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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 and 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>jdg@debian.org</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-licenses/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 General 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 and 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 therefore should not be changed without peer
137 review. Package maintainers can then rely on this
138 interfaces not changing, and the package
139 management software authors need to ensure
140 compatibility with these interface
141 definitions. (Control file and and changelog file
142 formats are examples.)
145 <tag>Chosen Convention</tag>
148 If there are a number of technically viable choices
149 that can be made, but one needs to select one of
150 these options for inter-operability. The version
151 number format is one example.
155 Please note that these are not mutually exclusive;
156 selected conventions often become parts of standard
163 The footnotes present in this manual are
164 merely informative, and are not part of Debian policy itself.
169 In this manual, the words <em>must</em>, <em>should</em> and
170 <em>may</em>, and the adjectives <em>required</em>,
171 <em>recommended</em> and <em>optional</em>, are used to
172 distinguish the significance of the various guidelines in
173 this policy document. Packages that do not conform the the
174 guidelines denoted by <em>must</em> (or <em>required</em>)
175 will generally not be considered acceptable for the Debian
176 distribution. Non-conformance with guidelines denoted by
177 <em>should</em> (or <em>recommended</em>) will generally be
178 considered a bug, but will not necessarily render a package
179 unsuitable for distribution. Guidelines denoted by
180 <em>may</em> (or <em>optional</em>) are truly optional and
181 adherence is left to the maintainer's discretion.
184 These classifications are roughly equivalent to the bug
185 severities <em>serious</em> (for <em>must</em> or
186 <em>required</em> directive violations), <em>minor</em>,
187 <em>normal</em> or <em>important</em>
188 (for <em>should</em> or <em>recommended</em> directive
189 violations) and <em>wishlist</em> (for <em>optional</em>
191 <p>Compare RFC 2119. Note, however, that these words are
192 used in a different way in this document.</p>
196 Much of the information presented in this manual will be
197 useful even when building a package which is to be
198 distributed in some other way or is intended for local use
203 <heading>New versions of this document</heading>
205 The current version of this document is always accessible
206 from the Debian FTP server <ftpsite>ftp.debian.org</ftpsite>
208 <ftppath>/debian/doc/package-developer/policy.txt.gz</ftppath>
209 (also available from the same directory are several other
210 formats: <tt>policy.html.tar.gz</tt>, <tt>policy.pdf.gz</tt>
211 and <tt>policy.ps.gz</tt>) or from the <url
212 id="http://www.debian.org/doc/debian-policy/" name="Debian
213 Policy Manual"> webpage.</p>
216 In addition, this manual is distributed via the Debian package
217 <tt>debian-policy</tt>.
221 The <tt>debian-policy</tt> package also includes the file
222 <tt>upgrading-checklist.txt</tt> which indicates policy
223 changes between versions of this document.
227 <heading>Feedback</heading>
230 As the Debian GNU/Linux system is continuously evolving this
234 While the authors of this document have tried hard to avoid
235 typos and other errors, these do still occur. If you discover
236 an error in this manual or if you want to give any
237 comments, suggestions, or criticisms please send an email to
238 the Debian Policy List,
239 <email>debian-policy@lists.debian.org</email>, or submit a
240 bug report against the <tt>debian-policy</tt> package.
245 <heading>The Debian Archive</heading>
247 The Debian GNU/Linux system is maintained and distributed as a
248 collection of <em>packages</em>. Since there are so many of
249 them (currently well over 6000), they are split into
250 <em>sections</em> and given <em>priorities</em> to simplify
251 the handling of them.
254 The effort of the Debian project is to build a free operating
255 system, but not every package we want to make accessible is
256 <em>free</em> in our sense (see the Debian Free Software
257 Guidelines, below), or may be imported/exported without
258 restrictions. Thus, the archive is split into the sections
259 <em>main</em>, <em>non-free</em>, <em>contrib</em>,
260 <em>non-US/main</em>, <em>non-US/non-free</em>, and
261 <em>non-US/contrib</em>. The sections are explained in detail
266 The <em>main</em> and the <em>non-US/main</em> sections
267 together form the <em>Debian GNU/Linux distribution</em>.
271 Packages in the other sections are not considered to be part
272 of the Debian distribution, although we support their use and
273 provide infrastructure for them (such as our bug-tracking
274 system and mailing lists). This Debian Policy Manual applies
275 to these packages as well.</p>
277 <sect id="pkgcopyright">
278 <heading>Package copyright and sections</heading>
280 The aims of this section are:
282 <list compact="compact">
284 <p>to allow us to make as much software available as we
288 <p>to allow us to encourage everyone to write free
292 <p>to allow us to make it easy for people to produce
293 CD-ROMs of our system without violating any licenses,
294 import/export restrictions, or any other laws.</p>
299 <heading>The Debian Free Software Guidelines</heading>
301 The Debian Free Software Guidelines (DFSG) form our
302 definition of `free software'. These are:
304 <tag>Free Redistribution
308 The license of a Debian component may not restrict any
309 party from selling or giving away the software as a
310 component of an aggregate software distribution
311 containing programs from several different
312 sources. The license may not require a royalty or
313 other fee for such sale.
320 The program must include source code, and must allow
321 distribution in source code as well as compiled form.
328 The license must allow modifications and derived
329 works, and must allow them to be distributed under the
330 same terms as the license of the original software.
333 <tag>Integrity of The Author's Source Code
337 The license may restrict source-code from being
338 distributed in modified form <em>only</em> if the
339 license allows the distribution of ``patch files''
340 with the source code for the purpose of modifying the
341 program at build time. The license must explicitly
342 permit distribution of software built from modified
343 source code. The license may require derived works to
344 carry a different name or version number from the
345 original software. (This is a compromise. The Debian
346 Project encourages all authors to not restrict any
347 files, source or binary, from being modified.)
350 <tag>No Discrimination Against Persons or Groups
354 The license must not discriminate against any person
358 <tag>No Discrimination Against Fields of Endeavor
362 The license must not restrict anyone from making use
363 of the program in a specific field of endeavor. For
364 example, it may not restrict the program from being
365 used in a business, or from being used for genetic
369 <tag>Distribution of License
373 The rights attached to the program must apply to all
374 to whom the program is redistributed without the need
375 for execution of an additional license by those
379 <tag>License Must Not Be Specific to Debian
383 The rights attached to the program must not depend on
384 the program's being part of a Debian system. If the
385 program is extracted from Debian and used or
386 distributed without Debian but otherwise within the
387 terms of the program's license, all parties to whom
388 the program is redistributed must have the same
389 rights as those that are granted in conjunction with
393 <tag>License Must Not Contaminate Other Software
397 The license must not place restrictions on other
398 software that is distributed along with the licensed
399 software. For example, the license must not insist
400 that all other programs distributed on the same medium
401 must be free software.
404 <tag>Example Licenses
408 The ``GPL,'' ``BSD,'' and ``Artistic'' licenses are
409 examples of licenses that we consider <em>free</em>.
416 <heading>The main section</heading>
418 Every package in <em>main</em> and <em>non-US/main</em>
419 must comply with the DFSG (Debian Free Software
423 In addition, the packages in <em>main</em>
424 <list compact="compact">
427 must not require a package outside of <em>main</em>
428 for compilation or execution (thus, the package must
429 not declare a "Depends", "Recommends", or
430 "Build-Depends" relationship on a non-<em>main</em>
436 must not be so buggy that we refuse to support them,
442 must meet all policy requirements presented in this
449 Similarly, the packages in <em>non-US/main</em>
450 <list compact="compact">
453 must not require a package outside of <em>main</em>
454 or <em>non-US/main</em> for compilation or
460 must not be so buggy that we refuse to support them,
465 must meet all policy requirements presented in this
473 <heading>The contrib section</heading>
475 Every package in <em>contrib</em> and
476 <em>non-US/contrib</em> must comply with the DFSG.
480 In addition, the packages in <em>contrib</em> and
481 <em>non-US/contrib</em>
482 <list compact="compact">
485 must not be so buggy that we refuse to support them,
491 must meet all policy requirements presented in this
499 Furthermore, packages in <em>contrib</em> must not require
500 a package in a <em>non-US</em> section for compilation or
505 Examples of packages which would be included in
506 <em>contrib</em> or <em>non-US/contrib</em> are:
507 <list compact="compact">
510 free packages which require <em>contrib</em>,
511 <em>non-free</em> packages or packages which are not
512 in our archive at all for compilation or execution,
518 wrapper packages or other sorts of free accessories for
526 <heading>The non-free section</heading>
528 Packages must be placed in <em>non-free</em> or
529 <em>non-US/non-free</em> if they are not compliant with
530 the DFSG or are encumbered by patents or other legal
531 issues that make their distribution problematic.
534 In addition, the packages in <em>non-free</em> and
535 <em>non-US/non-free</em>
536 <list compact="compact">
539 must not be so buggy that we refuse to support them,
545 must meet all policy requirements presented in this
546 manual that it is possible for them to meet.
549 It is possible that there are policy
550 requirements which the package is unable to
551 meet, for example, if the source is
552 unavailable. These situations will need to be
553 handled on a case-by-case basis.
563 <heading>The non-US sections</heading>
565 Some programs with cryptographic program code need to be
566 stored on the <em>non-US</em> server because of United
567 States export restrictions. Such programs must be
568 distributed in the appropriate <em>non-US</em> section,
569 either <em>non-US/main</em>, <em>non-US/contrib</em> or
570 <em>non-US/non-free</em>.
573 This applies only to packages which contain cryptographic
574 code. A package containing a program with an interface to
575 a cryptographic program or a program that's dynamically
576 linked against a cryptographic library should not be
577 distributed via the <em>non-US</em> server if it is
578 capable of running without the cryptographic library or
583 <heading>Further copyright considerations</heading>
585 Every package must be accompanied by a verbatim copy of
586 its copyright and distribution license in the file
587 <tt>/usr/share/doc/<ital><package-name></ital>/copyright</tt>
588 (see <ref id="copyrightfile"> for further details).
591 We reserve the right to restrict files from being included
592 anywhere in our archives if
593 <list compact="compact">
596 their use or distribution would break a law,
601 there is an ethical conflict in their distribution or
607 we would have to sign a license for them, or
612 their distribution would conflict with other project
620 Programs whose authors encourage the user to make
621 donations are fine for the main distribution, provided
622 that the authors do not claim that not donating is
623 immoral, unethical, illegal or something similar; in such
624 a case they must go in <em>non-free</em>.</p>
627 Packages whose copyright permission notices (or patent
628 problems) do not even allow redistribution of binaries
629 only, and where no special permission has been obtained,
630 must not be placed on the Debian FTP site and its mirrors
634 Note that under international copyright law (this applies
635 in the United States, too), <em>no</em> distribution or
636 modification of a work is allowed without an explicit
637 notice saying so. Therefore a program without a copyright
638 notice <em>is</em> copyrighted and you may not do anything
639 to it without risking being sued! Likewise if a program
640 has a copyright notice but no statement saying what is
641 permitted then nothing is permitted.</p>
644 Many authors are unaware of the problems that restrictive
645 copyrights (or lack of copyright notices) can cause for
646 the users of their supposedly-free software. It is often
647 worthwhile contacting such authors diplomatically to ask
648 them to modify their license terms. However, this can be a
649 politically difficult thing to do and you should ask for
650 advice on the <tt>debian-legal</tt> mailing list first, as
655 When in doubt about a copyright, send mail to
656 <email>debian-legal@lists.debian.org</email>. Be prepared
657 to provide us with the copyright statement. Software
658 covered by the GPL, public domain software and BSD-like
659 copyrights are safe; be wary of the phrases `commercial
660 use prohibited' and `distribution restricted'.
664 <heading>Subsections</heading>
667 The packages in the sections <em>main</em>,
668 <em>contrib</em> and <em>non-free</em> are grouped further
669 into <em>subsections</em> to simplify handling.
673 The section and subsection for each package should be
674 specified in the package's <tt>Section</tt> control
675 record. However, the maintainer of the Debian archive
676 may override this selection to ensure the consistency of
677 the Debian distribution. The <tt>Section</tt> field
678 should be of the form:
679 <list compact="compact">
682 <ital>subsection</ital> if the package is in the
683 <em>main</em> section,
688 <ital>section/subsection</ital> if the package is in
689 the <em>contrib</em> or <em>non-free</em> section,
695 <tt>non-US</tt>, <tt>non-US/contrib</tt> or
696 <tt>non-US/non-free</tt> if the package is in
697 <em>non-US/main</em>, <em>non-US/contrib</em> or
698 <em>non-US/non-free</em> respectively.
705 The Debian archive maintainers provide the authoritative
706 list of subsections. At present, they are:
707 <em>admin</em>, <em>base</em>, <em>comm</em>,
708 <em>contrib</em>, <em>devel</em>, <em>doc</em>,
709 <em>editors</em>, <em>electronics</em>, <em>games</em>,
710 <em>graphics</em>, <em>hamradio</em>,
711 <em>interpreters</em>, <em>libs</em>, <em>mail</em>,
712 <em>math</em>, <em>misc</em>, <em>net</em>, <em>news</em>,
713 <em>non-US</em>, <em>non-free</em>, <em>oldlibs</em>,
714 <em>otherosfs</em>, <em>science</em>, <em>shells</em>,
715 <em>sound</em>, <em>tex</em>, <em>text</em>,
716 <em>utils</em>, <em>web</em>, <em>x11</em>.
720 <heading>Priorities</heading>
723 Each package should have a <em>priority</em> value, which is
724 included in the package's <em>control record</em>. This
725 information is used by the Debian package management tools
726 to separate high-priority packages from less-important
730 The following <em>priority levels</em> are recognised by the
731 Debian package management tools.
733 <tag><tt>required</tt></tag>
736 Packages which are necessary for the proper
737 functioning of the system. You must not remove these
738 packages or your system may become totally broken and
739 you may not even be able to use <prgn>dpkg</prgn> to
740 put things back. Systems with only the
741 <tt>required</tt> packages are probably unusable, but
742 they do have enough functionality to allow the
743 sysadmin to boot and install more software.</p>
745 <tag><tt>important</tt></tag>
748 Important programs, including those which one would
749 expect to find on any Unix-like system. If the
750 expectation is that an experienced Unix person who
751 found it missing would say `What on earth is going on,
752 where is <prgn>foo</prgn>?', it must be an
753 <tt>important</tt> package.
756 This is an important criterion because we are
757 trying to produce, amongst other things, a free
761 Other packages without which the system will not run
762 well or be usable must also have priority
763 <tt>important</tt>. This does
764 <em>not</em> include Emacs, the X Window System, TeX
765 or any other large applications. The
766 <tt>important</tt> packages are just a bare minimum of
767 commonly-expected and necessary tools.</p>
769 <tag><tt>standard</tt></tag>
772 These packages provide a reasonably small but not too
773 limited character-mode system. This is what will
774 install by default if the user doesn't select anything
775 else. It doesn't include many large applications, but
776 it does include Emacs (this is more of a piece of
777 infrastructure than an application) and a reasonable
778 subset of TeX and LaTeX.</p>
780 <tag><tt>optional</tt></tag>
783 (In a sense everything that isn't required is
784 optional, but that's not what is meant here.) This is
785 all the software that you might reasonably want to
786 install if you didn't know what it was and don't have
787 specialized requirements. This is a much larger system
788 and includes the X Window System, a full TeX
789 distribution, and many applications. Note that
790 optional packages should not conflict with each other.
793 <tag><tt>extra</tt></tag>
796 This contains all packages that conflict with others
797 with required, important, standard or optional
798 priorities, or are only likely to be useful if you
799 already know what they are or have specialised
806 Packages must not depend on packages with lower priority
807 values (excluding build-time dependencies). In order to
808 ensure this, the priorities of one or more packages may need
814 <heading>Binary packages</heading>
817 The Debian GNU/Linux distribution is based on the Debian
818 package management system, called <prgn>dpkg</prgn>. Thus,
819 all packages in the Debian distribution must be provided
820 in the <tt>.deb</tt> file format.</p>
824 <heading>The package name</heading>
827 Every package must have a name that's unique within the Debian
831 Package names must consist of lower case letters (a-z),
832 digits (0-9), plus (+) and minus (-) signs, and periods
833 (.). They must be at least two characters long and must
834 contain at least one letter.
838 The package name is part of the file name of the
839 <tt>.deb</tt> file and is included in the control field
845 <heading>The maintainer of a package</heading>
847 Every package must have a Debian maintainer (the
848 maintainer may be one person or a group of people
849 reachable from a common email address, such as a mailing
850 list). The maintainer is responsible for ensuring that
851 the package is placed in the appropriate distributions.
855 The maintainer must be specified in the
856 <tt>Maintainer</tt> control field with their correct name
857 and a working email address. If one person maintains
858 several packages, he/she should try to avoid having
859 different forms of their name and email address in
860 the <tt>Maintainer</tt> fields of those packages.
864 If the maintainer of a package quits from the Debian
865 project, "Debian QA Group"
866 <email>packages@qa.debian.org</email> takes over the
867 maintainership of the package until someone else
868 volunteers for that task. These packages are called
869 <em>orphaned packages</em>.
872 The detailed procedure for doing this gracefully can
873 be found in the Debian Developer's Reference, either
874 in the <tt>developers-reference</tt> package, or on
875 the Debian FTP server
876 <ftpsite>ftp.debian.org</ftpsite> as
877 <ftppath>/debian/doc/package-developer/developers-reference.txt.gz</ftppath>
879 id="http://www.debian.org/doc/packaging-manuals/developers-reference/"
880 name="Debian Developer's Reference"> webpage.
888 <heading>The description of a package</heading>
891 Every Debian package must have an extended description
892 stored in the appropriate field of the control record.</p>
895 The description should be written so that it gives the
896 system administrator enough information to decide whether
897 to install the package. This description should not just
898 be copied verbatim from the program's documentation.
899 Instructions for configuring or using the package should
900 not be included -- that is what installation scripts,
901 manual pages, info files, etc., are for. Copyright
902 statements and other administrivia should not be included
903 either -- that is what the copyright file is for.</p>
908 <heading>Dependencies</heading>
911 Every package must specify the dependency information
912 about other packages that are required for the first to
916 For example, a dependency entry must be provided for any
917 shared libraries required by a dynamically-linked executable
918 binary in a package.</p>
921 Packages are not required to declare any dependencies they
922 have on other packages which are marked <tt>Essential</tt>
923 (see below), and should not do so unless they depend on a
924 particular version of that package.</p>
927 Sometimes, a package requires another package to be installed
928 <em>and</em> configured before it can be installed. In this
929 case, you must specify a <tt>Pre-Depends</tt> entry for
933 You should not specify a <tt>Pre-Depends</tt> entry for a
934 package before this has been discussed on the
935 <tt>debian-devel</tt> mailing list and a consensus about
936 doing that has been reached.</p></sect1>
940 <heading>Virtual packages</heading>
943 Sometimes, there are several packages which offer
944 more-or-less the same functionality. In this case, it's
945 useful to define a <em>virtual package</em> whose name
946 describes that common functionality. (The virtual
947 packages only exist logically, not physically--that's why
948 they are called <em>virtual</em>.) The packages with this
949 particular function will then <em>provide</em> the virtual
950 package. Thus, any other package requiring that function
951 can simply depend on the virtual package without having to
952 specify all possible packages individually.</p>
955 All packages should use virtual package names where
956 appropriate, and arrange to create new ones if necessary.
957 They should not use virtual package names (except privately,
958 amongst a cooperating group of packages) unless they have
959 been agreed upon and appear in the list of virtual package
963 The latest version of the authoritative list of virtual
964 package names can be found on
965 <ftpsite>ftp.debian.org</ftpsite> in
966 <ftppath>/debian/doc/package-developer/virtual-package-names-list.txt</ftppath>
967 or your local mirror. In addition, it is included in the
968 <tt>debian-policy</tt> package. The procedure for updating
969 the list is described at the top of the file.</p></sect1>
973 <heading>Base packages</heading>
976 The packages included in the <tt>base</tt> section have a
977 special function. They form a minimum subset of the Debian
978 GNU/Linux system that is installed before everything else
979 on a new system. Thus, only very few packages are allowed
980 to go into the <tt>base</tt> section to keep the required
981 disk usage very small.</p>
984 Most of these packages will have the priority value
985 <tt>required</tt> or at least <tt>important</tt>, and many
986 of them will be tagged <tt>essential</tt> (see below).</p>
989 You must not place any packages into the <tt>base</tt>
990 section before this has been discussed on the
991 <tt>debian-devel</tt> mailing list and a consensus about
992 doing that has been reached.</p></sect1>
996 <heading>Essential packages</heading>
999 Some packages are tagged <tt>essential</tt>. (They have
1000 <tt>Essential: yes</tt> in their package control record.)
1001 This flag is used for packages that are <em>essential</em>
1005 Since these packages cannot be easily removed (one has to
1006 specify an extra <em>force option</em> to
1007 <prgn>dpkg</prgn> to do so), this flag must not be used
1008 unless absolutely necessary. A shared library package
1009 must not be tagged <tt>essential</tt>--dependencies will
1010 prevent its premature removal, and we need to be able to
1011 remove it when it has been superseded.
1015 Since dpkg will not prevent upgrading of other packages
1016 while an <tt>essential</tt> package is in an unconfigured
1017 state, all <tt>essential</tt> packages must supply all of
1018 their core functionality even when unconfigured. If the
1019 package cannot satisfy this requirement it must not be
1020 tagged as essential, and any packages depending on this
1021 package must instead have explicit dependency fields as
1026 You must not tag any packages <tt>essential</tt> before
1027 this has been discussed on the <tt>debian-devel</tt>
1028 mailing list and a consensus about doing that has been
1034 <heading>Maintainer scripts</heading>
1037 The package installation scripts should avoid producing
1038 output which it is unnecessary for the user to see and
1039 should rely on <prgn>dpkg</prgn> to stave off boredom on
1040 the part of a user installing many packages. This means,
1041 amongst other things, using the <tt>--quiet</tt> option on
1042 <prgn>install-info</prgn>.</p>
1045 Errors which occur during the execution of an installation
1046 script must be checked and the installation must not
1047 continue after an error.
1051 Note that in general <ref id="scripts"> applies to package
1052 maintainer scripts, too.
1056 You should not use <tt>dpkg-divert</tt> on a file
1057 belonging to another package without consulting the
1058 maintainer of that package first.
1061 All packages which supply an instance of a common command
1062 name (or, in general, filename) should generally use
1063 <prgn>update-alternatives</prgn>, so that they may be
1064 installed together. If <prgn>update-alternatives</prgn>
1065 is not used, then each package must use
1066 <var>Conflicts</var> to ensure that other packages are
1067 de-installed. (In this case, it may be appropriate to
1068 specify a conflict against earlier versions of something
1069 that previously did not use
1070 <prgn>update-alternatives</prgn> - this is an exception to
1071 the usual rule that versioned conflicts should be
1077 <heading>Prompting in maintainer scripts</heading>
1079 Package maintainer scripts may prompt the user if
1080 necessary. Prompting may be accomplished by hand, or by
1081 communicating with a program, such as
1082 <prgn>debconf</prgn>, which conforms to the Debian
1083 Configuration management specification, version 2 or
1084 higher. These are included in the
1085 <file>debconf_specification</file> files in the
1086 <package>debian-policy</package> package.
1087 You may also find this file on the FTP site
1088 <ftpsite>ftp.debian.org</ftpsite> in
1089 <ftppath>/debian/doc/package-developer/debconf_specification.txt.gz</ftppath>
1090 or on your local mirror.
1093 2.5% of Debian packages [see <url
1094 id="http://kitenet.net/programs/debconf/stats/">]
1095 currently use <package>debconf</package> to prompt
1096 the user at install time, and this number is growing
1097 daily. The benefits of using debconf are briefly
1099 id="http://kitenet.net/doc/debconf-doc/introduction.html">;
1100 they include preconfiguration, (mostly)
1101 noninteractive installation, elimination of
1102 redundant prompting, consistency of user interface,
1106 With this increasing number of packages using
1107 <package>debconf</package>, plus the existance of a
1108 nascent second implementation of the Debian
1109 configuration management system
1110 (<package>cdebconf</package>), and the stabalization
1111 of the protocol these things use, the time has
1112 finally come to reflect the use of these things in
1119 Packages which use the Debian Configuration management
1120 specification may contain an additional
1121 <file>config</file> script and a <file>templates</file>
1122 file in their control archive. The <prgn>config</prgn>
1123 script might be run before the <prgn>preinst</prgn>
1124 script, and before the package is unpacked or any of its
1125 dependancies or pre-dependancies are satisfied.
