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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
48 the operating system, as well as technical requirements that
49 each package must satisfy to be included in the distribution.
50 The policy package itself is maintained by a group of
51 maintainers that have no editorial powers. The current list
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
90 obtain it by writing to the Free Software Foundation, Inc.,
91 59 Temple Place - Suite 330, 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.<footnote>
120 Informally, the criteria used for inclusion is that the
121 material meet one of the following requirements:
122 <taglist compact="compact">
123 <tag>Standard interfaces</tag>
126 The material presented represents an interface to
127 the packaging system that is mandated for use, and
128 is used by, a significant number of packages, and
129 therefore should not be changed without peer
130 review. Package maintainers can then rely on this
131 interfaces not changing, and the package
132 management software authors need to ensure
133 compatibility with these interface
134 definitions. (Control file and changelog file
135 formats are examples.)
138 <tag>Chosen Convention</tag>
141 If there are a number of technically viable choices
142 that can be made, but one needs to select one of
143 these options for inter-operability. The version
144 number format is one example.
148 Please note that these are not mutually exclusive;
149 selected conventions often become parts of standard
156 The footnotes present in this manual are
157 merely informative, and are not part of Debian policy itself.
162 In this manual, the words <em>must</em>, <em>should</em> and
163 <em>may</em>, and the adjectives <em>required</em>,
164 <em>recommended</em> and <em>optional</em>, are used to
165 distinguish the significance of the various guidelines in
166 this policy document. Packages that do not conform to the
167 guidelines denoted by <em>must</em> (or <em>required</em>)
168 will generally not be considered acceptable for the Debian
169 distribution. Non-conformance with guidelines denoted by
170 <em>should</em> (or <em>recommended</em>) will generally be
171 considered a bug, but will not necessarily render a package
172 unsuitable for distribution. Guidelines denoted by
173 <em>may</em> (or <em>optional</em>) are truly optional and
174 adherence is left to the maintainer's discretion.
177 These classifications are roughly equivalent to the bug
178 severities <em>serious</em> (for <em>must</em> or
179 <em>required</em> directive violations), <em>minor</em>,
180 <em>normal</em> or <em>important</em>
181 (for <em>should</em> or <em>recommended</em> directive
182 violations) and <em>wishlist</em> (for <em>optional</em>
184 <p>Compare RFC 2119. Note, however, that these words are
185 used in a different way in this document.</p>
189 Much of the information presented in this manual will be
190 useful even when building a package which is to be
191 distributed in some other way or is intended for local use
196 <heading>New versions of this document</heading>
198 The current version of this document is always accessible
199 from the Debian FTP server <ftpsite>ftp.debian.org</ftpsite>
201 <ftppath>/debian/doc/package-developer/policy.txt.gz</ftppath>
202 (also available from the same directory are several other
203 formats: <tt>policy.html.tar.gz</tt>, <tt>policy.pdf.gz</tt>
204 and <tt>policy.ps.gz</tt>) or from the <url
205 id="http://www.debian.org/doc/debian-policy/" name="Debian
206 Policy Manual"> webpage.</p>
209 In addition, this manual is distributed via the Debian package
210 <tt>debian-policy</tt>.
214 The <tt>debian-policy</tt> package also includes the file
215 <tt>upgrading-checklist.txt</tt> which indicates policy
216 changes between versions of this document.
220 <heading>Feedback</heading>
223 As the Debian GNU/Linux system is continuously evolving this
227 While the authors of this document have tried hard to avoid
228 typos and other errors, these do still occur. If you discover
229 an error in this manual or if you want to give any
230 comments, suggestions, or criticisms please send an email to
231 the Debian Policy List,
232 <email>debian-policy@lists.debian.org</email>, or submit a
233 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.<footnote>
542 It is possible that there are policy
543 requirements which the package is unable to
544 meet, for example, if the source is
545 unavailable. These situations will need to be
546 handled on a case-by-case basis.
556 <heading>The non-US sections</heading>
558 Some programs with cryptographic program code need to be
559 stored on the <em>non-US</em> server because of United
560 States export restrictions. Such programs must be
561 distributed in the appropriate <em>non-US</em> section,
562 either <em>non-US/main</em>, <em>non-US/contrib</em> or
563 <em>non-US/non-free</em>.
566 This applies only to packages which contain cryptographic
567 code. A package containing a program with an interface to
568 a cryptographic program or a program that's dynamically
569 linked against a cryptographic library should not be
570 distributed via the <em>non-US</em> server if it is
571 capable of running without the cryptographic library or
576 <heading>Further copyright considerations</heading>
578 Every package must be accompanied by a verbatim copy of
579 its copyright and distribution license in the file
580 <tt>/usr/share/doc/<var>package</var>/copyright</tt>
581 (see <ref id="copyrightfile"> for further details).
584 We reserve the right to restrict files from being included
585 anywhere in our archives if
586 <list compact="compact">
589 their use or distribution would break a law,
594 there is an ethical conflict in their distribution or
600 we would have to sign a license for them, or
605 their distribution would conflict with other project
613 Programs whose authors encourage the user to make
614 donations are fine for the main distribution, provided
615 that the authors do not claim that not donating is
616 immoral, unethical, illegal or something similar; in such
617 a case they must go in <em>non-free</em>.</p>
620 Packages whose copyright permission notices (or patent
621 problems) do not even allow redistribution of binaries
622 only, and where no special permission has been obtained,
623 must not be placed on the Debian FTP site and its mirrors
627 Note that under international copyright law (this applies
628 in the United States, too), <em>no</em> distribution or
629 modification of a work is allowed without an explicit
630 notice saying so. Therefore a program without a copyright
631 notice <em>is</em> copyrighted and you may not do anything
632 to it without risking being sued! Likewise if a program
633 has a copyright notice but no statement saying what is
634 permitted then nothing is permitted.</p>
637 Many authors are unaware of the problems that restrictive
638 copyrights (or lack of copyright notices) can cause for
639 the users of their supposedly-free software. It is often
640 worthwhile contacting such authors diplomatically to ask
641 them to modify their license terms. However, this can be a
642 politically difficult thing to do and you should ask for
643 advice on the <tt>debian-legal</tt> mailing list first, as
648 When in doubt about a copyright, send mail to
649 <email>debian-legal@lists.debian.org</email>. Be prepared
650 to provide us with the copyright statement. Software
651 covered by the GPL, public domain software and BSD-like
652 copyrights are safe; be wary of the phrases `commercial
653 use prohibited' and `distribution restricted'.
657 <heading>Subsections</heading>
660 The packages in the sections <em>main</em>,
661 <em>contrib</em> and <em>non-free</em> are grouped further
662 into <em>subsections</em> to simplify handling.
666 The section and subsection for each package should be
667 specified in the package's <tt>Section</tt> control
668 record. However, the maintainer of the Debian archive
669 may override this selection to ensure the consistency of
670 the Debian distribution. The <tt>Section</tt> field
671 should be of the form:
672 <list compact="compact">
675 <em>subsection</em> if the package is in the
676 <em>main</em> section,
681 <em>section/subsection</em> if the package is in
682 the <em>contrib</em> or <em>non-free</em> section,
688 <tt>non-US</tt>, <tt>non-US/contrib</tt> or
689 <tt>non-US/non-free</tt> if the package is in
690 <em>non-US/main</em>, <em>non-US/contrib</em> or
691 <em>non-US/non-free</em> respectively.
698 The Debian archive maintainers provide the authoritative
699 list of subsections. At present, they are:
700 <em>admin</em>, <em>base</em>, <em>comm</em>,
701 <em>contrib</em>, <em>devel</em>, <em>doc</em>,
702 <em>editors</em>, <em>electronics</em>, <em>games</em>,
703 <em>graphics</em>, <em>hamradio</em>,
704 <em>interpreters</em>, <em>libs</em>, <em>mail</em>,
705 <em>math</em>, <em>misc</em>, <em>net</em>, <em>news</em>,
706 <em>non-US</em>, <em>non-free</em>, <em>oldlibs</em>,
707 <em>otherosfs</em>, <em>science</em>, <em>shells</em>,
708 <em>sound</em>, <em>tex</em>, <em>text</em>,
709 <em>utils</em>, <em>web</em>, <em>x11</em>.
713 <heading>Priorities</heading>
716 Each package should have a <em>priority</em> value, which is
717 included in the package's <em>control record</em>. This
718 information is used by the Debian package management tools
719 to separate high-priority packages from less-important
723 The following <em>priority levels</em> are recognised by the
724 Debian package management tools.
726 <tag><tt>required</tt></tag>
729 Packages which are necessary for the proper
730 functioning of the system. You must not remove these
731 packages or your system may become totally broken and
732 you may not even be able to use <prgn>dpkg</prgn> to
733 put things back. Systems with only the
734 <tt>required</tt> packages are probably unusable, but
735 they do have enough functionality to allow the
736 sysadmin to boot and install more software.</p>
738 <tag><tt>important</tt></tag>
741 Important programs, including those which one would
742 expect to find on any Unix-like system. If the
743 expectation is that an experienced Unix person who
744 found it missing would say `What on earth is going on,
745 where is <prgn>foo</prgn>?', it must be an
746 <tt>important</tt> package.<footnote>
748 This is an important criterion because we are
749 trying to produce, amongst other things, a free
753 Other packages without which the system will not run
754 well or be usable must also have priority
755 <tt>important</tt>. This does
756 <em>not</em> include Emacs, the X Window System, TeX
757 or any other large applications. The
758 <tt>important</tt> packages are just a bare minimum of
759 commonly-expected and necessary tools.</p>
761 <tag><tt>standard</tt></tag>
764 These packages provide a reasonably small but not too
765 limited character-mode system. This is what will be
766 installed by default if the user doesn't select anything
767 else. It doesn't include many large applications, but
768 it does include Emacs (this is more of a piece of
769 infrastructure than an application) and a reasonable
770 subset of TeX and LaTeX.</p>
772 <tag><tt>optional</tt></tag>
775 (In a sense everything that isn't required is
776 optional, but that's not what is meant here.) This is
777 all the software that you might reasonably want to
778 install if you didn't know what it was and don't have
779 specialized requirements. This is a much larger system
780 and includes the X Window System, a full TeX
781 distribution, and many applications. Note that
782 optional packages should not conflict with each other.
785 <tag><tt>extra</tt></tag>
788 This contains all packages that conflict with others
789 with required, important, standard or optional
790 priorities, or are only likely to be useful if you
791 already know what they are or have specialised
798 Packages must not depend on packages with lower priority
799 values (excluding build-time dependencies). In order to
800 ensure this, the priorities of one or more packages may need
806 <heading>Binary packages</heading>
809 The Debian GNU/Linux distribution is based on the Debian
810 package management system, called <prgn>dpkg</prgn>. Thus,
811 all packages in the Debian distribution must be provided
812 in the <tt>.deb</tt> file format.</p>
816 <heading>The package name</heading>
819 Every package must have a name that's unique within the Debian
823 Package names must consist of lower case letters
824 (<tt>a-z</tt>), digits (<tt>0-9</tt>), plus (<tt>+</tt>)
825 and minus (<tt>-</tt>) signs, and periods (<tt>.</tt>).
826 They must be at least two characters long and must contain
831 The package name is part of the file name of the
832 <tt>.deb</tt> file and is included in the control field
838 <heading>The maintainer of a package</heading>
840 Every package must have a Debian maintainer (the
841 maintainer may be one person or a group of people
842 reachable from a common email address, such as a mailing
843 list). The maintainer is responsible for ensuring that
844 the package is placed in the appropriate distributions.
848 The maintainer must be specified in the
849 <tt>Maintainer</tt> control field with their correct name
850 and a working email address. If one person maintains
851 several packages, he/she should try to avoid having
852 different forms of their name and email address in
853 the <tt>Maintainer</tt> fields of those packages.
857 If the maintainer of a package quits from the Debian
858 project, "Debian QA Group"
859 <email>packages@qa.debian.org</email> takes over the
860 maintainership of the package until someone else
861 volunteers for that task. These packages are called
862 <em>orphaned packages</em>.<footnote>
864 The detailed procedure for doing this gracefully can
865 be found in the Debian Developer's Reference, either
866 in the <tt>developers-reference</tt> package, or on
867 the Debian FTP server
868 <ftpsite>ftp.debian.org</ftpsite> as
869 <ftppath>/debian/doc/package-developer/developers-reference.txt.gz</ftppath>
871 id="http://www.debian.org/doc/packaging-manuals/developers-reference/"
872 name="Debian Developer's Reference"> webpage.
880 <heading>The description of a package</heading>
883 Every Debian package must have an extended description
884 stored in the appropriate field of the control record.</p>
887 The description should be written so that it gives the
888 system administrator enough information to decide whether
889 to install the package. This description should not just
890 be copied verbatim from the program's documentation.
891 Instructions for configuring or using the package should
892 not be included (that is what installation scripts,
893 manual pages, info files, etc., are for). Copyright
894 statements and other administrivia should not be included
895 either (that is what the copyright file is for).
901 <heading>Dependencies</heading>
904 Every package must specify the dependency information
905 about other packages that are required for the first to
909 For example, a dependency entry must be provided for any
910 shared libraries required by a dynamically-linked executable
911 binary in a package.</p>
914 Packages are not required to declare any dependencies they
915 have on other packages which are marked <tt>Essential</tt>
916 (see below), and should not do so unless they depend on a
917 particular version of that package.</p>
920 Sometimes, a package requires another package to be installed
921 <em>and</em> configured before it can be installed. In this
922 case, you must specify a <tt>Pre-Depends</tt> entry for
926 You should not specify a <tt>Pre-Depends</tt> entry for a
927 package before this has been discussed on the
928 <tt>debian-devel</tt> mailing list and a consensus about
929 doing that has been reached.</p></sect1>
933 <heading>Virtual packages</heading>
936 Sometimes, there are several packages which offer
937 more-or-less the same functionality. In this case, it's
938 useful to define a <em>virtual package</em> whose name
939 describes that common functionality. (The virtual
940 packages only exist logically, not physically; that's why
941 they are called <em>virtual</em>.) The packages with this
942 particular function will then <em>provide</em> the virtual
943 package. Thus, any other package requiring that function
944 can simply depend on the virtual package without having to
945 specify all possible packages individually.</p>
948 All packages should use virtual package names where
949 appropriate, and arrange to create new ones if necessary.
950 They should not use virtual package names (except privately,
951 amongst a cooperating group of packages) unless they have
952 been agreed upon and appear in the list of virtual package
956 The latest version of the authoritative list of virtual
957 package names can be found on
958 <ftpsite>ftp.debian.org</ftpsite> in
959 <ftppath>/debian/doc/package-developer/virtual-package-names-list.txt</ftppath>
960 or your local mirror. In addition, it is included in the
961 <tt>debian-policy</tt> package. The procedure for updating
962 the list is described at the top of the file.</p></sect1>
966 <heading>Base packages</heading>
969 The packages included in the <tt>base</tt> section have a
970 special function. They form a minimum subset of the Debian
971 GNU/Linux system that is installed before everything else
972 on a new system. Thus, only very few packages are allowed
973 to go into the <tt>base</tt> section to keep the required
974 disk usage very small.</p>
977 Most of these packages will have the priority value
978 <tt>required</tt> or at least <tt>important</tt>, and many
979 of them will be tagged <tt>essential</tt> (see below).</p>
982 You must not place any packages into the <tt>base</tt>
983 section before this has been discussed on the
984 <tt>debian-devel</tt> mailing list and a consensus about
985 doing that has been reached.</p></sect1>
989 <heading>Essential packages</heading>
992 Some packages are tagged <tt>essential</tt>. (They have
993 <tt>Essential: yes</tt> in their package control record.)
994 This flag is used for packages that are <em>essential</em>
998 Since these packages cannot be easily removed (one has to
999 specify an extra <em>force option</em> to
1000 <prgn>dpkg</prgn> to do so), this flag must not be used
1001 unless absolutely necessary. A shared library package
1002 must not be tagged <tt>essential</tt>; dependencies will
1003 prevent its premature removal, and we need to be able to
1004 remove it when it has been superseded.
1008 Since dpkg will not prevent upgrading of other packages
1009 while an <tt>essential</tt> package is in an unconfigured
1010 state, all <tt>essential</tt> packages must supply all of
1011 their core functionality even when unconfigured. If the
1012 package cannot satisfy this requirement it must not be
1013 tagged as essential, and any packages depending on this
1014 package must instead have explicit dependency fields as
1019 You must not tag any packages <tt>essential</tt> before
1020 this has been discussed on the <tt>debian-devel</tt>
1021 mailing list and a consensus about doing that has been
1026 <sect1 id="maintscripts">
1027 <heading>Maintainer scripts</heading>
1030 The package installation scripts should avoid producing
1031 output which it is unnecessary for the user to see and
1032 should rely on <prgn>dpkg</prgn> to stave off boredom on
1033 the part of a user installing many packages. This means,
1034 amongst other things, using the <tt>--quiet</tt> option on
1035 <prgn>install-info</prgn>.</p>
1038 Errors which occur during the execution of an installation
1039 script must be checked and the installation must not
1040 continue after an error.
1044 Note that in general <ref id="scripts"> applies to package
1045 maintainer scripts, too.
1049 You should not use <tt>dpkg-divert</tt> on a file
1050 belonging to another package without consulting the
1051 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 <tt>Conflicts</tt> 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 <tt>debconf_specification</tt> 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.<footnote>
1086 4% of Debian packages [see <url
1087 id="http://kitenet.net/programs/debconf/stats/"
1088 name="Debconf stats">] currently use
1089 <package>debconf</package> to prompt the user at
1090 install time, and this number is growing daily. The
1091 benefits of using debconf are briefly explained at
1093 id="http://kitenet.net/doc/debconf-doc/introduction.html"
1094 name="Debconf introduction">; they include
1095 preconfiguration, (mostly) noninteractive
1096 installation, elimination of redundant prompting,
1097 consistency of user interface, etc.
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 <prgn>config</prgn> script and a <tt>templates</tt>
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.<footnote>
1123 <package>Debconf</package> or another tool that
1124 implements the Debian Configuration management
1125 specification will also be installed, and any
1126 versioned dependencies on it will be satisfied
1127 before preconfiguration begins.
1133 Packages should try to minimize the amount of prompting
1134 they need to do, and they should ensure that the user
1135 will only ever be asked each question once. This means
1136 that packages should try to use appropriate shared
1137 configuration files (such as <tt>/etc/papersize</tt> and
1138 <tt>/etc/news/server</tt>), and shared
1139 <package>debconf</package> variables rather than each
1140 prompting for their own list of required pieces of
1145 It also means that an upgrade should not ask the same
1146 questions again, unless the user has used <tt>dpkg
1147 --purge</tt> to remove the package's configuration. The
1148 answers to configuration questions should be stored in an
1149 appropriate place in <tt>/etc</tt> so that the user can
1150 modify them, and how this has been done should be
1154 If a package has a vitally important piece of
1155 information to pass to the user (such as "don't run me
1156 as I am, you must edit the following configuration files
1157 first or you risk your system emitting badly-formatted
1158 messages"), it should display this in the
1159 <prgn>config</prgn> or <prgn>postinst</prgn> script and
1160 prompt the user to hit return to acknowledge the
1161 message. Copyright messages do not count as vitally
1162 important (they belong in
1163 <tt>/usr/share/doc/<var>package</var>/copyright</tt>);
1164 neither do instructions on how to use a program (these
1165 should be in on-line documentation, where all the users
1169 Any necessary prompting should almost always be confined
1170 to the <prgn>config</prgn> or <prgn>postinst</prgn>
1171 script. If it is done in the <prgn>postinst</prgn>, it
1172 should be protected with a conditional so that
1173 unnecessary prompting doesn't happen if a package's
1174 installation fails and the <prgn>postinst</prgn> is
1175 called with <tt>abort-upgrade</tt>,
1176 <tt>abort-remove</tt> or <tt>abort-deconfigure</tt>.</p>
1181 <heading>Source packages</heading>
1183 <sect1 id="standardsversion">
1184 <heading>Standards conformance</heading>
1187 In the source package's <tt>Standards-Version</tt> control
1188 field, you should specify the most recent version number
1189 of this policy document with which your package complied
1190 when it was last updated. The current version number is
1195 This information may be used to file bug reports
1196 automatically if your package becomes too much out of
1201 The version number has four components: major and minor
1202 version number and major and minor patch level. When the
1203 standards change in a way that requires every package to
1204 change the major number will be changed. Significant
1205 changes that will require work in many packages will be
1206 signaled by a change to the minor number. The major patch
1207 level will be changed for any change to the meaning of the
1208 standards, however small; the minor patch level will be
1209 changed when only cosmetic, typographical or other edits
1210 are made which neither change the meaning of the document
1211 nor affect the contents of packages.</p>
1214 Thus only the first three components of the policy version
1215 are significant in the <em>Standards-Version</em> control
1216 field, and so either these three components or the all
1217 four components may be specified.<footnote>
1219 In the past, people specified the full version number
1220 in the Standards-Version field, for example `2.3.0.0'.
1221 Since minor patch-level changes don't introduce new
1222 policy, it was thought it would be better to relax
1223 policy and only require the first 3 components to be
1224 specified, in this example `2.3.0'. All four
1225 components may still be used if someone wishes to do
1232 You should regularly, and especially if your package has
1233 become out of date, check for the newest Policy Manual
1234 available and update your package, if necessary. When your
1235 package complies with the new standards you should update the
1236 <tt>Standards-Version</tt> source package field and
1237 release it.<footnote>
1239 See the file <tt>upgrading-checklist</tt> for
1240 information about policy which has changed between
1241 different versions of this document.
1249 <heading>Package relationships</heading>
1252 Source packages should specify which binary packages they
1253 require to be installed or not to be installed in order to
1254 build correctly. For example, if building a package
1255 requires a certain compiler, then the compiler should be
1256 specified as a build-time dependency.
1260 It is not necessary to explicitly specify build-time
1261 relationships on a minimal set of packages that are always
1262 needed to compile, link and put in a Debian package a
1263 standard "Hello World!" program written in C or C++. The
1264 required packages are called <em>build-essential</em>, and
1265 an informational list can be found in
1266 <tt>/usr/share/doc/build-essential/list</tt> (which is
1267 contained in the <tt>build-essential</tt>
1270 <list compact="compact">
1272 <p>This allows maintaining the list separately
1273 from the policy documents (the list does not
1274 need the kind of control that the policy
1280 Having a separate package allows one to install
1281 the build-essential packages on a machine, as
1282 well as allowing other packages such as task
1283 packages to require installation of the
1284 build-essential packages using the depends
1290 The separate package allows bug reports against
1291 the list to be categorized separately from
1292 the policy management process in the BTS.
1302 When specifying the set of build-time dependencies, one
1303 should list only those packages explicitly required by the
1304 build. It is not necessary to list packages which are
1305 required merely because some other package in the list of
1306 build-time dependencies depends on them.<footnote>
1308 The reason for this is that dependencies change, and
1309 you should list all those packages, and <em>only</em>
1310 those packages that <em>you</em> need directly. What
1311 others need is their business. For example, if you
1312 only link against <tt>libimlib</tt>, you will need to
1313 build-depend on <package>libimlib2-dev</package> but
1314 not against any <tt>libjpeg*</tt> packages, even
1315 though <tt>libimlib2-dev</tt> currently depends on
1316 them: installation of <package>libimlib2-dev</package>
1317 will automatically ensure that all of its run-time
1318 dependencies are satisfied.
1324 If build-time dependencies are specified, it must be
1325 possible to build the package and produce working binaries
1326 on a system with only essential and build-essential
1327 packages installed and also those required to satisfy the
1328 build-time relationships (including any implied
1329 relationships). In particular, this means that version
1330 clauses should be used rigorously in build-time
1331 relationships so that one cannot produce bad or
1332 inconsistently configured packages when the relationships
1333 are properly satisfied.
1337 <heading>Changes to the upstream sources</heading>
1340 If changes to the source code are made that are not
1341 specific to the needs of the Debian system, they should be
1342 sent to the upstream authors in whatever form they prefer
1343 so as to be included in the upstream version of the
1347 If you need to configure the package differently for
1348 Debian or for Linux, and the upstream source doesn't
1349 provide a way to do so, you should add such configuration
1350 facilities (for example, a new <prgn>autoconf</prgn> test
1351 or <tt>#define</tt>) and send the patch to the upstream
1352 authors, with the default set to the way they originally
1353 had it. You can then easily override the default in your
1354 <tt>debian/rules</tt> or wherever is appropriate.</p>
1357 You should make sure that the <prgn>configure</prgn> utility
1358 detects the correct architecture specification string
1359 (refer to <ref id="arch-spec"> for details).</p>
1362 If you need to edit a <prgn>Makefile</prgn> where
1363 GNU-style <prgn>configure</prgn> scripts are used, you
1364 should edit the <tt>.in</tt> files rather than editing the
1365 <prgn>Makefile</prgn> directly. This allows the user to
1366 reconfigure the package if necessary. You should
1367 <em>not</em> configure the package and edit the generated
1368 <prgn>Makefile</prgn>! This makes it impossible for
1369 someone else to later reconfigure the package.</p></sect1>
1373 <heading>Documenting your changes</heading>
1376 You should document your changes and updates to the source
1377 package properly in the <tt>debian/changelog</tt> file. (Note
1378 that mistakes in changelogs are usually best rectified by
1379 making a new changelog entry rather than "rewriting history"
1380 by editing old changelog entries.)</p>
1383 In non-experimental packages you must use a format for
1384 <tt>debian/changelog</tt> which is supported by the most
1385 recent released version of <prgn>dpkg</prgn>.<footnote>
1387 If you wish to use an alternative format, you may do
1388 so as long as you include a parser for it in your
1389 source package. The parser must have an API
1390 compatible with that expected by
1391 <prgn>dpkg-genchanges</prgn> and
1392 <prgn>dpkg-gencontrol</prgn>. If there is general
1393 interest in the new format, you should contact the
1394 <package>dpkg</package> maintainer to have the parser
1395 script for it included in the <prgn>dpkg</prgn>
1396 package. (You will need to agree that the parser and
1397 its manpage may be distributed under the GNU GPL, just
1398 as the rest of `dpkg' is.)
1406 <heading>Error trapping in makefiles</heading>
1409 When <prgn>make</prgn> invokes a command in a makefile
1410 (including your package's upstream makefiles and
1411 <tt>debian/rules</tt>), it does so using <tt>sh</tt>. This
1412 means that <tt>sh</tt>'s usual bad error handling
1413 properties apply: if you include a miniature script as one
1414 of the commands in your makefile you'll find that if you
1415 don't do anything about it then errors are not detected
1416 and <prgn>make</prgn> will blithely continue after
1420 Every time you put more than one shell command (this
1421 includes using a loop) in a makefile command you
1422 must make sure that errors are trapped. For
1423 simple compound commands, such as changing directory and
1424 then running a program, using <tt>&&</tt> rather
1425 than semicolon as a command separator is sufficient. For
1426 more complex commands including most loops and
1427 conditionals you should include a separate <tt>set -e</tt>
1428 command at the start of every makefile command that's
1429 actually one of these miniature shell scripts.</p></sect1>
1433 <heading>Obsolete constructs and libraries</heading>
1436 The include file <tt><varargs.h></tt> is
1437 provided to support end-users compiling very old software;
1438 the library <tt>libtermcap</tt> is provided to support the
1439 execution of software which has been linked against it
1440 (either old programs or those such as Netscape which are
1441 only available in binary form).</p>
1444 Debian packages should be patched to use
1445 <tt><stdarg.h></tt> and <tt>ncurses</tt>
1452 <chapt id="controlfields"><heading>Control files and their fields</heading>
1455 Many of the tools in the package management suite manipulate
1456 data represented in a common format, known as <em>control
1457 data</em>. The data is often stored in <em>control
1458 files</em>. Binary and source packages have control files,
1459 and the <tt>.changes</tt> files which control the installation
1460 of uploaded files are also in control file format.
1461 <prgn>Dpkg</prgn>'s internal databases are in a similar
1465 <sect id="controlsyntax"><heading>Syntax of control files</heading>
1468 A control file consists of one or more paragraphs of fields.
1469 The paragraphs are separated by blank lines. Some control
1470 files allow only one paragraph; others allow several, in
1471 which case each paragraph usually refers to a different
1472 package. (For example, in source packages, the first
1473 paragraph refers to the source package, and later paragraphs
1474 refer to binary packages generated from the source.)
1478 Each paragraph consists of a series of data fields; each
1479 field consists of the field name, followed by a colon and
1480 then the data/value associated with that field. It ends at
1481 the end of the line. Horizontal whitespace (spaces and
1482 tabs) may occur immediately before or after the value and is
1483 ignored there; it is conventional to put a single space
1484 after the colon. For example, a field might be:
1485 <example compact="compact">
1488 the field name is <tt>Package</tt> and the field value
1493 Some fields' values may span several lines; in this case
1494 each continuation line <em>must</em> start with a space or
1495 tab. Any trailing spaces or tabs at the end of individual
1496 lines of a field value are ignored.
1500 Except where otherwise stated only a single line of data is
1501 allowed and whitespace is not significant in a field body.
1502 Whitespace must not appear inside names (of packages,
1503 architectures, files or anything else) or version numbers,
1504 or between the characters of multi-character version
1509 Field names are not case-sensitive, but it is usual to
1510 capitalize the field names using mixed case as shown below.
1514 Blank lines, or lines consisting only of spaces and tabs,
1515 are not allowed within field values or between fields - that
1516 would mean a new paragraph.
1521 <sect><heading>List of fields</heading>
1523 This list here is not supposed to be exhaustive. Most fields
1524 are dealt with elsewhere in this document.
1526 <sect1 id="f-Package"><heading><tt>Package</tt>
1530 The name of the binary package. Package names consist of
1531 the alphanumerics and <tt>+</tt> <tt>-</tt> <tt>.</tt>
1532 (plus, minus and full stop).
1536 They must be at least two characters long and must start
1537 with an alphanumeric character and not be all digits. The
1538 use of lowercase package names is strongly recommended
1539 unless the package you're building (or referring to, in
1540 other fields) is already using uppercase.</p>
1543 <sect1 id="f-Version"><heading><tt>Version</tt>
1547 This lists the source or binary package's version number -
1548 see <ref id="versions">.
1554 id="f-Standards-Version"><heading><tt>Standards-Version</tt>
1558 The most recent version of the standards (the policy
1559 manual and associated texts) with which the package
1560 complies. This is updated manually when editing the
1561 source package to conform to newer standards; it can
1562 sometimes be used to tell when a package needs attention.
1563 Its format is described above; see
1564 <ref id="standardsversion">.
1569 <sect1 id="f-Distribution"><heading><tt>Distribution</tt>
1573 In a <tt>.changes</tt> file or parsed changelog output
1574 this contains the (space-separated) name(s) of the
1575 distribution(s) where this version of the package should
1576 be installed. Valid distributions are determined by the
1577 archive maintainers.<footnote>
1578 Current distribution names are:
1579 <taglist compact="compact">
1580 <tag><em>stable</em></tag>
1583 This is the current `released' version of Debian
1584 GNU/Linux. Once the distribution is
1585 <em>stable</em> only security fixes and other
1586 major bug fixes are allowed. When changes are
1587 made to this distribution, the release number is
1588 increased (for example: 2.2r1 becomes 2.2r2 then
1593 <tag><em>unstable</em></tag>
1596 This distribution value refers to the
1597 <em>developmental</em> part of the Debian
1598 distribution tree. New packages, new upstream
1599 versions of packages and bug fixes go into the
1600 <em>unstable</em> directory tree. Download from
1601 this distribution at your own risk.
1605 <tag><em>testing</em></tag>
1608 This distribution value refers to the
1609 <em>testing</em> part of the Debian distribution
1610 tree. It receives its packages from the
1611 unstable distribution after a short time lag to
1612 ensure that there are no major issues with the
1613 unstable packages. It is less prone to breakage
1614 than unstable, but still risky. It is not
1615 possible to upload packages directly to
1620 <tag><em>frozen</em></tag>
1623 From time to time, the <em>testing</em>
1624 distribution enters a state of `code-freeze' in
1625 anticipation of release as a <em>stable</em>
1626 version. During this period of testing only
1627 fixes for existing or newly-discovered bugs will
1628 be allowed. The exact details of this stage are
1629 determined by the Release Manager.
1633 <tag><em>experimental</em></tag>
1636 The packages with this distribution value are
1637 deemed by their maintainers to be high
1638 risk. Oftentimes they represent early beta or
1639 developmental packages from various sources that
1640 the maintainers want people to try, but are not
1641 ready to be a part of the other parts of the
1642 Debian distribution tree. Download at your own
1648 You should list <em>all</em> distributions that the
1649 package should be installed into.
1658 <chapt id="versions"><heading>Version numbering</heading>
1661 Every package has a version number recorded in its
1662 <tt>Version</tt> control file field.
1666 The package management system imposes an ordering on version
1667 numbers, so that it can tell whether packages are being up- or
1668 downgraded and so that package system front end applications
1669 can tell whether a package it finds available is newer than
1670 the one installed on the system. The version number format
1671 has the most significant parts (as far as comparison is
1672 concerned) at the beginning.
1676 The version number format is:
1677 [<var>epoch</var><tt>:</tt>]<var>upstream_version</var>[<tt>-</tt><var>debian_revision</var>]
1681 The three components here are:
1683 <tag><var>epoch</var></tag>
1686 This is a single (generally small) unsigned integer. It
1687 may be omitted, in which case zero is assumed. If it is
1688 omitted then the <var>upstream_version</var> may not
1693 It is provided to allow mistakes in the version numbers
1694 of older versions of a package, and also a package's
1695 previous version numbering schemes, to be left behind.
1699 <tag><var>upstream_version</var></tag>
1702 This is the main part of the version number. It is
1703 usually the version number of the original (`upstream')
1704 package from which the <tt>.deb</tt> file has been made,
1705 if this is applicable. Usually this will be in the same
1706 format as that specified by the upstream author(s);
1707 however, it may need to be reformatted to fit into the
1708 package management system's format and comparison
1713 The comparison behavior of the package management system
1714 with respect to the <var>upstream_version</var> is
1715 described below. The <var>upstream_version</var>
1716 portion of the version number is mandatory.
1720 The <var>upstream_version</var> may contain only
1721 alphanumerics<footnote>
1722 <p>Alphanumerics are <tt>A-Za-z0-9</tt> only.</p>
1724 and the characters <tt>.</tt> <tt>+</tt> <tt>-</tt>
1725 <tt>:</tt> (full stop, plus, hyphen, colon) and should
1726 start with a digit. If there is no
1727 <var>debian_revision</var> then hyphens are not allowed;
1728 if there is no <var>epoch</var> then colons are not
1732 <tag><var>debian_revision</var></tag>
1735 This part of the version number specifies the version of
1736 the Debian package based on the upstream version. It
1737 may contain only alphanumerics and the characters
1738 <tt>+</tt> and <tt>.</tt> (plus and full stop) and is
1739 compared in the same way as the
1740 <var>upstream_version</var> is.
1744 It is optional; if it isn't present then the
1745 <var>upstream_version</var> may not contain a hyphen.
1746 This format represents the case where a piece of
1747 software was written specifically to be turned into a
1748 Debian package, and so there is only one `debianization'
1749 of it and therefore no revision indication is required.
1753 It is conventional to restart the
1754 <var>debian_revision</var> at <tt>1</tt> each time the
1755 <var>upstream_version</var> is increased.
1759 The package management system will break the version
1760 number apart at the last hyphen in the string (if there
1761 is one) to determine the <var>upstream_version</var> and
1762 <var>debian_revision</var>. The absence of a
1763 <var>debian_revision</var> compares earlier than the
1764 presence of one (but note that the
1765 <var>debian_revision</var> is the least significant part
1766 of the version number).
