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;
8 Debian GNU/Linux Policy Manual.
9 Copyright (C)1996,1997,1998 Ian Jackson and Christian Schwarz;
10 released under the terms of the GNU
11 General Public License, version 2 or (at your option) any later.
12 Initial version 1996, Ian Jackson, ijackson@gnu.ai.mit.edu
13 Revised November 27, 1996, David A. Morris, bweaver@debian.org
14 New sections March 15, 1997, Christian Schwarz, schwarz@debian.org
15 Reworked/Restructured April-July 1997, Christian Schwarz, schwarz@debian.org
16 Maintainer since 1997, Christian Schwarz, schwarz@debian.org
17 Christoph Lameter contributed the "Web Standard"
18 The debian-policy mailing list has taken responsibility for the
19 contents of this document since September 1998, with the package
20 maintainers responsible for packaging administrivia only.
25 <title>Debian Policy Manual</title>
27 <name>Ian Jackson </name>
28 <email>ijackson@gnu.ai.mit.edu</email>
31 <name>Christian Schwarz</name>
32 <email>schwarz@debian.org</email>
35 <name>revised: David A. Morris</name>
36 <email>bweaver@debian.org</email>
39 <name>The Debian Policy mailing List</name>
40 <email>debian-policy@lists.debian.org</email>
42 <version>version &version;, &date;</version>
45 This manual describes the policy requirements for the Debian
46 GNU/Linux distribution. This includes the structure and
47 contents of the Debian archive, several design issues of the
48 operating system, as well as technical requirements that each
49 package must satisfy to be included in the distribution. The
50 policy package itself is maintained by a group of maintainers
51 that have no editorial powers. At the moment, the list of
55 <p>Michael Alan Dorman <email>mdorman@debian.org</email></p>
58 <p>Richard Braakman <email>dark@xs4all.nl</email></p>
61 <p>Philip Hands <email>phil@hands.com</email></p>
64 <p>Julian Gilbey <email>J.D.Gilbey@qmw.ac.uk</email></p>
67 <p>Manoj Srivastava <email>srivasta@debian.org</email></p>
75 Copyright ©1996,1997,1998 Ian Jackson
76 and Christian Schwarz.
79 This manual is free software; you may redistribute it and/or
80 modify it under the terms of the GNU General Public License
81 as published by the Free Software Foundation; either version
82 2, or (at your option) any later version.
86 This is distributed in the hope that it will be useful, but
87 <em>without any warranty</em>; without even the implied
88 warranty of merchantability or fitness for a particular
89 purpose. See the GNU General Public License for more
94 A copy of the GNU General Public License is available as
95 <tt>/usr/share/common-licences/GPL</tt> in the Debian GNU/Linux
96 distribution or on the World Wide Web at
97 <url id="http://www.gnu.org/copyleft/gpl.html"
98 name="The GNU Public Licence">. You can also obtain it by writing to the
99 Free Software Foundation, Inc., 59 Temple Place - Suite 330,
100 Boston, MA 02111-1307, USA.
108 <heading>About this manual</heading>
110 <heading>Scope</heading>
112 This manual describes the policy requirements for the Debian
113 GNU/Linux distribution. This includes the structure and
114 contents of the Debian archive, several design issues of the
115 operating system, as well as technical requirements that
116 each package must satisfy to be included in the
122 This manual also describes Debian policy as it relates to
123 creating Debian packages. It is not a tutorial on how to build
124 packages, nor is it exhaustive where it comes to describing
125 the behavior of the packaging system. Instead, this manual
126 attempts to define the interface to the package management
127 system that the developers have to be conversant with.
130 Informally, the criteria used for inclusion is that the
131 material meet one of the following requirements:
133 <tag>Standard interfaces</tag>
136 The material presented represents an interface to
137 the packaging system that is mandated for use, and
138 is used by, a significant number of packages, and
139 should not be changed without peer review. Package
140 maintainers can then rely on this interfaces not
141 changing, and the package management software
142 authors need to ensure compatibility with these
143 interface definitions. (control file and and
144 changelog file formats are one example)
147 <tag>Chosen Convention</tag>
150 If there are a number of technically viable choices
151 that can be made, but one needs to select one of
152 these options for inter-operability. The version
153 number format is one example.
157 Please note that these are not mutually exclusive;
158 selected conventions often become parts of standard
165 Please note that the footnotes present in this manual are
166 merely informative, and are not part of Debian policy itself.
171 In this manual, the words <em>must</em>, <em>should</em> and
172 <em>may</em>, and the adjectives <em>required</em>,
173 <em>recommended</em> and <em>optional</em>, are used to
174 distinguish the significance of the various guidelines in
175 this policy document. Packages that do not conform the the
176 guidelines denoted by <em>must</em> (or <em>required</em>)
177 will generally not be considered acceptable for the Debian
178 distribution. Non-conformance with guidelines denoted by
179 <em>should</em> (or <em>recommended</em>) will generally be
180 considered a bug, but will not necessarily render a package
181 unsuitable for distribution. Guidelines denoted by
182 <em>may</em> (or <em>optional</em>) are truly optional and
183 adherence is left to the maintainer's discretion.
186 These classifications are roughly equivalent to the bug
187 severities <em>important</em> (for <em>must</em> or
188 <em>required</em> directive violations), <em>normal</em>
189 (for <em>should</em> or <em>recommended</em> directive
190 violations) and <em>wishlist</em> (for <em>optional</em>
192 <p>Also see RFC 2119.</p>
196 Much of the information presented in this manual will be
197 useful even when building a package which is to be
198 distributed in some other way or is for local use.
202 <heading>New versions of this document</heading>
204 The current version of this document is always accessible from the
205 Debian FTP server <ftpsite>ftp.debian.org</ftpsite> at
206 <ftppath>/debian/doc/package-developer/debian-policy.html.tar.gz</ftppath>
207 or from the Debian WWW server at
208 <url id="http://www.debian.org/doc/debian-policy/"
209 name="The Debian Policy Manual">.</p>
212 In addition, this manual is distributed via the Debian package
213 <tt>debian-policy</tt>.
217 <heading>Feedback</heading>
220 As the Debian GNU/Linux system is continuously evolving this
221 manual is changed from time to time.
224 While the authors of this document tried hard not to include
225 any typos or other errors these still occur. If you discover
226 an error in this manual or if you want to tell us any
227 comments, suggestions, or critics please send an email to
228 the Debian Policy List,
229 <email>debian-policy@lists.debian.org</email>, or submit a
230 bug report against the <tt>debian-policy</tt> package.
235 <heading>The Debian Archive</heading>
237 The Debian GNU/Linux system is maintained and distributed as a
238 collection of <em>packages</em>. Since there are so many of them (over
239 5000) they are split into <em>sections</em> and <em>priorities</em> to
240 simplify handling of them.
243 The effort of the Debian project is to build a free operating
244 system, but not every package we want to make accessible is
245 <em>free</em> in our sense (see Debian Free Software
246 Guidelines, below), or may be imported/exported without
247 restrictions. Thus, the archive is split into the sections
248 <em>main</em>, <em>non-free</em>, <em>contrib</em>,
249 <em>non-US/main</em>, <em>non-US/non-free</em>, and
250 <em>non-US/contrib</em>.</p>
253 The <em>main</em> and the <em>non-US/main</em> sections form
254 the <em>Debian GNU/Linux distribution</em>.
258 Packages in the other sections are not considered as part of
259 the Debian distribution, though we support their use, and we
260 provide infrastructure for them (such as our bug-tracking
261 system and mailing lists). This Debian Policy Manual applies
262 to these packages as well.</p>
264 <sect id="pkgcopyright">
265 <heading>Package copyright and sections</heading>
267 The aims of this policy are:
269 <list compact="compact">
271 <p>We want to make as much software available as we
275 <p>We want to encourage everyone to write free software.</p>
278 <p> We want to make it easy for people to produce
279 CD-ROMs of our system without violating any licenses,
280 import/export restrictions, or any other laws.</p>
285 <heading>The Debian Free Software Guidelines</heading>
287 The Debian Free Software Guidelines (DFSG) is our
288 definition of `free' software.
290 <tag>Free Redistribution
294 The license of a Debian component may not restrict any
295 party from selling or giving away the software as a
296 component of an aggregate software distribution
297 containing programs from several different
298 sources. The license may not require a royalty or
299 other fee for such sale.
306 The program must include source code, and must allow
307 distribution in source code as well as compiled form.
314 The license must allow modifications and derived
315 works, and must allow them to be distributed under the
316 same terms as the license of the original software.
319 <tag>Integrity of The Author's Source Code
323 The license may restrict source-code from being
324 distributed in modified form <em>only</em> if the
325 license allows the distribution of ``patch files''
326 with the source code for the purpose of modifying the
327 program at build time. The license must explicitly
328 permit distribution of software built from modified
329 source code. The license may require derived works to
330 carry a different name or version number from the
331 original software. (This is a compromise. The Debian
332 group encourages all authors to not restrict any
333 files, source or binary, from being modified.)
336 <tag>No Discrimination Against Persons or Groups
340 The license must not discriminate against any person
344 <tag>No Discrimination Against Fields of Endeavor
348 The license must not restrict anyone from making use
349 of the program in a specific field of endeavor. For
350 example, it may not restrict the program from being
351 used in a business, or from being used for genetic
355 <tag>Distribution of License
359 The rights attached to the program must apply to all
360 to whom the program is redistributed without the need
361 for execution of an additional license by those
365 <tag>License Must Not Be Specific to Debian
369 The rights attached to the program must not depend on
370 the program's being part of a Debian system. If the
371 program is extracted from Debian and used or
372 distributed without Debian but otherwise within the
373 terms of the program's license, all parties to whom
374 the program is redistributed must have the same
375 rights as those that are granted in conjunction with
379 <tag>License Must Not Contaminate Other Software
383 The license must not place restrictions on other
384 software that is distributed along with the licensed
385 software. For example, the license must not insist
386 that all other programs distributed on the same medium
387 must be free software.
390 <tag>Example Licenses
394 The ``GPL,'' ``BSD,'' and ``Artistic'' licenses are
395 examples of licenses that we consider <em>free</em>.
402 <heading>The main section</heading>
404 Every package in "main" and "non-US/main" must comply with
405 the DFSG (Debian Free Software Guidelines).</p>
408 In addition, the packages in "main"
409 <list compact="compact">
412 must not require a package outside of "main" for
413 compilation or execution (thus, the package must not
414 declare a "Depends", "Recommends", or
415 "Build-Depends" relationship on a non-main package),
420 must not be so buggy that we refuse to support them,
425 must meet all policy requirements presented in this
432 Similarly, the packages in "non-US/main"
433 <list compact="compact">
436 must not require a package outside of "main" or
437 "non-US/main" for compilation or execution,
442 must not be so buggy that we refuse to support them,
447 must meet all policy requirements presented in this
455 <heading>The contrib section</heading>
457 Every package in "contrib" and "non-US/contrib" must
458 comply with the DFSG.
462 Examples of packages which would be included in "contrib"
463 or "non-US/contrib" are
464 <list compact="compact">
467 free packages which require "contrib", "non-free"
468 packages or packages which are not in our
469 archive at all for compilation or execution,
474 wrapper packages or other sorts of free accessories for
482 <heading>The non-free section and non-US/non-free </heading>
484 Packages must be placed in "non-free" or "non-US/non-free"
485 if they are not compliant with the DFSG or are encumbered
486 by patents or other legal issues that make their
487 distribution problematic.
491 <heading>The non-US sections</heading>
493 Some programs with cryptographic program code need to be stored
494 on the "non-US" server because of export restrictions of the
495 U.S. Such programs must be distributed in the appropriate
496 non-US section, either non-US/main, non-US/contrib or
497 non-US/non-free. </p>
499 This applies only to packages which contain cryptographic
500 code. A package containing a program with an interface to a
501 cryptographic program or a program that's dynamically linked
502 against a cryptographic library should not be distributed
503 via the non-us server if it is capable of running without the
504 cryptography library or program.
508 <heading>Further copyright considerations</heading>
510 Every package must be accompanied by a verbatim copy of its
511 copyright and distribution license in the file
512 /usr/share/doc/<package-name>/copyright (see
513 <ref id="copyrightfile"> for details).</p>
515 We reserve the right to restrict files from being included
516 anywhere in our archives if
517 <list compact="compact">
520 their use or distribution would break a law,
525 there is an ethical conflict in their distribution or
531 we would have to sign a license for them, or
536 their distribution would conflict with other project
544 Programs whose authors encourage the user to make donations
545 are fine for the main distribution, provided that the
546 authors do not claim that not donating is immoral,
547 unethical, illegal or something similar; otherwise they must
551 Packages whose copyright permission notices (or patent
552 problems) do not allow redistribution even of only binaries,
553 and where no special permission has been obtained, must not be
554 placed on the Debian FTP site and its mirrors at all.</p>
557 Note, that under international copyright law (this applies
558 in the United States, too) <em>no</em> distribution or
559 modification of a work is allowed without an explicit notice
560 saying so. Therefore a program without a copyright notice
561 <em>is</em> copyrighted and you may not do anything to it
562 without risking being sued! Likewise if a program has a
563 copyright notice but no statement saying what is permitted
564 then nothing is permitted.</p>
567 Many authors are unaware of the problems that restrictive
568 copyrights (or lack of copyright notices) can cause for the
569 users of their supposedly-free software. It is often
570 worthwhile contacting such authors diplomatically to ask
571 them to modify their license terms. However, this is a
572 politically difficult thing to do and you should ask for
573 advice on <tt>debian-legal</tt> first.</p>
576 When in doubt, send mail to
577 <email>debian-legal@lists.debian.org</email>. Be prepared
578 to provide us with the copyright statement. Software
579 covered by the GPL, public domain software and BSD-like
580 copyrights are safe; be wary of the phrases `commercial use
581 prohibited' and `distribution restricted'.</p>
584 <heading>Subsections</heading>
587 The packages in all the sections (<em>main</em>,
588 <em>contrib</em>, <em>non-US/main</em>, <em>non-free</em>,
589 <em>non-US/contrib</em>, and <em>non-US/non-free</em>) are
590 grouped further into <em>subsections</em> to simplify
594 The section for each package should be specified in the
595 package's <em>control record</em>. However, the maintainer of
596 the Debian archive may override this selection to assure the
597 consistency of the Debian distribution. </p>
600 Please check the current Debian distribution to see which
601 sections are available.</p>
604 <heading>Priorities</heading>
607 Each package should have a <em>priority</em> value,
608 which is included in the package's <em>control
609 record</em>. This information is used in the Debian package
610 management tool to separate high-priority packages from
611 less-important packages.</p>
614 The following <em>priority levels</em> are supported by the
615 Debian package management system, <prgn>dpkg</prgn>.
617 <tag><tt>required</tt></tag>
620 <tt>required</tt> packages are necessary for the
621 proper functioning of the system. You must not remove
622 these packages or your system may become totally
623 broken and you may not even be able to use
624 <prgn>dpkg</prgn> to put things back. Systems with
625 only the <tt>required</tt> packages are probably
626 unusable, but they do have enough functionality to
627 allow the sysadmin to boot and install more
630 <tag><tt>important</tt></tag>
633 Important programs, including those which one would
634 expect to find on any Unix-like system. If the
635 expectation is that an experienced Unix person who
636 found it missing would say `What the F*!@<+ is
637 going on, where is <prgn>foo</prgn>', it must be in
638 <tt>important</tt>. This is an important criterion
639 because we are trying to produce, amongst other
640 things, a free Unix. Other packages without which the
641 system will not run well or be usable must also be
642 here. This does <em>not</em> include Emacs, the X
643 Window System, TeX or any other large applications.
644 The <tt>important</tt> packages are just a bare
645 minimum of commonly-expected and necessary tools.</p>
647 <tag><tt>standard</tt></tag>
650 These packages provide a reasonably small but not too
651 limited character-mode system. This is what will
652 install by default if the user doesn't select anything
653 else. It doesn't include many large applications, but
654 it does include Emacs (this is more of a piece of
655 infrastructure than an application) and a reasonable
656 subset of TeX and LaTeX (if this is possible without
659 <tag><tt>optional</tt></tag>
662 (In a sense everything is optional that isn't
663 required, but that's not what is meant here.) This is
664 all the software that you might reasonably want to
665 install if you didn't know what it was or don't have
666 specialized requirements. This is a much larger system
667 and includes the X Window System, a full TeX distribution,
668 and many applications. Note that optional packages should
669 not conflict with each other.
672 <tag><tt>extra</tt></tag>
675 This contains all packages that conflict with others
676 with required, important, standard or optional
677 priorities, or are only likely to be useful if you
678 already know what they are or have specialised
685 Packages must not depend on packages with lower priority
686 values (excluding build-time dependencies). In order to
687 ensure this, the priorities of one or more packages must
693 <heading>Binary packages</heading>
696 The Debian GNU/Linux distribution is based on the Debian
697 package management system, called <prgn>dpkg</prgn>. Thus,
698 all packages in the Debian distribution must be provided
699 in the <tt>.deb</tt> file format.</p>
703 <heading>The package name</heading>
706 Every package must have a name that's unique within the Debian
710 Package names must only consist of lower case letters, digits (0-9),
711 plus (+) or minus (-) signs, and periods (.).</p>
714 The package name is part of the file name of the
715 <tt>.deb</tt> file and is included in the control field
721 <heading>The maintainer of a package</heading>
723 Every package must have a maintainer (the maintainer may
724 be one person or a group of people reachable from a common
725 email address, such as a mailing list). The maintainer is
726 responsible for ensuring that the package is placed in
727 the appropriate distribution
731 The maintainer must be specified in the
732 <tt>Maintainer</tt> control field with the correct name
733 and a working email address for the Debian maintainer of
734 the package. If one person maintains several packages
735 he/she should try to avoid having different forms of their
736 name and email address in different <tt>Maintainer</tt>
740 If the maintainer of a package quits from the Debian
741 project the Debian QA Group
742 <email>debian-qa@lists.debian.org</email> takes over the
743 maintainership of the package until someone else
744 volunteers for that task. These packages are called
745 <em>orphaned packages</em>.
751 <heading>The description of a package</heading>
754 Every Debian package must have an extended description
755 stored in the appropriate field of the control record.</p>
758 The description should be written so that it tells the user
759 what they need to know to decide whether to install the
760 package. This description should not just be copied from
761 the blurb for the program. Instructions for configuring
762 or using the package should not be included -- that is what
763 installation scripts, manual pages, Info files, etc. are
764 for. Copyright statements and other administrivia should
765 not be included -- that is what the copyright file is
771 <heading>Dependencies</heading>
774 Every package must specify the dependency information
775 about other packages that are required for the first to
779 For example, a dependency entry must be provided for any
780 shared libraries required by a dynamically-linked executable
781 binary in a package.</p>
784 Packages are not required to declare any dependencies they
785 have on other packages which are marked <tt>Essential</tt>
786 (see below), and should not do so unless they depend on a
787 particular version of that package.</p>
790 Sometimes, a package requires another package to be installed
791 <em>and</em> configured before it can be installed. In this
792 case, you must specify a <tt>Pre-Depends</tt> entry for
796 You should not specify a <tt>Pre-Depends</tt> entry for a
797 package before this has been discussed on the
798 <tt>debian-devel</tt> mailing list and a consensus about
799 doing that has been reached.</p></sect1>
803 <heading>Virtual packages</heading>
806 Sometimes, there are several packages doing more-or-less
807 the same job. In this case, it's useful to define a
808 <em>virtual package</em> whose name describes the function
809 the packages have. (The virtual packages just exist
810 logically, not physically--that's why they are called
811 <em>virtual</em>.) The packages with this particular
812 function will then <em>provide</em> the virtual
813 package. Thus, any other package requiring that function
814 can simply depend on the virtual package without having to
815 specify all possible packages individually.</p>
818 All packages should use virtual package names where
819 appropriate, and arrange to create new ones if necessary.
820 They should not use virtual package names (except privately,
821 amongst a cooperating group of packages) unless they have
822 been agreed upon and appear in the list of virtual package
826 The latest version of the authoritative list of virtual
827 package names can be found on
828 <ftpsite>ftp.debian.org</ftpsite> in
829 <ftppath>/debian/doc/package-developer/virtual-package-names-list.text</ftppath>
830 or your local mirror. In addition, it is included in the
831 <tt>debian-policy</tt> package. The procedure for updating
832 the list is described at the top of the file.</p></sect1>
836 <heading>Base packages</heading>
839 The packages included in the <tt>base</tt> section have a
840 special function. They form a minimum subset of the Debian
841 GNU/Linux system that is installed before everything else
842 on a new system. Thus, only very few packages are allowed
843 to go into the <tt>base</tt> section to keep the required
844 disk usage very small.</p>
847 Most of these packages will have the priority value
848 <tt>required</tt> or at least <tt>important</tt>, and many
849 of them will be tagged <tt>essential</tt> (see below).</p>
852 You must not place any packages into the <tt>base</tt>
853 section before this has been discussed on the
854 <tt>debian-devel</tt> mailing list and a consensus about
855 doing that has been reached.</p></sect1>
859 <heading>Essential packages</heading>
862 Some packages are tagged <tt>essential</tt>. (They have
863 <tt>Essential: yes</tt> in their package control record.)
864 This flag is used for packages that are <em>essential</em>
868 Since these packages can not easily be removed (you'll
869 have to specify an extra <em>force option</em> to
870 <prgn>dpkg</prgn>) this flag must not be used unless
871 absolutely necessary. A shared library package must not
872 be tagged <tt>essential</tt>--the dependencies will
873 prevent its premature removal, and we need to be able to
874 remove it when it has been superseded.
878 Since dpkg will not prevent upgrading of other packages
879 while an <tt>essential</tt> package is in an unconfigured
880 state, all <tt>essential</tt> packages must supply all
881 their core functionality even when unconfigured. If the
882 package cannot satisfy this requirement it must not be
883 tagged as essential, and any packages depending on this
884 package must instead have explicit dependency fields as
889 You must not tag any packages <tt>essential</tt> before
890 this has been discussed on the <tt>debian-devel</tt>
891 mailing and a consensus about doing that has been
896 <heading>Maintainer scripts</heading>
899 The package installation scripts should avoid producing
900 output which it is unnecessary for the user to see and
901 should rely on <prgn>dpkg</prgn> to stave off boredom on
902 the part of a user installing many packages. This means,
903 amongst other things, using the <tt>--quiet</tt> option on
904 <prgn>install-info</prgn>.</p>
907 Errors which occur during the execution of an installation
908 script must be checked and the installation must not
909 continue after an error.
913 Note, that <ref id="scripts">, in general applies to package
914 maintainer scripts, too.
918 You should not use <tt>dpkg-divert</tt>' on a file
919 belonging to another package without consulting the
920 maintainer of that package first.
923 All packages which supply an instance of a common command
924 name (or, in general, filename) should generally use
925 <prgn>update-alternatives</prgn>, so that they may be
926 installed together. If <prgn>update-alternatives</prgn>
927 is not used, then each package must use
928 <var>Conflicts</var> to ensure that other packages are
929 de-installed. (In this case, it may be appropriate to
930 specify a conflict against earlier versions of something
931 that previously did not use
932 <prgn>update-alternatives</prgn> - this is an exception to
933 the usual rule that this not allowed).
938 <heading>Prompting in maintainer scripts</heading>
940 Package maintainer scripts may prompt the user if
941 necessary. Prompting may be accomplished by hand, or by
942 communicating with a program, such as
943 <prgn>debconf</prgn>, which conforms to the Debian
944 Configuration management specification, version 2 or
945 higher. (Included in the
946 <file>debconf_specification</file> files in the
947 <package>debian-policy</package> package.)
948 You may also find this file on the FTP site
949 <ftpsite>ftp.debian.org</ftpsite> in
950 <ftppath>/debian/doc/package-developer/debconf_specification.txt.gz</ftppath>
951 or your local mirror.
