packages, and <em>only</em>
1512 those packages that <em>you</em> need directly. What
1513 others need is their business. For example, if you
1514 only link against <file>libimlib</file>, you will need to
1515 build-depend on <package>libimlib2-dev</package> but
1516 not against any <tt>libjpeg*</tt> packages, even
1517 though <tt>libimlib2-dev</tt> currently depends on
1518 them: installation of <package>libimlib2-dev</package>
1519 will automatically ensure that all of its run-time
1520 dependencies are satisfied.
1525 If build-time dependencies are specified, it must be
1526 possible to build the package and produce working binaries
1527 on a system with only essential and build-essential
1528 packages installed and also those required to satisfy the
1529 build-time relationships (including any implied
1530 relationships). In particular, this means that version
1531 clauses should be used rigorously in build-time
1532 relationships so that one cannot produce bad or
1533 inconsistently configured packages when the relationships
1534 are properly satisfied.
1538 <ref id="relationships"> explains the technical details.
1543 <heading>Changes to the upstream sources</heading>
1546 If changes to the source code are made that are not
1547 specific to the needs of the Debian system, they should be
1548 sent to the upstream authors in whatever form they prefer
1549 so as to be included in the upstream version of the
1554 If you need to configure the package differently for
1555 Debian or for Linux, and the upstream source doesn't
1556 provide a way to do so, you should add such configuration
1557 facilities (for example, a new <prgn>autoconf</prgn> test
1558 or <tt>#define</tt>) and send the patch to the upstream
1559 authors, with the default set to the way they originally
1560 had it. You can then easily override the default in your
1561 <file>debian/rules</file> or wherever is appropriate.
1565 You should make sure that the <prgn>configure</prgn> utility
1566 detects the correct architecture specification string
1567 (refer to <ref id="arch-spec"> for details).
1571 If you need to edit a <prgn>Makefile</prgn> where GNU-style
1572 <prgn>configure</prgn> scripts are used, you should edit the
1573 <file>.in</file> files rather than editing the
1574 <prgn>Makefile</prgn> directly. This allows the user to
1575 reconfigure the package if necessary. You should
1576 <em>not</em> configure the package and edit the generated
1577 <prgn>Makefile</prgn>! This makes it impossible for someone
1578 else to later reconfigure the package without losing the
1584 <sect id="dpkgchangelog">
1585 <heading>Debian changelog: <file>debian/changelog</file></heading>
1588 Changes in the Debian version of the package should be
1589 briefly explained in the Debian changelog file
1590 <file>debian/changelog</file>.<footnote>
1592 Mistakes in changelogs are usually best rectified by
1593 making a new changelog entry rather than "rewriting
1594 history" by editing old changelog entries.
1597 This includes modifications
1598 made in the Debian package compared to the upstream one
1599 as well as other changes and updates to the package.
1601 Although there is nothing stopping an author who is also
1602 the Debian maintainer from using this changelog for all
1603 their changes, it will have to be renamed if the Debian
1604 and upstream maintainers become different people. In such
1605 a case, however, it might be better to maintain the package
1606 as a non-native package.
1611 The format of the <file>debian/changelog</file> allows the
1612 package building tools to discover which version of the package
1613 is being built and find out other release-specific information.
1617 That format is a series of entries like this:
1619 <example compact="compact">
1620 <var>package</var> (<var>version</var>) <var>distribution(s)</var>; urgency=<var>urgency</var>
1622 [optional blank line(s), stripped]
1624 * <var>change details</var>
1625 <var>more change details</var>
1627 [blank line(s), included in output of dpkg-parsechangelog]
1629 * <var>even more change details</var>
1631 [optional blank line(s), stripped]
1633 -- <var>maintainer name</var> <<var>email address</var>><var>[two spaces]</var> <var>date</var>
1638 <var>package</var> and <var>version</var> are the source
1639 package name and version number.
1643 <var>distribution(s)</var> lists the distributions where
1644 this version should be installed when it is uploaded - it
1645 is copied to the <tt>Distribution</tt> field in the
1646 <file>.changes</file> file. See <ref id="f-Distribution">.
1650 <var>urgency</var> is the value for the <tt>Urgency</tt>
1651 field in the <file>.changes</file> file for the upload
1652 (see <ref id="f-Urgency">). It is not possible to specify
1653 an urgency containing commas; commas are used to separate
1654 <tt><var>keyword</var>=<var>value</var></tt> settings in the
1655 <prgn>dpkg</prgn> changelog format (though there is
1656 currently only one useful <var>keyword</var>,
1661 The change details may in fact be any series of lines
1662 starting with at least two spaces, but conventionally each
1663 change starts with an asterisk and a separating space and
1664 continuation lines are indented so as to bring them in
1665 line with the start of the text above. Blank lines may be
1666 used here to separate groups of changes, if desired.
1670 If this upload resolves bugs recorded in the Bug Tracking
1671 System (BTS), they may be automatically closed on the
1672 inclusion of this package into the Debian archive by
1673 including the string: <tt>closes: Bug#<var>nnnnn</var></tt>
1674 in the change details.<footnote>
1675 To be precise, the string should match the following
1676 Perl regular expression:
1678 /closes:\s*(?:bug)?\#?\s?\d+(?:,\s*(?:bug)?\#?\s?\d+)*/i
1680 Then all of the bug numbers listed will be closed by the
1681 archive maintenance script (<prgn>katie</prgn>) using the
1682 <var>version</var> of the changelog entry.
1684 This information is conveyed via the <tt>Closes</tt> field
1685 in the <tt>.changes</tt> file (see <ref id="f-Closes">).
1689 The maintainer name and email address used in the changelog
1690 should be the details of the person uploading <em>this</em>
1691 version. They are <em>not</em> necessarily those of the
1692 usual package maintainer.<footnote>
1693 If the developer uploading the package is not one of the usual
1694 maintainers of the package (as listed in
1695 the <qref id="f-Maintainer"><tt>Maintainer</tt></qref>
1696 or <qref id="f-Uploaders"><tt>Uploaders</tt></qref> control
1697 fields of the package), the first line of the changelog is
1698 conventionally used to explain why a non-maintainer is
1699 uploading the package. The Debian Developer's Reference
1700 (see <ref id="related">) documents the conventions
1702 The information here will be copied to the <tt>Changed-By</tt>
1703 field in the <tt>.changes</tt> file
1704 (see <ref id="f-Changed-By">), and then later used to send an
1705 acknowledgement when the upload has been installed.
1709 The <var>date</var> has the following format<footnote>
1710 This is the same as the format generated by <tt>date
1712 </footnote> (compatible and with the same semantics of
1713 RFC 2822 and RFC 5322):
1714 <example>day-of-week, dd month yyyy hh:mm:ss +zzzz</example>
1716 <list compact="compact">
1718 day-of week is one of: Mon, Tue, Wed, Thu, Fri, Sat, Sun
1721 dd is a one- or two-digit day of the month (01-31)
1724 month is one of: Jan, Feb, Mar, Apr, May, Jun, Jul, Aug,
1727 <item>yyyy is the four-digit year (e.g. 2010)</item>
1728 <item>hh is the two-digit hour (00-23)</item>
1729 <item>mm is the two-digit minutes (00-59)</item>
1730 <item>ss is the two-digit seconds (00-60)</item>
1732 +zzzz or -zzzz is the the time zone offset from Coordinated
1733 Universal Time (UTC). "+" indicates that the time is ahead
1734 of (i.e., east of) UTC and "-" indicates that the time is
1735 behind (i.e., west of) UTC. The first two digits indicate
1736 the hour difference from UTC and the last two digits
1737 indicate the number of additional minutes difference from
1738 UTC. The last two digits must be in the range 00-59.
1744 The first "title" line with the package name must start
1745 at the left hand margin. The "trailer" line with the
1746 maintainer and date details must be preceded by exactly
1747 one space. The maintainer details and the date must be
1748 separated by exactly two spaces.
1752 The entire changelog must be encoded in UTF-8.
1756 For more information on placement of the changelog files
1757 within binary packages, please see <ref id="changelogs">.
1761 <sect id="dpkgcopyright">
1762 <heading>Copyright: <file>debian/copyright</file></heading>
1764 Every package must be accompanied by a verbatim copy of its
1765 copyright information and distribution license in the file
1766 <file>/usr/share/doc/<var>package</var>/copyright</file>
1767 (see <ref id="copyrightfile"> for further details). Also see
1768 <ref id="pkgcopyright"> for further considerations related
1769 to copyrights for packages.
1773 <heading>Error trapping in makefiles</heading>
1776 When <prgn>make</prgn> invokes a command in a makefile
1777 (including your package's upstream makefiles and
1778 <file>debian/rules</file>), it does so using <prgn>sh</prgn>. This
1779 means that <prgn>sh</prgn>'s usual bad error handling
1780 properties apply: if you include a miniature script as one
1781 of the commands in your makefile you'll find that if you
1782 don't do anything about it then errors are not detected
1783 and <prgn>make</prgn> will blithely continue after
1788 Every time you put more than one shell command (this
1789 includes using a loop) in a makefile command you
1790 must make sure that errors are trapped. For
1791 simple compound commands, such as changing directory and
1792 then running a program, using <tt>&&</tt> rather
1793 than semicolon as a command separator is sufficient. For
1794 more complex commands including most loops and
1795 conditionals you should include a separate <tt>set -e</tt>
1796 command at the start of every makefile command that's
1797 actually one of these miniature shell scripts.
1801 <sect id="timestamps">
1802 <heading>Time Stamps</heading>
1804 Maintainers should preserve the modification times of the
1805 upstream source files in a package, as far as is reasonably
1807 The rationale is that there is some information conveyed
1808 by knowing the age of the file, for example, you could
1809 recognize that some documentation is very old by looking
1810 at the modification time, so it would be nice if the
1811 modification time of the upstream source would be
1817 <sect id="restrictions">
1818 <heading>Restrictions on objects in source packages</heading>
1821 The source package may not contain any hard links<footnote>
1823 This is not currently detected when building source
1824 packages, but only when extracting
1828 Hard links may be permitted at some point in the
1829 future, but would require a fair amount of
1832 </footnote>, device special files, sockets or setuid or
1833 setgid files.<footnote>
1834 Setgid directories are allowed.
1839 <sect id="debianrules">
1840 <heading>Main building script: <file>debian/rules</file></heading>
1843 This file must be an executable makefile, and contains the
1844 package-specific recipes for compiling the package and
1845 building binary package(s) from the source.
1849 It must start with the line <tt>#!/usr/bin/make -f</tt>,
1850 so that it can be invoked by saying its name rather than
1851 invoking <prgn>make</prgn> explicitly. That is, invoking
1852 either of <tt>make -f debian/rules <em>args...</em></tt>
1853 or <tt>./debian/rules <em>args...</em></tt> must result in
1858 The following targets are required and must be implemented
1859 by <file>debian/rules</file>: <tt>clean</tt>, <tt>binary</tt>,
1860 <tt>binary-arch</tt>, <tt>binary-indep</tt>, and <tt>build</tt>.
1861 These are the targets called by <prgn>dpkg-buildpackage</prgn>.
1865 Since an interactive <file>debian/rules</file> script makes it
1866 impossible to auto-compile that package and also makes it hard
1867 for other people to reproduce the same binary package, all
1868 required targets must be non-interactive. It also follows that
1869 any target that these targets depend on must also be
1874 The targets are as follows:
1876 <tag><tt>build</tt> (required)</tag>
1879 The <tt>build</tt> target should perform all the
1880 configuration and compilation of the package.
1881 If a package has an interactive pre-build
1882 configuration routine, the Debian source package
1883 must either be built after this has taken place (so
1884 that the binary package can be built without rerunning
1885 the configuration) or the configuration routine
1886 modified to become non-interactive. (The latter is
1887 preferable if there are architecture-specific features
1888 detected by the configuration routine.)
1892 For some packages, notably ones where the same
1893 source tree is compiled in different ways to produce
1894 two binary packages, the <tt>build</tt> target
1895 does not make much sense. For these packages it is
1896 good enough to provide two (or more) targets
1897 (<tt>build-a</tt> and <tt>build-b</tt> or whatever)
1898 for each of the ways of building the package, and a
1899 <tt>build</tt> target that does nothing. The
1900 <tt>binary</tt> target will have to build the
1901 package in each of the possible ways and make the
1902 binary package out of each.
1906 The <tt>build</tt> target must not do anything
1907 that might require root privilege.
1911 The <tt>build</tt> target may need to run the
1912 <tt>clean</tt> target first - see below.
1916 When a package has a configuration and build routine
1917 which takes a long time, or when the makefiles are
1918 poorly designed, or when <tt>build</tt> needs to
1919 run <tt>clean</tt> first, it is a good idea to
1920 <tt>touch build</tt> when the build process is
1921 complete. This will ensure that if <tt>debian/rules
1922 build</tt> is run again it will not rebuild the whole
1924 Another common way to do this is for <tt>build</tt>
1925 to depend on <prgn>build-stamp</prgn> and to do
1926 nothing else, and for the <prgn>build-stamp</prgn>
1927 target to do the building and to <tt>touch
1928 build-stamp</tt> on completion. This is
1929 especially useful if the build routine creates a
1930 file or directory called <tt>build</tt>; in such a
1931 case, <tt>build</tt> will need to be listed as
1932 a phony target (i.e., as a dependency of the
1933 <tt>.PHONY</tt> target). See the documentation of
1934 <prgn>make</prgn> for more information on phony
1940 <tag><tt>build-arch</tt> (optional),
1941 <tt>build-indep</tt> (optional)
1945 A package may also provide both of the targets
1946 <tt>build-arch</tt> and <tt>build-indep</tt>.
1947 The <tt>build-arch</tt> target, if provided, should
1948 perform all the configuration and compilation required for
1949 producing all architecture-dependant binary packages
1950 (those packages for which the body of the
1951 <tt>Architecture</tt> field in <tt>debian/control</tt> is
1952 not <tt>all</tt>). Similarly, the <tt>build-indep</tt>
1953 target, if provided, should perform all the configuration
1954 and compilation required for producing all
1955 architecture-independent binary packages (those packages
1956 for which the body of the <tt>Architecture</tt> field
1957 in <tt>debian/control</tt> is <tt>all</tt>).
1958 The <tt>build</tt> target should depend on those of the
1959 targets <tt>build-arch</tt> and <tt>build-indep</tt> that
1960 are provided in the rules file.<footnote>
1961 The intent of this split is so that binary-only builds
1962 need not install the dependencies required for
1963 the <tt>build-indep</tt> target. However, this is not
1964 yet used in practice since <tt>dpkg-buildpackage
1965 -B</tt>, and therefore the autobuilders,
1966 invoke <tt>build</tt> rather than <tt>build-arch</tt>
1967 due to the difficulties in determining whether the
1968 optional <tt>build-arch</tt> target exists.
1973 If one or both of the targets <tt>build-arch</tt> and
1974 <tt>build-indep</tt> are not provided, then invoking
1975 <file>debian/rules</file> with one of the not-provided
1976 targets as arguments should produce a exit status code
1977 of 2. Usually this is provided automatically by make
1978 if the target is missing.
1982 The <tt>build-arch</tt> and <tt>build-indep</tt> targets
1983 must not do anything that might require root privilege.
1987 <tag><tt>binary</tt> (required), <tt>binary-arch</tt>
1988 (required), <tt>binary-indep</tt> (required)
1992 The <tt>binary</tt> target must be all that is
1993 necessary for the user to build the binary package(s)
1994 produced from this source package. It is
1995 split into two parts: <prgn>binary-arch</prgn> builds
1996 the binary packages which are specific to a particular
1997 architecture, and <tt>binary-indep</tt> builds
1998 those which are not.
2001 <tt>binary</tt> may be (and commonly is) a target with
2002 no commands which simply depends on
2003 <tt>binary-arch</tt> and <tt>binary-indep</tt>.
2006 Both <tt>binary-*</tt> targets should depend on the
2007 <tt>build</tt> target, or on the appropriate
2008 <tt>build-arch</tt> or <tt>build-indep</tt> target, if
2009 provided, so that the package is built if it has not
2010 been already. It should then create the relevant
2011 binary package(s), using <prgn>dpkg-gencontrol</prgn> to
2012 make their control files and <prgn>dpkg-deb</prgn> to
2013 build them and place them in the parent of the top
2018 Both the <tt>binary-arch</tt> and
2019 <tt>binary-indep</tt> targets <em>must</em> exist.
2020 If one of them has nothing to do (which will always be
2021 the case if the source generates only a single binary
2022 package, whether architecture-dependent or not), it
2023 must still exist and must always succeed.
2027 The <tt>binary</tt> targets must be invoked as
2029 The <prgn>fakeroot</prgn> package often allows one
2030 to build a package correctly even without being
2036 <tag><tt>clean</tt> (required)</tag>
2039 This must undo any effects that the <tt>build</tt>
2040 and <tt>binary</tt> targets may have had, except
2041 that it should leave alone any output files created in
2042 the parent directory by a run of a <tt>binary</tt>
2047 If a <tt>build</tt> file is touched at the end of
2048 the <tt>build</tt> target, as suggested above, it
2049 should be removed as the first action that
2050 <tt>clean</tt> performs, so that running
2051 <tt>build</tt> again after an interrupted
2052 <tt>clean</tt> doesn't think that everything is
2057 The <tt>clean</tt> target may need to be
2058 invoked as root if <tt>binary</tt> has been
2059 invoked since the last <tt>clean</tt>, or if
2060 <tt>build</tt> has been invoked as root (since
2061 <tt>build</tt> may create directories, for
2066 <tag><tt>get-orig-source</tt> (optional)</tag>
2069 This target fetches the most recent version of the
2070 original source package from a canonical archive site
2071 (via FTP or WWW, for example), does any necessary
2072 rearrangement to turn it into the original source
2073 tar file format described below, and leaves it in the
2078 This target may be invoked in any directory, and
2079 should take care to clean up any temporary files it
2084 This target is optional, but providing it if
2085 possible is a good idea.
2089 <tag><tt>patch</tt> (optional)</tag>
2092 This target performs whatever additional actions are
2093 required to make the source ready for editing (unpacking
2094 additional upstream archives, applying patches, etc.).
2095 It is recommended to be implemented for any package where
2096 <tt>dpkg-source -x</tt> does not result in source ready
2097 for additional modification. See
2098 <ref id="readmesource">.
2104 The <tt>build</tt>, <tt>binary</tt> and
2105 <tt>clean</tt> targets must be invoked with the current
2106 directory being the package's top-level directory.
2111 Additional targets may exist in <file>debian/rules</file>,
2112 either as published or undocumented interfaces or for the
2113 package's internal use.
2117 The architectures we build on and build for are determined
2118 by <prgn>make</prgn> variables using the
2119 utility <qref id="pkg-dpkg-architecture"><prgn>dpkg-architecture</prgn></qref>.
2120 You can determine the Debian architecture and the GNU style
2121 architecture specification string for the build architecture as
2122 well as for the host architecture. The build architecture is
2123 the architecture on which <file>debian/rules</file> is run and
2124 the package build is performed. The host architecture is the
2125 architecture on which the resulting package will be installed
2126 and run. These are normally the same, but may be different in
2127 the case of cross-compilation (building packages for one
2128 architecture on machines of a different architecture).
2132 Here is a list of supported <prgn>make</prgn> variables:
2133 <list compact="compact">
2135 <tt>DEB_*_ARCH</tt> (the Debian architecture)
2138 <tt>DEB_*_ARCH_CPU</tt> (the Debian CPU name)
2141 <tt>DEB_*_ARCH_OS</tt> (the Debian System name)
2144 <tt>DEB_*_GNU_TYPE</tt> (the GNU style architecture
2145 specification string)
2148 <tt>DEB_*_GNU_CPU</tt> (the CPU part of
2149 <tt>DEB_*_GNU_TYPE</tt>)
2152 <tt>DEB_*_GNU_SYSTEM</tt> (the System part of
2153 <tt>DEB_*_GNU_TYPE</tt>)
2155 where <tt>*</tt> is either <tt>BUILD</tt> for specification of
2156 the build architecture or <tt>HOST</tt> for specification of the
2161 Backward compatibility can be provided in the rules file
2162 by setting the needed variables to suitable default
2163 values; please refer to the documentation of
2164 <prgn>dpkg-architecture</prgn> for details.
2168 It is important to understand that the <tt>DEB_*_ARCH</tt>
2169 string only determines which Debian architecture we are
2170 building on or for. It should not be used to get the CPU
2171 or system information; the <tt>DEB_*_ARCH_CPU</tt> and
2172 <tt>DEB_*_ARCH_OS</tt> variables should be used for that.
2173 GNU style variables should generally only be used with upstream
2177 <sect1 id="debianrules-options">
2178 <heading><file>debian/rules</file> and
2179 <tt>DEB_BUILD_OPTIONS</tt></heading>
2182 Supporting the standardized environment variable
2183 <tt>DEB_BUILD_OPTIONS</tt> is recommended. This variable can
2184 contain several flags to change how a package is compiled and
2185 built. Each flag must be in the form <var>flag</var> or
2186 <var>flag</var>=<var>options</var>. If multiple flags are
2187 given, they must be separated by whitespace.<footnote>
2188 Some packages support any delimiter, but whitespace is the
2189 easiest to parse inside a makefile and avoids ambiguity with
2190 flag values that contain commas.
2192 <var>flag</var> must start with a lowercase letter
2193 (<tt>a-z</tt>) and consist only of lowercase letters,
2194 numbers (<tt>0-9</tt>), and the characters
2195 <tt>-</tt> and <tt>_</tt> (hyphen and underscore).
2196 <var>options</var> must not contain whitespace. The same
2197 tag should not be given multiple times with conflicting
2198 values. Package maintainers may assume that
2199 <tt>DEB_BUILD_OPTIONS</tt> will not contain conflicting tags.
2203 The meaning of the following tags has been standardized:
2207 This tag says to not run any build-time test suite
2208 provided by the package.
2212 The presence of this tag means that the package should
2213 be compiled with a minimum of optimization. For C
2214 programs, it is best to add <tt>-O0</tt> to
2215 <tt>CFLAGS</tt> (although this is usually the default).
2216 Some programs might fail to build or run at this level
2217 of optimization; it may be necessary to use
2218 <tt>-O1</tt>, for example.
2222 This tag means that the debugging symbols should not be
2223 stripped from the binary during installation, so that
2224 debugging information may be included in the package.
2226 <tag>parallel=n</tag>
2228 This tag means that the package should be built using up
2229 to <tt>n</tt> parallel processes if the package build
2230 system supports this.<footnote>
2231 Packages built with <tt>make</tt> can often implement
2232 this by passing the <tt>-j</tt><var>n</var> option to
2235 If the package build system does not support parallel
2236 builds, this string must be ignored. If the package
2237 build system only supports a lower level of concurrency
2238 than <var>n</var>, the package should be built using as
2239 many parallel processes as the package build system
2240 supports. It is up to the package maintainer to decide
2241 whether the package build times are long enough and the
2242 package build system is robust enough to make supporting
2243 parallel builds worthwhile.
2249 Unknown flags must be ignored by <file>debian/rules</file>.
2253 The following makefile snippet is an example of how one may
2254 implement the build options; you will probably have to
2255 massage this example in order to make it work for your
2257 <example compact="compact">
2260 INSTALL_FILE = $(INSTALL) -p -o root -g root -m 644
2261 INSTALL_PROGRAM = $(INSTALL) -p -o root -g root -m 755
2262 INSTALL_SCRIPT = $(INSTALL) -p -o root -g root -m 755
2263 INSTALL_DIR = $(INSTALL) -p -d -o root -g root -m 755
2265 ifneq (,$(filter noopt,$(DEB_BUILD_OPTIONS)))
2270 ifeq (,$(filter nostrip,$(DEB_BUILD_OPTIONS)))
2271 INSTALL_PROGRAM += -s
2273 ifneq (,$(filter parallel=%,$(DEB_BUILD_OPTIONS)))
2274 NUMJOBS = $(patsubst parallel=%,%,$(filter parallel=%,$(DEB_BUILD_OPTIONS)))
2275 MAKEFLAGS += -j$(NUMJOBS)
2280 ifeq (,$(filter nocheck,$(DEB_BUILD_OPTIONS)))
2281 # Code to run the package test suite.
2288 <!-- FIXME: section pkg-srcsubstvars is the same as substvars -->
2289 <sect id="substvars">
2290 <heading>Variable substitutions: <file>debian/substvars</file></heading>
2293 When <prgn>dpkg-gencontrol</prgn>
2294 generates <qref id="binarycontrolfiles">binary package control
2295 files</qref> (<file>DEBIAN/control</file>), it performs variable
2296 substitutions on its output just before writing it. Variable
2297 substitutions have the form <tt>${<var>variable</var>}</tt>.
2298 The optional file <file>debian/substvars</file> contains
2299 variable substitutions to be used; variables can also be set
2300 directly from <file>debian/rules</file> using the <tt>-V</tt>
2301 option to the source packaging commands, and certain predefined
2302 variables are also available.
2306 The <file>debian/substvars</file> file is usually generated and
2307 modified dynamically by <file>debian/rules</file> targets, in
2308 which case it must be removed by the <tt>clean</tt> target.
2312 See <manref name="deb-substvars" section="5"> for full
2313 details about source variable substitutions, including the
2314 format of <file>debian/substvars</file>.</p>
2317 <sect id="debianwatch">
2318 <heading>Optional upstream source location: <file>debian/watch</file></heading>
2321 This is an optional, recommended configuration file for the
2322 <tt>uscan</tt> utility which defines how to automatically scan
2323 ftp or http sites for newly available updates of the
2324 package. This is used
2325 by <url id="http://dehs.alioth.debian.org/"> and other Debian QA
2326 tools to help with quality control and maintenance of the
2327 distribution as a whole.
2332 <sect id="debianfiles">
2333 <heading>Generated files list: <file>debian/files</file></heading>
2336 This file is not a permanent part of the source tree; it
2337 is used while building packages to record which files are
2338 being generated. <prgn>dpkg-genchanges</prgn> uses it
2339 when it generates a <file>.changes</file> file.
2343 It should not exist in a shipped source package, and so it
2344 (and any backup files or temporary files such as
2345 <file>files.new</file><footnote>
2346 <file>files.new</file> is used as a temporary file by
2347 <prgn>dpkg-gencontrol</prgn> and
2348 <prgn>dpkg-distaddfile</prgn> - they write a new
2349 version of <tt>files</tt> here before renaming it,
2350 to avoid leaving a corrupted copy if an error
2352 </footnote>) should be removed by the
2353 <tt>clean</tt> target. It may also be wise to
2354 ensure a fresh start by emptying or removing it at the
2355 start of the <tt>binary</tt> target.
2359 When <prgn>dpkg-gencontrol</prgn> is run for a binary
2360 package, it adds an entry to <file>debian/files</file> for the
2361 <file>.deb</file> file that will be created when <tt>dpkg-deb
2362 --build</tt> is run for that binary package. So for most
2363 packages all that needs to be done with this file is to
2364 delete it in the <tt>clean</tt> target.
2368 If a package upload includes files besides the source
2369 package and any binary packages whose control files were
2370 made with <prgn>dpkg-gencontrol</prgn> then they should be
2371 placed in the parent of the package's top-level directory
2372 and <prgn>dpkg-distaddfile</prgn> should be called to add
2373 the file to the list in <file>debian/files</file>.</p>
2376 <sect id="embeddedfiles">
2377 <heading>Convenience copies of code</heading>
2380 Some software packages include in their distribution convenience
2381 copies of code from other software packages, generally so that
2382 users compiling from source don't have to download multiple
2383 packages. Debian packages should not make use of these
2384 convenience copies unless the included package is explicitly
2385 intended to be used in this way.<footnote>
2386 For example, parts of the GNU build system work like this.
2388 If the included code is already in the Debian archive in the
2389 form of a library, the Debian packaging should ensure that
2390 binary packages reference the libraries already in Debian and
2391 the convenience copy is not used. If the included code is not
2392 already in Debian, it should be packaged separately as a
2393 prerequisite if possible.
2395 Having multiple copies of the same code in Debian is
2396 inefficient, often creates either static linking or shared
2397 library conflicts, and, most importantly, increases the
2398 difficulty of handling security vulnerabilities in the
2404 <sect id="readmesource">
2405 <heading>Source package handling:
2406 <file>debian/README.source</file></heading>
2409 If running <prgn>dpkg-source -x</prgn> on a source package
2410 doesn't produce the source of the package, ready for editing,
2411 and allow one to make changes and run
2412 <prgn>dpkg-buildpackage</prgn> to produce a modified package
2413 without taking any additional steps, creating a
2414 <file>debian/README.source</file> documentation file is
2415 recommended. This file should explain how to do all of the
2418 <item>Generate the fully patched source, in a form ready for
2419 editing, that would be built to create Debian
2420 packages. Doing this with a <tt>patch</tt> target in
2421 <file>debian/rules</file> is recommended; see
2422 <ref id="debianrules">.</item>
2423 <item>Modify the source and save those modifications so that
2424 they will be applied when building the package.</item>
2425 <item>Remove source modifications that are currently being
2426 applied when building the package.</item>
2427 <item>Optionally, document what steps are necessary to
2428 upgrade the Debian source package to a new upstream version,
2429 if applicable.</item>
2431 This explanation should include specific commands and mention
2432 any additional required Debian packages. It should not assume
2433 familiarity with any specific Debian packaging system or patch
2438 This explanation may refer to a documentation file installed by
2439 one of the package's build dependencies provided that the
2440 referenced documentation clearly explains these tasks and is not
2441 a general reference manual.
2445 <file>debian/README.source</file> may also include any other
2446 information that would be helpful to someone modifying the
2447 source package. Even if the package doesn't fit the above
2448 description, maintainers are encouraged to document in a
2449 <file>debian/README.source</file> file any source package with a
2450 particularly complex or unintuitive source layout or build
2451 system (for example, a package that builds the same source
2452 multiple times to generate different binary packages).
2458 <chapt id="controlfields">
2459 <heading>Control files and their fields</heading>
2462 The package management system manipulates data represented in
2463 a common format, known as <em>control data</em>, stored in
2464 <em>control files</em>.
2465 Control files are used for source packages, binary packages and
2466 the <file>.changes</file> files which control the installation
2467 of uploaded files<footnote>
2468 <prgn>dpkg</prgn>'s internal databases are in a similar
2473 <sect id="controlsyntax">
2474 <heading>Syntax of control files</heading>
2477 A control file consists of one or more paragraphs of
2479 The paragraphs are also sometimes referred to as stanzas.
2481 The paragraphs are separated by blank lines. Some control
2482 files allow only one paragraph; others allow several, in
2483 which case each paragraph usually refers to a different
2484 package. (For example, in source packages, the first
2485 paragraph refers to the source package, and later paragraphs
2486 refer to binary packages generated from the source.)
2490 Each paragraph consists of a series of data fields; each
2491 field consists of the field name, followed by a colon and
2492 then the data/value associated with that field. It ends at
2493 the end of the (logical) line. Horizontal whitespace
2494 (spaces and tabs) may occur immediately before or after the
2495 value and is ignored there; it is conventional to put a
2496 single space after the colon. For example, a field might
2498 <example compact="compact">
2501 the field name is <tt>Package</tt> and the field value
2506 A paragraph must not contain more than one instance of a
2507 particular field name.
2511 Many fields' values may span several lines; in this case
2512 each continuation line must start with a space or a tab.
2513 Any trailing spaces or tabs at the end of individual
2514 lines of a field value are ignored.
2518 In fields where it is specified that lines may not wrap,
2519 only a single line of data is allowed and whitespace is not
2520 significant in a field body. Whitespace must not appear
2521 inside names (of packages, architectures, files or anything
2522 else) or version numbers, or between the characters of
2523 multi-character version relationships.
2527 Field names are not case-sensitive, but it is usual to
2528 capitalize the field names using mixed case as shown below.
2529 Field values are case-sensitive unless the description of the
2530 field says otherwise.
2534 Blank lines, or lines consisting only of spaces and tabs,
2535 are not allowed within field values or between fields - that
2536 would mean a new paragraph.
2540 All control files must be encoded in UTF-8.
2544 <sect id="sourcecontrolfiles">
2545 <heading>Source package control files -- <file>debian/control</file></heading>
2548 The <file>debian/control</file> file contains the most vital
2549 (and version-independent) information about the source package
2550 and about the binary packages it creates.
2554 The first paragraph of the control file contains information about
2555 the source package in general. The subsequent sets each describe a
2556 binary package that the source tree builds.
2560 The fields in the general paragraph (the first one, for the source
2563 <list compact="compact">
2564 <item><qref id="f-Source"><tt>Source</tt></qref> (mandatory)</item>
2565 <item><qref id="f-Maintainer"><tt>Maintainer</tt></qref> (mandatory)</item>
2566 <item><qref id="f-Uploaders"><tt>Uploaders</tt></qref></item>
2567 <item><qref id="f-DM-Upload-Allowed"<tt>DM-Upload-Allowed</tt></qref></item>
2568 <item><qref id="f-Section"><tt>Section</tt></qref> (recommended)</item>
2569 <item><qref id="f-Priority"><tt>Priority</tt></qref> (recommended)</item>
2570 <item><qref id="sourcebinarydeps"><tt>Build-Depends</tt> et al</qref></item>
2571 <item><qref id="f-Standards-Version"><tt>Standards-Version</tt></qref> (recommended)</item>
2572 <item><qref id="f-Homepage"><tt>Homepage</tt></qref></item>
2577 The fields in the binary package paragraphs are:
2579 <list compact="compact">
2580 <item><qref id="f-Package"><tt>Package</tt></qref> (mandatory)</item>
2581 <item><qref id="f-Architecture"><tt>Architecture</tt></qref> (mandatory)</item>
2582 <item><qref id="f-Section"><tt>Section</tt></qref> (recommended)</item>
2583 <item><qref id="f-Priority"><tt>Priority</tt></qref> (recommended)</item>
2584 <item><qref id="f-Essential"><tt>Essential</tt></qref></item>
2585 <item><qref id="binarydeps"><tt>Depends</tt> et al</qref></item>
2586 <item><qref id="f-Description"><tt>Description</tt></qref> (mandatory)</item>
2587 <item><qref id="f-Homepage"><tt>Homepage</tt></qref></item>
2592 The syntax and semantics of the fields are described below.
2596 These fields are used by <prgn>dpkg-gencontrol</prgn> to
2597 generate control files for binary packages (see below), by
2598 <prgn>dpkg-genchanges</prgn> to generate the
2599 <file>.changes</file> file to accompany the upload, and by
2600 <prgn>dpkg-source</prgn> when it creates the
2601 <file>.dsc</file> source control file as part of a source
2602 archive. Many fields are permitted to span multiple lines in
2603 <file>debian/control</file> but not in any other control
2604 file. These tools are responsible for removing the line
2605 breaks from such fields when using fields from
2606 <file>debian/control</file> to generate other control files.
2610 The fields here may contain variable references - their
2611 values will be substituted by <prgn>dpkg-gencontrol</prgn>,
2612 <prgn>dpkg-genchanges</prgn> or <prgn>dpkg-source</prgn>
2613 when they generate output control files.
2614 See <ref id="substvars"> for details.
2618 In addition to the control file syntax described <qref
2619 id="controlsyntax">above</qref>, this file may also contain
2620 comment lines starting with <tt>#</tt> without any preceding
2621 whitespace. All such lines are ignored, even in the middle of
2622 continuation lines for a multiline field, and do not end a
2628 <sect id="binarycontrolfiles">
2629 <heading>Binary package control files -- <file>DEBIAN/control</file></heading>
2632 The <file>DEBIAN/control</file> file contains the most vital
2633 (and version-dependent) information about a binary package. It
2634 consists of a single paragraph.
2638 The fields in this file are:
2640 <list compact="compact">
2641 <item><qref id="f-Package"><tt>Package</tt></qref> (mandatory)</item>
2642 <item><qref id="f-Source"><tt>Source</tt></qref></item>
2643 <item><qref id="f-Version"><tt>Version</tt></qref> (mandatory)</item>
2644 <item><qref id="f-Section"><tt>Section</tt></qref> (recommended)</item>
2645 <item><qref id="f-Priority"><tt>Priority</tt></qref> (recommended)</item>
2646 <item><qref id="f-Architecture"><tt>Architecture</tt></qref> (mandatory)</item>
2647 <item><qref id="f-Essential"><tt>Essential</tt></qref></item>
2648 <item><qref id="binarydeps"><tt>Depends</tt> et al</qref></item>
2649 <item><qref id="f-Installed-Size"><tt>Installed-Size</tt></qref></item>
2650 <item><qref id="f-Maintainer"><tt>Maintainer</tt></qref> (mandatory)</item>
2651 <item><qref id="f-Description"><tt>Description</tt></qref> (mandatory)</item>
2652 <item><qref id="f-Homepage"><tt>Homepage</tt></qref></item>
2657 <sect id="debiansourcecontrolfiles">
2658 <heading>Debian source control files -- <tt>.dsc</tt></heading>
2661 This file consists of a single paragraph, possibly surrounded by
2662 a PGP signature. The fields of that paragraph are listed below.
