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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.</p>
769 <tag><tt>optional</tt></tag>
772 (In a sense everything that isn't required is
773 optional, but that's not what is meant here.) This is
774 all the software that you might reasonably want to
775 install if you didn't know what it was and don't have
776 specialized requirements. This is a much larger system
777 and includes the X Window System, a full TeX
778 distribution, and many applications. Note that
779 optional packages should not conflict with each other.
782 <tag><tt>extra</tt></tag>
785 This contains all packages that conflict with others
786 with required, important, standard or optional
787 priorities, or are only likely to be useful if you
788 already know what they are or have specialised
795 Packages must not depend on packages with lower priority
796 values (excluding build-time dependencies). In order to
797 ensure this, the priorities of one or more packages may need
803 <heading>Binary packages</heading>
806 The Debian GNU/Linux distribution is based on the Debian
807 package management system, called <prgn>dpkg</prgn>. Thus,
808 all packages in the Debian distribution must be provided
809 in the <tt>.deb</tt> file format.</p>
813 <heading>The package name</heading>
816 Every package must have a name that's unique within the Debian
820 Package names must consist of lower case letters
821 (<tt>a-z</tt>), digits (<tt>0-9</tt>), plus (<tt>+</tt>)
822 and minus (<tt>-</tt>) signs, and periods (<tt>.</tt>).
823 They must be at least two characters long and must contain
828 The package name is part of the file name of the
829 <tt>.deb</tt> file and is included in the control field
835 <heading>The maintainer of a package</heading>
837 Every package must have a Debian maintainer (the
838 maintainer may be one person or a group of people
839 reachable from a common email address, such as a mailing
840 list). The maintainer is responsible for ensuring that
841 the package is placed in the appropriate distributions.
845 The maintainer must be specified in the
846 <tt>Maintainer</tt> control field with their correct name
847 and a working email address. If one person maintains
848 several packages, he/she should try to avoid having
849 different forms of their name and email address in
850 the <tt>Maintainer</tt> fields of those packages.
854 If the maintainer of a package quits from the Debian
855 project, "Debian QA Group"
856 <email>packages@qa.debian.org</email> takes over the
857 maintainership of the package until someone else
858 volunteers for that task. These packages are called
859 <em>orphaned packages</em>.<footnote>
861 The detailed procedure for doing this gracefully can
862 be found in the Debian Developer's Reference, either
863 in the <tt>developers-reference</tt> package, or on
864 the Debian FTP server
865 <ftpsite>ftp.debian.org</ftpsite> as
866 <ftppath>/debian/doc/package-developer/developers-reference.txt.gz</ftppath>
868 id="http://www.debian.org/doc/packaging-manuals/developers-reference/"
869 name="Debian Developer's Reference"> webpage.
877 <heading>The description of a package</heading>
880 Every Debian package must have an extended description
881 stored in the appropriate field of the control record.</p>
884 The description should be written so that it gives the
885 system administrator enough information to decide whether
886 to install the package. This description should not just
887 be copied verbatim from the program's documentation.
888 Instructions for configuring or using the package should
889 not be included (that is what installation scripts,
890 manual pages, info files, etc., are for). Copyright
891 statements and other administrivia should not be included
892 either (that is what the copyright file is for).
898 <heading>Dependencies</heading>
901 Every package must specify the dependency information
902 about other packages that are required for the first to
906 For example, a dependency entry must be provided for any
907 shared libraries required by a dynamically-linked executable
908 binary in a package.</p>
911 Packages are not required to declare any dependencies they
912 have on other packages which are marked <tt>Essential</tt>
913 (see below), and should not do so unless they depend on a
914 particular version of that package.</p>
917 Sometimes, a package requires another package to be installed
918 <em>and</em> configured before it can be installed. In this
919 case, you must specify a <tt>Pre-Depends</tt> entry for
923 You should not specify a <tt>Pre-Depends</tt> entry for a
924 package before this has been discussed on the
925 <tt>debian-devel</tt> mailing list and a consensus about
926 doing that has been reached.</p></sect1>
930 <heading>Virtual packages</heading>
933 Sometimes, there are several packages which offer
934 more-or-less the same functionality. In this case, it's
935 useful to define a <em>virtual package</em> whose name
936 describes that common functionality. (The virtual
937 packages only exist logically, not physically; that's why
938 they are called <em>virtual</em>.) The packages with this
939 particular function will then <em>provide</em> the virtual
940 package. Thus, any other package requiring that function
941 can simply depend on the virtual package without having to
942 specify all possible packages individually.</p>
945 All packages should use virtual package names where
946 appropriate, and arrange to create new ones if necessary.
947 They should not use virtual package names (except privately,
948 amongst a cooperating group of packages) unless they have
949 been agreed upon and appear in the list of virtual package
953 The latest version of the authoritative list of virtual
954 package names can be found on
955 <ftpsite>ftp.debian.org</ftpsite> in
956 <ftppath>/debian/doc/package-developer/virtual-package-names-list.txt</ftppath>
957 or your local mirror. In addition, it is included in the
958 <tt>debian-policy</tt> package. The procedure for updating
959 the list is described at the top of the file.</p></sect1>
963 <heading>Base packages</heading>
966 The packages included in the <tt>base</tt> section have a
967 special function. They form a minimum subset of the Debian
968 GNU/Linux system that is installed before everything else
969 on a new system. Thus, only very few packages are allowed
970 to go into the <tt>base</tt> section to keep the required
971 disk usage very small.</p>
974 Most of these packages will have the priority value
975 <tt>required</tt> or at least <tt>important</tt>, and many
976 of them will be tagged <tt>essential</tt> (see below).</p>
979 You must not place any packages into the <tt>base</tt>
980 section before this has been discussed on the
981 <tt>debian-devel</tt> mailing list and a consensus about
982 doing that has been reached.</p></sect1>
986 <heading>Essential packages</heading>
989 Some packages are tagged <tt>essential</tt>. (They have
990 <tt>Essential: yes</tt> in their package control record.)
991 This flag is used for packages that are <em>essential</em>
995 Since these packages cannot be easily removed (one has to
996 specify an extra <em>force option</em> to
997 <prgn>dpkg</prgn> to do so), this flag must not be used
998 unless absolutely necessary. A shared library package
999 must not be tagged <tt>essential</tt>; dependencies will
1000 prevent its premature removal, and we need to be able to
1001 remove it when it has been superseded.
1005 Since dpkg will not prevent upgrading of other packages
1006 while an <tt>essential</tt> package is in an unconfigured
1007 state, all <tt>essential</tt> packages must supply all of
1008 their core functionality even when unconfigured. If the
1009 package cannot satisfy this requirement it must not be
1010 tagged as essential, and any packages depending on this
1011 package must instead have explicit dependency fields as
1016 You must not tag any packages <tt>essential</tt> before
1017 this has been discussed on the <tt>debian-devel</tt>
1018 mailing list and a consensus about doing that has been
1023 <sect1 id="maintscripts">
1024 <heading>Maintainer scripts</heading>
1027 The package installation scripts should avoid producing
1028 output which it is unnecessary for the user to see and
1029 should rely on <prgn>dpkg</prgn> to stave off boredom on
1030 the part of a user installing many packages. This means,
1031 amongst other things, using the <tt>--quiet</tt> option on
1032 <prgn>install-info</prgn>.</p>
1035 Errors which occur during the execution of an installation
1036 script must be checked and the installation must not
1037 continue after an error.
1041 Note that in general <ref id="scripts"> applies to package
1042 maintainer scripts, too.
1046 You should not use <tt>dpkg-divert</tt> on a file
1047 belonging to another package without consulting the
1048 maintainer of that package first.
1052 All packages which supply an instance of a common command
1053 name (or, in general, filename) should generally use
1054 <prgn>update-alternatives</prgn>, so that they may be
1055 installed together. If <prgn>update-alternatives</prgn>
1056 is not used, then each package must use
1057 <tt>Conflicts</tt> to ensure that other packages are
1058 de-installed. (In this case, it may be appropriate to
1059 specify a conflict against earlier versions of something
1060 that previously did not use
1061 <prgn>update-alternatives</prgn>; this is an exception to
1062 the usual rule that versioned conflicts should be
1068 <heading>Prompting in maintainer scripts</heading>
1070 Package maintainer scripts may prompt the user if
1071 necessary. Prompting may be accomplished by hand, or by
1072 communicating with a program, such as
1073 <prgn>debconf</prgn>, which conforms to the Debian
1074 Configuration management specification, version 2 or
1075 higher. These are included in the
1076 <tt>debconf_specification</tt> files in the
1077 <package>debian-policy</package> package.
1078 You may also find this file on the FTP site
1079 <ftpsite>ftp.debian.org</ftpsite> in
1080 <ftppath>/debian/doc/package-developer/debconf_specification.txt.gz</ftppath>
1081 or on your local mirror.<footnote>
1083 4% of Debian packages [see <url
1084 id="http://kitenet.net/programs/debconf/stats/"
1085 name="Debconf stats">] currently use
1086 <package>debconf</package> to prompt the user at
1087 install time, and this number is growing daily. The
1088 benefits of using debconf are briefly explained at
1090 id="http://kitenet.net/doc/debconf-doc/introduction.html"
1091 name="Debconf introduction">; they include
1092 preconfiguration, (mostly) noninteractive
1093 installation, elimination of redundant prompting,
1094 consistency of user interface, etc.
1097 With this increasing number of packages using
1098 <package>debconf</package>, plus the existance of a
1099 nascent second implementation of the Debian
1100 configuration management system
1101 (<package>cdebconf</package>), and the stabalization
1102 of the protocol these things use, the time has
1103 finally come to reflect the use of these things in
1110 Packages which use the Debian Configuration management
1111 specification may contain an additional
1112 <prgn>config</prgn> script and a <tt>templates</tt>
1113 file in their control archive. The <prgn>config</prgn>
1114 script might be run before the <prgn>preinst</prgn>
1115 script, and before the package is unpacked or any of its
1116 dependencies or pre-dependancies are satisfied.
1117 Therefore it must work using only the tools present in
1118 <em>essential</em> packages.<footnote>
1120 <package>Debconf</package> or another tool that
1121 implements the Debian Configuration management
1122 specification will also be installed, and any
1123 versioned dependencies on it will be satisfied
1124 before preconfiguration begins.
1130 Packages should try to minimize the amount of prompting
1131 they need to do, and they should ensure that the user
1132 will only ever be asked each question once. This means
1133 that packages should try to use appropriate shared
1134 configuration files (such as <tt>/etc/papersize</tt> and
1135 <tt>/etc/news/server</tt>), and shared
1136 <package>debconf</package> variables rather than each
1137 prompting for their own list of required pieces of
1142 It also means that an upgrade should not ask the same
1143 questions again, unless the user has used <tt>dpkg
1144 --purge</tt> to remove the package's configuration. The
1145 answers to configuration questions should be stored in an
1146 appropriate place in <tt>/etc</tt> so that the user can
1147 modify them, and how this has been done should be
1151 If a package has a vitally important piece of
1152 information to pass to the user (such as "don't run me
1153 as I am, you must edit the following configuration files
1154 first or you risk your system emitting badly-formatted
1155 messages"), it should display this in the
1156 <prgn>config</prgn> or <prgn>postinst</prgn> script and
1157 prompt the user to hit return to acknowledge the
1158 message. Copyright messages do not count as vitally
1159 important (they belong in
1160 <tt>/usr/share/doc/<var>package</var>/copyright</tt>);
1161 neither do instructions on how to use a program (these
1162 should be in on-line documentation, where all the users
1166 Any necessary prompting should almost always be confined
1167 to the <prgn>config</prgn> or <prgn>postinst</prgn>
1168 script. If it is done in the <prgn>postinst</prgn>, it
1169 should be protected with a conditional so that
1170 unnecessary prompting doesn't happen if a package's
1171 installation fails and the <prgn>postinst</prgn> is
1172 called with <tt>abort-upgrade</tt>,
1173 <tt>abort-remove</tt> or <tt>abort-deconfigure</tt>.</p>
1178 <heading>Source packages</heading>
1180 <sect1 id="standardsversion">
1181 <heading>Standards conformance</heading>
1184 In the source package's <tt>Standards-Version</tt> control
1185 field, you should specify the most recent version number
1186 of this policy document with which your package complied
1187 when it was last updated. The current version number is
1192 This information may be used to file bug reports
1193 automatically if your package becomes too much out of
1198 The version number has four components: major and minor
1199 version number and major and minor patch level. When the
1200 standards change in a way that requires every package to
1201 change the major number will be changed. Significant
1202 changes that will require work in many packages will be
1203 signaled by a change to the minor number. The major patch
1204 level will be changed for any change to the meaning of the
1205 standards, however small; the minor patch level will be
1206 changed when only cosmetic, typographical or other edits
1207 are made which neither change the meaning of the document
1208 nor affect the contents of packages.</p>
1211 Thus only the first three components of the policy version
1212 are significant in the <em>Standards-Version</em> control
1213 field, and so either these three components or the all
1214 four components may be specified.<footnote>
1216 In the past, people specified the full version number
1217 in the Standards-Version field, for example `2.3.0.0'.
1218 Since minor patch-level changes don't introduce new
1219 policy, it was thought it would be better to relax
1220 policy and only require the first 3 components to be
1221 specified, in this example `2.3.0'. All four
1222 components may still be used if someone wishes to do
1229 You should regularly, and especially if your package has
1230 become out of date, check for the newest Policy Manual
1231 available and update your package, if necessary. When your
1232 package complies with the new standards you should update the
1233 <tt>Standards-Version</tt> source package field and
1234 release it.<footnote>
1236 See the file <tt>upgrading-checklist</tt> for
1237 information about policy which has changed between
1238 different versions of this document.
1246 <heading>Package relationships</heading>
1249 Source packages should specify which binary packages they
1250 require to be installed or not to be installed in order to
1251 build correctly. For example, if building a package
1252 requires a certain compiler, then the compiler should be
1253 specified as a build-time dependency.
1257 It is not necessary to explicitly specify build-time
1258 relationships on a minimal set of packages that are always
1259 needed to compile, link and put in a Debian package a
1260 standard "Hello World!" program written in C or C++. The
1261 required packages are called <em>build-essential</em>, and
1262 an informational list can be found in
1263 <tt>/usr/share/doc/build-essential/list</tt> (which is
1264 contained in the <tt>build-essential</tt>
1267 <list compact="compact">
1269 <p>This allows maintaining the list separately
1270 from the policy documents (the list does not
1271 need the kind of control that the policy
1277 Having a separate package allows one to install
1278 the build-essential packages on a machine, as
1279 well as allowing other packages such as task
1280 packages to require installation of the
1281 build-essential packages using the depends
1287 The separate package allows bug reports against
1288 the list to be categorized separately from
1289 the policy management process in the BTS.
1299 When specifying the set of build-time dependencies, one
1300 should list only those packages explicitly required by the
1301 build. It is not necessary to list packages which are
1302 required merely because some other package in the list of
1303 build-time dependencies depends on them.<footnote>
1305 The reason for this is that dependencies change, and
1306 you should list all those packages, and <em>only</em>
1307 those packages that <em>you</em> need directly. What
1308 others need is their business. For example, if you
1309 only link against <tt>libimlib</tt>, you will need to
1310 build-depend on <package>libimlib2-dev</package> but
1311 not against any <tt>libjpeg*</tt> packages, even
1312 though <tt>libimlib2-dev</tt> currently depends on
1313 them: installation of <package>libimlib2-dev</package>
1314 will automatically ensure that all of its run-time
1315 dependencies are satisfied.
1321 If build-time dependencies are specified, it must be
1322 possible to build the package and produce working binaries
1323 on a system with only essential and build-essential
1324 packages installed and also those required to satisfy the
1325 build-time relationships (including any implied
1326 relationships). In particular, this means that version
1327 clauses should be used rigorously in build-time
1328 relationships so that one cannot produce bad or
1329 inconsistently configured packages when the relationships
1330 are properly satisfied.
1334 <heading>Changes to the upstream sources</heading>
1337 If changes to the source code are made that are not
1338 specific to the needs of the Debian system, they should be
1339 sent to the upstream authors in whatever form they prefer
1340 so as to be included in the upstream version of the
1344 If you need to configure the package differently for
1345 Debian or for Linux, and the upstream source doesn't
1346 provide a way to do so, you should add such configuration
1347 facilities (for example, a new <prgn>autoconf</prgn> test
1348 or <tt>#define</tt>) and send the patch to the upstream
1349 authors, with the default set to the way they originally
1350 had it. You can then easily override the default in your
1351 <tt>debian/rules</tt> or wherever is appropriate.</p>
1354 You should make sure that the <prgn>configure</prgn> utility
1355 detects the correct architecture specification string
1356 (refer to <ref id="arch-spec"> for details).</p>
1359 If you need to edit a <prgn>Makefile</prgn> where
1360 GNU-style <prgn>configure</prgn> scripts are used, you
1361 should edit the <tt>.in</tt> files rather than editing the
1362 <prgn>Makefile</prgn> directly. This allows the user to
1363 reconfigure the package if necessary. You should
1364 <em>not</em> configure the package and edit the generated
1365 <prgn>Makefile</prgn>! This makes it impossible for
1366 someone else to later reconfigure the package.</p></sect1>
1370 <heading>Documenting your changes</heading>
1373 You should document your changes and updates to the source
1374 package properly in the <tt>debian/changelog</tt> file. (Note
1375 that mistakes in changelogs are usually best rectified by
1376 making a new changelog entry rather than "rewriting history"
1377 by editing old changelog entries.)</p>
1380 In non-experimental packages you must use a format for
1381 <tt>debian/changelog</tt> which is supported by the most
1382 recent released version of <prgn>dpkg</prgn>.<footnote>
1384 If you wish to use an alternative format, you may do
1385 so as long as you include a parser for it in your
1386 source package. The parser must have an API
1387 compatible with that expected by
1388 <prgn>dpkg-genchanges</prgn> and
1389 <prgn>dpkg-gencontrol</prgn>. If there is general
1390 interest in the new format, you should contact the
1391 <package>dpkg</package> maintainer to have the parser
1392 script for it included in the <prgn>dpkg</prgn>
1393 package. (You will need to agree that the parser and
1394 its manpage may be distributed under the GNU GPL, just
1395 as the rest of `dpkg' is.)
1403 <heading>Error trapping in makefiles</heading>
1406 When <prgn>make</prgn> invokes a command in a makefile
1407 (including your package's upstream makefiles and
1408 <tt>debian/rules</tt>), it does so using <tt>sh</tt>. This
1409 means that <tt>sh</tt>'s usual bad error handling
1410 properties apply: if you include a miniature script as one
1411 of the commands in your makefile you'll find that if you
1412 don't do anything about it then errors are not detected
1413 and <prgn>make</prgn> will blithely continue after
1417 Every time you put more than one shell command (this
1418 includes using a loop) in a makefile command you
1419 must make sure that errors are trapped. For
1420 simple compound commands, such as changing directory and
1421 then running a program, using <tt>&&</tt> rather
1422 than semicolon as a command separator is sufficient. For
1423 more complex commands including most loops and
1424 conditionals you should include a separate <tt>set -e</tt>
1425 command at the start of every makefile command that's
1426 actually one of these miniature shell scripts.</p></sect1>
1430 <heading>Obsolete constructs and libraries</heading>
1433 The include file <tt><varargs.h></tt> is
1434 provided to support end-users compiling very old software;
1435 the library <tt>libtermcap</tt> is provided to support the
1436 execution of software which has been linked against it
1437 (either old programs or those such as Netscape which are
1438 only available in binary form).</p>
1441 Debian packages should be patched to use
1442 <tt><stdarg.h></tt> and <tt>ncurses</tt>
1449 <chapt id="controlfields"><heading>Control files and their fields</heading>
1452 Many of the tools in the package management suite manipulate
1453 data represented in a common format, known as <em>control
1454 data</em>. The data is often stored in <em>control
1455 files</em>. Binary and source packages have control files,
1456 and the <tt>.changes</tt> files which control the installation
1457 of uploaded files are also in control file format.
1458 <prgn>Dpkg</prgn>'s internal databases are in a similar
1462 <sect id="controlsyntax"><heading>Syntax of control files</heading>
1465 A control file consists of one or more paragraphs of fields.
1466 The paragraphs are separated by blank lines. Some control
1467 files allow only one paragraph; others allow several, in
1468 which case each paragraph usually refers to a different
1469 package. (For example, in source packages, the first
1470 paragraph refers to the source package, and later paragraphs
1471 refer to binary packages generated from the source.)
