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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>Julian Gilbey <email>jdg@debian.org</email></p>
58 <p>Manoj Srivastava <email>srivasta@debian.org</email></p>
66 Copyright ©1996,1997,1998 Ian Jackson
67 and Christian Schwarz.
70 This manual is free software; you may redistribute it and/or
71 modify it under the terms of the GNU General Public License
72 as published by the Free Software Foundation; either version
73 2, or (at your option) any later version.
77 This is distributed in the hope that it will be useful, but
78 <em>without any warranty</em>; without even the implied
79 warranty of merchantability or fitness for a particular
80 purpose. See the GNU General Public License for more
85 A copy of the GNU General Public License is available as
86 <tt>/usr/share/common-licenses/GPL</tt> in the Debian GNU/Linux
87 distribution or on the World Wide Web at
88 <url id="http://www.gnu.org/copyleft/gpl.html"
89 name="The GNU General Public Licence">. You can also obtain it by writing to the
90 Free Software Foundation, Inc., 59 Temple Place - Suite 330,
91 Boston, MA 02111-1307, USA.
99 <heading>About this manual</heading>
101 <heading>Scope</heading>
103 This manual describes the policy requirements for the Debian
104 GNU/Linux distribution. This includes the structure and
105 contents of the Debian archive and several design issues of the
106 operating system, as well as technical requirements that
107 each package must satisfy to be included in the
113 This manual also describes Debian policy as it relates to
114 creating Debian packages. It is not a tutorial on how to build
115 packages, nor is it exhaustive where it comes to describing
116 the behavior of the packaging system. Instead, this manual
117 attempts to define the interface to the package management
118 system that the developers have to be conversant with.
121 Informally, the criteria used for inclusion is that the
122 material meet one of the following requirements:
124 <tag>Standard interfaces</tag>
127 The material presented represents an interface to
128 the packaging system that is mandated for use, and
129 is used by, a significant number of packages, and
130 therefore should not be changed without peer
131 review. Package maintainers can then rely on this
132 interfaces not changing, and the package
133 management software authors need to ensure
134 compatibility with these interface
135 definitions. (Control file and and changelog file
136 formats are examples.)
139 <tag>Chosen Convention</tag>
142 If there are a number of technically viable choices
143 that can be made, but one needs to select one of
144 these options for inter-operability. The version
145 number format is one example.
149 Please note that these are not mutually exclusive;
150 selected conventions often become parts of standard
157 The footnotes present in this manual are
158 merely informative, and are not part of Debian policy itself.
163 In this manual, the words <em>must</em>, <em>should</em> and
164 <em>may</em>, and the adjectives <em>required</em>,
165 <em>recommended</em> and <em>optional</em>, are used to
166 distinguish the significance of the various guidelines in
167 this policy document. Packages that do not conform the the
168 guidelines denoted by <em>must</em> (or <em>required</em>)
169 will generally not be considered acceptable for the Debian
170 distribution. Non-conformance with guidelines denoted by
171 <em>should</em> (or <em>recommended</em>) will generally be
172 considered a bug, but will not necessarily render a package
173 unsuitable for distribution. Guidelines denoted by
174 <em>may</em> (or <em>optional</em>) are truly optional and
175 adherence is left to the maintainer's discretion.
178 These classifications are roughly equivalent to the bug
179 severities <em>serious</em> (for <em>must</em> or
180 <em>required</em> directive violations), <em>minor</em>,
181 <em>normal</em> or <em>important</em>
182 (for <em>should</em> or <em>recommended</em> directive
183 violations) and <em>wishlist</em> (for <em>optional</em>
185 <p>Compare RFC 2119. Note, however, that these words are
186 used in a different way in this document.</p>
190 Much of the information presented in this manual will be
191 useful even when building a package which is to be
192 distributed in some other way or is intended for local use
197 <heading>New versions of this document</heading>
199 The current version of this document is always accessible
200 from the Debian FTP server <ftpsite>ftp.debian.org</ftpsite>
202 <ftppath>/debian/doc/package-developer/policy.txt.gz</ftppath>
203 (also available from the same directory are several other
204 formats: <tt>policy.html.tar.gz</tt>, <tt>policy.pdf.gz</tt>
205 and <tt>policy.ps.gz</tt>) or from the <url
206 id="http://www.debian.org/doc/debian-policy/" name="Debian
207 Policy Manual"> webpage.</p>
210 In addition, this manual is distributed via the Debian package
211 <tt>debian-policy</tt>.
215 The <tt>debian-policy</tt> package also includes the file
216 <tt>upgrading-checklist.txt</tt> which indicates policy
217 changes between versions of this document.
221 <heading>Feedback</heading>
224 As the Debian GNU/Linux system is continuously evolving this
228 While the authors of this document have tried hard to avoid
229 typos and other errors, these do still occur. If you discover
230 an error in this manual or if you want to give any
231 comments, suggestions, or criticisms please send an email to
232 the Debian Policy List,
233 <email>debian-policy@lists.debian.org</email>, or submit a
234 bug report against the <tt>debian-policy</tt> package.
239 <heading>The Debian Archive</heading>
241 The Debian GNU/Linux system is maintained and distributed as a
242 collection of <em>packages</em>. Since there are so many of
243 them (currently well over 6000), they are split into
244 <em>sections</em> and given <em>priorities</em> to simplify
245 the handling of them.
248 The effort of the Debian project is to build a free operating
249 system, but not every package we want to make accessible is
250 <em>free</em> in our sense (see the Debian Free Software
251 Guidelines, below), or may be imported/exported without
252 restrictions. Thus, the archive is split into the sections
253 <em>main</em>, <em>non-free</em>, <em>contrib</em>,
254 <em>non-US/main</em>, <em>non-US/non-free</em>, and
255 <em>non-US/contrib</em>. The sections are explained in detail
260 The <em>main</em> and the <em>non-US/main</em> sections
261 together form the <em>Debian GNU/Linux distribution</em>.
265 Packages in the other sections are not considered to be part
266 of the Debian distribution, although we support their use and
267 provide infrastructure for them (such as our bug-tracking
268 system and mailing lists). This Debian Policy Manual applies
269 to these packages as well.</p>
271 <sect id="pkgcopyright">
272 <heading>Package copyright and sections</heading>
274 The aims of this section are:
276 <list compact="compact">
278 <p>to allow us to make as much software available as we
282 <p>to allow us to encourage everyone to write free
286 <p>to allow us to make it easy for people to produce
287 CD-ROMs of our system without violating any licenses,
288 import/export restrictions, or any other laws.</p>
293 <heading>The Debian Free Software Guidelines</heading>
295 The Debian Free Software Guidelines (DFSG) form our
296 definition of `free software'. These are:
298 <tag>Free Redistribution
302 The license of a Debian component may not restrict any
303 party from selling or giving away the software as a
304 component of an aggregate software distribution
305 containing programs from several different
306 sources. The license may not require a royalty or
307 other fee for such sale.
314 The program must include source code, and must allow
315 distribution in source code as well as compiled form.
322 The license must allow modifications and derived
323 works, and must allow them to be distributed under the
324 same terms as the license of the original software.
327 <tag>Integrity of The Author's Source Code
331 The license may restrict source-code from being
332 distributed in modified form <em>only</em> if the
333 license allows the distribution of ``patch files''
334 with the source code for the purpose of modifying the
335 program at build time. The license must explicitly
336 permit distribution of software built from modified
337 source code. The license may require derived works to
338 carry a different name or version number from the
339 original software. (This is a compromise. The Debian
340 Project encourages all authors to not restrict any
341 files, source or binary, from being modified.)
344 <tag>No Discrimination Against Persons or Groups
348 The license must not discriminate against any person
352 <tag>No Discrimination Against Fields of Endeavor
356 The license must not restrict anyone from making use
357 of the program in a specific field of endeavor. For
358 example, it may not restrict the program from being
359 used in a business, or from being used for genetic
363 <tag>Distribution of License
367 The rights attached to the program must apply to all
368 to whom the program is redistributed without the need
369 for execution of an additional license by those
373 <tag>License Must Not Be Specific to Debian
377 The rights attached to the program must not depend on
378 the program's being part of a Debian system. If the
379 program is extracted from Debian and used or
380 distributed without Debian but otherwise within the
381 terms of the program's license, all parties to whom
382 the program is redistributed must have the same
383 rights as those that are granted in conjunction with
387 <tag>License Must Not Contaminate Other Software
391 The license must not place restrictions on other
392 software that is distributed along with the licensed
393 software. For example, the license must not insist
394 that all other programs distributed on the same medium
395 must be free software.
398 <tag>Example Licenses
402 The ``GPL,'' ``BSD,'' and ``Artistic'' licenses are
403 examples of licenses that we consider <em>free</em>.
410 <heading>The main section</heading>
412 Every package in <em>main</em> and <em>non-US/main</em>
413 must comply with the DFSG (Debian Free Software
417 In addition, the packages in <em>main</em>
418 <list compact="compact">
421 must not require a package outside of <em>main</em>
422 for compilation or execution (thus, the package must
423 not declare a "Depends", "Recommends", or
424 "Build-Depends" relationship on a non-<em>main</em>
430 must not be so buggy that we refuse to support them,
436 must meet all policy requirements presented in this
443 Similarly, the packages in <em>non-US/main</em>
444 <list compact="compact">
447 must not require a package outside of <em>main</em>
448 or <em>non-US/main</em> for compilation or
454 must not be so buggy that we refuse to support them,
459 must meet all policy requirements presented in this
467 <heading>The contrib section</heading>
469 Every package in <em>contrib</em> and
470 <em>non-US/contrib</em> must comply with the DFSG.
474 In addition, the packages in <em>contrib</em> and
475 <em>non-US/contrib</em>
476 <list compact="compact">
479 must not be so buggy that we refuse to support them,
485 must meet all policy requirements presented in this
493 Furthermore, packages in <em>contrib</em> must not require
494 a package in a <em>non-US</em> section for compilation or
499 Examples of packages which would be included in
500 <em>contrib</em> or <em>non-US/contrib</em> are:
501 <list compact="compact">
504 free packages which require <em>contrib</em>,
505 <em>non-free</em> packages or packages which are not
506 in our archive at all for compilation or execution,
512 wrapper packages or other sorts of free accessories for
520 <heading>The non-free section</heading>
522 Packages must be placed in <em>non-free</em> or
523 <em>non-US/non-free</em> if they are not compliant with
524 the DFSG or are encumbered by patents or other legal
525 issues that make their distribution problematic.
528 In addition, the packages in <em>non-free</em> and
529 <em>non-US/non-free</em>
530 <list compact="compact">
533 must not be so buggy that we refuse to support them,
539 must meet all policy requirements presented in this
540 manual that it is possible for them to meet.
543 It is possible that there are policy
544 requirements which the package is unable to
545 meet, for example, if the source is
546 unavailable. These situations will need to be
547 handled on a case-by-case basis.
557 <heading>The non-US sections</heading>
559 Some programs with cryptographic program code need to be
560 stored on the <em>non-US</em> server because of United
561 States export restrictions. Such programs must be
562 distributed in the appropriate <em>non-US</em> section,
563 either <em>non-US/main</em>, <em>non-US/contrib</em> or
564 <em>non-US/non-free</em>.
567 This applies only to packages which contain cryptographic
568 code. A package containing a program with an interface to
569 a cryptographic program or a program that's dynamically
570 linked against a cryptographic library should not be
571 distributed via the <em>non-US</em> server if it is
572 capable of running without the cryptographic library or
577 <heading>Further copyright considerations</heading>
579 Every package must be accompanied by a verbatim copy of
580 its copyright and distribution license in the file
581 <tt>/usr/share/doc/<em><package-name></em>/copyright</tt>
582 (see <ref id="copyrightfile"> for further details).
585 We reserve the right to restrict files from being included
586 anywhere in our archives if
587 <list compact="compact">
590 their use or distribution would break a law,
595 there is an ethical conflict in their distribution or
601 we would have to sign a license for them, or
606 their distribution would conflict with other project
614 Programs whose authors encourage the user to make
615 donations are fine for the main distribution, provided
616 that the authors do not claim that not donating is
617 immoral, unethical, illegal or something similar; in such
618 a case they must go in <em>non-free</em>.</p>
621 Packages whose copyright permission notices (or patent
622 problems) do not even allow redistribution of binaries
623 only, and where no special permission has been obtained,
624 must not be placed on the Debian FTP site and its mirrors
628 Note that under international copyright law (this applies
629 in the United States, too), <em>no</em> distribution or
630 modification of a work is allowed without an explicit
631 notice saying so. Therefore a program without a copyright
632 notice <em>is</em> copyrighted and you may not do anything
633 to it without risking being sued! Likewise if a program
634 has a copyright notice but no statement saying what is
635 permitted then nothing is permitted.</p>
638 Many authors are unaware of the problems that restrictive
639 copyrights (or lack of copyright notices) can cause for
640 the users of their supposedly-free software. It is often
641 worthwhile contacting such authors diplomatically to ask
642 them to modify their license terms. However, this can be a
643 politically difficult thing to do and you should ask for
644 advice on the <tt>debian-legal</tt> mailing list first, as
649 When in doubt about a copyright, send mail to
650 <email>debian-legal@lists.debian.org</email>. Be prepared
651 to provide us with the copyright statement. Software
652 covered by the GPL, public domain software and BSD-like
653 copyrights are safe; be wary of the phrases `commercial
654 use prohibited' and `distribution restricted'.
658 <heading>Subsections</heading>
661 The packages in the sections <em>main</em>,
662 <em>contrib</em> and <em>non-free</em> are grouped further
663 into <em>subsections</em> to simplify handling.
667 The section and subsection for each package should be
668 specified in the package's <tt>Section</tt> control
669 record. However, the maintainer of the Debian archive
670 may override this selection to ensure the consistency of
671 the Debian distribution. The <tt>Section</tt> field
672 should be of the form:
673 <list compact="compact">
676 <em>subsection</em> if the package is in the
677 <em>main</em> section,
682 <em>section/subsection</em> if the package is in
683 the <em>contrib</em> or <em>non-free</em> section,
689 <tt>non-US</tt>, <tt>non-US/contrib</tt> or
690 <tt>non-US/non-free</tt> if the package is in
691 <em>non-US/main</em>, <em>non-US/contrib</em> or
692 <em>non-US/non-free</em> respectively.
699 The Debian archive maintainers provide the authoritative
700 list of subsections. At present, they are:
701 <em>admin</em>, <em>base</em>, <em>comm</em>,
702 <em>contrib</em>, <em>devel</em>, <em>doc</em>,
703 <em>editors</em>, <em>electronics</em>, <em>games</em>,
704 <em>graphics</em>, <em>hamradio</em>,
705 <em>interpreters</em>, <em>libs</em>, <em>mail</em>,
706 <em>math</em>, <em>misc</em>, <em>net</em>, <em>news</em>,
707 <em>non-US</em>, <em>non-free</em>, <em>oldlibs</em>,
708 <em>otherosfs</em>, <em>science</em>, <em>shells</em>,
709 <em>sound</em>, <em>tex</em>, <em>text</em>,
710 <em>utils</em>, <em>web</em>, <em>x11</em>.
714 <heading>Priorities</heading>
717 Each package should have a <em>priority</em> value, which is
718 included in the package's <em>control record</em>. This
719 information is used by the Debian package management tools
720 to separate high-priority packages from less-important
724 The following <em>priority levels</em> are recognised by the
725 Debian package management tools.
727 <tag><tt>required</tt></tag>
730 Packages which are necessary for the proper
731 functioning of the system. You must not remove these
732 packages or your system may become totally broken and
733 you may not even be able to use <prgn>dpkg</prgn> to
734 put things back. Systems with only the
735 <tt>required</tt> packages are probably unusable, but
736 they do have enough functionality to allow the
737 sysadmin to boot and install more software.</p>
739 <tag><tt>important</tt></tag>
742 Important programs, including those which one would
743 expect to find on any Unix-like system. If the
744 expectation is that an experienced Unix person who
745 found it missing would say `What on earth is going on,
746 where is <prgn>foo</prgn>?', it must be an
747 <tt>important</tt> package.
750 This is an important criterion because we are
751 trying to produce, amongst other things, a free
755 Other packages without which the system will not run
756 well or be usable must also have priority
757 <tt>important</tt>. This does
758 <em>not</em> include Emacs, the X Window System, TeX
759 or any other large applications. The
760 <tt>important</tt> packages are just a bare minimum of
761 commonly-expected and necessary tools.</p>
763 <tag><tt>standard</tt></tag>
766 These packages provide a reasonably small but not too
767 limited character-mode system. This is what will
768 install by default if the user doesn't select anything
769 else. It doesn't include many large applications, but
770 it does include Emacs (this is more of a piece of
771 infrastructure than an application) and a reasonable
772 subset of TeX and LaTeX.</p>
774 <tag><tt>optional</tt></tag>
777 (In a sense everything that isn't required is
778 optional, but that's not what is meant here.) This is
779 all the software that you might reasonably want to
780 install if you didn't know what it was and don't have
781 specialized requirements. This is a much larger system
782 and includes the X Window System, a full TeX
783 distribution, and many applications. Note that
784 optional packages should not conflict with each other.
787 <tag><tt>extra</tt></tag>
790 This contains all packages that conflict with others
791 with required, important, standard or optional
792 priorities, or are only likely to be useful if you
793 already know what they are or have specialised
800 Packages must not depend on packages with lower priority
801 values (excluding build-time dependencies). In order to
802 ensure this, the priorities of one or more packages may need
808 <heading>Binary packages</heading>
811 The Debian GNU/Linux distribution is based on the Debian
812 package management system, called <prgn>dpkg</prgn>. Thus,
813 all packages in the Debian distribution must be provided
814 in the <tt>.deb</tt> file format.</p>
818 <heading>The package name</heading>
821 Every package must have a name that's unique within the Debian
825 Package names must consist of lower case letters (a-z),
826 digits (0-9), plus (+) and minus (-) signs, and periods
827 (.). They must be at least two characters long and must
828 contain at least one letter.
832 The package name is part of the file name of the
833 <tt>.deb</tt> file and is included in the control field
839 <heading>The maintainer of a package</heading>
841 Every package must have a Debian maintainer (the
842 maintainer may be one person or a group of people
843 reachable from a common email address, such as a mailing
844 list). The maintainer is responsible for ensuring that
845 the package is placed in the appropriate distributions.
849 The maintainer must be specified in the
850 <tt>Maintainer</tt> control field with their correct name
851 and a working email address. If one person maintains
852 several packages, he/she should try to avoid having
853 different forms of their name and email address in
854 the <tt>Maintainer</tt> fields of those packages.
858 If the maintainer of a package quits from the Debian
859 project, "Debian QA Group"
860 <email>packages@qa.debian.org</email> takes over the
861 maintainership of the package until someone else
862 volunteers for that task. These packages are called
863 <em>orphaned packages</em>.
866 The detailed procedure for doing this gracefully can
867 be found in the Debian Developer's Reference, either
868 in the <tt>developers-reference</tt> package, or on
869 the Debian FTP server
870 <ftpsite>ftp.debian.org</ftpsite> as
871 <ftppath>/debian/doc/package-developer/developers-reference.txt.gz</ftppath>
873 id="http://www.debian.org/doc/packaging-manuals/developers-reference/"
874 name="Debian Developer's Reference"> webpage.
882 <heading>The description of a package</heading>
885 Every Debian package must have an extended description
886 stored in the appropriate field of the control record.</p>
889 The description should be written so that it gives the
890 system administrator enough information to decide whether
891 to install the package. This description should not just
892 be copied verbatim from the program's documentation.
893 Instructions for configuring or using the package should
894 not be included -- that is what installation scripts,
895 manual pages, info files, etc., are for. Copyright
896 statements and other administrivia should not be included
897 either -- that is what the copyright file is for.</p>
902 <heading>Dependencies</heading>
905 Every package must specify the dependency information
906 about other packages that are required for the first to
910 For example, a dependency entry must be provided for any
911 shared libraries required by a dynamically-linked executable
912 binary in a package.</p>
915 Packages are not required to declare any dependencies they
916 have on other packages which are marked <tt>Essential</tt>
917 (see below), and should not do so unless they depend on a
918 particular version of that package.</p>
921 Sometimes, a package requires another package to be installed
922 <em>and</em> configured before it can be installed. In this
923 case, you must specify a <tt>Pre-Depends</tt> entry for
927 You should not specify a <tt>Pre-Depends</tt> entry for a
928 package before this has been discussed on the
929 <tt>debian-devel</tt> mailing list and a consensus about
930 doing that has been reached.</p></sect1>
934 <heading>Virtual packages</heading>
937 Sometimes, there are several packages which offer
938 more-or-less the same functionality. In this case, it's
939 useful to define a <em>virtual package</em> whose name
940 describes that common functionality. (The virtual
941 packages only exist logically, not physically--that's why
942 they are called <em>virtual</em>.) The packages with this
943 particular function will then <em>provide</em> the virtual
944 package. Thus, any other package requiring that function
945 can simply depend on the virtual package without having to
946 specify all possible packages individually.</p>
949 All packages should use virtual package names where
950 appropriate, and arrange to create new ones if necessary.
951 They should not use virtual package names (except privately,
952 amongst a cooperating group of packages) unless they have
953 been agreed upon and appear in the list of virtual package
957 The latest version of the authoritative list of virtual
958 package names can be found on
959 <ftpsite>ftp.debian.org</ftpsite> in
960 <ftppath>/debian/doc/package-developer/virtual-package-names-list.txt</ftppath>
961 or your local mirror. In addition, it is included in the
962 <tt>debian-policy</tt> package. The procedure for updating
963 the list is described at the top of the file.</p></sect1>
967 <heading>Base packages</heading>
970 The packages included in the <tt>base</tt> section have a
971 special function. They form a minimum subset of the Debian
972 GNU/Linux system that is installed before everything else
973 on a new system. Thus, only very few packages are allowed
974 to go into the <tt>base</tt> section to keep the required
975 disk usage very small.</p>
978 Most of these packages will have the priority value
979 <tt>required</tt> or at least <tt>important</tt>, and many
980 of them will be tagged <tt>essential</tt> (see below).</p>
983 You must not place any packages into the <tt>base</tt>
984 section before this has been discussed on the
985 <tt>debian-devel</tt> mailing list and a consensus about
986 doing that has been reached.</p></sect1>
990 <heading>Essential packages</heading>
993 Some packages are tagged <tt>essential</tt>. (They have
994 <tt>Essential: yes</tt> in their package control record.)
995 This flag is used for packages that are <em>essential</em>
999 Since these packages cannot be easily removed (one has to
1000 specify an extra <em>force option</em> to
1001 <prgn>dpkg</prgn> to do so), this flag must not be used
1002 unless absolutely necessary. A shared library package
1003 must not be tagged <tt>essential</tt>--dependencies will
1004 prevent its premature removal, and we need to be able to
1005 remove it when it has been superseded.
1009 Since dpkg will not prevent upgrading of other packages
1010 while an <tt>essential</tt> package is in an unconfigured
1011 state, all <tt>essential</tt> packages must supply all of
1012 their core functionality even when unconfigured. If the
1013 package cannot satisfy this requirement it must not be
1014 tagged as essential, and any packages depending on this
1015 package must instead have explicit dependency fields as
1020 You must not tag any packages <tt>essential</tt> before
1021 this has been discussed on the <tt>debian-devel</tt>
1022 mailing list and a consensus about doing that has been
1028 <heading>Maintainer scripts</heading>
1031 The package installation scripts should avoid producing
1032 output which it is unnecessary for the user to see and
1033 should rely on <prgn>dpkg</prgn> to stave off boredom on
1034 the part of a user installing many packages. This means,
1035 amongst other things, using the <tt>--quiet</tt> option on
1036 <prgn>install-info</prgn>.</p>
1039 Errors which occur during the execution of an installation
1040 script must be checked and the installation must not
1041 continue after an error.
1045 Note that in general <ref id="scripts"> applies to package
1046 maintainer scripts, too.
1050 You should not use <tt>dpkg-divert</tt> on a file
1051 belonging to another package without consulting the
1052 maintainer of that package first.