2663 Their syntax is described above, in <ref id="pkg-controlfields">.
2665 <list compact="compact">
2666 <item><qref id="f-Format"><tt>Format</tt></qref> (mandatory)</item>
2667 <item><qref id="f-Source"><tt>Source</tt></qref> (mandatory)</item>
2668 <item><qref id="f-Binary"><tt>Binary</tt></qref></item>
2669 <item><qref id="f-Architecture"><tt>Architecture</tt></qref></item>
2670 <item><qref id="f-Version"><tt>Version</tt></qref> (mandatory)</item>
2671 <item><qref id="f-Maintainer"><tt>Maintainer</tt></qref> (mandatory)</item>
2672 <item><qref id="f-Uploaders"><tt>Uploaders</tt></qref></item>
2673 <item><qref id="f-DM-Upload-Allowed"<tt>DM-Upload-Allowed</tt></qref></item>
2674 <item><qref id="f-Homepage"><tt>Homepage</tt></qref></item>
2675 <item><qref id="f-Standards-Version"><tt>Standards-Version</tt></qref> (recommended)</item>
2676 <item><qref id="sourcebinarydeps"><tt>Build-Depends</tt> et al</qref></item>
2677 <item><qref id="f-Checksums"><tt>Checksums-Sha1</tt>
2678 and <tt>Checksums-Sha256</tt></qref> (recommended)</item>
2679 <item><qref id="f-Files"><tt>Files</tt></qref> (mandatory)</item>
2684 The source package control file is generated by
2685 <prgn>dpkg-source</prgn> when it builds the source
2686 archive, from other files in the source package,
2687 described above. When unpacking, it is checked against
2688 the files and directories in the other parts of the
2694 <sect id="debianchangesfiles">
2695 <heading>Debian changes files -- <file>.changes</file></heading>
2698 The <file>.changes</file> files are used by the Debian archive
2699 maintenance software to process updates to packages. They
2700 consist of a single paragraph, possibly surrounded by a PGP
2701 signature. That paragraph contains information from the
2702 <file>debian/control</file> file and other data about the
2703 source package gathered via <file>debian/changelog</file>
2704 and <file>debian/rules</file>.
2708 <file>.changes</file> files have a format version that is
2709 incremented whenever the documented fields or their meaning
2710 change. This document describes format &changesversion;.
2714 The fields in this file are:
2716 <list compact="compact">
2717 <item><qref id="f-Format"><tt>Format</tt></qref> (mandatory)</item>
2718 <item><qref id="f-Date"><tt>Date</tt></qref> (mandatory)</item>
2719 <item><qref id="f-Source"><tt>Source</tt></qref> (mandatory)</item>
2720 <item><qref id="f-Binary"><tt>Binary</tt></qref> (mandatory)</item>
2721 <item><qref id="f-Architecture"><tt>Architecture</tt></qref> (mandatory)</item>
2722 <item><qref id="f-Version"><tt>Version</tt></qref> (mandatory)</item>
2723 <item><qref id="f-Distribution"><tt>Distribution</tt></qref> (mandatory)</item>
2724 <item><qref id="f-Urgency"><tt>Urgency</tt></qref> (recommended)</item>
2725 <item><qref id="f-Maintainer"><tt>Maintainer</tt></qref> (mandatory)</item>
2726 <item><qref id="f-Changed-By"><tt>Changed-By</tt></qref></item>
2727 <item><qref id="f-Description"><tt>Description</tt></qref> (mandatory)</item>
2728 <item><qref id="f-Closes"><tt>Closes</tt></qref></item>
2729 <item><qref id="f-Changes"><tt>Changes</tt></qref> (mandatory)</item>
2730 <item><qref id="f-Checksums"><tt>Checksums-Sha1</tt>
2731 and <tt>Checksums-Sha256</tt></qref> (recommended)</item>
2732 <item><qref id="f-Files"><tt>Files</tt></qref> (mandatory)</item>
2737 <sect id="controlfieldslist">
2738 <heading>List of fields</heading>
2740 <sect1 id="f-Source">
2741 <heading><tt>Source</tt></heading>
2744 This field identifies the source package name.
2748 In <file>debian/control</file> or a <file>.dsc</file> file,
2749 this field must contain only the name of the source package.
2753 In a binary package control file or a <file>.changes</file>
2754 file, the source package name may be followed by a version
2755 number in parentheses<footnote>
2756 It is customary to leave a space after the package name
2757 if a version number is specified.
2759 This version number may be omitted (and is, by
2760 <prgn>dpkg-gencontrol</prgn>) if it has the same value as
2761 the <tt>Version</tt> field of the binary package in
2762 question. The field itself may be omitted from a binary
2763 package control file when the source package has the same
2764 name and version as the binary package.
2768 Package names (both source and binary,
2769 see <ref id="f-Package">) must consist only of lower case
2770 letters (<tt>a-z</tt>), digits (<tt>0-9</tt>), plus
2771 (<tt>+</tt>) and minus (<tt>-</tt>) signs, and periods
2772 (<tt>.</tt>). They must be at least two characters long and
2773 must start with an alphanumeric character.
2777 <sect1 id="f-Maintainer">
2778 <heading><tt>Maintainer</tt></heading>
2781 The package maintainer's name and email address. The name
2782 must come first, then the email address inside angle
2783 brackets <tt><></tt> (in RFC822 format).
2787 If the maintainer's name contains a full stop then the
2788 whole field will not work directly as an email address due
2789 to a misfeature in the syntax specified in RFC822; a
2790 program using this field as an address must check for this
2791 and correct the problem if necessary (for example by
2792 putting the name in round brackets and moving it to the
2793 end, and bringing the email address forward).
2797 See <ref id="maintainer"> for additional requirements and
2798 information about package maintainers.
2802 <sect1 id="f-Uploaders">
2803 <heading><tt>Uploaders</tt></heading>
2806 List of the names and email addresses of co-maintainers of the
2807 package, if any. If the package has other maintainers besides
2808 the one named in the <qref id="f-Maintainer">Maintainer
2809 field</qref>, their names and email addresses should be listed
2810 here. The format of each entry is the same as that of the
2811 Maintainer field, and multiple entries must be comma
2816 This is normally an optional field, but if
2817 the <tt>Maintainer</tt> control field names a group of people
2818 and a shared email address, the <tt>Uploaders</tt> field must
2819 be present and must contain at least one human with their
2820 personal email address.
2824 Any parser that interprets the Uploaders field in
2825 <file>debian/control</file> must permit it to span multiple
2826 lines. Line breaks in an Uploaders field that spans multiple
2827 lines are not significant and the semantics of the field are
2828 the same as if the line breaks had not been present.
2832 <sect1 id="f-Changed-By">
2833 <heading><tt>Changed-By</tt></heading>
2836 The name and email address of the person who prepared this
2837 version of the package, usually a maintainer. The syntax is
2838 the same as for the <qref id="f-Maintainer">Maintainer
2843 <sect1 id="f-Section">
2844 <heading><tt>Section</tt></heading>
2847 This field specifies an application area into which the package
2848 has been classified. See <ref id="subsections">.
2852 When it appears in the <file>debian/control</file> file,
2853 it gives the value for the subfield of the same name in
2854 the <tt>Files</tt> field of the <file>.changes</file> file.
2855 It also gives the default for the same field in the binary
2860 <sect1 id="f-Priority">
2861 <heading><tt>Priority</tt></heading>
2864 This field represents how important it is that the user
2865 have the package installed. See <ref id="priorities">.
2869 When it appears in the <file>debian/control</file> file,
2870 it gives the value for the subfield of the same name in
2871 the <tt>Files</tt> field of the <file>.changes</file> file.
2872 It also gives the default for the same field in the binary
2877 <sect1 id="f-Package">
2878 <heading><tt>Package</tt></heading>
2881 The name of the binary package.
2885 Binary package names must follow the same syntax and
2886 restrictions as source package names. See <ref id="f-Source">
2891 <sect1 id="f-Architecture">
2892 <heading><tt>Architecture</tt></heading>
2895 Depending on context and the control file used, the
2896 <tt>Architecture</tt> field can include the following sets of
2900 A unique single word identifying a Debian machine
2901 architecture as described in <ref id="arch-spec">.
2904 An architecture wildcard identifying a set of Debian
2905 machine architectures, see <ref id="arch-wildcard-spec">.
2906 <tt>any</tt> matches all Debian machine architectures
2907 and is the most frequently used.
2910 <tt>all</tt>, which indicates an
2911 architecture-independent package.
2914 <tt>source</tt>, which indicates a source package.
2920 In the main <file>debian/control</file> file in the source
2921 package, this field may contain the special
2922 value <tt>all</tt>, the special architecture
2923 wildcard <tt>any</tt>, or a list of specific and wildcard
2924 architectures separated by spaces. If <tt>all</tt>
2925 or <tt>any</tt> appears, that value must be the entire
2926 contents of the field. Most packages will use
2927 either <tt>all</tt> or <tt>any</tt>.
2931 Specifying a specific list of architectures indicates that the
2932 source will build an architecture-dependent package only on
2933 architectures included in the list. Specifying a list of
2934 architecture wildcards indicates that the source will build an
2935 architecture-dependent package on only those architectures
2936 that match any of the specified architecture wildcards.
2937 Specifying a list of architectures or architecture wildcards
2938 other than <tt>any</tt> is for the minority of cases where a
2939 program is not portable or is not useful on some
2940 architectures. Where possible, the program should be made
2945 In the source package control file <file>.dsc</file>, this
2946 field may contain either the architecture
2947 wildcard <tt>any</tt> or a list of architectures and
2948 architecture wildcards separated by spaces. If a list is
2949 given, it may include (or consist solely of) the special
2950 value <tt>all</tt>. In other words, in <file>.dsc</file>
2951 files unlike the <file>debian/control</file>, <tt>all</tt> may
2952 occur in combination with specific architectures.
2953 The <tt>Architecture</tt> field in the source package control
2954 file <file>.dsc</file> is generally constructed from
2955 the <tt>Architecture</tt> fields in
2956 the <file>debian/control</file> in the source package.
2960 Specifying <tt>any</tt> indicates that the source package
2961 isn't dependent on any particular architecture and should
2962 compile fine on any one. The produced binary package(s)
2963 will either be specific to whatever the current build
2964 architecture is or will be architecture-independent.
2968 Specifying only <tt>all</tt> indicates that the source package
2969 will only build architecture-independent packages. If this is
2970 the case, <tt>all</tt> must be used rather than <tt>any</tt>;
2971 <tt>any</tt> implies that the source package will build at
2972 least one architecture-dependent package.
2976 Specifying a list of architectures or architecture wildcards
2977 indicates that the source will build an architecture-dependent
2978 package, and will only work correctly on the listed or
2979 matching architectures. If the source package also builds at
2980 least one architecture-independent package, <tt>all</tt> will
2981 also be included in the list.
2985 In a <file>.changes</file> file, the <tt>Architecture</tt>
2986 field lists the architecture(s) of the package(s) currently
2987 being uploaded. This will be a list; if the source for the
2988 package is also being uploaded, the special
2989 entry <tt>source</tt> is also present. <tt>all</tt> will be
2990 present if any architecture-independent packages are being
2991 uploaded. Architecture wildcards such as <tt>any</tt> must
2992 never occur in the <tt>Architecture</tt> field in
2993 the <file>.changes</file> file.
2997 See <ref id="debianrules"> for information on how to get
2998 the architecture for the build process.
3002 <sect1 id="f-Essential">
3003 <heading><tt>Essential</tt></heading>
3006 This is a boolean field which may occur only in the
3007 control file of a binary package or in a per-package fields
3008 paragraph of a main source control data file.
3012 If set to <tt>yes</tt> then the package management system
3013 will refuse to remove the package (upgrading and replacing
3014 it is still possible). The other possible value is <tt>no</tt>,
3015 which is the same as not having the field at all.
3020 <heading>Package interrelationship fields:
3021 <tt>Depends</tt>, <tt>Pre-Depends</tt>,
3022 <tt>Recommends</tt>, <tt>Suggests</tt>,
3023 <tt>Breaks</tt>, <tt>Conflicts</tt>,
3024 <tt>Provides</tt>, <tt>Replaces</tt>, <tt>Enhances</tt>
3028 These fields describe the package's relationships with
3029 other packages. Their syntax and semantics are described
3030 in <ref id="relationships">.</p>
3033 <sect1 id="f-Standards-Version">
3034 <heading><tt>Standards-Version</tt></heading>
3037 The most recent version of the standards (the policy
3038 manual and associated texts) with which the package
3043 The version number has four components: major and minor
3044 version number and major and minor patch level. When the
3045 standards change in a way that requires every package to
3046 change the major number will be changed. Significant
3047 changes that will require work in many packages will be
3048 signaled by a change to the minor number. The major patch
3049 level will be changed for any change to the meaning of the
3050 standards, however small; the minor patch level will be
3051 changed when only cosmetic, typographical or other edits
3052 are made which neither change the meaning of the document
3053 nor affect the contents of packages.
3057 Thus only the first three components of the policy version
3058 are significant in the <em>Standards-Version</em> control
3059 field, and so either these three components or all four
3060 components may be specified.<footnote>
3061 In the past, people specified the full version number
3062 in the Standards-Version field, for example "2.3.0.0".
3063 Since minor patch-level changes don't introduce new
3064 policy, it was thought it would be better to relax
3065 policy and only require the first 3 components to be
3066 specified, in this example "2.3.0". All four
3067 components may still be used if someone wishes to do so.
3073 <sect1 id="f-Version">
3074 <heading><tt>Version</tt></heading>
3077 The version number of a package. The format is:
3078 [<var>epoch</var><tt>:</tt>]<var>upstream_version</var>[<tt>-</tt><var>debian_revision</var>]
3082 The three components here are:
3084 <tag><var>epoch</var></tag>
3087 This is a single (generally small) unsigned integer. It
3088 may be omitted, in which case zero is assumed. If it is
3089 omitted then the <var>upstream_version</var> may not
3094 It is provided to allow mistakes in the version numbers
3095 of older versions of a package, and also a package's
3096 previous version numbering schemes, to be left behind.
3100 <tag><var>upstream_version</var></tag>
3103 This is the main part of the version number. It is
3104 usually the version number of the original ("upstream")
3105 package from which the <file>.deb</file> file has been made,
3106 if this is applicable. Usually this will be in the same
3107 format as that specified by the upstream author(s);
3108 however, it may need to be reformatted to fit into the
3109 package management system's format and comparison
3114 The comparison behavior of the package management system
3115 with respect to the <var>upstream_version</var> is
3116 described below. The <var>upstream_version</var>
3117 portion of the version number is mandatory.
3121 The <var>upstream_version</var> may contain only
3122 alphanumerics<footnote>
3123 Alphanumerics are <tt>A-Za-z0-9</tt> only.
3125 and the characters <tt>.</tt> <tt>+</tt> <tt>-</tt>
3126 <tt>:</tt> <tt>~</tt> (full stop, plus, hyphen, colon,
3127 tilde) and should start with a digit. If there is no
3128 <var>debian_revision</var> then hyphens are not allowed;
3129 if there is no <var>epoch</var> then colons are not
3134 <tag><var>debian_revision</var></tag>
3137 This part of the version number specifies the version of
3138 the Debian package based on the upstream version. It
3139 may contain only alphanumerics and the characters
3140 <tt>+</tt> <tt>.</tt> <tt>~</tt> (plus, full stop,
3141 tilde) and is compared in the same way as the
3142 <var>upstream_version</var> is.
3146 It is optional; if it isn't present then the
3147 <var>upstream_version</var> may not contain a hyphen.
3148 This format represents the case where a piece of
3149 software was written specifically to be a Debian
3150 package, where the Debian package source must always
3151 be identical to the pristine source and therefore no
3152 revision indication is required.
3156 It is conventional to restart the
3157 <var>debian_revision</var> at <tt>1</tt> each time the
3158 <var>upstream_version</var> is increased.
3162 The package management system will break the version
3163 number apart at the last hyphen in the string (if there
3164 is one) to determine the <var>upstream_version</var> and
3165 <var>debian_revision</var>. The absence of a
3166 <var>debian_revision</var> is equivalent to a
3167 <var>debian_revision</var> of <tt>0</tt>.
3174 When comparing two version numbers, first the <var>epoch</var>
3175 of each are compared, then the <var>upstream_version</var> if
3176 <var>epoch</var> is equal, and then <var>debian_revision</var>
3177 if <var>upstream_version</var> is also equal.
3178 <var>epoch</var> is compared numerically. The
3179 <var>upstream_version</var> and <var>debian_revision</var>
3180 parts are compared by the package management system using the
3181 following algorithm:
3185 The strings are compared from left to right.
3189 First the initial part of each string consisting entirely of
3190 non-digit characters is determined. These two parts (one of
3191 which may be empty) are compared lexically. If a difference
3192 is found it is returned. The lexical comparison is a
3193 comparison of ASCII values modified so that all the letters
3194 sort earlier than all the non-letters and so that a tilde
3195 sorts before anything, even the end of a part. For example,
3196 the following parts are in sorted order from earliest to
3197 latest: <tt>~~</tt>, <tt>~~a</tt>, <tt>~</tt>, the empty part,
3198 <tt>a</tt>.<footnote>
3199 One common use of <tt>~</tt> is for upstream pre-releases.
3200 For example, <tt>1.0~beta1~svn1245</tt> sorts earlier than
3201 <tt>1.0~beta1</tt>, which sorts earlier than <tt>1.0</tt>.
3206 Then the initial part of the remainder of each string which
3207 consists entirely of digit characters is determined. The
3208 numerical values of these two parts are compared, and any
3209 difference found is returned as the result of the comparison.
3210 For these purposes an empty string (which can only occur at
3211 the end of one or both version strings being compared) counts
3216 These two steps (comparing and removing initial non-digit
3217 strings and initial digit strings) are repeated until a
3218 difference is found or both strings are exhausted.
3222 Note that the purpose of epochs is to allow us to leave behind
3223 mistakes in version numbering, and to cope with situations
3224 where the version numbering scheme changes. It is
3225 <em>not</em> intended to cope with version numbers containing
3226 strings of letters which the package management system cannot
3227 interpret (such as <tt>ALPHA</tt> or <tt>pre-</tt>), or with
3228 silly orderings.<footnote>
3229 The author of this manual has heard of a package whose
3230 versions went <tt>1.1</tt>, <tt>1.2</tt>, <tt>1.3</tt>,
3231 <tt>1</tt>, <tt>2.1</tt>, <tt>2.2</tt>, <tt>2</tt> and so
3237 <sect1 id="f-Description">
3238 <heading><tt>Description</tt></heading>
3241 In a source or binary control file, the <tt>Description</tt>
3242 field contains a description of the binary package, consisting
3243 of two parts, the synopsis or the short description, and the
3244 long description. The field's format is as follows:
3249 Description: <single line synopsis>
3250 <extended description over several lines>
3255 The lines in the extended description can have these formats:
3261 Those starting with a single space are part of a paragraph.
3262 Successive lines of this form will be word-wrapped when
3263 displayed. The leading space will usually be stripped off.
3267 Those starting with two or more spaces. These will be
3268 displayed verbatim. If the display cannot be panned
3269 horizontally, the displaying program will line wrap them "hard"
3270 (i.e., without taking account of word breaks). If it can they
3271 will be allowed to trail off to the right. None, one or two
3272 initial spaces may be deleted, but the number of spaces
3273 deleted from each line will be the same (so that you can have
3274 indenting work correctly, for example).
3278 Those containing a single space followed by a single full stop
3279 character. These are rendered as blank lines. This is the
3280 <em>only</em> way to get a blank line<footnote>
3281 Completely empty lines will not be rendered as blank lines.
3282 Instead, they will cause the parser to think you're starting
3283 a whole new record in the control file, and will therefore
3284 likely abort with an error.
3289 Those containing a space, a full stop and some more characters.
3290 These are for future expansion. Do not use them.
3296 Do not use tab characters. Their effect is not predictable.
3300 See <ref id="descriptions"> for further information on this.
3304 In a <file>.changes</file> file, the <tt>Description</tt>
3305 field contains a summary of the descriptions for the packages
3306 being uploaded. For this case, the first line of the field
3307 value (the part on the same line as <tt>Description:</tt>) is
3308 always empty. The content of the field is expressed as
3309 continuation lines, one line per package. Each line is
3310 indented by one space and contains the name of a binary
3311 package, a space, a hyphen (<tt>-</tt>), a space, and the
3312 short description line from that package.
3316 <sect1 id="f-Distribution">
3317 <heading><tt>Distribution</tt></heading>
3320 In a <file>.changes</file> file or parsed changelog output
3321 this contains the (space-separated) name(s) of the
3322 distribution(s) where this version of the package should
3323 be installed. Valid distributions are determined by the
3324 archive maintainers.<footnote>
3325 Example distribution names in the Debian archive used in
3326 <file>.changes</file> files are:
3327 <taglist compact="compact">
3328 <tag><em>unstable</em></tag>
3330 This distribution value refers to the
3331 <em>developmental</em> part of the Debian distribution
3332 tree. Most new packages, new upstream versions of
3333 packages and bug fixes go into the <em>unstable</em>
3337 <tag><em>experimental</em></tag>
3339 The packages with this distribution value are deemed
3340 by their maintainers to be high risk. Oftentimes they
3341 represent early beta or developmental packages from
3342 various sources that the maintainers want people to
3343 try, but are not ready to be a part of the other parts
3344 of the Debian distribution tree.
3349 Others are used for updating stable releases or for
3350 security uploads. More information is available in the
3351 Debian Developer's Reference, section "The Debian
3355 The Debian archive software only supports listing a single
3356 distribution. Migration of packages to other distributions is
3357 handled outside of the upload process.
3362 <heading><tt>Date</tt></heading>
3365 This field includes the date the package was built or last
3366 edited. It must be in the same format as the <var>date</var>
3367 in a <file>debian/changelog</file> entry.
3371 The value of this field is usually extracted from the
3372 <file>debian/changelog</file> file - see
3373 <ref id="dpkgchangelog">).
3377 <sect1 id="f-Format">
3378 <heading><tt>Format</tt></heading>
3381 In <qref id="debianchangesfiles"><file>.changes</file></qref>
3382 files, this field declares the format version of that file.
3383 The syntax of the field value is the same as that of
3384 a <qref id="f-Version">package version number</qref> except
3385 that no epoch or Debian revision is allowed. The format
3386 described in this document is <tt>&changesversion;</tt>.
3390 In <qref id="debiansourcecontrolfiles"><file>.dsc</file>
3391 Debian source control</qref> files, this field declares the
3392 format of the source package. The field value is used by
3393 programs acting on a source package to interpret the list of
3394 files in the source package and determine how to unpack it.
3395 The syntax of the field value is a numeric major revision, a
3396 period, a numeric minor revision, and then an optional subtype
3397 after whitespace, which if specified is an alphanumeric word
3398 in parentheses. The subtype is optional in the syntax but may
3399 be mandatory for particular source format revisions.
3401 The source formats currently supported by the Debian archive
3402 software are <tt>1.0</tt>, <tt>3.0 (native)</tt>,
3403 and <tt>3.0 (quilt)</tt>.
3408 <sect1 id="f-Urgency">
3409 <heading><tt>Urgency</tt></heading>
3412 This is a description of how important it is to upgrade to
3413 this version from previous ones. It consists of a single
3414 keyword taking one of the values <tt>low</tt>,
3415 <tt>medium</tt>, <tt>high</tt>, <tt>emergency</tt>, or
3416 <tt>critical</tt><footnote>
3417 Other urgency values are supported with configuration
3418 changes in the archive software but are not used in Debian.
3419 The urgency affects how quickly a package will be considered
3420 for inclusion into the <tt>testing</tt> distribution and
3421 gives an indication of the importance of any fixes included
3422 in the upload. <tt>Emergency</tt> and <tt>critical</tt> are
3423 treated as synonymous.
3424 </footnote> (not case-sensitive) followed by an optional
3425 commentary (separated by a space) which is usually in
3426 parentheses. For example:
3429 Urgency: low (HIGH for users of diversions)
3435 The value of this field is usually extracted from the
3436 <file>debian/changelog</file> file - see
3437 <ref id="dpkgchangelog">.
3441 <sect1 id="f-Changes">
3442 <heading><tt>Changes</tt></heading>
3445 This field contains the human-readable changes data, describing
3446 the differences between the last version and the current one.
3450 The first line of the field value (the part on the same line
3451 as <tt>Changes:</tt>) is always empty. The content of the
3452 field is expressed as continuation lines, with each line
3453 indented by at least one space. Blank lines must be
3454 represented by a line consisting only of a space and a full
3459 The value of this field is usually extracted from the
3460 <file>debian/changelog</file> file - see
3461 <ref id="dpkgchangelog">).
3465 Each version's change information should be preceded by a
3466 "title" line giving at least the version, distribution(s)
3467 and urgency, in a human-readable way.
3471 If data from several versions is being returned the entry
3472 for the most recent version should be returned first, and
3473 entries should be separated by the representation of a
3474 blank line (the "title" line may also be followed by the
3475 representation of a blank line).
3479 <sect1 id="f-Binary">
3480 <heading><tt>Binary</tt></heading>
3483 This field is a list of binary packages. Its syntax and
3484 meaning varies depending on the control file in which it
3489 When it appears in the <file>.dsc</file> file, it lists binary
3490 packages which a source package can produce, separated by
3492 A space after each comma is conventional.
3493 </footnote>. It may span multiple lines. The source package
3494 does not necessarily produce all of these binary packages for
3495 every architecture. The source control file doesn't contain
3496 details of which architectures are appropriate for which of
3497 the binary packages.
3501 When it appears in a <file>.changes</file> file, it lists the
3502 names of the binary packages being uploaded, separated by
3503 whitespace (not commas). It may span multiple lines.
3507 <sect1 id="f-Installed-Size">
3508 <heading><tt>Installed-Size</tt></heading>
3511 This field appears in the control files of binary packages,
3512 and in the <file>Packages</file> files. It gives an estimate
3513 of the total amount of disk space required to install the
3514 named package. Actual installed size may vary based on block
3515 size, file system properties, or actions taken by package
3520 The disk space is given as the integer value of the estimated
3521 installed size in bytes, divided by 1024 and rounded up.
3525 <sect1 id="f-Files">
3526 <heading><tt>Files</tt></heading>
3529 This field contains a list of files with information about
3530 each one. The exact information and syntax varies with
3535 In all cases, Files is a multiline field. The first line of
3536 the field value (the part on the same line as <tt>Files:</tt>)
3537 is always empty. The content of the field is expressed as
3538 continuation lines, one line per file. Each line must be
3539 indented by one space and contain a number of sub-fields,
3540 separated by spaces, as described below.
3544 In the <file>.dsc</file> file, each line contains the MD5
3545 checksum, size and filename of the tar file and (if
3546 applicable) diff file which make up the remainder of the
3547 source package<footnote>
3548 That is, the parts which are not the <tt>.dsc</tt>.
3549 </footnote>. For example:
3552 c6f698f19f2a2aa07dbb9bbda90a2754 571925 example_1.2.orig.tar.gz
3553 938512f08422f3509ff36f125f5873ba 6220 example_1.2-1.diff.gz
3555 The exact forms of the filenames are described
3556 in <ref id="pkg-sourcearchives">.
3560 In the <file>.changes</file> file this contains one line per
3561 file being uploaded. Each line contains the MD5 checksum,
3562 size, section and priority and the filename. For example:
3565 4c31ab7bfc40d3cf49d7811987390357 1428 text extra example_1.2-1.dsc
3566 c6f698f19f2a2aa07dbb9bbda90a2754 571925 text extra example_1.2.orig.tar.gz
3567 938512f08422f3509ff36f125f5873ba 6220 text extra example_1.2-1.diff.gz
3568 7c98fe853b3bbb47a00e5cd129b6cb56 703542 text extra example_1.2-1_i386.deb
3570 The <qref id="f-Section">section</qref>
3571 and <qref id="f-Priority">priority</qref> are the values of
3572 the corresponding fields in the main source control file. If
3573 no section or priority is specified then <tt>-</tt> should be
3574 used, though section and priority values must be specified for
3575 new packages to be installed properly.
3579 The special value <tt>byhand</tt> for the section in a
3580 <tt>.changes</tt> file indicates that the file in question
3581 is not an ordinary package file and must by installed by
3582 hand by the distribution maintainers. If the section is
3583 <tt>byhand</tt> the priority should be <tt>-</tt>.
3587 If a new Debian revision of a package is being shipped and
3588 no new original source archive is being distributed the
3589 <tt>.dsc</tt> must still contain the <tt>Files</tt> field
3590 entry for the original source archive
3591 <file><var>package</var>_<var>upstream-version</var>.orig.tar.gz</file>,
3592 but the <file>.changes</file> file should leave it out. In
3593 this case the original source archive on the distribution
3594 site must match exactly, byte-for-byte, the original
3595 source archive which was used to generate the
3596 <file>.dsc</file> file and diff which are being uploaded.</p>
3599 <sect1 id="f-Closes">
3600 <heading><tt>Closes</tt></heading>
3603 A space-separated list of bug report numbers that the upload
3604 governed by the .changes file closes.
3608 <sect1 id="f-Homepage">
3609 <heading><tt>Homepage</tt></heading>
3612 The URL of the web site for this package, preferably (when
3613 applicable) the site from which the original source can be
3614 obtained and any additional upstream documentation or
3615 information may be found. The content of this field is a
3616 simple URL without any surrounding characters such as
3621 <sect1 id="f-Checksums">
3622 <heading><tt>Checksums-Sha1</tt>
3623 and <tt>Checksums-Sha256</tt></heading>
3626 These fields contain a list of files with a checksum and size
3627 for each one. Both <tt>Checksums-Sha1</tt>
3628 and <tt>Checksums-Sha256</tt> have the same syntax and differ
3629 only in the checksum algorithm used: SHA-1
3630 for <tt>Checksums-Sha1</tt> and SHA-256
3631 for <tt>Checksums-Sha256</tt>.
3635 <tt>Checksums-Sha1</tt> and <tt>Checksums-Sha256</tt> are
3636 multiline fields. The first line of the field value (the part
3637 on the same line as <tt>Checksums-Sha1:</tt>
3638 or <tt>Checksums-Sha256:</tt>) is always empty. The content
3639 of the field is expressed as continuation lines, one line per
3640 file. Each line consists of the checksum, a space, the file
3641 size, a space, and the file name. For example (from
3642 a <file>.changes</file> file):
3645 1f418afaa01464e63cc1ee8a66a05f0848bd155c 1276 example_1.0-1.dsc
3646 a0ed1456fad61116f868b1855530dbe948e20f06 171602 example_1.0.orig.tar.gz
3647 5e86ecf0671e113b63388dac81dd8d00e00ef298 6137 example_1.0-1.debian.tar.gz
3648 71a0ff7da0faaf608481195f9cf30974b142c183 548402 example_1.0-1_i386.deb
3650 ac9d57254f7e835bed299926fd51bf6f534597cc3fcc52db01c4bffedae81272 1276 example_1.0-1.dsc
3651 0d123be7f51e61c4bf15e5c492b484054be7e90f3081608a5517007bfb1fd128 171602 example_1.0.orig.tar.gz
3652 f54ae966a5f580571ae7d9ef5e1df0bd42d63e27cb505b27957351a495bc6288 6137 example_1.0-1.debian.tar.gz
3653 3bec05c03974fdecd11d020fc2e8250de8404867a8a2ce865160c250eb723664 548402 example_1.0-1_i386.deb
3658 In the <file>.dsc</file> file, these fields should list all
3659 files that make up the source package. In
3660 the <file>.changes</file> file, these fields should list all
3661 files being uploaded. The list of files in these fields
3662 must match the list of files in the <tt>Files</tt> field.
3666 <sect1 id="f-DM-Upload-Allowed">
3667 <heading><tt>DM-Upload-Allowed</tt></heading>
3670 The most recent version of a package uploaded to unstable or
3671 experimental must include the field <tt>DM-Upload-Allowed:
3672 yes</tt> in the source section of its source control file for
3673 the Debian archive to accept uploads signed with a key in the
3674 Debian Maintainer keyring. See the General
3675 Resolution <url id="http://www.debian.org/vote/2007/vote_003"
3676 name="Endorse the concept of Debian Maintainers"> for more
3683 <heading>User-defined fields</heading>
3686 Additional user-defined fields may be added to the
3687 source package control file. Such fields will be
3688 ignored, and not copied to (for example) binary or
3689 source package control files or upload control files.
3693 If you wish to add additional unsupported fields to
3694 these output files you should use the mechanism
3699 Fields in the main source control information file with
3700 names starting <tt>X</tt>, followed by one or more of
3701 the letters <tt>BCS</tt> and a hyphen <tt>-</tt>, will
3702 be copied to the output files. Only the part of the
3703 field name after the hyphen will be used in the output
3704 file. Where the letter <tt>B</tt> is used the field
3705 will appear in binary package control files, where the
3706 letter <tt>S</tt> is used in source package control
3707 files and where <tt>C</tt> is used in upload control
3708 (<tt>.changes</tt>) files.
3712 For example, if the main source information control file
3715 XBS-Comment: I stand between the candle and the star.
3717 then the binary and source package control files will contain the
3720 Comment: I stand between the candle and the star.
3729 <chapt id="maintainerscripts">
3730 <heading>Package maintainer scripts and installation procedure</heading>
3733 <heading>Introduction to package maintainer scripts</heading>
3736 It is possible to supply scripts as part of a package which
3737 the package management system will run for you when your
3738 package is installed, upgraded or removed.
3742 These scripts are the control information
3743 files <prgn>preinst</prgn>, <prgn>postinst</prgn>, <prgn>prerm</prgn>
3744 and <prgn>postrm</prgn>. They must be proper executable files;
3745 if they are scripts (which is recommended), they must start with
3746 the usual <tt>#!</tt> convention. They should be readable and
3747 executable by anyone, and must not be world-writable.
3751 The package management system looks at the exit status from
3752 these scripts. It is important that they exit with a
3753 non-zero status if there is an error, so that the package
3754 management system can stop its processing. For shell
3755 scripts this means that you <em>almost always</em> need to
3756 use <tt>set -e</tt> (this is usually true when writing shell
3757 scripts, in fact). It is also important, of course, that
3758 they exit with a zero status if everything went well.
3762 Additionally, packages interacting with users
3763 using <prgn>debconf</prgn> in the <prgn>postinst</prgn> script
3764 should install a <prgn>config</prgn> script as a control
3765 information file. See <ref id="maintscriptprompt"> for details.
3769 When a package is upgraded a combination of the scripts from
3770 the old and new packages is called during the upgrade
3771 procedure. If your scripts are going to be at all
3772 complicated you need to be aware of this, and may need to
3773 check the arguments to your scripts.
3777 Broadly speaking the <prgn>preinst</prgn> is called before
3778 (a particular version of) a package is installed, and the
3779 <prgn>postinst</prgn> afterwards; the <prgn>prerm</prgn>
3780 before (a version of) a package is removed and the
3781 <prgn>postrm</prgn> afterwards.
3785 Programs called from maintainer scripts should not normally
3786 have a path prepended to them. Before installation is
3787 started, the package management system checks to see if the
3788 programs <prgn>ldconfig</prgn>,
3789 <prgn>start-stop-daemon</prgn>, <prgn>install-info</prgn>,
3790 and <prgn>update-rc.d</prgn> can be found via the
3791 <tt>PATH</tt> environment variable. Those programs, and any
3792 other program that one would expect to be in the
3793 <tt>PATH</tt>, should thus be invoked without an absolute
3794 pathname. Maintainer scripts should also not reset the
3795 <tt>PATH</tt>, though they might choose to modify it by
3796 prepending or appending package-specific directories. These
3797 considerations really apply to all shell scripts.</p>
3800 <sect id="idempotency">
3801 <heading>Maintainer scripts idempotency</heading>
3804 It is necessary for the error recovery procedures that the
3805 scripts be idempotent. This means that if it is run
3806 successfully, and then it is called again, it doesn't bomb
3807 out or cause any harm, but just ensures that everything is
3808 the way it ought to be. If the first call failed, or
3809 aborted half way through for some reason, the second call
3810 should merely do the things that were left undone the first
3811 time, if any, and exit with a success status if everything
3813 This is so that if an error occurs, the user interrupts
3814 <prgn>dpkg</prgn> or some other unforeseen circumstance
3815 happens you don't leave the user with a badly-broken
3816 package when <prgn>dpkg</prgn> attempts to repeat the
3822 <sect id="controllingterminal">
3823 <heading>Controlling terminal for maintainer scripts</heading>
3826 Maintainer scripts are not guaranteed to run with a controlling
3827 terminal and may not be able to interact with the user. They
3828 must be able to fall back to noninteractive behavior if no
3829 controlling terminal is available. Maintainer scripts that
3830 prompt via a program conforming to the Debian Configuration
3831 Management Specification (see <ref id="maintscriptprompt">) may
3832 assume that program will handle falling back to noninteractive
3837 For high-priority prompts without a reasonable default answer,
3838 maintainer scripts may abort if there is no controlling
3839 terminal. However, this situation should be avoided if at all
3840 possible, since it prevents automated or unattended installs.
