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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 install
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. Most fields
1349 are dealt with elsewhere in this document and in the
1352 <sect1 id="f-Package"><heading><tt>Package</tt>
1356 The name of the binary package. Package names consist of
1357 the alphanumerics and <tt>+</tt> <tt>-</tt> <tt>.</tt>
1358 (plus, minus and full stop).
1362 They must be at least two characters long and must start
1363 with an alphanumeric character. The use of lowercase
1364 package names is strongly recommended unless the package
1365 you're building (or referring to, in other fields) is
1366 already using uppercase.</p>
1369 <sect1 id="f-Version"><heading><tt>Version</tt>
1373 This lists the source or binary package's version number -
1374 see <ref id="versions">.
1380 id="f-Standards-Version"><heading><tt>Standards-Version</tt>
1384 The most recent version of the standards (the policy
1385 manual and associated texts) with which the package
1386 complies. This is updated manually when editing the
1387 source package to conform to newer standards; it can
1388 sometimes be used to tell when a package needs attention.
1392 Its format is the same as that of a version number except
1393 that no epoch or Debian revision is allowed - see <ref
1398 <sect1 id="f-Distribution"><heading><tt>Distribution</tt>
1402 In a <tt>.changes</tt> file or parsed changelog output
1403 this contains the (space-separated) name(s) of the
1404 distribution(s) where this version of the package should
1405 be or was installed. Distribution names follow the rules
1406 for package names. (See <ref id="f-Package">).
1411 Current distribution values are:
1413 <tag><em>stable</em></tag>
1416 This is the current `released' version of Debian
1418 distribution is <em>stable</em> only major bug fixes
1419 are allowed. When changes are made to this
1420 distribution, the release number is increased
1421 (for example: 1.2r1 becomes 1.2r2 then 1.2r3, etc).
1425 <tag><em>unstable</em></tag>
1428 This distribution value refers to the
1429 <em>developmental</em> part of the Debian
1430 distribution tree. New packages, new upstream
1431 versions of packages and bug fixes go into the
1432 <em>unstable</em> directory tree. Download from
1433 this distribution at your own risk.
1437 <tag><em>frozen</em></tag>
1440 From time to time, the <em>unstable</em>
1441 distribution enters a state of `code-freeze' in
1442 anticipation of release as a <em>stable</em>
1443 version. During this period of testing only
1444 fixes for existing or newly-discovered bugs will
1449 <tag><em>experimental</em></tag>
1452 The packages with this distribution value are deemed
1453 by their maintainers to be high risk. Oftentimes they
1454 represent early beta or developmental packages from
1455 various sources that the maintainers want people to
1456 try, but are not ready to be a part of the other parts
1457 of the Debian distribution tree. Download at your own
1462 There are several sections in each
1463 distribution. Currently, these sections are:
1466 <tag><em>main</em></tag>
1469 The packages in this section are those in the
1470 main Debian distribution. They are all free
1471 (according to the Debian free software
1472 guidelines) and meet any other criteria for
1473 inclusion described in this manual.</p>
1476 <tag><em>contrib</em></tag>
1479 The packages in this section do not meet the
1480 criteria for inclusion in the main Debian
1481 distribution as defined by this manual, but are
1482 otherwise free, as defined by the Debian free
1483 software guidelines.</p>
1486 <tag><em>non-free</em></tag>
1489 Packages in <em>non-free</em> do not meet the
1490 criteria of free software, as defined by the
1491 Debian free software guidelines. Again, use your
1492 best judgment in downloading from this
1496 </taglist> You should list <em>all</em> distributions that
1497 the package should be installed into. Except in unusual
1498 circumstances, installations to <em>stable</em> should also
1499 go into <em>frozen</em> (if it exists) and
1500 <em>unstable</em>. Likewise, installations into
1501 <em>frozen</em> should also go into <em>unstable</em>.
1510 <chapt id="versions"><heading>Version numbering </heading>
1513 Every package has a version number, in its <tt>Version</tt>
1518 The package management system imposes an ordering on version
1519 numbers, so that it can tell whether packages are being up- or
1520 downgraded and so that package system front end applications
1521 can tell whether a package it finds available is newer than
1522 the one installed on the system. The version number format
1523 has the most significant parts (as far as comparison is
1524 concerned) at the beginning.
1528 The version number format is:
1529 &lsqb<var>epoch</var><tt>:</tt>]<var>upstream-version</var>[<tt>-</tt><var>debian-revision</var>]
1533 The three components here are:
1535 <tag><var>epoch</var></tag>
1539 This is a single (generally small) unsigned integer. It
1540 may be omitted, in which case zero is assumed. If it is
1541 omitted then the <var>upstream-version</var> may not
1546 It is provided to allow mistakes in the version numbers
1547 of older versions of a package, and also a package's
1548 previous version numbering schemes, to be left behind.
1553 <tag><var>upstream-version</var></tag>
1557 This is the main part of the version. It is usually the
1558 version number of the original (`upstream') package from
1559 which the <tt>.deb</tt> file has been made, if this is
1560 applicable. Usually this will be in the same format as
1561 that specified by the upstream author(s); however, it
1562 may need to be reformatted to fit into the package
1563 management system's format and comparison scheme.
1567 The comparison behavior of the package management system
1568 with respect to the <var>upstream-version</var> is
1569 described below. The <var>upstream-version</var>
1570 portion of the version number is mandatory.
1574 The <var>upstream-version</var> may contain only
1575 alphanumerics and the characters <tt>.</tt> <tt>+</tt>
1576 <tt>-</tt> <tt>:</tt> (full stop, plus, hyphen, colon)
1577 and should start with a digit. If there is no
1578 <var>debian-revision</var> then hyphens are not allowed;
1579 if there is no <var>epoch</var> then colons are not
1583 <tag><var>debian-revision</var></tag>
1587 This part of the version represents the version of the
1588 modifications that were made to the package to make it a
1589 Debian binary package. It is in the same format as the
1590 <var>upstream-version</var> and is compared in the same
1595 It is optional; if it isn't present then the
1596 <var>upstream-version</var> may not contain a hyphen.
1597 This format represents the case where a piece of
1598 software was written specifically to be turned into a
1599 Debian binary package, and so there is only one
1600 `debianization' of it and therefore no revision
1601 indication is required.
1605 It is conventional to restart the
1606 <var>debian-revision</var> at <tt>1</tt> each time the
1607 <var>upstream-version</var> is increased.
1611 The package management system will break the
1612 <var>upstream-version</var> and
1613 <var>debian-revision</var> apart at the last hyphen in
1614 the string. The absence of a <var>debian-revision</var>
1615 compares earlier than the presence of one (but note that
1616 the <var>debian-revision</var> is the least significant
1617 part of the version number).
1621 The <var>debian-revision</var> may contain only
1622 alphanumerics and the characters <tt>+</tt> and
1623 <tt>.</tt> (plus and full stop).
1627 The <var>upstream-version</var> and <var>debian-revision</var>
1628 parts are compared by the package management system using the
1633 The strings are compared from left to right.
1637 First the initial part of each string consisting entirely of
1638 non-digit characters is determined. These two parts (one of
1639 which may be empty) are compared lexically. If a difference
1640 is found it is returned. The lexical comparison is a
1641 comparison of ASCII values modified so that all the letters
1642 sort earlier than all the non-letters.
1646 Then the initial part of the remainder of each string which
1647 consists entirely of digit characters is determined. The
1648 numerical values of these two parts are compared, and any
1649 difference found is returned as the result of the comparison.
1650 For these purposes an empty string (which can only occur at
1651 the end of one or both version strings being compared) counts
1656 These two steps are repeated (chopping initial non-digit
1657 strings and initial digit strings off from the start) until a
1658 difference is found or both strings are exhausted.
1662 Note that the purpose of epochs is to allow us to leave behind
1663 mistakes in version numbering, and to cope with situations
1664 where the version numbering changes. It is <em>not</em> there
1665 to cope with version numbers containing strings of letters
1666 which the package management system cannot interpret (such as
1667 <tt>ALPHA</tt> or <tt>pre-</tt>), or with silly orderings (the
1668 author of this manual has heard of a package whose versions
1669 went <tt>1.1</tt>, <tt>1.2</tt>, <tt>1.3</tt>, <tt>1</tt>,
1670 <tt>2.1</tt>, <tt>2.2</tt>, <tt>2</tt> and so forth).
1674 If an upstream package has problematic version numbers they
1675 should be converted to a sane form for use in the
1676 <tt>Version</tt> field.
1680 <heading>Version numbers based on dates</heading>
1682 In general, Debian packages should use the same version
1683 numbers as the upstream sources.</p>
1686 However, in some cases where the upstream version number is
1687 based on a date (e.g., a development `snapshot' release) the
1688 package management system cannot handle these version
1689 numbers without epochs. For example, dpkg will consider
1690 `96May01' to be greater than `96Dec24'.</p>
1693 To prevent having to use epochs for every new upstream
1694 version, the version number should be changed to the
1695 following format in such cases: `19960501', `19961224'. It
1696 is up to the maintainer whether he/she wants to bother the
1697 upstream maintainer to change the version numbers upstream,
1701 Note, that other version formats based on dates which are
1702 parsed correctly by the package management system should
1703 <em>not</em> be changed.</p>
1706 Native Debian packages (i.e., packages which have been
1707 written especially for Debian) whose version numbers include
1708 dates should always use the `YYYYMMDD' format.</p>
1712 <chapt id="miscellaneous"><heading>Packaging Considerations</heading>
1714 <sect id="timestamps"><heading>Time Stamps</heading>
1716 Maintainers are encouraged to preserve the modification
1717 times of the upstream source files in a package, as far as
1718 is reasonably possible. Even though this is optional, this
1719 is still a good idea.
1722 The rationale is that there is some information conveyed
1723 by knowing the age of the file, for example, you could
1724 recognize that some documentation is very old by looking
1725 at the modification time, so it would be nice if the
1726 modification time of the upstream source would be
1733 <sect id="debianrules"><heading><tt>debian/rules</tt> - the
1734 main building script </heading>
1737 This file must be an executable makefile, and contains the
1738 package-specific recipes for compiling the package and
1739 building binary package(s) out of the source.
1743 It must start with the line <tt>#!/usr/bin/make -f</tt>,
1744 so that it can be invoked by saying its name rather than
1745 invoking <prgn>make</prgn> explicitly.
1749 Since an interactive <tt>debian/rules</tt> script makes it
1750 impossible to auto-compile that package and also makes it
1751 hard for other people to reproduce the same binary
1752 package, all <strong>required targets</strong> MUST be
1753 non-interactive. At a minimum, required targets are the
1754 ones called by <prgn>dpkg-buildpackage</prgn>, namely,
1755 <em>clean</em>, <em>binary</em>, <em>binary-arch</em>,
1756 <em>binary-indep</em>, and <em>build</em>. It also follows
1757 that any target that these targets depend on must also be
1762 The targets which must be present are:
1764 <tag><tt>build</tt></tag>
1767 This should perform all non-interactive
1768 configuration and compilation of the package. If a
1769 package has an interactive pre-build configuration
1770 routine, the Debianised source package should be
1771 built after this has taken place, so that it can be
1772 built without rerunning the configuration.
1776 For some packages, notably ones where the same
1777 source tree is compiled in different ways to produce
1778 two binary packages, the <prgn>build</prgn> target
1779 does not make much sense. For these packages it is
1780 good enough to provide two (or more) targets
1781 (<tt>build-a</tt> and <tt>build-b</tt> or whatever)
1782 for each of the ways of building the package, and a
1783 <prgn>build</prgn> target that does nothing. The
1784 <prgn>binary</prgn> target will have to build the
1785 package in each of the possible ways and make the
1786 binary package out of each.
1790 The <prgn>build</prgn> target must not do anything
1791 that might require root privilege.
1795 The <prgn>build</prgn> target may need to run
1796 <prgn>clean</prgn> first - see below.
1800 When a package has a configuration routine that
1801 takes a long time, or when the makefiles are poorly
1802 designed, or when <prgn>build</prgn> needs to run
1803 <prgn>clean</prgn> first, it is a good idea to
1804 <tt>touch build</tt> when the build process is
1805 complete. This will ensure that if <tt>debian/rules
1806 build</tt> is run again it will not rebuild the
1811 <tag><tt>binary</tt>, <tt>binary-arch</tt>,
1812 <tt>binary-indep</tt>
1816 The <prgn>binary</prgn> target must be all that is
1817 necessary for the user to build the binary
1818 package. All these targets are required to be
1819 non-interactive. It is split into two parts:
1820 <prgn>binary-arch</prgn> builds the packages' output
1821 files which are specific to a particular
1822 architecture, and <prgn>binary-indep</prgn> builds
1823 those which are not.
1827 <prgn>binary</prgn> may be (and commonly is) a target
1828 with no commands which simply depends on
1829 <prgn>binary-arch</prgn> and
1830 <prgn>binary-indep</prgn>.
1834 Both <prgn>binary-*</prgn> targets should depend on
1835 the <prgn>build</prgn> target, above, so that the
1836 package is built if it has not been already. It
1837 should then create the relevant binary package(s),
1838 using <prgn>dpkg-gencontrol</prgn> to make their
1839 control files and <prgn>dpkg-deb</prgn> to build
1840 them and place them in the parent of the top level
1845 If one of the <prgn>binary-*</prgn> targets has
1846 nothing to do (this will be always be the case if
1847 the source generates only a single binary package,
1848 whether architecture-dependent or not) it
1849 <em>must</em> still exist, and must always
1854 The <prgn>binary</prgn> targets must be invoked as
1859 <tag><tt>clean</tt></tag>
1863 This must undo any effects that the
1864 <prgn>build</prgn> and <prgn>binary</prgn> targets
1865 may have had, except that it should leave alone any
1866 output files created in the parent directory by a
1867 run of <prgn>binary</prgn>. This target must be
1872 If a <prgn>build</prgn> file is touched at the end
1873 of the <prgn>build</prgn> target, as suggested
1874 above, it should be removed as the first thing that
1875 <prgn>clean</prgn> does, so that running
1876 <prgn>build</prgn> again after an interrupted
1877 <prgn>clean</prgn> doesn't think that everything is
1882 The <prgn>clean</prgn> target may need to be
1883 invoked as root if <prgn>binary</prgn> has been
1884 invoked since the last <prgn>clean</prgn>, or if
1885 <prgn>build</prgn> has been invoked as root (since
1886 <prgn>build</prgn> may create directories, for
1891 <tag><tt>get-orig-source</tt> (optional)</tag>
1895 This target fetches the most recent version of the
1896 original source package from a canonical archive site
1897 (via FTP or WWW, for example), does any necessary
1898 rearrangement to turn it into the original source
1899 tar file format described below, and leaves it in the
1904 This target may be invoked in any directory, and
1905 should take care to clean up any temporary files it
1910 This target is optional, but providing it if
1911 possible is a good idea.
1917 The <prgn>build</prgn>, <prgn>binary</prgn> and
1918 <prgn>clean</prgn> targets must be invoked with a current
1919 directory of the package's top-level directory.
1924 Additional targets may exist in <tt>debian/rules</tt>,
1925 either as published or undocumented interfaces or for the
1926 package's internal use.
1930 The architecture we build on and build for is determined by
1931 make variables via dpkg-architecture. You can get the Debian
1932 architecture and the GNU style architecture specification
1933 string for the build machine as well as the host
1934 machine. Here is a list of supported make variables:
1935 <list compact="compact">
1937 <p><tt>DEB_*_ARCH</tt> (the Debian architecture)</p>
1940 <p><tt>DEB_*_GNU_TYPE</tt> (the GNU style architecture
1941 specification string)</p>
1944 <p><tt>DEB_*_GNU_CPU</tt> (the CPU part of DEB_*_GNU_TYPE)</p>
1947 <p><tt>DEB_*_GNU_SYSTEM</tt> (the System part of
1953 where <tt>*</tt> is either <tt>BUILD</tt> for specification of
1954 the build machine or <tt>HOST</tt> for specification of the machine
1959 Backward compatibility can be provided in the rules file
1960 by setting the needed variables to suitable default
1961 values, please refer to the documentation of
1962 dpkg-architecture for details.
1966 It is important to understand that the <tt>DEB_*_ARCH</tt>
1967 string only determines which Debian architecture we are
1968 building on or for. It should not be used to get the CPU
1969 or system information; the GNU style variables should be
1974 <sect id="dpkgchangelog"><heading><tt>debian/changelog</tt>
1978 This file records the changes to the Debian-specific parts of the
1982 Though there is nothing stopping an author who is also
1983 the Debian maintainer from using it for all their
1984 changes, it will have to be renamed if the Debian and
1985 upstream maintainers become different
1992 It has a special format which allows the package building
1993 tools to discover which version of the package is being
1994 built and find out other release-specific information.
1998 That format is a series of entries like this:
2000 <var>package</var> (<var>version</var>) <var>distribution(s)</var>; urgency=<var>urgency</var>
2002 * <var>change details</var>
2003 <var>more change details</var>
2004 * <var>even more change details</var>
2006 -- <var>maintainer name and email address</var> <var>date</var>
2011 <var>package</var> and <var>version</var> are the source
2012 package name and version number.
2016 <var>distribution(s)</var> lists the distributions where
2017 this version should be installed when it is uploaded - it
2018 is copied to the <tt>Distribution</tt> field in the
2019 <tt>.changes</tt> file. See <ref id="f-Distribution">.
2023 <var>urgency</var> is the value for the <tt>Urgency</tt>
2024 field in the <tt>.changes</tt> file for the upload. It is
2025 not possible to specify an urgency containing commas; commas
2026 are used to separate
2027 <tt><var>keyword</var>=<var>value</var></tt> settings in the
2028 <prgn>dpkg</prgn> changelog format (though there is
2029 currently only one useful <var>keyword</var>,
2034 The change details may in fact be any series of lines
2035 starting with at least two spaces, but conventionally each
2036 change starts with an asterisk and a separating space and
2037 continuation lines are indented so as to bring them in
2038 line with the start of the text above. Blank lines may be
2039 used here to separate groups of changes, if desired.
2043 The maintainer name and email address need <em>not</em>
2044 necessarily be those of the usual package maintainer.
2045 They should be the details of the person doing
2046 <em>this</em> version. The information here will be
2047 copied to the <tt>.changes</tt> file, and then later used
2048 to send an acknowledgement when the upload has been
2053 The <var>date</var> should be in RFC822 format
2056 This is generated by the <prgn>822-date</prgn>
2059 </footnote>; it should include the time zone specified
2060 numerically, with the time zone name or abbreviation
2061 optionally present as a comment.
2065 The first `title' line with the package name should start
2066 at the left hand margin; the `trailer' line with the
2067 maintainer and date details should be preceded by exactly
2068 one space. The maintainer details and the date must be
2069 separated by exactly two spaces.
2072 <sect1><heading>Defining alternative changelog formats</heading>
2075 It is possible to use a different format to the standard
2076 one, by providing a parser for the format you wish to
2080 A changelog parser must not interact with the user at
2086 <sect id="srcsubstvars"><heading><tt>debian/substvars</tt>
2087 and variable substitutions </heading>
2090 When <prgn>dpkg-gencontrol</prgn>,
2091 <prgn>dpkg-genchanges</prgn> and <prgn>dpkg-source</prgn>
2092 generate control files they do variable substitutions on
2093 their output just before writing it. Variable
2094 substitutions have the form
2095 <tt>${<var>variable-name</var>}</tt>. The optional file
2096 <tt>debian/substvars</tt> contains variable substitutions
2097 to be used; variables can also be set directly from
2098 <tt>debian/rules</tt> using the <tt>-V</tt> option to the
2099 source packaging commands, and certain predefined
2100 variables are available.
