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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>Philip Hands <email>phil@hands.com</email></p>
61 <p>Julian Gilbey <email>J.D.Gilbey@qmw.ac.uk</email></p>
64 <p>Manoj Srivastava <email>srivasta@debian.org</email></p>
72 Copyright ©1996,1997,1998 Ian Jackson
73 and Christian Schwarz.
76 This manual is free software; you may redistribute it and/or
77 modify it under the terms of the GNU General Public License
78 as published by the Free Software Foundation; either version
79 2, or (at your option) any later version.
83 This is distributed in the hope that it will be useful, but
84 <em>without any warranty</em>; without even the implied
85 warranty of merchantability or fitness for a particular
86 purpose. See the GNU General Public License for more
91 A copy of the GNU General Public License is available as
92 <tt>/usr/share/common-licences/GPL</tt> in the Debian GNU/Linux
93 distribution or on the World Wide Web at
94 <url id="http://www.gnu.org/copyleft/gpl.html"
95 name="The GNU Public Licence">. You can also obtain it by writing to the
96 Free Software Foundation, Inc., 59 Temple Place - Suite 330,
97 Boston, MA 02111-1307, USA.
105 <heading>About this manual</heading>
107 <heading>Scope</heading>
109 This manual describes the policy requirements for the Debian
110 GNU/Linux distribution. This includes the structure and
111 contents of the Debian archive, several design issues of the
112 operating system, as well as technical requirements that
113 each package must satisfy to be included in the
119 This manual also describes Debian policy as it relates to
120 creating Debian packages. It is not a tutorial on how to build
121 packages, nor is it exhaustive where it comes to describing
122 the behavior of the packaging system. Instead, this manual
123 attempts to define the interface to the package management
124 system that the developers have to be conversant with.
127 Informally, the criteria used for inclusion is that the
128 material meet one of the following requirements:
130 <tag>Standard interfaces</tag>
133 The material presented represents an interface to
134 the packaging system that is mandated for use, and
135 is used by, a significant number of packages, and
136 should not be changed without peer review. Package
137 maintainers can then rely on this interfaces not
138 changing, and the package management software
139 authors need to ensure compatibility with these
140 interface definitions. (control file and and
141 changelog file formats are one example)
144 <tag>Chosen Convention</tag>
147 If there are a number of technically viable choices
148 that can be made, but one needs to select one of
149 these options for inter-operability. The version
150 number format is one example.
154 Please note that these are not mutually exclusive;
155 selected conventions often become parts of standard
162 Please note that the footnotes present in this manual are
163 merely informative, and are not part of Debian policy itself.
168 In this manual, the words <em>must</em>, <em>should</em> and
169 <em>may</em>, and the adjectives <em>required</em>,
170 <em>recommended</em> and <em>optional</em>, are used to
171 distinguish the significance of the various guidelines in
172 this policy document. Packages that do not conform the the
173 guidelines denoted by <em>must</em> (or <em>required</em>)
174 will generally not be considered acceptable for the Debian
175 distribution. Non-conformance with guidelines denoted by
176 <em>should</em> (or <em>recommended</em>) will generally be
177 considered a bug, but will not necessarily render a package
178 unsuitable for distribution. Guidelines denoted by
179 <em>may</em> (or <em>optional</em>) are truly optional and
180 adherence is left to the maintainer's discretion.
183 These classifications are roughly equivalent to the bug
184 severities <em>important</em> (for <em>must</em> or
185 <em>required</em> directive violations), <em>normal</em>
186 (for <em>should</em> or <em>recommended</em> directive
187 violations) and <em>wishlist</em> (for <em>optional</em>
189 <p>Also see RFC 2119.</p>
193 Much of the information presented in this manual will be
194 useful even when building a package which is to be
195 distributed in some other way or is for local use.
199 <heading>New versions of this document</heading>
201 The current version of this document is always accessible from the
202 Debian FTP server <ftpsite>ftp.debian.org</ftpsite> at
203 <ftppath>/debian/doc/package-developer/debian-policy.html.tar.gz</ftppath>
204 or from the Debian WWW server at
205 <url id="http://www.debian.org/doc/debian-policy/"
206 name="The Debian Policy Manual">.</p>
209 In addition, this manual is distributed via the Debian package
210 <tt>debian-policy</tt>.
214 <heading>Feedback</heading>
217 As the Debian GNU/Linux system is continuously evolving this
218 manual is changed from time to time.
221 While the authors of this document tried hard not to include
222 any typos or other errors these still occur. If you discover
223 an error in this manual or if you want to tell us any
224 comments, suggestions, or critics please send an email to
225 the Debian Policy List,
226 <email>debian-policy@lists.debian.org</email>, or submit a
227 bug report against the <tt>debian-policy</tt> package.
232 <heading>The Debian Archive</heading>
234 The Debian GNU/Linux system is maintained and distributed as a
235 collection of <em>packages</em>. Since there are so many of them (over
236 5000) they are split into <em>sections</em> and <em>priorities</em> to
237 simplify handling of them.
240 The effort of the Debian project is to build a free operating
241 system, but not every package we want to make accessible is
242 <em>free</em> in our sense (see Debian Free Software
243 Guidelines, below), or may be imported/exported without
244 restrictions. Thus, the archive is split into the sections
245 <em>main</em>, <em>non-free</em>, <em>contrib</em>,
246 <em>non-US/main</em>, <em>non-US/non-free</em>, and
247 <em>non-US/contrib</em>.</p>
250 The <em>main</em> and the <em>non-US/main</em> sections form
251 the <em>Debian GNU/Linux distribution</em>.
255 Packages in the other sections are not considered as part of
256 the Debian distribution, though we support their use, and we
257 provide infrastructure for them (such as our bug-tracking
258 system and mailing lists). This Debian Policy Manual applies
259 to these packages as well.</p>
261 <sect id="pkgcopyright">
262 <heading>Package copyright and sections</heading>
264 The aims of this policy are:
266 <list compact="compact">
268 <p>We want to make as much software available as we
272 <p>We want to encourage everyone to write free software.</p>
275 <p> We want to make it easy for people to produce
276 CD-ROMs of our system without violating any licenses,
277 import/export restrictions, or any other laws.</p>
282 <heading>The Debian Free Software Guidelines</heading>
284 The Debian Free Software Guidelines (DFSG) is our
285 definition of `free' software.
287 <tag>Free Redistribution
291 The license of a Debian component may not restrict any
292 party from selling or giving away the software as a
293 component of an aggregate software distribution
294 containing programs from several different
295 sources. The license may not require a royalty or
296 other fee for such sale.
303 The program must include source code, and must allow
304 distribution in source code as well as compiled form.
311 The license must allow modifications and derived
312 works, and must allow them to be distributed under the
313 same terms as the license of the original software.
316 <tag>Integrity of The Author's Source Code
320 The license may restrict source-code from being
321 distributed in modified form <em>only</em> if the
322 license allows the distribution of ``patch files''
323 with the source code for the purpose of modifying the
324 program at build time. The license must explicitly
325 permit distribution of software built from modified
326 source code. The license may require derived works to
327 carry a different name or version number from the
328 original software. (This is a compromise. The Debian
329 group encourages all authors to not restrict any
330 files, source or binary, from being modified.)
333 <tag>No Discrimination Against Persons or Groups
337 The license must not discriminate against any person
341 <tag>No Discrimination Against Fields of Endeavor
345 The license must not restrict anyone from making use
346 of the program in a specific field of endeavor. For
347 example, it may not restrict the program from being
348 used in a business, or from being used for genetic
352 <tag>Distribution of License
356 The rights attached to the program must apply to all
357 to whom the program is redistributed without the need
358 for execution of an additional license by those
362 <tag>License Must Not Be Specific to Debian
366 The rights attached to the program must not depend on
367 the program's being part of a Debian system. If the
368 program is extracted from Debian and used or
369 distributed without Debian but otherwise within the
370 terms of the program's license, all parties to whom
371 the program is redistributed must have the same
372 rights as those that are granted in conjunction with
376 <tag>License Must Not Contaminate Other Software
380 The license must not place restrictions on other
381 software that is distributed along with the licensed
382 software. For example, the license must not insist
383 that all other programs distributed on the same medium
384 must be free software.
387 <tag>Example Licenses
391 The ``GPL,'' ``BSD,'' and ``Artistic'' licenses are
392 examples of licenses that we consider <em>free</em>.
399 <heading>The main section</heading>
401 Every package in "main" and "non-US/main" must comply with
402 the DFSG (Debian Free Software Guidelines).</p>
405 In addition, the packages in "main"
406 <list compact="compact">
409 must not require a package outside of "main" for
410 compilation or execution (thus, the package must not
411 declare a "Depends", "Recommends", or
412 "Build-Depends" relationship on a non-main package),
417 must not be so buggy that we refuse to support them,
422 must meet all policy requirements presented in this
429 Similarly, the packages in "non-US/main"
430 <list compact="compact">
433 must not require a package outside of "main" or
434 "non-US/main" for compilation or execution,
439 must not be so buggy that we refuse to support them,
444 must meet all policy requirements presented in this
452 <heading>The contrib section</heading>
454 Every package in "contrib" and "non-US/contrib" must
455 comply with the DFSG.
459 Examples of packages which would be included in "contrib"
460 or "non-US/contrib" are
461 <list compact="compact">
464 free packages which require "contrib", "non-free"
465 packages or packages which are not in our
466 archive at all for compilation or execution,
471 wrapper packages or other sorts of free accessories for
479 <heading>The non-free section and non-US/non-free </heading>
481 Packages must be placed in "non-free" or "non-US/non-free"
482 if they are not compliant with the DFSG or are encumbered
483 by patents or other legal issues that make their
484 distribution problematic.
488 <heading>The non-US sections</heading>
490 Some programs with cryptographic program code need to be stored
491 on the "non-US" server because of export restrictions of the
492 U.S. Such programs must be distributed in the appropriate
493 non-US section, either non-US/main, non-US/contrib or
494 non-US/non-free. </p>
496 This applies only to packages which contain cryptographic
497 code. A package containing a program with an interface to a
498 cryptographic program or a program that's dynamically linked
499 against a cryptographic library should not be distributed
500 via the non-us server if it is capable of running without the
501 cryptography library or program.
505 <heading>Further copyright considerations</heading>
507 Every package must be accompanied by a verbatim copy of its
508 copyright and distribution license in the file
509 /usr/share/doc/<package-name>/copyright (see
510 <ref id="copyrightfile"> for details).</p>
512 We reserve the right to restrict files from being included
513 anywhere in our archives if
514 <list compact="compact">
517 their use or distribution would break a law,
522 there is an ethical conflict in their distribution or
528 we would have to sign a license for them, or
533 their distribution would conflict with other project
541 Programs whose authors encourage the user to make donations
542 are fine for the main distribution, provided that the
543 authors do not claim that not donating is immoral,
544 unethical, illegal or something similar; otherwise they must
548 Packages whose copyright permission notices (or patent
549 problems) do not allow redistribution even of only binaries,
550 and where no special permission has been obtained, must not be
551 placed on the Debian FTP site and its mirrors at all.</p>
554 Note, that under international copyright law (this applies
555 in the United States, too) <em>no</em> distribution or
556 modification of a work is allowed without an explicit notice
557 saying so. Therefore a program without a copyright notice
558 <em>is</em> copyrighted and you may not do anything to it
559 without risking being sued! Likewise if a program has a
560 copyright notice but no statement saying what is permitted
561 then nothing is permitted.</p>
564 Many authors are unaware of the problems that restrictive
565 copyrights (or lack of copyright notices) can cause for the
566 users of their supposedly-free software. It is often
567 worthwhile contacting such authors diplomatically to ask
568 them to modify their license terms. However, this is a
569 politically difficult thing to do and you should ask for
570 advice on <tt>debian-legal</tt> first.</p>
573 When in doubt, send mail to
574 <email>debian-legal@lists.debian.org</email>. Be prepared
575 to provide us with the copyright statement. Software
576 covered by the GPL, public domain software and BSD-like
577 copyrights are safe; be wary of the phrases `commercial use
578 prohibited' and `distribution restricted'.</p>
581 <heading>Subsections</heading>
584 The packages in all the sections (<em>main</em>,
585 <em>contrib</em>, <em>non-US/main</em>, <em>non-free</em>,
586 <em>non-US/contrib</em>, and <em>non-US/non-free</em>) are
587 grouped further into <em>subsections</em> to simplify
591 The section for each package should be specified in the
592 package's <em>control record</em>. However, the maintainer of
593 the Debian archive may override this selection to assure the
594 consistency of the Debian distribution. </p>
597 Please check the current Debian distribution to see which
598 sections are available.</p>
601 <heading>Priorities</heading>
604 Each package should have a <em>priority</em> value,
605 which is included in the package's <em>control
606 record</em>. This information is used in the Debian package
607 management tool to separate high-priority packages from
608 less-important packages.</p>
611 The following <em>priority levels</em> are supported by the
612 Debian package management system, <prgn>dpkg</prgn>.
614 <tag><tt>required</tt></tag>
617 <tt>required</tt> packages are necessary for the
618 proper functioning of the system. You must not remove
619 these packages or your system may become totally
620 broken and you may not even be able to use
621 <prgn>dpkg</prgn> to put things back. Systems with
622 only the <tt>required</tt> packages are probably
623 unusable, but they do have enough functionality to
624 allow the sysadmin to boot and install more
627 <tag><tt>important</tt></tag>
630 Important programs, including those which one would
631 expect to find on any Unix-like system. If the
632 expectation is that an experienced Unix person who
633 found it missing would say `What the F*!@<+ is
634 going on, where is <prgn>foo</prgn>', it must be in
635 <tt>important</tt>. This is an important criterion
636 because we are trying to produce, amongst other
637 things, a free Unix. Other packages without which the
638 system will not run well or be usable must also be
639 here. This does <em>not</em> include Emacs, the X
640 Window System, TeX or any other large applications.
641 The <tt>important</tt> packages are just a bare
642 minimum of commonly-expected and necessary tools.</p>
644 <tag><tt>standard</tt></tag>
647 These packages provide a reasonably small but not too
648 limited character-mode system. This is what will
649 install by default if the user doesn't select anything
650 else. It doesn't include many large applications, but
651 it does include Emacs (this is more of a piece of
652 infrastructure than an application) and a reasonable
653 subset of TeX and LaTeX (if this is possible without
656 <tag><tt>optional</tt></tag>
659 (In a sense everything is optional that isn't
660 required, but that's not what is meant here.) This is
661 all the software that you might reasonably want to
662 install if you didn't know what it was or don't have
663 specialized requirements. This is a much larger system
664 and includes the X Window System, a full TeX distribution,
665 and many applications. Note that optional packages should
666 not conflict with each other.
669 <tag><tt>extra</tt></tag>
672 This contains all packages that conflict with others
673 with required, important, standard or optional
674 priorities, or are only likely to be useful if you
675 already know what they are or have specialised
682 Packages must not depend on packages with lower priority
683 values (excluding build-time dependencies). In order to
684 ensure this, the priorities of one or more packages must
690 <heading>Binary packages</heading>
693 The Debian GNU/Linux distribution is based on the Debian
694 package management system, called <prgn>dpkg</prgn>. Thus,
695 all packages in the Debian distribution must be provided
696 in the <tt>.deb</tt> file format.</p>
700 <heading>The package name</heading>
703 Every package must have a name that's unique within the Debian
707 Package names must only consist of lower case letters, digits (0-9),
708 plus (+) or minus (-) signs, and periods (.).</p>
711 The package name is part of the file name of the
712 <tt>.deb</tt> file and is included in the control field
718 <heading>The maintainer of a package</heading>
720 Every package must have a maintainer (the maintainer may
721 be one person or a group of people reachable from a common
722 email address, such as a mailing list). The maintainer is
723 responsible for ensuring that the package is placed in
724 the appropriate distribution
728 The maintainer must be specified in the
729 <tt>Maintainer</tt> control field with the correct name
730 and a working email address for the Debian maintainer of
731 the package. If one person maintains several packages
732 he/she should try to avoid having different forms of their
733 name and email address in different <tt>Maintainer</tt>
737 If the maintainer of a package quits from the Debian
738 project the Debian QA Group
739 <email>debian-qa@lists.debian.org</email> takes over the
740 maintainership of the package until someone else
741 volunteers for that task. These packages are called
742 <em>orphaned packages</em>.
748 <heading>The description of a package</heading>
751 Every Debian package must have an extended description
752 stored in the appropriate field of the control record.</p>
755 The description should be written so that it tells the user
756 what they need to know to decide whether to install the
757 package. This description should not just be copied from
758 the blurb for the program. Instructions for configuring
759 or using the package should not be included -- that is what
760 installation scripts, manual pages, Info files, etc. are
761 for. Copyright statements and other administrivia should
762 not be included -- that is what the copyright file is
768 <heading>Dependencies</heading>
771 Every package must specify the dependency information
772 about other packages that are required for the first to
776 For example, a dependency entry must be provided for any
777 shared libraries required by a dynamically-linked executable
778 binary in a package.</p>
781 Packages are not required to declare any dependencies they
782 have on other packages which are marked <tt>Essential</tt>
783 (see below), and should not do so unless they depend on a
784 particular version of that package.</p>
787 Sometimes, a package requires another package to be installed
788 <em>and</em> configured before it can be installed. In this
789 case, you must specify a <tt>Pre-Depends</tt> entry for
793 You should not specify a <tt>Pre-Depends</tt> entry for a
794 package before this has been discussed on the
795 <tt>debian-devel</tt> mailing list and a consensus about
796 doing that has been reached.</p></sect1>
800 <heading>Virtual packages</heading>
803 Sometimes, there are several packages doing more-or-less
804 the same job. In this case, it's useful to define a
805 <em>virtual package</em> whose name describes the function
806 the packages have. (The virtual packages just exist
807 logically, not physically--that's why they are called
808 <em>virtual</em>.) The packages with this particular
809 function will then <em>provide</em> the virtual
810 package. Thus, any other package requiring that function
811 can simply depend on the virtual package without having to
812 specify all possible packages individually.</p>
815 All packages should use virtual package names where
816 appropriate, and arrange to create new ones if necessary.
817 They should not use virtual package names (except privately,
818 amongst a cooperating group of packages) unless they have
819 been agreed upon and appear in the list of virtual package
823 The latest version of the authoritative list of virtual
824 package names can be found on
825 <ftpsite>ftp.debian.org</ftpsite> in
826 <ftppath>/debian/doc/package-developer/virtual-package-names-list.text</ftppath>
827 or your local mirror. In addition, it is included in the
828 <tt>debian-policy</tt> package. The procedure for updating
829 the list is described at the top of the file.</p></sect1>
833 <heading>Base packages</heading>
836 The packages included in the <tt>base</tt> section have a
837 special function. They form a minimum subset of the Debian
838 GNU/Linux system that is installed before everything else
839 on a new system. Thus, only very few packages are allowed
840 to go into the <tt>base</tt> section to keep the required
841 disk usage very small.</p>
844 Most of these packages will have the priority value
845 <tt>required</tt> or at least <tt>important</tt>, and many
846 of them will be tagged <tt>essential</tt> (see below).</p>
849 You must not place any packages into the <tt>base</tt>
850 section before this has been discussed on the
851 <tt>debian-devel</tt> mailing list and a consensus about
852 doing that has been reached.</p></sect1>
856 <heading>Essential packages</heading>
859 Some packages are tagged <tt>essential</tt>. (They have
860 <tt>Essential: yes</tt> in their package control record.)
861 This flag is used for packages that are <em>essential</em>
865 Since these packages can not easily be removed (you'll
866 have to specify an extra <em>force option</em> to
867 <prgn>dpkg</prgn>) this flag must not be used unless
868 absolutely necessary. A shared library package must not
869 be tagged <tt>essential</tt>--the dependencies will
870 prevent its premature removal, and we need to be able to
871 remove it when it has been superseded.
875 Since dpkg will not prevent upgrading of other packages
876 while an <tt>essential</tt> package is in an unconfigured
877 state, all <tt>essential</tt> packages must supply all
878 their core functionality even when unconfigured. If the
879 package cannot satisfy this requirement it must not be
880 tagged as essential, and any packages depending on this
881 package must instead have explicit dependency fields as
886 You must not tag any packages <tt>essential</tt> before
887 this has been discussed on the <tt>debian-devel</tt>
888 mailing and a consensus about doing that has been
893 <heading>Maintainer scripts</heading>
896 The package installation scripts should avoid producing
897 output which it is unnecessary for the user to see and
898 should rely on <prgn>dpkg</prgn> to stave off boredom on
899 the part of a user installing many packages. This means,
900 amongst other things, using the <tt>--quiet</tt> option on
901 <prgn>install-info</prgn>.</p>
904 Errors which occur during the execution of an installation
905 script must be checked and the installation must not
906 continue after an error.
910 Note, that <ref id="scripts">, in general applies to package
911 maintainer scripts, too.
915 You should not use <tt>dpkg-divert</tt>' on a file
916 belonging to another package without consulting the
917 maintainer of that package first.
920 All packages which supply an instance of a common command
921 name (or, in general, filename) should generally use
922 <prgn>update-alternatives</prgn>, so that they may be
923 installed together. If <prgn>update-alternatives</prgn>
924 is not used, then each package must use
925 <var>Conflicts</var> to ensure that other packages are
926 de-installed. (In this case, it may be appropriate to
927 specify a conflict against earlier versions of something
928 that previously did not use
929 <prgn>update-alternatives</prgn> - this is an exception to
930 the usual rule that this not allowed).
935 <heading>Prompting in maintainer scripts</heading>
937 Package maintainer scripts may prompt the user if
938 necessary. Prompting may be accomplished by hand, or by
939 communicating with a program, such as
940 <prgn>debconf</prgn>, which conforms to the Debian
941 Configuration management specification, version 2 or
942 higher. (Included in the
943 <file>debconf_specification</file> files in the
944 <package>debian-policy</package> package.)
945 You may also find this file on the FTP site
946 <ftpsite>ftp.debian.org</ftpsite> in
947 <ftppath>/debian/doc/package-developer/debconf_specification.txt.gz</ftppath>
948 or your local mirror.
951 2.5% of Debian packages
952 [<url id="http://kitenet.net/programs/debconf/stats/">]
953 use debconf to prompt the user at install time, and
954 this number is growing daily. The benefits of using
955 debconf are briefly explained at
956 <url id="http://kitenet.net/doc/debconf-doc/introduction.html">;
957 they include preconfiguration, (mostly)
958 noninteractive installation, elimination of
959 redundant prompting, consistency of user interface,
963 With this increasing number of packages using
964 debconf, plus the existance of a nascent second
965 implementation of the Debian configuration
966 management system (<package>cdebconf</package>), and
967 the stabalization of the protocol these things use,
968 the time has finally come to reflect the use of
969 these things in policy.
975 Packages which use the Debian Configuration management
976 specification may contain an additional
977 <file>config</file> script and a <file>templates</file>
978 file in their control archive. The <prgn>config</prgn>
979 script can be run before the preinst, and before the
980 package is unpacked or any of its dependancies or
981 pre-dependancies are satisfied, so it must work using
982 only the tools present in the <em>Essential</em>
986 Debconf or another tool that implements the Debian
987 Configuration management specification will also be
988 installed, and any versioned dependancies on it will
989 be satisfied before preconfiguration begins.
995 Packages should try to minimize the amount of prompting
996 they need to do, and they should ensure that the user
997 will only ever be asked each question once. This means
998 that packages should try to use appropriate shared
999 configuration files (such as <tt>/etc/papersize</tt> and
1000 <tt>/etc/news/server</tt>), and shared debconf variables
1001 rather than each prompting for their own list of
1002 required pieces of information.