1126 Therefore it must work using only the tools present in
1127 <em>essential</em> packages.
1130 <package>Debconf</package> or another tool that
1131 implements the Debian Configuration management
1132 specification will also be installed, and any
1133 versioned dependencies on it will be satisfied
1134 before preconfiguration begins.
1140 Packages should try to minimize the amount of prompting
1141 they need to do, and they should ensure that the user
1142 will only ever be asked each question once. This means
1143 that packages should try to use appropriate shared
1144 configuration files (such as <tt>/etc/papersize</tt> and
1145 <tt>/etc/news/server</tt>), and shared
1146 <package>debconf</package> variables rather than each
1147 prompting for their own list of required pieces of
1152 It also means that an upgrade should not ask the same
1153 questions again, unless the user has used <tt>dpkg
1154 --purge</tt> to remove the package's configuration. The
1155 answers to configuration questions should be stored in an
1156 appropriate place in <tt>/etc</tt> so that the user can
1157 modify them, and how this has been done should be
1161 If a package has a vitally important piece of
1162 information to pass to the user (such as "don't run me
1163 as I am, you must edit the following configuration files
1164 first or you risk your system emitting badly-formatted
1165 messages"), it should display this in the
1166 <prgn>config</prgn> or <prgn>postinst</prgn> script and
1167 prompt the user to hit return to acknowledge the
1168 message. Copyright messages do not count as vitally
1169 important (they belong in
1170 <tt>/usr/share/doc/<var>package</var>/copyright</tt>);
1171 neither do instructions on how to use a program (these
1172 should be in on-line documentation, where all the users
1176 Any necessary prompting should almost always be confined
1177 to the <prgn>config</prgn> or <prgn>postinst</prgn>
1178 script. If it is done in the <prgn>postinst</prgn>, it
1179 should be protected with a conditional so that unnecessary
1180 prompting doesn't happen if a package's installation fails
1181 and the <prgn>postinst</prgn> is called with
1182 <tt>abort-upgrade</tt>, <tt>abort-remove</tt> or
1183 <tt>abort-deconfigure</tt>.</p>
1188 <heading>Source packages</heading>
1191 <heading>Standards conformance</heading>
1194 In the source package's <tt>Standards-Version</tt> control
1195 field, you must specify the most recent version number of
1196 this policy document with which your package complies.
1197 The current version number is &version;.
1201 This information may be used to file bug reports
1202 automatically if your package becomes too much out of
1207 The version number has four components--major and minor
1208 version number and major and minor patch level. When the
1209 standards change in a way that requires every package to
1210 change the major number will be changed. Significant
1211 changes that will require work in many packages will be
1212 signaled by a change to the minor number. The major patch
1213 level will be changed for any change to the meaning of the
1214 standards, however small; the minor patch level will be
1215 changed when only cosmetic, typographical or other edits
1216 are made which neither change the meaning of the document
1217 nor affect the contents of packages.</p>
1220 Thus only the first three components of the policy version
1221 are significant in the <em>Standards-Version</em> control
1222 field, and so either these three components or the all
1223 four components may be specified.
1226 In the past, people specified the full version number
1227 in the Standards-Version field, for example `2.3.0.0'.
1228 Since minor patch-level changes don't introduce new
1229 policy, it was thought it would be better to relax
1230 policy and only require the first 3 components to be
1231 specified, in this example `2.3.0'. All four
1232 components may still be used if someone wishes to do
1239 You should regularly, and especially if your package has
1240 become out of date, check for the newest Policy Manual
1241 available and update your package, if necessary. When your
1242 package complies with the new standards you should update the
1243 <tt>Standards-Version</tt> source package field and
1247 See the file <tt>upgrading-checklist</tt> for
1248 information about policy which has changed between
1249 different versions of this document.
1257 <heading>Package relationships</heading>
1260 Source packages should specify which binary packages they
1261 require to be installed or not to be installed in order to
1262 build correctly. For example, if building a package
1263 requires a certain compiler, then the compiler should be
1264 specified as a build-time dependency.
1268 It is not necessary to explicitly specify build-time
1269 relationships on a minimal set of packages that are always
1270 needed to compile, link and put in a Debian package a
1271 standard "Hello World!" program written in C or C++. The
1272 required packages are called <em>build-essential</em>, and
1273 an informational list can be found in
1274 <tt>/usr/share/doc/build-essential/list</tt> (which is
1275 contained in the <tt>build-essential</tt>
1281 <p>This allows maintaining the list separately
1282 from the policy documents (the list does not
1283 need the kind of control that the policy
1289 Having a separate package allows one to install
1290 the build-essential packages on a machine, as
1291 well as allowing other packages such as task
1292 packages to require installation of the
1293 build-essential packages using the depends
1299 The separate package allows bug reports against
1300 the list to be categorized separately from
1301 the policy management process in the BTS.
1311 When specifying the set of build-time dependencies, one
1312 should list only those packages explicitly required by the
1313 build. It is not necessary to list packages which are
1314 required merely because some other package in the list of
1315 build-time dependencies depends on them.
1318 The reason for this is that dependencies change, and
1319 you should list all those packages, and <em>only</em>
1320 those packages that <em>you</em> need directly. What
1321 others need is their business. For example, if you
1322 only link against <tt>libimlib</tt>, you will need to
1323 build-depend on <package>libimlib2-dev</package> but
1324 not against any <tt>libjpeg*</tt> packages, even
1325 though <tt>libimlib2-dev</tt> currently depends on
1326 them: installation of <package>libimlib2-dev</package>
1327 will automatically ensure that all of its run-time
1328 dependencies are satisfied.
1334 If build-time dependencies are specified, it must be
1335 possible to build the package and produce working binaries
1336 on a system with only essential and build-essential
1337 packages installed and also those required to satisfy the
1338 build-time relationships (including any implied
1339 relationships). In particular, this means that version
1340 clauses should be used rigorously in build-time
1341 relationships so that one cannot produce bad or
1342 inconsistently configured packages when the relationships
1343 are properly satisfied.
1347 <heading>Changes to the upstream sources</heading>
1350 If changes to the source code are made that are not
1351 specific to the needs of the Debian system, they should be
1352 sent to the upstream authors in whatever form they prefer
1353 so as to be included in the upstream version of the
1357 If you need to configure the package differently for
1358 Debian or for Linux, and the upstream source doesn't
1359 provide a way to do so, you should add such configuration
1360 facilities (for example, a new <prgn>autoconf</prgn> test
1361 or <tt>#define</tt>) and send the patch to the upstream
1362 authors, with the default set to the way they originally
1363 had it. You can then easily override the default in your
1364 <tt>debian/rules</tt> or wherever is appropriate.</p>
1367 You should make sure that the <prgn>configure</prgn> utility
1368 detects the correct architecture specification string
1369 (refer to <ref id="arch-spec"> for details).</p>
1372 If you need to edit a <prgn>Makefile</prgn> where
1373 GNU-style <prgn>configure</prgn> scripts are used, you
1374 should edit the <tt>.in</tt> files rather than editing the
1375 <prgn>Makefile</prgn> directly. This allows the user to
1376 reconfigure the package if necessary. You should
1377 <em>not</em> configure the package and edit the generated
1378 <prgn>Makefile</prgn>! This makes it impossible for
1379 someone else to later reconfigure the package.</p></sect1>
1383 <heading>Documenting your changes</heading>
1386 You should document your changes and updates to the source
1387 package properly in the <tt>debian/changelog</tt> file. (Note
1388 that mistakes in changelogs are usually best rectified by
1389 making a new changelog entry rather than "rewriting history"
1390 by editing old changelog entries.)</p>
1393 In non-experimental packages you must use a format for
1394 <tt>debian/changelog</tt> which is supported by the most
1395 recent released version of <prgn>dpkg</prgn>.
1398 If you wish to use an alternative format, you may do
1399 so as long as you include a parser for it in your
1400 source package. The parser must have an API
1401 compatible with that expected by
1402 <prgn>dpkg-genchanges</prgn> and
1403 <prgn>dpkg-gencontrol</prgn>. If there is general
1404 interest in the new format, you should contact the
1405 <package>dpkg</package> maintainer to have the parser
1406 script for it included in the <prgn>dpkg</prgn>
1407 package. (You will need to agree that the parser and
1408 its manpage may be distributed under the GNU GPL, just
1409 as the rest of `dpkg' is.)
1417 <heading>Error trapping in makefiles</heading>
1420 When <prgn>make</prgn> invokes a command in a makefile
1421 (including your package's upstream makefiles and
1422 <tt>debian/rules</tt>), it does so using <tt>sh</tt>. This
1423 means that <tt>sh</tt>'s usual bad error handling
1424 properties apply: if you include a miniature script as one
1425 of the commands in your makefile you'll find that if you
1426 don't do anything about it then errors are not detected
1427 and <prgn>make</prgn> will blithely continue after
1431 Every time you put more than one shell command (this
1432 includes using a loop) in a makefile command you
1433 must make sure that errors are trapped. For
1434 simple compound commands, such as changing directory and
1435 then running a program, using <tt>&&</tt> rather
1436 than semicolon as a command separator is sufficient. For
1437 more complex commands including most loops and
1438 conditionals you should include a separate <tt>set -e</tt>
1439 command at the start of every makefile command that's
1440 actually one of these miniature shell scripts.</p></sect1>
1444 <heading>Obsolete constructs and libraries</heading>
1447 The include file <prgn><varargs.h></prgn> is
1448 provided to support end-users compiling very old software;
1449 the library <tt>libtermcap</tt> is provided to support the
1450 execution of software which has been linked against it
1451 (either old programs or those such as Netscape which are
1452 only available in binary form).</p>
1455 Debian packages should be patched to use
1456 <prgn><stdarg.h></prgn> and <tt>ncurses</tt>
1463 <chapt id="controlfields"><heading>Control files and their fields</heading>
1466 Many of the tools in the package management suite manipulate
1467 data in a common format, known as control files. Binary and
1468 source packages have control data as do the <tt>.changes</tt>
1469 files which control the installation of uploaded files, and
1470 <prgn>dpkg</prgn>'s internal databases are in a similar
1474 <sect><heading>Syntax of control files</heading>
1477 A file consists of one or more paragraphs of fields. The
1478 paragraphs are separated by blank lines. Some control files
1479 only allow one paragraph; others allow several, in which
1480 case each paragraph often refers to a different package.
1484 Each paragraph is a series of fields and values; each field
1485 consists of a name, followed by a colon and the value. It
1486 ends at the end of the line. Horizontal whitespace (spaces
1487 and tabs) may occur immediately before or after the value
1488 and is ignored there; it is conventional to put a single
1489 space after the colon.
1493 Some fields' values may span several lines; in this case
1494 each continuation line <em>must</em> start with a space or
1495 tab. Any trailing spaces or tabs at the end of individual
1496 lines of a field value are ignored.
1500 Except where otherwise stated only a single line of data is
1501 allowed and whitespace is not significant in a field body.
1502 Whitespace may never appear inside names (of packages,
1503 architectures, files or anything else), version numbers or
1504 in between the characters of multi-character version
1509 Field names are not case-sensitive, but it is usual to
1510 capitalize the field names using mixed case as shown below.
1514 Blank lines, or lines consisting only of spaces and tabs,
1515 are not allowed within field values or between fields - that
1516 would mean a new paragraph.
1520 It is important to note that there are several fields which
1521 are optional as far as <prgn>dpkg</prgn> and the related
1522 tools are concerned, but which must appear in every Debian
1523 package, or whose omission may cause problems. When writing
1524 the control files for Debian packages you <em>must</em> read
1525 the Debian policy manual in conjunction with the details
1526 below and the list of fields for the particular file.</p>
1529 <sect><heading>List of fields</heading>
1531 This list here is not supposed to be exhaustive. Most fields
1532 are dealt with elsewhere in this document and in the
1535 <sect1 id="f-Package"><heading><tt>Package</tt>
1539 The name of the binary package. Package names consist of
1540 the alphanumerics and <tt>+</tt> <tt>-</tt> <tt>.</tt>
1541 (plus, minus and full stop).
1545 They must be at least two characters long and must start
1546 with an alphanumeric character. The use of lowercase
1547 package names is strongly recommended unless the package
1548 you're building (or referring to, in other fields) is
1549 already using uppercase.</p>
1552 <sect1 id="f-Version"><heading><tt>Version</tt>
1556 This lists the source or binary package's version number -
1557 see <ref id="versions">.
1563 id="f-Standards-Version"><heading><tt>Standards-Version</tt>
1567 The most recent version of the standards (the policy
1568 manual and associated texts) with which the package
1569 complies. This is updated manually when editing the
1570 source package to conform to newer standards; it can
1571 sometimes be used to tell when a package needs attention.
1575 Its format is the same as that of a version number except
1576 that no epoch or Debian revision is allowed - see <ref
1581 <sect1 id="f-Distribution"><heading><tt>Distribution</tt>
1585 In a <tt>.changes</tt> file or parsed changelog output
1586 this contains the (space-separated) name(s) of the
1587 distribution(s) where this version of the package should
1588 be or was installed. Distribution names follow the rules
1589 for package names. (See <ref id="f-Package">).
1594 Current distribution values are:
1596 <tag><em>stable</em></tag>
1599 This is the current `released' version of Debian
1601 distribution is <em>stable</em> only major bug fixes
1602 are allowed. When changes are made to this
1603 distribution, the release number is increased
1604 (for example: 1.2r1 becomes 1.2r2 then 1.2r3, etc).
1608 <tag><em>unstable</em></tag>
1611 This distribution value refers to the
1612 <em>developmental</em> part of the Debian
1613 distribution tree. New packages, new upstream
1614 versions of packages and bug fixes go into the
1615 <em>unstable</em> directory tree. Download from
1616 this distribution at your own risk.
1620 <tag><em>frozen</em></tag>
1623 From time to time, the <em>unstable</em>
1624 distribution enters a state of `code-freeze' in
1625 anticipation of release as a <em>stable</em>
1626 version. During this period of testing only
1627 fixes for existing or newly-discovered bugs will
1632 <tag><em>experimental</em></tag>
1635 The packages with this distribution value are deemed
1636 by their maintainers to be high risk. Oftentimes they
1637 represent early beta or developmental packages from
1638 various sources that the maintainers want people to
1639 try, but are not ready to be a part of the other parts
1640 of the Debian distribution tree. Download at your own
1645 There are several sections in each
1646 distribution. Currently, these sections are:
1649 <tag><em>main</em></tag>
1652 The packages in this section are those in the
1653 main Debian distribution. They are all free
1654 (according to the Debian free software
1655 guidelines) and meet any other criteria for
1656 inclusion described in this manual.</p>
1659 <tag><em>contrib</em></tag>
1662 The packages in this section do not meet the
1663 criteria for inclusion in the main Debian
1664 distribution as defined by this manual, but are
1665 otherwise free, as defined by the Debian free
1666 software guidelines.</p>
1669 <tag><em>non-free</em></tag>
1672 Packages in <em>non-free</em> do not meet the
1673 criteria of free software, as defined by the
1674 Debian free software guidelines. Again, use your
1675 best judgment in downloading from this
1679 </taglist> You should list <em>all</em> distributions that
1680 the package should be installed into. Except in unusual
1681 circumstances, installations to <em>stable</em> should also
1682 go into <em>frozen</em> (if it exists) and
1683 <em>unstable</em>. Likewise, installations into
1684 <em>frozen</em> should also go into <em>unstable</em>.
1693 <chapt id="versions"><heading>Version numbering </heading>
1696 Every package has a version number, in its <tt>Version</tt>
1701 The package management system imposes an ordering on version
1702 numbers, so that it can tell whether packages are being up- or
1703 downgraded and so that package system front end applications
1704 can tell whether a package it finds available is newer than
1705 the one installed on the system. The version number format
1706 has the most significant parts (as far as comparison is
1707 concerned) at the beginning.
1711 The version number format is:
1712 &lsqb<var>epoch</var><tt>:</tt>]<var>upstream-version</var>[<tt>-</tt><var>debian-revision</var>]
1716 The three components here are:
1718 <tag><var>epoch</var></tag>
1722 This is a single (generally small) unsigned integer. It
1723 may be omitted, in which case zero is assumed. If it is
1724 omitted then the <var>upstream-version</var> may not
1729 It is provided to allow mistakes in the version numbers
1730 of older versions of a package, and also a package's
1731 previous version numbering schemes, to be left behind.
1736 <tag><var>upstream-version</var></tag>
1740 This is the main part of the version. It is usually the
1741 version number of the original (`upstream') package from
1742 which the <tt>.deb</tt> file has been made, if this is
1743 applicable. Usually this will be in the same format as
1744 that specified by the upstream author(s); however, it
1745 may need to be reformatted to fit into the package
1746 management system's format and comparison scheme.
1750 The comparison behavior of the package management system
1751 with respect to the <var>upstream-version</var> is
1752 described below. The <var>upstream-version</var>
1753 portion of the version number is mandatory.
1757 The <var>upstream-version</var> may contain only
1758 alphanumerics and the characters <tt>.</tt> <tt>+</tt>
1759 <tt>-</tt> <tt>:</tt> (full stop, plus, hyphen, colon)
1760 and should start with a digit. If there is no
1761 <var>debian-revision</var> then hyphens are not allowed;
1762 if there is no <var>epoch</var> then colons are not
1766 <tag><var>debian-revision</var></tag>
1770 This part of the version represents the version of the
1771 modifications that were made to the package to make it a
1772 Debian binary package. It is in the same format as the
1773 <var>upstream-version</var> and is compared in the same
1778 It is optional; if it isn't present then the
1779 <var>upstream-version</var> may not contain a hyphen.
1780 This format represents the case where a piece of
1781 software was written specifically to be turned into a
1782 Debian binary package, and so there is only one
1783 `debianization' of it and therefore no revision
1784 indication is required.
1788 It is conventional to restart the
1789 <var>debian-revision</var> at <tt>1</tt> each time the
1790 <var>upstream-version</var> is increased.
1794 The package management system will break the
1795 <var>upstream-version</var> and
1796 <var>debian-revision</var> apart at the last hyphen in
1797 the string. The absence of a <var>debian-revision</var>
1798 compares earlier than the presence of one (but note that
1799 the <var>debian-revision</var> is the least significant
1800 part of the version number).
1804 The <var>debian-revision</var> may contain only
1805 alphanumerics and the characters <tt>+</tt> and
1806 <tt>.</tt> (plus and full stop).
1810 The <var>upstream-version</var> and <var>debian-revision</var>
1811 parts are compared by the package management system using the
1816 The strings are compared from left to right.
1820 First the initial part of each string consisting entirely of
1821 non-digit characters is determined. These two parts (one of
1822 which may be empty) are compared lexically. If a difference
1823 is found it is returned. The lexical comparison is a
1824 comparison of ASCII values modified so that all the letters
1825 sort earlier than all the non-letters.
1829 Then the initial part of the remainder of each string which
1830 consists entirely of digit characters is determined. The
1831 numerical values of these two parts are compared, and any
1832 difference found is returned as the result of the comparison.
1833 For these purposes an empty string (which can only occur at
1834 the end of one or both version strings being compared) counts
1839 These two steps are repeated (chopping initial non-digit
1840 strings and initial digit strings off from the start) until a
1841 difference is found or both strings are exhausted.
1845 Note that the purpose of epochs is to allow us to leave behind
1846 mistakes in version numbering, and to cope with situations
1847 where the version numbering changes. It is <em>not</em> there
1848 to cope with version numbers containing strings of letters
1849 which the package management system cannot interpret (such as
1850 <tt>ALPHA</tt> or <tt>pre-</tt>), or with silly orderings (the
1851 author of this manual has heard of a package whose versions
1852 went <tt>1.1</tt>, <tt>1.2</tt>, <tt>1.3</tt>, <tt>1</tt>,
1853 <tt>2.1</tt>, <tt>2.2</tt>, <tt>2</tt> and so forth).
1857 If an upstream package has problematic version numbers they
1858 should be converted to a sane form for use in the
1859 <tt>Version</tt> field.
1863 <heading>Version numbers based on dates</heading>
1865 In general, Debian packages should use the same version
1866 numbers as the upstream sources.</p>
1869 However, in some cases where the upstream version number is
1870 based on a date (e.g., a development `snapshot' release) the
1871 package management system cannot handle these version
1872 numbers without epochs. For example, dpkg will consider
1873 `96May01' to be greater than `96Dec24'.</p>
1876 To prevent having to use epochs for every new upstream
1877 version, the version number should be changed to the
1878 following format in such cases: `19960501', `19961224'. It
1879 is up to the maintainer whether he/she wants to bother the
1880 upstream maintainer to change the version numbers upstream,
1884 Note, that other version formats based on dates which are
1885 parsed correctly by the package management system should
1886 <em>not</em> be changed.</p>
1889 Native Debian packages (i.e., packages which have been
1890 written especially for Debian) whose version numbers include
1891 dates should always use the `YYYYMMDD' format.</p>
1895 <chapt id="miscellaneous"><heading>Packaging Considerations</heading>
1897 <sect id="timestamps"><heading>Time Stamps</heading>
1899 Maintainers are encouraged to preserve the modification
1900 times of the upstream source files in a package, as far as
1901 is reasonably possible. Even though this is optional, this
1902 is still a good idea.
1905 The rationale is that there is some information conveyed
1906 by knowing the age of the file, for example, you could
1907 recognize that some documentation is very old by looking
1908 at the modification time, so it would be nice if the
1909 modification time of the upstream source would be
1916 <sect id="debianrules"><heading><tt>debian/rules</tt> - the
1917 main building script </heading>
1920 This file must be an executable makefile, and contains the
1921 package-specific recipes for compiling the package and
1922 building binary package(s) out of the source.
1926 It must start with the line <tt>#!/usr/bin/make -f</tt>,
1927 so that it can be invoked by saying its name rather than
1928 invoking <prgn>make</prgn> explicitly.
1932 Since an interactive <tt>debian/rules</tt> script makes it
1933 impossible to auto-compile that package and also makes it
1934 hard for other people to reproduce the same binary
1935 package, all <strong>required targets</strong> MUST be
1936 non-interactive. At a minimum, required targets are the
1937 ones called by <prgn>dpkg-buildpackage</prgn>, namely,
1938 <em>clean</em>, <em>binary</em>, <em>binary-arch</em>,
1939 <em>binary-indep</em>, and <em>build</em>. It also follows
1940 that any target that these targets depend on must also be
1945 The targets which must be present are:
1947 <tag><tt>build</tt></tag>
1950 This should perform all non-interactive
1951 configuration and compilation of the package. If a
1952 package has an interactive pre-build configuration
1953 routine, the Debianised source package should be
1954 built after this has taken place, so that it can be
1955 built without rerunning the configuration.
1959 For some packages, notably ones where the same
1960 source tree is compiled in different ways to produce
1961 two binary packages, the <prgn>build</prgn> target
1962 does not make much sense. For these packages it is
1963 good enough to provide two (or more) targets
1964 (<tt>build-a</tt> and <tt>build-b</tt> or whatever)
1965 for each of the ways of building the package, and a
1966 <prgn>build</prgn> target that does nothing. The
1967 <prgn>binary</prgn> target will have to build the
1968 package in each of the possible ways and make the
1969 binary package out of each.
1973 The <prgn>build</prgn> target must not do anything
1974 that might require root privilege.
1978 The <prgn>build</prgn> target may need to run
1979 <prgn>clean</prgn> first - see below.