1055 All packages which supply an instance of a common command
1056 name (or, in general, filename) should generally use
1057 <prgn>update-alternatives</prgn>, so that they may be
1058 installed together. If <prgn>update-alternatives</prgn>
1059 is not used, then each package must use
1060 <var>Conflicts</var> to ensure that other packages are
1061 de-installed. (In this case, it may be appropriate to
1062 specify a conflict against earlier versions of something
1063 that previously did not use
1064 <prgn>update-alternatives</prgn> - this is an exception to
1065 the usual rule that versioned conflicts should be
1071 <heading>Prompting in maintainer scripts</heading>
1073 Package maintainer scripts may prompt the user if
1074 necessary. Prompting may be accomplished by hand, or by
1075 communicating with a program, such as
1076 <prgn>debconf</prgn>, which conforms to the Debian
1077 Configuration management specification, version 2 or
1078 higher. These are included in the
1079 <file>debconf_specification</file> files in the
1080 <package>debian-policy</package> package.
1081 You may also find this file on the FTP site
1082 <ftpsite>ftp.debian.org</ftpsite> in
1083 <ftppath>/debian/doc/package-developer/debconf_specification.txt.gz</ftppath>
1084 or on your local mirror.
1087 2.5% of Debian packages [see <url
1088 id="http://kitenet.net/programs/debconf/stats/">]
1089 currently use <package>debconf</package> to prompt
1090 the user at install time, and this number is growing
1091 daily. The benefits of using debconf are briefly
1093 id="http://kitenet.net/doc/debconf-doc/introduction.html">;
1094 they include preconfiguration, (mostly)
1095 noninteractive installation, elimination of
1096 redundant prompting, consistency of user interface,
1100 With this increasing number of packages using
1101 <package>debconf</package>, plus the existance of a
1102 nascent second implementation of the Debian
1103 configuration management system
1104 (<package>cdebconf</package>), and the stabalization
1105 of the protocol these things use, the time has
1106 finally come to reflect the use of these things in
1113 Packages which use the Debian Configuration management
1114 specification may contain an additional
1115 <file>config</file> script and a <file>templates</file>
1116 file in their control archive. The <prgn>config</prgn>
1117 script might be run before the <prgn>preinst</prgn>
1118 script, and before the package is unpacked or any of its
1119 dependancies or pre-dependancies are satisfied.
1120 Therefore it must work using only the tools present in
1121 <em>essential</em> packages.
1124 <package>Debconf</package> or another tool that
1125 implements the Debian Configuration management
1126 specification will also be installed, and any
1127 versioned dependencies on it will be satisfied
1128 before preconfiguration begins.
1134 Packages should try to minimize the amount of prompting
1135 they need to do, and they should ensure that the user
1136 will only ever be asked each question once. This means
1137 that packages should try to use appropriate shared
1138 configuration files (such as <tt>/etc/papersize</tt> and
1139 <tt>/etc/news/server</tt>), and shared
1140 <package>debconf</package> variables rather than each
1141 prompting for their own list of required pieces of
1146 It also means that an upgrade should not ask the same
1147 questions again, unless the user has used <tt>dpkg
1148 --purge</tt> to remove the package's configuration. The
1149 answers to configuration questions should be stored in an
1150 appropriate place in <tt>/etc</tt> so that the user can
1151 modify them, and how this has been done should be
1155 If a package has a vitally important piece of
1156 information to pass to the user (such as "don't run me
1157 as I am, you must edit the following configuration files
1158 first or you risk your system emitting badly-formatted
1159 messages"), it should display this in the
1160 <prgn>config</prgn> or <prgn>postinst</prgn> script and
1161 prompt the user to hit return to acknowledge the
1162 message. Copyright messages do not count as vitally
1163 important (they belong in
1164 <tt>/usr/share/doc/<var>package</var>/copyright</tt>);
1165 neither do instructions on how to use a program (these
1166 should be in on-line documentation, where all the users
1170 Any necessary prompting should almost always be confined
1171 to the <prgn>config</prgn> or <prgn>postinst</prgn>
1172 script. If it is done in the <prgn>postinst</prgn>, it
1173 should be protected with a conditional so that unnecessary
1174 prompting doesn't happen if a package's installation fails
1175 and the <prgn>postinst</prgn> is called with
1176 <tt>abort-upgrade</tt>, <tt>abort-remove</tt> or
1177 <tt>abort-deconfigure</tt>.</p>
1182 <heading>Source packages</heading>
1185 <heading>Standards conformance</heading>
1186 <sect id="standardsversion">
1189 In the source package's <tt>Standards-Version</tt> control
1190 field, you must specify the most recent version number of
1191 this policy document with which your package complies.
1192 The current version number is &version;.
1196 This information may be used to file bug reports
1197 automatically if your package becomes too much out of
1202 The version number has four components--major and minor
1203 version number and major and minor patch level. When the
1204 standards change in a way that requires every package to
1205 change the major number will be changed. Significant
1206 changes that will require work in many packages will be
1207 signaled by a change to the minor number. The major patch
1208 level will be changed for any change to the meaning of the
1209 standards, however small; the minor patch level will be
1210 changed when only cosmetic, typographical or other edits
1211 are made which neither change the meaning of the document
1212 nor affect the contents of packages.</p>
1215 Thus only the first three components of the policy version
1216 are significant in the <em>Standards-Version</em> control
1217 field, and so either these three components or the all
1218 four components may be specified.
1221 In the past, people specified the full version number
1222 in the Standards-Version field, for example `2.3.0.0'.
1223 Since minor patch-level changes don't introduce new
1224 policy, it was thought it would be better to relax
1225 policy and only require the first 3 components to be
1226 specified, in this example `2.3.0'. All four
1227 components may still be used if someone wishes to do
1234 You should regularly, and especially if your package has
1235 become out of date, check for the newest Policy Manual
1236 available and update your package, if necessary. When your
1237 package complies with the new standards you should update the
1238 <tt>Standards-Version</tt> source package field and
1242 See the file <tt>upgrading-checklist</tt> for
1243 information about policy which has changed between
1244 different versions of this document.
1252 <heading>Package relationships</heading>
1255 Source packages should specify which binary packages they
1256 require to be installed or not to be installed in order to
1257 build correctly. For example, if building a package
1258 requires a certain compiler, then the compiler should be
1259 specified as a build-time dependency.
1263 It is not necessary to explicitly specify build-time
1264 relationships on a minimal set of packages that are always
1265 needed to compile, link and put in a Debian package a
1266 standard "Hello World!" program written in C or C++. The
1267 required packages are called <em>build-essential</em>, and
1268 an informational list can be found in
1269 <tt>/usr/share/doc/build-essential/list</tt> (which is
1270 contained in the <tt>build-essential</tt>
1276 <p>This allows maintaining the list separately
1277 from the policy documents (the list does not
1278 need the kind of control that the policy
1284 Having a separate package allows one to install
1285 the build-essential packages on a machine, as
1286 well as allowing other packages such as task
1287 packages to require installation of the
1288 build-essential packages using the depends
1294 The separate package allows bug reports against
1295 the list to be categorized separately from
1296 the policy management process in the BTS.
1306 When specifying the set of build-time dependencies, one
1307 should list only those packages explicitly required by the
1308 build. It is not necessary to list packages which are
1309 required merely because some other package in the list of
1310 build-time dependencies depends on them.
1313 The reason for this is that dependencies change, and
1314 you should list all those packages, and <em>only</em>
1315 those packages that <em>you</em> need directly. What
1316 others need is their business. For example, if you
1317 only link against <tt>libimlib</tt>, you will need to
1318 build-depend on <package>libimlib2-dev</package> but
1319 not against any <tt>libjpeg*</tt> packages, even
1320 though <tt>libimlib2-dev</tt> currently depends on
1321 them: installation of <package>libimlib2-dev</package>
1322 will automatically ensure that all of its run-time
1323 dependencies are satisfied.
1329 If build-time dependencies are specified, it must be
1330 possible to build the package and produce working binaries
1331 on a system with only essential and build-essential
1332 packages installed and also those required to satisfy the
1333 build-time relationships (including any implied
1334 relationships). In particular, this means that version
1335 clauses should be used rigorously in build-time
1336 relationships so that one cannot produce bad or
1337 inconsistently configured packages when the relationships
1338 are properly satisfied.
1342 <heading>Changes to the upstream sources</heading>
1345 If changes to the source code are made that are not
1346 specific to the needs of the Debian system, they should be
1347 sent to the upstream authors in whatever form they prefer
1348 so as to be included in the upstream version of the
1352 If you need to configure the package differently for
1353 Debian or for Linux, and the upstream source doesn't
1354 provide a way to do so, you should add such configuration
1355 facilities (for example, a new <prgn>autoconf</prgn> test
1356 or <tt>#define</tt>) and send the patch to the upstream
1357 authors, with the default set to the way they originally
1358 had it. You can then easily override the default in your
1359 <tt>debian/rules</tt> or wherever is appropriate.</p>
1362 You should make sure that the <prgn>configure</prgn> utility
1363 detects the correct architecture specification string
1364 (refer to <ref id="arch-spec"> for details).</p>
1367 If you need to edit a <prgn>Makefile</prgn> where
1368 GNU-style <prgn>configure</prgn> scripts are used, you
1369 should edit the <tt>.in</tt> files rather than editing the
1370 <prgn>Makefile</prgn> directly. This allows the user to
1371 reconfigure the package if necessary. You should
1372 <em>not</em> configure the package and edit the generated
1373 <prgn>Makefile</prgn>! This makes it impossible for
1374 someone else to later reconfigure the package.</p></sect1>
1378 <heading>Documenting your changes</heading>
1381 You should document your changes and updates to the source
1382 package properly in the <tt>debian/changelog</tt> file. (Note
1383 that mistakes in changelogs are usually best rectified by
1384 making a new changelog entry rather than "rewriting history"
1385 by editing old changelog entries.)</p>
1388 In non-experimental packages you must use a format for
1389 <tt>debian/changelog</tt> which is supported by the most
1390 recent released version of <prgn>dpkg</prgn>.
1393 If you wish to use an alternative format, you may do
1394 so as long as you include a parser for it in your
1395 source package. The parser must have an API
1396 compatible with that expected by
1397 <prgn>dpkg-genchanges</prgn> and
1398 <prgn>dpkg-gencontrol</prgn>. If there is general
1399 interest in the new format, you should contact the
1400 <package>dpkg</package> maintainer to have the parser
1401 script for it included in the <prgn>dpkg</prgn>
1402 package. (You will need to agree that the parser and
1403 its manpage may be distributed under the GNU GPL, just
1404 as the rest of `dpkg' is.)
1412 <heading>Error trapping in makefiles</heading>
1415 When <prgn>make</prgn> invokes a command in a makefile
1416 (including your package's upstream makefiles and
1417 <tt>debian/rules</tt>), it does so using <tt>sh</tt>. This
1418 means that <tt>sh</tt>'s usual bad error handling
1419 properties apply: if you include a miniature script as one
1420 of the commands in your makefile you'll find that if you
1421 don't do anything about it then errors are not detected
1422 and <prgn>make</prgn> will blithely continue after
1426 Every time you put more than one shell command (this
1427 includes using a loop) in a makefile command you
1428 must make sure that errors are trapped. For
1429 simple compound commands, such as changing directory and
1430 then running a program, using <tt>&&</tt> rather
1431 than semicolon as a command separator is sufficient. For
1432 more complex commands including most loops and
1433 conditionals you should include a separate <tt>set -e</tt>
1434 command at the start of every makefile command that's
1435 actually one of these miniature shell scripts.</p></sect1>
1439 <heading>Obsolete constructs and libraries</heading>
1442 The include file <prgn><varargs.h></prgn> is
1443 provided to support end-users compiling very old software;
1444 the library <tt>libtermcap</tt> is provided to support the
1445 execution of software which has been linked against it
1446 (either old programs or those such as Netscape which are
1447 only available in binary form).</p>
1450 Debian packages should be patched to use
1451 <prgn><stdarg.h></prgn> and <tt>ncurses</tt>
1458 <chapt id="controlfields"><heading>Control files and their fields</heading>
1461 Many of the tools in the package management suite manipulate
1462 data represented in a common format, known as <em>control
1463 data</em>. The data is often stored in <em>control
1464 files</em>. Binary and source packages have control files,
1465 and the <tt>.changes</tt> files which control the installation
1466 of uploaded files are also in control file format.
1467 <prgn>Dpkg</prgn>'s internal databases are in a similar
1471 <sect><heading>Syntax of control files</heading>
1474 A control file consists of one or more paragraphs of fields.
1475 The paragraphs are separated by blank lines. Some control
1476 files allow only one paragraph; others allow several, in
1477 which case each paragraph usually refers to a different
1478 package. (For example, in source packages, the first
1479 paragraph refers to the source package, and later paragraphs
1480 refer to binary packages generated from the source.)
1484 Each paragraph consists of a series of data fields; each
1485 field consists of the field name, followed by a colon and
1486 then the data/value associated with that field. It ends at
1487 the end of the line. Horizontal whitespace (spaces and
1488 tabs) may occur immediately before or after the value and is
1489 ignored there; it is conventional to put a single space
1490 after the colon. For example, a field might be:
1494 the field name is <tt>Package</tt> and the field value
1499 Some fields' values may span several lines; in this case
1500 each continuation line <em>must</em> start with a space or
1501 tab. Any trailing spaces or tabs at the end of individual
1502 lines of a field value are ignored.
1506 Except where otherwise stated only a single line of data is
1507 allowed and whitespace is not significant in a field body.
1508 Whitespace must not appear inside names (of packages,
1509 architectures, files or anything else) or version numbers,
1510 or between the characters of multi-character version
1515 Field names are not case-sensitive, but it is usual to
1516 capitalize the field names using mixed case as shown below.
1520 Blank lines, or lines consisting only of spaces and tabs,
1521 are not allowed within field values or between fields - that
1522 would mean a new paragraph.
1527 <sect><heading>List of fields</heading>
1529 This list here is not supposed to be exhaustive. Most fields
1530 are dealt with elsewhere in this document.
1532 <sect1 id="f-Package"><heading><tt>Package</tt>
1536 The name of the binary package. Package names consist of
1537 the alphanumerics and <tt>+</tt> <tt>-</tt> <tt>.</tt>
1538 (plus, minus and full stop).
1542 They must be at least two characters long and must start
1543 with an alphanumeric character and not be all digits. The
1544 use of lowercase package names is strongly recommended
1545 unless the package you're building (or referring to, in
1546 other fields) is already using uppercase.</p>
1549 <sect1 id="f-Version"><heading><tt>Version</tt>
1553 This lists the source or binary package's version number -
1554 see <ref id="versions">.
1560 id="f-Standards-Version"><heading><tt>Standards-Version</tt>
1564 The most recent version of the standards (the policy
1565 manual and associated texts) with which the package
1566 complies. This is updated manually when editing the
1567 source package to conform to newer standards; it can
1568 sometimes be used to tell when a package needs attention.
1569 Its format is described above; see
1570 <ref id="standardsversion">.
1575 <sect1 id="f-Distribution"><heading><tt>Distribution</tt>
1579 In a <tt>.changes</tt> file or parsed changelog output
1580 this contains the (space-separated) name(s) of the
1581 distribution(s) where this version of the package should
1582 be installed. Valid distributions are determined by the
1583 archive maintainers.
1585 Current distribution names are:
1587 <tag><em>stable</em></tag>
1590 This is the current `released' version of Debian
1591 GNU/Linux. Once the distribution is
1592 <em>stable</em> only security fixes and other
1593 major bug fixes are allowed. When changes are
1594 made to this distribution, the release number is
1595 increased (for example: 2.2r1 becomes 2.2r2 then
1600 <tag><em>unstable</em></tag>
1603 This distribution value refers to the
1604 <em>developmental</em> part of the Debian
1605 distribution tree. New packages, new upstream
1606 versions of packages and bug fixes go into the
1607 <em>unstable</em> directory tree. Download from
1608 this distribution at your own risk.
1612 <tag><em>testing</em></tag>
1615 This distribution value refers to the
1616 <em>testing</em> part of the Debian distribution
1617 tree. It receives its packages from the
1618 unstable distribution after a short time lag to
1619 ensure that there are no major issues with the
1620 unstable packages. It is less prone to breakage
1621 than unstable, but still risky. It is not
1622 possible to upload packages directly to
1627 <tag><em>frozen</em></tag>
1630 From time to time, the <em>frozen</em>
1631 distribution enters a state of `code-freeze' in
1632 anticipation of release as a <em>stable</em>
1633 version. During this period of testing only
1634 fixes for existing or newly-discovered bugs will
1635 be allowed. The exact details of this stage are
1636 determined by the Release Manager.
1640 <tag><em>experimental</em></tag>
1643 The packages with this distribution value are
1644 deemed by their maintainers to be high
1645 risk. Oftentimes they represent early beta or
1646 developmental packages from various sources that
1647 the maintainers want people to try, but are not
1648 ready to be a part of the other parts of the
1649 Debian distribution tree. Download at your own
1655 You should list <em>all</em> distributions that the
1656 package should be installed into.
1665 <chapt id="versions"><heading>Version numbering </heading>
1668 Every package has a version number, in its <tt>Version</tt>
1673 The package management system imposes an ordering on version
1674 numbers, so that it can tell whether packages are being up- or
1675 downgraded and so that package system front end applications
1676 can tell whether a package it finds available is newer than
1677 the one installed on the system. The version number format
1678 has the most significant parts (as far as comparison is
1679 concerned) at the beginning.
1683 The version number format is:
1684 &lsqb<var>epoch</var><tt>:</tt>]<var>upstream-version</var>[<tt>-</tt><var>debian-revision</var>]
1688 The three components here are:
1690 <tag><var>epoch</var></tag>
1694 This is a single (generally small) unsigned integer. It
1695 may be omitted, in which case zero is assumed. If it is
1696 omitted then the <var>upstream-version</var> may not
1701 It is provided to allow mistakes in the version numbers
1702 of older versions of a package, and also a package's
1703 previous version numbering schemes, to be left behind.
1708 <tag><var>upstream-version</var></tag>
1712 This is the main part of the version. It is usually the
1713 version number of the original (`upstream') package from
1714 which the <tt>.deb</tt> file has been made, if this is
1715 applicable. Usually this will be in the same format as
1716 that specified by the upstream author(s); however, it
1717 may need to be reformatted to fit into the package
1718 management system's format and comparison scheme.
1722 The comparison behavior of the package management system
1723 with respect to the <var>upstream-version</var> is
1724 described below. The <var>upstream-version</var>
1725 portion of the version number is mandatory.
1729 The <var>upstream-version</var> may contain only
1730 alphanumerics and the characters <tt>.</tt> <tt>+</tt>
1731 <tt>-</tt> <tt>:</tt> (full stop, plus, hyphen, colon)
1732 and should start with a digit. If there is no
1733 <var>debian-revision</var> then hyphens are not allowed;
1734 if there is no <var>epoch</var> then colons are not
1738 <tag><var>debian-revision</var></tag>
1742 This part of the version represents the version of the
1743 modifications that were made to the package to make it a
1744 Debian binary package. It is in the same format as the
1745 <var>upstream-version</var> and is compared in the same
1750 It is optional; if it isn't present then the
1751 <var>upstream-version</var> may not contain a hyphen.
1752 This format represents the case where a piece of
1753 software was written specifically to be turned into a
1754 Debian binary package, and so there is only one
1755 `debianization' of it and therefore no revision
1756 indication is required.
1760 It is conventional to restart the
1761 <var>debian-revision</var> at <tt>1</tt> each time the
1762 <var>upstream-version</var> is increased.
1766 The package management system will break the
1767 <var>upstream-version</var> and
1768 <var>debian-revision</var> apart at the last hyphen in
1769 the string. The absence of a <var>debian-revision</var>
1770 compares earlier than the presence of one (but note that
1771 the <var>debian-revision</var> is the least significant
1772 part of the version number).
1776 The <var>debian-revision</var> may contain only
1777 alphanumerics and the characters <tt>+</tt> and
1778 <tt>.</tt> (plus and full stop).
1782 The <var>upstream-version</var> and <var>debian-revision</var>
1783 parts are compared by the package management system using the
1788 The strings are compared from left to right.
1792 First the initial part of each string consisting entirely of
1793 non-digit characters is determined. These two parts (one of
1794 which may be empty) are compared lexically. If a difference
1795 is found it is returned. The lexical comparison is a
1796 comparison of ASCII values modified so that all the letters
1797 sort earlier than all the non-letters.
1801 Then the initial part of the remainder of each string which
1802 consists entirely of digit characters is determined. The
1803 numerical values of these two parts are compared, and any
1804 difference found is returned as the result of the comparison.
1805 For these purposes an empty string (which can only occur at
1806 the end of one or both version strings being compared) counts
1811 These two steps are repeated (chopping initial non-digit
1812 strings and initial digit strings off from the start) until a
1813 difference is found or both strings are exhausted.
1817 Note that the purpose of epochs is to allow us to leave behind
1818 mistakes in version numbering, and to cope with situations
1819 where the version numbering changes. It is <em>not</em> there
1820 to cope with version numbers containing strings of letters
1821 which the package management system cannot interpret (such as
1822 <tt>ALPHA</tt> or <tt>pre-</tt>), or with silly orderings (the
1823 author of this manual has heard of a package whose versions
1824 went <tt>1.1</tt>, <tt>1.2</tt>, <tt>1.3</tt>, <tt>1</tt>,
1825 <tt>2.1</tt>, <tt>2.2</tt>, <tt>2</tt> and so forth).
1829 If an upstream package has problematic version numbers they
1830 should be converted to a sane form for use in the
1831 <tt>Version</tt> field.
1835 <heading>Version numbers based on dates</heading>
1837 In general, Debian packages should use the same version
1838 numbers as the upstream sources.</p>
1841 However, in some cases where the upstream version number is
1842 based on a date (e.g., a development `snapshot' release) the
1843 package management system cannot handle these version
1844 numbers without epochs. For example, dpkg will consider
1845 `96May01' to be greater than `96Dec24'.</p>
1848 To prevent having to use epochs for every new upstream
1849 version, the version number should be changed to the
1850 following format in such cases: `19960501', `19961224'. It
1851 is up to the maintainer whether he/she wants to bother the
1852 upstream maintainer to change the version numbers upstream,
1856 Note, that other version formats based on dates which are
1857 parsed correctly by the package management system should
1858 <em>not</em> be changed.</p>
1861 Native Debian packages (i.e., packages which have been
1862 written especially for Debian) whose version numbers include
1863 dates should always use the `YYYYMMDD' format.</p>
1867 <chapt id="miscellaneous"><heading>Packaging Considerations</heading>
1869 <sect id="timestamps"><heading>Time Stamps</heading>
1871 Maintainers are encouraged to preserve the modification
1872 times of the upstream source files in a package, as far as
1873 is reasonably possible. Even though this is optional, this
1874 is still a good idea.
1877 The rationale is that there is some information conveyed
1878 by knowing the age of the file, for example, you could
1879 recognize that some documentation is very old by looking
1880 at the modification time, so it would be nice if the
1881 modification time of the upstream source would be
1888 <sect id="debianrules"><heading><tt>debian/rules</tt> - the
1889 main building script </heading>
1892 This file must be an executable makefile, and contains the
1893 package-specific recipes for compiling the package and
1894 building binary package(s) out of the source.
1898 It must start with the line <tt>#!/usr/bin/make -f</tt>,
1899 so that it can be invoked by saying its name rather than
1900 invoking <prgn>make</prgn> explicitly.
1904 Since an interactive <tt>debian/rules</tt> script makes it
1905 impossible to auto-compile that package and also makes it
1906 hard for other people to reproduce the same binary
1907 package, all <strong>required targets</strong> MUST be
1908 non-interactive. At a minimum, required targets are the
1909 ones called by <prgn>dpkg-buildpackage</prgn>, namely,
1910 <em>clean</em>, <em>binary</em>, <em>binary-arch</em>,
1911 <em>binary-indep</em>, and <em>build</em>. It also follows
1912 that any target that these targets depend on must also be
1917 The targets which must be present are:
1919 <tag><tt>build</tt></tag>
1922 This should perform all non-interactive
1923 configuration and compilation of the package. If a
1924 package has an interactive pre-build configuration
1925 routine, the Debianised source package should be
1926 built after this has taken place, so that it can be
1927 built without rerunning the configuration.