2104 The is usually generated and modified dynamically by
2105 <tt>debian/rules</tt> targets; in this case it must be
2106 removed by the <prgn>clean</prgn> target.
2110 See <manref name="dpkg-source" section="1"> for full
2111 details about source variable substitutions, including the
2112 format of <tt>debian/substvars</tt>.</p>
2115 <sect id="debianfiles"><heading><tt>debian/files</tt>
2119 This file is not a permanent part of the source tree; it
2120 is used while building packages to record which files are
2121 being generated. <prgn>dpkg-genchanges</prgn> uses it
2122 when it generates a <tt>.changes</tt> file.
2126 It should not exist in a shipped source package, and so it
2127 (and any backup files or temporary files such as
2131 <tt>files.new</tt> is used as a temporary file by
2132 <prgn>dpkg-gencontrol</prgn> and
2133 <prgn>dpkg-distaddfile</prgn> - they write a new
2134 version of <tt>files</tt> here before renaming it,
2135 to avoid leaving a corrupted copy if an error
2138 </footnote>) should be removed by the
2139 <prgn>clean</prgn> target. It may also be wise to
2140 ensure a fresh start by emptying or removing it at the
2141 start of the <prgn>binary</prgn> target.
2145 <prgn>dpkg-gencontrol</prgn> adds an entry to this file
2146 for the <tt>.deb</tt> file that will be created by
2147 <prgn>dpkg-deb</prgn> from the control file that it
2148 generates, so for most packages all that needs to be done
2149 with this file is to delete it in <prgn>clean</prgn>.
2153 If a package upload includes files besides the source
2154 package and any binary packages whose control files were
2155 made with <prgn>dpkg-gencontrol</prgn> then they should be
2156 placed in the parent of the package's top-level directory
2157 and <prgn>dpkg-distaddfile</prgn> should be called to add
2158 the file to the list in <tt>debian/files</tt>.</p>
2161 <sect id="restrictions"><heading>Restrictions on objects in source packages
2165 The source package may not contain any hard links
2168 This is not currently detected when building source
2169 packages, but only when extracting
2175 Hard links may be permitted at some point in the
2176 future, but would require a fair amount of
2179 </footnote>, device special files, sockets or setuid or
2183 Setgid directories are allowed.
2188 <sect id="descriptions"><heading>Descriptions of packages - the
2189 <tt>Description</tt> field </heading>
2192 The description is intended to describe the program to a user
2193 who has never met it before so that they know whether they
2194 want to install it. It should also give information about the
2195 significant dependencies and conflicts between this package
2196 and others, so that the user knows why these dependencies and
2197 conflicts have been declared.
2200 <sect1><heading>Notes about writing descriptions
2204 The single line synopsis should be kept brief - certainly
2205 under 80 characters.
2209 Do not include the package name in the synopsis line. The
2210 display software knows how to display this already, and you
2211 do not need to state it. Remember that in many situations
2212 the user may only see the synopsis line - make it as
2213 informative as you can.
2217 Do not try to continue the single line synopsis into the
2218 extended description. This will not work correctly when
2219 the full description is displayed, and makes no sense
2220 where only the summary (the single line synopsis) is
2225 The extended description should describe what the package
2226 does and how it relates to the rest of the system (in terms
2227 of, for example, which subsystem it is which part of).
2231 The description field needs to make sense to anyone, even
2232 people who have no idea about any of the things the
2236 The blurb that comes with a program in its
2237 announcements and/or <prgn>README</prgn> files is
2238 rarely suitable for use in a description. It is
2239 usually aimed at people who are already in the
2240 community where the package is used.
2246 Put important information first, both in the synopsis and
2247 extended description. Sometimes only the first part of the
2248 synopsis or of the description will be displayed. You can
2249 assume that there will usually be a way to see the whole
2250 extended description.
2254 You may include information about dependencies and so forth
2255 in the extended description, if you wish.
2259 Do not use tab characters. Their effect is not predictable.
2267 <chapt id="maintainerscripts"><heading>Package maintainer scripts
2268 and installation procedure
2271 <sect><heading>Introduction to package maintainer scripts
2275 It is possible to supply scripts as part of a package which
2276 the package management system will run for you when your
2277 package is installed, upgraded or removed.
2281 These scripts should be the files <tt>preinst</tt>,
2282 <tt>postinst</tt>, <tt>prerm</tt> and <tt>postrm</tt> in the
2283 control area of the package. They must be proper executable
2284 files; if they are scripts (which is recommended) they must
2285 start with the usual <tt>#!</tt> convention. They should be
2286 readable and executable by anyone, and not world-writable.
2290 The package management system looks at the exit status from
2291 these scripts. It is important that they exit with a
2292 non-zero status if there is an error, so that the package
2293 management system can stop its processing. For shell
2294 scripts this means that you <em>almost always</em> need to
2295 use <tt>set -e</tt> (this is usually true when writing shell
2296 scripts, in fact). It is also important, of course, that
2297 they don't exit with a non-zero status if everything went
2302 It is necessary for the error recovery procedures that the
2303 scripts be idempotent: i.e., invoking the same script several
2304 times in the same situation should do no harm. If the first
2305 call failed, or aborted half way through for some reason,
2306 the second call should merely do the things that were left
2307 undone the first time, if any, and exit with a success
2312 When a package is upgraded a combination of the scripts from
2313 the old and new packages is called in amongst the other
2314 steps of the upgrade procedure. If your scripts are going
2315 to be at all complicated you need to be aware of this, and
2316 may need to check the arguments to your scripts.
2320 Broadly speaking the <prgn>preinst</prgn> is called before
2321 (a particular version of) a package is installed, and the
2322 <prgn>postinst</prgn> afterwards; the <prgn>prerm</prgn>
2323 before (a version of) a package is removed and the
2324 <prgn>postrm</prgn> afterwards.
2327 next paragraph by Guy Maor to close bug #2481
2330 <p> Programs called from maintainer scripts should not
2331 normally have a path prepended to them. Before installation
2332 is started the package management system checks to see if
2333 the programs <prgn>ldconfig</prgn>,
2334 <prgn>start-stop-daemon</prgn>, <prgn>install-info</prgn>,
2335 and <prgn>update-rc.d</prgn> can be found via the
2336 <tt>PATH</tt> environment variable. Those programs, and any
2337 other program that one would expect to on the <tt>PATH</tt>,
2338 should thus be invoked without an absolute
2339 pathname. Maintainer scripts should also not reset the
2340 <tt>PATH</tt>, though they might choose to modify it by pre-
2341 or appending package-specific directories. These
2342 considerations really apply to all shell scripts.</p>
2345 <heading>Maintainer scripts Idempotency</heading>
2348 It is very important to make maintainer scripts
2352 That means that if it runs successfully or fails
2353 and then you call it again it doesn't bomb out,
2354 but just ensures that everything is the way it
2357 </footnote> This is so that if an error occurs, the
2358 user interrupts <prgn>dpkg</prgn> or some other
2359 unforeseen circumstance happens you don't leave the
2360 user with a badly-broken package.
2364 <heading>Controlling terminal for maintainer scripts</heading>
2367 The maintainer scripts are guaranteed to run with a
2368 controlling terminal and can interact with the user.
2369 If they need to prompt for passwords, do full-screen
2370 interaction or something similar you should do these
2371 things to and from <tt>/dev/tty</tt>, since
2372 <prgn>dpkg</prgn> will at some point redirect scripts'
2373 standard input and output so that it can log the
2374 installation process. Likewise, because these scripts
2375 may be executed with standard output redirected into a
2376 pipe for logging purposes, Perl scripts should set
2377 unbuffered output by setting <tt>$|=1</tt> so that the
2378 output is printed immediately rather than being
2383 Each script should return a zero exit status for
2384 success, or a nonzero one for failure.
2388 <sect id="mscriptsinstact"><heading>Summary of ways maintainer
2393 <list compact="compact">
2395 <p><var>new-preinst</var> <tt>install</tt></p>
2398 <p><var>new-preinst</var> <tt>install</tt>
2399 <var>old-version</var></p>
2402 <p><var>new-preinst</var> <tt>upgrade</tt>
2403 <var>old-version</var></p>
2406 <p><var>old-preinst</var> <tt>abort-upgrade</tt>
2407 <var>new-version</var>
2413 <list compact="compact">
2415 <p><var>postinst</var> <tt>configure</tt>
2416 <var>most-recently-configured-version</var></p>
2419 <p><var>old-postinst</var> <tt>abort-upgrade</tt>
2420 <var>new version</var></p>
2423 <p><var>conflictor's-postinst</var> <tt>abort-remove</tt>
2424 <tt>in-favour</tt> <var>package</var>
2425 <var>new-version</var></p>
2429 <var>deconfigured's-postinst</var>
2430 <tt>abort-deconfigure</tt> <tt>in-favour</tt>
2431 <var>failed-install-package</var> <var>version</var>
2432 <tt>removing</tt> <var>conflicting-package</var>
2439 <list compact="compact">
2441 <p><var>prerm</var> <tt>remove</tt></p>
2444 <p><var>old-prerm</var> <tt>upgrade</tt>
2445 <var>new-version</var></p>
2448 <p><var>new-prerm</var> <tt>failed-upgrade</tt>
2449 <var>old-version</var></p>
2452 <p><var>conflictor's-prerm</var> <tt>remove</tt>
2453 <tt>in-favour</tt> <var>package</var>
2454 <var>new-version</var></p>
2458 <var>deconfigured's-prerm</var> <tt>deconfigure</tt>
2459 <tt>in-favour</tt> <var>package-being-installed</var>
2460 <var>version</var> <tt>removing</tt>
2461 <var>conflicting-package</var>
2468 <list compact="compact">
2470 <p><var>postrm</var> <tt>remove</tt></p>
2473 <p><var>postrm</var> <tt>purge</tt></p>
2477 <var>old-postrm</var> <tt>upgrade</tt>
2478 <var>new-version</var></p>
2481 <p><var>new-postrm</var> <tt>failed-upgrade</tt>
2482 <var>old-version</var></p>
2485 <p><var>new-postrm</var> <tt>abort-install</tt></p>
2488 <p><var>new-postrm</var> <tt>abort-install</tt>
2489 <var>old-version</var></p>
2492 <p><var>new-postrm</var> <tt>abort-upgrade</tt>
2493 <var>old-version</var></p>
2497 <var>disappearer's-postrm</var> <tt>disappear</tt>
2498 <var>overwriter</var>
2499 <var>overwriter-version</var></p></item>
2504 <sect id="unpackphase"><heading>Details of unpack phase of
2505 installation or upgrade
2509 The procedure on installation/upgrade/overwrite/disappear
2510 (i.e., when running <tt>dpkg --unpack</tt>, or the unpack
2511 stage of <tt>dpkg --install</tt>) is as follows. In each
2512 case if an error occurs the actions are, in general, run
2513 backwards - this means that the maintainer scripts are run
2514 with different arguments in reverse order. These are the
2515 `error unwind' calls listed below.
2522 <p>If a version of the package is already
2525 <var>old-prerm</var> upgrade <var>new-version</var>
2530 If the script runs but exits with a non-zero
2531 exit status, <prgn>dpkg</prgn> will attempt:
2533 <var>new-prerm</var> failed-upgrade <var>old-version</var>
2535 Error unwind, for both the above cases:
2537 <var>old-postinst</var> abort-upgrade <var>new-version</var>
2545 <p>If a `conflicting' package is being removed at the same time:
2549 If any packages depended on that conflicting
2550 package and <tt>--auto-deconfigure</tt> is
2551 specified, call, for each such package:
2553 <var>deconfigured's-prerm</var> deconfigure \
2554 in-favour <var>package-being-installed</var> <var>version</var> \
2555 removing <var>conflicting-package</var> <var>version</var>
2559 <var>deconfigured's-postinst</var> abort-deconfigure \
2560 in-favour <var>package-being-installed-but-failed</var> <var>version</var> \
2561 removing <var>conflicting-package</var> <var>version</var>
2563 The deconfigured packages are marked as
2564 requiring configuration, so that if
2565 <tt>--install</tt> is used they will be
2566 configured again if possible.</p>
2569 <p>To prepare for removal of the conflicting package, call:
2571 <var>conflictor's-prerm</var> remove in-favour <var>package</var> <var>new-version</var>
2575 <var>conflictor's-postinst</var> abort-remove \
2576 in-favour <var>package</var> <var>new-version</var>
2587 <p>If the package is being upgraded, call:
2589 <var>new-preinst</var> upgrade <var>old-version</var>
2594 Otherwise, if the package had some configuration
2595 files from a previous version installed (i.e., it
2596 is in the `configuration files only' state):
2598 <var>new-preinst</var> install <var>old-version</var>
2602 <p>Otherwise (i.e., the package was completely purged):
2604 <var>new-preinst</var> install
2606 Error unwind versions, respectively:
2608 <var>new-postrm</var> abort-upgrade <var>old-version</var>
2609 <var>new-postrm</var> abort-install <var>old-version</var>
2610 <var>new-postrm</var> abort-install
2620 The new package's files are unpacked, overwriting any
2621 that may be on the system already, for example any
2622 from the old version of the same package or from
2623 another package (backups of the old files are left
2624 around, and if anything goes wrong the package
2625 management system will attempt to put them back as
2626 part of the error unwind).
2630 It is an error for a package to contains files which
2631 are on the system in another package, unless
2632 <tt>Replaces</tt> is used (see <ref id="replaces">).
2633 Currently the <tt>--force-overwrite</tt> flag is
2634 enabled, downgrading it to a warning, but this may not
2639 It is a more serious error for a package to contain a
2640 plain file or other kind of non-directory where another
2641 package has a directory (again, unless
2642 <tt>Replaces</tt> is used). This error can be
2643 overridden if desired using
2644 <tt>--force-overwrite-dir</tt>, but this is not
2649 Packages which overwrite each other's files produce
2650 behavior which though deterministic is hard for the
2651 system administrator to understand. It can easily
2652 lead to `missing' programs if, for example, a package
2653 is installed which overwrites a file from another
2654 package, and is then removed again.
2657 Part of the problem is due to what is arguably a
2658 bug in <prgn>dpkg</prgn>.
2664 A directory will never be replaced by a symbolic links
2665 to a directory or vice versa; instead, the existing
2666 state (symlink or not) will be left alone and
2667 <prgn>dpkg</prgn> will follow the symlink if there is
2675 <p>If the package is being upgraded, call
2677 <var>old-postrm</var> upgrade <var>new-version</var>
2681 <p>If this fails, <prgn>dpkg</prgn> will attempt:
2683 <var>new-postrm</var> failed-upgrade <var>old-version</var>
2685 Error unwind, for both cases:
2687 <var>old-preinst</var> abort-upgrade <var>new-version</var>
2693 This is the point of no return - if
2694 <prgn>dpkg</prgn> gets this far, it won't back off
2695 past this point if an error occurs. This will
2696 leave the package in a fairly bad state, which
2697 will require a successful re-installation to clear
2698 up, but it's when <prgn>dpkg</prgn> starts doing
2699 things that are irreversible.
2704 Any files which were in the old version of the package
2705 but not in the new are removed.</p>
2708 <p>The new file list replaces the old.</p>
2711 <p>The new maintainer scripts replace the old.</p>
2715 <p>Any packages all of whose files have been overwritten during the
2716 installation, and which aren't required for
2717 dependencies, are considered to have been removed.
2718 For each such package,
2721 <p><prgn>dpkg</prgn> calls:
2723 <var>disappearer's-postrm</var> disappear \
2724 <var>overwriter</var> <var>overwriter-version</var>
2729 <p>The package's maintainer scripts are removed.
2734 It is noted in the status database as being in a
2735 sane state, namely not installed (any conffiles
2736 it may have are ignored, rather than being
2737 removed by <prgn>dpkg</prgn>). Note that
2738 disappearing packages do not have their prerm
2739 called, because <prgn>dpkg</prgn> doesn't know
2740 in advance that the package is going to
2749 Any files in the package we're unpacking that are also
2750 listed in the file lists of other packages are removed
2751 from those lists. (This will lobotomize the file list
2752 of the `conflicting' package if there is one.)
2757 The backup files made during installation, above, are
2764 The new package's status is now sane, and recorded as
2765 `unpacked'. Here is another point of no return - if
2766 the conflicting package's removal fails we do not
2767 unwind the rest of the installation; the conflicting
2768 package is left in a half-removed limbo.
2773 If there was a conflicting package we go and do the
2774 removal actions (described below), starting with the
2775 removal of the conflicting package's files (any that
2776 are also in the package being installed have already
2777 been removed from the conflicting package's file list,
2778 and so do not get removed now).
2785 <sect><heading>Details of configuration</heading>
2788 When we configure a package (this happens with <tt>dpkg
2789 --install</tt>, or with <tt>--configure</tt>), we first
2790 update the conffiles and then call:
2792 <var>postinst</var> configure <var>most-recently-configured-version</var>
2797 No attempt is made to unwind after errors during
2802 If there is no most recently configured version
2803 <prgn>dpkg</prgn> will pass a null argument; older versions
2804 of dpkg may pass <tt><unknown></tt> (including the
2805 angle brackets) in this case. Even older ones do not pass a
2806 second argument at all, under any circumstances.
2810 <sect><heading>Details of removal and/or configuration purging
2818 <var>prerm</var> remove
2824 The package's files are removed (except conffiles).
2829 <var>postrm</var> remove
2833 <p>All the maintainer scripts except the postrm are removed.
2837 If we aren't purging the package we stop here. Note
2838 that packages which have no postrm and no conffiles
2839 are automatically purged when removed, as there is no
2840 difference except for the <prgn>dpkg</prgn>
2845 The conffiles and any backup files (<tt>~</tt>-files,
2846 <tt>#*#</tt> files, <tt>%</tt>-files,
2847 <tt>.dpkg-{old,new,tmp}</tt>, etc.) are removed.</p>
2851 <var>postrm</var> purge
2855 <p>The package's file list is removed.</p>
2858 No attempt is made to unwind after errors during
2864 <chapt id="relationships"><heading>Declaring relationships between
2868 Packages can declare in their control file that they have
2869 certain relationships to other packages - for example, that
2870 they may not be installed at the same time as certain other
2871 packages, and/or that they depend on the presence of others,
2872 or that they should overwrite files in certain other packages
2877 This is done using the <tt>Depends</tt>, <tt>Recommends</tt>,
2878 <tt>Suggests</tt>, <tt>Enhances</tt>, <tt>Conflicts</tt>,
2879 <tt>Provides</tt> and <tt>Replaces</tt> control file fields.
2883 Source packages may declare relationships to binary packages,
2884 saying that they require certain binary packages to be
2885 installed or absent at the time of building the package.
2889 This is done using the <tt>Build-Depends</tt>,
2890 <tt>Build-Depends-Indep</tt>, <tt>Build-Conflicts</tt>, and
2891 <tt>Build-Conflicts-Indep</tt> control file fields.
2894 <sect id="depsyntax"><heading>Syntax of relationship fields
2898 These fields all have a uniform syntax. They are a list of
2899 package names separated by commas.
2903 In the <tt>Depends</tt>, <tt>Recommends</tt>,
2904 <tt>Suggests</tt>, <tt>Pre-Depends</tt>,
2905 <tt>Build-Depends</tt> and <tt>Build-Depends-Indep</tt>
2906 control file fields of the package, which declare
2907 dependencies on other packages, the package names listed may
2908 also include lists of alternative package names, separated
2909 by vertical bar symbols <tt>|</tt> (pipe symbols). In such
2910 a case, the presence of any one of the alternative packages
2911 is installed, that part of the dependency is considered to
2916 All the fields except <tt>Provides</tt> may restrict their
2917 applicability to particular versions of each named package.