1983 When a package has a configuration routine that
1984 takes a long time, or when the makefiles are poorly
1985 designed, or when <prgn>build</prgn> needs to run
1986 <prgn>clean</prgn> first, it is a good idea to
1987 <tt>touch build</tt> when the build process is
1988 complete. This will ensure that if <tt>debian/rules
1989 build</tt> is run again it will not rebuild the
1994 <tag><tt>binary</tt>, <tt>binary-arch</tt>,
1995 <tt>binary-indep</tt>
1999 The <prgn>binary</prgn> target must be all that is
2000 necessary for the user to build the binary
2001 package. All these targets are required to be
2002 non-interactive. It is split into two parts:
2003 <prgn>binary-arch</prgn> builds the packages' output
2004 files which are specific to a particular
2005 architecture, and <prgn>binary-indep</prgn> builds
2006 those which are not.
2010 <prgn>binary</prgn> may be (and commonly is) a target
2011 with no commands which simply depends on
2012 <prgn>binary-arch</prgn> and
2013 <prgn>binary-indep</prgn>.
2017 Both <prgn>binary-*</prgn> targets should depend on
2018 the <prgn>build</prgn> target, above, so that the
2019 package is built if it has not been already. It
2020 should then create the relevant binary package(s),
2021 using <prgn>dpkg-gencontrol</prgn> to make their
2022 control files and <prgn>dpkg-deb</prgn> to build
2023 them and place them in the parent of the top level
2028 If one of the <prgn>binary-*</prgn> targets has
2029 nothing to do (this will be always be the case if
2030 the source generates only a single binary package,
2031 whether architecture-dependent or not) it
2032 <em>must</em> still exist, and must always
2037 The <prgn>binary</prgn> targets must be invoked as
2042 <tag><tt>clean</tt></tag>
2046 This must undo any effects that the
2047 <prgn>build</prgn> and <prgn>binary</prgn> targets
2048 may have had, except that it should leave alone any
2049 output files created in the parent directory by a
2050 run of <prgn>binary</prgn>. This target must be
2055 If a <prgn>build</prgn> file is touched at the end
2056 of the <prgn>build</prgn> target, as suggested
2057 above, it should be removed as the first thing that
2058 <prgn>clean</prgn> does, so that running
2059 <prgn>build</prgn> again after an interrupted
2060 <prgn>clean</prgn> doesn't think that everything is
2065 The <prgn>clean</prgn> target may need to be
2066 invoked as root if <prgn>binary</prgn> has been
2067 invoked since the last <prgn>clean</prgn>, or if
2068 <prgn>build</prgn> has been invoked as root (since
2069 <prgn>build</prgn> may create directories, for
2074 <tag><tt>get-orig-source</tt> (optional)</tag>
2078 This target fetches the most recent version of the
2079 original source package from a canonical archive site
2080 (via FTP or WWW, for example), does any necessary
2081 rearrangement to turn it into the original source
2082 tar file format described below, and leaves it in the
2087 This target may be invoked in any directory, and
2088 should take care to clean up any temporary files it
2093 This target is optional, but providing it if
2094 possible is a good idea.
2100 The <prgn>build</prgn>, <prgn>binary</prgn> and
2101 <prgn>clean</prgn> targets must be invoked with a current
2102 directory of the package's top-level directory.
2107 Additional targets may exist in <tt>debian/rules</tt>,
2108 either as published or undocumented interfaces or for the
2109 package's internal use.
2113 The architecture we build on and build for is determined by
2114 make variables via dpkg-architecture. You can get the Debian
2115 architecture and the GNU style architecture specification
2116 string for the build machine as well as the host
2117 machine. Here is a list of supported make variables:
2118 <list compact="compact">
2120 <p><tt>DEB_*_ARCH</tt> (the Debian architecture)</p>
2123 <p><tt>DEB_*_GNU_TYPE</tt> (the GNU style architecture
2124 specification string)</p>
2127 <p><tt>DEB_*_GNU_CPU</tt> (the CPU part of DEB_*_GNU_TYPE)</p>
2130 <p><tt>DEB_*_GNU_SYSTEM</tt> (the System part of
2136 where <tt>*</tt> is either <tt>BUILD</tt> for specification of
2137 the build machine or <tt>HOST</tt> for specification of the machine
2142 Backward compatibility can be provided in the rules file
2143 by setting the needed variables to suitable default
2144 values, please refer to the documentation of
2145 dpkg-architecture for details.
2149 It is important to understand that the <tt>DEB_*_ARCH</tt>
2150 string only determines which Debian architecture we are
2151 building on or for. It should not be used to get the CPU
2152 or system information; the GNU style variables should be
2157 <sect id="dpkgchangelog"><heading><tt>debian/changelog</tt>
2161 This file records the changes to the Debian-specific parts of the
2165 Though there is nothing stopping an author who is also
2166 the Debian maintainer from using it for all their
2167 changes, it will have to be renamed if the Debian and
2168 upstream maintainers become different
2175 It has a special format which allows the package building
2176 tools to discover which version of the package is being
2177 built and find out other release-specific information.
2181 That format is a series of entries like this:
2183 <var>package</var> (<var>version</var>) <var>distribution(s)</var>; urgency=<var>urgency</var>
2185 * <var>change details</var>
2186 <var>more change details</var>
2187 * <var>even more change details</var>
2189 -- <var>maintainer name and email address</var> <var>date</var>
2194 <var>package</var> and <var>version</var> are the source
2195 package name and version number.
2199 <var>distribution(s)</var> lists the distributions where
2200 this version should be installed when it is uploaded - it
2201 is copied to the <tt>Distribution</tt> field in the
2202 <tt>.changes</tt> file. See <ref id="f-Distribution">.
2206 <var>urgency</var> is the value for the <tt>Urgency</tt>
2207 field in the <tt>.changes</tt> file for the upload. It is
2208 not possible to specify an urgency containing commas; commas
2209 are used to separate
2210 <tt><var>keyword</var>=<var>value</var></tt> settings in the
2211 <prgn>dpkg</prgn> changelog format (though there is
2212 currently only one useful <var>keyword</var>,
2217 The change details may in fact be any series of lines
2218 starting with at least two spaces, but conventionally each
2219 change starts with an asterisk and a separating space and
2220 continuation lines are indented so as to bring them in
2221 line with the start of the text above. Blank lines may be
2222 used here to separate groups of changes, if desired.
2226 The maintainer name and email address need <em>not</em>
2227 necessarily be those of the usual package maintainer.
2228 They should be the details of the person doing
2229 <em>this</em> version. The information here will be
2230 copied to the <tt>.changes</tt> file, and then later used
2231 to send an acknowledgement when the upload has been
2236 The <var>date</var> should be in RFC822 format
2239 This is generated by the <prgn>822-date</prgn>
2242 </footnote>; it should include the time zone specified
2243 numerically, with the time zone name or abbreviation
2244 optionally present as a comment.
2248 The first `title' line with the package name should start
2249 at the left hand margin; the `trailer' line with the
2250 maintainer and date details should be preceded by exactly
2251 one space. The maintainer details and the date must be
2252 separated by exactly two spaces.
2255 <sect1><heading>Defining alternative changelog formats</heading>
2258 It is possible to use a different format to the standard
2259 one, by providing a parser for the format you wish to
2263 A changelog parser must not interact with the user at
2269 <sect id="srcsubstvars"><heading><tt>debian/substvars</tt>
2270 and variable substitutions </heading>
2273 When <prgn>dpkg-gencontrol</prgn>,
2274 <prgn>dpkg-genchanges</prgn> and <prgn>dpkg-source</prgn>
2275 generate control files they do variable substitutions on
2276 their output just before writing it. Variable
2277 substitutions have the form
2278 <tt>${<var>variable-name</var>}</tt>. The optional file
2279 <tt>debian/substvars</tt> contains variable substitutions
2280 to be used; variables can also be set directly from
2281 <tt>debian/rules</tt> using the <tt>-V</tt> option to the
2282 source packaging commands, and certain predefined
2283 variables are available.
2287 The is usually generated and modified dynamically by
2288 <tt>debian/rules</tt> targets; in this case it must be
2289 removed by the <prgn>clean</prgn> target.
2293 See <manref name="dpkg-source" section="1"> for full
2294 details about source variable substitutions, including the
2295 format of <tt>debian/substvars</tt>.</p>
2298 <sect id="debianfiles"><heading><tt>debian/files</tt>
2302 This file is not a permanent part of the source tree; it
2303 is used while building packages to record which files are
2304 being generated. <prgn>dpkg-genchanges</prgn> uses it
2305 when it generates a <tt>.changes</tt> file.
2309 It should not exist in a shipped source package, and so it
2310 (and any backup files or temporary files such as
2314 <tt>files.new</tt> is used as a temporary file by
2315 <prgn>dpkg-gencontrol</prgn> and
2316 <prgn>dpkg-distaddfile</prgn> - they write a new
2317 version of <tt>files</tt> here before renaming it,
2318 to avoid leaving a corrupted copy if an error
2321 </footnote>) should be removed by the
2322 <prgn>clean</prgn> target. It may also be wise to
2323 ensure a fresh start by emptying or removing it at the
2324 start of the <prgn>binary</prgn> target.
2328 <prgn>dpkg-gencontrol</prgn> adds an entry to this file
2329 for the <tt>.deb</tt> file that will be created by
2330 <prgn>dpkg-deb</prgn> from the control file that it
2331 generates, so for most packages all that needs to be done
2332 with this file is to delete it in <prgn>clean</prgn>.
2336 If a package upload includes files besides the source
2337 package and any binary packages whose control files were
2338 made with <prgn>dpkg-gencontrol</prgn> then they should be
2339 placed in the parent of the package's top-level directory
2340 and <prgn>dpkg-distaddfile</prgn> should be called to add
2341 the file to the list in <tt>debian/files</tt>.</p>
2344 <sect id="restrictions"><heading>Restrictions on objects in source packages
2348 The source package may not contain any hard links
2351 This is not currently detected when building source
2352 packages, but only when extracting
2358 Hard links may be permitted at some point in the
2359 future, but would require a fair amount of
2362 </footnote>, device special files, sockets or setuid or
2366 Setgid directories are allowed.
2371 <sect id="descriptions"><heading>Descriptions of packages - the
2372 <tt>Description</tt> field </heading>
2375 The description is intended to describe the program to a user
2376 who has never met it before so that they know whether they
2377 want to install it. It should also give information about the
2378 significant dependencies and conflicts between this package
2379 and others, so that the user knows why these dependencies and
2380 conflicts have been declared.
2383 <sect1><heading>Notes about writing descriptions
2387 The single line synopsis should be kept brief - certainly
2388 under 80 characters.
2392 Do not include the package name in the synopsis line. The
2393 display software knows how to display this already, and you
2394 do not need to state it. Remember that in many situations
2395 the user may only see the synopsis line - make it as
2396 informative as you can.
2400 Do not try to continue the single line synopsis into the
2401 extended description. This will not work correctly when
2402 the full description is displayed, and makes no sense
2403 where only the summary (the single line synopsis) is
2408 The extended description should describe what the package
2409 does and how it relates to the rest of the system (in terms
2410 of, for example, which subsystem it is which part of).
2414 The description field needs to make sense to anyone, even
2415 people who have no idea about any of the things the
2419 The blurb that comes with a program in its
2420 announcements and/or <prgn>README</prgn> files is
2421 rarely suitable for use in a description. It is
2422 usually aimed at people who are already in the
2423 community where the package is used.
2429 Put important information first, both in the synopsis and
2430 extended description. Sometimes only the first part of the
2431 synopsis or of the description will be displayed. You can
2432 assume that there will usually be a way to see the whole
2433 extended description.
2437 You may include information about dependencies and so forth
2438 in the extended description, if you wish.
2442 Do not use tab characters. Their effect is not predictable.
2450 <chapt id="maintainerscripts"><heading>Package maintainer scripts
2451 and installation procedure
2454 <sect><heading>Introduction to package maintainer scripts
2458 It is possible to supply scripts as part of a package which
2459 the package management system will run for you when your
2460 package is installed, upgraded or removed.
2464 These scripts should be the files <tt>preinst</tt>,
2465 <tt>postinst</tt>, <tt>prerm</tt> and <tt>postrm</tt> in the
2466 control area of the package. They must be proper executable
2467 files; if they are scripts (which is recommended) they must
2468 start with the usual <tt>#!</tt> convention. They should be
2469 readable and executable by anyone, and not world-writable.
2473 The package management system looks at the exit status from
2474 these scripts. It is important that they exit with a
2475 non-zero status if there is an error, so that the package
2476 management system can stop its processing. For shell
2477 scripts this means that you <em>almost always</em> need to
2478 use <tt>set -e</tt> (this is usually true when writing shell
2479 scripts, in fact). It is also important, of course, that
2480 they don't exit with a non-zero status if everything went
2485 It is necessary for the error recovery procedures that the
2486 scripts be idempotent: i.e., invoking the same script several
2487 times in the same situation should do no harm. If the first
2488 call failed, or aborted half way through for some reason,
2489 the second call should merely do the things that were left
2490 undone the first time, if any, and exit with a success
2495 When a package is upgraded a combination of the scripts from
2496 the old and new packages is called in amongst the other
2497 steps of the upgrade procedure. If your scripts are going
2498 to be at all complicated you need to be aware of this, and
2499 may need to check the arguments to your scripts.
2503 Broadly speaking the <prgn>preinst</prgn> is called before
2504 (a particular version of) a package is installed, and the
2505 <prgn>postinst</prgn> afterwards; the <prgn>prerm</prgn>
2506 before (a version of) a package is removed and the
2507 <prgn>postrm</prgn> afterwards.
2510 <p> Programs called from maintainer scripts should not
2511 normally have a path prepended to them. Before installation
2512 is started the package management system checks to see if
2513 the programs <prgn>ldconfig</prgn>,
2514 <prgn>start-stop-daemon</prgn>, <prgn>install-info</prgn>,
2515 and <prgn>update-rc.d</prgn> can be found via the
2516 <tt>PATH</tt> environment variable. Those programs, and any
2517 other program that one would expect to on the <tt>PATH</tt>,
2518 should thus be invoked without an absolute
2519 pathname. Maintainer scripts should also not reset the
2520 <tt>PATH</tt>, though they might choose to modify it by pre-
2521 or appending package-specific directories. These
2522 considerations really apply to all shell scripts.</p>
2525 <heading>Maintainer scripts Idempotency</heading>
2528 It is very important to make maintainer scripts
2532 That means that if it runs successfully or fails
2533 and then you call it again it doesn't bomb out,
2534 but just ensures that everything is the way it
2537 </footnote> This is so that if an error occurs, the
2538 user interrupts <prgn>dpkg</prgn> or some other
2539 unforeseen circumstance happens you don't leave the
2540 user with a badly-broken package.
2544 <heading>Controlling terminal for maintainer scripts</heading>
2547 The maintainer scripts are guaranteed to run with a
2548 controlling terminal and can interact with the user.
2549 If they need to prompt for passwords, do full-screen
2550 interaction or something similar you should do these
2551 things to and from <tt>/dev/tty</tt>, since
2552 <prgn>dpkg</prgn> will at some point redirect scripts'
2553 standard input and output so that it can log the
2554 installation process. Likewise, because these scripts
2555 may be executed with standard output redirected into a
2556 pipe for logging purposes, Perl scripts should set
2557 unbuffered output by setting <tt>$|=1</tt> so that the
2558 output is printed immediately rather than being
2563 Each script should return a zero exit status for
2564 success, or a nonzero one for failure.
2568 <sect id="mscriptsinstact"><heading>Summary of ways maintainer
2573 <list compact="compact">
2575 <p><var>new-preinst</var> <tt>install</tt></p>
2578 <p><var>new-preinst</var> <tt>install</tt>
2579 <var>old-version</var></p>
2582 <p><var>new-preinst</var> <tt>upgrade</tt>
2583 <var>old-version</var></p>
2586 <p><var>old-preinst</var> <tt>abort-upgrade</tt>
2587 <var>new-version</var>
2593 <list compact="compact">
2595 <p><var>postinst</var> <tt>configure</tt>
2596 <var>most-recently-configured-version</var></p>
2599 <p><var>old-postinst</var> <tt>abort-upgrade</tt>
2600 <var>new version</var></p>
2603 <p><var>conflictor's-postinst</var> <tt>abort-remove</tt>
2604 <tt>in-favour</tt> <var>package</var>
2605 <var>new-version</var></p>
2609 <var>deconfigured's-postinst</var>
2610 <tt>abort-deconfigure</tt> <tt>in-favour</tt>
2611 <var>failed-install-package</var> <var>version</var>
2612 <tt>removing</tt> <var>conflicting-package</var>
2619 <list compact="compact">
2621 <p><var>prerm</var> <tt>remove</tt></p>
2624 <p><var>old-prerm</var> <tt>upgrade</tt>
2625 <var>new-version</var></p>
2628 <p><var>new-prerm</var> <tt>failed-upgrade</tt>
2629 <var>old-version</var></p>
2632 <p><var>conflictor's-prerm</var> <tt>remove</tt>
2633 <tt>in-favour</tt> <var>package</var>
2634 <var>new-version</var></p>
2638 <var>deconfigured's-prerm</var> <tt>deconfigure</tt>
2639 <tt>in-favour</tt> <var>package-being-installed</var>
2640 <var>version</var> <tt>removing</tt>
2641 <var>conflicting-package</var>
2648 <list compact="compact">
2650 <p><var>postrm</var> <tt>remove</tt></p>
2653 <p><var>postrm</var> <tt>purge</tt></p>
2657 <var>old-postrm</var> <tt>upgrade</tt>
2658 <var>new-version</var></p>
2661 <p><var>new-postrm</var> <tt>failed-upgrade</tt>
2662 <var>old-version</var></p>
2665 <p><var>new-postrm</var> <tt>abort-install</tt></p>
2668 <p><var>new-postrm</var> <tt>abort-install</tt>
2669 <var>old-version</var></p>
2672 <p><var>new-postrm</var> <tt>abort-upgrade</tt>
2673 <var>old-version</var></p>
2677 <var>disappearer's-postrm</var> <tt>disappear</tt>
2678 <var>overwriter</var>
2679 <var>overwriter-version</var></p></item>
2684 <sect id="unpackphase"><heading>Details of unpack phase of
2685 installation or upgrade
2689 The procedure on installation/upgrade/overwrite/disappear
2690 (i.e., when running <tt>dpkg --unpack</tt>, or the unpack
2691 stage of <tt>dpkg --install</tt>) is as follows. In each
2692 case if an error occurs the actions are, in general, run
2693 backwards - this means that the maintainer scripts are run
2694 with different arguments in reverse order. These are the
2695 `error unwind' calls listed below.
2702 <p>If a version of the package is already
2705 <var>old-prerm</var> upgrade <var>new-version</var>
2710 If the script runs but exits with a non-zero
2711 exit status, <prgn>dpkg</prgn> will attempt:
2713 <var>new-prerm</var> failed-upgrade <var>old-version</var>
2715 Error unwind, for both the above cases:
2717 <var>old-postinst</var> abort-upgrade <var>new-version</var>
2725 <p>If a `conflicting' package is being removed at the same time:
2729 If any packages depended on that conflicting
2730 package and <tt>--auto-deconfigure</tt> is
2731 specified, call, for each such package:
2733 <var>deconfigured's-prerm</var> deconfigure \
2734 in-favour <var>package-being-installed</var> <var>version</var> \
2735 removing <var>conflicting-package</var> <var>version</var>
2739 <var>deconfigured's-postinst</var> abort-deconfigure \
2740 in-favour <var>package-being-installed-but-failed</var> <var>version</var> \
2741 removing <var>conflicting-package</var> <var>version</var>
2743 The deconfigured packages are marked as
2744 requiring configuration, so that if
2745 <tt>--install</tt> is used they will be
2746 configured again if possible.</p>
2749 <p>To prepare for removal of the conflicting package, call:
2751 <var>conflictor's-prerm</var> remove in-favour <var>package</var> <var>new-version</var>
2755 <var>conflictor's-postinst</var> abort-remove \
2756 in-favour <var>package</var> <var>new-version</var>
2767 <p>If the package is being upgraded, call:
2769 <var>new-preinst</var> upgrade <var>old-version</var>
2774 Otherwise, if the package had some configuration
2775 files from a previous version installed (i.e., it
2776 is in the `configuration files only' state):
2778 <var>new-preinst</var> install <var>old-version</var>
2782 <p>Otherwise (i.e., the package was completely purged):
2784 <var>new-preinst</var> install
2786 Error unwind versions, respectively:
2788 <var>new-postrm</var> abort-upgrade <var>old-version</var>
2789 <var>new-postrm</var> abort-install <var>old-version</var>
2790 <var>new-postrm</var> abort-install
2800 The new package's files are unpacked, overwriting any
2801 that may be on the system already, for example any
2802 from the old version of the same package or from
2803 another package (backups of the old files are left
2804 around, and if anything goes wrong the package
2805 management system will attempt to put them back as
2806 part of the error unwind).
2810 It is an error for a package to contains files which
2811 are on the system in another package, unless
2812 <tt>Replaces</tt> is used (see <ref id="replaces">).
2813 Currently the <tt>--force-overwrite</tt> flag is
2814 enabled, downgrading it to a warning, but this may not
2819 It is a more serious error for a package to contain a
2820 plain file or other kind of non-directory where another
2821 package has a directory (again, unless
2822 <tt>Replaces</tt> is used). This error can be
2823 overridden if desired using
2824 <tt>--force-overwrite-dir</tt>, but this is not
2829 Packages which overwrite each other's files produce
2830 behavior which though deterministic is hard for the
2831 system administrator to understand. It can easily
2832 lead to `missing' programs if, for example, a package
2833 is installed which overwrites a file from another
2834 package, and is then removed again.
2837 Part of the problem is due to what is arguably a
2838 bug in <prgn>dpkg</prgn>.
2844 A directory will never be replaced by a symbolic links
2845 to a directory or vice versa; instead, the existing
2846 state (symlink or not) will be left alone and
2847 <prgn>dpkg</prgn> will follow the symlink if there is
2855 <p>If the package is being upgraded, call
2857 <var>old-postrm</var> upgrade <var>new-version</var>
2861 <p>If this fails, <prgn>dpkg</prgn> will attempt:
2863 <var>new-postrm</var> failed-upgrade <var>old-version</var>
2865 Error unwind, for both cases:
2867 <var>old-preinst</var> abort-upgrade <var>new-version</var>
2873 This is the point of no return - if
2874 <prgn>dpkg</prgn> gets this far, it won't back off
2875 past this point if an error occurs. This will
2876 leave the package in a fairly bad state, which
2877 will require a successful re-installation to clear
2878 up, but it's when <prgn>dpkg</prgn> starts doing
2879 things that are irreversible.
2884 Any files which were in the old version of the package
2885 but not in the new are removed.</p>
2888 <p>The new file list replaces the old.</p>
2891 <p>The new maintainer scripts replace the old.</p>
2895 <p>Any packages all of whose files have been overwritten during the
2896 installation, and which aren't required for
2897 dependencies, are considered to have been removed.
2898 For each such package,
2901 <p><prgn>dpkg</prgn> calls:
2903 <var>disappearer's-postrm</var> disappear \
2904 <var>overwriter</var> <var>overwriter-version</var>
2909 <p>The package's maintainer scripts are removed.
2914 It is noted in the status database as being in a
2915 sane state, namely not installed (any conffiles
2916 it may have are ignored, rather than being
2917 removed by <prgn>dpkg</prgn>). Note that
2918 disappearing packages do not have their prerm
2919 called, because <prgn>dpkg</prgn> doesn't know
2920 in advance that the package is going to
2929 Any files in the package we're unpacking that are also
2930 listed in the file lists of other packages are removed
2931 from those lists. (This will lobotomize the file list
2932 of the `conflicting' package if there is one.)
2937 The backup files made during installation, above, are
2944 The new package's status is now sane, and recorded as
2945 `unpacked'. Here is another point of no return - if
2946 the conflicting package's removal fails we do not
2947 unwind the rest of the installation; the conflicting
2948 package is left in a half-removed limbo.
2953 If there was a conflicting package we go and do the
2954 removal actions (described below), starting with the
2955 removal of the conflicting package's files (any that
2956 are also in the package being installed have already
2957 been removed from the conflicting package's file list,
2958 and so do not get removed now).