954 2.5% of Debian packages
955 [<url id="http://kitenet.net/programs/debconf/stats/">]
956 use debconf to prompt the user at install time, and
957 this number is growing daily. The benefits of using
958 debconf are briefly explained at
959 <url id="http://kitenet.net/doc/debconf-doc/introduction.html">;
960 they include preconfiguration, (mostly)
961 noninteractive installation, elimination of
962 redundant prompting, consistency of user interface,
966 With this increasing number of packages using
967 debconf, plus the existance of a nascent second
968 implementation of the Debian configuration
969 management system (<package>cdebconf</package>), and
970 the stabalization of the protocol these things use,
971 the time has finally come to reflect the use of
972 these things in policy.
978 Packages which use the Debian Configuration management
979 specification may contain an additional
980 <file>config</file> script and a <file>templates</file>
981 file in their control archive. The <prgn>config</prgn>
982 script can be run before the preinst, and before the
983 package is unpacked or any of its dependancies or
984 pre-dependancies are satisfied, so it must work using
985 only the tools present in the <em>Essential</em>
989 Debconf or another tool that implements the Debian
990 Configuration management specification will also be
991 installed, and any versioned dependancies on it will
992 be satisfied before preconfiguration begins.
998 Packages should try to minimize the amount of prompting
999 they need to do, and they should ensure that the user
1000 will only ever be asked each question once. This means
1001 that packages should try to use appropriate shared
1002 configuration files (such as <tt>/etc/papersize</tt> and
1003 <tt>/etc/news/server</tt>), and shared debconf variables
1004 rather than each prompting for their own list of
1005 required pieces of information.
1009 It also means that an upgrade should not ask the same
1010 questions again, unless the user has used <tt>dpkg
1011 --purge</tt> to remove the package's configuration. The
1012 answers to configuration questions should be stored in an
1013 appropriate place in <tt>/etc</tt> so that the user can
1014 modify them, and how this has been done should be
1018 If a package has a vitally important piece of
1019 information to pass to the user (such as "don't run me
1020 as I am, you must edit the following configuration files
1021 first or you risk your system emitting badly-formatted
1022 messages"), it should display this in the
1023 <prgn>config</prgn> or <prgn>postinst</prgn> script and
1024 prompt the user to hit return to acknowledge the
1025 message. Copyright messages do not count as vitally
1026 important (they belong in
1027 <tt>/usr/share/doc/<var>package</var>/copyright</tt>);
1028 neither do instructions on how to use a program (these
1029 should be in on line documentation, where all the users
1033 Any necessary prompting should almost always be confined
1034 to the <prgn>config</prgn> or <prgn>postinst</prgn>
1035 script. If it is done in the <prgn>postinst</prgn>, it
1036 should be protected with a conditional so that unnecessary
1037 prompting doesn't happen if a package's installation fails
1038 and the <prgn>postinst</prgn> is called with
1039 <tt>abort-upgrade</tt>, <tt>abort-remove</tt> or
1040 <tt>abort-deconfigure</tt>.</p>
1045 <heading>Source packages</heading>
1048 <heading>Standards conformance</heading>
1051 You should specify the most recent version of the
1052 packaging standards with which your package complies in
1053 the source package's <tt>Standards-Version</tt> field.</p>
1056 This value will be used to file bug reports automatically
1057 if your package becomes too much out of date.</p>
1060 The value corresponds to a version of the Debian manuals,
1061 as can be found on the title page or page headers and
1062 footers (depending on the format).</p>
1065 The version number has four components--major and minor
1066 number and major and minor patch level. When the
1067 standards change in a way that requires every package to
1068 change the major number will be changed. Significant
1069 changes that will require work in many packages will be
1070 signaled by a change to the minor number. The major patch
1071 level will be changed for any change to the meaning of the
1072 standards, however small; the minor patch level will be
1073 changed when only cosmetic, typographical or other edits
1074 which do not change the meaning are made, or changes which
1075 do not affect the contents of packages.</p>
1078 For package maintainers, only the first 3 digits of the
1079 manual version are significant in representing the
1080 <em>Standards-Version</em>, and either these 3 digits or
1081 the complete 4 digits may be specified.
1084 In the past, people specified 4 digits in the
1085 Standards-Version field, like `2.3.0.0'. Since any
1086 `patch-level changes' don't introduce new policy, it
1087 was thought it would be better to relax policy and
1088 only require that the first 3 digits are specified. (4
1089 digits may still be used if someone wants to do so.)
1095 You should regularly, and especially if your package has
1096 become out of date, check for the newest Policy Manual
1097 available and update your package, if necessary. When your
1098 package complies with the new standards you should update the
1099 <tt>Standards-Version</tt> source package field and
1100 release it.</p></sect1>
1104 <heading>Package relationships</heading>
1107 Source packages should specify which binary packages they
1108 require to be installed or not to be installed in order to
1109 build correctly. For example, if building a package
1110 requires a certain compiler, then the compiler should be
1111 specified as a build-time dependency.
1115 It is not necessary to explicitly specify build-time
1116 relationships on a minimal set of packages that are always
1117 needed to compile, link and put in a Debian package a
1118 standard "Hello World!" program written in C or C++. The
1119 required packages are called <em>build-essential</em>, and
1120 an informational list can be found in
1121 <tt>/usr/share/doc/build-essential/list</tt> (which is
1122 contained in the <tt>build-essential</tt>
1128 <p>This allows maintaining the list separately
1129 from the policy documents (the list does not
1130 need the kind of control that the policy
1136 Having a separate package allows one to nistall
1137 the build essential packages on a machine, as
1138 well as allowing other packages (think task
1139 packages) to bring in the build-essential
1140 packages using the depends relation
1145 The separate package allows bug reports against
1146 the package to be categorized separately from
1147 the policy management process that uses the BTS
1157 When specifying the set of build-time dependencies, one
1158 should list only those packages explicitly required by the
1159 build. It is not necessary to list packages which are
1160 required merely because some other package in the list of
1161 build-time dependencies depends on them. The reason is
1162 that dependencies change, and you should list only those
1163 <em>you</em> need. What others need is their business.
1167 If build-time dependencies are specified, it must be
1168 possible to build the package and produce working binaries
1169 on a system with the build-essential packages installed
1170 and satisfying the build-time relationships (including any
1171 implied relationships). This
1172 means in particular that version clauses should be used
1173 rigorously in build-time relationships so that one cannot
1174 produce bad or inconsistently configured packages when the
1175 relationships are properly satisfied.
1179 <heading>Changes to the upstream sources</heading>
1182 If changes to the source code are made that are generally
1183 applicable, they should be sent to the upstream authors
1184 in whatever form they prefer so as to be included in the
1185 upstream version of the package.</p>
1188 If you need to configure the package differently for
1189 Debian or for Linux, and the upstream source doesn't
1190 provide a way to configure it the way you need to, you
1191 should add such configuration facilities (for example, a new
1192 <prgn>autoconf</prgn> test or <tt>#define</tt>) and send
1193 the patch to the upstream authors, with the default set to
1194 the way they originally had it. You can then easily
1195 override the default in your <tt>debian/rules</tt> or
1196 wherever is appropriate.</p>
1199 You should make sure that the <prgn>configure</prgn> utility
1200 detects the correct architecture specification string
1201 (refer to <ref id="arch-spec"> for details).</p>
1204 If you need to edit a <prgn>Makefile</prgn> where
1205 GNU-style <prgn>configure</prgn> scripts are used, you
1206 should edit the <tt>.in</tt> files rather than editing the
1207 <prgn>Makefile</prgn> directly. This allows the user to
1208 reconfigure the package if necessary. You should
1209 <em>not</em> configure the package and edit the generated
1210 <prgn>Makefile</prgn>! This makes it impossible for
1211 someone else to later reconfigure the package.</p></sect1>
1215 <heading>Documenting your changes</heading>
1218 You should document your changes and updates to the source
1219 package properly in the <tt>debian/changelog</tt> file. (Note
1220 that mistakes in changelogs are usually best rectified by
1221 making a new changelog entry rather than "rewriting history"
1222 by editing old changelog entries)</p>
1225 In non-experimental packages you must only use a format for
1226 <tt>debian/changelog</tt> which is supported by the most
1227 recent released version of <prgn>dpkg</prgn>. If your
1228 format is not supported and there is general support for
1229 it you should contact the <prgn>dpkg</prgn> maintainer to
1230 have the parser script for your format included in the
1231 <prgn>dpkg</prgn> package. (You will need to agree that
1232 the parser and its manpage may be distributed under the
1233 GNU GPL, just as the rest of <prgn>dpkg</prgn>
1238 <heading>Error trapping in makefiles</heading>
1241 When <prgn>make</prgn> invokes a command in a makefile
1242 (including your package's upstream makefiles and the
1243 <tt>debian/rules</tt>) it does so using <tt>sh</tt>. This
1244 means that <tt>sh</tt>'s usual bad error handling
1245 properties apply: if you include a miniature script as one
1246 of the commands in your makefile you'll find that if you
1247 don't do anything about it then errors are not detected
1248 and <prgn>make</prgn> will blithely continue after
1252 Every time you put more than one shell command (this
1253 includes using a loop) in a makefile command you
1254 must make sure that errors are trapped. For
1255 simple compound commands, such as changing directory and
1256 then running a program, using <tt>&&</tt> rather
1257 than semicolon as a command separator is sufficient. For
1258 more complex commands including most loops and
1259 conditionals you should include a separate <tt>set -e</tt>
1260 command at the start of every makefile command that's
1261 actually one of these miniature shell scripts.</p></sect1>
1265 <heading>Obsolete constructs and libraries</heading>
1268 The include file <prgn><varargs.h></prgn> is
1269 provided to support end-users compiling very old software;
1270 the library <tt>libtermcap</tt> is provided to support the
1271 execution of software which has been linked against it
1272 (either old programs or those such as Netscape which are
1273 only available in binary form).</p>
1276 Debian packages should be ported to include
1277 <prgn><stdarg.h></prgn> and <tt>ncurses</tt> when
1283 <chapt id="controlfields"><heading>Control files and their fields</heading>
1286 Many of the tools in the package management suite manipulate
1287 data in a common format, known as control files. Binary and
1288 source packages have control data as do the <tt>.changes</tt>
1289 files which control the installation of uploaded files, and
1290 <prgn>dpkg</prgn>'s internal databases are in a similar
1294 <sect><heading>Syntax of control files</heading>
1297 A file consists of one or more paragraphs of fields. The
1298 paragraphs are separated by blank lines. Some control files
1299 only allow one paragraph; others allow several, in which
1300 case each paragraph often refers to a different package.
1304 Each paragraph is a series of fields and values; each field
1305 consists of a name, followed by a colon and the value. It
1306 ends at the end of the line. Horizontal whitespace (spaces
1307 and tabs) may occur immediately before or after the value
1308 and is ignored there; it is conventional to put a single
1309 space after the colon.
1313 Some fields' values may span several lines; in this case
1314 each continuation line <em>must</em> start with a space or
1315 tab. Any trailing spaces or tabs at the end of individual
1316 lines of a field value are ignored.
1320 Except where otherwise stated only a single line of data is
1321 allowed and whitespace is not significant in a field body.
1322 Whitespace may never appear inside names (of packages,
1323 architectures, files or anything else), version numbers or
1324 in between the characters of multi-character version
1329 Field names are not case-sensitive, but it is usual to
1330 capitalize the field names using mixed case as shown below.
1334 Blank lines, or lines consisting only of spaces and tabs,
1335 are not allowed within field values or between fields - that
1336 would mean a new paragraph.
1340 It is important to note that there are several fields which
1341 are optional as far as <prgn>dpkg</prgn> and the related
1342 tools are concerned, but which must appear in every Debian
1343 package, or whose omission may cause problems. When writing
1344 the control files for Debian packages you <em>must</em> read
1345 the Debian policy manual in conjunction with the details
1346 below and the list of fields for the particular file.</p>
1349 <sect><heading>List of fields</heading>
1351 This list here is not supposed to be exhaustive. Typically
1352 only fields for whom policy exists are mentioned here.
1354 <sect1 id="f-Package"><heading><tt>Package</tt>
1358 The name of the binary package. Package names consist of
1359 the alphanumerics and <tt>+</tt> <tt>-</tt> <tt>.</tt>
1360 (plus, minus and full stop).
1364 They must be at least two characters long and must start
1365 with an alphanumeric character. The use lowercase package
1366 names is strongly recommended unless the package you're
1367 building (or referring to, in other fields) is already
1368 using uppercase.</p>
1371 <sect1 id="f-Version"><heading><tt>Version</tt>
1375 This lists the source or binary package's version number -
1376 see <ref id="versions">.
1382 id="f-Standards-Version"><heading><tt>Standards-Version</tt>
1386 The most recent version of the standards (the packaging
1387 and policy manuals and associated texts) with which the
1388 package complies. This is updated manually when editing
1389 the source package to conform to newer standards; it can
1390 sometimes be used to tell when a package needs attention.
1394 Its format is the same as that of a version number except
1395 that no epoch or Debian revision is allowed - see <ref
1400 <sect1 id="f-Distribution"><heading><tt>Distribution</tt>
1404 In a <tt>.changes</tt> file or parsed changelog output
1405 this contains the (space-separated) name(s) of the
1406 distribution(s) where this version of the package should
1407 be or was installed. Distribution names follow the rules
1408 for package names. (See <ref id="f-Package">).
1413 Current distribution values are:
1415 <tag><em>stable</em></tag>
1418 This is the current `released' version of Debian
1420 distribution is <em>stable</em> only major bug fixes
1421 are allowed. When changes are made to this
1422 distribution, the release number is increased
1423 (for example: 1.2r1 becomes 1.2r2 then 1.2r3, etc).
1427 <tag><em>unstable</em></tag>
1430 This distribution value refers to the
1431 <em>developmental</em> part of the Debian
1432 distribution tree. New packages, new upstream
1433 versions of packages and bug fixes go into the
1434 <em>unstable</em> directory tree. Download from
1435 this distribution at your own risk.
1439 <tag><em>frozen</em></tag>
1442 From time to time, the <em>unstable</em>
1443 distribution enters a state of `code-freeze' in
1444 anticipation of release as a <em>stable</em>
1445 version. During this period of testing only
1446 fixes for existing or newly-discovered bugs will
1451 <tag><em>experimental</em></tag>
1454 The packages with this distribution value are deemed
1455 by their maintainers to be high risk. Oftentimes they
1456 represent early beta or developmental packages from
1457 various sources that the maintainers want people to
1458 try, but are not ready to be a part of the other parts
1459 of the Debian distribution tree. Download at your own
1464 There are several sections in each
1465 distribution. Currently, these sections are:
1468 <tag><em>contrib</em></tag>
1471 The packages in this section do not meet the
1472 criteria for inclusion in the main Debian
1473 distribution as defined by the Policy Manual,
1474 but are otherwise free, as defined by the Debian
1475 free software guidelines.</p>
1478 <tag><em>non-free</em></tag>
1481 Packages in <em>non-free</em> do not meet the
1482 criteria of free software, as defined by the
1483 Debian free software guidelines. Again, use your
1484 best judgment in downloading from this
1488 </taglist> You should list <em>all</em> distributions that
1489 the package should be installed into. Except in unusual
1490 circumstances, installations to <em>stable</em> should also
1491 go into <em>frozen</em> (if it exists) and
1492 <em>unstable</em>. Likewise, installations into
1493 <em>frozen</em> should also go into <em>unstable</em>.
1502 <chapt id="versions"><heading>Version numbering </heading>
1505 Every package has a version number, in its <tt>Version</tt>
1510 The package management system imposes an ordering on version
1511 numbers, so that it can tell whether packages are being up- or
1512 downgraded and so that package system front end applications
1513 can tell whether a package it finds available is newer than
1514 the one installed on the system. The version number format
1515 has the most significant parts (as far as comparison is
1516 concerned) at the beginning.
1520 The version number format is:
1521 &lsqb<var>epoch</var><tt>:</tt>]<var>upstream-version</var>[<tt>-/<var>debian-revision</var>].</tt>
1525 The three components here are:
1527 <tag><var>epoch</var></tag>
1531 This is a single (generally small) unsigned integer. It
1532 may be omitted, in which case zero is assumed. If it is
1533 omitted then the <var>upstream-version</var> may not
1538 It is provided to allow mistakes in the version numbers
1539 of older versions of a package, and also a package's
1540 previous version numbering schemes, to be left behind.
1545 <tag><var>upstream-version</var></tag>
1549 This is the main part of the version. It is usually
1550 version number of the original (`upstream') package of
1551 which the <tt>.deb</tt> file has been made, if this is
1552 applicable. Usually this will be in the same format as
1553 that specified by the upstream author(s); however, it
1554 may need to be reformatted to fit into the package
1555 management system's format and comparison scheme.
1559 The comparison behavior of the package management system
1560 with respect to the <var>upstream-version</var> is
1561 described below. The <var>upstream-version</var>
1562 portion of the version number is mandatory.
1566 The <var>upstream-version</var> may contain only
1567 alphanumerics and the characters <tt>.</tt> <tt>+</tt>
1568 <tt>-</tt> <tt>:</tt> (full stop, plus, hyphen, colon)
1569 and should start with a digit. If there is no
1570 <var>debian-revision</var> then hyphens are not allowed;
1571 if there is no <var>epoch</var> then colons are not
1575 <tag><var>debian-revision</var></tag>
1579 This part of the version represents the version of the
1580 modifications that were made to the package to make it a
1581 Debian binary package. It is in the same format as the
1582 <var>upstream-version</var> and is compared in the same
1587 It is optional; if it isn't present then the
1588 <var>upstream-version</var> may not contain a hyphen.
1589 This format represents the case where a piece of
1590 software was written specifically to be turned into a
1591 Debian binary package, and so there is only one
1592 `debianization' of it and therefore no revision
1593 indication is required.
1597 It is conventional to restart the
1598 <var>debian-revision</var> at <tt>1</tt> each time the
1599 <var>upstream-version</var> is increased.
1603 The package management system will break the
1604 <var>upstream-version</var> and
1605 <var>debian-revision</var> apart at the last hyphen in
1606 the string. The absence of a <var>debian-revision</var>
1607 compares earlier than the presence of one (but note that
1608 the <var>debian-revision</var> is the least significant
1609 part of the version number).
1613 The <var>debian-revision</var> may contain only
1614 alphanumerics and the characters <tt>+</tt> and
1615 <tt>.</tt> (plus and full stop).
1619 The <var>upstream-version</var> and <var>debian-revision</var>
1620 parts are compared by the package management system using the
1625 The strings are compared from left to right.
1629 First the initial part of each string consisting entirely of
1630 non-digit characters is determined. These two parts (one of
1631 which may be empty) are compared lexically. If a difference
1632 is found it is returned. The lexical comparison is a
1633 comparison of ASCII values modified so that all the letters
1634 sort earlier than all the non-letters.
1638 Then the initial part of the remainder of each string which
1639 consists entirely of digit characters is determined. The
1640 numerical values of these two parts are compared, and any
1641 difference found is returned as the result of the comparison.
1642 For these purposes an empty string (which can only occur at
1643 the end of one or both version strings being compared) counts
1648 These two steps are repeated (chopping initial non-digit
1649 strings and initial digit strings off from the start) until a
1650 difference is found or both strings are exhausted.
1654 Note that the purpose of epochs is to allow us to leave behind
1655 mistakes in version numbering, and to cope with situations
1656 where the version numbering changes. It is <em>not</em> there
1657 to cope with version numbers containing strings of letters
1658 which the package management system cannot interpret (such as
1659 <tt>ALPHA</tt> or <tt>pre-</tt>), or with silly orderings (the
1660 author of this manual has heard of a package whose versions
1661 went <tt>1.1</tt>, <tt>1.2</tt>, <tt>1.3</tt>, <tt>1</tt>,
1662 <tt>2.1</tt>, <tt>2.2</tt>, <tt>2</tt> and so forth).
1666 If an upstream package has problematic version numbers they
1667 should be converted to a sane form for use in the
1668 <tt>Version</tt> field.
1672 <heading>Version numbers based on dates</heading>
1674 In general, Debian packages should use the same version
1675 numbers as the upstream sources.</p>
1678 However, in some cases where the upstream version number is
1679 based on a date (e.g., a development `snapshot' release) the
1680 package management system cannot handle these version
1681 numbers without epochs. For example, dpkg will consider
1682 `96May01' to be greater than `96Dec24'.</p>
1685 To prevent having to use epochs for every new upstream
1686 version, the version number should be changed to the
1687 following format in such cases: `19960501', `19961224'. It
1688 is up to the maintainer whether he/she wants to bother the
1689 upstream maintainer to change the version numbers upstream,
1693 Note, that other version formats based on dates which are
1694 parsed correctly by the package management system should
1695 <em>not</em> be changed.</p>
1698 Native Debian packages (i.e., packages which have been
1699 written especially for Debian) whose version numbers include
1700 dates should always use the `YYYYMMDD' format.</p>
1704 <chapt id="miscellaneous"><heading>Packaging Considerations</heading>
1706 <sect id="timestamps"><heading>Time Stamps</heading>
1708 Maintainers are encouraged to preserve the modification
1709 times of the upstream source files in a package, as far as
1710 is reasonably possible. Even though this is optional, this
1711 is still a good idea.
1714 The rationale is that there is some information conveyed
1715 by knowing the age of the file, for example, you could
1716 recognize that some documentation is very old by looking
1717 at the modification time, so it would be nice if the
1718 modification time of the upstream source would be
1725 <sect id="debianrules"><heading><tt>debian/rules</tt> - the
1726 main building script </heading>
1729 This file must be an executable makefile, and contains the
1730 package-specific recipes for compiling the package and
1731 building binary package(s) out of the source.
1735 It must start with the line <tt>#!/usr/bin/make -f</tt>,
1736 so that it can be invoked by saying its name rather than
1737 invoking <prgn>make</prgn> explicitly.
1741 Since an interactive <tt>debian/rules</tt> script makes it
1742 impossible to auto-compile that package and also makes it
1743 hard for other people to reproduce the same binary
1744 package, all <strong>required targets</strong> MUST be
1745 non-interactive. At a minimum, required targets are the
1746 ones called by <prgn>dpkg-buildpackage</prgn>, namely,
1747 <em>clean</em>, <em>binary</em>, <em>binary-arch</em>, and
1748 <em>build</em>. It also follows that any target that these
1749 targets depend on must also be non-interactive.
1753 The targets which must be present are:
1755 <tag><tt>build</tt></tag>
1758 This should perform all non-interactive
1759 configuration and compilation of the package. If a
1760 package has an interactive pre-build configuration
1761 routine, the Debianised source package should be
1762 built after this has taken place, so that it can be
1763 built without rerunning the configuration.
1767 For some packages, notably ones where the same
1768 source tree is compiled in different ways to produce
1769 two binary packages, the <prgn>build</prgn> target
1770 does not make much sense. For these packages it is
1771 good enough to provide two (or more) targets
1772 (<tt>build-a</tt> and <tt>build-b</tt> or whatever)
1773 for each of the ways of building the package, and a
1774 <prgn>build</prgn> target that does nothing. The
1775 <prgn>binary</prgn> target will have to build the
1776 package in each of the possible ways and make the
1777 binary package out of each.
1781 The <prgn>build</prgn> target must not do anything
1782 that might require root privilege.
1786 The <prgn>build</prgn> target may need to run
1787 <prgn>clean</prgn> first - see below.
1791 When a package has a configuration routine that
1792 takes a long time, or when the makefiles are poorly
1793 designed, or when <prgn>build</prgn> needs to run
1794 <prgn>clean</prgn> first, it is a good idea to
1795 <tt>touch build</tt> when the build process is
1796 complete. This will ensure that if <tt>debian/rules
1797 build</tt> is run again it will not rebuild the
1802 <tag><tt>binary</tt>, <tt>binary-arch</tt>,
1803 <tt>binary-indep</tt>
1807 The <prgn>binary</prgn> target must be all that is
1808 necessary for the user to build the binary
1809 package. All these targets are required to be
1810 non-interactive. It is split into two parts:
1811 <prgn>binary-arch</prgn> builds the packages' output
1812 files which are specific to a particular
1813 architecture, and <prgn>binary-indep</prgn> builds
1814 those which are not.