1006 It also means that an upgrade should not ask the same
1007 questions again, unless the user has used <tt>dpkg
1008 --purge</tt> to remove the package's configuration. The
1009 answers to configuration questions should be stored in an
1010 appropriate place in <tt>/etc</tt> so that the user can
1011 modify them, and how this has been done should be
1015 If a package has a vitally important piece of
1016 information to pass to the user (such as "don't run me
1017 as I am, you must edit the following configuration files
1018 first or you risk your system emitting badly-formatted
1019 messages"), it should display this in the
1020 <prgn>config</prgn> or <prgn>postinst</prgn> script and
1021 prompt the user to hit return to acknowledge the
1022 message. Copyright messages do not count as vitally
1023 important (they belong in
1024 <tt>/usr/share/doc/<var>package</var>/copyright</tt>);
1025 neither do instructions on how to use a program (these
1026 should be in on line documentation, where all the users
1030 Any necessary prompting should almost always be confined
1031 to the <prgn>config</prgn> or <prgn>postinst</prgn>
1032 script. If it is done in the <prgn>postinst</prgn>, it
1033 should be protected with a conditional so that unnecessary
1034 prompting doesn't happen if a package's installation fails
1035 and the <prgn>postinst</prgn> is called with
1036 <tt>abort-upgrade</tt>, <tt>abort-remove</tt> or
1037 <tt>abort-deconfigure</tt>.</p>
1042 <heading>Source packages</heading>
1045 <heading>Standards conformance</heading>
1048 You should specify the most recent version of the
1049 packaging standards with which your package complies in
1050 the source package's <tt>Standards-Version</tt> field.</p>
1053 This value will be used to file bug reports automatically
1054 if your package becomes too much out of date.</p>
1057 The value corresponds to a version of the Debian manuals,
1058 as can be found on the title page or page headers and
1059 footers (depending on the format).</p>
1062 The version number has four components--major and minor
1063 number and major and minor patch level. When the
1064 standards change in a way that requires every package to
1065 change the major number will be changed. Significant
1066 changes that will require work in many packages will be
1067 signaled by a change to the minor number. The major patch
1068 level will be changed for any change to the meaning of the
1069 standards, however small; the minor patch level will be
1070 changed when only cosmetic, typographical or other edits
1071 which do not change the meaning are made, or changes which
1072 do not affect the contents of packages.</p>
1075 For package maintainers, only the first 3 digits of the
1076 manual version are significant in representing the
1077 <em>Standards-Version</em>, and either these 3 digits or
1078 the complete 4 digits may be specified.
1081 In the past, people specified 4 digits in the
1082 Standards-Version field, like `2.3.0.0'. Since any
1083 `patch-level changes' don't introduce new policy, it
1084 was thought it would be better to relax policy and
1085 only require that the first 3 digits are specified. (4
1086 digits may still be used if someone wants to do so.)
1092 You should regularly, and especially if your package has
1093 become out of date, check for the newest Policy Manual
1094 available and update your package, if necessary. When your
1095 package complies with the new standards you should update the
1096 <tt>Standards-Version</tt> source package field and
1097 release it.</p></sect1>
1101 <heading>Package relationships</heading>
1104 Source packages should specify which binary packages they
1105 require to be installed or not to be installed in order to
1106 build correctly. For example, if building a package
1107 requires a certain compiler, then the compiler should be
1108 specified as a build-time dependency.
1112 It is not necessary to explicitly specify build-time
1113 relationships on a minimal set of packages that are always
1114 needed to compile, link and put in a Debian package a
1115 standard "Hello World!" program written in C or C++. The
1116 required packages are called <em>build-essential</em>, and
1117 an informational list can be found in
1118 <tt>/usr/share/doc/build-essential/list</tt> (which is
1119 contained in the <tt>build-essential</tt>
1125 <p>This allows maintaining the list separately
1126 from the policy documents (the list does not
1127 need the kind of control that the policy
1133 Having a separate package allows one to nistall
1134 the build essential packages on a machine, as
1135 well as allowing other packages (think task
1136 packages) to bring in the build-essential
1137 packages using the depends relation
1142 The separate package allows bug reports against
1143 the package to be categorized separately from
1144 the policy management process that uses the BTS
1154 When specifying the set of build-time dependencies, one
1155 should list only those packages explicitly required by the
1156 build. It is not necessary to list packages which are
1157 required merely because some other package in the list of
1158 build-time dependencies depends on them. The reason is
1159 that dependencies change, and you should list only those
1160 <em>you</em> need. What others need is their business.
1164 If build-time dependencies are specified, it must be
1165 possible to build the package and produce working binaries
1166 on a system with the build-essential packages installed
1167 and satisfying the build-time relationships (including any
1168 implied relationships). This
1169 means in particular that version clauses should be used
1170 rigorously in build-time relationships so that one cannot
1171 produce bad or inconsistently configured packages when the
1172 relationships are properly satisfied.
1176 <heading>Changes to the upstream sources</heading>
1179 If changes to the source code are made that are generally
1180 applicable, they should be sent to the upstream authors
1181 in whatever form they prefer so as to be included in the
1182 upstream version of the package.</p>
1185 If you need to configure the package differently for
1186 Debian or for Linux, and the upstream source doesn't
1187 provide a way to configure it the way you need to, you
1188 should add such configuration facilities (for example, a new
1189 <prgn>autoconf</prgn> test or <tt>#define</tt>) and send
1190 the patch to the upstream authors, with the default set to
1191 the way they originally had it. You can then easily
1192 override the default in your <tt>debian/rules</tt> or
1193 wherever is appropriate.</p>
1196 You should make sure that the <prgn>configure</prgn> utility
1197 detects the correct architecture specification string
1198 (refer to <ref id="arch-spec"> for details).</p>
1201 If you need to edit a <prgn>Makefile</prgn> where
1202 GNU-style <prgn>configure</prgn> scripts are used, you
1203 should edit the <tt>.in</tt> files rather than editing the
1204 <prgn>Makefile</prgn> directly. This allows the user to
1205 reconfigure the package if necessary. You should
1206 <em>not</em> configure the package and edit the generated
1207 <prgn>Makefile</prgn>! This makes it impossible for
1208 someone else to later reconfigure the package.</p></sect1>
1212 <heading>Documenting your changes</heading>
1215 You should document your changes and updates to the source
1216 package properly in the <tt>debian/changelog</tt> file. (Note
1217 that mistakes in changelogs are usually best rectified by
1218 making a new changelog entry rather than "rewriting history"
1219 by editing old changelog entries)</p>
1222 In non-experimental packages you must only use a format for
1223 <tt>debian/changelog</tt> which is supported by the most
1224 recent released version of <prgn>dpkg</prgn>. If your
1225 format is not supported and there is general support for
1226 it you should contact the <prgn>dpkg</prgn> maintainer to
1227 have the parser script for your format included in the
1228 <prgn>dpkg</prgn> package. (You will need to agree that
1229 the parser and its manpage may be distributed under the
1230 GNU GPL, just as the rest of <prgn>dpkg</prgn>
1235 <heading>Error trapping in makefiles</heading>
1238 When <prgn>make</prgn> invokes a command in a makefile
1239 (including your package's upstream makefiles and the
1240 <tt>debian/rules</tt>) it does so using <tt>sh</tt>. This
1241 means that <tt>sh</tt>'s usual bad error handling
1242 properties apply: if you include a miniature script as one
1243 of the commands in your makefile you'll find that if you
1244 don't do anything about it then errors are not detected
1245 and <prgn>make</prgn> will blithely continue after
1249 Every time you put more than one shell command (this
1250 includes using a loop) in a makefile command you
1251 must make sure that errors are trapped. For
1252 simple compound commands, such as changing directory and
1253 then running a program, using <tt>&&</tt> rather
1254 than semicolon as a command separator is sufficient. For
1255 more complex commands including most loops and
1256 conditionals you should include a separate <tt>set -e</tt>
1257 command at the start of every makefile command that's
1258 actually one of these miniature shell scripts.</p></sect1>
1262 <heading>Obsolete constructs and libraries</heading>
1265 The include file <prgn><varargs.h></prgn> is
1266 provided to support end-users compiling very old software;
1267 the library <tt>libtermcap</tt> is provided to support the
1268 execution of software which has been linked against it
1269 (either old programs or those such as Netscape which are
1270 only available in binary form).</p>
1273 Debian packages should be ported to include
1274 <prgn><stdarg.h></prgn> and <tt>ncurses</tt> when
1280 <chapt id="controlfields"><heading>Control files and their fields</heading>
1283 Many of the tools in the package management suite manipulate
1284 data in a common format, known as control files. Binary and
1285 source packages have control data as do the <tt>.changes</tt>
1286 files which control the installation of uploaded files, and
1287 <prgn>dpkg</prgn>'s internal databases are in a similar
1291 <sect><heading>Syntax of control files</heading>
1294 A file consists of one or more paragraphs of fields. The
1295 paragraphs are separated by blank lines. Some control files
1296 only allow one paragraph; others allow several, in which
1297 case each paragraph often refers to a different package.
1301 Each paragraph is a series of fields and values; each field
1302 consists of a name, followed by a colon and the value. It
1303 ends at the end of the line. Horizontal whitespace (spaces
1304 and tabs) may occur immediately before or after the value
1305 and is ignored there; it is conventional to put a single
1306 space after the colon.
1310 Some fields' values may span several lines; in this case
1311 each continuation line <em>must</em> start with a space or
1312 tab. Any trailing spaces or tabs at the end of individual
1313 lines of a field value are ignored.
1317 Except where otherwise stated only a single line of data is
1318 allowed and whitespace is not significant in a field body.
1319 Whitespace may never appear inside names (of packages,
1320 architectures, files or anything else), version numbers or
1321 in between the characters of multi-character version
1326 Field names are not case-sensitive, but it is usual to
1327 capitalize the field names using mixed case as shown below.
1331 Blank lines, or lines consisting only of spaces and tabs,
1332 are not allowed within field values or between fields - that
1333 would mean a new paragraph.
1337 It is important to note that there are several fields which
1338 are optional as far as <prgn>dpkg</prgn> and the related
1339 tools are concerned, but which must appear in every Debian
1340 package, or whose omission may cause problems. When writing
1341 the control files for Debian packages you <em>must</em> read
1342 the Debian policy manual in conjunction with the details
1343 below and the list of fields for the particular file.</p>
1346 <sect><heading>List of fields</heading>
1348 This list here is not supposed to be exhaustive. Typically
1349 only fields for whom policy exists are mentioned here.
1351 <sect1 id="f-Package"><heading><tt>Package</tt>
1355 The name of the binary package. Package names consist of
1356 the alphanumerics and <tt>+</tt> <tt>-</tt> <tt>.</tt>
1357 (plus, minus and full stop).
1361 They must be at least two characters long and must start
1362 with an alphanumeric character. The use lowercase package
1363 names is strongly recommended unless the package you're
1364 building (or referring to, in other fields) is already
1365 using uppercase.</p>
1368 <sect1 id="f-Version"><heading><tt>Version</tt>
1372 This lists the source or binary package's version number -
1373 see <ref id="versions">.
1379 id="f-Standards-Version"><heading><tt>Standards-Version</tt>
1383 The most recent version of the standards (the packaging
1384 and policy manuals and associated texts) with which the
1385 package complies. This is updated manually when editing
1386 the source package to conform to newer standards; it can
1387 sometimes be used to tell when a package needs attention.
1391 Its format is the same as that of a version number except
1392 that no epoch or Debian revision is allowed - see <ref
1397 <sect1 id="f-Distribution"><heading><tt>Distribution</tt>
1401 In a <tt>.changes</tt> file or parsed changelog output
1402 this contains the (space-separated) name(s) of the
1403 distribution(s) where this version of the package should
1404 be or was installed. Distribution names follow the rules
1405 for package names. (See <ref id="f-Package">).
1410 Current distribution values are:
1412 <tag><em>stable</em></tag>
1415 This is the current `released' version of Debian
1417 distribution is <em>stable</em> only major bug fixes
1418 are allowed. When changes are made to this
1419 distribution, the release number is increased
1420 (for example: 1.2r1 becomes 1.2r2 then 1.2r3, etc).
1424 <tag><em>unstable</em></tag>
1427 This distribution value refers to the
1428 <em>developmental</em> part of the Debian
1429 distribution tree. New packages, new upstream
1430 versions of packages and bug fixes go into the
1431 <em>unstable</em> directory tree. Download from
1432 this distribution at your own risk.
1436 <tag><em>frozen</em></tag>
1439 From time to time, the <em>unstable</em>
1440 distribution enters a state of `code-freeze' in
1441 anticipation of release as a <em>stable</em>
1442 version. During this period of testing only
1443 fixes for existing or newly-discovered bugs will
1448 <tag><em>experimental</em></tag>
1451 The packages with this distribution value are deemed
1452 by their maintainers to be high risk. Oftentimes they
1453 represent early beta or developmental packages from
1454 various sources that the maintainers want people to
1455 try, but are not ready to be a part of the other parts
1456 of the Debian distribution tree. Download at your own
1461 There are several sections in each
1462 distribution. Currently, these sections are:
1465 <tag><em>contrib</em></tag>
1468 The packages in this section do not meet the
1469 criteria for inclusion in the main Debian
1470 distribution as defined by the Policy Manual,
1471 but are otherwise free, as defined by the Debian
1472 free software guidelines.</p>
1475 <tag><em>non-free</em></tag>
1478 Packages in <em>non-free</em> do not meet the
1479 criteria of free software, as defined by the
1480 Debian free software guidelines. Again, use your
1481 best judgment in downloading from this
1485 </taglist> You should list <em>all</em> distributions that
1486 the package should be installed into. Except in unusual
1487 circumstances, installations to <em>stable</em> should also
1488 go into <em>frozen</em> (if it exists) and
1489 <em>unstable</em>. Likewise, installations into
1490 <em>frozen</em> should also go into <em>unstable</em>.
1499 <chapt id="versions"><heading>Version numbering </heading>
1502 Every package has a version number, in its <tt>Version</tt>
1507 The package management system imposes an ordering on version
1508 numbers, so that it can tell whether packages are being up- or
1509 downgraded and so that package system front end applications
1510 can tell whether a package it finds available is newer than
1511 the one installed on the system. The version number format
1512 has the most significant parts (as far as comparison is
1513 concerned) at the beginning.
1517 The version number format is:
1518 &lsqb<var>epoch</var><tt>:</tt>]<var>upstream-version</var>[<tt>-/<var>debian-revision</var>].</tt>
1522 The three components here are:
1524 <tag><var>epoch</var></tag>
1528 This is a single (generally small) unsigned integer. It
1529 may be omitted, in which case zero is assumed. If it is
1530 omitted then the <var>upstream-version</var> may not
1535 It is provided to allow mistakes in the version numbers
1536 of older versions of a package, and also a package's
1537 previous version numbering schemes, to be left behind.
1542 <tag><var>upstream-version</var></tag>
1546 This is the main part of the version. It is usually
1547 version number of the original (`upstream') package of
1548 which the <tt>.deb</tt> file has been made, if this is
1549 applicable. Usually this will be in the same format as
1550 that specified by the upstream author(s); however, it
1551 may need to be reformatted to fit into the package
1552 management system's format and comparison scheme.
1556 The comparison behavior of the package management system
1557 with respect to the <var>upstream-version</var> is
1558 described below. The <var>upstream-version</var>
1559 portion of the version number is mandatory.
1563 The <var>upstream-version</var> may contain only
1564 alphanumerics and the characters <tt>.</tt> <tt>+</tt>
1565 <tt>-</tt> <tt>:</tt> (full stop, plus, hyphen, colon)
1566 and should start with a digit. If there is no
1567 <var>debian-revision</var> then hyphens are not allowed;
1568 if there is no <var>epoch</var> then colons are not
1572 <tag><var>debian-revision</var></tag>
1576 This part of the version represents the version of the
1577 modifications that were made to the package to make it a
1578 Debian binary package. It is in the same format as the
1579 <var>upstream-version</var> and is compared in the same
1584 It is optional; if it isn't present then the
1585 <var>upstream-version</var> may not contain a hyphen.
1586 This format represents the case where a piece of
1587 software was written specifically to be turned into a
1588 Debian binary package, and so there is only one
1589 `debianization' of it and therefore no revision
1590 indication is required.
1594 It is conventional to restart the
1595 <var>debian-revision</var> at <tt>1</tt> each time the
1596 <var>upstream-version</var> is increased.
1600 The package management system will break the
1601 <var>upstream-version</var> and
1602 <var>debian-revision</var> apart at the last hyphen in
1603 the string. The absence of a <var>debian-revision</var>
1604 compares earlier than the presence of one (but note that
1605 the <var>debian-revision</var> is the least significant
1606 part of the version number).
1610 The <var>debian-revision</var> may contain only
1611 alphanumerics and the characters <tt>+</tt> and
1612 <tt>.</tt> (plus and full stop).
1616 The <var>upstream-version</var> and <var>debian-revision</var>
1617 parts are compared by the package management system using the
1622 The strings are compared from left to right.
1626 First the initial part of each string consisting entirely of
1627 non-digit characters is determined. These two parts (one of
1628 which may be empty) are compared lexically. If a difference
1629 is found it is returned. The lexical comparison is a
1630 comparison of ASCII values modified so that all the letters
1631 sort earlier than all the non-letters.
1635 Then the initial part of the remainder of each string which
1636 consists entirely of digit characters is determined. The
1637 numerical values of these two parts are compared, and any
1638 difference found is returned as the result of the comparison.
1639 For these purposes an empty string (which can only occur at
1640 the end of one or both version strings being compared) counts
1645 These two steps are repeated (chopping initial non-digit
1646 strings and initial digit strings off from the start) until a
1647 difference is found or both strings are exhausted.
1651 Note that the purpose of epochs is to allow us to leave behind
1652 mistakes in version numbering, and to cope with situations
1653 where the version numbering changes. It is <em>not</em> there
1654 to cope with version numbers containing strings of letters
1655 which the package management system cannot interpret (such as
1656 <tt>ALPHA</tt> or <tt>pre-</tt>), or with silly orderings (the
1657 author of this manual has heard of a package whose versions
1658 went <tt>1.1</tt>, <tt>1.2</tt>, <tt>1.3</tt>, <tt>1</tt>,
1659 <tt>2.1</tt>, <tt>2.2</tt>, <tt>2</tt> and so forth).
1663 If an upstream package has problematic version numbers they
1664 should be converted to a sane form for use in the
1665 <tt>Version</tt> field.
1669 <heading>Version numbers based on dates</heading>
1671 In general, Debian packages should use the same version
1672 numbers as the upstream sources.</p>
1675 However, in some cases where the upstream version number is
1676 based on a date (e.g., a development `snapshot' release) the
1677 package management system cannot handle these version
1678 numbers without epochs. For example, dpkg will consider
1679 `96May01' to be greater than `96Dec24'.</p>
1682 To prevent having to use epochs for every new upstream
1683 version, the version number should be changed to the
1684 following format in such cases: `19960501', `19961224'. It
1685 is up to the maintainer whether he/she wants to bother the
1686 upstream maintainer to change the version numbers upstream,
1690 Note, that other version formats based on dates which are
1691 parsed correctly by the package management system should
1692 <em>not</em> be changed.</p>
1695 Native Debian packages (i.e., packages which have been
1696 written especially for Debian) whose version numbers include
1697 dates should always use the `YYYYMMDD' format.</p>
1701 <chapt id="miscellaneous"><heading>Packaging Considerations</heading>
1703 <sect id="timestamps"><heading>Time Stamps</heading>
1705 Maintainers are encouraged to preserve the modification
1706 times of the upstream source files in a package, as far as
1707 is reasonably possible. Even though this is optional, this
1708 is still a good idea.
1711 The rationale is that there is some information conveyed
1712 by knowing the age of the file, for example, you could
1713 recognize that some documentation is very old by looking
1714 at the modification time, so it would be nice if the
1715 modification time of the upstream source would be
1722 <sect id="debianrules"><heading><tt>debian/rules</tt> - the
1723 main building script </heading>
1726 This file must be an executable makefile, and contains the
1727 package-specific recipes for compiling the package and
1728 building binary package(s) out of the source.
1732 It must start with the line <tt>#!/usr/bin/make -f</tt>,
1733 so that it can be invoked by saying its name rather than
1734 invoking <prgn>make</prgn> explicitly.
1738 Since an interactive <tt>debian/rules</tt> script makes it
1739 impossible to auto-compile that package and also makes it
1740 hard for other people to reproduce the same binary
1741 package, all <strong>required targets</strong> MUST be
1742 non-interactive. At a minimum, required targets are the
1743 ones called by <prgn>dpkg-buildpackage</prgn>, namely,
1744 <em>clean</em>, <em>binary</em>, <em>binary-arch</em>, and
1745 <em>build</em>. It also follows that any target that these
1746 targets depend on must also be non-interactive.
1750 The targets which must be present are:
1752 <tag><tt>build</tt></tag>
1755 This should perform all non-interactive
1756 configuration and compilation of the package. If a
1757 package has an interactive pre-build configuration
1758 routine, the Debianised source package should be
1759 built after this has taken place, so that it can be
1760 built without rerunning the configuration.
1764 For some packages, notably ones where the same
1765 source tree is compiled in different ways to produce
1766 two binary packages, the <prgn>build</prgn> target
1767 does not make much sense. For these packages it is
1768 good enough to provide two (or more) targets
1769 (<tt>build-a</tt> and <tt>build-b</tt> or whatever)
1770 for each of the ways of building the package, and a
1771 <prgn>build</prgn> target that does nothing. The
1772 <prgn>binary</prgn> target will have to build the
1773 package in each of the possible ways and make the
1774 binary package out of each.
1778 The <prgn>build</prgn> target must not do anything
1779 that might require root privilege.
1783 The <prgn>build</prgn> target may need to run
1784 <prgn>clean</prgn> first - see below.
1788 When a package has a configuration routine that
1789 takes a long time, or when the makefiles are poorly
1790 designed, or when <prgn>build</prgn> needs to run
1791 <prgn>clean</prgn> first, it is a good idea to
1792 <tt>touch build</tt> when the build process is
1793 complete. This will ensure that if <tt>debian/rules
1794 build</tt> is run again it will not rebuild the
1799 <tag><tt>binary</tt>, <tt>binary-arch</tt>,
1800 <tt>binary-indep</tt>
1804 The <prgn>binary</prgn> target must be all that is
1805 necessary for the user to build the binary
1806 package. All these targets are required to be
1807 non-interactive. It is split into two parts:
1808 <prgn>binary-arch</prgn> builds the packages' output
1809 files which are specific to a particular
1810 architecture, and <prgn>binary-indep</prgn> builds
1811 those which are not.
1815 <prgn>binary</prgn> may be (and commonly is) a target
1816 with no commands which simply depends on
1817 <prgn>binary-arch</prgn> and
1818 <prgn>binary-indep</prgn>.