2918 This is done in parentheses after each individual package
2919 name; the parentheses should contain a relation from the
2920 list below followed by a version number, in the format
2921 described in <ref id="versions">.
2925 The relations allowed are <tt><<</tt>, <tt><=</tt>,
2926 <tt>=</tt>, <tt>>=</tt> and <tt>>></tt> for
2927 strictly earlier, earlier or equal, exactly equal, later or
2928 equal and strictly later, respectively. The forms
2929 <tt><</tt> and <tt>></tt> were used to mean
2930 earlier/later or equal, rather than strictly earlier/later,
2931 so they should not appear in new packages (though
2932 <prgn>dpkg</prgn> still supports them).
2936 Whitespace may appear at any point in the version
2937 specification, and must appear where it's necessary to
2938 disambiguate; it is not otherwise significant. For
2939 consistency and in case of future changes to
2940 <prgn>dpkg</prgn> it is recommended that a single space be
2941 used after a version relationship and before a version
2942 number; it is usual also to put a single space after each
2943 comma, on either side of each vertical bar, and before each
2952 Depends: libc5 (>= 5.2.18-4), mime-support, csh | tcsh
2957 All fields that specify build-time relationships
2958 (<tt>Build-Depends</tt>, <tt>Build-Depends-Indep</tt>,
2959 <tt>Build-Conflicts</tt> and <tt>Build-Conflicts-Indep</tt>)
2960 may be restricted to a certain set of architectures. This
2961 is done in brackets after each individual package name and
2962 the optional version specification. The brackets enclose a
2963 list of Debian architecture names separated by whitespace.
2964 An exclamation mark may be prepended to each name. If the
2965 current Debian host architecture is not in this list and
2966 there are no exclamation marks in the list, or it is in the
2967 list with a prepended exclamation mark, the package name and
2968 the associated version specification are ignored completely
2969 for the purposes of defining the relationships.
2976 Build-Depends-Indep: texinfo
2977 Build-Depends: kernel-headers-2.2.10 [!hurd-i386],
2978 hurd-dev [hurd-i386], gnumach-dev [hurd-i386]
2984 <heading>Binary Dependencies - <tt>Depends</tt>,
2985 <tt>Recommends</tt>, <tt>Suggests</tt>, <tt>Enhances</tt>,
2986 <tt>Pre-Depends</tt>
2990 These five fields are used to declare a dependency
2991 relationship by one package on another. They appear in the
2992 depending package's control file.
2996 All but <tt>Pre-Depends</tt> and <tt>Conflicts</tt>
2997 (discussed below) take effect <em>only</em> when a package
2998 is to be configured. They do not prevent a package being on
2999 the system in an unconfigured state while its dependencies
3000 are unsatisfied, and it is possible to replace a package
3001 whose dependencies are satisfied and which is properly
3002 installed with a different version whose dependencies are
3003 not and cannot be satisfied; when this is done the depending
3004 package will be left unconfigured (since attempts to
3005 configure it will give errors) and will not function
3010 For this reason packages in an installation run are usually
3011 all unpacked first and all configured later; this gives
3012 later versions of packages with dependencies on later
3013 versions of other packages the opportunity to have their
3014 dependencies satisfied.
3018 Thus <tt>Depends</tt> allows package maintainers to impose
3019 an order in which packages should be configured.
3021 <tag><tt>Depends</tt></tag>
3024 <p>This declares an absolute dependency.
3028 The <tt>Depends</tt> field should be used if the
3029 depended-on package is required for the depending
3030 package to provide a significant amount of
3034 <tag><tt>Recommends</tt></tag>
3036 <p>This declares a strong, but not absolute, dependency.
3040 The <tt>Recommends</tt> field should list packages
3041 that would be found together with this one in all but
3042 unusual installations.</p>
3045 <tag><tt>Suggests</tt></tag>
3049 This is used to declare that one package may be more
3050 useful with one or more others. Using this field
3051 tells the packaging system and the user that the
3052 listed packages are related to this one and can
3053 perhaps enhance its usefulness, but that installing
3054 this one without them is perfectly reasonable.
3058 <tag><tt>Enhances</tt></tag>
3061 This field is similar to Suggests but works in the
3062 opposite direction. It is used to declare that a
3063 package can enhance the functionality of another
3068 <tag><tt>Pre-Depends</tt></tag>
3072 This field is like <tt>Depends</tt>, except that it
3073 also forces <prgn>dpkg</prgn> to complete installation
3074 of the packages named before even starting the
3075 installation of the package which declares the
3080 <tt>Pre-Depends</tt> should be used sparingly,
3081 preferably only by packages whose premature upgrade or
3082 installation would hamper the ability of the system to
3083 continue with any upgrade that might be in progress.
3087 When the package declaring it is being configured, a
3088 <tt>Pre-Dependency</tt> will be considered satisfied
3089 only if the depending package has been correctly
3090 configured, just as if an ordinary <tt>Depends</tt>
3095 However, when a package declaring a Pre-dependency is
3096 being unpacked the predependency can be satisfied even
3097 if the depended-on package(s) are only unpacked or
3098 half-configured, provided that they have been
3099 configured correctly at some point in the past (and
3100 not removed or partially removed since). In this case
3101 both the previously-configured and currently unpacked
3102 or half-configured versions must satisfy any version
3103 clause in the <tt>Pre-Depends</tt> field.
3109 When selecting which level of dependency to use you should
3110 consider how important the depended-on package is to the
3111 functionality of the one declaring the dependency. Some
3112 packages are composed of components of varying degrees of
3113 importance. Such a package should list using
3114 <tt>Depends</tt> the package(s) which are required by the
3115 more important components. The other components'
3116 requirements may be mentioned as Suggestions or
3117 Recommendations, as appropriate to the components' relative
3122 <sect id="conflicts"><heading>Alternative binary packages -
3123 <tt>Conflicts</tt> and <tt>Replaces</tt>
3127 When one binary package declares a conflict with another
3128 <prgn>dpkg</prgn> will refuse to allow them to be installed
3129 on the system at the same time.
3133 If one package is to be installed, the other must be removed
3134 first - if the package being installed is marked as
3135 replacing (<ref id="replaces">) the one on the system, or
3136 the one on the system is marked as deselected, or both
3137 packages are marked <tt>Essential</tt>, then
3138 <prgn>dpkg</prgn> will automatically remove the package
3139 which is causing the conflict, otherwise it will halt the
3140 installation of the new package with an error. This
3141 mechanism specifically doesn't work when the installed
3142 package is <tt>Essential</tt>, but the new package is not.
3147 A package will not cause a conflict merely because its
3148 configuration files are still installed; it must be at least
3153 A special exception is made for packages which declare a
3154 conflict with their own package name, or with a virtual
3155 package which they provide (see below): this does not
3156 prevent their installation, and allows a package to conflict
3157 with others providing a replacement for it. You use this
3158 feature when you want the package in question to be the only
3159 package providing something.
3163 A <tt>Conflicts</tt> entry should almost never have an
3164 `earlier than' version clause. This would prevent
3165 <prgn>dpkg</prgn> from upgrading or installing the package
3166 which declared such a conflict until the upgrade or removal
3167 of the conflicted-with package had been completed.
3171 <sect id="virtual"><heading>Virtual packages - <tt>Provides</tt>
3175 As well as the names of actual (`concrete') packages, the
3176 package relationship fields <tt>Depends</tt>,
3177 <tt>Build-Depends</tt>, <tt>Build-Depends-Indep</tt>,
3178 <tt>Recommends</tt>, <tt>Suggests</tt>, <tt>Conflicts</tt>,
3179 <tt>Build-Conflicts</tt> and <tt>Build-Conflicts-Indep</tt> may
3180 mention virtual packages.
3184 A virtual package is one which appears in the
3185 <tt>Provides</tt> control file field of another package.
3186 The effect is as if the package(s) which provide a
3187 particular virtual package name had been listed by name
3188 everywhere the virtual package name appears.
3192 If there are both a real and a virtual package of the same
3193 name then the dependency may be satisfied (or the conflict
3194 caused) by either the real package or any of the virtual
3195 packages which provide it. This is so that, for example,
3201 and someone else releases an xemacs package they can say
3205 </example> and all will work in the interim (until a purely
3206 virtual package name is decided on and the <tt>emacs</tt>
3207 and <tt>vm</tt> packages are changed to use it).
3211 If a dependency or a conflict has a version number attached
3212 then only real packages will be considered to see whether
3213 the relationship is satisfied (or the prohibition violated,
3214 for a conflict) - it is assumed that a real package which
3215 provides the virtual package is not of the `right' version.
3216 So, a <tt>Provides</tt> field may not contain version
3217 numbers, and the version number of the concrete package
3218 which provides a particular virtual package will not be
3219 looked at when considering a dependency on or conflict with
3220 the virtual package name.
3224 It is likely that the ability will be added in a future
3225 release of <prgn>dpkg</prgn> to specify a version number for
3226 each virtual package it provides. This feature is not yet
3227 present, however, and is expected to be used only
3232 If you want to specify which of a set of real packages should be the
3233 default to satisfy a particular dependency on a virtual package, you
3234 should list the real package as an alternative before the virtual.
3239 <sect id="replaces"><heading><tt>Replaces</tt> - overwriting
3240 files and replacing packages
3244 The <tt>Replaces</tt> control file field has two purposes,
3245 which come into play in different situations.
3249 Virtual packages (<ref id="virtual">) are not considered
3250 when looking at a <tt>Replaces</tt> field - the packages
3251 declared as being replaced must be mentioned by their real
3255 <sect1><heading>Overwriting files in other packages
3259 Firstly, as mentioned before, it is usually an error for a
3260 package to contain files which are on the system in
3261 another package, though currently the
3262 <tt>--force-overwrite</tt> flag is enabled by default,
3263 downgrading the error to a warning,
3267 If the overwriting package declares that it replaces the
3268 one containing the file being overwritten then
3269 <prgn>dpkg</prgn> will proceed, and replace the file from
3270 the old package with that from the new. The file will no
3271 longer be listed as `owned' by the old package.
3275 If a package is completely replaced in this way, so that
3276 <prgn>dpkg</prgn> does not know of any files it still
3277 contains, it is considered to have disappeared. It will
3278 be marked as not wanted on the system (selected for
3279 removal) and not installed. Any conffiles details noted
3280 in the package will be ignored, as they will have been
3281 taken over by the replacing package(s). The package's
3282 <prgn>postrm</prgn> script will be run to allow the
3283 package to do any final cleanup required. See <ref
3284 id="mscriptsinstact">.
3288 In the future <prgn>dpkg</prgn> will discard files which
3289 would overwrite those from an already installed package
3290 which declares that it replaces the package being
3291 installed. This is so that you can install an older
3292 version of a package without problems.
3296 This usage of <tt>Replaces</tt> only takes effect when
3297 both packages are at least partially on the system at
3298 once, so that it can only happen if they do not conflict
3299 or if the conflict has been overridden.</p>
3302 <sect1><heading>Replacing whole packages, forcing their
3307 Secondly, <tt>Replaces</tt> allows the packaging system to
3308 resolve which package should be removed when there is a
3309 conflict - see <ref id="conflicts">. This usage only
3310 takes effect when the two packages <em>do</em> conflict,
3311 so that the two effects do not interfere with each other.
3316 <sect><heading>Relationships between source and binary packages -
3317 <tt>Build-Depends</tt>, <tt>Build-Depends-Indep</tt>,
3318 <tt>Build-Conflicts</tt>, <tt>Build-Conflicts-Indep</tt>
3322 A source package may declare a dependency or a conflict on a
3323 binary package. This is done with the control file fields
3324 <tt>Build-Depends</tt>, <tt>Build-Depends-Indep</tt>,
3325 <tt>Build-Conflicts</tt>, and
3326 <tt>Build-Conflicts-Indep</tt>. Their semantics are that
3327 the dependencies and conflicts they define must be satisfied
3328 (as defined earlier for binary packages), when one of the
3329 targets in <tt>debian/rules</tt> that the particular field
3330 applies to is invoked.
3333 <tag><tt>Build-Depends</tt>, <tt>Build-Conflicts</tt></tag>
3336 The <tt>Build-Depends</tt> and
3337 <tt>Build-Conflicts</tt> fields apply to the targets
3338 <tt>build</tt>, <tt>binary</tt>, <tt>binary-arch</tt>
3339 and <tt>binary-indep</tt>.
3342 <tag><tt>Build-Depends-Indep</tt>, <tt>Build-Conflicts-Indep</tt></tag>
3345 The <tt>Build-Depends-Indep</tt> and
3346 <tt>Build-Conflicts-Indep</tt> fields apply to the
3347 targets <tt>binary</tt> and <tt>binary-indep</tt>.
3358 <chapt id="conffiles"><heading>Configuration file handling
3362 <prgn>dpkg</prgn> can do a certain amount of automatic
3363 handling of package configuration files.
3367 Whether this mechanism is appropriate depends on a number of
3368 factors, but basically there are two approaches to any
3369 particular configuration file.
3373 The easy method is to ship a best-effort configuration in the
3374 package, and use <prgn>dpkg</prgn>'s conffile mechanism to
3375 handle updates. If the user is unlikely to want to edit the
3376 file, but you need them to be able to without losing their
3377 changes, and a new package with a changed version of the file
3378 is only released infrequently, this is a good approach.
3382 The hard method is to build the configuration file from
3383 scratch in the <prgn>postinst</prgn> script, and to take the
3384 responsibility for fixing any mistakes made in earlier
3385 versions of the package automatically. This will be
3386 appropriate if the file is likely to need to be different on
3391 <chapt id="sharedlibs"><heading>Shared libraries
3395 Packages containing shared libraries must be constructed with
3396 a little care to make sure that the shared library is always
3397 available. This is especially important for packages whose
3398 shared libraries are vitally important, such as the libc.
3402 Firstly, your package should install the shared libraries
3403 under their normal names. For example, the
3404 <prgn>libgdbm1</prgn> package should install
3405 <tt>libgdbm.so.1.7.3</tt> as
3406 <tt>/usr/lib/libgdbm.so.1.7.3</tt>. The files should not be
3407 renamed or re-linked by any prerm or postrm scripts;
3408 <prgn>dpkg</prgn> will take care of renaming things safely
3409 without affecting running programs, and attempts to interfere
3410 with this are likely to lead to problems.
3414 Secondly, your package should include the symlink that
3415 <prgn>ldconfig</prgn> would create for the shared libraries.
3416 For example, the <prgn>libgdbm1</prgn> package should include
3417 a symlink from <tt>/usr/lib/libgdbm.so.1</tt> to
3418 <tt>libgdbm.so.1.7.3</tt>. This is needed so that
3419 <prgn>ld.so</prgn> can find the library in between the time
3420 <prgn>dpkg</prgn> installs it and <prgn>ldconfig</prgn> is run
3421 in the <prgn>postinst</prgn> script. Furthermore, older
3422 versions of the package management system required the library
3423 must be placed before the symlink pointing to it in the
3424 <tt>.deb</tt> file. This is so that by the time
3425 <prgn>dpkg</prgn> comes to install the symlink (overwriting
3426 the previous symlink pointing at an older version of the
3427 library) the new shared library is already in place.
3428 Unfortunately, this was not not always possible, since it
3429 highly depends on the behavior of the file system. Some
3430 file systems (such as reiserfs) will reorder the files so it
3431 doesn't matter in what order you create them. Starting with
3432 release <tt>1.7.0</tt> <prgn>dpkg</prgn> will reorder the
3433 files itself when building a package.
3437 next Paragraph added to close Bug #5299, Guy Maor
3441 Thirdly, the development package should contain a symlink for
3442 the shared library without a version number. For example, the
3443 <tt>libgdbm1-dev</tt> package should include a symlink from
3444 <tt>/usr/lib/libgdm.so</tt> to <tt>libgdm.so.1.7.3</tt>. This
3445 symlink is needed by <prgn>ld</prgn> when compiling packages
3446 as it will only look for <tt>libgdm.so</tt> and
3447 <tt>libgdm.a</tt> when compiling dynamically or statically,
3452 next paragraph changed by Christian Schwarz (see policy weekly #6)
3456 Any package installing shared libraries in a directory that's listed
3457 in <tt>/etc/ld.so.conf</tt> or in one of the default library
3458 directories of <prgn>ld.so</prgn> (currently, these are <tt>/usr/lib</tt>
3459 and <tt>/lib</tt>) must call <prgn>ldconfig</prgn> in its <prgn>postinst</prgn>
3460 script if and only if the first argument is `configure'. However, it
3461 is important not to call <prgn>ldconfig</prgn> in the postrm or preinst
3462 scripts in the case where the package is being upgraded (see <ref
3463 id="unpackphase">), as <prgn>ldconfig</prgn> will see the temporary names
3464 that <prgn>dpkg</prgn> uses for the files while it is
3465 installing them and will make the shared library links point
3466 to them, just before <prgn>dpkg</prgn> continues the
3467 installation and removes the links!
3471 moved from section 2.2 , DMorris
3474 <sect id="shlibs"><heading>The <tt>shlibs</tt> File Format
3478 This file is for use by <prgn>dpkg-shlibdeps</prgn> and is
3479 required when your package provides shared libraries.
3483 Each line is of the form:
3485 <var>library-name</var> <var>version-or-soname</var> <var>dependencies ...</var>
3490 <var>library-name</var> is the name of the shared library,
3491 for example <tt>libc5</tt>.
3495 <var>version-or-soname</var> is the soname of the library -
3496 i.e., the thing that must exactly match for the library to be
3497 recognized by <prgn>ld.so</prgn>. Usually this is the major
3498 version number of the library.
3502 <var>dependencies</var> has the same syntax as a dependency
3503 field in a binary package control file. It should give
3504 details of which package(s) are required to satisfy a binary
3505 built against the version of the library contained in the
3506 package. See <ref id="depsyntax">.
3510 For example, if the package <tt>foo</tt> contains
3511 <tt>libfoo.so.1.2.3</tt>, where the soname of the library is
3512 <tt>libfoo.so.1</tt>, and the first version of the package
3513 which contained a minor number of at least <tt>2.3</tt> was
3514 <var>1.2.3-1</var>, then the package's <var>shlibs</var>
3517 libfoo 1 foo (>= 1.2.3-1)
3522 The version-specific dependency is to avoid warnings from
3523 <prgn>ld.so</prgn> about using older shared libraries with
3527 <sect><heading>Further Technical information on
3528 <tt>shlibs</tt></heading>
3532 following section mostly provided by Heiko Schlittermann
3536 <sect1><heading><em>What</em> are the <tt>shlibs</tt> files?
3540 The <tt>debian/shlibs</tt> file provides a way of checking
3541 for shared library dependencies on packaged binaries.
3542 They are intended to be used by package maintainers to
3543 make their lives easier.
3547 Other <tt>shlibs</tt> files that exist on a Debian system are
3549 <item> <p><tt>/etc/dpkg/shlibs.default</tt></p></item>
3550 <item> <p><tt>/etc/dpkg/shlibs.override</tt></p></item>
3551 <item> <p><tt>/var/lib/dpkg/info/*.shlibs</tt></p></item>
3552 <item> <p><tt>debian/shlibs.local</tt></p></item>
3554 These files are used by <prgn>dpkg-shlibdeps</prgn> when
3555 creating a binary package.</p>
3558 <sect1><heading><em>How</em> does <prgn>dpkg-shlibdeps</prgn>
3562 <prgn>dpkg-shlibdeps</prgn>
3563 determines the shared libraries directly
3566 It used to do this by calling <prgn>ldd</prgn>, but it
3567 now calls <prgn>objdump</prgn> to to this. This
3568 requires a couple of changes in the way that packages
3572 A binary <tt>foo</tt> directly uses a library
3573 <tt>libbar</tt> if it is linked with that
3574 library. Other libraries that are needed by
3575 <tt>libbar</tt> are linked indirectly to <tt>foo</tt>,
3576 and the dynamic linker will load them automatically
3577 when it loads <tt>libbar</tt>. Running<prgn>ldd</prgn>
3578 lists all of the libraries used, both directly and
3579 indirectly; but <prgn>objdump</prgn> only lists the
3580 directly linked libraries. A package only needs to
3581 depend on the libraries it is directly linked to,
3582 since the dependencies for those libraries should
3583 automatically pull in the other libraries.