1818 <prgn>binary</prgn> may be (and commonly is) a target
1819 with no commands which simply depends on
1820 <prgn>binary-arch</prgn> and
1821 <prgn>binary-indep</prgn>.
1825 Both <prgn>binary-*</prgn> targets should depend on
1826 the <prgn>build</prgn> target, above, so that the
1827 package is built if it has not been already. It
1828 should then create the relevant binary package(s),
1829 using <prgn>dpkg-gencontrol</prgn> to make their
1830 control files and <prgn>dpkg-deb</prgn> to build
1831 them and place them in the parent of the top level
1836 If one of the <prgn>binary-*</prgn> targets has
1837 nothing to do (this will be always be the case if
1838 the source generates only a single binary package,
1839 whether architecture-dependent or not) it
1840 <em>must</em> still exist, and must always
1845 The <prgn>binary</prgn> targets must be invoked as
1850 <tag><tt>clean</tt></tag>
1854 This must undo any effects that the
1855 <prgn>build</prgn> and <prgn>binary</prgn> targets
1856 may have had, except that it should leave alone any
1857 output files created in the parent directory by a
1858 run of <prgn>binary</prgn>. This target must be
1863 If a <prgn>build</prgn> file is touched at the end
1864 of the <prgn>build</prgn> target, as suggested
1865 above, it should be removed as the first thing that
1866 <prgn>clean</prgn> does, so that running
1867 <prgn>build</prgn> again after an interrupted
1868 <prgn>clean</prgn> doesn't think that everything is
1873 The <prgn>clean</prgn> target may need to be
1874 invoked as root if <prgn>binary</prgn> has been
1875 invoked since the last <prgn>clean</prgn>, or if
1876 <prgn>build</prgn> has been invoked as root (since
1877 <prgn>build</prgn> may create directories, for
1882 <tag><tt>get-orig-source</tt> (optional)</tag>
1886 This target fetches the most recent version of the
1887 original source package from a canonical archive site
1888 (via FTP or WWW, for example), does any necessary
1889 rearrangement to turn it into the original source
1890 tar file format described below, and leaves it in the
1895 This target may be invoked in any directory, and
1896 should take care to clean up any temporary files it
1901 This target is optional, but providing it if
1902 possible is a good idea.
1908 The <prgn>build</prgn>, <prgn>binary</prgn> and
1909 <prgn>clean</prgn> targets must be invoked with a current
1910 directory of the package's top-level directory.
1915 Additional targets may exist in <tt>debian/rules</tt>,
1916 either as published or undocumented interfaces or for the
1917 package's internal use.
1921 The architecture we build on and build for is determined by
1922 make variables via dpkg-architecture. You can get the Debian
1923 architecture and the GNU style architecture specification
1924 string for the build machine as well as the host
1925 machine. Here is a list of supported make variables:
1926 <list compact="compact">
1928 <p><tt>DEB_*_ARCH</tt> (the Debian architecture)</p>
1931 <p><tt>DEB_*_GNU_TYPE</tt> (the GNU style architecture
1932 specification string)</p>
1935 <p><tt>DEB_*_GNU_CPU</tt> (the CPU part of DEB_*_GNU_TYPE)</p>
1938 <p><tt>DEB_*_GNU_SYSTEM</tt> (the System part of
1944 where <tt>*</tt> is either <tt>BUILD</tt> for specification of
1945 the build machine or <tt>HOST</tt> for specification of the machine
1950 Backward compatibility can be provided in the rules file
1951 by setting the needed variables to suitable default
1952 values, please refer to the documentation of
1953 dpkg-architecture for details.
1957 It is important to understand that the <tt>DEB_*_ARCH</tt>
1958 string does only determine which Debian architecture we
1959 build on resp. for. It should not be used to get the CPU
1960 or System information, the GNU style variables should be
1965 <sect id="dpkgchangelog"><heading><tt>debian/changelog</tt>
1969 This file records the changes to the Debian-specific parts of the
1973 Though there is nothing stopping an author who is also
1974 the Debian maintainer from using it for all their
1975 changes, it will have to be renamed if the Debian and
1976 upstream maintainers become different
1983 It has a special format which allows the package building
1984 tools to discover which version of the package is being
1985 built and find out other release-specific information.
1989 That format is a series of entries like this:
1991 <var>package</var> (<var>version</var>) <var>distribution(s)</var>; urgency=<var>urgency</var>
1993 * <var>change details</var>
1994 <var>more change details</var>
1995 * <var>even more change details</var>
1997 -- <var>maintainer name and email address</var> <var>date</var>
2002 <var>package</var> and <var>version</var> are the source
2003 package name and version number.
2007 <var>distribution(s)</var> lists the distributions where
2008 this version should be installed when it is uploaded - it
2009 is copied to the <tt>Distribution</tt> field in the
2010 <tt>.changes</tt> file. See <ref id="f-Distribution">.
2014 <var>urgency</var> is the value for the <tt>Urgency</tt>
2015 field in the <tt>.changes</tt> file for the upload. It is
2016 not possible to specify an urgency containing commas; commas
2017 are used to separate
2018 <tt><var>keyword</var>=<var>value</var></tt> settings in the
2019 <prgn>dpkg</prgn> changelog format (though there is
2020 currently only one useful <var>keyword</var>,
2025 The change details may in fact be any series of lines
2026 starting with at least two spaces, but conventionally each
2027 change starts with an asterisk and a separating space and
2028 continuation lines are indented so as to bring them in
2029 line with the start of the text above. Blank lines may be
2030 used here to separate groups of changes, if desired.
2034 The maintainer name and email address need <em>not</em>
2035 necessarily be those of the usual package maintainer.
2036 They should be the details of the person doing
2037 <em>this</em> version. The information here will be
2038 copied to the <tt>.changes</tt> file, and then later used
2039 to send an acknowledgement when the upload has been
2044 The <var>date</var> should be in RFC822 format
2047 This is generated by the <prgn>822-date</prgn>
2050 </footnote>; it should include the time zone specified
2051 numerically, with the time zone name or abbreviation
2052 optionally present as a comment.
2056 The first `title' line with the package name should start
2057 at the left hand margin; the `trailer' line with the
2058 maintainer and date details should be preceded by exactly
2059 one space. The maintainer details and the date must be
2060 separated by exactly two spaces.
2063 <sect1><heading>Defining alternative changelog formats</heading>
2066 It is possible to use a different format to the standard
2067 one, by providing a parser for the format you wish to
2071 A changelog parser must not interact with the user at
2077 <sect id="srcsubstvars"><heading><tt>debian/substvars</tt>
2078 and variable substitutions </heading>
2081 When <prgn>dpkg-gencontrol</prgn>,
2082 <prgn>dpkg-genchanges</prgn> and <prgn>dpkg-source</prgn>
2083 generate control files they do variable substitutions on
2084 their output just before writing it. Variable
2085 substitutions have the form
2086 <tt>${<var>variable-name</var>}</tt>. The optional file
2087 <tt>debian/substvars</tt> contains variable substitutions
2088 to be used; variables can also be set directly from
2089 <tt>debian/rules</tt> using the <tt>-V</tt> option to the
2090 source packaging commands, and certain predefined
2091 variables are available.
2095 The is usually generated and modified dynamically by
2096 <tt>debian/rules</tt> targets; in this case it must be
2097 removed by the <prgn>clean</prgn> target.
2101 See <manref name="dpkg-source" section="1"> for full
2102 details about source variable substitutions, including the
2103 format of <tt>debian/substvars</tt>.</p>
2106 <sect id="debianfiles"><heading><tt>debian/files</tt>
2110 This file is not a permanent part of the source tree; it
2111 is used while building packages to record which files are
2112 being generated. <prgn>dpkg-genchanges</prgn> uses it
2113 when it generates a <tt>.changes</tt> file.
2117 It should not exist in a shipped source package, and so it
2118 (and any backup files or temporary files such as
2122 <tt>files.new</tt> is used as a temporary file by
2123 <prgn>dpkg-gencontrol</prgn> and
2124 <prgn>dpkg-distaddfile</prgn> - they write a new
2125 version of <tt>files</tt> here before renaming it,
2126 to avoid leaving a corrupted copy if an error
2129 </footnote>) should be removed by the
2130 <prgn>clean</prgn> target. It may also be wise to
2131 ensure a fresh start by emptying or removing it at the
2132 start of the <prgn>binary</prgn> target.
2136 <prgn>dpkg-gencontrol</prgn> adds an entry to this file
2137 for the <tt>.deb</tt> file that will be created by
2138 <prgn>dpkg-deb</prgn> from the control file that it
2139 generates, so for most packages all that needs to be done
2140 with this file is to delete it in <prgn>clean</prgn>.
2144 If a package upload includes files besides the source
2145 package and any binary packages whose control files were
2146 made with <prgn>dpkg-gencontrol</prgn> then they should be
2147 placed in the parent of the package's top-level directory
2148 and <prgn>dpkg-distaddfile</prgn> should be called to add
2149 the file to the list in <tt>debian/files</tt>.</p>
2152 <sect id="restrictions"><heading>Restrictions on objects in source packages
2156 The source package may not contain any hard links
2159 This is not currently detected when building source
2160 packages, but only when extracting
2166 Hard links may be permitted at some point in the
2167 future, but would require a fair amount of
2170 </footnote>, device special files, sockets or setuid or
2174 Setgid directories are allowed.
2179 <sect id="descriptions"><heading>Descriptions of packages - the
2180 <tt>Description</tt> field </heading>
2183 The description is intended to describe the program to a user
2184 who has never met it before so that they know whether they
2185 want to install it. It should also give information about the
2186 significant dependencies and conflicts between this package
2187 and others, so that the user knows why these dependencies and
2188 conflicts have been declared.
2191 <sect1><heading>Notes about writing descriptions
2195 The single line synopsis should be kept brief - certainly
2196 under 80 characters.
2200 Do not include the package name in the synopsis line. The
2201 display software knows how to display this already, and you
2202 do not need to state it. Remember that in many situations
2203 the user may only see the synopsis line - make it as
2204 informative as you can.
2208 Do not try to continue the single line synopsis into the
2209 extended description. This will not work correctly when
2210 the full description is displayed, and makes no sense
2211 where only the summary (the single line synopsis) is
2216 The extended description should describe what the package
2217 does and how it relates to the rest of the system (in terms
2218 of, for example, which subsystem it is which part of).
2222 The description field needs to make sense to anyone, even
2223 people who have no idea about any of the things the
2227 The blurb that comes with a program in its
2228 announcements and/or <prgn>README</prgn> files is
2229 rarely suitable for use in a description. It is
2230 usually aimed at people who are already in the
2231 community where the package is used.
2237 Put important information first, both in the synopsis and
2238 extended description. Sometimes only the first part of the
2239 synopsis or of the description will be displayed. You can
2240 assume that there will usually be a way to see the whole
2241 extended description.
2245 You may include information about dependencies and so forth
2246 in the extended description, if you wish.
2250 Do not use tab characters. Their effect is not predictable.
2258 <chapt id="maintainerscripts"><heading>Package maintainer scripts
2259 and installation procedure
2262 <sect><heading>Introduction to package maintainer scripts
2266 It is possible to supply scripts as part of a package which
2267 the package management system will run for you when your
2268 package is installed, upgraded or removed.
2272 These scripts should be the files <tt>preinst</tt>,
2273 <tt>postinst</tt>, <tt>prerm</tt> and <tt>postrm</tt> in the
2274 control area of the package. They must be proper executable
2275 files; if they are scripts (which is recommended) they must
2276 start with the usual <tt>#!</tt> convention. They should be
2277 readable and executable to anyone, and not world-writable.
2281 the package management system looks at the exit status from
2282 these scripts. It is important that they exit with a
2283 non-zero status if there is an error, so that the package
2284 management system can stop its processing. For shell
2285 scripts this means that you <em>almost always</em> need to
2286 use <tt>set -e</tt> (this is usually true when writing shell
2287 scripts, in fact). It is also important, of course, that
2288 they don't exit with a non-zero status if everything went
2293 It is necessary for the error recovery procedures that the
2294 scripts be idempotent: i.e., invoking the same script several
2295 times in the same situation should do no harm. If the first
2296 call failed, or aborted half way through for some reason,
2297 the second call should merely do the things that were left
2298 undone the first time, if any, and exit with a success
2303 When a package is upgraded a combination of the scripts from
2304 the old and new packages is called in amongst the other
2305 steps of the upgrade procedure. If your scripts are going
2306 to be at all complicated you need to be aware of this, and
2307 may need to check the arguments to your scripts.
2311 Broadly speaking the <prgn>preinst</prgn> is called before
2312 (a particular version of) a package is installed, and the
2313 <prgn>postinst</prgn> afterwards; the <prgn>prerm</prgn>
2314 before (a version of) a package is removed and the
2315 <prgn>postrm</prgn> afterwards.
2318 next paragraph by Guy Maor to close bug #2481
2321 <p> Programs called from maintainer scripts should not
2322 normally have a path prepended to them. Before installation
2323 is started the package management system checks to see if
2324 the programs <prgn>ldconfig</prgn>,
2325 <prgn>start-stop-daemon</prgn>, <prgn>install-info</prgn>,
2326 and <prgn>update-rc.d</prgn> can be found via the
2327 <tt>PATH</tt> environment variable. Those programs, and any
2328 other program that one would expect to on the <tt>PATH</tt>,
2329 should thus be invoked without an absolute
2330 pathname. Maintainer scripts should also not reset the
2331 <tt>PATH</tt>, though they might choose to modify it by pre-
2332 or appending package-specific directories. These
2333 considerations really apply to all shell scripts.</p>
2336 <heading>Maintainer scripts Idempotency</heading>
2339 It is very important to make maintainer scripts
2343 That means that if it runs successfully or fails
2344 and then you call it again it doesn't bomb out,
2345 but just ensures that everything is the way it
2348 </footnote> This is so that if an error occurs, the
2349 user interrupts <prgn>dpkg</prgn> or some other
2350 unforeseen circumstance happens you don't leave the
2351 user with a badly-broken package.
2355 <heading>Controlling terminal for maintainer scripts</heading>
2358 The maintainer scripts are guaranteed to run with a
2359 controlling terminal and can interact with the user.
2360 If they need to prompt for passwords, do full-screen
2361 interaction or something similar you should do these
2362 things to and from <tt>/dev/tty</tt>, since
2363 <prgn>dpkg</prgn> will at some point redirect scripts'
2364 standard input and output so that it can log the
2365 installation process. Likewise, because these scripts
2366 may be executed with standard output redirected into a
2367 pipe for logging purposes, Perl scripts should set
2368 unbuffered output by setting <tt>$|=1</tt> so that the
2369 output is printed immediately rather than being
2374 Each script should return a zero exit status for
2375 success, or a nonzero one for failure.
2379 <sect id="mscriptsinstact"><heading>Summary of ways maintainer
2384 <list compact="compact">
2386 <p><var>new-preinst</var> <tt>install</tt></p>
2389 <p><var>new-preinst</var> <tt>install</tt>
2390 <var>old-version</var></p>
2393 <p><var>new-preinst</var> <tt>upgrade</tt>
2394 <var>old-version</var></p>
2397 <p><var>old-preinst</var> <tt>abort-upgrade</tt>
2398 <var>new-version</var>
2404 <list compact="compact">
2406 <p><var>postinst</var> <tt>configure</tt>
2407 <var>most-recently-configured-version</var></p>
2410 <p><var>old-postinst</var> <tt>abort-upgrade</tt>
2411 <var>new version</var></p>
2414 <p><var>conflictor's-postinst</var> <tt>abort-remove</tt>
2415 <tt>in-favour</tt> <var>package</var>
2416 <var>new-version</var></p>
2420 <var>deconfigured's-postinst</var>
2421 <tt>abort-deconfigure</tt> <tt>in-favour</tt>
2422 <var>failed-install-package</var> <var>version</var>
2423 <tt>removing</tt> <var>conflicting-package</var>
2430 <list compact="compact">
2432 <p><var>prerm</var> <tt>remove</tt></p>
2435 <p><var>old-prerm</var> <tt>upgrade</tt>
2436 <var>new-version</var></p>
2439 <p><var>new-prerm</var> <tt>failed-upgrade</tt>
2440 <var>old-version</var></p>
2443 <p><var>conflictor's-prerm</var> <tt>remove</tt>
2444 <tt>in-favour</tt> <var>package</var>
2445 <var>new-version</var></p>
2449 <var>deconfigured's-prerm</var> <tt>deconfigure</tt>
2450 <tt>in-favour</tt> <var>package-being-installed</var>
2451 <var>version</var> <tt>removing</tt>
2452 <var>conflicting-package</var>
2459 <list compact="compact">
2461 <p><var>postrm</var> <tt>remove</tt></p>
2464 <p><var>postrm</var> <tt>purge</tt></p>
2468 <var>old-postrm</var> <tt>upgrade</tt>
2469 <var>new-version</var></p>
2472 <p><var>new-postrm</var> <tt>failed-upgrade</tt>
2473 <var>old-version</var></p>
2476 <p><var>new-postrm</var> <tt>abort-install</tt></p>
2479 <p><var>new-postrm</var> <tt>abort-install</tt>
2480 <var>old-version</var></p>
2483 <p><var>new-postrm</var> <tt>abort-upgrade</tt>
2484 <var>old-version</var></p>
2488 <var>disappearer's-postrm</var> <tt>disappear</tt>
2489 <var>overwriter</var>
2490 <var>overwriter-version</var></p></item>
2495 <sect id="unpackphase"><heading>Details of unpack phase of
2496 installation or upgrade
2500 The procedure on installation/upgrade/overwrite/disappear
2501 (i.e., when running <tt>dpkg --unpack</tt>, or the unpack
2503 --install</tt>) is as follows. In each case if an error occurs the
2504 actions in are general run backwards - this means that the maintainer
2505 scripts are run with different arguments in reverse order. These are
2506 the `error unwind' calls listed below.
2513 <p>If a version the package is already
2516 <var>old-prerm</var> upgrade <var>new-version</var>
2521 If this gives an error (i.e., a non-zero exit
2522 status), dpkg will attempt instead:
2524 <var>new-prerm</var> failed-upgrade <var>old-version</var>
2526 Error unwind, for both the above cases:
2528 <var>old-postinst</var> abort-upgrade <var>new-version</var>
2536 <p>If a `conflicting' package is being removed at the same time:
2540 If any packages depended on that conflicting
2541 package and <tt>--auto-deconfigure</tt> is
2542 specified, call, for each such package:
2544 <var>deconfigured's-prerm</var> deconfigure \
2545 in-favour <var>package-being-installed</var> <var>version</var> \
2546 removing <var>conflicting-package</var> <var>version</var>
2550 <var>deconfigured's-postinst</var> abort-deconfigure \
2551 in-favour <var>package-being-installed-but-failed</var> <var>version</var> \
2552 removing <var>conflicting-package</var> <var>version</var>
2554 The deconfigured packages are marked as
2555 requiring configuration, so that if
2556 <tt>--install</tt> is used they will be
2557 configured again if possible.</p>
2560 <p>To prepare for removal of the conflicting package, call:
2562 <var>conflictor's-prerm</var> remove in-favour <var>package</var> <var>new-version</var>
2566 <var>conflictor's-postinst</var> abort-remove \
2567 in-favour <var>package</var> <var>new-version</var>
2578 <p>If the package is being upgraded, call:
2580 <var>new-preinst</var> upgrade <var>old-version</var>
2585 Otherwise, if the package had some configuration
2586 files from a previous version installed (i.e., it
2587 is in the `configuration files only' state):
2589 <var>new-preinst</var> install <var>old-version</var>
2593 <p>Otherwise (i.e., the package was completely purged):
2595 <var>new-preinst</var> install
2597 Error unwind versions, respectively:
2599 <var>new-postrm</var> abort-upgrade <var>old-version</var>
2600 <var>new-postrm</var> abort-install <var>old-version</var>
2601 <var>new-postrm</var> abort-install
2611 The new package's files are unpacked, overwriting any
2612 that may be on the system already, for example any
2613 from the old version of the same package or from
2614 another package (backups of the old files are left
2615 around, and if anything goes wrong the package
2616 management system will attempt to put them back as
2617 part of the error unwind).
2621 It is an error for a package to contains files which
2622 are on the system in another package, unless
2623 <tt>Replaces</tt> is used (see <ref id="replaces">).
2624 Currently the <tt>--force-overwrite</tt> flag is
2625 enabled, downgrading it to a warning, but this may not
2630 It is a more serious error for a package to contain a
2631 plain file or other kind of non-directory where another
2632 package has a directory (again, unless
2633 <tt>Replaces</tt> is used). This error can be
2634 overridden if desired using
2635 <tt>--force-overwrite-dir</tt>, but this is not
2640 Packages which overwrite each other's files produce
2641 behavior which though deterministic is hard for the
2642 system administrator to understand. It can easily
2643 lead to `missing' programs if, for example, a package
2644 is installed which overwrites a file from another
2645 package, and is then removed again.
2648 Part of the problem is due to what is arguably a
2649 bug in <prgn>dpkg</prgn>.
2655 A directory will never be replaced by a symbolic links
2656 to a directory or vice versa; instead, the existing
2657 state (symlink or not) will be left alone and
2658 <prgn>dpkg</prgn> will follow the symlink if there is
2666 <p>If the package is being upgraded, call
2668 <var>old-postrm</var> upgrade <var>new-version</var>
2672 <p>If this fails, <prgn>dpkg</prgn> will attempt:
2674 <var>new-postrm</var> failed-upgrade <var>old-version</var>
2676 Error unwind, for both cases:
2678 <var>old-preinst</var> abort-upgrade <var>new-version</var>
2684 This is the point of no return - if
2685 <prgn>dpkg</prgn> gets this far, it won't back off
2686 past this point if an error occurs. This will
2687 leave the package in a fairly bad state, which
2688 will require a successful re-installation to clear
2689 up, but it's when <prgn>dpkg</prgn> starts doing
2690 things that are irreversible.
2695 Any files which were in the old version of the package
2696 but not in the new are removed.</p>
2699 <p>The new file list replaces the old.</p>
2702 <p>The new maintainer scripts replace the old.</p>
2706 <p>Any packages all of whose files have been overwritten during the
2707 installation, and which aren't required for
2708 dependencies, are considered to have been removed.
2709 For each such package,
2712 <p><prgn>dpkg</prgn> calls:
2714 <var>disappearer's-postrm</var> disappear \
2715 <var>overwriter</var> <var>overwriter-version</var>
2720 <p>The package's maintainer scripts are removed.
2725 It is noted in the status database as being in a
2726 sane state, namely not installed (any conffiles
2727 it may have are ignored, rather than being
2728 removed by <prgn>dpkg</prgn>). Note that
2729 disappearing packages do not have their prerm
2730 called, because <prgn>dpkg</prgn> doesn't know
2731 in advance that the package is going to
2740 Any files in the package we're unpacking that are also
2741 listed in the file lists of other packages are removed
2742 from those lists. (This will lobotomize the file list
2743 of the `conflicting' package if there is one.)
2748 The backup files made during installation, above, are
2755 The new package's status is now sane, and recorded as
2756 `unpacked'. Here is another point of no return - if
2757 the conflicting package's removal fails we do not
2758 unwind the rest of the installation; the conflicting
2759 package is left in a half-removed limbo.
2764 If there was a conflicting package we go and do the
2765 removal actions (described below), starting with the
2766 removal of the conflicting package's files (any that
2767 are also in the package being installed have already
2768 been removed from the conflicting package's file list,
2769 and so do not get removed now).