1822 Both <prgn>binary-*</prgn> targets should depend on
1823 the <prgn>build</prgn> target, above, so that the
1824 package is built if it has not been already. It
1825 should then create the relevant binary package(s),
1826 using <prgn>dpkg-gencontrol</prgn> to make their
1827 control files and <prgn>dpkg-deb</prgn> to build
1828 them and place them in the parent of the top level
1833 If one of the <prgn>binary-*</prgn> targets has
1834 nothing to do (this will be always be the case if
1835 the source generates only a single binary package,
1836 whether architecture-dependent or not) it
1837 <em>must</em> still exist, and must always
1842 The <prgn>binary</prgn> targets must be invoked as
1847 <tag><tt>clean</tt></tag>
1851 This must undo any effects that the
1852 <prgn>build</prgn> and <prgn>binary</prgn> targets
1853 may have had, except that it should leave alone any
1854 output files created in the parent directory by a
1855 run of <prgn>binary</prgn>. This target must be
1860 If a <prgn>build</prgn> file is touched at the end
1861 of the <prgn>build</prgn> target, as suggested
1862 above, it should be removed as the first thing that
1863 <prgn>clean</prgn> does, so that running
1864 <prgn>build</prgn> again after an interrupted
1865 <prgn>clean</prgn> doesn't think that everything is
1870 The <prgn>clean</prgn> target may need to be
1871 invoked as root if <prgn>binary</prgn> has been
1872 invoked since the last <prgn>clean</prgn>, or if
1873 <prgn>build</prgn> has been invoked as root (since
1874 <prgn>build</prgn> may create directories, for
1879 <tag><tt>get-orig-source</tt> (optional)</tag>
1883 This target fetches the most recent version of the
1884 original source package from a canonical archive site
1885 (via FTP or WWW, for example), does any necessary
1886 rearrangement to turn it into the original source
1887 tar file format described below, and leaves it in the
1892 This target may be invoked in any directory, and
1893 should take care to clean up any temporary files it
1898 This target is optional, but providing it if
1899 possible is a good idea.
1905 The <prgn>build</prgn>, <prgn>binary</prgn> and
1906 <prgn>clean</prgn> targets must be invoked with a current
1907 directory of the package's top-level directory.
1912 Additional targets may exist in <tt>debian/rules</tt>,
1913 either as published or undocumented interfaces or for the
1914 package's internal use.
1918 The architecture we build on and build for is determined by
1919 make variables via dpkg-architecture. You can get the Debian
1920 architecture and the GNU style architecture specification
1921 string for the build machine as well as the host
1922 machine. Here is a list of supported make variables:
1923 <list compact="compact">
1925 <p><tt>DEB_*_ARCH</tt> (the Debian architecture)</p>
1928 <p><tt>DEB_*_GNU_TYPE</tt> (the GNU style architecture
1929 specification string)</p>
1932 <p><tt>DEB_*_GNU_CPU</tt> (the CPU part of DEB_*_GNU_TYPE)</p>
1935 <p><tt>DEB_*_GNU_SYSTEM</tt> (the System part of
1941 where <tt>*</tt> is either <tt>BUILD</tt> for specification of
1942 the build machine or <tt>HOST</tt> for specification of the machine
1947 Backward compatibility can be provided in the rules file
1948 by setting the needed variables to suitable default
1949 values, please refer to the documentation of
1950 dpkg-architecture for details.
1954 It is important to understand that the <tt>DEB_*_ARCH</tt>
1955 string does only determine which Debian architecture we
1956 build on resp. for. It should not be used to get the CPU
1957 or System information, the GNU style variables should be
1962 <sect id="dpkgchangelog"><heading><tt>debian/changelog</tt>
1966 This file records the changes to the Debian-specific parts of the
1970 Though there is nothing stopping an author who is also
1971 the Debian maintainer from using it for all their
1972 changes, it will have to be renamed if the Debian and
1973 upstream maintainers become different
1980 It has a special format which allows the package building
1981 tools to discover which version of the package is being
1982 built and find out other release-specific information.
1986 That format is a series of entries like this:
1988 <var>package</var> (<var>version</var>) <var>distribution(s)</var>; urgency=<var>urgency</var>
1990 * <var>change details</var>
1991 <var>more change details</var>
1992 * <var>even more change details</var>
1994 -- <var>maintainer name and email address</var> <var>date</var>
1999 <var>package</var> and <var>version</var> are the source
2000 package name and version number.
2004 <var>distribution(s)</var> lists the distributions where
2005 this version should be installed when it is uploaded - it
2006 is copied to the <tt>Distribution</tt> field in the
2007 <tt>.changes</tt> file. See <ref id="f-Distribution">.
2011 <var>urgency</var> is the value for the <tt>Urgency</tt>
2012 field in the <tt>.changes</tt> file for the upload. It is
2013 not possible to specify an urgency containing commas; commas
2014 are used to separate
2015 <tt><var>keyword</var>=<var>value</var></tt> settings in the
2016 <prgn>dpkg</prgn> changelog format (though there is
2017 currently only one useful <var>keyword</var>,
2022 The change details may in fact be any series of lines
2023 starting with at least two spaces, but conventionally each
2024 change starts with an asterisk and a separating space and
2025 continuation lines are indented so as to bring them in
2026 line with the start of the text above. Blank lines may be
2027 used here to separate groups of changes, if desired.
2031 The maintainer name and email address need <em>not</em>
2032 necessarily be those of the usual package maintainer.
2033 They should be the details of the person doing
2034 <em>this</em> version. The information here will be
2035 copied to the <tt>.changes</tt> file, and then later used
2036 to send an acknowledgement when the upload has been
2041 The <var>date</var> should be in RFC822 format
2044 This is generated by the <prgn>822-date</prgn>
2047 </footnote>; it should include the time zone specified
2048 numerically, with the time zone name or abbreviation
2049 optionally present as a comment.
2053 The first `title' line with the package name should start
2054 at the left hand margin; the `trailer' line with the
2055 maintainer and date details should be preceded by exactly
2056 one space. The maintainer details and the date must be
2057 separated by exactly two spaces.
2060 <sect1><heading>Defining alternative changelog formats</heading>
2063 It is possible to use a different format to the standard
2064 one, by providing a parser for the format you wish to
2068 A changelog parser must not interact with the user at
2074 <sect id="srcsubstvars"><heading><tt>debian/substvars</tt>
2075 and variable substitutions </heading>
2078 When <prgn>dpkg-gencontrol</prgn>,
2079 <prgn>dpkg-genchanges</prgn> and <prgn>dpkg-source</prgn>
2080 generate control files they do variable substitutions on
2081 their output just before writing it. Variable
2082 substitutions have the form
2083 <tt>${<var>variable-name</var>}</tt>. The optional file
2084 <tt>debian/substvars</tt> contains variable substitutions
2085 to be used; variables can also be set directly from
2086 <tt>debian/rules</tt> using the <tt>-V</tt> option to the
2087 source packaging commands, and certain predefined
2088 variables are available.
2092 The is usually generated and modified dynamically by
2093 <tt>debian/rules</tt> targets; in this case it must be
2094 removed by the <prgn>clean</prgn> target.
2098 See <manref name="dpkg-source" section="1"> for full
2099 details about source variable substitutions, including the
2100 format of <tt>debian/substvars</tt>.</p>
2103 <sect id="debianfiles"><heading><tt>debian/files</tt>
2107 This file is not a permanent part of the source tree; it
2108 is used while building packages to record which files are
2109 being generated. <prgn>dpkg-genchanges</prgn> uses it
2110 when it generates a <tt>.changes</tt> file.
2114 It should not exist in a shipped source package, and so it
2115 (and any backup files or temporary files such as
2119 <tt>files.new</tt> is used as a temporary file by
2120 <prgn>dpkg-gencontrol</prgn> and
2121 <prgn>dpkg-distaddfile</prgn> - they write a new
2122 version of <tt>files</tt> here before renaming it,
2123 to avoid leaving a corrupted copy if an error
2126 </footnote>) should be removed by the
2127 <prgn>clean</prgn> target. It may also be wise to
2128 ensure a fresh start by emptying or removing it at the
2129 start of the <prgn>binary</prgn> target.
2133 <prgn>dpkg-gencontrol</prgn> adds an entry to this file
2134 for the <tt>.deb</tt> file that will be created by
2135 <prgn>dpkg-deb</prgn> from the control file that it
2136 generates, so for most packages all that needs to be done
2137 with this file is to delete it in <prgn>clean</prgn>.
2141 If a package upload includes files besides the source
2142 package and any binary packages whose control files were
2143 made with <prgn>dpkg-gencontrol</prgn> then they should be
2144 placed in the parent of the package's top-level directory
2145 and <prgn>dpkg-distaddfile</prgn> should be called to add
2146 the file to the list in <tt>debian/files</tt>.</p>
2149 <sect id="restrictions"><heading>Restrictions on objects in source packages
2153 The source package may not contain any hard links
2156 This is not currently detected when building source
2157 packages, but only when extracting
2163 Hard links may be permitted at some point in the
2164 future, but would require a fair amount of
2167 </footnote>, device special files, sockets or setuid or
2171 Setgid directories are allowed.
2176 <sect id="descriptions"><heading>Descriptions of packages - the
2177 <tt>Description</tt> field </heading>
2180 The description is intended to describe the program to a user
2181 who has never met it before so that they know whether they
2182 want to install it. It should also give information about the
2183 significant dependencies and conflicts between this package
2184 and others, so that the user knows why these dependencies and
2185 conflicts have been declared.
2188 <sect1><heading>Notes about writing descriptions
2192 The single line synopsis should be kept brief - certainly
2193 under 80 characters.
2197 Do not include the package name in the synopsis line. The
2198 display software knows how to display this already, and you
2199 do not need to state it. Remember that in many situations
2200 the user may only see the synopsis line - make it as
2201 informative as you can.
2205 Do not try to continue the single line synopsis into the
2206 extended description. This will not work correctly when
2207 the full description is displayed, and makes no sense
2208 where only the summary (the single line synopsis) is
2213 The extended description should describe what the package
2214 does and how it relates to the rest of the system (in terms
2215 of, for example, which subsystem it is which part of).
2219 The description field needs to make sense to anyone, even
2220 people who have no idea about any of the things the
2224 The blurb that comes with a program in its
2225 announcements and/or <prgn>README</prgn> files is
2226 rarely suitable for use in a description. It is
2227 usually aimed at people who are already in the
2228 community where the package is used.
2234 Put important information first, both in the synopsis and
2235 extended description. Sometimes only the first part of the
2236 synopsis or of the description will be displayed. You can
2237 assume that there will usually be a way to see the whole
2238 extended description.
2242 You may include information about dependencies and so forth
2243 in the extended description, if you wish.
2247 Do not use tab characters. Their effect is not predictable.
2255 <chapt id="maintainerscripts"><heading>Package maintainer scripts
2256 and installation procedure
2259 <sect><heading>Introduction to package maintainer scripts
2263 It is possible to supply scripts as part of a package which
2264 the package management system will run for you when your
2265 package is installed, upgraded or removed.
2269 These scripts should be the files <tt>preinst</tt>,
2270 <tt>postinst</tt>, <tt>prerm</tt> and <tt>postrm</tt> in the
2271 control area of the package. They must be proper executable
2272 files; if they are scripts (which is recommended) they must
2273 start with the usual <tt>#!</tt> convention. They should be
2274 readable and executable to anyone, and not world-writable.
2278 the package management system looks at the exit status from
2279 these scripts. It is important that they exit with a
2280 non-zero status if there is an error, so that the package
2281 management system can stop its processing. For shell
2282 scripts this means that you <em>almost always</em> need to
2283 use <tt>set -e</tt> (this is usually true when writing shell
2284 scripts, in fact). It is also important, of course, that
2285 they don't exit with a non-zero status if everything went
2290 It is necessary for the error recovery procedures that the
2291 scripts be idempotent: i.e., invoking the same script several
2292 times in the same situation should do no harm. If the first
2293 call failed, or aborted half way through for some reason,
2294 the second call should merely do the things that were left
2295 undone the first time, if any, and exit with a success
2300 When a package is upgraded a combination of the scripts from
2301 the old and new packages is called in amongst the other
2302 steps of the upgrade procedure. If your scripts are going
2303 to be at all complicated you need to be aware of this, and
2304 may need to check the arguments to your scripts.
2308 Broadly speaking the <prgn>preinst</prgn> is called before
2309 (a particular version of) a package is installed, and the
2310 <prgn>postinst</prgn> afterwards; the <prgn>prerm</prgn>
2311 before (a version of) a package is removed and the
2312 <prgn>postrm</prgn> afterwards.
2315 next paragraph by Guy Maor to close bug #2481
2318 <p> Programs called from maintainer scripts should not
2319 normally have a path prepended to them. Before installation
2320 is started the package management system checks to see if
2321 the programs <prgn>ldconfig</prgn>,
2322 <prgn>start-stop-daemon</prgn>, <prgn>install-info</prgn>,
2323 and <prgn>update-rc.d</prgn> can be found via the
2324 <tt>PATH</tt> environment variable. Those programs, and any
2325 other program that one would expect to on the <tt>PATH</tt>,
2326 should thus be invoked without an absolute
2327 pathname. Maintainer scripts should also not reset the
2328 <tt>PATH</tt>, though they might choose to modify it by pre-
2329 or appending package-specific directories. These
2330 considerations really apply to all shell scripts.</p>
2333 <heading>Maintainer scripts Idempotency</heading>
2336 It is very important to make maintainer scripts
2340 That means that if it runs successfully or fails
2341 and then you call it again it doesn't bomb out,
2342 but just ensures that everything is the way it
2345 </footnote> This is so that if an error occurs, the
2346 user interrupts <prgn>dpkg</prgn> or some other
2347 unforeseen circumstance happens you don't leave the
2348 user with a badly-broken package.
2352 <heading>Controlling terminal for maintainer scripts</heading>
2355 The maintainer scripts are guaranteed to run with a
2356 controlling terminal and can interact with the user.
2357 If they need to prompt for passwords, do full-screen
2358 interaction or something similar you should do these
2359 things to and from <tt>/dev/tty</tt>, since
2360 <prgn>dpkg</prgn> will at some point redirect scripts'
2361 standard input and output so that it can log the
2362 installation process. Likewise, because these scripts
2363 may be executed with standard output redirected into a
2364 pipe for logging purposes, Perl scripts should set
2365 unbuffered output by setting <tt>$|=1</tt> so that the
2366 output is printed immediately rather than being
2371 Each script should return a zero exit status for
2372 success, or a nonzero one for failure.
2376 <sect id="mscriptsinstact"><heading>Summary of ways maintainer
2381 <list compact="compact">
2383 <p><var>new-preinst</var> <tt>install</tt></p>
2386 <p><var>new-preinst</var> <tt>install</tt>
2387 <var>old-version</var></p>
2390 <p><var>new-preinst</var> <tt>upgrade</tt>
2391 <var>old-version</var></p>
2394 <p><var>old-preinst</var> <tt>abort-upgrade</tt>
2395 <var>new-version</var>
2401 <list compact="compact">
2403 <p><var>postinst</var> <tt>configure</tt>
2404 <var>most-recently-configured-version</var></p>
2407 <p><var>old-postinst</var> <tt>abort-upgrade</tt>
2408 <var>new version</var></p>
2411 <p><var>conflictor's-postinst</var> <tt>abort-remove</tt>
2412 <tt>in-favour</tt> <var>package</var>
2413 <var>new-version</var></p>
2417 <var>deconfigured's-postinst</var>
2418 <tt>abort-deconfigure</tt> <tt>in-favour</tt>
2419 <var>failed-install-package</var> <var>version</var>
2420 <tt>removing</tt> <var>conflicting-package</var>
2427 <list compact="compact">
2429 <p><var>prerm</var> <tt>remove</tt></p>
2432 <p><var>old-prerm</var> <tt>upgrade</tt>
2433 <var>new-version</var></p>
2436 <p><var>new-prerm</var> <tt>failed-upgrade</tt>
2437 <var>old-version</var></p>
2440 <p><var>conflictor's-prerm</var> <tt>remove</tt>
2441 <tt>in-favour</tt> <var>package</var>
2442 <var>new-version</var></p>
2446 <var>deconfigured's-prerm</var> <tt>deconfigure</tt>
2447 <tt>in-favour</tt> <var>package-being-installed</var>
2448 <var>version</var> <tt>removing</tt>
2449 <var>conflicting-package</var>
2456 <list compact="compact">
2458 <p><var>postrm</var> <tt>remove</tt></p>
2461 <p><var>postrm</var> <tt>purge</tt></p>
2465 <var>old-postrm</var> <tt>upgrade</tt>
2466 <var>new-version</var></p>
2469 <p><var>new-postrm</var> <tt>failed-upgrade</tt>
2470 <var>old-version</var></p>
2473 <p><var>new-postrm</var> <tt>abort-install</tt></p>
2476 <p><var>new-postrm</var> <tt>abort-install</tt>
2477 <var>old-version</var></p>
2480 <p><var>new-postrm</var> <tt>abort-upgrade</tt>
2481 <var>old-version</var></p>
2485 <var>disappearer's-postrm</var> <tt>disappear</tt>
2486 <var>overwriter</var>
2487 <var>overwriter-version</var></p></item>
2492 <sect id="unpackphase"><heading>Details of unpack phase of
2493 installation or upgrade
2497 The procedure on installation/upgrade/overwrite/disappear
2498 (i.e., when running <tt>dpkg --unpack</tt>, or the unpack
2500 --install</tt>) is as follows. In each case if an error occurs the
2501 actions in are general run backwards - this means that the maintainer
2502 scripts are run with different arguments in reverse order. These are
2503 the `error unwind' calls listed below.
2510 <p>If a version the package is already
2513 <var>old-prerm</var> upgrade <var>new-version</var>
2518 If this gives an error (i.e., a non-zero exit
2519 status), dpkg will attempt instead:
2521 <var>new-prerm</var> failed-upgrade <var>old-version</var>
2523 Error unwind, for both the above cases:
2525 <var>old-postinst</var> abort-upgrade <var>new-version</var>
2533 <p>If a `conflicting' package is being removed at the same time:
2537 If any packages depended on that conflicting
2538 package and <tt>--auto-deconfigure</tt> is
2539 specified, call, for each such package:
2541 <var>deconfigured's-prerm</var> deconfigure \
2542 in-favour <var>package-being-installed</var> <var>version</var> \
2543 removing <var>conflicting-package</var> <var>version</var>
2547 <var>deconfigured's-postinst</var> abort-deconfigure \
2548 in-favour <var>package-being-installed-but-failed</var> <var>version</var> \
2549 removing <var>conflicting-package</var> <var>version</var>
2551 The deconfigured packages are marked as
2552 requiring configuration, so that if
2553 <tt>--install</tt> is used they will be
2554 configured again if possible.</p>
2557 <p>To prepare for removal of the conflicting package, call:
2559 <var>conflictor's-prerm</var> remove in-favour <var>package</var> <var>new-version</var>
2563 <var>conflictor's-postinst</var> abort-remove \
2564 in-favour <var>package</var> <var>new-version</var>
2575 <p>If the package is being upgraded, call:
2577 <var>new-preinst</var> upgrade <var>old-version</var>
2582 Otherwise, if the package had some configuration
2583 files from a previous version installed (i.e., it
2584 is in the `configuration files only' state):
2586 <var>new-preinst</var> install <var>old-version</var>
2590 <p>Otherwise (i.e., the package was completely purged):
2592 <var>new-preinst</var> install
2594 Error unwind versions, respectively:
2596 <var>new-postrm</var> abort-upgrade <var>old-version</var>
2597 <var>new-postrm</var> abort-install <var>old-version</var>
2598 <var>new-postrm</var> abort-install
2608 The new package's files are unpacked, overwriting any
2609 that may be on the system already, for example any
2610 from the old version of the same package or from
2611 another package (backups of the old files are left
2612 around, and if anything goes wrong the package
2613 management system will attempt to put them back as
2614 part of the error unwind).
2618 It is an error for a package to contains files which
2619 are on the system in another package, unless
2620 <tt>Replaces</tt> is used (see <ref id="replaces">).
2621 Currently the <tt>--force-overwrite</tt> flag is
2622 enabled, downgrading it to a warning, but this may not
2627 It is a more serious error for a package to contain a
2628 plain file or other kind of non-directory where another
2629 package has a directory (again, unless
2630 <tt>Replaces</tt> is used). This error can be
2631 overridden if desired using
2632 <tt>--force-overwrite-dir</tt>, but this is not
2637 Packages which overwrite each other's files produce
2638 behavior which though deterministic is hard for the
2639 system administrator to understand. It can easily
2640 lead to `missing' programs if, for example, a package
2641 is installed which overwrites a file from another
2642 package, and is then removed again.
2645 Part of the problem is due to what is arguably a
2646 bug in <prgn>dpkg</prgn>.
2652 A directory will never be replaced by a symbolic links
2653 to a directory or vice versa; instead, the existing
2654 state (symlink or not) will be left alone and
2655 <prgn>dpkg</prgn> will follow the symlink if there is
2663 <p>If the package is being upgraded, call
2665 <var>old-postrm</var> upgrade <var>new-version</var>
2669 <p>If this fails, <prgn>dpkg</prgn> will attempt:
2671 <var>new-postrm</var> failed-upgrade <var>old-version</var>
2673 Error unwind, for both cases:
2675 <var>old-preinst</var> abort-upgrade <var>new-version</var>
2681 This is the point of no return - if
2682 <prgn>dpkg</prgn> gets this far, it won't back off
2683 past this point if an error occurs. This will
2684 leave the package in a fairly bad state, which
2685 will require a successful re-installation to clear
2686 up, but it's when <prgn>dpkg</prgn> starts doing
2687 things that are irreversible.
2692 Any files which were in the old version of the package
2693 but not in the new are removed.</p>
2696 <p>The new file list replaces the old.</p>
2699 <p>The new maintainer scripts replace the old.</p>
2703 <p>Any packages all of whose files have been overwritten during the
2704 installation, and which aren't required for
2705 dependencies, are considered to have been removed.
2706 For each such package,
2709 <p><prgn>dpkg</prgn> calls:
2711 <var>disappearer's-postrm</var> disappear \
2712 <var>overwriter</var> <var>overwriter-version</var>
2717 <p>The package's maintainer scripts are removed.
2722 It is noted in the status database as being in a
2723 sane state, namely not installed (any conffiles
2724 it may have are ignored, rather than being
2725 removed by <prgn>dpkg</prgn>). Note that
2726 disappearing packages do not have their prerm
2727 called, because <prgn>dpkg</prgn> doesn't know
2728 in advance that the package is going to
2737 Any files in the package we're unpacking that are also
2738 listed in the file lists of other packages are removed
2739 from those lists. (This will lobotomize the file list
2740 of the `conflicting' package if there is one.)
2745 The backup files made during installation, above, are
2752 The new package's status is now sane, and recorded as
2753 `unpacked'. Here is another point of no return - if
2754 the conflicting package's removal fails we do not
2755 unwind the rest of the installation; the conflicting
2756 package is left in a half-removed limbo.
2761 If there was a conflicting package we go and do the
2762 removal actions (described below), starting with the
2763 removal of the conflicting package's files (any that
2764 are also in the package being installed have already
2765 been removed from the conflicting package's file list,
2766 and so do not get removed now).
2773 <sect><heading>Details of configuration</heading>
2776 When we configure a package (this happens with <tt>dpkg
2777 --install</tt>, or with <tt>--configure</tt>), we first
2778 update the conffiles and then call:
2780 <var>postinst</var> configure <var>most-recently-configured-version</var>
2785 No attempt is made to unwind after errors during
2790 If there is no most recently configured version
2791 <prgn>dpkg</prgn> will pass a null argument; older versions
2792 of dpkg may pass <tt><unknown></tt> (including the
2793 angle brackets) in this case. Even older ones do not pass a
2794 second argument at all, under any circumstances.
2798 <sect><heading>Details of removal and/or configuration purging
2806 <var>prerm</var> remove
2812 The package's files are removed (except conffiles).
2817 <var>postrm</var> remove
2821 <p>All the maintainer scripts except the postrm are removed.