1931 For some packages, notably ones where the same
1932 source tree is compiled in different ways to produce
1933 two binary packages, the <prgn>build</prgn> target
1934 does not make much sense. For these packages it is
1935 good enough to provide two (or more) targets
1936 (<tt>build-a</tt> and <tt>build-b</tt> or whatever)
1937 for each of the ways of building the package, and a
1938 <prgn>build</prgn> target that does nothing. The
1939 <prgn>binary</prgn> target will have to build the
1940 package in each of the possible ways and make the
1941 binary package out of each.
1945 The <prgn>build</prgn> target must not do anything
1946 that might require root privilege.
1950 The <prgn>build</prgn> target may need to run
1951 <prgn>clean</prgn> first - see below.
1955 When a package has a configuration routine that
1956 takes a long time, or when the makefiles are poorly
1957 designed, or when <prgn>build</prgn> needs to run
1958 <prgn>clean</prgn> first, it is a good idea to
1959 <tt>touch build</tt> when the build process is
1960 complete. This will ensure that if <tt>debian/rules
1961 build</tt> is run again it will not rebuild the
1966 <tag><tt>binary</tt>, <tt>binary-arch</tt>,
1967 <tt>binary-indep</tt>
1971 The <prgn>binary</prgn> target must be all that is
1972 necessary for the user to build the binary
1973 package. All these targets are required to be
1974 non-interactive. It is split into two parts:
1975 <prgn>binary-arch</prgn> builds the packages' output
1976 files which are specific to a particular
1977 architecture, and <prgn>binary-indep</prgn> builds
1978 those which are not.
1982 <prgn>binary</prgn> may be (and commonly is) a target
1983 with no commands which simply depends on
1984 <prgn>binary-arch</prgn> and
1985 <prgn>binary-indep</prgn>.
1989 Both <prgn>binary-*</prgn> targets should depend on
1990 the <prgn>build</prgn> target, above, so that the
1991 package is built if it has not been already. It
1992 should then create the relevant binary package(s),
1993 using <prgn>dpkg-gencontrol</prgn> to make their
1994 control files and <prgn>dpkg-deb</prgn> to build
1995 them and place them in the parent of the top level
2000 If one of the <prgn>binary-*</prgn> targets has
2001 nothing to do (this will be always be the case if
2002 the source generates only a single binary package,
2003 whether architecture-dependent or not) it
2004 <em>must</em> still exist, and must always
2009 The <prgn>binary</prgn> targets must be invoked as
2014 <tag><tt>clean</tt></tag>
2018 This must undo any effects that the
2019 <prgn>build</prgn> and <prgn>binary</prgn> targets
2020 may have had, except that it should leave alone any
2021 output files created in the parent directory by a
2022 run of <prgn>binary</prgn>. This target must be
2027 If a <prgn>build</prgn> file is touched at the end
2028 of the <prgn>build</prgn> target, as suggested
2029 above, it should be removed as the first thing that
2030 <prgn>clean</prgn> does, so that running
2031 <prgn>build</prgn> again after an interrupted
2032 <prgn>clean</prgn> doesn't think that everything is
2037 The <prgn>clean</prgn> target may need to be
2038 invoked as root if <prgn>binary</prgn> has been
2039 invoked since the last <prgn>clean</prgn>, or if
2040 <prgn>build</prgn> has been invoked as root (since
2041 <prgn>build</prgn> may create directories, for
2046 <tag><tt>get-orig-source</tt> (optional)</tag>
2050 This target fetches the most recent version of the
2051 original source package from a canonical archive site
2052 (via FTP or WWW, for example), does any necessary
2053 rearrangement to turn it into the original source
2054 tar file format described below, and leaves it in the
2059 This target may be invoked in any directory, and
2060 should take care to clean up any temporary files it
2065 This target is optional, but providing it if
2066 possible is a good idea.
2072 The <prgn>build</prgn>, <prgn>binary</prgn> and
2073 <prgn>clean</prgn> targets must be invoked with a current
2074 directory of the package's top-level directory.
2079 Additional targets may exist in <tt>debian/rules</tt>,
2080 either as published or undocumented interfaces or for the
2081 package's internal use.
2085 The architecture we build on and build for is determined by
2086 make variables via dpkg-architecture. You can get the Debian
2087 architecture and the GNU style architecture specification
2088 string for the build machine as well as the host
2089 machine. Here is a list of supported make variables:
2090 <list compact="compact">
2092 <p><tt>DEB_*_ARCH</tt> (the Debian architecture)</p>
2095 <p><tt>DEB_*_GNU_TYPE</tt> (the GNU style architecture
2096 specification string)</p>
2099 <p><tt>DEB_*_GNU_CPU</tt> (the CPU part of DEB_*_GNU_TYPE)</p>
2102 <p><tt>DEB_*_GNU_SYSTEM</tt> (the System part of
2108 where <tt>*</tt> is either <tt>BUILD</tt> for specification of
2109 the build machine or <tt>HOST</tt> for specification of the machine
2114 Backward compatibility can be provided in the rules file
2115 by setting the needed variables to suitable default
2116 values, please refer to the documentation of
2117 dpkg-architecture for details.
2121 It is important to understand that the <tt>DEB_*_ARCH</tt>
2122 string only determines which Debian architecture we are
2123 building on or for. It should not be used to get the CPU
2124 or system information; the GNU style variables should be
2129 <sect id="dpkgchangelog"><heading><tt>debian/changelog</tt>
2133 This file records the changes to the Debian-specific parts of the
2137 Though there is nothing stopping an author who is also
2138 the Debian maintainer from using it for all their
2139 changes, it will have to be renamed if the Debian and
2140 upstream maintainers become different
2147 It has a special format which allows the package building
2148 tools to discover which version of the package is being
2149 built and find out other release-specific information.
2153 That format is a series of entries like this:
2155 <var>package</var> (<var>version</var>) <var>distribution(s)</var>; urgency=<var>urgency</var>
2157 * <var>change details</var>
2158 <var>more change details</var>
2159 * <var>even more change details</var>
2161 -- <var>maintainer name and email address</var> <var>date</var>
2166 <var>package</var> and <var>version</var> are the source
2167 package name and version number.
2171 <var>distribution(s)</var> lists the distributions where
2172 this version should be installed when it is uploaded - it
2173 is copied to the <tt>Distribution</tt> field in the
2174 <tt>.changes</tt> file. See <ref id="f-Distribution">.
2178 <var>urgency</var> is the value for the <tt>Urgency</tt>
2179 field in the <tt>.changes</tt> file for the upload. It is
2180 not possible to specify an urgency containing commas; commas
2181 are used to separate
2182 <tt><var>keyword</var>=<var>value</var></tt> settings in the
2183 <prgn>dpkg</prgn> changelog format (though there is
2184 currently only one useful <var>keyword</var>,
2189 The change details may in fact be any series of lines
2190 starting with at least two spaces, but conventionally each
2191 change starts with an asterisk and a separating space and
2192 continuation lines are indented so as to bring them in
2193 line with the start of the text above. Blank lines may be
2194 used here to separate groups of changes, if desired.
2198 The maintainer name and email address need <em>not</em>
2199 necessarily be those of the usual package maintainer.
2200 They should be the details of the person doing
2201 <em>this</em> version. The information here will be
2202 copied to the <tt>.changes</tt> file, and then later used
2203 to send an acknowledgement when the upload has been
2208 The <var>date</var> should be in RFC822 format
2211 This is generated by the <prgn>822-date</prgn>
2214 </footnote>; it should include the time zone specified
2215 numerically, with the time zone name or abbreviation
2216 optionally present as a comment.
2220 The first `title' line with the package name should start
2221 at the left hand margin; the `trailer' line with the
2222 maintainer and date details should be preceded by exactly
2223 one space. The maintainer details and the date must be
2224 separated by exactly two spaces.
2227 <sect1><heading>Defining alternative changelog formats</heading>
2230 It is possible to use a different format to the standard
2231 one, by providing a parser for the format you wish to
2235 A changelog parser must not interact with the user at
2241 <sect id="srcsubstvars"><heading><tt>debian/substvars</tt>
2242 and variable substitutions </heading>
2245 When <prgn>dpkg-gencontrol</prgn>,
2246 <prgn>dpkg-genchanges</prgn> and <prgn>dpkg-source</prgn>
2247 generate control files they do variable substitutions on
2248 their output just before writing it. Variable
2249 substitutions have the form
2250 <tt>${<var>variable-name</var>}</tt>. The optional file
2251 <tt>debian/substvars</tt> contains variable substitutions
2252 to be used; variables can also be set directly from
2253 <tt>debian/rules</tt> using the <tt>-V</tt> option to the
2254 source packaging commands, and certain predefined
2255 variables are available.
2259 The is usually generated and modified dynamically by
2260 <tt>debian/rules</tt> targets; in this case it must be
2261 removed by the <prgn>clean</prgn> target.
2265 See <manref name="dpkg-source" section="1"> for full
2266 details about source variable substitutions, including the
2267 format of <tt>debian/substvars</tt>.</p>
2270 <sect id="debianfiles"><heading><tt>debian/files</tt>
2274 This file is not a permanent part of the source tree; it
2275 is used while building packages to record which files are
2276 being generated. <prgn>dpkg-genchanges</prgn> uses it
2277 when it generates a <tt>.changes</tt> file.
2281 It should not exist in a shipped source package, and so it
2282 (and any backup files or temporary files such as
2286 <tt>files.new</tt> is used as a temporary file by
2287 <prgn>dpkg-gencontrol</prgn> and
2288 <prgn>dpkg-distaddfile</prgn> - they write a new
2289 version of <tt>files</tt> here before renaming it,
2290 to avoid leaving a corrupted copy if an error
2293 </footnote>) should be removed by the
2294 <prgn>clean</prgn> target. It may also be wise to
2295 ensure a fresh start by emptying or removing it at the
2296 start of the <prgn>binary</prgn> target.
2300 <prgn>dpkg-gencontrol</prgn> adds an entry to this file
2301 for the <tt>.deb</tt> file that will be created by
2302 <prgn>dpkg-deb</prgn> from the control file that it
2303 generates, so for most packages all that needs to be done
2304 with this file is to delete it in <prgn>clean</prgn>.
2308 If a package upload includes files besides the source
2309 package and any binary packages whose control files were
2310 made with <prgn>dpkg-gencontrol</prgn> then they should be
2311 placed in the parent of the package's top-level directory
2312 and <prgn>dpkg-distaddfile</prgn> should be called to add
2313 the file to the list in <tt>debian/files</tt>.</p>
2316 <sect id="restrictions"><heading>Restrictions on objects in source packages
2320 The source package may not contain any hard links
2323 This is not currently detected when building source
2324 packages, but only when extracting
2330 Hard links may be permitted at some point in the
2331 future, but would require a fair amount of
2334 </footnote>, device special files, sockets or setuid or
2338 Setgid directories are allowed.
2343 <sect id="descriptions"><heading>Descriptions of packages - the
2344 <tt>Description</tt> field </heading>
2347 The description is intended to describe the program to a user
2348 who has never met it before so that they know whether they
2349 want to install it. It should also give information about the
2350 significant dependencies and conflicts between this package
2351 and others, so that the user knows why these dependencies and
2352 conflicts have been declared.
2355 <sect1><heading>Notes about writing descriptions
2359 The single line synopsis should be kept brief - certainly
2360 under 80 characters.
2364 Do not include the package name in the synopsis line. The
2365 display software knows how to display this already, and you
2366 do not need to state it. Remember that in many situations
2367 the user may only see the synopsis line - make it as
2368 informative as you can.
2372 Do not try to continue the single line synopsis into the
2373 extended description. This will not work correctly when
2374 the full description is displayed, and makes no sense
2375 where only the summary (the single line synopsis) is
2380 The extended description should describe what the package
2381 does and how it relates to the rest of the system (in terms
2382 of, for example, which subsystem it is which part of).
2386 The description field needs to make sense to anyone, even
2387 people who have no idea about any of the things the
2391 The blurb that comes with a program in its
2392 announcements and/or <prgn>README</prgn> files is
2393 rarely suitable for use in a description. It is
2394 usually aimed at people who are already in the
2395 community where the package is used.
2401 Put important information first, both in the synopsis and
2402 extended description. Sometimes only the first part of the
2403 synopsis or of the description will be displayed. You can
2404 assume that there will usually be a way to see the whole
2405 extended description.
2409 You may include information about dependencies and so forth
2410 in the extended description, if you wish.
2414 Do not use tab characters. Their effect is not predictable.
2422 <chapt id="maintainerscripts"><heading>Package maintainer scripts
2423 and installation procedure
2426 <sect><heading>Introduction to package maintainer scripts
2430 It is possible to supply scripts as part of a package which
2431 the package management system will run for you when your
2432 package is installed, upgraded or removed.
2436 These scripts should be the files <tt>preinst</tt>,
2437 <tt>postinst</tt>, <tt>prerm</tt> and <tt>postrm</tt> in the
2438 control area of the package. They must be proper executable
2439 files; if they are scripts (which is recommended) they must
2440 start with the usual <tt>#!</tt> convention. They should be
2441 readable and executable by anyone, and not world-writable.
2445 The package management system looks at the exit status from
2446 these scripts. It is important that they exit with a
2447 non-zero status if there is an error, so that the package
2448 management system can stop its processing. For shell
2449 scripts this means that you <em>almost always</em> need to
2450 use <tt>set -e</tt> (this is usually true when writing shell
2451 scripts, in fact). It is also important, of course, that
2452 they don't exit with a non-zero status if everything went
2457 It is necessary for the error recovery procedures that the
2458 scripts be idempotent: i.e., invoking the same script several
2459 times in the same situation should do no harm. If the first
2460 call failed, or aborted half way through for some reason,
2461 the second call should merely do the things that were left
2462 undone the first time, if any, and exit with a success
2467 When a package is upgraded a combination of the scripts from
2468 the old and new packages is called in amongst the other
2469 steps of the upgrade procedure. If your scripts are going
2470 to be at all complicated you need to be aware of this, and
2471 may need to check the arguments to your scripts.
2475 Broadly speaking the <prgn>preinst</prgn> is called before
2476 (a particular version of) a package is installed, and the
2477 <prgn>postinst</prgn> afterwards; the <prgn>prerm</prgn>
2478 before (a version of) a package is removed and the
2479 <prgn>postrm</prgn> afterwards.
2482 <p> Programs called from maintainer scripts should not
2483 normally have a path prepended to them. Before installation
2484 is started the package management system checks to see if
2485 the programs <prgn>ldconfig</prgn>,
2486 <prgn>start-stop-daemon</prgn>, <prgn>install-info</prgn>,
2487 and <prgn>update-rc.d</prgn> can be found via the
2488 <tt>PATH</tt> environment variable. Those programs, and any
2489 other program that one would expect to on the <tt>PATH</tt>,
2490 should thus be invoked without an absolute
2491 pathname. Maintainer scripts should also not reset the
2492 <tt>PATH</tt>, though they might choose to modify it by pre-
2493 or appending package-specific directories. These
2494 considerations really apply to all shell scripts.</p>
2497 <heading>Maintainer scripts Idempotency</heading>
2500 It is very important to make maintainer scripts
2504 That means that if it runs successfully or fails
2505 and then you call it again it doesn't bomb out,
2506 but just ensures that everything is the way it
2509 </footnote> This is so that if an error occurs, the
2510 user interrupts <prgn>dpkg</prgn> or some other
2511 unforeseen circumstance happens you don't leave the
2512 user with a badly-broken package.
2516 <heading>Controlling terminal for maintainer scripts</heading>
2519 The maintainer scripts are guaranteed to run with a
2520 controlling terminal and can interact with the user.
2521 If they need to prompt for passwords, do full-screen
2522 interaction or something similar you should do these
2523 things to and from <tt>/dev/tty</tt>, since
2524 <prgn>dpkg</prgn> will at some point redirect scripts'
2525 standard input and output so that it can log the
2526 installation process. Likewise, because these scripts
2527 may be executed with standard output redirected into a
2528 pipe for logging purposes, Perl scripts should set
2529 unbuffered output by setting <tt>$|=1</tt> so that the
2530 output is printed immediately rather than being
2535 Each script should return a zero exit status for
2536 success, or a nonzero one for failure.
2540 <sect id="mscriptsinstact"><heading>Summary of ways maintainer
2545 <list compact="compact">
2547 <p><var>new-preinst</var> <tt>install</tt></p>
2550 <p><var>new-preinst</var> <tt>install</tt>
2551 <var>old-version</var></p>
2554 <p><var>new-preinst</var> <tt>upgrade</tt>
2555 <var>old-version</var></p>
2558 <p><var>old-preinst</var> <tt>abort-upgrade</tt>
2559 <var>new-version</var>
2565 <list compact="compact">
2567 <p><var>postinst</var> <tt>configure</tt>
2568 <var>most-recently-configured-version</var></p>
2571 <p><var>old-postinst</var> <tt>abort-upgrade</tt>
2572 <var>new version</var></p>
2575 <p><var>conflictor's-postinst</var> <tt>abort-remove</tt>
2576 <tt>in-favour</tt> <var>package</var>
2577 <var>new-version</var></p>
2581 <var>deconfigured's-postinst</var>
2582 <tt>abort-deconfigure</tt> <tt>in-favour</tt>
2583 <var>failed-install-package</var> <var>version</var>
2584 <tt>removing</tt> <var>conflicting-package</var>
2591 <list compact="compact">
2593 <p><var>prerm</var> <tt>remove</tt></p>
2596 <p><var>old-prerm</var> <tt>upgrade</tt>
2597 <var>new-version</var></p>
2600 <p><var>new-prerm</var> <tt>failed-upgrade</tt>
2601 <var>old-version</var></p>
2604 <p><var>conflictor's-prerm</var> <tt>remove</tt>
2605 <tt>in-favour</tt> <var>package</var>
2606 <var>new-version</var></p>
2610 <var>deconfigured's-prerm</var> <tt>deconfigure</tt>
2611 <tt>in-favour</tt> <var>package-being-installed</var>
2612 <var>version</var> <tt>removing</tt>
2613 <var>conflicting-package</var>
2620 <list compact="compact">
2622 <p><var>postrm</var> <tt>remove</tt></p>
2625 <p><var>postrm</var> <tt>purge</tt></p>
2629 <var>old-postrm</var> <tt>upgrade</tt>
2630 <var>new-version</var></p>
2633 <p><var>new-postrm</var> <tt>failed-upgrade</tt>
2634 <var>old-version</var></p>
2637 <p><var>new-postrm</var> <tt>abort-install</tt></p>
2640 <p><var>new-postrm</var> <tt>abort-install</tt>
2641 <var>old-version</var></p>
2644 <p><var>new-postrm</var> <tt>abort-upgrade</tt>
2645 <var>old-version</var></p>
2649 <var>disappearer's-postrm</var> <tt>disappear</tt>
2650 <var>overwriter</var>
2651 <var>overwriter-version</var></p></item>
2656 <sect id="unpackphase"><heading>Details of unpack phase of
2657 installation or upgrade
2661 The procedure on installation/upgrade/overwrite/disappear
2662 (i.e., when running <tt>dpkg --unpack</tt>, or the unpack
2663 stage of <tt>dpkg --install</tt>) is as follows. In each
2664 case if an error occurs the actions are, in general, run
2665 backwards - this means that the maintainer scripts are run
2666 with different arguments in reverse order. These are the
2667 `error unwind' calls listed below.
2674 <p>If a version of the package is already
2677 <var>old-prerm</var> upgrade <var>new-version</var>
2682 If the script runs but exits with a non-zero
2683 exit status, <prgn>dpkg</prgn> will attempt:
2685 <var>new-prerm</var> failed-upgrade <var>old-version</var>
2687 Error unwind, for both the above cases:
2689 <var>old-postinst</var> abort-upgrade <var>new-version</var>
2697 <p>If a `conflicting' package is being removed at the same time:
2701 If any packages depended on that conflicting
2702 package and <tt>--auto-deconfigure</tt> is
2703 specified, call, for each such package:
2705 <var>deconfigured's-prerm</var> deconfigure \
2706 in-favour <var>package-being-installed</var> <var>version</var> \
2707 removing <var>conflicting-package</var> <var>version</var>
2711 <var>deconfigured's-postinst</var> abort-deconfigure \
2712 in-favour <var>package-being-installed-but-failed</var> <var>version</var> \
2713 removing <var>conflicting-package</var> <var>version</var>
2715 The deconfigured packages are marked as
2716 requiring configuration, so that if
2717 <tt>--install</tt> is used they will be
2718 configured again if possible.</p>
2721 <p>To prepare for removal of the conflicting package, call:
2723 <var>conflictor's-prerm</var> remove in-favour <var>package</var> <var>new-version</var>
2727 <var>conflictor's-postinst</var> abort-remove \
2728 in-favour <var>package</var> <var>new-version</var>
2739 <p>If the package is being upgraded, call:
2741 <var>new-preinst</var> upgrade <var>old-version</var>
2746 Otherwise, if the package had some configuration
2747 files from a previous version installed (i.e., it
2748 is in the `configuration files only' state):
2750 <var>new-preinst</var> install <var>old-version</var>
2754 <p>Otherwise (i.e., the package was completely purged):
2756 <var>new-preinst</var> install
2758 Error unwind versions, respectively:
2760 <var>new-postrm</var> abort-upgrade <var>old-version</var>
2761 <var>new-postrm</var> abort-install <var>old-version</var>
2762 <var>new-postrm</var> abort-install
2772 The new package's files are unpacked, overwriting any
2773 that may be on the system already, for example any
2774 from the old version of the same package or from
2775 another package (backups of the old files are left
2776 around, and if anything goes wrong the package
2777 management system will attempt to put them back as
2778 part of the error unwind).
2782 It is an error for a package to contains files which
2783 are on the system in another package, unless
2784 <tt>Replaces</tt> is used (see <ref id="replaces">).
2785 Currently the <tt>--force-overwrite</tt> flag is
2786 enabled, downgrading it to a warning, but this may not
2791 It is a more serious error for a package to contain a
2792 plain file or other kind of non-directory where another
2793 package has a directory (again, unless
2794 <tt>Replaces</tt> is used). This error can be
2795 overridden if desired using
2796 <tt>--force-overwrite-dir</tt>, but this is not
2801 Packages which overwrite each other's files produce
2802 behavior which though deterministic is hard for the
2803 system administrator to understand. It can easily
2804 lead to `missing' programs if, for example, a package
2805 is installed which overwrites a file from another
2806 package, and is then removed again.
2809 Part of the problem is due to what is arguably a
2810 bug in <prgn>dpkg</prgn>.
2816 A directory will never be replaced by a symbolic links
2817 to a directory or vice versa; instead, the existing
2818 state (symlink or not) will be left alone and
2819 <prgn>dpkg</prgn> will follow the symlink if there is
2827 <p>If the package is being upgraded, call
2829 <var>old-postrm</var> upgrade <var>new-version</var>
2833 <p>If this fails, <prgn>dpkg</prgn> will attempt:
2835 <var>new-postrm</var> failed-upgrade <var>old-version</var>
2837 Error unwind, for both cases:
2839 <var>old-preinst</var> abort-upgrade <var>new-version</var>
2845 This is the point of no return - if
2846 <prgn>dpkg</prgn> gets this far, it won't back off
2847 past this point if an error occurs. This will
2848 leave the package in a fairly bad state, which
2849 will require a successful re-installation to clear
2850 up, but it's when <prgn>dpkg</prgn> starts doing
2851 things that are irreversible.
2856 Any files which were in the old version of the package
2857 but not in the new are removed.</p>
2860 <p>The new file list replaces the old.</p>
2863 <p>The new maintainer scripts replace the old.</p>
2867 <p>Any packages all of whose files have been overwritten during the
2868 installation, and which aren't required for
2869 dependencies, are considered to have been removed.
2870 For each such package,
2873 <p><prgn>dpkg</prgn> calls:
2875 <var>disappearer's-postrm</var> disappear \
2876 <var>overwriter</var> <var>overwriter-version</var>
2881 <p>The package's maintainer scripts are removed.