1475 Each paragraph consists of a series of data fields; each
1476 field consists of the field name, followed by a colon and
1477 then the data/value associated with that field. It ends at
1478 the end of the line. Horizontal whitespace (spaces and
1479 tabs) may occur immediately before or after the value and is
1480 ignored there; it is conventional to put a single space
1481 after the colon. For example, a field might be:
1482 <example compact="compact">
1485 the field name is <tt>Package</tt> and the field value
1490 Some fields' values may span several lines; in this case
1491 each continuation line <em>must</em> start with a space or
1492 tab. Any trailing spaces or tabs at the end of individual
1493 lines of a field value are ignored.
1497 Except where otherwise stated only a single line of data is
1498 allowed and whitespace is not significant in a field body.
1499 Whitespace must not appear inside names (of packages,
1500 architectures, files or anything else) or version numbers,
1501 or between the characters of multi-character version
1506 Field names are not case-sensitive, but it is usual to
1507 capitalize the field names using mixed case as shown below.
1511 Blank lines, or lines consisting only of spaces and tabs,
1512 are not allowed within field values or between fields - that
1513 would mean a new paragraph.
1518 <sect><heading>List of fields</heading>
1520 This list here is not supposed to be exhaustive. Most fields
1521 are dealt with elsewhere in this document.
1523 <sect1 id="f-Package"><heading><tt>Package</tt>
1527 The name of the binary package. Package names consist of
1528 the alphanumerics and <tt>+</tt> <tt>-</tt> <tt>.</tt>
1529 (plus, minus and full stop).
1533 They must be at least two characters long and must start
1534 with an alphanumeric character and not be all digits. The
1535 use of lowercase package names is strongly recommended
1536 unless the package you're building (or referring to, in
1537 other fields) is already using uppercase.</p>
1540 <sect1 id="f-Version"><heading><tt>Version</tt>
1544 This lists the source or binary package's version number -
1545 see <ref id="versions">.
1551 id="f-Standards-Version"><heading><tt>Standards-Version</tt>
1555 The most recent version of the standards (the policy
1556 manual and associated texts) with which the package
1557 complies. This is updated manually when editing the
1558 source package to conform to newer standards; it can
1559 sometimes be used to tell when a package needs attention.
1560 Its format is described above; see
1561 <ref id="standardsversion">.
1566 <sect1 id="f-Distribution"><heading><tt>Distribution</tt>
1570 In a <tt>.changes</tt> file or parsed changelog output
1571 this contains the (space-separated) name(s) of the
1572 distribution(s) where this version of the package should
1573 be installed. Valid distributions are determined by the
1574 archive maintainers.<footnote>
1575 Current distribution names are:
1576 <taglist compact="compact">
1577 <tag><em>stable</em></tag>
1580 This is the current `released' version of Debian
1581 GNU/Linux. Once the distribution is
1582 <em>stable</em> only security fixes and other
1583 major bug fixes are allowed. When changes are
1584 made to this distribution, the release number is
1585 increased (for example: 2.2r1 becomes 2.2r2 then
1590 <tag><em>unstable</em></tag>
1593 This distribution value refers to the
1594 <em>developmental</em> part of the Debian
1595 distribution tree. New packages, new upstream
1596 versions of packages and bug fixes go into the
1597 <em>unstable</em> directory tree. Download from
1598 this distribution at your own risk.
1602 <tag><em>testing</em></tag>
1605 This distribution value refers to the
1606 <em>testing</em> part of the Debian distribution
1607 tree. It receives its packages from the
1608 unstable distribution after a short time lag to
1609 ensure that there are no major issues with the
1610 unstable packages. It is less prone to breakage
1611 than unstable, but still risky. It is not
1612 possible to upload packages directly to
1617 <tag><em>frozen</em></tag>
1620 From time to time, the <em>testing</em>
1621 distribution enters a state of `code-freeze' in
1622 anticipation of release as a <em>stable</em>
1623 version. During this period of testing only
1624 fixes for existing or newly-discovered bugs will
1625 be allowed. The exact details of this stage are
1626 determined by the Release Manager.
1630 <tag><em>experimental</em></tag>
1633 The packages with this distribution value are
1634 deemed by their maintainers to be high
1635 risk. Oftentimes they represent early beta or
1636 developmental packages from various sources that
1637 the maintainers want people to try, but are not
1638 ready to be a part of the other parts of the
1639 Debian distribution tree. Download at your own
1645 You should list <em>all</em> distributions that the
1646 package should be installed into.
1655 <chapt id="versions"><heading>Version numbering</heading>
1658 Every package has a version number recorded in its
1659 <tt>Version</tt> control file field.
1663 The package management system imposes an ordering on version
1664 numbers, so that it can tell whether packages are being up- or
1665 downgraded and so that package system front end applications
1666 can tell whether a package it finds available is newer than
1667 the one installed on the system. The version number format
1668 has the most significant parts (as far as comparison is
1669 concerned) at the beginning.
1673 The version number format is:
1674 [<var>epoch</var><tt>:</tt>]<var>upstream_version</var>[<tt>-</tt><var>debian_revision</var>]
1678 The three components here are:
1680 <tag><var>epoch</var></tag>
1683 This is a single (generally small) unsigned integer. It
1684 may be omitted, in which case zero is assumed. If it is
1685 omitted then the <var>upstream_version</var> may not
1690 It is provided to allow mistakes in the version numbers
1691 of older versions of a package, and also a package's
1692 previous version numbering schemes, to be left behind.
1696 <tag><var>upstream_version</var></tag>
1699 This is the main part of the version number. It is
1700 usually the version number of the original (`upstream')
1701 package from which the <tt>.deb</tt> file has been made,
1702 if this is applicable. Usually this will be in the same
1703 format as that specified by the upstream author(s);
1704 however, it may need to be reformatted to fit into the
1705 package management system's format and comparison
1710 The comparison behavior of the package management system
1711 with respect to the <var>upstream_version</var> is
1712 described below. The <var>upstream_version</var>
1713 portion of the version number is mandatory.
1717 The <var>upstream_version</var> may contain only
1718 alphanumerics<footnote>
1719 <p>Alphanumerics are <tt>A-Za-z0-9</tt> only.</p>
1721 and the characters <tt>.</tt> <tt>+</tt> <tt>-</tt>
1722 <tt>:</tt> (full stop, plus, hyphen, colon) and should
1723 start with a digit. If there is no
1724 <var>debian_revision</var> then hyphens are not allowed;
1725 if there is no <var>epoch</var> then colons are not
1729 <tag><var>debian_revision</var></tag>
1732 This part of the version number specifies the version of
1733 the Debian package based on the upstream version. It
1734 may contain only alphanumerics and the characters
1735 <tt>+</tt> and <tt>.</tt> (plus and full stop) and is
1736 compared in the same way as the
1737 <var>upstream_version</var> is.
1741 It is optional; if it isn't present then the
1742 <var>upstream_version</var> may not contain a hyphen.
1743 This format represents the case where a piece of
1744 software was written specifically to be turned into a
1745 Debian package, and so there is only one `debianization'
1746 of it and therefore no revision indication is required.
1750 It is conventional to restart the
1751 <var>debian_revision</var> at <tt>1</tt> each time the
1752 <var>upstream_version</var> is increased.
1756 The package management system will break the version
1757 number apart at the last hyphen in the string (if there
1758 is one) to determine the <var>upstream_version</var> and
1759 <var>debian_revision</var>. The absence of a
1760 <var>debian_revision</var> compares earlier than the
1761 presence of one (but note that the
1762 <var>debian_revision</var> is the least significant part
1763 of the version number).
1770 The <var>upstream_version</var> and <var>debian_revision</var>
1771 parts are compared by the package management system using the
1776 The strings are compared from left to right.
1780 First the initial part of each string consisting entirely of
1781 non-digit characters is determined. These two parts (one of
1782 which may be empty) are compared lexically. If a difference
1783 is found it is returned. The lexical comparison is a
1784 comparison of ASCII values modified so that all the letters
1785 sort earlier than all the non-letters.
1789 Then the initial part of the remainder of each string which
1790 consists entirely of digit characters is determined. The
1791 numerical values of these two parts are compared, and any
1792 difference found is returned as the result of the comparison.
1793 For these purposes an empty string (which can only occur at
1794 the end of one or both version strings being compared) counts
1799 These two steps (comparing and removing initial non-digit
1800 strings and initial digit strings) are repeated until a
1801 difference is found or both strings are exhausted.
1805 Note that the purpose of epochs is to allow us to leave behind
1806 mistakes in version numbering, and to cope with situations
1807 where the version numbering scheme changes. It is
1808 <em>not</em> intended to cope with version numbers containing
1809 strings of letters which the package management system cannot
1810 interpret (such as <tt>ALPHA</tt> or <tt>pre-</tt>), or with
1811 silly orderings (the author of this manual has heard of a
1812 package whose versions went <tt>1.1</tt>, <tt>1.2</tt>,
1813 <tt>1.3</tt>, <tt>1</tt>, <tt>2.1</tt>, <tt>2.2</tt>,
1814 <tt>2</tt> and so forth).
1818 If an upstream package has problematic version numbers they
1819 should be converted to a sane form for use in the
1820 <tt>Version</tt> field.
1824 <heading>Version numbers based on dates</heading>
1826 In general, Debian packages should use the same version
1827 numbers as the upstream sources.</p>
1830 However, in some cases where the upstream version number is
1831 based on a date (e.g., a development `snapshot' release) the
1832 package management system cannot handle these version
1833 numbers without epochs. For example, dpkg will consider
1834 `96May01' to be greater than `96Dec24'.</p>
1837 To prevent having to use epochs for every new upstream
1838 version, the version number should be changed to the
1839 following format in such cases: `19960501', `19961224'. It
1840 is up to the maintainer whether he/she wants to bother the
1841 upstream maintainer to change the version numbers upstream,
1845 Note that other version formats based on dates which are
1846 parsed correctly by the package management system should
1847 <em>not</em> be changed.</p>
1850 Native Debian packages (i.e., packages which have been
1851 written especially for Debian) whose version numbers include
1852 dates should always use the `YYYYMMDD' format.</p>
1856 <chapt id="miscellaneous"><heading>Packaging Considerations</heading>
1858 <sect id="timestamps"><heading>Time Stamps</heading>
1860 Maintainers should preserve the modification times of the
1861 upstream source files in a package, as far as is reasonably
1864 The rationale is that there is some information conveyed
1865 by knowing the age of the file, for example, you could
1866 recognize that some documentation is very old by looking
1867 at the modification time, so it would be nice if the
1868 modification time of the upstream source would be
1875 <sect id="debianrules"><heading><tt>debian/rules</tt> - the
1876 main building script</heading>
1879 This file must be an executable makefile, and contains the
1880 package-specific recipes for compiling the package and
1881 building binary package(s) from the source.
1885 It must start with the line <tt>#!/usr/bin/make -f</tt>,
1886 so that it can be invoked by saying its name rather than
1887 invoking <prgn>make</prgn> explicitly.
1891 Since an interactive <tt>debian/rules</tt> script makes it
1892 impossible to auto-compile that package and also makes it
1893 hard for other people to reproduce the same binary
1894 package, all <em>required targets</em> MUST be
1895 non-interactive. At a minimum, required targets are the
1896 ones called by <prgn>dpkg-buildpackage</prgn>, namely,
1897 <em>clean</em>, <em>binary</em>, <em>binary-arch</em>,
1898 <em>binary-indep</em>, and <em>build</em>. It also follows
1899 that any target that these targets depend on must also be
1904 The required and optional targets are as follows:
1906 <tag><tt>build</tt>, <tt>build-arch</tt> (optional),
1907 <tt>build-indep</tt> (optional)</tag>
1910 The <tt>build</tt> target should perform all
1911 non-interactive configuration and compilation of the
1912 package. If a package has an interactive pre-build
1913 configuration routine, the Debianized source package
1914 must either be built after this has taken place (so
1915 that the binary package can be built without rerunning
1916 the configuration) or the configuration routine
1917 modified to become non-interactive. (The latter is
1918 preferable if there are architecture-specific features
1919 detected by the configuration routine.)
1923 For some packages, notably ones where the same
1924 source tree is compiled in different ways to produce
1925 two binary packages, the <tt>build</tt> target
1926 does not make much sense. For these packages it is
1927 good enough to provide two (or more) targets
1928 (<tt>build-a</tt> and <tt>build-b</tt> or whatever)
1929 for each of the ways of building the package, and a
1930 <tt>build</tt> target that does nothing. The
1931 <tt>binary</tt> target will have to build the
1932 package in each of the possible ways and make the
1933 binary package out of each.
1937 The <tt>build</tt> target must not do anything
1938 that might require root privilege.
1942 The <tt>build</tt> target may need to run the
1943 <tt>clean</tt> target first - see below.
1947 When a package has a configuration and build routine
1948 which takes a long time, or when the makefiles are
1949 poorly designed, or when <tt>build</tt> needs to
1950 run <tt>clean</tt> first, it is a good idea to
1951 <tt>touch build</tt> when the build process is
1952 complete. This will ensure that if <tt>debian/rules
1953 build</tt> is run again it will not rebuild the whole
1956 Another common way to do this is for <tt>build</tt>
1957 to depend on <prgn>build-stamp</prgn> and to do
1958 nothing else, and for the <prgn>build-stamp</prgn>
1959 target to do the building and to <tt>touch
1960 build-stamp</tt> on completion. This is
1961 especially useful if the build routine creates a
1962 file or directory called <tt>build</tt>; in such a
1963 case, <tt>build</tt> will need to be listed as
1964 a phony target (i.e., as a dependency of the
1965 <tt>.PHONY</tt> target). See the documentation of
1966 <prgn>make</prgn> for more information on phony
1973 <tag><tt>binary</tt>, <tt>binary-arch</tt>,
1974 <tt>binary-indep</tt>
1978 The <tt>binary</tt> target must be all that is
1979 necessary for the user to build the binary package(s)
1980 produced from this source package. All of these
1981 targets are required to be non-interactive. It is
1982 split into two parts: <prgn>binary-arch</prgn> builds
1983 the binary packages which are specific to a particular
1984 architecture, and <tt>binary-indep</tt> builds
1985 those which are not.
1988 <tt>binary</tt> may be (and commonly is) a target with
1989 no commands which simply depends on
1990 <tt>binary-arch</tt> and <tt>binary-indep</tt>.
1993 Both <tt>binary-*</tt> targets should depend on the
1994 <tt>build</tt> target, or on the appropriate
1995 <tt>build-arch</tt> or <tt>build-indep</tt> target, if
1996 provided, so that the package is built if it has not
1997 been already. It should then create the relevant
1998 binary package(s), using <tt>dpkg-gencontrol</tt> to
1999 make their control files and <tt>dpkg-deb</tt> to
2000 build them and place them in the parent of the top
2005 Both the <tt>binary-arch</tt> and
2006 <tt>binary-indep</tt> targets <em>must</em> exist.
2007 If one of them has nothing to do (which will always be
2008 the case if the source generates only a single binary
2009 package, whether architecture-dependent or not), it
2010 must still exist and must always succeed.
2014 The <tt>binary</tt> targets must be invoked as
2017 The <prgn>fakeroot</prgn> package often allows one
2018 to build a package correctly even without being
2025 <tag><tt>clean</tt></tag>
2028 This must undo any effects that the <tt>build</tt>
2029 and <tt>binary</tt> targets may have had, except
2030 that it should leave alone any output files created in
2031 the parent directory by a run of a <tt>binary</tt>
2032 target. This target must be non-interactive.
2036 If a <tt>build</tt> file is touched at the end of
2037 the <tt>build</tt> target, as suggested above, it
2038 should be removed as the first action that
2039 <tt>clean</tt> performs, so that running
2040 <tt>build</tt> again after an interrupted
2041 <tt>clean</tt> doesn't think that everything is
2046 The <tt>clean</tt> target may need to be
2047 invoked as root if <tt>binary</tt> has been
2048 invoked since the last <tt>clean</tt>, or if
2049 <tt>build</tt> has been invoked as root (since
2050 <tt>build</tt> may create directories, for
2055 <tag><tt>get-orig-source</tt> (optional)</tag>
2058 This target fetches the most recent version of the
2059 original source package from a canonical archive site
2060 (via FTP or WWW, for example), does any necessary
2061 rearrangement to turn it into the original source
2062 tar file format described below, and leaves it in the
2067 This target may be invoked in any directory, and
2068 should take care to clean up any temporary files it
2073 This target is optional, but providing it if
2074 possible is a good idea.
2080 The <tt>build</tt>, <tt>binary</tt> and
2081 <tt>clean</tt> targets must be invoked with the current
2082 directory being the package's top-level directory.
2087 Additional targets may exist in <tt>debian/rules</tt>,
2088 either as published or undocumented interfaces or for the
2089 package's internal use.
2093 The architectures we build on and build for are determined
2094 by <prgn>make</prgn> variables using the utility
2095 <prgn>dpkg-architecture</prgn>. You can determine the
2096 Debian architecture and the GNU style architecture
2097 specification string for the build machine (the machine type
2098 we are building on) as well as for the host machine (the
2099 machine type we are building for). Here is a list of
2100 supported <prgn>make</prgn> variables:
2101 <list compact="compact">
2103 <p><tt>DEB_*_ARCH</tt> (the Debian architecture)</p>
2106 <p><tt>DEB_*_GNU_TYPE</tt> (the GNU style architecture
2107 specification string)</p>
2110 <p><tt>DEB_*_GNU_CPU</tt> (the CPU part of
2111 <tt>DEB_*_GNU_TYPE</tt>)</p>
2114 <p><tt>DEB_*_GNU_SYSTEM</tt> (the System part of
2115 <tt>DEB_*_GNU_TYPE</tt>)</p>
2117 where <tt>*</tt> is either <tt>BUILD</tt> for specification of
2118 the build machine or <tt>HOST</tt> for specification of the
2123 Backward compatibility can be provided in the rules file
2124 by setting the needed variables to suitable default
2125 values; please refer to the documentation of
2126 <prgn>dpkg-architecture</prgn> for details.
2130 It is important to understand that the <tt>DEB_*_ARCH</tt>
2131 string only determines which Debian architecture we are
2132 building on or for. It should not be used to get the CPU
2133 or system information; the GNU style variables should be
2138 <sect id="dpkgchangelog"><heading><tt>debian/changelog</tt>
2142 This file records the changes to the Debian-specific parts of the
2145 Though there is nothing stopping an author who is also
2146 the Debian maintainer from using it for all their
2147 changes, it will have to be renamed if the Debian and
2148 upstream maintainers become different people. In such a
2149 case, however, it might be better to maintain the
2150 package as a non-native package.
2156 It has a special format which allows the package building
2157 tools to discover which version of the package is being
2158 built and find out other release-specific information.
2162 That format is a series of entries like this:
2163 <example compact="compact">
2164 <var>package</var> (<var>version</var>) <var>distribution(s)</var>; urgency=<var>urgency</var>
2166 <p>[optional blank line(s), stripped]</p>
2168 * <var>change details</var>
2169 <var>more change details</var>
2171 <p>[blank line(s), included in output of dpkg-parsechangelog]</p>
2173 * <var>even more change details</var>
2175 <p>[optional blank line(s), stripped]</p>
2177 -- <var>maintainer name</var> <<var>email
2178 address</var>><var>[two spaces]</var> <var>date</var>
2183 <var>package</var> and <var>version</var> are the source
2184 package name and version number.
2188 <var>distribution(s)</var> lists the distributions where
2189 this version should be installed when it is uploaded - it
2190 is copied to the <tt>Distribution</tt> field in the
2191 <tt>.changes</tt> file. See <ref id="f-Distribution">.
2195 <var>urgency</var> is the value for the <tt>Urgency</tt>
2196 field in the <tt>.changes</tt> file for the upload. It is
2197 not possible to specify an urgency containing commas; commas
2198 are used to separate
2199 <tt><var>keyword</var>=<var>value</var></tt> settings in the
2200 <prgn>dpkg</prgn> changelog format (though there is
2201 currently only one useful <var>keyword</var>,
2202 <tt>urgency</tt>).<footnote>
2204 Recognised urgency values are <tt>low</tt>,
2205 <tt>medium</tt>, <tt>high</tt> and <tt>emergency</tt>.
2206 They have an effect on how quickly a package will be
2207 considered for inclusion into the <tt>testing</tt>
2208 distribution, and give an indication of the importance
2209 of any fixes included in this upload.