2825 If we aren't purging the package we stop here. Note
2826 that packages which have no postrm and no conffiles
2827 are automatically purged when removed, as there is no
2828 difference except for the <prgn>dpkg</prgn>
2833 The conffiles and any backup files (<tt>~</tt>-files,
2834 <tt>#*#</tt> files, <tt>%</tt>-files,
2835 <tt>.dpkg-{old,new,tmp}</tt>, etc.) are removed.</p>
2839 <var>postrm</var> purge
2843 <p>The package's file list is removed.</p>
2846 No attempt is made to unwind after errors during
2852 <chapt id="relationships"><heading>Declaring relationships between
2856 Packages can declare in their control file that they have
2857 certain relationships to other packages - for example, that
2858 they may not be installed at the same time as certain other
2859 packages, and/or that they depend on the presence of others,
2860 or that they should overwrite files in certain other packages
2865 This is done using the <tt>Depends</tt>, <tt>Recommends</tt>,
2866 <tt>Suggests</tt>, <tt>Enhances</tt>, <tt>Conflicts</tt>,
2867 <tt>Provides</tt> and <tt>Replaces</tt> control file fields.
2871 Source packages may declare relationships to binary packages,
2872 saying that they require certain binary packages being
2873 installed or absent at the time of building the package.
2877 This is done using the <tt>Build-Depends</tt>,
2878 <tt>Build-Depends-Indep</tt>, <tt>Build-Conflicts</tt>, and
2879 <tt>Build-Conflicts-Indep</tt> control file fields.
2882 <sect id="depsyntax"><heading>Syntax of relationship fields
2886 These fields all have a uniform syntax. They are a list of
2887 package names separated by commas.
2891 In <tt>Depends</tt>, <tt>Recommends</tt>, <tt>Suggests</tt>,
2892 <tt>Pre-Depends</tt>, <tt>Build-Depends</tt> and
2893 <tt>Build-Depends-Indep</tt>(the fields which declare
2894 dependencies of the package in which they occur on other
2895 packages) these package names may also be lists of
2896 alternative package names, separated by vertical bar symbols
2897 <tt>|</tt> (pipe symbols).
2901 All the fields except <tt>Provides</tt> may restrict their
2902 applicability to particular versions of each named package.
2903 This is done in parentheses after each individual package
2904 name; the parentheses should contain a relation from the
2905 list below followed by a version number, in the format
2906 described in <ref id="versions">.
2910 The relations allowed are <tt><<</tt>, <tt><=</tt>,
2911 <tt>=</tt>, <tt>>=</tt> and <tt>>></tt> for
2912 strictly earlier, earlier or equal, exactly equal, later or
2913 equal and strictly later, respectively. The forms
2914 <tt><</tt> and <tt>></tt> were used to mean
2915 earlier/later or equal, rather than strictly earlier/later,
2916 so they should not appear in new packages (though
2917 <prgn>dpkg</prgn> still supports them).
2921 Whitespace may appear at any point in the version
2922 specification, and must appear where it's necessary to
2923 disambiguate; it is not otherwise significant. For
2924 consistency and in case of future changes to
2925 <prgn>dpkg</prgn> it is recommended that a single space be
2926 used after a version relationship and before a version
2927 number; it is usual also to put a single space after each
2928 comma, on either side of each vertical bar, and before each
2937 Depends: libc5 (>= 5.2.18-4), mime-support, csh | tcsh
2942 All fields that specify build-time relationships
2943 (<tt>Build-Depends</tt>, <tt>Build-Depends-Indep</tt>,
2944 <tt>Build-Conflicts</tt> and <tt>Build-Conflicts-Indep</tt>)
2945 may be restricted to a certain set of architectures. This
2946 is done in brackets after each individual package name and
2947 the optional version specification. The brackets enclose a
2948 list of Debian architecture names separated by whitespace.
2949 An exclamation mark may be prepended to each name. If the
2950 current Debian host architecture is not in this list and
2951 there are no exclamation marks in the list, or it is in the
2952 list with a prepended exclamation mark, the package name and
2953 the associated version specification are ignored completely
2954 for the purposes of defining the relationships.
2961 Build-Depends-Indep: texinfo
2962 Build-Depends: kernel-headers-2.2.10 [!hurd-i386],
2963 hurd-dev [hurd-i386], gnumach-dev [hurd-i386]
2969 <heading>Binary Dependencies - <tt>Depends</tt>,
2970 <tt>Recommends</tt>, <tt>Suggests</tt>, <tt>Enhances</tt>,
2971 <tt>Pre-Depends</tt>
2975 These five fields are used to declare a dependency
2976 relationship by one package on another. They appear in the
2977 depending package's control file.
2981 All but <tt>Pre-Depends</tt> and <tt>Conflicts</tt>
2982 (discussed below) take effect <em>only</em> when a package
2983 is to be configured. They do not prevent a package being on
2984 the system in an unconfigured state while its dependencies
2985 are unsatisfied, and it is possible to replace a package
2986 whose dependencies are satisfied and which is properly
2987 installed with a different version whose dependencies are
2988 not and cannot be satisfied; when this is done the depending
2989 package will be left unconfigured (since attempts to
2990 configure it will give errors) and will not function
2995 For this reason packages in an installation run are usually
2996 all unpacked first and all configured later; this gives
2997 later versions of packages with dependencies on later
2998 versions of other packages the opportunity to have their
2999 dependencies satisfied.
3003 Thus <tt>Depends</tt> allows package maintainers to impose
3004 an order in which packages should be configured.
3006 <tag><tt>Depends</tt></tag>
3009 <p>This declares an absolute dependency.
3013 The <tt>Depends</tt> field should be used if the
3014 depended-on package is required for the depending
3015 package to provide a significant amount of
3019 <tag><tt>Recommends</tt></tag>
3021 <p>This declares a strong, but not absolute, dependency.
3025 The <tt>Recommends</tt> field should list packages
3026 that would be found together with this one in all but
3027 unusual installations.</p>
3030 <tag><tt>Suggests</tt></tag>
3034 This is used to declare that one package may be more
3035 useful with one or more others. Using this field
3036 tells the packaging system and the user that the
3037 listed packages are related to this one and can
3038 perhaps enhance its usefulness, but that installing
3039 this one without them is perfectly reasonable.
3043 <tag><tt>Enhances</tt></tag>
3046 This field is similar to Suggests but works in the
3047 opposite direction. It is used to declare that a
3048 package can enhance the functionality of another
3053 <tag><tt>Pre-Depends</tt></tag>
3057 This field is like <tt>Depends</tt>, except that it
3058 also forces <prgn>dpkg</prgn> to complete installation
3059 of the packages named before even starting the
3060 installation of the package which declares the
3065 <tt>Pre-Depends</tt> should be used sparingly,
3066 preferably only by packages whose premature upgrade or
3067 installation would hamper the ability of the system to
3068 continue with any upgrade that might be in progress.
3072 When the package declaring it is being configured, a
3073 <tt>Pre-Dependency</tt> will be considered satisfied
3074 only if the depending package has been correctly
3075 configured, just as if an ordinary <tt>Depends</tt>
3080 However, when a package declaring a Pre-dependency is
3081 being unpacked the predependency can be satisfied even
3082 if the depended-on package(s) are only unpacked or
3083 half-configured, provided that they have been
3084 configured correctly at some point in the past (and
3085 not removed or partially removed since). In this case
3086 both the previously-configured and currently unpacked
3087 or half-configured versions must satisfy any version
3088 clause in the <tt>Pre-Depends</tt> field.
3094 When selecting which level of dependency to use you should
3095 consider how important the depended-on package is to the
3096 functionality of the one declaring the dependency. Some
3097 packages are composed of components of varying degrees of
3098 importance. Such a package should list using
3099 <tt>Depends</tt> the package(s) which are required by the
3100 more important components. The other components'
3101 requirements may be mentioned as Suggestions or
3102 Recommendations, as appropriate to the components' relative
3107 <sect id="conflicts"><heading>Alternative binary packages -
3108 <tt>Conflicts</tt> and <tt>Replaces</tt>
3112 When one binary package declares a conflict with another
3113 <prgn>dpkg</prgn> will refuse to allow them to be installed
3114 on the system at the same time.
3118 If one package is to be installed, the other must be removed
3119 first - if the package being installed is marked as
3120 replacing (<ref id="replaces">) the one on the system, or
3121 the one on the system is marked as deselected, or both
3122 packages are marked <tt>Essential</tt>, then
3123 <prgn>dpkg</prgn> will automatically remove the package
3124 which is causing the conflict, otherwise it will halt the
3125 installation of the new package with an error. This
3126 mechanism specifically doesn't work when the installed
3127 package is <tt>Essential</tt>, but the new package is not.
3132 A package will not cause a conflict merely because its
3133 configuration files are still installed; it must be at least
3138 A special exception is made for packages which declare a
3139 conflict with their own package name, or with a virtual
3140 package which they provide (see below): this does not
3141 prevent their installation, and allows a package to conflict
3142 with others providing a replacement for it. You use this
3143 feature when you want the package in question to be the only
3144 package providing something.
3148 A <tt>Conflicts</tt> entry should almost never have an
3149 `earlier than' version clause. This would prevent
3150 <prgn>dpkg</prgn> from upgrading or installing the package
3151 which declared such a conflict until the upgrade or removal
3152 of the conflicted-with package had been completed.
3156 <sect id="virtual"><heading>Virtual packages - <tt>Provides</tt>
3160 As well as the names of actual (`concrete') packages, the
3161 package relationship fields <tt>Depends</tt>,
3162 <tt>Build-Depends</tt>, <tt>Build-Depends-Indep</tt>,
3163 <tt>Recommends</tt>, <tt>Suggests</tt>, <tt>Conflicts</tt>,
3164 <tt>Build-Conflicts</tt> and <tt>Build-Conflicts-Indep</tt> may
3165 mention virtual packages.
3169 A virtual package is one which appears in the
3170 <tt>Provides</tt> control file field of another package.
3171 The effect is as if the package(s) which provide a
3172 particular virtual package name had been listed by name
3173 everywhere the virtual package name appears.
3177 If there are both a real and a virtual package of the same
3178 name then the dependency may be satisfied (or the conflict
3179 caused) by either the real package or any of the virtual
3180 packages which provide it. This is so that, for example,
3186 and someone else releases an xemacs package they can say
3190 </example> and all will work in the interim (until a purely
3191 virtual package name is decided on and the <tt>emacs</tt>
3192 and <tt>vm</tt> packages are changed to use it).
3196 If a dependency or a conflict has a version number attached
3197 then only real packages will be considered to see whether
3198 the relationship is satisfied (or the prohibition violated,
3199 for a conflict) - it is assumed that a real package which
3200 provides virtual package is not of the `right' version. So,
3201 a <tt>Provides</tt> field may not contain version numbers,
3202 and the version number of the concrete package which
3203 provides a particular virtual package will not be looked at
3204 when considering a dependency on or conflict with the
3205 virtual package name.
3209 It is likely that the ability will be added in a future
3210 release of <prgn>dpkg</prgn> to specify a version number for
3211 each virtual package it provides. This feature is not yet
3212 present, however, and is expected to be used only
3217 If you want to specify which of a set of real packages should be the
3218 default to satisfy a particular dependency on a virtual package, you
3219 should list the real package as an alternative before the virtual.
3224 <sect id="replaces"><heading><tt>Replaces</tt> - overwriting
3225 files and replacing packages
3229 The <tt>Replaces</tt> control file field has two purposes,
3230 which come into play in different situations.
3234 Virtual packages (<ref id="virtual">) are not considered
3235 when looking at a <tt>Replaces</tt> field - the packages
3236 declared as being replaced must be mentioned by their real
3240 <sect1><heading>Overwriting files in other packages
3244 Firstly, as mentioned before, it is usually an error for a
3245 package to contains files which are on the system in
3246 another package, though currently the
3247 <tt>--force-overwrite</tt> flag is enabled by default,
3248 downgrading the error to a warning,
3252 If the overwriting package declares that it replaces the
3253 one containing the file being overwritten then
3254 <prgn>dpkg</prgn> will proceed, and replace the file from
3255 the old package with that from the new. The file will no
3256 longer be listed as `owned' by the old package.
3260 If a package is completely replaced in this way, so that
3261 <prgn>dpkg</prgn> does not know of any files it still
3262 contains, it is considered to have disappeared. It will
3263 be marked as not wanted on the system (selected for
3264 removal) and not installed. Any conffiles details noted
3265 in the package will be ignored, as they will have been
3266 taken over by the replacing package(s). The package's
3267 <prgn>postrm</prgn> script will be run to allow the
3268 package to do any final cleanup required. See <ref
3269 id="mscriptsinstact">.
3273 In the future <prgn>dpkg</prgn> will discard files which
3274 overwrite those from another package which declares that
3275 it replaces the one being installed (so that you can
3276 install an older version of a package without problems).
3280 This usage of <tt>Replaces</tt> only takes effect when
3281 both packages are at least partially on the system at
3282 once, so that it can only happen if they do not conflict
3283 or if the conflict has been overridden.</p>
3286 <sect1><heading>Replacing whole packages, forcing their
3291 Secondly, <tt>Replaces</tt> allows the packaging system to
3292 resolve which package should be removed when there is a
3293 conflict - see <ref id="conflicts">. This usage only
3294 takes effect when the two packages <em>do</em> conflict,
3295 so that the two effects do not interfere with each other.
3300 <sect><heading>Relationships between source and binary packages -
3301 <tt>Build-Depends</tt>, <tt>Build-Depends-Indep</tt>,
3302 <tt>Build-Conflicts</tt>, <tt>Build-Conflicts-Indep</tt>
3306 A source package may declare a dependency or a conflict on a
3307 binary package. This is done with the control file fields
3308 <tt>Build-Depends</tt>, <tt>Build-Depends-Indep</tt>,
3309 <tt>Build-Conflicts</tt>, and <tt>Build-Conflicts-Indep</tt>. Their
3310 semantics is that the dependencies and conflicts they define
3311 must be satisfied (as defined earlier for binary packages),
3312 when one of the targets in <tt>debian/rules</tt> that the
3313 particular field applies to is invoked.
3316 <tag><tt>Build-Depends</tt>, <tt>Build-Conflicts</tt></tag>
3319 The <tt>Build-Depends</tt> and
3320 <tt>Build-Conflicts</tt> fields apply to the targets
3321 <tt>build</tt>, <tt>binary</tt>, <tt>binary-arch</tt>
3322 and <tt>binary-indep</tt>.
3325 <tag><tt>Build-Depends-Indep</tt>, <tt>Build-Conflicts-Indep</tt></tag>
3328 The <tt>Build-Depends-Indep</tt> and
3329 <tt>Build-Conflicts-Indep</tt> fields apply to the
3330 targets <tt>binary</tt> and <tt>binary-indep</tt>.
3341 <chapt id="conffiles"><heading>Configuration file handling
3345 <prgn>dpkg</prgn> can do a certain amount of automatic
3346 handling of package configuration files.
3350 Whether this mechanism is appropriate depends on a number of
3351 factors, but basically there are two approaches to any
3352 particular configuration file.
3356 The easy method is to ship a best-effort configuration in the
3357 package, and use <prgn>dpkg</prgn>'s conffile mechanism to
3358 handle updates. If the user is unlikely to want to edit the
3359 file, but you need them to be able to without losing their
3360 changes, and a new package with a changed version of the file
3361 is only released infrequently, this is a good approach.
3365 The hard method is to build the configuration file from
3366 scratch in the <prgn>postinst</prgn> script, and to take the
3367 responsibility for fixing any mistakes made in earlier
3368 versions of the package automatically. This will be
3369 appropriate if the file is likely to need to be different on
3374 <chapt id="sharedlibs"><heading>Shared libraries
3378 Packages containing shared libraries must be constructed with
3379 a little care to make sure that the shared library is always
3380 available. This is especially important for packages whose
3381 shared libraries are vitally important, such as the libc.
3385 Firstly, your package should install the shared libraries
3386 under their normal names. For example, the
3387 <prgn>libgdbm1</prgn> package should install
3388 <tt>libgdbm.so.1.7.3</tt> as
3389 <tt>/usr/lib/libgdbm.so.1.7.3</tt>. The files should not be
3390 renamed or re-linked by any prerm or postrm scripts;
3391 <prgn>dpkg</prgn> will take care of renaming things safely
3392 without affecting running programs, and attempts to interfere
3393 with this are likely to lead to problems.
3397 Secondly, your package should include the symlink that
3398 <prgn>ldconfig</prgn> would create for the shared libraries.
3399 For example, the <prgn>libgdbm1</prgn> package should include
3400 a symlink from <tt>/usr/lib/libgdbm.so.1</tt> to
3401 <tt>libgdbm.so.1.7.3</tt>. This is needed so that
3402 <prgn>ld.so</prgn> can find the library in between the time
3403 <prgn>dpkg</prgn> installs it and <prgn>ldconfig</prgn> is run
3404 in the <prgn>postinst</prgn> script. Furthermore, older
3405 versions of the package management system required the library
3406 must be placed before the symlink pointing to it in the
3407 <tt>.deb</tt> file. This is so that by the time
3408 <prgn>dpkg</prgn> comes to install the symlink (overwriting
3409 the previous symlink pointing at an older version of the
3410 library) the new shared library is already in place.
3411 Unfortunately, this was not not always possible, since it
3412 highly depends on the behavior of the file system. Some
3413 file systems (such as reiserfs) will reorder the files so it
3414 doesn't matter in what order you create them. Starting with
3415 release <tt>1.7.0</tt> <prgn>dpkg</prgn> will reorder the
3416 files itself when building a package.
3420 next Paragraph added to close Bug #5299, Guy Maor
3424 Thirdly, the development package should contain a symlink for
3425 the shared library without a version number. For example, the
3426 <tt>libgdbm1-dev</tt> package should include a symlink from
3427 <tt>/usr/lib/libgdm.so</tt> to <tt>libgdm.so.1.7.3</tt>. This
3428 symlink is needed by <prgn>ld</prgn> when compiling packages
3429 as it will only look for <tt>libgdm.so</tt> and
3430 <tt>libgdm.a</tt> when compiling dynamically or statically,
3435 next paragraph changed by Christian Schwarz (see policy weekly #6)
3439 Any package installing shared libraries in a directory that's listed
3440 in <tt>/etc/ld.so.conf</tt> or in one of the default library
3441 directories of <prgn>ld.so</prgn> (currently, these are <tt>/usr/lib</tt>
3442 and <tt>/lib</tt>) must call <prgn>ldconfig</prgn> in its <prgn>postinst</prgn>
3443 script if and only if the first argument is `configure'. However, it
3444 is important not to call <prgn>ldconfig</prgn> in the postrm or preinst
3445 scripts in the case where the package is being upgraded (see <ref
3446 id="unpackphase">), as <prgn>ldconfig</prgn> will see the temporary names
3447 that <prgn>dpkg</prgn> uses for the files while it is
3448 installing them and will make the shared library links point
3449 to them, just before <prgn>dpkg</prgn> continues the
3450 installation and removes the links!
3454 moved from section 2.2 , DMorris
3457 <sect id="shlibs"><heading>The <tt>shlibs</tt> File Format
3461 This file is for use by <prgn>dpkg-shlibdeps</prgn> and is
3462 required when your package provides shared libraries.
3466 Each line is of the form:
3468 <var>library-name</var> <var>version-or-soname</var> <var>dependencies ...</var>
3473 <var>library-name</var> is the name of the shared library,
3474 for example <tt>libc5</tt>.
3478 <var>version-or-soname</var> is the soname of the library -
3479 i.e., the thing that must exactly match for the library to be
3480 recognized by <prgn>ld.so</prgn>. Usually this is major
3481 version number of the library.
3485 <var>dependencies</var> has the same syntax as a dependency
3486 field in a binary package control file. It should give
3487 details of which package(s) are required to satisfy a binary
3488 built against the version of the library contained in the
3489 package. See <ref id="depsyntax">.
3493 For example, if the package <tt>foo</tt> contains
3494 <tt>libfoo.so.1.2.3</tt>, where the soname of the library is
3495 <tt>libfoo.so.1</tt>, and the first version of the package
3496 which contained a minor number of at least <tt>2.3</tt> was
3497 <var>1.2.3-1</var>, then the package's <var>shlibs</var>
3500 libfoo 1 foo (>= 1.2.3-1)
3505 The version-specific dependency is to avoid warnings from
3506 <prgn>ld.so</prgn> about using older shared libraries with
3510 <sect><heading>Further Technical information on
3511 <tt>shlibs</tt></heading>
3515 following section mostly provided by Heiko Schlittermann
3519 <sect1><heading><em>What</em> are the <tt>shlibs</tt> files?
3523 The <tt>debian/shlibs</tt> file provides a way of checking
3524 for shared library dependencies on packaged binaries.
3525 They are intended to be used by package maintainers to
3526 make their lives easier.
3530 Other <tt>shlibs</tt> files that exist on a Debian system are
3532 <item> <p><tt>/etc/dpkg/shlibs.default</tt></p></item>
3533 <item> <p><tt>/etc/dpkg/shlibs.override</tt></p></item>
3534 <item> <p><tt>/var/lib/dpkg/info/*.shlibs</tt></p></item>
3535 <item> <p><tt>debian/shlibs.local</tt></p></item>
3537 These files are used by <prgn>dpkg-shlibdeps</prgn> when
3538 creating a binary package.</p>
3541 <sect1><heading><em>How</em> does <prgn>dpkg-shlibdeps</prgn>
3545 <prgn>dpkg-shlibdeps</prgn>
3546 determines the shared libraries directly
3549 Currently, it calls <prgn>ldd</prgn>, but in a
3550 forthcoming version it shall call <prgn>objdump</prgn>
3551 to to this. This however changes will need a couple of
3552 changes in the way that packages are build.
3555 Suppose a binary <tt>foo</tt> directly use a library
3556 <tt>libbar</tt> if it is linked with that
3557 library. Other libraries that are needed by
3558 <tt>libbar</tt> are linked indirectly to <tt>foo</tt>,
3559 and the dynamic linker will load the automatically
3560 when it loads <tt>libbar</tt>. Using <prgn>ldd</prgn>
3561 lists all the libraries, used directly and indirectly;
3562 but <prgn>objdump</prgn> only lists the directly
3563 linked libraries. A package only needs to depend on
3564 the libraries it is directly linked to, since the
3565 dependencies for those libraries should automatically
3566 pull in the other libraries.</p>
3569 This change does mean a change in the way packages are
3570 build though: currently dpkg-shlibdeps is only run on
3571 binaries. But since we will now depend on the
3572 libraries to depend on the libraries they need the
3573 packages containing those libraries will need to run
3574 dpkg-shlibdeps on the libraries.
3577 A good example where this would help us is the current
3578 mess with multiple version of the mesa library. With
3579 the ldd-based system every package that uses mesa need
3580 to add a dependency on svgalib|svgalib-dummy in order
3581 to handle the glide mesa variant. With an
3582 objdump-based system this isn't necessary anymore and
3583 would have saved everyone a lot of work.
3586 Another example: we could update libimlib with a new
3587 version that supports a new graphics format called
3588 dgf. If we use the old ldd method every package that
3589 uses libimlib would need to be recompiled so it would
3590 also depend on libdgf or it wouldn't run due to
3591 missing symbols. However with the new system packages
3592 using libimlib can depend on libimlib itself having
3593 the dependency on libgdh and wouldn't need to be
3597 used by the compiled binaries (and libraries, in a version
3598 of <prgn>dpkg-shlibdeps</prgn> coming soon) passed through
3599 on its command line.
3603 For each shared library, <prgn>dpkg-shlibdeps</prgn> needs to know
3604 <list compact="compact">
3605 <item><p>the package containing the library, and</p></item>
3606 <item><p>the library version number,</p></item>
3609 it scans the following files in this order.
3610 <enumlist compact="compact">
3611 <item><p><tt>debian/shlibs.local</tt></p></item>
3612 <item><p><tt>/etc/dpkg/shlibs.override</tt></p></item>
3613 <item><p><tt>/var/lib/dpkg/info/*.shlibs</tt></p></item>
3614 <item><p><tt>/etc/dpkg/shlibs.default</tt></p></item>
3618 <sect1><heading><em>Who</em> maintains the various
3619 <tt>shlibs</tt> files?