3841 In most cases, users will consider this to be a bug in the
3846 <sect id="exitstatus">
3847 <heading>Exit status</heading>
3850 Each script must return a zero exit status for
3851 success, or a nonzero one for failure, since the package
3852 management system looks for the exit status of these scripts
3853 and determines what action to take next based on that datum.
3857 <sect id="mscriptsinstact"><heading>Summary of ways maintainer
3862 <list compact="compact">
3864 <var>new-preinst</var> <tt>install</tt>
3867 <var>new-preinst</var> <tt>install</tt> <var>old-version</var>
3870 <var>new-preinst</var> <tt>upgrade</tt> <var>old-version</var>
3873 <var>old-preinst</var> <tt>abort-upgrade</tt>
3874 <var>new-version</var>
3879 <list compact="compact">
3881 <var>postinst</var> <tt>configure</tt>
3882 <var>most-recently-configured-version</var>
3885 <var>old-postinst</var> <tt>abort-upgrade</tt>
3886 <var>new-version</var>
3889 <var>conflictor's-postinst</var> <tt>abort-remove</tt>
3890 <tt>in-favour</tt> <var>package</var>
3891 <var>new-version</var>
3894 <var>postinst</var> <tt>abort-remove</tt>
3897 <var>deconfigured's-postinst</var>
3898 <tt>abort-deconfigure</tt> <tt>in-favour</tt>
3899 <var>failed-install-package</var> <var>version</var>
3900 [<tt>removing</tt> <var>conflicting-package</var>
3906 <list compact="compact">
3908 <var>prerm</var> <tt>remove</tt>
3911 <var>old-prerm</var> <tt>upgrade</tt>
3912 <var>new-version</var>
3915 <var>new-prerm</var> <tt>failed-upgrade</tt>
3916 <var>old-version</var>
3919 <var>conflictor's-prerm</var> <tt>remove</tt>
3920 <tt>in-favour</tt> <var>package</var>
3921 <var>new-version</var>
3924 <var>deconfigured's-prerm</var> <tt>deconfigure</tt>
3925 <tt>in-favour</tt> <var>package-being-installed</var>
3926 <var>version</var> [<tt>removing</tt>
3927 <var>conflicting-package</var>
3933 <list compact="compact">
3935 <var>postrm</var> <tt>remove</tt>
3938 <var>postrm</var> <tt>purge</tt>
3941 <var>old-postrm</var> <tt>upgrade</tt>
3942 <var>new-version</var>
3945 <var>new-postrm</var> <tt>failed-upgrade</tt>
3946 <var>old-version</var>
3949 <var>new-postrm</var> <tt>abort-install</tt>
3952 <var>new-postrm</var> <tt>abort-install</tt>
3953 <var>old-version</var>
3956 <var>new-postrm</var> <tt>abort-upgrade</tt>
3957 <var>old-version</var>
3960 <var>disappearer's-postrm</var> <tt>disappear</tt>
3961 <var>overwriter</var>
3962 <var>overwriter-version</var>
3968 <sect id="unpackphase">
3969 <heading>Details of unpack phase of installation or upgrade</heading>
3972 The procedure on installation/upgrade/overwrite/disappear
3973 (i.e., when running <tt>dpkg --unpack</tt>, or the unpack
3974 stage of <tt>dpkg --install</tt>) is as follows. In each
3975 case, if a major error occurs (unless listed below) the
3976 actions are, in general, run backwards - this means that the
3977 maintainer scripts are run with different arguments in
3978 reverse order. These are the "error unwind" calls listed
3985 If a version of the package is already installed, call
3986 <example compact="compact">
3987 <var>old-prerm</var> upgrade <var>new-version</var>
3991 If the script runs but exits with a non-zero
3992 exit status, <prgn>dpkg</prgn> will attempt:
3993 <example compact="compact">
3994 <var>new-prerm</var> failed-upgrade <var>old-version</var>
3996 If this works, the upgrade continues. If this
3997 does not work, the error unwind:
3998 <example compact="compact">
3999 <var>old-postinst</var> abort-upgrade <var>new-version</var>
4001 If this works, then the old-version is
4002 "Installed", if not, the old version is in a
4003 "Half-Configured" state.
4009 If a "conflicting" package is being removed at the same time,
4010 or if any package will be broken (due to <tt>Breaks</tt>):
4013 If <tt>--auto-deconfigure</tt> is
4014 specified, call, for each package to be deconfigured
4015 due to <tt>Breaks</tt>:
4016 <example compact="compact">
4017 <var>deconfigured's-prerm</var> deconfigure \
4018 in-favour <var>package-being-installed</var> <var>version</var>
4021 <example compact="compact">
4022 <var>deconfigured's-postinst</var> abort-deconfigure \
4023 in-favour <var>package-being-installed-but-failed</var> <var>version</var>
4025 The deconfigured packages are marked as
4026 requiring configuration, so that if
4027 <tt>--install</tt> is used they will be
4028 configured again if possible.
4031 If any packages depended on a conflicting
4032 package being removed and <tt>--auto-deconfigure</tt> is
4033 specified, call, for each such package:
4034 <example compact="compact">
4035 <var>deconfigured's-prerm</var> deconfigure \
4036 in-favour <var>package-being-installed</var> <var>version</var> \
4037 removing <var>conflicting-package</var> <var>version</var>
4040 <example compact="compact">
4041 <var>deconfigured's-postinst</var> abort-deconfigure \
4042 in-favour <var>package-being-installed-but-failed</var> <var>version</var> \
4043 removing <var>conflicting-package</var> <var>version</var>
4045 The deconfigured packages are marked as
4046 requiring configuration, so that if
4047 <tt>--install</tt> is used they will be
4048 configured again if possible.
4051 To prepare for removal of each conflicting package, call:
4052 <example compact="compact">
4053 <var>conflictor's-prerm</var> remove \
4054 in-favour <var>package</var> <var>new-version</var>
4057 <example compact="compact">
4058 <var>conflictor's-postinst</var> abort-remove \
4059 in-favour <var>package</var> <var>new-version</var>
4068 If the package is being upgraded, call:
4069 <example compact="compact">
4070 <var>new-preinst</var> upgrade <var>old-version</var>
4072 If this fails, we call:
4074 <var>new-postrm</var> abort-upgrade <var>old-version</var>
4081 <var>old-postinst</var> abort-upgrade <var>new-version</var>
4083 is called. If this works, then the old version
4084 is in an "Installed" state, or else it is left
4085 in an "Unpacked" state.
4090 If it fails, then the old version is left
4091 in an "Half-Installed" state.
4098 Otherwise, if the package had some configuration
4099 files from a previous version installed (i.e., it
4100 is in the "configuration files only" state):
4101 <example compact="compact">
4102 <var>new-preinst</var> install <var>old-version</var>
4106 <var>new-postrm</var> abort-install <var>old-version</var>
4108 If this fails, the package is left in a
4109 "Half-Installed" state, which requires a
4110 reinstall. If it works, the packages is left in
4111 a "Config-Files" state.
4114 Otherwise (i.e., the package was completely purged):
4115 <example compact="compact">
4116 <var>new-preinst</var> install
4119 <example compact="compact">
4120 <var>new-postrm</var> abort-install
4122 If the error-unwind fails, the package is in a
4123 "Half-Installed" phase, and requires a
4124 reinstall. If the error unwind works, the
4125 package is in a not installed state.
4132 The new package's files are unpacked, overwriting any
4133 that may be on the system already, for example any
4134 from the old version of the same package or from
4135 another package. Backups of the old files are kept
4136 temporarily, and if anything goes wrong the package
4137 management system will attempt to put them back as
4138 part of the error unwind.
4142 It is an error for a package to contain files which
4143 are on the system in another package, unless
4144 <tt>Replaces</tt> is used (see <ref id="replaces">).
4146 The following paragraph is not currently the case:
4147 Currently the <tt>- - force-overwrite</tt> flag is
4148 enabled, downgrading it to a warning, but this may not
4154 It is a more serious error for a package to contain a
4155 plain file or other kind of non-directory where another
4156 package has a directory (again, unless
4157 <tt>Replaces</tt> is used). This error can be
4158 overridden if desired using
4159 <tt>--force-overwrite-dir</tt>, but this is not
4164 Packages which overwrite each other's files produce
4165 behavior which, though deterministic, is hard for the
4166 system administrator to understand. It can easily
4167 lead to "missing" programs if, for example, a package
4168 is installed which overwrites a file from another
4169 package, and is then removed again.<footnote>
4170 Part of the problem is due to what is arguably a
4171 bug in <prgn>dpkg</prgn>.
4176 A directory will never be replaced by a symbolic link
4177 to a directory or vice versa; instead, the existing
4178 state (symlink or not) will be left alone and
4179 <prgn>dpkg</prgn> will follow the symlink if there is
4188 If the package is being upgraded, call
4189 <example compact="compact">
4190 <var>old-postrm</var> upgrade <var>new-version</var>
4194 If this fails, <prgn>dpkg</prgn> will attempt:
4195 <example compact="compact">
4196 <var>new-postrm</var> failed-upgrade <var>old-version</var>
4198 If this works, installation continues. If not,
4200 <example compact="compact">
4201 <var>old-preinst</var> abort-upgrade <var>new-version</var>
4203 If this fails, the old version is left in a
4204 "Half-Installed" state. If it works, dpkg now
4206 <example compact="compact">
4207 <var>new-postrm</var> abort-upgrade <var>old-version</var>
4209 If this fails, the old version is left in a
4210 "Half-Installed" state. If it works, dpkg now
4212 <example compact="compact">
4213 <var>old-postinst</var> abort-upgrade <var>new-version</var>
4215 If this fails, the old version is in an
4222 This is the point of no return - if
4223 <prgn>dpkg</prgn> gets this far, it won't back off
4224 past this point if an error occurs. This will
4225 leave the package in a fairly bad state, which
4226 will require a successful re-installation to clear
4227 up, but it's when <prgn>dpkg</prgn> starts doing
4228 things that are irreversible.
4233 Any files which were in the old version of the package
4234 but not in the new are removed.
4238 The new file list replaces the old.
4242 The new maintainer scripts replace the old.
4246 Any packages all of whose files have been overwritten
4247 during the installation, and which aren't required for
4248 dependencies, are considered to have been removed.
4249 For each such package
4252 <prgn>dpkg</prgn> calls:
4253 <example compact="compact">
4254 <var>disappearer's-postrm</var> disappear \
4255 <var>overwriter</var> <var>overwriter-version</var>
4259 The package's maintainer scripts are removed.
4262 It is noted in the status database as being in a
4263 sane state, namely not installed (any conffiles
4264 it may have are ignored, rather than being
4265 removed by <prgn>dpkg</prgn>). Note that
4266 disappearing packages do not have their prerm
4267 called, because <prgn>dpkg</prgn> doesn't know
4268 in advance that the package is going to
4275 Any files in the package we're unpacking that are also
4276 listed in the file lists of other packages are removed
4277 from those lists. (This will lobotomize the file list
4278 of the "conflicting" package if there is one.)
4282 The backup files made during installation, above, are
4288 The new package's status is now sane, and recorded as
4293 Here is another point of no return - if the
4294 conflicting package's removal fails we do not unwind
4295 the rest of the installation; the conflicting package
4296 is left in a half-removed limbo.
4301 If there was a conflicting package we go and do the
4302 removal actions (described below), starting with the
4303 removal of the conflicting package's files (any that
4304 are also in the package being installed have already
4305 been removed from the conflicting package's file list,
4306 and so do not get removed now).
4312 <sect id="configdetails"><heading>Details of configuration</heading>
4315 When we configure a package (this happens with <tt>dpkg
4316 --install</tt> and <tt>dpkg --configure</tt>), we first
4317 update any <tt>conffile</tt>s and then call:
4318 <example compact="compact">
4319 <var>postinst</var> configure <var>most-recently-configured-version</var>
4324 No attempt is made to unwind after errors during
4325 configuration. If the configuration fails, the package is in
4326 a "Failed Config" state, and an error message is generated.
4330 If there is no most recently configured version
4331 <prgn>dpkg</prgn> will pass a null argument.
4334 Historical note: Truly ancient (pre-1997) versions of
4335 <prgn>dpkg</prgn> passed <tt><unknown></tt>
4336 (including the angle brackets) in this case. Even older
4337 ones did not pass a second argument at all, under any
4338 circumstance. Note that upgrades using such an old dpkg
4339 version are unlikely to work for other reasons, even if
4340 this old argument behavior is handled by your postinst script.
4346 <sect id="removedetails"><heading>Details of removal and/or
4347 configuration purging</heading>
4353 <example compact="compact">
4354 <var>prerm</var> remove
4358 If prerm fails during replacement due to conflict
4360 <var>conflictor's-postinst</var> abort-remove \
4361 in-favour <var>package</var> <var>new-version</var>
4365 <var>postinst</var> abort-remove
4369 If this fails, the package is in a "Half-Configured"
4370 state, or else it remains "Installed".
4374 The package's files are removed (except <tt>conffile</tt>s).
4377 <example compact="compact">
4378 <var>postrm</var> remove
4382 If it fails, there's no error unwind, and the package is in
4383 an "Half-Installed" state.
4388 All the maintainer scripts except the <prgn>postrm</prgn>
4393 If we aren't purging the package we stop here. Note
4394 that packages which have no <prgn>postrm</prgn> and no
4395 <tt>conffile</tt>s are automatically purged when
4396 removed, as there is no difference except for the
4397 <prgn>dpkg</prgn> status.
4401 The <tt>conffile</tt>s and any backup files
4402 (<tt>~</tt>-files, <tt>#*#</tt> files,
4403 <tt>%</tt>-files, <tt>.dpkg-{old,new,tmp}</tt>, etc.)
4408 <example compact="compact">
4409 <var>postrm</var> purge
4413 If this fails, the package remains in a "Config-Files"
4418 The package's file list is removed.
4427 <chapt id="relationships">
4428 <heading>Declaring relationships between packages</heading>
4430 <sect id="depsyntax">
4431 <heading>Syntax of relationship fields</heading>
4434 These fields all have a uniform syntax. They are a list of
4435 package names separated by commas.
4439 In the <tt>Depends</tt>, <tt>Recommends</tt>,
4440 <tt>Suggests</tt>, <tt>Pre-Depends</tt>,
4441 <tt>Build-Depends</tt> and <tt>Build-Depends-Indep</tt>
4442 control fields of the package, which declare
4443 dependencies on other packages, the package names listed may
4444 also include lists of alternative package names, separated
4445 by vertical bar (pipe) symbols <tt>|</tt>. In such a case,
4446 if any one of the alternative packages is installed, that
4447 part of the dependency is considered to be satisfied.
4451 All of the fields except for <tt>Provides</tt> may restrict
4452 their applicability to particular versions of each named
4453 package. This is done in parentheses after each individual
4454 package name; the parentheses should contain a relation from
4455 the list below followed by a version number, in the format
4456 described in <ref id="f-Version">.
4460 The relations allowed are <tt><<</tt>, <tt><=</tt>,
4461 <tt>=</tt>, <tt>>=</tt> and <tt>>></tt> for
4462 strictly earlier, earlier or equal, exactly equal, later or
4463 equal and strictly later, respectively. The deprecated
4464 forms <tt><</tt> and <tt>></tt> were used to mean
4465 earlier/later or equal, rather than strictly earlier/later,
4466 so they should not appear in new packages (though
4467 <prgn>dpkg</prgn> still supports them).
4471 Whitespace may appear at any point in the version
4472 specification subject to the rules in <ref
4473 id="controlsyntax">, and must appear where it's necessary to
4474 disambiguate; it is not otherwise significant. All of the
4475 relationship fields may span multiple lines. For
4476 consistency and in case of future changes to
4477 <prgn>dpkg</prgn> it is recommended that a single space be
4478 used after a version relationship and before a version
4479 number; it is also conventional to put a single space after
4480 each comma, on either side of each vertical bar, and before
4481 each open parenthesis. When wrapping a relationship field, it
4482 is conventional to do so after a comma and before the space
4483 following that comma.
4487 For example, a list of dependencies might appear as:
4488 <example compact="compact">
4491 Depends: libc6 (>= 2.2.1), exim | mail-transport-agent
4496 Relationships may be restricted to a certain set of
4497 architectures. This is indicated in brackets after each
4498 individual package name and the optional version specification.
4499 The brackets enclose a list of Debian architecture names
4500 separated by whitespace. Exclamation marks may be prepended to
4501 each of the names. (It is not permitted for some names to be
4502 prepended with exclamation marks while others aren't.)
4506 For build relationship fields
4507 (<tt>Build-Depends</tt>, <tt>Build-Depends-Indep</tt>,
4508 <tt>Build-Conflicts</tt> and <tt>Build-Conflicts-Indep</tt>), if
4509 the current Debian host architecture is not in this list and
4510 there are no exclamation marks in the list, or it is in the list
4511 with a prepended exclamation mark, the package name and the
4512 associated version specification are ignored completely for the
4513 purposes of defining the relationships.
4518 <example compact="compact">
4520 Build-Depends-Indep: texinfo
4521 Build-Depends: kernel-headers-2.2.10 [!hurd-i386],
4522 hurd-dev [hurd-i386], gnumach-dev [hurd-i386]
4524 requires <tt>kernel-headers-2.2.10</tt> on all architectures
4525 other than hurd-i386 and requires <tt>hurd-dev</tt> and
4526 <tt>gnumach-dev</tt> only on hurd-i386.
4530 For binary relationship fields, the architecture restriction
4531 syntax is only supported in the source package control
4532 file <file>debian/control</file>. When the corresponding binary
4533 package control file is generated, the relationship will either
4534 be omitted or included without the architecture restriction
4535 based on the architecture of the binary package. This means
4536 that architecture restrictions must not be used in binary
4537 relationship fields for architecture-independent packages
4538 (<tt>Architecture: all</tt>).
4543 <example compact="compact">
4544 Depends: foo [i386], bar [amd64]
4546 becomes <tt>Depends: foo</tt> when the package is built on
4547 the <tt>i386</tt> architecture, <tt>Depends: bar</tt> when the
4548 package is built on the <tt>amd64</tt> architecture, and omitted
4549 entirely in binary packages built on all other architectures.
4553 If the architecture-restricted dependency is part of a set of
4554 alternatives using <tt>|</tt>, that alternative is ignored
4555 completely on architectures that do not match the restriction.
4557 <example compact="compact">
4558 Build-Depends: foo [!i386] | bar [!amd64]
4560 is equivalent to <tt>bar</tt> on the i386 architecture, to
4561 <tt>foo</tt> on the amd64 architecture, and to <tt>foo |
4562 bar</tt> on all other architectures.
4566 Relationships may also be restricted to a certain set of
4567 architectures using architecture wildcards. The syntax for
4568 declaring such restrictions is the same as declaring
4569 restrictions using a certain set of architectures without
4570 architecture wildcards. For example:
4571 <example compact="compact">
4572 Build-Depends: foo [linux-any], bar [any-i386], baz [!linux-any]
4574 is equivalent to <tt>foo</tt> on architectures using the Linux
4575 kernel and any cpu, <tt>bar</tt> on architectures using any
4576 kernel and an i386 cpu, and <tt>baz</tt> on any architecture
4577 using a kernel other than Linux.
4581 Note that the binary package relationship fields such as
4582 <tt>Depends</tt> appear in one of the binary package
4583 sections of the control file, whereas the build-time
4584 relationships such as <tt>Build-Depends</tt> appear in the
4585 source package section of the control file (which is the
4590 <sect id="binarydeps">
4591 <heading>Binary Dependencies - <tt>Depends</tt>,
4592 <tt>Recommends</tt>, <tt>Suggests</tt>, <tt>Enhances</tt>,
4593 <tt>Pre-Depends</tt>
4597 Packages can declare in their control file that they have
4598 certain relationships to other packages - for example, that
4599 they may not be installed at the same time as certain other
4600 packages, and/or that they depend on the presence of others.
4604 This is done using the <tt>Depends</tt>, <tt>Pre-Depends</tt>,
4605 <tt>Recommends</tt>, <tt>Suggests</tt>, <tt>Enhances</tt>,
4606 <tt>Breaks</tt> and <tt>Conflicts</tt> control fields.
4607 <tt>Breaks</tt> is described in <ref id="breaks">, and
4608 <tt>Conflicts</tt> is described in <ref id="conflicts">. The
4609 rest are described below.
4613 These seven fields are used to declare a dependency
4614 relationship by one package on another. Except for
4615 <tt>Enhances</tt> and <tt>Breaks</tt>, they appear in the
4616 depending (binary) package's control file.
4617 (<tt>Enhances</tt> appears in the recommending package's
4618 control file, and <tt>Breaks</tt> appears in the version of
4619 depended-on package which causes the named package to
4624 A <tt>Depends</tt> field takes effect <em>only</em> when a
4625 package is to be configured. It does not prevent a package
4626 being on the system in an unconfigured state while its
4627 dependencies are unsatisfied, and it is possible to replace
4628 a package whose dependencies are satisfied and which is
4629 properly installed with a different version whose
4630 dependencies are not and cannot be satisfied; when this is
4631 done the depending package will be left unconfigured (since
4632 attempts to configure it will give errors) and will not
4633 function properly. If it is necessary, a
4634 <tt>Pre-Depends</tt> field can be used, which has a partial
4635 effect even when a package is being unpacked, as explained
4636 in detail below. (The other three dependency fields,
4637 <tt>Recommends</tt>, <tt>Suggests</tt> and
4638 <tt>Enhances</tt>, are only used by the various front-ends
4639 to <prgn>dpkg</prgn> such as <prgn>apt-get</prgn>,
4640 <prgn>aptitude</prgn>, and <prgn>dselect</prgn>.)
4644 For this reason packages in an installation run are usually
4645 all unpacked first and all configured later; this gives
4646 later versions of packages with dependencies on later
4647 versions of other packages the opportunity to have their
4648 dependencies satisfied.
4652 In case of circular dependencies, since installation or
4653 removal order honoring the dependency order can't be
4654 established, dependency loops are broken at some point
4655 (based on rules below), and some packages may not be able to
4656 rely on their dependencies being present when being
4657 installed or removed, depending on which side of the break
4658 of the circular dependency loop they happen to be on. If one
4659 of the packages in the loop has no postinst script, then the
4660 cycle will be broken at that package, so as to ensure that
4661 all postinst scripts run with the dependencies properly
4662 configured if this is possible. Otherwise the breaking point
4667 The <tt>Depends</tt> field thus allows package maintainers
4668 to impose an order in which packages should be configured.
4672 The meaning of the five dependency fields is as follows:
4674 <tag><tt>Depends</tt></tag>
4677 This declares an absolute dependency. A package will
4678 not be configured unless all of the packages listed in
4679 its <tt>Depends</tt> field have been correctly
4684 The <tt>Depends</tt> field should be used if the
4685 depended-on package is required for the depending
4686 package to provide a significant amount of
4691 The <tt>Depends</tt> field should also be used if the
4692 <prgn>postinst</prgn>, <prgn>prerm</prgn> or
4693 <prgn>postrm</prgn> scripts require the package to be
4694 present in order to run. Note, however, that the
4695 <prgn>postrm</prgn> cannot rely on any non-essential
4696 packages to be present during the <tt>purge</tt>
4700 <tag><tt>Recommends</tt></tag>
4703 This declares a strong, but not absolute, dependency.
4707 The <tt>Recommends</tt> field should list packages
4708 that would be found together with this one in all but
4709 unusual installations.
4713 <tag><tt>Suggests</tt></tag>
4715 This is used to declare that one package may be more
4716 useful with one or more others. Using this field
4717 tells the packaging system and the user that the
4718 listed packages are related to this one and can
4719 perhaps enhance its usefulness, but that installing
4720 this one without them is perfectly reasonable.
4723 <tag><tt>Enhances</tt></tag>
4725 This field is similar to Suggests but works in the
4726 opposite direction. It is used to declare that a
4727 package can enhance the functionality of another
4731 <tag><tt>Pre-Depends</tt></tag>
4734 This field is like <tt>Depends</tt>, except that it
4735 also forces <prgn>dpkg</prgn> to complete installation
4736 of the packages named before even starting the
4737 installation of the package which declares the
4738 pre-dependency, as follows:
4742 When a package declaring a pre-dependency is about to
4743 be <em>unpacked</em> the pre-dependency can be
4744 satisfied if the depended-on package is either fully
4745 configured, <em>or even if</em> the depended-on
4746 package(s) are only unpacked or in the "Half-Configured"
4747 state, provided that they have been configured
4748 correctly at some point in the past (and not removed
4749 or partially removed since). In this case, both the
4750 previously-configured and currently unpacked or
4751 "Half-Configured" versions must satisfy any version
4752 clause in the <tt>Pre-Depends</tt> field.
4756 When the package declaring a pre-dependency is about
4757 to be <em>configured</em>, the pre-dependency will be
4758 treated as a normal <tt>Depends</tt>, that is, it will
4759 be considered satisfied only if the depended-on
4760 package has been correctly configured.
4764 <tt>Pre-Depends</tt> should be used sparingly,
4765 preferably only by packages whose premature upgrade or
4766 installation would hamper the ability of the system to
4767 continue with any upgrade that might be in progress.
4771 <tt>Pre-Depends</tt> are also required if the
4772 <prgn>preinst</prgn> script depends on the named
4773 package. It is best to avoid this situation if
4781 When selecting which level of dependency to use you should
4782 consider how important the depended-on package is to the
4783 functionality of the one declaring the dependency. Some
4784 packages are composed of components of varying degrees of
4785 importance. Such a package should list using
4786 <tt>Depends</tt> the package(s) which are required by the
4787 more important components. The other components'
4788 requirements may be mentioned as Suggestions or
4789 Recommendations, as appropriate to the components' relative
4795 <heading>Packages which break other packages - <tt>Breaks</tt></heading>
4798 When one binary package declares that it breaks another,
4799 <prgn>dpkg</prgn> will refuse to allow the package which
4800 declares <tt>Breaks</tt> be installed unless the broken
4801 package is deconfigured first, and it will refuse to
4802 allow the broken package to be reconfigured.
4806 A package will not be regarded as causing breakage merely
4807 because its configuration files are still installed; it must
4808 be at least "Half-Installed".
4812 A special exception is made for packages which declare that
4813 they break their own package name or a virtual package which
4814 they provide (see below): this does not count as a real
4819 Normally a <tt>Breaks</tt> entry will have an "earlier than"
4820 version clause; such a <tt>Breaks</tt> is introduced in the
4821 version of an (implicit or explicit) dependency which violates
4822 an assumption or reveals a bug in earlier versions of the broken
4823 package, or which takes over a file from earlier versions of the
4824 package named in <tt>Breaks</tt>. This use of <tt>Breaks</tt>
4825 will inform higher-level package management tools that the
4826 broken package must be upgraded before the new one.
4830 If the breaking package also overwrites some files from the
4831 older package, it should use <tt>Replaces</tt> to ensure this
4832 goes smoothly. See <ref id="replaces"> for a full discussion
4833 of taking over files from other packages, including how to
4834 use <tt>Breaks</tt> in those cases.
4838 Many of the cases where <tt>Breaks</tt> should be used were
4839 previously handled with <tt>Conflicts</tt>
4840 because <tt>Breaks</tt> did not yet exist.
4841 Many <tt>Conflicts</tt> fields should now be <tt>Breaks</tt>.
4842 See <ref id="conflicts"> for more information about the
4847 <sect id="conflicts">
4848 <heading>Conflicting binary packages - <tt>Conflicts</tt></heading>
4851 When one binary package declares a conflict with another
4852 using a <tt>Conflicts</tt> field, <prgn>dpkg</prgn> will
4853 refuse to allow them to be installed on the system at the
4854 same time. This is a stronger restriction than <tt>Breaks</tt>,
4855 which just prevents both packages from being configured at the
4856 same time. Conflicting packages cannot be unpacked on the
4857 system at the same time.
4861 If one package is to be installed, the other must be removed
4862 first. If the package being installed is marked as replacing
4863 (see <ref id="replaces">, but note that <tt>Breaks</tt> should
4864 normally be used in this case) the one on the system, or the one
4865 on the system is marked as deselected, or both packages are
4866 marked <tt>Essential</tt>, then <prgn>dpkg</prgn> will
4867 automatically remove the package which is causing the conflict.
4868 Otherwise, it will halt the installation of the new package with
4869 an error. This mechanism is specifically designed to produce an
4870 error when the installed package is <tt>Essential</tt>, but the
4875 A package will not cause a conflict merely because its
4876 configuration files are still installed; it must be at least
4881 A special exception is made for packages which declare a
4882 conflict with their own package name, or with a virtual
4883 package which they provide (see below): this does not
4884 prevent their installation, and allows a package to conflict
4885 with others providing a replacement for it. You use this
4886 feature when you want the package in question to be the only
4887 package providing some feature.
4891 Normally, <tt>Breaks</tt> should be used instead
4892 of <tt>Conflicts</tt> since <tt>Conflicts</tt> imposes a
4893 stronger restriction on the ordering of package installation or
4894 upgrade and can make it more difficult for the package manager
4895 to find a correct solution to an upgrade or installation
4896 problem. <tt>Breaks</tt> should be used
4898 <item>when moving a file from one package to another (see
4899 <ref id="replaces">),</item>
4900 <item>when splitting a package (a special case of the previous
4902 <item>when the breaking package exposes a bug in or interacts
4903 badly with particular versions of the broken
4906 <tt>Conflicts</tt> should be used
4908 <item>when two packages provide the same file and will
4909 continue to do so,</item>
4910 <item>in conjunction with <tt>Provides</tt> when only one
4911 package providing a given virtual facility may be installed
4912 at a time (see <ref id="virtual">),</item>
4913 <item>in other cases where one must prevent simultaneous
4914 installation of two packages for reasons that are ongoing
4915 (not fixed in a later version of one of the packages) or
4916 that must prevent both packages from being unpacked at the
4917 same time, not just configured.</item>
4919 Be aware that adding <tt>Conflicts</tt> is normally not the best
4920 solution when two packages provide the same files. Depending on
4921 the reason for that conflict, using alternatives or renaming the
4922 files is often a better approach. See, for
4923 example, <ref id="binaries">.
4927 Neither <tt>Breaks</tt> nor <tt>Conflicts</tt> should be used
4928 unless two packages cannot be installed at the same time or
4929 installing them both causes one of them to be broken or
4930 unusable. Having similar functionality or performing the same
4931 tasks as another package is not sufficient reason to
4932 declare <tt>Breaks</tt> or <tt>Conflicts</tt> with that package.
4936 A <tt>Conflicts</tt> entry may have an "earlier than" version
4937 clause if the reason for the conflict is corrected in a later
4938 version of one of the packages. However, normally the presence
4939 of an "earlier than" version clause is a sign
4940 that <tt>Breaks</tt> should have been used instead. An "earlier
4941 than" version clause in <tt>Conflicts</tt>
4942 prevents <prgn>dpkg</prgn> from upgrading or installing the
4943 package which declares such a conflict until the upgrade or
4944 removal of the conflicted-with package has been completed, which
4945 is a strong restriction.
4949 <sect id="virtual"><heading>Virtual packages - <tt>Provides</tt>
4953 As well as the names of actual ("concrete") packages, the
4954 package relationship fields <tt>Depends</tt>,
4955 <tt>Recommends</tt>, <tt>Suggests</tt>, <tt>Enhances</tt>,
4956 <tt>Pre-Depends</tt>, <tt>Breaks</tt>, <tt>Conflicts</tt>,
4957 <tt>Build-Depends</tt>, <tt>Build-Depends-Indep</tt>,
4958 <tt>Build-Conflicts</tt> and <tt>Build-Conflicts-Indep</tt>
4959 may mention "virtual packages".
4963 A <em>virtual package</em> is one which appears in the
4964 <tt>Provides</tt> control field of another package. The effect
4965 is as if the package(s) which provide a particular virtual
4966 package name had been listed by name everywhere the virtual
4967 package name appears. (See also <ref id="virtual_pkg">)
4971 If there are both concrete and virtual packages of the same
4972 name, then the dependency may be satisfied (or the conflict
4973 caused) by either the concrete package with the name in
4974 question or any other concrete package which provides the
4975 virtual package with the name in question. This is so that,
4976 for example, supposing we have
4977 <example compact="compact">
4980 </example> and someone else releases an enhanced version of
4981 the <tt>bar</tt> package they can say:
4982 <example compact="compact">
4986 and the <tt>bar-plus</tt> package will now also satisfy the
4987 dependency for the <tt>foo</tt> package.
4991 If a relationship field has a version number attached, only real
4992 packages will be considered to see whether the relationship is
4993 satisfied (or the prohibition violated, for a conflict or
4994 breakage). In other words, if a version number is specified,
4995 this is a request to ignore all <tt>Provides</tt> for that
4996 package name and consider only real packages. The package
4997 manager will assume that a package providing that virtual
4998 package is not of the "right" version. A <tt>Provides</tt>
4999 field may not contain version numbers, and the version number of
5000 the concrete package which provides a particular virtual package
5001 will not be considered when considering a dependency on or
5002 conflict with the virtual package name.<footnote>
5003 It is possible that a future release of <prgn>dpkg</prgn> may
5004 add the ability to specify a version number for each virtual
5005 package it provides. This feature is not yet present,
5006 however, and is expected to be used only infrequently.
5011 To specify which of a set of real packages should be the default
5012 to satisfy a particular dependency on a virtual package, list
5013 the real package as an alternative before the virtual one.
5017 If the virtual package represents a facility that can only be
5018 provided by one real package at a time, such as
5019 the <package>mail-transport-agent</package> virtual package that
5020 requires installation of a binary that would conflict with all
5021 other providers of that virtual package (see
5022 <ref id="mail-transport-agents">), all packages providing that
5023 virtual package should also declare a conflict with it
5024 using <tt>Conflicts</tt>. This will ensure that at most one
5025 provider of that virtual package is unpacked or installed at a
5030 <sect id="replaces"><heading>Overwriting files and replacing
5031 packages - <tt>Replaces</tt></heading>
5034 Packages can declare in their control file that they should
5035 overwrite files in certain other packages, or completely replace
5036 other packages. The <tt>Replaces</tt> control field has these
5037 two distinct purposes.
5040 <sect1><heading>Overwriting files in other packages</heading>
5043 It is usually an error for a package to contain files which
5044 are on the system in another package. However, if the
5045 overwriting package declares that it <tt>Replaces</tt> the one
5046 containing the file being overwritten, then <prgn>dpkg</prgn>
5047 will replace the file from the old package with that from the
5048 new. The file will no longer be listed as "owned" by the old
5049 package and will be taken over by the new package.
5050 Normally, <tt>Breaks</tt> should be used in conjunction
5051 with <tt>Replaces</tt>.<footnote>
5052 To see why <tt>Breaks</tt> is normally needed in addition
5053 to <tt>Replaces</tt>, consider the case of a file in the
5054 package <package>foo</package> being taken over by the
5055 package <package>foo-data</package>.
5056 <tt>Replaces</tt> will allow <package>foo-data</package> to
5057 be installed and take over that file. However,
5058 without <tt>Breaks</tt>, nothing
5059 requires <package>foo</package> to be upgraded to a newer
5060 version that knows it does not include that file and instead
5061 depends on <package>foo-data</package>. Nothing would
5062 prevent the new <package>foo-data</package> package from
5063 being installed and then removed, removing the file that it
5064 took over from <package>foo</package>. After that
5065 operation, the package manager would think the system was in
5066 a consistent state, but the <package>foo</package> package
5067 would be missing one of its files.
5072 For example, if a package <package>foo</package> is split
5073 into <package>foo</package> and <package>foo-data</package>
5074 starting at version 1.2-3, <package>foo-data</package> would
5076 <example compact="compact">
5077 Replaces: foo (<< 1.2-3)
5078 Breaks: foo (<< 1.2-3)
5080 in its control file. The new version of the
5081 package <package>foo</package> would normally have the field
5082 <example compact="compact">
5083 Depends: foo-data (>= 1.2-3)
5085 (or possibly <tt>Recommends</tt> or even <tt>Suggests</tt> if
5086 the files moved into <package>foo-data</package> are not
5087 required for normal operation).
5091 If a package is completely replaced in this way, so that
5092 <prgn>dpkg</prgn> does not know of any files it still
5093 contains, it is considered to have "disappeared". It will
5094 be marked as not wanted on the system (selected for
5095 removal) and not installed. Any <tt>conffile</tt>s
5096 details noted for the package will be ignored, as they
5097 will have been taken over by the overwriting package. The
5098 package's <prgn>postrm</prgn> script will be run with a
5099 special argument to allow the package to do any final
5100 cleanup required. See <ref id="mscriptsinstact">.
5102 Replaces is a one way relationship. You have to install
5103 the replacing package after the replaced package.