3586 This change does mean a change in the way packages are
3587 build though: currently <prgn>dpkg-shlibdeps</prgn> is
3588 only run on binaries. But since we will now rely on the
3589 libraries depending on the libraries they themselves
3590 need, the packages containing those libraries will
3591 need to run <prgn>dpkg-shlibdeps</prgn> on the
3595 A good example where this would help us is the current
3596 mess with multiple version of the <tt>mesa</tt>
3597 library. With the <prgn>ldd</prgn>-based system, every
3598 package that uses <tt>mesa</tt> needs to add a
3599 dependency on <tt>svgalib|svgalib-dummy</tt> in order
3600 to handle the glide <tt>mesa</tt> variant. With an
3601 <prgn>objdump</prgn>-based system this isn't necessary
3602 anymore and would have saved everyone a lot of work.
3605 Another example: we could update <tt>libimlib</tt>
3606 with a new version that supports a new graphics format
3607 called dgf. If we use the old <prgn>ldd</prgn> method,
3608 every package that uses <tt>libimlib</tt> would need
3609 to be recompiled so it would also depend on
3610 <tt>libdgf</tt> or it wouldn't run due to missing
3611 symbols. However with the new system, packages using
3612 <tt>libimlib</tt> can rely on <tt>libimlib</tt> itself
3613 having the dependency on <tt>libdgf</tt> and wouldn't
3617 used by the compiled binaries and libraries passed through
3618 on its command line.
3622 For each shared library linked to,
3623 <prgn>dpkg-shlibdeps</prgn> needs to know
3624 <list compact="compact">
3625 <item><p>the package containing the library, and</p></item>
3626 <item><p>the library version number,</p></item>
3628 and it scans the following files in this order:
3629 <enumlist compact="compact">
3630 <item><p><tt>debian/shlibs.local</tt></p></item>
3631 <item><p><tt>/etc/dpkg/shlibs.override</tt></p></item>
3632 <item><p><tt>/var/lib/dpkg/info/*.shlibs</tt></p></item>
3633 <item><p><tt>/etc/dpkg/shlibs.default</tt></p></item>
3638 <sect1><heading><em>Who</em> maintains the various
3639 <tt>shlibs</tt> files?
3643 <list compact="compact">
3645 <p><tt>/etc/dpkg/shlibs.default</tt> - the maintainer
3650 <tt>/var/lib/dpkg/info/<var>package</var>.shlibs</tt>
3651 - the maintainer of each package</p>
3655 <tt>/etc/dpkg/shlibs.override</tt> - the local
3656 system administrator</p>
3659 <p><tt>debian/shlibs.local</tt> - the maintainer of
3664 The <tt>shlibs.default</tt> file is managed by
3665 <prgn>dpkg</prgn>. The entries in <tt>shlibs.default</tt>
3666 that are provided by <prgn>dpkg</prgn> are just there to
3667 fix things until the shared library packages all have
3668 <tt>shlibs</tt> files.
3672 <sect1><heading><em>How</em> to use <prgn>dpkg-shlibdeps</prgn> and
3673 the <tt>shlibs</tt> files
3676 <sect2><heading>If your package doesn't provide a shared
3681 Put a call to <prgn>dpkg-shlibdeps</prgn> into your
3682 <tt>debian/rules</tt> file. If your package contains
3683 only binaries (e.g. no scripts) use:
3685 dpkg-shlibdeps debian/tmp/usr/bin/* debian/tmp/usr/sbin/*
3687 If <prgn>dpkg-shlibdeps</prgn> doesn't complain, you're
3688 done. If it does complain you might need to create your
3689 own <tt>debian/shlibs.local</tt> file.</p>
3692 <sect2><heading>If your package provides a shared library
3696 Create a <tt>debian/shlibs</tt> file and let
3697 <tt>debian/rules</tt> install it in the control area:
3699 install -m644 debian/shlibs debian/tmp/DEBIAN
3701 If your package contains additional binaries see above.
3706 <sect1><heading><em>How</em> to write
3707 <tt>debian/shlibs.local</tt>
3711 This file is intended only as a <em>temporary</em> fix if
3712 your binaries depend on a library which doesn't provide
3713 its own <tt>/var/lib/dpkg/info/*.shlibs</tt> file yet.
3717 Let's assume you are packaging a binary <tt>foo</tt>. Your
3718 output in building the package might look like this.
3721 libbar.so.1 => /usr/X11R6/lib/libbar.so.1.0 (0x4001e000)
3722 libX11.so.6 => /usr/X11R6/lib/libX11.so.6 (0x4002c000)
3723 libc.so.6 => /lib/libc.so.6 (0x40114000)
3724 /lib/ld-linux.so.2 => /lib/ld-linux.so.2 (0x40000000)
3726 And when you ran <prgn>dpkg-shlibdeps</prgn>
3728 $ dpkg-shlibdeps -O foo
3729 dpkg-shlibdeps: warning: unable to find dependency information for shared library libbar
3730 (soname 1, path /usr/X11R6/lib/libbar.so.1.0, dependency field Depends)
3731 shlibs:Depends=libc6 (>= 2.2.1), xlibs (>= 4.0.1-11)
3733 The <prgn>foo</prgn> binary depends on the
3734 <prgn>libbar</prgn> shared library, but no package seems
3735 to provide a <tt>*.shlibs</tt> file in
3736 <tt>/var/lib/dpkg/info/</tt>. Let's determine the package
3742 $ dpkg -S /usr/X11R6/lib/libbar.so.1.0
3743 bar1: /usr/X11R6/lib/libbar.so.1.0
3744 $ dpkg -s bar1 | grep Version
3747 This tells us that the <prgn>bar1</prgn> package, version
3748 1.0-1 is the one we are using. Now we can create our own
3749 <tt>debian/shlibs.local</tt> to temporarily fix the above
3750 problem. Include the following line into your
3751 <tt>debian/shlibs.local</tt> file.
3753 libbar 1 bar1 (>= 1.0-1)
3755 Now your package build should work. As soon as the
3756 maintainer of <prgn>libbar1</prgn> provides a
3757 <tt>shlibs</tt> file, you can remove your
3758 <tt>debian/shlibs.local</tt> file.
3764 <chapt><heading>The Operating System</heading>
3768 <heading>File system hierarchy</heading>
3772 <heading>Linux File system Structure</heading>
3775 The location of all installed files and directories must
3776 comply with the Linux File system Hierarchy Standard
3777 (FHS). The latest version of this document can be found
3778 alongside this manual or on
3779 <url id="http://www.pathname.com/fhs/">.
3780 Specific questions about following the standard may be
3781 asked on <prgn>debian-devel</prgn>, or referred to Daniel
3782 Quinlan, the FHS coordinator, at
3783 <email>quinlan@pathname.com</email>.</p></sect1>
3787 <heading>Site-specific programs</heading>
3790 As mandated by the FHS, packages must not place any
3791 files in <tt>/usr/local</tt>, either by putting them in
3792 the file system archive to be unpacked by <prgn>dpkg</prgn>
3793 or by manipulating them in their maintainer scripts.</p>
3796 However, the package may create empty directories below
3797 <tt>/usr/local</tt> so that the system administrator knows
3798 where to place site-specific files. These directories
3799 should be removed on package removal if they are
3803 Note, that this applies only to directories <em>below</em>
3804 <tt>/usr/local</tt>, not <em>in</em>
3805 <tt>/usr/local</tt>. Packages must not create sub-directories
3806 in the directory <tt>/usr/local</tt> itself, except those listed in
3807 FHS, section 4.5. However, you may create directories
3808 below them as you wish. You must not remove any of the
3809 directories listed in 4.5, even if you created them.</p>
3812 Since <tt>/usr/local</tt> can be mounted read-only from a
3813 remote server, these directories must be created and
3814 removed by the <tt>postinst</tt> and <tt>prerm</tt>
3815 maintainer scripts. These scripts must not fail if either
3816 of these operations fail. (In the future, it will be
3817 possible to tell <prgn>dpkg</prgn> not to unpack files
3818 matching certain patterns, so that the directories can be
3819 included in the <tt>.deb</tt> packages and system
3820 administrators who do not wish these directories in
3821 /usr/local do not need to have them.)</p>
3824 For example, the <prgn>emacs</prgn> package will contain
3826 mkdir -p /usr/local/lib/emacs/site-lisp || true
3828 in the <tt>postinst</tt> script, and
3830 rmdir /usr/local/lib/emacs/site-lisp || true
3831 rmdir /usr/local/lib/emacs || true
3833 in the <tt>prerm</tt> script.</p>
3836 If you do create a directory in <tt>/usr/local</tt> for
3837 local additions to a package, you should ensure that
3838 settings in <tt>/usr/local</tt> take precedence over the
3839 equivalents in <tt>/usr</tt>.</p>
3842 However, because '/usr/local' and its contents are for
3843 exclusive use of the local administrator, a package must
3844 not rely on the presence or absence of files or
3845 directories in '/usr/local' for normal operation.</p>
3848 The <tt>/usr/local</tt> directory itself and all the
3849 subdirectories created by the package should (by default) have
3850 permissions 2775 (group-writable and set-group-id) and be
3851 owned by <tt>root.staff</tt>.</p>
3856 <heading>Users and groups</heading>
3859 The Debian system can be configured to use either plain or
3860 shadow passwords.</p>
3863 Some user ids (UIDs) and group ids (GIDs) are reserved
3864 globally for use by certain packages. Because some packages
3865 need to include files which are owned by these users or
3866 groups, or need the ids compiled into binaries, these ids
3867 must be used on any Debian system only for the purpose for
3868 which they are allocated. This is a serious restriction, and
3869 we should avoid getting in the way of local administration
3870 policies. In particular, many sites allocate users and/or
3871 local system groups starting at 100.</p>
3874 Apart from this we should have dynamically allocated ids,
3875 which should by default be arranged in some sensible
3876 order--but the behavior should be configurable.</p>
3879 Packages other than <tt>base-passwd</tt> must not modify
3880 <tt>/etc/passwd</tt>, <tt>/etc/shadow</tt>,
3881 <tt>/etc/group</tt> or <tt>/etc/gshadow</tt>.</p>
3884 The UID and GID ranges are as follows:
3889 Globally allocated by the Debian project, the
3890 same on every Debian system. These ids will appear in
3891 the <tt>passwd</tt> and <tt>group</tt> files of all
3892 Debian systems, new ids in this range being added
3893 automatically as the <tt>base-passwd</tt> package is
3897 Packages which need a single statically allocated uid
3898 or gid should use one of these; their maintainers
3899 should ask the <tt>base-passwd</tt> maintainer for
3906 Dynamically allocated system users and groups.
3907 Packages which need a user or group, but can have this
3908 user or group allocated dynamically and differently on
3909 each system, should use `<tt>adduser --system</tt>' to
3910 create the group and/or user. <prgn>adduser</prgn>
3911 will check for the existence of the user or group, and
3912 if necessary choose an unused id based on the ranges
3913 specified in <tt>adduser.conf</tt>.</p></item>
3916 <tag>1000-29999:</tag>
3919 Dynamically allocated user accounts. By default
3920 <prgn>adduser</prgn> will choose UIDs and GIDs for
3921 user accounts in this range, though
3922 <tt>adduser.conf</tt> may be used to modify this
3926 <tag>30000-59999:</tag>
3928 <p>Reserved.</p></item>
3931 <tag>60000-64999:</tag>
3934 Globally allocated by the Debian project, but only
3935 created on demand. The ids are allocated centrally and
3936 statically, but the actual accounts are only created
3937 on users' systems on demand.</p>
3940 These ids are for packages which are obscure or which
3941 require many statically-allocated ids. These packages
3942 should check for and create the accounts in
3943 <tt>/etc/passwd</tt> or <tt>/etc/group</tt> (using
3944 <prgn>adduser</prgn> if it has this facility) if
3945 necessary. Packages which are likely to require
3946 further allocations should have a `hole' left after
3947 them in the allocation, to give them room to
3951 <tag>65000-65533:</tag>
3953 <p>Reserved.</p></item>
3958 <p>User `<tt>nobody</tt>.' The corresponding gid refers
3959 to the group `<tt>nogroup</tt>.'</p></item>
3965 <tt>(uid_t)(-1) == (gid_t)(-1)</tt>. NOT TO BE USED,
3966 because it is the error return sentinel value.</p>
3971 <sect id="sysvinit">
3972 <heading>System run levels</heading>
3975 <sect1 id="/etc/init.d">
3976 <heading>Introduction</heading>
3979 The <tt>/etc/init.d</tt> directory contains the scripts
3980 executed by <prgn>init</prgn> at boot time and when init
3981 state (or `runlevel') is changed (see <manref name="init"
3985 There are at least two different, yet functionally
3986 equivalent, ways of handling these scripts. For the sake
3987 of simplicity, this document describes only the symbolic
3988 link method. However, it must not be assumed by maintainer
3989 scripts that this method is being used, and any automated
3990 manipulation of the various runlevel behaviours by
3991 maintainer scripts must be performed using `update-rc.d'
3992 as described below and not by manually installing or
3993 removing symlinks. For information on the
3994 implementation details of the other method, implemented in
3995 the <tt>file-rc</tt> package, please refer to the
3996 documentation of that package.</p>
3999 These scripts are referenced by symbolic links in
4000 the <tt>/etc/rc<var>n</var>.d</tt> directories. When
4001 changing runlevels, <prgn>init</prgn> looks in the
4002 directory <tt>/etc/rc<var>n</var>.d</tt> for the scripts
4003 it should execute, where <var>n</var> is the runlevel that
4004 is being changed to, or `S' for the boot-up scripts.</p>
4007 The names of the links all have the form
4008 <tt>S<var>mm</var><var>script</var></tt> or
4009 <tt>K<var>mm</var><var>script</var></tt> where
4010 <var>mm</var> is a two-digit number and <var>script</var>
4011 is the name of the script (this should be the same as the
4012 name of the actual script in <tt>/etc/init.d</tt>.</p>
4015 When <prgn>init</prgn> changes runlevel first the targets
4016 of the links whose names starting with a <tt>K</tt> are
4017 executed, each with the single argument <tt>stop</tt>,
4018 followed by the scripts prefixed with an <tt>S</tt>, each
4019 with the single argument <tt>start</tt>. The <tt>K</tt>
4020 links are responsible for killing services and the
4021 <tt>S</tt> link for starting services upon entering the
4025 For example, if we are changing from runlevel 2 to
4026 runlevel 3, init will first execute all of the <tt>K</tt>
4027 prefixed scripts it finds in <tt>/etc/rc3.d</tt>, and then
4028 all of the <tt>S</tt> prefixed scripts. The links
4029 starting with <tt>K</tt> will cause the referred-to file
4030 to be executed with an argument of <tt>stop</tt>, and the
4031 <tt>S</tt> links with an argument of <tt>start</tt>.</p>
4034 The two-digit number <var>mm</var> is used to decide which
4035 order to start and stop things in--low-numbered links have
4036 their scripts run first. For example, the <tt>K20</tt>
4037 scripts will be executed before the <tt>K30</tt> scripts.
4038 This is used when a certain service must be started before
4039 another. For example, the name server <prgn>bind</prgn>
4040 might need to be started before the news server
4041 <prgn>inn</prgn> so that <prgn>inn</prgn> can set up its
4042 access lists. In this case, the script that starts
4043 <prgn>bind</prgn> would have a lower number than the
4044 script that starts <prgn>inn</prgn> so that it runs first:
4053 <heading>Writing the scripts</heading>
4056 Packages that include daemons for system services should
4057 place scripts in <tt>/etc/init.d</tt> to start or stop
4058 services at boot time or during a change of runlevel.
4059 These scripts should be named
4060 <tt>/etc/init.d/<var>package</var></tt>, and they should
4061 accept one argument, saying what to do:
4064 <tag><tt>start</tt></tag>
4065 <item><p>start the service,</p></item>
4067 <tag><tt>stop</tt></tag>
4068 <item><p>stop the service,</p></item>
4070 <tag><tt>restart</tt></tag>
4071 <item><p>stop and restart the service,</p></item>
4073 <tag><tt>reload</tt></tag>
4074 <item><p>cause the configuration of the service to be
4075 reloaded without actually stopping and restarting
4076 the service,</p></item>
4078 <tag><tt>force-reload</tt></tag> <item><p>cause the
4079 configuration to be reloaded if the service supports
4080 this, otherwise restart the service.</p></item>
4083 The <tt>start</tt>, <tt>stop</tt>, <tt>restart</tt>, and
4084 <tt>force-reload</tt> options should be supported by all
4085 scripts in <tt>/etc/init.d</tt>, the <tt>reload</tt>
4086 option is optional.</p>
4089 The <tt>init.d</tt> scripts should ensure that they will
4090 behave sensibly if invoked with <tt>start</tt> when the
4091 service is already running, or with <tt>stop</tt> when it
4092 isn't, and that they don't kill unfortunately-named user
4093 processes. The best way to achieve this is usually to use
4094 <prgn>start-stop-daemon</prgn>.</p>
4097 If a service reloads its configuration automatically (as
4098 in the case of <prgn>cron</prgn>, for example), the
4099 <tt>reload</tt> option of the <tt>init.d</tt> script
4100 should behave as if the configuration has been reloaded
4104 These scripts should not fail obscurely when the
4105 configuration files remain but the package has been
4106 removed, as configuration files remain on the system after
4107 the package has been removed. Only when <prgn>dpkg</prgn>
4108 is executed with the <tt>--purge</tt> option will
4109 configuration files be removed. In particular, the init
4110 script itself is usually a configuration file (see
4111 <ref id="init.d notes">), and will remain on the system if
4112 the package is removed but not purged. Therefore, you
4113 should include a <tt>test</tt> statement at the top of the
4116 test -f <var>program-executed-later-in-script</var> || exit 0
4120 Often there are some values in the `<tt>init.d</tt>'
4121 scripts that a system administrator will frequently want
4122 to change. While the scripts are frequently conffiles,
4123 modifying them requires that the administrator merge in
4124 their changes each time the package is upgraded and the
4125 conffile changes. To ease the burden on the system
4126 administrator, such configurable values should not be
4127 placed directly in the script. Instead, they should be
4128 placed in a file in `<tt>/etc/default</tt>', which
4129 typically will have the same base name as the
4130 `<tt>init.d</tt>' script. This extra file can be sourced
4131 by the script when the script runs. It must contain only
4132 variable settings and comments.
4136 To ensure that vital configurable values are always
4137 available, the `<tt>init.d</tt>' script should set default
4138 values for each of the shell variables it uses before
4139 sourcing the <tt>/etc/default/</tt> file. Also, since the
4140 `<tt>/etc/default/</tt>' file is often a conffile, the
4141 `<tt>init.d</tt>' script must behave sensibly without
4142 failing if it is deleted.