3623 <list compact="compact">
3625 <p><tt>/etc/dpkg/shlibs.default</tt> - the maintainer
3630 <tt>/var/lib/dpkg/info/<var>package</var>.shlibs</tt>
3631 - the maintainer of each package</p>
3635 <tt>/etc/dpkg/shlibs.override</tt> - the local
3636 system administrator</p>
3639 <p><tt>debian/shlibs.local</tt> - the maintainer of
3644 The <tt>shlibs.default</tt> file is managed by
3645 <prgn>dpkg</prgn>. The entries in <tt>shlibs.default</tt>
3646 that are provided by <prgn>dpkg</prgn> are just there to
3647 fix things until the shared library packages all have
3648 <tt>shlibs</tt> files.
3652 <sect1><heading><em>How</em> to use <prgn>dpkg-shlibdeps</prgn> and
3653 the <tt>shlibs</tt> files?
3656 <sect2><heading>If your package doesn't provide a shared
3661 Put a call to <prgn>dpkg-shlibdeps</prgn> into your
3662 <tt>debian/rules</tt> file. If your package contains
3663 only binaries (e.g. no scripts) use:
3665 dpkg-shlibdeps debian/tmp/usr/bin/* debian/tmp/usr/sbin/*
3667 If <prgn>dpkg-shlibdeps</prgn> doesn't complain, you're
3668 done. If it does complain you might need to create your
3669 own <tt>debian/shlibs.local</tt> file.</p>
3672 <sect2><heading>If your package provides a shared library
3676 Create a <tt>debian/shlibs</tt> file and let
3677 <tt>debian/rules</tt> install it in the control area:
3679 install -m644 debian/shlibs debian/tmp/DEBIAN
3681 If your package contains additional binaries see above.
3686 <sect1><heading><em>How</em> to write
3687 <tt>debian/shlibs.local</tt>
3691 This file is intended only as a <em>temporary</em> fix if
3692 your binaries depend on a library which doesn't provide
3693 its own <tt>/var/lib/dpkg/info/*.shlibs</tt> file yet.
3697 Let's assume you are packaging a binary <tt>foo</tt>. Your
3698 output in building the package might look like this.
3701 libbar.so.1 => /usr/X11R6/lib/libbar.so.1.0
3702 libc.so.5 => /lib/libc.so.5.2.18
3703 libX11.so.6 => /usr/X11R6/lib/libX11.so.6.0
3705 And when you ran <prgn>dpkg-shlibdeps</prgn>
3707 $ dpkg-shlibdeps -o foo
3708 dpkg-shlibdeps: warning: unable to find dependency information
3709 for shared library libbar
3710 (soname 1, path /usr/X11R6/lib/libbar.so.1.0, dependency field Depends)
3711 shlibs:Depends=elf-x11r6lib, libc5 (>= 5.2.18)
3713 The <prgn>foo</prgn> binary depends on the
3714 <prgn>libbar</prgn> shared library, but no package seems
3715 to provide a <tt>*.shlibs</tt> file in
3716 <tt>var/lib/dpkg/info/</tt>. Let's determine the package
3722 $ dpkg -S /usr/X11R6/lib/libbar.so.1.0
3723 bar1: /usr/X11R6/lib/libbar.so.1.0
3724 $ dpkg -s bar1 | grep Version
3727 This tells us that the <prgn>bar1</prgn> package, version
3728 1.0-1 is the one we are using. Now we can create our own
3729 <tt>debian/shlibs.local</tt> to temporarily fix the above
3730 problem. Include the following line into your
3731 <tt>debian/shlibs.local</tt> file.
3733 libbar 1 bar1 (>= 1.0-1)
3735 Now your package build should work. As soon as the
3736 maintainer of <prgn>libbar1</prgn> provides a
3737 <tt>shlibs</tt> file, you can remove your
3738 <tt>debian/shlibs.local</tt> file.
3744 <chapt><heading>The Operating System</heading>
3748 <heading>File system hierarchy</heading>
3752 <heading>Linux File system Structure</heading>
3755 The location of all installed files and directories must
3756 comply with the Linux File system Hierarchy Standard
3757 (FHS). The latest version of this document can be found
3758 alongside this manual or on
3759 <url id="http://www.pathname.com/fhs/">.
3760 Specific questions about following the standard may be
3761 asked on <prgn>debian-devel</prgn>, or referred to Daniel
3762 Quinlan, the FHS coordinator, at
3763 <email>quinlan@pathname.com</email>.</p></sect1>
3767 <heading>Site-specific programs</heading>
3770 As mandated by the FHS, packages must not place any
3771 files in <tt>/usr/local</tt>, either by putting them in
3772 the file system archive to be unpacked by <prgn>dpkg</prgn>
3773 or by manipulating them in their maintainer scripts.</p>
3776 However, the package may create empty directories below
3777 <tt>/usr/local</tt> so that the system administrator knows
3778 where to place site-specific files. These directories
3779 should be removed on package removal if they are
3783 Note, that this applies only to directories <em>below</em>
3784 <tt>/usr/local</tt>, not <em>in</em>
3785 <tt>/usr/local</tt>. Packages must not create sub-directories
3786 in the directory <tt>/usr/local</tt> itself, except those listed in
3787 FHS, section 4.5. However, you may create directories
3788 below them as you wish. You must not remove any of the
3789 directories listed in 4.5, even if you created them.</p>
3792 Since <tt>/usr/local</tt> can be mounted read-only from a
3793 remote server, these directories must be created and
3794 removed by the <tt>postinst</tt> and <tt>prerm</tt>
3795 maintainer scripts. These scripts must not fail if either
3796 of these operations fail. (In the future, it will be
3797 possible to tell <prgn>dpkg</prgn> not to unpack files
3798 matching certain patterns, so that the directories can be
3799 included in the <tt>.deb</tt> packages and system
3800 administrators who do not wish these directories in
3801 /usr/local do not need to have them.)</p>
3804 For example, the <prgn>emacs</prgn> package will contain
3806 mkdir -p /usr/local/lib/emacs/site-lisp || true
3808 in the <tt>postinst</tt> script, and
3810 rmdir /usr/local/lib/emacs/site-lisp || true
3811 rmdir /usr/local/lib/emacs || true
3813 in the <tt>prerm</tt> script.</p>
3816 If you do create a directory in <tt>/usr/local</tt> for
3817 local additions to a package, you should ensure that
3818 settings in <tt>/usr/local</tt> take precedence over the
3819 equivalents in <tt>/usr</tt>.</p>
3822 However, because '/usr/local' and its contents are for
3823 exclusive use of the local administrator, a package must
3824 not rely on the presence or absence of files or
3825 directories in '/usr/local' for normal operation.</p>
3828 The <tt>/usr/local</tt> directory itself and all the
3829 subdirectories created by the package should (by default) have
3830 permissions 2775 (group-writable and set-group-id) and be
3831 owned by <tt>root.staff</tt>.</p>
3836 <heading>Users and groups</heading>
3839 The Debian system can be configured to use either plain or
3840 shadow passwords.</p>
3843 Some user ids (UIDs) and group ids (GIDs) are reserved
3844 globally for use by certain packages. Because some packages
3845 need to include files which are owned by these users or
3846 groups, or need the ids compiled into binaries, these ids
3847 must be used on any Debian system only for the purpose for
3848 which they are allocated. This is a serious restriction, and
3849 we should avoid getting in the way of local administration
3850 policies. In particular, many sites allocate users and/or
3851 local system groups starting at 100.</p>
3854 Apart from this we should have dynamically allocated ids,
3855 which should by default be arranged in some sensible
3856 order--but the behavior should be configurable.</p>
3859 Packages other than <tt>base-passwd</tt> must not modify
3860 <tt>/etc/passwd</tt>, <tt>/etc/shadow</tt>,
3861 <tt>/etc/group</tt> or <tt>/etc/gshadow</tt>.</p>
3864 The UID and GID ranges are as follows:
3869 Globally allocated by the Debian project, the
3870 same on every Debian system. These ids will appear in
3871 the <tt>passwd</tt> and <tt>group</tt> files of all
3872 Debian systems, new ids in this range being added
3873 automatically as the <tt>base-passwd</tt> package is
3877 Packages which need a single statically allocated uid
3878 or gid should use one of these; their maintainers
3879 should ask the <tt>base-passwd</tt> maintainer for
3886 Dynamically allocated system users and groups.
3887 Packages which need a user or group, but can have this
3888 user or group allocated dynamically and differently on
3889 each system, should use `<tt>adduser --system</tt>' to
3890 create the group and/or user. <prgn>adduser</prgn>
3891 will check for the existence of the user or group, and
3892 if necessary choose an unused id based on the ranges
3893 specified in <tt>adduser.conf</tt>.</p></item>
3896 <tag>1000-29999:</tag>
3899 Dynamically allocated user accounts. By default
3900 <prgn>adduser</prgn> will choose UIDs and GIDs for
3901 user accounts in this range, though
3902 <tt>adduser.conf</tt> may be used to modify this
3906 <tag>30000-59999:</tag>
3908 <p>Reserved.</p></item>
3911 <tag>60000-64999:</tag>
3914 Globally allocated by the Debian project, but only
3915 created on demand. The ids are allocated centrally and
3916 statically, but the actual accounts are only created
3917 on users' systems on demand.</p>
3920 These ids are for packages which are obscure or which
3921 require many statically-allocated ids. These packages
3922 should check for and create the accounts in
3923 <tt>/etc/passwd</tt> or <tt>/etc/group</tt> (using
3924 <prgn>adduser</prgn> if it has this facility) if
3925 necessary. Packages which are likely to require
3926 further allocations should have a `hole' left after
3927 them in the allocation, to give them room to
3931 <tag>65000-65533:</tag>
3933 <p>Reserved.</p></item>
3938 <p>User `<tt>nobody</tt>.' The corresponding gid refers
3939 to the group `<tt>nogroup</tt>.'</p></item>
3945 <tt>(uid_t)(-1) == (gid_t)(-1)</tt>. NOT TO BE USED,
3946 because it is the error return sentinel value.</p>
3951 <sect id="sysvinit">
3952 <heading>System run levels</heading>
3955 <sect1 id="/etc/init.d">
3956 <heading>Introduction</heading>
3959 The <tt>/etc/init.d</tt> directory contains the scripts
3960 executed by <prgn>init</prgn> at boot time and when init
3961 state (or `runlevel') is changed (see <manref name="init"
3965 There are at least two different, yet functionally
3966 equivalent, ways of handling these scripts. For the sake
3967 of simplicity, this document describes only the symbolic
3968 link method. However, it must not be assumed by maintainer
3969 scripts that this method is being used, and any automated
3970 manipulation of the various runlevel behaviours by
3971 maintainer scripts must be performed using `update-rc.d'
3972 as described below and not by manually installing or
3973 removing symlinks. For information on the
3974 implementation details of the other method, implemented in
3975 the <tt>file-rc</tt> package, please refer to the
3976 documentation of that package.</p>
3979 These scripts are referenced by symbolic links in
3980 the <tt>/etc/rc<var>n</var>.d</tt> directories. When
3981 changing runlevels, <prgn>init</prgn> looks in the
3982 directory <tt>/etc/rc<var>n</var>.d</tt> for the scripts
3983 it should execute, where <var>n</var> is the runlevel that
3984 is being changed to, or `S' for the boot-up scripts.</p>
3987 The names of the links all have the form
3988 <tt>S<var>mm</var><var>script</var></tt> or
3989 <tt>K<var>mm</var><var>script</var></tt> where
3990 <var>mm</var> is a two-digit number and <var>script</var>
3991 is the name of the script (this should be the same as the
3992 name of the actual script in <tt>/etc/init.d</tt>.</p>
3995 When <prgn>init</prgn> changes runlevel first the targets
3996 of the links whose names starting with a <tt>K</tt> are
3997 executed, each with the single argument <tt>stop</tt>,
3998 followed by the scripts prefixed with an <tt>S</tt>, each
3999 with the single argument <tt>start</tt>. The <tt>K</tt>
4000 links are responsible for killing services and the
4001 <tt>S</tt> link for starting services upon entering the
4005 For example, if we are changing from runlevel 2 to
4006 runlevel 3, init will first execute all of the <tt>K</tt>
4007 prefixed scripts it finds in <tt>/etc/rc3.d</tt>, and then
4008 all of the <tt>S</tt> prefixed scripts. The links
4009 starting with <tt>K</tt> will cause the referred-to file
4010 to be executed with an argument of <tt>stop</tt>, and the
4011 <tt>S</tt> links with an argument of <tt>start</tt>.</p>
4014 The two-digit number <var>mm</var> is used to decide which
4015 order to start and stop things in--low-numbered links have
4016 their scripts run first. For example, the <tt>K20</tt>
4017 scripts will be executed before the <tt>K30</tt> scripts.
4018 This is used when a certain service must be started before
4019 another. For example, the name server <prgn>bind</prgn>
4020 might need to be started before the news server
4021 <prgn>inn</prgn> so that <prgn>inn</prgn> can set up its
4022 access lists. In this case, the script that starts
4023 <prgn>bind</prgn> would have a lower number than the
4024 script that starts <prgn>inn</prgn> so that it runs first:
4033 <heading>Writing the scripts</heading>
4036 Packages that include daemons for system services should
4037 place scripts in <tt>/etc/init.d</tt> to start or stop
4038 services at boot time or during a change of runlevel.
4039 These scripts should be named
4040 <tt>/etc/init.d/<var>package</var></tt>, and they should
4041 accept one argument, saying what to do:
4044 <tag><tt>start</tt></tag>
4045 <item><p>start the service,</p></item>
4047 <tag><tt>stop</tt></tag>
4048 <item><p>stop the service,</p></item>
4050 <tag><tt>restart</tt></tag>
4051 <item><p>stop and restart the service,</p></item>
4053 <tag><tt>reload</tt></tag>
4054 <item><p>cause the configuration of the service to be
4055 reloaded without actually stopping and restarting
4056 the service,</p></item>
4058 <tag><tt>force-reload</tt></tag> <item><p>cause the
4059 configuration to be reloaded if the service supports
4060 this, otherwise restart the service.</p></item>
4063 The <tt>start</tt>, <tt>stop</tt>, <tt>restart</tt>, and
4064 <tt>force-reload</tt> options should be supported by all
4065 scripts in <tt>/etc/init.d</tt>, the <tt>reload</tt>
4066 option is optional.</p>
4069 The <tt>init.d</tt> scripts should ensure that they will
4070 behave sensibly if invoked with <tt>start</tt> when the
4071 service is already running, or with <tt>stop</tt> when it
4072 isn't, and that they don't kill unfortunately-named user
4073 processes. The best way to achieve this is usually to use
4074 <prgn>start-stop-daemon</prgn>.</p>
4077 If a service reloads its configuration automatically (as
4078 in the case of <prgn>cron</prgn>, for example), the
4079 <tt>reload</tt> option of the <tt>init.d</tt> script
4080 should behave as if the configuration has been reloaded
4084 These scripts should not fail obscurely when the
4085 configuration files remain but the package has been
4086 removed, as configuration files remain on the system after
4087 the package has been removed. Only when <prgn>dpkg</prgn>
4088 is executed with the <tt>--purge</tt> option will
4089 configuration files be removed. In particular, the init
4090 script itself is usually a configuration file (see
4091 <ref id="init.d notes">), and will remain on the system if
4092 the package is removed but not purged. Therefore, you
4093 should include a <tt>test</tt> statement at the top of the
4096 test -f <var>program-executed-later-in-script</var> || exit 0
4100 Often there are some values in the `<tt>init.d</tt>'
4101 scripts that a system administrator will frequently want
4102 to change. While the scripts are frequently conffiles,
4103 modifying them requires that the administrator merge in
4104 their changes each time the package is upgraded and the
4105 conffile changes. To ease the burden on the system
4106 administrator, such configurable values should not be
4107 placed directly in the script. Instead, they should be
4108 placed in a file in `<tt>/etc/default</tt>', which
4109 typically will have the same base name as the
4110 `<tt>init.d</tt>' script. This extra file can be sourced
4111 by the script when the script runs. It must contain only
4112 variable settings and comments.
4116 To ensure that vital configurable values are always
4117 available, the `<tt>init.d</tt>' script should set default
4118 values for each of the shell variables it uses before
4119 sourcing the <tt>/etc/default/</tt> file. Also, since the
4120 `<tt>/etc/default/</tt>' file is often a conffile, the
4121 `<tt>init.d</tt>' script must behave sensibly without
4122 failing if it is deleted.
4128 <heading>Managing the links</heading>
4131 The program <prgn>update-rc.d</prgn> is provided to make
4132 it easier for package maintainers to arrange for the
4133 proper creation and removal of
4134 <tt>/etc/rc<var>n</var>.d</tt> symbolic links, or their
4135 functional equivalent if another method is being used.
4136 This may be used by maintainers in their packages'
4137 <tt>postinst</tt> and <tt>postrm</tt> scripts.</p>
4140 You must use this script to make changes to
4141 <tt>/etc/rc<var>n</var>.d</tt> and <em>never</em> either
4142 include any <tt>/etc/rc<var>n</var>.d</tt> symbolic links
4143 in the actual archive or manually create or remove the
4144 symbolic links in maintainer scripts. (The latter will
4145 fail if an alternative method of maintaining runlevel
4146 information is being used.)</p>
4149 By default <prgn>update-rc.d</prgn> will start services in
4150 each of the multi-user state runlevels (2, 3, 4, and 5)
4151 and stop them in the halt runlevel (0), the single-user
4152 runlevel (1) and the reboot runlevel (6). The system
4153 administrator will have the opportunity to customize
4154 runlevels by either running <prgn>update-rc.d</prgn>, by
4155 simply adding, moving, or removing the symbolic links in
4156 <tt>/etc/rc<var>n</var>.d</tt> if symbolic links are being
4157 used, or by modifying <tt>/etc/runlevel.conf</tt> if the
4158 <tt>file-rc</tt> method is being used.</p>
4161 To get the default behavior for your package, put in your
4162 <tt>postinst</tt> script
4164 update-rc.d <var>package</var> defaults >/dev/null
4166 and in your <tt>postrm</tt>
4168 if [ purge = "$1" ]; then
4169 update-rc.d <var>package</var> remove >/dev/null
4174 This will use a default sequence number of 20. If it does
4175 not matter when or in which order the script is run, use
4176 this default. If it does, then you should talk to the
4177 maintainer of the <prgn>sysvinit</prgn> package or post to
4178 <tt>debian-devel</tt>, and they will help you choose a
4182 For more information about using <tt>update-rc.d</tt>,
4183 please consult its manpage <manref name="update-rc.d"
4184 section="8">.</p></sect1>
4188 <heading>Boot-time initialization</heading>
4191 There used to be another directory, <tt>/etc/rc.boot</tt>,
4192 which contained scripts which were run once per machine
4193 boot. This has been deprecated in favour of links from
4194 <tt>/etc/rcS.d</tt> to files in <tt>/etc/init.d</tt> as
4195 described in <ref id="/etc/init.d">. Packages must not
4196 place files in <tt>/etc/rc.boot</tt>.</p>
4198 <sect1 id="init.d notes">
4199 <heading>Notes</heading>
4202 <em>Do not</em> include the
4203 <tt>/etc/rc<var>n</var>.d/*</tt> symbolic links in the
4204 <tt>.deb</tt> file system archive! <em>This will cause
4205 problems!</em> You must create them with
4206 <prgn>update-rc.d</prgn>, as above.</p>
4209 <em>Do not</em> include the
4210 <tt>/etc/rc<var>n</var>.d/*</tt> symbolic links in
4211 <prgn>dpkg</prgn>'s conffiles list! <em>This will cause
4212 problems!</em> You should, however, treat the
4213 <tt>/etc/init.d</tt> scripts as configuration files,
4214 either by marking them as conffiles or managing them
4215 correctly in the maintainer scripts (see
4216 <ref id="config files">). (This is important since we want
4217 to give the local system administrator the chance to adapt
4218 the scripts to the local system--e.g., to disable a
4219 service without de-installing the package, or to specify
4220 some special command line options when starting a
4221 service--while making sure her changes aren't lost during
4222 the next package upgrade.)</p>
4226 <heading>Example</heading>
4229 The <prgn>bind</prgn> DNS (nameserver) package wants to
4230 make sure that the nameserver is running in multiuser
4231 runlevels, and is properly shut down with the system. It
4232 puts a script in <tt>/etc/init.d</tt>, naming the script
4233 appropriately <tt>bind</tt>. As you can see, the script
4234 interprets the argument <tt>reload</tt> to send the
4235 nameserver a <tt>HUP</tt> signal (causing it to reload its
4236 configuration); this way the user can say
4237 <tt>/etc/init.d/bind reload</tt> to reload the name
4238 server. The script has one configurable value, which can
4239 be used to pass parameters to the named program at
4247 # Original version by Robert Leslie
4248 # <rob@mars.org>, edited by iwj and cs
4250 test -x /usr/sbin/named || exit 0
4252 # Source defaults file.
4254 if [ -f /etc/default/bind ]; then
4261 echo -n "Starting domain name service: named"
4262 start-stop-daemon --start --quiet --exec /usr/sbin/named \
4267 echo -n "Stopping domain name service: named"
4268 start-stop-daemon --stop --quiet \
4269 --pidfile /var/run/named.pid --exec /usr/sbin/named
4273 echo -n "Restarting domain name service: named"
4274 start-stop-daemon --stop --quiet \
4275 --pidfile /var/run/named.pid --exec /usr/sbin/named
4276 start-stop-daemon --start --verbose --exec /usr/sbin/named \
4280 force-reload|reload)
4281 echo -n "Reloading configuration of domain name service: named"
4282 start-stop-daemon --stop --signal 1 --quiet \
4283 --pidfile /var/run/named.pid --exec /usr/sbin/named
4287 echo "Usage: /etc/init.d/bind {start|stop|restart|reload|force-reload}" >&2
4297 Complementing the above init script is a file
4298 '<tt>/etc/default/bind</tt>', which contains configurable
4299 parameters used by the script.
4303 # Specified parameters to pass to named. See named(8).
4304 # You may uncomment the following line, and edit to taste.