2776 <sect><heading>Details of configuration</heading>
2779 When we configure a package (this happens with <tt>dpkg
2780 --install</tt>, or with <tt>--configure</tt>), we first
2781 update the conffiles and then call:
2783 <var>postinst</var> configure <var>most-recently-configured-version</var>
2788 No attempt is made to unwind after errors during
2793 If there is no most recently configured version
2794 <prgn>dpkg</prgn> will pass a null argument; older versions
2795 of dpkg may pass <tt><unknown></tt> (including the
2796 angle brackets) in this case. Even older ones do not pass a
2797 second argument at all, under any circumstances.
2801 <sect><heading>Details of removal and/or configuration purging
2809 <var>prerm</var> remove
2815 The package's files are removed (except conffiles).
2820 <var>postrm</var> remove
2824 <p>All the maintainer scripts except the postrm are removed.
2828 If we aren't purging the package we stop here. Note
2829 that packages which have no postrm and no conffiles
2830 are automatically purged when removed, as there is no
2831 difference except for the <prgn>dpkg</prgn>
2836 The conffiles and any backup files (<tt>~</tt>-files,
2837 <tt>#*#</tt> files, <tt>%</tt>-files,
2838 <tt>.dpkg-{old,new,tmp}</tt>, etc.) are removed.</p>
2842 <var>postrm</var> purge
2846 <p>The package's file list is removed.</p>
2849 No attempt is made to unwind after errors during
2855 <chapt id="relationships"><heading>Declaring relationships between
2859 Packages can declare in their control file that they have
2860 certain relationships to other packages - for example, that
2861 they may not be installed at the same time as certain other
2862 packages, and/or that they depend on the presence of others,
2863 or that they should overwrite files in certain other packages
2868 This is done using the <tt>Depends</tt>, <tt>Recommends</tt>,
2869 <tt>Suggests</tt>, <tt>Enhances</tt>, <tt>Conflicts</tt>,
2870 <tt>Provides</tt> and <tt>Replaces</tt> control file fields.
2874 Source packages may declare relationships to binary packages,
2875 saying that they require certain binary packages being
2876 installed or absent at the time of building the package.
2880 This is done using the <tt>Build-Depends</tt>,
2881 <tt>Build-Depends-Indep</tt>, <tt>Build-Conflicts</tt>, and
2882 <tt>Build-Conflicts-Indep</tt> control file fields.
2885 <sect id="depsyntax"><heading>Syntax of relationship fields
2889 These fields all have a uniform syntax. They are a list of
2890 package names separated by commas.
2894 In <tt>Depends</tt>, <tt>Recommends</tt>, <tt>Suggests</tt>,
2895 <tt>Pre-Depends</tt>, <tt>Build-Depends</tt> and
2896 <tt>Build-Depends-Indep</tt>(the fields which declare
2897 dependencies of the package in which they occur on other
2898 packages) these package names may also be lists of
2899 alternative package names, separated by vertical bar symbols
2900 <tt>|</tt> (pipe symbols).
2904 All the fields except <tt>Provides</tt> may restrict their
2905 applicability to particular versions of each named package.
2906 This is done in parentheses after each individual package
2907 name; the parentheses should contain a relation from the
2908 list below followed by a version number, in the format
2909 described in <ref id="versions">.
2913 The relations allowed are <tt><<</tt>, <tt><=</tt>,
2914 <tt>=</tt>, <tt>>=</tt> and <tt>>></tt> for
2915 strictly earlier, earlier or equal, exactly equal, later or
2916 equal and strictly later, respectively. The forms
2917 <tt><</tt> and <tt>></tt> were used to mean
2918 earlier/later or equal, rather than strictly earlier/later,
2919 so they should not appear in new packages (though
2920 <prgn>dpkg</prgn> still supports them).
2924 Whitespace may appear at any point in the version
2925 specification, and must appear where it's necessary to
2926 disambiguate; it is not otherwise significant. For
2927 consistency and in case of future changes to
2928 <prgn>dpkg</prgn> it is recommended that a single space be
2929 used after a version relationship and before a version
2930 number; it is usual also to put a single space after each
2931 comma, on either side of each vertical bar, and before each
2940 Depends: libc5 (>= 5.2.18-4), mime-support, csh | tcsh
2945 All fields that specify build-time relationships
2946 (<tt>Build-Depends</tt>, <tt>Build-Depends-Indep</tt>,
2947 <tt>Build-Conflicts</tt> and <tt>Build-Conflicts-Indep</tt>)
2948 may be restricted to a certain set of architectures. This
2949 is done in brackets after each individual package name and
2950 the optional version specification. The brackets enclose a
2951 list of Debian architecture names separated by whitespace.
2952 An exclamation mark may be prepended to each name. If the
2953 current Debian host architecture is not in this list and
2954 there are no exclamation marks in the list, or it is in the
2955 list with a prepended exclamation mark, the package name and
2956 the associated version specification are ignored completely
2957 for the purposes of defining the relationships.
2964 Build-Depends-Indep: texinfo
2965 Build-Depends: kernel-headers-2.2.10 [!hurd-i386],
2966 hurd-dev [hurd-i386], gnumach-dev [hurd-i386]
2972 <heading>Binary Dependencies - <tt>Depends</tt>,
2973 <tt>Recommends</tt>, <tt>Suggests</tt>, <tt>Enhances</tt>,
2974 <tt>Pre-Depends</tt>
2978 These five fields are used to declare a dependency
2979 relationship by one package on another. They appear in the
2980 depending package's control file.
2984 All but <tt>Pre-Depends</tt> and <tt>Conflicts</tt>
2985 (discussed below) take effect <em>only</em> when a package
2986 is to be configured. They do not prevent a package being on
2987 the system in an unconfigured state while its dependencies
2988 are unsatisfied, and it is possible to replace a package
2989 whose dependencies are satisfied and which is properly
2990 installed with a different version whose dependencies are
2991 not and cannot be satisfied; when this is done the depending
2992 package will be left unconfigured (since attempts to
2993 configure it will give errors) and will not function
2998 For this reason packages in an installation run are usually
2999 all unpacked first and all configured later; this gives
3000 later versions of packages with dependencies on later
3001 versions of other packages the opportunity to have their
3002 dependencies satisfied.
3006 Thus <tt>Depends</tt> allows package maintainers to impose
3007 an order in which packages should be configured.
3009 <tag><tt>Depends</tt></tag>
3012 <p>This declares an absolute dependency.
3016 The <tt>Depends</tt> field should be used if the
3017 depended-on package is required for the depending
3018 package to provide a significant amount of
3022 <tag><tt>Recommends</tt></tag>
3024 <p>This declares a strong, but not absolute, dependency.
3028 The <tt>Recommends</tt> field should list packages
3029 that would be found together with this one in all but
3030 unusual installations.</p>
3033 <tag><tt>Suggests</tt></tag>
3037 This is used to declare that one package may be more
3038 useful with one or more others. Using this field
3039 tells the packaging system and the user that the
3040 listed packages are related to this one and can
3041 perhaps enhance its usefulness, but that installing
3042 this one without them is perfectly reasonable.
3046 <tag><tt>Enhances</tt></tag>
3049 This field is similar to Suggests but works in the
3050 opposite direction. It is used to declare that a
3051 package can enhance the functionality of another
3056 <tag><tt>Pre-Depends</tt></tag>
3060 This field is like <tt>Depends</tt>, except that it
3061 also forces <prgn>dpkg</prgn> to complete installation
3062 of the packages named before even starting the
3063 installation of the package which declares the
3068 <tt>Pre-Depends</tt> should be used sparingly,
3069 preferably only by packages whose premature upgrade or
3070 installation would hamper the ability of the system to
3071 continue with any upgrade that might be in progress.
3075 When the package declaring it is being configured, a
3076 <tt>Pre-Dependency</tt> will be considered satisfied
3077 only if the depending package has been correctly
3078 configured, just as if an ordinary <tt>Depends</tt>
3083 However, when a package declaring a Pre-dependency is
3084 being unpacked the predependency can be satisfied even
3085 if the depended-on package(s) are only unpacked or
3086 half-configured, provided that they have been
3087 configured correctly at some point in the past (and
3088 not removed or partially removed since). In this case
3089 both the previously-configured and currently unpacked
3090 or half-configured versions must satisfy any version
3091 clause in the <tt>Pre-Depends</tt> field.
3097 When selecting which level of dependency to use you should
3098 consider how important the depended-on package is to the
3099 functionality of the one declaring the dependency. Some
3100 packages are composed of components of varying degrees of
3101 importance. Such a package should list using
3102 <tt>Depends</tt> the package(s) which are required by the
3103 more important components. The other components'
3104 requirements may be mentioned as Suggestions or
3105 Recommendations, as appropriate to the components' relative
3110 <sect id="conflicts"><heading>Alternative binary packages -
3111 <tt>Conflicts</tt> and <tt>Replaces</tt>
3115 When one binary package declares a conflict with another
3116 <prgn>dpkg</prgn> will refuse to allow them to be installed
3117 on the system at the same time.
3121 If one package is to be installed, the other must be removed
3122 first - if the package being installed is marked as
3123 replacing (<ref id="replaces">) the one on the system, or
3124 the one on the system is marked as deselected, or both
3125 packages are marked <tt>Essential</tt>, then
3126 <prgn>dpkg</prgn> will automatically remove the package
3127 which is causing the conflict, otherwise it will halt the
3128 installation of the new package with an error. This
3129 mechanism specifically doesn't work when the installed
3130 package is <tt>Essential</tt>, but the new package is not.
3135 A package will not cause a conflict merely because its
3136 configuration files are still installed; it must be at least
3141 A special exception is made for packages which declare a
3142 conflict with their own package name, or with a virtual
3143 package which they provide (see below): this does not
3144 prevent their installation, and allows a package to conflict
3145 with others providing a replacement for it. You use this
3146 feature when you want the package in question to be the only
3147 package providing something.
3151 A <tt>Conflicts</tt> entry should almost never have an
3152 `earlier than' version clause. This would prevent
3153 <prgn>dpkg</prgn> from upgrading or installing the package
3154 which declared such a conflict until the upgrade or removal
3155 of the conflicted-with package had been completed.
3159 <sect id="virtual"><heading>Virtual packages - <tt>Provides</tt>
3163 As well as the names of actual (`concrete') packages, the
3164 package relationship fields <tt>Depends</tt>,
3165 <tt>Build-Depends</tt>, <tt>Build-Depends-Indep</tt>,
3166 <tt>Recommends</tt>, <tt>Suggests</tt>, <tt>Conflicts</tt>,
3167 <tt>Build-Conflicts</tt> and <tt>Build-Conflicts-Indep</tt> may
3168 mention virtual packages.
3172 A virtual package is one which appears in the
3173 <tt>Provides</tt> control file field of another package.
3174 The effect is as if the package(s) which provide a
3175 particular virtual package name had been listed by name
3176 everywhere the virtual package name appears.
3180 If there are both a real and a virtual package of the same
3181 name then the dependency may be satisfied (or the conflict
3182 caused) by either the real package or any of the virtual
3183 packages which provide it. This is so that, for example,
3189 and someone else releases an xemacs package they can say
3193 </example> and all will work in the interim (until a purely
3194 virtual package name is decided on and the <tt>emacs</tt>
3195 and <tt>vm</tt> packages are changed to use it).
3199 If a dependency or a conflict has a version number attached
3200 then only real packages will be considered to see whether
3201 the relationship is satisfied (or the prohibition violated,
3202 for a conflict) - it is assumed that a real package which
3203 provides virtual package is not of the `right' version. So,
3204 a <tt>Provides</tt> field may not contain version numbers,
3205 and the version number of the concrete package which
3206 provides a particular virtual package will not be looked at
3207 when considering a dependency on or conflict with the
3208 virtual package name.
3212 It is likely that the ability will be added in a future
3213 release of <prgn>dpkg</prgn> to specify a version number for
3214 each virtual package it provides. This feature is not yet
3215 present, however, and is expected to be used only
3220 If you want to specify which of a set of real packages should be the
3221 default to satisfy a particular dependency on a virtual package, you
3222 should list the real package as an alternative before the virtual.
3227 <sect id="replaces"><heading><tt>Replaces</tt> - overwriting
3228 files and replacing packages
3232 The <tt>Replaces</tt> control file field has two purposes,
3233 which come into play in different situations.
3237 Virtual packages (<ref id="virtual">) are not considered
3238 when looking at a <tt>Replaces</tt> field - the packages
3239 declared as being replaced must be mentioned by their real
3243 <sect1><heading>Overwriting files in other packages
3247 Firstly, as mentioned before, it is usually an error for a
3248 package to contains files which are on the system in
3249 another package, though currently the
3250 <tt>--force-overwrite</tt> flag is enabled by default,
3251 downgrading the error to a warning,
3255 If the overwriting package declares that it replaces the
3256 one containing the file being overwritten then
3257 <prgn>dpkg</prgn> will proceed, and replace the file from
3258 the old package with that from the new. The file will no
3259 longer be listed as `owned' by the old package.
3263 If a package is completely replaced in this way, so that
3264 <prgn>dpkg</prgn> does not know of any files it still
3265 contains, it is considered to have disappeared. It will
3266 be marked as not wanted on the system (selected for
3267 removal) and not installed. Any conffiles details noted
3268 in the package will be ignored, as they will have been
3269 taken over by the replacing package(s). The package's
3270 <prgn>postrm</prgn> script will be run to allow the
3271 package to do any final cleanup required. See <ref
3272 id="mscriptsinstact">.
3276 In the future <prgn>dpkg</prgn> will discard files which
3277 overwrite those from another package which declares that
3278 it replaces the one being installed (so that you can
3279 install an older version of a package without problems).
3283 This usage of <tt>Replaces</tt> only takes effect when
3284 both packages are at least partially on the system at
3285 once, so that it can only happen if they do not conflict
3286 or if the conflict has been overridden.</p>
3289 <sect1><heading>Replacing whole packages, forcing their
3294 Secondly, <tt>Replaces</tt> allows the packaging system to
3295 resolve which package should be removed when there is a
3296 conflict - see <ref id="conflicts">. This usage only
3297 takes effect when the two packages <em>do</em> conflict,
3298 so that the two effects do not interfere with each other.
3303 <sect><heading>Relationships between source and binary packages -
3304 <tt>Build-Depends</tt>, <tt>Build-Depends-Indep</tt>,
3305 <tt>Build-Conflicts</tt>, <tt>Build-Conflicts-Indep</tt>
3309 A source package may declare a dependency or a conflict on a
3310 binary package. This is done with the control file fields
3311 <tt>Build-Depends</tt>, <tt>Build-Depends-Indep</tt>,
3312 <tt>Build-Conflicts</tt>, and <tt>Build-Conflicts-Indep</tt>. Their
3313 semantics is that the dependencies and conflicts they define
3314 must be satisfied (as defined earlier for binary packages),
3315 when one of the targets in <tt>debian/rules</tt> that the
3316 particular field applies to is invoked.
3319 <tag><tt>Build-Depends</tt>, <tt>Build-Conflicts</tt></tag>
3322 The <tt>Build-Depends</tt> and
3323 <tt>Build-Conflicts</tt> fields apply to the targets
3324 <tt>build</tt>, <tt>binary</tt>, <tt>binary-arch</tt>
3325 and <tt>binary-indep</tt>.
3328 <tag><tt>Build-Depends-Indep</tt>, <tt>Build-Conflicts-Indep</tt></tag>
3331 The <tt>Build-Depends-Indep</tt> and
3332 <tt>Build-Conflicts-Indep</tt> fields apply to the
3333 targets <tt>binary</tt> and <tt>binary-indep</tt>.
3344 <chapt id="conffiles"><heading>Configuration file handling
3348 <prgn>dpkg</prgn> can do a certain amount of automatic
3349 handling of package configuration files.
3353 Whether this mechanism is appropriate depends on a number of
3354 factors, but basically there are two approaches to any
3355 particular configuration file.
3359 The easy method is to ship a best-effort configuration in the
3360 package, and use <prgn>dpkg</prgn>'s conffile mechanism to
3361 handle updates. If the user is unlikely to want to edit the
3362 file, but you need them to be able to without losing their
3363 changes, and a new package with a changed version of the file
3364 is only released infrequently, this is a good approach.
3368 The hard method is to build the configuration file from
3369 scratch in the <prgn>postinst</prgn> script, and to take the
3370 responsibility for fixing any mistakes made in earlier
3371 versions of the package automatically. This will be
3372 appropriate if the file is likely to need to be different on
3377 <chapt id="sharedlibs"><heading>Shared libraries
3381 Packages containing shared libraries must be constructed with
3382 a little care to make sure that the shared library is always
3383 available. This is especially important for packages whose
3384 shared libraries are vitally important, such as the libc.
3388 Firstly, your package should install the shared libraries
3389 under their normal names. For example, the
3390 <prgn>libgdbm1</prgn> package should install
3391 <tt>libgdbm.so.1.7.3</tt> as
3392 <tt>/usr/lib/libgdbm.so.1.7.3</tt>. The files should not be
3393 renamed or re-linked by any prerm or postrm scripts;
3394 <prgn>dpkg</prgn> will take care of renaming things safely
3395 without affecting running programs, and attempts to interfere
3396 with this are likely to lead to problems.
3400 Secondly, your package should include the symlink that
3401 <prgn>ldconfig</prgn> would create for the shared libraries.
3402 For example, the <prgn>libgdbm1</prgn> package should include
3403 a symlink from <tt>/usr/lib/libgdbm.so.1</tt> to
3404 <tt>libgdbm.so.1.7.3</tt>. This is needed so that
3405 <prgn>ld.so</prgn> can find the library in between the time
3406 <prgn>dpkg</prgn> installs it and <prgn>ldconfig</prgn> is run
3407 in the <prgn>postinst</prgn> script. Furthermore, older
3408 versions of the package management system required the library
3409 must be placed before the symlink pointing to it in the
3410 <tt>.deb</tt> file. This is so that by the time
3411 <prgn>dpkg</prgn> comes to install the symlink (overwriting
3412 the previous symlink pointing at an older version of the
3413 library) the new shared library is already in place.
3414 Unfortunately, this was not not always possible, since it
3415 highly depends on the behavior of the file system. Some
3416 file systems (such as reiserfs) will reorder the files so it
3417 doesn't matter in what order you create them. Starting with
3418 release <tt>1.7.0</tt> <prgn>dpkg</prgn> will reorder the
3419 files itself when building a package.
3423 next Paragraph added to close Bug #5299, Guy Maor
3427 Thirdly, the development package should contain a symlink for
3428 the shared library without a version number. For example, the
3429 <tt>libgdbm1-dev</tt> package should include a symlink from
3430 <tt>/usr/lib/libgdm.so</tt> to <tt>libgdm.so.1.7.3</tt>. This
3431 symlink is needed by <prgn>ld</prgn> when compiling packages
3432 as it will only look for <tt>libgdm.so</tt> and
3433 <tt>libgdm.a</tt> when compiling dynamically or statically,
3438 next paragraph changed by Christian Schwarz (see policy weekly #6)
3442 Any package installing shared libraries in a directory that's listed
3443 in <tt>/etc/ld.so.conf</tt> or in one of the default library
3444 directories of <prgn>ld.so</prgn> (currently, these are <tt>/usr/lib</tt>
3445 and <tt>/lib</tt>) must call <prgn>ldconfig</prgn> in its <prgn>postinst</prgn>
3446 script if and only if the first argument is `configure'. However, it
3447 is important not to call <prgn>ldconfig</prgn> in the postrm or preinst
3448 scripts in the case where the package is being upgraded (see <ref
3449 id="unpackphase">), as <prgn>ldconfig</prgn> will see the temporary names
3450 that <prgn>dpkg</prgn> uses for the files while it is
3451 installing them and will make the shared library links point
3452 to them, just before <prgn>dpkg</prgn> continues the
3453 installation and removes the links!
3457 moved from section 2.2 , DMorris
3460 <sect id="shlibs"><heading>The <tt>shlibs</tt> File Format
3464 This file is for use by <prgn>dpkg-shlibdeps</prgn> and is
3465 required when your package provides shared libraries.
3469 Each line is of the form:
3471 <var>library-name</var> <var>version-or-soname</var> <var>dependencies ...</var>
3476 <var>library-name</var> is the name of the shared library,
3477 for example <tt>libc5</tt>.
3481 <var>version-or-soname</var> is the soname of the library -
3482 i.e., the thing that must exactly match for the library to be
3483 recognized by <prgn>ld.so</prgn>. Usually this is major
3484 version number of the library.
3488 <var>dependencies</var> has the same syntax as a dependency
3489 field in a binary package control file. It should give
3490 details of which package(s) are required to satisfy a binary
3491 built against the version of the library contained in the
3492 package. See <ref id="depsyntax">.
3496 For example, if the package <tt>foo</tt> contains
3497 <tt>libfoo.so.1.2.3</tt>, where the soname of the library is
3498 <tt>libfoo.so.1</tt>, and the first version of the package
3499 which contained a minor number of at least <tt>2.3</tt> was
3500 <var>1.2.3-1</var>, then the package's <var>shlibs</var>
3503 libfoo 1 foo (>= 1.2.3-1)
3508 The version-specific dependency is to avoid warnings from
3509 <prgn>ld.so</prgn> about using older shared libraries with
3513 <sect><heading>Further Technical information on
3514 <tt>shlibs</tt></heading>
3518 following section mostly provided by Heiko Schlittermann
3522 <sect1><heading><em>What</em> are the <tt>shlibs</tt> files?
3526 The <tt>debian/shlibs</tt> file provides a way of checking
3527 for shared library dependencies on packaged binaries.
3528 They are intended to be used by package maintainers to
3529 make their lives easier.
3533 Other <tt>shlibs</tt> files that exist on a Debian system are
3535 <item> <p><tt>/etc/dpkg/shlibs.default</tt></p></item>
3536 <item> <p><tt>/etc/dpkg/shlibs.override</tt></p></item>
3537 <item> <p><tt>/var/lib/dpkg/info/*.shlibs</tt></p></item>
3538 <item> <p><tt>debian/shlibs.local</tt></p></item>
3540 These files are used by <prgn>dpkg-shlibdeps</prgn> when
3541 creating a binary package.</p>
3544 <sect1><heading><em>How</em> does <prgn>dpkg-shlibdeps</prgn>
3548 <prgn>dpkg-shlibdeps</prgn>
3549 determines the shared libraries directly
3552 Currently, it calls <prgn>ldd</prgn>, but in a
3553 forthcoming version it shall call <prgn>objdump</prgn>
3554 to to this. This however changes will need a couple of
3555 changes in the way that packages are build.
3558 Suppose a binary <tt>foo</tt> directly use a library
3559 <tt>libbar</tt> if it is linked with that
3560 library. Other libraries that are needed by
3561 <tt>libbar</tt> are linked indirectly to <tt>foo</tt>,
3562 and the dynamic linker will load the automatically
3563 when it loads <tt>libbar</tt>. Using <prgn>ldd</prgn>
3564 lists all the libraries, used directly and indirectly;
3565 but <prgn>objdump</prgn> only lists the directly
3566 linked libraries. A package only needs to depend on
3567 the libraries it is directly linked to, since the
3568 dependencies for those libraries should automatically
3569 pull in the other libraries.</p>
3572 This change does mean a change in the way packages are
3573 build though: currently dpkg-shlibdeps is only run on
3574 binaries. But since we will now depend on the
3575 libraries to depend on the libraries they need the
3576 packages containing those libraries will need to run
3577 dpkg-shlibdeps on the libraries.
3580 A good example where this would help us is the current
3581 mess with multiple version of the mesa library. With
3582 the ldd-based system every package that uses mesa need
3583 to add a dependency on svgalib|svgalib-dummy in order
3584 to handle the glide mesa variant. With an
3585 objdump-based system this isn't necessary anymore and
3586 would have saved everyone a lot of work.
3589 Another example: we could update libimlib with a new
3590 version that supports a new graphics format called
3591 dgf. If we use the old ldd method every package that
3592 uses libimlib would need to be recompiled so it would
3593 also depend on libdgf or it wouldn't run due to
3594 missing symbols. However with the new system packages
3595 using libimlib can depend on libimlib itself having
3596 the dependency on libgdh and wouldn't need to be
3600 used by the compiled binaries (and libraries, in a version
3601 of <prgn>dpkg-shlibdeps</prgn> coming soon) passed through
3602 on its command line.