1773 The <var>upstream_version</var> and <var>debian_revision</var>
1774 parts are compared by the package management system using the
1779 The strings are compared from left to right.
1783 First the initial part of each string consisting entirely of
1784 non-digit characters is determined. These two parts (one of
1785 which may be empty) are compared lexically. If a difference
1786 is found it is returned. The lexical comparison is a
1787 comparison of ASCII values modified so that all the letters
1788 sort earlier than all the non-letters.
1792 Then the initial part of the remainder of each string which
1793 consists entirely of digit characters is determined. The
1794 numerical values of these two parts are compared, and any
1795 difference found is returned as the result of the comparison.
1796 For these purposes an empty string (which can only occur at
1797 the end of one or both version strings being compared) counts
1802 These two steps (comparing and removing initial non-digit
1803 strings and initial digit strings) are repeated until a
1804 difference is found or both strings are exhausted.
1808 Note that the purpose of epochs is to allow us to leave behind
1809 mistakes in version numbering, and to cope with situations
1810 where the version numbering scheme changes. It is
1811 <em>not</em> intended to cope with version numbers containing
1812 strings of letters which the package management system cannot
1813 interpret (such as <tt>ALPHA</tt> or <tt>pre-</tt>), or with
1814 silly orderings (the author of this manual has heard of a
1815 package whose versions went <tt>1.1</tt>, <tt>1.2</tt>,
1816 <tt>1.3</tt>, <tt>1</tt>, <tt>2.1</tt>, <tt>2.2</tt>,
1817 <tt>2</tt> and so forth).
1821 If an upstream package has problematic version numbers they
1822 should be converted to a sane form for use in the
1823 <tt>Version</tt> field.
1827 <heading>Version numbers based on dates</heading>
1829 In general, Debian packages should use the same version
1830 numbers as the upstream sources.</p>
1833 However, in some cases where the upstream version number is
1834 based on a date (e.g., a development `snapshot' release) the
1835 package management system cannot handle these version
1836 numbers without epochs. For example, dpkg will consider
1837 `96May01' to be greater than `96Dec24'.</p>
1840 To prevent having to use epochs for every new upstream
1841 version, the version number should be changed to the
1842 following format in such cases: `19960501', `19961224'. It
1843 is up to the maintainer whether he/she wants to bother the
1844 upstream maintainer to change the version numbers upstream,
1848 Note that other version formats based on dates which are
1849 parsed correctly by the package management system should
1850 <em>not</em> be changed.</p>
1853 Native Debian packages (i.e., packages which have been
1854 written especially for Debian) whose version numbers include
1855 dates should always use the `YYYYMMDD' format.</p>
1859 <chapt id="miscellaneous"><heading>Packaging Considerations</heading>
1861 <sect id="timestamps"><heading>Time Stamps</heading>
1863 Maintainers should preserve the modification times of the
1864 upstream source files in a package, as far as is reasonably
1867 The rationale is that there is some information conveyed
1868 by knowing the age of the file, for example, you could
1869 recognize that some documentation is very old by looking
1870 at the modification time, so it would be nice if the
1871 modification time of the upstream source would be
1878 <sect id="debianrules"><heading><tt>debian/rules</tt> - the
1879 main building script</heading>
1882 This file must be an executable makefile, and contains the
1883 package-specific recipes for compiling the package and
1884 building binary package(s) from the source.
1888 It must start with the line <tt>#!/usr/bin/make -f</tt>,
1889 so that it can be invoked by saying its name rather than
1890 invoking <prgn>make</prgn> explicitly.
1894 Since an interactive <tt>debian/rules</tt> script makes it
1895 impossible to auto-compile that package and also makes it
1896 hard for other people to reproduce the same binary
1897 package, all <em>required targets</em> MUST be
1898 non-interactive. At a minimum, required targets are the
1899 ones called by <prgn>dpkg-buildpackage</prgn>, namely,
1900 <em>clean</em>, <em>binary</em>, <em>binary-arch</em>,
1901 <em>binary-indep</em>, and <em>build</em>. It also follows
1902 that any target that these targets depend on must also be
1907 The required and optional targets are as follows:
1909 <tag><tt>build</tt></tag>
1912 This should perform all non-interactive configuration
1913 and compilation of the package. If a package has an
1914 interactive pre-build configuration routine, the
1915 Debianized source package must either be built after
1916 this has taken place (so that the binary package can
1917 be built without rerunning the configuration) or the
1918 configuration routine modified to become
1919 non-interactive. (The latter is preferable if there
1920 are architecture-specific features detected by the
1921 configuration routine.)
1925 For some packages, notably ones where the same
1926 source tree is compiled in different ways to produce
1927 two binary packages, the <prgn>build</prgn> target
1928 does not make much sense. For these packages it is
1929 good enough to provide two (or more) targets
1930 (<tt>build-a</tt> and <tt>build-b</tt> or whatever)
1931 for each of the ways of building the package, and a
1932 <prgn>build</prgn> target that does nothing. The
1933 <prgn>binary</prgn> target will have to build the
1934 package in each of the possible ways and make the
1935 binary package out of each.
1939 The <prgn>build</prgn> target must not do anything
1940 that might require root privilege.
1944 The <prgn>build</prgn> target may need to run the
1945 <prgn>clean</prgn> target first - see below.
1949 When a package has a configuration and build routine
1950 which takes a long time, or when the makefiles are
1951 poorly designed, or when <prgn>build</prgn> needs to
1952 run <prgn>clean</prgn> first, it is a good idea to
1953 <tt>touch build</tt> when the build process is
1954 complete. This will ensure that if <tt>debian/rules
1955 build</tt> is run again it will not rebuild the whole
1958 Another common way to do this is for <prgn>build</prgn>
1959 to depend on <prgn>build-stamp</prgn> and to do
1960 nothing else, and for the <prgn>build-stamp</prgn>
1961 target to do the building and to <tt>touch
1962 build-stamp</tt> on completion. This is
1963 especially useful if the build routine creates a
1964 file or directory called <tt>build</tt>; in such a
1965 case, <prgn>build</prgn> will need to be listed as
1966 a phony target (i.e., as a dependency of the
1967 <tt>.PHONY</tt> target). See the documentation of
1968 <prgn>make</prgn> for more information on phony
1975 <tag><tt>binary</tt>, <tt>binary-arch</tt>,
1976 <tt>binary-indep</tt>
1980 The <prgn>binary</prgn> target must be all that is
1981 necessary for the user to build the binary package(s)
1982 produced from this source package. All of these
1983 targets are required to be non-interactive. It is
1984 split into two parts: <prgn>binary-arch</prgn> builds
1985 the binary packages which are specific to a particular
1986 architecture, and <prgn>binary-indep</prgn> builds
1987 those which are not.
1991 <prgn>binary</prgn> may be (and commonly is) a target
1992 with no commands which simply depends on
1993 <prgn>binary-arch</prgn> and
1994 <prgn>binary-indep</prgn>.
1998 Each <prgn>binary-*</prgn> target should depend on
1999 the <prgn>build</prgn> target, above, so that the
2000 package is built if it has not been already. It
2001 should then create the relevant binary package(s),
2002 using <prgn>dpkg-gencontrol</prgn> to make their
2003 control files and <prgn>dpkg-deb</prgn> to build
2004 them and place them in the parent of the top level
2009 Both the <prgn>binary-arch</prgn> and
2010 <prgn>binary-indep</prgn> targets <em>must</em> exist.
2011 If one of them has nothing to do (which will always be
2012 the case if the source generates only a single binary
2013 package, whether architecture-dependent or not), it
2014 must still exist and must always succeed.
2018 The <prgn>binary</prgn> targets must be invoked as
2021 The <prgn>fakeroot</prgn> package often allows one
2022 to build a package correctly even without being
2029 <tag><tt>clean</tt></tag>
2032 This must undo any effects that the <prgn>build</prgn>
2033 and <prgn>binary</prgn> targets may have had, except
2034 that it should leave alone any output files created in
2035 the parent directory by a run of a <prgn>binary</prgn>
2036 target. This target must be non-interactive.
2040 If a <prgn>build</prgn> file is touched at the end of
2041 the <prgn>build</prgn> target, as suggested above, it
2042 should be removed as the first action that
2043 <prgn>clean</prgn> performs, so that running
2044 <prgn>build</prgn> again after an interrupted
2045 <prgn>clean</prgn> doesn't think that everything is
2050 The <prgn>clean</prgn> target may need to be
2051 invoked as root if <prgn>binary</prgn> has been
2052 invoked since the last <prgn>clean</prgn>, or if
2053 <prgn>build</prgn> has been invoked as root (since
2054 <prgn>build</prgn> may create directories, for
2059 <tag><tt>get-orig-source</tt> (optional)</tag>
2062 This target fetches the most recent version of the
2063 original source package from a canonical archive site
2064 (via FTP or WWW, for example), does any necessary
2065 rearrangement to turn it into the original source
2066 tar file format described below, and leaves it in the
2071 This target may be invoked in any directory, and
2072 should take care to clean up any temporary files it
2077 This target is optional, but providing it if
2078 possible is a good idea.
2084 The <prgn>build</prgn>, <prgn>binary</prgn> and
2085 <prgn>clean</prgn> targets must be invoked with the current
2086 directory being the package's top-level directory.
2091 Additional targets may exist in <tt>debian/rules</tt>,
2092 either as published or undocumented interfaces or for the
2093 package's internal use.
2097 The architectures we build on and build for are determined
2098 by <prgn>make</prgn> variables using the utility
2099 <prgn>dpkg-architecture</prgn>. You can determine the
2100 Debian architecture and the GNU style architecture
2101 specification string for the build machine (the machine type
2102 we are building on) as well as for the host machine (the
2103 machine type we are building for). Here is a list of
2104 supported <prgn>make</prgn> variables:
2105 <list compact="compact">
2107 <p><tt>DEB_*_ARCH</tt> (the Debian architecture)</p>
2110 <p><tt>DEB_*_GNU_TYPE</tt> (the GNU style architecture
2111 specification string)</p>
2114 <p><tt>DEB_*_GNU_CPU</tt> (the CPU part of
2115 <tt>DEB_*_GNU_TYPE</tt>)</p>
2118 <p><tt>DEB_*_GNU_SYSTEM</tt> (the System part of
2119 <tt>DEB_*_GNU_TYPE</tt>)</p>
2121 where <tt>*</tt> is either <tt>BUILD</tt> for specification of
2122 the build machine or <tt>HOST</tt> for specification of the
2127 Backward compatibility can be provided in the rules file
2128 by setting the needed variables to suitable default
2129 values; please refer to the documentation of
2130 <prgn>dpkg-architecture</prgn> for details.
2134 It is important to understand that the <tt>DEB_*_ARCH</tt>
2135 string only determines which Debian architecture we are
2136 building on or for. It should not be used to get the CPU
2137 or system information; the GNU style variables should be
2142 <sect id="dpkgchangelog"><heading><tt>debian/changelog</tt>
2146 This file records the changes to the Debian-specific parts of the
2149 Though there is nothing stopping an author who is also
2150 the Debian maintainer from using it for all their
2151 changes, it will have to be renamed if the Debian and
2152 upstream maintainers become different people. In such a
2153 case, however, it might be better to maintain the
2154 package as a non-native package.
2160 It has a special format which allows the package building
2161 tools to discover which version of the package is being
2162 built and find out other release-specific information.
2166 That format is a series of entries like this:
2167 <example compact="compact">
2168 <var>package</var> (<var>version</var>) <var>distribution(s)</var>; urgency=<var>urgency</var>
2170 * <var>change details</var>
2171 <var>more change details</var>
2172 * <var>even more change details</var>
2174 -- <var>maintainer name</var> <<var>email address</var>> <var>date</var>
2179 <var>package</var> and <var>version</var> are the source
2180 package name and version number.
2184 <var>distribution(s)</var> lists the distributions where
2185 this version should be installed when it is uploaded - it
2186 is copied to the <tt>Distribution</tt> field in the
2187 <tt>.changes</tt> file. See <ref id="f-Distribution">.
2191 <var>urgency</var> is the value for the <tt>Urgency</tt>
2192 field in the <tt>.changes</tt> file for the upload. It is
2193 not possible to specify an urgency containing commas; commas
2194 are used to separate
2195 <tt><var>keyword</var>=<var>value</var></tt> settings in the
2196 <prgn>dpkg</prgn> changelog format (though there is
2197 currently only one useful <var>keyword</var>,
2198 <tt>urgency</tt>).<footnote>
2200 Recognised urgency values are <tt>low</tt>,
2201 <tt>medium</tt>, <tt>high</tt> and <tt>emergency</tt>.
2202 They have an effect on how quickly a package will be
2203 considered for inclusion into the <tt>testing</tt>
2204 distribution, and give an indication of the importance
2205 of any fixes included in this upload.
2211 The change details may in fact be any series of lines
2212 starting with at least two spaces, but conventionally each
2213 change starts with an asterisk and a separating space and
2214 continuation lines are indented so as to bring them in
2215 line with the start of the text above. Blank lines may be
2216 used here to separate groups of changes, if desired.
2220 If this upload resolves bugs recorded in the Bug Tracking
2221 System (BTS), they may be automatically closed on the
2222 inclusion of this package into the Debian archive by
2223 including the string: <tt>closes: Bug#<var>nnnnn</var></tt>
2224 in the change details.<footnote>
2226 To be precise, the string should match the following
2227 Perl regular expression:
2229 /closes:\s*(?:bug)?\#?\s?\d+(?:,\s*(?:bug)?\#?\s?\d+)*/i
2231 Then all of the bug numbers listed will be closed by the
2232 archive maintenance script (<prgn>katie</prgn>), or in
2233 the case of an NMU, marked as fixed.
2239 The maintainer name and email address used in the changelog
2240 should be the details of the person uploading <em>this</em>
2241 version. They are <em>not</em> necessarily those of the
2242 usual package maintainer. The information here will be
2243 copied to the <tt>Changed-By</tt> field in the
2244 <tt>.changes</tt> file, and then later used to send an
2245 acknowledgement when the upload has been installed.
2249 The <var>date</var> should be in RFC822 format<footnote>
2251 This is generated by the <prgn>822-date</prgn>
2254 </footnote>; it should include the time zone specified
2255 numerically, with the time zone name or abbreviation
2256 optionally present as a comment in parentheses.
2260 The first `title' line with the package name should start
2261 at the left hand margin; the `trailer' line with the
2262 maintainer and date details should be preceded by exactly
2263 one space. The maintainer details and the date must be
2264 separated by exactly two spaces.
2267 <sect1><heading>Defining alternative changelog formats</heading>
2270 It is possible to use a different format to the standard
2271 one, by providing a parser for the format you wish to
2275 A changelog parser must not interact with the user at
2281 <sect id="srcsubstvars"><heading><tt>debian/substvars</tt>
2282 and variable substitutions </heading>
2285 When <prgn>dpkg-gencontrol</prgn>,
2286 <prgn>dpkg-genchanges</prgn> and <prgn>dpkg-source</prgn>
2287 generate control files they perform variable substitutions
2288 on their output just before writing it. Variable
2289 substitutions have the form <tt>${<var>variable</var>}</tt>.
2290 The optional file <tt>debian/substvars</tt> contains
2291 variable substitutions to be used; variables can also be set
2292 directly from <tt>debian/rules</tt> using the <tt>-V</tt>
2293 option to the source packaging commands, and certain
2294 predefined variables are also available.
2298 The <tt>debian/substvars</tt> file is usually generated and
2299 modified dynamically by <tt>debian/rules</tt> targets; in
2300 this case it must be removed by the <prgn>clean</prgn>
2305 See <manref name="dpkg-source" section="1"> for full
2306 details about source variable substitutions, including the
2307 format of <tt>debian/substvars</tt>.</p>
2310 <sect id="debianfiles"><heading><tt>debian/files</tt>
2314 This file is not a permanent part of the source tree; it
2315 is used while building packages to record which files are
2316 being generated. <prgn>dpkg-genchanges</prgn> uses it
2317 when it generates a <tt>.changes</tt> file.
2321 It should not exist in a shipped source package, and so it
2322 (and any backup files or temporary files such as
2323 <tt>files.new</tt><footnote>
2325 <tt>files.new</tt> is used as a temporary file by
2326 <prgn>dpkg-gencontrol</prgn> and
2327 <prgn>dpkg-distaddfile</prgn> - they write a new
2328 version of <tt>files</tt> here before renaming it,
2329 to avoid leaving a corrupted copy if an error
2332 </footnote>) should be removed by the
2333 <prgn>clean</prgn> target. It may also be wise to
2334 ensure a fresh start by emptying or removing it at the
2335 start of the <prgn>binary</prgn> target.
2339 When <prgn>dpkg-gencontrol</prgn> is run for a binary
2340 package, it adds an entry to <tt>debian/files</tt> for the
2341 <tt>.deb</tt> file that will be created when <tt>dpkg-deb
2342 --build</tt> is run for that binary package. So for most
2343 packages all that needs to be done with this file is to
2344 delete it in the <prgn>clean</prgn> target.
2348 If a package upload includes files besides the source
2349 package and any binary packages whose control files were
2350 made with <prgn>dpkg-gencontrol</prgn> then they should be
2351 placed in the parent of the package's top-level directory
2352 and <prgn>dpkg-distaddfile</prgn> should be called to add
2353 the file to the list in <tt>debian/files</tt>.</p>
2356 <sect id="restrictions"><heading>Restrictions on objects in source packages
2360 The source package may not contain any hard links<footnote>
2362 This is not currently detected when building source
2363 packages, but only when extracting
2367 Hard links may be permitted at some point in the
2368 future, but would require a fair amount of
2371 </footnote>, device special files, sockets or setuid or
2372 setgid files.<footnote>
2374 Setgid directories are allowed.
2379 <sect id="descriptions"><heading>Descriptions of packages - the
2380 <tt>Description</tt> field </heading>
2383 The description is intended to describe the program to a user
2384 who has never met it before so that they know whether they
2385 want to install it. It should also give information about the
2386 significant dependencies and conflicts between this package
2387 and others, so that the user knows why these dependencies and
2388 conflicts have been declared.
2391 <sect1><heading>Notes about writing descriptions
2395 The single line synopsis should be kept brief - certainly
2396 under 80 characters.
2400 Do not include the package name in the synopsis line. The
2401 display software knows how to display this already, and you
2402 do not need to state it. Remember that in many situations
2403 the user may only see the synopsis line - make it as
2404 informative as you can.
2408 Do not try to continue the single line synopsis into the
2409 extended description. This will not work correctly when
2410 the full description is displayed, and makes no sense
2411 where only the summary (the single line synopsis) is
2416 The extended description should describe what the package
2417 does and how it relates to the rest of the system (in terms
2418 of, for example, which subsystem it is which part of).
2422 The description field needs to make sense to anyone, even
2423 people who have no idea about any of the things the
2424 package deals with.<footnote>
2426 The blurb that comes with a program in its
2427 announcements and/or <prgn>README</prgn> files is
2428 rarely suitable for use in a description. It is
2429 usually aimed at people who are already in the
2430 community where the package is used.
2436 Put important information first, both in the synopsis and
2437 extended description. Sometimes only the first part of the
2438 synopsis or of the description will be displayed. You can
2439 assume that there will usually be a way to see the whole
2440 extended description.
2444 You may include information about dependencies and so forth
2445 in the extended description, if you wish.
2449 Do not use tab characters. Their effect is not predictable.
2457 <chapt id="maintainerscripts"><heading>Package maintainer scripts
2458 and installation procedure
2461 <sect><heading>Introduction to package maintainer scripts
2465 It is possible to supply scripts as part of a package which
2466 the package management system will run for you when your
2467 package is installed, upgraded or removed.
2471 These scripts are the files <prgn>preinst</prgn>,
2472 <prgn>postinst</prgn>, <prgn>prerm</prgn> and <prgn>postrm</prgn> in the
2473 control area of the package. They must be proper executable
2474 files; if they are scripts (which is recommended), they must
2475 start with the usual <tt>#!</tt> convention. They should be
2476 readable and executable by anyone, and not world-writable.
2480 The package management system looks at the exit status from
2481 these scripts. It is important that they exit with a
2482 non-zero status if there is an error, so that the package
2483 management system can stop its processing. For shell
2484 scripts this means that you <em>almost always</em> need to
2485 use <tt>set -e</tt> (this is usually true when writing shell
2486 scripts, in fact). It is also important, of course, that
2487 they don't exit with a non-zero status if everything went
2492 When a package is upgraded a combination of the scripts from
2493 the old and new packages is called during the upgrade
2494 procedure. If your scripts are going to be at all
2495 complicated you need to be aware of this, and may need to
2496 check the arguments to your scripts.
2500 Broadly speaking the <prgn>preinst</prgn> is called before
2501 (a particular version of) a package is installed, and the
2502 <prgn>postinst</prgn> afterwards; the <prgn>prerm</prgn>
2503 before (a version of) a package is removed and the
2504 <prgn>postrm</prgn> afterwards.
2508 Programs called from maintainer scripts should not normally
2509 have a path prepended to them. Before installation is
2510 started, the package management system checks to see if the
2511 programs <prgn>ldconfig</prgn>,
2512 <prgn>start-stop-daemon</prgn>, <prgn>install-info</prgn>,
2513 and <prgn>update-rc.d</prgn> can be found via the
2514 <tt>PATH</tt> environment variable. Those programs, and any
2515 other program that one would expect to be on the
2516 <tt>PATH</tt>, should thus be invoked without an absolute
2517 pathname. Maintainer scripts should also not reset the
2518 <tt>PATH</tt>, though they might choose to modify it by
2519 prepending or appending package-specific directories. These
2520 considerations really apply to all shell scripts.</p>
2524 <heading>Maintainer scripts Idempotency</heading>
2527 It is necessary for the error recovery procedures that the
2528 scripts be idempotent. This means that if it is run
2529 successfully, and then it is called again, it doesn't bomb
2530 out or cause any harm, but just ensures that everything is
2531 the way it ought to be. If the first call failed, or
2532 aborted half way through for some reason, the second call
2533 should merely do the things that were left undone the first
2534 time, if any, and exit with a success status if everything
2537 This is so that if an error occurs, the user interrupts
2538 <prgn>dpkg</prgn> or some other unforeseen circumstance
2539 happens you don't leave the user with a badly-broken
2540 package when <prgn>dpkg</prgn> attempts to repeat the
2548 <heading>Controlling terminal for maintainer scripts</heading>
2551 The maintainer scripts are guaranteed to run with a
2552 controlling terminal and can interact with the user.
2553 If they need to prompt for passwords, do full-screen
2554 interaction or something similar you should do these
2555 things to and from <tt>/dev/tty</tt>, since
2556 <prgn>dpkg</prgn> will at some point redirect scripts'
2557 standard input and output so that it can log the
2558 installation process. Likewise, because these scripts
2559 may be executed with standard output redirected into a
2560 pipe for logging purposes, Perl scripts should set
2561 unbuffered output by setting <tt>$|=1</tt> so that the
2562 output is printed immediately rather than being
2567 Each script should return a zero exit status for
2568 success, or a nonzero one for failure.
2572 <sect id="mscriptsinstact"><heading>Summary of ways maintainer
2577 <list compact="compact">
2579 <p><var>new-preinst</var> <tt>install</tt></p>
2582 <p><var>new-preinst</var> <tt>install</tt>
2583 <var>old-version</var></p>
2586 <p><var>new-preinst</var> <tt>upgrade</tt>
2587 <var>old-version</var></p>
2590 <p><var>old-preinst</var> <tt>abort-upgrade</tt>
2591 <var>new-version</var>
2597 <list compact="compact">
2599 <p><var>postinst</var> <tt>configure</tt>
2600 <var>most-recently-configured-version</var></p>
2603 <p><var>old-postinst</var> <tt>abort-upgrade</tt>
2604 <var>new-version</var></p>
2607 <p><var>conflictor's-postinst</var> <tt>abort-remove</tt>
2608 <tt>in-favour</tt> <var>package</var>
2609 <var>new-version</var></p>
2613 <var>deconfigured's-postinst</var>
2614 <tt>abort-deconfigure</tt> <tt>in-favour</tt>
2615 <var>failed-install-package</var> <var>version</var>
2616 <tt>removing</tt> <var>conflicting-package</var>
2623 <list compact="compact">
2625 <p><var>prerm</var> <tt>remove</tt></p>
2628 <p><var>old-prerm</var> <tt>upgrade</tt>
2629 <var>new-version</var></p>
2632 <p><var>new-prerm</var> <tt>failed-upgrade</tt>
2633 <var>old-version</var></p>
2636 <p><var>conflictor's-prerm</var> <tt>remove</tt>
2637 <tt>in-favour</tt> <var>package</var>
2638 <var>new-version</var></p>
2642 <var>deconfigured's-prerm</var> <tt>deconfigure</tt>
2643 <tt>in-favour</tt> <var>package-being-installed</var>
2644 <var>version</var> <tt>removing</tt>
2645 <var>conflicting-package</var>
2652 <list compact="compact">
2654 <p><var>postrm</var> <tt>remove</tt></p>
2657 <p><var>postrm</var> <tt>purge</tt></p>
2661 <var>old-postrm</var> <tt>upgrade</tt>
2662 <var>new-version</var></p>
2665 <p><var>new-postrm</var> <tt>failed-upgrade</tt>
2666 <var>old-version</var></p>
2669 <p><var>new-postrm</var> <tt>abort-install</tt></p>
2672 <p><var>new-postrm</var> <tt>abort-install</tt>
2673 <var>old-version</var></p>
2676 <p><var>new-postrm</var> <tt>abort-upgrade</tt>
2677 <var>old-version</var></p>
2681 <var>disappearer's-postrm</var> <tt>disappear</tt>
2682 <var>overwriter</var>
2683 <var>overwriter-version</var></p></item>
2688 <sect id="unpackphase"><heading>Details of unpack phase of
2689 installation or upgrade
2693 The procedure on installation/upgrade/overwrite/disappear
2694 (i.e., when running <tt>dpkg --unpack</tt>, or the unpack
2695 stage of <tt>dpkg --install</tt>) is as follows. In each
2696 case, if a major error occurs (unless listed below) the
2697 actions are, in general, run backwards - this means that the
2698 maintainer scripts are run with different arguments in
2699 reverse order. These are the `error unwind' calls listed
2707 <p>If a version of the package is already
2709 <example compact="compact">
2710 <var>old-prerm</var> upgrade <var>new-version</var>
2715 If the script runs but exits with a non-zero
2716 exit status, <prgn>dpkg</prgn> will attempt:
2717 <example compact="compact">
2718 <var>new-prerm</var> failed-upgrade <var>old-version</var>
2720 Error unwind, for both the above cases:
2721 <example compact="compact">
2722 <var>old-postinst</var> abort-upgrade <var>new-version</var>
2730 <p>If a `conflicting' package is being removed at the same time:
2734 If any packages depended on that conflicting
2735 package and <tt>--auto-deconfigure</tt> is
2736 specified, call, for each such package:
2737 <example compact="compact">
2738 <var>deconfigured's-prerm</var> deconfigure \
2739 in-favour <var>package-being-installed</var> <var>version</var> \
2740 removing <var>conflicting-package</var> <var>version</var>
2743 <example compact="compact">
2744 <var>deconfigured's-postinst</var> abort-deconfigure \
2745 in-favour <var>package-being-installed-but-failed</var> <var>version</var> \
2746 removing <var>conflicting-package</var> <var>version</var>
2748 The deconfigured packages are marked as
2749 requiring configuration, so that if
2750 <tt>--install</tt> is used they will be
2751 configured again if possible.</p>
2754 <p>To prepare for removal of the conflicting package, call:
2755 <example compact="compact">
2756 <var>conflictor's-prerm</var> remove \
2757 in-favour <var>package</var> <var>new-version</var>
2760 <example compact="compact">
2761 <var>conflictor's-postinst</var> abort-remove \
2762 in-favour <var>package</var> <var>new-version</var>
2773 <p>If the package is being upgraded, call:
2774 <example compact="compact">
2775 <var>new-preinst</var> upgrade <var>old-version</var>
2780 Otherwise, if the package had some configuration
2781 files from a previous version installed (i.e., it
2782 is in the `configuration files only' state):
2783 <example compact="compact">
2784 <var>new-preinst</var> install <var>old-version</var>
2788 <p>Otherwise (i.e., the package was completely purged):
2789 <example compact="compact">
2790 <var>new-preinst</var> install
2792 Error unwind actions, respectively:
2793 <example compact="compact">
2794 <var>new-postrm</var> abort-upgrade <var>old-version</var>
2795 <var>new-postrm</var> abort-install <var>old-version</var>
2796 <var>new-postrm</var> abort-install
2805 The new package's files are unpacked, overwriting any
2806 that may be on the system already, for example any
2807 from the old version of the same package or from
2808 another package. Backups of the old files are kept
2809 temporarily, and if anything goes wrong the package
2810 management system will attempt to put them back as
2811 part of the error unwind.
2815 It is an error for a package to contains files which
2816 are on the system in another package, unless
2817 <tt>Replaces</tt> is used (see <ref id="replaces">).
2819 The following paragraph is not currently the case:
2820 Currently the <tt>- - force-overwrite</tt> flag is
2821 enabled, downgrading it to a warning, but this may not
2827 It is a more serious error for a package to contain a
2828 plain file or other kind of non-directory where another
2829 package has a directory (again, unless
2830 <tt>Replaces</tt> is used). This error can be
2831 overridden if desired using
2832 <tt>--force-overwrite-dir</tt>, but this is not
2837 Packages which overwrite each other's files produce
2838 behavior which, though deterministic, is hard for the
2839 system administrator to understand. It can easily
2840 lead to `missing' programs if, for example, a package
2841 is installed which overwrites a file from another
2842 package, and is then removed again.<footnote>
2844 Part of the problem is due to what is arguably a
2845 bug in <prgn>dpkg</prgn>.
2851 A directory will never be replaced by a symbolic link
2852 to a directory or vice versa; instead, the existing
2853 state (symlink or not) will be left alone and
2854 <prgn>dpkg</prgn> will follow the symlink if there is
2862 <p>If the package is being upgraded, call
2863 <example compact="compact">
2864 <var>old-postrm</var> upgrade <var>new-version</var>
2869 <p>If this fails, <prgn>dpkg</prgn> will attempt:
2870 <example compact="compact">
2871 <var>new-postrm</var> failed-upgrade <var>old-version</var>
2873 Error unwind, for both cases:
2874 <example compact="compact">
2875 <var>old-preinst</var> abort-upgrade <var>new-version</var>
2882 This is the point of no return - if
2883 <prgn>dpkg</prgn> gets this far, it won't back off
2884 past this point if an error occurs. This will
2885 leave the package in a fairly bad state, which
2886 will require a successful re-installation to clear
2887 up, but it's when <prgn>dpkg</prgn> starts doing
2888 things that are irreversible.
2893 Any files which were in the old version of the package
2894 but not in the new are removed.</p>
2897 <p>The new file list replaces the old.</p>
2900 <p>The new maintainer scripts replace the old.</p>
2904 <p>Any packages all of whose files have been overwritten during the
2905 installation, and which aren't required for
2906 dependencies, are considered to have been removed.
2907 For each such package
2910 <p><prgn>dpkg</prgn> calls:
2911 <example compact="compact">
2912 <var>disappearer's-postrm</var> disappear \
2913 <var>overwriter</var> <var>overwriter-version</var>
2918 <p>The package's maintainer scripts are removed.
2923 It is noted in the status database as being in a
2924 sane state, namely not installed (any conffiles
2925 it may have are ignored, rather than being
2926 removed by <prgn>dpkg</prgn>). Note that
2927 disappearing packages do not have their prerm
2928 called, because <prgn>dpkg</prgn> doesn't know
2929 in advance that the package is going to
2938 Any files in the package we're unpacking that are also
2939 listed in the file lists of other packages are removed
2940 from those lists. (This will lobotomize the file list
2941 of the `conflicting' package if there is one.)
2946 The backup files made during installation, above, are
2953 The new package's status is now sane, and recorded as
2958 Here is another point of no return - if the
2959 conflicting package's removal fails we do not unwind
2960 the rest of the installation; the conflicting package
2961 is left in a half-removed limbo.
2967 If there was a conflicting package we go and do the
2968 removal actions (described below), starting with the
2969 removal of the conflicting package's files (any that
2970 are also in the package being installed have already
2971 been removed from the conflicting package's file list,
2972 and so do not get removed now).
2979 <sect id="configdetails"><heading>Details of configuration</heading>
2982 When we configure a package (this happens with <tt>dpkg
2983 --install</tt> and <tt>dpkg --configure</tt>), we first
2984 update any <tt>conffile</tt>s and then call:
2985 <example compact="compact">
2986 <var>postinst</var> configure <var>most-recently-configured-version</var>
2991 No attempt is made to unwind after errors during
2996 If there is no most recently configured version
2997 <prgn>dpkg</prgn> will pass a null argument; older versions
2998 of dpkg may pass <tt><unknown></tt> (including the
2999 angle brackets) in this case. Even older ones do not pass a
3000 second argument at all, under any circumstances.
3004 <sect id="removedetails"><heading>Details of removal and/or
3005 configuration purging</heading>
3011 <example compact="compact">
3012 <var>prerm</var> remove
3018 The package's files are removed (except <tt>conffile</tt>s).
3023 <example compact="compact">
3024 <var>postrm</var> remove
3030 All the maintainer scripts except the <prgn>postrm</prgn>
3035 If we aren't purging the package we stop here. Note
3036 that packages which have no <prgn>postrm</prgn> and no
3037 <tt>conffile</tt>s are automatically purged when
3038 removed, as there is no difference except for the
3039 <prgn>dpkg</prgn> status.</p>
3043 The <tt>conffile</tt>s and any backup files
3044 (<tt>~</tt>-files, <tt>#*#</tt> files,
3045 <tt>%</tt>-files, <tt>.dpkg-{old,new,tmp}</tt>, etc.)
3050 <example compact="compact">
3051 <var>postrm</var> purge
3056 <p>The package's file list is removed.</p>
3059 No attempt is made to unwind after errors during
3066 <chapt id="relationships"><heading>Declaring relationships between
3070 Packages can declare in their control file that they have
3071 certain relationships to other packages - for example, that
3072 they may not be installed at the same time as certain other
3073 packages, and/or that they depend on the presence of others,
3074 or that they should overwrite files in certain other packages
3079 This is done using the <tt>Depends</tt>, <tt>Pre-Depends</tt>,
3080 <tt>Recommends</tt>, <tt>Suggests</tt>, <tt>Enhances</tt>,
3081 <tt>Conflicts</tt>, <tt>Provides</tt> and <tt>Replaces</tt>
3082 control file fields.
3086 Source packages may declare relationships to binary packages,
3087 saying that they require certain binary packages to be
3088 installed or absent at the time of building the package.
3092 This is done using the <tt>Build-Depends</tt>,
3093 <tt>Build-Depends-Indep</tt>, <tt>Build-Conflicts</tt> and
3094 <tt>Build-Conflicts-Indep</tt> control file fields.
3097 <sect id="depsyntax"><heading>Syntax of relationship fields
3101 These fields all have a uniform syntax. They are a list of
3102 package names separated by commas.
3106 In the <tt>Depends</tt>, <tt>Recommends</tt>,
3107 <tt>Suggests</tt>, <tt>Pre-Depends</tt>,
3108 <tt>Build-Depends</tt> and <tt>Build-Depends-Indep</tt>
3109 control file fields of the package, which declare
3110 dependencies on other packages, the package names listed may
3111 also include lists of alternative package names, separated
3112 by vertical bar (pipe) symbols <tt>|</tt>. In such a case,
3113 if any one of the alternative packages is installed, that
3114 part of the dependency is considered to be satisfied.