4148 <heading>Managing the links</heading>
4151 The program <prgn>update-rc.d</prgn> is provided to make
4152 it easier for package maintainers to arrange for the
4153 proper creation and removal of
4154 <tt>/etc/rc<var>n</var>.d</tt> symbolic links, or their
4155 functional equivalent if another method is being used.
4156 This may be used by maintainers in their packages'
4157 <tt>postinst</tt> and <tt>postrm</tt> scripts.</p>
4160 You must use this script to make changes to
4161 <tt>/etc/rc<var>n</var>.d</tt> and <em>never</em> either
4162 include any <tt>/etc/rc<var>n</var>.d</tt> symbolic links
4163 in the actual archive or manually create or remove the
4164 symbolic links in maintainer scripts. (The latter will
4165 fail if an alternative method of maintaining runlevel
4166 information is being used.)</p>
4169 By default <prgn>update-rc.d</prgn> will start services in
4170 each of the multi-user state runlevels (2, 3, 4, and 5)
4171 and stop them in the halt runlevel (0), the single-user
4172 runlevel (1) and the reboot runlevel (6). The system
4173 administrator will have the opportunity to customize
4174 runlevels by either running <prgn>update-rc.d</prgn>, by
4175 simply adding, moving, or removing the symbolic links in
4176 <tt>/etc/rc<var>n</var>.d</tt> if symbolic links are being
4177 used, or by modifying <tt>/etc/runlevel.conf</tt> if the
4178 <tt>file-rc</tt> method is being used.</p>
4181 To get the default behavior for your package, put in your
4182 <tt>postinst</tt> script
4184 update-rc.d <var>package</var> defaults >/dev/null
4186 and in your <tt>postrm</tt>
4188 if [ purge = "$1" ]; then
4189 update-rc.d <var>package</var> remove >/dev/null
4194 This will use a default sequence number of 20. If it does
4195 not matter when or in which order the script is run, use
4196 this default. If it does, then you should talk to the
4197 maintainer of the <prgn>sysvinit</prgn> package or post to
4198 <tt>debian-devel</tt>, and they will help you choose a
4202 For more information about using <tt>update-rc.d</tt>,
4203 please consult its manpage <manref name="update-rc.d"
4204 section="8">.</p></sect1>
4208 <heading>Boot-time initialization</heading>
4211 There used to be another directory, <tt>/etc/rc.boot</tt>,
4212 which contained scripts which were run once per machine
4213 boot. This has been deprecated in favour of links from
4214 <tt>/etc/rcS.d</tt> to files in <tt>/etc/init.d</tt> as
4215 described in <ref id="/etc/init.d">. Packages must not
4216 place files in <tt>/etc/rc.boot</tt>.</p>
4218 <sect1 id="init.d notes">
4219 <heading>Notes</heading>
4222 <em>Do not</em> include the
4223 <tt>/etc/rc<var>n</var>.d/*</tt> symbolic links in the
4224 <tt>.deb</tt> file system archive! <em>This will cause
4225 problems!</em> You must create them with
4226 <prgn>update-rc.d</prgn>, as above.</p>
4229 <em>Do not</em> include the
4230 <tt>/etc/rc<var>n</var>.d/*</tt> symbolic links in
4231 <prgn>dpkg</prgn>'s conffiles list! <em>This will cause
4232 problems!</em> You should, however, treat the
4233 <tt>/etc/init.d</tt> scripts as configuration files,
4234 either by marking them as conffiles or managing them
4235 correctly in the maintainer scripts (see
4236 <ref id="config files">). (This is important since we want
4237 to give the local system administrator the chance to adapt
4238 the scripts to the local system--e.g., to disable a
4239 service without de-installing the package, or to specify
4240 some special command line options when starting a
4241 service--while making sure her changes aren't lost during
4242 the next package upgrade.)</p>
4246 <heading>Example</heading>
4249 The <prgn>bind</prgn> DNS (nameserver) package wants to
4250 make sure that the nameserver is running in multiuser
4251 runlevels, and is properly shut down with the system. It
4252 puts a script in <tt>/etc/init.d</tt>, naming the script
4253 appropriately <tt>bind</tt>. As you can see, the script
4254 interprets the argument <tt>reload</tt> to send the
4255 nameserver a <tt>HUP</tt> signal (causing it to reload its
4256 configuration); this way the user can say
4257 <tt>/etc/init.d/bind reload</tt> to reload the name
4258 server. The script has one configurable value, which can
4259 be used to pass parameters to the named program at
4267 # Original version by Robert Leslie
4268 # <rob@mars.org>, edited by iwj and cs
4270 test -x /usr/sbin/named || exit 0
4272 # Source defaults file.
4274 if [ -f /etc/default/bind ]; then
4281 echo -n "Starting domain name service: named"
4282 start-stop-daemon --start --quiet --exec /usr/sbin/named \
4287 echo -n "Stopping domain name service: named"
4288 start-stop-daemon --stop --quiet \
4289 --pidfile /var/run/named.pid --exec /usr/sbin/named
4293 echo -n "Restarting domain name service: named"
4294 start-stop-daemon --stop --quiet \
4295 --pidfile /var/run/named.pid --exec /usr/sbin/named
4296 start-stop-daemon --start --verbose --exec /usr/sbin/named \
4300 force-reload|reload)
4301 echo -n "Reloading configuration of domain name service: named"
4302 start-stop-daemon --stop --signal 1 --quiet \
4303 --pidfile /var/run/named.pid --exec /usr/sbin/named
4307 echo "Usage: /etc/init.d/bind {start|stop|restart|reload|force-reload}" >&2
4317 Complementing the above init script is a file
4318 '<tt>/etc/default/bind</tt>', which contains configurable
4319 parameters used by the script.
4323 # Specified parameters to pass to named. See named(8).
4324 # You may uncomment the following line, and edit to taste.
4330 Another example on which to base your <tt>/etc/init.d</tt>
4331 scripts is in <tt>/etc/init.d/skeleton</tt>.</p>
4334 If this package is happy with the default setup from
4335 <prgn>update-rc.d</prgn>, namely an ordering number of 20
4336 and having named running in all runlevels, it can say in
4337 its <tt>postinst</tt>:
4339 update-rc.d bind defaults >/dev/null
4341 And in its <tt>postrm</tt>, to remove the links when the
4344 if [ purge = "$1" ]; then
4345 update-rc.d bind remove >/dev/null
4351 <heading>Cron jobs</heading>
4354 Packages must not modify the configuration file
4355 <tt>/etc/crontab</tt>, and they must not modify the files in
4356 <tt>/var/spool/cron/crontabs</tt>.</p>
4359 If a package wants to install a job that has to be executed
4360 via cron, it should place a file with the name of the
4361 package in one of the following directories:
4367 As these directory names imply, the files within them are
4368 executed on a daily, weekly, or monthly basis,
4369 respectively. The exact times are listed in
4370 <tt>/etc/crontab</tt>.</p>
4373 All files installed in any of these directories must be
4374 scripts (shell scripts, Perl scripts, etc.) so that they can
4375 easily be modified by the local system administrator. In
4376 addition, they should be treated as configuration files.</p>
4379 If a certain job has to be executed more frequently than
4380 daily, the package should install a file
4381 <tt>/etc/cron.d/<var>package-name</var></tt>. This file uses
4382 the same syntax as <tt>/etc/crontab</tt> and is processed by
4383 <prgn>cron</prgn> automatically. The file must also be
4384 treated as a configuration file. (Note, that entries in the
4385 <tt>/etc/cron.d</tt> directory are not handled by
4386 <prgn>anacron</prgn>. Thus, you should only use this
4387 directory for jobs which may be skipped if the system is not
4391 The scripts or crontab entries in these directories should
4392 check if all necessary programs are installed before they
4393 try to execute them. Otherwise, problems will arise when a
4394 package was removed but not purged since configuration files
4395 are kept on the system in this situation.</p>
4399 <heading>Console messages</heading>
4402 This section describes different formats for messages
4403 written to standard output by the <tt>/etc/init.d</tt>
4404 scripts. The intent is to improve the consistency of
4405 Debian's startup and shutdown look and feel.</p>
4408 Please look very careful at the details. We want to get the
4409 messages to look exactly the same way concerning spaces,
4410 punctuation, and case of letters.</p>
4413 Here is a list of overall rules that you should use when you
4414 create output messages. They can be useful if you have a
4415 non-standard message that isn't covered in the sections
4422 Every message should cover one line, start with a
4423 capital letter and end with a period `.'.</p></item>
4428 If you want to express that the computer is working on
4429 something (performing a specific task, not starting or
4430 stopping a program), we use an ``ellipsis'', namely
4431 three dots `...'. Note that we don't insert spaces in
4432 front of or behind the dots. If the task has been
4433 completed we write `done.' and a line feed.</p></item>
4438 Design your messages as if the computer is telling you
4439 what he is doing (let him be polite :-) but don't
4440 mention ``him'' directly. For example, if you think
4443 I'm starting network daemons: nfsd mountd.
4447 Starting network daemons: nfsd mountd.
4448 </example></p></item>
4452 The following formats should be used</p>
4457 <p>when daemons get started.</p>
4460 Use this format if your script starts one or more
4461 daemons. The output should look like this (a single
4462 line, no leading spaces):
4464 Starting <description>: <daemon-1> <daemon-2> <...> <daemon-n>.
4466 The <description> should describe the subsystem
4467 the daemon or set of daemons are part of, while
4468 <daemon-1> up to <daemon-n> denote each
4469 daemon's name (typically the file name of the
4473 For example, the output of /etc/init.d/lpd would look like:
4475 Starting printer spooler: lpd.
4479 This can be achieved by saying
4481 echo -n "Starting printer spooler: lpd"
4482 start-stop-daemon --start --quiet lpd
4485 in the script. If you have more than one daemon to
4486 start, you should do the following:
4488 echo -n "Starting remote file system services:"
4489 echo -n " nfsd"; start-stop-daemon --start --quiet nfsd
4490 echo -n " mountd"; start-stop-daemon --start --quiet mountd
4491 echo -n " ugidd"; start-stop-daemon --start --quiet ugidd
4494 This makes it possible for the user to see what takes
4495 so long and when the final daemon has been
4496 started. You should be careful where to put spaces: In the
4497 example above the system administrator can easily
4498 comment out a line if he don't wants to start a
4499 specific daemon, while the displayed message still
4500 looks good.</p></item>
4504 <p>when something needs to be configured.</p>
4507 If you have to set up different parameters of the
4508 system upon boot up, you should use this format:
4510 Setting <parameter> to `<value>'.
4514 You can use the following echo statement to get the quotes right:
4516 echo "Setting DNS domainname to \`"value"'."
4520 Note that the left quotation mark (`) is different
4521 from the right (').</p></item>
4524 <p>when a daemon is stopped.</p>
4527 When you stop a daemon you should issue a message
4528 similar to the startup message, except that `Starting'
4529 is replaced with `Stopping'.</p>
4532 So stopping the printer daemon will like like this:
4534 Stopping printer spooler: lpd.
4535 </example></p></item>
4538 <p>when something is executed.</p>
4541 There are several examples where you have to run a
4542 program at system startup or shutdown to perform a
4543 specific task. For example, setting the system's clock
4544 via `netdate' or killing all processes when the system
4545 comes down. Your message should like this:
4547 Doing something very useful...done.
4549 You should print the `done.' right after the job has been completed,
4550 so that the user gets informed why he has to wait. You can get this
4553 echo -n "Doing something very useful..."
4557 in your script.</p></item>
4560 <p>when the configuration is reloaded.</p>
4563 When a daemon is forced to reload its configuration
4564 files you should use the following format:
4566 Reloading <daemon's-name> configuration...done.
4567 </example></p></item>
4570 <p>when none of the above rules apply.</p>
4573 If you have to print a message that doesn't fit into
4574 the styles described above, you can use something
4575 appropriate, but please have a look at the overall
4576 rules listed above.</p></item>
4581 <heading>Menus</heading>
4584 Menu entries should follow the current menu policy as
4585 defined in the file <ftpsite>ftp.debian.org</ftpsite> in
4586 <ftppath>/debian/doc/package-developer/menu-policy.text.gz</ftppath>
4587 or your local mirror. In addition, it is included in the
4588 <tt>debian-policy</tt> package.
4592 The Debian <tt>menu</tt> packages provides a unique
4593 interface between packages providing applications and
4594 documents, and <em>menu programs</em> (either X window
4595 managers or text-based menu programs as
4596 <prgn>pdmenu</prgn>).</p>
4599 All packages that provide applications that need not be
4600 passed any special command line arguments for normal
4601 operation should register a menu entry for those
4602 applications, so that users of the <tt>menu</tt> package
4603 will automatically get menu entries in their window
4604 managers, as well in shells like <tt>pdmenu</tt>.</p>
4607 Please refer to the <em>Debian Menu System</em> document
4608 that comes with the <tt>menu</tt> package for information
4609 about how to register your applications and web
4615 <heading>Multimedia handlers</heading>
4618 Packages which provide the ability to view/show/play,
4619 compose, edit or print MIME types should register themselves
4620 as such following the current MIME support policy as defined
4621 in the file found on <ftpsite>ftp.debian.org</ftpsite> in
4622 <ftppath>/debian/doc/package-developer/mime-policy.text.gz</ftppath>
4623 or your local mirror. In addition, it is included in the
4624 <tt>debian-policy</tt> package.
4628 MIME (Multipurpose Internet Mail Extensions, RFC 1521) is a
4629 mechanism for encoding files and data streams and providing
4630 meta-information about them, in particular their type (e.g.
4631 audio or video) and format (e.g. PNG, HTML, MP3).
4635 Registration of MIME type handlers allows programs like mail
4636 user agents and web browsers to to invoke these handlers to
4637 view, edit or display MIME types they don't support
4643 <heading>Keyboard configuration</heading>
4646 To achieve a consistent keyboard configuration (i.e., all
4647 applications interpret a keyboard event the same way) all
4648 programs in the Debian distribution must be configured to
4649 comply with the following guidelines.</p>
4652 Here is a list that contains certain keys and their interpretation:
4655 <tag><tt><--</tt></tag>
4656 <item><p>delete the character to the left of the cursor</p></item>
4658 <tag><tt>Delete</tt></tag>
4659 <item><p>delete the character to the right of the cursor</p></item>
4661 <tag><tt>Control+H</tt></tag>
4662 <item><p>emacs: the help prefix</p></item>
4665 The interpretation of any keyboard events should be independent
4666 of the terminal that's used, be it a virtual console, an X
4667 terminal emulator, an rlogin/telnet session, etc.</p>
4670 The following list explains how the different programs
4671 should be set up to achieve this:</p>
4674 <list compact="compact">
4675 <item><p>`<tt><--</tt>' generates KB_Backspace in
4678 <item><p>`<tt>Delete</tt>' generates KB_Delete in X.</p></item>
4682 X translations are set up to make KB_Backspace
4683 generate ASCII DEL, and to make KB_Delete generate
4684 <tt>ESC [ 3 ~</tt> (this is the vt220 escape code for
4685 the `delete character' key). This must be done by
4686 loading the resources using xrdb on all local X
4687 displays, not using the application defaults, so that
4688 the translation resources used correspond to the
4689 xmodmap settings.</p></item>
4693 The Linux console is configured to make
4694 `<tt><--</tt>' generate DEL, and `Delete' generate
4695 <tt>ESC [ 3 ~</tt> (this is the case at the
4699 X applications are configured so that Backspace
4700 deletes left, and Delete deletes right. Motif
4701 applications already work like this.</p></item>
4703 <item><p>stty erase <tt>^?</tt> .</p></item>
4706 The `xterm' terminfo entry should have <tt>ESC [ 3
4707 ~</tt> for kdch1, just like TERM=linux and
4708 TERM=vt220.</p></item>
4711 Emacs is programmed to map KB_Backspace or the `stty
4712 erase' character to delete-backward-char, and
4713 KB_Delete or kdch1 to delete-forward-char, and
4714 <tt>^H</tt> to help as always.</p></item>
4717 Other applications use the `stty erase' character and
4718 kdch1 for the two delete keys, with ASCII DEL being
4719 `delete previous character' and kdch1 being `delete
4720 character under cursor'.</p></item>
4724 This will solve the problem except for:</p>
4727 <list compact="compact">
4729 Some terminals have a <tt><--</tt> key that cannot
4730 be made to produce anything except <tt>^H</tt>. On
4731 these terminals Emacs help will be unavailable on
4732 <tt>^H</tt> (assuming that the `stty erase' character
4733 takes precedence in Emacs, and has been set
4734 correctly). M-x help or F1 (if available) can be used
4738 Some operating systems use <tt>^H</tt> for stty erase.
4739 However, modern telnet versions and all rlogin
4740 versions propagate stty settings, and almost all UNIX
4741 versions honour stty erase. Where the stty settings
4742 are not propagated correctly things can be made to
4743 work by using stty manually.</p></item>
4746 Some systems (including previous Debian versions) use
4747 xmodmap to arrange for both <tt><--</tt> and Delete
4748 to generate KB_Delete. We can change the behavior
4749 of their X clients via the same X resources that we
4750 use to do it for our own, or have our clients be
4751 configured via their resources when things are the
4752 other way around. On displays configured like this
4753 Delete will not work, but <tt><--</tt>
4757 Some operating systems have different kdch1 settings
4758 in their terminfo for xterm and others. On these
4759 systems the Delete key will not work correctly when
4760 you log in from a system conforming to our policy, but
4761 <tt><--</tt> will.</p></item>
4768 <heading>Environment variables</heading>
4771 A program must not depend on environment variables to get
4772 reasonable defaults. (That's because these environment
4773 variables would have to be set in a system-wide
4774 configuration file like /etc/profile, which is not supported
4778 If a program usually depends on environment variables for its
4779 configuration, the program should be changed to fall back to
4780 a reasonable default configuration if these environment
4781 variables are not present. If this cannot be done easily
4782 (e.g., if the source code of a non-free program is not
4783 available), the program must be replaced by a small
4784 `wrapper' shell script which sets the environment variables
4785 if they are not already defined, and calls the original program.</p>
4788 Here is an example of a wrapper script for this purpose:
4792 BAR=${BAR:-/var/lib/fubar}
4794 exec /usr/lib/foo/foo "$@"
4798 Furthermore, as <tt>/etc/profile</tt> is a configuration
4799 file of the <prgn>base-files</prgn> package, other packages must not
4800 put any environment variables or other commands into that
4805 <heading>Files</heading>
4809 <heading>Binaries</heading>
4812 Two different packages must not install programs with
4813 different functionality but with the same filenames. (The
4814 case of two programs having the same functionality but
4815 different implementations is handled via `alternatives.')
4816 If this case happens, one of the programs must be
4817 renamed. The maintainers should report this to the
4818 developers' mailing and try to find a consensus about
4819 which package will have to be renamed. If a consensus can
4820 not be reached, <em>both</em> programs must be
4824 Generally the following compilation parameters should be used:
4827 CFLAGS = -O2 -Wall # sane warning options vary between programs
4829 install -s # (or use strip on the files in debian/tmp)
4833 Note that by default all installed binaries should be stripped,
4834 either by using the <tt>-s</tt> flag to
4835 <prgn>install</prgn>, or by calling <prgn>strip</prgn> on
4836 the binaries after they have been copied into
4837 <tt>debian/tmp</tt> but before the tree is made into a
4841 The <tt>-N</tt> flag should not be used. On a.out systems
4842 it may have been useful for some very small binaries, but
4843 for ELF it has no good effect.</p>
4846 Debugging symbols are useful for error diagnosis,
4847 investigation of core dumps (which may be submitted by users
4848 in bug reports), or testing and developing the
4849 software. Therefore it is recommended to support building
4850 the package with debugging information through the following
4851 interface: If the environment variable
4852 <tt>DEB_BUILD_OPTIONS</tt> contains the string
4853 <tt>debug</tt>, compile the software with debugging
4854 information (usually this involves adding the <tt>-g</tt>
4855 flag to <tt>CFLAGS</tt>). This allows the generation of a
4856 build tree with debugging information. If the environment
4857 variable <tt>DEB_BUILD_OPTIONS</tt> contains the string
4858 <tt>nostrip</tt>, do not strip the files at installation
4859 time. This allows one to generate a package with debugging
4860 information included. The following makefile snippet is only
4861 an example of how one may test for either condition:
4864 Rationale: Building by default with -g causes more
4865 wasted CPU cycles since the information is stripped away
4866 anyway. The package can by default build without -g if
4867 it also provides a mechanism to easily be rebuilt with
4868 debugging information. This can be done by providing a
4869 "build-debug" make target, or allowing the user to
4870 specify "DEB_BUILD_OPTIONS=debug" in the environment while
4871 compiling that package.