2886 It is noted in the status database as being in a
2887 sane state, namely not installed (any conffiles
2888 it may have are ignored, rather than being
2889 removed by <prgn>dpkg</prgn>). Note that
2890 disappearing packages do not have their prerm
2891 called, because <prgn>dpkg</prgn> doesn't know
2892 in advance that the package is going to
2901 Any files in the package we're unpacking that are also
2902 listed in the file lists of other packages are removed
2903 from those lists. (This will lobotomize the file list
2904 of the `conflicting' package if there is one.)
2909 The backup files made during installation, above, are
2916 The new package's status is now sane, and recorded as
2917 `unpacked'. Here is another point of no return - if
2918 the conflicting package's removal fails we do not
2919 unwind the rest of the installation; the conflicting
2920 package is left in a half-removed limbo.
2925 If there was a conflicting package we go and do the
2926 removal actions (described below), starting with the
2927 removal of the conflicting package's files (any that
2928 are also in the package being installed have already
2929 been removed from the conflicting package's file list,
2930 and so do not get removed now).
2937 <sect><heading>Details of configuration</heading>
2940 When we configure a package (this happens with <tt>dpkg
2941 --install</tt>, or with <tt>--configure</tt>), we first
2942 update the conffiles and then call:
2944 <var>postinst</var> configure <var>most-recently-configured-version</var>
2949 No attempt is made to unwind after errors during
2954 If there is no most recently configured version
2955 <prgn>dpkg</prgn> will pass a null argument; older versions
2956 of dpkg may pass <tt><unknown></tt> (including the
2957 angle brackets) in this case. Even older ones do not pass a
2958 second argument at all, under any circumstances.
2962 <sect><heading>Details of removal and/or configuration purging
2970 <var>prerm</var> remove
2976 The package's files are removed (except conffiles).
2981 <var>postrm</var> remove
2985 <p>All the maintainer scripts except the postrm are removed.
2989 If we aren't purging the package we stop here. Note
2990 that packages which have no postrm and no conffiles
2991 are automatically purged when removed, as there is no
2992 difference except for the <prgn>dpkg</prgn>
2997 The conffiles and any backup files (<tt>~</tt>-files,
2998 <tt>#*#</tt> files, <tt>%</tt>-files,
2999 <tt>.dpkg-{old,new,tmp}</tt>, etc.) are removed.</p>
3003 <var>postrm</var> purge
3007 <p>The package's file list is removed.</p>
3010 No attempt is made to unwind after errors during
3016 <chapt id="relationships"><heading>Declaring relationships between
3020 Packages can declare in their control file that they have
3021 certain relationships to other packages - for example, that
3022 they may not be installed at the same time as certain other
3023 packages, and/or that they depend on the presence of others,
3024 or that they should overwrite files in certain other packages
3029 This is done using the <tt>Depends</tt>, <tt>Recommends</tt>,
3030 <tt>Suggests</tt>, <tt>Enhances</tt>, <tt>Conflicts</tt>,
3031 <tt>Provides</tt> and <tt>Replaces</tt> control file fields.
3035 Source packages may declare relationships to binary packages,
3036 saying that they require certain binary packages to be
3037 installed or absent at the time of building the package.
3041 This is done using the <tt>Build-Depends</tt>,
3042 <tt>Build-Depends-Indep</tt>, <tt>Build-Conflicts</tt>, and
3043 <tt>Build-Conflicts-Indep</tt> control file fields.
3046 <sect id="depsyntax"><heading>Syntax of relationship fields
3050 These fields all have a uniform syntax. They are a list of
3051 package names separated by commas.
3055 In the <tt>Depends</tt>, <tt>Recommends</tt>,
3056 <tt>Suggests</tt>, <tt>Pre-Depends</tt>,
3057 <tt>Build-Depends</tt> and <tt>Build-Depends-Indep</tt>
3058 control file fields of the package, which declare
3059 dependencies on other packages, the package names listed may
3060 also include lists of alternative package names, separated
3061 by vertical bar symbols <tt>|</tt> (pipe symbols). In such
3062 a case, the presence of any one of the alternative packages
3063 is installed, that part of the dependency is considered to
3068 All the fields except <tt>Provides</tt> may restrict their
3069 applicability to particular versions of each named package.
3070 This is done in parentheses after each individual package
3071 name; the parentheses should contain a relation from the
3072 list below followed by a version number, in the format
3073 described in <ref id="versions">.
3077 The relations allowed are <tt><<</tt>, <tt><=</tt>,
3078 <tt>=</tt>, <tt>>=</tt> and <tt>>></tt> for
3079 strictly earlier, earlier or equal, exactly equal, later or
3080 equal and strictly later, respectively. The forms
3081 <tt><</tt> and <tt>></tt> were used to mean
3082 earlier/later or equal, rather than strictly earlier/later,
3083 so they should not appear in new packages (though
3084 <prgn>dpkg</prgn> still supports them).
3088 Whitespace may appear at any point in the version
3089 specification, and must appear where it's necessary to
3090 disambiguate; it is not otherwise significant. For
3091 consistency and in case of future changes to
3092 <prgn>dpkg</prgn> it is recommended that a single space be
3093 used after a version relationship and before a version
3094 number; it is usual also to put a single space after each
3095 comma, on either side of each vertical bar, and before each
3104 Depends: libc5 (>= 5.2.18-4), mime-support, csh | tcsh
3109 All fields that specify build-time relationships
3110 (<tt>Build-Depends</tt>, <tt>Build-Depends-Indep</tt>,
3111 <tt>Build-Conflicts</tt> and <tt>Build-Conflicts-Indep</tt>)
3112 may be restricted to a certain set of architectures. This
3113 is done in brackets after each individual package name and
3114 the optional version specification. The brackets enclose a
3115 list of Debian architecture names separated by whitespace.
3116 Exclamation marks may be prepended to each of the names.
3117 (It is not permitted for some names to be prepended with
3118 exclamation marks and others not.) If the current Debian
3119 host architecture is not in this list and there are no
3120 exclamation marks in the list, or it is in the list with a
3121 prepended exclamation mark, the package name and the
3122 associated version specification are ignored completely for
3123 the purposes of defining the relationships.
3130 Build-Depends-Indep: texinfo
3131 Build-Depends: kernel-headers-2.2.10 [!hurd-i386],
3132 hurd-dev [hurd-i386], gnumach-dev [hurd-i386]
3138 <heading>Binary Dependencies - <tt>Depends</tt>,
3139 <tt>Recommends</tt>, <tt>Suggests</tt>, <tt>Enhances</tt>,
3140 <tt>Pre-Depends</tt>
3144 These five fields are used to declare a dependency
3145 relationship by one package on another. They appear in the
3146 depending package's control file.
3150 All but <tt>Pre-Depends</tt> and <tt>Conflicts</tt>
3151 (discussed below) take effect <em>only</em> when a package
3152 is to be configured. They do not prevent a package being on
3153 the system in an unconfigured state while its dependencies
3154 are unsatisfied, and it is possible to replace a package
3155 whose dependencies are satisfied and which is properly
3156 installed with a different version whose dependencies are
3157 not and cannot be satisfied; when this is done the depending
3158 package will be left unconfigured (since attempts to
3159 configure it will give errors) and will not function
3164 For this reason packages in an installation run are usually
3165 all unpacked first and all configured later; this gives
3166 later versions of packages with dependencies on later
3167 versions of other packages the opportunity to have their
3168 dependencies satisfied.
3172 Thus <tt>Depends</tt> allows package maintainers to impose
3173 an order in which packages should be configured.
3175 <tag><tt>Depends</tt></tag>
3178 <p>This declares an absolute dependency.
3182 The <tt>Depends</tt> field should be used if the
3183 depended-on package is required for the depending
3184 package to provide a significant amount of
3188 <tag><tt>Recommends</tt></tag>
3190 <p>This declares a strong, but not absolute, dependency.
3194 The <tt>Recommends</tt> field should list packages
3195 that would be found together with this one in all but
3196 unusual installations.</p>
3199 <tag><tt>Suggests</tt></tag>
3203 This is used to declare that one package may be more
3204 useful with one or more others. Using this field
3205 tells the packaging system and the user that the
3206 listed packages are related to this one and can
3207 perhaps enhance its usefulness, but that installing
3208 this one without them is perfectly reasonable.
3212 <tag><tt>Enhances</tt></tag>
3215 This field is similar to Suggests but works in the
3216 opposite direction. It is used to declare that a
3217 package can enhance the functionality of another
3222 <tag><tt>Pre-Depends</tt></tag>
3226 This field is like <tt>Depends</tt>, except that it
3227 also forces <prgn>dpkg</prgn> to complete installation
3228 of the packages named before even starting the
3229 installation of the package which declares the
3234 <tt>Pre-Depends</tt> should be used sparingly,
3235 preferably only by packages whose premature upgrade or
3236 installation would hamper the ability of the system to
3237 continue with any upgrade that might be in progress.
3241 When the package declaring it is being configured, a
3242 <tt>Pre-Dependency</tt> will be considered satisfied
3243 only if the depending package has been correctly
3244 configured, just as if an ordinary <tt>Depends</tt>
3249 However, when a package declaring a Pre-dependency is
3250 being unpacked the predependency can be satisfied even
3251 if the depended-on package(s) are only unpacked or
3252 half-configured, provided that they have been
3253 configured correctly at some point in the past (and
3254 not removed or partially removed since). In this case
3255 both the previously-configured and currently unpacked
3256 or half-configured versions must satisfy any version
3257 clause in the <tt>Pre-Depends</tt> field.
3263 When selecting which level of dependency to use you should
3264 consider how important the depended-on package is to the
3265 functionality of the one declaring the dependency. Some
3266 packages are composed of components of varying degrees of
3267 importance. Such a package should list using
3268 <tt>Depends</tt> the package(s) which are required by the
3269 more important components. The other components'
3270 requirements may be mentioned as Suggestions or
3271 Recommendations, as appropriate to the components' relative
3276 <sect id="conflicts"><heading>Alternative binary packages -
3277 <tt>Conflicts</tt> and <tt>Replaces</tt>
3281 When one binary package declares a conflict with another
3282 <prgn>dpkg</prgn> will refuse to allow them to be installed
3283 on the system at the same time.
3287 If one package is to be installed, the other must be removed
3288 first - if the package being installed is marked as
3289 replacing (<ref id="replaces">) the one on the system, or
3290 the one on the system is marked as deselected, or both
3291 packages are marked <tt>Essential</tt>, then
3292 <prgn>dpkg</prgn> will automatically remove the package
3293 which is causing the conflict, otherwise it will halt the
3294 installation of the new package with an error. This
3295 mechanism specifically doesn't work when the installed
3296 package is <tt>Essential</tt>, but the new package is not.
3301 A package will not cause a conflict merely because its
3302 configuration files are still installed; it must be at least
3307 A special exception is made for packages which declare a
3308 conflict with their own package name, or with a virtual
3309 package which they provide (see below): this does not
3310 prevent their installation, and allows a package to conflict
3311 with others providing a replacement for it. You use this
3312 feature when you want the package in question to be the only
3313 package providing something.
3317 A <tt>Conflicts</tt> entry should almost never have an
3318 `earlier than' version clause. This would prevent
3319 <prgn>dpkg</prgn> from upgrading or installing the package
3320 which declared such a conflict until the upgrade or removal
3321 of the conflicted-with package had been completed.
3325 <sect id="virtual"><heading>Virtual packages - <tt>Provides</tt>
3329 As well as the names of actual (`concrete') packages, the
3330 package relationship fields <tt>Depends</tt>,
3331 <tt>Build-Depends</tt>, <tt>Build-Depends-Indep</tt>,
3332 <tt>Recommends</tt>, <tt>Suggests</tt>, <tt>Conflicts</tt>,
3333 <tt>Build-Conflicts</tt> and <tt>Build-Conflicts-Indep</tt> may
3334 mention virtual packages.
3338 A virtual package is one which appears in the
3339 <tt>Provides</tt> control file field of another package.
3340 The effect is as if the package(s) which provide a
3341 particular virtual package name had been listed by name
3342 everywhere the virtual package name appears.
3346 If there are both a real and a virtual package of the same
3347 name then the dependency may be satisfied (or the conflict
3348 caused) by either the real package or any of the virtual
3349 packages which provide it. This is so that, for example,
3355 and someone else releases an xemacs package they can say
3359 </example> and all will work in the interim (until a purely
3360 virtual package name is decided on and the <tt>emacs</tt>
3361 and <tt>vm</tt> packages are changed to use it).
3365 If a dependency or a conflict has a version number attached
3366 then only real packages will be considered to see whether
3367 the relationship is satisfied (or the prohibition violated,
3368 for a conflict) - it is assumed that a real package which
3369 provides the virtual package is not of the `right' version.
3370 So, a <tt>Provides</tt> field may not contain version
3371 numbers, and the version number of the concrete package
3372 which provides a particular virtual package will not be
3373 looked at when considering a dependency on or conflict with
3374 the virtual package name.
3378 It is likely that the ability will be added in a future
3379 release of <prgn>dpkg</prgn> to specify a version number for
3380 each virtual package it provides. This feature is not yet
3381 present, however, and is expected to be used only
3386 If you want to specify which of a set of real packages should be the
3387 default to satisfy a particular dependency on a virtual package, you
3388 should list the real package as an alternative before the virtual.
3393 <sect id="replaces"><heading><tt>Replaces</tt> - overwriting
3394 files and replacing packages
3398 The <tt>Replaces</tt> control file field has two purposes,
3399 which come into play in different situations.
3403 Virtual packages (<ref id="virtual">) are not considered
3404 when looking at a <tt>Replaces</tt> field - the packages
3405 declared as being replaced must be mentioned by their real
3409 <sect1><heading>Overwriting files in other packages
3413 Firstly, as mentioned before, it is usually an error for a
3414 package to contain files which are on the system in
3415 another package, though currently the
3416 <tt>--force-overwrite</tt> flag is enabled by default,
3417 downgrading the error to a warning,
3421 If the overwriting package declares that it replaces the
3422 one containing the file being overwritten then
3423 <prgn>dpkg</prgn> will proceed, and replace the file from
3424 the old package with that from the new. The file will no
3425 longer be listed as `owned' by the old package.
3429 If a package is completely replaced in this way, so that
3430 <prgn>dpkg</prgn> does not know of any files it still
3431 contains, it is considered to have disappeared. It will
3432 be marked as not wanted on the system (selected for
3433 removal) and not installed. Any conffiles details noted
3434 in the package will be ignored, as they will have been
3435 taken over by the replacing package(s). The package's
3436 <prgn>postrm</prgn> script will be run to allow the
3437 package to do any final cleanup required. See <ref
3438 id="mscriptsinstact">.
3442 In the future <prgn>dpkg</prgn> will discard files which
3443 would overwrite those from an already installed package
3444 which declares that it replaces the package being
3445 installed. This is so that you can install an older
3446 version of a package without problems.
3450 This usage of <tt>Replaces</tt> only takes effect when
3451 both packages are at least partially on the system at
3452 once, so that it can only happen if they do not conflict
3453 or if the conflict has been overridden.</p>
3456 <sect1><heading>Replacing whole packages, forcing their
3461 Secondly, <tt>Replaces</tt> allows the packaging system to
3462 resolve which package should be removed when there is a
3463 conflict - see <ref id="conflicts">. This usage only
3464 takes effect when the two packages <em>do</em> conflict,
3465 so that the two effects do not interfere with each other.
3470 <sect><heading>Relationships between source and binary packages -
3471 <tt>Build-Depends</tt>, <tt>Build-Depends-Indep</tt>,
3472 <tt>Build-Conflicts</tt>, <tt>Build-Conflicts-Indep</tt>
3476 A source package may declare a dependency or a conflict on a
3477 binary package. This is done with the control file fields
3478 <tt>Build-Depends</tt>, <tt>Build-Depends-Indep</tt>,
3479 <tt>Build-Conflicts</tt>, and
3480 <tt>Build-Conflicts-Indep</tt>. Their semantics are that
3481 the dependencies and conflicts they define must be satisfied
3482 (as defined earlier for binary packages), when one of the
3483 targets in <tt>debian/rules</tt> that the particular field
3484 applies to is invoked.
3487 <tag><tt>Build-Depends</tt>, <tt>Build-Conflicts</tt></tag>
3490 The <tt>Build-Depends</tt> and
3491 <tt>Build-Conflicts</tt> fields apply to the targets
3492 <tt>build</tt>, <tt>binary</tt>, <tt>binary-arch</tt>
3493 and <tt>binary-indep</tt>.
3496 <tag><tt>Build-Depends-Indep</tt>, <tt>Build-Conflicts-Indep</tt></tag>
3499 The <tt>Build-Depends-Indep</tt> and
3500 <tt>Build-Conflicts-Indep</tt> fields apply to the
3501 targets <tt>binary</tt> and <tt>binary-indep</tt>.
3512 <chapt id="conffiles"><heading>Configuration file handling
3516 <prgn>dpkg</prgn> can do a certain amount of automatic
3517 handling of package configuration files.
3521 Whether this mechanism is appropriate depends on a number of
3522 factors, but basically there are two approaches to any
3523 particular configuration file.
3527 The easy method is to ship a best-effort configuration in the
3528 package, and use <prgn>dpkg</prgn>'s conffile mechanism to
3529 handle updates. If the user is unlikely to want to edit the
3530 file, but you need them to be able to without losing their
3531 changes, and a new package with a changed version of the file
3532 is only released infrequently, this is a good approach.
3536 The hard method is to build the configuration file from
3537 scratch in the <prgn>postinst</prgn> script, and to take the
3538 responsibility for fixing any mistakes made in earlier
3539 versions of the package automatically. This will be
3540 appropriate if the file is likely to need to be different on
3545 <chapt id="sharedlibs"><heading>Shared libraries
3549 Packages containing shared libraries must be constructed with
3550 a little care to make sure that the shared library is always
3551 available. This is especially important for packages whose
3552 shared libraries are vitally important, such as the libc.
3556 Firstly, your package should install the shared libraries
3557 under their normal names. For example, the
3558 <prgn>libgdbm1</prgn> package should install
3559 <tt>libgdbm.so.1.7.3</tt> as
3560 <tt>/usr/lib/libgdbm.so.1.7.3</tt>. The files should not be
3561 renamed or re-linked by any prerm or postrm scripts;
3562 <prgn>dpkg</prgn> will take care of renaming things safely
3563 without affecting running programs, and attempts to interfere
3564 with this are likely to lead to problems.
3568 Secondly, your package should include the symlink that
3569 <prgn>ldconfig</prgn> would create for the shared libraries.
3570 For example, the <prgn>libgdbm1</prgn> package should include
3571 a symlink from <tt>/usr/lib/libgdbm.so.1</tt> to
3572 <tt>libgdbm.so.1.7.3</tt>. This is needed so that
3573 <prgn>ld.so</prgn> can find the library in between the time
3574 <prgn>dpkg</prgn> installs it and <prgn>ldconfig</prgn> is run
3575 in the <prgn>postinst</prgn> script. Furthermore, older
3576 versions of the package management system required the library
3577 must be placed before the symlink pointing to it in the
3578 <tt>.deb</tt> file. This is so that by the time
3579 <prgn>dpkg</prgn> comes to install the symlink (overwriting
3580 the previous symlink pointing at an older version of the
3581 library) the new shared library is already in place.
3582 Unfortunately, this was not not always possible, since it
3583 highly depends on the behavior of the file system. Some
3584 file systems (such as reiserfs) will reorder the files so it
3585 doesn't matter in what order you create them. Starting with
3586 release <tt>1.7.0</tt> <prgn>dpkg</prgn> will reorder the
3587 files itself when building a package.
3591 Thirdly, the development package should contain a symlink for
3592 the shared library without a version number. For example, the
3593 <tt>libgdbm1-dev</tt> package should include a symlink from
3594 <tt>/usr/lib/libgdm.so</tt> to <tt>libgdm.so.1.7.3</tt>. This
3595 symlink is needed by <prgn>ld</prgn> when compiling packages
3596 as it will only look for <tt>libgdm.so</tt> and
3597 <tt>libgdm.a</tt> when compiling dynamically or statically,
3602 Any package installing shared libraries in a directory that's listed
3603 in <tt>/etc/ld.so.conf</tt> or in one of the default library
3604 directories of <prgn>ld.so</prgn> (currently, these are <tt>/usr/lib</tt>
3605 and <tt>/lib</tt>) must call <prgn>ldconfig</prgn> in its <prgn>postinst</prgn>
3606 script if and only if the first argument is `configure'. However, it
3607 is important not to call <prgn>ldconfig</prgn> in the postrm or preinst
3608 scripts in the case where the package is being upgraded (see <ref
3609 id="unpackphase">), as <prgn>ldconfig</prgn> will see the temporary names
3610 that <prgn>dpkg</prgn> uses for the files while it is
3611 installing them and will make the shared library links point
3612 to them, just before <prgn>dpkg</prgn> continues the
3613 installation and removes the links!
3616 <sect id="shlibs"><heading>The <tt>shlibs</tt> File Format
3620 This file is for use by <prgn>dpkg-shlibdeps</prgn> and is
3621 required when your package provides shared libraries.
3625 Each line is of the form:
3627 <var>library-name</var> <var>version-or-soname</var> <var>dependencies ...</var>
3632 <var>library-name</var> is the name of the shared library,
3633 for example <tt>libc5</tt>.
3637 <var>version-or-soname</var> is the soname of the library -
3638 i.e., the thing that must exactly match for the library to be
3639 recognized by <prgn>ld.so</prgn>. Usually this is the major
3640 version number of the library.
3644 <var>dependencies</var> has the same syntax as a dependency
3645 field in a binary package control file. It should give
3646 details of which package(s) are required to satisfy a binary
3647 built against the version of the library contained in the
3648 package. See <ref id="depsyntax">.
3652 For example, if the package <tt>foo</tt> contains
3653 <tt>libfoo.so.1.2.3</tt>, where the soname of the library is
3654 <tt>libfoo.so.1</tt>, and the first version of the package
3655 which contained a minor number of at least <tt>2.3</tt> was
3656 <var>1.2.3-1</var>, then the package's <var>shlibs</var>
3659 libfoo 1 foo (>= 1.2.3-1)
3664 The version-specific dependency is to avoid warnings from
3665 <prgn>ld.so</prgn> about using older shared libraries with
3669 <sect><heading>Further Technical information on
3670 <tt>shlibs</tt></heading>
3672 <sect1><heading><em>What</em> are the <tt>shlibs</tt> files?
3676 The <tt>debian/shlibs</tt> file provides a way of checking
3677 for shared library dependencies on packaged binaries.
3678 They are intended to be used by package maintainers to
3679 make their lives easier.
3683 Other <tt>shlibs</tt> files that exist on a Debian system are
3685 <item> <p><tt>/etc/dpkg/shlibs.default</tt></p></item>
3686 <item> <p><tt>/etc/dpkg/shlibs.override</tt></p></item>
3687 <item> <p><tt>/var/lib/dpkg/info/*.shlibs</tt></p></item>
3688 <item> <p><tt>debian/shlibs.local</tt></p></item>
3690 These files are used by <prgn>dpkg-shlibdeps</prgn> when
3691 creating a binary package.</p>
3694 <sect1><heading><em>How</em> does <prgn>dpkg-shlibdeps</prgn>
3698 <prgn>dpkg-shlibdeps</prgn>
3699 determines the shared libraries directly
3702 It used to do this by calling <prgn>ldd</prgn>, but it
3703 now calls <prgn>objdump</prgn> to do this. This
3704 requires a couple of changes in the way that packages
3708 A binary <tt>foo</tt> directly uses a library
3709 <tt>libbar</tt> if it is linked with that
3710 library. Other libraries that are needed by
3711 <tt>libbar</tt> are linked indirectly to <tt>foo</tt>,
3712 and the dynamic linker will load them automatically
3713 when it loads <tt>libbar</tt>. Running<prgn>ldd</prgn>
3714 lists all of the libraries used, both directly and
3715 indirectly; but <prgn>objdump</prgn> only lists the
3716 directly linked libraries. A package only needs to
3717 depend on the libraries it is directly linked to,
3718 since the dependencies for those libraries should
3719 automatically pull in the other libraries.