3118 All of the fields except for <tt>Provides</tt> may restrict
3119 their applicability to particular versions of each named
3120 package. This is done in parentheses after each individual
3121 package name; the parentheses should contain a relation from
3122 the list below followed by a version number, in the format
3123 described in <ref id="versions">.
3127 The relations allowed are <tt><<</tt>, <tt><=</tt>,
3128 <tt>=</tt>, <tt>>=</tt> and <tt>>></tt> for
3129 strictly earlier, earlier or equal, exactly equal, later or
3130 equal and strictly later, respectively. The deprecated
3131 forms <tt><</tt> and <tt>></tt> were used to mean
3132 earlier/later or equal, rather than strictly earlier/later,
3133 so they should not appear in new packages (though
3134 <prgn>dpkg</prgn> still supports them).
3138 Whitespace may appear at any point in the version
3139 specification subject to the rules in <ref
3140 id="controlsyntax">, and must appear where it's necessary to
3141 disambiguate; it is not otherwise significant. For
3142 consistency and in case of future changes to
3143 <prgn>dpkg</prgn> it is recommended that a single space be
3144 used after a version relationship and before a version
3145 number; it is also conventional to put a single space after
3146 each comma, on either side of each vertical bar, and before
3147 each open parenthesis.
3151 For example, a list of dependencies might appear as:
3152 <example compact="compact">
3155 Depends: libc6 (>= 2.2.1), exim | mail-transport-agent
3160 All fields that specify build-time relationships
3161 (<tt>Build-Depends</tt>, <tt>Build-Depends-Indep</tt>,
3162 <tt>Build-Conflicts</tt> and <tt>Build-Conflicts-Indep</tt>)
3163 may be restricted to a certain set of architectures. This
3164 is indicated in brackets after each individual package name and
3165 the optional version specification. The brackets enclose a
3166 list of Debian architecture names separated by whitespace.
3167 Exclamation marks may be prepended to each of the names.
3168 (It is not permitted for some names to be prepended with
3169 exclamation marks and others not.) If the current Debian
3170 host architecture is not in this list and there are no
3171 exclamation marks in the list, or it is in the list with a
3172 prepended exclamation mark, the package name and the
3173 associated version specification are ignored completely for
3174 the purposes of defining the relationships.
3179 <example compact="compact">
3181 Build-Depends-Indep: texinfo
3182 Build-Depends: kernel-headers-2.2.10 [!hurd-i386],
3183 hurd-dev [hurd-i386], gnumach-dev [hurd-i386]
3188 Note that the binary package relationship fields such as
3189 <tt>Depends</tt> appear in one of the binary package
3190 sections of the control file, whereas the build-time
3191 relationships such as <tt>Build-Depends</tt> appear in the
3192 source package section of the control file (which is the
3198 <heading>Binary Dependencies - <tt>Depends</tt>,
3199 <tt>Recommends</tt>, <tt>Suggests</tt>, <tt>Enhances</tt>,
3200 <tt>Pre-Depends</tt>
3204 These five fields are used to declare a dependency
3205 relationship by one package on another. Except for
3206 <tt>Enhances</tt>, they appear in the depending (binary)
3207 package's control file. (<tt>Enhances</tt> appears in the
3208 recommending package's control file.)
3212 A <tt>Depends</tt> field takes effect <em>only</em> when a
3213 package is to be configured. It does not prevent a package
3214 being on the system in an unconfigured state while its
3215 dependencies are unsatisfied, and it is possible to replace
3216 a package whose dependencies are satisfied and which is
3217 properly installed with a different version whose
3218 dependencies are not and cannot be satisfied; when this is
3219 done the depending package will be left unconfigured (since
3220 attempts to configure it will give errors) and will not
3221 function properly. If it is necessary, a
3222 <tt>Pre-Depends</tt> field can be used, which has a partial
3223 effect even when a package is being unpacked, as explained
3224 in detail below. (The other three dependency fields,
3225 <tt>Recommends</tt>, <tt>Suggests</tt> and
3226 <tt>Enhances</tt>, are only used by the various front-ends
3227 to <prgn>dpkg</prgn> such as <prgn>dselect</prgn>.)
3231 For this reason packages in an installation run are usually
3232 all unpacked first and all configured later; this gives
3233 later versions of packages with dependencies on later
3234 versions of other packages the opportunity to have their
3235 dependencies satisfied.
3239 The <tt>Depends</tt> field thus allows package maintainers
3240 to impose an order in which packages should be configured.
3244 The meaning of the five dependency fields is as follows:
3246 <tag><tt>Depends</tt></tag>
3249 This declares an absolute dependency. A package will
3250 not be configured unless all of the packages listed in
3251 its <tt>Depends</tt> field have been correctly
3256 The <tt>Depends</tt> field should be used if the
3257 depended-on package is required for the depending
3258 package to provide a significant amount of
3262 The <tt>Depends</tt> field should also be used if the
3263 <prgn>postinst</prgn>, <prgn>prerm</prgn> or
3264 <prgn>postrm</prgn> scripts require the package to be
3265 present in order to run. Note, however, that the
3266 <prgn>postrm</prgn> cannot rely on any non-essential
3267 packages to be present during the <tt>purge</tt>
3271 <tag><tt>Recommends</tt></tag>
3273 <p>This declares a strong, but not absolute, dependency.
3277 The <tt>Recommends</tt> field should list packages
3278 that would be found together with this one in all but
3279 unusual installations.</p>
3282 <tag><tt>Suggests</tt></tag>
3285 This is used to declare that one package may be more
3286 useful with one or more others. Using this field
3287 tells the packaging system and the user that the
3288 listed packages are related to this one and can
3289 perhaps enhance its usefulness, but that installing
3290 this one without them is perfectly reasonable.
3294 <tag><tt>Enhances</tt></tag>
3297 This field is similar to Suggests but works in the
3298 opposite direction. It is used to declare that a
3299 package can enhance the functionality of another
3304 <tag><tt>Pre-Depends</tt></tag>
3307 This field is like <tt>Depends</tt>, except that it
3308 also forces <prgn>dpkg</prgn> to complete installation
3309 of the packages named before even starting the
3310 installation of the package which declares the
3311 pre-dependency, as follows:
3315 When a package declaring a pre-dependency is about to
3316 be <em>unpacked</em> the pre-dependency can be
3317 satisfied if the depended-on package is either fully
3318 configured, <em>or even if</em> the depended-on
3319 package(s) are only unpacked or half-configured,
3320 provided that they have been configured correctly at
3321 some point in the past (and not removed or partially
3322 removed since). In this case, both the
3323 previously-configured and currently unpacked or
3324 half-configured versions must satisfy any version
3325 clause in the <tt>Pre-Depends</tt> field.
3329 When the package declaring a pre-dependency is about
3330 to be <em>configured</em>, the pre-dependency will be
3331 treated as a normal <tt>Depends</tt>, that is, it will
3332 be considered satisfied only if the depended-on
3333 package has been correctly configured.
3337 <tt>Pre-Depends</tt> should be used sparingly,
3338 preferably only by packages whose premature upgrade or
3339 installation would hamper the ability of the system to
3340 continue with any upgrade that might be in progress.
3344 <tt>Pre-Depends</tt> are also required if the
3345 <prgn>preinst</prgn> script depends on the named
3346 package. It is best to avoid this situation if
3352 When selecting which level of dependency to use you should
3353 consider how important the depended-on package is to the
3354 functionality of the one declaring the dependency. Some
3355 packages are composed of components of varying degrees of
3356 importance. Such a package should list using
3357 <tt>Depends</tt> the package(s) which are required by the
3358 more important components. The other components'
3359 requirements may be mentioned as Suggestions or
3360 Recommendations, as appropriate to the components' relative
3365 <sect id="conflicts"><heading>Conflicting binary packages -
3366 <tt>Conflicts</tt></heading>
3369 When one binary package declares a conflict with another
3370 using a <tt>Conflicts</tt> field, <prgn>dpkg</prgn> will
3371 refuse to allow them to be installed on the system at the
3376 If one package is to be installed, the other must be removed
3377 first - if the package being installed is marked as
3378 replacing (see <ref id="replaces">) the one on the system,
3379 or the one on the system is marked as deselected, or both
3380 packages are marked <tt>Essential</tt>, then
3381 <prgn>dpkg</prgn> will automatically remove the package
3382 which is causing the conflict, otherwise it will halt the
3383 installation of the new package with an error. This
3384 mechanism is specifically designed to produce an error when
3385 the installed package is <tt>Essential</tt>, but the new
3390 A package will not cause a conflict merely because its
3391 configuration files are still installed; it must be at least
3396 A special exception is made for packages which declare a
3397 conflict with their own package name, or with a virtual
3398 package which they provide (see below): this does not
3399 prevent their installation, and allows a package to conflict
3400 with others providing a replacement for it. You use this
3401 feature when you want the package in question to be the only
3402 package providing some feature.
3406 A <tt>Conflicts</tt> entry should almost never have an
3407 `earlier than' version clause. This would prevent
3408 <prgn>dpkg</prgn> from upgrading or installing the package
3409 which declared such a conflict until the upgrade or removal
3410 of the conflicted-with package had been completed.
3414 <sect id="virtual"><heading>Virtual packages - <tt>Provides</tt>
3418 As well as the names of actual (`concrete') packages, the
3419 package relationship fields <tt>Depends</tt>,
3420 <tt>Recommends</tt>, <tt>Suggests</tt>, <tt>Enhances</tt>,
3421 <tt>Pre-Depends</tt>, <tt>Conflicts</tt>,
3422 <tt>Build-Depends</tt>, <tt>Build-Depends-Indep</tt>,
3423 <tt>Build-Conflicts</tt> and <tt>Build-Conflicts-Indep</tt>
3424 may mention `virtual packages'.
3428 A <em>virtual package</em> is one which appears in the
3429 <tt>Provides</tt> control file field of another package.
3430 The effect is as if the package(s) which provide a
3431 particular virtual package name had been listed by name
3432 everywhere the virtual package name appears.
3436 If there are both a real and a virtual package of the same
3437 name then the dependency may be satisfied (or the conflict
3438 caused) by either the real package or any of the virtual
3439 packages which provide it. This is so that, for example,
3441 <example compact="compact">
3445 and someone else releases an enhanced version of the
3446 <tt>bar</tt> package (for example, a non-US variant), they
3448 <example compact="compact">
3452 and the <tt>bar-plus</tt> package will now also satisfy the
3453 dependency for the <tt>foo</tt> package.
3457 If a dependency or a conflict has a version number attached
3458 then only real packages will be considered to see whether
3459 the relationship is satisfied (or the prohibition violated,
3460 for a conflict) - it is assumed that a real package which
3461 provides the virtual package is not of the `right' version.
3462 So, a <tt>Provides</tt> field may not contain version
3463 numbers, and the version number of the concrete package
3464 which provides a particular virtual package will not be
3465 looked at when considering a dependency on or conflict with
3466 the virtual package name.
3470 It is likely that the ability will be added in a future
3471 release of <prgn>dpkg</prgn> to specify a version number for
3472 each virtual package it provides. This feature is not yet
3473 present, however, and is expected to be used only
3478 If you want to specify which of a set of real packages
3479 should be the default to satisfy a particular dependency on
3480 a virtual package, you should list the real package as an
3481 alternative before the virtual one.
3486 <sect id="replaces"><heading>Overwriting files and replacing
3487 packages - <tt>Replaces</tt></heading>
3490 The <tt>Replaces</tt> control file field has two distinct
3491 purposes, which come into play in different situations.
3494 <sect1><heading>Overwriting files in other packages</heading>
3497 Firstly, as mentioned before, it is usually an error for a
3498 package to contain files which are on the system in
3503 However, if the overwriting package declares that it
3504 <tt>Replaces</tt> the one containing the file being
3505 overwritten, then <prgn>dpkg</prgn> will replace the file
3506 from the old package with that from the new. The file
3507 will no longer be listed as `owned' by the old package.
3511 If a package is completely replaced in this way, so that
3512 <prgn>dpkg</prgn> does not know of any files it still
3513 contains, it is considered to have `disappeared'. It will
3514 be marked as not wanted on the system (selected for
3515 removal) and not installed. Any <tt>conffile</tt>s
3516 details noted for the package will be ignored, as they
3517 will have been taken over by the overwriting package. The
3518 package's <prgn>postrm</prgn> script will be run with a
3519 special argument to allow the package to do any final
3520 cleanup required. See <ref id="mscriptsinstact">.
3524 If an installed package, <tt>foo</tt> say, declares that
3525 it replaces another, <tt>bar</tt>, and an attempt is made
3526 to install <tt>bar</tt>, <prgn>dpkg</prgn> will discard
3527 files in the <tt>bar</tt> package which would overwrite
3528 those already present in <tt>foo</tt>. This is so that
3529 you can install an older version of a package without
3534 For this usage of <tt>Replaces</tt>, virtual packages (see
3535 <ref id="virtual">) are not considered when looking at a
3536 <tt>Replaces</tt> field - the packages declared as being
3537 replaced must be mentioned by their real names.
3541 Furthermore, this usage of <tt>Replaces</tt> only takes
3542 effect when both packages are at least partially on the
3543 system at once, so that it can only happen if they do not
3544 conflict or if the conflict has been overridden.
3549 <sect1><heading>Replacing whole packages, forcing their
3553 Secondly, <tt>Replaces</tt> allows the packaging system to
3554 resolve which package should be removed when there is a
3555 conflict - see <ref id="conflicts">. This usage only
3556 takes effect when the two packages <em>do</em> conflict,
3557 so that the two usages of this field do not interfere with
3562 In this situation, the package declared as being replaced
3563 can be a virtual package, so for example, all mail
3564 transport agents (MTAs) would have the following fields in
3565 their control files:
3566 <example compact="compact">
3567 Provides: mail-transport-agent
3568 Conflicts: mail-transport-agent
3569 Replaces: mail-transport-agent
3571 ensuring that only one MTA can be installed at any one
3576 <sect><heading>Relationships between source and binary packages -
3577 <tt>Build-Depends</tt>, <tt>Build-Depends-Indep</tt>,
3578 <tt>Build-Conflicts</tt>, <tt>Build-Conflicts-Indep</tt>
3582 A source package may declare a dependency or a conflict on a
3583 binary package, indicating which packages are required to be
3584 present on the system in order to build the binary packages
3585 from the source package. This is done with the control file
3586 fields <tt>Build-Depends</tt>, <tt>Build-Depends-Indep</tt>,
3587 <tt>Build-Conflicts</tt> and <tt>Build-Conflicts-Indep</tt>.
3588 The dependencies and conflicts they define must be satisfied
3589 (as defined earlier for binary packages) in order to invoke
3590 the targets in <tt>debian/rules</tt>, as follows:
3593 <tag><tt>Build-Depends</tt>, <tt>Build-Conflicts</tt></tag>
3596 The <tt>Build-Depends</tt> and
3597 <tt>Build-Conflicts</tt> fields must be satisfied when
3598 any of the following targets is invoked:
3599 <tt>build</tt>, <tt>binary</tt>, <tt>binary-arch</tt>
3600 and <tt>binary-indep</tt>.
3603 <tag><tt>Build-Depends-Indep</tt>, <tt>Build-Conflicts-Indep</tt></tag>
3606 The <tt>Build-Depends-Indep</tt> and
3607 <tt>Build-Conflicts-Indep</tt> fields must be
3608 satisfied when any of the following targets is
3609 invoked: <tt>binary</tt> and <tt>binary-indep</tt>.
3620 <chapt id="conffiles"><heading>Configuration file handling
3624 This chapter has been superseded by <ref id="config files">.
3628 <chapt id="sharedlibs"><heading>Shared libraries</heading>
3631 Packages containing shared libraries must be constructed with
3632 a little care to make sure that the shared library is always
3633 available. This is especially important for packages whose
3634 shared libraries are vitally important, such as the C library
3635 (currently <tt>libc6</tt>).
3639 Firstly, the package should install the shared libraries under
3640 their normal names. For example, the <tt>libgdbmg1</tt>
3641 package should install <tt>libgdbm.so.1.7.3</tt> as
3642 <tt>/usr/lib/libgdbm.so.1.7.3</tt>. The files should not be
3643 renamed or re-linked by any <prgn>prerm</prgn> or
3644 <prgn>postrm</prgn> scripts; <prgn>dpkg</prgn> will take care
3645 of renaming things safely without affecting running programs,
3646 and attempts to interfere with this are likely to lead to
3651 Secondly, the package should include the symbolic link that
3652 <prgn>ldconfig</prgn> would create for the shared libraries.
3653 For example, the <prgn>libgdbmg1</prgn> package should include
3654 a symbolic link from <tt>/usr/lib/libgdbm.so.1</tt> to
3655 <tt>libgdbm.so.1.7.3</tt>. This is needed so that the dynamic
3656 linker (for example <prgn>ld.so</prgn> or
3657 <prgn>ld-linux.so.*</prgn>) can find the library between the
3658 time that <prgn>dpkg</prgn> installs it and the time that
3659 <prgn>ldconfig</prgn> is run in the <prgn>postinst</prgn>
3662 The package management system requires the library to be
3663 placed before the symbolic link pointing to it in the
3664 <tt>.deb</tt> file. This is so that when
3665 <prgn>dpkg</prgn> comes to install the symlink
3666 (overwriting the previous symlink pointing at an older
3667 version of the library), the new shared library is already
3668 in place. In the past, this was achieved by creating the
3669 library in the temporary packaging directory before
3670 creating the symlink. Unfortunately, this was not always
3671 effective, since the building of the tar file in the
3672 <tt>.deb</tt> depended on the behavior of the underlying
3673 file system. Some file systems (such as reiserfs) reorder
3674 the files so that the order of creation is forgotten.
3675 Starting with release <tt>1.7.0</tt>, <prgn>dpkg</prgn>
3676 will reorder the files itself as necessary when building a
3677 package. Thus it is no longer important to concern
3678 oneself with the order of file creation.
3684 Thirdly, the associated development package should contain a
3685 symlink for the shared library without a version number. For
3686 example, the <tt>libgdbmg1-dev</tt> package should include a
3687 symlink from <tt>/usr/lib/libgdbm.so</tt> to
3688 <tt>libgdbm.so.1.7.3</tt>. This symlink is needed by the
3689 linker (<prgn>ld</prgn>) when compiling packages, as it will
3690 only look for <tt>libgdbm.so</tt> when compiling dynamically.
3694 Any package installing shared libraries in one of the default
3695 library directories of the dynamic linker (which are currently
3696 <tt>/usr/lib</tt> and <tt>/lib</tt>) or a directory that is
3697 listed in <tt>/etc/ld.so.conf</tt><footnote>
3700 <list compact="compact">
3701 <item><p>/usr/X11R6/lib/Xaw3d</p></item>
3702 <item><p>/usr/local/lib</p></item>
3703 <item><p>/usr/lib/libc5-compat</p></item>
3704 <item><p>/lib/libc5-compat</p></item>
3705 <item><p>/usr/X11R6/lib</p></item>
3709 must call <prgn>ldconfig</prgn> in its <prgn>postinst</prgn>
3710 script if the first argument is <tt>configure</tt> and should
3711 call it in the <prgn>postrm</prgn> script if the first
3712 argument is <tt>remove</tt>.
3716 However, <prgn>postrm</prgn> and <prgn>preinst</prgn> scripts
3717 <em>must not</em> call <prgn>ldconfig</prgn> in the case where
3718 the package is being upgraded (see <ref id="unpackphase"> for
3719 details), as <prgn>ldconfig</prgn> will see the temporary
3720 names that <prgn>dpkg</prgn> uses for the files while it is
3721 installing them and will make the shared library links point
3722 to them, just before <prgn>dpkg</prgn> continues the
3723 installation and renames the temporary files!
3727 <heading>Handling shared library dependencies - the
3728 <tt>shlibs</tt> system</heading>
3731 If a package contains a binary or library which links to a
3732 shared library, we must ensure that when the package is
3733 installed on the system, all of the libraries needed are
3734 also installed. This requirement led to the creation of the
3735 <tt>shlibs</tt> system, which is very simple in its design:
3736 any package which <em>provides</em> a shared library also
3737 provides information on the package dependencies required to
3738 ensure the presence of this library, and any package which
3739 <em>uses</em> a shared library uses this information to
3740 determine the dependencies it requires. The files which
3741 contain the mapping from shared libraries to the necessary
3742 dependency information are called <tt>shlibs</tt> files.
3746 Thus, when a package is built which contains any shared
3747 libraries, it must provide a <tt>shlibs</tt> file for other
3748 packages to use, and when a package is built which contains
3749 any shared libraries or compiled binaries, it must run
3750 <prgn>dpkg-shlibdeps</prgn> on these to determine the
3751 libraries used and hence the dependencies needed by this
3754 In the past, the shared libraries linked to were
3755 determined by calling <prgn>ldd</prgn>, but now
3756 <prgn>objdump</prgn> to do this. The only change this
3757 makes to package building is that
3758 <prgn>dpkg-shlibdeps</prgn> must also be run on shared
3759 libraries, whereas in the past this was unnecessary.
3760 The rest of this footnote explains the advantage that
3765 We say that a binary <tt>foo</tt> <em>directly</em> uses
3766 a library <tt>libbar</tt> if it is explicitly linked
3767 with that library (that is, it uses the flag
3768 <tt>-lbar</tt> during the linking stage). Other
3769 libraries that are needed by <tt>libbar</tt> are linked
3770 <em>indirectly</em> to <tt>foo</tt>, and the dynamic
3771 linker will load them automatically when it loads
3772 <tt>libbar</tt>. A package should needs to depend on
3773 the libraries it directly uses, and the dependencies for
3774 those libraries should automatically pull in the other
3779 Unfortunately, the <prgn>ldd</prgn> program shows both
3780 the directly and indirectly used libraries, meaning that
3781 the dependencies determined included both direct and
3782 indirect dependencies. The use of <prgn>objdump</prgn>
3783 avoids this problem by determining only the directly
3788 A good example of where this helps is the following. We
3789 could update <tt>libimlib</tt> with a new version that
3790 supports a new graphics format called dgf (but retaining
3791 the same major version number). If we used the old
3792 <prgn>ldd</prgn> method, every package that uses
3793 <tt>libimlib</tt> would need to be recompiled so it
3794 would also depend on <tt>libdgf</tt> or it wouldn't run
3795 due to missing symbols. However with the new system,
3796 packages using <tt>libimlib</tt> can rely on
3797 <tt>libimlib</tt> itself having the dependency on
3798 <tt>libdgf</tt> and so they would not need rebuilding.
3804 In the following sections, we will first describe where the
3805 various <tt>shlibs</tt> files are to be found, then how to
3806 use <prgn>dpkg-shlibdeps</prgn>, and finally the
3807 <tt>shlibs</tt> file format and how to create them if your
3808 package contains a shared library.
3812 <sect><heading>The <tt>shlibs</tt> files present on the system
3816 There are several places where <tt>shlibs</tt> files are
3817 found. The following list gives them in the order in which
3818 they are read by <prgn>dpkg-shlibdeps</prgn>. (The first
3819 one which gives the required information is used.)
3825 <p><tt>debian/shlibs.local</tt></p>
3827 This lists overrides for this package. Its use is
3828 described below (see <ref id="shlibslocal">).
3833 <p><tt>/etc/dpkg/shlibs.override</tt></p>
3835 This lists global overrides. This list is normally
3836 empty. It is maintained by the local system
3842 <p><tt>DEBIAN/shlibs</tt> files in the `build directory'</p>
3844 When packages are being built, any
3845 <tt>debian/shlibs</tt> files are copied into the
3846 control file area of the temporary build directory and
3847 given the name <tt>shlibs</tt>. These files give
3848 details of any shared libraries included in the
3851 An example may help here. Let us say that the
3852 source package <tt>foo</tt> generates two binary
3853 packages, <tt>libfoo2</tt> and
3854 <tt>foo-runtime</tt>. When building the binary
3855 packages, the two packages are created in the
3856 directories <tt>debian/libfoo2</tt> and
3857 <tt>debian/foo-runtime</tt> respectively.
3858 (<tt>debian/tmp</tt> could be used instead of one
3859 of these.) Since <tt>libfoo2</tt> provides the
3860 <tt>libfoo</tt> shared library, it will require a
3861 <tt>shlibs</tt> file, which will be installed in
3862 <tt>debian/libfoo2/DEBIAN/shlibs</tt>, eventually
3864 <tt>/var/lib/dpkg/info/libfoo2.shlibs</tt>. Then
3865 when <prgn>dpkg-shlibdeps</prgn> is run on the
3867 <tt>debian/foo-runtime/usr/bin/foo-prog</tt>, it
3869 <tt>debian/libfoo2/DEBIAN/shlibs</tt> file to
3870 determine whether <tt>foo-prog</tt>'s library
3871 dependencies are satisfied by any of the libraries
3872 provided by <tt>libfoo2</tt>. For this reason,
3873 <prgn>dpkg-shlibdeps</prgn> must only be run once
3874 all of the individual binary packages'
3875 <tt>shlibs</tt> files have been installed into the
3883 <p><tt>/var/lib/dpkg/info/*.shlibs</tt></p>
3885 These are the <tt>shlibs</tt> files corresponding to
3886 all of the packages installed on the system, and are
3887 maintained by the relevant package maintainers.
3892 <p><tt>/etc/dpkg/shlibs.default</tt></p>
3894 This file lists any shared libraries whose packages
3895 have failed to provide correct <tt>shlibs</tt> files.
3896 It was used when the <tt>shlibs</tt> setup was first
3897 introduced, but it is now normally empty. It is
3898 maintained by the <tt>dpkg</tt> maintainer.
3906 <heading>How to use <prgn>dpkg-shlibdeps</prgn> and the
3907 <tt>shlibs</tt> files</heading>
3910 Put a call to <prgn>dpkg-shlibdeps</prgn> into your
3911 <tt>debian/rules</tt> file. If your package contains only
3912 compiled binaries and libraries (but no scripts), you can
3913 use a command such as:
3914 <example compact="compact">
3915 dpkg-shlibdeps debian/tmp/usr/bin/* debian/tmp/usr/sbin/* \
3916 debian/tmp/usr/lib/*
3918 Otherwise, you will need to explicitly list the compiled
3919 binaries and libraries.<footnote>
3921 If you are using <tt>debhelper</tt>, the
3922 <prgn>dh_shlibdeps</prgn> program will do this work for
3923 you. It will also correctly handle multi-binary
3930 This command puts the dependency information into the
3931 <tt>debian/substvars</tt> file, which is then used by
3932 <prgn>dpkg-gencontrol</prgn>. You will need to place a
3933 <tt>${shlib:Depends}</tt> variable in the <tt>Depends</tt>
3934 field in the control file for this to work.
3938 If <prgn>dpkg-shlibdeps</prgn> doesn't complain, you're
3939 done. If it does complain you might need to create your own
3940 <tt>debian/shlibs.local</tt> file, as explained below (see
3941 <ref id="shlibslocal">).
3945 If you have multiple binary packages, you will need to call
3946 <prgn>dpkg-shlibdeps</prgn> on each one which contains
3947 compiled libraries or binaries. In such a case, you will
3948 need to use the <tt>-T</tt> option to the <tt>dpkg</tt>
3949 utilities to specify a different <tt>substvars</tt> file.
3950 For more details on this and other options, see <manref
3951 name="dpkg-shlibdeps" section="1">.
3955 <sect id="shlibs"><heading>The <tt>shlibs</tt> File Format
3959 Each <tt>shlibs</tt> file has the same format. Lines
3960 beginning with <tt>#</tt> are considered to be commments and
3961 are ignored. Each line is of the form:
3962 <example compact="compact">
3963 <var>library-name</var> <var>soname-version-number</var> <var>dependencies ...</var>
3968 We will explain this by reference to the example of the
3969 <tt>zlib1g</tt> package, which (at the time of writing)
3970 installs the shared library <tt>/usr/lib/libz.so.1.1.3</tt>.
3974 <var>library-name</var> is the name of the shared library,
3975 in this case <tt>libz</tt>. (This must match the name part
3976 of the soname, see below.)
3980 <var>soname-version-number</var> is the version part of the
3981 soname of the library. The soname is the thing that must
3982 exactly match for the library to be recognized by the
3983 dynamic linker, and is usually of the form
3984 <tt><var>name</var>.so.<var>major-version</var></tt>, in our
3985 example, <tt>libz.so.1</tt>.<footnote>
3987 This can be determined using the command
3988 <example compact="compact">
3989 objdump -p /usr/lib/libz.so.1.1.3 | grep SONAME
3993 The version part is the part which comes after
3994 <tt>.so.</tt>, so in our case, it is <tt>1</tt>.
3998 <var>dependencies</var> has the same syntax as a dependency
3999 field in a binary package control file. It should give
4000 details of which packages are required to satisfy a binary
4001 built against the version of the library contained in the
4002 package. See <ref id="depsyntax"> for details.
4006 In our example, if the first version of the <tt>zlib1g</tt>
4007 package which contained a minor number of at least
4008 <tt>1.3</tt> was <var>1:1.1.3-1</var>, then the
4009 <tt>shlibs</tt> entry for this library could say:
4010 <example compact="compact">
4011 libz 1 zlib1g (>= 1:1.1.3)
4013 The version-specific dependency is to avoid warnings from
4014 the dynamic linker about using older shared libraries with
4020 <heading>Providing a <tt>shlibs</tt> file</heading>
4023 If your package provides a shared library, you should create
4024 a <tt>shlibs</tt> file following the format described above.
4025 It is usual to call this file <tt>debian/shlibs</tt> (but if
4026 you have multiple binary packages, you might want to call it
4027 <tt>debian/shlibs.<var>package</var></tt> instead). Then
4028 let <tt>debian/rules</tt> install it in the control area:
4029 <example compact="compact">
4030 install -m644 debian/shlibs debian/tmp/DEBIAN
4032 or, in the case of a multi-binary package:
4033 <example compact="compact">
4034 install -m644 debian/shlibs.<var>package</var> debian/<var>package</var>/DEBIAN/shlibs
4036 An alternative way of doing this is to create the
4037 <tt>shlibs</tt> file in the control area directly from
4038 <tt>debian/rules</tt> without using a <tt>debian/shlibs</tt>
4039 file at all,<footnote>
4041 This is what <prgn>dh_makeshlibs</prgn> in the
4042 <tt>debhelper</tt> suite does.
4045 since the <tt>debian/shlibs</tt> file itself is ignored by
4046 <prgn>dpkg-shlibdeps</prgn>.
4050 As <prgn>dpkg-shlibdeps</prgn> reads the
4051 <tt>DEBIAN/shlibs</tt> files in all of the binary packages
4052 being built from this source package, all of the
4053 <tt>DEBIAN/shlibs</tt> files should be installed before
4054 <prgn>dpkg-shlibdeps</prgn> is called on any of the binary
4059 <sect id="shlibslocal">
4060 <heading>Writing the <tt>debian/shlibs.local</tt> file</heading>
4063 This file is intended only as a <em>temporary</em> fix if
4064 your binaries or libraries depend on a library whose package
4065 does not yet provide a correct <tt>shlibs</tt> file.
4069 We will assume that you are trying to package a binary
4070 <tt>foo</tt>. When you try running
4071 <prgn>dpkg-shlibdeps</prgn> you get the following error
4072 message (<tt>-O</tt> displays the dependency information on
4073 <tt>stdout</tt> instead of writing it to
4074 <tt>debian/substvars</tt>, and the lines have been wrapped
4075 for ease of reading):
4076 <example compact="compact">
4077 $ dpkg-shlibdeps -O debian/tmp/usr/bin/foo
4078 dpkg-shlibdeps: warning: unable to find dependency
4079 information for shared library libbar (soname 1,
4080 path /usr/lib/libbar.so.1, dependency field Depends)
4081 shlibs:Depends=libc6 (>= 2.2.2-2)
4083 You can then run <prgn>ldd</prgn> on the binary to find the
4084 full location of the library concerned:
4085 <example compact="compact">
4087 libbar.so.1 => /usr/lib/libbar.so.1 (0x4001e000)
4088 libc.so.6 => /lib/libc.so.6 (0x40032000)
4089 /lib/ld-linux.so.2 => /lib/ld-linux.so.2 (0x40000000)
4091 So the <prgn>foo</prgn> binary depends on the
4092 <prgn>libbar</prgn> shared library, but no package seems to
4093 provide a <tt>*.shlibs</tt> file handling
4094 <tt>libbar.so.1</tt> in <tt>/var/lib/dpkg/info/</tt>. Let's
4095 determine the package responsible:
4096 <example compact="compact">
4097 $ dpkg -S /usr/lib/libbar.so.1
4098 bar1: /usr/lib/libbar.so.1
4099 $ dpkg -s bar1 | grep Version
4102 This tells us that the <tt>bar1</tt> package, version 1.0-1,
4103 is the one we are using. Now we can file a bug against the
4104 <tt>bar1</tt> package and create our own
4105 <tt>debian/shlibs.local</tt> to locally fix the problem.
4106 Including the following line into your
4107 <tt>debian/shlibs.local</tt> file:
4108 <example compact="compact">
4109 libbar 1 bar1 (>= 1.0-1)
4111 should allow the package build to work.
4115 As soon as the maintainer of <tt>bar1</tt> provides a
4116 correct <tt>shlibs</tt> file, you should remove this line
4117 from your <tt>debian/shlibs.local</tt> file. (You should
4118 probably also then have a versioned <tt>Build-Depends</tt>
4119 on <tt>bar1</tt> to help ensure that others do not have the
4120 same problem building your package.)
4125 <chapt id="opersys"><heading>The Operating System</heading>
4128 <heading>Filesystem hierarchy</heading>
4132 <heading>Filesystem Structure</heading>
4135 The location of all installed files and directories must
4136 comply with the Filesystem Hierarchy Standard (FHS),
4137 version 2.1. This can be found in the
4138 <tt>debian-policy</tt> package or on <url
4139 id="http://www.debian.org/doc/packaging-manuals/fhs"
4140 name="FHS (Debian copy)"> alongside this manual or on <url
4141 id="http://www.pathname.com/fhs/" name="FHS (upstream)">.
4142 Specific questions about following the standard may be
4143 asked on the <tt>debian-devel</tt> mailing list, or
4144 referred to Daniel Quinlan, the FHS coordinator, at
4145 <email>quinlan@pathname.com</email>.
4150 <heading>Site-specific programs</heading>
4153 As mandated by the FHS, packages must not place any
4154 files in <tt>/usr/local</tt>, either by putting them in
4155 the file system archive to be unpacked by <prgn>dpkg</prgn>
4156 or by manipulating them in their maintainer scripts.
4160 However, the package may create empty directories below
4161 <tt>/usr/local</tt> so that the system administrator knows
4162 where to place site-specific files. These directories
4163 should be removed on package removal if they are
4168 Note, that this applies only to directories <em>below</em>
4169 <tt>/usr/local</tt>, not <em>in</em> <tt>/usr/local</tt>.
4170 Packages must not create sub-directories in the directory
4171 <tt>/usr/local</tt> itself, except those listed in FHS,
4172 section 4.5. However, you may create directories below
4173 them as you wish. You must not remove any of the
4174 directories listed in 4.5, even if you created them.
4178 Since <tt>/usr/local</tt> can be mounted read-only from a
4179 remote server, these directories must be created and
4180 removed by the <prgn>postinst</prgn> and <prgn>prerm</prgn>
4181 maintainer scripts and not be included in the
4182 <tt>.deb</tt> archive. These scripts must not fail if
4183 either of these operations fail.