3606 For each shared library, <prgn>dpkg-shlibdeps</prgn> needs to know
3607 <list compact="compact">
3608 <item><p>the package containing the library, and</p></item>
3609 <item><p>the library version number,</p></item>
3612 it scans the following files in this order.
3613 <enumlist compact="compact">
3614 <item><p><tt>debian/shlibs.local</tt></p></item>
3615 <item><p><tt>/etc/dpkg/shlibs.override</tt></p></item>
3616 <item><p><tt>/var/lib/dpkg/info/*.shlibs</tt></p></item>
3617 <item><p><tt>/etc/dpkg/shlibs.default</tt></p></item>
3621 <sect1><heading><em>Who</em> maintains the various
3622 <tt>shlibs</tt> files?
3626 <list compact="compact">
3628 <p><tt>/etc/dpkg/shlibs.default</tt> - the maintainer
3633 <tt>/var/lib/dpkg/info/<var>package</var>.shlibs</tt>
3634 - the maintainer of each package</p>
3638 <tt>/etc/dpkg/shlibs.override</tt> - the local
3639 system administrator</p>
3642 <p><tt>debian/shlibs.local</tt> - the maintainer of
3647 The <tt>shlibs.default</tt> file is managed by
3648 <prgn>dpkg</prgn>. The entries in <tt>shlibs.default</tt>
3649 that are provided by <prgn>dpkg</prgn> are just there to
3650 fix things until the shared library packages all have
3651 <tt>shlibs</tt> files.
3655 <sect1><heading><em>How</em> to use <prgn>dpkg-shlibdeps</prgn> and
3656 the <tt>shlibs</tt> files?
3659 <sect2><heading>If your package doesn't provide a shared
3664 Put a call to <prgn>dpkg-shlibdeps</prgn> into your
3665 <tt>debian/rules</tt> file. If your package contains
3666 only binaries (e.g. no scripts) use:
3668 dpkg-shlibdeps debian/tmp/usr/bin/* debian/tmp/usr/sbin/*
3670 If <prgn>dpkg-shlibdeps</prgn> doesn't complain, you're
3671 done. If it does complain you might need to create your
3672 own <tt>debian/shlibs.local</tt> file.</p>
3675 <sect2><heading>If your package provides a shared library
3679 Create a <tt>debian/shlibs</tt> file and let
3680 <tt>debian/rules</tt> install it in the control area:
3682 install -m644 debian/shlibs debian/tmp/DEBIAN
3684 If your package contains additional binaries see above.
3689 <sect1><heading><em>How</em> to write
3690 <tt>debian/shlibs.local</tt>
3694 This file is intended only as a <em>temporary</em> fix if
3695 your binaries depend on a library which doesn't provide
3696 its own <tt>/var/lib/dpkg/info/*.shlibs</tt> file yet.
3700 Let's assume you are packaging a binary <tt>foo</tt>. Your
3701 output in building the package might look like this.
3704 libbar.so.1 => /usr/X11R6/lib/libbar.so.1.0
3705 libc.so.5 => /lib/libc.so.5.2.18
3706 libX11.so.6 => /usr/X11R6/lib/libX11.so.6.0
3708 And when you ran <prgn>dpkg-shlibdeps</prgn>
3710 $ dpkg-shlibdeps -o foo
3711 dpkg-shlibdeps: warning: unable to find dependency information
3712 for shared library libbar
3713 (soname 1, path /usr/X11R6/lib/libbar.so.1.0, dependency field Depends)
3714 shlibs:Depends=elf-x11r6lib, libc5 (>= 5.2.18)
3716 The <prgn>foo</prgn> binary depends on the
3717 <prgn>libbar</prgn> shared library, but no package seems
3718 to provide a <tt>*.shlibs</tt> file in
3719 <tt>var/lib/dpkg/info/</tt>. Let's determine the package
3725 $ dpkg -S /usr/X11R6/lib/libbar.so.1.0
3726 bar1: /usr/X11R6/lib/libbar.so.1.0
3727 $ dpkg -s bar1 | grep Version
3730 This tells us that the <prgn>bar1</prgn> package, version
3731 1.0-1 is the one we are using. Now we can create our own
3732 <tt>debian/shlibs.local</tt> to temporarily fix the above
3733 problem. Include the following line into your
3734 <tt>debian/shlibs.local</tt> file.
3736 libbar 1 bar1 (>= 1.0-1)
3738 Now your package build should work. As soon as the
3739 maintainer of <prgn>libbar1</prgn> provides a
3740 <tt>shlibs</tt> file, you can remove your
3741 <tt>debian/shlibs.local</tt> file.
3747 <chapt><heading>The Operating System</heading>
3751 <heading>File system hierarchy</heading>
3755 <heading>Linux File system Structure</heading>
3758 The location of all installed files and directories must
3759 comply with the Linux File system Hierarchy Standard
3760 (FHS). The latest version of this document can be found
3761 alongside this manual or on
3762 <url id="http://www.pathname.com/fhs/">.
3763 Specific questions about following the standard may be
3764 asked on <prgn>debian-devel</prgn>, or referred to Daniel
3765 Quinlan, the FHS coordinator, at
3766 <email>quinlan@pathname.com</email>.</p></sect1>
3770 <heading>Site-specific programs</heading>
3773 As mandated by the FHS, packages must not place any
3774 files in <tt>/usr/local</tt>, either by putting them in
3775 the file system archive to be unpacked by <prgn>dpkg</prgn>
3776 or by manipulating them in their maintainer scripts.</p>
3779 However, the package may create empty directories below
3780 <tt>/usr/local</tt> so that the system administrator knows
3781 where to place site-specific files. These directories
3782 should be removed on package removal if they are
3786 Note, that this applies only to directories <em>below</em>
3787 <tt>/usr/local</tt>, not <em>in</em>
3788 <tt>/usr/local</tt>. Packages must not create sub-directories
3789 in the directory <tt>/usr/local</tt> itself, except those listed in
3790 FHS, section 4.5. However, you may create directories
3791 below them as you wish. You must not remove any of the
3792 directories listed in 4.5, even if you created them.</p>
3795 Since <tt>/usr/local</tt> can be mounted read-only from a
3796 remote server, these directories must be created and
3797 removed by the <tt>postinst</tt> and <tt>prerm</tt>
3798 maintainer scripts. These scripts must not fail if either
3799 of these operations fail. (In the future, it will be
3800 possible to tell <prgn>dpkg</prgn> not to unpack files
3801 matching certain patterns, so that the directories can be
3802 included in the <tt>.deb</tt> packages and system
3803 administrators who do not wish these directories in
3804 /usr/local do not need to have them.)</p>
3807 For example, the <prgn>emacs</prgn> package will contain
3809 mkdir -p /usr/local/lib/emacs/site-lisp || true
3811 in the <tt>postinst</tt> script, and
3813 rmdir /usr/local/lib/emacs/site-lisp && \
3814 rmdir /usr/local/lib/emacs || \
3817 in the <tt>prerm</tt> script.</p>
3820 If you do create a directory in <tt>/usr/local</tt> for
3821 local additions to a package, you should ensure that
3822 settings in <tt>/usr/local</tt> take precedence over the
3823 equivalents in <tt>/usr</tt>.</p>
3826 However, because '/usr/local' and its contents are for
3827 exclusive use of the local administrator, a package must
3828 not rely on the presence or absence of files or
3829 directories in '/usr/local' for normal operation.</p>
3832 The <tt>/usr/local</tt> directory itself and all the
3833 subdirectories created by the package should (by default) have
3834 permissions 2775 (group-writable and set-group-id) and be
3835 owned by <tt>root.staff</tt>.</p>
3840 <heading>Users and groups</heading>
3843 The Debian system can be configured to use either plain or
3844 shadow passwords.</p>
3847 Some user ids (UIDs) and group ids (GIDs) are reserved
3848 globally for use by certain packages. Because some packages
3849 need to include files which are owned by these users or
3850 groups, or need the ids compiled into binaries, these ids
3851 must be used on any Debian system only for the purpose for
3852 which they are allocated. This is a serious restriction, and
3853 we should avoid getting in the way of local administration
3854 policies. In particular, many sites allocate users and/or
3855 local system groups starting at 100.</p>
3858 Apart from this we should have dynamically allocated ids,
3859 which should by default be arranged in some sensible
3860 order--but the behavior should be configurable.</p>
3863 Packages other than <tt>base-passwd</tt> must not modify
3864 <tt>/etc/passwd</tt>, <tt>/etc/shadow</tt>,
3865 <tt>/etc/group</tt> or <tt>/etc/gshadow</tt>.</p>
3868 The UID and GID ranges are as follows:
3873 Globally allocated by the Debian project, the
3874 same on every Debian system. These ids will appear in
3875 the <tt>passwd</tt> and <tt>group</tt> files of all
3876 Debian systems, new ids in this range being added
3877 automatically as the <tt>base-passwd</tt> package is
3881 Packages which need a single statically allocated uid
3882 or gid should use one of these; their maintainers
3883 should ask the <tt>base-passwd</tt> maintainer for
3890 Dynamically allocated system users and groups.
3891 Packages which need a user or group, but can have this
3892 user or group allocated dynamically and differently on
3893 each system, should use `<tt>adduser --system</tt>' to
3894 create the group and/or user. <prgn>adduser</prgn>
3895 will check for the existence of the user or group, and
3896 if necessary choose an unused id based on the ranges
3897 specified in <tt>adduser.conf</tt>.</p></item>
3900 <tag>1000-29999:</tag>
3903 Dynamically allocated user accounts. By default
3904 <prgn>adduser</prgn> will choose UIDs and GIDs for
3905 user accounts in this range, though
3906 <tt>adduser.conf</tt> may be used to modify this
3910 <tag>30000-59999:</tag>
3912 <p>Reserved.</p></item>
3915 <tag>60000-64999:</tag>
3918 Globally allocated by the Debian project, but only
3919 created on demand. The ids are allocated centrally and
3920 statically, but the actual accounts are only created
3921 on users' systems on demand.</p>
3924 These ids are for packages which are obscure or which
3925 require many statically-allocated ids. These packages
3926 should check for and create the accounts in
3927 <tt>/etc/passwd</tt> or <tt>/etc/group</tt> (using
3928 <prgn>adduser</prgn> if it has this facility) if
3929 necessary. Packages which are likely to require
3930 further allocations should have a `hole' left after
3931 them in the allocation, to give them room to
3935 <tag>65000-65533:</tag>
3937 <p>Reserved.</p></item>
3942 <p>User `<tt>nobody</tt>.' The corresponding gid refers
3943 to the group `<tt>nogroup</tt>.'</p></item>
3949 <tt>(uid_t)(-1) == (gid_t)(-1)</tt>. NOT TO BE USED,
3950 because it is the error return sentinel value.</p>
3955 <sect id="sysvinit">
3956 <heading>System run levels</heading>
3959 <sect1 id="/etc/init.d">
3960 <heading>Introduction</heading>
3963 The <tt>/etc/init.d</tt> directory contains the scripts
3964 executed by <prgn>init</prgn> at boot time and when init
3965 state (or `runlevel') is changed (see <manref name="init"
3969 There are at least two different, yet functionally
3970 equivalent, ways of handling these scripts. For the sake
3971 of simplicity, this document describes only the symbolic
3972 link method. However, it must not be assumed by maintainer
3973 scripts that this method is being used, and any automated
3974 manipulation of the various runlevel behaviours by
3975 maintainer scripts must be performed using `update-rc.d'
3976 as described below and not by manually installing or
3977 removing symlinks. For information on the
3978 implementation details of the other method, implemented in
3979 the <tt>file-rc</tt> package, please refer to the
3980 documentation of that package.</p>
3983 These scripts are referenced by symbolic links in
3984 the <tt>/etc/rc<var>n</var>.d</tt> directories. When
3985 changing runlevels, <prgn>init</prgn> looks in the
3986 directory <tt>/etc/rc<var>n</var>.d</tt> for the scripts
3987 it should execute, where <var>n</var> is the runlevel that
3988 is being changed to, or `S' for the boot-up scripts.</p>
3991 The names of the links all have the form
3992 <tt>S<var>mm</var><var>script</var></tt> or
3993 <tt>K<var>mm</var><var>script</var></tt> where
3994 <var>mm</var> is a two-digit number and <var>script</var>
3995 is the name of the script (this should be the same as the
3996 name of the actual script in <tt>/etc/init.d</tt>.</p>
3999 When <prgn>init</prgn> changes runlevel first the targets
4000 of the links whose names starting with a <tt>K</tt> are
4001 executed, each with the single argument <tt>stop</tt>,
4002 followed by the scripts prefixed with an <tt>S</tt>, each
4003 with the single argument <tt>start</tt>. The <tt>K</tt>
4004 links are responsible for killing services and the
4005 <tt>S</tt> link for starting services upon entering the
4009 For example, if we are changing from runlevel 2 to
4010 runlevel 3, init will first execute all of the <tt>K</tt>
4011 prefixed scripts it finds in <tt>/etc/rc3.d</tt>, and then
4012 all of the <tt>S</tt> prefixed scripts. The links
4013 starting with <tt>K</tt> will cause the referred-to file
4014 to be executed with an argument of <tt>stop</tt>, and the
4015 <tt>S</tt> links with an argument of <tt>start</tt>.</p>
4018 The two-digit number <var>mm</var> is used to decide which
4019 order to start and stop things in--low-numbered links have
4020 their scripts run first. For example, the <tt>K20</tt>
4021 scripts will be executed before the <tt>K30</tt> scripts.
4022 This is used when a certain service must be started before
4023 another. For example, the name server <prgn>bind</prgn>
4024 might need to be started before the news server
4025 <prgn>inn</prgn> so that <prgn>inn</prgn> can set up its
4026 access lists. In this case, the script that starts
4027 <prgn>bind</prgn> would have a lower number than the
4028 script that starts <prgn>inn</prgn> so that it runs first:
4037 <heading>Writing the scripts</heading>
4040 Packages that include daemons for system services should
4041 place scripts in <tt>/etc/init.d</tt> to start or stop
4042 services at boot time or during a change of runlevel.
4043 These scripts should be named
4044 <tt>/etc/init.d/<var>package</var></tt>, and they should
4045 accept one argument, saying what to do:
4048 <tag><tt>start</tt></tag>
4049 <item><p>start the service,</p></item>
4051 <tag><tt>stop</tt></tag>
4052 <item><p>stop the service,</p></item>
4054 <tag><tt>restart</tt></tag>
4055 <item><p>stop and restart the service,</p></item>
4057 <tag><tt>reload</tt></tag>
4058 <item><p>cause the configuration of the service to be
4059 reloaded without actually stopping and restarting
4060 the service,</p></item>
4062 <tag><tt>force-reload</tt></tag> <item><p>cause the
4063 configuration to be reloaded if the service supports
4064 this, otherwise restart the service.</p></item>
4067 The <tt>start</tt>, <tt>stop</tt>, <tt>restart</tt>, and
4068 <tt>force-reload</tt> options should be supported by all
4069 scripts in <tt>/etc/init.d</tt>, the <tt>reload</tt>
4070 option is optional.</p>
4073 The <tt>init.d</tt> scripts should ensure that they will
4074 behave sensibly if invoked with <tt>start</tt> when the
4075 service is already running, or with <tt>stop</tt> when it
4076 isn't, and that they don't kill unfortunately-named user
4077 processes. The best way to achieve this is usually to use
4078 <prgn>start-stop-daemon</prgn>.</p>
4081 If a service reloads its configuration automatically (as
4082 in the case of <prgn>cron</prgn>, for example), the
4083 <tt>reload</tt> option of the <tt>init.d</tt> script
4084 should behave as if the configuration has been reloaded
4088 These scripts should not fail obscurely when the
4089 configuration files remain but the package has been
4090 removed, as configuration files remain on the system after
4091 the package has been removed. Only when <prgn>dpkg</prgn>
4092 is executed with the <tt>--purge</tt> option will
4093 configuration files be removed. In particular, the init
4094 script itself is usually a configuration file (see
4095 <ref id="init.d notes">), and will remain on the system if
4096 the package is removed but not purged. Therefore, you
4097 should include a <tt>test</tt> statement at the top of the
4100 test -f <var>program-executed-later-in-script</var> || exit 0
4104 Often there are some values in the `<tt>init.d</tt>'
4105 scripts that a system administrator will frequently want
4106 to change. While the scripts are frequently conffiles,
4107 modifying them requires that the administrator merge in
4108 their changes each time the package is upgraded and the
4109 conffile changes. To ease the burden on the system
4110 administrator, such configurable values should not be
4111 placed directly in the script. Instead, they should be
4112 placed in a file in `<tt>/etc/default</tt>', which
4113 typically will have the same base name as the
4114 `<tt>init.d</tt>' script. This extra file can be sourced
4115 by the script when the script runs. It must contain only
4116 variable settings and comments.
4120 To ensure that vital configurable values are always
4121 available, the `<tt>init.d</tt>' script should set default
4122 values for each of the shell variables it uses before
4123 sourcing the <tt>/etc/default/</tt> file. Also, since the
4124 `<tt>/etc/default/</tt>' file is often a conffile, the
4125 `<tt>init.d</tt>' script must behave sensibly without
4126 failing if it is deleted.
4132 <heading>Managing the links</heading>
4135 The program <prgn>update-rc.d</prgn> is provided to make
4136 it easier for package maintainers to arrange for the
4137 proper creation and removal of
4138 <tt>/etc/rc<var>n</var>.d</tt> symbolic links, or their
4139 functional equivalent if another method is being used.
4140 This may be used by maintainers in their packages'
4141 <tt>postinst</tt> and <tt>postrm</tt> scripts.</p>
4144 You must use this script to make changes to
4145 <tt>/etc/rc<var>n</var>.d</tt> and <em>never</em> either
4146 include any <tt>/etc/rc<var>n</var>.d</tt> symbolic links
4147 in the actual archive or manually create or remove the
4148 symbolic links in maintainer scripts. (The latter will
4149 fail if an alternative method of maintaining runlevel
4150 information is being used.)</p>
4153 By default <prgn>update-rc.d</prgn> will start services in
4154 each of the multi-user state runlevels (2, 3, 4, and 5)
4155 and stop them in the halt runlevel (0), the single-user
4156 runlevel (1) and the reboot runlevel (6). The system
4157 administrator will have the opportunity to customize
4158 runlevels by either running <prgn>update-rc.d</prgn>, by
4159 simply adding, moving, or removing the symbolic links in
4160 <tt>/etc/rc<var>n</var>.d</tt> if symbolic links are being
4161 used, or by modifying <tt>/etc/runlevel.conf</tt> if the
4162 <tt>file-rc</tt> method is being used.</p>
4165 To get the default behavior for your package, put in your
4166 <tt>postinst</tt> script
4168 update-rc.d <var>package</var> defaults >/dev/null
4170 and in your <tt>postrm</tt>
4172 if [ purge = "$1" ]; then
4173 update-rc.d <var>package</var> remove >/dev/null
4178 This will use a default sequence number of 20. If it does
4179 not matter when or in which order the script is run, use
4180 this default. If it does, then you should talk to the
4181 maintainer of the <prgn>sysvinit</prgn> package or post to
4182 <tt>debian-devel</tt>, and they will help you choose a
4186 For more information about using <tt>update-rc.d</tt>,
4187 please consult its manpage <manref name="update-rc.d"
4188 section="8">.</p></sect1>
4192 <heading>Boot-time initialization</heading>
4195 There used to be another directory, <tt>/etc/rc.boot</tt>,
4196 which contained scripts which were run once per machine
4197 boot. This has been deprecated in favour of links from
4198 <tt>/etc/rcS.d</tt> to files in <tt>/etc/init.d</tt> as
4199 described in <ref id="/etc/init.d">. Packages must not
4200 place files in <tt>/etc/rc.boot</tt>.</p>
4202 <sect1 id="init.d notes">
4203 <heading>Notes</heading>
4206 <em>Do not</em> include the
4207 <tt>/etc/rc<var>n</var>.d/*</tt> symbolic links in the
4208 <tt>.deb</tt> file system archive! <em>This will cause
4209 problems!</em> You must create them with
4210 <prgn>update-rc.d</prgn>, as above.</p>
4213 <em>Do not</em> include the
4214 <tt>/etc/rc<var>n</var>.d/*</tt> symbolic links in
4215 <prgn>dpkg</prgn>'s conffiles list! <em>This will cause
4216 problems!</em> You should, however, treat the
4217 <tt>/etc/init.d</tt> scripts as configuration files,
4218 either by marking them as conffiles or managing them
4219 correctly in the maintainer scripts (see
4220 <ref id="config files">). (This is important since we want
4221 to give the local system administrator the chance to adapt
4222 the scripts to the local system--e.g., to disable a
4223 service without de-installing the package, or to specify
4224 some special command line options when starting a
4225 service--while making sure her changes aren't lost during
4226 the next package upgrade.)</p>
4230 <heading>Example</heading>
4233 The <prgn>bind</prgn> DNS (nameserver) package wants to
4234 make sure that the nameserver is running in multiuser
4235 runlevels, and is properly shut down with the system. It
4236 puts a script in <tt>/etc/init.d</tt>, naming the script
4237 appropriately <tt>bind</tt>. As you can see, the script
4238 interprets the argument <tt>reload</tt> to send the
4239 nameserver a <tt>HUP</tt> signal (causing it to reload its
4240 configuration); this way the user can say
4241 <tt>/etc/init.d/bind reload</tt> to reload the name
4242 server. The script has one configurable value, which can
4243 be used to pass parameters to the named program at
4251 # Original version by Robert Leslie
4252 # <rob@mars.org>, edited by iwj and cs
4254 test -x /usr/sbin/named || exit 0
4256 # Source defaults file.
4258 if [ -f /etc/default/bind ]; then
4265 echo -n "Starting domain name service: named"
4266 start-stop-daemon --start --quiet --exec /usr/sbin/named \
4271 echo -n "Stopping domain name service: named"
4272 start-stop-daemon --stop --quiet \
4273 --pidfile /var/run/named.pid --exec /usr/sbin/named
4277 echo -n "Restarting domain name service: named"
4278 start-stop-daemon --stop --quiet \
4279 --pidfile /var/run/named.pid --exec /usr/sbin/named
4280 start-stop-daemon --start --verbose --exec /usr/sbin/named \
4284 force-reload|reload)
4285 echo -n "Reloading configuration of domain name service: named"
4286 start-stop-daemon --stop --signal 1 --quiet \
4287 --pidfile /var/run/named.pid --exec /usr/sbin/named
4291 echo "Usage: /etc/init.d/bind {start|stop|restart|reload|force-reload}" >&2
4301 Complementing the above init script is a file
4302 '<tt>/etc/default/bind</tt>', which contains configurable
4303 parameters used by the script.
4307 # Specified parameters to pass to named. See named(8).
4308 # You may uncomment the following line, and edit to taste.