3722 This change does mean a change in the way packages are
3723 build though: currently <prgn>dpkg-shlibdeps</prgn> is
3724 only run on binaries. But since we will now rely on the
3725 libraries depending on the libraries they themselves
3726 need, the packages containing those libraries will
3727 need to run <prgn>dpkg-shlibdeps</prgn> on the
3731 A good example where this would help us is the current
3732 mess with multiple version of the <tt>mesa</tt>
3733 library. With the <prgn>ldd</prgn>-based system, every
3734 package that uses <tt>mesa</tt> needs to add a
3735 dependency on <tt>svgalib|svgalib-dummy</tt> in order
3736 to handle the glide <tt>mesa</tt> variant. With an
3737 <prgn>objdump</prgn>-based system this isn't necessary
3738 anymore and would have saved everyone a lot of work.
3741 Another example: we could update <tt>libimlib</tt>
3742 with a new version that supports a new graphics format
3743 called dgf. If we use the old <prgn>ldd</prgn> method,
3744 every package that uses <tt>libimlib</tt> would need
3745 to be recompiled so it would also depend on
3746 <tt>libdgf</tt> or it wouldn't run due to missing
3747 symbols. However with the new system, packages using
3748 <tt>libimlib</tt> can rely on <tt>libimlib</tt> itself
3749 having the dependency on <tt>libdgf</tt> and wouldn't
3753 used by the compiled binaries and libraries passed through
3754 on its command line.
3758 For each shared library linked to,
3759 <prgn>dpkg-shlibdeps</prgn> needs to know
3760 <list compact="compact">
3761 <item><p>the package containing the library, and</p></item>
3762 <item><p>the library version number,</p></item>
3764 and it scans the following files in this order:
3765 <enumlist compact="compact">
3766 <item><p><tt>debian/shlibs.local</tt></p></item>
3767 <item><p><tt>/etc/dpkg/shlibs.override</tt></p></item>
3768 <item><p><tt>/var/lib/dpkg/info/*.shlibs</tt></p></item>
3769 <item><p><tt>/etc/dpkg/shlibs.default</tt></p></item>
3774 <sect1><heading><em>Who</em> maintains the various
3775 <tt>shlibs</tt> files?
3779 <list compact="compact">
3781 <p><tt>/etc/dpkg/shlibs.default</tt> - the maintainer
3786 <tt>/var/lib/dpkg/info/<var>package</var>.shlibs</tt>
3787 - the maintainer of each package</p>
3791 <tt>/etc/dpkg/shlibs.override</tt> - the local
3792 system administrator</p>
3795 <p><tt>debian/shlibs.local</tt> - the maintainer of
3800 The <tt>shlibs.default</tt> file is managed by
3801 <prgn>dpkg</prgn>. The entries in <tt>shlibs.default</tt>
3802 that are provided by <prgn>dpkg</prgn> are just there to
3803 fix things until the shared library packages all have
3804 <tt>shlibs</tt> files.
3808 <sect1><heading><em>How</em> to use <prgn>dpkg-shlibdeps</prgn> and
3809 the <tt>shlibs</tt> files
3812 <sect2><heading>If your package doesn't provide a shared
3817 Put a call to <prgn>dpkg-shlibdeps</prgn> into your
3818 <tt>debian/rules</tt> file. If your package contains
3819 only binaries (e.g. no scripts) use:
3821 dpkg-shlibdeps debian/tmp/usr/bin/* debian/tmp/usr/sbin/*
3823 If <prgn>dpkg-shlibdeps</prgn> doesn't complain, you're
3824 done. If it does complain you might need to create your
3825 own <tt>debian/shlibs.local</tt> file.</p>
3828 <sect2><heading>If your package provides a shared library
3832 Create a <tt>debian/shlibs</tt> file and let
3833 <tt>debian/rules</tt> install it in the control area:
3835 install -m644 debian/shlibs debian/tmp/DEBIAN
3837 If your package contains additional binaries see above.
3842 <sect1><heading><em>How</em> to write
3843 <tt>debian/shlibs.local</tt>
3847 This file is intended only as a <em>temporary</em> fix if
3848 your binaries depend on a library which doesn't provide
3849 its own <tt>/var/lib/dpkg/info/*.shlibs</tt> file yet.
3853 Let's assume you are packaging a binary <tt>foo</tt>. Your
3854 output in building the package might look like this.
3857 libbar.so.1 => /usr/X11R6/lib/libbar.so.1.0 (0x4001e000)
3858 libX11.so.6 => /usr/X11R6/lib/libX11.so.6 (0x4002c000)
3859 libc.so.6 => /lib/libc.so.6 (0x40114000)
3860 /lib/ld-linux.so.2 => /lib/ld-linux.so.2 (0x40000000)
3862 And when you ran <prgn>dpkg-shlibdeps</prgn>
3864 $ dpkg-shlibdeps -O foo
3865 dpkg-shlibdeps: warning: unable to find dependency information for shared library libbar
3866 (soname 1, path /usr/X11R6/lib/libbar.so.1.0, dependency field Depends)
3867 shlibs:Depends=libc6 (>= 2.2.1), xlibs (>= 4.0.1-11)
3869 The <prgn>foo</prgn> binary depends on the
3870 <prgn>libbar</prgn> shared library, but no package seems
3871 to provide a <tt>*.shlibs</tt> file in
3872 <tt>/var/lib/dpkg/info/</tt>. Let's determine the package
3878 $ dpkg -S /usr/X11R6/lib/libbar.so.1.0
3879 bar1: /usr/X11R6/lib/libbar.so.1.0
3880 $ dpkg -s bar1 | grep Version
3883 This tells us that the <prgn>bar1</prgn> package, version
3884 1.0-1 is the one we are using. Now we can create our own
3885 <tt>debian/shlibs.local</tt> to temporarily fix the above
3886 problem. Include the following line into your
3887 <tt>debian/shlibs.local</tt> file.
3889 libbar 1 bar1 (>= 1.0-1)
3891 Now your package build should work. As soon as the
3892 maintainer of <prgn>libbar1</prgn> provides a
3893 <tt>shlibs</tt> file, you can remove your
3894 <tt>debian/shlibs.local</tt> file.
3900 <chapt><heading>The Operating System</heading>
3904 <heading>File system hierarchy</heading>
3908 <heading>Linux File system Structure</heading>
3911 The location of all installed files and directories must
3912 comply with the Linux File system Hierarchy Standard
3913 (FHS). The latest version of this document can be found
3914 alongside this manual or on
3915 <url id="http://www.pathname.com/fhs/">.
3916 Specific questions about following the standard may be
3917 asked on <prgn>debian-devel</prgn>, or referred to Daniel
3918 Quinlan, the FHS coordinator, at
3919 <email>quinlan@pathname.com</email>.</p></sect1>
3923 <heading>Site-specific programs</heading>
3926 As mandated by the FHS, packages must not place any
3927 files in <tt>/usr/local</tt>, either by putting them in
3928 the file system archive to be unpacked by <prgn>dpkg</prgn>
3929 or by manipulating them in their maintainer scripts.</p>
3932 However, the package may create empty directories below
3933 <tt>/usr/local</tt> so that the system administrator knows
3934 where to place site-specific files. These directories
3935 should be removed on package removal if they are
3939 Note, that this applies only to directories <em>below</em>
3940 <tt>/usr/local</tt>, not <em>in</em>
3941 <tt>/usr/local</tt>. Packages must not create sub-directories
3942 in the directory <tt>/usr/local</tt> itself, except those listed in
3943 FHS, section 4.5. However, you may create directories
3944 below them as you wish. You must not remove any of the
3945 directories listed in 4.5, even if you created them.</p>
3948 Since <tt>/usr/local</tt> can be mounted read-only from a
3949 remote server, these directories must be created and
3950 removed by the <tt>postinst</tt> and <tt>prerm</tt>
3951 maintainer scripts. These scripts must not fail if either
3952 of these operations fail. (In the future, it will be
3953 possible to tell <prgn>dpkg</prgn> not to unpack files
3954 matching certain patterns, so that the directories can be
3955 included in the <tt>.deb</tt> packages and system
3956 administrators who do not wish these directories in
3957 /usr/local do not need to have them.)</p>
3960 For example, the <prgn>emacs</prgn> package will contain
3962 mkdir -p /usr/local/lib/emacs/site-lisp || true
3964 in the <tt>postinst</tt> script, and
3966 rmdir /usr/local/lib/emacs/site-lisp || true
3967 rmdir /usr/local/lib/emacs || true
3969 in the <tt>prerm</tt> script.</p>
3972 If you do create a directory in <tt>/usr/local</tt> for
3973 local additions to a package, you should ensure that
3974 settings in <tt>/usr/local</tt> take precedence over the
3975 equivalents in <tt>/usr</tt>.</p>
3978 However, because '/usr/local' and its contents are for
3979 exclusive use of the local administrator, a package must
3980 not rely on the presence or absence of files or
3981 directories in '/usr/local' for normal operation.</p>
3984 The <tt>/usr/local</tt> directory itself and all the
3985 subdirectories created by the package should (by default) have
3986 permissions 2775 (group-writable and set-group-id) and be
3987 owned by <tt>root.staff</tt>.</p>
3992 <heading>Users and groups</heading>
3995 The Debian system can be configured to use either plain or
3996 shadow passwords.</p>
3999 Some user ids (UIDs) and group ids (GIDs) are reserved
4000 globally for use by certain packages. Because some packages
4001 need to include files which are owned by these users or
4002 groups, or need the ids compiled into binaries, these ids
4003 must be used on any Debian system only for the purpose for
4004 which they are allocated. This is a serious restriction, and
4005 we should avoid getting in the way of local administration
4006 policies. In particular, many sites allocate users and/or
4007 local system groups starting at 100.</p>
4010 Apart from this we should have dynamically allocated ids,
4011 which should by default be arranged in some sensible
4012 order--but the behavior should be configurable.</p>
4015 Packages other than <tt>base-passwd</tt> must not modify
4016 <tt>/etc/passwd</tt>, <tt>/etc/shadow</tt>,
4017 <tt>/etc/group</tt> or <tt>/etc/gshadow</tt>.</p>
4020 The UID and GID ranges are as follows:
4025 Globally allocated by the Debian project, the
4026 same on every Debian system. These ids will appear in
4027 the <tt>passwd</tt> and <tt>group</tt> files of all
4028 Debian systems, new ids in this range being added
4029 automatically as the <tt>base-passwd</tt> package is
4033 Packages which need a single statically allocated uid
4034 or gid should use one of these; their maintainers
4035 should ask the <tt>base-passwd</tt> maintainer for
4042 Dynamically allocated system users and groups.
4043 Packages which need a user or group, but can have this
4044 user or group allocated dynamically and differently on
4045 each system, should use `<tt>adduser --system</tt>' to
4046 create the group and/or user. <prgn>adduser</prgn>
4047 will check for the existence of the user or group, and
4048 if necessary choose an unused id based on the ranges
4049 specified in <tt>adduser.conf</tt>.</p></item>
4052 <tag>1000-29999:</tag>
4055 Dynamically allocated user accounts. By default
4056 <prgn>adduser</prgn> will choose UIDs and GIDs for
4057 user accounts in this range, though
4058 <tt>adduser.conf</tt> may be used to modify this
4062 <tag>30000-59999:</tag>
4064 <p>Reserved.</p></item>
4067 <tag>60000-64999:</tag>
4070 Globally allocated by the Debian project, but only
4071 created on demand. The ids are allocated centrally and
4072 statically, but the actual accounts are only created
4073 on users' systems on demand.</p>
4076 These ids are for packages which are obscure or which
4077 require many statically-allocated ids. These packages
4078 should check for and create the accounts in
4079 <tt>/etc/passwd</tt> or <tt>/etc/group</tt> (using
4080 <prgn>adduser</prgn> if it has this facility) if
4081 necessary. Packages which are likely to require
4082 further allocations should have a `hole' left after
4083 them in the allocation, to give them room to
4087 <tag>65000-65533:</tag>
4089 <p>Reserved.</p></item>
4094 <p>User `<tt>nobody</tt>.' The corresponding gid refers
4095 to the group `<tt>nogroup</tt>.'</p></item>
4101 <tt>(uid_t)(-1) == (gid_t)(-1)</tt>. NOT TO BE USED,
4102 because it is the error return sentinel value.</p>
4107 <sect id="sysvinit">
4108 <heading>System run levels</heading>
4111 <sect1 id="/etc/init.d">
4112 <heading>Introduction</heading>
4115 The <tt>/etc/init.d</tt> directory contains the scripts
4116 executed by <prgn>init</prgn> at boot time and when init
4117 state (or `runlevel') is changed (see <manref name="init"
4121 There are at least two different, yet functionally
4122 equivalent, ways of handling these scripts. For the sake
4123 of simplicity, this document describes only the symbolic
4124 link method. However, it must not be assumed by maintainer
4125 scripts that this method is being used, and any automated
4126 manipulation of the various runlevel behaviours by
4127 maintainer scripts must be performed using `update-rc.d'
4128 as described below and not by manually installing or
4129 removing symlinks. For information on the
4130 implementation details of the other method, implemented in
4131 the <tt>file-rc</tt> package, please refer to the
4132 documentation of that package.</p>
4135 These scripts are referenced by symbolic links in
4136 the <tt>/etc/rc<var>n</var>.d</tt> directories. When
4137 changing runlevels, <prgn>init</prgn> looks in the
4138 directory <tt>/etc/rc<var>n</var>.d</tt> for the scripts
4139 it should execute, where <var>n</var> is the runlevel that
4140 is being changed to, or `S' for the boot-up scripts.</p>
4143 The names of the links all have the form
4144 <tt>S<var>mm</var><var>script</var></tt> or
4145 <tt>K<var>mm</var><var>script</var></tt> where
4146 <var>mm</var> is a two-digit number and <var>script</var>
4147 is the name of the script (this should be the same as the
4148 name of the actual script in <tt>/etc/init.d</tt>.</p>
4151 When <prgn>init</prgn> changes runlevel first the targets
4152 of the links whose names starting with a <tt>K</tt> are
4153 executed, each with the single argument <tt>stop</tt>,
4154 followed by the scripts prefixed with an <tt>S</tt>, each
4155 with the single argument <tt>start</tt>. The <tt>K</tt>
4156 links are responsible for killing services and the
4157 <tt>S</tt> link for starting services upon entering the
4161 For example, if we are changing from runlevel 2 to
4162 runlevel 3, init will first execute all of the <tt>K</tt>
4163 prefixed scripts it finds in <tt>/etc/rc3.d</tt>, and then
4164 all of the <tt>S</tt> prefixed scripts. The links
4165 starting with <tt>K</tt> will cause the referred-to file
4166 to be executed with an argument of <tt>stop</tt>, and the
4167 <tt>S</tt> links with an argument of <tt>start</tt>.</p>
4170 The two-digit number <var>mm</var> is used to decide which
4171 order to start and stop things in--low-numbered links have
4172 their scripts run first. For example, the <tt>K20</tt>
4173 scripts will be executed before the <tt>K30</tt> scripts.
4174 This is used when a certain service must be started before
4175 another. For example, the name server <prgn>bind</prgn>
4176 might need to be started before the news server
4177 <prgn>inn</prgn> so that <prgn>inn</prgn> can set up its
4178 access lists. In this case, the script that starts
4179 <prgn>bind</prgn> would have a lower number than the
4180 script that starts <prgn>inn</prgn> so that it runs first:
4189 <heading>Writing the scripts</heading>
4192 Packages that include daemons for system services should
4193 place scripts in <tt>/etc/init.d</tt> to start or stop
4194 services at boot time or during a change of runlevel.
4195 These scripts should be named
4196 <tt>/etc/init.d/<var>package</var></tt>, and they should
4197 accept one argument, saying what to do:
4200 <tag><tt>start</tt></tag>
4201 <item><p>start the service,</p></item>
4203 <tag><tt>stop</tt></tag>
4204 <item><p>stop the service,</p></item>
4206 <tag><tt>restart</tt></tag>
4207 <item><p>stop and restart the service,</p></item>
4209 <tag><tt>reload</tt></tag>
4210 <item><p>cause the configuration of the service to be
4211 reloaded without actually stopping and restarting
4212 the service,</p></item>
4214 <tag><tt>force-reload</tt></tag> <item><p>cause the
4215 configuration to be reloaded if the service supports
4216 this, otherwise restart the service.</p></item>
4219 The <tt>start</tt>, <tt>stop</tt>, <tt>restart</tt>, and
4220 <tt>force-reload</tt> options should be supported by all
4221 scripts in <tt>/etc/init.d</tt>, the <tt>reload</tt>
4222 option is optional.</p>
4225 The <tt>init.d</tt> scripts should ensure that they will
4226 behave sensibly if invoked with <tt>start</tt> when the
4227 service is already running, or with <tt>stop</tt> when it
4228 isn't, and that they don't kill unfortunately-named user
4229 processes. The best way to achieve this is usually to use
4230 <prgn>start-stop-daemon</prgn>.</p>
4233 If a service reloads its configuration automatically (as
4234 in the case of <prgn>cron</prgn>, for example), the
4235 <tt>reload</tt> option of the <tt>init.d</tt> script
4236 should behave as if the configuration has been reloaded
4240 These scripts should not fail obscurely when the
4241 configuration files remain but the package has been
4242 removed, as configuration files remain on the system after
4243 the package has been removed. Only when <prgn>dpkg</prgn>
4244 is executed with the <tt>--purge</tt> option will
4245 configuration files be removed. In particular, the init
4246 script itself is usually a configuration file (see
4247 <ref id="init.d notes">), and will remain on the system if
4248 the package is removed but not purged. Therefore, you
4249 should include a <tt>test</tt> statement at the top of the
4252 test -f <var>program-executed-later-in-script</var> || exit 0
4256 Often there are some values in the `<tt>init.d</tt>'
4257 scripts that a system administrator will frequently want
4258 to change. While the scripts are frequently conffiles,
4259 modifying them requires that the administrator merge in
4260 their changes each time the package is upgraded and the
4261 conffile changes. To ease the burden on the system
4262 administrator, such configurable values should not be
4263 placed directly in the script. Instead, they should be
4264 placed in a file in `<tt>/etc/default</tt>', which
4265 typically will have the same base name as the
4266 `<tt>init.d</tt>' script. This extra file can be sourced
4267 by the script when the script runs. It must contain only
4268 variable settings and comments.
4272 To ensure that vital configurable values are always
4273 available, the `<tt>init.d</tt>' script should set default
4274 values for each of the shell variables it uses before
4275 sourcing the <tt>/etc/default/</tt> file. Also, since the
4276 `<tt>/etc/default/</tt>' file is often a conffile, the
4277 `<tt>init.d</tt>' script must behave sensibly without
4278 failing if it is deleted.
4284 <heading>Managing the links</heading>
4287 The program <prgn>update-rc.d</prgn> is provided to make
4288 it easier for package maintainers to arrange for the
4289 proper creation and removal of
4290 <tt>/etc/rc<var>n</var>.d</tt> symbolic links, or their
4291 functional equivalent if another method is being used.
4292 This may be used by maintainers in their packages'
4293 <tt>postinst</tt> and <tt>postrm</tt> scripts.</p>
4296 You must use this script to make changes to
4297 <tt>/etc/rc<var>n</var>.d</tt> and <em>never</em> either
4298 include any <tt>/etc/rc<var>n</var>.d</tt> symbolic links
4299 in the actual archive or manually create or remove the
4300 symbolic links in maintainer scripts. (The latter will
4301 fail if an alternative method of maintaining runlevel
4302 information is being used.)</p>
4305 By default <prgn>update-rc.d</prgn> will start services in
4306 each of the multi-user state runlevels (2, 3, 4, and 5)
4307 and stop them in the halt runlevel (0), the single-user
4308 runlevel (1) and the reboot runlevel (6). The system
4309 administrator will have the opportunity to customize
4310 runlevels by either running <prgn>update-rc.d</prgn>, by
4311 simply adding, moving, or removing the symbolic links in
4312 <tt>/etc/rc<var>n</var>.d</tt> if symbolic links are being
4313 used, or by modifying <tt>/etc/runlevel.conf</tt> if the
4314 <tt>file-rc</tt> method is being used.</p>
4317 To get the default behavior for your package, put in your
4318 <tt>postinst</tt> script
4320 update-rc.d <var>package</var> defaults >/dev/null
4322 and in your <tt>postrm</tt>
4324 if [ purge = "$1" ]; then
4325 update-rc.d <var>package</var> remove >/dev/null
4330 This will use a default sequence number of 20. If it does
4331 not matter when or in which order the script is run, use
4332 this default. If it does, then you should talk to the
4333 maintainer of the <prgn>sysvinit</prgn> package or post to
4334 <tt>debian-devel</tt>, and they will help you choose a
4338 For more information about using <tt>update-rc.d</tt>,
4339 please consult its manpage <manref name="update-rc.d"
4340 section="8">.</p></sect1>
4344 <heading>Boot-time initialization</heading>
4347 There used to be another directory, <tt>/etc/rc.boot</tt>,
4348 which contained scripts which were run once per machine
4349 boot. This has been deprecated in favour of links from
4350 <tt>/etc/rcS.d</tt> to files in <tt>/etc/init.d</tt> as
4351 described in <ref id="/etc/init.d">. Packages must not
4352 place files in <tt>/etc/rc.boot</tt>.</p>
4354 <sect1 id="init.d notes">
4355 <heading>Notes</heading>
4358 <em>Do not</em> include the
4359 <tt>/etc/rc<var>n</var>.d/*</tt> symbolic links in the
4360 <tt>.deb</tt> file system archive! <em>This will cause
4361 problems!</em> You must create them with
4362 <prgn>update-rc.d</prgn>, as above.</p>
4365 <em>Do not</em> include the
4366 <tt>/etc/rc<var>n</var>.d/*</tt> symbolic links in
4367 <prgn>dpkg</prgn>'s conffiles list! <em>This will cause
4368 problems!</em> You should, however, treat the
4369 <tt>/etc/init.d</tt> scripts as configuration files,
4370 either by marking them as conffiles or managing them
4371 correctly in the maintainer scripts (see
4372 <ref id="config files">). (This is important since we want
4373 to give the local system administrator the chance to adapt
4374 the scripts to the local system--e.g., to disable a
4375 service without de-installing the package, or to specify
4376 some special command line options when starting a
4377 service--while making sure her changes aren't lost during
4378 the next package upgrade.)</p>
4382 <heading>Example</heading>
4385 The <prgn>bind</prgn> DNS (nameserver) package wants to
4386 make sure that the nameserver is running in multiuser
4387 runlevels, and is properly shut down with the system. It
4388 puts a script in <tt>/etc/init.d</tt>, naming the script
4389 appropriately <tt>bind</tt>. As you can see, the script
4390 interprets the argument <tt>reload</tt> to send the
4391 nameserver a <tt>HUP</tt> signal (causing it to reload its
4392 configuration); this way the user can say
4393 <tt>/etc/init.d/bind reload</tt> to reload the name
4394 server. The script has one configurable value, which can
4395 be used to pass parameters to the named program at
4403 # Original version by Robert Leslie
4404 # <rob@mars.org>, edited by iwj and cs
4406 test -x /usr/sbin/named || exit 0
4408 # Source defaults file.
4410 if [ -f /etc/default/bind ]; then
4417 echo -n "Starting domain name service: named"
4418 start-stop-daemon --start --quiet --exec /usr/sbin/named \
4423 echo -n "Stopping domain name service: named"
4424 start-stop-daemon --stop --quiet \
4425 --pidfile /var/run/named.pid --exec /usr/sbin/named
4429 echo -n "Restarting domain name service: named"
4430 start-stop-daemon --stop --quiet \
4431 --pidfile /var/run/named.pid --exec /usr/sbin/named
4432 start-stop-daemon --start --verbose --exec /usr/sbin/named \
4436 force-reload|reload)
4437 echo -n "Reloading configuration of domain name service: named"
4438 start-stop-daemon --stop --signal 1 --quiet \
4439 --pidfile /var/run/named.pid --exec /usr/sbin/named
4443 echo "Usage: /etc/init.d/bind {start|stop|restart|reload|force-reload}" >&2
4453 Complementing the above init script is a file
4454 '<tt>/etc/default/bind</tt>', which contains configurable
4455 parameters used by the script.
4459 # Specified parameters to pass to named. See named(8).
4460 # You may uncomment the following line, and edit to taste.