2965 <sect><heading>Details of configuration</heading>
2968 When we configure a package (this happens with <tt>dpkg
2969 --install</tt>, or with <tt>--configure</tt>), we first
2970 update the conffiles and then call:
2972 <var>postinst</var> configure <var>most-recently-configured-version</var>
2977 No attempt is made to unwind after errors during
2982 If there is no most recently configured version
2983 <prgn>dpkg</prgn> will pass a null argument; older versions
2984 of dpkg may pass <tt><unknown></tt> (including the
2985 angle brackets) in this case. Even older ones do not pass a
2986 second argument at all, under any circumstances.
2990 <sect><heading>Details of removal and/or configuration purging
2998 <var>prerm</var> remove
3004 The package's files are removed (except conffiles).
3009 <var>postrm</var> remove
3013 <p>All the maintainer scripts except the postrm are removed.
3017 If we aren't purging the package we stop here. Note
3018 that packages which have no postrm and no conffiles
3019 are automatically purged when removed, as there is no
3020 difference except for the <prgn>dpkg</prgn>
3025 The conffiles and any backup files (<tt>~</tt>-files,
3026 <tt>#*#</tt> files, <tt>%</tt>-files,
3027 <tt>.dpkg-{old,new,tmp}</tt>, etc.) are removed.</p>
3031 <var>postrm</var> purge
3035 <p>The package's file list is removed.</p>
3038 No attempt is made to unwind after errors during
3044 <chapt id="relationships"><heading>Declaring relationships between
3048 Packages can declare in their control file that they have
3049 certain relationships to other packages - for example, that
3050 they may not be installed at the same time as certain other
3051 packages, and/or that they depend on the presence of others,
3052 or that they should overwrite files in certain other packages
3057 This is done using the <tt>Depends</tt>, <tt>Recommends</tt>,
3058 <tt>Suggests</tt>, <tt>Enhances</tt>, <tt>Conflicts</tt>,
3059 <tt>Provides</tt> and <tt>Replaces</tt> control file fields.
3063 Source packages may declare relationships to binary packages,
3064 saying that they require certain binary packages to be
3065 installed or absent at the time of building the package.
3069 This is done using the <tt>Build-Depends</tt>,
3070 <tt>Build-Depends-Indep</tt>, <tt>Build-Conflicts</tt>, and
3071 <tt>Build-Conflicts-Indep</tt> control file fields.
3074 <sect id="depsyntax"><heading>Syntax of relationship fields
3078 These fields all have a uniform syntax. They are a list of
3079 package names separated by commas.
3083 In the <tt>Depends</tt>, <tt>Recommends</tt>,
3084 <tt>Suggests</tt>, <tt>Pre-Depends</tt>,
3085 <tt>Build-Depends</tt> and <tt>Build-Depends-Indep</tt>
3086 control file fields of the package, which declare
3087 dependencies on other packages, the package names listed may
3088 also include lists of alternative package names, separated
3089 by vertical bar symbols <tt>|</tt> (pipe symbols). In such
3090 a case, the presence of any one of the alternative packages
3091 is installed, that part of the dependency is considered to
3096 All the fields except <tt>Provides</tt> may restrict their
3097 applicability to particular versions of each named package.
3098 This is done in parentheses after each individual package
3099 name; the parentheses should contain a relation from the
3100 list below followed by a version number, in the format
3101 described in <ref id="versions">.
3105 The relations allowed are <tt><<</tt>, <tt><=</tt>,
3106 <tt>=</tt>, <tt>>=</tt> and <tt>>></tt> for
3107 strictly earlier, earlier or equal, exactly equal, later or
3108 equal and strictly later, respectively. The forms
3109 <tt><</tt> and <tt>></tt> were used to mean
3110 earlier/later or equal, rather than strictly earlier/later,
3111 so they should not appear in new packages (though
3112 <prgn>dpkg</prgn> still supports them).
3116 Whitespace may appear at any point in the version
3117 specification, and must appear where it's necessary to
3118 disambiguate; it is not otherwise significant. For
3119 consistency and in case of future changes to
3120 <prgn>dpkg</prgn> it is recommended that a single space be
3121 used after a version relationship and before a version
3122 number; it is usual also to put a single space after each
3123 comma, on either side of each vertical bar, and before each
3132 Depends: libc5 (>= 5.2.18-4), mime-support, csh | tcsh
3137 All fields that specify build-time relationships
3138 (<tt>Build-Depends</tt>, <tt>Build-Depends-Indep</tt>,
3139 <tt>Build-Conflicts</tt> and <tt>Build-Conflicts-Indep</tt>)
3140 may be restricted to a certain set of architectures. This
3141 is done in brackets after each individual package name and
3142 the optional version specification. The brackets enclose a
3143 list of Debian architecture names separated by whitespace.
3144 An exclamation mark may be prepended to each name. If the
3145 current Debian host architecture is not in this list and
3146 there are no exclamation marks in the list, or it is in the
3147 list with a prepended exclamation mark, the package name and
3148 the associated version specification are ignored completely
3149 for the purposes of defining the relationships.
3156 Build-Depends-Indep: texinfo
3157 Build-Depends: kernel-headers-2.2.10 [!hurd-i386],
3158 hurd-dev [hurd-i386], gnumach-dev [hurd-i386]
3164 <heading>Binary Dependencies - <tt>Depends</tt>,
3165 <tt>Recommends</tt>, <tt>Suggests</tt>, <tt>Enhances</tt>,
3166 <tt>Pre-Depends</tt>
3170 These five fields are used to declare a dependency
3171 relationship by one package on another. They appear in the
3172 depending package's control file.
3176 All but <tt>Pre-Depends</tt> and <tt>Conflicts</tt>
3177 (discussed below) take effect <em>only</em> when a package
3178 is to be configured. They do not prevent a package being on
3179 the system in an unconfigured state while its dependencies
3180 are unsatisfied, and it is possible to replace a package
3181 whose dependencies are satisfied and which is properly
3182 installed with a different version whose dependencies are
3183 not and cannot be satisfied; when this is done the depending
3184 package will be left unconfigured (since attempts to
3185 configure it will give errors) and will not function
3190 For this reason packages in an installation run are usually
3191 all unpacked first and all configured later; this gives
3192 later versions of packages with dependencies on later
3193 versions of other packages the opportunity to have their
3194 dependencies satisfied.
3198 Thus <tt>Depends</tt> allows package maintainers to impose
3199 an order in which packages should be configured.
3201 <tag><tt>Depends</tt></tag>
3204 <p>This declares an absolute dependency.
3208 The <tt>Depends</tt> field should be used if the
3209 depended-on package is required for the depending
3210 package to provide a significant amount of
3214 <tag><tt>Recommends</tt></tag>
3216 <p>This declares a strong, but not absolute, dependency.
3220 The <tt>Recommends</tt> field should list packages
3221 that would be found together with this one in all but
3222 unusual installations.</p>
3225 <tag><tt>Suggests</tt></tag>
3229 This is used to declare that one package may be more
3230 useful with one or more others. Using this field
3231 tells the packaging system and the user that the
3232 listed packages are related to this one and can
3233 perhaps enhance its usefulness, but that installing
3234 this one without them is perfectly reasonable.
3238 <tag><tt>Enhances</tt></tag>
3241 This field is similar to Suggests but works in the
3242 opposite direction. It is used to declare that a
3243 package can enhance the functionality of another
3248 <tag><tt>Pre-Depends</tt></tag>
3252 This field is like <tt>Depends</tt>, except that it
3253 also forces <prgn>dpkg</prgn> to complete installation
3254 of the packages named before even starting the
3255 installation of the package which declares the
3260 <tt>Pre-Depends</tt> should be used sparingly,
3261 preferably only by packages whose premature upgrade or
3262 installation would hamper the ability of the system to
3263 continue with any upgrade that might be in progress.
3267 When the package declaring it is being configured, a
3268 <tt>Pre-Dependency</tt> will be considered satisfied
3269 only if the depending package has been correctly
3270 configured, just as if an ordinary <tt>Depends</tt>
3275 However, when a package declaring a Pre-dependency is
3276 being unpacked the predependency can be satisfied even
3277 if the depended-on package(s) are only unpacked or
3278 half-configured, provided that they have been
3279 configured correctly at some point in the past (and
3280 not removed or partially removed since). In this case
3281 both the previously-configured and currently unpacked
3282 or half-configured versions must satisfy any version
3283 clause in the <tt>Pre-Depends</tt> field.
3289 When selecting which level of dependency to use you should
3290 consider how important the depended-on package is to the
3291 functionality of the one declaring the dependency. Some
3292 packages are composed of components of varying degrees of
3293 importance. Such a package should list using
3294 <tt>Depends</tt> the package(s) which are required by the
3295 more important components. The other components'
3296 requirements may be mentioned as Suggestions or
3297 Recommendations, as appropriate to the components' relative
3302 <sect id="conflicts"><heading>Alternative binary packages -
3303 <tt>Conflicts</tt> and <tt>Replaces</tt>
3307 When one binary package declares a conflict with another
3308 <prgn>dpkg</prgn> will refuse to allow them to be installed
3309 on the system at the same time.
3313 If one package is to be installed, the other must be removed
3314 first - if the package being installed is marked as
3315 replacing (<ref id="replaces">) the one on the system, or
3316 the one on the system is marked as deselected, or both
3317 packages are marked <tt>Essential</tt>, then
3318 <prgn>dpkg</prgn> will automatically remove the package
3319 which is causing the conflict, otherwise it will halt the
3320 installation of the new package with an error. This
3321 mechanism specifically doesn't work when the installed
3322 package is <tt>Essential</tt>, but the new package is not.
3327 A package will not cause a conflict merely because its
3328 configuration files are still installed; it must be at least
3333 A special exception is made for packages which declare a
3334 conflict with their own package name, or with a virtual
3335 package which they provide (see below): this does not
3336 prevent their installation, and allows a package to conflict
3337 with others providing a replacement for it. You use this
3338 feature when you want the package in question to be the only
3339 package providing something.
3343 A <tt>Conflicts</tt> entry should almost never have an
3344 `earlier than' version clause. This would prevent
3345 <prgn>dpkg</prgn> from upgrading or installing the package
3346 which declared such a conflict until the upgrade or removal
3347 of the conflicted-with package had been completed.
3351 <sect id="virtual"><heading>Virtual packages - <tt>Provides</tt>
3355 As well as the names of actual (`concrete') packages, the
3356 package relationship fields <tt>Depends</tt>,
3357 <tt>Build-Depends</tt>, <tt>Build-Depends-Indep</tt>,
3358 <tt>Recommends</tt>, <tt>Suggests</tt>, <tt>Conflicts</tt>,
3359 <tt>Build-Conflicts</tt> and <tt>Build-Conflicts-Indep</tt> may
3360 mention virtual packages.
3364 A virtual package is one which appears in the
3365 <tt>Provides</tt> control file field of another package.
3366 The effect is as if the package(s) which provide a
3367 particular virtual package name had been listed by name
3368 everywhere the virtual package name appears.
3372 If there are both a real and a virtual package of the same
3373 name then the dependency may be satisfied (or the conflict
3374 caused) by either the real package or any of the virtual
3375 packages which provide it. This is so that, for example,
3381 and someone else releases an xemacs package they can say
3385 </example> and all will work in the interim (until a purely
3386 virtual package name is decided on and the <tt>emacs</tt>
3387 and <tt>vm</tt> packages are changed to use it).
3391 If a dependency or a conflict has a version number attached
3392 then only real packages will be considered to see whether
3393 the relationship is satisfied (or the prohibition violated,
3394 for a conflict) - it is assumed that a real package which
3395 provides the virtual package is not of the `right' version.
3396 So, a <tt>Provides</tt> field may not contain version
3397 numbers, and the version number of the concrete package
3398 which provides a particular virtual package will not be
3399 looked at when considering a dependency on or conflict with
3400 the virtual package name.
3404 It is likely that the ability will be added in a future
3405 release of <prgn>dpkg</prgn> to specify a version number for
3406 each virtual package it provides. This feature is not yet
3407 present, however, and is expected to be used only
3412 If you want to specify which of a set of real packages should be the
3413 default to satisfy a particular dependency on a virtual package, you
3414 should list the real package as an alternative before the virtual.
3419 <sect id="replaces"><heading><tt>Replaces</tt> - overwriting
3420 files and replacing packages
3424 The <tt>Replaces</tt> control file field has two purposes,
3425 which come into play in different situations.
3429 Virtual packages (<ref id="virtual">) are not considered
3430 when looking at a <tt>Replaces</tt> field - the packages
3431 declared as being replaced must be mentioned by their real
3435 <sect1><heading>Overwriting files in other packages
3439 Firstly, as mentioned before, it is usually an error for a
3440 package to contain files which are on the system in
3441 another package, though currently the
3442 <tt>--force-overwrite</tt> flag is enabled by default,
3443 downgrading the error to a warning,
3447 If the overwriting package declares that it replaces the
3448 one containing the file being overwritten then
3449 <prgn>dpkg</prgn> will proceed, and replace the file from
3450 the old package with that from the new. The file will no
3451 longer be listed as `owned' by the old package.
3455 If a package is completely replaced in this way, so that
3456 <prgn>dpkg</prgn> does not know of any files it still
3457 contains, it is considered to have disappeared. It will
3458 be marked as not wanted on the system (selected for
3459 removal) and not installed. Any conffiles details noted
3460 in the package will be ignored, as they will have been
3461 taken over by the replacing package(s). The package's
3462 <prgn>postrm</prgn> script will be run to allow the
3463 package to do any final cleanup required. See <ref
3464 id="mscriptsinstact">.
3468 In the future <prgn>dpkg</prgn> will discard files which
3469 would overwrite those from an already installed package
3470 which declares that it replaces the package being
3471 installed. This is so that you can install an older
3472 version of a package without problems.
3476 This usage of <tt>Replaces</tt> only takes effect when
3477 both packages are at least partially on the system at
3478 once, so that it can only happen if they do not conflict
3479 or if the conflict has been overridden.</p>
3482 <sect1><heading>Replacing whole packages, forcing their
3487 Secondly, <tt>Replaces</tt> allows the packaging system to
3488 resolve which package should be removed when there is a
3489 conflict - see <ref id="conflicts">. This usage only
3490 takes effect when the two packages <em>do</em> conflict,
3491 so that the two effects do not interfere with each other.
3496 <sect><heading>Relationships between source and binary packages -
3497 <tt>Build-Depends</tt>, <tt>Build-Depends-Indep</tt>,
3498 <tt>Build-Conflicts</tt>, <tt>Build-Conflicts-Indep</tt>
3502 A source package may declare a dependency or a conflict on a
3503 binary package. This is done with the control file fields
3504 <tt>Build-Depends</tt>, <tt>Build-Depends-Indep</tt>,
3505 <tt>Build-Conflicts</tt>, and
3506 <tt>Build-Conflicts-Indep</tt>. Their semantics are that
3507 the dependencies and conflicts they define must be satisfied
3508 (as defined earlier for binary packages), when one of the
3509 targets in <tt>debian/rules</tt> that the particular field
3510 applies to is invoked.
3513 <tag><tt>Build-Depends</tt>, <tt>Build-Conflicts</tt></tag>
3516 The <tt>Build-Depends</tt> and
3517 <tt>Build-Conflicts</tt> fields apply to the targets
3518 <tt>build</tt>, <tt>binary</tt>, <tt>binary-arch</tt>
3519 and <tt>binary-indep</tt>.
3522 <tag><tt>Build-Depends-Indep</tt>, <tt>Build-Conflicts-Indep</tt></tag>
3525 The <tt>Build-Depends-Indep</tt> and
3526 <tt>Build-Conflicts-Indep</tt> fields apply to the
3527 targets <tt>binary</tt> and <tt>binary-indep</tt>.
3538 <chapt id="conffiles"><heading>Configuration file handling
3542 <prgn>dpkg</prgn> can do a certain amount of automatic
3543 handling of package configuration files.
3547 Whether this mechanism is appropriate depends on a number of
3548 factors, but basically there are two approaches to any
3549 particular configuration file.
3553 The easy method is to ship a best-effort configuration in the
3554 package, and use <prgn>dpkg</prgn>'s conffile mechanism to
3555 handle updates. If the user is unlikely to want to edit the
3556 file, but you need them to be able to without losing their
3557 changes, and a new package with a changed version of the file
3558 is only released infrequently, this is a good approach.
3562 The hard method is to build the configuration file from
3563 scratch in the <prgn>postinst</prgn> script, and to take the
3564 responsibility for fixing any mistakes made in earlier
3565 versions of the package automatically. This will be
3566 appropriate if the file is likely to need to be different on
3571 <chapt id="sharedlibs"><heading>Shared libraries
3575 Packages containing shared libraries must be constructed with
3576 a little care to make sure that the shared library is always
3577 available. This is especially important for packages whose
3578 shared libraries are vitally important, such as the libc.
3582 Firstly, your package should install the shared libraries
3583 under their normal names. For example, the
3584 <prgn>libgdbm1</prgn> package should install
3585 <tt>libgdbm.so.1.7.3</tt> as
3586 <tt>/usr/lib/libgdbm.so.1.7.3</tt>. The files should not be
3587 renamed or re-linked by any prerm or postrm scripts;
3588 <prgn>dpkg</prgn> will take care of renaming things safely
3589 without affecting running programs, and attempts to interfere
3590 with this are likely to lead to problems.
3594 Secondly, your package should include the symlink that
3595 <prgn>ldconfig</prgn> would create for the shared libraries.
3596 For example, the <prgn>libgdbm1</prgn> package should include
3597 a symlink from <tt>/usr/lib/libgdbm.so.1</tt> to
3598 <tt>libgdbm.so.1.7.3</tt>. This is needed so that
3599 <prgn>ld.so</prgn> can find the library in between the time
3600 <prgn>dpkg</prgn> installs it and <prgn>ldconfig</prgn> is run
3601 in the <prgn>postinst</prgn> script. Furthermore, older
3602 versions of the package management system required the library
3603 must be placed before the symlink pointing to it in the
3604 <tt>.deb</tt> file. This is so that by the time
3605 <prgn>dpkg</prgn> comes to install the symlink (overwriting
3606 the previous symlink pointing at an older version of the
3607 library) the new shared library is already in place.
3608 Unfortunately, this was not not always possible, since it
3609 highly depends on the behavior of the file system. Some
3610 file systems (such as reiserfs) will reorder the files so it
3611 doesn't matter in what order you create them. Starting with
3612 release <tt>1.7.0</tt> <prgn>dpkg</prgn> will reorder the
3613 files itself when building a package.
3617 Thirdly, the development package should contain a symlink for
3618 the shared library without a version number. For example, the
3619 <tt>libgdbm1-dev</tt> package should include a symlink from
3620 <tt>/usr/lib/libgdm.so</tt> to <tt>libgdm.so.1.7.3</tt>. This
3621 symlink is needed by <prgn>ld</prgn> when compiling packages
3622 as it will only look for <tt>libgdm.so</tt> and
3623 <tt>libgdm.a</tt> when compiling dynamically or statically,
3628 Any package installing shared libraries in a directory that's listed
3629 in <tt>/etc/ld.so.conf</tt> or in one of the default library
3630 directories of <prgn>ld.so</prgn> (currently, these are <tt>/usr/lib</tt>
3631 and <tt>/lib</tt>) must call <prgn>ldconfig</prgn> in its <prgn>postinst</prgn>
3632 script if and only if the first argument is `configure'. However, it
3633 is important not to call <prgn>ldconfig</prgn> in the postrm or preinst
3634 scripts in the case where the package is being upgraded (see <ref
3635 id="unpackphase">), as <prgn>ldconfig</prgn> will see the temporary names
3636 that <prgn>dpkg</prgn> uses for the files while it is
3637 installing them and will make the shared library links point
3638 to them, just before <prgn>dpkg</prgn> continues the
3639 installation and removes the links!
3642 <sect id="shlibs"><heading>The <tt>shlibs</tt> File Format
3646 This file is for use by <prgn>dpkg-shlibdeps</prgn> and is
3647 required when your package provides shared libraries.
3651 Each line is of the form:
3653 <var>library-name</var> <var>version-or-soname</var> <var>dependencies ...</var>
3658 <var>library-name</var> is the name of the shared library,
3659 for example <tt>libc5</tt>.
3663 <var>version-or-soname</var> is the soname of the library -
3664 i.e., the thing that must exactly match for the library to be
3665 recognized by <prgn>ld.so</prgn>. Usually this is the major
3666 version number of the library.
3670 <var>dependencies</var> has the same syntax as a dependency
3671 field in a binary package control file. It should give
3672 details of which package(s) are required to satisfy a binary
3673 built against the version of the library contained in the
3674 package. See <ref id="depsyntax">.
3678 For example, if the package <tt>foo</tt> contains
3679 <tt>libfoo.so.1.2.3</tt>, where the soname of the library is
3680 <tt>libfoo.so.1</tt>, and the first version of the package
3681 which contained a minor number of at least <tt>2.3</tt> was
3682 <var>1.2.3-1</var>, then the package's <var>shlibs</var>
3685 libfoo 1 foo (>= 1.2.3-1)
3690 The version-specific dependency is to avoid warnings from
3691 <prgn>ld.so</prgn> about using older shared libraries with
3695 <sect><heading>Further Technical information on
3696 <tt>shlibs</tt></heading>
3698 <sect1><heading><em>What</em> are the <tt>shlibs</tt> files?
3702 The <tt>debian/shlibs</tt> file provides a way of checking
3703 for shared library dependencies on packaged binaries.
3704 They are intended to be used by package maintainers to
3705 make their lives easier.
3709 Other <tt>shlibs</tt> files that exist on a Debian system are
3711 <item> <p><tt>/etc/dpkg/shlibs.default</tt></p></item>
3712 <item> <p><tt>/etc/dpkg/shlibs.override</tt></p></item>
3713 <item> <p><tt>/var/lib/dpkg/info/*.shlibs</tt></p></item>
3714 <item> <p><tt>debian/shlibs.local</tt></p></item>
3716 These files are used by <prgn>dpkg-shlibdeps</prgn> when
3717 creating a binary package.</p>
3720 <sect1><heading><em>How</em> does <prgn>dpkg-shlibdeps</prgn>
3724 <prgn>dpkg-shlibdeps</prgn>
3725 determines the shared libraries directly
3728 It used to do this by calling <prgn>ldd</prgn>, but it
3729 now calls <prgn>objdump</prgn> to to this. This
3730 requires a couple of changes in the way that packages
3734 A binary <tt>foo</tt> directly uses a library
3735 <tt>libbar</tt> if it is linked with that
3736 library. Other libraries that are needed by
3737 <tt>libbar</tt> are linked indirectly to <tt>foo</tt>,
3738 and the dynamic linker will load them automatically
3739 when it loads <tt>libbar</tt>. Running<prgn>ldd</prgn>
3740 lists all of the libraries used, both directly and
3741 indirectly; but <prgn>objdump</prgn> only lists the
3742 directly linked libraries. A package only needs to
3743 depend on the libraries it is directly linked to,
3744 since the dependencies for those libraries should
3745 automatically pull in the other libraries.
3748 This change does mean a change in the way packages are
3749 build though: currently <prgn>dpkg-shlibdeps</prgn> is
3750 only run on binaries. But since we will now rely on the
3751 libraries depending on the libraries they themselves
3752 need, the packages containing those libraries will
3753 need to run <prgn>dpkg-shlibdeps</prgn> on the
3757 A good example where this would help us is the current
3758 mess with multiple version of the <tt>mesa</tt>
3759 library. With the <prgn>ldd</prgn>-based system, every
3760 package that uses <tt>mesa</tt> needs to add a
3761 dependency on <tt>svgalib|svgalib-dummy</tt> in order
3762 to handle the glide <tt>mesa</tt> variant. With an
3763 <prgn>objdump</prgn>-based system this isn't necessary
3764 anymore and would have saved everyone a lot of work.