2215 The change details may in fact be any series of lines
2216 starting with at least two spaces, but conventionally each
2217 change starts with an asterisk and a separating space and
2218 continuation lines are indented so as to bring them in
2219 line with the start of the text above. Blank lines may be
2220 used here to separate groups of changes, if desired.
2224 If this upload resolves bugs recorded in the Bug Tracking
2225 System (BTS), they may be automatically closed on the
2226 inclusion of this package into the Debian archive by
2227 including the string: <tt>closes: Bug#<var>nnnnn</var></tt>
2228 in the change details.<footnote>
2230 To be precise, the string should match the following
2231 Perl regular expression:
2233 /closes:\s*(?:bug)?\#?\s?\d+(?:,\s*(?:bug)?\#?\s?\d+)*/i
2235 Then all of the bug numbers listed will be closed by the
2236 archive maintenance script (<prgn>katie</prgn>), or in
2237 the case of an NMU, marked as fixed.
2243 The maintainer name and email address used in the changelog
2244 should be the details of the person uploading <em>this</em>
2245 version. They are <em>not</em> necessarily those of the
2246 usual package maintainer. The information here will be
2247 copied to the <tt>Changed-By</tt> field in the
2248 <tt>.changes</tt> file, and then later used to send an
2249 acknowledgement when the upload has been installed.
2253 The <var>date</var> should be in RFC822 format<footnote>
2255 This is generated by the <prgn>822-date</prgn>
2258 </footnote>; it should include the time zone specified
2259 numerically, with the time zone name or abbreviation
2260 optionally present as a comment in parentheses.
2264 The first `title' line with the package name should start
2265 at the left hand margin; the `trailer' line with the
2266 maintainer and date details should be preceded by exactly
2267 one space. The maintainer details and the date must be
2268 separated by exactly two spaces.
2271 <sect1><heading>Defining alternative changelog formats</heading>
2274 It is possible to use a different format to the standard
2275 one, by providing a parser for the format you wish to
2279 A changelog parser must not interact with the user at
2285 <sect id="srcsubstvars"><heading><tt>debian/substvars</tt>
2286 and variable substitutions </heading>
2289 When <prgn>dpkg-gencontrol</prgn>,
2290 <prgn>dpkg-genchanges</prgn> and <prgn>dpkg-source</prgn>
2291 generate control files they perform variable substitutions
2292 on their output just before writing it. Variable
2293 substitutions have the form <tt>${<var>variable</var>}</tt>.
2294 The optional file <tt>debian/substvars</tt> contains
2295 variable substitutions to be used; variables can also be set
2296 directly from <tt>debian/rules</tt> using the <tt>-V</tt>
2297 option to the source packaging commands, and certain
2298 predefined variables are also available.
2302 The <tt>debian/substvars</tt> file is usually generated and
2303 modified dynamically by <tt>debian/rules</tt> targets; in
2304 this case it must be removed by the <tt>clean</tt>
2309 See <manref name="dpkg-source" section="1"> for full
2310 details about source variable substitutions, including the
2311 format of <tt>debian/substvars</tt>.</p>
2314 <sect id="debianfiles"><heading><tt>debian/files</tt>
2318 This file is not a permanent part of the source tree; it
2319 is used while building packages to record which files are
2320 being generated. <prgn>dpkg-genchanges</prgn> uses it
2321 when it generates a <tt>.changes</tt> file.
2325 It should not exist in a shipped source package, and so it
2326 (and any backup files or temporary files such as
2327 <tt>files.new</tt><footnote>
2329 <tt>files.new</tt> is used as a temporary file by
2330 <prgn>dpkg-gencontrol</prgn> and
2331 <prgn>dpkg-distaddfile</prgn> - they write a new
2332 version of <tt>files</tt> here before renaming it,
2333 to avoid leaving a corrupted copy if an error
2336 </footnote>) should be removed by the
2337 <tt>clean</tt> target. It may also be wise to
2338 ensure a fresh start by emptying or removing it at the
2339 start of the <tt>binary</tt> target.
2343 When <prgn>dpkg-gencontrol</prgn> is run for a binary
2344 package, it adds an entry to <tt>debian/files</tt> for the
2345 <tt>.deb</tt> file that will be created when <tt>dpkg-deb
2346 --build</tt> is run for that binary package. So for most
2347 packages all that needs to be done with this file is to
2348 delete it in the <tt>clean</tt> target.
2352 If a package upload includes files besides the source
2353 package and any binary packages whose control files were
2354 made with <prgn>dpkg-gencontrol</prgn> then they should be
2355 placed in the parent of the package's top-level directory
2356 and <prgn>dpkg-distaddfile</prgn> should be called to add
2357 the file to the list in <tt>debian/files</tt>.</p>
2360 <sect id="restrictions"><heading>Restrictions on objects in source packages
2364 The source package may not contain any hard links<footnote>
2366 This is not currently detected when building source
2367 packages, but only when extracting
2371 Hard links may be permitted at some point in the
2372 future, but would require a fair amount of
2375 </footnote>, device special files, sockets or setuid or
2376 setgid files.<footnote>
2378 Setgid directories are allowed.
2383 <sect id="descriptions"><heading>Descriptions of packages - the
2384 <tt>Description</tt> field </heading>
2387 The description is intended to describe the program to a user
2388 who has never met it before so that they know whether they
2389 want to install it. It should also give information about the
2390 significant dependencies and conflicts between this package
2391 and others, so that the user knows why these dependencies and
2392 conflicts have been declared.
2395 <sect1><heading>Notes about writing descriptions
2399 The single line synopsis should be kept brief - certainly
2400 under 80 characters.
2404 Do not include the package name in the synopsis line. The
2405 display software knows how to display this already, and you
2406 do not need to state it. Remember that in many situations
2407 the user may only see the synopsis line - make it as
2408 informative as you can.
2412 Do not try to continue the single line synopsis into the
2413 extended description. This will not work correctly when
2414 the full description is displayed, and makes no sense
2415 where only the summary (the single line synopsis) is
2420 The extended description should describe what the package
2421 does and how it relates to the rest of the system (in terms
2422 of, for example, which subsystem it is which part of).
2426 The description field needs to make sense to anyone, even
2427 people who have no idea about any of the things the
2428 package deals with.<footnote>
2430 The blurb that comes with a program in its
2431 announcements and/or <prgn>README</prgn> files is
2432 rarely suitable for use in a description. It is
2433 usually aimed at people who are already in the
2434 community where the package is used.
2440 Put important information first, both in the synopsis and
2441 extended description. Sometimes only the first part of the
2442 synopsis or of the description will be displayed. You can
2443 assume that there will usually be a way to see the whole
2444 extended description.
2448 You may include information about dependencies and so forth
2449 in the extended description, if you wish.
2453 Do not use tab characters. Their effect is not predictable.
2461 <chapt id="maintainerscripts"><heading>Package maintainer scripts
2462 and installation procedure
2465 <sect><heading>Introduction to package maintainer scripts
2469 It is possible to supply scripts as part of a package which
2470 the package management system will run for you when your
2471 package is installed, upgraded or removed.
2475 These scripts are the files <prgn>preinst</prgn>,
2476 <prgn>postinst</prgn>, <prgn>prerm</prgn> and <prgn>postrm</prgn> in the
2477 control area of the package. They must be proper executable
2478 files; if they are scripts (which is recommended), they must
2479 start with the usual <tt>#!</tt> convention. They should be
2480 readable and executable by anyone, and not world-writable.
2484 The package management system looks at the exit status from
2485 these scripts. It is important that they exit with a
2486 non-zero status if there is an error, so that the package
2487 management system can stop its processing. For shell
2488 scripts this means that you <em>almost always</em> need to
2489 use <tt>set -e</tt> (this is usually true when writing shell
2490 scripts, in fact). It is also important, of course, that
2491 they don't exit with a non-zero status if everything went
2496 When a package is upgraded a combination of the scripts from
2497 the old and new packages is called during the upgrade
2498 procedure. If your scripts are going to be at all
2499 complicated you need to be aware of this, and may need to
2500 check the arguments to your scripts.
2504 Broadly speaking the <prgn>preinst</prgn> is called before
2505 (a particular version of) a package is installed, and the
2506 <prgn>postinst</prgn> afterwards; the <prgn>prerm</prgn>
2507 before (a version of) a package is removed and the
2508 <prgn>postrm</prgn> afterwards.
2512 Programs called from maintainer scripts should not normally
2513 have a path prepended to them. Before installation is
2514 started, the package management system checks to see if the
2515 programs <prgn>ldconfig</prgn>,
2516 <prgn>start-stop-daemon</prgn>, <prgn>install-info</prgn>,
2517 and <prgn>update-rc.d</prgn> can be found via the
2518 <tt>PATH</tt> environment variable. Those programs, and any
2519 other program that one would expect to be on the
2520 <tt>PATH</tt>, should thus be invoked without an absolute
2521 pathname. Maintainer scripts should also not reset the
2522 <tt>PATH</tt>, though they might choose to modify it by
2523 prepending or appending package-specific directories. These
2524 considerations really apply to all shell scripts.</p>
2528 <heading>Maintainer scripts Idempotency</heading>
2531 It is necessary for the error recovery procedures that the
2532 scripts be idempotent. This means that if it is run
2533 successfully, and then it is called again, it doesn't bomb
2534 out or cause any harm, but just ensures that everything is
2535 the way it ought to be. If the first call failed, or
2536 aborted half way through for some reason, the second call
2537 should merely do the things that were left undone the first
2538 time, if any, and exit with a success status if everything
2541 This is so that if an error occurs, the user interrupts
2542 <prgn>dpkg</prgn> or some other unforeseen circumstance
2543 happens you don't leave the user with a badly-broken
2544 package when <prgn>dpkg</prgn> attempts to repeat the
2552 <heading>Controlling terminal for maintainer scripts</heading>
2555 The maintainer scripts are guaranteed to run with a
2556 controlling terminal and can interact with the user.
2557 If they need to prompt for passwords, do full-screen
2558 interaction or something similar you should do these
2559 things to and from <tt>/dev/tty</tt>, since
2560 <prgn>dpkg</prgn> will at some point redirect scripts'
2561 standard input and output so that it can log the
2562 installation process. Likewise, because these scripts
2563 may be executed with standard output redirected into a
2564 pipe for logging purposes, Perl scripts should set
2565 unbuffered output by setting <tt>$|=1</tt> so that the
2566 output is printed immediately rather than being
2571 Each script should return a zero exit status for
2572 success, or a nonzero one for failure.
2576 <sect id="mscriptsinstact"><heading>Summary of ways maintainer
2581 <list compact="compact">
2583 <p><var>new-preinst</var> <tt>install</tt></p>
2586 <p><var>new-preinst</var> <tt>install</tt>
2587 <var>old-version</var></p>
2590 <p><var>new-preinst</var> <tt>upgrade</tt>
2591 <var>old-version</var></p>
2594 <p><var>old-preinst</var> <tt>abort-upgrade</tt>
2595 <var>new-version</var>
2601 <list compact="compact">
2603 <p><var>postinst</var> <tt>configure</tt>
2604 <var>most-recently-configured-version</var></p>
2607 <p><var>old-postinst</var> <tt>abort-upgrade</tt>
2608 <var>new-version</var></p>
2611 <p><var>conflictor's-postinst</var> <tt>abort-remove</tt>
2612 <tt>in-favour</tt> <var>package</var>
2613 <var>new-version</var></p>
2617 <var>deconfigured's-postinst</var>
2618 <tt>abort-deconfigure</tt> <tt>in-favour</tt>
2619 <var>failed-install-package</var> <var>version</var>
2620 <tt>removing</tt> <var>conflicting-package</var>
2627 <list compact="compact">
2629 <p><var>prerm</var> <tt>remove</tt></p>
2632 <p><var>old-prerm</var> <tt>upgrade</tt>
2633 <var>new-version</var></p>
2636 <p><var>new-prerm</var> <tt>failed-upgrade</tt>
2637 <var>old-version</var></p>
2640 <p><var>conflictor's-prerm</var> <tt>remove</tt>
2641 <tt>in-favour</tt> <var>package</var>
2642 <var>new-version</var></p>
2646 <var>deconfigured's-prerm</var> <tt>deconfigure</tt>
2647 <tt>in-favour</tt> <var>package-being-installed</var>
2648 <var>version</var> <tt>removing</tt>
2649 <var>conflicting-package</var>
2656 <list compact="compact">
2658 <p><var>postrm</var> <tt>remove</tt></p>
2661 <p><var>postrm</var> <tt>purge</tt></p>
2665 <var>old-postrm</var> <tt>upgrade</tt>
2666 <var>new-version</var></p>
2669 <p><var>new-postrm</var> <tt>failed-upgrade</tt>
2670 <var>old-version</var></p>
2673 <p><var>new-postrm</var> <tt>abort-install</tt></p>
2676 <p><var>new-postrm</var> <tt>abort-install</tt>
2677 <var>old-version</var></p>
2680 <p><var>new-postrm</var> <tt>abort-upgrade</tt>
2681 <var>old-version</var></p>
2685 <var>disappearer's-postrm</var> <tt>disappear</tt>
2686 <var>overwriter</var>
2687 <var>overwriter-version</var></p></item>
2692 <sect id="unpackphase"><heading>Details of unpack phase of
2693 installation or upgrade
2697 The procedure on installation/upgrade/overwrite/disappear
2698 (i.e., when running <tt>dpkg --unpack</tt>, or the unpack
2699 stage of <tt>dpkg --install</tt>) is as follows. In each
2700 case, if a major error occurs (unless listed below) the
2701 actions are, in general, run backwards - this means that the
2702 maintainer scripts are run with different arguments in
2703 reverse order. These are the `error unwind' calls listed
2711 <p>If a version of the package is already
2713 <example compact="compact">
2714 <var>old-prerm</var> upgrade <var>new-version</var>
2719 If the script runs but exits with a non-zero
2720 exit status, <prgn>dpkg</prgn> will attempt:
2721 <example compact="compact">
2722 <var>new-prerm</var> failed-upgrade <var>old-version</var>
2724 Error unwind, for both the above cases:
2725 <example compact="compact">
2726 <var>old-postinst</var> abort-upgrade <var>new-version</var>
2734 <p>If a `conflicting' package is being removed at the same time:
2738 If any packages depended on that conflicting
2739 package and <tt>--auto-deconfigure</tt> is
2740 specified, call, for each such package:
2741 <example compact="compact">
2742 <var>deconfigured's-prerm</var> deconfigure \
2743 in-favour <var>package-being-installed</var> <var>version</var> \
2744 removing <var>conflicting-package</var> <var>version</var>
2747 <example compact="compact">
2748 <var>deconfigured's-postinst</var> abort-deconfigure \
2749 in-favour <var>package-being-installed-but-failed</var> <var>version</var> \
2750 removing <var>conflicting-package</var> <var>version</var>
2752 The deconfigured packages are marked as
2753 requiring configuration, so that if
2754 <tt>--install</tt> is used they will be
2755 configured again if possible.</p>
2758 <p>To prepare for removal of the conflicting package, call:
2759 <example compact="compact">
2760 <var>conflictor's-prerm</var> remove \
2761 in-favour <var>package</var> <var>new-version</var>
2764 <example compact="compact">
2765 <var>conflictor's-postinst</var> abort-remove \
2766 in-favour <var>package</var> <var>new-version</var>
2777 <p>If the package is being upgraded, call:
2778 <example compact="compact">
2779 <var>new-preinst</var> upgrade <var>old-version</var>
2784 Otherwise, if the package had some configuration
2785 files from a previous version installed (i.e., it
2786 is in the `configuration files only' state):
2787 <example compact="compact">
2788 <var>new-preinst</var> install <var>old-version</var>
2792 <p>Otherwise (i.e., the package was completely purged):
2793 <example compact="compact">
2794 <var>new-preinst</var> install
2796 Error unwind actions, respectively:
2797 <example compact="compact">
2798 <var>new-postrm</var> abort-upgrade <var>old-version</var>
2799 <var>new-postrm</var> abort-install <var>old-version</var>
2800 <var>new-postrm</var> abort-install
2809 The new package's files are unpacked, overwriting any
2810 that may be on the system already, for example any
2811 from the old version of the same package or from
2812 another package. Backups of the old files are kept
2813 temporarily, and if anything goes wrong the package
2814 management system will attempt to put them back as
2815 part of the error unwind.
2819 It is an error for a package to contains files which
2820 are on the system in another package, unless
2821 <tt>Replaces</tt> is used (see <ref id="replaces">).
2823 The following paragraph is not currently the case:
2824 Currently the <tt>- - force-overwrite</tt> flag is
2825 enabled, downgrading it to a warning, but this may not
2831 It is a more serious error for a package to contain a
2832 plain file or other kind of non-directory where another
2833 package has a directory (again, unless
2834 <tt>Replaces</tt> is used). This error can be
2835 overridden if desired using
2836 <tt>--force-overwrite-dir</tt>, but this is not
2841 Packages which overwrite each other's files produce
2842 behavior which, though deterministic, is hard for the
2843 system administrator to understand. It can easily
2844 lead to `missing' programs if, for example, a package
2845 is installed which overwrites a file from another
2846 package, and is then removed again.<footnote>
2848 Part of the problem is due to what is arguably a
2849 bug in <prgn>dpkg</prgn>.
2855 A directory will never be replaced by a symbolic link
2856 to a directory or vice versa; instead, the existing
2857 state (symlink or not) will be left alone and
2858 <prgn>dpkg</prgn> will follow the symlink if there is
2866 <p>If the package is being upgraded, call
2867 <example compact="compact">
2868 <var>old-postrm</var> upgrade <var>new-version</var>
2873 <p>If this fails, <prgn>dpkg</prgn> will attempt:
2874 <example compact="compact">
2875 <var>new-postrm</var> failed-upgrade <var>old-version</var>
2877 Error unwind, for both cases:
2878 <example compact="compact">
2879 <var>old-preinst</var> abort-upgrade <var>new-version</var>
2886 This is the point of no return - if
2887 <prgn>dpkg</prgn> gets this far, it won't back off
2888 past this point if an error occurs. This will
2889 leave the package in a fairly bad state, which
2890 will require a successful re-installation to clear
2891 up, but it's when <prgn>dpkg</prgn> starts doing
2892 things that are irreversible.
2897 Any files which were in the old version of the package
2898 but not in the new are removed.</p>
2901 <p>The new file list replaces the old.</p>
2904 <p>The new maintainer scripts replace the old.</p>
2908 <p>Any packages all of whose files have been overwritten during the
2909 installation, and which aren't required for
2910 dependencies, are considered to have been removed.
2911 For each such package
2914 <p><prgn>dpkg</prgn> calls:
2915 <example compact="compact">
2916 <var>disappearer's-postrm</var> disappear \
2917 <var>overwriter</var> <var>overwriter-version</var>
2922 <p>The package's maintainer scripts are removed.
2927 It is noted in the status database as being in a
2928 sane state, namely not installed (any conffiles
2929 it may have are ignored, rather than being
2930 removed by <prgn>dpkg</prgn>). Note that
2931 disappearing packages do not have their prerm
2932 called, because <prgn>dpkg</prgn> doesn't know
2933 in advance that the package is going to
2942 Any files in the package we're unpacking that are also
2943 listed in the file lists of other packages are removed
2944 from those lists. (This will lobotomize the file list
2945 of the `conflicting' package if there is one.)
2950 The backup files made during installation, above, are
2957 The new package's status is now sane, and recorded as
2962 Here is another point of no return - if the
2963 conflicting package's removal fails we do not unwind
2964 the rest of the installation; the conflicting package
2965 is left in a half-removed limbo.
2971 If there was a conflicting package we go and do the
2972 removal actions (described below), starting with the
2973 removal of the conflicting package's files (any that
2974 are also in the package being installed have already
2975 been removed from the conflicting package's file list,
2976 and so do not get removed now).
2983 <sect id="configdetails"><heading>Details of configuration</heading>
2986 When we configure a package (this happens with <tt>dpkg
2987 --install</tt> and <tt>dpkg --configure</tt>), we first
2988 update any <tt>conffile</tt>s and then call:
2989 <example compact="compact">
2990 <var>postinst</var> configure <var>most-recently-configured-version</var>
2995 No attempt is made to unwind after errors during
3000 If there is no most recently configured version
3001 <prgn>dpkg</prgn> will pass a null argument; older versions
3002 of dpkg may pass <tt><unknown></tt> (including the
3003 angle brackets) in this case. Even older ones do not pass a
3004 second argument at all, under any circumstances.