4310 Another example on which to base your <tt>/etc/init.d</tt>
4311 scripts is in <tt>/etc/init.d/skeleton</tt>.</p>
4314 If this package is happy with the default setup from
4315 <prgn>update-rc.d</prgn>, namely an ordering number of 20
4316 and having named running in all runlevels, it can say in
4317 its <tt>postinst</tt>:
4319 update-rc.d bind defaults >/dev/null
4321 And in its <tt>postrm</tt>, to remove the links when the
4324 if [ purge = "$1" ]; then
4325 update-rc.d bind remove >/dev/null
4331 <heading>Cron jobs</heading>
4334 Packages must not modify the configuration file
4335 <tt>/etc/crontab</tt>, and they must not modify the files in
4336 <tt>/var/spool/cron/crontabs</tt>.</p>
4339 If a package wants to install a job that has to be executed
4340 via cron, it should place a file with the name if the
4341 package in one of the following directories:
4347 As these directory names imply, the files within them are
4348 executed on a daily, weekly, or monthly basis,
4349 respectively. The exact times are listed in
4350 <tt>/etc/crontab</tt>.</p>
4353 All files installed in any of these directories must be
4354 scripts (shell scripts, Perl scripts, etc.) so that they can
4355 easily be modified by the local system administrator. In
4356 addition, they should be treated as configuration files.</p>
4359 If a certain job has to be executed more frequently than
4360 daily, the package should install a file
4361 <tt>/etc/cron.d/<var>package-name</var></tt>. This file uses
4362 the same syntax as <tt>/etc/crontab</tt> and is processed by
4363 <prgn>cron</prgn> automatically. The file must also be
4364 treated as a configuration file. (Note, that entries in the
4365 <tt>/etc/cron.d</tt> directory are not handled by
4366 <prgn>anacron</prgn>. Thus, you should only use this
4367 directory for jobs which may be skipped if the system is not
4371 The scripts or crontab entries in these directories should
4372 check if all necessary programs are installed before they
4373 try to execute them. Otherwise, problems will arise when a
4374 package was removed but not purged since configuration files
4375 are kept on the system in this situation.</p>
4379 <heading>Console messages</heading>
4382 This section describes different formats for messages
4383 written to standard output by the <tt>/etc/init.d</tt>
4384 scripts. The intent is to improve the consistency of
4385 Debian's startup and shutdown look and feel.</p>
4388 Please look very careful at the details. We want to get the
4389 messages to look exactly the same way concerning spaces,
4390 punctuation, and case of letters.</p>
4393 Here is a list of overall rules that you should use when you
4394 create output messages. They can be useful if you have a
4395 non-standard message that isn't covered in the sections
4402 Every message should cover one line, start with a
4403 capital letter and end with a period `.'.</p></item>
4408 If you want to express that the computer is working on
4409 something (performing a specific task, not starting or
4410 stopping a program), we use an ``ellipsis'', namely
4411 three dots `...'. Note that we don't insert spaces in
4412 front of or behind the dots. If the task has been
4413 completed we write `done.' and a line feed.</p></item>
4418 Design your messages as if the computer is telling you
4419 what he is doing (let him be polite :-) but don't
4420 mention ``him'' directly. For example, if you think
4423 I'm starting network daemons: nfsd mountd.
4427 Starting network daemons: nfsd mountd.
4428 </example></p></item>
4432 The following formats should be used</p>
4437 <p>when daemons get started.</p>
4440 Use this format if your script starts one or more
4441 daemons. The output should look like this (a single
4442 line, no leading spaces):
4444 Starting <description>: <daemon-1> <daemon-2> <...> <daemon-n>.
4446 The <description> should describe the subsystem
4447 the daemon or set of daemons are part of, while
4448 <daemon-1> up to <daemon-n> denote each
4449 daemon's name (typically the file name of the
4453 For example, the output of /etc/init.d/lpd would look like:
4455 Starting printer spooler: lpd.
4459 This can be achieved by saying
4461 echo -n "Starting printer spooler: lpd"
4462 start-stop-daemon --start --quiet lpd
4465 in the script. If you have more than one daemon to
4466 start, you should do the following:
4468 echo -n "Starting remote file system services:"
4469 echo -n " nfsd"; start-stop-daemon --start --quiet nfsd
4470 echo -n " mountd"; start-stop-daemon --start --quiet mountd
4471 echo -n " ugidd"; start-stop-daemon --start --quiet ugidd
4474 This makes it possible for the user to see what takes
4475 so long and when the final daemon has been
4476 started. You should be careful where to put spaces: In the
4477 example above the system administrator can easily
4478 comment out a line if he don't wants to start a
4479 specific daemon, while the displayed message still
4480 looks good.</p></item>
4484 <p>when something needs to be configured.</p>
4487 If you have to set up different parameters of the
4488 system upon boot up, you should use this format:
4490 Setting <parameter> to `<value>'.
4494 You can use the following echo statement to get the quotes right:
4496 echo "Setting DNS domainname to \`"value"'."
4500 Note that the left quotation mark (`) is different
4501 from the right (').</p></item>
4504 <p>when a daemon is stopped.</p>
4507 When you stop a daemon you should issue a message
4508 similar to the startup message, except that `Starting'
4509 is replaced with `Stopping'.</p>
4512 So stopping the printer daemon will like like this:
4514 Stopping printer spooler: lpd.
4515 </example></p></item>
4518 <p>when something is executed.</p>
4521 There are several examples where you have to run a
4522 program at system startup or shutdown to perform a
4523 specific task. For example, setting the system's clock
4524 via `netdate' or killing all processes when the system
4525 comes down. Your message should like this:
4527 Doing something very useful...done.
4529 You should print the `done.' right after the job has been completed,
4530 so that the user gets informed why he has to wait. You can get this
4533 echo -n "Doing something very useful..."
4537 in your script.</p></item>
4540 <p>when the configuration is reloaded.</p>
4543 When a daemon is forced to reload its configuration
4544 files you should use the following format:
4546 Reloading <daemon's-name> configuration...done.
4547 </example></p></item>
4550 <p>when none of the above rules apply.</p>
4553 If you have to print a message that doesn't fit into
4554 the styles described above, you can use something
4555 appropriate, but please have a look at the overall
4556 rules listed above.</p></item>
4561 <heading>Menus</heading>
4564 Menu entries should follow the current menu policy as
4565 defined in the file <ftpsite>ftp.debian.org</ftpsite> in
4566 <ftppath>/debian/doc/package-developer/menu-policy.text.gz</ftppath>
4567 or your local mirror. In addition, it is included in the
4568 <tt>debian-policy</tt> package.
4572 The Debian <tt>menu</tt> packages provides a unique
4573 interface between packages providing applications and
4574 documents, and <em>menu programs</em> (either X window
4575 managers or text-based menu programs as
4576 <prgn>pdmenu</prgn>).</p>
4579 All packages that provide applications that need not be
4580 passed any special command line arguments for normal
4581 operation should register a menu entry for those
4582 applications, so that users of the <tt>menu</tt> package
4583 will automatically get menu entries in their window
4584 managers, as well in shells like <tt>pdmenu</tt>.</p>
4587 Please refer to the <em>Debian Menu System</em> document
4588 that comes with the <tt>menu</tt> package for information
4589 about how to register your applications and web
4595 <heading>Multimedia handlers</heading>
4598 Packages which provide the ability to view/show/play,
4599 compose, edit or print MIME types should register themselves
4600 as such following the current MIME support policy as defined
4601 in the file found on <ftpsite>ftp.debian.org</ftpsite> in
4602 <ftppath>/debian/doc/package-developer/mime-policy.text.gz</ftppath>
4603 or your local mirror. In addition, it is included in the
4604 <tt>debian-policy</tt> package.
4608 MIME (Multipurpose Internet Mail Extensions, RFC 1521) is a
4609 mechanism for encoding files and data streams and providing
4610 meta-information about them, in particular their type (e.g.
4611 audio or video) and format (e.g. PNG, HTML, MP3).
4615 Registration of MIME type handlers allows programs like mail
4616 user agents and web browsers to to invoke these handlers to
4617 view, edit or display MIME types they don't support
4623 <heading>Keyboard configuration</heading>
4626 To achieve a consistent keyboard configuration (i.e., all
4627 applications interpret a keyboard event the same way) all
4628 programs in the Debian distribution must be configured to
4629 comply with the following guidelines.</p>
4632 Here is a list that contains certain keys and their interpretation:
4635 <tag><tt><--</tt></tag>
4636 <item><p>delete the character to the left of the cursor</p></item>
4638 <tag><tt>Delete</tt></tag>
4639 <item><p>delete the character to the right of the cursor</p></item>
4641 <tag><tt>Control+H</tt></tag>
4642 <item><p>emacs: the help prefix</p></item>
4645 The interpretation of any keyboard events should be independent
4646 of the terminal that's used, be it a virtual console, an X
4647 terminal emulator, an rlogin/telnet session, etc.</p>
4650 The following list explains how the different programs
4651 should be set up to achieve this:</p>
4654 <list compact="compact">
4655 <item><p>`<tt><--</tt>' generates KB_Backspace in
4658 <item><p>`<tt>Delete</tt>' generates KB_Delete in X.</p></item>
4662 X translations are set up to make KB_Backspace
4663 generate ASCII DEL, and to make KB_Delete generate
4664 <tt>ESC [ 3 ~</tt> (this is the vt220 escape code for
4665 the `delete character' key). This must be done by
4666 loading the resources using xrdb on all local X
4667 displays, not using the application defaults, so that
4668 the translation resources used correspond to the
4669 xmodmap settings.</p></item>
4673 The Linux console is configured to make
4674 `<tt><--</tt>' generate DEL, and `Delete' generate
4675 <tt>ESC [ 3 ~</tt> (this is the case at the
4679 X applications are configured so that Backspace
4680 deletes left, and Delete deletes right. Motif
4681 applications already work like this.</p></item>
4683 <item><p>stty erase <tt>^?</tt> .</p></item>
4686 The `xterm' terminfo entry should have <tt>ESC [ 3
4687 ~</tt> for kdch1, just like TERM=linux and
4688 TERM=vt220.</p></item>
4691 Emacs is programmed to map KB_Backspace or the `stty
4692 erase' character to delete-backward-char, and
4693 KB_Delete or kdch1 to delete-forward-char, and
4694 <tt>^H</tt> to help as always.</p></item>
4697 Other applications use the `stty erase' character and
4698 kdch1 for the two delete keys, with ASCII DEL being
4699 `delete previous character' and kdch1 being `delete
4700 character under cursor'.</p></item>
4704 This will solve the problem except for:</p>
4707 <list compact="compact">
4709 Some terminals have a <tt><--</tt> key that cannot
4710 be made to produce anything except <tt>^H</tt>. On
4711 these terminals Emacs help will be unavailable on
4712 <tt>^H</tt> (assuming that the `stty erase' character
4713 takes precedence in Emacs, and has been set
4714 correctly). M-x help or F1 (if available) can be used
4718 Some operating systems use <tt>^H</tt> for stty erase.
4719 However, modern telnet versions and all rlogin
4720 versions propagate stty settings, and almost all UNIX
4721 versions honour stty erase. Where the stty settings
4722 are not propagated correctly things can be made to
4723 work by using stty manually.</p></item>
4726 Some systems (including previous Debian versions) use
4727 xmodmap to arrange for both <tt><--</tt> and Delete
4728 to generate KB_Delete. We can change the behavior
4729 of their X clients via the same X resources that we
4730 use to do it for our own, or have our clients be
4731 configured via their resources when things are the
4732 other way around. On displays configured like this
4733 Delete will not work, but <tt><--</tt>
4737 Some operating systems have different kdch1 settings
4738 in their terminfo for xterm and others. On these
4739 systems the Delete key will not work correctly when
4740 you log in from a system conforming to our policy, but
4741 <tt><--</tt> will.</p></item>
4748 <heading>Environment variables</heading>
4751 A program must not depend on environment variables to get
4752 reasonable defaults. (That's because these environment
4753 variables would have to be set in a system-wide
4754 configuration file like /etc/profile, which is not supported
4758 If a program usually depends on environment variables for its
4759 configuration, the program should be changed to fall back to
4760 a reasonable default configuration if these environment
4761 variables are not present. If this cannot be done easily
4762 (e.g., if the source code of a non-free program is not
4763 available), the program must be replaced by a small
4764 `wrapper' shell script which sets the environment variables
4765 if they are not already defined, and calls the original program.</p>
4768 Here is an example of a wrapper script for this purpose:
4772 BAR=${BAR:-/var/lib/fubar}
4774 exec /usr/lib/foo/foo "$@"
4778 Furthermore, as <tt>/etc/profile</tt> is a configuration
4779 file of the <prgn>base-files</prgn> package, other packages must not
4780 put any environment variables or other commands into that
4785 <heading>Files</heading>
4789 <heading>Binaries</heading>
4792 Two different packages must not install programs with
4793 different functionality but with the same filenames. (The
4794 case of two programs having the same functionality but
4795 different implementations is handled via `alternatives.')
4796 If this case happens, one of the programs must be
4797 renamed. The maintainers should report this to the
4798 developers' mailing and try to find a consensus about
4799 which package will have to be renamed. If a consensus can
4800 not be reached, <em>both</em> programs must be
4804 Generally the following compilation parameters should be used:
4807 CFLAGS = -O2 -Wall # sane warning options vary between programs
4809 install -s # (or use strip on the files in debian/tmp)
4813 Note that by default all installed binaries should be stripped,
4814 either by using the <tt>-s</tt> flag to
4815 <prgn>install</prgn>, or by calling <prgn>strip</prgn> on
4816 the binaries after they have been copied into
4817 <tt>debian/tmp</tt> but before the tree is made into a
4821 The <tt>-N</tt> flag should not be used. On a.out systems
4822 it may have been useful for some very small binaries, but
4823 for ELF it has no good effect.</p>
4826 Debugging symbols are useful for error diagnosis,
4827 investigation of core dumps (which may be submitted by users
4828 in bug reports), or testing and developing the
4829 software. Therefore it is recommended to support building
4830 the package with debugging information through the following
4831 interface: If the environment variable
4832 <tt>DEB_BUILD_OPTIONS</tt> contains the string
4833 <tt>debug</tt>, compile the software with debugging
4834 information (usually this involves adding the <tt>-g</tt>
4835 flag to <tt>CFLAGS</tt>). This allows the generation of a
4836 build tree with debugging information. If the environment
4837 variable <tt>DEB_BUILD_OPTIONS</tt> contains the string
4838 <tt>nostrip</tt>, do not strip the files at installation
4839 time. This allows one to generate a package with debugging
4840 information included. The following makefile snippet is only
4841 an example of how one may test for either condition:
4844 Rationale: Building by default with -g causes more
4845 wasted CPU cycles since the information is stripped away
4846 anyway. The package can by default build without -g if
4847 it also provides a mechanism to easily be rebuilt with
4848 debugging information. This can be done by providing a
4849 "build-debug" make target, or allowing the user to
4850 specify "DEB_BUILD_OPTIONS=debug" in the environment while
4851 compiling that package.
4853 <p>Now this has several added benefits:
4857 It is actually easier to build debugging bins and
4858 libraries this way (no more editing debian/rules
4859 or similar) since it provides a documented way of
4860 getting this type of build.</p>
4864 There will be much less wasted CPU time for the
4865 autobuilders since not having debugging
4866 information (and hence also not having to strip
4867 it) will increase the speed of compiles. This
4868 skips an entire pass of the compiler.
4879 INSTALL_FILE = $(INSTALL) -p -o root -g root -m 644
4880 INSTALL_PROGRAM = $(INSTALL) -p -o root -g root -m 755
4881 INSTALL_SCRIPT = $(INSTALL) -p -o root -g root -m 755
4882 INSTALL_DIR = $(INSTALL) -p -d -o root -g root -m 755
4884 ifneq (,$(findstring debug,$(DEB_BUILD_OPTIONS)))
4887 ifeq (,$(findstring nostrip,$(DEB_BUILD_OPTIONS)))
4888 INSTALL_PROGRAM += -s
4892 Please note that the above example is merely informative,
4893 and is not a policy mandate. You may have to massage this
4894 example in order to make it work for your package.
4899 It is up to the package maintainer to decide what
4900 compilation options are best for the package. Certain
4901 binaries (such as computationally-intensive programs) will
4902 function better with certain flags (<tt>-O3</tt>, for
4903 example); feel free to use them. Please use good judgment
4904 here. Don't use flags for the sake of it; only use them
4905 if there is good reason to do so. Feel free to override
4906 the upstream author's ideas about which compilation
4907 options are best--they are often inappropriate for our
4908 environment.</p></sect>
4912 <heading>Libraries</heading>
4915 All libraries must have a shared version in the lib
4916 package and a static version in the lib-dev package. The
4917 shared version must be compiled with <tt>-fPIC</tt>, and
4918 the static version must not be. In other words, each
4919 <tt>*.c</tt> file will need to be compiled twice.</p>
4922 You must specify the gcc option <tt>-D_REENTRANT</tt>
4923 when building a library (either static or shared) to make
4924 the library compatible with LinuxThreads.</p>
4927 Note that all installed shared libraries should be
4930 strip --strip-unneeded <your-lib>
4932 (The option `--strip-unneeded' makes <tt>strip</tt> remove
4933 only the symbols which aren't needed for relocation
4934 processing.) Shared libraries can function perfectly well
4935 when stripped, since the symbols for dynamic linking are
4936 in a separate part of the ELF object file.</p>
4939 Note that under some circumstances it may be useful to
4940 install a shared library unstripped, for example when
4941 building a separate package to support debugging.
4945 An ever increasing number of packages are using libtool to
4946 do their linking. The latest GNU libtools (>= 1.3a) can take
4947 advantage of the metadata in the installed libtool archive
4948 files (`*.la'). The main advantage of libtool's .la files is
4949 that it allows libtool to store and subsequently access
4950 metadata with respect to the libraries it builds. libtool
4951 will search for those files, which contain a lot of useful
4952 information about a library (e.g. dependency libraries for
4953 static linking). Also, they're <em>essential</em> for
4954 programs using libltdl.
4958 Certainly libtool is fully capable of linking against shared
4959 libraries which don't have .la files, but being a mere shell
4960 script it can add considerably to the build time of a
4961 libtool using package if that shell-script has to derive all
4962 this information from first principles for each library every
4963 time it is linked. With the advent of libtool-1.4 (and to a
4964 lesser extent libtool-1.3), the .la files will also store
4965 information about inter-library dependencies which cannot
4966 necessarily be derived after the .la file is deleted.
4970 Packages that use libtool to create shared libraries should
4971 include the <em>.la</em> files in the <em>-dev</em>
4972 packages, with the exception that if the package relies on
4973 libtool's <em>libltdl</em> library, in which case the .la
4974 files must go in the run-time library package. This is a
4975 good idea in general, and especially for static linking
4980 You must make sure that you use only released versions of
4981 shared libraries to build your packages; otherwise other
4982 users will not be able to run your binaries
4983 properly. Producing source packages that depend on
4984 unreleased compilers is also usually a bad
4991 <heading>Shared libraries</heading>
4994 Packages involving shared libraries should be split up
4995 into several binary packages.</p>
4998 For a straightforward library which has a development
4999 environment and a runtime kit including just shared
5000 libraries you need to create two packages:
5001 <tt><var>libraryname</var><var>soname</var></tt>
5002 (<var>soname</var> is the shared object name of the shared
5003 library--it's the thing that has to match exactly between
5004 building an executable and running it for the dynamic
5005 linker to be able run the program; usually the
5006 <var>soname</var> is the major number of the library) and
5007 <tt><var>libraryname</var><var>soname</var>-dev</tt>.</p>
5010 If you prefer only to support one development version at a
5011 time you may name the development package
5012 <tt><var>libraryname</var>-dev</tt>; otherwise you may
5013 wish to use <prgn>dpkg</prgn>'s conflicts mechanism to
5014 ensure that the user only installs one development version
5015 at a time (after all, different development versions are
5016 likely to have the same header files in them, causing a
5017 filename clash if both are installed). Typically the
5018 development version should also have an exact version
5019 dependency on the runtime library, to make sure that
5020 compilation and linking happens correctly.</p>
5023 Packages which use the shared library should have a
5024 dependency on the name of the shared library package,
5025 <tt><var>libraryname</var><var>soname</var></tt>. When
5026 the <var>soname</var> changes you can have both versions
5027 of the library installed while moving from the old library
5031 If your package has some run-time support programs which
5032 use the shared library you must not put them in
5033 the shared library package. If you do that then you won't
5034 be able to install several versions of the shared library
5035 without getting filename clashes. Instead, either create
5036 a third package for the runtime binaries (this package
5037 might typically be named
5038 <tt><var>libraryname</var>-runtime</tt>--note the absence
5039 of the <var>soname</var> in the package name) or if the
5040 development package is small include them in there.</p>
5043 If you have several shared libraries built from the same
5044 source tree you may lump them all together into a single
5045 shared library package, provided that you change all their
5046 <var>soname</var>s at once (so that you don't get filename
5047 clashes if you try to install different versions of the
5048 combined shared libraries package).</p>
5051 You should follow the directions in the <em>Debian Packaging
5052 Manual</em> for putting the shared library in its package,
5053 and you must include a <tt>shlibs</tt> control area
5054 file with details of the dependencies for packages which
5055 use the library.</p>
5058 Shared libraries should not be installed
5059 executable, since <prgn>ld.so</prgn> does not require this
5060 and trying to execute a shared library results in a core
5065 <heading>Scripts</heading>
5068 All command scripts, including the package maintainer
5069 scripts inside the package and used by <prgn>dpkg</prgn>,
5070 should have a <tt>#!</tt> line naming the shell to be used
5071 to interpret them.</p>
5074 In the case of Perl scripts this should be
5075 <tt>#!/usr/bin/perl</tt>.</p>
5078 Shell scripts (<prgn>sh</prgn> and <prgn>bash</prgn>)
5079 should almost certainly start with <tt>set -e</tt> so that
5080 errors are detected. Every script should use
5081 <tt>set -e</tt> or check the exit status of <em>every</em>
5085 The standard shell interpreter `<tt>/bin/sh</tt>' can be a
5086 symbolic link to any POSIX compatible shell, if <tt>echo
5087 -n</tt> does not generate a newline.
5090 Debian policy specifies POSIX behavior for /bin/sh, but
5091 echo -n has widespread use in the Linux community
5092 (including especially debian policy, the linux kernel
5093 source, many debian scripts, etc.). This echo -n
5094 mechanism is valid but not required under POSIX, hence
5095 this explicit addition. Also, rumour has it that this
5096 shall be mandated under the LSB anyway.
5100 specifying `<tt>/bin/sh</tt>' as interpreter should only
5101 use POSIX features. If a script requires non-POSIX
5102 features from the shell interpreter, the appropriate shell
5103 must be specified in the first line of the script (e.g.,
5104 `<tt>#!/bin/bash</tt>') and the package must depend on the
5105 package providing the shell (unless the shell package is
5106 marked `Essential', e.g., in the case of
5111 You may wish to restrict your script to POSIX features when possible so
5112 that it may use <tt>/bin/sh</tt> as its interpreter. If
5113 your script works with <prgn>ash</prgn>, it's probably
5114 POSIX compliant, but if you are in doubt, use
5115 <tt>/bin/bash</tt>.</p>
5118 Perl scripts should check for errors when making any
5119 system calls, including <tt>open</tt>, <tt>print</tt>,
5120 <tt>close</tt>, <tt>rename</tt> and <tt>system</tt>.</p>
5123 <prgn>csh</prgn> and <prgn>tcsh</prgn> should be avoided
5124 as scripting languages. See <em>Csh Programming
5125 Considered Harmful</em>, one of the <tt>comp.unix.*</tt>
5126 FAQs. It can be found on
5127 <url id="http://language.perl.com/versus/csh.whynot">, or
5128 <url id="http://www.cpan.org/doc/FMTEYEWTK/versus/csh.whynot">
5129 or even on <ftpsite>ftp.cpan.org</ftpsite>
5130 <ftppath>/pub/perl/CPAN/doc/FMTEYEWTK/versus/csh.whynot</ftppath>.