3767 Another example: we could update <tt>libimlib</tt>
3768 with a new version that supports a new graphics format
3769 called dgf. If we use the old <prgn>ldd</prgn> method,
3770 every package that uses <tt>libimlib</tt> would need
3771 to be recompiled so it would also depend on
3772 <tt>libdgf</tt> or it wouldn't run due to missing
3773 symbols. However with the new system, packages using
3774 <tt>libimlib</tt> can rely on <tt>libimlib</tt> itself
3775 having the dependency on <tt>libdgf</tt> and wouldn't
3779 used by the compiled binaries and libraries passed through
3780 on its command line.
3784 For each shared library linked to,
3785 <prgn>dpkg-shlibdeps</prgn> needs to know
3786 <list compact="compact">
3787 <item><p>the package containing the library, and</p></item>
3788 <item><p>the library version number,</p></item>
3790 and it scans the following files in this order:
3791 <enumlist compact="compact">
3792 <item><p><tt>debian/shlibs.local</tt></p></item>
3793 <item><p><tt>/etc/dpkg/shlibs.override</tt></p></item>
3794 <item><p><tt>/var/lib/dpkg/info/*.shlibs</tt></p></item>
3795 <item><p><tt>/etc/dpkg/shlibs.default</tt></p></item>
3800 <sect1><heading><em>Who</em> maintains the various
3801 <tt>shlibs</tt> files?
3805 <list compact="compact">
3807 <p><tt>/etc/dpkg/shlibs.default</tt> - the maintainer
3812 <tt>/var/lib/dpkg/info/<var>package</var>.shlibs</tt>
3813 - the maintainer of each package</p>
3817 <tt>/etc/dpkg/shlibs.override</tt> - the local
3818 system administrator</p>
3821 <p><tt>debian/shlibs.local</tt> - the maintainer of
3826 The <tt>shlibs.default</tt> file is managed by
3827 <prgn>dpkg</prgn>. The entries in <tt>shlibs.default</tt>
3828 that are provided by <prgn>dpkg</prgn> are just there to
3829 fix things until the shared library packages all have
3830 <tt>shlibs</tt> files.
3834 <sect1><heading><em>How</em> to use <prgn>dpkg-shlibdeps</prgn> and
3835 the <tt>shlibs</tt> files
3838 <sect2><heading>If your package doesn't provide a shared
3843 Put a call to <prgn>dpkg-shlibdeps</prgn> into your
3844 <tt>debian/rules</tt> file. If your package contains
3845 only binaries (e.g. no scripts) use:
3847 dpkg-shlibdeps debian/tmp/usr/bin/* debian/tmp/usr/sbin/*
3849 If <prgn>dpkg-shlibdeps</prgn> doesn't complain, you're
3850 done. If it does complain you might need to create your
3851 own <tt>debian/shlibs.local</tt> file.</p>
3854 <sect2><heading>If your package provides a shared library
3858 Create a <tt>debian/shlibs</tt> file and let
3859 <tt>debian/rules</tt> install it in the control area:
3861 install -m644 debian/shlibs debian/tmp/DEBIAN
3863 If your package contains additional binaries see above.
3868 <sect1><heading><em>How</em> to write
3869 <tt>debian/shlibs.local</tt>
3873 This file is intended only as a <em>temporary</em> fix if
3874 your binaries depend on a library which doesn't provide
3875 its own <tt>/var/lib/dpkg/info/*.shlibs</tt> file yet.
3879 Let's assume you are packaging a binary <tt>foo</tt>. Your
3880 output in building the package might look like this.
3883 libbar.so.1 => /usr/X11R6/lib/libbar.so.1.0 (0x4001e000)
3884 libX11.so.6 => /usr/X11R6/lib/libX11.so.6 (0x4002c000)
3885 libc.so.6 => /lib/libc.so.6 (0x40114000)
3886 /lib/ld-linux.so.2 => /lib/ld-linux.so.2 (0x40000000)
3888 And when you ran <prgn>dpkg-shlibdeps</prgn>
3890 $ dpkg-shlibdeps -O foo
3891 dpkg-shlibdeps: warning: unable to find dependency information for shared library libbar
3892 (soname 1, path /usr/X11R6/lib/libbar.so.1.0, dependency field Depends)
3893 shlibs:Depends=libc6 (>= 2.2.1), xlibs (>= 4.0.1-11)
3895 The <prgn>foo</prgn> binary depends on the
3896 <prgn>libbar</prgn> shared library, but no package seems
3897 to provide a <tt>*.shlibs</tt> file in
3898 <tt>/var/lib/dpkg/info/</tt>. Let's determine the package
3904 $ dpkg -S /usr/X11R6/lib/libbar.so.1.0
3905 bar1: /usr/X11R6/lib/libbar.so.1.0
3906 $ dpkg -s bar1 | grep Version
3909 This tells us that the <prgn>bar1</prgn> package, version
3910 1.0-1 is the one we are using. Now we can create our own
3911 <tt>debian/shlibs.local</tt> to temporarily fix the above
3912 problem. Include the following line into your
3913 <tt>debian/shlibs.local</tt> file.
3915 libbar 1 bar1 (>= 1.0-1)
3917 Now your package build should work. As soon as the
3918 maintainer of <prgn>libbar1</prgn> provides a
3919 <tt>shlibs</tt> file, you can remove your
3920 <tt>debian/shlibs.local</tt> file.
3926 <chapt><heading>The Operating System</heading>
3930 <heading>File system hierarchy</heading>
3934 <heading>Linux File system Structure</heading>
3937 The location of all installed files and directories must
3938 comply with the Linux File system Hierarchy Standard
3939 (FHS). The latest version of this document can be found
3940 alongside this manual or on
3941 <url id="http://www.pathname.com/fhs/">.
3942 Specific questions about following the standard may be
3943 asked on <prgn>debian-devel</prgn>, or referred to Daniel
3944 Quinlan, the FHS coordinator, at
3945 <email>quinlan@pathname.com</email>.</p></sect1>
3949 <heading>Site-specific programs</heading>
3952 As mandated by the FHS, packages must not place any
3953 files in <tt>/usr/local</tt>, either by putting them in
3954 the file system archive to be unpacked by <prgn>dpkg</prgn>
3955 or by manipulating them in their maintainer scripts.</p>
3958 However, the package may create empty directories below
3959 <tt>/usr/local</tt> so that the system administrator knows
3960 where to place site-specific files. These directories
3961 should be removed on package removal if they are
3965 Note, that this applies only to directories <em>below</em>
3966 <tt>/usr/local</tt>, not <em>in</em>
3967 <tt>/usr/local</tt>. Packages must not create sub-directories
3968 in the directory <tt>/usr/local</tt> itself, except those listed in
3969 FHS, section 4.5. However, you may create directories
3970 below them as you wish. You must not remove any of the
3971 directories listed in 4.5, even if you created them.</p>
3974 Since <tt>/usr/local</tt> can be mounted read-only from a
3975 remote server, these directories must be created and
3976 removed by the <tt>postinst</tt> and <tt>prerm</tt>
3977 maintainer scripts. These scripts must not fail if either
3978 of these operations fail. (In the future, it will be
3979 possible to tell <prgn>dpkg</prgn> not to unpack files
3980 matching certain patterns, so that the directories can be
3981 included in the <tt>.deb</tt> packages and system
3982 administrators who do not wish these directories in
3983 /usr/local do not need to have them.)</p>
3986 For example, the <prgn>emacs</prgn> package will contain
3988 mkdir -p /usr/local/lib/emacs/site-lisp || true
3990 in the <tt>postinst</tt> script, and
3992 rmdir /usr/local/lib/emacs/site-lisp || true
3993 rmdir /usr/local/lib/emacs || true
3995 in the <tt>prerm</tt> script.</p>
3998 If you do create a directory in <tt>/usr/local</tt> for
3999 local additions to a package, you should ensure that
4000 settings in <tt>/usr/local</tt> take precedence over the
4001 equivalents in <tt>/usr</tt>.</p>
4004 However, because '/usr/local' and its contents are for
4005 exclusive use of the local administrator, a package must
4006 not rely on the presence or absence of files or
4007 directories in '/usr/local' for normal operation.</p>
4010 The <tt>/usr/local</tt> directory itself and all the
4011 subdirectories created by the package should (by default) have
4012 permissions 2775 (group-writable and set-group-id) and be
4013 owned by <tt>root.staff</tt>.</p>
4018 <heading>Users and groups</heading>
4021 The Debian system can be configured to use either plain or
4022 shadow passwords.</p>
4025 Some user ids (UIDs) and group ids (GIDs) are reserved
4026 globally for use by certain packages. Because some packages
4027 need to include files which are owned by these users or
4028 groups, or need the ids compiled into binaries, these ids
4029 must be used on any Debian system only for the purpose for
4030 which they are allocated. This is a serious restriction, and
4031 we should avoid getting in the way of local administration
4032 policies. In particular, many sites allocate users and/or
4033 local system groups starting at 100.</p>
4036 Apart from this we should have dynamically allocated ids,
4037 which should by default be arranged in some sensible
4038 order--but the behavior should be configurable.</p>
4041 Packages other than <tt>base-passwd</tt> must not modify
4042 <tt>/etc/passwd</tt>, <tt>/etc/shadow</tt>,
4043 <tt>/etc/group</tt> or <tt>/etc/gshadow</tt>.</p>
4046 The UID and GID ranges are as follows:
4051 Globally allocated by the Debian project, the
4052 same on every Debian system. These ids will appear in
4053 the <tt>passwd</tt> and <tt>group</tt> files of all
4054 Debian systems, new ids in this range being added
4055 automatically as the <tt>base-passwd</tt> package is
4059 Packages which need a single statically allocated uid
4060 or gid should use one of these; their maintainers
4061 should ask the <tt>base-passwd</tt> maintainer for
4068 Dynamically allocated system users and groups.
4069 Packages which need a user or group, but can have this
4070 user or group allocated dynamically and differently on
4071 each system, should use `<tt>adduser --system</tt>' to
4072 create the group and/or user. <prgn>adduser</prgn>
4073 will check for the existence of the user or group, and
4074 if necessary choose an unused id based on the ranges
4075 specified in <tt>adduser.conf</tt>.</p></item>
4078 <tag>1000-29999:</tag>
4081 Dynamically allocated user accounts. By default
4082 <prgn>adduser</prgn> will choose UIDs and GIDs for
4083 user accounts in this range, though
4084 <tt>adduser.conf</tt> may be used to modify this
4088 <tag>30000-59999:</tag>
4090 <p>Reserved.</p></item>
4093 <tag>60000-64999:</tag>
4096 Globally allocated by the Debian project, but only
4097 created on demand. The ids are allocated centrally and
4098 statically, but the actual accounts are only created
4099 on users' systems on demand.</p>
4102 These ids are for packages which are obscure or which
4103 require many statically-allocated ids. These packages
4104 should check for and create the accounts in
4105 <tt>/etc/passwd</tt> or <tt>/etc/group</tt> (using
4106 <prgn>adduser</prgn> if it has this facility) if
4107 necessary. Packages which are likely to require
4108 further allocations should have a `hole' left after
4109 them in the allocation, to give them room to
4113 <tag>65000-65533:</tag>
4115 <p>Reserved.</p></item>
4120 <p>User `<tt>nobody</tt>.' The corresponding gid refers
4121 to the group `<tt>nogroup</tt>.'</p></item>
4127 <tt>(uid_t)(-1) == (gid_t)(-1)</tt>. NOT TO BE USED,
4128 because it is the error return sentinel value.</p>
4133 <sect id="sysvinit">
4134 <heading>System run levels</heading>
4137 <sect1 id="/etc/init.d">
4138 <heading>Introduction</heading>
4141 The <tt>/etc/init.d</tt> directory contains the scripts
4142 executed by <prgn>init</prgn> at boot time and when init
4143 state (or `runlevel') is changed (see <manref name="init"
4147 There are at least two different, yet functionally
4148 equivalent, ways of handling these scripts. For the sake
4149 of simplicity, this document describes only the symbolic
4150 link method. However, it must not be assumed by maintainer
4151 scripts that this method is being used, and any automated
4152 manipulation of the various runlevel behaviours by
4153 maintainer scripts must be performed using `update-rc.d'
4154 as described below and not by manually installing or
4155 removing symlinks. For information on the
4156 implementation details of the other method, implemented in
4157 the <tt>file-rc</tt> package, please refer to the
4158 documentation of that package.</p>
4161 These scripts are referenced by symbolic links in
4162 the <tt>/etc/rc<var>n</var>.d</tt> directories. When
4163 changing runlevels, <prgn>init</prgn> looks in the
4164 directory <tt>/etc/rc<var>n</var>.d</tt> for the scripts
4165 it should execute, where <var>n</var> is the runlevel that
4166 is being changed to, or `S' for the boot-up scripts.</p>
4169 The names of the links all have the form
4170 <tt>S<var>mm</var><var>script</var></tt> or
4171 <tt>K<var>mm</var><var>script</var></tt> where
4172 <var>mm</var> is a two-digit number and <var>script</var>
4173 is the name of the script (this should be the same as the
4174 name of the actual script in <tt>/etc/init.d</tt>.</p>
4177 When <prgn>init</prgn> changes runlevel first the targets
4178 of the links whose names starting with a <tt>K</tt> are
4179 executed, each with the single argument <tt>stop</tt>,
4180 followed by the scripts prefixed with an <tt>S</tt>, each
4181 with the single argument <tt>start</tt>. The <tt>K</tt>
4182 links are responsible for killing services and the
4183 <tt>S</tt> link for starting services upon entering the
4187 For example, if we are changing from runlevel 2 to
4188 runlevel 3, init will first execute all of the <tt>K</tt>
4189 prefixed scripts it finds in <tt>/etc/rc3.d</tt>, and then
4190 all of the <tt>S</tt> prefixed scripts. The links
4191 starting with <tt>K</tt> will cause the referred-to file
4192 to be executed with an argument of <tt>stop</tt>, and the
4193 <tt>S</tt> links with an argument of <tt>start</tt>.</p>
4196 The two-digit number <var>mm</var> is used to decide which
4197 order to start and stop things in--low-numbered links have
4198 their scripts run first. For example, the <tt>K20</tt>
4199 scripts will be executed before the <tt>K30</tt> scripts.
4200 This is used when a certain service must be started before
4201 another. For example, the name server <prgn>bind</prgn>
4202 might need to be started before the news server
4203 <prgn>inn</prgn> so that <prgn>inn</prgn> can set up its
4204 access lists. In this case, the script that starts
4205 <prgn>bind</prgn> would have a lower number than the
4206 script that starts <prgn>inn</prgn> so that it runs first:
4215 <heading>Writing the scripts</heading>
4218 Packages that include daemons for system services should
4219 place scripts in <tt>/etc/init.d</tt> to start or stop
4220 services at boot time or during a change of runlevel.
4221 These scripts should be named
4222 <tt>/etc/init.d/<var>package</var></tt>, and they should
4223 accept one argument, saying what to do:
4226 <tag><tt>start</tt></tag>
4227 <item><p>start the service,</p></item>
4229 <tag><tt>stop</tt></tag>
4230 <item><p>stop the service,</p></item>
4232 <tag><tt>restart</tt></tag>
4233 <item><p>stop and restart the service,</p></item>
4235 <tag><tt>reload</tt></tag>
4236 <item><p>cause the configuration of the service to be
4237 reloaded without actually stopping and restarting
4238 the service,</p></item>
4240 <tag><tt>force-reload</tt></tag> <item><p>cause the
4241 configuration to be reloaded if the service supports
4242 this, otherwise restart the service.</p></item>
4245 The <tt>start</tt>, <tt>stop</tt>, <tt>restart</tt>, and
4246 <tt>force-reload</tt> options should be supported by all
4247 scripts in <tt>/etc/init.d</tt>, the <tt>reload</tt>
4248 option is optional.</p>
4251 The <tt>init.d</tt> scripts should ensure that they will
4252 behave sensibly if invoked with <tt>start</tt> when the
4253 service is already running, or with <tt>stop</tt> when it
4254 isn't, and that they don't kill unfortunately-named user
4255 processes. The best way to achieve this is usually to use
4256 <prgn>start-stop-daemon</prgn>.</p>
4259 If a service reloads its configuration automatically (as
4260 in the case of <prgn>cron</prgn>, for example), the
4261 <tt>reload</tt> option of the <tt>init.d</tt> script
4262 should behave as if the configuration has been reloaded
4266 These scripts should not fail obscurely when the
4267 configuration files remain but the package has been
4268 removed, as configuration files remain on the system after
4269 the package has been removed. Only when <prgn>dpkg</prgn>
4270 is executed with the <tt>--purge</tt> option will
4271 configuration files be removed. In particular, the init
4272 script itself is usually a configuration file (see
4273 <ref id="init.d notes">), and will remain on the system if
4274 the package is removed but not purged. Therefore, you
4275 should include a <tt>test</tt> statement at the top of the
4278 test -f <var>program-executed-later-in-script</var> || exit 0
4282 Often there are some values in the `<tt>init.d</tt>'
4283 scripts that a system administrator will frequently want
4284 to change. While the scripts are frequently conffiles,
4285 modifying them requires that the administrator merge in
4286 their changes each time the package is upgraded and the
4287 conffile changes. To ease the burden on the system
4288 administrator, such configurable values should not be
4289 placed directly in the script. Instead, they should be
4290 placed in a file in `<tt>/etc/default</tt>', which
4291 typically will have the same base name as the
4292 `<tt>init.d</tt>' script. This extra file can be sourced
4293 by the script when the script runs. It must contain only
4294 variable settings and comments.
4298 To ensure that vital configurable values are always
4299 available, the `<tt>init.d</tt>' script should set default
4300 values for each of the shell variables it uses before
4301 sourcing the <tt>/etc/default/</tt> file. Also, since the
4302 `<tt>/etc/default/</tt>' file is often a conffile, the
4303 `<tt>init.d</tt>' script must behave sensibly without
4304 failing if it is deleted.
4310 <heading>Managing the links</heading>
4313 The program <prgn>update-rc.d</prgn> is provided to make
4314 it easier for package maintainers to arrange for the
4315 proper creation and removal of
4316 <tt>/etc/rc<var>n</var>.d</tt> symbolic links, or their
4317 functional equivalent if another method is being used.
4318 This may be used by maintainers in their packages'
4319 <tt>postinst</tt> and <tt>postrm</tt> scripts.</p>
4322 You must use this script to make changes to
4323 <tt>/etc/rc<var>n</var>.d</tt> and <em>never</em> either
4324 include any <tt>/etc/rc<var>n</var>.d</tt> symbolic links
4325 in the actual archive or manually create or remove the
4326 symbolic links in maintainer scripts. (The latter will
4327 fail if an alternative method of maintaining runlevel
4328 information is being used.)</p>
4331 By default <prgn>update-rc.d</prgn> will start services in
4332 each of the multi-user state runlevels (2, 3, 4, and 5)
4333 and stop them in the halt runlevel (0), the single-user
4334 runlevel (1) and the reboot runlevel (6). The system
4335 administrator will have the opportunity to customize
4336 runlevels by either running <prgn>update-rc.d</prgn>, by
4337 simply adding, moving, or removing the symbolic links in
4338 <tt>/etc/rc<var>n</var>.d</tt> if symbolic links are being
4339 used, or by modifying <tt>/etc/runlevel.conf</tt> if the
4340 <tt>file-rc</tt> method is being used.</p>
4343 To get the default behavior for your package, put in your
4344 <tt>postinst</tt> script
4346 update-rc.d <var>package</var> defaults >/dev/null
4348 and in your <tt>postrm</tt>
4350 if [ purge = "$1" ]; then
4351 update-rc.d <var>package</var> remove >/dev/null
4356 This will use a default sequence number of 20. If it does
4357 not matter when or in which order the script is run, use
4358 this default. If it does, then you should talk to the
4359 maintainer of the <prgn>sysvinit</prgn> package or post to
4360 <tt>debian-devel</tt>, and they will help you choose a
4364 For more information about using <tt>update-rc.d</tt>,
4365 please consult its manpage <manref name="update-rc.d"
4366 section="8">.</p></sect1>
4370 <heading>Boot-time initialization</heading>
4373 There used to be another directory, <tt>/etc/rc.boot</tt>,
4374 which contained scripts which were run once per machine
4375 boot. This has been deprecated in favour of links from
4376 <tt>/etc/rcS.d</tt> to files in <tt>/etc/init.d</tt> as
4377 described in <ref id="/etc/init.d">. Packages must not
4378 place files in <tt>/etc/rc.boot</tt>.</p>
4380 <sect1 id="init.d notes">
4381 <heading>Notes</heading>
4384 <em>Do not</em> include the
4385 <tt>/etc/rc<var>n</var>.d/*</tt> symbolic links in the
4386 <tt>.deb</tt> file system archive! <em>This will cause
4387 problems!</em> You must create them with
4388 <prgn>update-rc.d</prgn>, as above.</p>
4391 <em>Do not</em> include the
4392 <tt>/etc/rc<var>n</var>.d/*</tt> symbolic links in
4393 <prgn>dpkg</prgn>'s conffiles list! <em>This will cause
4394 problems!</em> You should, however, treat the
4395 <tt>/etc/init.d</tt> scripts as configuration files,
4396 either by marking them as conffiles or managing them
4397 correctly in the maintainer scripts (see
4398 <ref id="config files">). (This is important since we want
4399 to give the local system administrator the chance to adapt
4400 the scripts to the local system--e.g., to disable a
4401 service without de-installing the package, or to specify
4402 some special command line options when starting a
4403 service--while making sure her changes aren't lost during
4404 the next package upgrade.)</p>
4408 <heading>Example</heading>
4411 The <prgn>bind</prgn> DNS (nameserver) package wants to
4412 make sure that the nameserver is running in multiuser
4413 runlevels, and is properly shut down with the system. It
4414 puts a script in <tt>/etc/init.d</tt>, naming the script
4415 appropriately <tt>bind</tt>. As you can see, the script
4416 interprets the argument <tt>reload</tt> to send the
4417 nameserver a <tt>HUP</tt> signal (causing it to reload its
4418 configuration); this way the user can say
4419 <tt>/etc/init.d/bind reload</tt> to reload the name
4420 server. The script has one configurable value, which can
4421 be used to pass parameters to the named program at
4429 # Original version by Robert Leslie
4430 # <rob@mars.org>, edited by iwj and cs
4432 test -x /usr/sbin/named || exit 0
4434 # Source defaults file.
4436 if [ -f /etc/default/bind ]; then
4443 echo -n "Starting domain name service: named"
4444 start-stop-daemon --start --quiet --exec /usr/sbin/named \
4449 echo -n "Stopping domain name service: named"
4450 start-stop-daemon --stop --quiet \
4451 --pidfile /var/run/named.pid --exec /usr/sbin/named
4455 echo -n "Restarting domain name service: named"
4456 start-stop-daemon --stop --quiet \
4457 --pidfile /var/run/named.pid --exec /usr/sbin/named
4458 start-stop-daemon --start --verbose --exec /usr/sbin/named \
4462 force-reload|reload)
4463 echo -n "Reloading configuration of domain name service: named"
4464 start-stop-daemon --stop --signal 1 --quiet \
4465 --pidfile /var/run/named.pid --exec /usr/sbin/named
4469 echo "Usage: /etc/init.d/bind {start|stop|restart|reload|force-reload}" >&2
4479 Complementing the above init script is a file
4480 '<tt>/etc/default/bind</tt>', which contains configurable
4481 parameters used by the script.
4485 # Specified parameters to pass to named. See named(8).
4486 # You may uncomment the following line, and edit to taste.