4466 Another example on which to base your <tt>/etc/init.d</tt>
4467 scripts is in <tt>/etc/init.d/skeleton</tt>.</p>
4470 If this package is happy with the default setup from
4471 <prgn>update-rc.d</prgn>, namely an ordering number of 20
4472 and having named running in all runlevels, it can say in
4473 its <tt>postinst</tt>:
4475 update-rc.d bind defaults >/dev/null
4477 And in its <tt>postrm</tt>, to remove the links when the
4480 if [ purge = "$1" ]; then
4481 update-rc.d bind remove >/dev/null
4487 <heading>Cron jobs</heading>
4490 Packages must not modify the configuration file
4491 <tt>/etc/crontab</tt>, and they must not modify the files in
4492 <tt>/var/spool/cron/crontabs</tt>.</p>
4495 If a package wants to install a job that has to be executed
4496 via cron, it should place a file with the name of the
4497 package in one of the following directories:
4503 As these directory names imply, the files within them are
4504 executed on a daily, weekly, or monthly basis,
4505 respectively. The exact times are listed in
4506 <tt>/etc/crontab</tt>.</p>
4509 All files installed in any of these directories must be
4510 scripts (shell scripts, Perl scripts, etc.) so that they can
4511 easily be modified by the local system administrator. In
4512 addition, they should be treated as configuration files.</p>
4515 If a certain job has to be executed more frequently than
4516 daily, the package should install a file
4517 <tt>/etc/cron.d/<var>package-name</var></tt>. This file uses
4518 the same syntax as <tt>/etc/crontab</tt> and is processed by
4519 <prgn>cron</prgn> automatically. The file must also be
4520 treated as a configuration file. (Note, that entries in the
4521 <tt>/etc/cron.d</tt> directory are not handled by
4522 <prgn>anacron</prgn>. Thus, you should only use this
4523 directory for jobs which may be skipped if the system is not
4527 The scripts or crontab entries in these directories should
4528 check if all necessary programs are installed before they
4529 try to execute them. Otherwise, problems will arise when a
4530 package was removed but not purged since configuration files
4531 are kept on the system in this situation.</p>
4535 <heading>Console messages</heading>
4538 This section describes different formats for messages
4539 written to standard output by the <tt>/etc/init.d</tt>
4540 scripts. The intent is to improve the consistency of
4541 Debian's startup and shutdown look and feel.</p>
4544 Please look very careful at the details. We want to get the
4545 messages to look exactly the same way concerning spaces,
4546 punctuation, and case of letters.</p>
4549 Here is a list of overall rules that you should use when you
4550 create output messages. They can be useful if you have a
4551 non-standard message that isn't covered in the sections
4558 Every message should cover one line, start with a
4559 capital letter and end with a period `.'.</p></item>
4564 If you want to express that the computer is working on
4565 something (performing a specific task, not starting or
4566 stopping a program), we use an ``ellipsis'', namely
4567 three dots `...'. Note that we don't insert spaces in
4568 front of or behind the dots. If the task has been
4569 completed we write `done.' and a line feed.</p></item>
4574 Design your messages as if the computer is telling you
4575 what he is doing (let him be polite :-) but don't
4576 mention ``him'' directly. For example, if you think
4579 I'm starting network daemons: nfsd mountd.
4583 Starting network daemons: nfsd mountd.
4584 </example></p></item>
4588 The following formats should be used</p>
4593 <p>when daemons get started.</p>
4596 Use this format if your script starts one or more
4597 daemons. The output should look like this (a single
4598 line, no leading spaces):
4600 Starting <description>: <daemon-1> <daemon-2> <...> <daemon-n>.
4602 The <description> should describe the subsystem
4603 the daemon or set of daemons are part of, while
4604 <daemon-1> up to <daemon-n> denote each
4605 daemon's name (typically the file name of the
4609 For example, the output of /etc/init.d/lpd would look like:
4611 Starting printer spooler: lpd.
4615 This can be achieved by saying
4617 echo -n "Starting printer spooler: lpd"
4618 start-stop-daemon --start --quiet lpd
4621 in the script. If you have more than one daemon to
4622 start, you should do the following:
4624 echo -n "Starting remote file system services:"
4625 echo -n " nfsd"; start-stop-daemon --start --quiet nfsd
4626 echo -n " mountd"; start-stop-daemon --start --quiet mountd
4627 echo -n " ugidd"; start-stop-daemon --start --quiet ugidd
4630 This makes it possible for the user to see what takes
4631 so long and when the final daemon has been
4632 started. You should be careful where to put spaces: In the
4633 example above the system administrator can easily
4634 comment out a line if he don't wants to start a
4635 specific daemon, while the displayed message still
4636 looks good.</p></item>
4640 <p>when something needs to be configured.</p>
4643 If you have to set up different parameters of the
4644 system upon boot up, you should use this format:
4646 Setting <parameter> to `<value>'.
4650 You can use the following echo statement to get the quotes right:
4652 echo "Setting DNS domainname to \`"value"'."
4656 Note that the left quotation mark (`) is different
4657 from the right (').</p></item>
4660 <p>when a daemon is stopped.</p>
4663 When you stop a daemon you should issue a message
4664 similar to the startup message, except that `Starting'
4665 is replaced with `Stopping'.</p>
4668 So stopping the printer daemon will like like this:
4670 Stopping printer spooler: lpd.
4671 </example></p></item>
4674 <p>when something is executed.</p>
4677 There are several examples where you have to run a
4678 program at system startup or shutdown to perform a
4679 specific task. For example, setting the system's clock
4680 via `netdate' or killing all processes when the system
4681 comes down. Your message should like this:
4683 Doing something very useful...done.
4685 You should print the `done.' right after the job has been completed,
4686 so that the user gets informed why he has to wait. You can get this
4689 echo -n "Doing something very useful..."
4693 in your script.</p></item>
4696 <p>when the configuration is reloaded.</p>
4699 When a daemon is forced to reload its configuration
4700 files you should use the following format:
4702 Reloading <daemon's-name> configuration...done.
4703 </example></p></item>
4706 <p>when none of the above rules apply.</p>
4709 If you have to print a message that doesn't fit into
4710 the styles described above, you can use something
4711 appropriate, but please have a look at the overall
4712 rules listed above.</p></item>
4717 <heading>Menus</heading>
4720 Menu entries should follow the current menu policy as
4721 defined in the file <ftpsite>ftp.debian.org</ftpsite> in
4722 <ftppath>/debian/doc/package-developer/menu-policy.txt.gz</ftppath>
4723 or your local mirror. In addition, it is included in the
4724 <tt>debian-policy</tt> package.
4728 The Debian <tt>menu</tt> packages provides a unique
4729 interface between packages providing applications and
4730 documents, and <em>menu programs</em> (either X window
4731 managers or text-based menu programs as
4732 <prgn>pdmenu</prgn>).</p>
4735 All packages that provide applications that need not be
4736 passed any special command line arguments for normal
4737 operation should register a menu entry for those
4738 applications, so that users of the <tt>menu</tt> package
4739 will automatically get menu entries in their window
4740 managers, as well in shells like <tt>pdmenu</tt>.</p>
4743 Please refer to the <em>Debian Menu System</em> document
4744 that comes with the <tt>menu</tt> package for information
4745 about how to register your applications and web
4751 <heading>Multimedia handlers</heading>
4754 Packages which provide the ability to view/show/play,
4755 compose, edit or print MIME types should register themselves
4756 as such following the current MIME support policy as defined
4757 in the file found on <ftpsite>ftp.debian.org</ftpsite> in
4758 <ftppath>/debian/doc/package-developer/mime-policy.txt.gz</ftppath>
4759 or your local mirror. In addition, it is included in the
4760 <tt>debian-policy</tt> package.
4764 MIME (Multipurpose Internet Mail Extensions, RFC 1521) is a
4765 mechanism for encoding files and data streams and providing
4766 meta-information about them, in particular their type (e.g.
4767 audio or video) and format (e.g. PNG, HTML, MP3).
4771 Registration of MIME type handlers allows programs like mail
4772 user agents and web browsers to to invoke these handlers to
4773 view, edit or display MIME types they don't support
4779 <heading>Keyboard configuration</heading>
4782 To achieve a consistent keyboard configuration (i.e., all
4783 applications interpret a keyboard event the same way) all
4784 programs in the Debian distribution must be configured to
4785 comply with the following guidelines.</p>
4788 Here is a list that contains certain keys and their interpretation:
4791 <tag><tt><--</tt></tag>
4792 <item><p>delete the character to the left of the cursor</p></item>
4794 <tag><tt>Delete</tt></tag>
4795 <item><p>delete the character to the right of the cursor</p></item>
4797 <tag><tt>Control+H</tt></tag>
4798 <item><p>emacs: the help prefix</p></item>
4801 The interpretation of any keyboard events should be independent
4802 of the terminal that's used, be it a virtual console, an X
4803 terminal emulator, an rlogin/telnet session, etc.</p>
4806 The following list explains how the different programs
4807 should be set up to achieve this:</p>
4810 <list compact="compact">
4811 <item><p>`<tt><--</tt>' generates KB_Backspace in
4814 <item><p>`<tt>Delete</tt>' generates KB_Delete in X.</p></item>
4818 X translations are set up to make KB_Backspace
4819 generate ASCII DEL, and to make KB_Delete generate
4820 <tt>ESC [ 3 ~</tt> (this is the vt220 escape code for
4821 the `delete character' key). This must be done by
4822 loading the resources using xrdb on all local X
4823 displays, not using the application defaults, so that
4824 the translation resources used correspond to the
4825 xmodmap settings.</p></item>
4829 The Linux console is configured to make
4830 `<tt><--</tt>' generate DEL, and `Delete' generate
4831 <tt>ESC [ 3 ~</tt> (this is the case at the
4835 X applications are configured so that Backspace
4836 deletes left, and Delete deletes right. Motif
4837 applications already work like this.</p></item>
4839 <item><p>stty erase <tt>^?</tt> .</p></item>
4842 The `xterm' terminfo entry should have <tt>ESC [ 3
4843 ~</tt> for kdch1, just like TERM=linux and
4844 TERM=vt220.</p></item>
4847 Emacs is programmed to map KB_Backspace or the `stty
4848 erase' character to delete-backward-char, and
4849 KB_Delete or kdch1 to delete-forward-char, and
4850 <tt>^H</tt> to help as always.</p></item>
4853 Other applications use the `stty erase' character and
4854 kdch1 for the two delete keys, with ASCII DEL being
4855 `delete previous character' and kdch1 being `delete
4856 character under cursor'.</p></item>
4860 This will solve the problem except for:</p>
4863 <list compact="compact">
4865 Some terminals have a <tt><--</tt> key that cannot
4866 be made to produce anything except <tt>^H</tt>. On
4867 these terminals Emacs help will be unavailable on
4868 <tt>^H</tt> (assuming that the `stty erase' character
4869 takes precedence in Emacs, and has been set
4870 correctly). M-x help or F1 (if available) can be used
4874 Some operating systems use <tt>^H</tt> for stty erase.
4875 However, modern telnet versions and all rlogin
4876 versions propagate stty settings, and almost all UNIX
4877 versions honour stty erase. Where the stty settings
4878 are not propagated correctly things can be made to
4879 work by using stty manually.</p></item>
4882 Some systems (including previous Debian versions) use
4883 xmodmap to arrange for both <tt><--</tt> and Delete
4884 to generate KB_Delete. We can change the behavior
4885 of their X clients via the same X resources that we
4886 use to do it for our own, or have our clients be
4887 configured via their resources when things are the
4888 other way around. On displays configured like this
4889 Delete will not work, but <tt><--</tt>
4893 Some operating systems have different kdch1 settings
4894 in their terminfo for xterm and others. On these
4895 systems the Delete key will not work correctly when
4896 you log in from a system conforming to our policy, but
4897 <tt><--</tt> will.</p></item>
4904 <heading>Environment variables</heading>
4907 A program must not depend on environment variables to get
4908 reasonable defaults. (That's because these environment
4909 variables would have to be set in a system-wide
4910 configuration file like /etc/profile, which is not supported
4914 If a program usually depends on environment variables for its
4915 configuration, the program should be changed to fall back to
4916 a reasonable default configuration if these environment
4917 variables are not present. If this cannot be done easily
4918 (e.g., if the source code of a non-free program is not
4919 available), the program must be replaced by a small
4920 `wrapper' shell script which sets the environment variables
4921 if they are not already defined, and calls the original program.</p>
4924 Here is an example of a wrapper script for this purpose:
4928 BAR=${BAR:-/var/lib/fubar}
4930 exec /usr/lib/foo/foo "$@"
4934 Furthermore, as <tt>/etc/profile</tt> is a configuration
4935 file of the <prgn>base-files</prgn> package, other packages must not
4936 put any environment variables or other commands into that
4941 <heading>Files</heading>
4945 <heading>Binaries</heading>
4948 Two different packages must not install programs with
4949 different functionality but with the same filenames. (The
4950 case of two programs having the same functionality but
4951 different implementations is handled via `alternatives.')
4952 If this case happens, one of the programs must be
4953 renamed. The maintainers should report this to the
4954 developers' mailing and try to find a consensus about
4955 which package will have to be renamed. If a consensus can
4956 not be reached, <em>both</em> programs must be
4960 Generally the following compilation parameters should be used:
4963 CFLAGS = -O2 -Wall # sane warning options vary between programs
4965 install -s # (or use strip on the files in debian/tmp)
4969 Note that by default all installed binaries should be stripped,
4970 either by using the <tt>-s</tt> flag to
4971 <prgn>install</prgn>, or by calling <prgn>strip</prgn> on
4972 the binaries after they have been copied into
4973 <tt>debian/tmp</tt> but before the tree is made into a
4977 The <tt>-N</tt> flag should not be used. On a.out systems
4978 it may have been useful for some very small binaries, but
4979 for ELF it has no good effect.</p>
4982 Debugging symbols are useful for error diagnosis,
4983 investigation of core dumps (which may be submitted by users
4984 in bug reports), or testing and developing the
4985 software. Therefore it is recommended to support building
4986 the package with debugging information through the following
4987 interface: If the environment variable
4988 <tt>DEB_BUILD_OPTIONS</tt> contains the string
4989 <tt>debug</tt>, compile the software with debugging
4990 information (usually this involves adding the <tt>-g</tt>
4991 flag to <tt>CFLAGS</tt>). This allows the generation of a
4992 build tree with debugging information. If the environment
4993 variable <tt>DEB_BUILD_OPTIONS</tt> contains the string
4994 <tt>nostrip</tt>, do not strip the files at installation
4995 time. This allows one to generate a package with debugging
4996 information included. The following makefile snippet is only
4997 an example of how one may test for either condition:
5000 Rationale: Building by default with -g causes more
5001 wasted CPU cycles since the information is stripped away
5002 anyway. The package can by default build without -g if
5003 it also provides a mechanism to easily be rebuilt with
5004 debugging information. This can be done by providing a
5005 "build-debug" make target, or allowing the user to
5006 specify "DEB_BUILD_OPTIONS=debug" in the environment while
5007 compiling that package.
5009 <p>Now this has several added benefits:
5013 It is actually easier to build debugging bins and
5014 libraries this way (no more editing debian/rules
5015 or similar) since it provides a documented way of
5016 getting this type of build.</p>
5020 There will be much less wasted CPU time for the
5021 autobuilders since not having debugging
5022 information (and hence also not having to strip
5023 it) will increase the speed of compiles. This
5024 skips an entire pass of the compiler.
5035 INSTALL_FILE = $(INSTALL) -p -o root -g root -m 644
5036 INSTALL_PROGRAM = $(INSTALL) -p -o root -g root -m 755
5037 INSTALL_SCRIPT = $(INSTALL) -p -o root -g root -m 755
5038 INSTALL_DIR = $(INSTALL) -p -d -o root -g root -m 755
5040 ifneq (,$(findstring debug,$(DEB_BUILD_OPTIONS)))
5043 ifeq (,$(findstring nostrip,$(DEB_BUILD_OPTIONS)))
5044 INSTALL_PROGRAM += -s
5048 Please note that the above example is merely informative,
5049 and is not a policy mandate. You may have to massage this
5050 example in order to make it work for your package.
5055 It is up to the package maintainer to decide what
5056 compilation options are best for the package. Certain
5057 binaries (such as computationally-intensive programs) will
5058 function better with certain flags (<tt>-O3</tt>, for
5059 example); feel free to use them. Please use good judgment
5060 here. Don't use flags for the sake of it; only use them
5061 if there is good reason to do so. Feel free to override
5062 the upstream author's ideas about which compilation
5063 options are best--they are often inappropriate for our
5064 environment.</p></sect>
5068 <heading>Libraries</heading>
5071 All libraries must have a shared version in the lib
5072 package and a static version in the lib-dev package. The
5073 shared version must be compiled with <tt>-fPIC</tt>, and
5074 the static version must not be. In other words, each
5075 <tt>*.c</tt> file will need to be compiled twice.</p>
5078 You must specify the gcc option <tt>-D_REENTRANT</tt>
5079 when building a library (either static or shared) to make
5080 the library compatible with LinuxThreads.</p>
5083 Note that all installed shared libraries should be
5086 strip --strip-unneeded <your-lib>
5088 (The option `--strip-unneeded' makes <tt>strip</tt> remove
5089 only the symbols which aren't needed for relocation
5090 processing.) Shared libraries can function perfectly well
5091 when stripped, since the symbols for dynamic linking are
5092 in a separate part of the ELF object file.</p>
5095 Note that under some circumstances it may be useful to
5096 install a shared library unstripped, for example when
5097 building a separate package to support debugging.
5101 An ever increasing number of packages are using libtool to
5102 do their linking. The latest GNU libtools (>= 1.3a) can take
5103 advantage of the metadata in the installed libtool archive
5104 files (`*.la'). The main advantage of libtool's .la files is
5105 that it allows libtool to store and subsequently access
5106 metadata with respect to the libraries it builds. libtool
5107 will search for those files, which contain a lot of useful
5108 information about a library (e.g. dependency libraries for
5109 static linking). Also, they're <em>essential</em> for
5110 programs using libltdl.
5114 Certainly libtool is fully capable of linking against shared
5115 libraries which don't have .la files, but being a mere shell
5116 script it can add considerably to the build time of a
5117 libtool using package if that shell-script has to derive all
5118 this information from first principles for each library every
5119 time it is linked. With the advent of libtool-1.4 (and to a
5120 lesser extent libtool-1.3), the .la files will also store
5121 information about inter-library dependencies which cannot
5122 necessarily be derived after the .la file is deleted.
5126 Packages that use libtool to create shared libraries should
5127 include the <em>.la</em> files in the <em>-dev</em>
5128 packages, with the exception that if the package relies on
5129 libtool's <em>libltdl</em> library, in which case the .la
5130 files must go in the run-time library package. This is a
5131 good idea in general, and especially for static linking
5136 You must make sure that you use only released versions of
5137 shared libraries to build your packages; otherwise other
5138 users will not be able to run your binaries
5139 properly. Producing source packages that depend on
5140 unreleased compilers is also usually a bad
5147 <heading>Shared libraries</heading>
5150 Packages involving shared libraries should be split up
5151 into several binary packages.</p>
5154 For a straightforward library which has a development
5155 environment and a runtime kit including just shared
5156 libraries you need to create two packages:
5157 <tt><var>libraryname</var><var>soname</var></tt>
5158 (<var>soname</var> is the shared object name of the shared
5159 library--it's the thing that has to match exactly between
5160 building an executable and running it for the dynamic
5161 linker to be able run the program; usually the
5162 <var>soname</var> is the major number of the library) and
5163 <tt><var>libraryname</var><var>soname</var>-dev</tt>.</p>
5166 If you prefer only to support one development version at a
5167 time you may name the development package
5168 <tt><var>libraryname</var>-dev</tt>; otherwise you may
5169 wish to use <prgn>dpkg</prgn>'s conflicts mechanism to
5170 ensure that the user only installs one development version
5171 at a time (after all, different development versions are
5172 likely to have the same header files in them, causing a
5173 filename clash if both are installed). Typically the
5174 development version should also have an exact version
5175 dependency on the runtime library, to make sure that
5176 compilation and linking happens correctly.</p>
5179 Packages which use the shared library should have a
5180 dependency on the name of the shared library package,
5181 <tt><var>libraryname</var><var>soname</var></tt>. When
5182 the <var>soname</var> changes you can have both versions
5183 of the library installed while moving from the old library
5187 If your package has some run-time support programs which
5188 use the shared library you must not put them in
5189 the shared library package. If you do that then you won't
5190 be able to install several versions of the shared library
5191 without getting filename clashes. Instead, either create
5192 a third package for the runtime binaries (this package
5193 might typically be named
5194 <tt><var>libraryname</var>-runtime</tt>--note the absence
5195 of the <var>soname</var> in the package name) or if the
5196 development package is small include them in there.</p>
5199 If you have several shared libraries built from the same
5200 source tree you may lump them all together into a single
5201 shared library package, provided that you change all their
5202 <var>soname</var>s at once (so that you don't get filename
5203 clashes if you try to install different versions of the
5204 combined shared libraries package).</p>
5207 You should follow the directions in the <em>Debian Packaging
5208 Manual</em> for putting the shared library in its package,
5209 and you must include a <tt>shlibs</tt> control area
5210 file with details of the dependencies for packages which
5211 use the library.</p>
5214 Shared libraries should not be installed
5215 executable, since <prgn>ld.so</prgn> does not require this
5216 and trying to execute a shared library results in a core
5221 <heading>Scripts</heading>
5224 All command scripts, including the package maintainer
5225 scripts inside the package and used by <prgn>dpkg</prgn>,
5226 should have a <tt>#!</tt> line naming the shell to be used
5227 to interpret them.</p>
5230 In the case of Perl scripts this should be
5231 <tt>#!/usr/bin/perl</tt>.</p>
5234 Shell scripts (<prgn>sh</prgn> and <prgn>bash</prgn>)
5235 should almost certainly start with <tt>set -e</tt> so that
5236 errors are detected. Every script should use
5237 <tt>set -e</tt> or check the exit status of <em>every</em>
5241 The standard shell interpreter `<tt>/bin/sh</tt>' can be a
5242 symbolic link to any POSIX compatible shell, if <tt>echo
5243 -n</tt> does not generate a newline.
5246 Debian policy specifies POSIX behavior for /bin/sh, but
5247 echo -n has widespread use in the Linux community
5248 (including especially debian policy, the linux kernel
5249 source, many debian scripts, etc.). This echo -n
5250 mechanism is valid but not required under POSIX, hence
5251 this explicit addition. Also, rumour has it that this
5252 shall be mandated under the LSB anyway.
5256 specifying `<tt>/bin/sh</tt>' as interpreter should only
5257 use POSIX features. If a script requires non-POSIX
5258 features from the shell interpreter, the appropriate shell
5259 must be specified in the first line of the script (e.g.,
5260 `<tt>#!/bin/bash</tt>') and the package must depend on the
5261 package providing the shell (unless the shell package is
5262 marked `Essential', e.g., in the case of
5267 You may wish to restrict your script to POSIX features when possible so
5268 that it may use <tt>/bin/sh</tt> as its interpreter. If
5269 your script works with <prgn>ash</prgn>, it's probably
5270 POSIX compliant, but if you are in doubt, use
5271 <tt>/bin/bash</tt>.</p>
5274 Perl scripts should check for errors when making any
5275 system calls, including <tt>open</tt>, <tt>print</tt>,
5276 <tt>close</tt>, <tt>rename</tt> and <tt>system</tt>.</p>
5279 <prgn>csh</prgn> and <prgn>tcsh</prgn> should be avoided
5280 as scripting languages. See <em>Csh Programming
5281 Considered Harmful</em>, one of the <tt>comp.unix.*</tt>
5282 FAQs. It can be found on
5283 <url id="http://language.perl.com/versus/csh.whynot">, or
5284 <url id="http://www.cpan.org/doc/FMTEYEWTK/versus/csh.whynot">
5285 or even on <ftpsite>ftp.cpan.org</ftpsite>
5286 <ftppath>/pub/perl/CPAN/doc/FMTEYEWTK/versus/csh.whynot</ftppath>.