4873 <p>Now this has several added benefits:
4877 It is actually easier to build debugging bins and
4878 libraries this way (no more editing debian/rules
4879 or similar) since it provides a documented way of
4880 getting this type of build.</p>
4884 There will be much less wasted CPU time for the
4885 autobuilders since not having debugging
4886 information (and hence also not having to strip
4887 it) will increase the speed of compiles. This
4888 skips an entire pass of the compiler.
4899 INSTALL_FILE = $(INSTALL) -p -o root -g root -m 644
4900 INSTALL_PROGRAM = $(INSTALL) -p -o root -g root -m 755
4901 INSTALL_SCRIPT = $(INSTALL) -p -o root -g root -m 755
4902 INSTALL_DIR = $(INSTALL) -p -d -o root -g root -m 755
4904 ifneq (,$(findstring debug,$(DEB_BUILD_OPTIONS)))
4907 ifeq (,$(findstring nostrip,$(DEB_BUILD_OPTIONS)))
4908 INSTALL_PROGRAM += -s
4912 Please note that the above example is merely informative,
4913 and is not a policy mandate. You may have to massage this
4914 example in order to make it work for your package.
4919 It is up to the package maintainer to decide what
4920 compilation options are best for the package. Certain
4921 binaries (such as computationally-intensive programs) will
4922 function better with certain flags (<tt>-O3</tt>, for
4923 example); feel free to use them. Please use good judgment
4924 here. Don't use flags for the sake of it; only use them
4925 if there is good reason to do so. Feel free to override
4926 the upstream author's ideas about which compilation
4927 options are best--they are often inappropriate for our
4928 environment.</p></sect>
4932 <heading>Libraries</heading>
4935 All libraries must have a shared version in the lib
4936 package and a static version in the lib-dev package. The
4937 shared version must be compiled with <tt>-fPIC</tt>, and
4938 the static version must not be. In other words, each
4939 <tt>*.c</tt> file will need to be compiled twice.</p>
4942 You must specify the gcc option <tt>-D_REENTRANT</tt>
4943 when building a library (either static or shared) to make
4944 the library compatible with LinuxThreads.</p>
4947 Note that all installed shared libraries should be
4950 strip --strip-unneeded <your-lib>
4952 (The option `--strip-unneeded' makes <tt>strip</tt> remove
4953 only the symbols which aren't needed for relocation
4954 processing.) Shared libraries can function perfectly well
4955 when stripped, since the symbols for dynamic linking are
4956 in a separate part of the ELF object file.</p>
4959 Note that under some circumstances it may be useful to
4960 install a shared library unstripped, for example when
4961 building a separate package to support debugging.
4965 An ever increasing number of packages are using libtool to
4966 do their linking. The latest GNU libtools (>= 1.3a) can take
4967 advantage of the metadata in the installed libtool archive
4968 files (`*.la'). The main advantage of libtool's .la files is
4969 that it allows libtool to store and subsequently access
4970 metadata with respect to the libraries it builds. libtool
4971 will search for those files, which contain a lot of useful
4972 information about a library (e.g. dependency libraries for
4973 static linking). Also, they're <em>essential</em> for
4974 programs using libltdl.
4978 Certainly libtool is fully capable of linking against shared
4979 libraries which don't have .la files, but being a mere shell
4980 script it can add considerably to the build time of a
4981 libtool using package if that shell-script has to derive all
4982 this information from first principles for each library every
4983 time it is linked. With the advent of libtool-1.4 (and to a
4984 lesser extent libtool-1.3), the .la files will also store
4985 information about inter-library dependencies which cannot
4986 necessarily be derived after the .la file is deleted.
4990 Packages that use libtool to create shared libraries should
4991 include the <em>.la</em> files in the <em>-dev</em>
4992 packages, with the exception that if the package relies on
4993 libtool's <em>libltdl</em> library, in which case the .la
4994 files must go in the run-time library package. This is a
4995 good idea in general, and especially for static linking
5000 You must make sure that you use only released versions of
5001 shared libraries to build your packages; otherwise other
5002 users will not be able to run your binaries
5003 properly. Producing source packages that depend on
5004 unreleased compilers is also usually a bad
5011 <heading>Shared libraries</heading>
5014 Packages involving shared libraries should be split up
5015 into several binary packages.</p>
5018 For a straightforward library which has a development
5019 environment and a runtime kit including just shared
5020 libraries you need to create two packages:
5021 <tt><var>libraryname</var><var>soname</var></tt>
5022 (<var>soname</var> is the shared object name of the shared
5023 library--it's the thing that has to match exactly between
5024 building an executable and running it for the dynamic
5025 linker to be able run the program; usually the
5026 <var>soname</var> is the major number of the library) and
5027 <tt><var>libraryname</var><var>soname</var>-dev</tt>.</p>
5030 If you prefer only to support one development version at a
5031 time you may name the development package
5032 <tt><var>libraryname</var>-dev</tt>; otherwise you may
5033 wish to use <prgn>dpkg</prgn>'s conflicts mechanism to
5034 ensure that the user only installs one development version
5035 at a time (after all, different development versions are
5036 likely to have the same header files in them, causing a
5037 filename clash if both are installed). Typically the
5038 development version should also have an exact version
5039 dependency on the runtime library, to make sure that
5040 compilation and linking happens correctly.</p>
5043 Packages which use the shared library should have a
5044 dependency on the name of the shared library package,
5045 <tt><var>libraryname</var><var>soname</var></tt>. When
5046 the <var>soname</var> changes you can have both versions
5047 of the library installed while moving from the old library
5051 If your package has some run-time support programs which
5052 use the shared library you must not put them in
5053 the shared library package. If you do that then you won't
5054 be able to install several versions of the shared library
5055 without getting filename clashes. Instead, either create
5056 a third package for the runtime binaries (this package
5057 might typically be named
5058 <tt><var>libraryname</var>-runtime</tt>--note the absence
5059 of the <var>soname</var> in the package name) or if the
5060 development package is small include them in there.</p>
5063 If you have several shared libraries built from the same
5064 source tree you may lump them all together into a single
5065 shared library package, provided that you change all their
5066 <var>soname</var>s at once (so that you don't get filename
5067 clashes if you try to install different versions of the
5068 combined shared libraries package).</p>
5071 You should follow the directions in the <em>Debian Packaging
5072 Manual</em> for putting the shared library in its package,
5073 and you must include a <tt>shlibs</tt> control area
5074 file with details of the dependencies for packages which
5075 use the library.</p>
5078 Shared libraries should not be installed
5079 executable, since <prgn>ld.so</prgn> does not require this
5080 and trying to execute a shared library results in a core
5085 <heading>Scripts</heading>
5088 All command scripts, including the package maintainer
5089 scripts inside the package and used by <prgn>dpkg</prgn>,
5090 should have a <tt>#!</tt> line naming the shell to be used
5091 to interpret them.</p>
5094 In the case of Perl scripts this should be
5095 <tt>#!/usr/bin/perl</tt>.</p>
5098 Shell scripts (<prgn>sh</prgn> and <prgn>bash</prgn>)
5099 should almost certainly start with <tt>set -e</tt> so that
5100 errors are detected. Every script should use
5101 <tt>set -e</tt> or check the exit status of <em>every</em>
5105 The standard shell interpreter `<tt>/bin/sh</tt>' can be a
5106 symbolic link to any POSIX compatible shell, if <tt>echo
5107 -n</tt> does not generate a newline.
5110 Debian policy specifies POSIX behavior for /bin/sh, but
5111 echo -n has widespread use in the Linux community
5112 (including especially debian policy, the linux kernel
5113 source, many debian scripts, etc.). This echo -n
5114 mechanism is valid but not required under POSIX, hence
5115 this explicit addition. Also, rumour has it that this
5116 shall be mandated under the LSB anyway.
5120 specifying `<tt>/bin/sh</tt>' as interpreter should only
5121 use POSIX features. If a script requires non-POSIX
5122 features from the shell interpreter, the appropriate shell
5123 must be specified in the first line of the script (e.g.,
5124 `<tt>#!/bin/bash</tt>') and the package must depend on the
5125 package providing the shell (unless the shell package is
5126 marked `Essential', e.g., in the case of
5131 You may wish to restrict your script to POSIX features when possible so
5132 that it may use <tt>/bin/sh</tt> as its interpreter. If
5133 your script works with <prgn>ash</prgn>, it's probably
5134 POSIX compliant, but if you are in doubt, use
5135 <tt>/bin/bash</tt>.</p>
5138 Perl scripts should check for errors when making any
5139 system calls, including <tt>open</tt>, <tt>print</tt>,
5140 <tt>close</tt>, <tt>rename</tt> and <tt>system</tt>.</p>
5143 <prgn>csh</prgn> and <prgn>tcsh</prgn> should be avoided
5144 as scripting languages. See <em>Csh Programming
5145 Considered Harmful</em>, one of the <tt>comp.unix.*</tt>
5146 FAQs. It can be found on
5147 <url id="http://language.perl.com/versus/csh.whynot">, or
5148 <url id="http://www.cpan.org/doc/FMTEYEWTK/versus/csh.whynot">
5149 or even on <ftpsite>ftp.cpan.org</ftpsite>
5150 <ftppath>/pub/perl/CPAN/doc/FMTEYEWTK/versus/csh.whynot</ftppath>.
5151 If an upstream package comes with <prgn>csh</prgn> scripts
5152 then you must make sure that they start with
5153 <tt>#!/bin/csh</tt> and make your package depend on the
5154 <prgn>c-shell</prgn> virtual package.</p>
5157 Any scripts which create files in world-writeable
5158 directories (e.g., in <tt>/tmp</tt>) must use a
5159 mechanism which will fail if a file with the same name
5163 The Debian base distribution provides the
5164 <prgn>tempfile</prgn> and <prgn>mktemp</prgn> utilities
5165 for use by scripts for this purpose.</p></sect>
5169 <heading>Symbolic links</heading>
5172 In general, symbolic links within a top-level directory
5173 should be relative, and symbolic links pointing from one
5174 top-level directory into another should be absolute. (A
5175 top-level directory is a sub-directory of the root
5179 In addition, symbolic links should be specified as short
5180 as possible, i.e., link targets like `foo/../bar' are
5184 Note that when creating a relative link using
5185 <prgn>ln</prgn> it is not necessary for the target of the
5186 link to exist relative to the working directory you're
5187 running <prgn>ln</prgn> from; nor is it necessary to
5188 change directory to the directory where the link is to be
5189 made. Simply include the string that should appear as the
5190 target of the link (this will be a pathname relative to
5191 the directory in which the link resides) as the first
5192 argument to <prgn>ln</prgn>.</p>
5195 For example, in your <prgn>Makefile</prgn> or
5196 <tt>debian/rules</tt>, do things like:
5198 ln -fs gcc $(prefix)/bin/cc
5199 ln -fs gcc debian/tmp/usr/bin/cc
5200 ln -fs ../sbin/sendmail $(prefix)/bin/runq
5201 ln -fs ../sbin/sendmail debian/tmp/usr/bin/runq
5205 A symbolic link pointing to a compressed file should
5206 always have the same file extension as the referenced
5207 file. (For example, if a file `<tt>foo.gz</tt>' is
5208 referenced by a symbolic link, the filename of the link
5209 has to end with `<tt>.gz</tt>' too, as in
5210 `bar.gz.')</p></sect>
5214 <heading>Device files</heading>
5217 Packages must not include device files in the package file
5221 If a package needs any special device files that are not
5222 included in the base system, it must call
5223 <prgn>MAKEDEV</prgn> in the <tt>postinst</tt> script,
5224 after asking the user for permission to do so.</p>
5227 Packages must not remove any device files in the
5228 <tt>postrm</tt> or any other script. This is left to the
5229 system administrator.</p>
5232 Debian uses the serial devices
5233 <tt>/dev/ttyS*</tt>. Programs using the old
5234 <tt>/dev/cu*</tt> devices should be changed to use
5235 <tt>/dev/ttyS*</tt>.</p>
5238 <sect id="config files">
5239 <heading>Configuration files</heading>
5241 <heading>Definitions</heading>
5244 <tag>configuration file</tag>
5246 A file that affects the operation of program, or
5247 provides site- or host-specific information, or
5248 otherwise customizes the behavior of program.
5249 Typically, configuration files are intended to be
5250 modified by the system administrator (if needed or
5251 desired) to conform to local policy or provide more
5252 useful site-specific behavior.</p>
5255 <tag><tt>conffile</tt></tag>
5257 A file listed in a package's <tt>conffiles</tt>
5258 file, and is treated specially by <prgn>dpkg</prgn>
5259 (see the <em>Debian Packaging Manual</em>).</p>
5265 The distinction between these two is important; they are
5266 not interchangeable concepts. Almost all
5267 <tt>conffiles</tt> are configuration files, but many
5268 configuration files are not <tt>conffiles</tt>.</p>
5271 Note that a script that embeds configuration information
5272 (such as most of the files in <tt>/etc/init.d</tt> and
5273 <tt>/etc/cron.{daily,weekly,monthly}</tt>) is de-facto a
5274 configuration file and should be treated as such.</p>
5278 <heading>Location</heading>
5280 Any configuration files created or used by your package
5281 must reside in <tt>/etc</tt>. If there are several you
5282 should consider creating a subdirectory of <tt>/etc</tt>
5283 named after your package.</p>
5286 If your package creates or uses configuration files
5287 outside of <tt>/etc</tt>, and it is not feasible to modify
5288 the package to use the <tt>/etc</tt>, you should still put
5289 the files in <tt>/etc</tt> and create symbolic links to
5290 those files from the location that the package
5295 <heading>Behavior</heading>
5297 Configuration file handling must conform to the following
5301 <p>local changes must be preserved during a package
5305 <p>configuration files must be preserved when the
5306 package is removed, and only deleted when the
5307 package is purged.</p>
5312 The easy way to achieve this behavior is to make the
5313 configuration file a <tt>conffile</tt>. This is
5314 appropriate only if it is possible to distribute a default
5315 version that will work for most installations, although
5316 some system administrators may choose to modify it. This
5317 implies that the default version will be part of the
5318 package distribution, and must not be modified by the
5319 maintainer scripts during installation (or at any other
5324 In order to ensure that local changes are preserved
5325 correctly, no package may contain or make hard links to
5329 Rationale: There are two problems with hard links.
5330 The first is that some editors break the link while
5331 editing one of the files, so that the two files may
5332 unwittingly become different. The second is that
5333 <prgn>dpkg</prgn> might break the hard link while
5334 upgrading <tt>conffile</tt>s.
5339 The other way to do it is via the maintainer scripts.
5340 In this case, the configuration file must not be listed as
5341 a <tt>conffile</tt> and must not be part of the package
5342 distribution. If the existence of a file is required for
5343 the package to be sensibly configured it is the
5344 responsibility of the package maintainer to write scripts
5345 which correctly create, update, maintain and
5346 remove-on-purge the file. These scripts must be idempotent
5347 (i.e., must work correctly if <prgn>dpkg</prgn> needs to
5348 re-run them due to errors during installation or removal),
5349 must cope with all the variety of ways <prgn>dpkg</prgn>
5350 can call maintainer scripts, must not overwrite or
5351 otherwise mangle the user's configuration without asking,
5352 must not ask unnecessary questions (particularly during
5353 upgrades), and otherwise be good citizens.</p>
5356 The scripts are not required to configure every possible option for
5357 the package, but only those necessary to get the package
5358 running on a given system. Ideally the sysadmin should not
5359 have to do any configuration other than that done
5360 (semi-)automatically by the <tt>postinst</tt> script.</p>
5363 A common practice is to create a script called
5364 <tt><var>package</var>-configure</tt> and have the
5365 package's <tt>postinst</tt> call it if and only if the
5366 configuration file does not already exist. In certain
5367 cases it is useful for there to be an example or template
5368 file which the maintainer scripts use. Such files should
5369 be in <tt>/usr/share/doc</tt> if they are examples or
5370 <tt>/usr/lib</tt> if they are templates, and should be
5371 perfectly ordinary <prgn>dpkg</prgn>-handled files
5372 (<em>not</em> <tt>conffiles</tt>).</p>
5375 These two styles of configuration file handling must
5376 not be mixed, for that way lies madness:
5377 <prgn>dpkg</prgn> will ask about overwriting the file
5378 every time the package is upgraded.</p>
5383 <heading>Sharing configuration files</heading>
5385 Packages which specify the same file as
5386 `<tt>conffile</tt>' must be tagged as <em>conflicting</em>
5391 The maintainer scripts must not alter the conffile of
5392 <em>any</em> package, including the one the scripts belong
5396 If two or more packages use the same configuration file
5397 and it is reasonable for both to be installed at the same
5398 time, one of these packages must be defined as
5399 <em>owner</em> of the configuration file, i.e., it will be
5400 the package to list that distributes the file and lists it
5401 as a <tt>conffile</tt>. Other packages that use the
5402 configuration file must depend on the owning package if
5403 they require the configuration file to operate. If the
5404 other package will use the configuration file if present,
5405 but is capable of operating without it, no dependency need
5409 If it is desirable for two or more related packages to
5410 share a configuration file <em>and</em> for all of the
5411 related packages to be able to modify that configuration
5412 file, then the following should be done:
5416 have one of the related packages (the "core"
5417 package) manage the configuration file with
5418 maintainer scripts as described in the previous
5422 the core package should also provide a program that
5423 the other packages may use to modify the
5424 configuration file.</p>
5428 the related packages must use the provided program
5429 to make any modifications to the configuration file.
5430 They should either depend on the core package to
5431 guarantee that the configuration modifier program is
5432 available or accept gracefully that they cannot
5433 modify the configuration file if it is not.</p>
5438 Sometimes it's appropriate to create a new package which
5439 provides the basic infrastructure for the other packages
5440 and which manages the shared configuration files. (Check
5441 out the <tt>sgml-base</tt> package as an example.)</p>
5445 <heading>User configuration files ("dotfiles")</heading>
5448 Files in <tt>/etc/skel</tt> will automatically be copied
5449 into new user accounts by <prgn>adduser</prgn>. They
5450 should not be referenced there by any program.</p>
5453 Therefore, if a program needs a dotfile to exist in
5454 advance in <tt>$HOME</tt> to work sensibly, that dotfile
5455 should be installed in <tt>/etc/skel</tt> (and listed in
5456 conffiles, if it is not generated and modified dynamically
5457 by the package's installation scripts).</p>
5460 However, programs that require dotfiles in order to
5461 operate sensibly (dotfiles that they do not create
5462 themselves automatically, that is) are a bad thing, and
5463 programs should be configured by the Debian default
5464 installation as close to normal as possible.</p>
5467 Therefore, if a program in a Debian package needs to be
5468 configured in some way in order to operate sensibly that
5469 configuration should be done in a site-wide global
5470 configuration file elsewhere in <tt>/etc</tt>. Only if the
5471 program doesn't support a site-wide default configuration
5472 and the package maintainer doesn't have time to add it
5473 may a default per-user file be placed in
5474 <tt>/etc/skel</tt>.</p>
5477 <tt>/etc/skel</tt> should be as empty as we can make it.