4187 For example, the <tt>emacsen-common</tt> package could
4188 contain something like
4189 <example compact="compact">
4190 if [ ! -e /usr/local/share/emacs ]
4192 if mkdir /usr/local/share/emacs 2>/dev/null
4194 chown root:staff /usr/local/share/emacs
4195 chmod 2775 /usr/local/share/emacs
4199 in its <prgn>postinst</prgn> script, and
4200 <example compact="compact">
4201 rmdir /usr/local/share/emacs/site-lisp 2>/dev/null || true
4202 rmdir /usr/local/share/emacs 2>/dev/null || true
4204 in the <prgn>prerm</prgn> script. (Note that this form is
4205 used to ensure that if the script is interrupted, the
4206 directory <tt>/usr/local/share/emacs</tt> will still be
4211 If you do create a directory in <tt>/usr/local</tt> for
4212 local additions to a package, you should ensure that
4213 settings in <tt>/usr/local</tt> take precedence over the
4214 equivalents in <tt>/usr</tt>.
4218 However, because <tt>/usr/local</tt> and its contents are
4219 for exclusive use of the local administrator, a package
4220 must not rely on the presence or absence of files or
4221 directories in <tt>/usr/local</tt> for normal operation.
4225 The <tt>/usr/local</tt> directory itself and all the
4226 subdirectories created by the package should (by default) have
4227 permissions 2775 (group-writable and set-group-id) and be
4228 owned by <tt>root.staff</tt>.
4233 <heading>The system-wide mail directory</heading>
4235 The system-wide mail directory is <tt>/var/mail</tt>. This
4236 directory is part of the base system and should not owned
4237 by any particular mail agents. The use of the old
4238 location <tt>/var/spool/mail</tt> is deprecated, even
4239 though the spool may still be physically located there.
4240 To maintain partial upgrade compatibility for systems
4241 which have <tt>/var/spool/mail</tt> as their physical mail
4242 spool, packages using <tt>/var/mail</tt> must depend on
4243 either <package>libc6</package> (>= 2.1.3-13), or on
4244 <package>base-files</package> (>= 2.2.0), or on later
4245 versions of either one of these packages.
4251 <heading>Users and groups</heading>
4254 <heading>Introduction</heading>
4256 The Debian system can be configured to use either plain or
4261 Some user ids (UIDs) and group ids (GIDs) are reserved
4262 globally for use by certain packages. Because some
4263 packages need to include files which are owned by these
4264 users or groups, or need the ids compiled into binaries,
4265 these ids must be used on any Debian system only for the
4266 purpose for which they are allocated. This is a serious
4267 restriction, and we should avoid getting in the way of
4268 local administration policies. In particular, many sites
4269 allocate users and/or local system groups starting at 100.
4273 Apart from this we should have dynamically allocated ids,
4274 which should by default be arranged in some sensible
4275 order, but the behavior should be configurable.
4279 Packages other than <tt>base-passwd</tt> must not modify
4280 <tt>/etc/passwd</tt>, <tt>/etc/shadow</tt>,
4281 <tt>/etc/group</tt> or <tt>/etc/gshadow</tt>.
4286 <heading>UID and GID classes</heading>
4288 The UID and GID numbers are divided into classes as
4294 Globally allocated by the Debian project, the same
4295 on every Debian system. These ids will appear in
4296 the <tt>passwd</tt> and <tt>group</tt> files of all
4297 Debian systems, new ids in this range being added
4298 automatically as the <tt>base-passwd</tt> package is
4303 Packages which need a single statically allocated
4304 uid or gid should use one of these; their
4305 maintainers should ask the <tt>base-passwd</tt>
4313 Dynamically allocated system users and groups.
4314 Packages which need a user or group, but can have
4315 this user or group allocated dynamically and
4316 differently on each system, should use <tt>adduser
4317 --system</tt> to create the group and/or user.
4318 <prgn>adduser</prgn> will check for the existence of
4319 the user or group, and if necessary choose an unused
4320 id based on the ranges specified in
4321 <tt>adduser.conf</tt>.
4325 <tag>1000-29999:</tag>
4328 Dynamically allocated user accounts. By default
4329 <prgn>adduser</prgn> will choose UIDs and GIDs for
4330 user accounts in this range, though
4331 <tt>adduser.conf</tt> may be used to modify this
4336 <tag>30000-59999:</tag>
4341 <tag>60000-64999:</tag>
4344 Globally allocated by the Debian project, but only
4345 created on demand. The ids are allocated centrally
4346 and statically, but the actual accounts are only
4347 created on users' systems on demand.
4351 These ids are for packages which are obscure or
4352 which require many statically-allocated ids. These
4353 packages should check for and create the accounts in
4354 <tt>/etc/passwd</tt> or <tt>/etc/group</tt> (using
4355 <prgn>adduser</prgn> if it has this facility) if
4356 necessary. Packages which are likely to require
4357 further allocations should have a `hole' left after
4358 them in the allocation, to give them room to
4363 <tag>65000-65533:</tag>
4371 User <tt>nobody</tt>. The corresponding gid refers
4372 to the group <tt>nogroup</tt>.
4379 <tt>(uid_t)(-1) == (gid_t)(-1)</tt> <em>must
4380 not</em> be used, because it is the error return
4389 <sect id="sysvinit">
4390 <heading>System run levels and <tt>init.d</tt> scripts</heading>
4392 <sect1 id="/etc/init.d">
4393 <heading>Introduction</heading>
4396 The <tt>/etc/init.d</tt> directory contains the scripts
4397 executed by <prgn>init</prgn> at boot time and when the
4398 init state (or `runlevel') is changed (see <manref
4399 name="init" section="8">).
4403 There are at least two different, yet functionally
4404 equivalent, ways of handling these scripts. For the sake
4405 of simplicity, this document describes only the symbolic
4406 link method. However, it must not be assumed by maintainer
4407 scripts that this method is being used, and any automated
4408 manipulation of the various runlevel behaviours by
4409 maintainer scripts must be performed using
4410 <prgn>update-rc.d</prgn> as described below and not by
4411 manually installing or removing symlinks. For information
4412 on the implementation details of the other method,
4413 implemented in the <tt>file-rc</tt> package, please refer
4414 to the documentation of that package.
4418 These scripts are referenced by symbolic links in the
4419 <tt>/etc/rc<var>n</var>.d</tt> directories. When changing
4420 runlevels, <prgn>init</prgn> looks in the directory
4421 <tt>/etc/rc<var>n</var>.d</tt> for the scripts it should
4422 execute, where <tt><var>n</var></tt> is the runlevel that
4423 is being changed to, or <tt>S</tt> for the boot-up
4428 The names of the links all have the form
4429 <tt>S<var>mm</var><var>script</var></tt> or
4430 <tt>K<var>mm</var><var>script</var></tt> where
4431 <var>mm</var> is a two-digit number and <var>script</var>
4432 is the name of the script (this should be the same as the
4433 name of the actual script in <tt>/etc/init.d</tt>).
4437 When <prgn>init</prgn> changes runlevel first the targets
4438 of the links whose names start with a <tt>K</tt> are
4439 executed, each with the single argument <tt>stop</tt>,
4440 followed by the scripts prefixed with an <tt>S</tt>, each
4441 with the single argument <tt>start</tt>. (The links are
4442 those in the <tt>/etc/rc<var>n</var>.d</tt> directory
4443 corresponding to the new runlevel.) The <tt>K</tt> links
4444 are responsible for killing services and the <tt>S</tt>
4445 link for starting services upon entering the runlevel.
4449 For example, if we are changing from runlevel 2 to
4450 runlevel 3, init will first execute all of the <tt>K</tt>
4451 prefixed scripts it finds in <tt>/etc/rc3.d</tt>, and then
4452 all of the <tt>S</tt> prefixed scripts in that directory.
4453 The links starting with <tt>K</tt> will cause the
4454 referred-to file to be executed with an argument of
4455 <tt>stop</tt>, and the <tt>S</tt> links with an argument
4460 The two-digit number <var>mm</var> is used to determine
4461 the order in which to run the scripts: low-numbered links
4462 have their scripts run first. For example, the
4463 <tt>K20</tt> scripts will be executed before the
4464 <tt>K30</tt> scripts. This is used when a certain service
4465 must be started before another. For example, the name
4466 server <prgn>bind</prgn> might need to be started before
4467 the news server <prgn>inn</prgn> so that <prgn>inn</prgn>
4468 can set up its access lists. In this case, the script
4469 that starts <prgn>bind</prgn> would have a lower number
4470 than the script that starts <prgn>inn</prgn> so that it
4472 <example compact="compact">
4479 The two runlevels 0 (halt) and 6 (reboot) are slightly
4480 different. In these runlevels, the links with an
4481 <tt>S</tt> prefix are still called after those with a
4482 <tt>K</tt> prefix, but they too are called with the single
4483 argument <tt>stop</tt>.
4487 Also, if the script name ends <tt>.sh</tt>, the script
4488 will be sourced in runlevel <tt>S</tt> rather that being
4489 run in a forked subprocess, but will be explicitly run by
4490 <prgn>sh</prgn> in all other runlevels.
4495 <heading>Writing the scripts</heading>
4498 Packages that include daemons for system services should
4499 place scripts in <tt>/etc/init.d</tt> to start or stop
4500 services at boot time or during a change of runlevel.
4501 These scripts should be named
4502 <tt>/etc/init.d/<var>package</var></tt>, and they should
4503 accept one argument, saying what to do:
4506 <tag><tt>start</tt></tag>
4507 <item><p>start the service,</p></item>
4509 <tag><tt>stop</tt></tag>
4510 <item><p>stop the service,</p></item>
4512 <tag><tt>restart</tt></tag>
4513 <item><p>stop and restart the service,</p></item>
4515 <tag><tt>reload</tt></tag>
4516 <item><p>cause the configuration of the service to be
4517 reloaded without actually stopping and restarting
4518 the service,</p></item>
4520 <tag><tt>force-reload</tt></tag>
4521 <item><p>cause the configuration to be reloaded if the
4522 service supports this, otherwise restart the
4526 The <tt>start</tt>, <tt>stop</tt>, <tt>restart</tt>, and
4527 <tt>force-reload</tt> options should be supported by all
4528 scripts in <tt>/etc/init.d</tt>, the <tt>reload</tt>
4529 option is optional.</p>
4532 The <tt>init.d</tt> scripts should ensure that they will
4533 behave sensibly if invoked with <tt>start</tt> when the
4534 service is already running, or with <tt>stop</tt> when it
4535 isn't, and that they don't kill unfortunately-named user
4536 processes. The best way to achieve this is usually to use
4537 <prgn>start-stop-daemon</prgn>.</p>
4540 If a service reloads its configuration automatically (as
4541 in the case of <prgn>cron</prgn>, for example), the
4542 <tt>reload</tt> option of the <tt>init.d</tt> script
4543 should behave as if the configuration has been reloaded
4547 The <tt>/etc/init.d</tt> scripts should be treated as
4548 configuration files, either by marking them as
4549 <tt>conffile</tt>s or managing them correctly in the
4550 maintainer scripts (see <ref id="config files">). This is
4551 important since we want to give the local system
4552 administrator the chance to adapt the scripts to the local
4553 system, e.g., to disable a service without de-installing
4554 the package, or to specify some special command line
4555 options when starting a service, while making sure her
4556 changes aren't lost during the next package upgrade.
4560 These scripts should not fail obscurely when the
4561 configuration files remain but the package has been
4562 removed, as configuration files remain on the system after
4563 the package has been removed. Only when <prgn>dpkg</prgn>
4564 is executed with the <tt>--purge</tt> option will
4565 configuration files be removed. In particular, as the
4566 <tt>/etc/init.d/<var>package</var></tt> script itself is
4567 usually a <tt>conffile</tt>, it will remain on the system
4568 if the package is removed but not purged. Therefore, you
4569 should include a <tt>test</tt> statement at the top of the
4571 <example compact="compact">
4572 test -f <var>program-executed-later-in-script</var> || exit 0
4577 Often there are some variables in the <tt>init.d</tt>
4578 scripts whose values control the bahaviour of the scripts,
4579 and which a system administrator is likely to want to
4580 change. As the scripts themselves are frequently
4581 <tt>conffile</tt>s, modifying them requires that the
4582 administrator merge in their changes each time the package
4583 is upgraded and the <tt>conffile</tt> changes. To ease
4584 the burden on the system administrator, such configurable
4585 values should not be placed directly in the script.
4586 Instead, they should be placed in a file in
4587 <tt>/etc/default</tt>, which typically will have the same
4588 base name as the <tt>init.d</tt> script. This extra file
4589 should be sourced by the script when the script runs. It
4590 must contain only variable settings and comments in POSIX
4591 <prgn>sh</prgn> format. It may either be a
4592 <tt>conffile</tt> or a configuration file maintained by
4593 the package maintainer scripts. See <ref id="config
4594 files"> for more details.
4598 To ensure that vital configurable values are always
4599 available, the <tt>init.d</tt> script should set default
4600 values for each of the shell variables it uses, either
4601 before sourcing the <tt>/etc/default/</tt> file or
4602 afterwards using something like the <tt>:
4603 ${VAR:=default}</tt> syntax. Also, the <tt>init.d</tt>
4604 script must behave sensibly and not fail if the
4605 <tt>/etc/default</tt> file is deleted.
4610 <heading>Managing the links</heading>
4613 The program <prgn>update-rc.d</prgn> is provided for
4614 package maintainers to arrange for the proper creation and
4615 removal of <tt>/etc/rc<var>n</var>.d</tt> symbolic links,
4616 or their functional equivalent if another method is being
4617 used. This may be used by maintainers in their packages'
4618 <prgn>postinst</prgn> and <prgn>postrm</prgn> scripts.</p>
4621 You must not include any <tt>/etc/rc<var>n</var>.d</tt>
4622 symbolic links in the actual archive or manually create or
4623 remove the symbolic links in maintainer scripts; you must
4624 use the <prgn>update-rc.d</prgn> program instead. (The
4625 former will fail if an alternative method of maintaining
4626 runlevel information is being used.) You must not include
4627 the <tt>/etc/rc<var>n</var>.d</tt> directories themselves
4628 in the archive either. (Only the <tt>sysvinit</tt>
4633 By default <prgn>update-rc.d</prgn> will start services in
4634 each of the multi-user state runlevels (2, 3, 4, and 5)
4635 and stop them in the halt runlevel (0), the single-user
4636 runlevel (1) and the reboot runlevel (6). The system
4637 administrator will have the opportunity to customize
4638 runlevels by simply adding, moving, or removing the
4639 symbolic links in <tt>/etc/rc<var>n</var>.d</tt> if
4640 symbolic links are being used, or by modifying
4641 <tt>/etc/runlevel.conf</tt> if the <tt>file-rc</tt> method
4646 To get the default behavior for your package, put in your
4647 <prgn>postinst</prgn> script
4648 <example compact="compact">
4649 update-rc.d <var>package</var> defaults >/dev/null
4651 and in your <prgn>postrm</prgn>
4652 <example compact="compact">
4653 if [ "$1" = purge ]; then
4654 update-rc.d <var>package</var> remove >/dev/null
4659 This will use a default sequence number of 20. If it does
4660 not matter when or in which order the <tt>init.d</tt>
4661 script is run, use this default. If it does, then you
4662 should talk to the maintainer of the <prgn>sysvinit</prgn>
4663 package or post to <tt>debian-devel</tt>, and they will
4664 help you choose a number.
4668 For more information about using <tt>update-rc.d</tt>,
4669 please consult its manpage <manref name="update-rc.d"
4676 <heading>Boot-time initialization</heading>
4679 There used to be another directory, <tt>/etc/rc.boot</tt>,
4680 which contained scripts which were run once per machine
4681 boot. This has been deprecated in favour of links from
4682 <tt>/etc/rcS.d</tt> to files in <tt>/etc/init.d</tt> as
4683 described in <ref id="/etc/init.d">. Packages must not
4684 place files in <tt>/etc/rc.boot</tt>.</p>
4687 <heading>Example</heading>
4690 The <prgn>bind</prgn> DNS (nameserver) package wants to
4691 make sure that the nameserver is running in multiuser
4692 runlevels, and is properly shut down with the system. It
4693 puts a script in <tt>/etc/init.d</tt>, naming the script
4694 appropriately <tt>bind</tt>. As you can see, the script
4695 interprets the argument <tt>reload</tt> to send the
4696 nameserver a <tt>HUP</tt> signal (causing it to reload its
4697 configuration); this way the system administrator can say
4698 <tt>/etc/init.d/bind reload</tt> to reload the name
4699 server. The script has one configurable value, which can
4700 be used to pass parameters to the named program at
4701 startup; this value is read from
4702 <tt>/etc/default/bind</tt> (see below).
4706 <example compact="compact">
4709 # Original version by Robert Leslie
4710 # <rob@mars.org>, edited by iwj and cs
4712 test -x /usr/sbin/named || exit 0
4714 # Source defaults file.
4716 if [ -f /etc/default/bind ]; then
4723 echo -n "Starting domain name service: named"
4724 start-stop-daemon --start --quiet --exec /usr/sbin/named \
4729 echo -n "Stopping domain name service: named"
4730 start-stop-daemon --stop --quiet \
4731 --pidfile /var/run/named.pid --exec /usr/sbin/named
4735 echo -n "Restarting domain name service: named"
4736 start-stop-daemon --stop --quiet \
4737 --pidfile /var/run/named.pid --exec /usr/sbin/named
4738 start-stop-daemon --start --verbose --exec /usr/sbin/named \
4742 force-reload|reload)
4743 echo -n "Reloading configuration of domain name service: named"
4744 start-stop-daemon --stop --signal 1 --quiet \
4745 --pidfile /var/run/named.pid --exec /usr/sbin/named
4749 echo "Usage: /etc/init.d/bind {start|stop|restart|reload|force-reload}" >&2
4759 Complementing the above init script is a configuration
4760 file <tt>/etc/default/bind</tt>, which contains
4761 configurable parameters used by the script. This would be
4762 created by the <prgn>postinst</prgn> script if it was not
4763 already present, and removed on purge by the
4764 <prgn>postrm</prgn> script.
4765 <example compact="compact">
4766 # Specified parameters to pass to named. See named(8).
4767 # You may uncomment the following line, and edit to taste.
4773 Another example on which you can base your
4774 <tt>/etc/init.d</tt> scripts is found in
4775 <tt>/etc/init.d/skeleton</tt>.
4779 If this package is happy with the default setup from
4780 <prgn>update-rc.d</prgn>, namely an ordering number of 20
4781 and having named running in all runlevels, it can say in
4782 its <prgn>postinst</prgn>:
4783 <example compact="compact">
4784 update-rc.d bind defaults >/dev/null
4786 And in its <prgn>postrm</prgn>, to remove the links when the
4788 <example compact="compact">
4789 if [ "$1" = purge ]; then
4790 update-rc.d bind remove >/dev/null
4798 <heading>Console messages from <tt>init.d</tt> scripts</heading>
4801 This section describes the formats to be used for messages
4802 written to standard output by the <tt>/etc/init.d</tt>
4803 scripts. The intent is to improve the consistency of
4804 Debian's startup and shutdown look and feel. For this
4805 reason, please look very carefully at the details. We want
4806 the messages to have the same format in terms of wording,
4807 spaces, punctuation and case of letters.
4811 Here is a list of overall rules that you should use when you
4812 create output messages. They can be useful if you have a
4813 non-standard message that is not covered specifically in the
4821 Every message should fit in one line (fewer than 80
4822 characters), start with a capital letter and end with
4823 a period (<tt>.</tt>) and line feed (<tt>"\n"</tt>).
4829 If you want to express that the computer is working on
4830 something (that is, performing a specific task, not
4831 starting or stopping a program), we use an "ellipsis"
4832 (three dots: <tt>...</tt>). Note that we don't insert
4833 spaces before or after the dots. If the task has been
4834 completed we write <tt>done.</tt> and a line feed.
4840 Design your messages as if the computer is telling you
4841 what he is doing (let him be polite :-), but don't
4842 mention "him" directly. For example, if you think of
4844 <example compact="compact">
4845 I'm starting network daemons: nfsd mountd.
4848 <example compact="compact">
4849 Starting network daemons: nfsd mountd.
4857 There are standard message formats for the following
4858 situations. They should be used by the <tt>init.d</tt>
4865 <p>When daemons are started</p>
4868 If your script starts one or more daemons, the output
4869 should look like this (a single line, no leading
4871 <example compact="compact">
4872 Starting <var>description</var>: <var>daemon-1</var> ... <var>daemon-n</var>.
4874 The <var>description</var> should describe the
4875 subsystem the daemon or set of daemons are part of,
4876 while <var>daemon-1</var> up to <var>daemon-n</var>
4877 denote each daemon's name (typically the file name of
4882 For example, the output of <tt>/etc/init.d/lpd</tt>
4884 <example compact="compact">
4885 Starting printer spooler: lpd.
4890 This can be achieved by saying
4891 <example compact="compact">
4892 echo -n "Starting printer spooler: lpd"
4893 start-stop-daemon --start --quiet --exec /usr/sbin/lpd
4896 in the script. If you have more than one daemon to
4897 start, you should do the following:
4898 <example compact="compact">
4899 echo -n "Starting remote file system services:"
4900 echo -n " nfsd"; start-stop-daemon --start --quiet nfsd
4901 echo -n " mountd"; start-stop-daemon --start --quiet mountd
4902 echo -n " ugidd"; start-stop-daemon --start --quiet ugidd
4905 This makes it possible for the user to see what takes
4906 so long and when the final daemon has been started.
4907 You should be careful where to put spaces: in the
4908 example above the system administrator can easily
4909 comment out a line if he don't wants to start a
4910 specific daemon, while the displayed message still
4916 <p>When a system parameter is being set</p>
4919 If you have to set up different system parameters
4920 during the system boot, you should use this format:
4921 <example compact="compact">
4922 Setting <var>parameter</var> to `<var>value</var>'.
4927 You can use a statement such as the following to get
4929 <example compact="compact">
4930 echo "Setting DNS domainname to \`$domainname'."
4935 Note that the left quotation mark (<tt>`</tt>) is
4936 different from the right one (<tt>'</tt>).
4941 <p>When a daemon is stopped or restarted</p>
4944 When you stop or restart a daemon, you should issue a
4945 message identical to the startup message, except that
4946 <tt>Starting</tt> is replaced with <tt>Stopping</tt>
4947 or <tt>Restarting</tt> respectively.
4951 For example, stopping the printer daemon will like
4953 <example compact="compact">
4954 Stopping printer spooler: lpd.
4960 <p>When something is executed</p>
4963 There are several examples where you have to run a
4964 program at system startup or shutdown to perform a
4965 specific task, for example, setting the system's clock
4966 using <prgn>netdate</prgn> or killing all processes
4967 when the system shuts down. Your message should look
4969 <example compact="compact">
4970 Doing something very useful...done.
4972 You should print the <tt>done.</tt> immediately after
4973 the job has been completed, so that the user is
4974 informed why she has to wait. You can get this
4976 <example compact="compact">
4977 echo -n "Doing something very useful..."
4986 <p>When the configuration is reloaded</p>
4989 When a daemon is forced to reload its configuration
4990 files you should use the following format:
4991 <example compact="compact">
4992 Reloading <var>description</var> configuration...done.
4994 where <var>description</var> is the same as in the
4995 daemon starting message.
5003 <heading>Cron jobs</heading>
5006 Packages must not modify the configuration file
5007 <tt>/etc/crontab</tt>, and they must not modify the files in
5008 <tt>/var/spool/cron/crontabs</tt>.</p>
5011 If a package wants to install a job that has to be executed
5012 via cron, it should place a file with the name of the
5013 package in one or more of the following directories:
5014 <example compact="compact">
5019 As these directory names imply, the files within them are
5020 executed on a daily, weekly, or monthly basis,
5021 respectively. The exact times are listed in
5022 <tt>/etc/crontab</tt>.</p>
5025 All files installed in any of these directories must be
5026 scripts (e.g., shell scripts or Perl scripts) so that they
5027 can easily be modified by the local system administrator.
5028 In addition, they should be treated as configuration
5033 If a certain job has to be executed more frequently than
5034 daily, the package should install a file
5035 <tt>/etc/cron.d/<var>package</var></tt>. This file uses the
5036 same syntax as <tt>/etc/crontab</tt> and is processed by
5037 <prgn>cron</prgn> automatically. The file must also be
5038 treated as a configuration file. (Note that entries in the
5039 <tt>/etc/cron.d</tt> directory are not handled by
5040 <prgn>anacron</prgn>. Thus, you should only use this
5041 directory for jobs which may be skipped if the system is not
5045 The scripts or crontab entries in these directories should
5046 check if all necessary programs are installed before they
5047 try to execute them. Otherwise, problems will arise when a
5048 package was removed but not purged since configuration files
5049 are kept on the system in this situation.</p>
5053 <heading>Menus</heading>
5056 Menu entries should follow the current menu policy found in
5057 the <tt>menu-policy</tt> files in the <tt>debian-policy</tt>
5058 package. It may also be found on the Debian FTP site
5059 <ftpsite>ftp.debian.org</ftpsite> as the file
5060 <ftppath>/debian/doc/package-developer/menu-policy.txt.gz</ftppath>,
5061 or in the equivalent location on your local mirror.
5065 The Debian <tt>menu</tt> package provides a standard
5066 interface between packages providing applications and
5067 documents, and <em>menu programs</em> (either X window
5068 managers or text-based menu programs such as
5069 <prgn>pdmenu</prgn>).
5073 All packages that provide applications that need not be
5074 passed any special command line arguments for normal
5075 operation should register a menu entry for those
5076 applications, so that users of the <tt>menu</tt> package
5077 will automatically get menu entries in their window
5078 managers, as well in shells like <tt>pdmenu</tt>.</p>
5081 Please also refer to the <em>Debian Menu System</em>
5082 documentation that comes with the <tt>menu</tt> package for
5083 information about how to register your applications and web
5089 <heading>Multimedia handlers</heading>
5092 Packages which provide the ability to view/show/play,
5093 compose, edit or print MIME types should register themselves
5094 as such following the current MIME support policy found in
5095 the <tt>mime-policy</tt> files in the <tt>debian-policy</tt>
5096 package. It may also be found on the Debian FTP site
5097 <ftpsite>ftp.debian.org</ftpsite> as the file
5098 <ftppath>/debian/doc/package-developer/mime-policy.txt.gz</ftppath>,
5099 or in the equivalent location on your local mirror.
5103 MIME (Multipurpose Internet Mail Extensions, RFCs 2045-2049)
5104 is a mechanism for encoding files and data streams and
5105 providing meta-information about them, in particular their
5106 type (e.g. audio or video) and format (e.g. PNG, HTML,
5111 Registration of MIME type handlers allows programs like mail
5112 user agents and web browsers to to invoke these handlers to
5113 view, edit or display MIME types they don't support
5119 <heading>Keyboard configuration</heading>
5122 To achieve a consistent keyboard configuration so that all
5123 applications interpret a keyboard event the same way, all
5124 programs in the Debian distribution must be configured to
5125 comply with the following guidelines.
5129 The following keys must have the specified interpretations:
5132 <tag><tt><--</tt></tag>
5133 <item><p>delete the character to the left of the cursor</p></item>
5135 <tag><tt>Delete</tt></tag>
5136 <item><p>delete the character to the right of the cursor</p></item>
5138 <tag><tt>Control+H</tt></tag>
5139 <item><p>emacs: the help prefix</p></item>
5142 The interpretation of any keyboard events should be
5143 independent of the terminal that is used, be it a virtual
5144 console, an X terminal emulator, an rlogin/telnet session,
5149 The following list explains how the different programs
5150 should be set up to achieve this:
5155 <item><p><tt><--</tt> generates <tt>KB_Backspace</tt>
5158 <item><p><tt>Delete</tt> generates <tt>KB_Delete</tt> in
5163 X translations are set up to make
5164 <tt>KB_Backspace</tt> generate ASCII DEL, and to make
5165 <tt>KB_Delete</tt> generate <tt>ESC [ 3 ~</tt> (this
5166 is the vt220 escape code for the `delete character'
5167 key). This must be done by loading the X resources
5168 using <prgn>xrdb</prgn> on all local X displays, not
5169 using the application defaults, so that the
5170 translation resources used correspond to the
5171 <prgn>xmodmap</prgn> settings.</p></item>
5175 The Linux console is configured to make
5176 <tt><--</tt> generate DEL, and <tt>Delete</tt>
5177 generate <tt>ESC [ 3 ~</tt>.</p></item>
5181 X applications are configured so that <tt><</tt>
5182 deletes left, and <tt>Delete</tt> deletes right. Motif
5183 applications already work like this.</p></item>
5185 <item><p>Terminals should have <tt>stty erase ^?</tt> .</p></item>
5189 The <tt>xterm</tt> terminfo entry should have <tt>ESC
5190 [ 3 ~</tt> for <tt>kdch1</tt>, just as for
5191 <tt>TERM=linux</tt> and <tt>TERM=vt220</tt>.</p></item>
5195 Emacs is programmed to map <tt>KB_Backspace</tt> or
5196 the <tt>stty erase</tt> character to
5197 <tt>delete-backward-char</tt>, and <tt>KB_Delete</tt>
5198 or <tt>kdch1</tt> to <tt>delete-forward-char</tt>, and
5199 <tt>^H</tt> to <tt>help</tt> as always.</p></item>
5203 Other applications use the <tt>stty erase</tt>
5204 character and <tt>kdch1</tt> for the two delete keys,
5205 with ASCII DEL being `delete previous character' and
5206 <tt>kdch1</tt> being `delete character under
5213 This will solve the problem except for the following
5221 Some terminals have a <tt><--</tt> key that cannot
5222 be made to produce anything except <tt>^H</tt>. On
5223 these terminals Emacs help will be unavailable on
5224 <tt>^H</tt> (assuming that the <tt>stty erase</tt>
5225 character takes precedence in Emacs, and has been set
5226 correctly). <tt>M-x help</tt> or <tt>F1</tt> (if
5227 available) can be used instead.</p></item>
5231 Some operating systems use <tt>^H</tt> for <tt>stty
5232 erase</tt>. However, modern telnet versions and all
5233 rlogin versions propagate <tt>stty</tt> settings, and
5234 almost all UNIX versions honour <tt>stty erase</tt>.
5235 Where the <tt>stty</tt> settings are not propagated
5236 correctly, things can be made to work by using
5237 <tt>stty</tt> manually.</p></item>
5241 Some systems (including previous Debian versions) use
5242 <prgn>xmodmap</prgn> to arrange for both
5243 <tt><--</tt> and <tt>Delete</tt> to generate
5244 <tt>KB_Delete</tt>. We can change the behavior of
5245 their X clients using the same X resources that we use
5246 to do it for our own clients, or configure our clients
5247 using their resources when things are the other way
5248 around. On displays configured like this
5249 <tt>Delete</tt> will not work, but <tt><--</tt>
5254 Some operating systems have different <tt>kdch1</tt>
5255 settings in their <tt>terminfo</tt> database for
5256 <tt>xterm</tt> and others. On these systems the
5257 <tt>Delete</tt> key will not work correctly when you
5258 log in from a system conforming to our policy, but
5259 <tt><--</tt> will.</p></item>
5265 <heading>Environment variables</heading>
5268 A program must not depend on environment variables to get
5269 reasonable defaults. (That's because these environment
5270 variables would have to be set in a system-wide
5271 configuration file like <tt>/etc/profile</tt>, which is not
5272 supported by all shells.)</p>
5275 If a program usually depends on environment variables for its
5276 configuration, the program should be changed to fall back to
5277 a reasonable default configuration if these environment
5278 variables are not present. If this cannot be done easily
5279 (e.g., if the source code of a non-free program is not
5280 available), the program must be replaced by a small
5281 `wrapper' shell script which sets the environment variables
5282 if they are not already defined, and calls the original program.</p>
5285 Here is an example of a wrapper script for this purpose:
5287 <example compact="compact">
5289 BAR=${BAR:-/var/lib/fubar}
5291 exec /usr/lib/foo/foo "$@"
5296 Furthermore, as <tt>/etc/profile</tt> is a configuration
5297 file of the <prgn>base-files</prgn> package, other packages must not
5298 put any environment variables or other commands into that
5304 <heading>Files</heading>
5307 <heading>Binaries</heading>
5310 Two different packages must not install programs with
5311 different functionality but with the same filenames. (The
5312 case of two programs having the same functionality but
5313 different implementations is handled via `alternatives' or
5314 the `Conflicts' mechanism. See <ref id="maintscripts"> and
5315 <ref id="conflicts"> respectively.) If this case happens,
5316 one of the programs must be renamed. The maintainers should
5317 report this to the <tt>debian-devel</tt> mailing list and
5318 try to find a consensus about which program will have to be
5319 renamed. If a consensus cannot be reached, <em>both</em>
5320 programs must be renamed.
5324 Generally the following compilation parameters should be used:
5325 <example compact="compact">
5327 CFLAGS = -O2 -Wall # sane warning options vary between programs
5329 install -s # (or use strip on the files in debian/tmp)
5333 Note that by default all installed binaries should be stripped,
5334 either by using the <tt>-s</tt> flag to
5335 <prgn>install</prgn>, or by calling <prgn>strip</prgn> on
5336 the binaries after they have been copied into
5337 <tt>debian/tmp</tt> but before the tree is made into a
5341 The <tt>-N</tt> flag should not be used. On <tt>a.out</tt>
5342 systems it may have been useful for some very small
5343 binaries, but for ELF it has no good effect.</p>
5346 Debugging symbols are useful for error diagnosis,
5347 investigation of core dumps (which may be submitted by users
5348 in bug reports), or testing and developing the software.
5349 Therefore it is recommended to support building the package
5350 with debugging information through the following interface:
5351 If the environment variable <tt>DEB_BUILD_OPTIONS</tt>
5352 contains the string <tt>debug</tt>, compile the software
5353 with debugging information (usually this involves adding the
5354 <tt>-g</tt> flag to <tt>CFLAGS</tt>). This allows the
5355 generation of a build tree with debugging information. If
5356 the environment variable <tt>DEB_BUILD_OPTIONS</tt> contains
5357 the string <tt>nostrip</tt>, do not strip the files at
5358 installation time. This allows one to generate a package
5359 with debugging information included.<footnote>
5361 Rationale: Using <tt>-g</tt> by default causes wasted
5362 CPU cycles since the information is stripped away
5363 anyway; this can have a significant impact on the
5364 efficiency of the autobuilders. Having a standard way
5365 to build a debugging variant also makes it easier to
5366 build debugging bins and libraries since it provides a
5367 documented way of getting this type of build; one does
5368 not have to manually edit <tt>debian/rules</tt> or
5372 The following makefile snippet is an example of how one may
5373 test for either condition; you will probably have to massage
5374 this example in order to make it work for your package.