4492 Another example on which to base your <tt>/etc/init.d</tt>
4493 scripts is in <tt>/etc/init.d/skeleton</tt>.</p>
4496 If this package is happy with the default setup from
4497 <prgn>update-rc.d</prgn>, namely an ordering number of 20
4498 and having named running in all runlevels, it can say in
4499 its <tt>postinst</tt>:
4501 update-rc.d bind defaults >/dev/null
4503 And in its <tt>postrm</tt>, to remove the links when the
4506 if [ purge = "$1" ]; then
4507 update-rc.d bind remove >/dev/null
4513 <heading>Cron jobs</heading>
4516 Packages must not modify the configuration file
4517 <tt>/etc/crontab</tt>, and they must not modify the files in
4518 <tt>/var/spool/cron/crontabs</tt>.</p>
4521 If a package wants to install a job that has to be executed
4522 via cron, it should place a file with the name of the
4523 package in one of the following directories:
4529 As these directory names imply, the files within them are
4530 executed on a daily, weekly, or monthly basis,
4531 respectively. The exact times are listed in
4532 <tt>/etc/crontab</tt>.</p>
4535 All files installed in any of these directories must be
4536 scripts (shell scripts, Perl scripts, etc.) so that they can
4537 easily be modified by the local system administrator. In
4538 addition, they should be treated as configuration files.</p>
4541 If a certain job has to be executed more frequently than
4542 daily, the package should install a file
4543 <tt>/etc/cron.d/<var>package-name</var></tt>. This file uses
4544 the same syntax as <tt>/etc/crontab</tt> and is processed by
4545 <prgn>cron</prgn> automatically. The file must also be
4546 treated as a configuration file. (Note, that entries in the
4547 <tt>/etc/cron.d</tt> directory are not handled by
4548 <prgn>anacron</prgn>. Thus, you should only use this
4549 directory for jobs which may be skipped if the system is not
4553 The scripts or crontab entries in these directories should
4554 check if all necessary programs are installed before they
4555 try to execute them. Otherwise, problems will arise when a
4556 package was removed but not purged since configuration files
4557 are kept on the system in this situation.</p>
4561 <heading>Console messages</heading>
4564 This section describes different formats for messages
4565 written to standard output by the <tt>/etc/init.d</tt>
4566 scripts. The intent is to improve the consistency of
4567 Debian's startup and shutdown look and feel.</p>
4570 Please look very careful at the details. We want to get the
4571 messages to look exactly the same way concerning spaces,
4572 punctuation, and case of letters.</p>
4575 Here is a list of overall rules that you should use when you
4576 create output messages. They can be useful if you have a
4577 non-standard message that isn't covered in the sections
4584 Every message should cover one line, start with a
4585 capital letter and end with a period `.'.</p></item>
4590 If you want to express that the computer is working on
4591 something (performing a specific task, not starting or
4592 stopping a program), we use an ``ellipsis'', namely
4593 three dots `...'. Note that we don't insert spaces in
4594 front of or behind the dots. If the task has been
4595 completed we write `done.' and a line feed.</p></item>
4600 Design your messages as if the computer is telling you
4601 what he is doing (let him be polite :-) but don't
4602 mention ``him'' directly. For example, if you think
4605 I'm starting network daemons: nfsd mountd.
4609 Starting network daemons: nfsd mountd.
4610 </example></p></item>
4614 The following formats should be used</p>
4619 <p>when daemons get started.</p>
4622 Use this format if your script starts one or more
4623 daemons. The output should look like this (a single
4624 line, no leading spaces):
4626 Starting <description>: <daemon-1> <daemon-2> <...> <daemon-n>.
4628 The <description> should describe the subsystem
4629 the daemon or set of daemons are part of, while
4630 <daemon-1> up to <daemon-n> denote each
4631 daemon's name (typically the file name of the
4635 For example, the output of /etc/init.d/lpd would look like:
4637 Starting printer spooler: lpd.
4641 This can be achieved by saying
4643 echo -n "Starting printer spooler: lpd"
4644 start-stop-daemon --start --quiet lpd
4647 in the script. If you have more than one daemon to
4648 start, you should do the following:
4650 echo -n "Starting remote file system services:"
4651 echo -n " nfsd"; start-stop-daemon --start --quiet nfsd
4652 echo -n " mountd"; start-stop-daemon --start --quiet mountd
4653 echo -n " ugidd"; start-stop-daemon --start --quiet ugidd
4656 This makes it possible for the user to see what takes
4657 so long and when the final daemon has been
4658 started. You should be careful where to put spaces: In the
4659 example above the system administrator can easily
4660 comment out a line if he don't wants to start a
4661 specific daemon, while the displayed message still
4662 looks good.</p></item>
4666 <p>when something needs to be configured.</p>
4669 If you have to set up different parameters of the
4670 system upon boot up, you should use this format:
4672 Setting <parameter> to `<value>'.
4676 You can use the following echo statement to get the quotes right:
4678 echo "Setting DNS domainname to \`"value"'."
4682 Note that the left quotation mark (`) is different
4683 from the right (').</p></item>
4686 <p>when a daemon is stopped.</p>
4689 When you stop a daemon you should issue a message
4690 similar to the startup message, except that `Starting'
4691 is replaced with `Stopping'.</p>
4694 So stopping the printer daemon will like like this:
4696 Stopping printer spooler: lpd.
4697 </example></p></item>
4700 <p>when something is executed.</p>
4703 There are several examples where you have to run a
4704 program at system startup or shutdown to perform a
4705 specific task. For example, setting the system's clock
4706 via `netdate' or killing all processes when the system
4707 comes down. Your message should like this:
4709 Doing something very useful...done.
4711 You should print the `done.' right after the job has been completed,
4712 so that the user gets informed why he has to wait. You can get this
4715 echo -n "Doing something very useful..."
4719 in your script.</p></item>
4722 <p>when the configuration is reloaded.</p>
4725 When a daemon is forced to reload its configuration
4726 files you should use the following format:
4728 Reloading <daemon's-name> configuration...done.
4729 </example></p></item>
4732 <p>when none of the above rules apply.</p>
4735 If you have to print a message that doesn't fit into
4736 the styles described above, you can use something
4737 appropriate, but please have a look at the overall
4738 rules listed above.</p></item>
4743 <heading>Menus</heading>
4746 Menu entries should follow the current menu policy as
4747 defined in the file <ftpsite>ftp.debian.org</ftpsite> in
4748 <ftppath>/debian/doc/package-developer/menu-policy.txt.gz</ftppath>
4749 or your local mirror. In addition, it is included in the
4750 <tt>debian-policy</tt> package.
4754 The Debian <tt>menu</tt> packages provides a unique
4755 interface between packages providing applications and
4756 documents, and <em>menu programs</em> (either X window
4757 managers or text-based menu programs as
4758 <prgn>pdmenu</prgn>).</p>
4761 All packages that provide applications that need not be
4762 passed any special command line arguments for normal
4763 operation should register a menu entry for those
4764 applications, so that users of the <tt>menu</tt> package
4765 will automatically get menu entries in their window
4766 managers, as well in shells like <tt>pdmenu</tt>.</p>
4769 Please refer to the <em>Debian Menu System</em> document
4770 that comes with the <tt>menu</tt> package for information
4771 about how to register your applications and web
4777 <heading>Multimedia handlers</heading>
4780 Packages which provide the ability to view/show/play,
4781 compose, edit or print MIME types should register themselves
4782 as such following the current MIME support policy as defined
4783 in the file found on <ftpsite>ftp.debian.org</ftpsite> in
4784 <ftppath>/debian/doc/package-developer/mime-policy.txt.gz</ftppath>
4785 or your local mirror. In addition, it is included in the
4786 <tt>debian-policy</tt> package.
4790 MIME (Multipurpose Internet Mail Extensions, RFC 1521) is a
4791 mechanism for encoding files and data streams and providing
4792 meta-information about them, in particular their type (e.g.
4793 audio or video) and format (e.g. PNG, HTML, MP3).
4797 Registration of MIME type handlers allows programs like mail
4798 user agents and web browsers to to invoke these handlers to
4799 view, edit or display MIME types they don't support
4805 <heading>Keyboard configuration</heading>
4808 To achieve a consistent keyboard configuration (i.e., all
4809 applications interpret a keyboard event the same way) all
4810 programs in the Debian distribution must be configured to
4811 comply with the following guidelines.</p>
4814 Here is a list that contains certain keys and their interpretation:
4817 <tag><tt><--</tt></tag>
4818 <item><p>delete the character to the left of the cursor</p></item>
4820 <tag><tt>Delete</tt></tag>
4821 <item><p>delete the character to the right of the cursor</p></item>
4823 <tag><tt>Control+H</tt></tag>
4824 <item><p>emacs: the help prefix</p></item>
4827 The interpretation of any keyboard events should be independent
4828 of the terminal that's used, be it a virtual console, an X
4829 terminal emulator, an rlogin/telnet session, etc.</p>
4832 The following list explains how the different programs
4833 should be set up to achieve this:</p>
4836 <list compact="compact">
4837 <item><p>`<tt><--</tt>' generates KB_Backspace in
4840 <item><p>`<tt>Delete</tt>' generates KB_Delete in X.</p></item>
4844 X translations are set up to make KB_Backspace
4845 generate ASCII DEL, and to make KB_Delete generate
4846 <tt>ESC [ 3 ~</tt> (this is the vt220 escape code for
4847 the `delete character' key). This must be done by
4848 loading the resources using xrdb on all local X
4849 displays, not using the application defaults, so that
4850 the translation resources used correspond to the
4851 xmodmap settings.</p></item>
4855 The Linux console is configured to make
4856 `<tt><--</tt>' generate DEL, and `Delete' generate
4857 <tt>ESC [ 3 ~</tt> (this is the case at the
4861 X applications are configured so that Backspace
4862 deletes left, and Delete deletes right. Motif
4863 applications already work like this.</p></item>
4865 <item><p>stty erase <tt>^?</tt> .</p></item>
4868 The `xterm' terminfo entry should have <tt>ESC [ 3
4869 ~</tt> for kdch1, just like TERM=linux and
4870 TERM=vt220.</p></item>
4873 Emacs is programmed to map KB_Backspace or the `stty
4874 erase' character to delete-backward-char, and
4875 KB_Delete or kdch1 to delete-forward-char, and
4876 <tt>^H</tt> to help as always.</p></item>
4879 Other applications use the `stty erase' character and
4880 kdch1 for the two delete keys, with ASCII DEL being
4881 `delete previous character' and kdch1 being `delete
4882 character under cursor'.</p></item>
4886 This will solve the problem except for:</p>
4889 <list compact="compact">
4891 Some terminals have a <tt><--</tt> key that cannot
4892 be made to produce anything except <tt>^H</tt>. On
4893 these terminals Emacs help will be unavailable on
4894 <tt>^H</tt> (assuming that the `stty erase' character
4895 takes precedence in Emacs, and has been set
4896 correctly). M-x help or F1 (if available) can be used
4900 Some operating systems use <tt>^H</tt> for stty erase.
4901 However, modern telnet versions and all rlogin
4902 versions propagate stty settings, and almost all UNIX
4903 versions honour stty erase. Where the stty settings
4904 are not propagated correctly things can be made to
4905 work by using stty manually.</p></item>
4908 Some systems (including previous Debian versions) use
4909 xmodmap to arrange for both <tt><--</tt> and Delete
4910 to generate KB_Delete. We can change the behavior
4911 of their X clients via the same X resources that we
4912 use to do it for our own, or have our clients be
4913 configured via their resources when things are the
4914 other way around. On displays configured like this
4915 Delete will not work, but <tt><--</tt>
4919 Some operating systems have different kdch1 settings
4920 in their terminfo for xterm and others. On these
4921 systems the Delete key will not work correctly when
4922 you log in from a system conforming to our policy, but
4923 <tt><--</tt> will.</p></item>
4930 <heading>Environment variables</heading>
4933 A program must not depend on environment variables to get
4934 reasonable defaults. (That's because these environment
4935 variables would have to be set in a system-wide
4936 configuration file like /etc/profile, which is not supported
4940 If a program usually depends on environment variables for its
4941 configuration, the program should be changed to fall back to
4942 a reasonable default configuration if these environment
4943 variables are not present. If this cannot be done easily
4944 (e.g., if the source code of a non-free program is not
4945 available), the program must be replaced by a small
4946 `wrapper' shell script which sets the environment variables
4947 if they are not already defined, and calls the original program.</p>
4950 Here is an example of a wrapper script for this purpose:
4954 BAR=${BAR:-/var/lib/fubar}
4956 exec /usr/lib/foo/foo "$@"
4960 Furthermore, as <tt>/etc/profile</tt> is a configuration
4961 file of the <prgn>base-files</prgn> package, other packages must not
4962 put any environment variables or other commands into that
4967 <heading>Files</heading>
4971 <heading>Binaries</heading>
4974 Two different packages must not install programs with
4975 different functionality but with the same filenames. (The
4976 case of two programs having the same functionality but
4977 different implementations is handled via `alternatives.')
4978 If this case happens, one of the programs must be
4979 renamed. The maintainers should report this to the
4980 developers' mailing and try to find a consensus about
4981 which package will have to be renamed. If a consensus can
4982 not be reached, <em>both</em> programs must be
4986 Generally the following compilation parameters should be used:
4989 CFLAGS = -O2 -Wall # sane warning options vary between programs
4991 install -s # (or use strip on the files in debian/tmp)
4995 Note that by default all installed binaries should be stripped,
4996 either by using the <tt>-s</tt> flag to
4997 <prgn>install</prgn>, or by calling <prgn>strip</prgn> on
4998 the binaries after they have been copied into
4999 <tt>debian/tmp</tt> but before the tree is made into a
5003 The <tt>-N</tt> flag should not be used. On a.out systems
5004 it may have been useful for some very small binaries, but
5005 for ELF it has no good effect.</p>
5008 Debugging symbols are useful for error diagnosis,
5009 investigation of core dumps (which may be submitted by users
5010 in bug reports), or testing and developing the
5011 software. Therefore it is recommended to support building
5012 the package with debugging information through the following
5013 interface: If the environment variable
5014 <tt>DEB_BUILD_OPTIONS</tt> contains the string
5015 <tt>debug</tt>, compile the software with debugging
5016 information (usually this involves adding the <tt>-g</tt>
5017 flag to <tt>CFLAGS</tt>). This allows the generation of a
5018 build tree with debugging information. If the environment
5019 variable <tt>DEB_BUILD_OPTIONS</tt> contains the string
5020 <tt>nostrip</tt>, do not strip the files at installation
5021 time. This allows one to generate a package with debugging
5022 information included. The following makefile snippet is only
5023 an example of how one may test for either condition:
5026 Rationale: Building by default with -g causes more
5027 wasted CPU cycles since the information is stripped away
5028 anyway. The package can by default build without -g if
5029 it also provides a mechanism to easily be rebuilt with
5030 debugging information. This can be done by providing a
5031 "build-debug" make target, or allowing the user to
5032 specify "DEB_BUILD_OPTIONS=debug" in the environment while
5033 compiling that package.
5035 <p>Now this has several added benefits:
5039 It is actually easier to build debugging bins and
5040 libraries this way (no more editing debian/rules
5041 or similar) since it provides a documented way of
5042 getting this type of build.</p>
5046 There will be much less wasted CPU time for the
5047 autobuilders since not having debugging
5048 information (and hence also not having to strip
5049 it) will increase the speed of compiles. This
5050 skips an entire pass of the compiler.
5061 INSTALL_FILE = $(INSTALL) -p -o root -g root -m 644
5062 INSTALL_PROGRAM = $(INSTALL) -p -o root -g root -m 755
5063 INSTALL_SCRIPT = $(INSTALL) -p -o root -g root -m 755
5064 INSTALL_DIR = $(INSTALL) -p -d -o root -g root -m 755
5066 ifneq (,$(findstring debug,$(DEB_BUILD_OPTIONS)))
5069 ifeq (,$(findstring nostrip,$(DEB_BUILD_OPTIONS)))
5070 INSTALL_PROGRAM += -s
5074 Please note that the above example is merely informative,
5075 and is not a policy mandate. You may have to massage this
5076 example in order to make it work for your package.
5081 It is up to the package maintainer to decide what
5082 compilation options are best for the package. Certain
5083 binaries (such as computationally-intensive programs) will
5084 function better with certain flags (<tt>-O3</tt>, for
5085 example); feel free to use them. Please use good judgment
5086 here. Don't use flags for the sake of it; only use them
5087 if there is good reason to do so. Feel free to override
5088 the upstream author's ideas about which compilation
5089 options are best--they are often inappropriate for our
5090 environment.</p></sect>
5094 <heading>Libraries</heading>
5097 All libraries must have a shared version in the lib
5098 package and a static version in the lib-dev package. The
5099 shared version must be compiled with <tt>-fPIC</tt>, and
5100 the static version must not be. In other words, each
5101 <tt>*.c</tt> file will need to be compiled twice.</p>
5104 You must specify the gcc option <tt>-D_REENTRANT</tt>
5105 when building a library (either static or shared) to make
5106 the library compatible with LinuxThreads.</p>
5109 Note that all installed shared libraries should be
5112 strip --strip-unneeded <your-lib>
5114 (The option `--strip-unneeded' makes <tt>strip</tt> remove
5115 only the symbols which aren't needed for relocation
5116 processing.) Shared libraries can function perfectly well
5117 when stripped, since the symbols for dynamic linking are
5118 in a separate part of the ELF object file.</p>
5121 Note that under some circumstances it may be useful to
5122 install a shared library unstripped, for example when
5123 building a separate package to support debugging.
5127 An ever increasing number of packages are using libtool to
5128 do their linking. The latest GNU libtools (>= 1.3a) can take
5129 advantage of the metadata in the installed libtool archive
5130 files (`*.la'). The main advantage of libtool's .la files is
5131 that it allows libtool to store and subsequently access
5132 metadata with respect to the libraries it builds. libtool
5133 will search for those files, which contain a lot of useful
5134 information about a library (e.g. dependency libraries for
5135 static linking). Also, they're <em>essential</em> for
5136 programs using libltdl.
5140 Certainly libtool is fully capable of linking against shared
5141 libraries which don't have .la files, but being a mere shell
5142 script it can add considerably to the build time of a
5143 libtool using package if that shell-script has to derive all
5144 this information from first principles for each library every
5145 time it is linked. With the advent of libtool-1.4 (and to a
5146 lesser extent libtool-1.3), the .la files will also store
5147 information about inter-library dependencies which cannot
5148 necessarily be derived after the .la file is deleted.
5152 Packages that use libtool to create shared libraries should
5153 include the <em>.la</em> files in the <em>-dev</em>
5154 packages, with the exception that if the package relies on
5155 libtool's <em>libltdl</em> library, in which case the .la
5156 files must go in the run-time library package. This is a
5157 good idea in general, and especially for static linking
5162 You must make sure that you use only released versions of
5163 shared libraries to build your packages; otherwise other
5164 users will not be able to run your binaries
5165 properly. Producing source packages that depend on
5166 unreleased compilers is also usually a bad
5173 <heading>Shared libraries</heading>
5176 Packages involving shared libraries should be split up
5177 into several binary packages.</p>
5180 For a straightforward library which has a development
5181 environment and a runtime kit including just shared
5182 libraries you need to create two packages:
5183 <tt><var>libraryname</var><var>soname</var></tt>
5184 (<var>soname</var> is the shared object name of the shared
5185 library--it's the thing that has to match exactly between
5186 building an executable and running it for the dynamic
5187 linker to be able run the program; usually the
5188 <var>soname</var> is the major number of the library) and
5189 <tt><var>libraryname</var><var>soname</var>-dev</tt>.</p>
5192 If you prefer only to support one development version at a
5193 time you may name the development package
5194 <tt><var>libraryname</var>-dev</tt>; otherwise you may
5195 wish to use <prgn>dpkg</prgn>'s conflicts mechanism to
5196 ensure that the user only installs one development version
5197 at a time (after all, different development versions are
5198 likely to have the same header files in them, causing a
5199 filename clash if both are installed). Typically the
5200 development version should also have an exact version
5201 dependency on the runtime library, to make sure that
5202 compilation and linking happens correctly.</p>
5205 Packages which use the shared library should have a
5206 dependency on the name of the shared library package,
5207 <tt><var>libraryname</var><var>soname</var></tt>. When
5208 the <var>soname</var> changes you can have both versions
5209 of the library installed while moving from the old library
5213 If your package has some run-time support programs which
5214 use the shared library you must not put them in
5215 the shared library package. If you do that then you won't
5216 be able to install several versions of the shared library
5217 without getting filename clashes. Instead, either create
5218 a third package for the runtime binaries (this package
5219 might typically be named
5220 <tt><var>libraryname</var>-runtime</tt>--note the absence
5221 of the <var>soname</var> in the package name) or if the
5222 development package is small include them in there.</p>
5225 If you have several shared libraries built from the same
5226 source tree you may lump them all together into a single
5227 shared library package, provided that you change all their
5228 <var>soname</var>s at once (so that you don't get filename
5229 clashes if you try to install different versions of the
5230 combined shared libraries package).</p>
5233 You should follow the directions in the <em>Debian Packaging
5234 Manual</em> for putting the shared library in its package,
5235 and you must include a <tt>shlibs</tt> control area
5236 file with details of the dependencies for packages which
5237 use the library.</p>
5240 Shared libraries should not be installed
5241 executable, since <prgn>ld.so</prgn> does not require this
5242 and trying to execute a shared library results in a core
5247 <heading>Scripts</heading>
5250 All command scripts, including the package maintainer
5251 scripts inside the package and used by <prgn>dpkg</prgn>,
5252 should have a <tt>#!</tt> line naming the shell to be used
5253 to interpret them.</p>
5256 In the case of Perl scripts this should be
5257 <tt>#!/usr/bin/perl</tt>.</p>
5260 Shell scripts (<prgn>sh</prgn> and <prgn>bash</prgn>)
5261 should almost certainly start with <tt>set -e</tt> so that
5262 errors are detected. Every script should use
5263 <tt>set -e</tt> or check the exit status of <em>every</em>
5267 The standard shell interpreter `<tt>/bin/sh</tt>' can be a
5268 symbolic link to any POSIX compatible shell, if <tt>echo
5269 -n</tt> does not generate a newline.
5272 Debian policy specifies POSIX behavior for /bin/sh, but
5273 echo -n has widespread use in the Linux community
5274 (including especially debian policy, the linux kernel
5275 source, many debian scripts, etc.). This echo -n
5276 mechanism is valid but not required under POSIX, hence
5277 this explicit addition. Also, rumour has it that this
5278 shall be mandated under the LSB anyway.
5282 specifying `<tt>/bin/sh</tt>' as interpreter should only
5283 use POSIX features. If a script requires non-POSIX
5284 features from the shell interpreter, the appropriate shell
5285 must be specified in the first line of the script (e.g.,
5286 `<tt>#!/bin/bash</tt>') and the package must depend on the
5287 package providing the shell (unless the shell package is
5288 marked `Essential', e.g., in the case of
5293 You may wish to restrict your script to POSIX features when possible so
5294 that it may use <tt>/bin/sh</tt> as its interpreter. If
5295 your script works with <prgn>ash</prgn>, it's probably
5296 POSIX compliant, but if you are in doubt, use
5297 <tt>/bin/bash</tt>.</p>
5300 Perl scripts should check for errors when making any
5301 system calls, including <tt>open</tt>, <tt>print</tt>,
5302 <tt>close</tt>, <tt>rename</tt> and <tt>system</tt>.</p>
5305 <prgn>csh</prgn> and <prgn>tcsh</prgn> should be avoided
5306 as scripting languages. See <em>Csh Programming
5307 Considered Harmful</em>, one of the <tt>comp.unix.*</tt>
5308 FAQs. It can be found on
5309 <url id="http://language.perl.com/versus/csh.whynot">, or
5310 <url id="http://www.cpan.org/doc/FMTEYEWTK/versus/csh.whynot">
5311 or even on <ftpsite>ftp.cpan.org</ftpsite>
5312 <ftppath>/pub/perl/CPAN/doc/FMTEYEWTK/versus/csh.whynot</ftppath>.