5108 For this usage of <tt>Replaces</tt>, virtual packages (see
5109 <ref id="virtual">) are not considered when looking at a
5110 <tt>Replaces</tt> field. The packages declared as being
5111 replaced must be mentioned by their real names.
5115 This usage of <tt>Replaces</tt> only takes effect when both
5116 packages are at least partially on the system at once. It is
5117 not relevant if the packages conflict unless the conflict has
5122 <sect1><heading>Replacing whole packages, forcing their
5126 Second, <tt>Replaces</tt> allows the packaging system to
5127 resolve which package should be removed when there is a
5128 conflict (see <ref id="conflicts">). This usage only takes
5129 effect when the two packages <em>do</em> conflict, so that the
5130 two usages of this field do not interfere with each other.
5134 In this situation, the package declared as being replaced
5135 can be a virtual package, so for example, all mail
5136 transport agents (MTAs) would have the following fields in
5137 their control files:
5138 <example compact="compact">
5139 Provides: mail-transport-agent
5140 Conflicts: mail-transport-agent
5141 Replaces: mail-transport-agent
5143 ensuring that only one MTA can be installed at any one
5144 time. See <ref id="virtual"> for more information about this
5149 <sect id="sourcebinarydeps">
5150 <heading>Relationships between source and binary packages -
5151 <tt>Build-Depends</tt>, <tt>Build-Depends-Indep</tt>,
5152 <tt>Build-Conflicts</tt>, <tt>Build-Conflicts-Indep</tt>
5156 Source packages that require certain binary packages to be
5157 installed or absent at the time of building the package
5158 can declare relationships to those binary packages.
5162 This is done using the <tt>Build-Depends</tt>,
5163 <tt>Build-Depends-Indep</tt>, <tt>Build-Conflicts</tt> and
5164 <tt>Build-Conflicts-Indep</tt> control fields.
5168 Build-dependencies on "build-essential" binary packages can be
5169 omitted. Please see <ref id="pkg-relations"> for more information.
5173 The dependencies and conflicts they define must be satisfied
5174 (as defined earlier for binary packages) in order to invoke
5175 the targets in <tt>debian/rules</tt>, as follows:<footnote>
5177 There is no Build-Depends-Arch; this role is essentially
5178 met with Build-Depends. Anyone building the
5179 <tt>build-indep</tt> and <tt>binary-indep</tt> targets is
5180 assumed to be building the whole package, and therefore
5181 installation of all build dependencies is required.
5184 The autobuilders use <tt>dpkg-buildpackage -B</tt>, which
5185 calls <tt>build</tt>, not <tt>build-arch</tt> since it does
5186 not yet know how to check for its existence, and
5187 <tt>binary-arch</tt>. The purpose of the original split
5188 between <tt>Build-Depends</tt> and
5189 <tt>Build-Depends-Indep</tt> was so that the autobuilders
5190 wouldn't need to install extra packages needed only for the
5191 binary-indep targets. But without a build-arch/build-indep
5192 split, this didn't work, since most of the work is done in
5193 the build target, not in the binary target.
5197 <tag><tt>clean</tt>, <tt>build-arch</tt>, and
5198 <tt>binary-arch</tt></tag>
5200 Only the <tt>Build-Depends</tt> and <tt>Build-Conflicts</tt>
5201 fields must be satisfied when these targets are invoked.
5203 <tag><tt>build</tt>, <tt>build-indep</tt>, <tt>binary</tt>,
5204 and <tt>binary-indep</tt></tag>
5206 The <tt>Build-Depends</tt>, <tt>Build-Conflicts</tt>,
5207 <tt>Build-Depends-Indep</tt>, and
5208 <tt>Build-Conflicts-Indep</tt> fields must be satisfied when
5209 these targets are invoked.
5217 <chapt id="sharedlibs"><heading>Shared libraries</heading>
5220 Packages containing shared libraries must be constructed with
5221 a little care to make sure that the shared library is always
5222 available. This is especially important for packages whose
5223 shared libraries are vitally important, such as the C library
5224 (currently <tt>libc6</tt>).
5228 This section deals only with public shared libraries: shared
5229 libraries that are placed in directories searched by the dynamic
5230 linker by default or which are intended to be linked against
5231 normally and possibly used by other, independent packages. Shared
5232 libraries that are internal to a particular package or that are
5233 only loaded as dynamic modules are not covered by this section and
5234 are not subject to its requirements.
5238 A shared library is identified by the <tt>SONAME</tt> attribute
5239 stored in its dynamic section. When a binary is linked against a
5240 shared library, the <tt>SONAME</tt> of the shared library is
5241 recorded in the binary's <tt>NEEDED</tt> section so that the
5242 dynamic linker knows that library must be loaded at runtime. The
5243 shared library file's full name (which usually contains additional
5244 version information not needed in the <tt>SONAME</tt>) is
5245 therefore normally not referenced directly. Instead, the shared
5246 library is loaded by its <tt>SONAME</tt>, which exists on the file
5247 system as a symlink pointing to the full name of the shared
5248 library. This symlink must be provided by the
5249 package. <ref id="sharedlibs-runtime"> describes how to do this.
5251 This is a convention of shared library versioning, but not a
5252 requirement. Some libraries use the <tt>SONAME</tt> as the full
5253 library file name instead and therefore do not need a symlink.
5254 Most, however, encode additional information about
5255 backwards-compatible revisions as a minor version number in the
5256 file name. The <tt>SONAME</tt> itself only changes when
5257 binaries linked with the earlier version of the shared library
5258 may no longer work, but the filename may change with each
5259 release of the library. See <ref id="sharedlibs-runtime"> for
5265 When linking a binary or another shared library against a shared
5266 library, the <tt>SONAME</tt> for that shared library is not yet
5267 known. Instead, the shared library is found by looking for a file
5268 matching the library name with <tt>.so</tt> appended. This file
5269 exists on the file system as a symlink pointing to the shared
5274 Shared libraries are normally split into several binary packages.
5275 The <tt>SONAME</tt> symlink is installed by the runtime shared
5276 library package, and the bare <tt>.so</tt> symlink is installed in
5277 the development package since it's only used when linking binaries
5278 or shared libraries. However, there are some exceptions for
5279 unusual shared libraries or for shared libraries that are also
5280 loaded as dynamic modules by other programs.
5284 This section is primarily concerned with how the separation of
5285 shared libraries into multiple packages should be done and how
5286 dependencies on and between shared library binary packages are
5287 managed in Debian. <ref id="libraries"> should be read in
5288 conjunction with this section and contains additional rules for
5289 the files contained in the shared library packages.
5292 <sect id="sharedlibs-runtime">
5293 <heading>Run-time shared libraries</heading>
5296 The run-time shared library must be placed in a package
5297 whose name changes whenever the <tt>SONAME</tt> of the shared
5298 library changes. This allows several versions of the shared
5299 library to be installed at the same time, allowing installation
5300 of the new version of the shared library without immediately
5301 breaking binaries that depend on the old version. Normally, the
5302 run-time shared library and its <tt>SONAME</tt> symlink should
5303 be placed in a package named
5304 <package><var>libraryname</var><var>soversion</var></package>,
5305 where <var>soversion</var> is the version number in
5306 the <tt>SONAME</tt> of the shared library.
5307 See <ref id="shlibs"> for detailed information on how to
5308 determine this version. Alternatively, if it would be confusing
5309 to directly append <var>soversion</var>
5310 to <var>libraryname</var> (if, for example, <var>libraryname</var>
5311 itself ends in a number), you should use
5312 <package><var>libraryname</var>-<var>soversion</var></package>
5317 If you have several shared libraries built from the same source
5318 tree, you may lump them all together into a single shared
5319 library package provided that all of their <tt>SONAME</tt>s will
5320 always change together. Be aware that this is not normally the
5321 case, and if the <tt>SONAME</tt>s do not change together,
5322 upgrading such a merged shared library package will be
5323 unnecessarily difficult because of file conflicts with the old
5324 version of the package. When in doubt, always split shared
5325 library packages so that each binary package installs a single
5330 Every time the shared library ABI changes in a way that may
5331 break binaries linked against older versions of the shared
5332 library, the <tt>SONAME</tt> of the library and the
5333 corresponding name for the binary package containing the runtime
5334 shared library should change. Normally, this means
5335 the <tt>SONAME</tt> should change any time an interface is
5336 removed from the shared library or the signature of an interface
5337 (the number of parameters or the types of parameters that it
5338 takes, for example) is changed. This practice is vital to
5339 allowing clean upgrades from older versions of the package and
5340 clean transitions between the old ABI and new ABI without having
5341 to upgrade every affected package simultaneously.
5345 The <tt>SONAME</tt> and binary package name need not, and indeed
5346 normally should not, change if new interfaces are added but none
5347 are removed or changed, since this will not break binaries
5348 linked against the old shared library. Correct versioning of
5349 dependencies on the newer shared library by binaries that use
5350 the new interfaces is handled via
5351 the <qref id="sharedlibs-shlibdeps"><tt>shlibs</tt>
5352 system</qref> or via symbols files (see
5353 <manref name="deb-symbols" section="5">).
5357 The package should install the shared libraries under
5358 their normal names. For example, the <package>libgdbm3</package>
5359 package should install <file>libgdbm.so.3.0.0</file> as
5360 <file>/usr/lib/libgdbm.so.3.0.0</file>. The files should not be
5361 renamed or re-linked by any <prgn>prerm</prgn> or
5362 <prgn>postrm</prgn> scripts; <prgn>dpkg</prgn> will take care
5363 of renaming things safely without affecting running programs,
5364 and attempts to interfere with this are likely to lead to
5369 Shared libraries should not be installed executable, since
5370 the dynamic linker does not require this and trying to
5371 execute a shared library usually results in a core dump.
5375 The run-time library package should include the symbolic link for
5376 the <tt>SONAME</tt> that <prgn>ldconfig</prgn> would create for
5377 the shared libraries. For example,
5378 the <package>libgdbm3</package> package should include a symbolic
5379 link from <file>/usr/lib/libgdbm.so.3</file> to
5380 <file>libgdbm.so.3.0.0</file>. This is needed so that the dynamic
5381 linker (for example <prgn>ld.so</prgn> or
5382 <prgn>ld-linux.so.*</prgn>) can find the library between the
5383 time that <prgn>dpkg</prgn> installs it and the time that
5384 <prgn>ldconfig</prgn> is run in the <prgn>postinst</prgn>
5386 The package management system requires the library to be
5387 placed before the symbolic link pointing to it in the
5388 <file>.deb</file> file. This is so that when
5389 <prgn>dpkg</prgn> comes to install the symlink
5390 (overwriting the previous symlink pointing at an older
5391 version of the library), the new shared library is already
5392 in place. In the past, this was achieved by creating the
5393 library in the temporary packaging directory before
5394 creating the symlink. Unfortunately, this was not always
5395 effective, since the building of the tar file in the
5396 <file>.deb</file> depended on the behavior of the underlying
5397 file system. Some file systems (such as reiserfs) reorder
5398 the files so that the order of creation is forgotten.
5399 Since version 1.7.0, <prgn>dpkg</prgn>
5400 reorders the files itself as necessary when building a
5401 package. Thus it is no longer important to concern
5402 oneself with the order of file creation.
5406 <sect1 id="ldconfig">
5407 <heading><tt>ldconfig</tt></heading>
5410 Any package installing shared libraries in one of the default
5411 library directories of the dynamic linker (which are currently
5412 <file>/usr/lib</file> and <file>/lib</file>) or a directory that is
5413 listed in <file>/etc/ld.so.conf</file><footnote>
5414 These are currently <file>/usr/local/lib</file> plus
5415 directories under <file>/lib</file> and <file>/usr/lib</file>
5416 matching the multiarch triplet for the system architecture.
5418 must use <prgn>ldconfig</prgn> to update the shared library
5423 The package maintainer scripts must only call
5424 <prgn>ldconfig</prgn> under these circumstances:
5425 <list compact="compact">
5426 <item>When the <prgn>postinst</prgn> script is run with a
5427 first argument of <tt>configure</tt>, the script must call
5428 <prgn>ldconfig</prgn>, and may optionally invoke
5429 <prgn>ldconfig</prgn> at other times.
5431 <item>When the <prgn>postrm</prgn> script is run with a
5432 first argument of <tt>remove</tt>, the script should call
5433 <prgn>ldconfig</prgn>.
5438 During install or upgrade, the preinst is called before
5439 the new files are installed, so calling "ldconfig" is
5440 pointless. The preinst of an existing package can also be
5441 called if an upgrade fails. However, this happens during
5442 the critical time when a shared libs may exist on-disk
5443 under a temporary name. Thus, it is dangerous and
5444 forbidden by current policy to call "ldconfig" at this
5449 When a package is installed or upgraded, "postinst
5450 configure" runs after the new files are safely on-disk.
5451 Since it is perfectly safe to invoke ldconfig
5452 unconditionally in a postinst, it is OK for a package to
5453 simply put ldconfig in its postinst without checking the
5454 argument. The postinst can also be called to recover from
5455 a failed upgrade. This happens before any new files are
5456 unpacked, so there is no reason to call "ldconfig" at this
5461 For a package that is being removed, prerm is
5462 called with all the files intact, so calling ldconfig is
5463 useless. The other calls to "prerm" happen in the case of
5464 upgrade at a time when all the files of the old package
5465 are on-disk, so again calling "ldconfig" is pointless.
5469 postrm, on the other hand, is called with the "remove"
5470 argument just after the files are removed, so this is
5471 the proper time to call "ldconfig" to notify the system
5472 of the fact that the shared libraries from the package
5473 are removed. The postrm can be called at several other
5474 times. At the time of "postrm purge", "postrm
5475 abort-install", or "postrm abort-upgrade", calling
5476 "ldconfig" is useless because the shared lib files are
5477 not on-disk. However, when "postrm" is invoked with
5478 arguments "upgrade", "failed-upgrade", or "disappear", a
5479 shared lib may exist on-disk under a temporary filename.
5487 <sect id="sharedlibs-support-files">
5488 <heading>Shared library support files</heading>
5491 If your package contains files whose names do not change with
5492 each change in the library shared object version, you must not
5493 put them in the shared library package. Otherwise, several
5494 versions of the shared library cannot be installed at the same
5495 time without filename clashes, making upgrades and transitions
5496 unnecessarily difficult.
5500 It is recommended that supporting files and run-time support
5501 programs that do not need to be invoked manually by users, but
5502 are nevertheless required for the package to function, be placed
5503 (if they are binary) in a subdirectory of <file>/usr/lib</file>,
5504 preferably under <file>/usr/lib/</file><var>package-name</var>.
5505 If the program or file is architecture independent, the
5506 recommendation is for it to be placed in a subdirectory of
5507 <file>/usr/share</file> instead, preferably under
5508 <file>/usr/share/</file><var>package-name</var>. Following the
5509 <var>package-name</var> naming convention ensures that the file
5510 names change when the shared object version changes.
5514 Run-time support programs that use the shared library but are
5515 not required for the library to function or files used by the
5516 shared library that can be used by any version of the shared
5517 library package should instead be put in a separate package.
5518 This package might typically be named
5519 <package><var>libraryname</var>-tools</package>; note the
5520 absence of the <var>soversion</var> in the package name.
5524 Files and support programs only useful when compiling software
5525 against the library should be included in the development
5526 package for the library.<footnote>
5527 For example, a <file><var>package-name</var>-config</file>
5528 script or <package>pkg-config</package> configuration files.
5533 <sect id="sharedlibs-static">
5534 <heading>Static libraries</heading>
5537 The static library (<file><var>libraryname.a</var></file>)
5538 is usually provided in addition to the shared version.
5539 It is placed into the development package (see below).
5543 In some cases, it is acceptable for a library to be
5544 available in static form only; these cases include:
5546 <item>libraries for languages whose shared library support
5547 is immature or unstable</item>
5548 <item>libraries whose interfaces are in flux or under
5549 development (commonly the case when the library's
5550 major version number is zero, or where the ABI breaks
5551 across patchlevels)</item>
5552 <item>libraries which are explicitly intended to be
5553 available only in static form by their upstream
5558 <sect id="sharedlibs-dev">
5559 <heading>Development files</heading>
5562 If there are development files associated with a shared library,
5563 the source package needs to generate a binary development package
5564 named <package><var>libraryname</var><var>soversion</var>-dev</package>,
5565 or if you prefer only to support one development version at a
5566 time, <package><var>libraryname</var>-dev</package>. Installing
5567 the development package must result in installation of all the
5568 development files necessary for compiling programs against that
5569 shared library.<footnote>
5570 This wording allows the development files to be split into
5571 several packages, such as a separate architecture-independent
5572 <package><var>libraryname</var>-headers</package>, provided that
5573 the development package depends on all the required additional
5579 In case several development versions of a library exist, you may
5580 need to use <prgn>dpkg</prgn>'s Conflicts mechanism (see
5581 <ref id="conflicts">) to ensure that the user only installs one
5582 development version at a time (as different development versions are
5583 likely to have the same header files in them, which would cause a
5584 filename clash if both were installed).
5588 The development package should contain a symlink for the associated
5589 shared library without a version number. For example, the
5590 <package>libgdbm-dev</package> package should include a symlink
5591 from <file>/usr/lib/libgdbm.so</file> to
5592 <file>libgdbm.so.3.0.0</file>. This symlink is needed by the linker
5593 (<prgn>ld</prgn>) when compiling packages, as it will only look for
5594 <file>libgdbm.so</file> when compiling dynamically.
5598 If the package provides Ada Library Information
5599 (<file>*.ali</file>) files for use with GNAT, these files must be
5600 installed read-only (mode 0444) so that GNAT will not attempt to
5601 recompile them. This overrides the normal file mode requirements
5602 given in <ref id="permissions-owners">.
5606 <sect id="sharedlibs-intradeps">
5607 <heading>Dependencies between the packages of the same library</heading>
5610 Typically the development version should have an exact
5611 version dependency on the runtime library, to make sure that
5612 compilation and linking happens correctly. The
5613 <tt>${binary:Version}</tt> substitution variable can be
5614 useful for this purpose.
5616 Previously, <tt>${Source-Version}</tt> was used, but its name
5617 was confusing and it has been deprecated since dpkg 1.13.19.
5622 <sect id="sharedlibs-shlibdeps">
5623 <heading>Dependencies between the library and other packages -
5624 the <tt>shlibs</tt> system</heading>
5627 If a package contains a binary or library which links to a
5628 shared library, we must ensure that when the package is
5629 installed on the system, all of the libraries needed are
5630 also installed. This requirement led to the creation of the
5631 <tt>shlibs</tt> system, which is very simple in its design:
5632 any package which <em>provides</em> a shared library also
5633 provides information on the package dependencies required to
5634 ensure the presence of this library, and any package which
5635 <em>uses</em> a shared library uses this information to
5636 determine the dependencies it requires. The files which
5637 contain the mapping from shared libraries to the necessary
5638 dependency information are called <file>shlibs</file> files.
5642 When a package is built which contains any shared libraries, it
5643 must provide a <file>shlibs</file> file for other packages to
5644 use. When a package is built which contains any shared
5645 libraries or compiled binaries, it must run
5646 <qref id="pkg-dpkg-shlibdeps"><prgn>dpkg-shlibdeps</prgn></qref>
5647 on these to determine the libraries used and hence the
5648 dependencies needed by this package.<footnote>
5650 <prgn>dpkg-shlibdeps</prgn> will use a program
5651 like <prgn>objdump</prgn> or <prgn>readelf</prgn> to find
5652 the libraries directly needed by the binaries or shared
5653 libraries in the package.
5657 We say that a binary <tt>foo</tt> <em>directly</em> uses
5658 a library <tt>libbar</tt> if it is explicitly linked
5659 with that library (that is, the library is listed in the ELF
5660 <tt>NEEDED</tt> attribute, caused by adding <tt>-lbar</tt>
5661 to the link line when the binary is created). Other
5662 libraries that are needed by <tt>libbar</tt> are linked
5663 <em>indirectly</em> to <tt>foo</tt>, and the dynamic
5664 linker will load them automatically when it loads
5665 <tt>libbar</tt>. A package should depend on the libraries
5666 it directly uses, but not the libraries it indirectly uses.
5667 The dependencies for those libraries will automatically pull
5668 in the other libraries.
5672 A good example of where this helps is the following. We
5673 could update <tt>libimlib</tt> with a new version that
5674 supports a new graphics format called dgf (but retaining the
5675 same major version number) and depends on <tt>libdgf</tt>.
5676 If we used <prgn>ldd</prgn> to add dependencies for every
5677 library directly or indirectly linked with a binary, every
5678 package that uses <tt>libimlib</tt> would need to be
5679 recompiled so it would also depend on <tt>libdgf</tt> or it
5680 wouldn't run due to missing symbols. Since dependencies are
5681 only added based on ELF <tt>NEEDED</tt> attribute, packages
5682 using <tt>libimlib</tt> can rely on <tt>libimlib</tt> itself
5683 having the dependency on <tt>libdgf</tt> and so they would
5684 not need rebuilding.
5690 In the following sections, we will first describe where the
5691 various <tt>shlibs</tt> files are to be found, then how to
5692 use <prgn>dpkg-shlibdeps</prgn>, and finally the <tt>shlibs</tt>
5693 file format and how to create them if your package contains a
5698 <heading>The <tt>shlibs</tt> files present on the system</heading>
5701 There are several places where <tt>shlibs</tt> files are
5702 found. The following list gives them in the order in which
5704 <qref id="pkg-dpkg-shlibdeps"><prgn>dpkg-shlibdeps</prgn></qref>.
5705 (The first one which gives the required information is used.)
5711 <p><file>debian/shlibs.local</file></p>
5714 This lists overrides for this package. This file should
5715 normally not be used, but may be needed temporarily in
5716 unusual situations to work around bugs in other packages,
5717 or in unusual cases where the normally declared dependency
5718 information in the installed <file>shlibs</file> file for
5719 a library cannot be used. This file overrides information
5720 obtained from any other source.
5725 <p><file>/etc/dpkg/shlibs.override</file></p>
5728 This lists global overrides. This list is normally
5729 empty. It is maintained by the local system
5735 <p><file>DEBIAN/shlibs</file> files in the "build directory"</p>
5738 When packages are being built,
5739 any <file>debian/shlibs</file> files are copied into the
5740 control information file area of the temporary build
5741 directory and given the name <file>shlibs</file>. These
5742 files give details of any shared libraries included in the
5743 same package.<footnote>
5744 An example may help here. Let us say that the source
5745 package <tt>foo</tt> generates two binary
5746 packages, <tt>libfoo2</tt> and <tt>foo-runtime</tt>.
5747 When building the binary packages, the two packages are
5748 created in the directories <file>debian/libfoo2</file>
5749 and <file>debian/foo-runtime</file> respectively.
5750 (<file>debian/tmp</file> could be used instead of one of
5751 these.) Since <tt>libfoo2</tt> provides the
5752 <tt>libfoo</tt> shared library, it will require a
5753 <tt>shlibs</tt> file, which will be installed in
5754 <file>debian/libfoo2/DEBIAN/shlibs</file>, eventually to
5755 become <file>/var/lib/dpkg/info/libfoo2.shlibs</file>.
5756 When <prgn>dpkg-shlibdeps</prgn> is run on the
5757 executable <file>debian/foo-runtime/usr/bin/foo-prog</file>,
5759 the <file>debian/libfoo2/DEBIAN/shlibs</file> file to
5760 determine whether <tt>foo-prog</tt>'s library
5761 dependencies are satisfied by any of the libraries
5762 provided by <tt>libfoo2</tt>. For this reason,
5763 <prgn>dpkg-shlibdeps</prgn> must only be run once all of
5764 the individual binary packages' <tt>shlibs</tt> files
5765 have been installed into the build directory.
5771 <p><file>/var/lib/dpkg/info/*.shlibs</file></p>
5774 These are the <file>shlibs</file> files corresponding to
5775 all of the packages installed on the system, and are
5776 maintained by the relevant package maintainers.
5781 <p><file>/etc/dpkg/shlibs.default</file></p>
5784 This file lists any shared libraries whose packages
5785 have failed to provide correct <file>shlibs</file> files.
5786 It was used when the <file>shlibs</file> setup was first
5787 introduced, but it is now normally empty. It is
5788 maintained by the <tt>dpkg</tt> maintainer.
5796 <heading>How to use <prgn>dpkg-shlibdeps</prgn> and the
5797 <file>shlibs</file> files</heading>
5801 <qref id="pkg-dpkg-shlibdeps"><prgn>dpkg-shlibdeps</prgn></qref>
5802 into your <file>debian/rules</file> file. If your package
5803 contains only compiled binaries and libraries (but no scripts),
5804 you can use a command such as:
5805 <example compact="compact">
5806 dpkg-shlibdeps debian/tmp/usr/bin/* debian/tmp/usr/sbin/* \
5807 debian/tmp/usr/lib/*
5809 Otherwise, you will need to explicitly list the compiled
5810 binaries and libraries.<footnote>
5811 If you are using <tt>debhelper</tt>, the
5812 <prgn>dh_shlibdeps</prgn> program will do this work for you.
5813 It will also correctly handle multi-binary packages.
5818 This command puts the dependency information into the
5819 <file>debian/substvars</file> file, which is then used by
5820 <prgn>dpkg-gencontrol</prgn>. You will need to place a
5821 <tt>${shlibs:Depends}</tt> variable in the <tt>Depends</tt>
5822 field in the control file for this to work.
5826 If you have multiple binary packages, you will need to call
5827 <prgn>dpkg-shlibdeps</prgn> on each one which contains
5828 compiled libraries or binaries. In such a case, you will
5829 need to use the <tt>-T</tt> option to the <tt>dpkg</tt>
5830 utilities to specify a different <file>substvars</file> file.
5834 If you are creating a udeb for use in the Debian Installer,
5835 you will need to specify that <prgn>dpkg-shlibdeps</prgn>
5836 should use the dependency line of type <tt>udeb</tt> by
5837 adding the <tt>-tudeb</tt> option<footnote>
5838 <prgn>dh_shlibdeps</prgn> from the <tt>debhelper</tt> suite
5839 will automatically add this option if it knows it is
5841 </footnote>. If there is no dependency line of
5842 type <tt>udeb</tt> in the <file>shlibs</file>
5843 file, <prgn>dpkg-shlibdeps</prgn> will fall back to the regular
5848 For more details on <prgn>dpkg-shlibdeps</prgn>, please see
5849 <ref id="pkg-dpkg-shlibdeps"> and
5850 <manref name="dpkg-shlibdeps" section="1">.
5855 <heading>The <file>shlibs</file> File Format</heading>
5858 Each <file>shlibs</file> file has the same format. Lines
5859 beginning with <tt>#</tt> are considered to be comments and
5860 are ignored. Each line is of the form:
5861 <example compact="compact">
5862 [<var>type</var>: ]<var>library-name</var> <var>soname-version</var> <var>dependencies ...</var>
5867 We will explain this by reference to the example of the
5868 <tt>zlib1g</tt> package, which (at the time of writing)
5869 installs the shared library <file>/usr/lib/libz.so.1.1.3</file>.
5873 <var>type</var> is an optional element that indicates the type
5874 of package for which the line is valid. The only type currently
5875 in use is <tt>udeb</tt>. The colon and space after the type are
5880 <var>library-name</var> is the name of the shared library,
5881 in this case <tt>libz</tt>. (This must match the name part
5882 of the soname, see below.)
5886 <var>soname-version</var> is the version part of the soname of
5887 the library. The soname is the thing that must exactly match
5888 for the library to be recognized by the dynamic linker, and is
5890 <tt><var>name</var>.so.<var>major-version</var></tt>, in our
5891 example, <tt>libz.so.1</tt>.<footnote>
5892 This can be determined using the command
5893 <example compact="compact">
5894 objdump -p /usr/lib/libz.so.1.1.3 | grep SONAME
5897 The version part is the part which comes after
5898 <tt>.so.</tt>, so in our case, it is <tt>1</tt>. The soname may
5899 instead be of the form
5900 <tt><var>name</var>-<var>major-version</var>.so</tt>, such
5901 as <tt>libdb-4.8.so</tt>, in which case the name would
5902 be <tt>libdb</tt> and the version would be <tt>4.8</tt>.
5906 <var>dependencies</var> has the same syntax as a dependency
5907 field in a binary package control file. It should give
5908 details of which packages are required to satisfy a binary
5909 built against the version of the library contained in the
5910 package. See <ref id="depsyntax"> for details.
5914 In our example, if the first version of the <tt>zlib1g</tt>
5915 package which contained a minor number of at least
5916 <tt>1.3</tt> was <var>1:1.1.3-1</var>, then the
5917 <tt>shlibs</tt> entry for this library could say:
5918 <example compact="compact">
5919 libz 1 zlib1g (>= 1:1.1.3)
5921 The version-specific dependency is to avoid warnings from
5922 the dynamic linker about using older shared libraries with
5927 As zlib1g also provides a udeb containing the shared library,
5928 there would also be a second line:
5929 <example compact="compact">
5930 udeb: libz 1 zlib1g-udeb (>= 1:1.1.3)
5936 <heading>Providing a <file>shlibs</file> file</heading>
5939 If your package provides a shared library, you need to create
5940 a <file>shlibs</file> file following the format described above.
5941 It is usual to call this file <file>debian/shlibs</file> (but if
5942 you have multiple binary packages, you might want to call it
5943 <file>debian/shlibs.<var>package</var></file> instead). Then
5944 let <file>debian/rules</file> install it in the control
5945 information file area:
5946 <example compact="compact">
5947 install -m644 debian/shlibs debian/tmp/DEBIAN
5949 or, in the case of a multi-binary package:
5950 <example compact="compact">
5951 install -m644 debian/shlibs.<var>package</var> debian/<var>package</var>/DEBIAN/shlibs
5953 An alternative way of doing this is to create the
5954 <file>shlibs</file> file in the control information file area
5955 directly from <file>debian/rules</file> without using
5956 a <file>debian/shlibs</file> file at all,<footnote>
5957 This is what <prgn>dh_makeshlibs</prgn> in
5958 the <package>debhelper</package> suite does. If your package
5959 also has a udeb that provides a shared
5960 library, <prgn>dh_makeshlibs</prgn> can automatically generate
5961 the <tt>udeb:</tt> lines if you specify the name of the udeb
5962 with the <tt>--add-udeb</tt> option.
5964 since the <file>debian/shlibs</file> file itself is ignored by
5965 <prgn>dpkg-shlibdeps</prgn>.
5969 As <prgn>dpkg-shlibdeps</prgn> reads the
5970 <file>DEBIAN/shlibs</file> files in all of the binary packages
5971 being built from this source package, all of the
5972 <file>DEBIAN/shlibs</file> files should be installed before
5973 <prgn>dpkg-shlibdeps</prgn> is called on any of the binary
5981 <chapt id="opersys"><heading>The Operating System</heading>
5984 <heading>File system hierarchy</heading>
5988 <heading>File System Structure</heading>
5991 The location of all installed files and directories must
5992 comply with the Filesystem Hierarchy Standard (FHS),
5993 version 2.3, with the exceptions noted below, and except
5994 where doing so would violate other terms of Debian
5995 Policy. The following exceptions to the FHS apply:
6000 The optional rules related to user specific
6001 configuration files for applications are stored in
6002 the user's home directory are relaxed. It is
6003 recommended that such files start with the
6004 '<tt>.</tt>' character (a "dot file"), and if an
6005 application needs to create more than one dot file
6006 then the preferred placement is in a subdirectory
6007 with a name starting with a '.' character, (a "dot
6008 directory"). In this case it is recommended the
6009 configuration files not start with the '.'
6015 The requirement for amd64 to use <file>/lib64</file>
6016 for 64 bit binaries is removed.
6021 The requirement for object files, internal binaries, and
6022 libraries, including <file>libc.so.*</file>, to be located
6023 directly under <file>/lib{,32}</file> and
6024 <file>/usr/lib{,32}</file> is amended, permitting files
6025 to instead be installed to
6026 <file>/lib/<var>triplet</var></file> and
6027 <file>/usr/lib/<var>triplet</var></file>, where
6028 <tt><var>triplet</var></tt> is the value returned by
6029 <tt>dpkg-architecture -qDEB_HOST_GNU_TYPE</tt> for the
6030 architecture of the package. Packages may <em>not</em>
6031 install files to any <var>triplet</var> path other
6032 than the one matching the architecture of that package;
6033 for instance, an <tt>Architecture: amd64</tt> package
6034 containing 32-bit x86 libraries may not install these
6035 libraries to <file>/usr/lib/i486-linux-gnu</file>.
6037 This is necessary in order to reserve the directories for
6038 use in cross-installation of library packages from other
6039 architectures, as part of the planned deployment of
6044 Applications may also use a single subdirectory under
6045 <file>/usr/lib/<var>triplet</var></file>.
6048 The execution time linker/loader, ld*, must still be made
6049 available in the existing location under /lib or /lib64
6050 since this is part of the ELF ABI for the architecture.
6055 The requirement that
6056 <file>/usr/local/share/man</file> be "synonymous"
6057 with <file>/usr/local/man</file> is relaxed to a
6062 The requirement that windowmanagers with a single
6063 configuration file call it <file>system.*wmrc</file>
6064 is removed, as is the restriction that the window
6065 manager subdirectory be named identically to the
6066 window manager name itself.
6071 The requirement that boot manager configuration
6072 files live in <file>/etc</file>, or at least are
6073 symlinked there, is relaxed to a recommendation.
6078 The following directories in the root filesystem are
6079 additionally allowed: <file>/sys</file> and
6080 <file>/selinux</file>. <footnote>These directories
6081 are used as mount points to mount virtual filesystems
6082 to get access to kernel information.</footnote>
6087 On GNU/Hurd systems, the following additional
6088 directories are allowed in the root
6089 filesystem: <file>/hurd</file>
6090 and <file>/servers</file>.<footnote>
6091 These directories are used to store translators and as
6092 a set of standard names for mount points,
6101 The version of this document referred here can be
6102 found in the <tt>debian-policy</tt> package or on <url
6103 id="http://www.debian.org/doc/packaging-manuals/fhs/"
6104 name="FHS (Debian copy)"> alongside this manual (or, if
6105 you have the <package>debian-policy</package> installed,
6107 id="file:///usr/share/doc/debian-policy/fhs/" name="FHS
6108 (local copy)">). The
6109 latest version, which may be a more recent version, may
6111 <url id="http://www.pathname.com/fhs/" name="FHS (upstream)">.
6112 Specific questions about following the standard may be
6113 asked on the <tt>debian-devel</tt> mailing list, or
6114 referred to the FHS mailing list (see the
6115 <url id="http://www.pathname.com/fhs/" name="FHS web site"> for
6121 <heading>Site-specific programs</heading>
6124 As mandated by the FHS, packages must not place any
6125 files in <file>/usr/local</file>, either by putting them in
6126 the file system archive to be unpacked by <prgn>dpkg</prgn>
6127 or by manipulating them in their maintainer scripts.
6131 However, the package may create empty directories below
6132 <file>/usr/local</file> so that the system administrator knows
6133 where to place site-specific files. These are not
6134 directories <em>in</em> <file>/usr/local</file>, but are
6135 children of directories in <file>/usr/local</file>. These
6136 directories (<file>/usr/local/*/dir/</file>)
6137 should be removed on package removal if they are
6142 Note that this applies only to
6143 directories <em>below</em> <file>/usr/local</file>,
6144 not <em>in</em> <file>/usr/local</file>. Packages must
6145 not create sub-directories in the
6146 directory <file>/usr/local</file> itself, except those
6147 listed in FHS, section 4.5. However, you may create
6148 directories below them as you wish. You must not remove
6149 any of the directories listed in 4.5, even if you created
6154 Since <file>/usr/local</file> can be mounted read-only from a
6155 remote server, these directories must be created and
6156 removed by the <prgn>postinst</prgn> and <prgn>prerm</prgn>
6157 maintainer scripts and not be included in the
6158 <file>.deb</file> archive. These scripts must not fail if
6159 either of these operations fail.
6163 For example, the <tt>emacsen-common</tt> package could
6164 contain something like
6165 <example compact="compact">
6166 if [ ! -e /usr/local/share/emacs ]
6168 if mkdir /usr/local/share/emacs 2>/dev/null
6170 chown root:staff /usr/local/share/emacs
6171 chmod 2775 /usr/local/share/emacs
6175 in its <prgn>postinst</prgn> script, and
6176 <example compact="compact">
6177 rmdir /usr/local/share/emacs/site-lisp 2>/dev/null || true
6178 rmdir /usr/local/share/emacs 2>/dev/null || true
6180 in the <prgn>prerm</prgn> script. (Note that this form is
6181 used to ensure that if the script is interrupted, the
6182 directory <file>/usr/local/share/emacs</file> will still be
6187 If you do create a directory in <file>/usr/local</file> for
6188 local additions to a package, you should ensure that
6189 settings in <file>/usr/local</file> take precedence over the
6190 equivalents in <file>/usr</file>.