5375 <example compact="compact">
5378 INSTALL_FILE = $(INSTALL) -p -o root -g root -m 644
5379 INSTALL_PROGRAM = $(INSTALL) -p -o root -g root -m 755
5380 INSTALL_SCRIPT = $(INSTALL) -p -o root -g root -m 755
5381 INSTALL_DIR = $(INSTALL) -p -d -o root -g root -m 755
5383 ifneq (,$(findstring debug,$(DEB_BUILD_OPTIONS)))
5386 ifeq (,$(findstring nostrip,$(DEB_BUILD_OPTIONS)))
5387 INSTALL_PROGRAM += -s
5393 It is up to the package maintainer to decide what
5394 compilation options are best for the package. Certain
5395 binaries (such as computationally-intensive programs) will
5396 function better with certain flags (<tt>-O3</tt>, for
5397 example); feel free to use them. Please use good judgment
5398 here. Don't use flags for the sake of it; only use them
5399 if there is good reason to do so. Feel free to override
5400 the upstream author's ideas about which compilation
5401 options are best: they are often inappropriate for our
5402 environment.</p></sect>
5406 <heading>Libraries</heading>
5409 All libraries must have a shared version in the
5410 <tt>lib*</tt> package and a static version in the
5411 <tt>lib*-dev</tt> package. The shared version must be
5412 compiled with <tt>-fPIC</tt>, and the static version must
5413 not be. In other words, each <tt>*.c</tt> file will need to
5414 be compiled twice.</p>
5417 You must specify the gcc option <tt>-D_REENTRANT</tt>
5418 when building a library (either static or shared) to make
5419 the library compatible with LinuxThreads.</p>
5422 Note that all installed shared libraries should be
5424 <example compact="compact">
5425 strip --strip-unneeded <var>your-lib</var>
5427 (The option <tt>--strip-unneeded</tt> makes
5428 <prgn>strip</prgn> remove only the symbols which aren't
5429 needed for relocation processing.) Shared libraries can
5430 function perfectly well when stripped, since the symbols for
5431 dynamic linking are in a separate part of the ELF object
5434 You might also want to use the options
5435 <tt>--remove-section=.comment</tt> and
5436 <tt>--remove-section=.note</tt> on both shared libraries
5437 and executables, and <tt>--strip-debug</tt> on static
5444 Note that under some circumstances it may be useful to
5445 install a shared library unstripped, for example when
5446 building a separate package to support debugging.
5450 Shared object files (often <tt>.so</tt> files) that are not
5451 public libraries, that is, they are not meant to be linked
5452 to by third party executables (binaries of other packages),
5453 should be installed in subdirectories of the
5454 <tt>/usr/lib</tt> directory. Such files are exempt from the
5455 rules that govern ordinary shared libraries, except that
5456 they must not be installed executable and should be
5459 A common example are the so-called ``plug-ins'',
5460 internal shared objects that are dynamically loaded by
5461 programs using <manref name="dlopen" section="3">.
5467 Packages containing shared libraries that may be linked to
5468 by other packages' binaries, but which for some
5469 <em>compelling</em> reason can not be installed in
5470 <tt>/usr/lib</tt> directory, may install the shared library
5471 files in subdirectories of the <tt>/usr/lib</tt> directory,
5472 in which case they should arrange to add that directory in
5473 <tt>/etc/ld.so.conf</tt> in the package's post-installation
5474 script, and remove it in the package's post-removal script.
5478 An ever increasing number of packages are using
5479 <prgn>libtool</prgn> to do their linking. The latest GNU
5480 libtools (>= 1.3a) can take advantage of the metadata in the
5481 installed <prgn>libtool</prgn> archive files (<tt>*.la</tt>
5482 files). The main advantage of <prgn>libtool</prgn>'s
5483 <tt>.la</tt> files is that it allows <prgn>libtool</prgn> to
5484 store and subsequently access metadata with respect to the
5485 libraries it builds. <prgn>libtool</prgn> will search for
5486 those files, which contain a lot of useful information about
5487 a library (such as library dependency information for static
5488 linking). Also, they're <em>essential</em> for programs
5489 using <tt>libltdl</tt>.<footnote>
5491 Although <prgn>libtool</prgn> is fully capable of
5492 linking against shared libraries which don't have
5493 <tt>.la</tt> files, as it is a mere shell script it can
5494 add considerably to the build time of a
5495 <prgn>libtool</prgn>-using package if that shell script
5496 has to derive all this information from first principles
5497 for each library every time it is linked. With the
5498 advent of <prgn>libtool</prgn> version 1.4 (and to a
5499 lesser extent <prgn>libtool</prgn> version 1.3), the
5500 <tt>.la</tt> files also store information about
5501 inter-library dependencies which cannot necessarily be
5502 derived after the <tt>.la</tt> file is deleted.
5508 Packages that use <prgn>libtool</prgn> to create shared
5509 libraries should include the <tt>.la</tt> files in the
5510 <tt>-dev</tt> package, unless the package relies on
5511 <tt>libtool</tt>'s <tt>libltdl</tt> library, in which case
5512 the <tt>.la</tt> files must go in the run-time library
5517 You must make sure that you use only released versions of
5518 shared libraries to build your packages; otherwise other
5519 users will not be able to run your binaries
5520 properly. Producing source packages that depend on
5521 unreleased compilers is also usually a bad
5527 <heading>Shared libraries</heading>
5530 Packages involving shared libraries should be split up
5531 into several binary packages.</p>
5534 For a straightforward library which has a development
5535 environment and a runtime kit including just shared
5536 libraries you need to create two packages:
5537 <tt><var>libraryname</var><var>soversion</var></tt>, where
5538 <tt><var>soversion</var></tt> is the version number in the
5539 soname of the shared library<footnote>
5541 The soname is the shared object name: it's the thing
5542 that has to match exactly between building an executable
5543 and running it for the dynamic linker to be able run the
5544 program. For example, if the soname of the library is
5545 <tt>libfoo.so.6</tt>, the library package would be
5546 called <tt>libfoo6</tt>.
5549 and <tt><var>libraryname</var><var>soversion</var>-dev</tt>.
5553 If you prefer only to support one development version at a
5554 time you may name the development package
5555 <tt><var>libraryname</var>-dev</tt>; otherwise you may need
5556 to use <prgn>dpkg</prgn>'s Conflicts mechanism (see <ref
5557 id="conflicts">) to ensure that the user only installs one
5558 development version at a time (as different development
5559 versions are likely to have the same header files in them,
5560 which would cause a filename clash if both were installed).
5561 Typically the development version should also have an exact
5562 version dependency on the runtime library, to make sure that
5563 compilation and linking happens correctly. The
5564 <tt>${Source-Version}</tt> substitution variable can be
5565 useful for this purpose.
5569 Packages which use the shared library should have a
5570 dependency on the name of the shared library package,
5571 <tt><var>libraryname</var><var>soversion</var></tt>. When
5572 the soname changes you can have both versions of the library
5573 installed while migrating from the old library to the new.
5577 If your package has some run-time support programs which use
5578 the shared library you must not put them in the shared
5579 library package. If you do that then you won't be able to
5580 install several versions of the shared library without
5581 getting filename clashes. Instead, either create a third
5582 package for the runtime binaries (this package might
5583 typically be named <tt><var>libraryname</var>-runtime</tt>;
5584 note the absence of the <var>soversion</var> in the package
5585 name), or if the development package is small you may
5586 include them in there.
5590 If you have several shared libraries built from the same
5591 source tree you may lump them all together into a single
5592 shared library package, provided that you change all of
5593 their sonames at once (so that you don't get filename
5594 clashes if you try to install different versions of the
5595 combined shared libraries package).
5599 Shared libraries should not be installed executable, since
5600 the dynamic linker does not require this and trying to
5601 execute a shared library usually results in a core dump.
5606 <heading>Scripts</heading>
5609 All command scripts, including the package maintainer
5610 scripts inside the package and used by <prgn>dpkg</prgn>,
5611 should have a <tt>#!</tt> line naming the shell to be used
5612 to interpret them.</p>
5615 In the case of Perl scripts this should be
5616 <tt>#!/usr/bin/perl</tt>.</p>
5619 Shell scripts (<prgn>sh</prgn> and <prgn>bash</prgn>)
5620 should almost certainly start with <tt>set -e</tt> so that
5621 errors are detected. Every script should use
5622 <tt>set -e</tt> or check the exit status of <em>every</em>
5626 The standard shell interpreter <tt>/bin/sh</tt> can be a
5627 symbolic link to any POSIX compatible shell, if <tt>echo
5628 -n</tt> does not generate a newline.<footnote>
5630 Debian policy specifies POSIX behavior for
5631 <tt>/bin/sh</tt>, but <tt>echo -n</tt> has widespread
5632 use in the Linux community (in particular including this
5633 policy, the Linux kernel source, many Debian scripts,
5634 etc.). This <tt>echo -n</tt> mechanism is valid but not
5635 required under POSIX, hence this explicit addition.
5636 Also, rumour has it that this shall be mandated under
5640 Thus, shell scripts specifying <tt>/bin/sh</tt> as
5641 interpreter should only use POSIX features. If a script
5642 requires non-POSIX features from the shell interpreter, the
5643 appropriate shell must be specified in the first line of the
5644 script (e.g., <tt>#!/bin/bash</tt>) and the package must
5645 depend on the package providing the shell (unless the shell
5646 package is marked `Essential', as in the case of
5651 You may wish to restrict your script to POSIX features when
5652 possible so that it may use <tt>/bin/sh</tt> as its
5653 interpreter. If your script works with <prgn>ash</prgn>,
5654 it's probably POSIX compliant, but if you are in doubt, use
5659 Perl scripts should check for errors when making any
5660 system calls, including <tt>open</tt>, <tt>print</tt>,
5661 <tt>close</tt>, <tt>rename</tt> and <tt>system</tt>.
5665 <prgn>csh</prgn> and <prgn>tcsh</prgn> should be avoided as
5666 scripting languages. See <em>Csh Programming Considered
5667 Harmful</em>, one of the <tt>comp.unix.*</tt> FAQs, which
5668 can be found at <url
5669 id="http://language.perl.com/versus/csh.whynot">.<footnote>
5671 It can also be found on
5672 <url id="http://www.cpan.org/doc/FMTEYEWTK/versus/csh.whynot">
5673 or on the ftp site <ftpsite>ftp.cpan.org</ftpsite> as
5674 <ftppath>/pub/perl/CPAN/doc/FMTEYEWTK/versus/csh.whynot</ftppath>.
5677 If an upstream package comes with <prgn>csh</prgn> scripts
5678 then you must make sure that they start with
5679 <tt>#!/bin/csh</tt> and make your package depend on the
5680 <prgn>c-shell</prgn> virtual package.
5684 Any scripts which create files in world-writeable
5685 directories (e.g., in <tt>/tmp</tt>) must use a
5686 mechanism which will fail if a file with the same name
5690 The Debian base system provides the <prgn>tempfile</prgn>
5691 and <prgn>mktemp</prgn> utilities for use by scripts for
5692 this purpose.</p></sect>
5696 <heading>Symbolic links</heading>
5699 In general, symbolic links within a top-level directory
5700 should be relative, and symbolic links pointing from one
5701 top-level directory into another should be absolute. (A
5702 top-level directory is a sub-directory of the root
5703 directory <tt>/</tt>.)</p>
5706 In addition, symbolic links should be specified as short as
5707 possible, i.e., link targets like <tt>foo/../bar</tt> are
5711 Note that when creating a relative link using
5712 <prgn>ln</prgn> it is not necessary for the target of the
5713 link to exist relative to the working directory you're
5714 running <prgn>ln</prgn> from, nor is it necessary to change
5715 directory to the directory where the link is to be made.
5716 Simply include the string that should appear as the target
5717 of the link (this will be a pathname relative to the
5718 directory in which the link resides) as the first argument
5719 to <prgn>ln</prgn>.</p>
5722 For example, in your <prgn>Makefile</prgn> or
5723 <tt>debian/rules</tt>, you can do things like:
5724 <example compact="compact">
5725 ln -fs gcc $(prefix)/bin/cc
5726 ln -fs gcc debian/tmp/usr/bin/cc
5727 ln -fs ../sbin/sendmail $(prefix)/bin/runq
5728 ln -fs ../sbin/sendmail debian/tmp/usr/bin/runq
5732 A symbolic link pointing to a compressed file should always
5733 have the same file extension as the referenced file. (For
5734 example, if a file <tt>foo.gz</tt> is referenced by a
5735 symbolic link, the filename of the link has to end with
5736 `<tt>.gz</tt>' too, as in <tt>bar.gz</tt>.)
5741 <heading>Device files</heading>
5744 Packages must not include device files in the package file
5748 If a package needs any special device files that are not
5749 included in the base system, it must call
5750 <prgn>MAKEDEV</prgn> in the <prgn>postinst</prgn> script,
5751 after asking the user for permission to do so.</p>
5754 Packages must not remove any device files in the
5755 <prgn>postrm</prgn> or any other script. This is left to the
5756 system administrator.</p>
5759 Debian uses the serial devices
5760 <tt>/dev/ttyS*</tt>. Programs using the old
5761 <tt>/dev/cu*</tt> devices should be changed to use
5762 <tt>/dev/ttyS*</tt>.</p>
5765 <sect id="config files">
5766 <heading>Configuration files</heading>
5768 <heading>Definitions</heading>
5771 <tag>configuration file</tag>
5774 A file that affects the operation of a program, or
5775 provides site- or host-specific information, or
5776 otherwise customizes the behavior of a program.
5777 Typically, configuration files are intended to be
5778 modified by the system administrator (if needed or
5779 desired) to conform to local policy or to provide
5780 more useful site-specific behavior.
5784 <tag><tt>conffile</tt></tag>
5787 A file listed in a package's <tt>conffiles</tt>
5788 file, and is treated specially by <prgn>dpkg</prgn>
5789 (see <ref id="configdetails">).
5796 The distinction between these two is important; they are
5797 not interchangeable concepts. Almost all
5798 <tt>conffile</tt>s are configuration files, but many
5799 configuration files are not <tt>conffiles</tt>.
5803 Note that a script that embeds configuration information
5804 (such as most of the files in <tt>/etc/default</tt> and
5805 <tt>/etc/cron.{daily,weekly,monthly}</tt>) is de-facto a
5806 configuration file and should be treated as such.
5811 <heading>Location</heading>
5813 Any configuration files created or used by your package
5814 must reside in <tt>/etc</tt>. If there are several you
5815 should consider creating a subdirectory of <tt>/etc</tt>
5816 named after your package.</p>
5819 If your package creates or uses configuration files
5820 outside of <tt>/etc</tt>, and it is not feasible to modify
5821 the package to use the <tt>/etc</tt>, you should still put
5822 the files in <tt>/etc</tt> and create symbolic links to
5823 those files from the location that the package
5828 <heading>Behavior</heading>
5830 Configuration file handling must conform to the following
5832 <list compact="compact">
5835 local changes must be preserved during a package
5841 configuration files must be preserved when the
5842 package is removed, and only deleted when the
5850 The easy way to achieve this behavior is to make the
5851 configuration file a <tt>conffile</tt>. This is
5852 appropriate only if it is possible to distribute a default
5853 version that will work for most installations, although
5854 some system administrators may choose to modify it. This
5855 implies that the default version will be part of the
5856 package distribution, and must not be modified by the
5857 maintainer scripts during installation (or at any other
5862 In order to ensure that local changes are preserved
5863 correctly, no package may contain or make hard links to
5864 conffiles.<footnote>
5866 Rationale: There are two problems with hard links.
5867 The first is that some editors break the link while
5868 editing one of the files, so that the two files may
5869 unwittingly become unlinked and different. The second
5870 is that <prgn>dpkg</prgn> might break the hard link
5871 while upgrading <tt>conffile</tt>s.
5877 The other way to do it is via the maintainer scripts. In
5878 this case, the configuration file must not be listed as a
5879 <tt>conffile</tt> and must not be part of the package
5880 distribution. If the existence of a file is required for
5881 the package to be sensibly configured it is the
5882 responsibility of the package maintainer to provide
5883 maintainer scripts which correctly create, update and
5884 maintain the file and remove it on purge. (See <ref
5885 id="maintainerscripts"> for more information.) These
5886 scripts must be idempotent (i.e., must work correctly if
5887 <prgn>dpkg</prgn> needs to re-run them due to errors
5888 during installation or removal), must cope with all the
5889 variety of ways <prgn>dpkg</prgn> can call maintainer
5890 scripts, must not overwrite or otherwise mangle the user's
5891 configuration without asking, must not ask unnecessary
5892 questions (particularly during upgrades), and otherwise be
5897 The scripts are not required to configure every possible
5898 option for the package, but only those necessary to get
5899 the package running on a given system. Ideally the
5900 sysadmin should not have to do any configuration other
5901 than that done (semi-)automatically by the
5902 <prgn>postinst</prgn> script.
5906 A common practice is to create a script called
5907 <tt><var>package</var>-configure</tt> and have the
5908 package's <prgn>postinst</prgn> call it if and only if the
5909 configuration file does not already exist. In certain
5910 cases it is useful for there to be an example or template
5911 file which the maintainer scripts use. Such files should
5912 be in <tt>/usr/share/<var>package</var></tt> or
5913 <tt>/usr/lib/<var>package</var></tt> (depending on whether
5914 they are architecture-independent or not). There should
5915 be symbolic links to them from
5916 <tt>/usr/share/doc/<var>package</var>/examples</tt> if
5917 they are examples, and should be perfectly ordinary
5918 <prgn>dpkg</prgn>-handled files (<em>not</em>
5919 configuration files).
5923 These two styles of configuration file handling must
5924 not be mixed, for that way lies madness:
5925 <prgn>dpkg</prgn> will ask about overwriting the file
5926 every time the package is upgraded.
5931 <heading>Sharing configuration files</heading>
5933 Packages which specify the same file as a
5934 <tt>conffile</tt> must be tagged as <em>conflicting</em>
5935 with each other. (This is an instance of the general rule
5936 about not sharing files. Note that neither alternatives
5937 nor diversions are likely to be appropriate in this case;
5938 in particular, <prgn>dpkg</prgn> does not handle diverted
5939 <tt>conffile</tt>s well.)
5943 The maintainer scripts must not alter a <tt>conffile</tt>
5944 of <em>any</em> package, including the one the scripts
5949 If two or more packages use the same configuration file
5950 and it is reasonable for both to be installed at the same
5951 time, one of these packages must be defined as
5952 <em>owner</em> of the configuration file, i.e., it will be
5953 the package which handles that file as a configuration
5954 file. Other packages that use the configuration file must
5955 depend on the owning package if they require the
5956 configuration file to operate. If the other package will
5957 use the configuration file if present, but is capable of
5958 operating without it, no dependency need be declared.</p>
5961 If it is desirable for two or more related packages to
5962 share a configuration file <em>and</em> for all of the
5963 related packages to be able to modify that configuration
5964 file, then the following should be done:
5965 <enumlist compact="compact">
5968 One of the related packages (the "owning" package)
5969 will manage the configuration file with maintainer
5970 scripts as described in the previous section.
5975 The owning package should also provide a program
5976 that the other packages may use to modify the
5982 The related packages must use the provided program
5983 to make any desired modifications to the
5984 configuration file. They should either depend on
5985 the core package to guarantee that the configuration
5986 modifier program is available or accept gracefully
5987 that they cannot modify the configuration file if it
5988 is not. (This is in addition to the fact that the
5989 configuration file may not even be present in the
5997 Sometimes it's appropriate to create a new package which
5998 provides the basic infrastructure for the other packages
5999 and which manages the shared configuration files. (The
6000 <tt>sgml-base</tt> package is a good example.)
6005 <heading>User configuration files ("dotfiles")</heading>
6008 The files in <tt>/etc/skel</tt> will automatically be
6009 copied into new user accounts by <prgn>adduser</prgn>.
6010 No other program should reference the files in
6015 Therefore, if a program needs a dotfile to exist in
6016 advance in <tt>$HOME</tt> to work sensibly, that dotfile
6017 should be installed in <tt>/etc/skel</tt> and treated as a
6022 However, programs that require dotfiles in order to
6023 operate sensibly (dotfiles that they do not create
6024 themselves automatically, that is) are a bad thing.
6025 Furthermore, programs should be configured by the Debian
6026 default installation as behave as closely to the upstream
6027 default behaviour as possible.
6031 Therefore, if a program in a Debian package needs to be
6032 configured in some way in order to operate sensibly, that
6033 should be done using a site-wide configuration file placed
6034 in <tt>/etc</tt>. Only if the program doesn't support a
6035 site-wide default configuration and the package maintainer
6036 doesn't have time to add it may a default per-user file be
6037 placed in <tt>/etc/skel</tt>.
6041 <tt>/etc/skel</tt> should be as empty as we can make it.
6042 This is particularly true because there is no easy (or
6043 necessarily desirable) mechanism for ensuring that the
6044 appropriate dotfiles are copied into the accounts of
6045 existing users when a package is installed.
6051 <heading>Log files</heading>
6053 Log files should usually be named
6054 <tt>/var/log/<var>package</var>.log</tt>. If you have many
6055 log files, or need a separate directory for permission
6056 reasons (<tt>/var/log</tt> is writable only by
6057 <tt>root</tt>), you should usually create a directory named
6058 <tt>/var/log/<var>package</var></tt> and place your log
6063 Log files must be rotated occasionally so that they don't
6064 grow indefinitely; the best way to do this is to drop a log
6065 rotation configuration file into the directory
6066 <tt>/etc/logrotate.d</tt> and use the facilities provided by
6067 logrotate.<footnote>
6069 The traditional approach to log files has been to set up
6070 <em>ad hoc</em> log rotation schemes using simple shell
6071 scripts and cron. While this approach is highly
6072 customizable, it requires quite a lot of sysadmin work.
6073 Even though the original Debian system helped a little
6074 by automatically installing a system which can be used
6075 as a template, this was deemed not enough.
6079 The use of <prgn>logrotate</prgn>, a program developed
6080 by Red Hat, is better, as it centralizes log management.
6081 It has both a configuration file
6082 (<tt>/etc/logrotate.conf</tt>) and a directory where
6083 packages can drop their individual log rotation
6084 configurations (<tt>/etc/logrotate.d</tt>).
6087 Here is a good example for a logrotate config
6088 file (for more information see <manref name="logrotate"
6090 <example compact="compact">
6096 /etc/init.d/foo force-reload
6100 This rotates all files under <tt>/var/log/foo</tt>, saves 12
6101 compressed generations, and forces the daemon to reload its
6102 configuration information after the log rotation.
6106 Log files should be removed when the package is
6107 purged (but not when it is only removed). This should be
6108 done by the <prgn>postrm</prgn> script when it is called
6109 with the argument <tt>purge</tt> (see <ref
6110 id="removedetails">).
6115 <heading>Permissions and owners</heading>
6118 The rules in this section are guidelines for general use.
6119 If necessary you may deviate from the details below.
6120 However, if you do so you must make sure that what is done
6121 is secure and you should try to be as consistent as possible
6122 with the rest of the system. You should probably also
6123 discuss it on <prgn>debian-devel</prgn> first.
6127 Files should be owned by <tt>root.root</tt>, and made
6128 writable only by the owner and universally readable (and
6129 executable, if appropriate), that is mode 644 or 755.
6133 Directories should be mode 755 or (for group-writability)
6134 mode 2775. The ownership of the directory should be
6135 consistent with its mode: if a directory is mode 2775, it
6136 should be owned by the group that needs write access to
6141 Setuid and setgid executables should be mode 4755 or 2755
6142 respectively, and owned by the appropriate user or group.
6143 They should not be made unreadable (modes like 4711 or
6144 2711 or even 4111); doing so achieves no extra security,
6145 because anyone can find the binary in the freely available
6146 Debian package; it is merely inconvenient. For the same
6147 reason you should not restrict read or execute permissions
6148 on non-set-id executables.
6152 Some setuid programs need to be restricted to particular
6153 sets of users, using file permissions. In this case they
6154 should be owned by the uid to which they are set-id, and by
6155 the group which should be allowed to execute them. They
6156 should have mode 4754; again there is no point in making
6157 them unreadable to those users who must not be allowed to
6162 It is possible to arrange that the system administrator can
6163 reconfigure the package to correspond to their local
6164 security policy by changing the permissions on a binary:
6165 they can do this by using <prgn>dpkg-statoverride</prgn>, as
6166 described below.<footnote>
6168 Ordinary files installed by <prgn>dpkg</prgn> (as
6169 opposed to <tt>conffile</tt>s and other similar objects)
6170 normally have their permissions reset to the distributed
6171 permissions when the package is reinstalled. However,
6172 the use of <prgn>dpkg-statoverride</prgn> overrides this
6173 default behaviour. If you use this method, you should
6174 remember to describe <prgn>dpkg-statoverride</prgn> in
6175 the package documentation; being a relatively new
6176 addition to Debian, it is probably not yet well-known.
6179 Another method you should consider is to create a group for
6180 people allowed to use the program(s) and make any setuid
6181 executables executable only by that group.
6185 If you need to create a new user or group for your package
6186 there are two possibilities. Firstly, you may need to
6187 make some files in the binary package be owned by this
6188 user or group, or you may need to compile the user or
6189 group id (rather than just the name) into the binary
6190 (though this latter should be avoided if possible, as in
6191 this case you need a statically allocated id).</p>
6194 If you need a statically allocated id, you must ask for a
6195 user or group id from the <tt>base-passwd</tt> maintainer,
6196 and must not release the package until you have been
6197 allocated one. Once you have been allocated one you must
6198 either make the package depend on a version of the
6199 <tt>base-passwd</tt> package with the id present in
6200 <tt>/etc/passwd</tt> or <tt>/etc/group</tt>, or arrange for
6201 your package to create the user or group itself with the
6202 correct id (using <tt>adduser</tt>) in its
6203 <prgn>preinst</prgn> or <prgn>postinst</prgn>. (Doing it in
6204 the <prgn>postinst</prgn> is to be preferred if it is
6205 possible, otherwise a pre-dependency will be needed on the
6206 <tt>adduser</tt> package.)
6210 On the other hand, the program might be able to determine
6211 the uid or gid from the user or group name at runtime, so
6212 that a dynamically allocated id can be used. In this case
6213 you should choose an appropriate user or group name,
6214 discussing this on <prgn>debian-devel</prgn> and checking
6215 with the base system maintainer that it is unique and that
6216 they do not wish you to use a statically allocated id
6217 instead. When this has been checked you must arrange for
6218 your package to create the user or group if necessary using
6219 <prgn>adduser</prgn> in the <prgn>preinst</prgn> or
6220 <prgn>postinst</prgn> script (again, the latter is to be
6221 preferred if it is possible).
6225 Note that changing the numeric value of an id associated
6226 with a name is very difficult, and involves searching the
6227 file system for all appropriate files. You need to think
6228 carefully whether a static or dynamic id is required, since
6229 changing your mind later will cause problems.
6232 <sect1><heading>The use of <prgn>dpkg-statoverride</prgn></heading>
6234 This section is not intended as policy, but as a
6235 description of the use of <prgn>dpkg-statoverride</prgn>.
6239 <prgn>dpkg-statoverride</prgn> is a replacement for the
6240 deprecated <tt>suidmanager</tt> package. Packages which
6241 previously used <tt>suidmanager</tt> should have a
6242 <tt>Conflicts: suidmanager (<< 0.50)</tt> entry (or even
6243 <tt>(<< 0.52)</tt>), and calls to <tt>suidregister</tt>
6244 and <tt>suidunregister</tt> should now be simply removed
6245 from the maintainer scripts.
6249 If a system administrator wishes to have a file (or
6250 directory or other such thing) installed with owner and
6251 permissions different from those in the distributed Debian
6252 package, he can use the <prgn>dpkg-statoverride</prgn>
6253 program to instruct <prgn>dpkg</prgn> to use the different
6254 settings every time the file is installed. Thus the
6255 package maintainer should distribute the files with their
6256 normal permissions, and leave it for the system
6257 administrator to make any desired changes. For example, a
6258 daemon which is normally required to be setuid root, but
6259 in certain situations could be used without being setuid,
6260 should be installed setuid in the <tt>.deb</tt>. Then the
6261 local system administrator can change this if they wish.
6262 If there are two standard ways of doing it, the package
6263 maintainer can use <tt>debconf</tt> to find out the
6264 preference, and call <prgn>dpkg-statoverride</prgn> in the
6265 maintainer script if necessary to accommodate the system
6266 administrator's choice.
6270 Given the above, <prgn>dpkg-statoverride</prgn> is
6271 essentially a tool for system administrators and would not
6272 normally be needed in the maintainer scripts. There is
6273 one type of situation, though, where calls to
6274 <prgn>dpkg-statoverride</prgn> would be needed in the
6275 maintainer scripts, and that involves packages which use
6276 dynamically allocated user or group ids. In such a
6277 situation, something like the following idiom can be very
6278 helpful in the package's <prgn>postinst</prgn>, where
6279 <tt>sysuser</tt> is a dynamically allocated id:
6281 for i in /usr/bin/foo /usr/sbin/bar
6283 if ! dpkg-statoverride --list $i >/dev/null
6285 dpkg-statoverride --update --add sysuser root 4755 $i
6289 The corresponding <tt>dpkg-statoverride --remove</tt>
6290 calls can then be made unconditionally when the package is
6297 <chapt id="customized-programs">
6298 <heading>Customized programs</heading>
6300 <sect id="arch-spec">
6301 <heading>Architecture specification strings</heading>
6304 If a program needs to specify an <em>architecture specification
6305 string</em> in some place, the following format should be
6306 used: <var>arch</var>-<var>os</var><footnote>
6308 The following architectures and operating systems are
6309 currently recognised by <prgn>dpkg-archictecture</prgn>.
6310 The architecture, <tt><var>arch</var></tt>, is one of
6311 the following: <tt>alpha</tt>, <tt>arm</tt>,
6312 <tt>hppa</tt>, <tt>i386</tt>, <tt>ia64</tt>,
6313 <tt>m68k</tt>, <tt>mips</tt>, <tt>mipsel</tt>,
6314 <tt>powerpc</tt>, <tt>s390</tt>, <tt>sh</tt>,
6315 <tt>sheb</tt>, <tt>sparc</tt> and <tt>sparc64</tt>. The
6316 operating system, <tt><var>os</var></tt>, is one of:
6317 <tt>linux</tt>, <tt>gnu</tt>, <tt>freebsd</tt> and
6318 <tt>openbsd</tt>. Use of <tt>gnu</tt> in this string is
6319 reserved for the GNU/Hurd operating system.
6325 Note that we don't want to use
6326 <tt><var>arch</var>-debian-linux</tt> to apply to the rule
6327 <tt><var>architecture</var>-<var>vendor</var>-<var>os</var></tt>
6328 since this would make our programs incompatible with other
6329 Linux distributions. We also don't use something like
6330 <tt><var>arch</var>-unknown-linux</tt>, since the
6331 <tt>unknown</tt> does not look very good.
6336 <heading>Daemons</heading>
6339 The configuration files <tt>/etc/services</tt>,
6340 <tt>/etc/protocols</tt>, and <tt>/etc/rpc</tt> are managed
6341 by the <prgn>netbase</prgn> package and must not be modified
6346 If a package requires a new entry in one of these files, the
6347 maintainer should get in contact with the
6348 <prgn>netbase</prgn> maintainer, who will add the entries
6349 and release a new version of the <prgn>netbase</prgn>
6354 The configuration file <tt>/etc/inetd.conf</tt> must not be
6355 modified by the package's scripts except via the
6356 <prgn>update-inetd</prgn> script or the
6357 <tt>DebianNet.pm</tt> Perl module. See their documentation
6358 for details on how to add entries.
6362 If a package wants to install an example entry into
6363 <tt>/etc/inetd.conf</tt>, the entry must be preceded with
6364 exactly one hash character (<tt>#</tt>). Such lines are
6365 treated as `commented out by user' by the
6366 <prgn>update-inetd</prgn> script and are not changed or
6367 activated during package updates.
6372 <heading>Using pseudo-ttys and modifying wtmp, utmp and
6376 Some programs need to create pseudo-ttys. This should be done
6377 using Unix98 ptys if the C library supports it. The resulting
6378 program must not be installed setuid root, unless that
6379 is required for other functionality.
6383 The files <tt>/var/run/utmp</tt>, <tt>/var/log/wtmp</tt> and
6384 <tt>/var/log/lastlog</tt> must be installed writeable by
6385 group <tt>utmp</tt>. Programs which need to modify those
6386 files must be installed setgid <tt>utmp</tt>.
6391 <heading>Editors and pagers</heading>
6394 Some programs have the ability to launch an editor or pager
6395 program to edit or display a text document. Since there are
6396 lots of different editors and pagers available in the Debian
6397 distribution, the system administrator and each user should
6398 have the possibility to choose his/her preferred editor and
6403 In addition, every program should choose a good default
6404 editor/pager if none is selected by the user or system
6409 Thus, every program that launches an editor or pager must
6410 use the EDITOR or PAGER environment variable to determine
6411 the editor or pager the user wishes to use. If these
6412 variables are not set, the programs <tt>/usr/bin/editor</tt>
6413 and <tt>/usr/bin/pager</tt> should be used, respectively.
6417 These two files are managed through the <prgn>dpkg</prgn>
6418 `alternatives' mechanism. Thus every package providing an
6419 editor or pager must call the
6420 <prgn>update-alternatives</prgn> script to register these
6425 If it is very hard to adapt a program to make use of the
6426 EDITOR or PAGER variables, that program may be configured to
6427 use <tt>/usr/bin/sensible-editor</tt> and
6428 <tt>/usr/bin/sensible-pager</tt> as the editor or pager
6429 program respectively. These are two scripts provided in the
6430 Debian base system that check the EDITOR and PAGER variables
6431 and launch the appropriate program, and fall back to
6432 <tt>/usr/bin/editor</tt> and <tt>/usr/bin/pager</tt> if the
6433 variable is not set.
6437 A program may also use the VISUAL environment variable to
6438 determine the user's choice of editor. If it exists, it
6439 should take precedence over EDITOR. This is in fact what
6440 <tt>/usr/bin/sensible-editor</tt> does.
6444 It is not required for a package to depend on
6445 <tt>editor</tt> and <tt>pager</tt>, nor is it required for a
6446 package to provide such virtual packages.<footnote>
6448 The Debian base system already provides an editor and a
6455 <sect id="web-appl">
6456 <heading>Web servers and applications</heading>
6459 This section describes the locations and URLs that should
6460 be used by all web servers and web applications in the
6468 Cgi-bin executable files are installed in the
6470 <example compact="compact">
6471 /usr/lib/cgi-bin/<var>cgi-bin-name</var>
6473 and should be referred to as
6474 <example compact="compact">
6475 http://localhost/cgi-bin/<var>cgi-bin-name</var>
6480 <item><p>Access to HTML documents</p>
6483 HTML documents for a package are stored in
6484 <tt>/usr/share/doc/<var>package</var></tt> but should
6485 be accessed via symlinks as
6486 <tt>/usr/doc/<var>package</var></tt><footnote>
6488 for backward compatibility; see <ref
6492 and can be referred to as
6493 <example compact="compact">
6494 http://localhost/doc/<var>package</var>/<var>filename</var>
6499 <item><p>Web Document Root</p>
6502 Web Applications should try to avoid storing files in
6503 the Web Document Root. Instead they should use the
6504 /usr/share/doc/<var>package</var> directory for
6505 documents and register the Web Application via the
6506 menu package. If access to the web document root is
6507 unavoidable then use
6508 <example compact="compact">
6511 as the Document Root. This might be just a symbolic
6512 link to the location where the system administrator
6513 has put the real document root.
6517 </enumlist></p></sect>
6520 <sect id="mail-transport-agents">
6521 <heading>Mail transport, delivery and user agents</heading>
6524 Debian packages which process electronic mail, whether mail
6525 user agents (MUAs) or mail transport agents (MTAs), must
6526 ensure that they are compatible with the configuration
6527 decisions below. Failure to do this may result in lost
6528 mail, broken <tt>From:</tt> lines, and other serious brain
6533 The mail spool is <tt>/var/mail</tt> and the interface to
6534 send a mail message is <tt>/usr/sbin/sendmail</tt> (as per
6535 the FHS). On older systems, the mail spool may be
6536 physically located in <tt>/var/spool/mail</tt>, but all
6537 access to the mail spool should be via the
6538 <tt>/var/mail</tt> symlink. The mail spool is part of the
6539 base system and not part of the MTA package.