5478 This is particularly true because there is no easy
5479 mechanism for ensuring that the appropriate dotfiles are
5480 copied into the accounts of existing users when a package
5486 <heading>Log files</heading>
5488 The traditional approach to log files has been to set up ad
5489 hoc log rotation schemes using simple shell scripts and
5490 cron. While this approach is highly customizable, it
5491 requires quite a lot of sysadmin work. Even though the
5492 original Debian system helped a little by automatically
5493 installing a system which can be used as a template, this
5494 was deemed not enough.
5498 A better scheme is to use logrotate, a GPL'd program
5499 developed by Red Hat, which centralizes log management. It
5500 has both a configuration file (<tt>/etc/logrotate.conf</tt>)
5501 and a directory where packages can drop logrotation info
5502 (<tt>/etc/logrotate.d</tt>).
5506 Log files should usually be named
5507 <tt>/var/log/<var>package</var>.log</tt>. If you have many
5508 log files, or need a separate directory for permissions
5509 reasons (<tt>/var/log</tt> is writable only by
5510 <tt>root</tt>), you should usually create a directory named
5511 <tt>/var/log/<var>package</var></tt>.</p>
5514 Log files must be rotated occasionally so
5515 that they don't grow indefinitely; the best way to do this
5516 is to drop a script into the directory
5517 <tt>/etc/logrotate.d</tt> and use the facilities provided by
5518 logrotate. Here is a good example for a logrotate config
5519 file (for more information see <manref name="logrotate"
5527 /etc/init.d/foo force-reload
5531 Which rotates all files under `/var/log/foo', saves 12
5532 compressed generations, and sends a HUP signal at the end of
5538 Log files should be removed when the package is
5539 purged (but not when it is only removed), by checking the
5540 argument to the <tt>postrm</tt> script (see the <em>Debian
5541 Packaging Manual</em> for details).</p>
5546 <heading>Permissions and owners</heading>
5549 The rules in this section are guidelines for general use.
5550 If necessary you may deviate from the details below.
5551 However, if you do so you must make sure that what is done
5552 is secure and you should try to be as consistent as possible
5553 with the rest of the system. You should probably also
5554 discuss it on <prgn>debian-devel</prgn> first.</p>
5557 Files should be owned by <tt>root.root</tt>, and made
5558 writable only by the owner and universally readable (and
5559 executable, if appropriate).</p>
5562 Directories should be mode 755 or (for group-writability)
5563 mode 2775. The ownership of the directory should be
5564 consistent with its mode--if a directory is mode 2775, it
5565 should be owned by the group that needs write access to
5569 Setuid and setgid executables should be mode 4755 or 2755
5570 respectively, and owned by the appropriate user or group.
5571 They should not be made unreadable (modes like 4711 or
5572 2711 or even 4111); doing so achieves no extra security,
5573 because anyone can find the binary in the freely available
5574 Debian package--it is merely inconvenient. For the same
5575 reason you should not restrict read or execute permissions
5576 on non-set-id executables.</p>
5579 Some setuid programs need to be restricted to particular
5580 sets of users, using file permissions. In this case they
5581 should be owned by the uid to which they are set-id, and
5582 by the group which should be allowed to execute them.
5583 They should have mode 4754; there is no point in making
5584 them unreadable to those users who must not be allowed to
5588 You must not arrange that the system administrator can only
5589 reconfigure the package to correspond to their local
5590 security policy by changing the permissions on a binary.
5591 Ordinary files installed by <prgn>dpkg</prgn> (as opposed
5592 to conffiles and other similar objects) have their
5593 permissions reset to the distributed permissions when the
5594 package is reinstalled. Instead you should consider (for
5595 example) creating a group for people allowed to use the
5596 program(s) and making any setuid executables executable
5597 only by that group.</p>
5600 If you need to create a new user or group for your package
5601 there are two possibilities. Firstly, you may need to
5602 make some files in the binary package be owned by this
5603 user or group, or you may need to compile the user or
5604 group id (rather than just the name) into the binary
5605 (though this latter should be avoided if possible, as in
5606 this case you need a statically allocated id).</p>
5609 If you need a statically allocated id, you must ask for a
5610 user or group id from the base system
5611 maintainer, and must not release the package until you
5612 have been allocated one. Once you have been allocated one
5613 you must make the package depend on a version of the base
5614 system with the id present in <tt>/etc/passwd</tt> or
5615 <tt>/etc/group</tt>, or alternatively arrange for your
5616 package to create the user or group itself with the
5617 correct id (using <tt>adduser</tt>) in its pre- or
5618 post-installation script (the latter is to be preferred if
5619 it is possible).</p>
5622 On the other hand, the program might be able to determine the
5623 uid or gid from the group name at runtime, so that a
5624 dynamic id can be used. In this case you should choose an
5625 appropriate user or group name, discussing this on
5626 <prgn>debian-devel</prgn> and checking with the base
5627 system maintainer that it is unique and that they do not
5628 wish you to use a statically allocated id instead. When
5629 this has been checked you must arrange for your package to
5630 create the user or group if necessary using
5631 <prgn>adduser</prgn> in the pre- or post-installation
5632 script (again, the latter is to be preferred if it is
5636 Note that changing the numeric value of an id associated with a name
5637 is very difficult, and involves searching the file system for all
5638 appropriate files. You need to think carefully whether a static or
5639 dynamic id is required, since changing your mind later will cause
5645 <heading>Customized programs</heading>
5647 <sect id="arch-spec">
5648 <heading>Architecture specification strings</heading>
5651 If a program needs to specify an <em>architecture specification
5652 string</em> in some place, the following format should be used:
5654 <arch>-<os>
5656 where `<arch>' is one of the following: i386, alpha, arm, m68k,
5657 powerpc, sparc and `<os>' is one of: linux, gnu. Use
5658 of <em>gnu</em> in this string is reserved for the GNU/Hurd
5659 operating system.</p>
5661 Note, that we don't want to use `<arch>-debian-linux'
5662 to apply to the rule `architecture-vendor-os' since this
5663 would make our programs incompatible to other Linux
5664 distributions. Also note, that we don't use
5665 `<arch>-unknown-linux', since the `unknown' does not
5666 look very good.</p></sect>
5670 <heading>Daemons</heading>
5673 The configuration files <tt>/etc/services</tt>,
5674 <tt>/etc/protocols</tt>, and <tt>/etc/rpc</tt> are managed
5675 by the <prgn>netbase</prgn> package and may not be modified
5676 by other packages.</p>
5679 If a package requires a new entry in one of these files, the
5680 maintainer should get in contact with the
5681 <prgn>netbase</prgn> maintainer, who will add the entries
5682 and release a new version of the <prgn>netbase</prgn>
5686 The configuration file <tt>/etc/inetd.conf</tt> must not be
5687 modified by the package's scripts except via the
5688 <prgn>update-inetd</prgn> script or the
5689 <prgn>DebianNet.pm</prgn> Perl module.</p>
5692 If a package wants to install an example entry into
5693 <tt>/etc/inetd.conf</tt>, the entry must be preceded with
5694 exactly one hash character (<tt>#</tt>). Such lines are
5695 treated as `commented out by user' by the
5696 <prgn>update-inetd</prgn> script and are not changed or
5697 activated during a package updates.</p></sect>
5701 <heading>Using pseudo-ttys and modifying wtmp, utmp and lastlog</heading>
5704 Some programs need to create pseudo-ttys. This should be done
5705 using Unix98 ptys if the C library supports it. The resulting
5706 program must not be installed setuid root, unless that
5707 is required for other functionality.
5711 The files <tt>/var/run/utmp</tt>, <tt>/var/log/wtmp</tt> and
5712 <tt>/var/log/lastlog</tt> must be installed writeable by
5713 group utmp. Programs who need to modify those files must
5714 be installed setgid utmp.
5719 <heading>Editors and pagers</heading>
5722 Some programs have the ability to launch an editor or pager
5723 program to edit or display a text document. Since there are
5724 lots of different editors and pagers available in the Debian
5725 distribution, the system administrator and each user should
5726 have the possibility to choose his/her preferred editor and
5730 In addition, every program should choose a good default
5731 editor/pager if none is selected by the user or system
5735 Thus, every program that launches an editor or pager must
5736 use the EDITOR or PAGER environment variables to determine
5737 the editor/pager the user wants to get started. If these
5738 variables are not set, the programs <tt>/usr/bin/editor</tt>
5739 and <tt>/usr/bin/pager</tt> should be used, respectively.</p>
5742 These two files are managed through `alternatives.' That is,
5743 every package providing an editor or pager must call the
5744 <prgn>update-alternatives</prgn> script to register these
5748 If it is very hard to adapt a program to make us of the
5749 EDITOR and PAGER variables, that program may be configured
5750 to use <tt>/usr/bin/sensible-editor</tt> and
5751 <tt>/usr/bin/sensible-pager</tt> as editor or pager program,
5752 respectively. These are two scripts provided in the Debian
5753 base system that check the EDITOR and PAGER variables and
5754 launch the appropriate program or fall back to
5755 <tt>/usr/bin/editor</tt> and <tt>/usr/bin/pager</tt>,
5759 A program may also use the VISUAL environment variable to
5760 determine the user's choice of editor. If it exists, it
5761 should take precedence over EDITOR. This is in fact what
5762 <tt>/usr/bin/sensible-editor</tt> does.</p>
5765 It is not required for a package to depend on
5766 `editor' and `pager', nor is it required for a package to
5767 provide such virtual packages.
5770 The Debian base system already provides an editor and
5779 <sect id="web-appl">
5780 <heading>Web servers and applications</heading>
5783 This section describes the locations and URLs that should
5784 be used by all web servers and web application in the Debian
5790 <p>Cgi-bin executable files are installed in the
5793 /usr/lib/cgi-bin/<cgi-bin-name>
5795 and should be referred to as
5797 http://localhost/cgi-bin/<cgi-bin-name>
5798 </example></p></item>
5801 <item><p>Access to html documents</p>
5804 Html documents for a package are stored in
5805 <tt>/usr/share/doc/<var>package</var></tt> but should
5806 be accessed via symlinks as
5807 <tt>/usr/doc/<var>package</var></tt><footnote> for
5808 backward compatibility, see <ref id="usrdoc"></footnote>
5809 and can be referred to as
5811 http://localhost/doc/<package>/<filename>
5812 </example></p></item>
5815 <item><p>Web Document Root</p>
5818 Web Applications should try to avoid storing files in
5819 the Web Document Root. Instead they should use the
5820 /usr/share/doc/<package> directory for documents and
5821 register the Web Application via the menu package. If
5822 access to the web-root is unavoidable then use
5826 as the Document Root. This might be just a
5827 symbolic link to the location where the sysadmin has
5828 put the real document root.</p>
5831 </enumlist></p></sect>
5835 <heading>Mail transport, delivery and user agents</heading>
5838 Debian packages which process electronic mail, whether
5839 mail-user-agents (MUAs) or mail-transport-agents (MTAs),
5840 must make sure that they are compatible with the
5841 configuration decisions below. Failure to do this may
5842 result in lost mail, broken <tt>From:</tt> lines, and other
5843 serious brain damage!</p>
5846 The mail spool is <tt>/var/spool/mail</tt> and the interface
5847 to send a mail message is <tt>/usr/sbin/sendmail</tt> (as
5848 per the FHS). The mail spool is part of the base system
5849 and not part of the MTA package.</p>
5852 All Debian MUAs, MTAs, MDAs and other mailbox accessing
5853 programs (like IMAP daemons) must lock the mailbox in an
5854 NFS-safe way. This means that <tt>fcntl()</tt> locking must
5855 be combined with dot locking. To avoid deadlocks, a
5856 program should use <tt>fcntl()</tt> first and dot locking
5857 after this or alternatively implement the two locking
5858 methods in a non blocking way<footnote>
5860 If it is not possible to establish both locks, the
5861 system shouldn't wait for the second lock to be
5862 established, but remove the first lock, wait a (random)
5863 time, and start over locking again.</p>
5864 </footnote>. Using the functions <tt>maillock</tt> and
5865 <tt>mailunlock</tt> provided by the
5866 <tt>liblockfile*</tt><footnote>
5868 <tt>liblockfile</tt> version >>1.01</p>
5869 </footnote> packages is the recommended way to realize this.
5873 Mailboxes are generally 660 <tt><var>user</var>.mail</tt>
5874 unless the user has chosen otherwise. A MUA may remove a
5875 mailbox (unless it has nonstandard permissions) in which
5876 case the MTA or another MUA must recreate it if needed.
5877 Mailboxes must be writable by group mail.</p>
5880 The mail spool is 2775 <tt>root.mail</tt>, and MUAs should
5881 be setgid mail to do the locking mentioned above (and
5882 must obviously avoid accessing other users' mailboxes
5883 using this privilege).</p>
5886 <tt>/etc/aliases</tt> is the source file for the system mail
5887 aliases (e.g., postmaster, usenet, etc.)--it is the one
5888 which the sysadmin and <tt>postinst</tt> scripts may edit.
5889 After <tt>/etc/aliases</tt> is edited the program or human
5890 editing it must call <prgn>newaliases</prgn>. All MTA
5891 packages must come with a <prgn>newaliases</prgn> program,
5892 even if it does nothing, but older MTA packages do not do
5893 this so programs should not fail if <prgn>newaliases</prgn>
5894 cannot be found.</p>
5897 The convention of writing <tt>forward to
5898 <var>address</var></tt> in the mailbox itself is not
5899 supported. Use a <tt>.forward</tt> file instead.</p>
5902 The <prgn>rmail</prgn> program used by UUCP
5903 for incoming mail should be <tt>/usr/sbin/rmail</tt>.
5904 Likewise, <prgn>rsmtp</prgn>, for receiving
5905 batch-SMTP-over-UUCP, should be <tt>/usr/sbin/rsmtp</tt> if it
5909 If you need to know what name to use (for example) on
5910 outgoing news and mail messages which are generated locally,
5911 you should use the file <tt>/etc/mailname</tt>. It will
5912 contain the portion after the username and <tt>@</tt> (at)
5913 sign for email addresses of users on the machine (followed
5917 A package should check for the existence of this file. If
5918 it exists it should use it without comment. (An MTA's
5919 prompting configuration script may wish to prompt the user
5920 even if it finds this file exists.) If it does not exist it
5921 should prompt the user for the value and store it in
5922 <tt>/etc/mailname</tt> as well as using it in the package's
5923 configuration. The prompt should make it clear that the
5924 name will not just be used by that package. For example, in
5925 this situation the INN package says:
5927 Please enter the `mail name' of your system. This is the
5928 hostname portion of the address to be shown on outgoing
5929 news and mail messages. The default is
5930 <var>syshostname</var>, your system's host name. Mail
5931 name [`<var>syshostname</var>']:
5933 where <var>syshostname</var> is the output of <tt>hostname
5934 --fqdn</tt>.</p></sect>
5938 <heading>News system configuration</heading>
5941 All the configuration files related to the NNTP (news)
5942 servers and clients should be located under
5943 <tt>/etc/news</tt>.</p>
5946 There are some configuration issues that apply to a number
5947 of news clients and server packages on the machine. These
5951 <tag>/etc/news/organization</tag>
5952 <item><p>A string which should appear as the
5953 organization header for all messages posted
5954 by NNTP clients on the machine</p></item>
5956 <tag>/etc/news/server</tag>
5957 <item><p>Contains the FQDN of the upstream NNTP
5958 server, or localhost if the local machine is
5959 an NNTP server.</p></item>
5962 Other global files may be added as required for cross-package news
5963 configuration.</p></sect>
5967 <heading>Programs for the X Window System</heading>
5970 <em>Programs that may be configured with support for the X Window
5971 System</em> must be configured to do so and must declare any
5972 package dependencies necessary to satisfy their runtime
5973 requirements when using the X Window System, unless the package
5974 in question is of standard or higher priority, in which case
5975 X-specific binaries may be split into a separate package, or
5976 alternative versions of the package with X support may be
5982 <em>Packages which provide an X server</em> that, directly or
5983 indirectly, communicates with real input and display hardware
5984 should declare in their control data that they provide the
5985 virtual package <tt>xserver</tt>.
5988 This implements current practice, and provides an actual
5989 policy for usage of the "xserver" virtual package which
5990 appears in the virtual packages list. In a nutshell, X
5991 servers that interface directly with the display and input
5992 hardware or via another subsystem (e.g., GGI) should provide
5993 xserver. Things like Xvfb, Xnest, and Xprt should not.
5999 <em>Packages that provide a terminal emulator</em> for the X
6000 Window System which support a terminal type with a terminfo
6001 description provided in the <tt>ncurses-base</tt> package
6002 should declare in their control data that they provide the
6003 virtual package <tt>x-terminal-emulator</tt>. They should
6004 also register themselves as an alternative for
6005 <tt>/usr/bin/x-terminal-emulator</tt>, with a priority of
6010 <em>Packages that provide window managers</em> should declare in
6011 their control data that they provide the virtual package
6012 <tt>x-window-manager</tt>. They should also register themselves as an
6013 alternative for <tt>/usr/bin/x-window-manager</tt>, with a priority
6014 calculated as follows:
6016 <item>Start with a priority of 20.</item>
6017 <item>If the window manager supports the Debian menu system,
6018 add 20 points if this support is available in the
6019 package's default configuration (i.e., no
6020 configuration files belonging to the system or user
6021 have to be edited to activate the feature); if
6022 configuration files must be modified, add only 10
6024 <item>If the window manager permits the X session to be
6025 restarted using a <em>different</em> window manager
6026 (without killing the X server) in its default
6027 configuration, add 10 points; otherwise add
6033 <em>Packages that provide fonts for the X Window System</em>
6034 must do a number of things to ensure that they are both
6035 available without modification of the X or font server
6036 configuration, and that they do not corrupt files used by
6037 other font packages to register information about themselves.
6040 Fonts of any type supported by the X Window System
6041 should be be in a separate binary package from any
6042 executables, libraries, or documentation (except that
6043 specific to the fonts shipped); if a program or
6044 library is <em>unusable</em> without one or more
6045 specific fonts, the package containing the program or
6046 library should declare a dependency on the package(s)
6047 containing the font(s) it requires.
6050 BDF fonts should be converted to PCF fonts with the
6051 <tt>bdftopcf</tt> utility (available in the
6052 <tt>xutils</tt> package, <tt>gzip</tt>ped, and
6053 placed in a directory that corresponds to their
6057 100 dpi fonts should be placed in
6058 <tt>/usr/X11R6/lib/X11/fonts/100dpi/</tt>.
6061 75 dpi fonts should be placed in
6062 <tt>/usr/X11R6/lib/X11/fonts/75dpi/</tt>.
6065 Character-cell fonts, cursor fonts, and other
6066 low-resolution fonts should be placed in
6067 <tt>/usr/X11R6/lib/X11/fonts/misc/</tt>.
6072 Speedo fonts should be placed in
6073 <tt>/usr/X11R6/lib/X11/fonts/Speedo/</tt>.
6076 Type 1 fonts should be placed in
6077 <tt>/usr/X11R6/lib/X11/fonts/Type1/</tt>. If font
6078 metric files are available, they may be placed here as
6082 Subdirectories of <tt>/usr/X11R6/lib/X11/fonts/</tt>
6083 other than those listed above should be neither created nor
6084 used. (The <tt>PEX</tt> and <tt>cyrillic</tt> directories are
6085 excepted for historical reasons, but installation of files into
6086 these directories remains discouraged.)