5131 If an upstream package comes with <prgn>csh</prgn> scripts
5132 then you must make sure that they start with
5133 <tt>#!/bin/csh</tt> and make your package depend on the
5134 <prgn>c-shell</prgn> virtual package.</p>
5137 Any scripts which create files in world-writeable
5138 directories (e.g., in <tt>/tmp</tt>) must use a
5139 mechanism which will fail if a file with the same name
5143 The Debian base distribution provides the
5144 <prgn>tempfile</prgn> and <prgn>mktemp</prgn> utilities
5145 for use by scripts for this purpose.</p></sect>
5149 <heading>Symbolic links</heading>
5152 In general, symbolic links within a top-level directory
5153 should be relative, and symbolic links pointing from one
5154 top-level directory into another should be absolute. (A
5155 top-level directory is a sub-directory of the root
5159 In addition, symbolic links should be specified as short
5160 as possible, i.e., link targets like `foo/../bar' are
5164 Note that when creating a relative link using
5165 <prgn>ln</prgn> it is not necessary for the target of the
5166 link to exist relative to the working directory you're
5167 running <prgn>ln</prgn> from; nor is it necessary to
5168 change directory to the directory where the link is to be
5169 made. Simply include the string that should appear as the
5170 target of the link (this will be a pathname relative to
5171 the directory in which the link resides) as the first
5172 argument to <prgn>ln</prgn>.</p>
5175 For example, in your <prgn>Makefile</prgn> or
5176 <tt>debian/rules</tt>, do things like:
5178 ln -fs gcc $(prefix)/bin/cc
5179 ln -fs gcc debian/tmp/usr/bin/cc
5180 ln -fs ../sbin/sendmail $(prefix)/bin/runq
5181 ln -fs ../sbin/sendmail debian/tmp/usr/bin/runq
5185 A symbolic link pointing to a compressed file should
5186 always have the same file extension as the referenced
5187 file. (For example, if a file `<tt>foo.gz</tt>' is
5188 referenced by a symbolic link, the filename of the link
5189 has to end with `<tt>.gz</tt>' too, as in
5190 `bar.gz.')</p></sect>
5194 <heading>Device files</heading>
5197 Packages must not include device files in the package file
5201 If a package needs any special device files that are not
5202 included in the base system, it must call
5203 <prgn>MAKEDEV</prgn> in the <tt>postinst</tt> script,
5204 after asking the user for permission to do so.</p>
5207 Packages must not remove any device files in the
5208 <tt>postrm</tt> or any other script. This is left to the
5209 system administrator.</p>
5212 Debian uses the serial devices
5213 <tt>/dev/ttyS*</tt>. Programs using the old
5214 <tt>/dev/cu*</tt> devices should be changed to use
5215 <tt>/dev/ttyS*</tt>.</p>
5218 <sect id="config files">
5219 <heading>Configuration files</heading>
5221 <heading>Definitions</heading>
5224 <tag>configuration file</tag>
5226 A file that affects the operation of program, or
5227 provides site- or host-specific information, or
5228 otherwise customizes the behavior of program.
5229 Typically, configuration files are intended to be
5230 modified by the system administrator (if needed or
5231 desired) to conform to local policy or provide more
5232 useful site-specific behavior.</p>
5235 <tag><tt>conffile</tt></tag>
5237 A file listed in a package's <tt>conffiles</tt>
5238 file, and is treated specially by <prgn>dpkg</prgn>
5239 (see the <em>Debian Packaging Manual</em>).</p>
5245 The distinction between these two is important; they are
5246 not interchangeable concepts. Almost all
5247 <tt>conffiles</tt> are configuration files, but many
5248 configuration files are not <tt>conffiles</tt>.</p>
5251 Note that a script that embeds configuration information
5252 (such as most of the files in <tt>/etc/init.d</tt> and
5253 <tt>/etc/cron.{daily,weekly,monthly}</tt>) is de-facto a
5254 configuration file and should be treated as such.</p>
5258 <heading>Location</heading>
5260 Any configuration files created or used by your package
5261 must reside in <tt>/etc</tt>. If there are several you
5262 should consider creating a subdirectory of <tt>/etc</tt>
5263 named after your package.</p>
5266 If your package creates or uses configuration files
5267 outside of <tt>/etc</tt>, and it is not feasible to modify
5268 the package to use the <tt>/etc</tt>, you should still put
5269 the files in <tt>/etc</tt> and create symbolic links to
5270 those files from the location that the package
5275 <heading>Behavior</heading>
5277 Configuration file handling must conform to the following
5281 <p>local changes must be preserved during a package
5285 <p>configuration files must be preserved when the
5286 package is removed, and only deleted when the
5287 package is purged.</p>
5292 The easy way to achieve this behavior is to make the
5293 configuration file a <tt>conffile</tt>. This is
5294 appropriate only if it is possible to distribute a default
5295 version that will work for most installations, although
5296 some system administrators may choose to modify it. This
5297 implies that the default version will be part of the
5298 package distribution, and must not be modified by the
5299 maintainer scripts during installation (or at any other
5304 In order to ensure that local changes are preserved
5305 correctly, no package may contain or make hard links to
5309 Rationale: There are two problems with hard links.
5310 The first is that some editors break the link while
5311 editing one of the files, so that the two files may
5312 unwittingly become different. The second is that
5313 <prgn>dpkg</prgn> might break the hard link while
5314 upgrading <tt>conffile</tt>s.
5319 The other way to do it is via the maintainer scripts.
5320 In this case, the configuration file must not be listed as
5321 a <tt>conffile</tt> and must not be part of the package
5322 distribution. If the existence of a file is required for
5323 the package to be sensibly configured it is the
5324 responsibility of the package maintainer to write scripts
5325 which correctly create, update, maintain and
5326 remove-on-purge the file. These scripts must be idempotent
5327 (i.e., must work correctly if <prgn>dpkg</prgn> needs to
5328 re-run them due to errors during installation or removal),
5329 must cope with all the variety of ways <prgn>dpkg</prgn>
5330 can call maintainer scripts, must not overwrite or
5331 otherwise mangle the user's configuration without asking,
5332 must not ask unnecessary questions (particularly during
5333 upgrades), and otherwise be good citizens.</p>
5336 The scripts are not required to configure every possible option for
5337 the package, but only those necessary to get the package
5338 running on a given system. Ideally the sysadmin should not
5339 have to do any configuration other than that done
5340 (semi-)automatically by the <tt>postinst</tt> script.</p>
5343 A common practice is to create a script called
5344 <tt><var>package</var>-configure</tt> and have the
5345 package's <tt>postinst</tt> call it if and only if the
5346 configuration file does not already exist. In certain
5347 cases it is useful for there to be an example or template
5348 file which the maintainer scripts use. Such files should
5349 be in <tt>/usr/share/doc</tt> if they are examples or
5350 <tt>/usr/lib</tt> if they are templates, and should be
5351 perfectly ordinary <prgn>dpkg</prgn>-handled files
5352 (<em>not</em> <tt>conffiles</tt>).</p>
5355 These two styles of configuration file handling must
5356 not be mixed, for that way lies madness:
5357 <prgn>dpkg</prgn> will ask about overwriting the file
5358 every time the package is upgraded.</p>
5363 <heading>Sharing configuration files</heading>
5365 Packages which specify the same file as
5366 `<tt>conffile</tt>' must be tagged as <em>conflicting</em>
5371 The maintainer scripts must not alter the conffile of
5372 <em>any</em> package, including the one the scripts belong
5376 If two or more packages use the same configuration file
5377 and it is reasonable for both to be installed at the same
5378 time, one of these packages must be defined as
5379 <em>owner</em> of the configuration file, i.e., it will be
5380 the package to list that distributes the file and lists it
5381 as a <tt>conffile</tt>. Other packages that use the
5382 configuration file must depend on the owning package if
5383 they require the configuration file to operate. If the
5384 other package will use the configuration file if present,
5385 but is capable of operating without it, no dependency need
5389 If it is desirable for two or more related packages to
5390 share a configuration file <em>and</em> for all of the
5391 related packages to be able to modify that configuration
5392 file, then the following should be done:
5396 have one of the related packages (the "core"
5397 package) manage the configuration file with
5398 maintainer scripts as described in the previous
5402 the core package should also provide a program that
5403 the other packages may use to modify the
5404 configuration file.</p>
5408 the related packages must use the provided program
5409 to make any modifications to the configuration file.
5410 They should either depend on the core package to
5411 guarantee that the configuration modifier program is
5412 available or accept gracefully that they cannot
5413 modify the configuration file if it is not.</p>
5418 Sometimes it's appropriate to create a new package which
5419 provides the basic infrastructure for the other packages
5420 and which manages the shared configuration files. (Check
5421 out the <tt>sgml-base</tt> package as an example.)</p>
5425 <heading>User configuration files ("dotfiles")</heading>
5428 Files in <tt>/etc/skel</tt> will automatically be copied
5429 into new user accounts by <prgn>adduser</prgn>. They
5430 should not be referenced there by any program.</p>
5433 Therefore, if a program needs a dotfile to exist in
5434 advance in <tt>$HOME</tt> to work sensibly, that dotfile
5435 should be installed in <tt>/etc/skel</tt> (and listed in
5436 conffiles, if it is not generated and modified dynamically
5437 by the package's installation scripts).</p>
5440 However, programs that require dotfiles in order to
5441 operate sensibly (dotfiles that they do not create
5442 themselves automatically, that is) are a bad thing, and
5443 programs should be configured by the Debian default
5444 installation as close to normal as possible.</p>
5447 Therefore, if a program in a Debian package needs to be
5448 configured in some way in order to operate sensibly that
5449 configuration should be done in a site-wide global
5450 configuration file elsewhere in <tt>/etc</tt>. Only if the
5451 program doesn't support a site-wide default configuration
5452 and the package maintainer doesn't have time to add it
5453 may a default per-user file be placed in
5454 <tt>/etc/skel</tt>.</p>
5457 <tt>/etc/skel</tt> should be as empty as we can make it.
5458 This is particularly true because there is no easy
5459 mechanism for ensuring that the appropriate dotfiles are
5460 copied into the accounts of existing users when a package
5466 <heading>Log files</heading>
5468 The traditional approach to log files has been to set up ad
5469 hoc log rotation schemes using simple shell scripts and
5470 cron. While this approach is highly customizable, it
5471 requires quite a lot of sysadmin work. Even though the
5472 original Debian system helped a little by automatically
5473 installing a system which can be used as a template, this
5474 was deemed not enough.
5478 A better scheme is to use logrotate, a GPL'd program
5479 developed by Red Hat, which centralizes log management. It
5480 has both a configuration file (<tt>/etc/logrotate.conf</tt>)
5481 and a directory where packages can drop logrotation info
5482 (<tt>/etc/logrotate.d</tt>).
5486 Log files should usually be named
5487 <tt>/var/log/<var>package</var>.log</tt>. If you have many
5488 log files, or need a separate directory for permissions
5489 reasons (<tt>/var/log</tt> is writable only by
5490 <tt>root</tt>), you should usually create a directory named
5491 <tt>/var/log/<var>package</var></tt>.</p>
5494 Log files must be rotated occasionally so
5495 that they don't grow indefinitely; the best way to do this
5496 is to drop a script into the directory
5497 <tt>/etc/logrotate.d</tt> and use the facilities provided by
5498 logrotate. Here is a good example for a logrotate config
5499 file (for more information see <manref name="logrotate"
5507 /etc/init.d/foo force-reload
5511 Which rotates all files under `/var/log/foo', saves 12
5512 compressed generations, and sends a HUP signal at the end of
5518 Log files should be removed when the package is
5519 purged (but not when it is only removed), by checking the
5520 argument to the <tt>postrm</tt> script (see the <em>Debian
5521 Packaging Manual</em> for details).</p>
5526 <heading>Permissions and owners</heading>
5529 The rules in this section are guidelines for general use.
5530 If necessary you may deviate from the details below.
5531 However, if you do so you must make sure that what is done
5532 is secure and you should try to be as consistent as possible
5533 with the rest of the system. You should probably also
5534 discuss it on <prgn>debian-devel</prgn> first.</p>
5537 Files should be owned by <tt>root.root</tt>, and made
5538 writable only by the owner and universally readable (and
5539 executable, if appropriate).</p>
5542 Directories should be mode 755 or (for group-writability)
5543 mode 2775. The ownership of the directory should be
5544 consistent with its mode--if a directory is mode 2775, it
5545 should be owned by the group that needs write access to
5549 Setuid and setgid executables should be mode 4755 or 2755
5550 respectively, and owned by the appropriate user or group.
5551 They should not be made unreadable (modes like 4711 or
5552 2711 or even 4111); doing so achieves no extra security,
5553 because anyone can find the binary in the freely available
5554 Debian package--it is merely inconvenient. For the same
5555 reason you should not restrict read or execute permissions
5556 on non-set-id executables.</p>
5559 Some setuid programs need to be restricted to particular
5560 sets of users, using file permissions. In this case they
5561 should be owned by the uid to which they are set-id, and
5562 by the group which should be allowed to execute them.
5563 They should have mode 4754; there is no point in making
5564 them unreadable to those users who must not be allowed to
5568 You must not arrange that the system administrator can only
5569 reconfigure the package to correspond to their local
5570 security policy by changing the permissions on a binary.
5571 Ordinary files installed by <prgn>dpkg</prgn> (as opposed
5572 to conffiles and other similar objects) have their
5573 permissions reset to the distributed permissions when the
5574 package is reinstalled. Instead you should consider (for
5575 example) creating a group for people allowed to use the
5576 program(s) and making any setuid executables executable
5577 only by that group.</p>
5580 If you need to create a new user or group for your package
5581 there are two possibilities. Firstly, you may need to
5582 make some files in the binary package be owned by this
5583 user or group, or you may need to compile the user or
5584 group id (rather than just the name) into the binary
5585 (though this latter should be avoided if possible, as in
5586 this case you need a statically allocated id).</p>
5589 If you need a statically allocated id, you must ask for a
5590 user or group id from the base system
5591 maintainer, and must not release the package until you
5592 have been allocated one. Once you have been allocated one
5593 you must make the package depend on a version of the base
5594 system with the id present in <tt>/etc/passwd</tt> or
5595 <tt>/etc/group</tt>, or alternatively arrange for your
5596 package to create the user or group itself with the
5597 correct id (using <tt>adduser</tt>) in its pre- or
5598 post-installation script (the latter is to be preferred if
5599 it is possible).</p>
5602 On the other hand, the program might be able to determine the
5603 uid or gid from the group name at runtime, so that a
5604 dynamic id can be used. In this case you should choose an
5605 appropriate user or group name, discussing this on
5606 <prgn>debian-devel</prgn> and checking with the base
5607 system maintainer that it is unique and that they do not
5608 wish you to use a statically allocated id instead. When
5609 this has been checked you must arrange for your package to
5610 create the user or group if necessary using
5611 <prgn>adduser</prgn> in the pre- or post-installation
5612 script (again, the latter is to be preferred if it is
5616 Note that changing the numeric value of an id associated with a name
5617 is very difficult, and involves searching the file system for all
5618 appropriate files. You need to think carefully whether a static or
5619 dynamic id is required, since changing your mind later will cause
5625 <heading>Customized programs</heading>
5627 <sect id="arch-spec">
5628 <heading>Architecture specification strings</heading>
5631 If a program needs to specify an <em>architecture specification
5632 string</em> in some place, the following format should be used:
5634 <arch>-<os>
5636 where `<arch>' is one of the following: i386, alpha, arm, m68k,
5637 powerpc, sparc and `<os>' is one of: linux, gnu. Use
5638 of <em>gnu</em> in this string is reserved for the GNU/Hurd
5639 operating system.</p>
5641 Note, that we don't want to use `<arch>-debian-linux'
5642 to apply to the rule `architecture-vendor-os' since this
5643 would make our programs incompatible to other Linux
5644 distributions. Also note, that we don't use
5645 `<arch>-unknown-linux', since the `unknown' does not
5646 look very good.</p></sect>
5650 <heading>Daemons</heading>
5653 The configuration files <tt>/etc/services</tt>,
5654 <tt>/etc/protocols</tt>, and <tt>/etc/rpc</tt> are managed
5655 by the <prgn>netbase</prgn> package and may not be modified
5656 by other packages.</p>
5659 If a package requires a new entry in one of these files, the
5660 maintainer should get in contact with the
5661 <prgn>netbase</prgn> maintainer, who will add the entries
5662 and release a new version of the <prgn>netbase</prgn>
5666 The configuration file <tt>/etc/inetd.conf</tt> must not be
5667 modified by the package's scripts except via the
5668 <prgn>update-inetd</prgn> script or the
5669 <prgn>DebianNet.pm</prgn> Perl module.</p>
5672 If a package wants to install an example entry into
5673 <tt>/etc/inetd.conf</tt>, the entry must be preceded with
5674 exactly one hash character (<tt>#</tt>). Such lines are
5675 treated as `commented out by user' by the
5676 <prgn>update-inetd</prgn> script and are not changed or
5677 activated during a package updates.</p></sect>
5681 <heading>Using pseudo-ttys and modifying wtmp, utmp and lastlog</heading>
5684 Some programs need to create pseudo-ttys. This should be done
5685 using Unix98 ptys if the C library supports it. The resulting
5686 program must not be installed setuid root, unless that
5687 is required for other functionality.
5691 The files <tt>/var/run/utmp</tt>, <tt>/var/log/wtmp</tt> and
5692 <tt>/var/log/lastlog</tt> must be installed writeable by
5693 group utmp. Programs who need to modify those files must
5694 be installed setgid utmp.
5699 <heading>Editors and pagers</heading>
5702 Some programs have the ability to launch an editor or pager
5703 program to edit or display a text document. Since there are
5704 lots of different editors and pagers available in the Debian
5705 distribution, the system administrator and each user should
5706 have the possibility to choose his/her preferred editor and
5710 In addition, every program should choose a good default
5711 editor/pager if none is selected by the user or system
5715 Thus, every program that launches an editor or pager must
5716 use the EDITOR or PAGER environment variables to determine
5717 the editor/pager the user wants to get started. If these
5718 variables are not set, the programs <tt>/usr/bin/editor</tt>
5719 and <tt>/usr/bin/pager</tt> should be used, respectively.</p>
5722 These two files are managed through `alternatives.' That is,
5723 every package providing an editor or pager must call the
5724 <prgn>update-alternatives</prgn> script to register these
5728 If it is very hard to adapt a program to make us of the
5729 EDITOR and PAGER variables, that program may be configured
5730 to use <tt>/usr/bin/sensible-editor</tt> and
5731 <tt>/usr/bin/sensible-pager</tt> as editor or pager program,
5732 respectively. These are two scripts provided in the Debian
5733 base system that check the EDITOR and PAGER variables and
5734 launch the appropriate program or fall back to
5735 <tt>/usr/bin/editor</tt> and <tt>/usr/bin/pager</tt>,
5739 A program may also use the VISUAL environment variable to
5740 determine the user's choice of editor. If it exists, it
5741 should take precedence over EDITOR. This is in fact what
5742 <tt>/usr/bin/sensible-editor</tt> does.</p>
5745 It is not required for a package to depend on
5746 `editor' and `pager', nor is it required for a package to
5747 provide such virtual packages.
5750 The Debian base system already provides an editor and
5759 <sect id="web-appl">
5760 <heading>Web servers and applications</heading>
5763 This section describes the locations and URLs that should
5764 be used by all web servers and web application in the Debian
5770 <p>Cgi-bin executable files are installed in the
5773 /usr/lib/cgi-bin/<cgi-bin-name>
5775 and should be referred to as
5777 http://localhost/cgi-bin/<cgi-bin-name>
5778 </example></p></item>
5781 <item><p>Access to html documents</p>
5784 Html documents for a package are stored in
5785 <tt>/usr/share/doc/<var>package</var></tt> but should
5786 be accessed via symlinks as
5787 <tt>/usr/doc/<var>package</var></tt><footnote> for
5788 backward compatibility, see <ref id="usrdoc"></footnote>
5789 and can be referred to as
5791 http://localhost/doc/<package>/<filename>
5792 </example></p></item>
5795 <item><p>Web Document Root</p>
5798 Web Applications should try to avoid storing files in
5799 the Web Document Root. Instead they should use the
5800 /usr/share/doc/<package> directory for documents and
5801 register the Web Application via the menu package. If
5802 access to the web-root is unavoidable then use
5806 as the Document Root. This might be just a
5807 symbolic link to the location where the sysadmin has
5808 put the real document root.</p>
5811 </enumlist></p></sect>
5815 <heading>Mail transport, delivery and user agents</heading>
5818 Debian packages which process electronic mail, whether
5819 mail-user-agents (MUAs) or mail-transport-agents (MTAs),
5820 must make sure that they are compatible with the
5821 configuration decisions below. Failure to do this may
5822 result in lost mail, broken <tt>From:</tt> lines, and other
5823 serious brain damage!</p>
5826 The mail spool is <tt>/var/spool/mail</tt> and the interface
5827 to send a mail message is <tt>/usr/sbin/sendmail</tt> (as
5828 per the FHS). The mail spool is part of the base system
5829 and not part of the MTA package.</p>
5832 All Debian MUAs, MTAs, MDAs and other mailbox accessing
5833 programs (like IMAP daemons) must lock the mailbox in an
5834 NFS-safe way. This means that <tt>fcntl()</tt> locking must
5835 be combined with dot locking. To avoid deadlocks, a
5836 program should use <tt>fcntl()</tt> first and dot locking
5837 after this or alternatively implement the two locking
5838 methods in a non blocking way<footnote>
5840 If it is not possible to establish both locks, the
5841 system shouldn't wait for the second lock to be
5842 established, but remove the first lock, wait a (random)
5843 time, and start over locking again.</p>
5844 </footnote>. Using the functions <tt>maillock</tt> and
5845 <tt>mailunlock</tt> provided by the
5846 <tt>liblockfile*</tt><footnote>
5848 <tt>liblockfile</tt> version >>1.01</p>
5849 </footnote> packages is the recommended way to realize this.
5853 Mailboxes are generally 660 <tt><var>user</var>.mail</tt>
5854 unless the user has chosen otherwise. A MUA may remove a
5855 mailbox (unless it has nonstandard permissions) in which
5856 case the MTA or another MUA must recreate it if needed.
5857 Mailboxes must be writable by group mail.</p>
5860 The mail spool is 2775 <tt>root.mail</tt>, and MUAs should
5861 be setgid mail to do the locking mentioned above (and
5862 must obviously avoid accessing other users' mailboxes
5863 using this privilege).</p>
5866 <tt>/etc/aliases</tt> is the source file for the system mail
5867 aliases (e.g., postmaster, usenet, etc.)--it is the one
5868 which the sysadmin and <tt>postinst</tt> scripts may edit.
5869 After <tt>/etc/aliases</tt> is edited the program or human
5870 editing it must call <prgn>newaliases</prgn>. All MTA
5871 packages must come with a <prgn>newaliases</prgn> program,
5872 even if it does nothing, but older MTA packages do not do
5873 this so programs should not fail if <prgn>newaliases</prgn>
5874 cannot be found.</p>
5877 The convention of writing <tt>forward to
5878 <var>address</var></tt> in the mailbox itself is not
5879 supported. Use a <tt>.forward</tt> file instead.</p>
5882 The <prgn>rmail</prgn> program used by UUCP
5883 for incoming mail should be <tt>/usr/sbin/rmail</tt>.
5884 Likewise, <prgn>rsmtp</prgn>, for receiving
5885 batch-SMTP-over-UUCP, should be <tt>/usr/sbin/rsmtp</tt> if it
5889 If you need to know what name to use (for example) on
5890 outgoing news and mail messages which are generated locally,
5891 you should use the file <tt>/etc/mailname</tt>. It will
5892 contain the portion after the username and <tt>@</tt> (at)
5893 sign for email addresses of users on the machine (followed
5897 A package should check for the existence of this file. If
5898 it exists it should use it without comment. (An MTA's
5899 prompting configuration script may wish to prompt the user
5900 even if it finds this file exists.) If it does not exist it
5901 should prompt the user for the value and store it in
5902 <tt>/etc/mailname</tt> as well as using it in the package's
5903 configuration. The prompt should make it clear that the
5904 name will not just be used by that package. For example, in
5905 this situation the INN package says:
5907 Please enter the `mail name' of your system. This is the
5908 hostname portion of the address to be shown on outgoing
5909 news and mail messages. The default is
5910 <var>syshostname</var>, your system's host name. Mail
5911 name [`<var>syshostname</var>']:
5913 where <var>syshostname</var> is the output of <tt>hostname
5914 --fqdn</tt>.</p></sect>
5918 <heading>News system configuration</heading>
5921 All the configuration files related to the NNTP (news)
5922 servers and clients should be located under
5923 <tt>/etc/news</tt>.</p>
5926 There are some configuration issues that apply to a number
5927 of news clients and server packages on the machine. These
5931 <tag>/etc/news/organization</tag>
5932 <item><p>A string which should appear as the
5933 organization header for all messages posted
5934 by NNTP clients on the machine</p></item>
5936 <tag>/etc/news/server</tag>
5937 <item><p>Contains the FQDN of the upstream NNTP
5938 server, or localhost if the local machine is
5939 an NNTP server.</p></item>
5942 Other global files may be added as required for cross-package news
5943 configuration.</p></sect>
5947 <heading>Programs for the X Window System</heading>
5950 <em>Programs that may be configured with support for the X Window
5951 System</em> must be configured to do so and must declare any
5952 package dependencies necessary to satisfy their runtime
5953 requirements when using the X Window System, unless the package
5954 in question is of standard or higher priority, in which case
5955 X-specific binaries may be split into a separate package, or
5956 alternative versions of the package with X support may be
5962 <em>Packages which provide an X server</em> that, directly or
5963 indirectly, communicates with real input and display hardware
5964 should declare in their control data that they provide the
5965 virtual package <tt>xserver</tt>.