6543 All Debian MUAs, MTAs, MDAs and other mailbox accessing
6544 programs (such as IMAP daemons) must lock the mailbox in an
6545 NFS-safe way. This means that <tt>fcntl()</tt> locking must
6546 be combined with dot locking. To avoid deadlocks, a program
6547 should use <tt>fcntl()</tt> first and dot locking after
6548 this, or alternatively implement the two locking methods in
6549 a non blocking way<footnote>
6551 If it is not possible to establish both locks, the
6552 system shouldn't wait for the second lock to be
6553 established, but remove the first lock, wait a (random)
6554 time, and start over locking again.
6556 </footnote>. Using the functions <tt>maillock</tt> and
6557 <tt>mailunlock</tt> provided by the
6558 <tt>liblockfile*</tt><footnote>
6560 You will need to depend on <tt>liblockfile1
6561 (>>1.01)</tt> to use these functions.
6563 </footnote> packages is the recommended way to realize this.
6567 Mailboxes are generally mode 660
6568 <tt><var>user</var>.mail</tt> unless the system
6569 administrator has chosen otherwise. A MUA may remove a
6570 mailbox (unless it has nonstandard permissions) in which
6571 case the MTA or another MUA must recreate it if needed.
6572 Mailboxes must be writable by group mail.
6576 The mail spool is 2775 <tt>root.mail</tt>, and MUAs should
6577 be setgid mail to do the locking mentioned above (and
6578 must obviously avoid accessing other users' mailboxes
6579 using this privilege).</p>
6582 <tt>/etc/aliases</tt> is the source file for the system mail
6583 aliases (e.g., postmaster, usenet, etc.), it is the one
6584 which the sysadmin and <prgn>postinst</prgn> scripts may
6585 edit. After <tt>/etc/aliases</tt> is edited the program or
6586 human editing it must call <prgn>newaliases</prgn>. All MTA
6587 packages must come with a <prgn>newaliases</prgn> program,
6588 even if it does nothing, but older MTA packages did not do
6589 this so programs should not fail if <prgn>newaliases</prgn>
6590 cannot be found. Note that because of this, all MTA
6591 packages must have <tt>Provides</tt>, <tt>Conflicts</tt> and
6592 <tt>Replaces: mail-transport-agent</tt> control file
6597 The convention of writing <tt>forward to
6598 <var>address</var></tt> in the mailbox itself is not
6599 supported. Use a <tt>.forward</tt> file instead.</p>
6602 The <prgn>rmail</prgn> program used by UUCP
6603 for incoming mail should be <tt>/usr/sbin/rmail</tt>.
6604 Likewise, <prgn>rsmtp</prgn>, for receiving
6605 batch-SMTP-over-UUCP, should be <tt>/usr/sbin/rsmtp</tt> if it
6609 If your package needs to know what hostname to use on (for
6610 example) outgoing news and mail messages which are generated
6611 locally, you should use the file <tt>/etc/mailname</tt>. It
6612 will contain the portion after the username and <tt>@</tt>
6613 (at) sign for email addresses of users on the machine
6614 (followed by a newline).
6618 Such package should check for the existence of this file
6619 when it is being configured. If it exists, it should be
6620 used without comment, although an MTA's configuration script
6621 may wish to prompt the user even if it finds that this file
6622 exists. If the file does not exist, the package should
6623 prompt the user for the value (preferably using
6624 <prgn>debconf</prgn>) and store it in <tt>/etc/mailname</tt>
6625 as well as using it in the package's configuration. The
6626 prompt should make it clear that the name will not just be
6627 used by that package. For example, in this situation the
6628 <tt>inn</tt> package could say something like:
6629 <example compact="compact">
6630 Please enter the `mail name' of your system. This is the
6631 hostname portion of the address to be shown on outgoing
6632 news and mail messages. The default is
6633 <var>syshostname</var>, your system's host name. Mail
6634 name [`<var>syshostname</var>']:
6636 where <var>syshostname</var> is the output of <tt>hostname
6642 <heading>News system configuration</heading>
6645 All the configuration files related to the NNTP (news)
6646 servers and clients should be located under
6647 <tt>/etc/news</tt>.</p>
6650 There are some configuration issues that apply to a number
6651 of news clients and server packages on the machine. These
6655 <tag><tt>/etc/news/organization</tt></tag>
6656 <item><p>A string which should appear as the
6657 organization header for all messages posted
6658 by NNTP clients on the machine</p></item>
6660 <tag><tt>/etc/news/server</tt></tag>
6661 <item><p>Contains the FQDN of the upstream NNTP
6662 server, or localhost if the local machine is
6663 an NNTP server.</p></item>
6666 Other global files may be added as required for cross-package news
6667 configuration.</p></sect>
6671 <heading>Programs for the X Window System</heading>
6674 <heading>Providing X support and package priorities</heading>
6677 Programs that can be configured with support for the X
6678 Window System must be configured to do so and must declare
6679 any package dependencies necessary to satisfy their
6680 runtime requirements when using the X Window System. If
6681 such a package is of higher priority than the X packages
6682 on which it depends, it is required that either the
6683 X-specific components be split into a separate package, or
6684 that an alternative version of the package, which includes
6685 X support, be provided, or that the package's priority be
6691 <heading>Packages providing an X server</heading>
6694 Packages that provide an X server that, directly or
6695 indirectly, communicates with real input and display
6696 hardware should declare in their control data that they
6697 provide the virtual package <tt>xserver</tt>.<footnote>
6699 This implements current practice, and provides an
6700 actual policy for usage of the <tt>xserver</tt>
6701 virtual package which appears in the virtual packages
6702 list. In a nutshell, X servers that interface
6703 directly with the display and input hardware or via
6704 another subsystem (e.g., GGI) should provide
6705 <tt>xserver</tt>. Things like <tt>Xvfb</tt>,
6706 <tt>Xnest</tt>, and <tt>Xprt</tt> should not.
6713 <heading>Packages providing a terminal emulator</heading>
6716 Packages that provide a terminal emulator for the X Window
6717 System which meet the criteria listed below should declare
6718 in their control data that they provide the virtual
6719 package <tt>x-terminal-emulator</tt>. They should also
6720 register themselves as an alternative for
6721 <tt>/usr/bin/x-terminal-emulator</tt>, with a priority of
6726 To be an <tt>x-terminal-emulator</tt>, a program must:
6727 <list compact="compact">
6729 Be able to emulate a DEC VT100 terminal, or a
6730 compatible terminal.
6734 Support the command-line option <tt>-e
6735 <var>command</var></tt>, which creates a new
6736 terminal window<footnote>
6738 "New terminal window" does not necessarily mean
6739 a new top-level X window directly parented by
6740 the window manager; it could, if the terminal
6741 emulator application were so coded, be a new
6742 "view" in a multiple-document interface (MDI).
6745 and runs the specified <var>command</var>.
6749 Support the command-line option <tt>-T
6750 <var>title</var></tt>, which creates a new terminal
6751 window with the window title <var>title</var>.
6758 <heading>Packages providing a window manager</heading>
6761 Packages that provide a window manager should declare in
6762 their control data that they provide the virtual package
6763 <tt>x-window-manager</tt>. They should also register
6764 themselves as an alternative for
6765 <tt>/usr/bin/x-window-manager</tt>, with a priority
6766 calculated as follows:
6767 <list compact="compact">
6768 <item><p>Start with a priority of 20.</p></item>
6772 If the window manager supports the Debian menu
6773 system, add 20 points if this support is available
6774 in the package's default configuration (i.e., no
6775 configuration files belonging to the system or user
6776 have to be edited to activate the feature); if
6777 configuration files must be modified, add only 10
6784 If the window manager permits the X session to be
6785 restarted using a <em>different</em> window manager
6786 (without killing the X server) in its default
6787 configuration, add 10 points; otherwise add none.
6795 <heading>Packages providing fonts</heading>
6798 Packages that provide fonts for the X Window
6801 For the purposes of Debian Policy, a "font for the X
6802 Window System" is one which is accessed via X protocol
6803 requests. Fonts for the Linux console, for PostScript
6804 renderers, or any other purpose, do not fit this
6805 definition. Any tool which makes such fonts available
6806 to the X Window System, however, must abide by this
6810 must do a number of things to ensure that they are both
6811 available without modification of the X or font server
6812 configuration, and that they do not corrupt files used by
6813 other font packages to register information about
6818 Fonts of any type supported by the X Window System
6819 must be be in a separate binary package from any
6820 executables, libraries, or documentation (except
6821 that specific to the fonts shipped, such as their
6822 license information). If one or more of the fonts
6823 so packaged are necessary for proper operation of
6824 the package with which they are associated the font
6825 package may be Recommended; if the fonts merely
6826 provide an enhancement, a Suggests relationship may
6827 be used. Packages must not Depend on font
6830 This is because the X server may retrieve fonts
6831 from the local filesystem or over the network
6832 from an X font server; the Debian package system
6833 is empowered to deal only with the local
6842 BDF fonts must be converted to PCF fonts with the
6843 <prgn>bdftopcf</prgn> utility (available in the
6844 <tt>xutils</tt> package, <tt>gzip</tt>ped, and
6845 placed in a directory that corresponds to their
6847 <list compact="compact">
6849 100 dpi fonts must be placed in
6850 <tt>/usr/X11R6/lib/X11/fonts/100dpi/</tt>.
6854 75 dpi fonts must be placed in
6855 <tt>/usr/X11R6/lib/X11/fonts/75dpi/</tt>.
6859 Character-cell fonts, cursor fonts, and other
6860 low-resolution fonts must be placed in
6861 <tt>/usr/X11R6/lib/X11/fonts/misc/</tt>.
6868 Speedo fonts must be placed in
6869 <tt>/usr/X11R6/lib/X11/fonts/Speedo/</tt>.
6873 Type 1 fonts must be placed in
6874 <tt>/usr/X11R6/lib/X11/fonts/Type1/</tt>. If font
6875 metric files are available, they must be placed here
6881 Subdirectories of <tt>/usr/X11R6/lib/X11/fonts/</tt>
6882 other than those listed above must be neither
6883 created nor used. (The <tt>PEX</tt>, <tt>CID</tt>,
6884 and <tt>cyrillic</tt> directories are excepted for
6885 historical reasons, but installation of files into
6886 these directories remains discouraged.)
6892 Font packages may, instead of placing files directly
6893 in the X font directories listed above, provide
6894 symbolic links in the font directory which point to
6895 the files' actual location in the filesystem. Such
6896 a location must comply with the FHS.
6902 Font packages should not contain both 75dpi and
6903 100dpi versions of a font. If both are available,
6904 they should be provided in separate binary packages
6905 with <tt>-75dpi</tt> or <tt>-100dpi</tt> appended to
6906 the names of the packages containing the
6907 corresponding fonts.
6913 Fonts destined for the <tt>misc</tt> subdirectory
6914 should not be included in the same package as 75dpi
6915 or 100dpi fonts; instead, they should be provided in
6916 a separate package with <tt>-misc</tt> appended to
6923 Font packages must not provide the files
6924 <tt>fonts.dir</tt>, <tt>fonts.alias</tt>, or
6925 <tt>fonts.scale</tt> in a font directory:
6928 <tt>fonts.dir</tt> files must not be provided at all.
6933 <tt>fonts.alias</tt> and <tt>fonts.scale</tt>
6934 files, if needed, should be provided in the
6936 <tt>/etc/X11/fonts/<var>fontdir</var>/<var>package</var>.<var>extension</var></tt>,
6937 where <var>fontdir</var> is the name of the
6939 <tt>/usr/X11R6/lib/X11/fonts/</tt> where the
6940 package's corresponding fonts are stored
6941 (e.g., <tt>75dpi</tt> or <tt>misc</tt>),
6942 <var>package</var> is the name of the package
6943 that provides these fonts, and
6944 <var>extension</var> is either <tt>scale</tt>
6945 or <tt>alias</tt>, whichever corresponds to
6955 Font packages must declare a dependency on
6956 <tt>xutils (>> 4.0.3)</tt> in their control
6963 Font packages that provide one or more
6964 <tt>fonts.scale</tt> files as described above must
6965 invoke <prgn>update-fonts-scale</prgn> on each
6966 directory into which they installed fonts
6967 <em>before</em> invoking
6968 <prgn>update-fonts-dir</prgn> on that directory.
6969 This invocation must occur in both the
6970 <prgn>postinst</prgn> (for all arguments) and
6971 <prgn>postrm</prgn> (for all arguments except
6972 <tt>upgrade</tt>) scripts.
6978 Font packages that provide one or more
6979 <tt>fonts.alias</tt> files as described above must
6980 invoke <prgn>update-fonts-alias</prgn> on each
6981 directory into which they installed fonts. This
6982 invocation must occur in both the
6983 <prgn>postinst</prgn> (for all arguments) and
6984 <prgn>postrm</prgn> (for all arguments except
6985 <tt>upgrade</tt>) scripts.
6991 Font packages must invoke
6992 <prgn>update-fonts-dir</prgn> on each directory into
6993 which they installed fonts. This invocation must
6994 occur in both the <prgn>postinst</prgn> (for all
6995 arguments) and <prgn>postrm</prgn> (for all
6996 arguments except <tt>upgrade</tt>) scripts.
7002 Font packages must not provide alias names for the
7003 fonts they include which collide with alias names
7004 already in use by fonts already packaged.
7010 Font packages must not provide fonts with the same
7011 XLFD registry name as another font already packaged.
7019 <heading>Application defaults files</heading>
7022 Application defaults files must be installed in the
7023 directory <tt>/etc/X11/app-defaults/</tt> (use of a
7024 localized subdirectory of <tt>/etc/X11/</tt> as described
7025 in the <em>X Toolkit Intrinsics - C Language
7026 Interface</em> manual is also permitted). They must be
7027 registered as <tt>conffile</tt>s or handled as
7028 configuration files. Packages must not provide the
7029 directory <tt>/usr/X11R6/lib/X11/app-defaults/</tt>.
7033 Customization of programs' X resources may also be
7034 supported with the provision of a file with the same name
7035 as that of the package placed in the
7036 <tt>/etc/X11/Xresources/</tt> directory, which must
7037 registered as a <tt>conffile</tt> or handled as a
7038 configuration file.<footnote>
7040 Note that this mechanism is not the same as using
7041 app-defaults; app-defaults are tied to the client
7042 binary on the local filesystem, whereas X resources
7043 are stored in the X server and affect all connecting
7047 <em>Important:</em> packages that install files into the
7048 <tt>/etc/X11/Xresources/</tt> directory must conflict with
7049 <tt>xbase (<< 3.3.2.3a-2)</tt>; if this is not done
7050 it is possible for the installing package to destroy a
7051 previously-existing <tt>/etc/X11/Xresources</tt> file
7052 which had been customized by the system administrator.
7057 <heading>Installation directory issues</heading>
7060 Packages using the X Window System should not be
7061 configured to install files under the <tt>/usr/X11R6/</tt>
7062 directory unless they use <prgn>imake</prgn>. The
7063 <tt>/usr/X11R6/</tt> directory hierarchy should be
7064 regarded as deprecated for all packages except the X
7065 Window System itself, and those which use the
7066 <prgn>imake</prgn> program it provides, in which case the
7067 packages may transition out of the <tt>/usr/X11R6/</tt>
7068 directory at the maintainer's discretion.<footnote>
7070 <prgn>Imake</prgn>-using programs are exempt because,
7071 as long as they are written correctly, the pathnames
7072 they use to locate resources and install themselves
7073 are derived wholly from the X Window System
7074 configuration. Thus, in the event that the X Window
7075 System moves to <tt>/usr/X11R7/</tt>,
7076 <tt>/usr/X12/</tt>, or just plain <tt>/usr/</tt>, all
7077 that is required for these programs is a recompile
7078 against the corresponding X Window System library
7079 development packages.
7082 Programs that use GNU <prgn>autoconf</prgn> and
7083 <prgn>automake</prgn> are usually easily configured at
7084 compile time to use <tt>/usr/</tt> instead of
7085 <tt>/usr/X11R6/</tt>, and this should be done whenever
7086 possible. Configuration files for window managers and
7087 display managers should be placed in a subdirectory of
7088 <tt>/etc/X11/</tt> corresponding to the package name due
7089 to these programs' tight integration with the mechanisms
7090 of the X Window System. Application-level programs should
7091 use the <tt>/etc/</tt> directory unless otherwise mandated
7092 by policy. The installation of files into subdirectories
7093 of <tt>/usr/X11R6/include/X11/</tt> and
7094 <tt>/usr/X11R6/lib/X11/</tt> is permitted but discouraged;
7095 package maintainers should determine if subdirectories of
7096 <tt>/usr/lib/</tt> and <tt>/usr/share/</tt> can be used
7097 instead. (The use of symbolic links from the
7098 <tt>X11R6</tt> directories to other FHS-compliant
7099 locations is encouraged if the program is not easily
7100 configured to look elsewhere for its files.) Packages
7101 must not provide or install files into the directories
7102 <tt>/usr/bin/X11/</tt>, <tt>/usr/include/X11/</tt> or
7103 <tt>/usr/lib/X11/</tt>. Files within a package should,
7104 however, make reference to these directories, rather than
7105 their <tt>X11R6</tt>-named counterparts
7106 <tt>/usr/X11R6/bin/</tt>, <tt>/usr/X11R6/include/X11/</tt>
7107 and <tt>/usr/X11R6/lib/X11/</tt>, if the resources being
7108 referred to have not been moved to other FHS-compliant
7114 <heading>The OSF/Motif and OpenMotif libraries</heading>
7117 <em>Programs that require the non-DFSG-compliant OSF/Motif or
7118 OpenMotif libraries</em><footnote>
7120 OSF/Motif and OpenMotif are collectively referred to as
7121 "Motif" in this policy document.
7124 should be compiled against and tested with LessTif (a free
7125 re-implementation of Motif) instead. If the maintainer
7126 judges that the program or programs do not work
7127 sufficiently well with LessTif to be distributed and
7128 supported, but do so when compiled against Motif, then two
7129 versions of the package should be created; one linked
7130 statically against Motif and with <tt>-smotif</tt>
7131 appended to the package name, and one linked dynamically
7132 against Motif and with <tt>-dmotif</tt> appended to the
7133 package name. Both Motif-linked versions are dependent
7134 upon non-DFSG-compliant software and thus cannot be
7135 uploaded to the <em>main</em> distribution; if the
7136 software is itself DFSG-compliant it may be uploaded to
7137 the <em>contrib</em> distribution. While known existing
7138 versions of Motif permit unlimited redistribution of
7139 binaries linked against the library (whether statically or
7140 dynamically), it is the package maintainer's
7141 responsibility to determine whether this is permitted by
7142 the license of the copy of Motif in his or her possession.
7148 <heading>Perl programs and modules</heading>
7150 Perl programs and modules should follow the current Perl
7151 policy as defined in the file found on
7152 <ftpsite>ftp.debian.org</ftpsite> in
7153 <ftppath>/debian/doc/package-developer/perl-policy.txt.gz</ftppath>
7154 or your local mirror. In addition, it is included in the
7155 <tt>debian-policy</tt> package.
7160 <heading>Emacs lisp programs</heading>
7163 Please refer to the `Debian Emacs Policy' (documented in
7164 <tt>debian-emacs-policy.gz</tt> of the
7165 <prgn>emacsen-common</prgn> package) for details of how to
7166 package emacs lisp programs.
7171 <heading>Games</heading>
7174 The permissions on <tt>/var/games</tt> are mode 755, owner
7175 <tt>root</tt> and group <tt>root</tt>.
7179 Each game decides on its own security policy.</p>
7182 Games which require protected, privileged access to
7183 high-score files, savegames, etc., may be made
7184 set-<em>group</em>-id (mode 2755) and owned by
7185 <tt>root.games</tt>, and use files and directories with
7186 appropriate permissions (770 <tt>root.games</tt>, for
7187 example). They must not be made
7188 set-<em>user</em>-id, as this causes security problems. (If
7189 an attacker can subvert any set-user-id game they can
7190 overwrite the executable of any other, causing other players
7191 of these games to run a Trojan horse program. With a
7192 set-group-id game the attacker only gets access to less
7193 important game data, and if they can get at the other
7194 players' accounts at all it will take considerably more
7198 Some packages, for example some fortune cookie programs, are
7199 configured by the upstream authors to install with their
7200 data files or other static information made unreadable so
7201 that they can only be accessed through set-id programs
7202 provided. You should not do this in a Debian package: anyone can
7203 download the <tt>.deb</tt> file and read the data from it,
7204 so there is no point making the files unreadable. Not
7205 making the files unreadable also means that you don't have
7206 to make so many programs set-id, which reduces the risk of a
7210 As described in the FHS, binaries of games should be
7211 installed in the directory <tt>/usr/games</tt>. This also
7212 applies to games that use the X Window System. Manual pages
7213 for games (X and non-X games) should be installed in
7214 <tt>/usr/share/man/man6</tt>.</p>
7218 <chapt id="docs"><heading>Documentation</heading>
7222 <heading>Manual pages</heading>
7225 You should install manual pages in <prgn>nroff</prgn> source
7226 form, in appropriate places under <tt>/usr/share/man</tt>. You
7227 should only use sections 1 to 9 (see the FHS for more
7228 details). You must not install a preformatted `cat
7232 Each program, utility, and function should have an
7233 associated manpage included in the same package. It is
7234 suggested that all configuration files also have a manual
7235 page included as well.
7239 If no manual page is available for a particular program,
7240 utility, function or configuration file and this is reported
7241 as a bug to the Debian Bug Tracking System, a symbolic link
7242 from the requested manual page to the <manref
7243 name="undocumented" section="7"> manual page may be
7244 provided. This symbolic link can be created from
7245 <tt>debian/rules</tt> like this:
7246 <example compact="compact">
7247 ln -s ../man7/undocumented.7.gz \
7248 debian/tmp/usr/share/man/man[1-9]/<var>requested_manpage</var>.[1-9].gz
7250 This manpage claims that the lack of a manpage has been
7251 reported as a bug, so you may only do this if it really has
7252 (you can report it yourself, if you like). Do not close the
7253 bug report until a proper manpage is available.</p>
7256 You may forward a complaint about a missing manpage to the
7257 upstream authors, and mark the bug as forwarded in the
7258 Debian bug tracking system. Even though the GNU Project do
7259 not in general consider the lack of a manpage to be a bug,
7260 we do; if they tell you that they don't consider it a bug
7261 you should leave the bug in our bug tracking system open
7265 Manual pages should be installed compressed using <tt>gzip
7269 If one manpage needs to be accessible via several names it
7270 is better to use a symbolic link than the <tt>.so</tt>
7271 feature, but there is no need to fiddle with the relevant
7272 parts of the upstream source to change from <tt>.so</tt> to
7273 symlinks: don't do it unless it's easy. You should not
7274 create hard links in the manual page directories, nor put
7275 absolute filenames in <tt>.so</tt> directives. The filename
7276 in a <tt>.so</tt> in a manpage should be relative to the
7277 base of the manpage tree (usually
7278 <tt>/usr/share/man</tt>). If you do not create any links
7279 (whether symlinks, hard links, or <tt>.so</tt> directives)
7280 in the filesystem to the alternate names of the manpage,
7281 then you should not rely on <prgn>man</prgn> finding your
7282 manpage under those names based solely on the information in
7283 the manpage's header.<footnote>
7285 Supporting this in <prgn>man</prgn> often requires
7286 unreasonable processing time to find a manual page or to
7287 report that none exists, and moves knowledge into man's
7288 database that would be better left in the filesystem.
7289 This support is therefore deprecated and will cease to
7290 be present in the future.
7297 <heading>Info documents</heading>
7300 Info documents should be installed in <tt>/usr/share/info</tt>.
7301 They should be compressed with <tt>gzip -9</tt>.</p>
7304 Your package should call <prgn>install-info</prgn> to update
7305 the Info <tt>dir</tt> file in its <prgn>postinst</prgn>
7306 script when called with a <tt>configure</tt> argument, for
7308 <example compact="compact">
7309 install-info --quiet --section Development Development \
7310 /usr/share/info/foobar.info
7314 It is a good idea to specify a section for the location of
7315 your program; this is done with the <tt>--section</tt>
7316 switch. To determine which section to use, you should look
7317 at <tt>/usr/share/info/dir</tt> on your system and choose the most
7318 relevant (or create a new section if none of the current
7319 sections are relevant). Note that the <tt>--section</tt>
7320 flag takes two arguments; the first is a regular expression
7321 to match (case-insensitively) against an existing section,
7322 the second is used when creating a new one.</p>
7325 You should remove the entries in the <prgn>prerm</prgn>
7326 script when called with a <tt>remove</tt> argument:
7327 <example compact="compact">
7328 install-info --quiet --remove /usr/share/info/foobar.info
7332 If <prgn>install-info</prgn> cannot find a description entry
7333 in the Info file you must supply one. See <manref
7334 name="install-info" section="8"> for details.</p>
7338 <heading>Additional documentation</heading>
7341 Any additional documentation that comes with the package may
7342 be installed at the discretion of the package maintainer.
7343 Text documentation should be installed in the directory
7344 <tt>/usr/share/doc/<var>package</var></tt>, where
7345 <var>package</var> is the name of the package, and
7346 compressed with <tt>gzip -9</tt> unless it is small.</p>
7349 If a package comes with large amounts of documentation which
7350 many users of the package will not require you should create
7351 a separate binary package to contain it, so that it does not
7352 take up disk space on the machines of users who do not need
7353 or want it installed.</p>
7356 It is often a good idea to put text information files
7357 (<tt>README</tt>s, changelogs, and so forth) that come with
7358 the source package in <tt>/usr/share/doc/<var>package</var></tt>
7359 in the binary package. However, you don't need to install
7360 the instructions for building and installing the package, of
7364 Files in <tt>/usr/share/doc</tt> should not be referenced by
7365 any program, and the system administrator should be able to
7366 delete them without causing any programs to break. Any files
7367 that are referenced by programs but are also useful as
7368 standalone documentation should be installed under
7369 <tt>/usr/share/<var>package</var>/</tt> with symbolic links
7370 from <tt>/usr/share/doc/<var>package</var>/</tt>.
7376 <heading>Accessing the documentation</heading>
7379 Former Debian releases placed all additional documentation
7380 in <tt>/usr/doc/<var>package</var></tt>. To realize a
7382 <tt>/usr/share/doc/<var>package</var></tt>, each package
7383 must maintain a symlink <tt>/usr/doc/<var>package</var></tt>
7384 that points to the new location of its documentation in
7385 <tt>/usr/share/doc/<var>package</var></tt><footnote>These
7386 symlinks will be removed in the future, but they have to be
7387 there for compatibility reasons until all packages have
7388 moved and the policy is changed accordingly.</footnote>.
7389 The symlink must be created when the package is installed;
7390 it cannot be contained in the package itself due to problems
7391 with <prgn>dpkg</prgn>. One reasonable way to accomplish
7392 this is to put the following in the package's
7393 <prgn>postinst</prgn><footnote>
7395 The <tt>debhelper</tt> script
7396 <prgn>dh_installdocs</prgn> does this automatically.
7399 <example compact="compact">
7400 if [ "$1" = "configure" ]; then
7401 if [ -d /usr/doc -a ! -e /usr/doc/<var>package</var> \
7402 -a -d /usr/share/doc/<var>package</var> ]; then
7403 ln -sf ../share/doc/<var>package</var> /usr/doc/<var>package</var>
7407 and the following in the package's <prgn>prerm</prgn>:
7408 <example compact="compact">
7409 if [ \( "$1" = "upgrade" -o "$1" = "remove" \) \
7410 -a -L /usr/doc/<var>package</var> ]; then
7411 rm -f /usr/doc/<var>package</var>
7418 <heading>Preferred documentation formats</heading>
7421 The unification of Debian documentation is being carried out
7425 If your package comes with extensive documentation in a
7426 markup format that can be converted to various other formats
7427 you should if possible ship HTML versions in a binary
7428 package, in the directory
7429 <tt>/usr/share/doc/<var>appropriate-package</var></tt> or
7430 its subdirectories.<footnote>
7432 The rationale: The important thing here is that HTML
7433 docs should be available in <em>some</em> package, not
7434 necessarily in the main binary package.
7440 Other formats such as PostScript may be provided at the
7441 package maintainer's discretion.
7445 <sect id="copyrightfile">
7446 <heading>Copyright information</heading>
7449 Every package must be accompanied by a verbatim copy of its
7450 copyright and distribution license in the file
7451 <tt>/usr/share/doc/<var>package</var>/copyright</tt>. This
7452 file must neither be compressed nor be a symbolic link.
7456 In addition, the copyright file must say where the upstream
7457 sources (if any) were obtained, and should explain briefly what
7458 modifications were made in the Debian version of the package
7459 compared to the upstream one. It should name the original
7460 authors of the package and the Debian maintainer(s) who were
7461 involved with its creation.</p>
7464 A copy of the file which will be installed in
7465 <tt>/usr/share/doc/<var>package</var>/copyright</tt> should
7466 be in <tt>debian/copyright</tt> in the source package.
7470 <tt>/usr/share/doc/<var>package</var></tt> may be a symbolic
7471 link to another directory in <tt>/usr/share/doc</tt> only if
7472 the two packages both come from the same source and the
7473 first package Depends on the second. These rules are
7474 important because copyrights must be extractable by
7479 Packages distributed under the UCB BSD license, the Artistic
7480 license, the GNU GPL, and the GNU LGPL should refer to the
7481 files <tt>/usr/share/common-licenses/BSD</tt>,
7482 <tt>/usr/share/common-licenses/Artistic</tt>,
7483 <tt>/usr/share/common-licenses/GPL</tt>, and
7484 <tt>/usr/share/common-licenses/LGPL</tt> respectively,
7485 rather than quoting them in the copyright file.
7489 You should not use the copyright file as a general <tt>README</tt>
7490 file. If your package has such a file it should be
7491 installed in <tt>/usr/share/doc/<var>package</var>/README</tt> or
7492 <tt>README.Debian</tt> or some other appropriate place.</p>
7496 <heading>Examples</heading>
7499 Any examples (configurations, source files, whatever),
7500 should be installed in a directory
7501 <tt>/usr/share/doc/<var>package</var>/examples</tt>. These
7502 files should not be referenced by any program: they're there
7503 for the benefit of the system administrator and users as
7504 documentation only. Architecture-specific example files
7505 should be installed in a directory
7506 <tt>/usr/lib/<var>package</var>/examples</tt> with symbolic
7508 <tt>/usr/share/doc/<var>package</var>/examples</tt>, or the
7509 latter directory itself may be a symbolic link to the
7514 <sect id="instchangelog">
7515 <heading>Changelog files</heading>
7518 Packages that are not Debian-native must contain a
7519 compressed copy of the <tt>debian/changelog</tt> file from
7520 the Debian source tree in
7521 <tt>/usr/share/doc/<var>package</var></tt> with the name
7522 <tt>changelog.Debian.gz</tt>. If an upstream changelog is
7523 available, it should be accessible as
7524 <tt>/usr/share/doc/<var>package</var>/changelog.gz</tt> in
7525 plain text. If the upstream changelog is distributed in
7526 HTML, it should be made available in that form as
7527 <tt>/usr/share/doc/<var>package</var>/changelog.html.gz</tt>
7528 and a plain text <tt>changelog.gz</tt> should be generated
7529 from it using, for example, <tt>lynx -dump -nolist</tt>. If
7530 the upstream changelog files do not already conform to this
7531 naming convention, then this may be achieved either by
7532 renaming the files, or by adding a symbolic link, at the
7533 maintainer's discretion.<footnote>
7535 Rationale: People should not have to look in places for
7536 upstream changelogs merely because they are given
7537 different names or are distributed in HTML format.
7543 All of these files should be installed compressed using
7544 <tt>gzip -9</tt>, as they will become large with time even
7545 if they start out small.
7549 If the package has only one changelog which is used both as
7550 the Debian changelog and the upstream one because there is
7551 no separate upstream maintainer then that changelog should
7552 usually be installed as
7553 <tt>/usr/share/doc/<var>package</var>/changelog.gz</tt>; if
7554 there is a separate upstream maintainer, but no upstream
7555 changelog, then the Debian changelog should still be called
7556 <tt>changelog.Debian.gz</tt>.</p>
7560 <appendix id="pkg-scope">
7561 <heading>Introduction and scope of these appendices</heading>
7564 These appendices are taken essentially verbatim from the
7565 now-deprecated Packaging Manual, version 3.2.1.0. They are
7566 the chapters which are likely to be of use to package
7567 maintainers and which have not already been included in the
7568 policy document itself. They have not yet been checked to
7569 ensure that they are compatible with the contents of policy,
7570 and if there are any contradictions, the version in the main
7571 policy document takes precedence. The remaining chapters of
7572 the old Packaging Manual have also not been read in detail to
7573 ensure that there are not parts which have been left out.
7574 Both of these will be done in due course.
7578 <prgn>dpkg</prgn> is a suite of programs for creating binary
7579 package files and installing and removing them on Unix
7582 <prgn>dpkg</prgn> is targetted primarily at Debian
7583 GNU/Linux, but may work on or be ported to other
7590 The binary packages are designed for the management of
7591 installed executable programs (usually compiled binaries) and
7592 their associated data, though source code examples and
7593 documentation are provided as part of some packages.</p>
7596 This manual describes the technical aspects of creating Debian
7597 binary packages (<tt>.deb</tt> files). It documents the
7598 behaviour of the package management programs
7599 <prgn>dpkg</prgn>, <prgn>dselect</prgn> et al. and the way
7600 they interact with packages.</p>
7603 It also documents the interaction between
7604 <prgn>dselect</prgn>'s core and the access method scripts it
7605 uses to actually install the selected packages, and describes
7606 how to create a new access method.</p>
7609 This manual does not go into detail about the options and
7610 usage of the package building and installation tools. It
7611 should therefore be read in conjuction with those programs'
7616 The utility programs which are provided with <prgn>dpkg</prgn>
7617 for managing various system configuration and similar issues,
7618 such as <prgn>update-rc.d</prgn> and
7619 <prgn>install-info</prgn>, are not described in detail here -
7620 please see their manpages.
7624 It does <em>not</em> describe the policy requirements imposed
7625 on Debian packages, such as the permissions on files and
7626 directories, documentation requirements, upload procedure, and
7627 so on. You should see the Debian packaging policy manual for
7628 these details. (Many of them will probably turn out to be
7629 helpful even if you don't plan to upload your package and make
7630 it available as part of the distribution.)
7634 It is assumed that the reader is reasonably familiar with the
7635 <prgn>dpkg</prgn> System Administrators' manual.
7636 Unfortunately this manual does not yet exist.
7640 The Debian version of the FSF's GNU hello program is provided
7641 as an example for people wishing to create Debian
7642 packages. The Debian <prgn>debmake</prgn> package is
7643 recommended as a very helpful tool in creating and maintaining
7644 Debian packages. However, while the tools and examples are
7645 helpful, they do not replace the need to read and follow the
7646 Policy and Programmer's Manual.</p>
7649 <appendix id="pkg-binarypkg"><heading>Binary packages (from old
7654 The binary package has two main sections. The first part
7655 consists of various control information files and scripts used
7656 by <prgn>dpkg</prgn> when installing and removing. See <ref
7657 id="pkg-controlarea">.
7661 The second part is an archive containing the files and
7662 directories to be installed.
7666 In the future binary packages may also contain other
7667 components, such as checksums and digital signatures. The
7668 format for the archive is described in full in the
7669 <tt>deb(5)</tt> manpage.
7673 <sect id="pkg-bincreating"><heading>Creating package files -
7674 <prgn>dpkg-deb</prgn>
7678 All manipulation of binary package files is done by
7679 <prgn>dpkg-deb</prgn>; it's the only program that has
7680 knowledge of the format. (<prgn>dpkg-deb</prgn> may be
7681 invoked by calling <prgn>dpkg</prgn>, as <prgn>dpkg</prgn>
7682 will spot that the options requested are appropriate to
7683 <prgn>dpkg-deb</prgn> and invoke that instead with the same
7688 In order to create a binary package you must make a
7689 directory tree which contains all the files and directories
7690 you want to have in the filesystem data part of the package.