3008 <sect id="removedetails"><heading>Details of removal and/or
3009 configuration purging</heading>
3015 <example compact="compact">
3016 <var>prerm</var> remove
3022 The package's files are removed (except <tt>conffile</tt>s).
3027 <example compact="compact">
3028 <var>postrm</var> remove
3034 All the maintainer scripts except the <prgn>postrm</prgn>
3039 If we aren't purging the package we stop here. Note
3040 that packages which have no <prgn>postrm</prgn> and no
3041 <tt>conffile</tt>s are automatically purged when
3042 removed, as there is no difference except for the
3043 <prgn>dpkg</prgn> status.</p>
3047 The <tt>conffile</tt>s and any backup files
3048 (<tt>~</tt>-files, <tt>#*#</tt> files,
3049 <tt>%</tt>-files, <tt>.dpkg-{old,new,tmp}</tt>, etc.)
3054 <example compact="compact">
3055 <var>postrm</var> purge
3060 <p>The package's file list is removed.</p>
3063 No attempt is made to unwind after errors during
3070 <chapt id="relationships"><heading>Declaring relationships between
3074 Packages can declare in their control file that they have
3075 certain relationships to other packages - for example, that
3076 they may not be installed at the same time as certain other
3077 packages, and/or that they depend on the presence of others,
3078 or that they should overwrite files in certain other packages
3083 This is done using the <tt>Depends</tt>, <tt>Pre-Depends</tt>,
3084 <tt>Recommends</tt>, <tt>Suggests</tt>, <tt>Enhances</tt>,
3085 <tt>Conflicts</tt>, <tt>Provides</tt> and <tt>Replaces</tt>
3086 control file fields.
3090 Source packages may declare relationships to binary packages,
3091 saying that they require certain binary packages to be
3092 installed or absent at the time of building the package.
3096 This is done using the <tt>Build-Depends</tt>,
3097 <tt>Build-Depends-Indep</tt>, <tt>Build-Conflicts</tt> and
3098 <tt>Build-Conflicts-Indep</tt> control file fields.
3101 <sect id="depsyntax"><heading>Syntax of relationship fields
3105 These fields all have a uniform syntax. They are a list of
3106 package names separated by commas.
3110 In the <tt>Depends</tt>, <tt>Recommends</tt>,
3111 <tt>Suggests</tt>, <tt>Pre-Depends</tt>,
3112 <tt>Build-Depends</tt> and <tt>Build-Depends-Indep</tt>
3113 control file fields of the package, which declare
3114 dependencies on other packages, the package names listed may
3115 also include lists of alternative package names, separated
3116 by vertical bar (pipe) symbols <tt>|</tt>. In such a case,
3117 if any one of the alternative packages is installed, that
3118 part of the dependency is considered to be satisfied.
3122 All of the fields except for <tt>Provides</tt> may restrict
3123 their applicability to particular versions of each named
3124 package. This is done in parentheses after each individual
3125 package name; the parentheses should contain a relation from
3126 the list below followed by a version number, in the format
3127 described in <ref id="versions">.
3131 The relations allowed are <tt><<</tt>, <tt><=</tt>,
3132 <tt>=</tt>, <tt>>=</tt> and <tt>>></tt> for
3133 strictly earlier, earlier or equal, exactly equal, later or
3134 equal and strictly later, respectively. The deprecated
3135 forms <tt><</tt> and <tt>></tt> were used to mean
3136 earlier/later or equal, rather than strictly earlier/later,
3137 so they should not appear in new packages (though
3138 <prgn>dpkg</prgn> still supports them).
3142 Whitespace may appear at any point in the version
3143 specification subject to the rules in <ref
3144 id="controlsyntax">, and must appear where it's necessary to
3145 disambiguate; it is not otherwise significant. For
3146 consistency and in case of future changes to
3147 <prgn>dpkg</prgn> it is recommended that a single space be
3148 used after a version relationship and before a version
3149 number; it is also conventional to put a single space after
3150 each comma, on either side of each vertical bar, and before
3151 each open parenthesis.
3155 For example, a list of dependencies might appear as:
3156 <example compact="compact">
3159 Depends: libc6 (>= 2.2.1), exim | mail-transport-agent
3164 All fields that specify build-time relationships
3165 (<tt>Build-Depends</tt>, <tt>Build-Depends-Indep</tt>,
3166 <tt>Build-Conflicts</tt> and <tt>Build-Conflicts-Indep</tt>)
3167 may be restricted to a certain set of architectures. This
3168 is indicated in brackets after each individual package name and
3169 the optional version specification. The brackets enclose a
3170 list of Debian architecture names separated by whitespace.
3171 Exclamation marks may be prepended to each of the names.
3172 (It is not permitted for some names to be prepended with
3173 exclamation marks and others not.) If the current Debian
3174 host architecture is not in this list and there are no
3175 exclamation marks in the list, or it is in the list with a
3176 prepended exclamation mark, the package name and the
3177 associated version specification are ignored completely for
3178 the purposes of defining the relationships.
3183 <example compact="compact">
3185 Build-Depends-Indep: texinfo
3186 Build-Depends: kernel-headers-2.2.10 [!hurd-i386],
3187 hurd-dev [hurd-i386], gnumach-dev [hurd-i386]
3192 Note that the binary package relationship fields such as
3193 <tt>Depends</tt> appear in one of the binary package
3194 sections of the control file, whereas the build-time
3195 relationships such as <tt>Build-Depends</tt> appear in the
3196 source package section of the control file (which is the
3202 <heading>Binary Dependencies - <tt>Depends</tt>,
3203 <tt>Recommends</tt>, <tt>Suggests</tt>, <tt>Enhances</tt>,
3204 <tt>Pre-Depends</tt>
3208 These five fields are used to declare a dependency
3209 relationship by one package on another. Except for
3210 <tt>Enhances</tt>, they appear in the depending (binary)
3211 package's control file. (<tt>Enhances</tt> appears in the
3212 recommending package's control file.)
3216 A <tt>Depends</tt> field takes effect <em>only</em> when a
3217 package is to be configured. It does not prevent a package
3218 being on the system in an unconfigured state while its
3219 dependencies are unsatisfied, and it is possible to replace
3220 a package whose dependencies are satisfied and which is
3221 properly installed with a different version whose
3222 dependencies are not and cannot be satisfied; when this is
3223 done the depending package will be left unconfigured (since
3224 attempts to configure it will give errors) and will not
3225 function properly. If it is necessary, a
3226 <tt>Pre-Depends</tt> field can be used, which has a partial
3227 effect even when a package is being unpacked, as explained
3228 in detail below. (The other three dependency fields,
3229 <tt>Recommends</tt>, <tt>Suggests</tt> and
3230 <tt>Enhances</tt>, are only used by the various front-ends
3231 to <prgn>dpkg</prgn> such as <prgn>dselect</prgn>.)
3235 For this reason packages in an installation run are usually
3236 all unpacked first and all configured later; this gives
3237 later versions of packages with dependencies on later
3238 versions of other packages the opportunity to have their
3239 dependencies satisfied.
3243 The <tt>Depends</tt> field thus allows package maintainers
3244 to impose an order in which packages should be configured.
3248 The meaning of the five dependency fields is as follows:
3250 <tag><tt>Depends</tt></tag>
3253 This declares an absolute dependency. A package will
3254 not be configured unless all of the packages listed in
3255 its <tt>Depends</tt> field have been correctly
3260 The <tt>Depends</tt> field should be used if the
3261 depended-on package is required for the depending
3262 package to provide a significant amount of
3266 The <tt>Depends</tt> field should also be used if the
3267 <prgn>postinst</prgn>, <prgn>prerm</prgn> or
3268 <prgn>postrm</prgn> scripts require the package to be
3269 present in order to run. Note, however, that the
3270 <prgn>postrm</prgn> cannot rely on any non-essential
3271 packages to be present during the <tt>purge</tt>
3275 <tag><tt>Recommends</tt></tag>
3277 <p>This declares a strong, but not absolute, dependency.
3281 The <tt>Recommends</tt> field should list packages
3282 that would be found together with this one in all but
3283 unusual installations.</p>
3286 <tag><tt>Suggests</tt></tag>
3289 This is used to declare that one package may be more
3290 useful with one or more others. Using this field
3291 tells the packaging system and the user that the
3292 listed packages are related to this one and can
3293 perhaps enhance its usefulness, but that installing
3294 this one without them is perfectly reasonable.
3298 <tag><tt>Enhances</tt></tag>
3301 This field is similar to Suggests but works in the
3302 opposite direction. It is used to declare that a
3303 package can enhance the functionality of another
3308 <tag><tt>Pre-Depends</tt></tag>
3311 This field is like <tt>Depends</tt>, except that it
3312 also forces <prgn>dpkg</prgn> to complete installation
3313 of the packages named before even starting the
3314 installation of the package which declares the
3315 pre-dependency, as follows:
3319 When a package declaring a pre-dependency is about to
3320 be <em>unpacked</em> the pre-dependency can be
3321 satisfied if the depended-on package is either fully
3322 configured, <em>or even if</em> the depended-on
3323 package(s) are only unpacked or half-configured,
3324 provided that they have been configured correctly at
3325 some point in the past (and not removed or partially
3326 removed since). In this case, both the
3327 previously-configured and currently unpacked or
3328 half-configured versions must satisfy any version
3329 clause in the <tt>Pre-Depends</tt> field.
3333 When the package declaring a pre-dependency is about
3334 to be <em>configured</em>, the pre-dependency will be
3335 treated as a normal <tt>Depends</tt>, that is, it will
3336 be considered satisfied only if the depended-on
3337 package has been correctly configured.
3341 <tt>Pre-Depends</tt> should be used sparingly,
3342 preferably only by packages whose premature upgrade or
3343 installation would hamper the ability of the system to
3344 continue with any upgrade that might be in progress.
3348 <tt>Pre-Depends</tt> are also required if the
3349 <prgn>preinst</prgn> script depends on the named
3350 package. It is best to avoid this situation if
3356 When selecting which level of dependency to use you should
3357 consider how important the depended-on package is to the
3358 functionality of the one declaring the dependency. Some
3359 packages are composed of components of varying degrees of
3360 importance. Such a package should list using
3361 <tt>Depends</tt> the package(s) which are required by the
3362 more important components. The other components'
3363 requirements may be mentioned as Suggestions or
3364 Recommendations, as appropriate to the components' relative
3369 <sect id="conflicts"><heading>Conflicting binary packages -
3370 <tt>Conflicts</tt></heading>
3373 When one binary package declares a conflict with another
3374 using a <tt>Conflicts</tt> field, <prgn>dpkg</prgn> will
3375 refuse to allow them to be installed on the system at the
3380 If one package is to be installed, the other must be removed
3381 first - if the package being installed is marked as
3382 replacing (see <ref id="replaces">) the one on the system,
3383 or the one on the system is marked as deselected, or both
3384 packages are marked <tt>Essential</tt>, then
3385 <prgn>dpkg</prgn> will automatically remove the package
3386 which is causing the conflict, otherwise it will halt the
3387 installation of the new package with an error. This
3388 mechanism is specifically designed to produce an error when
3389 the installed package is <tt>Essential</tt>, but the new
3394 A package will not cause a conflict merely because its
3395 configuration files are still installed; it must be at least
3400 A special exception is made for packages which declare a
3401 conflict with their own package name, or with a virtual
3402 package which they provide (see below): this does not
3403 prevent their installation, and allows a package to conflict
3404 with others providing a replacement for it. You use this
3405 feature when you want the package in question to be the only
3406 package providing some feature.
3410 A <tt>Conflicts</tt> entry should almost never have an
3411 `earlier than' version clause. This would prevent
3412 <prgn>dpkg</prgn> from upgrading or installing the package
3413 which declared such a conflict until the upgrade or removal
3414 of the conflicted-with package had been completed.
3418 <sect id="virtual"><heading>Virtual packages - <tt>Provides</tt>
3422 As well as the names of actual (`concrete') packages, the
3423 package relationship fields <tt>Depends</tt>,
3424 <tt>Recommends</tt>, <tt>Suggests</tt>, <tt>Enhances</tt>,
3425 <tt>Pre-Depends</tt>, <tt>Conflicts</tt>,
3426 <tt>Build-Depends</tt>, <tt>Build-Depends-Indep</tt>,
3427 <tt>Build-Conflicts</tt> and <tt>Build-Conflicts-Indep</tt>
3428 may mention `virtual packages'.
3432 A <em>virtual package</em> is one which appears in the
3433 <tt>Provides</tt> control file field of another package.
3434 The effect is as if the package(s) which provide a
3435 particular virtual package name had been listed by name
3436 everywhere the virtual package name appears.
3440 If there are both a real and a virtual package of the same
3441 name then the dependency may be satisfied (or the conflict
3442 caused) by either the real package or any of the virtual
3443 packages which provide it. This is so that, for example,
3445 <example compact="compact">
3449 and someone else releases an enhanced version of the
3450 <tt>bar</tt> package (for example, a non-US variant), they
3452 <example compact="compact">
3456 and the <tt>bar-plus</tt> package will now also satisfy the
3457 dependency for the <tt>foo</tt> package.
3461 If a dependency or a conflict has a version number attached
3462 then only real packages will be considered to see whether
3463 the relationship is satisfied (or the prohibition violated,
3464 for a conflict) - it is assumed that a real package which
3465 provides the virtual package is not of the `right' version.
3466 So, a <tt>Provides</tt> field may not contain version
3467 numbers, and the version number of the concrete package
3468 which provides a particular virtual package will not be
3469 looked at when considering a dependency on or conflict with
3470 the virtual package name.
3474 It is likely that the ability will be added in a future
3475 release of <prgn>dpkg</prgn> to specify a version number for
3476 each virtual package it provides. This feature is not yet
3477 present, however, and is expected to be used only
3482 If you want to specify which of a set of real packages
3483 should be the default to satisfy a particular dependency on
3484 a virtual package, you should list the real package as an
3485 alternative before the virtual one.
3490 <sect id="replaces"><heading>Overwriting files and replacing
3491 packages - <tt>Replaces</tt></heading>
3494 The <tt>Replaces</tt> control file field has two distinct
3495 purposes, which come into play in different situations.
3498 <sect1><heading>Overwriting files in other packages</heading>
3501 Firstly, as mentioned before, it is usually an error for a
3502 package to contain files which are on the system in
3507 However, if the overwriting package declares that it
3508 <tt>Replaces</tt> the one containing the file being
3509 overwritten, then <prgn>dpkg</prgn> will replace the file
3510 from the old package with that from the new. The file
3511 will no longer be listed as `owned' by the old package.
3515 If a package is completely replaced in this way, so that
3516 <prgn>dpkg</prgn> does not know of any files it still
3517 contains, it is considered to have `disappeared'. It will
3518 be marked as not wanted on the system (selected for
3519 removal) and not installed. Any <tt>conffile</tt>s
3520 details noted for the package will be ignored, as they
3521 will have been taken over by the overwriting package. The
3522 package's <prgn>postrm</prgn> script will be run with a
3523 special argument to allow the package to do any final
3524 cleanup required. See <ref id="mscriptsinstact">.
3528 If an installed package, <tt>foo</tt> say, declares that
3529 it replaces another, <tt>bar</tt>, and an attempt is made
3530 to install <tt>bar</tt>, <prgn>dpkg</prgn> will discard
3531 files in the <tt>bar</tt> package which would overwrite
3532 those already present in <tt>foo</tt>. This is so that
3533 you can install an older version of a package without
3538 For this usage of <tt>Replaces</tt>, virtual packages (see
3539 <ref id="virtual">) are not considered when looking at a
3540 <tt>Replaces</tt> field - the packages declared as being
3541 replaced must be mentioned by their real names.
3545 Furthermore, this usage of <tt>Replaces</tt> only takes
3546 effect when both packages are at least partially on the
3547 system at once, so that it can only happen if they do not
3548 conflict or if the conflict has been overridden.
3553 <sect1><heading>Replacing whole packages, forcing their
3557 Secondly, <tt>Replaces</tt> allows the packaging system to
3558 resolve which package should be removed when there is a
3559 conflict - see <ref id="conflicts">. This usage only
3560 takes effect when the two packages <em>do</em> conflict,
3561 so that the two usages of this field do not interfere with
3566 In this situation, the package declared as being replaced
3567 can be a virtual package, so for example, all mail
3568 transport agents (MTAs) would have the following fields in
3569 their control files:
3570 <example compact="compact">
3571 Provides: mail-transport-agent
3572 Conflicts: mail-transport-agent
3573 Replaces: mail-transport-agent
3575 ensuring that only one MTA can be installed at any one
3580 <sect><heading>Relationships between source and binary packages -
3581 <tt>Build-Depends</tt>, <tt>Build-Depends-Indep</tt>,
3582 <tt>Build-Conflicts</tt>, <tt>Build-Conflicts-Indep</tt>
3586 A source package may declare a dependency or a conflict on a
3587 binary package, indicating which packages are required to be
3588 present on the system in order to build the binary packages
3589 from the source package. This is done with the control file
3590 fields <tt>Build-Depends</tt>, <tt>Build-Depends-Indep</tt>,
3591 <tt>Build-Conflicts</tt> and <tt>Build-Conflicts-Indep</tt>.
3592 The dependencies and conflicts they define must be satisfied
3593 (as defined earlier for binary packages) in order to invoke
3594 the targets in <tt>debian/rules</tt>, as follows:
3597 <tag><tt>Build-Depends</tt>, <tt>Build-Conflicts</tt></tag>
3600 The <tt>Build-Depends</tt> and
3601 <tt>Build-Conflicts</tt> fields must be satisfied when
3602 any of the following targets is invoked:
3603 <tt>build</tt>, <tt>binary</tt>, <tt>binary-arch</tt>
3604 and <tt>binary-indep</tt>.
3607 <tag><tt>Build-Depends-Indep</tt>, <tt>Build-Conflicts-Indep</tt></tag>
3610 The <tt>Build-Depends-Indep</tt> and
3611 <tt>Build-Conflicts-Indep</tt> fields must be
3612 satisfied when any of the following targets is
3613 invoked: <tt>binary</tt> and <tt>binary-indep</tt>.
3624 <chapt id="conffiles"><heading>Configuration file handling
3628 This chapter has been superseded by <ref id="config files">.
3632 <chapt id="sharedlibs"><heading>Shared libraries</heading>
3635 Packages containing shared libraries must be constructed with
3636 a little care to make sure that the shared library is always
3637 available. This is especially important for packages whose
3638 shared libraries are vitally important, such as the C library
3639 (currently <tt>libc6</tt>).
3643 Firstly, the package should install the shared libraries under
3644 their normal names. For example, the <tt>libgdbmg1</tt>
3645 package should install <tt>libgdbm.so.1.7.3</tt> as
3646 <tt>/usr/lib/libgdbm.so.1.7.3</tt>. The files should not be
3647 renamed or re-linked by any <prgn>prerm</prgn> or
3648 <prgn>postrm</prgn> scripts; <prgn>dpkg</prgn> will take care
3649 of renaming things safely without affecting running programs,
3650 and attempts to interfere with this are likely to lead to
3655 Secondly, the package should include the symbolic link that
3656 <prgn>ldconfig</prgn> would create for the shared libraries.
3657 For example, the <prgn>libgdbmg1</prgn> package should include
3658 a symbolic link from <tt>/usr/lib/libgdbm.so.1</tt> to
3659 <tt>libgdbm.so.1.7.3</tt>. This is needed so that the dynamic
3660 linker (for example <prgn>ld.so</prgn> or
3661 <prgn>ld-linux.so.*</prgn>) can find the library between the
3662 time that <prgn>dpkg</prgn> installs it and the time that
3663 <prgn>ldconfig</prgn> is run in the <prgn>postinst</prgn>
3666 The package management system requires the library to be
3667 placed before the symbolic link pointing to it in the
3668 <tt>.deb</tt> file. This is so that when
3669 <prgn>dpkg</prgn> comes to install the symlink
3670 (overwriting the previous symlink pointing at an older
3671 version of the library), the new shared library is already
3672 in place. In the past, this was achieved by creating the
3673 library in the temporary packaging directory before
3674 creating the symlink. Unfortunately, this was not always
3675 effective, since the building of the tar file in the
3676 <tt>.deb</tt> depended on the behavior of the underlying
3677 file system. Some file systems (such as reiserfs) reorder
3678 the files so that the order of creation is forgotten.
3679 Starting with release <tt>1.7.0</tt>, <prgn>dpkg</prgn>
3680 will reorder the files itself as necessary when building a
3681 package. Thus it is no longer important to concern
3682 oneself with the order of file creation.