5287 If an upstream package comes with <prgn>csh</prgn> scripts
5288 then you must make sure that they start with
5289 <tt>#!/bin/csh</tt> and make your package depend on the
5290 <prgn>c-shell</prgn> virtual package.</p>
5293 Any scripts which create files in world-writeable
5294 directories (e.g., in <tt>/tmp</tt>) must use a
5295 mechanism which will fail if a file with the same name
5299 The Debian base distribution provides the
5300 <prgn>tempfile</prgn> and <prgn>mktemp</prgn> utilities
5301 for use by scripts for this purpose.</p></sect>
5305 <heading>Symbolic links</heading>
5308 In general, symbolic links within a top-level directory
5309 should be relative, and symbolic links pointing from one
5310 top-level directory into another should be absolute. (A
5311 top-level directory is a sub-directory of the root
5315 In addition, symbolic links should be specified as short
5316 as possible, i.e., link targets like `foo/../bar' are
5320 Note that when creating a relative link using
5321 <prgn>ln</prgn> it is not necessary for the target of the
5322 link to exist relative to the working directory you're
5323 running <prgn>ln</prgn> from; nor is it necessary to
5324 change directory to the directory where the link is to be
5325 made. Simply include the string that should appear as the
5326 target of the link (this will be a pathname relative to
5327 the directory in which the link resides) as the first
5328 argument to <prgn>ln</prgn>.</p>
5331 For example, in your <prgn>Makefile</prgn> or
5332 <tt>debian/rules</tt>, do things like:
5334 ln -fs gcc $(prefix)/bin/cc
5335 ln -fs gcc debian/tmp/usr/bin/cc
5336 ln -fs ../sbin/sendmail $(prefix)/bin/runq
5337 ln -fs ../sbin/sendmail debian/tmp/usr/bin/runq
5341 A symbolic link pointing to a compressed file should
5342 always have the same file extension as the referenced
5343 file. (For example, if a file `<tt>foo.gz</tt>' is
5344 referenced by a symbolic link, the filename of the link
5345 has to end with `<tt>.gz</tt>' too, as in
5346 `bar.gz.')</p></sect>
5350 <heading>Device files</heading>
5353 Packages must not include device files in the package file
5357 If a package needs any special device files that are not
5358 included in the base system, it must call
5359 <prgn>MAKEDEV</prgn> in the <tt>postinst</tt> script,
5360 after asking the user for permission to do so.</p>
5363 Packages must not remove any device files in the
5364 <tt>postrm</tt> or any other script. This is left to the
5365 system administrator.</p>
5368 Debian uses the serial devices
5369 <tt>/dev/ttyS*</tt>. Programs using the old
5370 <tt>/dev/cu*</tt> devices should be changed to use
5371 <tt>/dev/ttyS*</tt>.</p>
5374 <sect id="config files">
5375 <heading>Configuration files</heading>
5377 <heading>Definitions</heading>
5380 <tag>configuration file</tag>
5382 A file that affects the operation of program, or
5383 provides site- or host-specific information, or
5384 otherwise customizes the behavior of program.
5385 Typically, configuration files are intended to be
5386 modified by the system administrator (if needed or
5387 desired) to conform to local policy or provide more
5388 useful site-specific behavior.</p>
5391 <tag><tt>conffile</tt></tag>
5393 A file listed in a package's <tt>conffiles</tt>
5394 file, and is treated specially by <prgn>dpkg</prgn>
5395 (see the <em>Debian Packaging Manual</em>).</p>
5401 The distinction between these two is important; they are
5402 not interchangeable concepts. Almost all
5403 <tt>conffiles</tt> are configuration files, but many
5404 configuration files are not <tt>conffiles</tt>.</p>
5407 Note that a script that embeds configuration information
5408 (such as most of the files in <tt>/etc/init.d</tt> and
5409 <tt>/etc/cron.{daily,weekly,monthly}</tt>) is de-facto a
5410 configuration file and should be treated as such.</p>
5414 <heading>Location</heading>
5416 Any configuration files created or used by your package
5417 must reside in <tt>/etc</tt>. If there are several you
5418 should consider creating a subdirectory of <tt>/etc</tt>
5419 named after your package.</p>
5422 If your package creates or uses configuration files
5423 outside of <tt>/etc</tt>, and it is not feasible to modify
5424 the package to use the <tt>/etc</tt>, you should still put
5425 the files in <tt>/etc</tt> and create symbolic links to
5426 those files from the location that the package
5431 <heading>Behavior</heading>
5433 Configuration file handling must conform to the following
5437 <p>local changes must be preserved during a package
5441 <p>configuration files must be preserved when the
5442 package is removed, and only deleted when the
5443 package is purged.</p>
5448 The easy way to achieve this behavior is to make the
5449 configuration file a <tt>conffile</tt>. This is
5450 appropriate only if it is possible to distribute a default
5451 version that will work for most installations, although
5452 some system administrators may choose to modify it. This
5453 implies that the default version will be part of the
5454 package distribution, and must not be modified by the
5455 maintainer scripts during installation (or at any other
5460 In order to ensure that local changes are preserved
5461 correctly, no package may contain or make hard links to
5465 Rationale: There are two problems with hard links.
5466 The first is that some editors break the link while
5467 editing one of the files, so that the two files may
5468 unwittingly become different. The second is that
5469 <prgn>dpkg</prgn> might break the hard link while
5470 upgrading <tt>conffile</tt>s.
5476 The other way to do it is via the maintainer scripts.
5477 In this case, the configuration file must not be listed as
5478 a <tt>conffile</tt> and must not be part of the package
5479 distribution. If the existence of a file is required for
5480 the package to be sensibly configured it is the
5481 responsibility of the package maintainer to write scripts
5482 which correctly create, update, maintain and
5483 remove-on-purge the file. These scripts must be idempotent
5484 (i.e., must work correctly if <prgn>dpkg</prgn> needs to
5485 re-run them due to errors during installation or removal),
5486 must cope with all the variety of ways <prgn>dpkg</prgn>
5487 can call maintainer scripts, must not overwrite or
5488 otherwise mangle the user's configuration without asking,
5489 must not ask unnecessary questions (particularly during
5490 upgrades), and otherwise be good citizens.</p>
5493 The scripts are not required to configure every possible option for
5494 the package, but only those necessary to get the package
5495 running on a given system. Ideally the sysadmin should not
5496 have to do any configuration other than that done
5497 (semi-)automatically by the <tt>postinst</tt> script.</p>
5500 A common practice is to create a script called
5501 <tt><var>package</var>-configure</tt> and have the
5502 package's <tt>postinst</tt> call it if and only if the
5503 configuration file does not already exist. In certain
5504 cases it is useful for there to be an example or template
5505 file which the maintainer scripts use. Such files should
5506 be in <tt>/usr/share/<package></tt> or
5507 <tt>/usr/lib/<package></tt> with a symbolic link
5508 from <tt>/usr/share/doc/<package>/examples</tt>
5509 if they are examples, and should be
5510 perfectly ordinary <prgn>dpkg</prgn>-handled files
5511 (<em>not</em> <tt>conffiles</tt>).
5515 These two styles of configuration file handling must
5516 not be mixed, for that way lies madness:
5517 <prgn>dpkg</prgn> will ask about overwriting the file
5518 every time the package is upgraded.</p>
5523 <heading>Sharing configuration files</heading>
5525 Packages which specify the same file as
5526 `<tt>conffile</tt>' must be tagged as <em>conflicting</em>
5531 The maintainer scripts must not alter the conffile of
5532 <em>any</em> package, including the one the scripts belong
5536 If two or more packages use the same configuration file
5537 and it is reasonable for both to be installed at the same
5538 time, one of these packages must be defined as
5539 <em>owner</em> of the configuration file, i.e., it will be
5540 the package to list that distributes the file and lists it
5541 as a <tt>conffile</tt>. Other packages that use the
5542 configuration file must depend on the owning package if
5543 they require the configuration file to operate. If the
5544 other package will use the configuration file if present,
5545 but is capable of operating without it, no dependency need
5549 If it is desirable for two or more related packages to
5550 share a configuration file <em>and</em> for all of the
5551 related packages to be able to modify that configuration
5552 file, then the following should be done:
5556 have one of the related packages (the "core"
5557 package) manage the configuration file with
5558 maintainer scripts as described in the previous
5562 the core package should also provide a program that
5563 the other packages may use to modify the
5564 configuration file.</p>
5568 the related packages must use the provided program
5569 to make any modifications to the configuration file.
5570 They should either depend on the core package to
5571 guarantee that the configuration modifier program is
5572 available or accept gracefully that they cannot
5573 modify the configuration file if it is not.</p>
5578 Sometimes it's appropriate to create a new package which
5579 provides the basic infrastructure for the other packages
5580 and which manages the shared configuration files. (Check
5581 out the <tt>sgml-base</tt> package as an example.)</p>
5585 <heading>User configuration files ("dotfiles")</heading>
5588 Files in <tt>/etc/skel</tt> will automatically be copied
5589 into new user accounts by <prgn>adduser</prgn>. They
5590 should not be referenced there by any program.</p>
5593 Therefore, if a program needs a dotfile to exist in
5594 advance in <tt>$HOME</tt> to work sensibly, that dotfile
5595 should be installed in <tt>/etc/skel</tt> (and listed in
5596 conffiles, if it is not generated and modified dynamically
5597 by the package's installation scripts).</p>
5600 However, programs that require dotfiles in order to
5601 operate sensibly (dotfiles that they do not create
5602 themselves automatically, that is) are a bad thing, and
5603 programs should be configured by the Debian default
5604 installation as close to normal as possible.</p>
5607 Therefore, if a program in a Debian package needs to be
5608 configured in some way in order to operate sensibly that
5609 configuration should be done in a site-wide global
5610 configuration file elsewhere in <tt>/etc</tt>. Only if the
5611 program doesn't support a site-wide default configuration
5612 and the package maintainer doesn't have time to add it
5613 may a default per-user file be placed in
5614 <tt>/etc/skel</tt>.</p>
5617 <tt>/etc/skel</tt> should be as empty as we can make it.
5618 This is particularly true because there is no easy
5619 mechanism for ensuring that the appropriate dotfiles are
5620 copied into the accounts of existing users when a package
5626 <heading>Log files</heading>
5628 The traditional approach to log files has been to set up ad
5629 hoc log rotation schemes using simple shell scripts and
5630 cron. While this approach is highly customizable, it
5631 requires quite a lot of sysadmin work. Even though the
5632 original Debian system helped a little by automatically
5633 installing a system which can be used as a template, this
5634 was deemed not enough.
5638 A better scheme is to use logrotate, a GPL'd program
5639 developed by Red Hat, which centralizes log management. It
5640 has both a configuration file (<tt>/etc/logrotate.conf</tt>)
5641 and a directory where packages can drop logrotation info
5642 (<tt>/etc/logrotate.d</tt>).
5646 Log files should usually be named
5647 <tt>/var/log/<var>package</var>.log</tt>. If you have many
5648 log files, or need a separate directory for permissions
5649 reasons (<tt>/var/log</tt> is writable only by
5650 <tt>root</tt>), you should usually create a directory named
5651 <tt>/var/log/<var>package</var></tt>.</p>
5654 Log files must be rotated occasionally so
5655 that they don't grow indefinitely; the best way to do this
5656 is to drop a script into the directory
5657 <tt>/etc/logrotate.d</tt> and use the facilities provided by
5658 logrotate. Here is a good example for a logrotate config
5659 file (for more information see <manref name="logrotate"
5667 /etc/init.d/foo force-reload
5671 Which rotates all files under `/var/log/foo', saves 12
5672 compressed generations, and sends a HUP signal at the end of
5678 Log files should be removed when the package is
5679 purged (but not when it is only removed), by checking the
5680 argument to the <tt>postrm</tt> script (see the <em>Debian
5681 Packaging Manual</em> for details).</p>
5686 <heading>Permissions and owners</heading>
5689 The rules in this section are guidelines for general use.
5690 If necessary you may deviate from the details below.
5691 However, if you do so you must make sure that what is done
5692 is secure and you should try to be as consistent as possible
5693 with the rest of the system. You should probably also
5694 discuss it on <prgn>debian-devel</prgn> first.</p>
5697 Files should be owned by <tt>root.root</tt>, and made
5698 writable only by the owner and universally readable (and
5699 executable, if appropriate).</p>
5702 Directories should be mode 755 or (for group-writability)
5703 mode 2775. The ownership of the directory should be
5704 consistent with its mode--if a directory is mode 2775, it
5705 should be owned by the group that needs write access to
5709 Setuid and setgid executables should be mode 4755 or 2755
5710 respectively, and owned by the appropriate user or group.
5711 They should not be made unreadable (modes like 4711 or
5712 2711 or even 4111); doing so achieves no extra security,
5713 because anyone can find the binary in the freely available
5714 Debian package--it is merely inconvenient. For the same
5715 reason you should not restrict read or execute permissions
5716 on non-set-id executables.</p>
5719 Some setuid programs need to be restricted to particular
5720 sets of users, using file permissions. In this case they
5721 should be owned by the uid to which they are set-id, and
5722 by the group which should be allowed to execute them.
5723 They should have mode 4754; there is no point in making
5724 them unreadable to those users who must not be allowed to
5728 You must not arrange that the system administrator can only
5729 reconfigure the package to correspond to their local
5730 security policy by changing the permissions on a binary.
5731 Ordinary files installed by <prgn>dpkg</prgn> (as opposed
5732 to conffiles and other similar objects) have their
5733 permissions reset to the distributed permissions when the
5734 package is reinstalled. Instead you should consider (for
5735 example) creating a group for people allowed to use the
5736 program(s) and making any setuid executables executable
5737 only by that group.</p>
5740 If you need to create a new user or group for your package
5741 there are two possibilities. Firstly, you may need to
5742 make some files in the binary package be owned by this
5743 user or group, or you may need to compile the user or
5744 group id (rather than just the name) into the binary
5745 (though this latter should be avoided if possible, as in
5746 this case you need a statically allocated id).</p>
5749 If you need a statically allocated id, you must ask for a
5750 user or group id from the base system
5751 maintainer, and must not release the package until you
5752 have been allocated one. Once you have been allocated one
5753 you must make the package depend on a version of the base
5754 system with the id present in <tt>/etc/passwd</tt> or
5755 <tt>/etc/group</tt>, or alternatively arrange for your
5756 package to create the user or group itself with the
5757 correct id (using <tt>adduser</tt>) in its pre- or
5758 post-installation script (the latter is to be preferred if
5759 it is possible).</p>
5762 On the other hand, the program might be able to determine the
5763 uid or gid from the group name at runtime, so that a
5764 dynamic id can be used. In this case you should choose an
5765 appropriate user or group name, discussing this on
5766 <prgn>debian-devel</prgn> and checking with the base
5767 system maintainer that it is unique and that they do not
5768 wish you to use a statically allocated id instead. When
5769 this has been checked you must arrange for your package to
5770 create the user or group if necessary using
5771 <prgn>adduser</prgn> in the pre- or post-installation
5772 script (again, the latter is to be preferred if it is
5776 Note that changing the numeric value of an id associated with a name
5777 is very difficult, and involves searching the file system for all
5778 appropriate files. You need to think carefully whether a static or
5779 dynamic id is required, since changing your mind later will cause
5785 <heading>Customized programs</heading>
5787 <sect id="arch-spec">
5788 <heading>Architecture specification strings</heading>
5791 If a program needs to specify an <em>architecture specification
5792 string</em> in some place, the following format should be used:
5794 <arch>-<os>
5796 where `<arch>' is one of the following: i386, alpha, arm, m68k,
5797 powerpc, sparc and `<os>' is one of: linux, gnu. Use
5798 of <em>gnu</em> in this string is reserved for the GNU/Hurd
5799 operating system.</p>
5801 Note, that we don't want to use `<arch>-debian-linux'
5802 to apply to the rule `architecture-vendor-os' since this
5803 would make our programs incompatible to other Linux
5804 distributions. Also note, that we don't use
5805 `<arch>-unknown-linux', since the `unknown' does not
5806 look very good.</p></sect>
5810 <heading>Daemons</heading>
5813 The configuration files <tt>/etc/services</tt>,
5814 <tt>/etc/protocols</tt>, and <tt>/etc/rpc</tt> are managed
5815 by the <prgn>netbase</prgn> package and may not be modified
5816 by other packages.</p>
5819 If a package requires a new entry in one of these files, the
5820 maintainer should get in contact with the
5821 <prgn>netbase</prgn> maintainer, who will add the entries
5822 and release a new version of the <prgn>netbase</prgn>
5826 The configuration file <tt>/etc/inetd.conf</tt> must not be
5827 modified by the package's scripts except via the
5828 <prgn>update-inetd</prgn> script or the
5829 <prgn>DebianNet.pm</prgn> Perl module.</p>
5832 If a package wants to install an example entry into
5833 <tt>/etc/inetd.conf</tt>, the entry must be preceded with
5834 exactly one hash character (<tt>#</tt>). Such lines are
5835 treated as `commented out by user' by the
5836 <prgn>update-inetd</prgn> script and are not changed or
5837 activated during a package updates.</p></sect>
5841 <heading>Using pseudo-ttys and modifying wtmp, utmp and lastlog</heading>
5844 Some programs need to create pseudo-ttys. This should be done
5845 using Unix98 ptys if the C library supports it. The resulting
5846 program must not be installed setuid root, unless that
5847 is required for other functionality.
5851 The files <tt>/var/run/utmp</tt>, <tt>/var/log/wtmp</tt> and
5852 <tt>/var/log/lastlog</tt> must be installed writeable by
5853 group utmp. Programs who need to modify those files must
5854 be installed setgid utmp.
5859 <heading>Editors and pagers</heading>
5862 Some programs have the ability to launch an editor or pager
5863 program to edit or display a text document. Since there are
5864 lots of different editors and pagers available in the Debian
5865 distribution, the system administrator and each user should
5866 have the possibility to choose his/her preferred editor and
5870 In addition, every program should choose a good default
5871 editor/pager if none is selected by the user or system
5875 Thus, every program that launches an editor or pager must
5876 use the EDITOR or PAGER environment variables to determine
5877 the editor/pager the user wants to get started. If these
5878 variables are not set, the programs <tt>/usr/bin/editor</tt>
5879 and <tt>/usr/bin/pager</tt> should be used, respectively.</p>
5882 These two files are managed through `alternatives.' That is,
5883 every package providing an editor or pager must call the
5884 <prgn>update-alternatives</prgn> script to register these
5888 If it is very hard to adapt a program to make us of the
5889 EDITOR and PAGER variables, that program may be configured
5890 to use <tt>/usr/bin/sensible-editor</tt> and
5891 <tt>/usr/bin/sensible-pager</tt> as editor or pager program,
5892 respectively. These are two scripts provided in the Debian
5893 base system that check the EDITOR and PAGER variables and
5894 launch the appropriate program or fall back to
5895 <tt>/usr/bin/editor</tt> and <tt>/usr/bin/pager</tt>,
5899 A program may also use the VISUAL environment variable to
5900 determine the user's choice of editor. If it exists, it
5901 should take precedence over EDITOR. This is in fact what
5902 <tt>/usr/bin/sensible-editor</tt> does.</p>
5905 It is not required for a package to depend on
5906 `editor' and `pager', nor is it required for a package to
5907 provide such virtual packages.
5910 The Debian base system already provides an editor and
5919 <sect id="web-appl">
5920 <heading>Web servers and applications</heading>
5923 This section describes the locations and URLs that should
5924 be used by all web servers and web application in the Debian
5930 <p>Cgi-bin executable files are installed in the
5933 /usr/lib/cgi-bin/<cgi-bin-name>
5935 and should be referred to as
5937 http://localhost/cgi-bin/<cgi-bin-name>
5938 </example></p></item>
5941 <item><p>Access to html documents</p>
5944 Html documents for a package are stored in
5945 <tt>/usr/share/doc/<var>package</var></tt> but should
5946 be accessed via symlinks as
5947 <tt>/usr/doc/<var>package</var></tt><footnote> for
5948 backward compatibility, see <ref id="usrdoc"></footnote>
5949 and can be referred to as
5951 http://localhost/doc/<package>/<filename>
5952 </example></p></item>
5955 <item><p>Web Document Root</p>
5958 Web Applications should try to avoid storing files in
5959 the Web Document Root. Instead they should use the
5960 /usr/share/doc/<package> directory for documents and
5961 register the Web Application via the menu package. If
5962 access to the web-root is unavoidable then use
5966 as the Document Root. This might be just a
5967 symbolic link to the location where the sysadmin has
5968 put the real document root.</p>
5971 </enumlist></p></sect>
5975 <heading>Mail transport, delivery and user agents</heading>
5978 Debian packages which process electronic mail, whether
5979 mail-user-agents (MUAs) or mail-transport-agents (MTAs),
5980 must make sure that they are compatible with the
5981 configuration decisions below. Failure to do this may
5982 result in lost mail, broken <tt>From:</tt> lines, and other
5983 serious brain damage!</p>
5986 The mail spool is <tt>/var/spool/mail</tt> and the interface
5987 to send a mail message is <tt>/usr/sbin/sendmail</tt> (as
5988 per the FHS). The mail spool is part of the base system
5989 and not part of the MTA package.</p>
5992 All Debian MUAs, MTAs, MDAs and other mailbox accessing
5993 programs (like IMAP daemons) must lock the mailbox in an
5994 NFS-safe way. This means that <tt>fcntl()</tt> locking must
5995 be combined with dot locking. To avoid deadlocks, a
5996 program should use <tt>fcntl()</tt> first and dot locking
5997 after this or alternatively implement the two locking
5998 methods in a non blocking way<footnote>
6000 If it is not possible to establish both locks, the
6001 system shouldn't wait for the second lock to be
6002 established, but remove the first lock, wait a (random)
6003 time, and start over locking again.</p>
6004 </footnote>. Using the functions <tt>maillock</tt> and
6005 <tt>mailunlock</tt> provided by the
6006 <tt>liblockfile*</tt><footnote>
6008 <tt>liblockfile</tt> version >>1.01</p>
6009 </footnote> packages is the recommended way to realize this.
6013 Mailboxes are generally 660 <tt><var>user</var>.mail</tt>
6014 unless the user has chosen otherwise. A MUA may remove a
6015 mailbox (unless it has nonstandard permissions) in which
6016 case the MTA or another MUA must recreate it if needed.
6017 Mailboxes must be writable by group mail.</p>
6020 The mail spool is 2775 <tt>root.mail</tt>, and MUAs should
6021 be setgid mail to do the locking mentioned above (and
6022 must obviously avoid accessing other users' mailboxes
6023 using this privilege).</p>
6026 <tt>/etc/aliases</tt> is the source file for the system mail
6027 aliases (e.g., postmaster, usenet, etc.)--it is the one
6028 which the sysadmin and <tt>postinst</tt> scripts may edit.
6029 After <tt>/etc/aliases</tt> is edited the program or human
6030 editing it must call <prgn>newaliases</prgn>. All MTA
6031 packages must come with a <prgn>newaliases</prgn> program,
6032 even if it does nothing, but older MTA packages do not do
6033 this so programs should not fail if <prgn>newaliases</prgn>
6034 cannot be found.</p>
6037 The convention of writing <tt>forward to
6038 <var>address</var></tt> in the mailbox itself is not
6039 supported. Use a <tt>.forward</tt> file instead.</p>
6042 The <prgn>rmail</prgn> program used by UUCP
6043 for incoming mail should be <tt>/usr/sbin/rmail</tt>.