7691 In Debian-format source packages this directory is usually
7692 <tt>debian/tmp</tt>, relative to the top of the package's
7697 They should have the locations (relative to the root of the
7698 directory tree you're constructing) ownerships and
7699 permissions which you want them to have on the system when
7704 With current versions of <prgn>dpkg</prgn> the uid/username
7705 and gid/groupname mappings for the users and groups being
7706 used should be the same on the system where the package is
7707 built and the one where it is installed.
7711 You need to add one special directory to the root of the
7712 miniature filesystem tree you're creating:
7713 <prgn>DEBIAN</prgn>. It should contain the control
7714 information files, notably the binary package control file
7715 (see <ref id="pkg-controlfile">).
7719 The <prgn>DEBIAN</prgn> directory will not appear in the
7720 filesystem archive of the package, and so won't be installed
7721 by <prgn>dpkg</prgn> when the package is installed.
7725 When you've prepared the package, you should invoke:
7727 dpkg --build <var>directory</var>
7732 This will build the package in
7733 <tt><var>directory</var>.deb</tt>. (<prgn>dpkg</prgn> knows
7734 that <tt>--build</tt> is a <prgn>dpkg-deb</prgn> option, so
7735 it invokes <prgn>dpkg-deb</prgn> with the same arguments to
7740 See the manpage <manref name="dpkg-deb" section="8"> for details of how
7741 to examine the contents of this newly-created file. You may find the
7742 output of following commands enlightening:
7744 dpkg-deb --info <var>filename</var>.deb
7745 dpkg-deb --contents <var>filename</var>.deb
7746 dpkg --contents <var>filename</var>.deb
7748 To view the copyright file for a package you could use this command:
7750 dpkg --fsys-tarfile <var>filename</var>.deb | tar xof usr/doc/<var>\*</var>copyright | less
7755 <sect id="pkg-controlarea">
7757 Package control information files
7761 The control information portion of a binary package is a
7762 collection of files with names known to <prgn>dpkg</prgn>.
7763 It will treat the contents of these files specially - some
7764 of them contain information used by <prgn>dpkg</prgn> when
7765 installing or removing the package; others are scripts which
7766 the package maintainer wants <prgn>dpkg</prgn> to run.
7770 It is possible to put other files in the package control
7771 area, but this is not generally a good idea (though they
7772 will largely be ignored).
7776 Here is a brief list of the control info files supported by
7777 <prgn>dpkg</prgn> and a summary of what they're used for.
7782 <tag><tt>control</tt>
7786 This is the key description file used by
7787 <prgn>dpkg</prgn>. It specifies the package's name
7788 and version, gives its description for the user,
7789 states its relationships with other packages, and so
7790 forth. See <ref id="pkg-controlfile">.
7794 It is usually generated automatically from information
7795 in the source package by the
7796 <prgn>dpkg-gencontrol</prgn> program, and with
7797 assistance from <prgn>dpkg-shlibdeps</prgn>. See <ref
7798 id="pkg-sourcetools">.</p>
7801 <tag><tt>postinst</tt>, <tt>preinst</tt>, <tt>postrm</tt>,
7807 These are exectuable files (usually scripts) which
7808 <prgn>dpkg</prgn> runs during installation, upgrade
7809 and removal of packages. They allow the package to
7810 deal with matters which are particular to that package
7811 or require more complicated processing than that
7812 provided by <prgn>dpkg</prgn>. Details of when and
7813 how they are called are in <ref
7814 id="maintainerscripts">.
7818 It is very important to make these scripts
7822 That means that if it runs successfully or fails
7823 and then you call it again it doesn't bomb out,
7824 but just ensures that everything is the way it
7827 </footnote> This is so that if an error occurs, the
7828 user interrupts <prgn>dpkg</prgn> or some other
7829 unforeseen circumstance happens you don't leave the
7830 user with a badly-broken package.
7834 The maintainer scripts are guaranteed to run with a
7835 controlling terminal and can interact with the user.
7836 If they need to prompt for passwords, do full-screen
7837 interaction or something similar you should do these
7838 things to and from <tt>/dev/tty</tt>, since
7839 <prgn>dpkg</prgn> will at some point redirect scripts'
7840 standard input and output so that it can log the
7841 installation process. Likewise, because these scripts
7842 may be executed with standard output redirected into a
7843 pipe for logging purposes, Perl scripts should set
7844 unbuffered output by setting <tt>$|=1</tt> so that the
7845 output is printed immediately rather than being
7850 Each script should return a zero exit status for
7851 success, or a nonzero one for failure.</p>
7854 <tag><tt>conffiles</tt>
7859 This file contains a list of configuration files which
7860 are to be handled automatically by <prgn>dpkg</prgn>
7861 (see <ref id="pkg-conffiles">). Note that not necessarily
7862 every configuration file should be listed here.</p>
7865 <tag><tt>shlibs</tt>
7870 This file contains a list of the shared libraries
7871 supplied by the package, with dependency details for
7872 each. This is used by <prgn>dpkg-shlibdeps</prgn>
7873 when it determines what dependencies are required in a
7874 package control file. The <tt>shlibs</tt> file format
7875 is described on <ref id="shlibs">.
7881 <sect id="pkg-controlfile">
7883 The main control information file: <tt>control</tt>
7886 The most important control information file used by
7887 <prgn>dpkg</prgn> when it installs a package is
7888 <tt>control</tt>. It contains all the package's `vital
7893 The binary package control files of packages built from
7894 Debian sources are made by a special tool,
7895 <prgn>dpkg-gencontrol</prgn>, which reads
7896 <tt>debian/control</tt> and <tt>debian/changelog</tt> to
7897 find the information it needs. See <ref id="pkg-sourcepkg"> for
7902 The fields in binary package control files are:
7903 <list compact="compact">
7905 <p><qref id="pkg-f-Package"><tt>Package</tt></qref> (mandatory)</p>
7908 <p><qref id="versions"><tt>Version</tt></qref> (mandatory)</p>
7910 <item><p><qref id="pkg-f-Architecture"><tt>Architecture</tt></qref>
7914 This field should appear in all packages, though
7915 <prgn>dpkg</prgn> doesn't require it yet so that
7916 old packages can still be installed.
7922 <p><qref id="relationships"><tt>Depends</tt>,
7923 <tt>Provides</tt> et al.</qref></p>
7926 <p><qref id="pkg-f-Essential"><tt>Essential</tt></qref></p>
7929 <p><qref id="pkg-f-Maintainer"><tt>Maintainer</tt></qref></p>
7932 <p><qref id="pkg-f-classification"><tt>Section</tt>,
7933 <tt>Priority</tt></qref></p>
7936 <p><qref id="pkg-f-Source"><tt>Source</tt></qref></p>
7939 <p><qref id="descriptions"><tt>Description</tt></qref></p>
7943 <qref id="pkg-f-Installed-Size"><tt>Installed-Size</tt></qref>
7949 A description of the syntax of control files and the purpose
7950 of these fields is available in <ref id="pkg-controlfields">.
7955 <heading>Time Stamps</heading>
7957 Maintainers are encouraged to preserve the modification
7958 times of the upstream source files in a package, as far as
7959 is reasonably possible.
7962 The rationale is that there is some information conveyed
7963 by knowing the age of the file, for example, you could
7964 recognize that some documentation is very old by looking
7965 at the modification time, so it would be nice if the
7966 modification time of the upstream source would be
7974 <appendix id="pkg-sourcepkg">
7975 <heading>Source packages (from old Packaging Manual) </heading>
7978 The Debian binary packages in the distribution are generated
7979 from Debian sources, which are in a special format to assist
7980 the easy and automatic building of binaries.
7984 There was a previous version of the Debian source format,
7985 which is now being phased out. Instructions for converting an
7986 old-style package are given in the Debian policy manual.
7989 <sect id="pkg-sourcetools">
7990 <heading>Tools for processing source packages</heading>
7993 Various tools are provided for manipulating source packages;
7994 they pack and unpack sources and help build of binary
7995 packages and help manage the distribution of new versions.
7999 They are introduced and typical uses described here; see
8000 <manref name="dpkg-source" section="1"> for full
8001 documentation about their arguments and operation.
8005 For examples of how to construct a Debian source package,
8006 and how to use those utilities that are used by Debian
8007 source packages, please see the <prgn>hello</prgn> example
8013 <prgn>dpkg-source</prgn> - packs and unpacks Debian source
8018 This program is frequently used by hand, and is also
8019 called from package-independent automated building scripts
8020 such as <prgn>dpkg-buildpackage</prgn>.
8024 To unpack a package it is typically invoked with
8026 dpkg-source -x <var>.../path/to/filename</var>.dsc
8031 with the <tt><var>filename</var>.tar.gz</tt> and
8032 <tt><var>filename</var>.diff.gz</tt> (if applicable) in
8033 the same directory. It unpacks into
8034 <tt><var>package</var>-<var>version</var></tt>, and if
8036 <tt><var>package</var>-<var>version</var>.orig</tt>, in
8037 the current directory.
8041 To create a packed source archive it is typically invoked:
8043 dpkg-source -b <var>package</var>-<var>version</var>
8048 This will create the <tt>.dsc</tt>, <tt>.tar.gz</tt> and
8049 <tt>.diff.gz</tt> (if appropriate) in the current
8050 directory. <prgn>dpkg-source</prgn> does not clean the
8051 source tree first - this must be done separately if it is
8056 See also <ref id="pkg-sourcearchives">.</p>
8062 <prgn>dpkg-buildpackage</prgn> - overall package-building
8067 <prgn>dpkg-buildpackage</prgn> is a script which invokes
8068 <prgn>dpkg-source</prgn>, the <tt>debian/rules</tt>
8069 targets <prgn>clean</prgn>, <prgn>build</prgn> and
8070 <prgn>binary</prgn>, <prgn>dpkg-genchanges</prgn> and
8071 <prgn>pgp</prgn> to build a signed source and binary
8076 It is usually invoked by hand from the top level of the
8077 built or unbuilt source directory. It may be invoked with
8078 no arguments; useful arguments include:
8079 <taglist compact="compact">
8080 <tag><tt>-uc</tt>, <tt>-us</tt></tag>
8083 Do not PGP-sign the <tt>.changes</tt> file or the
8084 source package <tt>.dsc</tt> file, respectively.</p>
8086 <tag><tt>-p<var>pgp-command</var></tt></tag>
8089 Invoke <var>pgp-command</var> instead of finding
8090 <tt>pgp</tt> on the <prgn>PATH</prgn>.
8091 <var>pgp-command</var> must behave just like
8092 <prgn>pgp</prgn>.</p>
8094 <tag><tt>-r<var>root-command</var></tt></tag>
8097 When root privilege is required, invoke the command
8098 <var>root-command</var>. <var>root-command</var>
8099 should invoke its first argument as a command, from
8100 the <prgn>PATH</prgn> if necessary, and pass its
8101 second and subsequent arguments to the command it
8102 calls. If no <var>root-command</var> is supplied
8103 then <var>dpkg-buildpackage</var> will take no
8104 special action to gain root privilege, so that for
8105 most packages it will have to be invoked as root to
8108 <tag><tt>-b</tt>, <tt>-B</tt></tag>
8111 Two types of binary-only build and upload - see
8112 <manref name="dpkg-source" section="1">.
8121 <prgn>dpkg-gencontrol</prgn> - generates binary package
8126 This program is usually called from <tt>debian/rules</tt>
8127 (see <ref id="pkg-sourcetree">) in the top level of the source
8132 This is usually done just before the files and directories in the
8133 temporary directory tree where the package is being built have their
8134 permissions and ownerships set and the package is constructed using
8135 <prgn>dpkg-deb/</prgn>
8138 This is so that the control file which is produced has
8139 the right permissions
8145 <prgn>dpkg-gencontrol</prgn> must be called after all the
8146 files which are to go into the package have been placed in
8147 the temporary build directory, so that its calculation of
8148 the installed size of a package is correct.
8152 It is also necessary for <prgn>dpkg-gencontrol</prgn> to
8153 be run after <prgn>dpkg-shlibdeps</prgn> so that the
8154 variable substitutions created by
8155 <prgn>dpkg-shlibdeps</prgn> in <tt>debian/substvars</tt>
8160 For a package which generates only one binary package, and
8161 which builds it in <tt>debian/tmp</tt> relative to the top
8162 of the source package, it is usually sufficient to call
8163 <prgn>dpkg-gencontrol</prgn>.
8167 Sources which build several binaries will typically need
8170 dpkg-gencontrol -Pdebian/tmp-<var>pkg</var> -p<var>package</var>
8171 </example> The <tt>-P</tt> tells
8172 <prgn>dpkg-gencontrol</prgn> that the package is being
8173 built in a non-default directory, and the <tt>-p</tt>
8174 tells it which package's control file should be generated.
8178 <prgn>dpkg-gencontrol</prgn> also adds information to the
8179 list of files in <tt>debian/files</tt>, for the benefit of
8180 (for example) a future invocation of
8181 <prgn>dpkg-genchanges</prgn>.</p>
8186 <prgn>dpkg-shlibdeps</prgn> - calculates shared library
8191 This program is usually called from <tt>debian/rules</tt>
8192 just before <prgn>dpkg-gencontrol</prgn> (see <ref
8193 id="pkg-sourcetree">), in the top level of the source tree.
8197 Its arguments are executables.
8200 In a forthcoming dpkg version,
8201 <prgn>dpkg-shlibdeps</prgn> would be required to be
8202 called on shared libraries as well.
8205 They may be specified either in the locations in the
8206 source tree where they are created or in the locations
8207 in the temporary build tree where they are installed
8208 prior to binary package creation.
8210 </footnote> for which shared library dependencies should
8211 be included in the binary package's control file.
8215 If some of the found shared libraries should only
8216 warrant a <tt>Recommends</tt> or <tt>Suggests</tt>, or if
8217 some warrant a <tt>Pre-Depends</tt>, this can be achieved
8218 by using the <tt>-d<var>dependency-field</var></tt> option
8219 before those executable(s). (Each <tt>-d</tt> option
8220 takes effect until the next <tt>-d</tt>.)
8224 <prgn>dpkg-shlibdeps</prgn> does not directly cause the
8225 output control file to be modified. Instead by default it
8226 adds to the <tt>debian/substvars</tt> file variable
8227 settings like <tt>shlibs:Depends</tt>. These variable
8228 settings must be referenced in dependency fields in the
8229 appropriate per-binary-package sections of the source
8234 For example, the <prgn>procps</prgn> package generates two
8235 kinds of binaries, simple C binaries like <prgn>ps</prgn>
8236 which require a predependency and full-screen ncurses
8237 binaries like <prgn>top</prgn> which require only a
8238 recommendation. It can say in its <tt>debian/rules</tt>:
8240 dpkg-shlibdeps -dPre-Depends ps -dRecommends top
8242 and then in its main control file <tt>debian/control</tt>:
8246 Pre-Depends: ${shlibs:Pre-Depends}
8247 Recommends: ${shlibs:Recommends}
8253 Sources which produce several binary packages with
8254 different shared library dependency requirements can use
8255 the <tt>-p<var>varnameprefix</var></tt> option to override
8256 the default <tt>shlib:</tt> prefix (one invocation of
8257 <prgn>dpkg-shlibdeps</prgn> per setting of this option).
8258 They can thus produce several sets of dependency
8259 variables, each of the form
8260 <tt><var>varnameprefix</var>:<var>dependencyfield</var></tt>,
8261 which can be referred to in the appropriate parts of the
8262 binary package control files.
8269 <prgn>dpkg-distaddfile</prgn> - adds a file to
8270 <tt>debian/files</tt>
8274 Some packages' uploads need to include files other than
8275 the source and binary package files.
8279 <prgn>dpkg-distaddfile</prgn> adds a file to the
8280 <tt>debian/files</tt> file so that it will be included in
8281 the <tt>.changes</tt> file when
8282 <prgn>dpkg-genchanges</prgn> is run.
8286 It is usually invoked from the <prgn>binary</prgn> target of
8287 <tt>debian/rules</tt>:
8289 dpkg-distaddfile <var>filename</var> <var>section</var> <var>priority</var>
8291 The <var>filename</var> is relative to the directory where
8292 <prgn>dpkg-genchanges</prgn> will expect to find it - this
8293 is usually the directory above the top level of the source
8294 tree. The <tt>debian/rules</tt> target should put the
8295 file there just before or just after calling
8296 <prgn>dpkg-distaddfile</prgn>.
8300 The <var>section</var> and <var>priority</var> are passed
8301 unchanged into the resulting <tt>.changes</tt> file. See
8302 <ref id="pkg-f-classification">.
8307 <sect1><heading><prgn>dpkg-genchanges</prgn> - generates a <tt>.changes</tt> upload
8312 This program is usually called by package-independent
8313 automatic building scripts such as
8314 <prgn>dpkg-buildpackage</prgn>, but it may also be called
8319 It is usually called in the top level of a built source
8320 tree, and when invoked with no arguments will print out a
8321 straightforward <tt>.changes</tt> file based on the
8322 information in the source package's changelog and control
8323 file and the binary and source packages which should have
8329 <sect1><heading><prgn>dpkg-parsechangelog</prgn> - produces parsed representation of
8334 This program is used internally by
8335 <prgn>dpkg-source</prgn> et al. It may also occasionally
8336 be useful in <tt>debian/rules</tt> and elsewhere. It
8337 parses a changelog, <tt>debian/changelog</tt> by default,
8338 and prints a control-file format representation of the
8339 information in it to standard output.
8343 <sect1 id="pkg-dpkgarch"><heading><prgn>dpkg-architecture</prgn> -
8344 information about the build and host system
8348 This program can be used manually, but is also invoked by
8349 <tt>dpkg-buildpackage</tt> or <tt>debian/rules</tt> to set
8350 to set environment or make variables which specify the build and
8351 host architecture for the package building process.
8356 <sect id="pkg-sourcetree"><heading>The Debianised source tree
8360 The source archive scheme described later is intended to
8361 allow a Debianised source tree with some associated control
8362 information to be reproduced and transported easily. The
8363 Debianised source tree is a version of the original program
8364 with certain files added for the benefit of the
8365 Debianisation process, and with any other changes required
8366 made to the rest of the source code and installation
8371 The extra files created for Debian are in the subdirectory
8372 <tt>debian</tt> of the top level of the Debianised source
8373 tree. They are described below.
8376 <sect1 id="pkg-debianrules"><heading><tt>debian/rules</tt> - the main building
8381 This file is an executable makefile, and contains the
8382 package-specific recipies for compiling the package and
8383 building binary package(s) out of the source.
8387 It must start with the line <tt>#!/usr/bin/make -f</tt>,
8388 so that it can be invoked by saying its name rather than
8389 invoking <prgn>make</prgn> explicitly.
8393 Since an interactive <tt>debian/rules</tt> script makes it
8394 impossible to autocompile that package and also makes it
8395 hard for other people to reproduce the same binary
8396 package, all <strong>required targets</strong> have to be
8397 non-interactive. At a minimul, required targets are the
8398 ones called by <prgn>dpkg-buildpackage</prgn>, namely,
8399 <em>clean</em>, <em>binary</em>, <em>binary-arch</em>, and
8400 <em>build</em>. It also follows that any target that these
8401 targets depend on must also be non-interactive.
8405 The targets which are required to be present are:
8407 <tag><tt>build</tt></tag>
8410 This should perform all non-interactive
8411 configuration and compilation of the package. If a
8412 package has an interactive pre-build configuration
8413 routine, the Debianised source package should be
8414 built after this has taken place, so that it can be
8415 built without rerunning the configuration.
8419 For some packages, notably ones where the same
8420 source tree is compiled in different ways to produce
8421 two binary packages, the <prgn>build</prgn> target
8422 does not make much sense. For these packages it is
8423 good enough to provide two (or more) targets
8424 (<tt>build-a</tt> and <tt>build-b</tt> or whatever)
8425 for each of the ways of building the package, and a
8426 <prgn>build</prgn> target that does nothing. The
8427 <prgn>binary</prgn> target will have to build the
8428 package in each of the possible ways and make the
8429 binary package out of each.
8433 The <prgn>build</prgn> target must not do anything
8434 that might require root privilege.
8438 The <prgn>build</prgn> target may need to run
8439 <prgn>clean</prgn> first - see below.
8443 When a package has a configuration routine that
8444 takes a long time, or when the makefiles are poorly
8445 designed, or when <prgn>build</prgn> needs to run
8446 <prgn>clean</prgn> first, it is a good idea to
8447 <tt>touch build</tt> when the build process is
8448 complete. This will ensure that if <tt>debian/rules
8449 build</tt> is run again it will not rebuild the
8454 <tag><tt>binary</tt>, <tt>binary-arch</tt>,
8455 <tt>binary-indep</tt>
8459 The <prgn>binary</prgn> target should be all that is
8460 necessary for the user to build the binary
8461 package. All these targets are required to be
8462 non-interactive. It is split into two parts:
8463 <prgn>binary-arch</prgn> builds the packages' output
8464 files which are specific to a particular
8465 architecture, and <prgn>binary-indep</prgn> builds
8466 those which are not.
8470 <prgn>binary</prgn> should usually be a target with
8471 no commands which simply depends on
8472 <prgn>binary-arch</prgn> and
8473 <prgn>binary-indep</prgn>.
8477 Both <prgn>binary-*</prgn> targets should depend on
8478 the <prgn>build</prgn> target, above, so that the
8479 package is built if it has not been already. It
8480 should then create the relevant binary package(s),
8481 using <prgn>dpkg-gencontrol</prgn> to make their
8482 control files and <prgn>dpkg-deb</prgn> to build
8483 them and place them in the parent of the top level
8488 If one of the <prgn>binary-*</prgn> targets has
8489 nothing to do (this will be always be the case if
8490 the source generates only a single binary package,
8491 whether architecture-dependent or not) it
8492 <em>must</em> still exist, but should always
8497 <ref id="pkg-binarypkg"> describes how to construct
8502 The <prgn>binary</prgn> targets must be invoked as
8507 <tag><tt>clean</tt></tag>
8511 This should undo any effects that the
8512 <prgn>build</prgn> and <prgn>binary</prgn> targets
8513 may have had, except that it should leave alone any
8514 output files created in the parent directory by a
8515 run of <prgn>binary</prgn>. This target is required
8516 to be non-interactive.
8520 If a <prgn>build</prgn> file is touched at the end
8521 of the <prgn>build</prgn> target, as suggested
8522 above, it must be removed as the first thing that
8523 <prgn>clean</prgn> does, so that running
8524 <prgn>build</prgn> again after an interrupted
8525 <prgn>clean</prgn> doesn't think that everything is
8530 The <prgn>clean</prgn> target must be invoked as
8531 root if <prgn>binary</prgn> has been invoked since
8532 the last <prgn>clean</prgn>, or if
8533 <prgn>build</prgn> has been invoked as root (since
8534 <prgn>build</prgn> may create directories, for
8539 <tag><tt>get-orig-source</tt> (optional)</tag>
8543 This target fetches the most recent version of the
8544 original source package from a canonical archive
8545 site (via FTP or WWW, for example), does any
8546 necessary rearrangement to turn it into the original
8547 source tarfile format described below, and leaves it
8548 in the current directory.
8552 This target may be invoked in any directory, and
8553 should take care to clean up any temporary files it
8558 This target is optional, but providing it if
8559 possible is a good idea.
8565 The <prgn>build</prgn>, <prgn>binary</prgn> and
8566 <prgn>clean</prgn> targets must be invoked with a current
8567 directory of the package's top-level directory.
8572 Additional targets may exist in <tt>debian/rules</tt>,
8573 either as published or undocumented interfaces or for the
8574 package's internal use.
8578 The architecture we build on and build for is determined by make
8579 variables via dpkg-architecture (see <ref id="pkg-dpkgarch">). You can
8580 get the Debian architecture and the GNU style architecture
8581 specification string for the build machine as well as the host
8582 machine. Here is a list of supported make variables:
8583 <list compact="compact">
8585 <p><tt>DEB_*_ARCH</tt> (the Debian architecture)</p>
8588 <p><tt>DEB_*_GNU_TYPE</tt> (the GNU style architecture
8589 specification string)</p>
8592 <p><tt>DEB_*_GNU_CPU</tt> (the CPU part of DEB_*_GNU_TYPE)</p>
8595 <p><tt>DEB_*_GNU_SYSTEM</tt> (the System part of
8601 where <tt>*</tt> is either <tt>BUILD</tt> for specification of
8602 the build machine or <tt>HOST</tt> for specification of the machine
8607 Backward compatibility can be provided in the rules file
8608 by setting the needed variables to suitable default
8609 values, please refer to the documentation of
8610 dpkg-architecture for details.
8614 It is important to understand that the <tt>DEB_*_ARCH</tt>
8615 string does only determine which Debian architecture we
8616 build on resp. for. It should not be used to get the CPU
8617 or System information, the GNU style variables should be
8623 <sect1><heading><tt>debian/control</tt>
8627 This file contains version-independent details about the
8628 source package and about the binary packages it creates.
8632 It is a series of sets of control fields, each
8633 syntactically similar to a binary package control file.
8634 The sets are separated by one or more blank lines. The
8635 first set is information about the source package in
8636 general; each subsequent set describes one binary package
8637 that the source tree builds.
8641 The syntax and semantics of the fields are described below
8642 in <ref id="pkg-controlfields">.
8646 The general (binary-package-independent) fields are:
8647 <list compact="compact">
8649 <p><qref id="pkg-f-Source"><tt>Source</tt></qref> (mandatory)</p>
8652 <p><qref id="pkg-f-Maintainer"><tt>Maintainer</tt></qref></p>
8656 <qref id="pkg-f-classification"><tt>Section</tt> and
8657 <tt>Priority</tt></qref>
8658 (classification, mandatory)
8663 <qref id="relationships"><tt>Build-Depends</tt> et
8664 al.</qref> (source package interrelationships)
8669 <qref id="pkg-f-Standards-Version"><tt>Standards-Version</tt></qref>
8675 The per-binary-package fields are:
8676 <list compact="compact">
8678 <p><qref id="pkg-f-Package"><tt>Package</tt></qref> (mandatory)</p>
8682 <qref id="pkg-f-Architecture"><tt>Architecture</tt></qref>
8686 <p><qref id="descriptions"><tt>Description</tt></qref></p>
8690 <qref id="pkg-f-classification"><tt>Section</tt> and
8691 <tt>Priority</tt></qref> (classification)</p>
8694 <p><qref id="pkg-f-Essential"><tt>Essential</tt></qref></p>
8698 <qref id="relationships"><tt>Depends</tt> et
8699 al.</qref> (binary package interrelationships)
8705 These fields are used by <prgn>dpkg-gencontrol</prgn> to
8706 generate control files for binary packages (see below), by
8707 <prgn>dpkg-genchanges</prgn> to generate the
8708 <tt>.changes</tt> file to accompany the upload, and by
8709 <prgn>dpkg-source</prgn> when it creates the <tt>.dsc</tt>
8710 source control file as part of a source archive.
8714 The fields here may contain variable references - their
8715 values will be substituted by
8716 <prgn>dpkg-gencontrol</prgn>, <prgn>dpkg-genchanges</prgn>
8717 or <prgn>dpkg-source</prgn> when they generate output
8718 control files. See <ref id="pkg-srcsubstvars"> for details.
8721 <p> <sect2><heading>User-defined fields
8725 Additional user-defined fields may be added to the
8726 source package control file. Such fields will be
8727 ignored, and not copied to (for example) binary or
8728 source package control files or upload control files.
8732 If you wish to add additional unsupported fields to
8733 these output files you should use the mechanism
8738 Fields in the main source control information file with
8739 names starting <tt>X</tt>, followed by one or more of
8740 the letters <tt>BCS</tt> and a hyphen <tt>-</tt>, will
8741 be copied to the output files. Only the part of the
8742 field name after the hyphen will be used in the output
8743 file. Where the letter <tt>B</tt> is used the field
8744 will appear in binary package control files, where the
8745 letter <tt>S</tt> is used in source package control
8746 files and where <tt>C</tt> is used in upload control
8747 (<tt>.changes</tt>) files.
8751 For example, if the main source information control file
8754 XBS-Comment: I stand between the candle and the star.
8756 then the binary and source package control files will contain the
8759 Comment: I stand between the candle and the star.
8766 <sect1 id="pkg-dpkgchangelog"><heading><tt>debian/changelog</tt>
8770 This file records the changes to the Debian-specific parts of the
8774 Though there is nothing stopping an author who is also
8775 the Debian maintainer from using it for all their
8776 changes, it will have to be renamed if the Debian and
8777 upstream maintainers become different
8784 It has a special format which allows the package building
8785 tools to discover which version of the package is being
8786 built and find out other release-specific information.
8790 That format is a series of entries like this:
8792 <var>package</var> (<var>version</var>) <var>distribution(s)</var>; urgency=<var>urgency</var>
8794 * <var>change details</var>
8795 <var>more change details</var>
8796 * <var>even more change details</var>
8798 -- <var>maintainer name and email address</var> <var>date</var>
8803 <var>package</var> and <var>version</var> are the source
8804 package name and version number.
8808 <var>distribution(s)</var> lists the distributions where
8809 this version should be installed when it is uploaded - it
8810 is copied to the <tt>Distribution</tt> field in the
8811 <tt>.changes</tt> file. See <ref id="pkg-f-Distribution">.
8815 <var>urgency</var> is the value for the <tt>Urgency</tt>
8816 field in the <tt>.changes</tt> file for the upload. See
8817 <ref id="pkg-f-Urgency">. It is not possible to specify an
8818 urgency containing commas; commas are used to separate
8819 <tt><var>keyword</var>=<var>value</var></tt> settings in
8820 the <prgn>dpkg</prgn> changelog format (though there is
8821 currently only one useful <var>keyword</var>,
8826 The change details may in fact be any series of lines
8827 starting with at least two spaces, but conventionally each
8828 change starts with an asterisk and a separating space and
8829 continuation lines are indented so as to bring them in
8830 line with the start of the text above. Blank lines may be
8831 used here to separate groups of changes, if desired.
8835 The maintainer name and email address should <em>not</em>
8836 necessarily be those of the usual package maintainer.
8837 They should be the details of the person doing
8838 <em>this</em> version. The information here will be
8839 copied to the <tt>.changes</tt> file, and then later used
8840 to send an acknowledgement when the upload has been
8845 The <var>date</var> should be in RFC822 format
8848 This is generated by the <prgn>822-date</prgn>
8851 </footnote>; it should include the timezone specified
8852 numerically, with the timezone name or abbreviation
8853 optionally present as a comment.
8857 The first `title' line with the package name should start
8858 at the left hand margin; the `trailer' line with the
8859 maintainer and date details should be preceded by exactly
8860 one space. The maintainer details and the date must be
8861 separated by exactly two spaces.
8865 An Emacs mode for editing this format is available: it is
8866 called <tt>debian-changelog-mode</tt>. You can have this
8867 mode selected automatically when you edit a Debian
8868 changelog by adding a local variables clause to the end of
8872 <sect2><heading>Defining alternative changelog formats
8876 It is possible to use a different format to the standard
8877 one, by providing a parser for the format you wish to
8882 In order to have <tt>dpkg-parsechangelog</tt> run your
8883 parser, you must include a line within the last 40 lines
8884 of your file matching the Perl regular expression:
8885 <tt>\schangelog-format:\s+([0-9a-z]+)\W</tt> The part in
8886 parentheses should be the name of the format. For
8887 example, you might say:
8889 @@@ changelog-format: joebloggs @@@
8891 Changelog format names are non-empty strings of alphanumerics.
8895 If such a line exists then <tt>dpkg-parsechangelog</tt>
8896 will look for the parser as
8897 <tt>/usr/lib/dpkg/parsechangelog/<var>format-name</var></tt>
8899 <tt>/usr/local/lib/dpkg/parsechangelog/<var>format-name</var></tt>;
8900 it is an error for it not to find it, or for it not to
8901 be an executable program. The default changelog format
8902 is <tt>dpkg</tt>, and a parser for it is provided with
8903 the <tt>dpkg</tt> package.
8907 The parser will be invoked with the changelog open on
8908 standard input at the start of the file. It should read
8909 the file (it may seek if it wishes) to determine the
8910 information required and return the parsed information
8911 to standard output in the form of a series of control
8912 fields in the standard format. By default it should
8913 return information about only the most recent version in
8914 the changelog; it should accept a
8915 <tt>-v<var>version</var></tt> option to return changes
8916 information from all versions present <em>strictly
8917 after</em> <var>version</var>, and it should then be an
8918 error for <var>version</var> not to be present in the
8924 <list compact="compact">
8926 <p><qref id="pkg-f-Source"><tt>Source</tt></qref></p>
8929 <p><qref id="versions"><tt>Version</tt></qref> (mandatory)</p>
8933 <qref id="pkg-f-Distribution"><tt>Distribution</tt></qref>
8938 <p><qref id="pkg-f-Urgency"><tt>Urgency</tt></qref> (mandatory)</p>
8942 <qref id="pkg-f-Maintainer"><tt>Maintainer</tt></qref>
8947 <p><qref id="pkg-f-Date"><tt>Date</tt></qref></p>
8951 <qref id="pkg-f-Changes"><tt>Changes</tt></qref>
8958 If several versions are being returned (due to the use
8959 of <tt>-v</tt>), the urgency value should be of the
8960 highest urgency code listed at the start of any of the
8961 versions requested followed by the concatenated
8962 (space-separated) comments from all the versions
8963 requested; the maintainer, version, distribution and
8964 date should always be from the most recent version.
8968 For the format of the <tt>Changes</tt> field see <ref
8969 id="pkg-f-Changes">.
8973 If the changelog format which is being parsed always or
8974 almost always leaves a blank line between individual
8975 change notes these blank lines should be stripped out,
8976 so as to make the resulting output compact.
8980 If the changelog format does not contain date or package
8981 name information this information should be omitted from
8982 the output. The parser should not attempt to synthesise
8983 it or find it from other sources.
8987 If the changelog does not have the expected format the
8988 parser should exit with a nonzero exit status, rather
8989 than trying to muddle through and possibly generating
8994 A changelog parser may not interact with the user at
8998 <sect1 id="pkg-srcsubstvars"><heading><tt>debian/substvars</tt>
8999 and variable substitutions
9003 When <prgn>dpkg-gencontrol</prgn>,
9004 <prgn>dpkg-genchanges</prgn> and <prgn>dpkg-source</prgn>
9005 generate control files they do variable substitutions on
9006 their output just before writing it. Variable
9007 substitutions have the form
9008 <tt>${<var>variable-name</var>}</tt>. The optional file
9009 <tt>debian/substvars</tt> contains variable substitutions
9010 to be used; variables can also be set directly from
9011 <tt>debian/rules</tt> using the <tt>-V</tt> option to the
9012 source packaging commands, and certain predefined
9013 variables are available.
9017 The is usually generated and modified dynamically by
9018 <tt>debian/rules</tt> targets; in this case it must be
9019 removed by the <prgn>clean</prgn> target.
9023 See <manref name="dpkg-source" section="1"> for full
9024 details about source variable substitutions, including the
9025 format of <tt>debian/substvars</tt>.</p>
9028 <sect1><heading><tt>debian/files</tt>
9032 This file is not a permanent part of the source tree; it
9033 is used while building packages to record which files are
9034 being generated. <prgn>dpkg-genchanges</prgn> uses it
9035 when it generates a <tt>.changes</tt> file.