3688 Thirdly, the associated development package should contain a
3689 symlink for the shared library without a version number. For
3690 example, the <tt>libgdbmg1-dev</tt> package should include a
3691 symlink from <tt>/usr/lib/libgdbm.so</tt> to
3692 <tt>libgdbm.so.1.7.3</tt>. This symlink is needed by the
3693 linker (<prgn>ld</prgn>) when compiling packages, as it will
3694 only look for <tt>libgdbm.so</tt> when compiling dynamically.
3698 Any package installing shared libraries in one of the default
3699 library directories of the dynamic linker (which are currently
3700 <tt>/usr/lib</tt> and <tt>/lib</tt>) or a directory that is
3701 listed in <tt>/etc/ld.so.conf</tt><footnote>
3704 <list compact="compact">
3705 <item><p>/usr/X11R6/lib/Xaw3d</p></item>
3706 <item><p>/usr/local/lib</p></item>
3707 <item><p>/usr/lib/libc5-compat</p></item>
3708 <item><p>/lib/libc5-compat</p></item>
3709 <item><p>/usr/X11R6/lib</p></item>
3713 must call <prgn>ldconfig</prgn> in its <prgn>postinst</prgn>
3714 script if the first argument is <tt>configure</tt> and should
3715 call it in the <prgn>postrm</prgn> script if the first
3716 argument is <tt>remove</tt>.
3720 However, <prgn>postrm</prgn> and <prgn>preinst</prgn> scripts
3721 <em>must not</em> call <prgn>ldconfig</prgn> in the case where
3722 the package is being upgraded (see <ref id="unpackphase"> for
3723 details), as <prgn>ldconfig</prgn> will see the temporary
3724 names that <prgn>dpkg</prgn> uses for the files while it is
3725 installing them and will make the shared library links point
3726 to them, just before <prgn>dpkg</prgn> continues the
3727 installation and renames the temporary files!
3731 <heading>Handling shared library dependencies - the
3732 <tt>shlibs</tt> system</heading>
3735 If a package contains a binary or library which links to a
3736 shared library, we must ensure that when the package is
3737 installed on the system, all of the libraries needed are
3738 also installed. This requirement led to the creation of the
3739 <tt>shlibs</tt> system, which is very simple in its design:
3740 any package which <em>provides</em> a shared library also
3741 provides information on the package dependencies required to
3742 ensure the presence of this library, and any package which
3743 <em>uses</em> a shared library uses this information to
3744 determine the dependencies it requires. The files which
3745 contain the mapping from shared libraries to the necessary
3746 dependency information are called <tt>shlibs</tt> files.
3750 Thus, when a package is built which contains any shared
3751 libraries, it must provide a <tt>shlibs</tt> file for other
3752 packages to use, and when a package is built which contains
3753 any shared libraries or compiled binaries, it must run
3754 <prgn>dpkg-shlibdeps</prgn> on these to determine the
3755 libraries used and hence the dependencies needed by this
3758 In the past, the shared libraries linked to were
3759 determined by calling <prgn>ldd</prgn>, but now
3760 <prgn>objdump</prgn> is used to do this. The only
3761 change this makes to package building is that
3762 <prgn>dpkg-shlibdeps</prgn> must also be run on shared
3763 libraries, whereas in the past this was unnecessary.
3764 The rest of this footnote explains the advantage that
3769 We say that a binary <tt>foo</tt> <em>directly</em> uses
3770 a library <tt>libbar</tt> if it is explicitly linked
3771 with that library (that is, it uses the flag
3772 <tt>-lbar</tt> during the linking stage). Other
3773 libraries that are needed by <tt>libbar</tt> are linked
3774 <em>indirectly</em> to <tt>foo</tt>, and the dynamic
3775 linker will load them automatically when it loads
3776 <tt>libbar</tt>. A package should depend on
3777 the libraries it directly uses, and the dependencies for
3778 those libraries should automatically pull in the other
3783 Unfortunately, the <prgn>ldd</prgn> program shows both
3784 the directly and indirectly used libraries, meaning that
3785 the dependencies determined included both direct and
3786 indirect dependencies. The use of <prgn>objdump</prgn>
3787 avoids this problem by determining only the directly
3792 A good example of where this helps is the following. We
3793 could update <tt>libimlib</tt> with a new version that
3794 supports a new graphics format called dgf (but retaining
3795 the same major version number). If we used the old
3796 <prgn>ldd</prgn> method, every package that uses
3797 <tt>libimlib</tt> would need to be recompiled so it
3798 would also depend on <tt>libdgf</tt> or it wouldn't run
3799 due to missing symbols. However with the new system,
3800 packages using <tt>libimlib</tt> can rely on
3801 <tt>libimlib</tt> itself having the dependency on
3802 <tt>libdgf</tt> and so they would not need rebuilding.
3808 In the following sections, we will first describe where the
3809 various <tt>shlibs</tt> files are to be found, then how to
3810 use <prgn>dpkg-shlibdeps</prgn>, and finally the
3811 <tt>shlibs</tt> file format and how to create them if your
3812 package contains a shared library.
3816 <sect><heading>The <tt>shlibs</tt> files present on the system
3820 There are several places where <tt>shlibs</tt> files are
3821 found. The following list gives them in the order in which
3822 they are read by <prgn>dpkg-shlibdeps</prgn>. (The first
3823 one which gives the required information is used.)
3829 <p><tt>debian/shlibs.local</tt></p>
3831 This lists overrides for this package. Its use is
3832 described below (see <ref id="shlibslocal">).
3837 <p><tt>/etc/dpkg/shlibs.override</tt></p>
3839 This lists global overrides. This list is normally
3840 empty. It is maintained by the local system
3846 <p><tt>DEBIAN/shlibs</tt> files in the `build directory'</p>
3848 When packages are being built, any
3849 <tt>debian/shlibs</tt> files are copied into the
3850 control file area of the temporary build directory and
3851 given the name <tt>shlibs</tt>. These files give
3852 details of any shared libraries included in the
3855 An example may help here. Let us say that the
3856 source package <tt>foo</tt> generates two binary
3857 packages, <tt>libfoo2</tt> and
3858 <tt>foo-runtime</tt>. When building the binary
3859 packages, the two packages are created in the
3860 directories <tt>debian/libfoo2</tt> and
3861 <tt>debian/foo-runtime</tt> respectively.
3862 (<tt>debian/tmp</tt> could be used instead of one
3863 of these.) Since <tt>libfoo2</tt> provides the
3864 <tt>libfoo</tt> shared library, it will require a
3865 <tt>shlibs</tt> file, which will be installed in
3866 <tt>debian/libfoo2/DEBIAN/shlibs</tt>, eventually
3868 <tt>/var/lib/dpkg/info/libfoo2.shlibs</tt>. Then
3869 when <prgn>dpkg-shlibdeps</prgn> is run on the
3871 <tt>debian/foo-runtime/usr/bin/foo-prog</tt>, it
3873 <tt>debian/libfoo2/DEBIAN/shlibs</tt> file to
3874 determine whether <tt>foo-prog</tt>'s library
3875 dependencies are satisfied by any of the libraries
3876 provided by <tt>libfoo2</tt>. For this reason,
3877 <prgn>dpkg-shlibdeps</prgn> must only be run once
3878 all of the individual binary packages'
3879 <tt>shlibs</tt> files have been installed into the
3887 <p><tt>/var/lib/dpkg/info/*.shlibs</tt></p>
3889 These are the <tt>shlibs</tt> files corresponding to
3890 all of the packages installed on the system, and are
3891 maintained by the relevant package maintainers.
3896 <p><tt>/etc/dpkg/shlibs.default</tt></p>
3898 This file lists any shared libraries whose packages
3899 have failed to provide correct <tt>shlibs</tt> files.
3900 It was used when the <tt>shlibs</tt> setup was first
3901 introduced, but it is now normally empty. It is
3902 maintained by the <tt>dpkg</tt> maintainer.
3910 <heading>How to use <prgn>dpkg-shlibdeps</prgn> and the
3911 <tt>shlibs</tt> files</heading>
3914 Put a call to <prgn>dpkg-shlibdeps</prgn> into your
3915 <tt>debian/rules</tt> file. If your package contains only
3916 compiled binaries and libraries (but no scripts), you can
3917 use a command such as:
3918 <example compact="compact">
3919 dpkg-shlibdeps debian/tmp/usr/bin/* debian/tmp/usr/sbin/* \
3920 debian/tmp/usr/lib/*
3922 Otherwise, you will need to explicitly list the compiled
3923 binaries and libraries.<footnote>
3925 If you are using <tt>debhelper</tt>, the
3926 <prgn>dh_shlibdeps</prgn> program will do this work for
3927 you. It will also correctly handle multi-binary
3934 This command puts the dependency information into the
3935 <tt>debian/substvars</tt> file, which is then used by
3936 <prgn>dpkg-gencontrol</prgn>. You will need to place a
3937 <tt>${shlib:Depends}</tt> variable in the <tt>Depends</tt>
3938 field in the control file for this to work.
3942 If <prgn>dpkg-shlibdeps</prgn> doesn't complain, you're
3943 done. If it does complain you might need to create your own
3944 <tt>debian/shlibs.local</tt> file, as explained below (see
3945 <ref id="shlibslocal">).
3949 If you have multiple binary packages, you will need to call
3950 <prgn>dpkg-shlibdeps</prgn> on each one which contains
3951 compiled libraries or binaries. In such a case, you will
3952 need to use the <tt>-T</tt> option to the <tt>dpkg</tt>
3953 utilities to specify a different <tt>substvars</tt> file.
3954 For more details on this and other options, see <manref
3955 name="dpkg-shlibdeps" section="1">.
3959 <sect id="shlibs"><heading>The <tt>shlibs</tt> File Format
3963 Each <tt>shlibs</tt> file has the same format. Lines
3964 beginning with <tt>#</tt> are considered to be comments and
3965 are ignored. Each line is of the form:
3966 <example compact="compact">
3967 <var>library-name</var> <var>soname-version-number</var> <var>dependencies ...</var>
3972 We will explain this by reference to the example of the
3973 <tt>zlib1g</tt> package, which (at the time of writing)
3974 installs the shared library <tt>/usr/lib/libz.so.1.1.3</tt>.
3978 <var>library-name</var> is the name of the shared library,
3979 in this case <tt>libz</tt>. (This must match the name part
3980 of the soname, see below.)
3984 <var>soname-version-number</var> is the version part of the
3985 soname of the library. The soname is the thing that must
3986 exactly match for the library to be recognized by the
3987 dynamic linker, and is usually of the form
3988 <tt><var>name</var>.so.<var>major-version</var></tt>, in our
3989 example, <tt>libz.so.1</tt>.<footnote>
3991 This can be determined using the command
3992 <example compact="compact">
3993 objdump -p /usr/lib/libz.so.1.1.3 | grep SONAME
3997 The version part is the part which comes after
3998 <tt>.so.</tt>, so in our case, it is <tt>1</tt>.
4002 <var>dependencies</var> has the same syntax as a dependency
4003 field in a binary package control file. It should give
4004 details of which packages are required to satisfy a binary
4005 built against the version of the library contained in the
4006 package. See <ref id="depsyntax"> for details.
4010 In our example, if the first version of the <tt>zlib1g</tt>
4011 package which contained a minor number of at least
4012 <tt>1.3</tt> was <var>1:1.1.3-1</var>, then the
4013 <tt>shlibs</tt> entry for this library could say:
4014 <example compact="compact">
4015 libz 1 zlib1g (>= 1:1.1.3)
4017 The version-specific dependency is to avoid warnings from
4018 the dynamic linker about using older shared libraries with
4024 <heading>Providing a <tt>shlibs</tt> file</heading>
4027 If your package provides a shared library, you should create
4028 a <tt>shlibs</tt> file following the format described above.
4029 It is usual to call this file <tt>debian/shlibs</tt> (but if
4030 you have multiple binary packages, you might want to call it
4031 <tt>debian/shlibs.<var>package</var></tt> instead). Then
4032 let <tt>debian/rules</tt> install it in the control area:
4033 <example compact="compact">
4034 install -m644 debian/shlibs debian/tmp/DEBIAN
4036 or, in the case of a multi-binary package:
4037 <example compact="compact">
4038 install -m644 debian/shlibs.<var>package</var> debian/<var>package</var>/DEBIAN/shlibs
4040 An alternative way of doing this is to create the
4041 <tt>shlibs</tt> file in the control area directly from
4042 <tt>debian/rules</tt> without using a <tt>debian/shlibs</tt>
4043 file at all,<footnote>
4045 This is what <prgn>dh_makeshlibs</prgn> in the
4046 <tt>debhelper</tt> suite does.
4049 since the <tt>debian/shlibs</tt> file itself is ignored by
4050 <prgn>dpkg-shlibdeps</prgn>.
4054 As <prgn>dpkg-shlibdeps</prgn> reads the
4055 <tt>DEBIAN/shlibs</tt> files in all of the binary packages
4056 being built from this source package, all of the
4057 <tt>DEBIAN/shlibs</tt> files should be installed before
4058 <prgn>dpkg-shlibdeps</prgn> is called on any of the binary
4063 <sect id="shlibslocal">
4064 <heading>Writing the <tt>debian/shlibs.local</tt> file</heading>
4067 This file is intended only as a <em>temporary</em> fix if
4068 your binaries or libraries depend on a library whose package
4069 does not yet provide a correct <tt>shlibs</tt> file.
4073 We will assume that you are trying to package a binary
4074 <tt>foo</tt>. When you try running
4075 <prgn>dpkg-shlibdeps</prgn> you get the following error
4076 message (<tt>-O</tt> displays the dependency information on
4077 <tt>stdout</tt> instead of writing it to
4078 <tt>debian/substvars</tt>, and the lines have been wrapped
4079 for ease of reading):
4080 <example compact="compact">
4081 $ dpkg-shlibdeps -O debian/tmp/usr/bin/foo
4082 dpkg-shlibdeps: warning: unable to find dependency
4083 information for shared library libbar (soname 1,
4084 path /usr/lib/libbar.so.1, dependency field Depends)
4085 shlibs:Depends=libc6 (>= 2.2.2-2)
4087 You can then run <prgn>ldd</prgn> on the binary to find the
4088 full location of the library concerned:
4089 <example compact="compact">
4091 libbar.so.1 => /usr/lib/libbar.so.1 (0x4001e000)
4092 libc.so.6 => /lib/libc.so.6 (0x40032000)
4093 /lib/ld-linux.so.2 => /lib/ld-linux.so.2 (0x40000000)
4095 So the <prgn>foo</prgn> binary depends on the
4096 <prgn>libbar</prgn> shared library, but no package seems to
4097 provide a <tt>*.shlibs</tt> file handling
4098 <tt>libbar.so.1</tt> in <tt>/var/lib/dpkg/info/</tt>. Let's
4099 determine the package responsible:
4100 <example compact="compact">
4101 $ dpkg -S /usr/lib/libbar.so.1
4102 bar1: /usr/lib/libbar.so.1
4103 $ dpkg -s bar1 | grep Version
4106 This tells us that the <tt>bar1</tt> package, version 1.0-1,
4107 is the one we are using. Now we can file a bug against the
4108 <tt>bar1</tt> package and create our own
4109 <tt>debian/shlibs.local</tt> to locally fix the problem.
4110 Including the following line into your
4111 <tt>debian/shlibs.local</tt> file:
4112 <example compact="compact">
4113 libbar 1 bar1 (>= 1.0-1)
4115 should allow the package build to work.
4119 As soon as the maintainer of <tt>bar1</tt> provides a
4120 correct <tt>shlibs</tt> file, you should remove this line
4121 from your <tt>debian/shlibs.local</tt> file. (You should
4122 probably also then have a versioned <tt>Build-Depends</tt>
4123 on <tt>bar1</tt> to help ensure that others do not have the
4124 same problem building your package.)
4129 <chapt id="opersys"><heading>The Operating System</heading>
4132 <heading>Filesystem hierarchy</heading>
4136 <heading>Filesystem Structure</heading>
4139 The location of all installed files and directories must
4140 comply with the Filesystem Hierarchy Standard (FHS),
4141 version 2.1, except where doing so would violate other
4142 terms of Debian Policy. The version of this document
4143 referred here can be found in the <tt>debian-policy</tt>
4145 <url id="http://www.debian.org/doc/packaging-manuals/fhs"
4146 name="FHS (Debian copy)"> alongside this manual. The
4147 latest version, which may be a more recent version, may
4149 <url id="http://www.pathname.com/fhs/" name="FHS (upstream)">.
4150 Specific questions about following the standard may be
4151 asked on the <tt>debian-devel</tt> mailing list, or
4152 referred to the FHS mailing list (see the
4153 <url id="http://www.pathname.com/fhs/" name="FHS web site"> for
4159 <heading>Site-specific programs</heading>
4162 As mandated by the FHS, packages must not place any
4163 files in <tt>/usr/local</tt>, either by putting them in
4164 the file system archive to be unpacked by <prgn>dpkg</prgn>
4165 or by manipulating them in their maintainer scripts.
4169 However, the package may create empty directories below
4170 <tt>/usr/local</tt> so that the system administrator knows
4171 where to place site-specific files. These directories
4172 should be removed on package removal if they are
4177 Note, that this applies only to directories <em>below</em>
4178 <tt>/usr/local</tt>, not <em>in</em> <tt>/usr/local</tt>.
4179 Packages must not create sub-directories in the directory
4180 <tt>/usr/local</tt> itself, except those listed in FHS,
4181 section 4.5. However, you may create directories below
4182 them as you wish. You must not remove any of the
4183 directories listed in 4.5, even if you created them.
4187 Since <tt>/usr/local</tt> can be mounted read-only from a
4188 remote server, these directories must be created and
4189 removed by the <prgn>postinst</prgn> and <prgn>prerm</prgn>
4190 maintainer scripts and not be included in the
4191 <tt>.deb</tt> archive. These scripts must not fail if
4192 either of these operations fail.
4196 For example, the <tt>emacsen-common</tt> package could
4197 contain something like
4198 <example compact="compact">
4199 if [ ! -e /usr/local/share/emacs ]
4201 if mkdir /usr/local/share/emacs 2>/dev/null
4203 chown root:staff /usr/local/share/emacs
4204 chmod 2775 /usr/local/share/emacs
4208 in its <prgn>postinst</prgn> script, and
4209 <example compact="compact">
4210 rmdir /usr/local/share/emacs/site-lisp 2>/dev/null || true
4211 rmdir /usr/local/share/emacs 2>/dev/null || true
4213 in the <prgn>prerm</prgn> script. (Note that this form is
4214 used to ensure that if the script is interrupted, the
4215 directory <tt>/usr/local/share/emacs</tt> will still be
4220 If you do create a directory in <tt>/usr/local</tt> for
4221 local additions to a package, you should ensure that
4222 settings in <tt>/usr/local</tt> take precedence over the
4223 equivalents in <tt>/usr</tt>.
4227 However, because <tt>/usr/local</tt> and its contents are
4228 for exclusive use of the local administrator, a package
4229 must not rely on the presence or absence of files or
4230 directories in <tt>/usr/local</tt> for normal operation.
4234 The <tt>/usr/local</tt> directory itself and all the
4235 subdirectories created by the package should (by default) have
4236 permissions 2775 (group-writable and set-group-id) and be
4237 owned by <tt>root.staff</tt>.
4242 <heading>The system-wide mail directory</heading>
4244 The system-wide mail directory is <tt>/var/mail</tt>. This
4245 directory is part of the base system and should not owned
4246 by any particular mail agents. The use of the old
4247 location <tt>/var/spool/mail</tt> is deprecated, even
4248 though the spool may still be physically located there.
4249 To maintain partial upgrade compatibility for systems
4250 which have <tt>/var/spool/mail</tt> as their physical mail
4251 spool, packages using <tt>/var/mail</tt> must depend on
4252 either <package>libc6</package> (>= 2.1.3-13), or on
4253 <package>base-files</package> (>= 2.2.0), or on later
4254 versions of either one of these packages.
4260 <heading>Users and groups</heading>
4263 <heading>Introduction</heading>
4265 The Debian system can be configured to use either plain or
4270 Some user ids (UIDs) and group ids (GIDs) are reserved
4271 globally for use by certain packages. Because some
4272 packages need to include files which are owned by these
4273 users or groups, or need the ids compiled into binaries,
4274 these ids must be used on any Debian system only for the
4275 purpose for which they are allocated. This is a serious
4276 restriction, and we should avoid getting in the way of
4277 local administration policies. In particular, many sites
4278 allocate users and/or local system groups starting at 100.