5313 If an upstream package comes with <prgn>csh</prgn> scripts
5314 then you must make sure that they start with
5315 <tt>#!/bin/csh</tt> and make your package depend on the
5316 <prgn>c-shell</prgn> virtual package.</p>
5319 Any scripts which create files in world-writeable
5320 directories (e.g., in <tt>/tmp</tt>) must use a
5321 mechanism which will fail if a file with the same name
5325 The Debian base distribution provides the
5326 <prgn>tempfile</prgn> and <prgn>mktemp</prgn> utilities
5327 for use by scripts for this purpose.</p></sect>
5331 <heading>Symbolic links</heading>
5334 In general, symbolic links within a top-level directory
5335 should be relative, and symbolic links pointing from one
5336 top-level directory into another should be absolute. (A
5337 top-level directory is a sub-directory of the root
5341 In addition, symbolic links should be specified as short
5342 as possible, i.e., link targets like `foo/../bar' are
5346 Note that when creating a relative link using
5347 <prgn>ln</prgn> it is not necessary for the target of the
5348 link to exist relative to the working directory you're
5349 running <prgn>ln</prgn> from; nor is it necessary to
5350 change directory to the directory where the link is to be
5351 made. Simply include the string that should appear as the
5352 target of the link (this will be a pathname relative to
5353 the directory in which the link resides) as the first
5354 argument to <prgn>ln</prgn>.</p>
5357 For example, in your <prgn>Makefile</prgn> or
5358 <tt>debian/rules</tt>, do things like:
5360 ln -fs gcc $(prefix)/bin/cc
5361 ln -fs gcc debian/tmp/usr/bin/cc
5362 ln -fs ../sbin/sendmail $(prefix)/bin/runq
5363 ln -fs ../sbin/sendmail debian/tmp/usr/bin/runq
5367 A symbolic link pointing to a compressed file should
5368 always have the same file extension as the referenced
5369 file. (For example, if a file `<tt>foo.gz</tt>' is
5370 referenced by a symbolic link, the filename of the link
5371 has to end with `<tt>.gz</tt>' too, as in
5372 `bar.gz.')</p></sect>
5376 <heading>Device files</heading>
5379 Packages must not include device files in the package file
5383 If a package needs any special device files that are not
5384 included in the base system, it must call
5385 <prgn>MAKEDEV</prgn> in the <tt>postinst</tt> script,
5386 after asking the user for permission to do so.</p>
5389 Packages must not remove any device files in the
5390 <tt>postrm</tt> or any other script. This is left to the
5391 system administrator.</p>
5394 Debian uses the serial devices
5395 <tt>/dev/ttyS*</tt>. Programs using the old
5396 <tt>/dev/cu*</tt> devices should be changed to use
5397 <tt>/dev/ttyS*</tt>.</p>
5400 <sect id="config files">
5401 <heading>Configuration files</heading>
5403 <heading>Definitions</heading>
5406 <tag>configuration file</tag>
5408 A file that affects the operation of program, or
5409 provides site- or host-specific information, or
5410 otherwise customizes the behavior of program.
5411 Typically, configuration files are intended to be
5412 modified by the system administrator (if needed or
5413 desired) to conform to local policy or provide more
5414 useful site-specific behavior.</p>
5417 <tag><tt>conffile</tt></tag>
5419 A file listed in a package's <tt>conffiles</tt>
5420 file, and is treated specially by <prgn>dpkg</prgn>
5421 (see the <em>Debian Packaging Manual</em>).</p>
5427 The distinction between these two is important; they are
5428 not interchangeable concepts. Almost all
5429 <tt>conffiles</tt> are configuration files, but many
5430 configuration files are not <tt>conffiles</tt>.</p>
5433 Note that a script that embeds configuration information
5434 (such as most of the files in <tt>/etc/init.d</tt> and
5435 <tt>/etc/cron.{daily,weekly,monthly}</tt>) is de-facto a
5436 configuration file and should be treated as such.</p>
5440 <heading>Location</heading>
5442 Any configuration files created or used by your package
5443 must reside in <tt>/etc</tt>. If there are several you
5444 should consider creating a subdirectory of <tt>/etc</tt>
5445 named after your package.</p>
5448 If your package creates or uses configuration files
5449 outside of <tt>/etc</tt>, and it is not feasible to modify
5450 the package to use the <tt>/etc</tt>, you should still put
5451 the files in <tt>/etc</tt> and create symbolic links to
5452 those files from the location that the package
5457 <heading>Behavior</heading>
5459 Configuration file handling must conform to the following
5463 <p>local changes must be preserved during a package
5467 <p>configuration files must be preserved when the
5468 package is removed, and only deleted when the
5469 package is purged.</p>
5474 The easy way to achieve this behavior is to make the
5475 configuration file a <tt>conffile</tt>. This is
5476 appropriate only if it is possible to distribute a default
5477 version that will work for most installations, although
5478 some system administrators may choose to modify it. This
5479 implies that the default version will be part of the
5480 package distribution, and must not be modified by the
5481 maintainer scripts during installation (or at any other
5486 In order to ensure that local changes are preserved
5487 correctly, no package may contain or make hard links to
5491 Rationale: There are two problems with hard links.
5492 The first is that some editors break the link while
5493 editing one of the files, so that the two files may
5494 unwittingly become different. The second is that
5495 <prgn>dpkg</prgn> might break the hard link while
5496 upgrading <tt>conffile</tt>s.
5501 The other way to do it is via the maintainer scripts.
5502 In this case, the configuration file must not be listed as
5503 a <tt>conffile</tt> and must not be part of the package
5504 distribution. If the existence of a file is required for
5505 the package to be sensibly configured it is the
5506 responsibility of the package maintainer to write scripts
5507 which correctly create, update, maintain and
5508 remove-on-purge the file. These scripts must be idempotent
5509 (i.e., must work correctly if <prgn>dpkg</prgn> needs to
5510 re-run them due to errors during installation or removal),
5511 must cope with all the variety of ways <prgn>dpkg</prgn>
5512 can call maintainer scripts, must not overwrite or
5513 otherwise mangle the user's configuration without asking,
5514 must not ask unnecessary questions (particularly during
5515 upgrades), and otherwise be good citizens.</p>
5518 The scripts are not required to configure every possible option for
5519 the package, but only those necessary to get the package
5520 running on a given system. Ideally the sysadmin should not
5521 have to do any configuration other than that done
5522 (semi-)automatically by the <tt>postinst</tt> script.</p>
5525 A common practice is to create a script called
5526 <tt><var>package</var>-configure</tt> and have the
5527 package's <tt>postinst</tt> call it if and only if the
5528 configuration file does not already exist. In certain
5529 cases it is useful for there to be an example or template
5530 file which the maintainer scripts use. Such files should
5531 be in <tt>/usr/share/doc</tt> if they are examples or
5532 <tt>/usr/lib</tt> if they are templates, and should be
5533 perfectly ordinary <prgn>dpkg</prgn>-handled files
5534 (<em>not</em> <tt>conffiles</tt>).</p>
5537 These two styles of configuration file handling must
5538 not be mixed, for that way lies madness:
5539 <prgn>dpkg</prgn> will ask about overwriting the file
5540 every time the package is upgraded.</p>
5545 <heading>Sharing configuration files</heading>
5547 Packages which specify the same file as
5548 `<tt>conffile</tt>' must be tagged as <em>conflicting</em>
5553 The maintainer scripts must not alter the conffile of
5554 <em>any</em> package, including the one the scripts belong
5558 If two or more packages use the same configuration file
5559 and it is reasonable for both to be installed at the same
5560 time, one of these packages must be defined as
5561 <em>owner</em> of the configuration file, i.e., it will be
5562 the package to list that distributes the file and lists it
5563 as a <tt>conffile</tt>. Other packages that use the
5564 configuration file must depend on the owning package if
5565 they require the configuration file to operate. If the
5566 other package will use the configuration file if present,
5567 but is capable of operating without it, no dependency need
5571 If it is desirable for two or more related packages to
5572 share a configuration file <em>and</em> for all of the
5573 related packages to be able to modify that configuration
5574 file, then the following should be done:
5578 have one of the related packages (the "core"
5579 package) manage the configuration file with
5580 maintainer scripts as described in the previous
5584 the core package should also provide a program that
5585 the other packages may use to modify the
5586 configuration file.</p>
5590 the related packages must use the provided program
5591 to make any modifications to the configuration file.
5592 They should either depend on the core package to
5593 guarantee that the configuration modifier program is
5594 available or accept gracefully that they cannot
5595 modify the configuration file if it is not.</p>
5600 Sometimes it's appropriate to create a new package which
5601 provides the basic infrastructure for the other packages
5602 and which manages the shared configuration files. (Check
5603 out the <tt>sgml-base</tt> package as an example.)</p>
5607 <heading>User configuration files ("dotfiles")</heading>
5610 Files in <tt>/etc/skel</tt> will automatically be copied
5611 into new user accounts by <prgn>adduser</prgn>. They
5612 should not be referenced there by any program.</p>
5615 Therefore, if a program needs a dotfile to exist in
5616 advance in <tt>$HOME</tt> to work sensibly, that dotfile
5617 should be installed in <tt>/etc/skel</tt> (and listed in
5618 conffiles, if it is not generated and modified dynamically
5619 by the package's installation scripts).</p>
5622 However, programs that require dotfiles in order to
5623 operate sensibly (dotfiles that they do not create
5624 themselves automatically, that is) are a bad thing, and
5625 programs should be configured by the Debian default
5626 installation as close to normal as possible.</p>
5629 Therefore, if a program in a Debian package needs to be
5630 configured in some way in order to operate sensibly that
5631 configuration should be done in a site-wide global
5632 configuration file elsewhere in <tt>/etc</tt>. Only if the
5633 program doesn't support a site-wide default configuration
5634 and the package maintainer doesn't have time to add it
5635 may a default per-user file be placed in
5636 <tt>/etc/skel</tt>.</p>
5639 <tt>/etc/skel</tt> should be as empty as we can make it.
5640 This is particularly true because there is no easy
5641 mechanism for ensuring that the appropriate dotfiles are
5642 copied into the accounts of existing users when a package
5648 <heading>Log files</heading>
5650 The traditional approach to log files has been to set up ad
5651 hoc log rotation schemes using simple shell scripts and
5652 cron. While this approach is highly customizable, it
5653 requires quite a lot of sysadmin work. Even though the
5654 original Debian system helped a little by automatically
5655 installing a system which can be used as a template, this
5656 was deemed not enough.
5660 A better scheme is to use logrotate, a GPL'd program
5661 developed by Red Hat, which centralizes log management. It
5662 has both a configuration file (<tt>/etc/logrotate.conf</tt>)
5663 and a directory where packages can drop logrotation info
5664 (<tt>/etc/logrotate.d</tt>).
5668 Log files should usually be named
5669 <tt>/var/log/<var>package</var>.log</tt>. If you have many
5670 log files, or need a separate directory for permissions
5671 reasons (<tt>/var/log</tt> is writable only by
5672 <tt>root</tt>), you should usually create a directory named
5673 <tt>/var/log/<var>package</var></tt>.</p>
5676 Log files must be rotated occasionally so
5677 that they don't grow indefinitely; the best way to do this
5678 is to drop a script into the directory
5679 <tt>/etc/logrotate.d</tt> and use the facilities provided by
5680 logrotate. Here is a good example for a logrotate config
5681 file (for more information see <manref name="logrotate"
5689 /etc/init.d/foo force-reload
5693 Which rotates all files under `/var/log/foo', saves 12
5694 compressed generations, and sends a HUP signal at the end of
5700 Log files should be removed when the package is
5701 purged (but not when it is only removed), by checking the
5702 argument to the <tt>postrm</tt> script (see the <em>Debian
5703 Packaging Manual</em> for details).</p>
5708 <heading>Permissions and owners</heading>
5711 The rules in this section are guidelines for general use.
5712 If necessary you may deviate from the details below.
5713 However, if you do so you must make sure that what is done
5714 is secure and you should try to be as consistent as possible
5715 with the rest of the system. You should probably also
5716 discuss it on <prgn>debian-devel</prgn> first.</p>
5719 Files should be owned by <tt>root.root</tt>, and made
5720 writable only by the owner and universally readable (and
5721 executable, if appropriate).</p>
5724 Directories should be mode 755 or (for group-writability)
5725 mode 2775. The ownership of the directory should be
5726 consistent with its mode--if a directory is mode 2775, it
5727 should be owned by the group that needs write access to
5731 Setuid and setgid executables should be mode 4755 or 2755
5732 respectively, and owned by the appropriate user or group.
5733 They should not be made unreadable (modes like 4711 or
5734 2711 or even 4111); doing so achieves no extra security,
5735 because anyone can find the binary in the freely available
5736 Debian package--it is merely inconvenient. For the same
5737 reason you should not restrict read or execute permissions
5738 on non-set-id executables.</p>
5741 Some setuid programs need to be restricted to particular
5742 sets of users, using file permissions. In this case they
5743 should be owned by the uid to which they are set-id, and
5744 by the group which should be allowed to execute them.
5745 They should have mode 4754; there is no point in making
5746 them unreadable to those users who must not be allowed to
5750 You must not arrange that the system administrator can only
5751 reconfigure the package to correspond to their local
5752 security policy by changing the permissions on a binary.
5753 Ordinary files installed by <prgn>dpkg</prgn> (as opposed
5754 to conffiles and other similar objects) have their
5755 permissions reset to the distributed permissions when the
5756 package is reinstalled. Instead you should consider (for
5757 example) creating a group for people allowed to use the
5758 program(s) and making any setuid executables executable
5759 only by that group.</p>
5762 If you need to create a new user or group for your package
5763 there are two possibilities. Firstly, you may need to
5764 make some files in the binary package be owned by this
5765 user or group, or you may need to compile the user or
5766 group id (rather than just the name) into the binary
5767 (though this latter should be avoided if possible, as in
5768 this case you need a statically allocated id).</p>
5771 If you need a statically allocated id, you must ask for a
5772 user or group id from the base system
5773 maintainer, and must not release the package until you
5774 have been allocated one. Once you have been allocated one
5775 you must make the package depend on a version of the base
5776 system with the id present in <tt>/etc/passwd</tt> or
5777 <tt>/etc/group</tt>, or alternatively arrange for your
5778 package to create the user or group itself with the
5779 correct id (using <tt>adduser</tt>) in its pre- or
5780 post-installation script (the latter is to be preferred if
5781 it is possible).</p>
5784 On the other hand, the program might be able to determine the
5785 uid or gid from the group name at runtime, so that a
5786 dynamic id can be used. In this case you should choose an
5787 appropriate user or group name, discussing this on
5788 <prgn>debian-devel</prgn> and checking with the base
5789 system maintainer that it is unique and that they do not
5790 wish you to use a statically allocated id instead. When
5791 this has been checked you must arrange for your package to
5792 create the user or group if necessary using
5793 <prgn>adduser</prgn> in the pre- or post-installation
5794 script (again, the latter is to be preferred if it is
5798 Note that changing the numeric value of an id associated with a name
5799 is very difficult, and involves searching the file system for all
5800 appropriate files. You need to think carefully whether a static or
5801 dynamic id is required, since changing your mind later will cause
5807 <heading>Customized programs</heading>
5809 <sect id="arch-spec">
5810 <heading>Architecture specification strings</heading>
5813 If a program needs to specify an <em>architecture specification
5814 string</em> in some place, the following format should be used:
5816 <arch>-<os>
5818 where `<arch>' is one of the following: i386, alpha, arm, m68k,
5819 powerpc, sparc and `<os>' is one of: linux, gnu. Use
5820 of <em>gnu</em> in this string is reserved for the GNU/Hurd
5821 operating system.</p>
5823 Note, that we don't want to use `<arch>-debian-linux'
5824 to apply to the rule `architecture-vendor-os' since this
5825 would make our programs incompatible to other Linux
5826 distributions. Also note, that we don't use
5827 `<arch>-unknown-linux', since the `unknown' does not
5828 look very good.</p></sect>
5832 <heading>Daemons</heading>
5835 The configuration files <tt>/etc/services</tt>,
5836 <tt>/etc/protocols</tt>, and <tt>/etc/rpc</tt> are managed
5837 by the <prgn>netbase</prgn> package and may not be modified
5838 by other packages.</p>
5841 If a package requires a new entry in one of these files, the
5842 maintainer should get in contact with the
5843 <prgn>netbase</prgn> maintainer, who will add the entries
5844 and release a new version of the <prgn>netbase</prgn>
5848 The configuration file <tt>/etc/inetd.conf</tt> must not be
5849 modified by the package's scripts except via the
5850 <prgn>update-inetd</prgn> script or the
5851 <prgn>DebianNet.pm</prgn> Perl module.</p>
5854 If a package wants to install an example entry into
5855 <tt>/etc/inetd.conf</tt>, the entry must be preceded with
5856 exactly one hash character (<tt>#</tt>). Such lines are
5857 treated as `commented out by user' by the
5858 <prgn>update-inetd</prgn> script and are not changed or
5859 activated during a package updates.</p></sect>
5863 <heading>Using pseudo-ttys and modifying wtmp, utmp and lastlog</heading>
5866 Some programs need to create pseudo-ttys. This should be done
5867 using Unix98 ptys if the C library supports it. The resulting
5868 program must not be installed setuid root, unless that
5869 is required for other functionality.
5873 The files <tt>/var/run/utmp</tt>, <tt>/var/log/wtmp</tt> and
5874 <tt>/var/log/lastlog</tt> must be installed writeable by
5875 group utmp. Programs who need to modify those files must
5876 be installed setgid utmp.
5881 <heading>Editors and pagers</heading>
5884 Some programs have the ability to launch an editor or pager
5885 program to edit or display a text document. Since there are
5886 lots of different editors and pagers available in the Debian
5887 distribution, the system administrator and each user should
5888 have the possibility to choose his/her preferred editor and
5892 In addition, every program should choose a good default
5893 editor/pager if none is selected by the user or system
5897 Thus, every program that launches an editor or pager must
5898 use the EDITOR or PAGER environment variables to determine
5899 the editor/pager the user wants to get started. If these
5900 variables are not set, the programs <tt>/usr/bin/editor</tt>
5901 and <tt>/usr/bin/pager</tt> should be used, respectively.</p>
5904 These two files are managed through `alternatives.' That is,
5905 every package providing an editor or pager must call the
5906 <prgn>update-alternatives</prgn> script to register these
5910 If it is very hard to adapt a program to make us of the
5911 EDITOR and PAGER variables, that program may be configured
5912 to use <tt>/usr/bin/sensible-editor</tt> and
5913 <tt>/usr/bin/sensible-pager</tt> as editor or pager program,
5914 respectively. These are two scripts provided in the Debian
5915 base system that check the EDITOR and PAGER variables and
5916 launch the appropriate program or fall back to
5917 <tt>/usr/bin/editor</tt> and <tt>/usr/bin/pager</tt>,
5921 A program may also use the VISUAL environment variable to
5922 determine the user's choice of editor. If it exists, it
5923 should take precedence over EDITOR. This is in fact what
5924 <tt>/usr/bin/sensible-editor</tt> does.</p>
5927 It is not required for a package to depend on
5928 `editor' and `pager', nor is it required for a package to
5929 provide such virtual packages.
5932 The Debian base system already provides an editor and
5941 <sect id="web-appl">
5942 <heading>Web servers and applications</heading>
5945 This section describes the locations and URLs that should
5946 be used by all web servers and web application in the Debian
5952 <p>Cgi-bin executable files are installed in the
5955 /usr/lib/cgi-bin/<cgi-bin-name>
5957 and should be referred to as
5959 http://localhost/cgi-bin/<cgi-bin-name>
5960 </example></p></item>
5963 <item><p>Access to html documents</p>
5966 Html documents for a package are stored in
5967 <tt>/usr/share/doc/<var>package</var></tt> but should
5968 be accessed via symlinks as
5969 <tt>/usr/doc/<var>package</var></tt><footnote> for
5970 backward compatibility, see <ref id="usrdoc"></footnote>
5971 and can be referred to as
5973 http://localhost/doc/<package>/<filename>
5974 </example></p></item>
5977 <item><p>Web Document Root</p>
5980 Web Applications should try to avoid storing files in
5981 the Web Document Root. Instead they should use the
5982 /usr/share/doc/<package> directory for documents and
5983 register the Web Application via the menu package. If
5984 access to the web-root is unavoidable then use
5988 as the Document Root. This might be just a
5989 symbolic link to the location where the sysadmin has
5990 put the real document root.</p>
5993 </enumlist></p></sect>
5997 <heading>Mail transport, delivery and user agents</heading>
6000 Debian packages which process electronic mail, whether
6001 mail-user-agents (MUAs) or mail-transport-agents (MTAs),
6002 must make sure that they are compatible with the
6003 configuration decisions below. Failure to do this may
6004 result in lost mail, broken <tt>From:</tt> lines, and other
6005 serious brain damage!</p>
6008 The mail spool is <tt>/var/spool/mail</tt> and the interface
6009 to send a mail message is <tt>/usr/sbin/sendmail</tt> (as
6010 per the FHS). The mail spool is part of the base system
6011 and not part of the MTA package.</p>
6014 All Debian MUAs, MTAs, MDAs and other mailbox accessing
6015 programs (like IMAP daemons) must lock the mailbox in an
6016 NFS-safe way. This means that <tt>fcntl()</tt> locking must
6017 be combined with dot locking. To avoid deadlocks, a
6018 program should use <tt>fcntl()</tt> first and dot locking
6019 after this or alternatively implement the two locking
6020 methods in a non blocking way<footnote>
6022 If it is not possible to establish both locks, the
6023 system shouldn't wait for the second lock to be
6024 established, but remove the first lock, wait a (random)
6025 time, and start over locking again.</p>
6026 </footnote>. Using the functions <tt>maillock</tt> and
6027 <tt>mailunlock</tt> provided by the
6028 <tt>liblockfile*</tt><footnote>
6030 <tt>liblockfile</tt> version >>1.01</p>
6031 </footnote> packages is the recommended way to realize this.
6035 Mailboxes are generally 660 <tt><var>user</var>.mail</tt>
6036 unless the user has chosen otherwise. A MUA may remove a
6037 mailbox (unless it has nonstandard permissions) in which
6038 case the MTA or another MUA must recreate it if needed.
6039 Mailboxes must be writable by group mail.</p>
6042 The mail spool is 2775 <tt>root.mail</tt>, and MUAs should
6043 be setgid mail to do the locking mentioned above (and
6044 must obviously avoid accessing other users' mailboxes
6045 using this privilege).</p>
6048 <tt>/etc/aliases</tt> is the source file for the system mail
6049 aliases (e.g., postmaster, usenet, etc.)--it is the one
6050 which the sysadmin and <tt>postinst</tt> scripts may edit.
6051 After <tt>/etc/aliases</tt> is edited the program or human
6052 editing it must call <prgn>newaliases</prgn>. All MTA
6053 packages must come with a <prgn>newaliases</prgn> program,
6054 even if it does nothing, but older MTA packages do not do
6055 this so programs should not fail if <prgn>newaliases</prgn>
6056 cannot be found.</p>
6059 The convention of writing <tt>forward to
6060 <var>address</var></tt> in the mailbox itself is not
6061 supported. Use a <tt>.forward</tt> file instead.</p>
6064 The <prgn>rmail</prgn> program used by UUCP
6065 for incoming mail should be <tt>/usr/sbin/rmail</tt>.