5968 This implements current practice, and provides an actual
5969 policy for usage of the "xserver" virtual package which
5970 appears in the virtual packages list. In a nutshell, X
5971 servers that interface directly with the display and input
5972 hardware or via another subsystem (e.g., GGI) should provide
5973 xserver. Things like Xvfb, Xnest, and Xprt should not.
5979 <em>Packages that provide a terminal emulator</em> for the X
5980 Window System which support a terminal type with a terminfo
5981 description provided in the <tt>ncurses-base</tt> package
5982 should declare in their control data that they provide the
5983 virtual package <tt>x-terminal-emulator</tt>. They should
5984 also register themselves as an alternative for
5985 <tt>/usr/bin/x-terminal-emulator</tt>, with a priority of
5990 <em>Packages that provide window managers</em> should declare in
5991 their control data that they provide the virtual package
5992 <tt>x-window-manager</tt>. They should also register themselves as an
5993 alternative for <tt>/usr/bin/x-window-manager</tt>, with a priority
5994 calculated as follows:
5996 <item>Start with a priority of 20.</item>
5997 <item>If the window manager supports the Debian menu system,
5998 add 20 points if this support is available in the
5999 package's default configuration (i.e., no
6000 configuration files belonging to the system or user
6001 have to be edited to activate the feature); if
6002 configuration files must be modified, add only 10
6004 <item>If the window manager permits the X session to be
6005 restarted using a <em>different</em> window manager
6006 (without killing the X server) in its default
6007 configuration, add 10 points; otherwise add
6013 <em>Packages that provide fonts for the X Window System</em>
6014 must do a number of things to ensure that they are both
6015 available without modification of the X or font server
6016 configuration, and that they do not corrupt files used by
6017 other font packages to register information about themselves.
6020 Fonts of any type supported by the X Window System
6021 should be be in a separate binary package from any
6022 executables, libraries, or documentation (except that
6023 specific to the fonts shipped); if a program or
6024 library is <em>unusable</em> without one or more
6025 specific fonts, the package containing the program or
6026 library should declare a dependency on the package(s)
6027 containing the font(s) it requires.
6030 BDF fonts should be converted to PCF fonts with the
6031 <tt>bdftopcf</tt> utility (available in the
6032 <tt>xutils</tt> package, <tt>gzip</tt>ped, and
6033 placed in a directory that corresponds to their
6037 100 dpi fonts should be placed in
6038 <tt>/usr/X11R6/lib/X11/fonts/100dpi/</tt>.
6041 75 dpi fonts should be placed in
6042 <tt>/usr/X11R6/lib/X11/fonts/75dpi/</tt>.
6045 Character-cell fonts, cursor fonts, and other
6046 low-resolution fonts should be placed in
6047 <tt>/usr/X11R6/lib/X11/fonts/misc/</tt>.
6052 Speedo fonts should be placed in
6053 <tt>/usr/X11R6/lib/X11/fonts/Speedo/</tt>.
6056 Type 1 fonts should be placed in
6057 <tt>/usr/X11R6/lib/X11/fonts/Type1/</tt>. If font
6058 metric files are available, they may be placed here as
6062 Subdirectories of <tt>/usr/X11R6/lib/X11/fonts/</tt>
6063 other than those listed above should be neither created nor
6064 used. (The <tt>PEX</tt> and <tt>cyrillic</tt> directories are
6065 excepted for historical reasons, but installation of files into
6066 these directories remains discouraged.)
6069 Font packages may, instead of placing files directly in
6070 the X font directories listed above, provide symbolic links in
6071 the font directory which point to the files' actual location
6072 in the filesystem. Such a location should comply with the
6076 Font packages should not contain both 75dpi and 100dpi
6077 versions of a font. If both are available, they should be
6078 provided in separate binary packages with "-75dpi" or "-100dpi"
6079 appended to the names of the packages containing the
6080 corresponding fonts.
6083 Fonts destined for the <tt>misc</tt> subdirectory should
6084 not be included in the same package as 75dpi or 100dpi fonts;
6085 instead, they should be provided in a separate package with
6086 "-misc" appended to its name.
6089 Font packages <em>must not</em> provide the files
6090 <tt>fonts.dir</tt>, <tt>fonts.alias</tt>, or
6091 <tt>fonts.scale</tt> in a font directory.
6094 <tt>fonts.dir</tt> files must not be provided at
6098 <tt>fonts.alias</tt> and <tt>fonts.scale</tt>
6099 files, if needed, should be provided in the
6101 <tt>/etc/X11/fonts/<em>fontdir</em>/<em>package</em>.<em>extension</em></tt>,
6102 where <em>fontdir</em> is the name of the
6104 <tt>/usr/X11R6/lib/X11/fonts/</tt> where the
6105 package's corresponding fonts are stored (e.g.,
6106 <tt>75dpi</tt> or <tt>misc</tt>),
6107 <em>package</em> is the name of the package that
6108 provides these fonts, and <em>extension</em> is
6109 either <tt>scale</tt> or <tt>alias</tt>,
6110 whichever corresponds to the file
6116 Font packages must declare a dependency on
6117 <tt>xutils</tt> and, in the package
6118 post-installation and post-removal scripts, invoke the
6119 <tt>mkfontdir</tt> command on each directory into
6120 which they installed fonts.
6123 Font packages that provide one or more
6124 <tt>fonts.scale</tt> files as described above must declare a
6125 versioned dependency on <tt>xutils (>=
6126 4.0.2)</tt> and invoke <tt>update-fonts-scale</tt> on each
6127 directory into which they installed fonts
6128 <em>before</em> invoking <tt>mkfontdir</tt> on that
6129 directory. This invocation must occur in both the
6130 post-installation and post-removal scripts.
6133 Font packages that provide one or more
6134 <tt>fonts.alias</tt> files as described above must
6135 declare a versioned dependency on <tt>xutils
6136 (>= 4.0.2)</tt> and, in the package
6137 post-installation and post-removal scripts, invoke
6138 <tt>update-fonts-alias</tt> on each directory into
6139 which they installed fonts.
6142 Font packages must not provide alias names for the
6143 fonts they include which collide with alias names already in
6144 use by fonts already packaged.
6147 Font packages must not provide fonts with the same XLFD
6148 registry name as another font already packaged.
6154 <em>Application defaults</em> files must be installed in the
6155 directory <tt>/usr/X11R6/lib/X11/app-defaults/</tt>.
6157 <p>Note: This shall change very shortly.</p>
6159 They should not be registered as <em>conffile</em>s or
6160 otherwise treated as configuration files. Customization of
6161 programs' X resources may be supported with the provision of
6162 a file with the same name as that of the package placed in
6163 the <tt>/etc/X11/Xresources/</tt> directory, which must
6164 registered as a <em>conffile</em>. <em>Important:</em>
6165 packages that install files into the
6166 <tt>/etc/X11/Xresources/</tt> directory <em>must</em>
6167 declare a conflict with <tt>xbase (<<
6168 3.3.2.3a-2)</tt>; if this is not done it is possible for the
6169 installing package to destroy a previously-existing
6170 <tt>/etc/X11/Xresources</tt> <em>file</em> which had been
6171 customized by the system administrator.
6173 <p>Rationale: clarifies the language to properly
6174 address the package maintainer, not the system
6175 administrator, as to how to manage
6176 /etc/X11/Xresources.</p>
6182 <em>Packages using the X Window System should abide by the FHS
6183 standard whenever possible</em>; they should install binaries,
6184 libraries, manual pages, and other files in FHS-mandated
6185 locations wherever possible. This means that files must
6186 not be installed into <tt>/usr/X11R6/bin/</tt>,
6187 <tt>/usr/X11R6/lib/</tt>, or <tt>/usr/X11R6/man/</tt> unless
6188 this is necessary for the package to operate properly.
6189 Configuration files for window managers and display managers
6190 should be placed in a subdirectory of <tt>/etc/X11/</tt>
6191 corresponding to the package name due to these programs'
6192 tight integration with the mechanisms of the X Window
6193 System. Application-level programs should use the
6194 <tt>/etc/</tt> directory unless otherwise mandated by
6195 policy. The installation of files into subdirectories of
6196 <tt>/usr/X11R6/include/X11/</tt> and
6197 <tt>/usr/X11R6/lib/X11/</tt> is permitted but discouraged;
6198 package maintainers should determine if subdirectories of
6199 <tt>/usr/lib/</tt> and <tt>/usr/share/</tt> can be used
6200 instead (symlinks from the X11R6 directories to
6201 FHS-compliant locations is encouraged if the program is not
6202 easily configured to look elsewhere for its files).
6203 Packages must not provide -- or install files into -- the
6204 directories <tt>/usr/bin/X11/</tt>,
6205 <tt>/usr/include/X11/</tt>, or <tt>/usr/lib/X11/</tt>.
6206 Files within a package should, however, make reference to
6207 these directories, rather than their X11R6-named
6208 counterparts <tt>/usr/X11R6/bin/</tt>,
6209 <tt>/usr/X11R6/include/X11/</tt>, and
6210 <tt>/usr/X11R6/lib/X11/</tt>, if the resources being
6211 referred to have not been moved to FHS-compliant locations.
6215 <em>Programs that require the non-DFSG-compliant OSF/Motif
6216 library</em> should be compiled against and tested with
6217 LessTif (a free re-implementation of Motif) instead. If the
6218 maintainer judges that the program or programs do not work
6219 sufficiently well with LessTif to be distributed and
6220 supported, but do so when compiled against Motif, then two
6221 versions of the package should be created; one linked
6222 statically against Motif and with <tt>-smotif</tt> appended
6223 to the package name, and one linked dynamically against
6224 Motif and with <tt>-dmotif</tt> appended to the package
6225 name. Both Motif-linked versions are dependent upon
6226 non-DFSG-compliant software and thus cannot be uploaded to
6227 the main distribution; if the software is itself
6228 DFSG-compliant it may be uploaded to the contrib
6229 distribution. While known existing versions of OSF/Motif
6230 permit unlimited redistribution of binaries linked against
6231 the library (whether statically or dynamically), it is the
6232 package maintainer's responsibility to determine whether
6233 this is permitted by the license of the copy of OSF/Motif in
6234 his or her possession.
6240 <heading>Emacs lisp programs</heading>
6243 Please refer to the `Debian Emacs Policy' (documented in
6244 <tt>debian-emacs-policy.gz</tt> of the
6245 <prgn>emacsen-common</prgn> package) for details of how to
6246 package emacs lisp programs.</p></sect>
6250 <heading>Games</heading>
6253 The permissions on /var/games are 755
6254 <tt>root.root</tt>.</p>
6257 Each game decides on its own security policy.</p>
6260 Games which require protected, privileged access to
6261 high-score files, savegames, etc., may be made
6262 set-<em>group</em>-id (mode 2755) and owned by
6263 <tt>root.games</tt>, and use files and directories with
6264 appropriate permissions (770 <tt>root.games</tt>, for
6265 example). They must not be made
6266 set-<em>user</em>-id, as this causes security problems. (If
6267 an attacker can subvert any set-user-id game they can
6268 overwrite the executable of any other, causing other players
6269 of these games to run a Trojan horse program. With a
6270 set-group-id game the attacker only gets access to less
6271 important game data, and if they can get at the other
6272 players' accounts at all it will take considerably more
6276 Some packages, for example some fortune cookie programs, are
6277 configured by the upstream authors to install with their
6278 data files or other static information made unreadable so
6279 that they can only be accessed through set-id programs
6280 provided. You should not do this in a Debian package: anyone can
6281 download the <tt>.deb</tt> file and read the data from it,
6282 so there is no point making the files unreadable. Not
6283 making the files unreadable also means that you don't have
6284 to make so many programs set-id, which reduces the risk of a
6288 As described in the FHS, binaries of games should be
6289 installed in the directory <tt>/usr/games</tt>. This also
6290 applies to games that use the X Window System. Manual pages
6291 for games (X and non-X games) should be installed in
6292 <tt>/usr/share/man/man6</tt>.</p>
6296 <chapt><heading>Documentation</heading>
6300 <heading>Manual pages</heading>
6303 You should install manual pages in <prgn>nroff</prgn> source
6304 form, in appropriate places under <tt>/usr/share/man</tt>. You
6305 should only use sections 1 to 9 (see the FHS for more
6306 details). You must not install a preformatted `cat
6310 Each program, utility, and function should have an
6311 associated manpage included in the same package. It is
6312 suggested that all configuration files also have a manual
6313 page included as well.
6317 If no manual page is available for a particular program,
6318 utility, function or configuration file and this is reported as a bug on
6319 debian-bugs, a symbolic link from the requested manual page
6320 to the <manref name="undocumented" section="7"> manual page
6321 may be provided. This symbolic link can be created from
6322 <tt>debian/rules</tt> like this:
6324 ln -s ../man7/undocumented.7.gz \
6325 debian/tmp/usr/share/man/man[1-9]/the_requested_manpage.[1-9].gz
6327 This manpage claims that the lack of a manpage has been
6328 reported as a bug, so you may only do this if it really has
6329 (you can report it yourself, if you like). Do not close the
6330 bug report until a proper manpage is available.</p>
6333 You may forward a complaint about a missing manpage to the
6334 upstream authors, and mark the bug as forwarded in the
6335 Debian bug tracking system. Even though the GNU Project do
6336 not in general consider the lack of a manpage to be a bug,
6337 we do--if they tell you that they don't consider it a bug
6338 you should leave the bug in our bug tracking system open
6342 Manual pages should be installed compressed using <tt>gzip
6346 If one manpage needs to be accessible via several names it
6347 is better to use a symbolic link than the <tt>.so</tt>
6348 feature, but there is no need to fiddle with the relevant
6349 parts of the upstream source to change from <tt>.so</tt> to
6350 symlinks--don't do it unless it's easy. You should not create hard
6351 links in the manual page directories, nor put
6352 absolute filenames in <tt>.so</tt> directives. The filename
6353 in a <tt>.so</tt> in a manpage should be relative to the
6354 base of the manpage tree (usually
6355 <tt>/usr/share/man</tt>).</p></sect>
6359 <heading>Info documents</heading>
6362 Info documents should be installed in <tt>/usr/share/info</tt>.
6363 They should be compressed with <tt>gzip -9</tt>.</p>
6366 Your package should call <prgn>install-info</prgn> to update the Info
6368 file, in its post-installation script:
6370 install-info --quiet --section Development Development \
6371 /usr/share/info/foobar.info
6375 It is a good idea to specify a section for the location of
6376 your program; this is done with the <tt>--section</tt>
6377 switch. To determine which section to use, you should look
6378 at <tt>/usr/share/info/dir</tt> on your system and choose the most
6379 relevant (or create a new section if none of the current
6380 sections are relevant). Note that the <tt>--section</tt>
6381 flag takes two arguments; the first is a regular expression
6382 to match (case-insensitively) against an existing section,
6383 the second is used when creating a new one.</p>
6386 You should remove the entries in the pre-removal script:
6388 install-info --quiet --remove /usr/share/info/foobar.info
6392 If <prgn>install-info</prgn> cannot find a description entry
6393 in the Info file you must supply one. See <manref
6394 name="install-info" section="8"> for details.</p>
6398 <heading>Additional documentation</heading>
6401 Any additional documentation that comes with the package may
6402 be installed at the discretion of the package maintainer.
6403 Text documentation should be installed in a directory
6404 <tt>/usr/share/doc/<var>package</var></tt>, where
6405 <var>package</var> is the name of the package, and
6406 compressed with <tt>gzip -9</tt> unless it is small.</p>
6409 If a package comes with large amounts of documentation which
6410 many users of the package will not require you should create
6411 a separate binary package to contain it, so that it does not
6412 take up disk space on the machines of users who do not need
6413 or want it installed.</p>
6416 It is often a good idea to put text information files
6417 (<tt>README</tt>s, changelogs, and so forth) that come with
6418 the source package in <tt>/usr/share/doc/<var>package</var></tt>
6419 in the binary package. However, you don't need to install
6420 the instructions for building and installing the package, of
6424 Files in <tt>/usr/share/doc</tt> should not be referenced by
6425 any program, and the system administrator should be able to
6426 delete them without causing any programs to break. Any files
6427 that are referenced by programs but are also useful as
6428 standalone documentation should be installed under
6429 <tt>/usr/share/<package$gt;/</tt> and symlinked in
6430 <tt>/usr/share/doc/<package$gt;/</tt>.
6436 <heading>Accessing the documentation</heading>
6439 Former Debian releases placed all additional documentation
6440 in <tt>/usr/doc/<var>package</var></tt>. To realize a
6442 <tt>/usr/share/doc/<var>package</var></tt>, each package
6443 must maintain a symlink <tt>/usr/doc/<var>package</var></tt>
6444 that points to the new location of its documentation in
6445 <tt>/usr/share/doc/<var>package</var></tt><footnote>These
6446 symlinks will be removed in the future, but they have to be
6447 there for compatibility reasons until all packages have
6448 moved and the policy is changed accordingly.</footnote>.
6449 The symlink must be created when the package is installed;
6450 it cannot be contained in the package itself due to problems
6451 with <prgn>dpkg</prgn>. One reasonable way to accomplish
6452 this is to put the following in the package's
6453 <prgn>postinst</prgn>:
6455 if [ "$1" = "configure" ]; then
6456 if [ -d /usr/doc -a ! -e /usr/doc/#PACKAGE# \
6457 -a -d /usr/share/doc/#PACKAGE# ]; then
6458 ln -sf ../share/doc/#PACKAGE# /usr/doc/#PACKAGE#
6462 And the following in the package's <prgn>prerm</prgn>:
6464 if [ \( "$1" = "upgrade" -o "$1" = "remove" \) \
6465 -a -L /usr/doc/#PACKAGE# ]; then
6466 rm -f /usr/doc/#PACKAGE#
6473 <heading>Preferred documentation formats</heading>
6476 The unification of Debian documentation is being carried out
6480 If your package comes with extensive documentation in a
6481 mark up format that can be converted to various other formats
6482 you should if possible ship HTML versions in a binary
6483 package, in the directory
6484 <tt>/usr/share/doc/<var>appropriate package</var></tt> or its
6487 <p>The rationale: The important thing here is that HTML
6488 docs should be available in <em>some</em> package, not
6489 necessarily in the main binary package, though. </p>
6494 Other formats such as PostScript may be provided at your
6498 <sect id="copyrightfile">
6499 <heading>Copyright information</heading>
6502 Every package must be accompanied by a verbatim copy of its
6503 copyright and distribution license in the file
6504 /usr/share/doc/<package-name>/copyright. This file must
6505 neither be compressed nor be a symbolic link.</p>
6508 In addition, the copyright file must say where the upstream
6509 sources (if any) were obtained, and should explain briefly what
6510 modifications were made in the Debian version of the package
6511 compared to the upstream one. It should name the original
6512 authors of the package and the Debian maintainer(s) who were
6513 involved with its creation.</p>
6516 A copy of the file which will be installed in
6517 <tt>/usr/share/doc/<var>package</var>/copyright</tt> should be
6518 in <tt>debian/copyright</tt>.</p>
6522 /usr/share/doc/<package-name> may be a symbolic link to a
6523 directory in /usr/share/doc only if two packages both come from
6524 the same source and the first package has a "Depends"
6525 relationship on the second. These rules are important
6526 because copyrights must be extractable by mechanical
6530 Packages distributed under the UCB BSD license, the Artistic
6531 license, the GNU GPL, and the GNU LGPL should refer to the
6532 files /usr/share/common-licenses/BSD,
6533 /usr/share/common-licenses/Artistic,
6534 /usr/share/common-licenses/GPL, and
6535 /usr/share/common-licenses/LGPL.
6538 Why "licenses" and not "copyright"? Because
6539 <tt>/usr/doc/copyright</tt> used to contain all the
6540 copyright files, plus the four common licenses GPL,
6541 LGPL, Artistic and BSD. Now individual copyright files
6542 for packages are no longer in a common directory. Once
6543 <tt>/usr/doc/copyright</tt> is almost empty it makes
6544 sense to rename "copyright" to "licenses"
6547 Why "common-licenses" and not "licenses"? Because if I
6548 put just "licenses" I'm sure I will receive a bug report
6549 saying "license foo is not included in the licenses
6550 directory. They are not all the licenses, just a few
6551 common ones. I could use /usr/share/doc/common-licenses
6552 but I think this is too long, and, after all, the GPL
6553 does not "document" anything, it is merely a license.
6559 You should not use the copyright file as a general <tt>README</tt>
6560 file. If your package has such a file it should be
6561 installed in <tt>/usr/share/doc/<var>package</var>/README</tt> or
6562 <tt>README.Debian</tt> or some other appropriate place.</p>
6566 <heading>Examples</heading>
6569 Any examples (configurations, source files, whatever),
6570 should be installed in a directory
6571 <tt>/usr/share/doc/<var>package</var>/examples</tt>. These
6572 files should not be referenced by any program--they're there
6573 for the benefit of the system administrator and users, as
6574 documentation only. Architecture-specific example files
6575 should be installed in a directory
6576 <tt>/usr/lib/<var>package</var>/examples</tt>, and files in
6577 <tt>/usr/share/doc/<var>package</var>/examples</tt> symlink
6578 to files in it. Or the latter directory may be a symlink to
6582 <sect id="instchangelog">
6583 <heading>Changelog files</heading>
6586 Packages that are not Debian-native must contain a copy of
6587 <tt>debian/changelog</tt> file from the Debian source tree
6588 in <tt>/usr/share/doc/<var>package</var></tt> as
6589 <tt>changelog.Debian.gz</tt>. If an upstream changelog is
6590 available, it should be accessible as
6591 <tt>/usr/share/doc/<var>package</var>/changelog.gz</tt> in
6592 plain text. If the upstream changelog is distributed in
6593 HTML, it should be made available in that form as
6594 <tt>/usr/share/doc/<var>package</var>/changelog.html.gz</tt>
6595 and the <tt>changelog.gz</tt> should be generated using, eg,
6596 <tt>lynx -dump -nolist</tt>. If the upstream changelog files
6597 do not already conform to this naming convention, then this
6598 may be achieved either by renaming the files, or adding a
6599 symbolic link, at the maintainer's discretion.
6602 Rationale: People should not have to look into two
6603 places for upstream changelogs merely because they are
6611 All these files should be installed compressed using <tt>gzip -9</tt>,
6612 as they will become large with time even if they start out
6617 If the package has only one changelog which is used both as
6618 the Debian changelog and the upstream one because there is
6619 no separate upstream maintainer then that changelog should
6620 usually be installed as
6621 <tt>/usr/share/doc/<var>package</var>/changelog.gz</tt>; if
6622 there is a separate upstream maintainer, but no upstream
6623 changelog, then the Debian changelog should still be called
6624 <tt>changelog.Debian.gz</tt>.</p>