6194 However, because <file>/usr/local</file> and its contents are
6195 for exclusive use of the local administrator, a package
6196 must not rely on the presence or absence of files or
6197 directories in <file>/usr/local</file> for normal operation.
6201 The <file>/usr/local</file> directory itself and all the
6202 subdirectories created by the package should (by default) have
6203 permissions 2775 (group-writable and set-group-id) and be
6204 owned by <tt>root:staff</tt>.
6209 <heading>The system-wide mail directory</heading>
6211 The system-wide mail directory
6212 is <file>/var/mail</file>. This directory is part of the
6213 base system and should not be owned by any particular mail
6214 agents. The use of the old
6215 location <file>/var/spool/mail</file> is deprecated, even
6216 though the spool may still be physically located there.
6222 <heading>Users and groups</heading>
6225 <heading>Introduction</heading>
6227 The Debian system can be configured to use either plain or
6232 Some user ids (UIDs) and group ids (GIDs) are reserved
6233 globally for use by certain packages. Because some
6234 packages need to include files which are owned by these
6235 users or groups, or need the ids compiled into binaries,
6236 these ids must be used on any Debian system only for the
6237 purpose for which they are allocated. This is a serious
6238 restriction, and we should avoid getting in the way of
6239 local administration policies. In particular, many sites
6240 allocate users and/or local system groups starting at 100.
6244 Apart from this we should have dynamically allocated ids,
6245 which should by default be arranged in some sensible
6246 order, but the behavior should be configurable.
6250 Packages other than <tt>base-passwd</tt> must not modify
6251 <file>/etc/passwd</file>, <file>/etc/shadow</file>,
6252 <file>/etc/group</file> or <file>/etc/gshadow</file>.
6257 <heading>UID and GID classes</heading>
6259 The UID and GID numbers are divided into classes as
6265 Globally allocated by the Debian project, the same
6266 on every Debian system. These ids will appear in
6267 the <file>passwd</file> and <file>group</file> files of all
6268 Debian systems, new ids in this range being added
6269 automatically as the <tt>base-passwd</tt> package is
6274 Packages which need a single statically allocated
6275 uid or gid should use one of these; their
6276 maintainers should ask the <tt>base-passwd</tt>
6284 Dynamically allocated system users and groups.
6285 Packages which need a user or group, but can have
6286 this user or group allocated dynamically and
6287 differently on each system, should use <tt>adduser
6288 --system</tt> to create the group and/or user.
6289 <prgn>adduser</prgn> will check for the existence of
6290 the user or group, and if necessary choose an unused
6291 id based on the ranges specified in
6292 <file>adduser.conf</file>.
6296 <tag>1000-59999:</tag>
6299 Dynamically allocated user accounts. By default
6300 <prgn>adduser</prgn> will choose UIDs and GIDs for
6301 user accounts in this range, though
6302 <file>adduser.conf</file> may be used to modify this
6307 <tag>60000-64999:</tag>
6310 Globally allocated by the Debian project, but only
6311 created on demand. The ids are allocated centrally
6312 and statically, but the actual accounts are only
6313 created on users' systems on demand.
6317 These ids are for packages which are obscure or
6318 which require many statically-allocated ids. These
6319 packages should check for and create the accounts in
6320 <file>/etc/passwd</file> or <file>/etc/group</file> (using
6321 <prgn>adduser</prgn> if it has this facility) if
6322 necessary. Packages which are likely to require
6323 further allocations should have a "hole" left after
6324 them in the allocation, to give them room to
6329 <tag>65000-65533:</tag>
6337 User <tt>nobody</tt>. The corresponding gid refers
6338 to the group <tt>nogroup</tt>.
6345 <tt>(uid_t)(-1) == (gid_t)(-1)</tt> <em>must
6346 not</em> be used, because it is the error return
6355 <sect id="sysvinit">
6356 <heading>System run levels and <file>init.d</file> scripts</heading>
6358 <sect1 id="/etc/init.d">
6359 <heading>Introduction</heading>
6362 The <file>/etc/init.d</file> directory contains the scripts
6363 executed by <prgn>init</prgn> at boot time and when the
6364 init state (or "runlevel") is changed (see <manref
6365 name="init" section="8">).
6369 There are at least two different, yet functionally
6370 equivalent, ways of handling these scripts. For the sake
6371 of simplicity, this document describes only the symbolic
6372 link method. However, it must not be assumed by maintainer
6373 scripts that this method is being used, and any automated
6374 manipulation of the various runlevel behaviors by
6375 maintainer scripts must be performed using
6376 <prgn>update-rc.d</prgn> as described below and not by
6377 manually installing or removing symlinks. For information
6378 on the implementation details of the other method,
6379 implemented in the <tt>file-rc</tt> package, please refer
6380 to the documentation of that package.
6384 These scripts are referenced by symbolic links in the
6385 <file>/etc/rc<var>n</var>.d</file> directories. When changing
6386 runlevels, <prgn>init</prgn> looks in the directory
6387 <file>/etc/rc<var>n</var>.d</file> for the scripts it should
6388 execute, where <tt><var>n</var></tt> is the runlevel that
6389 is being changed to, or <tt>S</tt> for the boot-up
6394 The names of the links all have the form
6395 <file>S<var>mm</var><var>script</var></file> or
6396 <file>K<var>mm</var><var>script</var></file> where
6397 <var>mm</var> is a two-digit number and <var>script</var>
6398 is the name of the script (this should be the same as the
6399 name of the actual script in <file>/etc/init.d</file>).
6403 When <prgn>init</prgn> changes runlevel first the targets
6404 of the links whose names start with a <tt>K</tt> are
6405 executed, each with the single argument <tt>stop</tt>,
6406 followed by the scripts prefixed with an <tt>S</tt>, each
6407 with the single argument <tt>start</tt>. (The links are
6408 those in the <file>/etc/rc<var>n</var>.d</file> directory
6409 corresponding to the new runlevel.) The <tt>K</tt> links
6410 are responsible for killing services and the <tt>S</tt>
6411 link for starting services upon entering the runlevel.
6415 For example, if we are changing from runlevel 2 to
6416 runlevel 3, init will first execute all of the <tt>K</tt>
6417 prefixed scripts it finds in <file>/etc/rc3.d</file>, and then
6418 all of the <tt>S</tt> prefixed scripts in that directory.
6419 The links starting with <tt>K</tt> will cause the
6420 referred-to file to be executed with an argument of
6421 <tt>stop</tt>, and the <tt>S</tt> links with an argument
6426 The two-digit number <var>mm</var> is used to determine
6427 the order in which to run the scripts: low-numbered links
6428 have their scripts run first. For example, the
6429 <tt>K20</tt> scripts will be executed before the
6430 <tt>K30</tt> scripts. This is used when a certain service
6431 must be started before another. For example, the name
6432 server <prgn>bind</prgn> might need to be started before
6433 the news server <prgn>inn</prgn> so that <prgn>inn</prgn>
6434 can set up its access lists. In this case, the script
6435 that starts <prgn>bind</prgn> would have a lower number
6436 than the script that starts <prgn>inn</prgn> so that it
6438 <example compact="compact">
6445 The two runlevels 0 (halt) and 6 (reboot) are slightly
6446 different. In these runlevels, the links with an
6447 <tt>S</tt> prefix are still called after those with a
6448 <tt>K</tt> prefix, but they too are called with the single
6449 argument <tt>stop</tt>.
6453 <sect1 id="writing-init">
6454 <heading>Writing the scripts</heading>
6457 Packages that include daemons for system services should
6458 place scripts in <file>/etc/init.d</file> to start or stop
6459 services at boot time or during a change of runlevel.
6460 These scripts should be named
6461 <file>/etc/init.d/<var>package</var></file>, and they should
6462 accept one argument, saying what to do:
6465 <tag><tt>start</tt></tag>
6466 <item>start the service,</item>
6468 <tag><tt>stop</tt></tag>
6469 <item>stop the service,</item>
6471 <tag><tt>restart</tt></tag>
6472 <item>stop and restart the service if it's already running,
6473 otherwise start the service</item>
6475 <tag><tt>reload</tt></tag>
6476 <item><p>cause the configuration of the service to be
6477 reloaded without actually stopping and restarting
6480 <tag><tt>force-reload</tt></tag>
6481 <item>cause the configuration to be reloaded if the
6482 service supports this, otherwise restart the
6486 The <tt>start</tt>, <tt>stop</tt>, <tt>restart</tt>, and
6487 <tt>force-reload</tt> options should be supported by all
6488 scripts in <file>/etc/init.d</file>, the <tt>reload</tt>
6493 The <file>init.d</file> scripts must ensure that they will
6494 behave sensibly (i.e., returning success and not starting
6495 multiple copies of a service) if invoked with <tt>start</tt>
6496 when the service is already running, or with <tt>stop</tt>
6497 when it isn't, and that they don't kill unfortunately-named
6498 user processes. The best way to achieve this is usually to
6499 use <prgn>start-stop-daemon</prgn> with the <tt>--oknodo</tt>
6504 Be careful of using <tt>set -e</tt> in <file>init.d</file>
6505 scripts. Writing correct <file>init.d</file> scripts requires
6506 accepting various error exit statuses when daemons are already
6507 running or already stopped without aborting
6508 the <file>init.d</file> script, and common <file>init.d</file>
6509 function libraries are not safe to call with <tt>set -e</tt>
6511 <tt>/lib/lsb/init-functions</tt>, which assists in writing
6512 LSB-compliant init scripts, may fail if <tt>set -e</tt> is
6513 in effect and echoing status messages to the console fails,
6515 </footnote>. For <tt>init.d</tt> scripts, it's often easier
6516 to not use <tt>set -e</tt> and instead check the result of
6517 each command separately.
6521 If a service reloads its configuration automatically (as
6522 in the case of <prgn>cron</prgn>, for example), the
6523 <tt>reload</tt> option of the <file>init.d</file> script
6524 should behave as if the configuration has been reloaded
6529 The <file>/etc/init.d</file> scripts must be treated as
6530 configuration files, either (if they are present in the
6531 package, that is, in the .deb file) by marking them as
6532 <tt>conffile</tt>s, or, (if they do not exist in the .deb)
6533 by managing them correctly in the maintainer scripts (see
6534 <ref id="config-files">). This is important since we want
6535 to give the local system administrator the chance to adapt
6536 the scripts to the local system, e.g., to disable a
6537 service without de-installing the package, or to specify
6538 some special command line options when starting a service,
6539 while making sure their changes aren't lost during the next
6544 These scripts should not fail obscurely when the
6545 configuration files remain but the package has been
6546 removed, as configuration files remain on the system after
6547 the package has been removed. Only when <prgn>dpkg</prgn>
6548 is executed with the <tt>--purge</tt> option will
6549 configuration files be removed. In particular, as the
6550 <file>/etc/init.d/<var>package</var></file> script itself is
6551 usually a <tt>conffile</tt>, it will remain on the system
6552 if the package is removed but not purged. Therefore, you
6553 should include a <tt>test</tt> statement at the top of the
6555 <example compact="compact">
6556 test -f <var>program-executed-later-in-script</var> || exit 0
6561 Often there are some variables in the <file>init.d</file>
6562 scripts whose values control the behavior of the scripts,
6563 and which a system administrator is likely to want to
6564 change. As the scripts themselves are frequently
6565 <tt>conffile</tt>s, modifying them requires that the
6566 administrator merge in their changes each time the package
6567 is upgraded and the <tt>conffile</tt> changes. To ease
6568 the burden on the system administrator, such configurable
6569 values should not be placed directly in the script.
6570 Instead, they should be placed in a file in
6571 <file>/etc/default</file>, which typically will have the same
6572 base name as the <file>init.d</file> script. This extra file
6573 should be sourced by the script when the script runs. It
6574 must contain only variable settings and comments in SUSv3
6575 <prgn>sh</prgn> format. It may either be a
6576 <tt>conffile</tt> or a configuration file maintained by
6577 the package maintainer scripts. See <ref id="config-files">
6582 To ensure that vital configurable values are always
6583 available, the <file>init.d</file> script should set default
6584 values for each of the shell variables it uses, either
6585 before sourcing the <file>/etc/default/</file> file or
6586 afterwards using something like the <tt>:
6587 ${VAR:=default}</tt> syntax. Also, the <file>init.d</file>
6588 script must behave sensibly and not fail if the
6589 <file>/etc/default</file> file is deleted.
6593 <file>/var/run</file> and <file>/var/lock</file> may be mounted
6594 as temporary filesystems<footnote>
6595 For example, using the <tt>RAMRUN</tt> and <tt>RAMLOCK</tt>
6596 options in <file>/etc/default/rcS</file>.
6597 </footnote>, so the <file>init.d</file> scripts must handle this
6598 correctly. This will typically amount to creating any required
6599 subdirectories dynamically when the <file>init.d</file> script
6600 is run, rather than including them in the package and relying on
6601 <prgn>dpkg</prgn> to create them.
6606 <heading>Interfacing with the initscript system</heading>
6609 Maintainers should use the abstraction layer provided by
6610 the <prgn>update-rc.d</prgn> and <prgn>invoke-rc.d</prgn>
6611 programs to deal with initscripts in their packages'
6612 scripts such as <prgn>postinst</prgn>, <prgn>prerm</prgn>
6613 and <prgn>postrm</prgn>.
6617 Directly managing the /etc/rc?.d links and directly
6618 invoking the <file>/etc/init.d/</file> initscripts should
6619 be done only by packages providing the initscript
6620 subsystem (such as <prgn>sysv-rc</prgn> and
6621 <prgn>file-rc</prgn>).
6625 <heading>Managing the links</heading>
6628 The program <prgn>update-rc.d</prgn> is provided for
6629 package maintainers to arrange for the proper creation and
6630 removal of <file>/etc/rc<var>n</var>.d</file> symbolic links,
6631 or their functional equivalent if another method is being
6632 used. This may be used by maintainers in their packages'
6633 <prgn>postinst</prgn> and <prgn>postrm</prgn> scripts.
6637 You must not include any <file>/etc/rc<var>n</var>.d</file>
6638 symbolic links in the actual archive or manually create or
6639 remove the symbolic links in maintainer scripts; you must
6640 use the <prgn>update-rc.d</prgn> program instead. (The
6641 former will fail if an alternative method of maintaining
6642 runlevel information is being used.) You must not include
6643 the <file>/etc/rc<var>n</var>.d</file> directories themselves
6644 in the archive either. (Only the <tt>sysvinit</tt>
6649 By default <prgn>update-rc.d</prgn> will start services in
6650 each of the multi-user state runlevels (2, 3, 4, and 5)
6651 and stop them in the halt runlevel (0), the single-user
6652 runlevel (1) and the reboot runlevel (6). The system
6653 administrator will have the opportunity to customize
6654 runlevels by simply adding, moving, or removing the
6655 symbolic links in <file>/etc/rc<var>n</var>.d</file> if
6656 symbolic links are being used, or by modifying
6657 <file>/etc/runlevel.conf</file> if the <tt>file-rc</tt> method
6662 To get the default behavior for your package, put in your
6663 <prgn>postinst</prgn> script
6664 <example compact="compact">
6665 update-rc.d <var>package</var> defaults
6667 and in your <prgn>postrm</prgn>
6668 <example compact="compact">
6669 if [ "$1" = purge ]; then
6670 update-rc.d <var>package</var> remove
6672 </example>. Note that if your package changes runlevels
6673 or priority, you may have to remove and recreate the links,
6674 since otherwise the old links may persist. Refer to the
6675 documentation of <prgn>update-rc.d</prgn>.
6679 This will use a default sequence number of 20. If it does
6680 not matter when or in which order the <file>init.d</file>
6681 script is run, use this default. If it does, then you
6682 should talk to the maintainer of the <prgn>sysvinit</prgn>
6683 package or post to <tt>debian-devel</tt>, and they will
6684 help you choose a number.
6688 For more information about using <tt>update-rc.d</tt>,
6689 please consult its man page <manref name="update-rc.d"
6695 <heading>Running initscripts</heading>
6697 The program <prgn>invoke-rc.d</prgn> is provided to make
6698 it easier for package maintainers to properly invoke an
6699 initscript, obeying runlevel and other locally-defined
6700 constraints that might limit a package's right to start,
6701 stop and otherwise manage services. This program may be
6702 used by maintainers in their packages' scripts.
6706 The package maintainer scripts must use
6707 <prgn>invoke-rc.d</prgn> to invoke the
6708 <file>/etc/init.d/*</file> initscripts, instead of
6709 calling them directly.
6713 By default, <prgn>invoke-rc.d</prgn> will pass any
6714 action requests (start, stop, reload, restart...) to the
6715 <file>/etc/init.d</file> script, filtering out requests
6716 to start or restart a service out of its intended
6721 Most packages will simply need to change:
6722 <example compact="compact">/etc/init.d/<package>
6723 <action></example> in their <prgn>postinst</prgn>
6724 and <prgn>prerm</prgn> scripts to:
6725 <example compact="compact">
6726 if which invoke-rc.d >/dev/null 2>&1; then
6727 invoke-rc.d <var>package</var> <action>
6729 /etc/init.d/<var>package</var> <action>
6735 A package should register its initscript services using
6736 <prgn>update-rc.d</prgn> before it tries to invoke them
6737 using <prgn>invoke-rc.d</prgn>. Invocation of
6738 unregistered services may fail.
6742 For more information about using
6743 <prgn>invoke-rc.d</prgn>, please consult its man page
6744 <manref name="invoke-rc.d" section="8">.
6750 <heading>Boot-time initialization</heading>
6753 There used to be another directory, <file>/etc/rc.boot</file>,
6754 which contained scripts which were run once per machine
6755 boot. This has been deprecated in favour of links from
6756 <file>/etc/rcS.d</file> to files in <file>/etc/init.d</file> as
6757 described in <ref id="/etc/init.d">. Packages must not
6758 place files in <file>/etc/rc.boot</file>.
6763 <heading>Example</heading>
6766 An example on which you can base your
6767 <file>/etc/init.d</file> scripts is found in
6768 <file>/etc/init.d/skeleton</file>.
6775 <heading>Console messages from <file>init.d</file> scripts</heading>
6778 This section describes the formats to be used for messages
6779 written to standard output by the <file>/etc/init.d</file>
6780 scripts. The intent is to improve the consistency of
6781 Debian's startup and shutdown look and feel. For this
6782 reason, please look very carefully at the details. We want
6783 the messages to have the same format in terms of wording,
6784 spaces, punctuation and case of letters.
6788 Here is a list of overall rules that should be used for
6789 messages generated by <file>/etc/init.d</file> scripts.
6795 The message should fit in one line (fewer than 80
6796 characters), start with a capital letter and end with
6797 a period (<tt>.</tt>) and line feed (<tt>"\n"</tt>).
6801 If the script is performing some time consuming task in
6802 the background (not merely starting or stopping a
6803 program, for instance), an ellipsis (three dots:
6804 <tt>...</tt>) should be output to the screen, with no
6805 leading or tailing whitespace or line feeds.
6809 The messages should appear as if the computer is telling
6810 the user what it is doing (politely :-), but should not
6811 mention "it" directly. For example, instead of:
6812 <example compact="compact">
6813 I'm starting network daemons: nfsd mountd.
6815 the message should say
6816 <example compact="compact">
6817 Starting network daemons: nfsd mountd.
6824 <tt>init.d</tt> script should use the following standard
6825 message formats for the situations enumerated below.
6831 <p>When daemons are started</p>
6834 If the script starts one or more daemons, the output
6835 should look like this (a single line, no leading
6837 <example compact="compact">
6838 Starting <var>description</var>: <var>daemon-1</var> ... <var>daemon-n</var>.
6840 The <var>description</var> should describe the
6841 subsystem the daemon or set of daemons are part of,
6842 while <var>daemon-1</var> up to <var>daemon-n</var>
6843 denote each daemon's name (typically the file name of
6848 For example, the output of <file>/etc/init.d/lpd</file>
6850 <example compact="compact">
6851 Starting printer spooler: lpd.
6856 This can be achieved by saying
6857 <example compact="compact">
6858 echo -n "Starting printer spooler: lpd"
6859 start-stop-daemon --start --quiet --exec /usr/sbin/lpd
6862 in the script. If there are more than one daemon to
6863 start, the output should look like this:
6864 <example compact="compact">
6865 echo -n "Starting remote file system services:"
6866 echo -n " nfsd"; start-stop-daemon --start --quiet nfsd
6867 echo -n " mountd"; start-stop-daemon --start --quiet mountd
6868 echo -n " ugidd"; start-stop-daemon --start --quiet ugidd
6871 This makes it possible for the user to see what is
6872 happening and when the final daemon has been started.
6873 Care should be taken in the placement of white spaces:
6874 in the example above the system administrators can
6875 easily comment out a line if they don't want to start
6876 a specific daemon, while the displayed message still
6882 <p>When a system parameter is being set</p>
6885 If you have to set up different system parameters
6886 during the system boot, you should use this format:
6887 <example compact="compact">
6888 Setting <var>parameter</var> to "<var>value</var>".
6893 You can use a statement such as the following to get
6895 <example compact="compact">
6896 echo "Setting DNS domainname to \"$domainname\"."
6901 Note that the same symbol (<tt>"</tt>) <!-- " --> is used
6902 for the left and right quotation marks. A grave accent
6903 (<tt>`</tt>) is not a quote character; neither is an
6904 apostrophe (<tt>'</tt>).
6909 <p>When a daemon is stopped or restarted</p>
6912 When you stop or restart a daemon, you should issue a
6913 message identical to the startup message, except that
6914 <tt>Starting</tt> is replaced with <tt>Stopping</tt>
6915 or <tt>Restarting</tt> respectively.
6919 For example, stopping the printer daemon will look like
6921 <example compact="compact">
6922 Stopping printer spooler: lpd.
6928 <p>When something is executed</p>
6931 There are several examples where you have to run a
6932 program at system startup or shutdown to perform a
6933 specific task, for example, setting the system's clock
6934 using <prgn>netdate</prgn> or killing all processes
6935 when the system shuts down. Your message should look
6937 <example compact="compact">
6938 Doing something very useful...done.
6940 You should print the <tt>done.</tt> immediately after
6941 the job has been completed, so that the user is
6942 informed why they have to wait. You can get this
6944 <example compact="compact">
6945 echo -n "Doing something very useful..."
6954 <p>When the configuration is reloaded</p>
6957 When a daemon is forced to reload its configuration
6958 files you should use the following format:
6959 <example compact="compact">
6960 Reloading <var>description</var> configuration...done.
6962 where <var>description</var> is the same as in the
6963 daemon starting message.
6971 <heading>Cron jobs</heading>
6974 Packages must not modify the configuration file
6975 <file>/etc/crontab</file>, and they must not modify the files in
6976 <file>/var/spool/cron/crontabs</file>.</p>
6979 If a package wants to install a job that has to be executed
6980 via cron, it should place a file with the name of the
6981 package in one or more of the following directories:
6982 <example compact="compact">
6988 As these directory names imply, the files within them are
6989 executed on an hourly, daily, weekly, or monthly basis,
6990 respectively. The exact times are listed in
6991 <file>/etc/crontab</file>.</p>
6994 All files installed in any of these directories must be
6995 scripts (e.g., shell scripts or Perl scripts) so that they
6996 can easily be modified by the local system administrator.
6997 In addition, they must be treated as configuration files.
7001 If a certain job has to be executed at some other frequency or
7002 at a specific time, the package should install a file
7003 <file>/etc/cron.d/<var>package</var></file>. This file uses the
7004 same syntax as <file>/etc/crontab</file> and is processed by
7005 <prgn>cron</prgn> automatically. The file must also be
7006 treated as a configuration file. (Note that entries in the
7007 <file>/etc/cron.d</file> directory are not handled by
7008 <prgn>anacron</prgn>. Thus, you should only use this
7009 directory for jobs which may be skipped if the system is not
7012 Unlike <file>crontab</file> files described in the IEEE Std
7013 1003.1-2008 (POSIX.1) available from
7014 <url id="http://www.opengroup.org/onlinepubs/9699919799/"
7015 name="The Open Group">, the files in
7016 <file>/etc/cron.d</file> and the file
7017 <file>/etc/crontab</file> have seven fields; namely:
7019 <item>Minute [0,59]</item>
7020 <item>Hour [0,23]</item>
7021 <item>Day of the month [1,31]</item>
7022 <item>Month of the year [1,12]</item>
7023 <item>Day of the week ([0,6] with 0=Sunday)</item>
7024 <item>Username</item>
7025 <item>Command to be run</item>
7027 Ranges of numbers are allowed. Ranges are two numbers
7028 separated with a hyphen. The specified range is inclusive.
7029 Lists are allowed. A list is a set of numbers (or ranges)
7030 separated by commas. Step values can be used in conjunction
7035 The scripts or <tt>crontab</tt> entries in these directories should
7036 check if all necessary programs are installed before they
7037 try to execute them. Otherwise, problems will arise when a
7038 package was removed but not purged since configuration files
7039 are kept on the system in this situation.
7043 Any <tt>cron</tt> daemon must provide
7044 <file>/usr/bin/crontab</file> and support normal
7045 <tt>crontab</tt> entries as specified in POSIX. The daemon
7046 must also support names for days and months, ranges, and
7047 step values. It has to support <file>/etc/crontab</file>,
7048 and correctly execute the scripts in
7049 <file>/etc/cron.d</file>. The daemon must also correctly
7051 <file>/etc/cron.{hourly,daily,weekly,monthly}</file>.
7056 <heading>Menus</heading>
7059 The Debian <tt>menu</tt> package provides a standard
7060 interface between packages providing applications and
7061 <em>menu programs</em> (either X window managers or
7062 text-based menu programs such as <prgn>pdmenu</prgn>).
7066 All packages that provide applications that need not be
7067 passed any special command line arguments for normal
7068 operation should register a menu entry for those
7069 applications, so that users of the <tt>menu</tt> package
7070 will automatically get menu entries in their window
7071 managers, as well in shells like <tt>pdmenu</tt>.
7075 Menu entries should follow the current menu policy.
7079 The menu policy can be found in the <tt>menu-policy</tt>
7080 files in the <tt>debian-policy</tt> package.
7081 It is also available from the Debian web mirrors at
7082 <tt><url name="/doc/packaging-manuals/menu-policy/"
7083 id="http://www.debian.org/doc/packaging-manuals/menu-policy/"></tt>.
7087 Please also refer to the <em>Debian Menu System</em>
7088 documentation that comes with the <package>menu</package>
7089 package for information about how to register your
7095 <heading>Multimedia handlers</heading>
7098 MIME (Multipurpose Internet Mail Extensions, RFCs 2045-2049)
7099 is a mechanism for encoding files and data streams and
7100 providing meta-information about them, in particular their
7101 type (e.g. audio or video) and format (e.g. PNG, HTML,
7106 Registration of MIME type handlers allows programs like mail
7107 user agents and web browsers to invoke these handlers to
7108 view, edit or display MIME types they don't support directly.
7112 Packages which provide the ability to view/show/play,
7113 compose, edit or print MIME types should register themselves
7114 as such following the current MIME support policy.
7118 The MIME support policy can be found in the <tt>mime-policy</tt>
7119 files in the <tt>debian-policy</tt> package.
7120 It is also available from the Debian web mirrors at
7121 <tt><url name="/doc/packaging-manuals/mime-policy/"
7122 id="http://www.debian.org/doc/packaging-manuals/mime-policy/"></tt>.
7128 <heading>Keyboard configuration</heading>
7131 To achieve a consistent keyboard configuration so that all
7132 applications interpret a keyboard event the same way, all
7133 programs in the Debian distribution must be configured to
7134 comply with the following guidelines.
7138 The following keys must have the specified interpretations:
7141 <tag><tt><--</tt></tag>
7142 <item>delete the character to the left of the cursor</item>
7144 <tag><tt>Delete</tt></tag>
7145 <item>delete the character to the right of the cursor</item>
7147 <tag><tt>Control+H</tt></tag>
7148 <item>emacs: the help prefix</item>
7151 The interpretation of any keyboard events should be
7152 independent of the terminal that is used, be it a virtual
7153 console, an X terminal emulator, an rlogin/telnet session,
7158 The following list explains how the different programs
7159 should be set up to achieve this:
7165 <tt><--</tt> generates <tt>KB_BackSpace</tt> in X.
7169 <tt>Delete</tt> generates <tt>KB_Delete</tt> in X.
7173 X translations are set up to make
7174 <tt>KB_Backspace</tt> generate ASCII DEL, and to make
7175 <tt>KB_Delete</tt> generate <tt>ESC [ 3 ~</tt> (this
7176 is the vt220 escape code for the "delete character"
7177 key). This must be done by loading the X resources
7178 using <prgn>xrdb</prgn> on all local X displays, not
7179 using the application defaults, so that the
7180 translation resources used correspond to the
7181 <prgn>xmodmap</prgn> settings.
7185 The Linux console is configured to make
7186 <tt><--</tt> generate DEL, and <tt>Delete</tt>
7187 generate <tt>ESC [ 3 ~</tt>.
7191 X applications are configured so that <tt><</tt>
7192 deletes left, and <tt>Delete</tt> deletes right. Motif
7193 applications already work like this.
7197 Terminals should have <tt>stty erase ^?</tt> .
7201 The <tt>xterm</tt> terminfo entry should have <tt>ESC
7202 [ 3 ~</tt> for <tt>kdch1</tt>, just as for
7203 <tt>TERM=linux</tt> and <tt>TERM=vt220</tt>.
7207 Emacs is programmed to map <tt>KB_Backspace</tt> or
7208 the <tt>stty erase</tt> character to
7209 <tt>delete-backward-char</tt>, and <tt>KB_Delete</tt>
7210 or <tt>kdch1</tt> to <tt>delete-forward-char</tt>, and
7211 <tt>^H</tt> to <tt>help</tt> as always.
7215 Other applications use the <tt>stty erase</tt>
7216 character and <tt>kdch1</tt> for the two delete keys,
7217 with ASCII DEL being "delete previous character" and
7218 <tt>kdch1</tt> being "delete character under
7226 This will solve the problem except for the following
7233 Some terminals have a <tt><--</tt> key that cannot
7234 be made to produce anything except <tt>^H</tt>. On
7235 these terminals Emacs help will be unavailable on
7236 <tt>^H</tt> (assuming that the <tt>stty erase</tt>
7237 character takes precedence in Emacs, and has been set
7238 correctly). <tt>M-x help</tt> or <tt>F1</tt> (if
7239 available) can be used instead.
7243 Some operating systems use <tt>^H</tt> for <tt>stty
7244 erase</tt>. However, modern telnet versions and all
7245 rlogin versions propagate <tt>stty</tt> settings, and
7246 almost all UNIX versions honour <tt>stty erase</tt>.
7247 Where the <tt>stty</tt> settings are not propagated
7248 correctly, things can be made to work by using
7249 <tt>stty</tt> manually.
7253 Some systems (including previous Debian versions) use
7254 <prgn>xmodmap</prgn> to arrange for both
7255 <tt><--</tt> and <tt>Delete</tt> to generate
7256 <tt>KB_Delete</tt>. We can change the behavior of
7257 their X clients using the same X resources that we use
7258 to do it for our own clients, or configure our clients
7259 using their resources when things are the other way
7260 around. On displays configured like this
7261 <tt>Delete</tt> will not work, but <tt><--</tt>
7266 Some operating systems have different <tt>kdch1</tt>
7267 settings in their <tt>terminfo</tt> database for
7268 <tt>xterm</tt> and others. On these systems the
7269 <tt>Delete</tt> key will not work correctly when you
7270 log in from a system conforming to our policy, but
7271 <tt><--</tt> will.
7278 <heading>Environment variables</heading>
7281 A program must not depend on environment variables to get
7282 reasonable defaults. (That's because these environment
7283 variables would have to be set in a system-wide
7284 configuration file like <file>/etc/profile</file>, which is not
7285 supported by all shells.)
7289 If a program usually depends on environment variables for its
7290 configuration, the program should be changed to fall back to
7291 a reasonable default configuration if these environment
7292 variables are not present. If this cannot be done easily
7293 (e.g., if the source code of a non-free program is not
7294 available), the program must be replaced by a small
7295 "wrapper" shell script which sets the environment variables
7296 if they are not already defined, and calls the original program.
7300 Here is an example of a wrapper script for this purpose:
7302 <example compact="compact">
7304 BAR=${BAR:-/var/lib/fubar}
7306 exec /usr/lib/foo/foo "$@"
7311 Furthermore, as <file>/etc/profile</file> is a configuration
7312 file of the <prgn>base-files</prgn> package, other packages must
7313 not put any environment variables or other commands into that
7318 <sect id="doc-base">
7319 <heading>Registering Documents using doc-base</heading>
7322 The <package>doc-base</package> package implements a
7323 flexible mechanism for handling and presenting
7324 documentation. The recommended practice is for every Debian
7325 package that provides online documentation (other than just
7326 manual pages) to register these documents with
7327 <package>doc-base</package> by installing a
7328 <package>doc-base</package> control file via the
7329 <prgn/install-docs/ script at installation time and
7330 de-register the manuals again when the package is removed.
7333 Please refer to the documentation that comes with the
7334 <package>doc-base</package> package for information and
7343 <heading>Files</heading>
7345 <sect id="binaries">
7346 <heading>Binaries</heading>
7349 Two different packages must not install programs with
7350 different functionality but with the same filenames. (The
7351 case of two programs having the same functionality but
7352 different implementations is handled via "alternatives" or
7353 the "Conflicts" mechanism. See <ref id="maintscripts"> and
7354 <ref id="conflicts"> respectively.) If this case happens,
7355 one of the programs must be renamed. The maintainers should
7356 report this to the <tt>debian-devel</tt> mailing list and
7357 try to find a consensus about which program will have to be
7358 renamed. If a consensus cannot be reached, <em>both</em>
7359 programs must be renamed.
7363 By default, when a package is being built, any binaries
7364 created should include debugging information, as well as
7365 being compiled with optimization. You should also turn on
7366 as many reasonable compilation warnings as possible; this
7367 makes life easier for porters, who can then look at build
7368 logs for possible problems. For the C programming language,
7369 this means the following compilation parameters should be
7371 <example compact="compact">
7373 CFLAGS = -O2 -g -Wall # sane warning options vary between programs
7375 INSTALL = install -s # (or use strip on the files in debian/tmp)
7380 Note that by default all installed binaries should be stripped,
7381 either by using the <tt>-s</tt> flag to
7382 <prgn>install</prgn>, or by calling <prgn>strip</prgn> on
7383 the binaries after they have been copied into
7384 <file>debian/tmp</file> but before the tree is made into a
7389 Although binaries in the build tree should be compiled with
7390 debugging information by default, it can often be difficult to
7391 debug programs if they are also subjected to compiler
7392 optimization. For this reason, it is recommended to support the
7393 standardized environment variable <tt>DEB_BUILD_OPTIONS</tt>
7394 (see <ref id="debianrules-options">). This variable can contain
7395 several flags to change how a package is compiled and built.
7399 It is up to the package maintainer to decide what
7400 compilation options are best for the package. Certain
7401 binaries (such as computationally-intensive programs) will
7402 function better with certain flags (<tt>-O3</tt>, for
7403 example); feel free to use them. Please use good judgment
7404 here. Don't use flags for the sake of it; only use them
7405 if there is good reason to do so. Feel free to override
7406 the upstream author's ideas about which compilation
7407 options are best: they are often inappropriate for our
7413 <sect id="libraries">
7414 <heading>Libraries</heading>
7417 If the package is <strong>architecture: any</strong>, then
7418 the shared library compilation and linking flags must have
7419 <tt>-fPIC</tt>, or the package shall not build on some of
7420 the supported architectures<footnote>
7422 If you are using GCC, <tt>-fPIC</tt> produces code with
7423 relocatable position independent code, which is required for
7424 most architectures to create a shared library, with i386 and
7425 perhaps some others where non position independent code is
7426 permitted in a shared library.
7429 Position independent code may have a performance penalty,
7430 especially on <tt>i386</tt>. However, in most cases the
7431 speed penalty must be measured against the memory wasted on
7432 the few architectures where non position independent code is
7435 </footnote>. Any exception to this rule must be discussed on
7436 the mailing list <em>debian-devel@lists.debian.org</em>, and
7437 a rough consensus obtained. The reasons for not compiling
7438 with <tt>-fPIC</tt> flag must be recorded in the file
7439 <tt>README.Debian</tt>, and care must be taken to either
7440 restrict the architecture or arrange for <tt>-fPIC</tt> to
7441 be used on architectures where it is required.<footnote>
7443 Some of the reasons why this might be required is if the
7444 library contains hand crafted assembly code that is not
7445 relocatable, the speed penalty is excessive for compute
7446 intensive libs, and similar reasons.