6066 Likewise, <prgn>rsmtp</prgn>, for receiving
6067 batch-SMTP-over-UUCP, should be <tt>/usr/sbin/rsmtp</tt> if it
6071 If you need to know what name to use (for example) on
6072 outgoing news and mail messages which are generated locally,
6073 you should use the file <tt>/etc/mailname</tt>. It will
6074 contain the portion after the username and <tt>@</tt> (at)
6075 sign for email addresses of users on the machine (followed
6079 A package should check for the existence of this file. If
6080 it exists it should use it without comment. (An MTA's
6081 prompting configuration script may wish to prompt the user
6082 even if it finds this file exists.) If it does not exist it
6083 should prompt the user for the value and store it in
6084 <tt>/etc/mailname</tt> as well as using it in the package's
6085 configuration. The prompt should make it clear that the
6086 name will not just be used by that package. For example, in
6087 this situation the INN package says:
6089 Please enter the `mail name' of your system. This is the
6090 hostname portion of the address to be shown on outgoing
6091 news and mail messages. The default is
6092 <var>syshostname</var>, your system's host name. Mail
6093 name [`<var>syshostname</var>']:
6095 where <var>syshostname</var> is the output of <tt>hostname
6096 --fqdn</tt>.</p></sect>
6100 <heading>News system configuration</heading>
6103 All the configuration files related to the NNTP (news)
6104 servers and clients should be located under
6105 <tt>/etc/news</tt>.</p>
6108 There are some configuration issues that apply to a number
6109 of news clients and server packages on the machine. These
6113 <tag>/etc/news/organization</tag>
6114 <item><p>A string which should appear as the
6115 organization header for all messages posted
6116 by NNTP clients on the machine</p></item>
6118 <tag>/etc/news/server</tag>
6119 <item><p>Contains the FQDN of the upstream NNTP
6120 server, or localhost if the local machine is
6121 an NNTP server.</p></item>
6124 Other global files may be added as required for cross-package news
6125 configuration.</p></sect>
6129 <heading>Programs for the X Window System</heading>
6132 <em>Programs that may be configured with support for the X Window
6133 System</em> must be configured to do so and must declare any
6134 package dependencies necessary to satisfy their runtime
6135 requirements when using the X Window System, unless the package
6136 in question is of standard or higher priority, in which case
6137 X-specific binaries may be split into a separate package, or
6138 alternative versions of the package with X support may be
6144 <em>Packages which provide an X server</em> that, directly or
6145 indirectly, communicates with real input and display hardware
6146 should declare in their control data that they provide the
6147 virtual package <tt>xserver</tt>.
6150 This implements current practice, and provides an actual
6151 policy for usage of the "xserver" virtual package which
6152 appears in the virtual packages list. In a nutshell, X
6153 servers that interface directly with the display and input
6154 hardware or via another subsystem (e.g., GGI) should provide
6155 xserver. Things like Xvfb, Xnest, and Xprt should not.
6161 <em>Packages that provide a terminal emulator</em> for the X
6162 Window System which support a terminal type with a terminfo
6163 description provided in the <tt>ncurses-base</tt> package
6164 should declare in their control data that they provide the
6165 virtual package <tt>x-terminal-emulator</tt>. They should
6166 also register themselves as an alternative for
6167 <tt>/usr/bin/x-terminal-emulator</tt>, with a priority of
6172 <em>Packages that provide window managers</em> should declare in
6173 their control data that they provide the virtual package
6174 <tt>x-window-manager</tt>. They should also register themselves as an
6175 alternative for <tt>/usr/bin/x-window-manager</tt>, with a priority
6176 calculated as follows:
6178 <item>Start with a priority of 20.</item>
6179 <item>If the window manager supports the Debian menu system,
6180 add 20 points if this support is available in the
6181 package's default configuration (i.e., no
6182 configuration files belonging to the system or user
6183 have to be edited to activate the feature); if
6184 configuration files must be modified, add only 10
6186 <item>If the window manager permits the X session to be
6187 restarted using a <em>different</em> window manager
6188 (without killing the X server) in its default
6189 configuration, add 10 points; otherwise add
6195 <em>Packages that provide fonts for the X Window System</em>
6196 must do a number of things to ensure that they are both
6197 available without modification of the X or font server
6198 configuration, and that they do not corrupt files used by
6199 other font packages to register information about themselves.
6202 Fonts of any type supported by the X Window System
6203 should be be in a separate binary package from any
6204 executables, libraries, or documentation (except that
6205 specific to the fonts shipped); if a program or
6206 library is <em>unusable</em> without one or more
6207 specific fonts, the package containing the program or
6208 library should declare a dependency on the package(s)
6209 containing the font(s) it requires.
6212 BDF fonts should be converted to PCF fonts with the
6213 <tt>bdftopcf</tt> utility (available in the
6214 <tt>xutils</tt> package, <tt>gzip</tt>ped, and
6215 placed in a directory that corresponds to their
6219 100 dpi fonts should be placed in
6220 <tt>/usr/X11R6/lib/X11/fonts/100dpi/</tt>.
6223 75 dpi fonts should be placed in
6224 <tt>/usr/X11R6/lib/X11/fonts/75dpi/</tt>.
6227 Character-cell fonts, cursor fonts, and other
6228 low-resolution fonts should be placed in
6229 <tt>/usr/X11R6/lib/X11/fonts/misc/</tt>.
6234 Speedo fonts should be placed in
6235 <tt>/usr/X11R6/lib/X11/fonts/Speedo/</tt>.
6238 Type 1 fonts should be placed in
6239 <tt>/usr/X11R6/lib/X11/fonts/Type1/</tt>. If font
6240 metric files are available, they may be placed here as
6244 Subdirectories of <tt>/usr/X11R6/lib/X11/fonts/</tt>
6245 other than those listed above should be neither created nor
6246 used. (The <tt>PEX</tt> and <tt>cyrillic</tt> directories are
6247 excepted for historical reasons, but installation of files into
6248 these directories remains discouraged.)
6251 Font packages may, instead of placing files directly in
6252 the X font directories listed above, provide symbolic links in
6253 the font directory which point to the files' actual location
6254 in the filesystem. Such a location should comply with the
6258 Font packages should not contain both 75dpi and 100dpi
6259 versions of a font. If both are available, they should be
6260 provided in separate binary packages with "-75dpi" or "-100dpi"
6261 appended to the names of the packages containing the
6262 corresponding fonts.
6265 Fonts destined for the <tt>misc</tt> subdirectory should
6266 not be included in the same package as 75dpi or 100dpi fonts;
6267 instead, they should be provided in a separate package with
6268 "-misc" appended to its name.
6271 Font packages <em>must not</em> provide the files
6272 <tt>fonts.dir</tt>, <tt>fonts.alias</tt>, or
6273 <tt>fonts.scale</tt> in a font directory.
6276 <tt>fonts.dir</tt> files must not be provided at
6280 <tt>fonts.alias</tt> and <tt>fonts.scale</tt>
6281 files, if needed, should be provided in the
6283 <tt>/etc/X11/fonts/<em>fontdir</em>/<em>package</em>.<em>extension</em></tt>,
6284 where <em>fontdir</em> is the name of the
6286 <tt>/usr/X11R6/lib/X11/fonts/</tt> where the
6287 package's corresponding fonts are stored (e.g.,
6288 <tt>75dpi</tt> or <tt>misc</tt>),
6289 <em>package</em> is the name of the package that
6290 provides these fonts, and <em>extension</em> is
6291 either <tt>scale</tt> or <tt>alias</tt>,
6292 whichever corresponds to the file
6298 Font packages must declare a dependency on
6299 <tt>xutils</tt> and, in the package
6300 post-installation and post-removal scripts, invoke the
6301 <tt>mkfontdir</tt> command on each directory into
6302 which they installed fonts.
6305 Font packages that provide one or more
6306 <tt>fonts.scale</tt> files as described above must declare a
6307 versioned dependency on <tt>xutils (>=
6308 4.0.2)</tt> and invoke <tt>update-fonts-scale</tt> on each
6309 directory into which they installed fonts
6310 <em>before</em> invoking <tt>mkfontdir</tt> on that
6311 directory. This invocation must occur in both the
6312 post-installation and post-removal scripts.
6315 Font packages that provide one or more
6316 <tt>fonts.alias</tt> files as described above must
6317 declare a versioned dependency on <tt>xutils
6318 (>= 4.0.2)</tt> and, in the package
6319 post-installation and post-removal scripts, invoke
6320 <tt>update-fonts-alias</tt> on each directory into
6321 which they installed fonts.
6324 Font packages must not provide alias names for the
6325 fonts they include which collide with alias names already in
6326 use by fonts already packaged.
6329 Font packages must not provide fonts with the same XLFD
6330 registry name as another font already packaged.
6336 <em>Application defaults</em> files must be installed in the
6337 directory <tt>/etc/X11/app-defaults/</tt> (use of a
6338 localized subdirectory of <tt>/etc/X11/</tt> as described in
6339 the <em>X Toolkit Intrinsics - C Language Interface</em>
6340 manual is also permitted). They must be registered as
6341 <em>conffile</em>s or handled as configuration files. For
6342 programs that are not linked against the X Toolkit (Xt)
6343 library, customization of programs' X resources may also be
6344 supported with the provision of a file with the same name as
6345 that of the package placed in the
6346 <tt>/etc/X11/Xresources/</tt> directory, which must
6347 registered as a <em>conffile</em> or handled as a
6348 configuration file. <em>Important:</em> packages that
6349 install files into the <tt>/etc/X11/Xresources/</tt>
6350 directory <em>must</em> declare a conflict with <tt>xbase
6351 (<< 3.3.2.3a-2)</tt>; if this is not done it is
6352 possible for the installing package to destroy a
6353 previously-existing <tt>/etc/X11/Xresources</tt> file which
6354 had been customized by the system administrator.
6358 <em>Packages using the X Window System should abide by the FHS
6359 standard whenever possible</em>; they should install binaries,
6360 libraries, manual pages, and other files in FHS-mandated
6361 locations wherever possible. This means that files must
6362 not be installed into <tt>/usr/X11R6/bin/</tt>,
6363 <tt>/usr/X11R6/lib/</tt>, or <tt>/usr/X11R6/man/</tt> unless
6364 this is necessary for the package to operate properly.
6365 Configuration files for window managers and display managers
6366 should be placed in a subdirectory of <tt>/etc/X11/</tt>
6367 corresponding to the package name due to these programs'
6368 tight integration with the mechanisms of the X Window
6369 System. Application-level programs should use the
6370 <tt>/etc/</tt> directory unless otherwise mandated by
6371 policy. The installation of files into subdirectories of
6372 <tt>/usr/X11R6/include/X11/</tt> and
6373 <tt>/usr/X11R6/lib/X11/</tt> is permitted but discouraged;
6374 package maintainers should determine if subdirectories of
6375 <tt>/usr/lib/</tt> and <tt>/usr/share/</tt> can be used
6376 instead (symlinks from the X11R6 directories to
6377 FHS-compliant locations is encouraged if the program is not
6378 easily configured to look elsewhere for its files).
6379 Packages must not provide -- or install files into -- the
6380 directories <tt>/usr/bin/X11/</tt>,
6381 <tt>/usr/include/X11/</tt>, or <tt>/usr/lib/X11/</tt>.
6382 Files within a package should, however, make reference to
6383 these directories, rather than their X11R6-named
6384 counterparts <tt>/usr/X11R6/bin/</tt>,
6385 <tt>/usr/X11R6/include/X11/</tt>, and
6386 <tt>/usr/X11R6/lib/X11/</tt>, if the resources being
6387 referred to have not been moved to FHS-compliant locations.
6391 <em>Programs that require the non-DFSG-compliant OSF/Motif
6392 library</em> should be compiled against and tested with
6393 LessTif (a free re-implementation of Motif) instead. If the
6394 maintainer judges that the program or programs do not work
6395 sufficiently well with LessTif to be distributed and
6396 supported, but do so when compiled against Motif, then two
6397 versions of the package should be created; one linked
6398 statically against Motif and with <tt>-smotif</tt> appended
6399 to the package name, and one linked dynamically against
6400 Motif and with <tt>-dmotif</tt> appended to the package
6401 name. Both Motif-linked versions are dependent upon
6402 non-DFSG-compliant software and thus cannot be uploaded to
6403 the main distribution; if the software is itself
6404 DFSG-compliant it may be uploaded to the contrib
6405 distribution. While known existing versions of OSF/Motif
6406 permit unlimited redistribution of binaries linked against
6407 the library (whether statically or dynamically), it is the
6408 package maintainer's responsibility to determine whether
6409 this is permitted by the license of the copy of OSF/Motif in
6410 his or her possession.
6416 <heading>Emacs lisp programs</heading>
6419 Please refer to the `Debian Emacs Policy' (documented in
6420 <tt>debian-emacs-policy.gz</tt> of the
6421 <prgn>emacsen-common</prgn> package) for details of how to
6422 package emacs lisp programs.</p></sect>
6426 <heading>Games</heading>
6429 The permissions on /var/games are 755
6430 <tt>root.root</tt>.</p>
6433 Each game decides on its own security policy.</p>
6436 Games which require protected, privileged access to
6437 high-score files, savegames, etc., may be made
6438 set-<em>group</em>-id (mode 2755) and owned by
6439 <tt>root.games</tt>, and use files and directories with
6440 appropriate permissions (770 <tt>root.games</tt>, for
6441 example). They must not be made
6442 set-<em>user</em>-id, as this causes security problems. (If
6443 an attacker can subvert any set-user-id game they can
6444 overwrite the executable of any other, causing other players
6445 of these games to run a Trojan horse program. With a
6446 set-group-id game the attacker only gets access to less
6447 important game data, and if they can get at the other
6448 players' accounts at all it will take considerably more
6452 Some packages, for example some fortune cookie programs, are
6453 configured by the upstream authors to install with their
6454 data files or other static information made unreadable so
6455 that they can only be accessed through set-id programs
6456 provided. You should not do this in a Debian package: anyone can
6457 download the <tt>.deb</tt> file and read the data from it,
6458 so there is no point making the files unreadable. Not
6459 making the files unreadable also means that you don't have
6460 to make so many programs set-id, which reduces the risk of a
6464 As described in the FHS, binaries of games should be
6465 installed in the directory <tt>/usr/games</tt>. This also
6466 applies to games that use the X Window System. Manual pages
6467 for games (X and non-X games) should be installed in
6468 <tt>/usr/share/man/man6</tt>.</p>
6472 <chapt><heading>Documentation</heading>
6476 <heading>Manual pages</heading>
6479 You should install manual pages in <prgn>nroff</prgn> source
6480 form, in appropriate places under <tt>/usr/share/man</tt>. You
6481 should only use sections 1 to 9 (see the FHS for more
6482 details). You must not install a preformatted `cat
6486 Each program, utility, and function should have an
6487 associated manpage included in the same package. It is
6488 suggested that all configuration files also have a manual
6489 page included as well.
6493 If no manual page is available for a particular program,
6494 utility, function or configuration file and this is reported as a bug on
6495 debian-bugs, a symbolic link from the requested manual page
6496 to the <manref name="undocumented" section="7"> manual page
6497 may be provided. This symbolic link can be created from
6498 <tt>debian/rules</tt> like this:
6500 ln -s ../man7/undocumented.7.gz \
6501 debian/tmp/usr/share/man/man[1-9]/the_requested_manpage.[1-9].gz
6503 This manpage claims that the lack of a manpage has been
6504 reported as a bug, so you may only do this if it really has
6505 (you can report it yourself, if you like). Do not close the
6506 bug report until a proper manpage is available.</p>
6509 You may forward a complaint about a missing manpage to the
6510 upstream authors, and mark the bug as forwarded in the
6511 Debian bug tracking system. Even though the GNU Project do
6512 not in general consider the lack of a manpage to be a bug,
6513 we do--if they tell you that they don't consider it a bug
6514 you should leave the bug in our bug tracking system open
6518 Manual pages should be installed compressed using <tt>gzip
6522 If one manpage needs to be accessible via several names it
6523 is better to use a symbolic link than the <tt>.so</tt>
6524 feature, but there is no need to fiddle with the relevant
6525 parts of the upstream source to change from <tt>.so</tt> to
6526 symlinks--don't do it unless it's easy. You should not create hard
6527 links in the manual page directories, nor put
6528 absolute filenames in <tt>.so</tt> directives. The filename
6529 in a <tt>.so</tt> in a manpage should be relative to the
6530 base of the manpage tree (usually
6531 <tt>/usr/share/man</tt>).</p></sect>
6535 <heading>Info documents</heading>
6538 Info documents should be installed in <tt>/usr/share/info</tt>.
6539 They should be compressed with <tt>gzip -9</tt>.</p>
6542 Your package should call <prgn>install-info</prgn> to update the Info
6544 file, in its post-installation script:
6546 install-info --quiet --section Development Development \
6547 /usr/share/info/foobar.info
6551 It is a good idea to specify a section for the location of
6552 your program; this is done with the <tt>--section</tt>
6553 switch. To determine which section to use, you should look
6554 at <tt>/usr/share/info/dir</tt> on your system and choose the most
6555 relevant (or create a new section if none of the current
6556 sections are relevant). Note that the <tt>--section</tt>
6557 flag takes two arguments; the first is a regular expression
6558 to match (case-insensitively) against an existing section,
6559 the second is used when creating a new one.</p>
6562 You should remove the entries in the pre-removal script:
6564 install-info --quiet --remove /usr/share/info/foobar.info
6568 If <prgn>install-info</prgn> cannot find a description entry
6569 in the Info file you must supply one. See <manref
6570 name="install-info" section="8"> for details.</p>
6574 <heading>Additional documentation</heading>
6577 Any additional documentation that comes with the package may
6578 be installed at the discretion of the package maintainer.
6579 Text documentation should be installed in a directory
6580 <tt>/usr/share/doc/<var>package</var></tt>, where
6581 <var>package</var> is the name of the package, and
6582 compressed with <tt>gzip -9</tt> unless it is small.</p>
6585 If a package comes with large amounts of documentation which
6586 many users of the package will not require you should create
6587 a separate binary package to contain it, so that it does not
6588 take up disk space on the machines of users who do not need
6589 or want it installed.</p>
6592 It is often a good idea to put text information files
6593 (<tt>README</tt>s, changelogs, and so forth) that come with
6594 the source package in <tt>/usr/share/doc/<var>package</var></tt>
6595 in the binary package. However, you don't need to install
6596 the instructions for building and installing the package, of
6600 Files in <tt>/usr/share/doc</tt> should not be referenced by
6601 any program, and the system administrator should be able to
6602 delete them without causing any programs to break. Any files
6603 that are referenced by programs but are also useful as
6604 standalone documentation should be installed under
6605 <tt>/usr/share/<package>/</tt> and symlinked in
6606 <tt>/usr/share/doc/<package>/</tt>.
6612 <heading>Accessing the documentation</heading>
6615 Former Debian releases placed all additional documentation
6616 in <tt>/usr/doc/<var>package</var></tt>. To realize a
6618 <tt>/usr/share/doc/<var>package</var></tt>, each package
6619 must maintain a symlink <tt>/usr/doc/<var>package</var></tt>
6620 that points to the new location of its documentation in
6621 <tt>/usr/share/doc/<var>package</var></tt><footnote>These
6622 symlinks will be removed in the future, but they have to be
6623 there for compatibility reasons until all packages have
6624 moved and the policy is changed accordingly.</footnote>.
6625 The symlink must be created when the package is installed;
6626 it cannot be contained in the package itself due to problems
6627 with <prgn>dpkg</prgn>. One reasonable way to accomplish
6628 this is to put the following in the package's
6629 <prgn>postinst</prgn>:
6631 if [ "$1" = "configure" ]; then
6632 if [ -d /usr/doc -a ! -e /usr/doc/#PACKAGE# \
6633 -a -d /usr/share/doc/#PACKAGE# ]; then
6634 ln -sf ../share/doc/#PACKAGE# /usr/doc/#PACKAGE#
6638 And the following in the package's <prgn>prerm</prgn>:
6640 if [ \( "$1" = "upgrade" -o "$1" = "remove" \) \
6641 -a -L /usr/doc/#PACKAGE# ]; then
6642 rm -f /usr/doc/#PACKAGE#
6649 <heading>Preferred documentation formats</heading>
6652 The unification of Debian documentation is being carried out
6656 If your package comes with extensive documentation in a
6657 mark up format that can be converted to various other formats
6658 you should if possible ship HTML versions in a binary
6659 package, in the directory
6660 <tt>/usr/share/doc/<var>appropriate package</var></tt> or its
6663 <p>The rationale: The important thing here is that HTML
6664 docs should be available in <em>some</em> package, not
6665 necessarily in the main binary package, though. </p>
6670 Other formats such as PostScript may be provided at your
6674 <sect id="copyrightfile">
6675 <heading>Copyright information</heading>
6678 Every package must be accompanied by a verbatim copy of its
6679 copyright and distribution license in the file
6680 /usr/share/doc/<package-name>/copyright. This file must
6681 neither be compressed nor be a symbolic link.</p>
6684 In addition, the copyright file must say where the upstream
6685 sources (if any) were obtained, and should explain briefly what
6686 modifications were made in the Debian version of the package
6687 compared to the upstream one. It should name the original
6688 authors of the package and the Debian maintainer(s) who were
6689 involved with its creation.</p>
6692 A copy of the file which will be installed in
6693 <tt>/usr/share/doc/<var>package</var>/copyright</tt> should be
6694 in <tt>debian/copyright</tt>.</p>
6698 /usr/share/doc/<package-name> may be a symbolic link to a
6699 directory in /usr/share/doc only if two packages both come from
6700 the same source and the first package has a "Depends"
6701 relationship on the second. These rules are important
6702 because copyrights must be extractable by mechanical
6706 Packages distributed under the UCB BSD license, the Artistic
6707 license, the GNU GPL, and the GNU LGPL should refer to the
6708 files /usr/share/common-licenses/BSD,
6709 /usr/share/common-licenses/Artistic,
6710 /usr/share/common-licenses/GPL, and
6711 /usr/share/common-licenses/LGPL.
6714 Why "licenses" and not "copyright"? Because
6715 <tt>/usr/doc/copyright</tt> used to contain all the
6716 copyright files, plus the four common licenses GPL,
6717 LGPL, Artistic and BSD. Now individual copyright files
6718 for packages are no longer in a common directory. Once
6719 <tt>/usr/doc/copyright</tt> is almost empty it makes
6720 sense to rename "copyright" to "licenses"
6723 Why "common-licenses" and not "licenses"? Because if I
6724 put just "licenses" I'm sure I will receive a bug report
6725 saying "license foo is not included in the licenses
6726 directory. They are not all the licenses, just a few
6727 common ones. I could use /usr/share/doc/common-licenses
6728 but I think this is too long, and, after all, the GPL
6729 does not "document" anything, it is merely a license.
6735 You should not use the copyright file as a general <tt>README</tt>
6736 file. If your package has such a file it should be
6737 installed in <tt>/usr/share/doc/<var>package</var>/README</tt> or
6738 <tt>README.Debian</tt> or some other appropriate place.</p>
6742 <heading>Examples</heading>
6745 Any examples (configurations, source files, whatever),
6746 should be installed in a directory
6747 <tt>/usr/share/doc/<var>package</var>/examples</tt>. These
6748 files should not be referenced by any program--they're there
6749 for the benefit of the system administrator and users, as
6750 documentation only. Architecture-specific example files
6751 should be installed in a directory
6752 <tt>/usr/lib/<var>package</var>/examples</tt>, and files in
6753 <tt>/usr/share/doc/<var>package</var>/examples</tt> symlink
6754 to files in it. Or the latter directory may be a symlink to
6758 <sect id="instchangelog">
6759 <heading>Changelog files</heading>
6762 Packages that are not Debian-native must contain a copy of
6763 <tt>debian/changelog</tt> file from the Debian source tree
6764 in <tt>/usr/share/doc/<var>package</var></tt> as
6765 <tt>changelog.Debian.gz</tt>. If an upstream changelog is
6766 available, it should be accessible as
6767 <tt>/usr/share/doc/<var>package</var>/changelog.gz</tt> in
6768 plain text. If the upstream changelog is distributed in
6769 HTML, it should be made available in that form as
6770 <tt>/usr/share/doc/<var>package</var>/changelog.html.gz</tt>
6771 and the <tt>changelog.gz</tt> should be generated using, eg,
6772 <tt>lynx -dump -nolist</tt>. If the upstream changelog files
6773 do not already conform to this naming convention, then this
6774 may be achieved either by renaming the files, or adding a
6775 symbolic link, at the maintainer's discretion.
6778 Rationale: People should not have to look into two
6779 places for upstream changelogs merely because they are
6787 All these files should be installed compressed using <tt>gzip -9</tt>,
6788 as they will become large with time even if they start out
6793 If the package has only one changelog which is used both as
6794 the Debian changelog and the upstream one because there is
6795 no separate upstream maintainer then that changelog should
6796 usually be installed as
6797 <tt>/usr/share/doc/<var>package</var>/changelog.gz</tt>; if
6798 there is a separate upstream maintainer, but no upstream
6799 changelog, then the Debian changelog should still be called
6800 <tt>changelog.Debian.gz</tt>.</p>