9039 It should not exist in a shipped source package, and so it
9040 (and any backup files or temporary files such as
9044 <tt>files.new</tt> is used as a temporary file by
9045 <prgn>dpkg-gencontrol</prgn> and
9046 <prgn>dpkg-distaddfile</prgn> - they write a new
9047 version of <tt>files</tt> here before renaming it,
9048 to avoid leaving a corrupted copy if an error
9051 </footnote>) should be removed by the
9052 <prgn>clean</prgn> target. It may also be wise to
9053 ensure a fresh start by emptying or removing it at the
9054 start of the <prgn>binary</prgn> target.
9058 <prgn>dpkg-gencontrol</prgn> adds an entry to this file
9059 for the <tt>.deb</tt> file that will be created by
9060 <prgn>dpkg-deb</prgn> from the control file that it
9061 generates, so for most packages all that needs to be done
9062 with this file is to delete it in <prgn>clean</prgn>.
9066 If a package upload includes files besides the source
9067 package and any binary packages whose control files were
9068 made with <prgn>dpkg-gencontrol</prgn> then they should be
9069 placed in the parent of the package's top-level directory
9070 and <prgn>dpkg-distaddfile</prgn> should be called to add
9071 the file to the list in <tt>debian/files</tt>.</p>
9074 <sect1><heading><tt>debian/tmp</tt>
9078 This is the canonical temporary location for the
9079 construction of binary packages by the <prgn>binary</prgn>
9080 target. The directory <tt>tmp</tt> serves as the root of
9081 the filesystem tree as it is being constructed (for
9082 example, by using the package's upstream makefiles install
9083 targets and redirecting the output there), and it also
9084 contains the <tt>DEBIAN</tt> subdirectory. See <ref
9085 id="pkg-bincreating">.
9089 If several binary packages are generated from the same
9090 source tree it is usual to use several
9091 <tt>debian/tmp<var>something</var></tt> directories, for
9092 example <tt>tmp-a</tt> or <tt>tmp-doc</tt>.
9096 Whatever <tt>tmp</tt> directories are created and used by
9097 <prgn>binary</prgn> must of course be removed by the
9098 <prgn>clean</prgn> target.</p></sect1>
9102 <sect id="pkg-sourcearchives"><heading>Source packages as archives
9106 As it exists on the FTP site, a Debian source package
9107 consists of three related files. You must have the right
9108 versions of all three to be able to use them.
9113 <tag>Debian source control file - <tt>.dsc</tt></tag>
9117 This file contains a series of fields, identified and
9118 separated just like the fields in the control file of
9119 a binary package. The fields are listed below; their
9120 syntax is described above, in <ref id="pkg-controlfields">.
9121 <list compact="compact">
9123 <p><qref id="pkg-f-Source"><tt>Source</tt></qref></p>
9126 <p><qref id="versions"><tt>Version</tt></qref></p>
9129 <p><qref id="pkg-f-Maintainer"><tt>Maintainer</tt></qref></p>
9132 <p><qref id="pkg-f-Binary"><tt>Binary</tt></qref></p>
9135 <p><qref id="pkg-f-Architecture"><tt>Architecture</tt></qref></p>
9139 <qref id="relationships"><tt>Build-Depends</tt> et
9140 al.</qref> (source package interrelationships)
9145 <qref id="pkg-f-Standards-Version"><tt>Standards-Version</tt></qref></p>
9148 <p><qref id="pkg-f-Files"><tt>Files</tt></qref></p>
9153 The source package control file is generated by
9154 <prgn>dpkg-source</prgn> when it builds the source
9155 archive, from other files in the source package,
9156 described above. When unpacking it is checked against
9157 the files and directories in the other parts of the
9158 source package, as described below.</p>
9162 Original source archive -
9164 <var>package</var>_<var>upstream-version</var>.orig.tar.gz
9171 This is a compressed (with <tt>gzip -9</tt>)
9172 <prgn>tar</prgn> file containing the source code from
9173 the upstream authors of the program. The tarfile
9174 unpacks into a directory
9175 <tt><var>package</var>-<var>upstream-version</var>.orig</tt>,
9176 and does not contain files anywhere other than in
9177 there or in its subdirectories.</p>
9181 Debianisation diff -
9183 <var>package</var>_<var>upstream_version-revision</var>.diff.gz
9189 This is a unified context diff (<tt>diff -u</tt>)
9190 giving the changes which are required to turn the
9191 original source into the Debian source. These changes
9192 may only include editing and creating plain files.
9193 The permissions of files, the targets of symbolic
9194 links and the characteristics of special files or
9195 pipes may not be changed and no files may be removed
9200 All the directories in the diff must exist, except the
9201 <tt>debian</tt> subdirectory of the top of the source
9202 tree, which will be created by
9203 <prgn>dpkg-source</prgn> if necessary when unpacking.
9207 The <prgn>dpkg-source</prgn> program will
9208 automatically make the <tt>debian/rules</tt> file
9209 executable (see below).</p></item>
9214 If there is no original source code - for example, if the
9215 package is specially prepared for Debian or the Debian
9216 maintainer is the same as the upstream maintainer - the
9217 format is slightly different: then there is no diff, and the
9219 <tt><var>package</var>_<var>version</var>.tar.gz</tt> and
9220 contains a directory
9221 <tt><var>package</var>-<var>version</var></tt>.
9225 <sect><heading>Unpacking a Debian source package without
9226 <prgn>dpkg-source</prgn>
9230 <tt>dpkg-source -x</tt> is the recommended way to unpack a
9231 Debian source package. However, if it is not available it
9232 is possible to unpack a Debian source archive as follows:
9233 <enumlist compact="compact">
9236 Untar the tarfile, which will create a <tt>.orig</tt>
9240 <p>Rename the <tt>.orig</tt> directory to
9241 <tt><var>package</var>-<var>version</var></tt>.</p>
9245 Create the subdirectory <tt>debian</tt> at the top of
9246 the source tree.</p>
9248 <item><p>Apply the diff using <tt>patch -p0</tt>.</p>
9250 <item><p>Untar the tarfile again if you want a copy of the original
9251 source code alongside the Debianised version.</p>
9256 It is not possible to generate a valid Debian source archive
9257 without using <prgn>dpkg-source</prgn>. In particular,
9258 attempting to use <prgn>diff</prgn> directly to generate the
9259 <tt>.diff.gz</tt> file will not work.
9262 <sect1><heading>Restrictions on objects in source packages
9266 The source package may not contain any hard links
9269 This is not currently detected when building source
9270 packages, but only when extracting
9276 Hard links may be permitted at some point in the
9277 future, but would require a fair amount of
9280 </footnote>, device special files, sockets or setuid or
9284 Setgid directories are allowed.
9290 The source packaging tools manage the changes between the
9291 original and Debianised source using <prgn>diff</prgn> and
9292 <prgn>patch</prgn>. Turning the original source tree as
9293 included in the <tt>.orig.tar.gz</tt> into the debianised
9294 source must not involve any changes which cannot be
9295 handled by these tools. Problematic changes which cause
9296 <prgn>dpkg-source</prgn> to halt with an error when
9297 building the source package are:
9298 <list compact="compact">
9299 <item><p>Adding or removing symbolic links, sockets or pipes.</p>
9301 <item><p>Changing the targets of symbolic links.</p>
9303 <item><p>Creating directories, other than <tt>debian</tt>.</p>
9305 <item><p>Changes to the contents of binary files.</p></item>
9306 </list> Changes which cause <prgn>dpkg-source</prgn> to
9307 print a warning but continue anyway are:
9308 <list compact="compact">
9311 Removing files, directories or symlinks.
9314 Renaming a file is not treated specially - it is
9315 seen as the removal of the old file (which
9316 generates a warning, but is otherwise ignored),
9317 and the creation of the new
9324 Changed text files which are missing the usual final
9325 newline (either in the original or the modified
9330 Changes which are not represented, but which are not detected by
9331 <prgn>dpkg-source</prgn>, are:
9332 <list compact="compact">
9333 <item><p>Changing the permissions of files (other than
9334 <tt>debian/rules</tt>) and directories.</p></item>
9339 The <tt>debian</tt> directory and <tt>debian/rules</tt>
9340 are handled specially by <prgn>dpkg-source</prgn> - before
9341 applying the changes it will create the <tt>debian</tt>
9342 directory, and afterwards it will make
9343 <tt>debian/rules</tt> world-exectuable.
9349 <appendix id="pkg-controlfields"><heading>Control files and their
9350 fields (from old Packaging Manual)
9354 Many of the tools in the <prgn>dpkg</prgn> suite manipulate
9355 data in a common format, known as control files. Binary and
9356 source packages have control data as do the <tt>.changes</tt>
9357 files which control the installation of uploaded files, and
9358 <prgn>dpkg</prgn>'s internal databases are in a similar
9362 <sect><heading>Syntax of control files
9366 A file consists of one or more paragraphs of fields. The
9367 paragraphs are separated by blank lines. Some control files
9368 only allow one paragraph; others allow several, in which
9369 case each paragraph often refers to a different package.
9373 Each paragraph is a series of fields and values; each field
9374 consists of a name, followed by a colon and the value. It
9375 ends at the end of the line. Horizontal whitespace (spaces
9376 and tabs) may occur before or after the value and is ignored
9377 there; it is conventional to put a single space after the
9382 Some fields' values may span several lines; in this case
9383 each continuation line <em>must</em> start with a space or
9384 tab. Any trailing spaces or tabs at the end of individual
9385 lines of a field value are ignored.
9389 Except where otherwise stated only a single line of data is
9390 allowed and whitespace is not significant in a field body.
9391 Whitespace may never appear inside names (of packages,
9392 architectures, files or anything else), version numbers or
9393 in between the characters of multi-character version
9398 Field names are not case-sensitive, but it is usual to
9399 capitalise the field names using mixed case as shown below.
9403 Blank lines, or lines consisting only of spaces and tabs,
9404 are not allowed within field values or between fields - that
9405 would mean a new paragraph.
9409 It is important to note that there are several fields which
9410 are optional as far as <prgn>dpkg</prgn> and the related
9411 tools are concerned, but which must appear in every Debian
9412 package, or whose omission may cause problems. When writing
9413 the control files for Debian packages you <em>must</em> read
9414 the Debian policy manual in conjuction with the details
9415 below and the list of fields for the particular file.</p>
9418 <sect><heading>List of fields
9421 <sect1 id="pkg-f-Package"><heading><tt>Package</tt>
9425 The name of the binary package. Package names consist of
9426 the alphanumerics and <tt>+</tt> <tt>-</tt> <tt>.</tt>
9427 (plus, minus and full stop).
9430 The characters <tt>@</tt> <tt>:</tt> <tt>=</tt>
9431 <tt>%</tt> <tt>_</tt> (at, colon, equals, percent
9432 and underscore) used to be legal and are still
9433 accepted when found in a package file, but may not be
9434 used in new packages
9440 They must be at least two characters and must start with
9441 an alphanumeric. In current versions of dpkg they are
9442 sort of case-sensitive<footnote><p>This is a
9443 bug.</p></footnote>; use lowercase package names unless
9444 the package you're building (or referring to, in other
9445 fields) is already using uppercase.</p>
9448 <sect1 id="pkg-f-Version"><heading><tt>Version</tt>
9452 This lists the source or binary package's version number -
9453 see <ref id="versions">.
9458 <sect1 id="pkg-f-Architecture"><heading><tt>Architecture</tt>
9462 This is the architecture string; it is a single word for
9463 the Debian architecture.
9467 <prgn>dpkg</prgn> will check the declared architecture of
9468 a binary package against its own compiled-in value before
9473 The special value <tt>all</tt> indicates that the package
9474 is architecture-independent.
9478 In the main <tt>debian/control</tt> file in the source
9479 package, or in the source package control file
9480 <tt>.dsc</tt>, a list of architectures (separated by
9481 spaces) is also allowed, as is the special value
9482 <tt>any</tt>. A list indicates that the source will build
9483 an architecture-dependent package, and will only work
9484 correctly on the listed architectures. <tt>any</tt>
9485 indicates that though the source package isn't dependent
9486 on any particular architecture and should compile fine on
9487 any one, the binary package(s) produced are not
9488 architecture-independent but will instead be specific to
9489 whatever the current build architecture is.
9493 In a <tt>.changes</tt> file the <tt>Architecture</tt>
9494 field lists the architecture(s) of the package(s)
9495 currently being uploaded. This will be a list; if the
9496 source for the package is being uploaded too the special
9497 entry <tt>source</tt> is also present.
9501 See <ref id="pkg-debianrules"> for information how to get the
9502 architecture for the build process.
9506 <sect1 id="pkg-f-Maintainer"><heading><tt>Maintainer</tt>
9510 The package maintainer's name and email address. The name
9511 should come first, then the email address inside angle
9512 brackets <tt><></tt> (in RFC822 format).
9516 If the maintainer's name contains a full stop then the
9517 whole field will not work directly as an email address due
9518 to a misfeature in the syntax specified in RFC822; a
9519 program using this field as an address must check for this
9520 and correct the problem if necessary (for example by
9521 putting the name in round brackets and moving it to the
9522 end, and bringing the email address forward).
9526 In a <tt>.changes</tt> file or parsed changelog data this
9527 contains the name and email address of the person
9528 responsible for the particular version in question - this
9529 may not be the package's usual maintainer.
9533 This field is usually optional in as far as the
9534 <prgn>dpkg</prgn> are concerned, but its absence when
9535 building packages usually generates a warning.</p>
9538 <sect1 id="pkg-f-Source"><heading><tt>Source</tt>
9542 This field identifies the source package name.
9546 In a main source control information or a
9547 <tt>.changes</tt> or <tt>.dsc</tt> file or parsed
9548 changelog data this may contain only the name of the
9553 In the control file of a binary package (or in a
9554 <tt>Packages</tt> file) it may be followed by a version
9555 number in parentheses.
9558 It is usual to leave a space after the package name if
9559 a version number is specified.
9561 </footnote> This version number may be omitted (and is, by
9562 <prgn>dpkg-gencontrol</prgn>) if it has the same value as
9563 the <tt>Version</tt> field of the binary package in
9564 question. The field itself may be omitted from a binary
9565 package control file when the source package has the same
9566 name and version as the binary package.
9570 <sect1><heading>Package interrelationship fields:
9571 <tt>Depends</tt>, <tt>Pre-Depends</tt>,
9572 <tt>Recommends</tt> <tt>Suggests</tt>, <tt>Conflicts</tt>,
9573 <tt>Provides</tt>, <tt>Replaces</tt>
9577 These fields describe the package's relationships with
9578 other packages. Their syntax and semantics are described
9579 in <ref id="relationships">.</p>
9582 <sect1 id="pkg-f-Description"><heading><tt>Description</tt>
9586 In a binary package <tt>Packages</tt> file or main source
9587 control file this field contains a description of the
9588 binary package, in a special format. See <ref
9589 id="descriptions"> for details.
9593 In a <tt>.changes</tt> file it contains a summary of the
9594 descriptions for the packages being uploaded. The part of
9595 the field before the first newline is empty; thereafter
9596 each line has the name of a binary package and the summary
9597 description line from that binary package. Each line is
9598 indented by one space.</p>
9601 <sect1 id="pkg-f-Essential"><heading><tt>Essential</tt>
9605 This is a boolean field which may occur only in the
9606 control file of a binary package (or in the
9607 <tt>Packages</tt> file) or in a per-package fields
9608 paragraph of a main source control data file.
9612 If set to <tt>yes</tt> then <prgn>dpkg</prgn> and
9613 <prgn>dselect</prgn> will refuse to remove the package
9614 (though it can be upgraded and/or replaced). The other
9615 possible value is <tt>no</tt>, which is the same as not
9616 having the field at all.</p>
9619 <sect1 id="pkg-f-classification"><heading><tt>Section</tt> and
9624 These two fields classify the package. The
9625 <tt>Priority</tt> represents how important that it is that
9626 the user have it installed; the <tt>Section</tt>
9627 represents an application area into which the package has
9632 When they appear in the <tt>debian/control</tt> file these
9633 fields give values for the section and priority subfields
9634 of the <tt>Files</tt> field of the <tt>.changes</tt> file,
9635 and give defaults for the section and priority of the
9640 The section and priority are represented, though not as
9641 separate fields, in the information for each file in the
9642 <qref id="pkg-f-Files"><tt>-File</tt></qref>field of a
9643 <tt>.changes</tt> file. The section value in a
9644 <tt>.changes</tt> file is used to decide where to install
9645 a package in the FTP archive.
9649 These fields are not used by by <prgn>dpkg</prgn> proper,
9650 but by <prgn>dselect</prgn> when it sorts packages and
9651 selects defaults. See the Debian policy manual for the
9652 priorities in use and the criteria for selecting the
9653 priority for a Debian package, and look at the Debian FTP
9654 archive for a list of currently in-use priorities.
9658 These fields may appear in binary package control files,
9659 in which case they provide a default value in case the
9660 <tt>Packages</tt> files are missing the information.
9661 <prgn>dpkg</prgn> and <prgn>dselect</prgn> will only use
9662 the value from a <tt>.deb</tt> file if they have no other
9663 information; a value listed in a <tt>Packages</tt> file
9664 will always take precedence. By default
9665 <prgn>dpkg-gencontrol</prgn> does not include the section
9666 and priority in the control file of a binary package - use
9667 the <tt>-isp</tt>, <tt>-is</tt> or <tt>-ip</tt> options to
9668 achieve this effect.</p>
9671 <sect1 id="pkg-f-Binary"><heading><tt>Binary</tt>
9675 This field is a list of binary packages.
9679 When it appears in the <tt>.dsc</tt> file it is the list
9680 of binary packages which a source package can produce. It
9681 does not necessarily produce all of these binary packages
9682 for every architecture. The source control file doesn't
9683 contain details of which architectures are appropriate for
9684 which of the binary packages.
9688 When it appears in a <tt>.changes</tt> file it lists the
9689 names of the binary packages actually being uploaded.
9693 The syntax is a list of binary packages separated by
9697 A space after each comma is conventional.
9699 </footnote> Currently the packages must be separated using
9700 only spaces in the <tt>.changes</tt> file.</p>
9703 <sect1 id="pkg-f-Installed-Size"><heading><tt>Installed-Size</tt>
9707 This field appears in the control files of binary
9708 packages, and in the <tt>Packages</tt> files. It gives
9709 the total amount of disk space required to install the
9714 The disk space is represented in kilobytes as a simple
9718 <sect1 id="pkg-f-Files"><heading><tt>Files</tt>
9722 This field contains a list of files with information about
9723 each one. The exact information and syntax varies with
9724 the context. In all cases the the part of the field
9725 contents on the same line as the field name is empty. The
9726 remainder of the field is one line per file, each line
9727 being indented by one space and containing a number of
9728 sub-fields separated by spaces.
9732 In the <tt>.dsc</tt> (Debian source control) file each
9733 line contains the MD5 checksum, size and filename of the
9734 tarfile and (if applicable) diff file which make up the
9735 remainder of the source package.
9738 That is, the parts which are not the
9741 </footnote> The exact forms of the filenames are described
9742 in <ref id="pkg-sourcearchives">.
9746 In the <tt>.changes</tt> file this contains one line per
9747 file being uploaded. Each line contains the MD5 checksum,
9748 size, section and priority and the filename. The section
9749 and priority are the values of the corresponding fields in
9750 the main source control file - see <ref
9751 id="pkg-f-classification">. If no section or priority is
9752 specified then <tt>-</tt> should be used, though section
9753 and priority values must be specified for new packages to
9754 be installed properly.
9758 The special value <tt>byhand</tt> for the section in a
9759 <tt>.changes</tt> file indicates that the file in question
9760 is not an ordinary package file and must by installed by
9761 hand by the distribution maintainers. If the section is
9762 <tt>byhand</tt> the priority should be <tt>-</tt>.
9766 If a new Debian revision of a package is being shipped and
9767 no new original source archive is being distributed the
9768 <tt>.dsc</tt> must still contain the <tt>Files</tt> field
9769 entry for the original source archive
9770 <tt><var>package</var>-<var>upstream-version</var>.orig.tar.gz</tt>,
9771 but the <tt>.changes</tt> file should leave it out. In
9772 this case the original source archive on the distribution
9773 site must match exactly, byte-for-byte, the original
9774 source archive which was used to generate the
9775 <tt>.dsc</tt> file and diff which are being uploaded.</p>
9780 id="pkg-f-Standards-Version"><heading><tt>Standards-Version</tt>
9784 The most recent version of the standards (the
9785 <prgn>dpkg</prgn> programmers' and policy manuals and
9786 associated texts) with which the package complies. This
9787 is updated manually when editing the source package to
9788 conform to newer standards; it can sometimes be used to
9789 tell when a package needs attention.
9793 Its format is the same as that of a version number except
9794 that no epoch or Debian revision is allowed - see <ref
9799 <sect1 id="pkg-f-Distribution"><heading><tt>Distribution</tt>
9803 In a <tt>.changes</tt> file or parsed changelog output
9804 this contains the (space-separated) name(s) of the
9805 distribution(s) where this version of the package should
9806 be or was installed. Distribution names follow the rules
9807 for package names. (See <ref id="pkg-f-Package">).
9811 Current distribution values are:
9813 <tag><em>stable</em></tag>
9816 This is the current `released' version of Debian
9817 GNU/Linux. A new version is released approximately
9818 every 3 months after the <em>development</em> code has
9819 been <em>frozen</em> for a month of testing. Once the
9820 distribution is <em>stable</em> only major bug fixes
9821 are allowed. When changes are made to this
9822 distribution, the release number is increased
9823 (for example: 1.2r1 becomes 1.2r2 then 1.2r3, etc).
9827 <tag><em>unstable</em></tag>
9830 This distribution value refers to the
9831 <em>developmental</em> part of the Debian distribution
9832 tree. New packages, new upstream versions of packages
9833 and bug fixes go into the <em>unstable</em> directory
9834 tree. Download from this distribution at your own
9838 <tag><em>contrib</em></tag>
9841 The packages with this distribution value do not meet
9842 the criteria for inclusion in the main Debian
9843 distribution as defined by the Policy Manual, but meet
9844 the criteria for the <em>contrib</em>
9845 Distribution. There is currently no distinction
9846 between stable and unstable packages in the
9847 <em>contrib</em> or <em>non-free</em>
9848 distributions. Use your best judgement in downloading
9849 from this Distribution.</p>
9852 <tag><em>non-free</em></tag>
9855 Like the packages in the <em>contrib</em> seciton,
9856 the packages in <em>non-free</em> do not meet the
9857 criteria for inclusion in the main Debian distribution
9858 as defined by the Policy Manual. Again, use your best
9859 judgement in downloading from this Distribution.</p>
9861 <tag><em>experimental</em></tag>
9864 The packages with this distribution value are deemed
9865 by their maintainers to be high risk. Oftentimes they
9866 represent early beta or developmental packages from
9867 various sources that the maintainers want people to
9868 try, but are not ready to be a part of the other parts
9869 of the Debian distribution tree. Download at your own
9873 <tag><em>frozen</em></tag>
9876 From time to time, (currently, every 3 months) the
9877 <em>unstable</em> distribution enters a state of
9878 `code-freeze' in anticipation of release as a
9879 <em>stable</em> version. During this period of testing
9880 (usually 4 weeks) only fixes for existing or
9881 newly-discovered bugs will be allowed.
9884 </taglist> You should list <em>all</em> distributions that
9885 the package should be installed into. Except in unusual
9886 circumstances, installations to <em>stable</em> should also
9887 go into <em>frozen</em> (if it exists) and
9888 <em>unstable</em>. Likewise, installations into
9889 <em>frozen</em> should also go into <em>unstable</em>.</p>
9892 <sect1 id="pkg-f-Urgency"><heading><tt>Urgency</tt>
9896 This is a description of how important it is to upgrade to
9897 this version from previous ones. It consists of a single
9898 keyword usually taking one of the values <tt>LOW</tt>,
9899 <tt>MEDIUM</tt> or <tt>HIGH</tt>) followed by an optional
9900 commentary (separated by a space) which is usually in
9901 parentheses. For example:
9903 Urgency: LOW (HIGH for diversions users)
9908 This field appears in the <tt>.changes</tt> file and in
9909 parsed changelogs; its value appears as the value of the
9910 <tt>urgency</tt> attribute in a <prgn>dpkg</prgn>-style
9911 changelog (see <ref id="pkg-dpkgchangelog">).
9915 Urgency keywords are not case-sensitive.</p>
9918 <sect1 id="pkg-f-Date"><heading><tt>Date</tt>
9922 In <tt>.changes</tt> files and parsed changelogs, this
9923 gives the date the package was built or last edited.</p>
9926 <sect1 id="pkg-f-Format"><heading><tt>Format</tt>
9930 This field occurs in <tt>.changes</tt> files, and
9931 specifies a format revision for the file. The format
9932 described here is version <tt>1.5</tt>. The syntax of the
9933 format value is the same as that of a package version
9934 number except that no epoch or Debian revision is allowed
9935 - see <ref id="versions">.</p>
9938 <sect1 id="pkg-f-Changes"><heading><tt>Changes</tt>
9942 In a <tt>.changes</tt> file or parsed changelog this field
9943 contains the human-readable changes data, describing the
9944 differences between the last version and the current one.
9948 There should be nothing in this field before the first
9949 newline; all the subsequent lines must be indented by at
9950 least one space; blank lines must be represented by a line
9951 consiting only of a space and a full stop.
9955 Each version's change information should be preceded by a
9956 `title' line giving at least the version, distribution(s)
9957 and urgency, in a human-readable way.
9961 If data from several versions is being returned the entry
9962 for the most recent version should be returned first, and
9963 entries should be separated by the representation of a
9964 blank line (the `title' line may also be followed by the
9965 representation of blank line).</p>
9968 <sect1 id="pkg-f-Filename"><heading><tt>Filename</tt> and
9969 <tt>MSDOS-Filename</tt>
9973 These fields in <tt>Packages</tt> files give the
9974 filename(s) of (the parts of) a package in the
9975 distribution directories, relative to the root of the
9976 Debian hierarchy. If the package has been split into
9977 several parts the parts are all listed in order, separated
9981 <sect1 id="pkg-f-Size"><heading><tt>Size</tt> and <tt>MD5sum</tt>
9985 These fields in <tt>Packages</tt> files give the size (in
9986 bytes, expressed in decimal) and MD5 checksum of the
9987 file(s) which make(s) up a binary package in the
9988 distribution. If the package is split into several parts
9989 the values for the parts are listed in order, separated by
9993 <sect1 id="pkg-f-Status"><heading><tt>Status</tt>
9997 This field in <prgn>dpkg</prgn>'s status file records
9998 whether the user wants a package installed, removed or
9999 left alone, whether it is broken (requiring
10000 reinstallation) or not and what its current state on the
10001 system is. Each of these pieces of information is a
10005 <sect1 id="pkg-f-Config-Version"><heading><tt>Config-Version</tt>
10009 If a package is not installed or not configured, this
10010 field in <prgn>dpkg</prgn>'s status file records the last
10011 version of the package which was successfully
10015 <sect1 id="pkg-f-Conffiles"><heading><tt>Conffiles</tt>
10019 This field in <prgn>dpkg</prgn>'s status file contains
10020 information about the automatically-managed configuration
10021 files held by a package. This field should <em>not</em>
10022 appear anywhere in a package!</p>
10025 <sect1><heading>Obsolete fields
10029 These are still recognised by <prgn>dpkg</prgn> but should
10030 not appear anywhere any more.
10031 <taglist compact="compact">
10033 <tag><tt>Revision</tt></tag>
10034 <tag><tt>Package-Revision</tt></tag>
10035 <tag><tt>Package_Revision</tt></tag>
10038 The Debian revision part of the package version was
10039 at one point in a separate control file field. This
10040 field went through several names.</p>
10043 <tag><tt>Recommended</tt></tag>
10044 <item><p>Old name for <tt>Recommends</tt></p>
10047 <tag><tt>Optional</tt></tag>
10048 <item><p>Old name for <tt>Suggests</tt>.</p>
10050 <tag><tt>Class</tt></tag>
10051 <item><p>Old name for <tt>Priority</tt>.</p>
10059 <appendix id="pkg-conffiles"><heading>Configuration file handling
10060 (from old Packaging Manual)
10064 <prgn>dpkg</prgn> can do a certain amount of automatic
10065 handling of package configuration files.
10069 Whether this mechanism is appropriate depends on a number of
10070 factors, but basically there are two approaches to any
10071 particular configuration file.
10075 The easy method is to ship a best-effort configuration in the
10076 package, and use <prgn>dpkg</prgn>'s conffile mechanism to
10077 handle updates. If the user is unlikely to want to edit the
10078 file, but you need them to be able to without losing their
10079 changes, and a new package with a changed version of the file
10080 is only released infrequently, this is a good approach.
10084 The hard method is to build the configuration file from
10085 scratch in the <prgn>postinst</prgn> script, and to take the
10086 responsibility for fixing any mistakes made in earlier
10087 versions of the package automatically. This will be
10088 appropriate if the file is likely to need to be different on
10092 <sect><heading>Automatic handling of configuration files by
10097 A package may contain a control area file called
10098 <tt>conffiles</tt>. This file should be a list of filenames
10099 of configuration files needing automatic handling, separated
10100 by newlines. The filenames should be absolute pathnames,
10101 and the files referred to should actually exist in the
10106 When a package is upgraded <prgn>dpkg</prgn> will process
10107 the configuration files during the configuration stage,
10108 shortly before it runs the package's <prgn>postinst</prgn>
10113 For each file it checks to see whether the version of the
10114 file included in the package is the same as the one that was
10115 included in the last version of the package (the one that is
10116 being upgraded from); it also compares the version currently
10117 installed on the system with the one shipped with the last
10122 If neither the user nor the package maintainer has changed
10123 the file, it is left alone. If one or the other has changed
10124 their version, then the changed version is preferred - i.e.,
10125 if the user edits their file, but the package maintainer
10126 doesn't ship a different version, the user's changes will
10127 stay, silently, but if the maintainer ships a new version
10128 and the user hasn't edited it the new version will be
10129 installed (with an informative message). If both have
10130 changed their version the user is prompted about the problem
10131 and must resolve the differences themselves.
10135 The comparisons are done by calculating the MD5 message
10136 digests of the files, and storing the MD5 of the file as it
10137 was included in the most recent version of the package.
10141 When a package is installed for the first time
10142 <prgn>dpkg</prgn> will install the file that comes with it,
10143 unless that would mean overwriting a file already on the
10148 However, note that <prgn>dpkg</prgn> will <em>not</em>
10149 replace a conffile that was removed by the user (or by a
10150 script). This is necessary because with some programs a
10151 missing file produces an effect hard or impossible to
10152 achieve in another way, so that a missing file needs to be
10153 kept that way if the user did it.
10157 Note that a package should <em>not</em> modify a
10158 <prgn>dpkg</prgn>-handled conffile in its maintainer
10159 scripts. Doing this will lead to <prgn>dpkg</prgn> giving
10160 the user confusing and possibly dangerous options for
10161 conffile update when the package is upgraded.</p>
10164 <sect><heading>Fully-featured maintainer script configuration
10169 For files which contain site-specific information such as
10170 the hostname and networking details and so forth, it is
10171 better to create the file in the package's
10172 <prgn>postinst</prgn> script.
10176 This will typically involve examining the state of the rest
10177 of the system to determine values and other information, and
10178 may involve prompting the user for some information which
10179 can't be obtained some other way.
10183 When using this method there are a couple of important
10184 issues which should be considered:
10188 If you discover a bug in the program which generates the
10189 configuration file, or if the format of the file changes
10190 from one version to the next, you will have to arrange for
10191 the postinst script to do something sensible - usually this
10192 will mean editing the installed configuration file to remove
10193 the problem or change the syntax. You will have to do this
10194 very carefully, since the user may have changed the file,
10195 perhaps to fix the very problem that your script is trying
10196 to deal with - you will have to detect these situations and
10197 deal with them correctly.
10201 If you do go down this route it's probably a good idea to
10202 make the program that generates the configuration file(s) a
10203 separate program in <tt>/usr/sbin</tt>, by convention called
10204 <tt><var>package</var>config</tt> and then run that if
10205 appropriate from the post-installation script. The
10206 <tt><var>package</var>config</tt> program should not
10207 unquestioningly overwrite an existing configuration - if its
10208 mode of operation is geared towards setting up a package for
10209 the first time (rather than any arbitrary reconfiguration
10210 later) you should have it check whether the configuration
10211 already exists, and require a <tt>--force</tt> flag to
10212 overwrite it.</p></sect>
10215 <appendix id="pkg-alternatives"><heading>Alternative versions of
10216 an interface - <prgn>update-alternatives</prgn> (from old
10221 When several packages all provide different versions of the
10222 same program or file it is useful to have the system select a
10223 default, but to allow the system administrator to change it
10224 and have their decisions respected.
10228 For example, there are several versions of the <prgn>vi</prgn>
10229 editor, and there is no reason to prevent all of them from
10230 being installed at once, each under their own name
10231 (<prgn>nvi</prgn>, <prgn>vim</prgn> or whatever).
10232 Nevertheless it is desirable to have the name <tt>vi</tt>
10233 refer to something, at least by default.
10237 If all the packages involved cooperate, this can be done with
10238 <prgn>update-alternatives</prgn>.
10242 Each package provides its own version under its own name, and
10243 calls <prgn>update-alternatives</prgn> in its postinst to
10244 register its version (and again in its prerm to deregister
10249 See the manpage <manref name="update-alternatives"
10250 section="8"> for details.
10254 If <prgn>update-alternatives</prgn> does not seem appropriate
10255 you may wish to consider using diversions instead.</p>
10258 <appendix id="pkg-diversions"><heading>Diversions - overriding a
10259 package's version of a file (from old Packaging Manual)
10263 It is possible to have <prgn>dpkg</prgn> not overwrite a file
10264 when it reinstalls the package it belongs to, and to have it
10265 put the file from the package somewhere else instead.
10269 This can be used locally to override a package's version of a
10270 file, or by one package to override another's version (or
10271 provide a wrapper for it).
10275 Before deciding to use a diversion, read <ref
10276 id="pkg-alternatives"> to see if you really want a diversion
10277 rather than several alternative versions of a program.
10281 There is a diversion list, which is read by <prgn>dpkg</prgn>,
10282 and updated by a special program <prgn>dpkg-divert</prgn>.
10283 Please see <manref name="dpkg-divert" section="8"> for full
10284 details of its operation.
10288 When a package wishes to divert a file from another, it should
10289 call <prgn>dpkg-divert</prgn> in its preinst to add the
10290 diversion and rename the existing file. For example,
10291 supposing that a <prgn>smailwrapper</prgn> package wishes to
10292 install a wrapper around <tt>/usr/sbin/smail</tt>:
10294 if [ install = "$1" -o upgrade = "$1" ]; then
10295 dpkg-divert --package smailwrapper --add --rename \
10296 --divert /usr/sbin/smail.real /usr/sbin/smail
10298 </example> Testing <tt>$1</tt> is necessary so that the script
10299 doesn't try to add the diversion again when
10300 <prgn>smailwrapper</prgn> is upgraded. The <tt>--package
10301 smailwrapper</tt> ensures that <prgn>smailwrapper</prgn>'s
10302 copy of <tt>/usr/sbin/smail</tt> can bypass the diversion and
10303 get installed as the true version.
10307 The postrm has to do the reverse:
10309 if [ remove = "$1" ]; then
10310 dpkg-divert --package smailwrapper --remove --rename \
10311 --divert /usr/sbin/smail.real /usr/sbin/smail
10317 Do not attempt to divert a file which is vitally important for
10318 the system's operation - when using <prgn>dpkg-divert</prgn>
10319 there is a time, after it has been diverted but before
10320 <prgn>dpkg</prgn> has installed the new version, when the file
10321 does not exist.</p>