4314 Another example on which to base your <tt>/etc/init.d</tt>
4315 scripts is in <tt>/etc/init.d/skeleton</tt>.</p>
4318 If this package is happy with the default setup from
4319 <prgn>update-rc.d</prgn>, namely an ordering number of 20
4320 and having named running in all runlevels, it can say in
4321 its <tt>postinst</tt>:
4323 update-rc.d bind defaults >/dev/null
4325 And in its <tt>postrm</tt>, to remove the links when the
4328 if [ purge = "$1" ]; then
4329 update-rc.d bind remove >/dev/null
4335 <heading>Cron jobs</heading>
4338 Packages must not modify the configuration file
4339 <tt>/etc/crontab</tt>, and they must not modify the files in
4340 <tt>/var/spool/cron/crontabs</tt>.</p>
4343 If a package wants to install a job that has to be executed
4344 via cron, it should place a file with the name if the
4345 package in one of the following directories:
4351 As these directory names imply, the files within them are
4352 executed on a daily, weekly, or monthly basis,
4353 respectively. The exact times are listed in
4354 <tt>/etc/crontab</tt>.</p>
4357 All files installed in any of these directories must be
4358 scripts (shell scripts, Perl scripts, etc.) so that they can
4359 easily be modified by the local system administrator. In
4360 addition, they should be treated as configuration files.</p>
4363 If a certain job has to be executed more frequently than
4364 daily, the package should install a file
4365 <tt>/etc/cron.d/<var>package-name</var></tt>. This file uses
4366 the same syntax as <tt>/etc/crontab</tt> and is processed by
4367 <prgn>cron</prgn> automatically. The file must also be
4368 treated as a configuration file. (Note, that entries in the
4369 <tt>/etc/cron.d</tt> directory are not handled by
4370 <prgn>anacron</prgn>. Thus, you should only use this
4371 directory for jobs which may be skipped if the system is not
4375 The scripts or crontab entries in these directories should
4376 check if all necessary programs are installed before they
4377 try to execute them. Otherwise, problems will arise when a
4378 package was removed but not purged since configuration files
4379 are kept on the system in this situation.</p>
4383 <heading>Console messages</heading>
4386 This section describes different formats for messages
4387 written to standard output by the <tt>/etc/init.d</tt>
4388 scripts. The intent is to improve the consistency of
4389 Debian's startup and shutdown look and feel.</p>
4392 Please look very careful at the details. We want to get the
4393 messages to look exactly the same way concerning spaces,
4394 punctuation, and case of letters.</p>
4397 Here is a list of overall rules that you should use when you
4398 create output messages. They can be useful if you have a
4399 non-standard message that isn't covered in the sections
4406 Every message should cover one line, start with a
4407 capital letter and end with a period `.'.</p></item>
4412 If you want to express that the computer is working on
4413 something (performing a specific task, not starting or
4414 stopping a program), we use an ``ellipsis'', namely
4415 three dots `...'. Note that we don't insert spaces in
4416 front of or behind the dots. If the task has been
4417 completed we write `done.' and a line feed.</p></item>
4422 Design your messages as if the computer is telling you
4423 what he is doing (let him be polite :-) but don't
4424 mention ``him'' directly. For example, if you think
4427 I'm starting network daemons: nfsd mountd.
4431 Starting network daemons: nfsd mountd.
4432 </example></p></item>
4436 The following formats should be used</p>
4441 <p>when daemons get started.</p>
4444 Use this format if your script starts one or more
4445 daemons. The output should look like this (a single
4446 line, no leading spaces):
4448 Starting <description>: <daemon-1> <daemon-2> <...> <daemon-n>.
4450 The <description> should describe the subsystem
4451 the daemon or set of daemons are part of, while
4452 <daemon-1> up to <daemon-n> denote each
4453 daemon's name (typically the file name of the
4457 For example, the output of /etc/init.d/lpd would look like:
4459 Starting printer spooler: lpd.
4463 This can be achieved by saying
4465 echo -n "Starting printer spooler: lpd"
4466 start-stop-daemon --start --quiet lpd
4469 in the script. If you have more than one daemon to
4470 start, you should do the following:
4472 echo -n "Starting remote file system services:"
4473 echo -n " nfsd"; start-stop-daemon --start --quiet nfsd
4474 echo -n " mountd"; start-stop-daemon --start --quiet mountd
4475 echo -n " ugidd"; start-stop-daemon --start --quiet ugidd
4478 This makes it possible for the user to see what takes
4479 so long and when the final daemon has been
4480 started. You should be careful where to put spaces: In the
4481 example above the system administrator can easily
4482 comment out a line if he don't wants to start a
4483 specific daemon, while the displayed message still
4484 looks good.</p></item>
4488 <p>when something needs to be configured.</p>
4491 If you have to set up different parameters of the
4492 system upon boot up, you should use this format:
4494 Setting <parameter> to `<value>'.
4498 You can use the following echo statement to get the quotes right:
4500 echo "Setting DNS domainname to \`"value"'."
4504 Note that the left quotation mark (`) is different
4505 from the right (').</p></item>
4508 <p>when a daemon is stopped.</p>
4511 When you stop a daemon you should issue a message
4512 similar to the startup message, except that `Starting'
4513 is replaced with `Stopping'.</p>
4516 So stopping the printer daemon will like like this:
4518 Stopping printer spooler: lpd.
4519 </example></p></item>
4522 <p>when something is executed.</p>
4525 There are several examples where you have to run a
4526 program at system startup or shutdown to perform a
4527 specific task. For example, setting the system's clock
4528 via `netdate' or killing all processes when the system
4529 comes down. Your message should like this:
4531 Doing something very useful...done.
4533 You should print the `done.' right after the job has been completed,
4534 so that the user gets informed why he has to wait. You can get this
4537 echo -n "Doing something very useful..."
4541 in your script.</p></item>
4544 <p>when the configuration is reloaded.</p>
4547 When a daemon is forced to reload its configuration
4548 files you should use the following format:
4550 Reloading <daemon's-name> configuration...done.
4551 </example></p></item>
4554 <p>when none of the above rules apply.</p>
4557 If you have to print a message that doesn't fit into
4558 the styles described above, you can use something
4559 appropriate, but please have a look at the overall
4560 rules listed above.</p></item>
4565 <heading>Menus</heading>
4568 Menu entries should follow the current menu policy as
4569 defined in the file <ftpsite>ftp.debian.org</ftpsite> in
4570 <ftppath>/debian/doc/package-developer/menu-policy.text.gz</ftppath>
4571 or your local mirror. In addition, it is included in the
4572 <tt>debian-policy</tt> package.
4576 The Debian <tt>menu</tt> packages provides a unique
4577 interface between packages providing applications and
4578 documents, and <em>menu programs</em> (either X window
4579 managers or text-based menu programs as
4580 <prgn>pdmenu</prgn>).</p>
4583 All packages that provide applications that need not be
4584 passed any special command line arguments for normal
4585 operation should register a menu entry for those
4586 applications, so that users of the <tt>menu</tt> package
4587 will automatically get menu entries in their window
4588 managers, as well in shells like <tt>pdmenu</tt>.</p>
4591 Please refer to the <em>Debian Menu System</em> document
4592 that comes with the <tt>menu</tt> package for information
4593 about how to register your applications and web
4599 <heading>Multimedia handlers</heading>
4602 Packages which provide the ability to view/show/play,
4603 compose, edit or print MIME types should register themselves
4604 as such following the current MIME support policy as defined
4605 in the file found on <ftpsite>ftp.debian.org</ftpsite> in
4606 <ftppath>/debian/doc/package-developer/mime-policy.text.gz</ftppath>
4607 or your local mirror. In addition, it is included in the
4608 <tt>debian-policy</tt> package.
4612 MIME (Multipurpose Internet Mail Extensions, RFC 1521) is a
4613 mechanism for encoding files and data streams and providing
4614 meta-information about them, in particular their type (e.g.
4615 audio or video) and format (e.g. PNG, HTML, MP3).
4619 Registration of MIME type handlers allows programs like mail
4620 user agents and web browsers to to invoke these handlers to
4621 view, edit or display MIME types they don't support
4627 <heading>Keyboard configuration</heading>
4630 To achieve a consistent keyboard configuration (i.e., all
4631 applications interpret a keyboard event the same way) all
4632 programs in the Debian distribution must be configured to
4633 comply with the following guidelines.</p>
4636 Here is a list that contains certain keys and their interpretation:
4639 <tag><tt><--</tt></tag>
4640 <item><p>delete the character to the left of the cursor</p></item>
4642 <tag><tt>Delete</tt></tag>
4643 <item><p>delete the character to the right of the cursor</p></item>
4645 <tag><tt>Control+H</tt></tag>
4646 <item><p>emacs: the help prefix</p></item>
4649 The interpretation of any keyboard events should be independent
4650 of the terminal that's used, be it a virtual console, an X
4651 terminal emulator, an rlogin/telnet session, etc.</p>
4654 The following list explains how the different programs
4655 should be set up to achieve this:</p>
4658 <list compact="compact">
4659 <item><p>`<tt><--</tt>' generates KB_Backspace in
4662 <item><p>`<tt>Delete</tt>' generates KB_Delete in X.</p></item>
4666 X translations are set up to make KB_Backspace
4667 generate ASCII DEL, and to make KB_Delete generate
4668 <tt>ESC [ 3 ~</tt> (this is the vt220 escape code for
4669 the `delete character' key). This must be done by
4670 loading the resources using xrdb on all local X
4671 displays, not using the application defaults, so that
4672 the translation resources used correspond to the
4673 xmodmap settings.</p></item>
4677 The Linux console is configured to make
4678 `<tt><--</tt>' generate DEL, and `Delete' generate
4679 <tt>ESC [ 3 ~</tt> (this is the case at the
4683 X applications are configured so that Backspace
4684 deletes left, and Delete deletes right. Motif
4685 applications already work like this.</p></item>
4687 <item><p>stty erase <tt>^?</tt> .</p></item>
4690 The `xterm' terminfo entry should have <tt>ESC [ 3
4691 ~</tt> for kdch1, just like TERM=linux and
4692 TERM=vt220.</p></item>
4695 Emacs is programmed to map KB_Backspace or the `stty
4696 erase' character to delete-backward-char, and
4697 KB_Delete or kdch1 to delete-forward-char, and
4698 <tt>^H</tt> to help as always.</p></item>
4701 Other applications use the `stty erase' character and
4702 kdch1 for the two delete keys, with ASCII DEL being
4703 `delete previous character' and kdch1 being `delete
4704 character under cursor'.</p></item>
4708 This will solve the problem except for:</p>
4711 <list compact="compact">
4713 Some terminals have a <tt><--</tt> key that cannot
4714 be made to produce anything except <tt>^H</tt>. On
4715 these terminals Emacs help will be unavailable on
4716 <tt>^H</tt> (assuming that the `stty erase' character
4717 takes precedence in Emacs, and has been set
4718 correctly). M-x help or F1 (if available) can be used
4722 Some operating systems use <tt>^H</tt> for stty erase.
4723 However, modern telnet versions and all rlogin
4724 versions propagate stty settings, and almost all UNIX
4725 versions honour stty erase. Where the stty settings
4726 are not propagated correctly things can be made to
4727 work by using stty manually.</p></item>
4730 Some systems (including previous Debian versions) use
4731 xmodmap to arrange for both <tt><--</tt> and Delete
4732 to generate KB_Delete. We can change the behavior
4733 of their X clients via the same X resources that we
4734 use to do it for our own, or have our clients be
4735 configured via their resources when things are the
4736 other way around. On displays configured like this
4737 Delete will not work, but <tt><--</tt>
4741 Some operating systems have different kdch1 settings
4742 in their terminfo for xterm and others. On these
4743 systems the Delete key will not work correctly when
4744 you log in from a system conforming to our policy, but
4745 <tt><--</tt> will.</p></item>
4752 <heading>Environment variables</heading>
4755 A program must not depend on environment variables to get
4756 reasonable defaults. (That's because these environment
4757 variables would have to be set in a system-wide
4758 configuration file like /etc/profile, which is not supported
4762 If a program usually depends on environment variables for its
4763 configuration, the program should be changed to fall back to
4764 a reasonable default configuration if these environment
4765 variables are not present. If this cannot be done easily
4766 (e.g., if the source code of a non-free program is not
4767 available), the program must be replaced by a small
4768 `wrapper' shell script which sets the environment variables
4769 if they are not already defined, and calls the original program.</p>
4772 Here is an example of a wrapper script for this purpose:
4776 BAR=${BAR:-/var/lib/fubar}
4778 exec /usr/lib/foo/foo "$@"
4782 Furthermore, as <tt>/etc/profile</tt> is a configuration
4783 file of the <prgn>base-files</prgn> package, other packages must not
4784 put any environment variables or other commands into that
4789 <heading>Files</heading>
4793 <heading>Binaries</heading>
4796 Two different packages must not install programs with
4797 different functionality but with the same filenames. (The
4798 case of two programs having the same functionality but
4799 different implementations is handled via `alternatives.')
4800 If this case happens, one of the programs must be
4801 renamed. The maintainers should report this to the
4802 developers' mailing and try to find a consensus about
4803 which package will have to be renamed. If a consensus can
4804 not be reached, <em>both</em> programs must be
4808 Generally the following compilation parameters should be used:
4811 CFLAGS = -O2 -Wall # sane warning options vary between programs
4813 install -s # (or use strip on the files in debian/tmp)
4817 Note that by default all installed binaries should be stripped,
4818 either by using the <tt>-s</tt> flag to
4819 <prgn>install</prgn>, or by calling <prgn>strip</prgn> on
4820 the binaries after they have been copied into
4821 <tt>debian/tmp</tt> but before the tree is made into a
4825 The <tt>-N</tt> flag should not be used. On a.out systems
4826 it may have been useful for some very small binaries, but
4827 for ELF it has no good effect.</p>
4830 Debugging symbols are useful for error diagnosis,
4831 investigation of core dumps (which may be submitted by users
4832 in bug reports), or testing and developing the
4833 software. Therefore it is recommended to support building
4834 the package with debugging information through the following
4835 interface: If the environment variable
4836 <tt>DEB_BUILD_OPTIONS</tt> contains the string
4837 <tt>debug</tt>, compile the software with debugging
4838 information (usually this involves adding the <tt>-g</tt>
4839 flag to <tt>CFLAGS</tt>). This allows the generation of a
4840 build tree with debugging information. If the environment
4841 variable <tt>DEB_BUILD_OPTIONS</tt> contains the string
4842 <tt>nostrip</tt>, do not strip the files at installation
4843 time. This allows one to generate a package with debugging
4844 information included. The following makefile snippet is only
4845 an example of how one may test for either condition:
4848 Rationale: Building by default with -g causes more
4849 wasted CPU cycles since the information is stripped away
4850 anyway. The package can by default build without -g if
4851 it also provides a mechanism to easily be rebuilt with
4852 debugging information. This can be done by providing a
4853 "build-debug" make target, or allowing the user to
4854 specify "DEB_BUILD_OPTIONS=debug" in the environment while
4855 compiling that package.
4857 <p>Now this has several added benefits:
4861 It is actually easier to build debugging bins and
4862 libraries this way (no more editing debian/rules
4863 or similar) since it provides a documented way of
4864 getting this type of build.</p>
4868 There will be much less wasted cpu time for the
4869 autobuilders since not having debugging
4870 information (and hence also not having to strip
4871 it) will increase the speed of compiles. This
4872 skips an entire pass of the compiler.
4883 INSTALL_FILE = $(INSTALL) -p -o root -g root -m 644
4884 INSTALL_PROGRAM = $(INSTALL) -p -o root -g root -m 755
4885 INSTALL_SCRIPT = $(INSTALL) -p -o root -g root -m 755
4886 INSTALL_DIR = $(INSTALL) -p -d -o root -g root -m 755
4888 ifneq (,$(findstring debug,$(DEB_BUILD_OPTIONS)))
4891 ifeq (,$(findstring nostrip,$(DEB_BUILD_OPTIONS)))
4892 INSTALL_PROGRAM += -s
4896 Please note that the above example is merely informative,
4897 and is not a policy mandate. You may have to massage this
4898 example in order to make it work for your package.
4903 It is up to the package maintainer to decide what
4904 compilation options are best for the package. Certain
4905 binaries (such as computationally-intensive programs) will
4906 function better with certain flags (<tt>-O3</tt>, for
4907 example); feel free to use them. Please use good judgment
4908 here. Don't use flags for the sake of it; only use them
4909 if there is good reason to do so. Feel free to override
4910 the upstream author's ideas about which compilation
4911 options are best--they are often inappropriate for our
4912 environment.</p></sect>
4916 <heading>Libraries</heading>
4919 All libraries must have a shared version in the lib
4920 package and a static version in the lib-dev package. The
4921 shared version must be compiled with <tt>-fPIC</tt>, and
4922 the static version must not be. In other words, each
4923 <tt>*.c</tt> file will need to be compiled twice.</p>
4926 You must specify the gcc option <tt>-D_REENTRANT</tt>
4927 when building a library (either static or shared) to make
4928 the library compatible with LinuxThreads.</p>
4931 Note that all installed shared libraries should be
4934 strip --strip-unneeded <your-lib>
4936 (The option `--strip-unneeded' makes <tt>strip</tt> remove
4937 only the symbols which aren't needed for relocation
4938 processing.) Shared libraries can function perfectly well
4939 when stripped, since the symbols for dynamic linking are
4940 in a separate part of the ELF object file.</p>
4943 Note that under some circumstances it may be useful to
4944 install a shared library unstripped, for example when
4945 building a separate package to support debugging.
4949 An ever increasing number of packages are using libtool to
4950 do their linking. The latest GNU libtools (>= 1.3a) can take
4951 advantage of the metadata in the installed libtool archive
4952 files (`*.la'). The main advantage of libtool's .la files is
4953 that it allows libtool to store and subsequently access
4954 metadata with respect to the libraries it builds. libtool
4955 will search for those files, which contain a lot of useful
4956 information about a library (e.g. dependency libraries for
4957 static linking). Also, they're <em>essential</em> for
4958 programs using libltdl.
4962 Certainly libtool is fully capable of linking against shared
4963 libraries which don't have .la files, but being a mere shell
4964 script it can add considerably to the build time of a
4965 libtool using package if that shell-script has to derive all
4966 this information from first principles for each library every
4967 time it is linked. With the advent of libtool-1.4 (and to a
4968 lesser extent libtool-1.3), the .la files will also store
4969 information about inter-library dependencies which cannot
4970 necessarily be derived after the .la file is deleted.
4974 Packages that use libtool to create shared libraries should
4975 include the <em>.la</em> files in the <em>-dev</em>
4976 packages, with the exception that if the package relies on
4977 libtool's <em>libltdl</em> library, in which case the .la
4978 files must go in the run-time library package. This is a
4979 good idea in general, and especially for static linking
4984 You must make sure that you use only released versions of
4985 shared libraries to build your packages; otherwise other
4986 users will not be able to run your binaries
4987 properly. Producing source packages that depend on
4988 unreleased compilers is also usually a bad
4995 <heading>Shared libraries</heading>
4998 Packages involving shared libraries should be split up
4999 into several binary packages.</p>
5002 For a straightforward library which has a development
5003 environment and a runtime kit including just shared
5004 libraries you need to create two packages:
5005 <tt><var>libraryname</var><var>soname</var></tt>
5006 (<var>soname</var> is the shared object name of the shared
5007 library--it's the thing that has to match exactly between
5008 building an executable and running it for the dynamic
5009 linker to be able run the program; usually the
5010 <var>soname</var> is the major number of the library) and
5011 <tt><var>libraryname</var><var>soname</var>-dev</tt>.</p>
5014 If you prefer only to support one development version at a
5015 time you may name the development package
5016 <tt><var>libraryname</var>-dev</tt>; otherwise you may
5017 wish to use <prgn>dpkg</prgn>'s conflicts mechanism to
5018 ensure that the user only installs one development version
5019 at a time (after all, different development versions are
5020 likely to have the same header files in them, causing a
5021 filename clash if both are installed). Typically the
5022 development version should also have an exact version
5023 dependency on the runtime library, to make sure that
5024 compilation and linking happens correctly.</p>
5027 Packages which use the shared library should have a
5028 dependency on the name of the shared library package,
5029 <tt><var>libraryname</var><var>soname</var></tt>. When
5030 the <var>soname</var> changes you can have both versions
5031 of the library installed while moving from the old library
5035 If your package has some run-time support programs which
5036 use the shared library you must not put them in
5037 the shared library package. If you do that then you won't
5038 be able to install several versions of the shared library
5039 without getting filename clashes. Instead, either create
5040 a third package for the runtime binaries (this package
5041 might typically be named
5042 <tt><var>libraryname</var>-runtime</tt>--note the absence
5043 of the <var>soname</var> in the package name) or if the
5044 development package is small include them in there.</p>
5047 If you have several shared libraries built from the same
5048 source tree you may lump them all together into a single
5049 shared library package, provided that you change all their
5050 <var>soname</var>s at once (so that you don't get filename
5051 clashes if you try to install different versions of the
5052 combined shared libraries package).</p>
5055 You should follow the directions in the <em>Debian Packaging
5056 Manual</em> for putting the shared library in its package,
5057 and you must include a <tt>shlibs</tt> control area
5058 file with details of the dependencies for packages which
5059 use the library.</p>
5062 Shared libraries should not be installed
5063 executable, since <prgn>ld.so</prgn> does not require this
5064 and trying to execute a shared library results in a core
5069 <heading>Scripts</heading>
5072 All command scripts, including the package maintainer
5073 scripts inside the package and used by <prgn>dpkg</prgn>,
5074 should have a <tt>#!</tt> line naming the shell to be used
5075 to interpret them.</p>
5078 In the case of Perl scripts this should be
5079 <tt>#!/usr/bin/perl</tt>.</p>
5082 Shell scripts (<prgn>sh</prgn> and <prgn>bash</prgn>)
5083 should almost certainly start with <tt>set -e</tt> so that
5084 errors are detected. Every script should use
5085 <tt>set -e</tt> or check the exit status of <em>every</em>
5089 The standard shell interpreter `<tt>/bin/sh</tt>' can be a
5090 symbolic link to any POSIX compatible shell, if <tt>echo
5091 -n</tt> does not generate a newline.
5094 Debian policy specifies POSIX behavior for /bin/sh, but
5095 echo -n has widespread use in the Linux community
5096 (including especially debian policy, the linux kernel
5097 source, many debian scripts, etc.). This echo -n
5098 mechanism is valid but not required under POSIX, hence
5099 this explicit addition. Also, rumour has it that this
5100 shall be mandated under the LSB anyway.
5104 specifying `<tt>/bin/sh</tt>' as interpreter should only
5105 use POSIX features. If a script requires non-POSIX
5106 features from the shell interpreter, the appropriate shell
5107 must be specified in the first line of the script (e.g.,
5108 `<tt>#!/bin/bash</tt>') and the package must depend on the
5109 package providing the shell (unless the shell package is
5110 marked `Essential', e.g., in the case of
5115 You may wish to restrict your script to POSIX features when possible so
5116 that it may use <tt>/bin/sh</tt> as its interpreter. If
5117 your script works with <prgn>ash</prgn>, it's probably
5118 POSIX compliant, but if you are in doubt, use
5119 <tt>/bin/bash</tt>.</p>
5122 Perl scripts should check for errors when making any
5123 system calls, including <tt>open</tt>, <tt>print</tt>,
5124 <tt>close</tt>, <tt>rename</tt> and <tt>system</tt>.</p>
5127 <prgn>csh</prgn> and <prgn>tcsh</prgn> should be avoided
5128 as scripting languages. See <em>Csh Programming
5129 Considered Harmful</em>, one of the <tt>comp.unix.*</tt>
5130 FAQs. It can be found on
5131 <url id="http://language.perl.com/versus/csh.whynot">, or
5132 <url id="http://www.cpan.org/doc/FMTEYEWTK/versus/csh.whynot">
5133 or even on <ftpsite>ftp.cpan.org</ftpsite>
5134 <ftppath>/pub/perl/CPAN/doc/FMTEYEWTK/versus/csh.whynot</ftppath>.