7451 As to the static libraries, the common case is not to have
7452 relocatable code, since there is no benefit, unless in specific
7453 cases; therefore the static version must not be compiled
7454 with the <tt>-fPIC</tt> flag. Any exception to this rule
7455 should be discussed on the mailing list
7456 <em>debian-devel@lists.debian.org</em>, and the reasons for
7457 compiling with the <tt>-fPIC</tt> flag must be recorded in
7458 the file <tt>README.Debian</tt>. <footnote>
7460 Some of the reasons for linking static libraries with
7461 the <tt>-fPIC</tt> flag are if, for example, one needs a
7462 Perl API for a library that is under rapid development,
7463 and has an unstable API, so shared libraries are
7464 pointless at this phase of the library's development. In
7465 that case, since Perl needs a library with relocatable
7466 code, it may make sense to create a static library with
7467 relocatable code. Another reason cited is if you are
7468 distilling various libraries into a common shared
7469 library, like <tt>mklibs</tt> does in the Debian
7475 In other words, if both a shared and a static library is
7476 being built, each source unit (<tt>*.c</tt>, for example,
7477 for C files) will need to be compiled twice, for the normal
7482 Libraries should be built with threading support and to be
7483 thread-safe if the library supports this.
7487 Although not enforced by the build tools, shared libraries
7488 must be linked against all libraries that they use symbols from
7489 in the same way that binaries are. This ensures the correct
7490 functioning of the <qref id="sharedlibs-shlibdeps">shlibs</qref>
7491 system and guarantees that all libraries can be safely opened
7492 with <tt>dlopen()</tt>. Packagers may wish to use the gcc
7493 option <tt>-Wl,-z,defs</tt> when building a shared library.
7494 Since this option enforces symbol resolution at build time,
7495 a missing library reference will be caught early as a fatal
7500 All installed shared libraries should be stripped with
7501 <example compact="compact">
7502 strip --strip-unneeded <var>your-lib</var>
7504 (The option <tt>--strip-unneeded</tt> makes
7505 <prgn>strip</prgn> remove only the symbols which aren't
7506 needed for relocation processing.) Shared libraries can
7507 function perfectly well when stripped, since the symbols for
7508 dynamic linking are in a separate part of the ELF object
7510 You might also want to use the options
7511 <tt>--remove-section=.comment</tt> and
7512 <tt>--remove-section=.note</tt> on both shared libraries
7513 and executables, and <tt>--strip-debug</tt> on static
7519 Note that under some circumstances it may be useful to
7520 install a shared library unstripped, for example when
7521 building a separate package to support debugging.
7525 Shared object files (often <file>.so</file> files) that are not
7526 public libraries, that is, they are not meant to be linked
7527 to by third party executables (binaries of other packages),
7528 should be installed in subdirectories of the
7529 <file>/usr/lib</file> directory. Such files are exempt from the
7530 rules that govern ordinary shared libraries, except that
7531 they must not be installed executable and should be
7533 A common example are the so-called "plug-ins",
7534 internal shared objects that are dynamically loaded by
7535 programs using <manref name="dlopen" section="3">.
7540 Packages that use <prgn>libtool</prgn> to create and install
7541 their shared libraries install a file containing additional
7542 metadata (ending in <file>.la</file>) alongside the library.
7543 For public libraries intended for use by other packages, these
7544 files normally should not be included in the Debian package,
7545 since the information they include is not necessary to link with
7546 the shared library on Debian and can add unnecessary additional
7547 dependencies to other programs or libraries.<footnote>
7548 These files store, among other things, all libraries on which
7549 that shared library depends. Unfortunately, if
7550 the <file>.la</file> file is present and contains that
7551 dependency information, using <prgn>libtool</prgn> when
7552 linking against that library will cause the resulting program
7553 or library to be linked against those dependencies as well,
7554 even if this is unnecessary. This can create unneeded
7555 dependencies on shared library packages that would otherwise
7556 be hidden behind the library ABI, and can make library
7557 transitions to new SONAMEs unnecessarily complicated and
7558 difficult to manage.
7560 If the <file>.la</file> file is required for that library (if,
7561 for instance, it's loaded via <tt>libltdl</tt> in a way that
7562 requires that meta-information), the <tt>dependency_libs</tt>
7563 setting in the <file>.la</file> file should normally be set to
7564 the empty string. If the shared library development package has
7565 historically included the <file>.la</file>, it must be retained
7566 in the development package (with <tt>dependency_libs</tt>
7567 emptied) until all libraries that depend on it have removed or
7568 emptied <tt>dependency_libs</tt> in their <file>.la</file>
7569 files to prevent linking with those other libraries
7570 using <prgn>libtool</prgn> from failing.
7574 If the <file>.la</file> must be included, it should be included
7575 in the development (<tt>-dev</tt>) package, unless the library
7576 will be loaded by <prgn>libtool</prgn>'s <tt>libltdl</tt>
7577 library. If it is intended for use with <tt>libltdl</tt>,
7578 the <file>.la</file> files must go in the run-time library
7583 These requirements for handling of <file>.la</file> files do not
7584 apply to loadable modules or libraries not installed in
7585 directories searched by default by the dynamic linker. Packages
7586 installing loadable modules will frequently need to install
7587 the <file>.la</file> files alongside the modules so that they
7588 can be loaded by <tt>libltdl</tt>. <tt>dependency_libs</tt>
7589 does not need to be modified for libraries or modules that are
7590 not installed in directories searched by the dynamic linker by
7591 default and not intended for use by other packages.
7595 You must make sure that you use only released versions of
7596 shared libraries to build your packages; otherwise other
7597 users will not be able to run your binaries
7598 properly. Producing source packages that depend on
7599 unreleased compilers is also usually a bad
7606 <heading>Shared libraries</heading>
7608 This section has moved to <ref id="sharedlibs">.
7614 <heading>Scripts</heading>
7617 All command scripts, including the package maintainer
7618 scripts inside the package and used by <prgn>dpkg</prgn>,
7619 should have a <tt>#!</tt> line naming the shell to be used
7624 In the case of Perl scripts this should be
7625 <tt>#!/usr/bin/perl</tt>.
7629 When scripts are installed into a directory in the system
7630 PATH, the script name should not include an extension such
7631 as <tt>.sh</tt> or <tt>.pl</tt> that denotes the scripting
7632 language currently used to implement it.
7635 Shell scripts (<prgn>sh</prgn> and <prgn>bash</prgn>) other than
7636 <file>init.d</file> scripts should almost certainly start
7637 with <tt>set -e</tt> so that errors are detected.
7638 <file>init.d</file> scripts are something of a special case, due
7639 to how frequently they need to call commands that are allowed to
7640 fail, and it may instead be easier to check the exit status of
7641 commands directly. See <ref id="writing-init"> for more
7642 information about writing <file>init.d</file> scripts.
7645 Every script should use <tt>set -e</tt> or check the exit status
7646 of <em>every</em> command.
7649 Scripts may assume that <file>/bin/sh</file> implements the
7650 SUSv3 Shell Command Language<footnote>
7651 Single UNIX Specification, version 3, which is also IEEE
7652 1003.1-2004 (POSIX), and is available on the World Wide Web
7653 from <url id="http://www.unix.org/version3/online.html"
7654 name="The Open Group"> after free
7655 registration.</footnote>
7656 plus the following additional features not mandated by
7658 These features are in widespread use in the Linux community
7659 and are implemented in all of bash, dash, and ksh, the most
7660 common shells users may wish to use as <file>/bin/sh</file>.
7663 <item><tt>echo -n</tt>, if implemented as a shell built-in,
7664 must not generate a newline.</item>
7665 <item><tt>test</tt>, if implemented as a shell built-in, must
7666 support <tt>-a</tt> and <tt>-o</tt> as binary logical
7668 <item><tt>local</tt> to create a scoped variable must be
7669 supported, including listing multiple variables in a single
7670 local command and assigning a value to a variable at the
7671 same time as localizing it. <tt>local</tt> may or
7672 may not preserve the variable value from an outer scope if
7673 no assignment is present. Uses such as:
7677 # ... use a, b, c, d ...
7680 must be supported and must set the value of <tt>c</tt> to
7683 <item>The XSI extension to <prgn>kill</prgn> allowing <tt>kill
7684 -<var>signal</var></tt>, where <var>signal</var> is either
7685 the name of a signal or one of the numeric signals listed in
7686 the XSI extension (0, 1, 2, 3, 6, 9, 14, and 15), must be
7687 supported if <prgn>kill</prgn> is implemented as a shell
7690 <item>The XSI extension to <prgn>trap</prgn> allowing numeric
7691 signals must be supported. In addition to the signal
7692 numbers listed in the extension, which are the same as for
7693 <prgn>kill</prgn> above, 13 (SIGPIPE) must be allowed.
7696 If a shell script requires non-SUSv3 features from the shell
7697 interpreter other than those listed above, the appropriate shell
7698 must be specified in the first line of the script (e.g.,
7699 <tt>#!/bin/bash</tt>) and the package must depend on the package
7700 providing the shell (unless the shell package is marked
7701 "Essential", as in the case of <prgn>bash</prgn>).
7705 You may wish to restrict your script to SUSv3 features plus the
7706 above set when possible so that it may use <file>/bin/sh</file>
7707 as its interpreter. If your script works with <prgn>dash</prgn>
7708 (originally called <prgn>ash</prgn>), it probably complies with
7709 the above requirements, but if you are in doubt, use
7710 <file>/bin/bash</file>.
7714 Perl scripts should check for errors when making any
7715 system calls, including <tt>open</tt>, <tt>print</tt>,
7716 <tt>close</tt>, <tt>rename</tt> and <tt>system</tt>.
7720 <prgn>csh</prgn> and <prgn>tcsh</prgn> should be avoided as
7721 scripting languages. See <em>Csh Programming Considered
7722 Harmful</em>, one of the <tt>comp.unix.*</tt> FAQs, which
7723 can be found at <url id="http://www.faqs.org/faqs/unix-faq/shell/csh-whynot/">.
7724 If an upstream package comes with <prgn>csh</prgn> scripts
7725 then you must make sure that they start with
7726 <tt>#!/bin/csh</tt> and make your package depend on the
7727 <prgn>c-shell</prgn> virtual package.
7731 Any scripts which create files in world-writeable
7732 directories (e.g., in <file>/tmp</file>) must use a
7733 mechanism which will fail atomically if a file with the same
7734 name already exists.
7738 The Debian base system provides the <prgn>tempfile</prgn>
7739 and <prgn>mktemp</prgn> utilities for use by scripts for
7746 <heading>Symbolic links</heading>
7749 In general, symbolic links within a top-level directory
7750 should be relative, and symbolic links pointing from one
7751 top-level directory into another should be absolute. (A
7752 top-level directory is a sub-directory of the root
7753 directory <file>/</file>.)
7757 In addition, symbolic links should be specified as short as
7758 possible, i.e., link targets like <file>foo/../bar</file> are
7763 Note that when creating a relative link using
7764 <prgn>ln</prgn> it is not necessary for the target of the
7765 link to exist relative to the working directory you're
7766 running <prgn>ln</prgn> from, nor is it necessary to change
7767 directory to the directory where the link is to be made.
7768 Simply include the string that should appear as the target
7769 of the link (this will be a pathname relative to the
7770 directory in which the link resides) as the first argument
7775 For example, in your <prgn>Makefile</prgn> or
7776 <file>debian/rules</file>, you can do things like:
7777 <example compact="compact">
7778 ln -fs gcc $(prefix)/bin/cc
7779 ln -fs gcc debian/tmp/usr/bin/cc
7780 ln -fs ../sbin/sendmail $(prefix)/bin/runq
7781 ln -fs ../sbin/sendmail debian/tmp/usr/bin/runq
7786 A symbolic link pointing to a compressed file should always
7787 have the same file extension as the referenced file. (For
7788 example, if a file <file>foo.gz</file> is referenced by a
7789 symbolic link, the filename of the link has to end with
7790 "<file>.gz</file>" too, as in <file>bar.gz</file>.)
7795 <heading>Device files</heading>
7798 Packages must not include device files or named pipes in the
7803 If a package needs any special device files that are not
7804 included in the base system, it must call
7805 <prgn>MAKEDEV</prgn> in the <prgn>postinst</prgn> script,
7806 after notifying the user<footnote>
7807 This notification could be done via a (low-priority)
7808 debconf message, or an echo (printf) statement.
7813 Packages must not remove any device files in the
7814 <prgn>postrm</prgn> or any other script. This is left to the
7815 system administrator.
7819 Debian uses the serial devices
7820 <file>/dev/ttyS*</file>. Programs using the old
7821 <file>/dev/cu*</file> devices should be changed to use
7822 <file>/dev/ttyS*</file>.
7826 Named pipes needed by the package must be created in
7827 the <prgn>postinst</prgn> script<footnote>
7828 It's better to use <prgn>mkfifo</prgn> rather
7829 than <prgn>mknod</prgn> to create named pipes so that
7830 automated checks for packages incorrectly creating device
7831 files with <prgn>mknod</prgn> won't have false positives.
7832 </footnote> and removed in
7833 the <prgn>prerm</prgn> or <prgn>postrm</prgn> script as
7838 <sect id="config-files">
7839 <heading>Configuration files</heading>
7842 <heading>Definitions</heading>
7846 <tag>configuration file</tag>
7848 A file that affects the operation of a program, or
7849 provides site- or host-specific information, or
7850 otherwise customizes the behavior of a program.
7851 Typically, configuration files are intended to be
7852 modified by the system administrator (if needed or
7853 desired) to conform to local policy or to provide
7854 more useful site-specific behavior.
7857 <tag><tt>conffile</tt></tag>
7859 A file listed in a package's <tt>conffiles</tt>
7860 file, and is treated specially by <prgn>dpkg</prgn>
7861 (see <ref id="configdetails">).
7867 The distinction between these two is important; they are
7868 not interchangeable concepts. Almost all
7869 <tt>conffile</tt>s are configuration files, but many
7870 configuration files are not <tt>conffiles</tt>.
7874 As noted elsewhere, <file>/etc/init.d</file> scripts,
7875 <file>/etc/default</file> files, scripts installed in
7876 <file>/etc/cron.{hourly,daily,weekly,monthly}</file>, and cron
7877 configuration installed in <file>/etc/cron.d</file> must be
7878 treated as configuration files. In general, any script that
7879 embeds configuration information is de-facto a configuration
7880 file and should be treated as such.
7885 <heading>Location</heading>
7888 Any configuration files created or used by your package
7889 must reside in <file>/etc</file>. If there are several,
7890 consider creating a subdirectory of <file>/etc</file>
7891 named after your package.
7895 If your package creates or uses configuration files
7896 outside of <file>/etc</file>, and it is not feasible to modify
7897 the package to use <file>/etc</file> directly, put the files
7898 in <file>/etc</file> and create symbolic links to those files
7899 from the location that the package requires.
7904 <heading>Behavior</heading>
7907 Configuration file handling must conform to the following
7909 <list compact="compact">
7911 local changes must be preserved during a package
7915 configuration files must be preserved when the
7916 package is removed, and only deleted when the
7920 Obsolete configuration files without local changes may be
7921 removed by the package during upgrade.
7925 The easy way to achieve this behavior is to make the
7926 configuration file a <tt>conffile</tt>. This is
7927 appropriate only if it is possible to distribute a default
7928 version that will work for most installations, although
7929 some system administrators may choose to modify it. This
7930 implies that the default version will be part of the
7931 package distribution, and must not be modified by the
7932 maintainer scripts during installation (or at any other
7937 In order to ensure that local changes are preserved
7938 correctly, no package may contain or make hard links to
7939 conffiles.<footnote>
7940 Rationale: There are two problems with hard links.
7941 The first is that some editors break the link while
7942 editing one of the files, so that the two files may
7943 unwittingly become unlinked and different. The second
7944 is that <prgn>dpkg</prgn> might break the hard link
7945 while upgrading <tt>conffile</tt>s.
7950 The other way to do it is via the maintainer scripts. In
7951 this case, the configuration file must not be listed as a
7952 <tt>conffile</tt> and must not be part of the package
7953 distribution. If the existence of a file is required for
7954 the package to be sensibly configured it is the
7955 responsibility of the package maintainer to provide
7956 maintainer scripts which correctly create, update and
7957 maintain the file and remove it on purge. (See <ref
7958 id="maintainerscripts"> for more information.) These
7959 scripts must be idempotent (i.e., must work correctly if
7960 <prgn>dpkg</prgn> needs to re-run them due to errors
7961 during installation or removal), must cope with all the
7962 variety of ways <prgn>dpkg</prgn> can call maintainer
7963 scripts, must not overwrite or otherwise mangle the user's
7964 configuration without asking, must not ask unnecessary
7965 questions (particularly during upgrades), and must
7966 otherwise be good citizens.
7970 The scripts are not required to configure every possible
7971 option for the package, but only those necessary to get
7972 the package running on a given system. Ideally the
7973 sysadmin should not have to do any configuration other
7974 than that done (semi-)automatically by the
7975 <prgn>postinst</prgn> script.
7979 A common practice is to create a script called
7980 <file><var>package</var>-configure</file> and have the
7981 package's <prgn>postinst</prgn> call it if and only if the
7982 configuration file does not already exist. In certain
7983 cases it is useful for there to be an example or template
7984 file which the maintainer scripts use. Such files should
7985 be in <file>/usr/share/<var>package</var></file> or
7986 <file>/usr/lib/<var>package</var></file> (depending on whether
7987 they are architecture-independent or not). There should
7988 be symbolic links to them from
7989 <file>/usr/share/doc/<var>package</var>/examples</file> if
7990 they are examples, and should be perfectly ordinary
7991 <prgn>dpkg</prgn>-handled files (<em>not</em>
7992 configuration files).
7996 These two styles of configuration file handling must
7997 not be mixed, for that way lies madness:
7998 <prgn>dpkg</prgn> will ask about overwriting the file
7999 every time the package is upgraded.
8004 <heading>Sharing configuration files</heading>
8007 Packages which specify the same file as a
8008 <tt>conffile</tt> must be tagged as <em>conflicting</em>
8009 with each other. (This is an instance of the general rule
8010 about not sharing files. Note that neither alternatives
8011 nor diversions are likely to be appropriate in this case;
8012 in particular, <prgn>dpkg</prgn> does not handle diverted
8013 <tt>conffile</tt>s well.)
8017 The maintainer scripts must not alter a <tt>conffile</tt>
8018 of <em>any</em> package, including the one the scripts
8023 If two or more packages use the same configuration file
8024 and it is reasonable for both to be installed at the same
8025 time, one of these packages must be defined as
8026 <em>owner</em> of the configuration file, i.e., it will be
8027 the package which handles that file as a configuration
8028 file. Other packages that use the configuration file must
8029 depend on the owning package if they require the
8030 configuration file to operate. If the other package will
8031 use the configuration file if present, but is capable of
8032 operating without it, no dependency need be declared.
8036 If it is desirable for two or more related packages to
8037 share a configuration file <em>and</em> for all of the
8038 related packages to be able to modify that configuration
8039 file, then the following should be done:
8040 <enumlist compact="compact">
8042 One of the related packages (the "owning" package)
8043 will manage the configuration file with maintainer
8044 scripts as described in the previous section.
8047 The owning package should also provide a program
8048 that the other packages may use to modify the
8052 The related packages must use the provided program
8053 to make any desired modifications to the
8054 configuration file. They should either depend on
8055 the core package to guarantee that the configuration
8056 modifier program is available or accept gracefully
8057 that they cannot modify the configuration file if it
8058 is not. (This is in addition to the fact that the
8059 configuration file may not even be present in the
8066 Sometimes it's appropriate to create a new package which
8067 provides the basic infrastructure for the other packages
8068 and which manages the shared configuration files. (The
8069 <tt>sgml-base</tt> package is a good example.)
8074 <heading>User configuration files ("dotfiles")</heading>
8077 The files in <file>/etc/skel</file> will automatically be
8078 copied into new user accounts by <prgn>adduser</prgn>.
8079 No other program should reference the files in
8080 <file>/etc/skel</file>.
8084 Therefore, if a program needs a dotfile to exist in
8085 advance in <file>$HOME</file> to work sensibly, that dotfile
8086 should be installed in <file>/etc/skel</file> and treated as a
8091 However, programs that require dotfiles in order to
8092 operate sensibly are a bad thing, unless they do create
8093 the dotfiles themselves automatically.
8097 Furthermore, programs should be configured by the Debian
8098 default installation to behave as closely to the upstream
8099 default behavior as possible.
8103 Therefore, if a program in a Debian package needs to be
8104 configured in some way in order to operate sensibly, that
8105 should be done using a site-wide configuration file placed
8106 in <file>/etc</file>. Only if the program doesn't support a
8107 site-wide default configuration and the package maintainer
8108 doesn't have time to add it may a default per-user file be
8109 placed in <file>/etc/skel</file>.
8113 <file>/etc/skel</file> should be as empty as we can make it.
8114 This is particularly true because there is no easy (or
8115 necessarily desirable) mechanism for ensuring that the
8116 appropriate dotfiles are copied into the accounts of
8117 existing users when a package is installed.
8123 <heading>Log files</heading>
8125 Log files should usually be named
8126 <file>/var/log/<var>package</var>.log</file>. If you have many
8127 log files, or need a separate directory for permission
8128 reasons (<file>/var/log</file> is writable only by
8129 <file>root</file>), you should usually create a directory named
8130 <file>/var/log/<var>package</var></file> and place your log
8135 Log files must be rotated occasionally so that they don't grow
8136 indefinitely. The best way to do this is to install a log
8137 rotation configuration file in the
8138 directory <file>/etc/logrotate.d</file>, normally
8139 named <file>/etc/logrotate.d/<var>package</var></file>, and use
8140 the facilities provided by <prgn>logrotate</prgn>.
8143 The traditional approach to log files has been to set up
8144 <em>ad hoc</em> log rotation schemes using simple shell
8145 scripts and cron. While this approach is highly
8146 customizable, it requires quite a lot of sysadmin work.
8147 Even though the original Debian system helped a little
8148 by automatically installing a system which can be used
8149 as a template, this was deemed not enough.
8153 The use of <prgn>logrotate</prgn>, a program developed
8154 by Red Hat, is better, as it centralizes log management.
8155 It has both a configuration file
8156 (<file>/etc/logrotate.conf</file>) and a directory where
8157 packages can drop their individual log rotation
8158 configurations (<file>/etc/logrotate.d</file>).
8161 Here is a good example for a logrotate config
8162 file (for more information see <manref name="logrotate"
8164 <example compact="compact">
8165 /var/log/foo/*.log {
8171 start-stop-daemon -K -p /var/run/foo.pid -s HUP -x /usr/sbin/foo -q
8175 This rotates all files under <file>/var/log/foo</file>, saves 12
8176 compressed generations, and tells the daemon to reopen its log
8177 files after the log rotation. It skips this log rotation
8178 (via <tt>missingok</tt>) if no such log file is present, which
8179 avoids errors if the package is removed but not purged.
8183 Log files should be removed when the package is
8184 purged (but not when it is only removed). This should be
8185 done by the <prgn>postrm</prgn> script when it is called
8186 with the argument <tt>purge</tt> (see <ref
8187 id="removedetails">).
8191 <sect id="permissions-owners">
8192 <heading>Permissions and owners</heading>
8195 The rules in this section are guidelines for general use.
8196 If necessary you may deviate from the details below.
8197 However, if you do so you must make sure that what is done
8198 is secure and you should try to be as consistent as possible
8199 with the rest of the system. You should probably also
8200 discuss it on <prgn>debian-devel</prgn> first.
8204 Files should be owned by <tt>root:root</tt>, and made
8205 writable only by the owner and universally readable (and
8206 executable, if appropriate), that is mode 644 or 755.
8210 Directories should be mode 755 or (for group-writability)
8211 mode 2775. The ownership of the directory should be
8212 consistent with its mode: if a directory is mode 2775, it
8213 should be owned by the group that needs write access to
8216 When a package is upgraded, and the owner or permissions
8217 of a file included in the package has changed, dpkg
8218 arranges for the ownership and permissions to be
8219 correctly set upon installation. However, this does not
8220 extend to directories; the permissions and ownership of
8221 directories already on the system does not change on
8222 install or upgrade of packages. This makes sense, since
8223 otherwise common directories like <tt>/usr</tt> would
8224 always be in flux. To correctly change permissions of a
8225 directory the package owns, explicit action is required,
8226 usually in the <tt>postinst</tt> script. Care must be
8227 taken to handle downgrades as well, in that case.
8233 Control information files should be owned by <tt>root:root</tt>
8234 and either mode 644 (for most files) or mode 755 (for
8235 executables such as <qref id="maintscripts">maintainer
8240 Setuid and setgid executables should be mode 4755 or 2755
8241 respectively, and owned by the appropriate user or group.
8242 They should not be made unreadable (modes like 4711 or
8243 2711 or even 4111); doing so achieves no extra security,
8244 because anyone can find the binary in the freely available
8245 Debian package; it is merely inconvenient. For the same
8246 reason you should not restrict read or execute permissions
8247 on non-set-id executables.
8251 Some setuid programs need to be restricted to particular
8252 sets of users, using file permissions. In this case they
8253 should be owned by the uid to which they are set-id, and by
8254 the group which should be allowed to execute them. They
8255 should have mode 4754; again there is no point in making
8256 them unreadable to those users who must not be allowed to
8261 It is possible to arrange that the system administrator can
8262 reconfigure the package to correspond to their local
8263 security policy by changing the permissions on a binary:
8264 they can do this by using <prgn>dpkg-statoverride</prgn>, as
8265 described below.<footnote>
8266 Ordinary files installed by <prgn>dpkg</prgn> (as
8267 opposed to <tt>conffile</tt>s and other similar objects)
8268 normally have their permissions reset to the distributed
8269 permissions when the package is reinstalled. However,
8270 the use of <prgn>dpkg-statoverride</prgn> overrides this
8273 Another method you should consider is to create a group for
8274 people allowed to use the program(s) and make any setuid
8275 executables executable only by that group.
8279 If you need to create a new user or group for your package
8280 there are two possibilities. Firstly, you may need to
8281 make some files in the binary package be owned by this
8282 user or group, or you may need to compile the user or
8283 group id (rather than just the name) into the binary
8284 (though this latter should be avoided if possible, as in
8285 this case you need a statically allocated id).</p>
8288 If you need a statically allocated id, you must ask for a
8289 user or group id from the <tt>base-passwd</tt> maintainer,
8290 and must not release the package until you have been
8291 allocated one. Once you have been allocated one you must
8292 either make the package depend on a version of the
8293 <tt>base-passwd</tt> package with the id present in
8294 <file>/etc/passwd</file> or <file>/etc/group</file>, or arrange for
8295 your package to create the user or group itself with the
8296 correct id (using <tt>adduser</tt>) in its
8297 <prgn>preinst</prgn> or <prgn>postinst</prgn>. (Doing it in
8298 the <prgn>postinst</prgn> is to be preferred if it is
8299 possible, otherwise a pre-dependency will be needed on the
8300 <tt>adduser</tt> package.)
8304 On the other hand, the program might be able to determine
8305 the uid or gid from the user or group name at runtime, so
8306 that a dynamically allocated id can be used. In this case
8307 you should choose an appropriate user or group name,
8308 discussing this on <prgn>debian-devel</prgn> and checking
8309 with the <package/base-passwd/ maintainer that it is unique and that
8310 they do not wish you to use a statically allocated id
8311 instead. When this has been checked you must arrange for
8312 your package to create the user or group if necessary using
8313 <prgn>adduser</prgn> in the <prgn>preinst</prgn> or
8314 <prgn>postinst</prgn> script (again, the latter is to be
8315 preferred if it is possible).
8319 Note that changing the numeric value of an id associated
8320 with a name is very difficult, and involves searching the
8321 file system for all appropriate files. You need to think
8322 carefully whether a static or dynamic id is required, since
8323 changing your mind later will cause problems.
8326 <sect1><heading>The use of <prgn>dpkg-statoverride</prgn></heading>
8328 This section is not intended as policy, but as a
8329 description of the use of <prgn>dpkg-statoverride</prgn>.
8333 If a system administrator wishes to have a file (or
8334 directory or other such thing) installed with owner and
8335 permissions different from those in the distributed Debian
8336 package, they can use the <prgn>dpkg-statoverride</prgn>
8337 program to instruct <prgn>dpkg</prgn> to use the different
8338 settings every time the file is installed. Thus the
8339 package maintainer should distribute the files with their
8340 normal permissions, and leave it for the system
8341 administrator to make any desired changes. For example, a
8342 daemon which is normally required to be setuid root, but
8343 in certain situations could be used without being setuid,
8344 should be installed setuid in the <tt>.deb</tt>. Then the
8345 local system administrator can change this if they wish.
8346 If there are two standard ways of doing it, the package
8347 maintainer can use <tt>debconf</tt> to find out the
8348 preference, and call <prgn>dpkg-statoverride</prgn> in the
8349 maintainer script if necessary to accommodate the system
8350 administrator's choice. Care must be taken during
8351 upgrades to not override an existing setting.
8355 Given the above, <prgn>dpkg-statoverride</prgn> is
8356 essentially a tool for system administrators and would not
8357 normally be needed in the maintainer scripts. There is
8358 one type of situation, though, where calls to
8359 <prgn>dpkg-statoverride</prgn> would be needed in the
8360 maintainer scripts, and that involves packages which use
8361 dynamically allocated user or group ids. In such a
8362 situation, something like the following idiom can be very
8363 helpful in the package's <prgn>postinst</prgn>, where
8364 <tt>sysuser</tt> is a dynamically allocated id:
8366 for i in /usr/bin/foo /usr/sbin/bar
8368 # only do something when no setting exists
8369 if ! dpkg-statoverride --list $i >/dev/null 2>&1
8371 #include: debconf processing, question about foo and bar
8372 if [ "$RET" = "true" ] ; then
8373 dpkg-statoverride --update --add sysuser root 4755 $i
8378 The corresponding code to remove the override when the package
8381 for i in /usr/bin/foo /usr/sbin/bar
8383 if dpkg-statoverride --list $i >/dev/null 2>&1
8385 dpkg-statoverride --remove $i
8395 <chapt id="customized-programs">
8396 <heading>Customized programs</heading>
8398 <sect id="arch-spec">
8399 <heading>Architecture specification strings</heading>
8402 If a program needs to specify an <em>architecture specification
8403 string</em> in some place, it should select one of the strings
8404 provided by <tt>dpkg-architecture -L</tt>. The strings are in
8405 the format <tt><var>os</var>-<var>arch</var></tt>, though the OS
8406 part is sometimes elided, as when the OS is Linux.
8410 Note that we don't want to use
8411 <tt><var>arch</var>-debian-linux</tt> to apply to the rule
8412 <tt><var>architecture</var>-<var>vendor</var>-<var>os</var></tt>
8413 since this would make our programs incompatible with other
8414 Linux distributions. We also don't use something like
8415 <tt><var>arch</var>-unknown-linux</tt>, since the
8416 <tt>unknown</tt> does not look very good.
8419 <sect1 id="arch-wildcard-spec">
8420 <heading>Architecture wildcards</heading>
8423 A package may specify an architecture wildcard. Architecture
8424 wildcards are in the format <tt>any</tt> (which matches every
8425 architecture), <tt><var>os</var></tt>-any, or
8426 any-<tt><var>cpu</var></tt>. <footnote>
8427 Internally, the package system normalizes the GNU triplets
8428 and the Debian arches into Debian arch triplets (which are
8429 kind of inverted GNU triplets), with the first component of
8430 the triplet representing the libc and ABI in use, and then
8431 does matching against those triplets. However, such
8432 triplets are an internal implementation detail that should
8433 not be used by packages directly. The libc and ABI portion
8434 is handled internally by the package system based on
8435 the <var>os</var> and <var>cpu</var>.
8442 <heading>Daemons</heading>
8445 The configuration files <file>/etc/services</file>,
8446 <file>/etc/protocols</file>, and <file>/etc/rpc</file> are managed
8447 by the <prgn>netbase</prgn> package and must not be modified
8452 If a package requires a new entry in one of these files, the
8453 maintainer should get in contact with the
8454 <prgn>netbase</prgn> maintainer, who will add the entries
8455 and release a new version of the <prgn>netbase</prgn>
8460 The configuration file <file>/etc/inetd.conf</file> must not be
8461 modified by the package's scripts except via the
8462 <prgn>update-inetd</prgn> script or the
8463 <file>DebianNet.pm</file> Perl module. See their documentation
8464 for details on how to add entries.
8468 If a package wants to install an example entry into
8469 <file>/etc/inetd.conf</file>, the entry must be preceded with
8470 exactly one hash character (<tt>#</tt>). Such lines are
8471 treated as "commented out by user" by the
8472 <prgn>update-inetd</prgn> script and are not changed or
8473 activated during package updates.
8478 <heading>Using pseudo-ttys and modifying wtmp, utmp and
8482 Some programs need to create pseudo-ttys. This should be done
8483 using Unix98 ptys if the C library supports it. The resulting
8484 program must not be installed setuid root, unless that
8485 is required for other functionality.
8489 The files <file>/var/run/utmp</file>, <file>/var/log/wtmp</file> and
8490 <file>/var/log/lastlog</file> must be installed writable by
8491 group <tt>utmp</tt>. Programs which need to modify those
8492 files must be installed setgid <tt>utmp</tt>.
8497 <heading>Editors and pagers</heading>
8500 Some programs have the ability to launch an editor or pager
8501 program to edit or display a text document. Since there are
8502 lots of different editors and pagers available in the Debian
8503 distribution, the system administrator and each user should
8504 have the possibility to choose their preferred editor and
8509 In addition, every program should choose a good default
8510 editor/pager if none is selected by the user or system
8515 Thus, every program that launches an editor or pager must
8516 use the EDITOR or PAGER environment variable to determine
8517 the editor or pager the user wishes to use. If these
8518 variables are not set, the programs <file>/usr/bin/editor</file>
8519 and <file>/usr/bin/pager</file> should be used, respectively.
8523 These two files are managed through the <prgn>dpkg</prgn>
8524 "alternatives" mechanism. Every package providing an editor or
8525 pager must call the <prgn>update-alternatives</prgn> script to
8526 register as an alternative for <file>/usr/bin/editor</file>
8527 or <file>/usr/bin/pager</file> as appropriate. The alternative
8528 should have a slave alternative
8529 for <file>/usr/share/man/man1/editor.1.gz</file>
8530 or <file>/usr/share/man/man1/pager.1.gz</file> pointing to the
8531 corresponding manual page.
8535 If it is very hard to adapt a program to make use of the
8536 EDITOR or PAGER variables, that program may be configured to
8537 use <file>/usr/bin/sensible-editor</file> and
8538 <file>/usr/bin/sensible-pager</file> as the editor or pager
8539 program respectively. These are two scripts provided in the
8540 <package>sensible-utils</package> package that check the EDITOR
8541 and PAGER variables and launch the appropriate program, and fall
8542 back to <file>/usr/bin/editor</file>
8543 and <file>/usr/bin/pager</file> if the variable is not set.
8547 A program may also use the VISUAL environment variable to
8548 determine the user's choice of editor. If it exists, it
8549 should take precedence over EDITOR. This is in fact what
8550 <file>/usr/bin/sensible-editor</file> does.
8554 It is not required for a package to depend on
8555 <tt>editor</tt> and <tt>pager</tt>, nor is it required for a
8556 package to provide such virtual packages.<footnote>
8557 The Debian base system already provides an editor and a
8563 <sect id="web-appl">
8564 <heading>Web servers and applications</heading>
8567 This section describes the locations and URLs that should
8568 be used by all web servers and web applications in the
8575 Cgi-bin executable files are installed in the
8577 <example compact="compact">
8578 /usr/lib/cgi-bin/<var>cgi-bin-name</var>
8580 or a subdirectory of that directory, and should be
8582 <example compact="compact">
8583 http://localhost/cgi-bin/<var>cgi-bin-name</var>
8585 (possibly with a subdirectory name
8586 before <var>cgi-bin-name</var>).
8590 <p>Access to HTML documents</p>
8593 HTML documents for a package are stored in
8594 <file>/usr/share/doc/<var>package</var></file>
8595 and can be referred to as
8596 <example compact="compact">
8597 http://localhost/doc/<var>package</var>/<var>filename</var>
8602 The web server should restrict access to the document
8603 tree so that only clients on the same host can read
8604 the documents. If the web server does not support such
8605 access controls, then it should not provide access at
8606 all, or ask about providing access during installation.
8611 <p>Access to images</p>
8613 It is recommended that images for a package be stored
8614 in <tt>/usr/share/images/<var>package</var></tt> and
8615 may be referred to through an alias <tt>/images/</tt>
8618 http://localhost/images/<package>/<filename>
8625 <p>Web Document Root</p>
8628 Web Applications should try to avoid storing files in
8629 the Web Document Root. Instead they should use the
8630 /usr/share/doc/<var>package</var> directory for
8631 documents and register the Web Application via the
8632 <package>doc-base</package> package. If access to the
8633 web document root is unavoidable then use
8634 <example compact="compact">
8637 as the Document Root. This might be just a symbolic
8638 link to the location where the system administrator
8639 has put the real document root.