4282 Apart from this we should have dynamically allocated ids,
4283 which should by default be arranged in some sensible
4284 order, but the behavior should be configurable.
4288 Packages other than <tt>base-passwd</tt> must not modify
4289 <tt>/etc/passwd</tt>, <tt>/etc/shadow</tt>,
4290 <tt>/etc/group</tt> or <tt>/etc/gshadow</tt>.
4295 <heading>UID and GID classes</heading>
4297 The UID and GID numbers are divided into classes as
4303 Globally allocated by the Debian project, the same
4304 on every Debian system. These ids will appear in
4305 the <tt>passwd</tt> and <tt>group</tt> files of all
4306 Debian systems, new ids in this range being added
4307 automatically as the <tt>base-passwd</tt> package is
4312 Packages which need a single statically allocated
4313 uid or gid should use one of these; their
4314 maintainers should ask the <tt>base-passwd</tt>
4322 Dynamically allocated system users and groups.
4323 Packages which need a user or group, but can have
4324 this user or group allocated dynamically and
4325 differently on each system, should use <tt>adduser
4326 --system</tt> to create the group and/or user.
4327 <prgn>adduser</prgn> will check for the existence of
4328 the user or group, and if necessary choose an unused
4329 id based on the ranges specified in
4330 <tt>adduser.conf</tt>.
4334 <tag>1000-29999:</tag>
4337 Dynamically allocated user accounts. By default
4338 <prgn>adduser</prgn> will choose UIDs and GIDs for
4339 user accounts in this range, though
4340 <tt>adduser.conf</tt> may be used to modify this
4345 <tag>30000-59999:</tag>
4350 <tag>60000-64999:</tag>
4353 Globally allocated by the Debian project, but only
4354 created on demand. The ids are allocated centrally
4355 and statically, but the actual accounts are only
4356 created on users' systems on demand.
4360 These ids are for packages which are obscure or
4361 which require many statically-allocated ids. These
4362 packages should check for and create the accounts in
4363 <tt>/etc/passwd</tt> or <tt>/etc/group</tt> (using
4364 <prgn>adduser</prgn> if it has this facility) if
4365 necessary. Packages which are likely to require
4366 further allocations should have a `hole' left after
4367 them in the allocation, to give them room to
4372 <tag>65000-65533:</tag>
4380 User <tt>nobody</tt>. The corresponding gid refers
4381 to the group <tt>nogroup</tt>.
4388 <tt>(uid_t)(-1) == (gid_t)(-1)</tt> <em>must
4389 not</em> be used, because it is the error return
4398 <sect id="sysvinit">
4399 <heading>System run levels and <tt>init.d</tt> scripts</heading>
4401 <sect1 id="/etc/init.d">
4402 <heading>Introduction</heading>
4405 The <tt>/etc/init.d</tt> directory contains the scripts
4406 executed by <prgn>init</prgn> at boot time and when the
4407 init state (or `runlevel') is changed (see <manref
4408 name="init" section="8">).
4412 There are at least two different, yet functionally
4413 equivalent, ways of handling these scripts. For the sake
4414 of simplicity, this document describes only the symbolic
4415 link method. However, it must not be assumed by maintainer
4416 scripts that this method is being used, and any automated
4417 manipulation of the various runlevel behaviours by
4418 maintainer scripts must be performed using
4419 <prgn>update-rc.d</prgn> as described below and not by
4420 manually installing or removing symlinks. For information
4421 on the implementation details of the other method,
4422 implemented in the <tt>file-rc</tt> package, please refer
4423 to the documentation of that package.
4427 These scripts are referenced by symbolic links in the
4428 <tt>/etc/rc<var>n</var>.d</tt> directories. When changing
4429 runlevels, <prgn>init</prgn> looks in the directory
4430 <tt>/etc/rc<var>n</var>.d</tt> for the scripts it should
4431 execute, where <tt><var>n</var></tt> is the runlevel that
4432 is being changed to, or <tt>S</tt> for the boot-up
4437 The names of the links all have the form
4438 <tt>S<var>mm</var><var>script</var></tt> or
4439 <tt>K<var>mm</var><var>script</var></tt> where
4440 <var>mm</var> is a two-digit number and <var>script</var>
4441 is the name of the script (this should be the same as the
4442 name of the actual script in <tt>/etc/init.d</tt>).
4446 When <prgn>init</prgn> changes runlevel first the targets
4447 of the links whose names start with a <tt>K</tt> are
4448 executed, each with the single argument <tt>stop</tt>,
4449 followed by the scripts prefixed with an <tt>S</tt>, each
4450 with the single argument <tt>start</tt>. (The links are
4451 those in the <tt>/etc/rc<var>n</var>.d</tt> directory
4452 corresponding to the new runlevel.) The <tt>K</tt> links
4453 are responsible for killing services and the <tt>S</tt>
4454 link for starting services upon entering the runlevel.
4458 For example, if we are changing from runlevel 2 to
4459 runlevel 3, init will first execute all of the <tt>K</tt>
4460 prefixed scripts it finds in <tt>/etc/rc3.d</tt>, and then
4461 all of the <tt>S</tt> prefixed scripts in that directory.
4462 The links starting with <tt>K</tt> will cause the
4463 referred-to file to be executed with an argument of
4464 <tt>stop</tt>, and the <tt>S</tt> links with an argument
4469 The two-digit number <var>mm</var> is used to determine
4470 the order in which to run the scripts: low-numbered links
4471 have their scripts run first. For example, the
4472 <tt>K20</tt> scripts will be executed before the
4473 <tt>K30</tt> scripts. This is used when a certain service
4474 must be started before another. For example, the name
4475 server <prgn>bind</prgn> might need to be started before
4476 the news server <prgn>inn</prgn> so that <prgn>inn</prgn>
4477 can set up its access lists. In this case, the script
4478 that starts <prgn>bind</prgn> would have a lower number
4479 than the script that starts <prgn>inn</prgn> so that it
4481 <example compact="compact">
4488 The two runlevels 0 (halt) and 6 (reboot) are slightly
4489 different. In these runlevels, the links with an
4490 <tt>S</tt> prefix are still called after those with a
4491 <tt>K</tt> prefix, but they too are called with the single
4492 argument <tt>stop</tt>.
4496 Also, if the script name ends <tt>.sh</tt>, the script
4497 will be sourced in runlevel <tt>S</tt> rather that being
4498 run in a forked subprocess, but will be explicitly run by
4499 <prgn>sh</prgn> in all other runlevels.
4504 <heading>Writing the scripts</heading>
4507 Packages that include daemons for system services should
4508 place scripts in <tt>/etc/init.d</tt> to start or stop
4509 services at boot time or during a change of runlevel.
4510 These scripts should be named
4511 <tt>/etc/init.d/<var>package</var></tt>, and they should
4512 accept one argument, saying what to do:
4515 <tag><tt>start</tt></tag>
4516 <item><p>start the service,</p></item>
4518 <tag><tt>stop</tt></tag>
4519 <item><p>stop the service,</p></item>
4521 <tag><tt>restart</tt></tag>
4522 <item><p>stop and restart the service,</p></item>
4524 <tag><tt>reload</tt></tag>
4525 <item><p>cause the configuration of the service to be
4526 reloaded without actually stopping and restarting
4527 the service,</p></item>
4529 <tag><tt>force-reload</tt></tag>
4530 <item><p>cause the configuration to be reloaded if the
4531 service supports this, otherwise restart the
4535 The <tt>start</tt>, <tt>stop</tt>, <tt>restart</tt>, and
4536 <tt>force-reload</tt> options should be supported by all
4537 scripts in <tt>/etc/init.d</tt>, the <tt>reload</tt>
4538 option is optional.</p>
4541 The <tt>init.d</tt> scripts should ensure that they will
4542 behave sensibly if invoked with <tt>start</tt> when the
4543 service is already running, or with <tt>stop</tt> when it
4544 isn't, and that they don't kill unfortunately-named user
4545 processes. The best way to achieve this is usually to use
4546 <prgn>start-stop-daemon</prgn>.</p>
4549 If a service reloads its configuration automatically (as
4550 in the case of <prgn>cron</prgn>, for example), the
4551 <tt>reload</tt> option of the <tt>init.d</tt> script
4552 should behave as if the configuration has been reloaded
4556 The <tt>/etc/init.d</tt> scripts must be treated as
4557 configuration files, either (if they are present in the
4558 package, that is, in the .deb file) by marking them as
4559 <tt>conffile</tt>s, or, (if they do not exist in the .deb)
4560 by managing them correctly in the maintainer scripts (see
4561 <ref id="config files">). This is important since we want
4562 to give the local system administrator the chance to adapt
4563 the scripts to the local system, e.g., to disable a
4564 service without de-installing the package, or to specify
4565 some special command line options when starting a service,
4566 while making sure her changes aren't lost during the next
4571 These scripts should not fail obscurely when the
4572 configuration files remain but the package has been
4573 removed, as configuration files remain on the system after
4574 the package has been removed. Only when <prgn>dpkg</prgn>
4575 is executed with the <tt>--purge</tt> option will
4576 configuration files be removed. In particular, as the
4577 <tt>/etc/init.d/<var>package</var></tt> script itself is
4578 usually a <tt>conffile</tt>, it will remain on the system
4579 if the package is removed but not purged. Therefore, you
4580 should include a <tt>test</tt> statement at the top of the
4582 <example compact="compact">
4583 test -f <var>program-executed-later-in-script</var> || exit 0
4588 Often there are some variables in the <tt>init.d</tt>
4589 scripts whose values control the bahaviour of the scripts,
4590 and which a system administrator is likely to want to
4591 change. As the scripts themselves are frequently
4592 <tt>conffile</tt>s, modifying them requires that the
4593 administrator merge in their changes each time the package
4594 is upgraded and the <tt>conffile</tt> changes. To ease
4595 the burden on the system administrator, such configurable
4596 values should not be placed directly in the script.
4597 Instead, they should be placed in a file in
4598 <tt>/etc/default</tt>, which typically will have the same
4599 base name as the <tt>init.d</tt> script. This extra file
4600 should be sourced by the script when the script runs. It
4601 must contain only variable settings and comments in POSIX
4602 <prgn>sh</prgn> format. It may either be a
4603 <tt>conffile</tt> or a configuration file maintained by
4604 the package maintainer scripts. See <ref id="config files">
4609 To ensure that vital configurable values are always
4610 available, the <tt>init.d</tt> script should set default
4611 values for each of the shell variables it uses, either
4612 before sourcing the <tt>/etc/default/</tt> file or
4613 afterwards using something like the <tt>:
4614 ${VAR:=default}</tt> syntax. Also, the <tt>init.d</tt>
4615 script must behave sensibly and not fail if the
4616 <tt>/etc/default</tt> file is deleted.
4621 <heading>Managing the links</heading>
4624 The program <prgn>update-rc.d</prgn> is provided for
4625 package maintainers to arrange for the proper creation and
4626 removal of <tt>/etc/rc<var>n</var>.d</tt> symbolic links,
4627 or their functional equivalent if another method is being
4628 used. This may be used by maintainers in their packages'
4629 <prgn>postinst</prgn> and <prgn>postrm</prgn> scripts.</p>
4632 You must not include any <tt>/etc/rc<var>n</var>.d</tt>
4633 symbolic links in the actual archive or manually create or
4634 remove the symbolic links in maintainer scripts; you must
4635 use the <prgn>update-rc.d</prgn> program instead. (The
4636 former will fail if an alternative method of maintaining
4637 runlevel information is being used.) You must not include
4638 the <tt>/etc/rc<var>n</var>.d</tt> directories themselves
4639 in the archive either. (Only the <tt>sysvinit</tt>
4644 By default <prgn>update-rc.d</prgn> will start services in
4645 each of the multi-user state runlevels (2, 3, 4, and 5)
4646 and stop them in the halt runlevel (0), the single-user
4647 runlevel (1) and the reboot runlevel (6). The system
4648 administrator will have the opportunity to customize
4649 runlevels by simply adding, moving, or removing the
4650 symbolic links in <tt>/etc/rc<var>n</var>.d</tt> if
4651 symbolic links are being used, or by modifying
4652 <tt>/etc/runlevel.conf</tt> if the <tt>file-rc</tt> method
4657 To get the default behavior for your package, put in your
4658 <prgn>postinst</prgn> script
4659 <example compact="compact">
4660 update-rc.d <var>package</var> defaults >/dev/null
4662 and in your <prgn>postrm</prgn>
4663 <example compact="compact">
4664 if [ "$1" = purge ]; then
4665 update-rc.d <var>package</var> remove >/dev/null
4670 This will use a default sequence number of 20. If it does
4671 not matter when or in which order the <tt>init.d</tt>
4672 script is run, use this default. If it does, then you
4673 should talk to the maintainer of the <prgn>sysvinit</prgn>
4674 package or post to <tt>debian-devel</tt>, and they will
4675 help you choose a number.
4679 For more information about using <tt>update-rc.d</tt>,
4680 please consult its manpage <manref name="update-rc.d"
4687 <heading>Boot-time initialization</heading>
4690 There used to be another directory, <tt>/etc/rc.boot</tt>,
4691 which contained scripts which were run once per machine
4692 boot. This has been deprecated in favour of links from
4693 <tt>/etc/rcS.d</tt> to files in <tt>/etc/init.d</tt> as
4694 described in <ref id="/etc/init.d">. Packages must not
4695 place files in <tt>/etc/rc.boot</tt>.</p>
4698 <heading>Example</heading>
4701 The <prgn>bind</prgn> DNS (nameserver) package wants to
4702 make sure that the nameserver is running in multiuser
4703 runlevels, and is properly shut down with the system. It
4704 puts a script in <tt>/etc/init.d</tt>, naming the script
4705 appropriately <tt>bind</tt>. As you can see, the script
4706 interprets the argument <tt>reload</tt> to send the
4707 nameserver a <tt>HUP</tt> signal (causing it to reload its
4708 configuration); this way the system administrator can say
4709 <tt>/etc/init.d/bind reload</tt> to reload the name
4710 server. The script has one configurable value, which can
4711 be used to pass parameters to the named program at
4712 startup; this value is read from
4713 <tt>/etc/default/bind</tt> (see below).
4717 <example compact="compact">
4720 # Original version by Robert Leslie
4721 # <rob@mars.org>, edited by iwj and cs
4723 test -x /usr/sbin/named || exit 0
4725 # Source defaults file.
4727 if [ -f /etc/default/bind ]; then
4734 echo -n "Starting domain name service: named"
4735 start-stop-daemon --start --quiet --exec /usr/sbin/named \
4740 echo -n "Stopping domain name service: named"
4741 start-stop-daemon --stop --quiet \
4742 --pidfile /var/run/named.pid --exec /usr/sbin/named
4746 echo -n "Restarting domain name service: named"
4747 start-stop-daemon --stop --quiet \
4748 --pidfile /var/run/named.pid --exec /usr/sbin/named
4749 start-stop-daemon --start --verbose --exec /usr/sbin/named \
4753 force-reload|reload)
4754 echo -n "Reloading configuration of domain name service: named"
4755 start-stop-daemon --stop --signal 1 --quiet \
4756 --pidfile /var/run/named.pid --exec /usr/sbin/named
4760 echo "Usage: /etc/init.d/bind {start|stop|restart|reload|force-reload}" >&2
4770 Complementing the above init script is a configuration
4771 file <tt>/etc/default/bind</tt>, which contains
4772 configurable parameters used by the script. This would be
4773 created by the <prgn>postinst</prgn> script if it was not
4774 already present, and removed on purge by the
4775 <prgn>postrm</prgn> script.
4776 <example compact="compact">
4777 # Specified parameters to pass to named. See named(8).
4778 # You may uncomment the following line, and edit to taste.
4784 Another example on which you can base your
4785 <tt>/etc/init.d</tt> scripts is found in
4786 <tt>/etc/init.d/skeleton</tt>.
4790 If this package is happy with the default setup from
4791 <prgn>update-rc.d</prgn>, namely an ordering number of 20
4792 and having named running in all runlevels, it can say in
4793 its <prgn>postinst</prgn>:
4794 <example compact="compact">
4795 update-rc.d bind defaults >/dev/null
4797 And in its <prgn>postrm</prgn>, to remove the links when the
4799 <example compact="compact">
4800 if [ "$1" = purge ]; then
4801 update-rc.d bind remove >/dev/null
4809 <heading>Console messages from <tt>init.d</tt> scripts</heading>
4812 This section describes the formats to be used for messages
4813 written to standard output by the <tt>/etc/init.d</tt>
4814 scripts. The intent is to improve the consistency of
4815 Debian's startup and shutdown look and feel. For this
4816 reason, please look very carefully at the details. We want
4817 the messages to have the same format in terms of wording,
4818 spaces, punctuation and case of letters.
4822 Here is a list of overall rules that you should use when you
4823 create output messages. They can be useful if you have a
4824 non-standard message that is not covered specifically in the
4832 Every message should fit in one line (fewer than 80
4833 characters), start with a capital letter and end with
4834 a period (<tt>.</tt>) and line feed (<tt>"\n"</tt>).
4840 If you want to express that the computer is working on
4841 something (that is, performing a specific task, not
4842 starting or stopping a program), we use an "ellipsis"
4843 (three dots: <tt>...</tt>). Note that we don't insert
4844 spaces before or after the dots. If the task has been
4845 completed we write <tt>done.</tt> and a line feed.
4851 Design your messages as if the computer is telling you
4852 what he is doing (let him be polite :-), but don't
4853 mention "him" directly. For example, if you think of
4855 <example compact="compact">
4856 I'm starting network daemons: nfsd mountd.
4859 <example compact="compact">
4860 Starting network daemons: nfsd mountd.
4868 There are standard message formats for the following
4869 situations. They should be used by the <tt>init.d</tt>
4876 <p>When daemons are started</p>
4879 If your script starts one or more daemons, the output
4880 should look like this (a single line, no leading
4882 <example compact="compact">
4883 Starting <var>description</var>: <var>daemon-1</var> ... <var>daemon-n</var>.
4885 The <var>description</var> should describe the
4886 subsystem the daemon or set of daemons are part of,
4887 while <var>daemon-1</var> up to <var>daemon-n</var>
4888 denote each daemon's name (typically the file name of
4893 For example, the output of <tt>/etc/init.d/lpd</tt>
4895 <example compact="compact">
4896 Starting printer spooler: lpd.
4901 This can be achieved by saying
4902 <example compact="compact">
4903 echo -n "Starting printer spooler: lpd"
4904 start-stop-daemon --start --quiet --exec /usr/sbin/lpd
4907 in the script. If you have more than one daemon to
4908 start, you should do the following:
4909 <example compact="compact">
4910 echo -n "Starting remote file system services:"
4911 echo -n " nfsd"; start-stop-daemon --start --quiet nfsd
4912 echo -n " mountd"; start-stop-daemon --start --quiet mountd
4913 echo -n " ugidd"; start-stop-daemon --start --quiet ugidd
4916 This makes it possible for the user to see what takes
4917 so long and when the final daemon has been started.
4918 You should be careful where to put spaces: in the
4919 example above the system administrator can easily
4920 comment out a line if he don't wants to start a
4921 specific daemon, while the displayed message still
4927 <p>When a system parameter is being set</p>
4930 If you have to set up different system parameters
4931 during the system boot, you should use this format:
4932 <example compact="compact">
4933 Setting <var>parameter</var> to `<var>value</var>'.
4938 You can use a statement such as the following to get
4940 <example compact="compact">
4941 echo "Setting DNS domainname to \`$domainname'."
4946 Note that the left quotation mark (<tt>`</tt>) is
4947 different from the right one (<tt>'</tt>).
4952 <p>When a daemon is stopped or restarted</p>
4955 When you stop or restart a daemon, you should issue a
4956 message identical to the startup message, except that
4957 <tt>Starting</tt> is replaced with <tt>Stopping</tt>
4958 or <tt>Restarting</tt> respectively.
4962 For example, stopping the printer daemon will like
4964 <example compact="compact">
4965 Stopping printer spooler: lpd.
4971 <p>When something is executed</p>
4974 There are several examples where you have to run a
4975 program at system startup or shutdown to perform a
4976 specific task, for example, setting the system's clock
4977 using <prgn>netdate</prgn> or killing all processes
4978 when the system shuts down. Your message should look
4980 <example compact="compact">
4981 Doing something very useful...done.
4983 You should print the <tt>done.</tt> immediately after
4984 the job has been completed, so that the user is
4985 informed why she has to wait. You can get this
4987 <example compact="compact">
4988 echo -n "Doing something very useful..."