6044 Likewise, <prgn>rsmtp</prgn>, for receiving
6045 batch-SMTP-over-UUCP, should be <tt>/usr/sbin/rsmtp</tt> if it
6049 If you need to know what name to use (for example) on
6050 outgoing news and mail messages which are generated locally,
6051 you should use the file <tt>/etc/mailname</tt>. It will
6052 contain the portion after the username and <tt>@</tt> (at)
6053 sign for email addresses of users on the machine (followed
6057 A package should check for the existence of this file. If
6058 it exists it should use it without comment. (An MTA's
6059 prompting configuration script may wish to prompt the user
6060 even if it finds this file exists.) If it does not exist it
6061 should prompt the user for the value and store it in
6062 <tt>/etc/mailname</tt> as well as using it in the package's
6063 configuration. The prompt should make it clear that the
6064 name will not just be used by that package. For example, in
6065 this situation the INN package says:
6067 Please enter the `mail name' of your system. This is the
6068 hostname portion of the address to be shown on outgoing
6069 news and mail messages. The default is
6070 <var>syshostname</var>, your system's host name. Mail
6071 name [`<var>syshostname</var>']:
6073 where <var>syshostname</var> is the output of <tt>hostname
6074 --fqdn</tt>.</p></sect>
6078 <heading>News system configuration</heading>
6081 All the configuration files related to the NNTP (news)
6082 servers and clients should be located under
6083 <tt>/etc/news</tt>.</p>
6086 There are some configuration issues that apply to a number
6087 of news clients and server packages on the machine. These
6091 <tag>/etc/news/organization</tag>
6092 <item><p>A string which should appear as the
6093 organization header for all messages posted
6094 by NNTP clients on the machine</p></item>
6096 <tag>/etc/news/server</tag>
6097 <item><p>Contains the FQDN of the upstream NNTP
6098 server, or localhost if the local machine is
6099 an NNTP server.</p></item>
6102 Other global files may be added as required for cross-package news
6103 configuration.</p></sect>
6107 <heading>Programs for the X Window System</heading>
6110 <em>Programs that may be configured with support for the X Window
6111 System</em> must be configured to do so and must declare any
6112 package dependencies necessary to satisfy their runtime
6113 requirements when using the X Window System, unless the package
6114 in question is of standard or higher priority, in which case
6115 X-specific binaries may be split into a separate package, or
6116 alternative versions of the package with X support may be
6122 <em>Packages which provide an X server</em> that, directly or
6123 indirectly, communicates with real input and display hardware
6124 should declare in their control data that they provide the
6125 virtual package <tt>xserver</tt>.
6128 This implements current practice, and provides an actual
6129 policy for usage of the "xserver" virtual package which
6130 appears in the virtual packages list. In a nutshell, X
6131 servers that interface directly with the display and input
6132 hardware or via another subsystem (e.g., GGI) should provide
6133 xserver. Things like Xvfb, Xnest, and Xprt should not.
6139 <em>Packages that provide a terminal emulator</em> for the X
6140 Window System which support a terminal type with a terminfo
6141 description provided in the <tt>ncurses-base</tt> package
6142 should declare in their control data that they provide the
6143 virtual package <tt>x-terminal-emulator</tt>. They should
6144 also register themselves as an alternative for
6145 <tt>/usr/bin/x-terminal-emulator</tt>, with a priority of
6150 <em>Packages that provide window managers</em> should declare in
6151 their control data that they provide the virtual package
6152 <tt>x-window-manager</tt>. They should also register themselves as an
6153 alternative for <tt>/usr/bin/x-window-manager</tt>, with a priority
6154 calculated as follows:
6156 <item>Start with a priority of 20.</item>
6157 <item>If the window manager supports the Debian menu system,
6158 add 20 points if this support is available in the
6159 package's default configuration (i.e., no
6160 configuration files belonging to the system or user
6161 have to be edited to activate the feature); if
6162 configuration files must be modified, add only 10
6164 <item>If the window manager permits the X session to be
6165 restarted using a <em>different</em> window manager
6166 (without killing the X server) in its default
6167 configuration, add 10 points; otherwise add
6173 <em>Packages that provide fonts for the X Window System</em>
6174 must do a number of things to ensure that they are both
6175 available without modification of the X or font server
6176 configuration, and that they do not corrupt files used by
6177 other font packages to register information about themselves.
6180 Fonts of any type supported by the X Window System
6181 should be be in a separate binary package from any
6182 executables, libraries, or documentation (except that
6183 specific to the fonts shipped); if a program or
6184 library is <em>unusable</em> without one or more
6185 specific fonts, the package containing the program or
6186 library should declare a dependency on the package(s)
6187 containing the font(s) it requires.
6190 BDF fonts should be converted to PCF fonts with the
6191 <tt>bdftopcf</tt> utility (available in the
6192 <tt>xutils</tt> package, <tt>gzip</tt>ped, and
6193 placed in a directory that corresponds to their
6197 100 dpi fonts should be placed in
6198 <tt>/usr/X11R6/lib/X11/fonts/100dpi/</tt>.
6201 75 dpi fonts should be placed in
6202 <tt>/usr/X11R6/lib/X11/fonts/75dpi/</tt>.
6205 Character-cell fonts, cursor fonts, and other
6206 low-resolution fonts should be placed in
6207 <tt>/usr/X11R6/lib/X11/fonts/misc/</tt>.
6212 Speedo fonts should be placed in
6213 <tt>/usr/X11R6/lib/X11/fonts/Speedo/</tt>.
6216 Type 1 fonts should be placed in
6217 <tt>/usr/X11R6/lib/X11/fonts/Type1/</tt>. If font
6218 metric files are available, they may be placed here as
6222 Subdirectories of <tt>/usr/X11R6/lib/X11/fonts/</tt>
6223 other than those listed above should be neither created nor
6224 used. (The <tt>PEX</tt> and <tt>cyrillic</tt> directories are
6225 excepted for historical reasons, but installation of files into
6226 these directories remains discouraged.)
6229 Font packages may, instead of placing files directly in
6230 the X font directories listed above, provide symbolic links in
6231 the font directory which point to the files' actual location
6232 in the filesystem. Such a location should comply with the
6236 Font packages should not contain both 75dpi and 100dpi
6237 versions of a font. If both are available, they should be
6238 provided in separate binary packages with "-75dpi" or "-100dpi"
6239 appended to the names of the packages containing the
6240 corresponding fonts.
6243 Fonts destined for the <tt>misc</tt> subdirectory should
6244 not be included in the same package as 75dpi or 100dpi fonts;
6245 instead, they should be provided in a separate package with
6246 "-misc" appended to its name.
6249 Font packages <em>must not</em> provide the files
6250 <tt>fonts.dir</tt>, <tt>fonts.alias</tt>, or
6251 <tt>fonts.scale</tt> in a font directory.
6254 <tt>fonts.dir</tt> files must not be provided at
6258 <tt>fonts.alias</tt> and <tt>fonts.scale</tt>
6259 files, if needed, should be provided in the
6261 <tt>/etc/X11/fonts/<em>fontdir</em>/<em>package</em>.<em>extension</em></tt>,
6262 where <em>fontdir</em> is the name of the
6264 <tt>/usr/X11R6/lib/X11/fonts/</tt> where the
6265 package's corresponding fonts are stored (e.g.,
6266 <tt>75dpi</tt> or <tt>misc</tt>),
6267 <em>package</em> is the name of the package that
6268 provides these fonts, and <em>extension</em> is
6269 either <tt>scale</tt> or <tt>alias</tt>,
6270 whichever corresponds to the file
6276 Font packages must declare a dependency on
6277 <tt>xutils</tt> and, in the package
6278 post-installation and post-removal scripts, invoke the
6279 <tt>mkfontdir</tt> command on each directory into
6280 which they installed fonts.
6283 Font packages that provide one or more
6284 <tt>fonts.scale</tt> files as described above must declare a
6285 versioned dependency on <tt>xutils (>=
6286 4.0.2)</tt> and invoke <tt>update-fonts-scale</tt> on each
6287 directory into which they installed fonts
6288 <em>before</em> invoking <tt>mkfontdir</tt> on that
6289 directory. This invocation must occur in both the
6290 post-installation and post-removal scripts.
6293 Font packages that provide one or more
6294 <tt>fonts.alias</tt> files as described above must
6295 declare a versioned dependency on <tt>xutils
6296 (>= 4.0.2)</tt> and, in the package
6297 post-installation and post-removal scripts, invoke
6298 <tt>update-fonts-alias</tt> on each directory into
6299 which they installed fonts.
6302 Font packages must not provide alias names for the
6303 fonts they include which collide with alias names already in
6304 use by fonts already packaged.
6307 Font packages must not provide fonts with the same XLFD
6308 registry name as another font already packaged.
6314 <em>Application defaults</em> files must be installed in the
6315 directory <tt>/etc/X11/app-defaults/</tt> (use of a
6316 localized subdirectory of <tt>/etc/X11/</tt> as described in
6317 the <em>X Toolkit Intrinsics - C Language Interface</em>
6318 manual is also permitted). They must be registered as
6319 <em>conffile</em>s or handled as configuration files. For
6320 programs that are not linked against the X Toolkit (Xt)
6321 library, customization of programs' X resources may also be
6322 supported with the provision of a file with the same name as
6323 that of the package placed in the
6324 <tt>/etc/X11/Xresources/</tt> directory, which must
6325 registered as a <em>conffile</em> or handled as a
6326 configuration file. <em>Important:</em> packages that
6327 install files into the <tt>/etc/X11/Xresources/</tt>
6328 directory <em>must</em> declare a conflict with <tt>xbase
6329 (<< 3.3.2.3a-2)</tt>; if this is not done it is
6330 possible for the installing package to destroy a
6331 previously-existing <tt>/etc/X11/Xresources</tt> file which
6332 had been customized by the system administrator.
6336 <em>Packages using the X Window System should abide by the FHS
6337 standard whenever possible</em>; they should install binaries,
6338 libraries, manual pages, and other files in FHS-mandated
6339 locations wherever possible. This means that files must
6340 not be installed into <tt>/usr/X11R6/bin/</tt>,
6341 <tt>/usr/X11R6/lib/</tt>, or <tt>/usr/X11R6/man/</tt> unless
6342 this is necessary for the package to operate properly.
6343 Configuration files for window managers and display managers
6344 should be placed in a subdirectory of <tt>/etc/X11/</tt>
6345 corresponding to the package name due to these programs'
6346 tight integration with the mechanisms of the X Window
6347 System. Application-level programs should use the
6348 <tt>/etc/</tt> directory unless otherwise mandated by
6349 policy. The installation of files into subdirectories of
6350 <tt>/usr/X11R6/include/X11/</tt> and
6351 <tt>/usr/X11R6/lib/X11/</tt> is permitted but discouraged;
6352 package maintainers should determine if subdirectories of
6353 <tt>/usr/lib/</tt> and <tt>/usr/share/</tt> can be used
6354 instead (symlinks from the X11R6 directories to
6355 FHS-compliant locations is encouraged if the program is not
6356 easily configured to look elsewhere for its files).
6357 Packages must not provide -- or install files into -- the
6358 directories <tt>/usr/bin/X11/</tt>,
6359 <tt>/usr/include/X11/</tt>, or <tt>/usr/lib/X11/</tt>.
6360 Files within a package should, however, make reference to
6361 these directories, rather than their X11R6-named
6362 counterparts <tt>/usr/X11R6/bin/</tt>,
6363 <tt>/usr/X11R6/include/X11/</tt>, and
6364 <tt>/usr/X11R6/lib/X11/</tt>, if the resources being
6365 referred to have not been moved to FHS-compliant locations.
6369 <em>Programs that require the non-DFSG-compliant OSF/Motif
6370 library</em> should be compiled against and tested with
6371 LessTif (a free re-implementation of Motif) instead. If the
6372 maintainer judges that the program or programs do not work
6373 sufficiently well with LessTif to be distributed and
6374 supported, but do so when compiled against Motif, then two
6375 versions of the package should be created; one linked
6376 statically against Motif and with <tt>-smotif</tt> appended
6377 to the package name, and one linked dynamically against
6378 Motif and with <tt>-dmotif</tt> appended to the package
6379 name. Both Motif-linked versions are dependent upon
6380 non-DFSG-compliant software and thus cannot be uploaded to
6381 the main distribution; if the software is itself
6382 DFSG-compliant it may be uploaded to the contrib
6383 distribution. While known existing versions of OSF/Motif
6384 permit unlimited redistribution of binaries linked against
6385 the library (whether statically or dynamically), it is the
6386 package maintainer's responsibility to determine whether
6387 this is permitted by the license of the copy of OSF/Motif in
6388 his or her possession.
6394 <heading>Emacs lisp programs</heading>
6397 Please refer to the `Debian Emacs Policy' (documented in
6398 <tt>debian-emacs-policy.gz</tt> of the
6399 <prgn>emacsen-common</prgn> package) for details of how to
6400 package emacs lisp programs.</p></sect>
6404 <heading>Games</heading>
6407 The permissions on /var/games are 755
6408 <tt>root.root</tt>.</p>
6411 Each game decides on its own security policy.</p>
6414 Games which require protected, privileged access to
6415 high-score files, savegames, etc., may be made
6416 set-<em>group</em>-id (mode 2755) and owned by
6417 <tt>root.games</tt>, and use files and directories with
6418 appropriate permissions (770 <tt>root.games</tt>, for
6419 example). They must not be made
6420 set-<em>user</em>-id, as this causes security problems. (If
6421 an attacker can subvert any set-user-id game they can
6422 overwrite the executable of any other, causing other players
6423 of these games to run a Trojan horse program. With a
6424 set-group-id game the attacker only gets access to less
6425 important game data, and if they can get at the other
6426 players' accounts at all it will take considerably more
6430 Some packages, for example some fortune cookie programs, are
6431 configured by the upstream authors to install with their
6432 data files or other static information made unreadable so
6433 that they can only be accessed through set-id programs
6434 provided. You should not do this in a Debian package: anyone can
6435 download the <tt>.deb</tt> file and read the data from it,
6436 so there is no point making the files unreadable. Not
6437 making the files unreadable also means that you don't have
6438 to make so many programs set-id, which reduces the risk of a
6442 As described in the FHS, binaries of games should be
6443 installed in the directory <tt>/usr/games</tt>. This also
6444 applies to games that use the X Window System. Manual pages
6445 for games (X and non-X games) should be installed in
6446 <tt>/usr/share/man/man6</tt>.</p>
6450 <chapt><heading>Documentation</heading>
6454 <heading>Manual pages</heading>
6457 You should install manual pages in <prgn>nroff</prgn> source
6458 form, in appropriate places under <tt>/usr/share/man</tt>. You
6459 should only use sections 1 to 9 (see the FHS for more
6460 details). You must not install a preformatted `cat
6464 Each program, utility, and function should have an
6465 associated manpage included in the same package. It is
6466 suggested that all configuration files also have a manual
6467 page included as well.
6471 If no manual page is available for a particular program,
6472 utility, function or configuration file and this is reported as a bug on
6473 debian-bugs, a symbolic link from the requested manual page
6474 to the <manref name="undocumented" section="7"> manual page
6475 may be provided. This symbolic link can be created from
6476 <tt>debian/rules</tt> like this:
6478 ln -s ../man7/undocumented.7.gz \
6479 debian/tmp/usr/share/man/man[1-9]/the_requested_manpage.[1-9].gz
6481 This manpage claims that the lack of a manpage has been
6482 reported as a bug, so you may only do this if it really has
6483 (you can report it yourself, if you like). Do not close the
6484 bug report until a proper manpage is available.</p>
6487 You may forward a complaint about a missing manpage to the
6488 upstream authors, and mark the bug as forwarded in the
6489 Debian bug tracking system. Even though the GNU Project do
6490 not in general consider the lack of a manpage to be a bug,
6491 we do--if they tell you that they don't consider it a bug
6492 you should leave the bug in our bug tracking system open
6496 Manual pages should be installed compressed using <tt>gzip
6500 If one manpage needs to be accessible via several names it
6501 is better to use a symbolic link than the <tt>.so</tt>
6502 feature, but there is no need to fiddle with the relevant
6503 parts of the upstream source to change from <tt>.so</tt> to
6504 symlinks--don't do it unless it's easy. You should not create hard
6505 links in the manual page directories, nor put
6506 absolute filenames in <tt>.so</tt> directives. The filename
6507 in a <tt>.so</tt> in a manpage should be relative to the
6508 base of the manpage tree (usually
6509 <tt>/usr/share/man</tt>).</p></sect>
6513 <heading>Info documents</heading>
6516 Info documents should be installed in <tt>/usr/share/info</tt>.
6517 They should be compressed with <tt>gzip -9</tt>.</p>
6520 Your package should call <prgn>install-info</prgn> to update the Info
6522 file, in its post-installation script:
6524 install-info --quiet --section Development Development \
6525 /usr/share/info/foobar.info
6529 It is a good idea to specify a section for the location of
6530 your program; this is done with the <tt>--section</tt>
6531 switch. To determine which section to use, you should look
6532 at <tt>/usr/share/info/dir</tt> on your system and choose the most
6533 relevant (or create a new section if none of the current
6534 sections are relevant). Note that the <tt>--section</tt>
6535 flag takes two arguments; the first is a regular expression
6536 to match (case-insensitively) against an existing section,
6537 the second is used when creating a new one.</p>
6540 You should remove the entries in the pre-removal script:
6542 install-info --quiet --remove /usr/share/info/foobar.info
6546 If <prgn>install-info</prgn> cannot find a description entry
6547 in the Info file you must supply one. See <manref
6548 name="install-info" section="8"> for details.</p>
6552 <heading>Additional documentation</heading>
6555 Any additional documentation that comes with the package may
6556 be installed at the discretion of the package maintainer.
6557 Text documentation should be installed in a directory
6558 <tt>/usr/share/doc/<var>package</var></tt>, where
6559 <var>package</var> is the name of the package, and
6560 compressed with <tt>gzip -9</tt> unless it is small.</p>
6563 If a package comes with large amounts of documentation which
6564 many users of the package will not require you should create
6565 a separate binary package to contain it, so that it does not
6566 take up disk space on the machines of users who do not need
6567 or want it installed.</p>
6570 It is often a good idea to put text information files
6571 (<tt>README</tt>s, changelogs, and so forth) that come with
6572 the source package in <tt>/usr/share/doc/<var>package</var></tt>
6573 in the binary package. However, you don't need to install
6574 the instructions for building and installing the package, of
6578 Files in <tt>/usr/share/doc</tt> should not be referenced by
6579 any program, and the system administrator should be able to
6580 delete them without causing any programs to break. Any files
6581 that are referenced by programs but are also useful as
6582 standalone documentation should be installed under
6583 <tt>/usr/share/<package>/</tt> and symlinked in
6584 <tt>/usr/share/doc/<package>/</tt>.
6590 <heading>Accessing the documentation</heading>
6593 Former Debian releases placed all additional documentation
6594 in <tt>/usr/doc/<var>package</var></tt>. To realize a
6596 <tt>/usr/share/doc/<var>package</var></tt>, each package
6597 must maintain a symlink <tt>/usr/doc/<var>package</var></tt>
6598 that points to the new location of its documentation in
6599 <tt>/usr/share/doc/<var>package</var></tt><footnote>These
6600 symlinks will be removed in the future, but they have to be
6601 there for compatibility reasons until all packages have
6602 moved and the policy is changed accordingly.</footnote>.
6603 The symlink must be created when the package is installed;
6604 it cannot be contained in the package itself due to problems
6605 with <prgn>dpkg</prgn>. One reasonable way to accomplish
6606 this is to put the following in the package's
6607 <prgn>postinst</prgn>:
6609 if [ "$1" = "configure" ]; then
6610 if [ -d /usr/doc -a ! -e /usr/doc/#PACKAGE# \
6611 -a -d /usr/share/doc/#PACKAGE# ]; then
6612 ln -sf ../share/doc/#PACKAGE# /usr/doc/#PACKAGE#
6616 And the following in the package's <prgn>prerm</prgn>:
6618 if [ \( "$1" = "upgrade" -o "$1" = "remove" \) \
6619 -a -L /usr/doc/#PACKAGE# ]; then
6620 rm -f /usr/doc/#PACKAGE#
6627 <heading>Preferred documentation formats</heading>
6630 The unification of Debian documentation is being carried out
6634 If your package comes with extensive documentation in a
6635 mark up format that can be converted to various other formats
6636 you should if possible ship HTML versions in a binary
6637 package, in the directory
6638 <tt>/usr/share/doc/<var>appropriate package</var></tt> or its
6641 <p>The rationale: The important thing here is that HTML
6642 docs should be available in <em>some</em> package, not
6643 necessarily in the main binary package, though. </p>
6648 Other formats such as PostScript may be provided at your
6652 <sect id="copyrightfile">
6653 <heading>Copyright information</heading>
6656 Every package must be accompanied by a verbatim copy of its
6657 copyright and distribution license in the file
6658 /usr/share/doc/<package-name>/copyright. This file must
6659 neither be compressed nor be a symbolic link.</p>
6662 In addition, the copyright file must say where the upstream
6663 sources (if any) were obtained, and should explain briefly what
6664 modifications were made in the Debian version of the package
6665 compared to the upstream one. It should name the original
6666 authors of the package and the Debian maintainer(s) who were
6667 involved with its creation.</p>
6670 A copy of the file which will be installed in
6671 <tt>/usr/share/doc/<var>package</var>/copyright</tt> should be
6672 in <tt>debian/copyright</tt>.</p>
6676 /usr/share/doc/<package-name> may be a symbolic link to a
6677 directory in /usr/share/doc only if two packages both come from
6678 the same source and the first package has a "Depends"
6679 relationship on the second. These rules are important
6680 because copyrights must be extractable by mechanical
6684 Packages distributed under the UCB BSD license, the Artistic
6685 license, the GNU GPL, and the GNU LGPL should refer to the
6686 files /usr/share/common-licenses/BSD,
6687 /usr/share/common-licenses/Artistic,
6688 /usr/share/common-licenses/GPL, and
6689 /usr/share/common-licenses/LGPL.
6692 Why "licenses" and not "copyright"? Because
6693 <tt>/usr/doc/copyright</tt> used to contain all the
6694 copyright files, plus the four common licenses GPL,
6695 LGPL, Artistic and BSD. Now individual copyright files
6696 for packages are no longer in a common directory. Once
6697 <tt>/usr/doc/copyright</tt> is almost empty it makes
6698 sense to rename "copyright" to "licenses"
6701 Why "common-licenses" and not "licenses"? Because if I
6702 put just "licenses" I'm sure I will receive a bug report
6703 saying "license foo is not included in the licenses
6704 directory. They are not all the licenses, just a few
6705 common ones. I could use /usr/share/doc/common-licenses
6706 but I think this is too long, and, after all, the GPL
6707 does not "document" anything, it is merely a license.
6713 You should not use the copyright file as a general <tt>README</tt>
6714 file. If your package has such a file it should be
6715 installed in <tt>/usr/share/doc/<var>package</var>/README</tt> or
6716 <tt>README.Debian</tt> or some other appropriate place.</p>
6720 <heading>Examples</heading>
6723 Any examples (configurations, source files, whatever),
6724 should be installed in a directory
6725 <tt>/usr/share/doc/<var>package</var>/examples</tt>. These
6726 files should not be referenced by any program--they're there
6727 for the benefit of the system administrator and users, as
6728 documentation only. Architecture-specific example files
6729 should be installed in a directory
6730 <tt>/usr/lib/<var>package</var>/examples</tt>, and files in
6731 <tt>/usr/share/doc/<var>package</var>/examples</tt> symlink
6732 to files in it. Or the latter directory may be a symlink to
6736 <sect id="instchangelog">
6737 <heading>Changelog files</heading>
6740 Packages that are not Debian-native must contain a copy of
6741 <tt>debian/changelog</tt> file from the Debian source tree
6742 in <tt>/usr/share/doc/<var>package</var></tt> as
6743 <tt>changelog.Debian.gz</tt>. If an upstream changelog is
6744 available, it should be accessible as
6745 <tt>/usr/share/doc/<var>package</var>/changelog.gz</tt> in
6746 plain text. If the upstream changelog is distributed in
6747 HTML, it should be made available in that form as
6748 <tt>/usr/share/doc/<var>package</var>/changelog.html.gz</tt>
6749 and the <tt>changelog.gz</tt> should be generated using, eg,
6750 <tt>lynx -dump -nolist</tt>. If the upstream changelog files
6751 do not already conform to this naming convention, then this
6752 may be achieved either by renaming the files, or adding a
6753 symbolic link, at the maintainer's discretion.
6756 Rationale: People should not have to look into two
6757 places for upstream changelogs merely because they are
6765 All these files should be installed compressed using <tt>gzip -9</tt>,
6766 as they will become large with time even if they start out
6771 If the package has only one changelog which is used both as
6772 the Debian changelog and the upstream one because there is
6773 no separate upstream maintainer then that changelog should
6774 usually be installed as
6775 <tt>/usr/share/doc/<var>package</var>/changelog.gz</tt>; if
6776 there is a separate upstream maintainer, but no upstream
6777 changelog, then the Debian changelog should still be called
6778 <tt>changelog.Debian.gz</tt>.</p>