8642 <item><p>Providing httpd and/or httpd-cgi</p>
8644 All web servers should provide the virtual package
8645 <tt>httpd</tt>. If a web server has CGI support it should
8646 provide <tt>httpd-cgi</tt> additionally.
8649 All web applications which do not contain CGI scripts should
8650 depend on <tt>httpd</tt>, all those web applications which
8651 <tt>do</tt> contain CGI scripts, should depend on
8659 <sect id="mail-transport-agents">
8660 <heading>Mail transport, delivery and user agents</heading>
8663 Debian packages which process electronic mail, whether mail
8664 user agents (MUAs) or mail transport agents (MTAs), must
8665 ensure that they are compatible with the configuration
8666 decisions below. Failure to do this may result in lost
8667 mail, broken <tt>From:</tt> lines, and other serious brain
8672 The mail spool is <file>/var/mail</file> and the interface to
8673 send a mail message is <file>/usr/sbin/sendmail</file> (as per
8674 the FHS). On older systems, the mail spool may be
8675 physically located in <file>/var/spool/mail</file>, but all
8676 access to the mail spool should be via the
8677 <file>/var/mail</file> symlink. The mail spool is part of the
8678 base system and not part of the MTA package.
8682 All Debian MUAs, MTAs, MDAs and other mailbox accessing
8683 programs (such as IMAP daemons) must lock the mailbox in an
8684 NFS-safe way. This means that <tt>fcntl()</tt> locking must
8685 be combined with dot locking. To avoid deadlocks, a program
8686 should use <tt>fcntl()</tt> first and dot locking after
8687 this, or alternatively implement the two locking methods in
8688 a non blocking way<footnote>
8689 If it is not possible to establish both locks, the
8690 system shouldn't wait for the second lock to be
8691 established, but remove the first lock, wait a (random)
8692 time, and start over locking again.
8693 </footnote>. Using the functions <tt>maillock</tt> and
8694 <tt>mailunlock</tt> provided by the
8695 <tt>liblockfile*</tt><footnote>
8696 You will need to depend on <tt>liblockfile1 (>>1.01)</tt>
8697 to use these functions.
8698 </footnote> packages is the recommended way to realize this.
8702 Mailboxes are generally either mode 600 and owned by
8703 <var>user</var> or mode 660 and owned by
8704 <tt><var>user</var>:mail</tt><footnote>
8705 There are two traditional permission schemes for mail spools:
8706 mode 600 with all mail delivery done by processes running as
8707 the destination user, or mode 660 and owned by group mail with
8708 mail delivery done by a process running as a system user in
8709 group mail. Historically, Debian required mode 660 mail
8710 spools to enable the latter model, but that model has become
8711 increasingly uncommon and the principle of least privilege
8712 indicates that mail systems that use the first model should
8713 use permissions of 600. If delivery to programs is permitted,
8714 it's easier to keep the mail system secure if the delivery
8715 agent runs as the destination user. Debian Policy therefore
8716 permits either scheme.
8717 </footnote>. The local system administrator may choose a
8718 different permission scheme; packages should not make
8719 assumptions about the permission and ownership of mailboxes
8720 unless required (such as when creating a new mailbox). A MUA
8721 may remove a mailbox (unless it has nonstandard permissions) in
8722 which case the MTA or another MUA must recreate it if needed.
8726 The mail spool is 2775 <tt>root:mail</tt>, and MUAs should
8727 be setgid mail to do the locking mentioned above (and
8728 must obviously avoid accessing other users' mailboxes
8729 using this privilege).</p>
8732 <file>/etc/aliases</file> is the source file for the system mail
8733 aliases (e.g., postmaster, usenet, etc.), it is the one
8734 which the sysadmin and <prgn>postinst</prgn> scripts may
8735 edit. After <file>/etc/aliases</file> is edited the program or
8736 human editing it must call <prgn>newaliases</prgn>. All MTA
8737 packages must come with a <prgn>newaliases</prgn> program,
8738 even if it does nothing, but older MTA packages did not do
8739 this so programs should not fail if <prgn>newaliases</prgn>
8740 cannot be found. Note that because of this, all MTA
8741 packages must have <tt>Provides</tt>, <tt>Conflicts</tt> and
8742 <tt>Replaces: mail-transport-agent</tt> control fields.
8746 The convention of writing <tt>forward to
8747 <var>address</var></tt> in the mailbox itself is not
8748 supported. Use a <tt>.forward</tt> file instead.</p>
8751 The <prgn>rmail</prgn> program used by UUCP
8752 for incoming mail should be <file>/usr/sbin/rmail</file>.
8753 Likewise, <prgn>rsmtp</prgn>, for receiving
8754 batch-SMTP-over-UUCP, should be <file>/usr/sbin/rsmtp</file> if it
8758 If your package needs to know what hostname to use on (for
8759 example) outgoing news and mail messages which are generated
8760 locally, you should use the file <file>/etc/mailname</file>. It
8761 will contain the portion after the username and <tt>@</tt>
8762 (at) sign for email addresses of users on the machine
8763 (followed by a newline).
8767 Such a package should check for the existence of this file
8768 when it is being configured. If it exists, it should be
8769 used without comment, although an MTA's configuration script
8770 may wish to prompt the user even if it finds that this file
8771 exists. If the file does not exist, the package should
8772 prompt the user for the value (preferably using
8773 <prgn>debconf</prgn>) and store it in <file>/etc/mailname</file>
8774 as well as using it in the package's configuration. The
8775 prompt should make it clear that the name will not just be
8776 used by that package. For example, in this situation the
8777 <tt>inn</tt> package could say something like:
8778 <example compact="compact">
8779 Please enter the "mail name" of your system. This is the
8780 hostname portion of the address to be shown on outgoing
8781 news and mail messages. The default is
8782 <var>syshostname</var>, your system's host name. Mail
8783 name ["<var>syshostname</var>"]:
8785 where <var>syshostname</var> is the output of <tt>hostname
8791 <heading>News system configuration</heading>
8794 All the configuration files related to the NNTP (news)
8795 servers and clients should be located under
8796 <file>/etc/news</file>.</p>
8799 There are some configuration issues that apply to a number
8800 of news clients and server packages on the machine. These
8804 <tag><file>/etc/news/organization</file></tag>
8806 A string which should appear as the
8807 organization header for all messages posted
8808 by NNTP clients on the machine
8811 <tag><file>/etc/news/server</file></tag>
8813 Contains the FQDN of the upstream NNTP
8814 server, or localhost if the local machine is
8819 Other global files may be added as required for cross-package news
8826 <heading>Programs for the X Window System</heading>
8829 <heading>Providing X support and package priorities</heading>
8832 Programs that can be configured with support for the X
8833 Window System must be configured to do so and must declare
8834 any package dependencies necessary to satisfy their
8835 runtime requirements when using the X Window System. If
8836 such a package is of higher priority than the X packages
8837 on which it depends, it is required that either the
8838 X-specific components be split into a separate package, or
8839 that an alternative version of the package, which includes
8840 X support, be provided, or that the package's priority be
8846 <heading>Packages providing an X server</heading>
8849 Packages that provide an X server that, directly or
8850 indirectly, communicates with real input and display
8851 hardware should declare in their <tt>Provides</tt> control
8852 field that they provide the virtual
8853 package <tt>xserver</tt>.<footnote>
8854 This implements current practice, and provides an
8855 actual policy for usage of the <tt>xserver</tt>
8856 virtual package which appears in the virtual packages
8857 list. In a nutshell, X servers that interface
8858 directly with the display and input hardware or via
8859 another subsystem (e.g., GGI) should provide
8860 <tt>xserver</tt>. Things like <tt>Xvfb</tt>,
8861 <tt>Xnest</tt>, and <tt>Xprt</tt> should not.
8867 <heading>Packages providing a terminal emulator</heading>
8870 Packages that provide a terminal emulator for the X Window
8871 System which meet the criteria listed below should declare in
8872 their <tt>Provides</tt> control field that they provide the
8873 virtual package <tt>x-terminal-emulator</tt>. They should
8874 also register themselves as an alternative for
8875 <file>/usr/bin/x-terminal-emulator</file>, with a priority of
8876 20. That alternative should have a slave alternative
8877 for <file>/usr/share/man/man1/x-terminal-emulator.1.gz</file>
8878 pointing to the corresponding manual page.
8882 To be an <tt>x-terminal-emulator</tt>, a program must:
8883 <list compact="compact">
8885 Be able to emulate a DEC VT100 terminal, or a
8886 compatible terminal.
8890 Support the command-line option <tt>-e
8891 <var>command</var></tt>, which creates a new
8892 terminal window<footnote>
8893 "New terminal window" does not necessarily mean
8894 a new top-level X window directly parented by
8895 the window manager; it could, if the terminal
8896 emulator application were so coded, be a new
8897 "view" in a multiple-document interface (MDI).
8899 and runs the specified <var>command</var>,
8900 interpreting the entirety of the rest of the command
8901 line as a command to pass straight to exec, in the
8902 manner that <tt>xterm</tt> does.
8906 Support the command-line option <tt>-T
8907 <var>title</var></tt>, which creates a new terminal
8908 window with the window title <var>title</var>.
8915 <heading>Packages providing a window manager</heading>
8918 Packages that provide a window manager should declare in
8919 their <tt>Provides</tt> control field that they provide the
8920 virtual package <tt>x-window-manager</tt>. They should also
8921 register themselves as an alternative for
8922 <file>/usr/bin/x-window-manager</file>, with a priority
8923 calculated as follows:
8924 <list compact="compact">
8926 Start with a priority of 20.
8930 If the window manager supports the Debian menu
8931 system, add 20 points if this support is available
8932 in the package's default configuration (i.e., no
8933 configuration files belonging to the system or user
8934 have to be edited to activate the feature); if
8935 configuration files must be modified, add only 10
8941 If the window manager complies with <url
8942 id="http://www.freedesktop.org/Standards/wm-spec"
8943 name="The Window Manager Specification Project">,
8944 written by the <url id="http://www.freedesktop.org/"
8945 name="Free Desktop Group">, add 40 points.
8949 If the window manager permits the X session to be
8950 restarted using a <em>different</em> window manager
8951 (without killing the X server) in its default
8952 configuration, add 10 points; otherwise add none.
8955 That alternative should have a slave alternative
8956 for <file>/usr/share/man/man1/x-window-manager.1.gz</file>
8957 pointing to the corresponding manual page.
8962 <heading>Packages providing fonts</heading>
8965 Packages that provide fonts for the X Window
8967 For the purposes of Debian Policy, a "font for the X
8968 Window System" is one which is accessed via X protocol
8969 requests. Fonts for the Linux console, for PostScript
8970 renderer, or any other purpose, do not fit this
8971 definition. Any tool which makes such fonts available
8972 to the X Window System, however, must abide by this
8975 must do a number of things to ensure that they are both
8976 available without modification of the X or font server
8977 configuration, and that they do not corrupt files used by
8978 other font packages to register information about
8982 Fonts of any type supported by the X Window System
8983 must be in a separate binary package from any
8984 executables, libraries, or documentation (except
8985 that specific to the fonts shipped, such as their
8986 license information). If one or more of the fonts
8987 so packaged are necessary for proper operation of
8988 the package with which they are associated the font
8989 package may be Recommended; if the fonts merely
8990 provide an enhancement, a Suggests relationship may
8991 be used. Packages must not Depend on font
8993 This is because the X server may retrieve fonts
8994 from the local file system or over the network
8995 from an X font server; the Debian package system
8996 is empowered to deal only with the local
9002 BDF fonts must be converted to PCF fonts with the
9003 <prgn>bdftopcf</prgn> utility (available in the
9004 <tt>xfonts-utils</tt> package, <prgn>gzip</prgn>ped, and
9005 placed in a directory that corresponds to their
9007 <list compact="compact">
9009 100 dpi fonts must be placed in
9010 <file>/usr/share/fonts/X11/100dpi/</file>.
9014 75 dpi fonts must be placed in
9015 <file>/usr/share/fonts/X11/75dpi/</file>.
9019 Character-cell fonts, cursor fonts, and other
9020 low-resolution fonts must be placed in
9021 <file>/usr/share/fonts/X11/misc/</file>.
9027 Type 1 fonts must be placed in
9028 <file>/usr/share/fonts/X11/Type1/</file>. If font
9029 metric files are available, they must be placed here
9034 Subdirectories of <file>/usr/share/fonts/X11/</file>
9035 other than those listed above must be neither
9036 created nor used. (The <file>PEX</file>, <file>CID</file>,
9037 <file>Speedo</file>, and <file>cyrillic</file> directories
9038 are excepted for historical reasons, but installation of
9039 files into these directories remains discouraged.)
9043 Font packages may, instead of placing files directly
9044 in the X font directories listed above, provide
9045 symbolic links in that font directory pointing to
9046 the files' actual location in the filesystem. Such
9047 a location must comply with the FHS.
9051 Font packages should not contain both 75dpi and
9052 100dpi versions of a font. If both are available,
9053 they should be provided in separate binary packages
9054 with <tt>-75dpi</tt> or <tt>-100dpi</tt> appended to
9055 the names of the packages containing the
9056 corresponding fonts.
9060 Fonts destined for the <file>misc</file> subdirectory
9061 should not be included in the same package as 75dpi
9062 or 100dpi fonts; instead, they should be provided in
9063 a separate package with <tt>-misc</tt> appended to
9068 Font packages must not provide the files
9069 <file>fonts.dir</file>, <file>fonts.alias</file>, or
9070 <file>fonts.scale</file> in a font directory:
9073 <file>fonts.dir</file> files must not be provided at all.
9077 <file>fonts.alias</file> and <file>fonts.scale</file>
9078 files, if needed, should be provided in the
9080 <file>/etc/X11/fonts/<var>fontdir</var>/<var>package</var>.<var>extension</var></file>,
9081 where <var>fontdir</var> is the name of the
9083 <file>/usr/share/fonts/X11/</file> where the
9084 package's corresponding fonts are stored
9085 (e.g., <tt>75dpi</tt> or <tt>misc</tt>),
9086 <var>package</var> is the name of the package
9087 that provides these fonts, and
9088 <var>extension</var> is either <tt>scale</tt>
9089 or <tt>alias</tt>, whichever corresponds to
9096 Font packages must declare a dependency on
9097 <tt>xfonts-utils</tt> in their <tt>Depends</tt>
9098 or <tt>Pre-Depends</tt> control field.
9102 Font packages that provide one or more
9103 <file>fonts.scale</file> files as described above must
9104 invoke <prgn>update-fonts-scale</prgn> on each
9105 directory into which they installed fonts
9106 <em>before</em> invoking
9107 <prgn>update-fonts-dir</prgn> on that directory.
9108 This invocation must occur in both the
9109 <prgn>postinst</prgn> (for all arguments) and
9110 <prgn>postrm</prgn> (for all arguments except
9111 <tt>upgrade</tt>) scripts.
9115 Font packages that provide one or more
9116 <file>fonts.alias</file> files as described above must
9117 invoke <prgn>update-fonts-alias</prgn> on each
9118 directory into which they installed fonts. This
9119 invocation must occur in both the
9120 <prgn>postinst</prgn> (for all arguments) and
9121 <prgn>postrm</prgn> (for all arguments except
9122 <tt>upgrade</tt>) scripts.
9126 Font packages must invoke
9127 <prgn>update-fonts-dir</prgn> on each directory into
9128 which they installed fonts. This invocation must
9129 occur in both the <prgn>postinst</prgn> (for all
9130 arguments) and <prgn>postrm</prgn> (for all
9131 arguments except <tt>upgrade</tt>) scripts.
9135 Font packages must not provide alias names for the
9136 fonts they include which collide with alias names
9137 already in use by fonts already packaged.
9141 Font packages must not provide fonts with the same
9142 XLFD registry name as another font already packaged.
9148 <sect1 id="appdefaults">
9149 <heading>Application defaults files</heading>
9152 Application defaults files must be installed in the
9153 directory <file>/etc/X11/app-defaults/</file> (use of a
9154 localized subdirectory of <file>/etc/X11/</file> as described
9155 in the <em>X Toolkit Intrinsics - C Language
9156 Interface</em> manual is also permitted). They must be
9157 registered as <tt>conffile</tt>s or handled as
9158 configuration files.
9162 Customization of programs' X resources may also be
9163 supported with the provision of a file with the same name
9164 as that of the package placed in
9165 the <file>/etc/X11/Xresources/</file> directory, which
9166 must be registered as a <tt>conffile</tt> or handled as a
9167 configuration file.<footnote>
9168 Note that this mechanism is not the same as using
9169 app-defaults; app-defaults are tied to the client
9170 binary on the local file system, whereas X resources
9171 are stored in the X server and affect all connecting
9178 <heading>Installation directory issues</heading>
9181 Historically, packages using the X Window System used a
9182 separate set of installation directories from other packages.
9183 This practice has been discontinued and packages using the X
9184 Window System should now generally be installed in the same
9185 directories as any other package. Specifically, packages must
9186 not install files under the <file>/usr/X11R6/</file> directory
9187 and the <file>/usr/X11R6/</file> directory hierarchy should be
9188 regarded as obsolete.
9192 Include files previously installed under
9193 <file>/usr/X11R6/include/X11/</file> should be installed into
9194 <file>/usr/include/X11/</file>. For files previously
9195 installed into subdirectories of
9196 <file>/usr/X11R6/lib/X11/</file>, package maintainers should
9197 determine if subdirectories of <file>/usr/lib/</file> and
9198 <file>/usr/share/</file> can be used. If not, a subdirectory
9199 of <file>/usr/lib/X11/</file> should be used.
9203 Configuration files for window, display, or session managers
9204 or other applications that are tightly integrated with the X
9205 Window System may be placed in a subdirectory
9206 of <file>/etc/X11/</file> corresponding to the package name.
9207 Other X Window System applications should use
9208 the <file>/etc/</file> directory unless otherwise mandated by
9209 policy (such as for <ref id="appdefaults">).
9214 <heading>The OSF/Motif and OpenMotif libraries</heading>
9217 <em>Programs that require the non-DFSG-compliant OSF/Motif or
9218 OpenMotif libraries</em><footnote>
9219 OSF/Motif and OpenMotif are collectively referred to as
9220 "Motif" in this policy document.
9222 should be compiled against and tested with LessTif (a free
9223 re-implementation of Motif) instead. If the maintainer
9224 judges that the program or programs do not work
9225 sufficiently well with LessTif to be distributed and
9226 supported, but do so when compiled against Motif, then two
9227 versions of the package should be created; one linked
9228 statically against Motif and with <tt>-smotif</tt>
9229 appended to the package name, and one linked dynamically
9230 against Motif and with <tt>-dmotif</tt> appended to the
9235 Both Motif-linked versions are dependent
9236 upon non-DFSG-compliant software and thus cannot be
9237 uploaded to the <em>main</em> distribution; if the
9238 software is itself DFSG-compliant it may be uploaded to
9239 the <em>contrib</em> distribution. While known existing
9240 versions of Motif permit unlimited redistribution of
9241 binaries linked against the library (whether statically or
9242 dynamically), it is the package maintainer's
9243 responsibility to determine whether this is permitted by
9244 the license of the copy of Motif in their possession.
9250 <heading>Perl programs and modules</heading>
9253 Perl programs and modules should follow the current Perl policy.
9257 The Perl policy can be found in the <tt>perl-policy</tt>
9258 files in the <tt>debian-policy</tt> package.
9259 It is also available from the Debian web mirrors at
9260 <tt><url name="/doc/packaging-manuals/perl-policy/"
9261 id="http://www.debian.org/doc/packaging-manuals/perl-policy/"></tt>.
9266 <heading>Emacs lisp programs</heading>
9269 Please refer to the "Debian Emacs Policy" for details of how to
9270 package emacs lisp programs.
9274 The Emacs policy is available in
9275 <file>debian-emacs-policy.gz</file> of the
9276 <package>emacsen-common</package> package.
9277 It is also available from the Debian web mirrors at
9278 <tt><url name="/doc/packaging-manuals/debian-emacs-policy"
9279 id="http://www.debian.org/doc/packaging-manuals/debian-emacs-policy"></tt>.
9284 <heading>Games</heading>
9287 The permissions on <file>/var/games</file> are mode 755, owner
9288 <tt>root</tt> and group <tt>root</tt>.
9292 Each game decides on its own security policy.</p>
9295 Games which require protected, privileged access to
9296 high-score files, saved games, etc., may be made
9297 set-<em>group</em>-id (mode 2755) and owned by
9298 <tt>root:games</tt>, and use files and directories with
9299 appropriate permissions (770 <tt>root:games</tt>, for
9300 example). They must not be made
9301 set-<em>user</em>-id, as this causes security problems. (If
9302 an attacker can subvert any set-user-id game they can
9303 overwrite the executable of any other, causing other players
9304 of these games to run a Trojan horse program. With a
9305 set-group-id game the attacker only gets access to less
9306 important game data, and if they can get at the other
9307 players' accounts at all it will take considerably more
9311 Some packages, for example some fortune cookie programs, are
9312 configured by the upstream authors to install with their
9313 data files or other static information made unreadable so
9314 that they can only be accessed through set-id programs
9315 provided. You should not do this in a Debian package: anyone can
9316 download the <file>.deb</file> file and read the data from it,
9317 so there is no point making the files unreadable. Not
9318 making the files unreadable also means that you don't have
9319 to make so many programs set-id, which reduces the risk of a
9323 As described in the FHS, binaries of games should be
9324 installed in the directory <file>/usr/games</file>. This also
9325 applies to games that use the X Window System. Manual pages
9326 for games (X and non-X games) should be installed in
9327 <file>/usr/share/man/man6</file>.</p>
9333 <heading>Documentation</heading>
9336 <heading>Manual pages</heading>
9339 You should install manual pages in <prgn>nroff</prgn> source
9340 form, in appropriate places under <file>/usr/share/man</file>.
9341 You should only use sections 1 to 9 (see the FHS for more
9342 details). You must not install a pre-formatted "cat page".
9346 Each program, utility, and function should have an
9347 associated manual page included in the same package. It is
9348 suggested that all configuration files also have a manual
9349 page included as well. Manual pages for protocols and other
9350 auxiliary things are optional.
9354 If no manual page is available, this is considered as a bug
9355 and should be reported to the Debian Bug Tracking System (the
9356 maintainer of the package is allowed to write this bug report
9357 themselves, if they so desire). Do not close the bug report
9358 until a proper man page is available.<footnote>
9359 It is not very hard to write a man page. See the
9360 <url id="http://www.schweikhardt.net/man_page_howto.html"
9361 name="Man-Page-HOWTO">,
9362 <manref name="man" section="7">, the examples
9363 created by <prgn>debmake</prgn> or <prgn>dh_make</prgn>,
9364 the helper program <prgn>help2man</prgn>, or the
9365 directory <file>/usr/share/doc/man-db/examples</file>.
9370 You may forward a complaint about a missing man page to the
9371 upstream authors, and mark the bug as forwarded in the
9372 Debian bug tracking system. Even though the GNU Project do
9373 not in general consider the lack of a man page to be a bug,
9374 we do; if they tell you that they don't consider it a bug
9375 you should leave the bug in our bug tracking system open
9380 Manual pages should be installed compressed using <tt>gzip -9</tt>.
9384 If one man page needs to be accessible via several names it
9385 is better to use a symbolic link than the <file>.so</file>
9386 feature, but there is no need to fiddle with the relevant
9387 parts of the upstream source to change from <file>.so</file> to
9388 symlinks: don't do it unless it's easy. You should not
9389 create hard links in the manual page directories, nor put
9390 absolute filenames in <file>.so</file> directives. The filename
9391 in a <file>.so</file> in a man page should be relative to the
9392 base of the man page tree (usually
9393 <file>/usr/share/man</file>). If you do not create any links
9394 (whether symlinks, hard links, or <tt>.so</tt> directives)
9395 in the file system to the alternate names of the man page,
9396 then you should not rely on <prgn>man</prgn> finding your
9397 man page under those names based solely on the information in
9398 the man page's header.<footnote>
9399 Supporting this in <prgn>man</prgn> often requires
9400 unreasonable processing time to find a manual page or to
9401 report that none exists, and moves knowledge into man's
9402 database that would be better left in the file system.
9403 This support is therefore deprecated and will cease to
9404 be present in the future.
9409 Manual pages in locale-specific subdirectories of
9410 <file>/usr/share/man</file> should use either UTF-8 or the usual
9411 legacy encoding for that language (normally the one corresponding
9412 to the shortest relevant locale name in
9413 <file>/usr/share/i18n/SUPPORTED</file>). For example, pages under
9414 <file>/usr/share/man/fr</file> should use either UTF-8 or
9415 ISO-8859-1.<footnote>
9416 <prgn>man</prgn> will automatically detect whether UTF-8 is in
9417 use. In future, all manual pages will be required to use
9423 A country name (the <tt>DE</tt> in <tt>de_DE</tt>) should not be
9424 included in the subdirectory name unless it indicates a
9425 significant difference in the language, as this excludes
9426 speakers of the language in other countries.<footnote>
9427 At the time of writing, Chinese and Portuguese are the main
9428 languages with such differences, so <file>pt_BR</file>,
9429 <file>zh_CN</file>, and <file>zh_TW</file> are all allowed.
9434 If a localized version of a manual page is provided, it should
9435 either be up-to-date or it should be obvious to the reader that
9436 it is outdated and the original manual page should be used
9437 instead. This can be done either by a note at the beginning of
9438 the manual page or by showing the missing or changed portions in
9439 the original language instead of the target language.
9444 <heading>Info documents</heading>
9447 Info documents should be installed in <file>/usr/share/info</file>.
9448 They should be compressed with <tt>gzip -9</tt>.
9452 The <prgn>install-info</prgn> program maintains a directory of
9453 installed info documents in <file>/usr/share/info/dir</file> for
9454 the use of info readers.<footnote>
9455 It was previously necessary for packages installing info
9456 documents to run <prgn>install-info</prgn> from maintainer
9457 scripts. This is no longer necessary. The installation
9458 system now uses dpkg triggers.
9460 This file must not be included in packages. Packages containing
9461 info documents should depend on <tt>dpkg (>= 1.15.4) |
9462 install-info</tt> to ensure that the directory file is properly
9463 rebuilt during partial upgrades from Debian 5.0 (lenny) and
9468 Info documents should contain section and directory entry
9469 information in the document for the use
9470 of <prgn>install-info</prgn>. The section should be specified
9471 via a line starting with <tt>INFO-DIR-SECTION</tt> followed by a
9472 space and the section of this info page. The directory entry or
9473 entries should be included between
9474 a <tt>START-INFO-DIR-ENTRY</tt> line and
9475 an <tt>END-INFO-DIR-ENTRY</tt> line. For example:
9477 INFO-DIR-SECTION Individual utilities
9478 START-INFO-DIR-ENTRY
9479 * example: (example). An example info directory entry.
9482 To determine which section to use, you should look
9483 at <file>/usr/share/info/dir</file> on your system and choose
9484 the most relevant (or create a new section if none of the
9485 current sections are relevant).<footnote>
9486 Normally, info documents are generated from Texinfo source.
9487 To include this information in the generated info document, if
9488 it is absent, add commands like:
9490 @dircategory Individual utilities
9492 * example: (example). An example info directory entry.
9495 to the Texinfo source of the document and ensure that the info
9496 documents are rebuilt from source during the package build.
9502 <heading>Additional documentation</heading>
9505 Any additional documentation that comes with the package may
9506 be installed at the discretion of the package maintainer.
9507 Plain text documentation should be installed in the directory
9508 <file>/usr/share/doc/<var>package</var></file>, where
9509 <var>package</var> is the name of the package, and
9510 compressed with <tt>gzip -9</tt> unless it is small.
9514 If a package comes with large amounts of documentation which
9515 many users of the package will not require you should create
9516 a separate binary package to contain it, so that it does not
9517 take up disk space on the machines of users who do not need
9518 or want it installed.</p>
9521 It is often a good idea to put text information files
9522 (<file>README</file>s, changelogs, and so forth) that come with
9523 the source package in <file>/usr/share/doc/<var>package</var></file>
9524 in the binary package. However, you don't need to install
9525 the instructions for building and installing the package, of
9529 Packages must not require the existence of any files in
9530 <file>/usr/share/doc/</file> in order to function
9532 The system administrator should be able to
9533 delete files in <file>/usr/share/doc/</file> without causing
9534 any programs to break.
9536 Any files that are referenced by programs but are also
9537 useful as stand alone documentation should be installed under
9538 <file>/usr/share/<var>package</var>/</file> with symbolic links from
9539 <file>/usr/share/doc/<var>package</var></file>.
9543 <file>/usr/share/doc/<var>package</var></file> may be a symbolic
9544 link to another directory in <file>/usr/share/doc</file> only if
9545 the two packages both come from the same source and the
9546 first package Depends on the second.<footnote>
9548 Please note that this does not override the section on
9549 changelog files below, so the file
9550 <file>/usr/share/doc/<var>package</var>/changelog.Debian.gz</file>
9551 must refer to the changelog for the current version of
9552 <var>package</var> in question. In practice, this means
9553 that the sources of the target and the destination of the
9554 symlink must be the same (same source package and
9561 Former Debian releases placed all additional documentation
9562 in <file>/usr/doc/<var>package</var></file>. This has been
9563 changed to <file>/usr/share/doc/<var>package</var></file>,
9564 and packages must not put documentation in the directory
9565 <file>/usr/doc/<var>package</var></file>. <footnote>
9566 At this phase of the transition, we no longer require a
9567 symbolic link in <file>/usr/doc/</file>. At a later point,
9568 policy shall change to make the symbolic links a bug.
9574 <heading>Preferred documentation formats</heading>
9577 The unification of Debian documentation is being carried out
9581 If your package comes with extensive documentation in a
9582 markup format that can be converted to various other formats
9583 you should if possible ship HTML versions in a binary
9584 package, in the directory
9585 <file>/usr/share/doc/<var>appropriate-package</var></file> or
9586 its subdirectories.<footnote>
9587 The rationale: The important thing here is that HTML
9588 docs should be available in <em>some</em> package, not
9589 necessarily in the main binary package.
9594 Other formats such as PostScript may be provided at the
9595 package maintainer's discretion.
9599 <sect id="copyrightfile">
9600 <heading>Copyright information</heading>
9603 Every package must be accompanied by a verbatim copy of its
9604 copyright information and distribution license in the file
9605 <file>/usr/share/doc/<var>package</var>/copyright</file>. This
9606 file must neither be compressed nor be a symbolic link.
9610 In addition, the copyright file must say where the upstream
9611 sources (if any) were obtained. It should name the original
9612 authors of the package and the Debian maintainer(s) who were
9613 involved with its creation.
9617 Packages in the <em>contrib</em> or <em>non-free</em> archive
9618 areas should state in the copyright file that the package is not
9619 part of the Debian distribution and briefly explain why.
9623 A copy of the file which will be installed in
9624 <file>/usr/share/doc/<var>package</var>/copyright</file> should
9625 be in <file>debian/copyright</file> in the source package.
9629 <file>/usr/share/doc/<var>package</var></file> may be a symbolic
9630 link to another directory in <file>/usr/share/doc</file> only if
9631 the two packages both come from the same source and the
9632 first package Depends on the second. These rules are
9633 important because copyrights must be extractable by
9638 Packages distributed under the Apache license (version 2.0), the
9639 Artistic license, the GNU GPL (versions 1, 2, or 3), the GNU
9640 LGPL (versions 2, 2.1, or 3), and the GNU FDL (versions 1.2 or
9641 1.3) should refer to the corresponding files
9642 under <file>/usr/share/common-licenses</file>,<footnote>
9645 <file>/usr/share/common-licenses/Apache-2.0</file>,
9646 <file>/usr/share/common-licenses/Artistic</file>,
9647 <file>/usr/share/common-licenses/GPL-1</file>,
9648 <file>/usr/share/common-licenses/GPL-2</file>,
9649 <file>/usr/share/common-licenses/GPL-3</file>,
9650 <file>/usr/share/common-licenses/LGPL-2</file>,
9651 <file>/usr/share/common-licenses/LGPL-2.1</file>,
9652 <file>/usr/share/common-licenses/LGPL-3</file>,
9653 <file>/usr/share/common-licenses/GFDL-1.2</file>, and
9654 <file>/usr/share/common-licenses/GFDL-1.3</file>
9655 respectively. The University of California BSD license is
9656 also included in <package>base-files</package> as
9657 <file>/usr/share/common-licenses/BSD</file>, but given the
9658 brevity of this license, its specificity to code whose
9659 copyright is held by the Regents of the University of
9660 California, and the frequency of minor wording changes, its
9661 text should be included in the copyright file rather than
9662 referencing this file.
9664 </footnote> rather than quoting them in the copyright
9669 You should not use the copyright file as a general <file>README</file>
9670 file. If your package has such a file it should be
9671 installed in <file>/usr/share/doc/<var>package</var>/README</file> or
9672 <file>README.Debian</file> or some other appropriate place.</p>
9676 <heading>Examples</heading>
9679 Any examples (configurations, source files, whatever),
9680 should be installed in a directory
9681 <file>/usr/share/doc/<var>package</var>/examples</file>. These
9682 files should not be referenced by any program: they're there
9683 for the benefit of the system administrator and users as
9684 documentation only. Architecture-specific example files
9685 should be installed in a directory
9686 <file>/usr/lib/<var>package</var>/examples</file> with symbolic
9688 <file>/usr/share/doc/<var>package</var>/examples</file>, or the
9689 latter directory itself may be a symbolic link to the
9694 If the purpose of a package is to provide examples, then the
9695 example files may be installed into
9696 <file>/usr/share/doc/<var>package</var></file>.
9700 <sect id="changelogs">
9701 <heading>Changelog files</heading>
9704 Packages that are not Debian-native must contain a
9705 compressed copy of the <file>debian/changelog</file> file from
9706 the Debian source tree in
9707 <file>/usr/share/doc/<var>package</var></file> with the name
9708 <file>changelog.Debian.gz</file>.
9712 If an upstream changelog is available, it should be accessible as
9713 <file>/usr/share/doc/<var>package</var>/changelog.gz</file> in
9714 plain text. If the upstream changelog is distributed in
9715 HTML, it should be made available in that form as
9716 <file>/usr/share/doc/<var>package</var>/changelog.html.gz</file>
9717 and a plain text <file>changelog.gz</file> should be generated
9718 from it using, for example, <tt>lynx -dump -nolist</tt>. If
9719 the upstream changelog files do not already conform to this
9720 naming convention, then this may be achieved either by
9721 renaming the files, or by adding a symbolic link, at the
9722 maintainer's discretion.<footnote>
9723 Rationale: People should not have to look in places for
9724 upstream changelogs merely because they are given
9725 different names or are distributed in HTML format.
9730 All of these files should be installed compressed using
9731 <tt>gzip -9</tt>, as they will become large with time even
9732 if they start out small.
9736 If the package has only one changelog which is used both as
9737 the Debian changelog and the upstream one because there is
9738 no separate upstream maintainer then that changelog should
9739 usually be installed as
9740 <file>/usr/share/doc/<var>package</var>/changelog.gz</file>; if
9741 there is a separate upstream maintainer, but no upstream
9742 changelog, then the Debian changelog should still be called
9743 <file>changelog.Debian.gz</file>.
9747 For details about the format and contents of the Debian
9748 changelog file, please see <ref id="dpkgchangelog">.
9753 <appendix id="pkg-scope">
9754 <heading>Introduction and scope of these appendices</heading>
9757 These appendices are taken essentially verbatim from the
9758 now-deprecated Packaging Manual, version 3.2.1.0. They are
9759 the chapters which are likely to be of use to package
9760 maintainers and which have not already been included in the
9761 policy document itself. Most of these sections are very likely
9762 not relevant to policy; they should be treated as
9763 documentation for the packaging system. Please note that these
9764 appendices are included for convenience, and for historical
9765 reasons: they used to be part of policy package, and they have
9766 not yet been incorporated into dpkg documentation. However,
9767 they still have value, and hence they are presented here.
9771 They have not yet been checked to ensure that they are
9772 compatible with the contents of policy, and if there are any
9773 contradictions, the version in the main policy document takes
9774 precedence. The remaining chapters of the old Packaging
9775 Manual have also not been read in detail to ensure that there
9776 are not parts which have been left out. Both of these will be
9781 Certain parts of the Packaging manual were integrated into the
9782 Policy Manual proper, and removed from the appendices. Links
9783 have been placed from the old locations to the new ones.
9787 <prgn>dpkg</prgn> is a suite of programs for creating binary
9788 package files and installing and removing them on Unix
9790 <prgn>dpkg</prgn> is targeted primarily at Debian, but may
9791 work on or be ported to other systems.