4997 <p>When the configuration is reloaded</p>
5000 When a daemon is forced to reload its configuration
5001 files you should use the following format:
5002 <example compact="compact">
5003 Reloading <var>description</var> configuration...done.
5005 where <var>description</var> is the same as in the
5006 daemon starting message.
5014 <heading>Cron jobs</heading>
5017 Packages must not modify the configuration file
5018 <tt>/etc/crontab</tt>, and they must not modify the files in
5019 <tt>/var/spool/cron/crontabs</tt>.</p>
5022 If a package wants to install a job that has to be executed
5023 via cron, it should place a file with the name of the
5024 package in one or more of the following directories:
5025 <example compact="compact">
5030 As these directory names imply, the files within them are
5031 executed on a daily, weekly, or monthly basis,
5032 respectively. The exact times are listed in
5033 <tt>/etc/crontab</tt>.</p>
5036 All files installed in any of these directories must be
5037 scripts (e.g., shell scripts or Perl scripts) so that they
5038 can easily be modified by the local system administrator.
5039 In addition, they should be treated as configuration
5044 If a certain job has to be executed more frequently than
5045 daily, the package should install a file
5046 <tt>/etc/cron.d/<var>package</var></tt>. This file uses the
5047 same syntax as <tt>/etc/crontab</tt> and is processed by
5048 <prgn>cron</prgn> automatically. The file must also be
5049 treated as a configuration file. (Note that entries in the
5050 <tt>/etc/cron.d</tt> directory are not handled by
5051 <prgn>anacron</prgn>. Thus, you should only use this
5052 directory for jobs which may be skipped if the system is not
5056 The scripts or crontab entries in these directories should
5057 check if all necessary programs are installed before they
5058 try to execute them. Otherwise, problems will arise when a
5059 package was removed but not purged since configuration files
5060 are kept on the system in this situation.</p>
5064 <heading>Menus</heading>
5067 Menu entries should follow the current menu policy found in
5068 the <tt>menu-policy</tt> files in the <tt>debian-policy</tt>
5069 package. It may also be found on the Debian FTP site
5070 <ftpsite>ftp.debian.org</ftpsite> as the file
5071 <ftppath>/debian/doc/package-developer/menu-policy.txt.gz</ftppath>,
5072 or in the equivalent location on your local mirror.
5076 The Debian <tt>menu</tt> package provides a standard
5077 interface between packages providing applications and
5078 documents, and <em>menu programs</em> (either X window
5079 managers or text-based menu programs such as
5080 <prgn>pdmenu</prgn>).
5084 All packages that provide applications that need not be
5085 passed any special command line arguments for normal
5086 operation should register a menu entry for those
5087 applications, so that users of the <tt>menu</tt> package
5088 will automatically get menu entries in their window
5089 managers, as well in shells like <tt>pdmenu</tt>.</p>
5092 Please also refer to the <em>Debian Menu System</em>
5093 documentation that comes with the <tt>menu</tt> package for
5094 information about how to register your applications and web
5100 <heading>Multimedia handlers</heading>
5103 Packages which provide the ability to view/show/play,
5104 compose, edit or print MIME types should register themselves
5105 as such following the current MIME support policy found in
5106 the <tt>mime-policy</tt> files in the <tt>debian-policy</tt>
5107 package. It may also be found on the Debian FTP site
5108 <ftpsite>ftp.debian.org</ftpsite> as the file
5109 <ftppath>/debian/doc/package-developer/mime-policy.txt.gz</ftppath>,
5110 or in the equivalent location on your local mirror.
5114 MIME (Multipurpose Internet Mail Extensions, RFCs 2045-2049)
5115 is a mechanism for encoding files and data streams and
5116 providing meta-information about them, in particular their
5117 type (e.g. audio or video) and format (e.g. PNG, HTML,
5122 Registration of MIME type handlers allows programs like mail
5123 user agents and web browsers to to invoke these handlers to
5124 view, edit or display MIME types they don't support
5130 <heading>Keyboard configuration</heading>
5133 To achieve a consistent keyboard configuration so that all
5134 applications interpret a keyboard event the same way, all
5135 programs in the Debian distribution must be configured to
5136 comply with the following guidelines.
5140 The following keys must have the specified interpretations:
5143 <tag><tt><--</tt></tag>
5144 <item><p>delete the character to the left of the cursor</p></item>
5146 <tag><tt>Delete</tt></tag>
5147 <item><p>delete the character to the right of the cursor</p></item>
5149 <tag><tt>Control+H</tt></tag>
5150 <item><p>emacs: the help prefix</p></item>
5153 The interpretation of any keyboard events should be
5154 independent of the terminal that is used, be it a virtual
5155 console, an X terminal emulator, an rlogin/telnet session,
5160 The following list explains how the different programs
5161 should be set up to achieve this:
5166 <item><p><tt><--</tt> generates <tt>KB_Backspace</tt>
5169 <item><p><tt>Delete</tt> generates <tt>KB_Delete</tt> in
5174 X translations are set up to make
5175 <tt>KB_Backspace</tt> generate ASCII DEL, and to make
5176 <tt>KB_Delete</tt> generate <tt>ESC [ 3 ~</tt> (this
5177 is the vt220 escape code for the `delete character'
5178 key). This must be done by loading the X resources
5179 using <prgn>xrdb</prgn> on all local X displays, not
5180 using the application defaults, so that the
5181 translation resources used correspond to the
5182 <prgn>xmodmap</prgn> settings.</p></item>
5186 The Linux console is configured to make
5187 <tt><--</tt> generate DEL, and <tt>Delete</tt>
5188 generate <tt>ESC [ 3 ~</tt>.</p></item>
5192 X applications are configured so that <tt><</tt>
5193 deletes left, and <tt>Delete</tt> deletes right. Motif
5194 applications already work like this.</p></item>
5196 <item><p>Terminals should have <tt>stty erase ^?</tt> .</p></item>
5200 The <tt>xterm</tt> terminfo entry should have <tt>ESC
5201 [ 3 ~</tt> for <tt>kdch1</tt>, just as for
5202 <tt>TERM=linux</tt> and <tt>TERM=vt220</tt>.</p></item>
5206 Emacs is programmed to map <tt>KB_Backspace</tt> or
5207 the <tt>stty erase</tt> character to
5208 <tt>delete-backward-char</tt>, and <tt>KB_Delete</tt>
5209 or <tt>kdch1</tt> to <tt>delete-forward-char</tt>, and
5210 <tt>^H</tt> to <tt>help</tt> as always.</p></item>
5214 Other applications use the <tt>stty erase</tt>
5215 character and <tt>kdch1</tt> for the two delete keys,
5216 with ASCII DEL being `delete previous character' and
5217 <tt>kdch1</tt> being `delete character under
5224 This will solve the problem except for the following
5232 Some terminals have a <tt><--</tt> key that cannot
5233 be made to produce anything except <tt>^H</tt>. On
5234 these terminals Emacs help will be unavailable on
5235 <tt>^H</tt> (assuming that the <tt>stty erase</tt>
5236 character takes precedence in Emacs, and has been set
5237 correctly). <tt>M-x help</tt> or <tt>F1</tt> (if
5238 available) can be used instead.</p></item>
5242 Some operating systems use <tt>^H</tt> for <tt>stty
5243 erase</tt>. However, modern telnet versions and all
5244 rlogin versions propagate <tt>stty</tt> settings, and
5245 almost all UNIX versions honour <tt>stty erase</tt>.
5246 Where the <tt>stty</tt> settings are not propagated
5247 correctly, things can be made to work by using
5248 <tt>stty</tt> manually.</p></item>
5252 Some systems (including previous Debian versions) use
5253 <prgn>xmodmap</prgn> to arrange for both
5254 <tt><--</tt> and <tt>Delete</tt> to generate
5255 <tt>KB_Delete</tt>. We can change the behavior of
5256 their X clients using the same X resources that we use
5257 to do it for our own clients, or configure our clients
5258 using their resources when things are the other way
5259 around. On displays configured like this
5260 <tt>Delete</tt> will not work, but <tt><--</tt>
5265 Some operating systems have different <tt>kdch1</tt>
5266 settings in their <tt>terminfo</tt> database for
5267 <tt>xterm</tt> and others. On these systems the
5268 <tt>Delete</tt> key will not work correctly when you
5269 log in from a system conforming to our policy, but
5270 <tt><--</tt> will.</p></item>
5276 <heading>Environment variables</heading>
5279 A program must not depend on environment variables to get
5280 reasonable defaults. (That's because these environment
5281 variables would have to be set in a system-wide
5282 configuration file like <tt>/etc/profile</tt>, which is not
5283 supported by all shells.)</p>
5286 If a program usually depends on environment variables for its
5287 configuration, the program should be changed to fall back to
5288 a reasonable default configuration if these environment
5289 variables are not present. If this cannot be done easily
5290 (e.g., if the source code of a non-free program is not
5291 available), the program must be replaced by a small
5292 `wrapper' shell script which sets the environment variables
5293 if they are not already defined, and calls the original program.</p>
5296 Here is an example of a wrapper script for this purpose:
5298 <example compact="compact">
5300 BAR=${BAR:-/var/lib/fubar}
5302 exec /usr/lib/foo/foo "$@"
5307 Furthermore, as <tt>/etc/profile</tt> is a configuration
5308 file of the <prgn>base-files</prgn> package, other packages must not
5309 put any environment variables or other commands into that
5315 <heading>Files</heading>
5318 <heading>Binaries</heading>
5321 Two different packages must not install programs with
5322 different functionality but with the same filenames. (The
5323 case of two programs having the same functionality but
5324 different implementations is handled via `alternatives' or
5325 the `Conflicts' mechanism. See <ref id="maintscripts"> and
5326 <ref id="conflicts"> respectively.) If this case happens,
5327 one of the programs must be renamed. The maintainers should
5328 report this to the <tt>debian-devel</tt> mailing list and
5329 try to find a consensus about which program will have to be
5330 renamed. If a consensus cannot be reached, <em>both</em>
5331 programs must be renamed.
5335 Generally the following compilation parameters should be used:
5336 <example compact="compact">
5338 CFLAGS = -O2 -Wall # sane warning options vary between programs
5340 install -s # (or use strip on the files in debian/tmp)
5344 Note that by default all installed binaries should be stripped,
5345 either by using the <tt>-s</tt> flag to
5346 <prgn>install</prgn>, or by calling <prgn>strip</prgn> on
5347 the binaries after they have been copied into
5348 <tt>debian/tmp</tt> but before the tree is made into a
5352 The <tt>-N</tt> flag should not be used. On <tt>a.out</tt>
5353 systems it may have been useful for some very small
5354 binaries, but for ELF it has no good effect.</p>
5357 Debugging symbols are useful for error diagnosis,
5358 investigation of core dumps (which may be submitted by users
5359 in bug reports), or testing and developing the software.
5360 Therefore it is recommended to support building the package
5361 with debugging information through the following interface:
5362 If the environment variable <tt>DEB_BUILD_OPTIONS</tt>
5363 contains the string <tt>debug</tt>, compile the software
5364 with debugging information (usually this involves adding the
5365 <tt>-g</tt> flag to <tt>CFLAGS</tt>). This allows the
5366 generation of a build tree with debugging information. If
5367 the environment variable <tt>DEB_BUILD_OPTIONS</tt> contains
5368 the string <tt>nostrip</tt>, do not strip the files at
5369 installation time. This allows one to generate a package
5370 with debugging information included.<footnote>
5372 Rationale: Using <tt>-g</tt> by default causes wasted
5373 CPU cycles since the information is stripped away
5374 anyway; this can have a significant impact on the
5375 efficiency of the autobuilders. Having a standard way
5376 to build a debugging variant also makes it easier to
5377 build debugging bins and libraries since it provides a
5378 documented way of getting this type of build; one does
5379 not have to manually edit <tt>debian/rules</tt> or
5383 The following makefile snippet is an example of how one may
5384 test for either condition; you will probably have to massage
5385 this example in order to make it work for your package.
5386 <example compact="compact">
5389 INSTALL_FILE = $(INSTALL) -p -o root -g root -m 644
5390 INSTALL_PROGRAM = $(INSTALL) -p -o root -g root -m 755
5391 INSTALL_SCRIPT = $(INSTALL) -p -o root -g root -m 755
5392 INSTALL_DIR = $(INSTALL) -p -d -o root -g root -m 755
5394 ifneq (,$(findstring debug,$(DEB_BUILD_OPTIONS)))
5397 ifeq (,$(findstring nostrip,$(DEB_BUILD_OPTIONS)))
5398 INSTALL_PROGRAM += -s
5404 It is up to the package maintainer to decide what
5405 compilation options are best for the package. Certain
5406 binaries (such as computationally-intensive programs) will
5407 function better with certain flags (<tt>-O3</tt>, for
5408 example); feel free to use them. Please use good judgment
5409 here. Don't use flags for the sake of it; only use them
5410 if there is good reason to do so. Feel free to override
5411 the upstream author's ideas about which compilation
5412 options are best: they are often inappropriate for our
5413 environment.</p></sect>
5417 <heading>Libraries</heading>
5420 All libraries must have a shared version in the
5421 <tt>lib*</tt> package and a static version in the
5422 <tt>lib*-dev</tt> package. The shared version must be
5423 compiled with <tt>-fPIC</tt>, and the static version must
5424 not be. In other words, each <tt>*.c</tt> file will need to
5425 be compiled twice.</p>
5428 You must specify the gcc option <tt>-D_REENTRANT</tt>
5429 when building a library (either static or shared) to make
5430 the library compatible with LinuxThreads.</p>
5433 Note that all installed shared libraries should be
5435 <example compact="compact">
5436 strip --strip-unneeded <var>your-lib</var>
5438 (The option <tt>--strip-unneeded</tt> makes
5439 <prgn>strip</prgn> remove only the symbols which aren't
5440 needed for relocation processing.) Shared libraries can
5441 function perfectly well when stripped, since the symbols for
5442 dynamic linking are in a separate part of the ELF object
5445 You might also want to use the options
5446 <tt>--remove-section=.comment</tt> and
5447 <tt>--remove-section=.note</tt> on both shared libraries
5448 and executables, and <tt>--strip-debug</tt> on static
5455 Note that under some circumstances it may be useful to
5456 install a shared library unstripped, for example when
5457 building a separate package to support debugging.
5461 Shared object files (often <tt>.so</tt> files) that are not
5462 public libraries, that is, they are not meant to be linked
5463 to by third party executables (binaries of other packages),
5464 should be installed in subdirectories of the
5465 <tt>/usr/lib</tt> directory. Such files are exempt from the
5466 rules that govern ordinary shared libraries, except that
5467 they must not be installed executable and should be
5470 A common example are the so-called ``plug-ins'',
5471 internal shared objects that are dynamically loaded by
5472 programs using <manref name="dlopen" section="3">.
5478 Packages containing shared libraries that may be linked to
5479 by other packages' binaries, but which for some
5480 <em>compelling</em> reason can not be installed in
5481 <tt>/usr/lib</tt> directory, may install the shared library
5482 files in subdirectories of the <tt>/usr/lib</tt> directory,
5483 in which case they should arrange to add that directory in
5484 <tt>/etc/ld.so.conf</tt> in the package's post-installation
5485 script, and remove it in the package's post-removal script.
5489 An ever increasing number of packages are using
5490 <prgn>libtool</prgn> to do their linking. The latest GNU
5491 libtools (>= 1.3a) can take advantage of the metadata in the
5492 installed <prgn>libtool</prgn> archive files (<tt>*.la</tt>
5493 files). The main advantage of <prgn>libtool</prgn>'s
5494 <tt>.la</tt> files is that it allows <prgn>libtool</prgn> to
5495 store and subsequently access metadata with respect to the
5496 libraries it builds. <prgn>libtool</prgn> will search for
5497 those files, which contain a lot of useful information about
5498 a library (such as library dependency information for static
5499 linking). Also, they're <em>essential</em> for programs
5500 using <tt>libltdl</tt>.<footnote>
5502 Although <prgn>libtool</prgn> is fully capable of
5503 linking against shared libraries which don't have
5504 <tt>.la</tt> files, as it is a mere shell script it can
5505 add considerably to the build time of a
5506 <prgn>libtool</prgn>-using package if that shell script
5507 has to derive all this information from first principles
5508 for each library every time it is linked. With the
5509 advent of <prgn>libtool</prgn> version 1.4 (and to a
5510 lesser extent <prgn>libtool</prgn> version 1.3), the
5511 <tt>.la</tt> files also store information about
5512 inter-library dependencies which cannot necessarily be
5513 derived after the <tt>.la</tt> file is deleted.
5519 Packages that use <prgn>libtool</prgn> to create shared
5520 libraries should include the <tt>.la</tt> files in the
5521 <tt>-dev</tt> package, unless the package relies on
5522 <tt>libtool</tt>'s <tt>libltdl</tt> library, in which case
5523 the <tt>.la</tt> files must go in the run-time library
5528 You must make sure that you use only released versions of
5529 shared libraries to build your packages; otherwise other
5530 users will not be able to run your binaries
5531 properly. Producing source packages that depend on
5532 unreleased compilers is also usually a bad
5538 <heading>Shared libraries</heading>
5541 Packages involving shared libraries should be split up
5542 into several binary packages.</p>
5545 For a straightforward library which has a development
5546 environment and a runtime kit including just shared
5547 libraries you need to create two packages:
5548 <tt><var>libraryname</var><var>soversion</var></tt>, where
5549 <tt><var>soversion</var></tt> is the version number in the
5550 soname of the shared library<footnote>
5552 The soname is the shared object name: it's the thing
5553 that has to match exactly between building an executable
5554 and running it for the dynamic linker to be able run the
5555 program. For example, if the soname of the library is
5556 <tt>libfoo.so.6</tt>, the library package would be
5557 called <tt>libfoo6</tt>.
5560 and <tt><var>libraryname</var><var>soversion</var>-dev</tt>.
5564 If you prefer only to support one development version at a
5565 time you may name the development package
5566 <tt><var>libraryname</var>-dev</tt>; otherwise you may need
5567 to use <prgn>dpkg</prgn>'s Conflicts mechanism (see <ref
5568 id="conflicts">) to ensure that the user only installs one
5569 development version at a time (as different development
5570 versions are likely to have the same header files in them,
5571 which would cause a filename clash if both were installed).
5572 Typically the development version should also have an exact
5573 version dependency on the runtime library, to make sure that
5574 compilation and linking happens correctly. The
5575 <tt>${Source-Version}</tt> substitution variable can be
5576 useful for this purpose.
5580 Packages which use the shared library should have a
5581 dependency on the name of the shared library package,
5582 <tt><var>libraryname</var><var>soversion</var></tt>. When
5583 the soname changes you can have both versions of the library
5584 installed while migrating from the old library to the new.
5588 If your package has some run-time support programs which use
5589 the shared library you must not put them in the shared
5590 library package. If you do that then you won't be able to
5591 install several versions of the shared library without
5592 getting filename clashes. Instead, either create a third
5593 package for the runtime binaries (this package might
5594 typically be named <tt><var>libraryname</var>-runtime</tt>;
5595 note the absence of the <var>soversion</var> in the package
5596 name), or if the development package is small you may
5597 include them in there.
5601 If you have several shared libraries built from the same
5602 source tree you may lump them all together into a single
5603 shared library package, provided that you change all of
5604 their sonames at once (so that you don't get filename
5605 clashes if you try to install different versions of the
5606 combined shared libraries package).
5610 Shared libraries should not be installed executable, since
5611 the dynamic linker does not require this and trying to
5612 execute a shared library usually results in a core dump.
5617 <heading>Scripts</heading>
5620 All command scripts, including the package maintainer
5621 scripts inside the package and used by <prgn>dpkg</prgn>,
5622 should have a <tt>#!</tt> line naming the shell to be used
5623 to interpret them.</p>
5626 In the case of Perl scripts this should be
5627 <tt>#!/usr/bin/perl</tt>.</p>
5630 Shell scripts (<prgn>sh</prgn> and <prgn>bash</prgn>)
5631 should almost certainly start with <tt>set -e</tt> so that
5632 errors are detected. Every script should use
5633 <tt>set -e</tt> or check the exit status of <em>every</em>
5637 The standard shell interpreter <tt>/bin/sh</tt> can be a
5638 symbolic link to any POSIX compatible shell, if <tt>echo
5639 -n</tt> does not generate a newline.<footnote>
5641 Debian policy specifies POSIX behavior for
5642 <tt>/bin/sh</tt>, but <tt>echo -n</tt> has widespread
5643 use in the Linux community (in particular including this
5644 policy, the Linux kernel source, many Debian scripts,
5645 etc.). This <tt>echo -n</tt> mechanism is valid but not
5646 required under POSIX, hence this explicit addition.