6089 Font packages may, instead of placing files directly in
6090 the X font directories listed above, provide symbolic links in
6091 the font directory which point to the files' actual location
6092 in the filesystem. Such a location should comply with the
6096 Font packages should not contain both 75dpi and 100dpi
6097 versions of a font. If both are available, they should be
6098 provided in separate binary packages with "-75dpi" or "-100dpi"
6099 appended to the names of the packages containing the
6100 corresponding fonts.
6103 Fonts destined for the <tt>misc</tt> subdirectory should
6104 not be included in the same package as 75dpi or 100dpi fonts;
6105 instead, they should be provided in a separate package with
6106 "-misc" appended to its name.
6109 Font packages <em>must not</em> provide the files
6110 <tt>fonts.dir</tt>, <tt>fonts.alias</tt>, or
6111 <tt>fonts.scale</tt> in a font directory.
6114 <tt>fonts.dir</tt> files must not be provided at
6118 <tt>fonts.alias</tt> and <tt>fonts.scale</tt>
6119 files, if needed, should be provided in the
6121 <tt>/etc/X11/fonts/<em>fontdir</em>/<em>package</em>.<em>extension</em></tt>,
6122 where <em>fontdir</em> is the name of the
6124 <tt>/usr/X11R6/lib/X11/fonts/</tt> where the
6125 package's corresponding fonts are stored (e.g.,
6126 <tt>75dpi</tt> or <tt>misc</tt>),
6127 <em>package</em> is the name of the package that
6128 provides these fonts, and <em>extension</em> is
6129 either <tt>scale</tt> or <tt>alias</tt>,
6130 whichever corresponds to the file
6136 Font packages must declare a dependency on
6137 <tt>xutils</tt> and, in the package
6138 post-installation and post-removal scripts, invoke the
6139 <tt>mkfontdir</tt> command on each directory into
6140 which they installed fonts.
6143 Font packages that provide one or more
6144 <tt>fonts.scale</tt> files as described above must declare a
6145 versioned dependency on <tt>xutils (>=
6146 4.0.2)</tt> and invoke <tt>update-fonts-scale</tt> on each
6147 directory into which they installed fonts
6148 <em>before</em> invoking <tt>mkfontdir</tt> on that
6149 directory. This invocation must occur in both the
6150 post-installation and post-removal scripts.
6153 Font packages that provide one or more
6154 <tt>fonts.alias</tt> files as described above must
6155 declare a versioned dependency on <tt>xutils
6156 (>= 4.0.2)</tt> and, in the package
6157 post-installation and post-removal scripts, invoke
6158 <tt>update-fonts-alias</tt> on each directory into
6159 which they installed fonts.
6162 Font packages must not provide alias names for the
6163 fonts they include which collide with alias names already in
6164 use by fonts already packaged.
6167 Font packages must not provide fonts with the same XLFD
6168 registry name as another font already packaged.
6174 <em>Application defaults</em> files must be installed in the
6175 directory <tt>/usr/X11R6/lib/X11/app-defaults/</tt>.
6177 <p>Note: This shall change very shortly.</p>
6179 They should not be registered as <em>conffile</em>s or
6180 otherwise treated as configuration files. Customization of
6181 programs' X resources may be supported with the provision of
6182 a file with the same name as that of the package placed in
6183 the <tt>/etc/X11/Xresources/</tt> directory, which must
6184 registered as a <em>conffile</em>. <em>Important:</em>
6185 packages that install files into the
6186 <tt>/etc/X11/Xresources/</tt> directory <em>must</em>
6187 declare a conflict with <tt>xbase (<<
6188 3.3.2.3a-2)</tt>; if this is not done it is possible for the
6189 installing package to destroy a previously-existing
6190 <tt>/etc/X11/Xresources</tt> <em>file</em> which had been
6191 customized by the system administrator.
6193 <p>Rationale: clarifies the language to properly
6194 address the package maintainer, not the system
6195 administrator, as to how to manage
6196 /etc/X11/Xresources.</p>
6202 <em>Packages using the X Window System should abide by the FHS
6203 standard whenever possible</em>; they should install binaries,
6204 libraries, manual pages, and other files in FHS-mandated
6205 locations wherever possible. This means that files must
6206 not be installed into <tt>/usr/X11R6/bin/</tt>,
6207 <tt>/usr/X11R6/lib/</tt>, or <tt>/usr/X11R6/man/</tt> unless
6208 this is necessary for the package to operate properly.
6209 Configuration files for window managers and display managers
6210 should be placed in a subdirectory of <tt>/etc/X11/</tt>
6211 corresponding to the package name due to these programs'
6212 tight integration with the mechanisms of the X Window
6213 System. Application-level programs should use the
6214 <tt>/etc/</tt> directory unless otherwise mandated by
6215 policy. The installation of files into subdirectories of
6216 <tt>/usr/X11R6/include/X11/</tt> and
6217 <tt>/usr/X11R6/lib/X11/</tt> is permitted but discouraged;
6218 package maintainers should determine if subdirectories of
6219 <tt>/usr/lib/</tt> and <tt>/usr/share/</tt> can be used
6220 instead (symlinks from the X11R6 directories to
6221 FHS-compliant locations is encouraged if the program is not
6222 easily configured to look elsewhere for its files).
6223 Packages must not provide -- or install files into -- the
6224 directories <tt>/usr/bin/X11/</tt>,
6225 <tt>/usr/include/X11/</tt>, or <tt>/usr/lib/X11/</tt>.
6226 Files within a package should, however, make reference to
6227 these directories, rather than their X11R6-named
6228 counterparts <tt>/usr/X11R6/bin/</tt>,
6229 <tt>/usr/X11R6/include/X11/</tt>, and
6230 <tt>/usr/X11R6/lib/X11/</tt>, if the resources being
6231 referred to have not been moved to FHS-compliant locations.
6235 <em>Programs that require the non-DFSG-compliant OSF/Motif
6236 library</em> should be compiled against and tested with
6237 LessTif (a free re-implementation of Motif) instead. If the
6238 maintainer judges that the program or programs do not work
6239 sufficiently well with LessTif to be distributed and
6240 supported, but do so when compiled against Motif, then two
6241 versions of the package should be created; one linked
6242 statically against Motif and with <tt>-smotif</tt> appended
6243 to the package name, and one linked dynamically against
6244 Motif and with <tt>-dmotif</tt> appended to the package
6245 name. Both Motif-linked versions are dependent upon
6246 non-DFSG-compliant software and thus cannot be uploaded to
6247 the main distribution; if the software is itself
6248 DFSG-compliant it may be uploaded to the contrib
6249 distribution. While known existing versions of OSF/Motif
6250 permit unlimited redistribution of binaries linked against
6251 the library (whether statically or dynamically), it is the
6252 package maintainer's responsibility to determine whether
6253 this is permitted by the license of the copy of OSF/Motif in
6254 his or her possession.
6260 <heading>Emacs lisp programs</heading>
6263 Please refer to the `Debian Emacs Policy' (documented in
6264 <tt>debian-emacs-policy.gz</tt> of the
6265 <prgn>emacsen-common</prgn> package) for details of how to
6266 package emacs lisp programs.</p></sect>
6270 <heading>Games</heading>
6273 The permissions on /var/games are 755
6274 <tt>root.root</tt>.</p>
6277 Each game decides on its own security policy.</p>
6280 Games which require protected, privileged access to
6281 high-score files, savegames, etc., may be made
6282 set-<em>group</em>-id (mode 2755) and owned by
6283 <tt>root.games</tt>, and use files and directories with
6284 appropriate permissions (770 <tt>root.games</tt>, for
6285 example). They must not be made
6286 set-<em>user</em>-id, as this causes security problems. (If
6287 an attacker can subvert any set-user-id game they can
6288 overwrite the executable of any other, causing other players
6289 of these games to run a Trojan horse program. With a
6290 set-group-id game the attacker only gets access to less
6291 important game data, and if they can get at the other
6292 players' accounts at all it will take considerably more
6296 Some packages, for example some fortune cookie programs, are
6297 configured by the upstream authors to install with their
6298 data files or other static information made unreadable so
6299 that they can only be accessed through set-id programs
6300 provided. You should not do this in a Debian package: anyone can
6301 download the <tt>.deb</tt> file and read the data from it,
6302 so there is no point making the files unreadable. Not
6303 making the files unreadable also means that you don't have
6304 to make so many programs set-id, which reduces the risk of a
6308 As described in the FHS, binaries of games should be
6309 installed in the directory <tt>/usr/games</tt>. This also
6310 applies to games that use the X Window System. Manual pages
6311 for games (X and non-X games) should be installed in
6312 <tt>/usr/share/man/man6</tt>.</p>
6316 <chapt><heading>Documentation</heading>
6320 <heading>Manual pages</heading>
6323 You should install manual pages in <prgn>nroff</prgn> source
6324 form, in appropriate places under <tt>/usr/share/man</tt>. You
6325 should only use sections 1 to 9 (see the FHS for more
6326 details). You must not install a preformatted `cat
6330 Each program, utility, and function should have an
6331 associated manpage included in the same package. It is
6332 suggested that all configuration files also have a manual
6333 page included as well.
6337 If no manual page is available for a particular program,
6338 utility, function or configuration file and this is reported as a bug on
6339 debian-bugs, a symbolic link from the requested manual page
6340 to the <manref name="undocumented" section="7"> manual page
6341 may be provided. This symbolic link can be created from
6342 <tt>debian/rules</tt> like this:
6344 ln -s ../man7/undocumented.7.gz \
6345 debian/tmp/usr/share/man/man[1-9]/the_requested_manpage.[1-9].gz
6347 This manpage claims that the lack of a manpage has been
6348 reported as a bug, so you may only do this if it really has
6349 (you can report it yourself, if you like). Do not close the
6350 bug report until a proper manpage is available.</p>
6353 You may forward a complaint about a missing manpage to the
6354 upstream authors, and mark the bug as forwarded in the
6355 Debian bug tracking system. Even though the GNU Project do
6356 not in general consider the lack of a manpage to be a bug,
6357 we do--if they tell you that they don't consider it a bug
6358 you should leave the bug in our bug tracking system open
6362 Manual pages should be installed compressed using <tt>gzip
6366 If one manpage needs to be accessible via several names it
6367 is better to use a symbolic link than the <tt>.so</tt>
6368 feature, but there is no need to fiddle with the relevant
6369 parts of the upstream source to change from <tt>.so</tt> to
6370 symlinks--don't do it unless it's easy. You should not create hard
6371 links in the manual page directories, nor put
6372 absolute filenames in <tt>.so</tt> directives. The filename
6373 in a <tt>.so</tt> in a manpage should be relative to the
6374 base of the manpage tree (usually
6375 <tt>/usr/share/man</tt>).</p></sect>
6379 <heading>Info documents</heading>
6382 Info documents should be installed in <tt>/usr/share/info</tt>.
6383 They should be compressed with <tt>gzip -9</tt>.</p>
6386 Your package should call <prgn>install-info</prgn> to update the Info
6388 file, in its post-installation script:
6390 install-info --quiet --section Development Development \
6391 /usr/share/info/foobar.info
6395 It is a good idea to specify a section for the location of
6396 your program; this is done with the <tt>--section</tt>
6397 switch. To determine which section to use, you should look
6398 at <tt>/usr/share/info/dir</tt> on your system and choose the most
6399 relevant (or create a new section if none of the current
6400 sections are relevant). Note that the <tt>--section</tt>
6401 flag takes two arguments; the first is a regular expression
6402 to match (case-insensitively) against an existing section,
6403 the second is used when creating a new one.</p>
6406 You should remove the entries in the pre-removal script:
6408 install-info --quiet --remove /usr/share/info/foobar.info
6412 If <prgn>install-info</prgn> cannot find a description entry
6413 in the Info file you must supply one. See <manref
6414 name="install-info" section="8"> for details.</p>
6418 <heading>Additional documentation</heading>
6421 Any additional documentation that comes with the package may
6422 be installed at the discretion of the package maintainer.
6423 Text documentation should be installed in a directory
6424 <tt>/usr/share/doc/<var>package</var></tt>, where
6425 <var>package</var> is the name of the package, and
6426 compressed with <tt>gzip -9</tt> unless it is small.</p>
6429 If a package comes with large amounts of documentation which
6430 many users of the package will not require you should create
6431 a separate binary package to contain it, so that it does not
6432 take up disk space on the machines of users who do not need
6433 or want it installed.</p>
6436 It is often a good idea to put text information files
6437 (<tt>README</tt>s, changelogs, and so forth) that come with
6438 the source package in <tt>/usr/share/doc/<var>package</var></tt>
6439 in the binary package. However, you don't need to install
6440 the instructions for building and installing the package, of
6444 Files in <tt>/usr/share/doc</tt> should not be referenced by
6445 any program, and the system administrator should be able to
6446 delete them without causing any programs to break. Any files
6447 that are referenced by programs but are also useful as
6448 standalone documentation should be installed under
6449 <tt>/usr/share/<package>/</tt> and symlinked in
6450 <tt>/usr/share/doc/<package>/</tt>.
6456 <heading>Accessing the documentation</heading>
6459 Former Debian releases placed all additional documentation
6460 in <tt>/usr/doc/<var>package</var></tt>. To realize a
6462 <tt>/usr/share/doc/<var>package</var></tt>, each package
6463 must maintain a symlink <tt>/usr/doc/<var>package</var></tt>
6464 that points to the new location of its documentation in
6465 <tt>/usr/share/doc/<var>package</var></tt><footnote>These
6466 symlinks will be removed in the future, but they have to be
6467 there for compatibility reasons until all packages have
6468 moved and the policy is changed accordingly.</footnote>.
6469 The symlink must be created when the package is installed;
6470 it cannot be contained in the package itself due to problems
6471 with <prgn>dpkg</prgn>. One reasonable way to accomplish
6472 this is to put the following in the package's
6473 <prgn>postinst</prgn>:
6475 if [ "$1" = "configure" ]; then
6476 if [ -d /usr/doc -a ! -e /usr/doc/#PACKAGE# \
6477 -a -d /usr/share/doc/#PACKAGE# ]; then
6478 ln -sf ../share/doc/#PACKAGE# /usr/doc/#PACKAGE#
6482 And the following in the package's <prgn>prerm</prgn>:
6484 if [ \( "$1" = "upgrade" -o "$1" = "remove" \) \
6485 -a -L /usr/doc/#PACKAGE# ]; then
6486 rm -f /usr/doc/#PACKAGE#
6493 <heading>Preferred documentation formats</heading>
6496 The unification of Debian documentation is being carried out
6500 If your package comes with extensive documentation in a
6501 mark up format that can be converted to various other formats
6502 you should if possible ship HTML versions in a binary
6503 package, in the directory
6504 <tt>/usr/share/doc/<var>appropriate package</var></tt> or its
6507 <p>The rationale: The important thing here is that HTML
6508 docs should be available in <em>some</em> package, not
6509 necessarily in the main binary package, though. </p>
6514 Other formats such as PostScript may be provided at your
6518 <sect id="copyrightfile">
6519 <heading>Copyright information</heading>
6522 Every package must be accompanied by a verbatim copy of its
6523 copyright and distribution license in the file
6524 /usr/share/doc/<package-name>/copyright. This file must
6525 neither be compressed nor be a symbolic link.</p>
6528 In addition, the copyright file must say where the upstream
6529 sources (if any) were obtained, and should explain briefly what
6530 modifications were made in the Debian version of the package
6531 compared to the upstream one. It should name the original
6532 authors of the package and the Debian maintainer(s) who were
6533 involved with its creation.</p>
6536 A copy of the file which will be installed in
6537 <tt>/usr/share/doc/<var>package</var>/copyright</tt> should be
6538 in <tt>debian/copyright</tt>.</p>
6542 /usr/share/doc/<package-name> may be a symbolic link to a
6543 directory in /usr/share/doc only if two packages both come from
6544 the same source and the first package has a "Depends"
6545 relationship on the second. These rules are important
6546 because copyrights must be extractable by mechanical
6550 Packages distributed under the UCB BSD license, the Artistic
6551 license, the GNU GPL, and the GNU LGPL should refer to the
6552 files /usr/share/common-licenses/BSD,
6553 /usr/share/common-licenses/Artistic,
6554 /usr/share/common-licenses/GPL, and
6555 /usr/share/common-licenses/LGPL.
6558 Why "licenses" and not "copyright"? Because
6559 <tt>/usr/doc/copyright</tt> used to contain all the
6560 copyright files, plus the four common licenses GPL,
6561 LGPL, Artistic and BSD. Now individual copyright files
6562 for packages are no longer in a common directory. Once
6563 <tt>/usr/doc/copyright</tt> is almost empty it makes
6564 sense to rename "copyright" to "licenses"
6567 Why "common-licenses" and not "licenses"? Because if I
6568 put just "licenses" I'm sure I will receive a bug report
6569 saying "license foo is not included in the licenses
6570 directory. They are not all the licenses, just a few
6571 common ones. I could use /usr/share/doc/common-licenses
6572 but I think this is too long, and, after all, the GPL
6573 does not "document" anything, it is merely a license.
6579 You should not use the copyright file as a general <tt>README</tt>
6580 file. If your package has such a file it should be
6581 installed in <tt>/usr/share/doc/<var>package</var>/README</tt> or
6582 <tt>README.Debian</tt> or some other appropriate place.</p>
6586 <heading>Examples</heading>
6589 Any examples (configurations, source files, whatever),
6590 should be installed in a directory
6591 <tt>/usr/share/doc/<var>package</var>/examples</tt>. These
6592 files should not be referenced by any program--they're there
6593 for the benefit of the system administrator and users, as
6594 documentation only. Architecture-specific example files
6595 should be installed in a directory
6596 <tt>/usr/lib/<var>package</var>/examples</tt>, and files in
6597 <tt>/usr/share/doc/<var>package</var>/examples</tt> symlink
6598 to files in it. Or the latter directory may be a symlink to
6602 <sect id="instchangelog">
6603 <heading>Changelog files</heading>
6606 Packages that are not Debian-native must contain a copy of
6607 <tt>debian/changelog</tt> file from the Debian source tree
6608 in <tt>/usr/share/doc/<var>package</var></tt> as
6609 <tt>changelog.Debian.gz</tt>. If an upstream changelog is
6610 available, it should be accessible as
6611 <tt>/usr/share/doc/<var>package</var>/changelog.gz</tt> in
6612 plain text. If the upstream changelog is distributed in
6613 HTML, it should be made available in that form as
6614 <tt>/usr/share/doc/<var>package</var>/changelog.html.gz</tt>
6615 and the <tt>changelog.gz</tt> should be generated using, eg,
6616 <tt>lynx -dump -nolist</tt>. If the upstream changelog files
6617 do not already conform to this naming convention, then this
6618 may be achieved either by renaming the files, or adding a
6619 symbolic link, at the maintainer's discretion.
6622 Rationale: People should not have to look into two
6623 places for upstream changelogs merely because they are
6631 All these files should be installed compressed using <tt>gzip -9</tt>,
6632 as they will become large with time even if they start out
6637 If the package has only one changelog which is used both as
6638 the Debian changelog and the upstream one because there is
6639 no separate upstream maintainer then that changelog should
6640 usually be installed as
6641 <tt>/usr/share/doc/<var>package</var>/changelog.gz</tt>; if
6642 there is a separate upstream maintainer, but no upstream
6643 changelog, then the Debian changelog should still be called
6644 <tt>changelog.Debian.gz</tt>.</p>