9796 The binary packages are designed for the management of
9797 installed executable programs (usually compiled binaries) and
9798 their associated data, though source code examples and
9799 documentation are provided as part of some packages.</p>
9802 This manual describes the technical aspects of creating Debian
9803 binary packages (<file>.deb</file> files). It documents the
9804 behavior of the package management programs
9805 <prgn>dpkg</prgn>, <prgn>dselect</prgn> et al. and the way
9806 they interact with packages.</p>
9809 It also documents the interaction between
9810 <prgn>dselect</prgn>'s core and the access method scripts it
9811 uses to actually install the selected packages, and describes
9812 how to create a new access method.</p>
9815 This manual does not go into detail about the options and
9816 usage of the package building and installation tools. It
9817 should therefore be read in conjunction with those programs'
9822 The utility programs which are provided with <prgn>dpkg</prgn>
9823 for managing various system configuration and similar issues,
9824 such as <prgn>update-rc.d</prgn> and
9825 <prgn>install-info</prgn>, are not described in detail here -
9826 please see their man pages.
9830 It is assumed that the reader is reasonably familiar with the
9831 <prgn>dpkg</prgn> System Administrators' manual.
9832 Unfortunately this manual does not yet exist.
9836 The Debian version of the FSF's GNU hello program is provided
9837 as an example for people wishing to create Debian
9838 packages. The Debian <prgn>debmake</prgn> package is
9839 recommended as a very helpful tool in creating and maintaining
9840 Debian packages. However, while the tools and examples are
9841 helpful, they do not replace the need to read and follow the
9842 Policy and Programmer's Manual.</p>
9845 <appendix id="pkg-binarypkg">
9846 <heading>Binary packages (from old Packaging Manual)</heading>
9849 The binary package has two main sections. The first part
9850 consists of various control information files and scripts used
9851 by <prgn>dpkg</prgn> when installing and removing. See <ref
9852 id="pkg-controlarea">.
9856 The second part is an archive containing the files and
9857 directories to be installed.
9861 In the future binary packages may also contain other
9862 components, such as checksums and digital signatures. The
9863 format for the archive is described in full in the
9864 <file>deb(5)</file> man page.
9868 <sect id="pkg-bincreating"><heading>Creating package files -
9869 <prgn>dpkg-deb</prgn>
9873 All manipulation of binary package files is done by
9874 <prgn>dpkg-deb</prgn>; it's the only program that has
9875 knowledge of the format. (<prgn>dpkg-deb</prgn> may be
9876 invoked by calling <prgn>dpkg</prgn>, as <prgn>dpkg</prgn>
9877 will spot that the options requested are appropriate to
9878 <prgn>dpkg-deb</prgn> and invoke that instead with the same
9883 In order to create a binary package you must make a
9884 directory tree which contains all the files and directories
9885 you want to have in the file system data part of the package.
9886 In Debian-format source packages this directory is usually
9887 <file>debian/tmp</file>, relative to the top of the package's
9892 They should have the locations (relative to the root of the
9893 directory tree you're constructing) ownerships and
9894 permissions which you want them to have on the system when
9899 With current versions of <prgn>dpkg</prgn> the uid/username
9900 and gid/groupname mappings for the users and groups being
9901 used should be the same on the system where the package is
9902 built and the one where it is installed.
9906 You need to add one special directory to the root of the
9907 miniature file system tree you're creating:
9908 <prgn>DEBIAN</prgn>. It should contain the control
9909 information files, notably the binary package control file
9910 (see <ref id="pkg-controlfile">).
9914 The <prgn>DEBIAN</prgn> directory will not appear in the
9915 file system archive of the package, and so won't be installed
9916 by <prgn>dpkg</prgn> when the package is installed.
9920 When you've prepared the package, you should invoke:
9922 dpkg --build <var>directory</var>
9927 This will build the package in
9928 <file><var>directory</var>.deb</file>. (<prgn>dpkg</prgn> knows
9929 that <tt>--build</tt> is a <prgn>dpkg-deb</prgn> option, so
9930 it invokes <prgn>dpkg-deb</prgn> with the same arguments to
9935 See the man page <manref name="dpkg-deb" section="8"> for details of how
9936 to examine the contents of this newly-created file. You may find the
9937 output of following commands enlightening:
9939 dpkg-deb --info <var>filename</var>.deb
9940 dpkg-deb --contents <var>filename</var>.deb
9941 dpkg --contents <var>filename</var>.deb
9943 To view the copyright file for a package you could use this command:
9945 dpkg --fsys-tarfile <var>filename</var>.deb | tar xOf - --wildcards \*/copyright | pager
9950 <sect id="pkg-controlarea">
9951 <heading>Package control information files</heading>
9954 The control information portion of a binary package is a
9955 collection of files with names known to <prgn>dpkg</prgn>.
9956 It will treat the contents of these files specially - some
9957 of them contain information used by <prgn>dpkg</prgn> when
9958 installing or removing the package; others are scripts which
9959 the package maintainer wants <prgn>dpkg</prgn> to run.
9963 It is possible to put other files in the package control
9964 information file area, but this is not generally a good idea
9965 (though they will largely be ignored).
9969 Here is a brief list of the control information files supported
9970 by <prgn>dpkg</prgn> and a summary of what they're used for.
9975 <tag><tt>control</tt>
9978 This is the key description file used by
9979 <prgn>dpkg</prgn>. It specifies the package's name
9980 and version, gives its description for the user,
9981 states its relationships with other packages, and so
9982 forth. See <ref id="sourcecontrolfiles"> and
9983 <ref id="binarycontrolfiles">.
9987 It is usually generated automatically from information
9988 in the source package by the
9989 <prgn>dpkg-gencontrol</prgn> program, and with
9990 assistance from <prgn>dpkg-shlibdeps</prgn>.
9991 See <ref id="pkg-sourcetools">.
9995 <tag><tt>postinst</tt>, <tt>preinst</tt>, <tt>postrm</tt>,
10000 These are executable files (usually scripts) which
10001 <prgn>dpkg</prgn> runs during installation, upgrade
10002 and removal of packages. They allow the package to
10003 deal with matters which are particular to that package
10004 or require more complicated processing than that
10005 provided by <prgn>dpkg</prgn>. Details of when and
10006 how they are called are in <ref id="maintainerscripts">.
10010 It is very important to make these scripts idempotent.
10011 See <ref id="idempotency">.
10015 The maintainer scripts are not guaranteed to run with a
10016 controlling terminal and may not be able to interact with
10017 the user. See <ref id="controllingterminal">.
10021 <tag><tt>conffiles</tt>
10024 This file contains a list of configuration files which
10025 are to be handled automatically by <prgn>dpkg</prgn>
10026 (see <ref id="pkg-conffiles">). Note that not necessarily
10027 every configuration file should be listed here.
10030 <tag><tt>shlibs</tt>
10033 This file contains a list of the shared libraries
10034 supplied by the package, with dependency details for
10035 each. This is used by <prgn>dpkg-shlibdeps</prgn>
10036 when it determines what dependencies are required in a
10037 package control file. The <tt>shlibs</tt> file format
10038 is described on <ref id="shlibs">.
10043 <sect id="pkg-controlfile">
10044 <heading>The main control information file: <tt>control</tt></heading>
10047 The most important control information file used by
10048 <prgn>dpkg</prgn> when it installs a package is
10049 <tt>control</tt>. It contains all the package's "vital
10054 The binary package control files of packages built from
10055 Debian sources are made by a special tool,
10056 <prgn>dpkg-gencontrol</prgn>, which reads
10057 <file>debian/control</file> and <file>debian/changelog</file> to
10058 find the information it needs. See <ref id="pkg-sourcepkg"> for
10063 The fields in binary package control files are listed in
10064 <ref id="binarycontrolfiles">.
10068 A description of the syntax of control files and the purpose
10069 of the fields is available in <ref id="controlfields">.
10074 <heading>Time Stamps</heading>
10077 See <ref id="timestamps">.
10082 <appendix id="pkg-sourcepkg">
10083 <heading>Source packages (from old Packaging Manual) </heading>
10086 The Debian binary packages in the distribution are generated
10087 from Debian sources, which are in a special format to assist
10088 the easy and automatic building of binaries.
10091 <sect id="pkg-sourcetools">
10092 <heading>Tools for processing source packages</heading>
10095 Various tools are provided for manipulating source packages;
10096 they pack and unpack sources and help build of binary
10097 packages and help manage the distribution of new versions.
10101 They are introduced and typical uses described here; see
10102 <manref name="dpkg-source" section="1"> for full
10103 documentation about their arguments and operation.
10107 For examples of how to construct a Debian source package,
10108 and how to use those utilities that are used by Debian
10109 source packages, please see the <prgn>hello</prgn> example
10113 <sect1 id="pkg-dpkg-source">
10115 <prgn>dpkg-source</prgn> - packs and unpacks Debian source
10120 This program is frequently used by hand, and is also
10121 called from package-independent automated building scripts
10122 such as <prgn>dpkg-buildpackage</prgn>.
10126 To unpack a package it is typically invoked with
10128 dpkg-source -x <var>.../path/to/filename</var>.dsc
10133 with the <file><var>filename</var>.tar.gz</file> and
10134 <file><var>filename</var>.diff.gz</file> (if applicable) in
10135 the same directory. It unpacks into
10136 <file><var>package</var>-<var>version</var></file>, and if
10138 <file><var>package</var>-<var>version</var>.orig</file>, in
10139 the current directory.
10143 To create a packed source archive it is typically invoked:
10145 dpkg-source -b <var>package</var>-<var>version</var>
10150 This will create the <file>.dsc</file>, <file>.tar.gz</file> and
10151 <file>.diff.gz</file> (if appropriate) in the current
10152 directory. <prgn>dpkg-source</prgn> does not clean the
10153 source tree first - this must be done separately if it is
10158 See also <ref id="pkg-sourcearchives">.</p>
10162 <sect1 id="pkg-dpkg-buildpackage">
10164 <prgn>dpkg-buildpackage</prgn> - overall package-building
10169 <prgn>dpkg-buildpackage</prgn> is a script which invokes
10170 <prgn>dpkg-source</prgn>, the <file>debian/rules</file>
10171 targets <tt>clean</tt>, <tt>build</tt> and
10172 <tt>binary</tt>, <prgn>dpkg-genchanges</prgn> and
10173 <prgn>gpg</prgn> (or <prgn>pgp</prgn>) to build a signed
10174 source and binary package upload.
10178 It is usually invoked by hand from the top level of the
10179 built or unbuilt source directory. It may be invoked with
10180 no arguments; useful arguments include:
10181 <taglist compact="compact">
10182 <tag><tt>-uc</tt>, <tt>-us</tt></tag>
10185 Do not sign the <tt>.changes</tt> file or the
10186 source package <tt>.dsc</tt> file, respectively.</p>
10188 <tag><tt>-p<var>sign-command</var></tt></tag>
10191 Invoke <var>sign-command</var> instead of finding
10192 <tt>gpg</tt> or <tt>pgp</tt> on the <prgn>PATH</prgn>.
10193 <var>sign-command</var> must behave just like
10194 <prgn>gpg</prgn> or <tt>pgp</tt>.</p>
10196 <tag><tt>-r<var>root-command</var></tt></tag>
10199 When root privilege is required, invoke the command
10200 <var>root-command</var>. <var>root-command</var>
10201 should invoke its first argument as a command, from
10202 the <prgn>PATH</prgn> if necessary, and pass its
10203 second and subsequent arguments to the command it
10204 calls. If no <var>root-command</var> is supplied
10205 then <var>dpkg-buildpackage</var> will take no
10206 special action to gain root privilege, so that for
10207 most packages it will have to be invoked as root to
10210 <tag><tt>-b</tt>, <tt>-B</tt></tag>
10213 Two types of binary-only build and upload - see
10214 <manref name="dpkg-source" section="1">.
10221 <sect1 id="pkg-dpkg-gencontrol">
10223 <prgn>dpkg-gencontrol</prgn> - generates binary package
10228 This program is usually called from <file>debian/rules</file>
10229 (see <ref id="pkg-sourcetree">) in the top level of the source
10234 This is usually done just before the files and directories in the
10235 temporary directory tree where the package is being built have their
10236 permissions and ownerships set and the package is constructed using
10237 <prgn>dpkg-deb/</prgn>
10239 This is so that the control file which is produced has
10240 the right permissions
10245 <prgn>dpkg-gencontrol</prgn> must be called after all the
10246 files which are to go into the package have been placed in
10247 the temporary build directory, so that its calculation of
10248 the installed size of a package is correct.
10252 It is also necessary for <prgn>dpkg-gencontrol</prgn> to
10253 be run after <prgn>dpkg-shlibdeps</prgn> so that the
10254 variable substitutions created by
10255 <prgn>dpkg-shlibdeps</prgn> in <file>debian/substvars</file>
10260 For a package which generates only one binary package, and
10261 which builds it in <file>debian/tmp</file> relative to the top
10262 of the source package, it is usually sufficient to call
10263 <prgn>dpkg-gencontrol</prgn>.
10267 Sources which build several binaries will typically need
10270 dpkg-gencontrol -Pdebian/tmp-<var>pkg</var> -p<var>package</var>
10271 </example> The <tt>-P</tt> tells
10272 <prgn>dpkg-gencontrol</prgn> that the package is being
10273 built in a non-default directory, and the <tt>-p</tt>
10274 tells it which package's control file should be generated.
10278 <prgn>dpkg-gencontrol</prgn> also adds information to the
10279 list of files in <file>debian/files</file>, for the benefit of
10280 (for example) a future invocation of
10281 <prgn>dpkg-genchanges</prgn>.</p>
10284 <sect1 id="pkg-dpkg-shlibdeps">
10286 <prgn>dpkg-shlibdeps</prgn> - calculates shared library
10291 This program is usually called from <file>debian/rules</file>
10292 just before <prgn>dpkg-gencontrol</prgn> (see <ref
10293 id="pkg-sourcetree">), in the top level of the source tree.
10297 Its arguments are executables and shared libraries
10300 They may be specified either in the locations in the
10301 source tree where they are created or in the locations
10302 in the temporary build tree where they are installed
10303 prior to binary package creation.
10305 </footnote> for which shared library dependencies should
10306 be included in the binary package's control file.
10310 If some of the found shared libraries should only
10311 warrant a <tt>Recommends</tt> or <tt>Suggests</tt>, or if
10312 some warrant a <tt>Pre-Depends</tt>, this can be achieved
10313 by using the <tt>-d<var>dependency-field</var></tt> option
10314 before those executable(s). (Each <tt>-d</tt> option
10315 takes effect until the next <tt>-d</tt>.)
10319 <prgn>dpkg-shlibdeps</prgn> does not directly cause the
10320 output control file to be modified. Instead by default it
10321 adds to the <file>debian/substvars</file> file variable
10322 settings like <tt>shlibs:Depends</tt>. These variable
10323 settings must be referenced in dependency fields in the
10324 appropriate per-binary-package sections of the source
10329 For example, a package that generates an essential part
10330 which requires dependencies, and optional parts that
10331 which only require a recommendation, would separate those
10332 two sets of dependencies into two different fields.<footnote>
10333 At the time of writing, an example for this was the
10334 <package/xmms/ package, with Depends used for the xmms
10335 executable, Recommends for the plug-ins and Suggests for
10336 even more optional features provided by unzip.
10338 It can say in its <file>debian/rules</file>:
10340 dpkg-shlibdeps -dDepends <var>program anotherprogram ...</var> \
10341 -dRecommends <var>optionalpart anotheroptionalpart</var>
10343 and then in its main control file <file>debian/control</file>:
10346 Depends: ${shlibs:Depends}
10347 Recommends: ${shlibs:Recommends}
10353 Sources which produce several binary packages with
10354 different shared library dependency requirements can use
10355 the <tt>-p<var>varnameprefix</var></tt> option to override
10356 the default <tt>shlibs:</tt> prefix (one invocation of
10357 <prgn>dpkg-shlibdeps</prgn> per setting of this option).
10358 They can thus produce several sets of dependency
10359 variables, each of the form
10360 <tt><var>varnameprefix</var>:<var>dependencyfield</var></tt>,
10361 which can be referred to in the appropriate parts of the
10362 binary package control files.
10367 <sect1 id="pkg-dpkg-distaddfile">
10369 <prgn>dpkg-distaddfile</prgn> - adds a file to
10370 <file>debian/files</file>
10374 Some packages' uploads need to include files other than
10375 the source and binary package files.
10379 <prgn>dpkg-distaddfile</prgn> adds a file to the
10380 <file>debian/files</file> file so that it will be included in
10381 the <file>.changes</file> file when
10382 <prgn>dpkg-genchanges</prgn> is run.
10386 It is usually invoked from the <tt>binary</tt> target of
10387 <file>debian/rules</file>:
10389 dpkg-distaddfile <var>filename</var> <var>section</var> <var>priority</var>
10391 The <var>filename</var> is relative to the directory where
10392 <prgn>dpkg-genchanges</prgn> will expect to find it - this
10393 is usually the directory above the top level of the source
10394 tree. The <file>debian/rules</file> target should put the
10395 file there just before or just after calling
10396 <prgn>dpkg-distaddfile</prgn>.
10400 The <var>section</var> and <var>priority</var> are passed
10401 unchanged into the resulting <file>.changes</file> file.
10406 <sect1 id="pkg-dpkg-genchanges">
10408 <prgn>dpkg-genchanges</prgn> - generates a <file>.changes</file>
10409 upload control file
10413 This program is usually called by package-independent
10414 automatic building scripts such as
10415 <prgn>dpkg-buildpackage</prgn>, but it may also be called
10420 It is usually called in the top level of a built source
10421 tree, and when invoked with no arguments will print out a
10422 straightforward <file>.changes</file> file based on the
10423 information in the source package's changelog and control
10424 file and the binary and source packages which should have
10430 <sect1 id="pkg-dpkg-parsechangelog">
10432 <prgn>dpkg-parsechangelog</prgn> - produces parsed
10433 representation of a changelog
10437 This program is used internally by
10438 <prgn>dpkg-source</prgn> et al. It may also occasionally
10439 be useful in <file>debian/rules</file> and elsewhere. It
10440 parses a changelog, <file>debian/changelog</file> by default,
10441 and prints a control-file format representation of the
10442 information in it to standard output.
10446 <sect1 id="pkg-dpkg-architecture">
10448 <prgn>dpkg-architecture</prgn> - information about the build and
10453 This program can be used manually, but is also invoked by
10454 <tt>dpkg-buildpackage</tt> or <file>debian/rules</file> to set
10455 environment or make variables which specify the build and host
10456 architecture for the package building process.
10461 <sect id="pkg-sourcetree">
10462 <heading>The Debian package source tree</heading>
10465 The source archive scheme described later is intended to
10466 allow a Debian package source tree with some associated
10467 control information to be reproduced and transported easily.
10468 The Debian package source tree is a version of the original
10469 program with certain files added for the benefit of the
10470 packaging process, and with any other changes required
10471 made to the rest of the source code and installation
10476 The extra files created for Debian are in the subdirectory
10477 <file>debian</file> of the top level of the Debian package
10478 source tree. They are described below.
10481 <sect1 id="pkg-debianrules">
10482 <heading><file>debian/rules</file> - the main building script</heading>
10485 See <ref id="debianrules">.
10489 <sect1 id="pkg-srcsubstvars">
10490 <heading><file>debian/substvars</file> and variable substitutions</heading>
10493 See <ref id="substvars">.
10499 <heading><file>debian/files</file></heading>
10502 See <ref id="debianfiles">.
10506 <sect1><heading><file>debian/tmp</file>
10510 This is the canonical temporary location for the
10511 construction of binary packages by the <tt>binary</tt>
10512 target. The directory <file>tmp</file> serves as the root of
10513 the file system tree as it is being constructed (for
10514 example, by using the package's upstream makefiles install
10515 targets and redirecting the output there), and it also
10516 contains the <tt>DEBIAN</tt> subdirectory. See <ref
10517 id="pkg-bincreating">.
10521 If several binary packages are generated from the same
10522 source tree it is usual to use several
10523 <file>debian/tmp<var>something</var></file> directories, for
10524 example <file>tmp-a</file> or <file>tmp-doc</file>.
10528 Whatever <file>tmp</file> directories are created and used by
10529 <tt>binary</tt> must of course be removed by the
10530 <tt>clean</tt> target.</p></sect1>
10534 <sect id="pkg-sourcearchives"><heading>Source packages as archives
10538 As it exists on the FTP site, a Debian source package
10539 consists of three related files. You must have the right
10540 versions of all three to be able to use them.
10545 <tag>Debian source control file - <tt>.dsc</tt></tag>
10547 This file is a control file used by <prgn>dpkg-source</prgn>
10548 to extract a source package.
10549 See <ref id="debiansourcecontrolfiles">.
10553 Original source archive -
10555 <var>package</var>_<var>upstream-version</var>.orig.tar.gz
10561 This is a compressed (with <tt>gzip -9</tt>)
10562 <prgn>tar</prgn> file containing the source code from
10563 the upstream authors of the program.
10568 Debian package diff -
10570 <var>package</var>_<var>upstream_version-revision</var>.diff.gz
10576 This is a unified context diff (<tt>diff -u</tt>)
10577 giving the changes which are required to turn the
10578 original source into the Debian source. These changes
10579 may only include editing and creating plain files.
10580 The permissions of files, the targets of symbolic
10581 links and the characteristics of special files or
10582 pipes may not be changed and no files may be removed
10587 All the directories in the diff must exist, except the
10588 <file>debian</file> subdirectory of the top of the source
10589 tree, which will be created by
10590 <prgn>dpkg-source</prgn> if necessary when unpacking.
10594 The <prgn>dpkg-source</prgn> program will
10595 automatically make the <file>debian/rules</file> file
10596 executable (see below).</p></item>
10601 If there is no original source code - for example, if the
10602 package is specially prepared for Debian or the Debian
10603 maintainer is the same as the upstream maintainer - the
10604 format is slightly different: then there is no diff, and the
10606 <file><var>package</var>_<var>version</var>.tar.gz</file>,
10607 and preferably contains a directory named
10608 <file><var>package</var>-<var>version</var></file>.
10613 <heading>Unpacking a Debian source package without <prgn>dpkg-source</prgn></heading>
10616 <tt>dpkg-source -x</tt> is the recommended way to unpack a
10617 Debian source package. However, if it is not available it
10618 is possible to unpack a Debian source archive as follows:
10619 <enumlist compact="compact">
10622 Untar the tarfile, which will create a <file>.orig</file>
10626 <p>Rename the <file>.orig</file> directory to
10627 <file><var>package</var>-<var>version</var></file>.</p>
10631 Create the subdirectory <file>debian</file> at the top of
10632 the source tree.</p>
10634 <item><p>Apply the diff using <tt>patch -p0</tt>.</p>
10636 <item><p>Untar the tarfile again if you want a copy of the original
10637 source code alongside the Debian version.</p>
10642 It is not possible to generate a valid Debian source archive
10643 without using <prgn>dpkg-source</prgn>. In particular,
10644 attempting to use <prgn>diff</prgn> directly to generate the
10645 <file>.diff.gz</file> file will not work.
10649 <heading>Restrictions on objects in source packages</heading>
10652 The source package may not contain any hard links
10654 This is not currently detected when building source
10655 packages, but only when extracting
10659 Hard links may be permitted at some point in the
10660 future, but would require a fair amount of
10662 </footnote>, device special files, sockets or setuid or
10665 Setgid directories are allowed.
10670 The source packaging tools manage the changes between the
10671 original and Debian source using <prgn>diff</prgn> and
10672 <prgn>patch</prgn>. Turning the original source tree as
10673 included in the <file>.orig.tar.gz</file> into the Debian
10674 package source must not involve any changes which cannot be
10675 handled by these tools. Problematic changes which cause
10676 <prgn>dpkg-source</prgn> to halt with an error when
10677 building the source package are:
10678 <list compact="compact">
10679 <item><p>Adding or removing symbolic links, sockets or pipes.</p>
10681 <item><p>Changing the targets of symbolic links.</p>
10683 <item><p>Creating directories, other than <file>debian</file>.</p>
10685 <item><p>Changes to the contents of binary files.</p></item>
10686 </list> Changes which cause <prgn>dpkg-source</prgn> to
10687 print a warning but continue anyway are:
10688 <list compact="compact">
10691 Removing files, directories or symlinks.
10693 Renaming a file is not treated specially - it is
10694 seen as the removal of the old file (which
10695 generates a warning, but is otherwise ignored),
10696 and the creation of the new one.
10702 Changed text files which are missing the usual final
10703 newline (either in the original or the modified
10708 Changes which are not represented, but which are not detected by
10709 <prgn>dpkg-source</prgn>, are:
10710 <list compact="compact">
10711 <item><p>Changing the permissions of files (other than
10712 <file>debian/rules</file>) and directories.</p></item>
10717 The <file>debian</file> directory and <file>debian/rules</file>
10718 are handled specially by <prgn>dpkg-source</prgn> - before
10719 applying the changes it will create the <file>debian</file>
10720 directory, and afterwards it will make
10721 <file>debian/rules</file> world-executable.
10727 <appendix id="pkg-controlfields">
10728 <heading>Control files and their fields (from old Packaging Manual)</heading>
10731 Many of the tools in the <prgn>dpkg</prgn> suite manipulate
10732 data in a common format, known as control files. Binary and
10733 source packages have control data as do the <file>.changes</file>
10734 files which control the installation of uploaded files, and
10735 <prgn>dpkg</prgn>'s internal databases are in a similar
10740 <heading>Syntax of control files</heading>
10743 See <ref id="controlsyntax">.
10747 It is important to note that there are several fields which
10748 are optional as far as <prgn>dpkg</prgn> and the related
10749 tools are concerned, but which must appear in every Debian
10750 package, or whose omission may cause problems.
10755 <heading>List of fields</heading>
10758 See <ref id="controlfieldslist">.
10762 This section now contains only the fields that didn't belong
10763 to the Policy manual.
10766 <sect1 id="pkg-f-Filename">
10767 <heading><tt>Filename</tt> and <tt>MSDOS-Filename</tt></heading>
10770 These fields in <tt>Packages</tt> files give the
10771 filename(s) of (the parts of) a package in the
10772 distribution directories, relative to the root of the
10773 Debian hierarchy. If the package has been split into
10774 several parts the parts are all listed in order, separated
10779 <sect1 id="pkg-f-Size">
10780 <heading><tt>Size</tt> and <tt>MD5sum</tt></heading>
10783 These fields in <file>Packages</file> files give the size (in
10784 bytes, expressed in decimal) and MD5 checksum of the
10785 file(s) which make(s) up a binary package in the
10786 distribution. If the package is split into several parts
10787 the values for the parts are listed in order, separated by
10792 <sect1 id="pkg-f-Status">
10793 <heading><tt>Status</tt></heading>
10796 This field in <prgn>dpkg</prgn>'s status file records
10797 whether the user wants a package installed, removed or
10798 left alone, whether it is broken (requiring
10799 re-installation) or not and what its current state on the
10800 system is. Each of these pieces of information is a
10805 <sect1 id="pkg-f-Config-Version">
10806 <heading><tt>Config-Version</tt></heading>
10809 If a package is not installed or not configured, this
10810 field in <prgn>dpkg</prgn>'s status file records the last
10811 version of the package which was successfully
10816 <sect1 id="pkg-f-Conffiles">
10817 <heading><tt>Conffiles</tt></heading>
10820 This field in <prgn>dpkg</prgn>'s status file contains
10821 information about the automatically-managed configuration
10822 files held by a package. This field should <em>not</em>
10823 appear anywhere in a package!
10828 <heading>Obsolete fields</heading>
10831 These are still recognized by <prgn>dpkg</prgn> but should
10832 not appear anywhere any more.
10834 <taglist compact="compact">
10836 <tag><tt>Revision</tt></tag>
10837 <tag><tt>Package-Revision</tt></tag>
10838 <tag><tt>Package_Revision</tt></tag>
10840 The Debian revision part of the package version was
10841 at one point in a separate control field. This
10842 field went through several names.
10845 <tag><tt>Recommended</tt></tag>
10846 <item>Old name for <tt>Recommends</tt>.</item>
10848 <tag><tt>Optional</tt></tag>
10849 <item>Old name for <tt>Suggests</tt>.</item>
10851 <tag><tt>Class</tt></tag>
10852 <item>Old name for <tt>Priority</tt>.</item>
10861 <appendix id="pkg-conffiles">
10862 <heading>Configuration file handling (from old Packaging Manual)</heading>
10865 <prgn>dpkg</prgn> can do a certain amount of automatic
10866 handling of package configuration files.
10870 Whether this mechanism is appropriate depends on a number of
10871 factors, but basically there are two approaches to any
10872 particular configuration file.
10876 The easy method is to ship a best-effort configuration in the
10877 package, and use <prgn>dpkg</prgn>'s conffile mechanism to
10878 handle updates. If the user is unlikely to want to edit the
10879 file, but you need them to be able to without losing their
10880 changes, and a new package with a changed version of the file
10881 is only released infrequently, this is a good approach.
10885 The hard method is to build the configuration file from
10886 scratch in the <prgn>postinst</prgn> script, and to take the
10887 responsibility for fixing any mistakes made in earlier
10888 versions of the package automatically. This will be
10889 appropriate if the file is likely to need to be different on
10893 <sect><heading>Automatic handling of configuration files by
10898 A package may contain a control information file called
10899 <tt>conffiles</tt>. This file should be a list of filenames
10900 of configuration files needing automatic handling, separated
10901 by newlines. The filenames should be absolute pathnames,
10902 and the files referred to should actually exist in the
10907 When a package is upgraded <prgn>dpkg</prgn> will process
10908 the configuration files during the configuration stage,
10909 shortly before it runs the package's <prgn>postinst</prgn>
10914 For each file it checks to see whether the version of the
10915 file included in the package is the same as the one that was
10916 included in the last version of the package (the one that is
10917 being upgraded from); it also compares the version currently
10918 installed on the system with the one shipped with the last
10923 If neither the user nor the package maintainer has changed
10924 the file, it is left alone. If one or the other has changed
10925 their version, then the changed version is preferred - i.e.,
10926 if the user edits their file, but the package maintainer
10927 doesn't ship a different version, the user's changes will
10928 stay, silently, but if the maintainer ships a new version
10929 and the user hasn't edited it the new version will be
10930 installed (with an informative message). If both have
10931 changed their version the user is prompted about the problem
10932 and must resolve the differences themselves.
10936 The comparisons are done by calculating the MD5 message
10937 digests of the files, and storing the MD5 of the file as it
10938 was included in the most recent version of the package.
10942 When a package is installed for the first time
10943 <prgn>dpkg</prgn> will install the file that comes with it,
10944 unless that would mean overwriting a file already on the
10949 However, note that <prgn>dpkg</prgn> will <em>not</em>
10950 replace a conffile that was removed by the user (or by a
10951 script). This is necessary because with some programs a
10952 missing file produces an effect hard or impossible to
10953 achieve in another way, so that a missing file needs to be
10954 kept that way if the user did it.
10958 Note that a package should <em>not</em> modify a
10959 <prgn>dpkg</prgn>-handled conffile in its maintainer
10960 scripts. Doing this will lead to <prgn>dpkg</prgn> giving
10961 the user confusing and possibly dangerous options for
10962 conffile update when the package is upgraded.</p>
10965 <sect><heading>Fully-featured maintainer script configuration
10970 For files which contain site-specific information such as
10971 the hostname and networking details and so forth, it is
10972 better to create the file in the package's
10973 <prgn>postinst</prgn> script.
10977 This will typically involve examining the state of the rest
10978 of the system to determine values and other information, and
10979 may involve prompting the user for some information which
10980 can't be obtained some other way.
10984 When using this method there are a couple of important
10985 issues which should be considered:
10989 If you discover a bug in the program which generates the
10990 configuration file, or if the format of the file changes
10991 from one version to the next, you will have to arrange for
10992 the postinst script to do something sensible - usually this
10993 will mean editing the installed configuration file to remove
10994 the problem or change the syntax. You will have to do this
10995 very carefully, since the user may have changed the file,
10996 perhaps to fix the very problem that your script is trying
10997 to deal with - you will have to detect these situations and
10998 deal with them correctly.
11002 If you do go down this route it's probably a good idea to
11003 make the program that generates the configuration file(s) a
11004 separate program in <file>/usr/sbin</file>, by convention called
11005 <file><var>package</var>config</file> and then run that if
11006 appropriate from the post-installation script. The
11007 <tt><var>package</var>config</tt> program should not
11008 unquestioningly overwrite an existing configuration - if its
11009 mode of operation is geared towards setting up a package for
11010 the first time (rather than any arbitrary reconfiguration
11011 later) you should have it check whether the configuration
11012 already exists, and require a <tt>--force</tt> flag to
11013 overwrite it.</p></sect>
11016 <appendix id="pkg-alternatives"><heading>Alternative versions of
11017 an interface - <prgn>update-alternatives</prgn> (from old
11022 When several packages all provide different versions of the
11023 same program or file it is useful to have the system select a
11024 default, but to allow the system administrator to change it
11025 and have their decisions respected.
11029 For example, there are several versions of the <prgn>vi</prgn>
11030 editor, and there is no reason to prevent all of them from
11031 being installed at once, each under their own name
11032 (<prgn>nvi</prgn>, <prgn>vim</prgn> or whatever).
11033 Nevertheless it is desirable to have the name <tt>vi</tt>
11034 refer to something, at least by default.
11038 If all the packages involved cooperate, this can be done with
11039 <prgn>update-alternatives</prgn>.
11043 Each package provides its own version under its own name, and
11044 calls <prgn>update-alternatives</prgn> in its postinst to
11045 register its version (and again in its prerm to deregister
11050 See the man page <manref name="update-alternatives"
11051 section="8"> for details.
11055 If <prgn>update-alternatives</prgn> does not seem appropriate
11056 you may wish to consider using diversions instead.</p>
11059 <appendix id="pkg-diversions"><heading>Diversions - overriding a
11060 package's version of a file (from old Packaging Manual)
11064 It is possible to have <prgn>dpkg</prgn> not overwrite a file
11065 when it reinstalls the package it belongs to, and to have it
11066 put the file from the package somewhere else instead.
11070 This can be used locally to override a package's version of a
11071 file, or by one package to override another's version (or
11072 provide a wrapper for it).
11076 Before deciding to use a diversion, read <ref
11077 id="pkg-alternatives"> to see if you really want a diversion
11078 rather than several alternative versions of a program.
11082 There is a diversion list, which is read by <prgn>dpkg</prgn>,
11083 and updated by a special program <prgn>dpkg-divert</prgn>.
11084 Please see <manref name="dpkg-divert" section="8"> for full
11085 details of its operation.
11089 When a package wishes to divert a file from another, it should
11090 call <prgn>dpkg-divert</prgn> in its preinst to add the
11091 diversion and rename the existing file. For example,
11092 supposing that a <prgn>smailwrapper</prgn> package wishes to
11093 install a wrapper around <file>/usr/sbin/smail</file>:
11095 dpkg-divert --package smailwrapper --add --rename \
11096 --divert /usr/sbin/smail.real /usr/sbin/smail
11097 </example> The <tt>--package smailwrapper</tt> ensures that
11098 <prgn>smailwrapper</prgn>'s copy of <file>/usr/sbin/smail</file>
11099 can bypass the diversion and get installed as the true version.
11100 It's safe to add the diversion unconditionally on upgrades since
11101 it will be left unchanged if it already exists, but
11102 <prgn>dpkg-divert</prgn> will display a message. To suppress that
11103 message, make the command conditional on the version from which
11104 the package is being upgraded:
11106 if [ upgrade != "$1" ] || dpkg --compare-versions "$2" lt 1.0-2; then
11107 dpkg-divert --package smailwrapper --add --rename \
11108 --divert /usr/sbin/smail.real /usr/sbin/smail
11110 </example> where <tt>1.0-2</tt> is the version at which the
11111 diversion was first added to the package. Running the command
11112 during abort-upgrade is pointless but harmless.
11116 The postrm has to do the reverse:
11118 if [ remove = "$1" -o abort-install = "$1" -o disappear = "$1" ]; then
11119 dpkg-divert --package smailwrapper --remove --rename \
11120 --divert /usr/sbin/smail.real /usr/sbin/smail
11122 </example> If the diversion was added at a particular version, the
11123 postrm should also handle the failure case of upgrading from an
11124 older version (unless the older version is so old that direct
11125 upgrades are no longer supported):
11127 if [ abort-upgrade = "$1" ] && dpkg --compare-versions "$2" lt 1.0-2; then
11128 dpkg-divert --package smailwrapper --remove --rename \
11129 --divert /usr/sbin/smail.real /usr/sbin/smail
11131 </example> where <tt>1.02-2</tt> is the version at which the
11132 diversion was first added to the package. The postrm should not
11133 remove the diversion on upgrades both because there's no reason to
11134 remove the diversion only to immediately re-add it and since the
11135 postrm of the old package is run after unpacking so the removal of
11136 the diversion will fail.
11140 Do not attempt to divert a file which is vitally important for
11141 the system's operation - when using <prgn>dpkg-divert</prgn>
11142 there is a time, after it has been diverted but before
11143 <prgn>dpkg</prgn> has installed the new version, when the file
11144 does not exist.</p>
11149 <!-- Local variables: -->
11150 <!-- indent-tabs-mode: t -->
11152 <!-- vim:set ai et sts=2 sw=2 tw=76: -->