5135 If an upstream package comes with <prgn>csh</prgn> scripts
5136 then you must make sure that they start with
5137 <tt>#!/bin/csh</tt> and make your package depend on the
5138 <prgn>c-shell</prgn> virtual package.</p>
5141 Any scripts which create files in world-writeable
5142 directories (e.g., in <tt>/tmp</tt>) must use a
5143 mechanism which will fail if a file with the same name
5147 The Debian base distribution provides the
5148 <prgn>tempfile</prgn> and <prgn>mktemp</prgn> utilities
5149 for use by scripts for this purpose.</p></sect>
5153 <heading>Symbolic links</heading>
5156 In general, symbolic links within a top-level directory
5157 should be relative, and symbolic links pointing from one
5158 top-level directory into another should be absolute. (A
5159 top-level directory is a sub-directory of the root
5163 In addition, symbolic links should be specified as short
5164 as possible, i.e., link targets like `foo/../bar' are
5168 Note that when creating a relative link using
5169 <prgn>ln</prgn> it is not necessary for the target of the
5170 link to exist relative to the working directory you're
5171 running <prgn>ln</prgn> from; nor is it necessary to
5172 change directory to the directory where the link is to be
5173 made. Simply include the string that should appear as the
5174 target of the link (this will be a pathname relative to
5175 the directory in which the link resides) as the first
5176 argument to <prgn>ln</prgn>.</p>
5179 For example, in your <prgn>Makefile</prgn> or
5180 <tt>debian/rules</tt>, do things like:
5182 ln -fs gcc $(prefix)/bin/cc
5183 ln -fs gcc debian/tmp/usr/bin/cc
5184 ln -fs ../sbin/sendmail $(prefix)/bin/runq
5185 ln -fs ../sbin/sendmail debian/tmp/usr/bin/runq
5189 A symbolic link pointing to a compressed file should
5190 always have the same file extension as the referenced
5191 file. (For example, if a file `<tt>foo.gz</tt>' is
5192 referenced by a symbolic link, the filename of the link
5193 has to end with `<tt>.gz</tt>' too, as in
5194 `bar.gz.')</p></sect>
5198 <heading>Device files</heading>
5201 Packages must not include device files in the package file
5205 If a package needs any special device files that are not
5206 included in the base system, it must call
5207 <prgn>MAKEDEV</prgn> in the <tt>postinst</tt> script,
5208 after asking the user for permission to do so.</p>
5211 Packages must not remove any device files in the
5212 <tt>postrm</tt> or any other script. This is left to the
5213 system administrator.</p>
5216 Debian uses the serial devices
5217 <tt>/dev/ttyS*</tt>. Programs using the old
5218 <tt>/dev/cu*</tt> devices should be changed to use
5219 <tt>/dev/ttyS*</tt>.</p>
5222 <sect id="config files">
5223 <heading>Configuration files</heading>
5225 <heading>Definitions</heading>
5228 <tag>configuration file</tag>
5230 A file that affects the operation of program, or
5231 provides site- or host-specific information, or
5232 otherwise customizes the behavior of program.
5233 Typically, configuration files are intended to be
5234 modified by the system administrator (if needed or
5235 desired) to conform to local policy or provide more
5236 useful site-specific behavior.</p>
5239 <tag><tt>conffile</tt></tag>
5241 A file listed in a package's <tt>conffiles</tt>
5242 file, and is treated specially by <prgn>dpkg</prgn>
5243 (see the <em>Debian Packaging Manual</em>).</p>
5249 The distinction between these two is important; they are
5250 not interchangeable concepts. Almost all
5251 <tt>conffiles</tt> are configuration files, but many
5252 configuration files are not <tt>conffiles</tt>.</p>
5255 Note that a script that embeds configuration information
5256 (such as most of the files in <tt>/etc/init.d</tt> and
5257 <tt>/etc/cron.{daily,weekly,monthly}</tt>) is de-facto a
5258 configuration file and should be treated as such.</p>
5262 <heading>Location</heading>
5264 Any configuration files created or used by your package
5265 must reside in <tt>/etc</tt>. If there are several you
5266 should consider creating a subdirectory of <tt>/etc</tt>
5267 named after your package.</p>
5270 If your package creates or uses configuration files
5271 outside of <tt>/etc</tt>, and it is not feasible to modify
5272 the package to use the <tt>/etc</tt>, you should still put
5273 the files in <tt>/etc</tt> and create symbolic links to
5274 those files from the location that the package
5279 <heading>Behavior</heading>
5281 Configuration file handling must conform to the following
5285 <p>local changes must be preserved during a package
5289 <p>configuration files must be preserved when the
5290 package is removed, and only deleted when the
5291 package is purged.</p>
5296 The easy way to achieve this behavior is to make the
5297 configuration file a <tt>conffile</tt>. This is
5298 appropriate only if it is possible to distribute a default
5299 version that will work for most installations, although
5300 some system administrators may choose to modify it. This
5301 implies that the default version will be part of the
5302 package distribution, and must not be modified by the
5303 maintainer scripts during installation (or at any other
5308 In order to ensure that local changes are preserved
5309 correctly, no package may contain or make hard links to
5313 Rationale: There are two problems with hard links.
5314 The first is that some editors break the link while
5315 editing one of the files, so that the two files may
5316 unwittingly become different. The second is that
5317 <prgn>dpkg</prgn> might break the hard link while
5318 upgrading <tt>conffile</tt>s.
5323 The other way to do it is via the maintainer scripts.
5324 In this case, the configuration file must not be listed as
5325 a <tt>conffile</tt> and must not be part of the package
5326 distribution. If the existence of a file is required for
5327 the package to be sensibly configured it is the
5328 responsibility of the package maintainer to write scripts
5329 which correctly create, update, maintain and
5330 remove-on-purge the file. These scripts must be idempotent
5331 (i.e., must work correctly if <prgn>dpkg</prgn> needs to
5332 re-run them due to errors during installation or removal),
5333 must cope with all the variety of ways <prgn>dpkg</prgn>
5334 can call maintainer scripts, must not overwrite or
5335 otherwise mangle the user's configuration without asking,
5336 must not ask unnecessary questions (particularly during
5337 upgrades), and otherwise be good citizens.</p>
5340 The scripts are not required to configure every possible option for
5341 the package, but only those necessary to get the package
5342 running on a given system. Ideally the sysadmin should not
5343 have to do any configuration other than that done
5344 (semi-)automatically by the <tt>postinst</tt> script.</p>
5347 A common practice is to create a script called
5348 <tt><var>package</var>-configure</tt> and have the
5349 package's <tt>postinst</tt> call it if and only if the
5350 configuration file does not already exist. In certain
5351 cases it is useful for there to be an example or template
5352 file which the maintainer scripts use. Such files should
5353 be in <tt>/usr/share/doc</tt> if they are examples or
5354 <tt>/usr/lib</tt> if they are templates, and should be
5355 perfectly ordinary <prgn>dpkg</prgn>-handled files
5356 (<em>not</em> <tt>conffiles</tt>).</p>
5359 These two styles of configuration file handling must
5360 not be mixed, for that way lies madness:
5361 <prgn>dpkg</prgn> will ask about overwriting the file
5362 every time the package is upgraded.</p>
5367 <heading>Sharing configuration files</heading>
5369 Packages which specify the same file as
5370 `<tt>conffile</tt>' must be tagged as <em>conflicting</em>
5375 The maintainer scripts must not alter the conffile of
5376 <em>any</em> package, including the one the scripts belong
5380 If two or more packages use the same configuration file
5381 and it is reasonable for both to be installed at the same
5382 time, one of these packages must be defined as
5383 <em>owner</em> of the configuration file, i.e., it will be
5384 the package to list that distributes the file and lists it
5385 as a <tt>conffile</tt>. Other packages that use the
5386 configuration file must depend on the owning package if
5387 they require the configuration file to operate. If the
5388 other package will use the configuration file if present,
5389 but is capable of operating without it, no dependency need
5393 If it is desirable for two or more related packages to
5394 share a configuration file <em>and</em> for all of the
5395 related packages to be able to modify that configuration
5396 file, then the following should be done:
5400 have one of the related packages (the "core"
5401 package) manage the configuration file with
5402 maintainer scripts as described in the previous
5406 the core package should also provide a program that
5407 the other packages may use to modify the
5408 configuration file.</p>
5412 the related packages must use the provided program
5413 to make any modifications to the configuration file.
5414 They should either depend on the core package to
5415 guarantee that the configuration modifier program is
5416 available or accept gracefully that they cannot
5417 modify the configuration file if it is not.</p>
5422 Sometimes it's appropriate to create a new package which
5423 provides the basic infrastructure for the other packages
5424 and which manages the shared configuration files. (Check
5425 out the <tt>sgml-base</tt> package as an example.)</p>
5429 <heading>User configuration files ("dotfiles")</heading>
5432 Files in <tt>/etc/skel</tt> will automatically be copied
5433 into new user accounts by <prgn>adduser</prgn>. They
5434 should not be referenced there by any program.</p>
5437 Therefore, if a program needs a dotfile to exist in
5438 advance in <tt>$HOME</tt> to work sensibly, that dotfile
5439 should be installed in <tt>/etc/skel</tt> (and listed in
5440 conffiles, if it is not generated and modified dynamically
5441 by the package's installation scripts).</p>
5444 However, programs that require dotfiles in order to
5445 operate sensibly (dotfiles that they do not create
5446 themselves automatically, that is) are a bad thing, and
5447 programs should be configured by the Debian default
5448 installation as close to normal as possible.</p>
5451 Therefore, if a program in a Debian package needs to be
5452 configured in some way in order to operate sensibly that
5453 configuration should be done in a site-wide global
5454 configuration file elsewhere in <tt>/etc</tt>. Only if the
5455 program doesn't support a site-wide default configuration
5456 and the package maintainer doesn't have time to add it
5457 may a default per-user file be placed in
5458 <tt>/etc/skel</tt>.</p>
5461 <tt>/etc/skel</tt> should be as empty as we can make it.
5462 This is particularly true because there is no easy
5463 mechanism for ensuring that the appropriate dotfiles are
5464 copied into the accounts of existing users when a package
5470 <heading>Log files</heading>
5472 The traditional approach to log files has been to set up ad
5473 hoc log rotation schemes using simple shell scripts and
5474 cron. While this approach is highly customizable, it
5475 requires quite a lot of sysadmin work. Even though the
5476 original Debian system helped a little by automatically
5477 installing a system which can be used as a template, this
5478 was deemed not enough.
5482 A better scheme is to use logrotate, a GPL'd program
5483 developed by Red Hat, which centralizes log management. It
5484 has both a configuration file (<tt>/etc/logrotate.conf</tt>)
5485 and a directory where packages can drop logrotation info
5486 (<tt>/etc/logrotate.d</tt>).
5490 Log files should usually be named
5491 <tt>/var/log/<var>package</var>.log</tt>. If you have many
5492 log files, or need a separate directory for permissions
5493 reasons (<tt>/var/log</tt> is writable only by
5494 <tt>root</tt>), you should usually create a directory named
5495 <tt>/var/log/<var>package</var></tt>.</p>
5498 Log files must be rotated occasionally so
5499 that they don't grow indefinitely; the best way to do this
5500 is to drop a script into the directory
5501 <tt>/etc/logrotate.d</tt> and use the facilities provided by
5502 logrotate. Here is a good example for a logrotate config
5503 file (for more information see <manref name="logrotate"
5511 /etc/init.d/foo force-reload
5515 Which rotates all files under `/var/log/foo', saves 12
5516 compressed generations, and sends a HUP signal at the end of
5522 Log files should be removed when the package is
5523 purged (but not when it is only removed), by checking the
5524 argument to the <tt>postrm</tt> script (see the <em>Debian
5525 Packaging Manual</em> for details).</p>
5530 <heading>Permissions and owners</heading>
5533 The rules in this section are guidelines for general use.
5534 If necessary you may deviate from the details below.
5535 However, if you do so you must make sure that what is done
5536 is secure and you should try to be as consistent as possible
5537 with the rest of the system. You should probably also
5538 discuss it on <prgn>debian-devel</prgn> first.</p>
5541 Files should be owned by <tt>root.root</tt>, and made
5542 writable only by the owner and universally readable (and
5543 executable, if appropriate).</p>
5546 Directories should be mode 755 or (for group-writability)
5547 mode 2775. The ownership of the directory should be
5548 consistent with its mode--if a directory is mode 2775, it
5549 should be owned by the group that needs write access to
5553 Setuid and setgid executables should be mode 4755 or 2755
5554 respectively, and owned by the appropriate user or group.
5555 They should not be made unreadable (modes like 4711 or
5556 2711 or even 4111); doing so achieves no extra security,
5557 because anyone can find the binary in the freely available
5558 Debian package--it is merely inconvenient. For the same
5559 reason you should not restrict read or execute permissions
5560 on non-set-id executables.</p>
5563 Some setuid programs need to be restricted to particular
5564 sets of users, using file permissions. In this case they
5565 should be owned by the uid to which they are set-id, and
5566 by the group which should be allowed to execute them.
5567 They should have mode 4754; there is no point in making
5568 them unreadable to those users who must not be allowed to
5572 You must not arrange that the system administrator can only
5573 reconfigure the package to correspond to their local
5574 security policy by changing the permissions on a binary.
5575 Ordinary files installed by <prgn>dpkg</prgn> (as opposed
5576 to conffiles and other similar objects) have their
5577 permissions reset to the distributed permissions when the
5578 package is reinstalled. Instead you should consider (for
5579 example) creating a group for people allowed to use the
5580 program(s) and making any setuid executables executable
5581 only by that group.</p>
5584 If you need to create a new user or group for your package
5585 there are two possibilities. Firstly, you may need to
5586 make some files in the binary package be owned by this
5587 user or group, or you may need to compile the user or
5588 group id (rather than just the name) into the binary
5589 (though this latter should be avoided if possible, as in
5590 this case you need a statically allocated id).</p>
5593 If you need a statically allocated id, you must ask for a
5594 user or group id from the base system
5595 maintainer, and must not release the package until you
5596 have been allocated one. Once you have been allocated one
5597 you must make the package depend on a version of the base
5598 system with the id present in <tt>/etc/passwd</tt> or
5599 <tt>/etc/group</tt>, or alternatively arrange for your
5600 package to create the user or group itself with the
5601 correct id (using <tt>adduser</tt>) in its pre- or
5602 post-installation script (the latter is to be preferred if
5603 it is possible).</p>
5606 On the other hand, the program might be able to determine the
5607 uid or gid from the group name at runtime, so that a
5608 dynamic id can be used. In this case you should choose an
5609 appropriate user or group name, discussing this on
5610 <prgn>debian-devel</prgn> and checking with the base
5611 system maintainer that it is unique and that they do not
5612 wish you to use a statically allocated id instead. When
5613 this has been checked you must arrange for your package to
5614 create the user or group if necessary using
5615 <prgn>adduser</prgn> in the pre- or post-installation
5616 script (again, the latter is to be preferred if it is
5620 Note that changing the numeric value of an id associated with a name
5621 is very difficult, and involves searching the file system for all
5622 appropriate files. You need to think carefully whether a static or
5623 dynamic id is required, since changing your mind later will cause
5629 <heading>Customized programs</heading>
5631 <sect id="arch-spec">
5632 <heading>Architecture specification strings</heading>
5635 If a program needs to specify an <em>architecture specification
5636 string</em> in some place, the following format should be used:
5638 <arch>-<os>
5640 where `<arch>' is one of the following: i386, alpha, arm, m68k,
5641 powerpc, sparc and `<os>' is one of: linux, gnu. Use
5642 of <em>gnu</em> in this string is reserved for the GNU/Hurd
5643 operating system.</p>
5645 Note, that we don't want to use `<arch>-debian-linux'
5646 to apply to the rule `architecture-vendor-os' since this
5647 would make our programs incompatible to other Linux
5648 distributions. Also note, that we don't use
5649 `<arch>-unknown-linux', since the `unknown' does not
5650 look very good.</p></sect>
5654 <heading>Daemons</heading>
5657 The configuration files <tt>/etc/services</tt>,
5658 <tt>/etc/protocols</tt>, and <tt>/etc/rpc</tt> are managed
5659 by the <prgn>netbase</prgn> package and may not be modified
5660 by other packages.</p>
5663 If a package requires a new entry in one of these files, the
5664 maintainer should get in contact with the
5665 <prgn>netbase</prgn> maintainer, who will add the entries
5666 and release a new version of the <prgn>netbase</prgn>
5670 The configuration file <tt>/etc/inetd.conf</tt> must not be
5671 modified by the package's scripts except via the
5672 <prgn>update-inetd</prgn> script or the
5673 <prgn>DebianNet.pm</prgn> Perl module.</p>
5676 If a package wants to install an example entry into
5677 <tt>/etc/inetd.conf</tt>, the entry must be preceded with
5678 exactly one hash character (<tt>#</tt>). Such lines are
5679 treated as `commented out by user' by the
5680 <prgn>update-inetd</prgn> script and are not changed or
5681 activated during a package updates.</p></sect>
5685 <heading>Using pseudo-ttys and modifying wtmp, utmp and lastlog</heading>
5688 Some programs need to create pseudo-ttys. This should be done
5689 using Unix98 ptys if the C library supports it. The resulting
5690 program must not be installed setuid root, unless that
5691 is required for other functionality.
5695 The files <tt>/var/run/utmp</tt>, <tt>/var/log/wtmp</tt> and
5696 <tt>/var/log/lastlog</tt> must be installed writeable by
5697 group utmp. Programs who need to modify those files must
5698 be installed setgid utmp.
5703 <heading>Editors and pagers</heading>
5706 Some programs have the ability to launch an editor or pager
5707 program to edit or display a text document. Since there are
5708 lots of different editors and pagers available in the Debian
5709 distribution, the system administrator and each user should
5710 have the possibility to choose his/her preferred editor and
5714 In addition, every program should choose a good default
5715 editor/pager if none is selected by the user or system
5719 Thus, every program that launches an editor or pager must
5720 use the EDITOR or PAGER environment variables to determine
5721 the editor/pager the user wants to get started. If these
5722 variables are not set, the programs <tt>/usr/bin/editor</tt>
5723 and <tt>/usr/bin/pager</tt> should be used, respectively.</p>
5726 These two files are managed through `alternatives.' That is,
5727 every package providing an editor or pager must call the
5728 <prgn>update-alternatives</prgn> script to register these
5732 If it is very hard to adapt a program to make us of the
5733 EDITOR and PAGER variables, that program may be configured
5734 to use <tt>/usr/bin/sensible-editor</tt> and
5735 <tt>/usr/bin/sensible-pager</tt> as editor or pager program,
5736 respectively. These are two scripts provided in the Debian
5737 base system that check the EDITOR and PAGER variables and
5738 launch the appropriate program or fall back to
5739 <tt>/usr/bin/editor</tt> and <tt>/usr/bin/pager</tt>,
5743 A program may also use the VISUAL environment variable to
5744 determine the user's choice of editor. If it exists, it
5745 should take precedence over EDITOR. This is in fact what
5746 <tt>/usr/bin/sensible-editor</tt> does.</p>
5749 It is not required for a package to depend on
5750 `editor' and `pager', nor is it required for a package to
5751 provide such virtual packages.
5754 The Debian base system already provides an editor and
5763 <sect id="web-appl">
5764 <heading>Web servers and applications</heading>
5767 This section describes the locations and URLs that should
5768 be used by all web servers and web application in the Debian
5774 <p>Cgi-bin executable files are installed in the
5777 /usr/lib/cgi-bin/<cgi-bin-name>
5779 and should be referred to as
5781 http://localhost/cgi-bin/<cgi-bin-name>
5782 </example></p></item>
5785 <item><p>Access to html documents</p>
5788 Html documents for a package are stored in
5789 <tt>/usr/share/doc/<var>package</var></tt> but should
5790 be accessed via symlinks as
5791 <tt>/usr/doc/<var>package</var></tt><footnote> for
5792 backward compatibility, see <ref id="usrdoc"></footnote>
5793 and can be referred to as
5795 http://localhost/doc/<package>/<filename>
5796 </example></p></item>
5799 <item><p>Web Document Root</p>
5802 Web Applications should try to avoid storing files in
5803 the Web Document Root. Instead they should use the
5804 /usr/share/doc/<package> directory for documents and
5805 register the Web Application via the menu package. If
5806 access to the web-root is unavoidable then use
5810 as the Document Root. This might be just a
5811 symbolic link to the location where the sysadmin has
5812 put the real document root.</p>
5815 </enumlist></p></sect>
5819 <heading>Mail transport, delivery and user agents</heading>
5822 Debian packages which process electronic mail, whether
5823 mail-user-agents (MUAs) or mail-transport-agents (MTAs),
5824 must make sure that they are compatible with the
5825 configuration decisions below. Failure to do this may
5826 result in lost mail, broken <tt>From:</tt> lines, and other
5827 serious brain damage!</p>
5830 The mail spool is <tt>/var/spool/mail</tt> and the interface
5831 to send a mail message is <tt>/usr/sbin/sendmail</tt> (as
5832 per the FHS). The mail spool is part of the base system
5833 and not part of the MTA package.</p>
5836 All Debian MUAs, MTAs, MDAs and other mailbox accessing
5837 programs (like IMAP daemons) must lock the mailbox in an
5838 NFS-safe way. This means that <tt>fcntl()</tt> locking must
5839 be combined with dot locking. To avoid deadlocks, a
5840 program should use <tt>fcntl()</tt> first and dot locking
5841 after this or alternatively implement the two locking
5842 methods in a non blocking way<footnote>
5844 If it is not possible to establish both locks, the
5845 system shouldn't wait for the second lock to be
5846 established, but remove the first lock, wait a (random)
5847 time, and start over locking again.</p>
5848 </footnote>. Using the functions <tt>maillock</tt> and
5849 <tt>mailunlock</tt> provided by the
5850 <tt>liblockfile*</tt><footnote>
5852 <tt>liblockfile</tt> version >>1.01</p>
5853 </footnote> packages is the recommended way to realize this.
5857 Mailboxes are generally 660 <tt><var>user</var>.mail</tt>
5858 unless the user has chosen otherwise. A MUA may remove a
5859 mailbox (unless it has nonstandard permissions) in which
5860 case the MTA or another MUA must recreate it if needed.
5861 Mailboxes must be writable by group mail.</p>
5864 The mail spool is 2775 <tt>root.mail</tt>, and MUAs should
5865 be setgid mail to do the locking mentioned above (and
5866 must obviously avoid accessing other users' mailboxes
5867 using this privilege).</p>
5870 <tt>/etc/aliases</tt> is the source file for the system mail
5871 aliases (e.g., postmaster, usenet, etc.)--it is the one
5872 which the sysadmin and <tt>postinst</tt> scripts may edit.
5873 After <tt>/etc/aliases</tt> is edited the program or human
5874 editing it must call <prgn>newaliases</prgn>. All MTA
5875 packages must come with a <prgn>newaliases</prgn> program,
5876 even if it does nothing, but older MTA packages do not do
5877 this so programs should not fail if <prgn>newaliases</prgn>
5878 cannot be found.</p>
5881 The convention of writing <tt>forward to
5882 <var>address</var></tt> in the mailbox itself is not
5883 supported. Use a <tt>.forward</tt> file instead.</p>
5886 The <prgn>rmail</prgn> program used by UUCP
5887 for incoming mail should be <tt>/usr/sbin/rmail</tt>.
5888 Likewise, <prgn>rsmtp</prgn>, for receiving
5889 batch-SMTP-over-UUCP, should be <tt>/usr/sbin/rsmtp</tt> if it
5893 If you need to know what name to use (for example) on
5894 outgoing news and mail messages which are generated locally,
5895 you should use the file <tt>/etc/mailname</tt>. It will
5896 contain the portion after the username and <tt>@</tt> (at)
5897 sign for email addresses of users on the machine (followed
5901 A package should check for the existence of this file. If
5902 it exists it should use it without comment. (An MTA's
5903 prompting configuration script may wish to prompt the user
5904 even if it finds this file exists.) If it does not exist it
5905 should prompt the user for the value and store it in
5906 <tt>/etc/mailname</tt> as well as using it in the package's
5907 configuration. The prompt should make it clear that the
5908 name will not just be used by that package. For example, in
5909 this situation the INN package says:
5911 Please enter the `mail name' of your system. This is the
5912 hostname portion of the address to be shown on outgoing
5913 news and mail messages. The default is
5914 <var>syshostname</var>, your system's host name. Mail
5915 name [`<var>syshostname</var>']:
5917 where <var>syshostname</var> is the output of <tt>hostname
5918 --fqdn</tt>.</p></sect>
5922 <heading>News system configuration</heading>
5925 All the configuration files related to the NNTP (news)
5926 servers and clients should be located under
5927 <tt>/etc/news</tt>.</p>
5930 There are some configuration issues that apply to a number
5931 of news clients and server packages on the machine. These
5935 <tag>/etc/news/organization</tag>
5936 <item><p>A string which should appear as the
5937 organization header for all messages posted
5938 by NNTP clients on the machine</p></item>
5940 <tag>/etc/news/server</tag>
5941 <item><p>Contains the FQDN of the upstream NNTP
5942 server, or localhost if the local machine is
5943 an NNTP server.</p></item>
5946 Other global files may be added as required for cross-package news
5947 configuration.</p></sect>
5951 <heading>Programs for the X Window System</heading>
5954 <em>Programs that may be configured with support for the X Window
5955 System</em> must be configured to do so and must declare any
5956 package dependencies necessary to satisfy their runtime
5957 requirements when using the X Window System, unless the package
5958 in question is of standard or higher priority, in which case
5959 X-specific binaries may be split into a separate package, or
5960 alternative versions of the package with X support may be
5966 <em>Packages which provide an X server</em> that, directly or
5967 indirectly, communicates with real input and display hardware
5968 should declare in their control data that they provide the
5969 virtual package <tt>xserver</tt>.
5972 This implements current practice, and provides an actual
5973 policy for usage of the "xserver" virtual package which
5974 appears in the virtual packages list. In a nutshell, X
5975 servers that interface directly with the display and input
5976 hardware or via another subsystem (e.g., GGI) should provide
5977 xserver. Things like Xvfb, Xnest, and Xprt should not.
5983 <em>Packages that provide a terminal emulator</em> for the X
5984 Window System which support a terminal type with a terminfo
5985 description provided in the <tt>ncurses-base</tt> package
5986 should declare in their control data that they provide the
5987 virtual package <tt>x-terminal-emulator</tt>. They should
5988 also register themselves as an alternative for
5989 <tt>/usr/bin/x-terminal-emulator</tt>, with a priority of
5994 <em>Packages that provide window managers</em> should declare in
5995 their control data that they provide the virtual package
5996 <tt>x-window-manager</tt>. They should also register themselves as an
5997 alternative for <tt>/usr/bin/x-window-manager</tt>, with a priority
5998 calculated as follows:
6000 <item>Start with a priority of 20.</item>
6001 <item>If the window manager supports the Debian menu system,
6002 add 20 points if this support is available in the
6003 package's default configuration (i.e., no
6004 configuration files belonging to the system or user
6005 have to be edited to activate the feature); if
6006 configuration files must be modified, add only 10
6008 <item>If the window manager permits the X session to be
6009 restarted using a <em>different</em> window manager
6010 (without killing the X server) in its default
6011 configuration, add 10 points; otherwise add
6017 <em>Packages that provide fonts for the X Window System</em>
6018 must do a number of things to ensure that they are both
6019 available without modification of the X or font server
6020 configuration, and that they do not corrupt files used by
6021 other font packages to register information about themselves.
6024 Fonts of any type supported by the X Window System
6025 should be be in a separate binary package from any
6026 executables, libraries, or documentation (except that
6027 specific to the fonts shipped); if a program or
6028 library is <em>unusable</em> without one or more
6029 specific fonts, the package containing the program or
6030 library should declare a dependency on the package(s)
6031 containing the font(s) it requires.
6034 BDF fonts should be converted to PCF fonts with the
6035 <tt>bdftopcf</tt> utility (available in the
6036 <tt>xutils</tt> package, <tt>gzip</tt>ped, and
6037 placed in a directory that corresponds to their
6041 100 dpi fonts should be placed in
6042 <tt>/usr/X11R6/lib/X11/fonts/100dpi/</tt>.
6045 75 dpi fonts should be placed in
6046 <tt>/usr/X11R6/lib/X11/fonts/75dpi/</tt>.
6049 Character-cell fonts, cursor fonts, and other
6050 low-resolution fonts should be placed in
6051 <tt>/usr/X11R6/lib/X11/fonts/misc/</tt>.
6056 Speedo fonts should be placed in
6057 <tt>/usr/X11R6/lib/X11/fonts/Speedo/</tt>.
6060 Type 1 fonts should be placed in
6061 <tt>/usr/X11R6/lib/X11/fonts/Type1/</tt>. If font
6062 metric files are available, they may be placed here as
6066 Subdirectories of <tt>/usr/X11R6/lib/X11/fonts/</tt>
6067 other than those listed above should be neither created nor
6068 used. (The <tt>PEX</tt> and <tt>cyrillic</tt> directories are
6069 excepted for historical reasons, but installation of files into
6070 these directories remains discouraged.)
6073 Font packages may, instead of placing files directly in
6074 the X font directories listed above, provide symbolic links in
6075 the font directory which point to the files' actual location
6076 in the filesystem. Such a location should comply with the
6080 Font packages should not contain both 75dpi and 100dpi
6081 versions of a font. If both are available, they should be
6082 provided in separate binary packages with "-75dpi" or "-100dpi"
6083 appended to the names of the packages containing the
6084 corresponding fonts.
6087 Fonts destined for the <tt>misc</tt> subdirectory should
6088 not be included in the same package as 75dpi or 100dpi fonts;
6089 instead, they should be provided in a separate package with
6090 "-misc" appended to its name.
6093 Font packages <em>must not</em> provide the files
6094 <tt>fonts.dir</tt>, <tt>fonts.alias</tt>, or
6095 <tt>fonts.scale</tt> in a font directory.
6098 <tt>fonts.dir</tt> files must not be provided at
6102 <tt>fonts.alias</tt> and <tt>fonts.scale</tt>
6103 files, if needed, should be provided in the
6105 <tt>/etc/X11/fonts/<em>fontdir</em>/<em>package</em>.<em>extension</em></tt>,
6106 where <em>fontdir</em> is the name of the
6108 <tt>/usr/X11R6/lib/X11/fonts/</tt> where the
6109 package's corresponding fonts are stored (e.g.,
6110 <tt>75dpi</tt> or <tt>misc</tt>),
6111 <em>package</em> is the name of the package that
6112 provides these fonts, and <em>extension</em> is
6113 either <tt>scale</tt> or <tt>alias</tt>,
6114 whichever corresponds to the file
6120 Font packages must declare a dependency on
6121 <tt>xutils</tt> and, in the package
6122 post-installation and post-removal scripts, invoke the
6123 <tt>mkfontdir</tt> command on each directory into
6124 which they installed fonts.
6127 Font packages that provide one or more
6128 <tt>fonts.scale</tt> files as described above must declare a
6129 versioned dependency on <tt>xutils (>=
6130 4.0.2)</tt> and invoke <tt>update-fonts-scale</tt> on each
6131 directory into which they installed fonts
6132 <em>before</em> invoking <tt>mkfontdir</tt> on that
6133 directory. This invocation must occur in both the
6134 post-installation and post-removal scripts.
6137 Font packages that provide one or more
6138 <tt>fonts.alias</tt> files as described above must
6139 declare a versioned dependency on <tt>xutils
6140 (>= 4.0.2)</tt> and, in the package
6141 post-installation and post-removal scripts, invoke
6142 <tt>update-fonts-alias</tt> on each directory into
6143 which they installed fonts.
6146 Font packages must not provide alias names for the
6147 fonts they include which collide with alias names already in
6148 use by fonts already packaged.
6151 Font packages must not provide fonts with the same XLFD
6152 registry name as another font already packaged.
6158 <em>Application defaults</em> files must be installed in the
6159 directory <tt>/usr/X11R6/lib/X11/app-defaults/</tt>.
6161 <p>Note: This shall change very shortly.</p>
6163 They should not be registered as <em>conffile</em>s or
6164 otherwise treated as configuration files. Customization of
6165 programs' X resources may be supported with the provision of
6166 a file with the same name as that of the package placed in
6167 the <tt>/etc/X11/Xresources/</tt> directory, which must
6168 registered as a <em>conffile</em>. <em>Important:</em>
6169 packages that install files into the
6170 <tt>/etc/X11/Xresources/</tt> directory <em>must</em>
6171 declare a conflict with <tt>xbase (<<
6172 3.3.2.3a-2)</tt>; if this is not done it is possible for the
6173 installing package to destroy a previously-existing
6174 <tt>/etc/X11/Xresources</tt> <em>file</em> which had been
6175 customized by the system administrator.
6177 <p>Rationale: clarifies the language to properly
6178 address the package maintainer, not the system
6179 administrator, as to how to manage
6180 /etc/X11/Xresources.</p>
6186 <em>Packages using the X Window System should abide by the FHS
6187 standard whenever possible</em>; they should install binaries,
6188 libraries, manual pages, and other files in FHS-mandated
6189 locations wherever possible. This means that files must
6190 not be installed into <tt>/usr/X11R6/bin/</tt>,
6191 <tt>/usr/X11R6/lib/</tt>, or <tt>/usr/X11R6/man/</tt> unless
6192 this is necessary for the package to operate properly.
6193 Configuration files for window managers and display managers
6194 should be placed in a subdirectory of <tt>/etc/X11/</tt>
6195 corresponding to the package name due to these programs'
6196 tight integration with the mechanisms of the X Window
6197 System. Application-level programs should use the
6198 <tt>/etc/</tt> directory unless otherwise mandated by
6199 policy. The installation of files into subdirectories of
6200 <tt>/usr/X11R6/include/X11/</tt> and
6201 <tt>/usr/X11R6/lib/X11/</tt> is permitted but discouraged;
6202 package maintainers should determine if subdirectories of
6203 <tt>/usr/lib/</tt> and <tt>/usr/share/</tt> can be used
6204 instead (symlinks from the X11R6 directories to
6205 FHS-compliant locations is encouraged if the program is not
6206 easily configured to look elsewhere for its files).
6207 Packages must not provide -- or install files into -- the
6208 directories <tt>/usr/bin/X11/</tt>,
6209 <tt>/usr/include/X11/</tt>, or <tt>/usr/lib/X11/</tt>.
6210 Files within a package should, however, make reference to
6211 these directories, rather than their X11R6-named
6212 counterparts <tt>/usr/X11R6/bin/</tt>,
6213 <tt>/usr/X11R6/include/X11/</tt>, and
6214 <tt>/usr/X11R6/lib/X11/</tt>, if the resources being
6215 referred to have not been moved to FHS-compliant locations.
6219 <em>Programs that require the non-DFSG-compliant OSF/Motif
6220 library</em> should be compiled against and tested with
6221 LessTif (a free re-implementation of Motif) instead. If the
6222 maintainer judges that the program or programs do not work
6223 sufficiently well with LessTif to be distributed and
6224 supported, but do so when compiled against Motif, then two
6225 versions of the package should be created; one linked
6226 statically against Motif and with <tt>-smotif</tt> appended
6227 to the package name, and one linked dynamically against
6228 Motif and with <tt>-dmotif</tt> appended to the package
6229 name. Both Motif-linked versions are dependent upon
6230 non-DFSG-compliant software and thus cannot be uploaded to
6231 the main distribution; if the software is itself
6232 DFSG-compliant it may be uploaded to the contrib
6233 distribution. While known existing versions of OSF/Motif
6234 permit unlimited redistribution of binaries linked against
6235 the library (whether statically or dynamically), it is the
6236 package maintainer's responsibility to determine whether
6237 this is permitted by the license of the copy of OSF/Motif in
6238 his or her possession.
6244 <heading>Emacs lisp programs</heading>
6247 Please refer to the `Debian Emacs Policy' (documented in
6248 <tt>debian-emacs-policy.gz</tt> of the
6249 <prgn>emacsen-common</prgn> package) for details of how to
6250 package emacs lisp programs.</p></sect>
6254 <heading>Games</heading>
6257 The permissions on /var/games are 755
6258 <tt>root.root</tt>.</p>
6261 Each game decides on its own security policy.</p>
6264 Games which require protected, privileged access to
6265 high-score files, savegames, etc., may be made
6266 set-<em>group</em>-id (mode 2755) and owned by
6267 <tt>root.games</tt>, and use files and directories with
6268 appropriate permissions (770 <tt>root.games</tt>, for
6269 example). They must not be made
6270 set-<em>user</em>-id, as this causes security problems. (If
6271 an attacker can subvert any set-user-id game they can
6272 overwrite the executable of any other, causing other players
6273 of these games to run a Trojan horse program. With a
6274 set-group-id game the attacker only gets access to less
6275 important game data, and if they can get at the other
6276 players' accounts at all it will take considerably more
6280 Some packages, for example some fortune cookie programs, are
6281 configured by the upstream authors to install with their
6282 data files or other static information made unreadable so
6283 that they can only be accessed through set-id programs
6284 provided. You should not do this in a Debian package: anyone can
6285 download the <tt>.deb</tt> file and read the data from it,
6286 so there is no point making the files unreadable. Not
6287 making the files unreadable also means that you don't have
6288 to make so many programs set-id, which reduces the risk of a
6292 As described in the FHS, binaries of games should be
6293 installed in the directory <tt>/usr/games</tt>. This also
6294 applies to games that use the X Window System. Manual pages
6295 for games (X and non-X games) should be installed in
6296 <tt>/usr/share/man/man6</tt>.</p>
6300 <chapt><heading>Documentation</heading>
6304 <heading>Manual pages</heading>
6307 You should install manual pages in <prgn>nroff</prgn> source
6308 form, in appropriate places under <tt>/usr/share/man</tt>. You
6309 should only use sections 1 to 9 (see the FHS for more
6310 details). You must not install a preformatted `cat
6314 Each program, utility, and function should have an
6315 associated manpage included in the same package. It is
6316 suggested that all configuration files also have a manual
6317 page included as well.
6321 If no manual page is available for a particular program,
6322 utility, function or configuration file and this is reported as a bug on
6323 debian-bugs, a symbolic link from the requested manual page
6324 to the <manref name="undocumented" section="7"> manual page
6325 may be provided. This symbolic link can be created from
6326 <tt>debian/rules</tt> like this:
6328 ln -s ../man7/undocumented.7.gz \
6329 debian/tmp/usr/share/man/man[1-9]/the_requested_manpage.[1-9].gz
6331 This manpage claims that the lack of a manpage has been
6332 reported as a bug, so you may only do this if it really has
6333 (you can report it yourself, if you like). Do not close the
6334 bug report until a proper manpage is available.</p>
6337 You may forward a complaint about a missing manpage to the
6338 upstream authors, and mark the bug as forwarded in the
6339 Debian bug tracking system. Even though the GNU Project do
6340 not in general consider the lack of a manpage to be a bug,
6341 we do--if they tell you that they don't consider it a bug
6342 you should leave the bug in our bug tracking system open
6346 Manual pages should be installed compressed using <tt>gzip
6350 If one manpage needs to be accessible via several names it
6351 is better to use a symbolic link than the <tt>.so</tt>
6352 feature, but there is no need to fiddle with the relevant
6353 parts of the upstream source to change from <tt>.so</tt> to
6354 symlinks--don't do it unless it's easy. You should not create hard
6355 links in the manual page directories, nor put
6356 absolute filenames in <tt>.so</tt> directives. The filename
6357 in a <tt>.so</tt> in a manpage should be relative to the
6358 base of the manpage tree (usually
6359 <tt>/usr/share/man</tt>).</p></sect>
6363 <heading>Info documents</heading>
6366 Info documents should be installed in <tt>/usr/share/info</tt>.
6367 They should be compressed with <tt>gzip -9</tt>.</p>
6370 Your package should call <prgn>install-info</prgn> to update the Info
6372 file, in its post-installation script:
6374 install-info --quiet --section Development Development \
6375 /usr/share/info/foobar.info
6379 It is a good idea to specify a section for the location of
6380 your program; this is done with the <tt>--section</tt>
6381 switch. To determine which section to use, you should look
6382 at <tt>/usr/share/info/dir</tt> on your system and choose the most
6383 relevant (or create a new section if none of the current
6384 sections are relevant). Note that the <tt>--section</tt>
6385 flag takes two arguments; the first is a regular expression
6386 to match (case-insensitively) against an existing section,
6387 the second is used when creating a new one.</p>
6390 You should remove the entries in the pre-removal script:
6392 install-info --quiet --remove /usr/share/info/foobar.info
6396 If <prgn>install-info</prgn> cannot find a description entry
6397 in the Info file you must supply one. See <manref
6398 name="install-info" section="8"> for details.</p>
6402 <heading>Additional documentation</heading>
6405 Any additional documentation that comes with the package may
6406 be installed at the discretion of the package maintainer.
6407 Text documentation should be installed in a directory
6408 <tt>/usr/share/doc/<var>package</var></tt>, where
6409 <var>package</var> is the name of the package, and
6410 compressed with <tt>gzip -9</tt> unless it is small.</p>
6413 If a package comes with large amounts of documentation which
6414 many users of the package will not require you should create
6415 a separate binary package to contain it, so that it does not
6416 take up disk space on the machines of users who do not need
6417 or want it installed.</p>
6420 It is often a good idea to put text information files
6421 (<tt>README</tt>s, changelogs, and so forth) that come with
6422 the source package in <tt>/usr/share/doc/<var>package</var></tt>
6423 in the binary package. However, you don't need to install
6424 the instructions for building and installing the package, of
6428 Files in <tt>/usr/share/doc</tt> should not be referenced by
6429 any program, and the system administrator should be able to
6430 delete them without causing any programs to break. Any files
6431 that are referenced by programs but are also useful as
6432 standalone documentation should be installed under
6433 <tt>/usr/share/<package$gt;/</tt> and symlinked in
6434 <tt>/usr/share/doc/<package$gt;/</tt>.
6440 <heading>Accessing the documentation</heading>
6443 Former Debian releases placed all additional documentation
6444 in <tt>/usr/doc/<var>package</var></tt>. To realize a
6446 <tt>/usr/share/doc/<var>package</var></tt>, each package
6447 must maintain a symlink <tt>/usr/doc/<var>package</var></tt>
6448 that points to the new location of its documentation in
6449 <tt>/usr/share/doc/<var>package</var></tt><footnote>These
6450 symlinks will be removed in the future, but they have to be
6451 there for compatibility reasons until all packages have
6452 moved and the policy is changed accordingly.</footnote>.
6453 The symlink must be created when the package is installed;
6454 it cannot be contained in the package itself due to problems
6455 with <prgn>dpkg</prgn>. One reasonable way to accomplish
6456 this is to put the following in the package's
6457 <prgn>postinst</prgn>:
6459 if [ "$1" = "configure" ]; then
6460 if [ -d /usr/doc -a ! -e /usr/doc/#PACKAGE# \
6461 -a -d /usr/share/doc/#PACKAGE# ]; then
6462 ln -sf ../share/doc/#PACKAGE# /usr/doc/#PACKAGE#
6466 And the following in the package's <prgn>prerm</prgn>:
6468 if [ \( "$1" = "upgrade" -o "$1" = "remove" \) \
6469 -a -L /usr/doc/#PACKAGE# ]; then
6470 rm -f /usr/doc/#PACKAGE#
6477 <heading>Preferred documentation formats</heading>
6480 The unification of Debian documentation is being carried out
6484 If your package comes with extensive documentation in a
6485 mark up format that can be converted to various other formats
6486 you should if possible ship HTML versions in a binary
6487 package, in the directory
6488 <tt>/usr/share/doc/<var>appropriate package</var></tt> or its
6491 <p>The rationale: The important thing here is that HTML
6492 docs should be available in <em>some</em> package, not
6493 necessarily in the main binary package, though. </p>
6498 Other formats such as PostScript may be provided at your
6502 <sect id="copyrightfile">
6503 <heading>Copyright information</heading>
6506 Every package must be accompanied by a verbatim copy of its
6507 copyright and distribution license in the file
6508 /usr/share/doc/<package-name>/copyright. This file must
6509 neither be compressed nor be a symbolic link.</p>
6512 In addition, the copyright file must say where the upstream
6513 sources (if any) were obtained, and should explain briefly what
6514 modifications were made in the Debian version of the package
6515 compared to the upstream one. It should name the original
6516 authors of the package and the Debian maintainer(s) who were
6517 involved with its creation.</p>
6520 A copy of the file which will be installed in
6521 <tt>/usr/share/doc/<var>package</var>/copyright</tt> should be
6522 in <tt>debian/copyright</tt>.</p>
6526 /usr/share/doc/<package-name> may be a symbolic link to a
6527 directory in /usr/share/doc only if two packages both come from
6528 the same source and the first package has a "Depends"
6529 relationship on the second. These rules are important
6530 because copyrights must be extractable by mechanical
6534 Packages distributed under the UCB BSD license, the Artistic
6535 license, the GNU GPL, and the GNU LGPL should refer to the
6536 files /usr/share/common-licenses/BSD,
6537 /usr/share/common-licenses/Artistic,
6538 /usr/share/common-licenses/GPL, and
6539 /usr/share/common-licenses/LGPL.
6542 Why "licenses" and not "copyright"? Because
6543 <tt>/usr/doc/copyright</tt> used to contain all the
6544 copyright files, plus the four common licenses GPL,
6545 LGPL, Artistic and BSD. Now individual copyright files
6546 for packages are no longer in a common directory. Once
6547 <tt>/usr/doc/copyright</tt> is almost empty it makes
6548 sense to rename "copyright" to "licenses"
6551 Why "common-licenses" and not "licenses"? Because if I
6552 put just "licenses" I'm sure I will receive a bug report
6553 saying "license foo is not included in the licenses
6554 directory. They are not all the licenses, just a few
6555 common ones. I could use /usr/share/doc/common-licenses
6556 but I think this is too long, and, after all, the GPL
6557 does not "document" anything, it is merely a license.
6563 You should not use the copyright file as a general <tt>README</tt>
6564 file. If your package has such a file it should be
6565 installed in <tt>/usr/share/doc/<var>package</var>/README</tt> or
6566 <tt>README.Debian</tt> or some other appropriate place.</p>
6570 <heading>Examples</heading>
6573 Any examples (configurations, source files, whatever),
6574 should be installed in a directory
6575 <tt>/usr/share/doc/<var>package</var>/examples</tt>. These
6576 files should not be referenced by any program--they're there
6577 for the benefit of the system administrator and users, as
6578 documentation only. Architecture-specific example files
6579 should be installed in a directory
6580 <tt>/usr/lib/<var>package</var>/examples</tt>, and files in
6581 <tt>/usr/share/doc/<var>package</var>/examples</tt> symlink
6582 to files in it. Or the latter directory may be a symlink to
6586 <sect id="instchangelog">
6587 <heading>Changelog files</heading>
6590 Packages that are not Debian-native must contain a copy of
6591 <tt>debian/changelog</tt> file from the Debian source tree
6592 in <tt>/usr/share/doc/<var>package</var></tt> as
6593 <tt>changelog.Debian.gz</tt>. If an upstream changelog is
6594 available, it should be accessible as
6595 <tt>/usr/share/doc/<var>package</var>/changelog.gz</tt> in
6596 plain text. If the upstream changelog is distributed in
6597 HTML, it should be made available in that form as
6598 <tt>/usr/share/doc/<var>package</var>/changelog.html.gz</tt>
6599 and the <tt>changelog.gz</tt> should be generated using, eg,
6600 <tt>lynx -dump -nolist</tt>. If the upstream changelog files
6601 do not already conform to this naming convention, then this
6602 may be achieved either by renaming the files, or adding a
6603 symbolic link, at the maintainer's discretion.
6606 Rationale: People should not have to look into two
6607 places for upstream changelogs merely because they are
6615 All these files should be installed compressed using <tt>gzip -9</tt>,
6616 as they will become large with time even if they start out
6621 If the package has only one changelog which is used both as
6622 the Debian changelog and the upstream one because there is
6623 no separate upstream maintainer then that changelog should
6624 usually be installed as
6625 <tt>/usr/share/doc/<var>package</var>/changelog.gz</tt>; if
6626 there is a separate upstream maintainer, but no upstream
6627 changelog, then the Debian changelog should still be called
6628 <tt>changelog.Debian.gz</tt>.</p>