5647 Also, rumour has it that this shall be mandated under
5651 Thus, shell scripts specifying <tt>/bin/sh</tt> as
5652 interpreter should only use POSIX features. If a script
5653 requires non-POSIX features from the shell interpreter, the
5654 appropriate shell must be specified in the first line of the
5655 script (e.g., <tt>#!/bin/bash</tt>) and the package must
5656 depend on the package providing the shell (unless the shell
5657 package is marked `Essential', as in the case of
5662 You may wish to restrict your script to POSIX features when
5663 possible so that it may use <tt>/bin/sh</tt> as its
5664 interpreter. If your script works with <prgn>ash</prgn>,
5665 it's probably POSIX compliant, but if you are in doubt, use
5670 Perl scripts should check for errors when making any
5671 system calls, including <tt>open</tt>, <tt>print</tt>,
5672 <tt>close</tt>, <tt>rename</tt> and <tt>system</tt>.
5676 <prgn>csh</prgn> and <prgn>tcsh</prgn> should be avoided as
5677 scripting languages. See <em>Csh Programming Considered
5678 Harmful</em>, one of the <tt>comp.unix.*</tt> FAQs, which
5679 can be found at <url
5680 id="http://language.perl.com/versus/csh.whynot">.<footnote>
5682 It can also be found on
5683 <url id="http://www.cpan.org/doc/FMTEYEWTK/versus/csh.whynot">
5684 or on the ftp site <ftpsite>ftp.cpan.org</ftpsite> as
5685 <ftppath>/pub/perl/CPAN/doc/FMTEYEWTK/versus/csh.whynot</ftppath>.
5688 If an upstream package comes with <prgn>csh</prgn> scripts
5689 then you must make sure that they start with
5690 <tt>#!/bin/csh</tt> and make your package depend on the
5691 <prgn>c-shell</prgn> virtual package.
5695 Any scripts which create files in world-writeable
5696 directories (e.g., in <tt>/tmp</tt>) must use a
5697 mechanism which will fail if a file with the same name
5701 The Debian base system provides the <prgn>tempfile</prgn>
5702 and <prgn>mktemp</prgn> utilities for use by scripts for
5703 this purpose.</p></sect>
5707 <heading>Symbolic links</heading>
5710 In general, symbolic links within a top-level directory
5711 should be relative, and symbolic links pointing from one
5712 top-level directory into another should be absolute. (A
5713 top-level directory is a sub-directory of the root
5714 directory <tt>/</tt>.)</p>
5717 In addition, symbolic links should be specified as short as
5718 possible, i.e., link targets like <tt>foo/../bar</tt> are
5722 Note that when creating a relative link using
5723 <prgn>ln</prgn> it is not necessary for the target of the
5724 link to exist relative to the working directory you're
5725 running <prgn>ln</prgn> from, nor is it necessary to change
5726 directory to the directory where the link is to be made.
5727 Simply include the string that should appear as the target
5728 of the link (this will be a pathname relative to the
5729 directory in which the link resides) as the first argument
5730 to <prgn>ln</prgn>.</p>
5733 For example, in your <prgn>Makefile</prgn> or
5734 <tt>debian/rules</tt>, you can do things like:
5735 <example compact="compact">
5736 ln -fs gcc $(prefix)/bin/cc
5737 ln -fs gcc debian/tmp/usr/bin/cc
5738 ln -fs ../sbin/sendmail $(prefix)/bin/runq
5739 ln -fs ../sbin/sendmail debian/tmp/usr/bin/runq
5743 A symbolic link pointing to a compressed file should always
5744 have the same file extension as the referenced file. (For
5745 example, if a file <tt>foo.gz</tt> is referenced by a
5746 symbolic link, the filename of the link has to end with
5747 `<tt>.gz</tt>' too, as in <tt>bar.gz</tt>.)
5752 <heading>Device files</heading>
5755 Packages must not include device files in the package file
5759 If a package needs any special device files that are not
5760 included in the base system, it must call
5761 <prgn>MAKEDEV</prgn> in the <prgn>postinst</prgn> script,
5762 after asking the user for permission to do so.</p>
5765 Packages must not remove any device files in the
5766 <prgn>postrm</prgn> or any other script. This is left to the
5767 system administrator.</p>
5770 Debian uses the serial devices
5771 <tt>/dev/ttyS*</tt>. Programs using the old
5772 <tt>/dev/cu*</tt> devices should be changed to use
5773 <tt>/dev/ttyS*</tt>.</p>
5776 <sect id="config files">
5777 <heading>Configuration files</heading>
5779 <heading>Definitions</heading>
5782 <tag>configuration file</tag>
5785 A file that affects the operation of a program, or
5786 provides site- or host-specific information, or
5787 otherwise customizes the behavior of a program.
5788 Typically, configuration files are intended to be
5789 modified by the system administrator (if needed or
5790 desired) to conform to local policy or to provide
5791 more useful site-specific behavior.
5795 <tag><tt>conffile</tt></tag>
5798 A file listed in a package's <tt>conffiles</tt>
5799 file, and is treated specially by <prgn>dpkg</prgn>
5800 (see <ref id="configdetails">).
5807 The distinction between these two is important; they are
5808 not interchangeable concepts. Almost all
5809 <tt>conffile</tt>s are configuration files, but many
5810 configuration files are not <tt>conffiles</tt>.
5814 Note that a script that embeds configuration information
5815 (such as most of the files in <tt>/etc/default</tt> and
5816 <tt>/etc/cron.{daily,weekly,monthly}</tt>) is de-facto a
5817 configuration file and should be treated as such.
5822 <heading>Location</heading>
5824 Any configuration files created or used by your package
5825 must reside in <tt>/etc</tt>. If there are several you
5826 should consider creating a subdirectory of <tt>/etc</tt>
5827 named after your package.</p>
5830 If your package creates or uses configuration files
5831 outside of <tt>/etc</tt>, and it is not feasible to modify
5832 the package to use the <tt>/etc</tt>, you should still put
5833 the files in <tt>/etc</tt> and create symbolic links to
5834 those files from the location that the package
5839 <heading>Behavior</heading>
5841 Configuration file handling must conform to the following
5843 <list compact="compact">
5846 local changes must be preserved during a package
5852 configuration files must be preserved when the
5853 package is removed, and only deleted when the
5861 The easy way to achieve this behavior is to make the
5862 configuration file a <tt>conffile</tt>. This is
5863 appropriate only if it is possible to distribute a default
5864 version that will work for most installations, although
5865 some system administrators may choose to modify it. This
5866 implies that the default version will be part of the
5867 package distribution, and must not be modified by the
5868 maintainer scripts during installation (or at any other
5873 In order to ensure that local changes are preserved
5874 correctly, no package may contain or make hard links to
5875 conffiles.<footnote>
5877 Rationale: There are two problems with hard links.
5878 The first is that some editors break the link while
5879 editing one of the files, so that the two files may
5880 unwittingly become unlinked and different. The second
5881 is that <prgn>dpkg</prgn> might break the hard link
5882 while upgrading <tt>conffile</tt>s.
5888 The other way to do it is via the maintainer scripts. In
5889 this case, the configuration file must not be listed as a
5890 <tt>conffile</tt> and must not be part of the package
5891 distribution. If the existence of a file is required for
5892 the package to be sensibly configured it is the
5893 responsibility of the package maintainer to provide
5894 maintainer scripts which correctly create, update and
5895 maintain the file and remove it on purge. (See <ref
5896 id="maintainerscripts"> for more information.) These
5897 scripts must be idempotent (i.e., must work correctly if
5898 <prgn>dpkg</prgn> needs to re-run them due to errors
5899 during installation or removal), must cope with all the
5900 variety of ways <prgn>dpkg</prgn> can call maintainer
5901 scripts, must not overwrite or otherwise mangle the user's
5902 configuration without asking, must not ask unnecessary
5903 questions (particularly during upgrades), and otherwise be
5908 The scripts are not required to configure every possible
5909 option for the package, but only those necessary to get
5910 the package running on a given system. Ideally the
5911 sysadmin should not have to do any configuration other
5912 than that done (semi-)automatically by the
5913 <prgn>postinst</prgn> script.
5917 A common practice is to create a script called
5918 <tt><var>package</var>-configure</tt> and have the
5919 package's <prgn>postinst</prgn> call it if and only if the
5920 configuration file does not already exist. In certain
5921 cases it is useful for there to be an example or template
5922 file which the maintainer scripts use. Such files should
5923 be in <tt>/usr/share/<var>package</var></tt> or
5924 <tt>/usr/lib/<var>package</var></tt> (depending on whether
5925 they are architecture-independent or not). There should
5926 be symbolic links to them from
5927 <tt>/usr/share/doc/<var>package</var>/examples</tt> if
5928 they are examples, and should be perfectly ordinary
5929 <prgn>dpkg</prgn>-handled files (<em>not</em>
5930 configuration files).
5934 These two styles of configuration file handling must
5935 not be mixed, for that way lies madness:
5936 <prgn>dpkg</prgn> will ask about overwriting the file
5937 every time the package is upgraded.
5942 <heading>Sharing configuration files</heading>
5944 Packages which specify the same file as a
5945 <tt>conffile</tt> must be tagged as <em>conflicting</em>
5946 with each other. (This is an instance of the general rule
5947 about not sharing files. Note that neither alternatives
5948 nor diversions are likely to be appropriate in this case;
5949 in particular, <prgn>dpkg</prgn> does not handle diverted
5950 <tt>conffile</tt>s well.)
5954 The maintainer scripts must not alter a <tt>conffile</tt>
5955 of <em>any</em> package, including the one the scripts
5960 If two or more packages use the same configuration file
5961 and it is reasonable for both to be installed at the same
5962 time, one of these packages must be defined as
5963 <em>owner</em> of the configuration file, i.e., it will be
5964 the package which handles that file as a configuration
5965 file. Other packages that use the configuration file must
5966 depend on the owning package if they require the
5967 configuration file to operate. If the other package will
5968 use the configuration file if present, but is capable of
5969 operating without it, no dependency need be declared.</p>
5972 If it is desirable for two or more related packages to
5973 share a configuration file <em>and</em> for all of the
5974 related packages to be able to modify that configuration
5975 file, then the following should be done:
5976 <enumlist compact="compact">
5979 One of the related packages (the "owning" package)
5980 will manage the configuration file with maintainer
5981 scripts as described in the previous section.
5986 The owning package should also provide a program
5987 that the other packages may use to modify the
5993 The related packages must use the provided program
5994 to make any desired modifications to the
5995 configuration file. They should either depend on
5996 the core package to guarantee that the configuration
5997 modifier program is available or accept gracefully
5998 that they cannot modify the configuration file if it
5999 is not. (This is in addition to the fact that the
6000 configuration file may not even be present in the
6008 Sometimes it's appropriate to create a new package which
6009 provides the basic infrastructure for the other packages
6010 and which manages the shared configuration files. (The
6011 <tt>sgml-base</tt> package is a good example.)
6016 <heading>User configuration files ("dotfiles")</heading>
6019 The files in <tt>/etc/skel</tt> will automatically be
6020 copied into new user accounts by <prgn>adduser</prgn>.
6021 No other program should reference the files in
6026 Therefore, if a program needs a dotfile to exist in
6027 advance in <tt>$HOME</tt> to work sensibly, that dotfile
6028 should be installed in <tt>/etc/skel</tt> and treated as a
6033 However, programs that require dotfiles in order to
6034 operate sensibly (dotfiles that they do not create
6035 themselves automatically, that is) are a bad thing.
6036 Furthermore, programs should be configured by the Debian
6037 default installation to behave as closely to the upstream
6038 default behaviour as possible.
6042 Therefore, if a program in a Debian package needs to be
6043 configured in some way in order to operate sensibly, that
6044 should be done using a site-wide configuration file placed
6045 in <tt>/etc</tt>. Only if the program doesn't support a
6046 site-wide default configuration and the package maintainer
6047 doesn't have time to add it may a default per-user file be
6048 placed in <tt>/etc/skel</tt>.
6052 <tt>/etc/skel</tt> should be as empty as we can make it.
6053 This is particularly true because there is no easy (or
6054 necessarily desirable) mechanism for ensuring that the
6055 appropriate dotfiles are copied into the accounts of
6056 existing users when a package is installed.
6062 <heading>Log files</heading>
6064 Log files should usually be named
6065 <tt>/var/log/<var>package</var>.log</tt>. If you have many
6066 log files, or need a separate directory for permission
6067 reasons (<tt>/var/log</tt> is writable only by
6068 <tt>root</tt>), you should usually create a directory named
6069 <tt>/var/log/<var>package</var></tt> and place your log
6074 Log files must be rotated occasionally so that they don't
6075 grow indefinitely; the best way to do this is to drop a log
6076 rotation configuration file into the directory
6077 <tt>/etc/logrotate.d</tt> and use the facilities provided by
6078 logrotate.<footnote>
6080 The traditional approach to log files has been to set up
6081 <em>ad hoc</em> log rotation schemes using simple shell
6082 scripts and cron. While this approach is highly
6083 customizable, it requires quite a lot of sysadmin work.
6084 Even though the original Debian system helped a little
6085 by automatically installing a system which can be used
6086 as a template, this was deemed not enough.
6090 The use of <prgn>logrotate</prgn>, a program developed
6091 by Red Hat, is better, as it centralizes log management.
6092 It has both a configuration file
6093 (<tt>/etc/logrotate.conf</tt>) and a directory where
6094 packages can drop their individual log rotation
6095 configurations (<tt>/etc/logrotate.d</tt>).
6098 Here is a good example for a logrotate config
6099 file (for more information see <manref name="logrotate"
6101 <example compact="compact">
6107 /etc/init.d/foo force-reload
6111 This rotates all files under <tt>/var/log/foo</tt>, saves 12
6112 compressed generations, and forces the daemon to reload its
6113 configuration information after the log rotation.
6117 Log files should be removed when the package is
6118 purged (but not when it is only removed). This should be
6119 done by the <prgn>postrm</prgn> script when it is called
6120 with the argument <tt>purge</tt> (see <ref
6121 id="removedetails">).
6126 <heading>Permissions and owners</heading>
6129 The rules in this section are guidelines for general use.
6130 If necessary you may deviate from the details below.
6131 However, if you do so you must make sure that what is done
6132 is secure and you should try to be as consistent as possible
6133 with the rest of the system. You should probably also
6134 discuss it on <prgn>debian-devel</prgn> first.
6138 Files should be owned by <tt>root.root</tt>, and made
6139 writable only by the owner and universally readable (and
6140 executable, if appropriate), that is mode 644 or 755.
6144 Directories should be mode 755 or (for group-writability)
6145 mode 2775. The ownership of the directory should be
6146 consistent with its mode: if a directory is mode 2775, it
6147 should be owned by the group that needs write access to
6152 Setuid and setgid executables should be mode 4755 or 2755
6153 respectively, and owned by the appropriate user or group.
6154 They should not be made unreadable (modes like 4711 or
6155 2711 or even 4111); doing so achieves no extra security,
6156 because anyone can find the binary in the freely available
6157 Debian package; it is merely inconvenient. For the same
6158 reason you should not restrict read or execute permissions
6159 on non-set-id executables.
6163 Some setuid programs need to be restricted to particular
6164 sets of users, using file permissions. In this case they
6165 should be owned by the uid to which they are set-id, and by
6166 the group which should be allowed to execute them. They
6167 should have mode 4754; again there is no point in making
6168 them unreadable to those users who must not be allowed to
6173 It is possible to arrange that the system administrator can
6174 reconfigure the package to correspond to their local
6175 security policy by changing the permissions on a binary:
6176 they can do this by using <prgn>dpkg-statoverride</prgn>, as
6177 described below.<footnote>
6179 Ordinary files installed by <prgn>dpkg</prgn> (as
6180 opposed to <tt>conffile</tt>s and other similar objects)
6181 normally have their permissions reset to the distributed
6182 permissions when the package is reinstalled. However,
6183 the use of <prgn>dpkg-statoverride</prgn> overrides this
6184 default behaviour. If you use this method, you should
6185 remember to describe <prgn>dpkg-statoverride</prgn> in
6186 the package documentation; being a relatively new
6187 addition to Debian, it is probably not yet well-known.
6190 Another method you should consider is to create a group for
6191 people allowed to use the program(s) and make any setuid
6192 executables executable only by that group.
6196 If you need to create a new user or group for your package
6197 there are two possibilities. Firstly, you may need to
6198 make some files in the binary package be owned by this
6199 user or group, or you may need to compile the user or
6200 group id (rather than just the name) into the binary
6201 (though this latter should be avoided if possible, as in
6202 this case you need a statically allocated id).</p>
6205 If you need a statically allocated id, you must ask for a
6206 user or group id from the <tt>base-passwd</tt> maintainer,
6207 and must not release the package until you have been
6208 allocated one. Once you have been allocated one you must
6209 either make the package depend on a version of the
6210 <tt>base-passwd</tt> package with the id present in
6211 <tt>/etc/passwd</tt> or <tt>/etc/group</tt>, or arrange for
6212 your package to create the user or group itself with the
6213 correct id (using <tt>adduser</tt>) in its
6214 <prgn>preinst</prgn> or <prgn>postinst</prgn>. (Doing it in
6215 the <prgn>postinst</prgn> is to be preferred if it is
6216 possible, otherwise a pre-dependency will be needed on the
6217 <tt>adduser</tt> package.)
6221 On the other hand, the program might be able to determine
6222 the uid or gid from the user or group name at runtime, so
6223 that a dynamically allocated id can be used. In this case
6224 you should choose an appropriate user or group name,
6225 discussing this on <prgn>debian-devel</prgn> and checking
6226 with the base system maintainer that it is unique and that
6227 they do not wish you to use a statically allocated id
6228 instead. When this has been checked you must arrange for
6229 your package to create the user or group if necessary using
6230 <prgn>adduser</prgn> in the <prgn>preinst</prgn> or
6231 <prgn>postinst</prgn> script (again, the latter is to be
6232 preferred if it is possible).
6236 Note that changing the numeric value of an id associated
6237 with a name is very difficult, and involves searching the
6238 file system for all appropriate files. You need to think
6239 carefully whether a static or dynamic id is required, since
6240 changing your mind later will cause problems.
6243 <sect1><heading>The use of <prgn>dpkg-statoverride</prgn></heading>
6245 This section is not intended as policy, but as a
6246 description of the use of <prgn>dpkg-statoverride</prgn>.
6250 <prgn>dpkg-statoverride</prgn> is a replacement for the
6251 deprecated <tt>suidmanager</tt> package. Packages which
6252 previously used <tt>suidmanager</tt> should have a
6253 <tt>Conflicts: suidmanager (<< 0.50)</tt> entry (or even
6254 <tt>(<< 0.52)</tt>), and calls to <tt>suidregister</tt>
6255 and <tt>suidunregister</tt> should now be simply removed
6256 from the maintainer scripts.
6260 If a system administrator wishes to have a file (or
6261 directory or other such thing) installed with owner and
6262 permissions different from those in the distributed Debian
6263 package, he can use the <prgn>dpkg-statoverride</prgn>
6264 program to instruct <prgn>dpkg</prgn> to use the different
6265 settings every time the file is installed. Thus the
6266 package maintainer should distribute the files with their
6267 normal permissions, and leave it for the system
6268 administrator to make any desired changes. For example, a
6269 daemon which is normally required to be setuid root, but
6270 in certain situations could be used without being setuid,
6271 should be installed setuid in the <tt>.deb</tt>. Then the
6272 local system administrator can change this if they wish.
6273 If there are two standard ways of doing it, the package
6274 maintainer can use <tt>debconf</tt> to find out the
6275 preference, and call <prgn>dpkg-statoverride</prgn> in the
6276 maintainer script if necessary to accommodate the system
6277 administrator's choice.
6281 Given the above, <prgn>dpkg-statoverride</prgn> is
6282 essentially a tool for system administrators and would not
6283 normally be needed in the maintainer scripts. There is
6284 one type of situation, though, where calls to
6285 <prgn>dpkg-statoverride</prgn> would be needed in the
6286 maintainer scripts, and that involves packages which use
6287 dynamically allocated user or group ids. In such a
6288 situation, something like the following idiom can be very
6289 helpful in the package's <prgn>postinst</prgn>, where
6290 <tt>sysuser</tt> is a dynamically allocated id:
6292 for i in /usr/bin/foo /usr/sbin/bar
6294 if ! dpkg-statoverride --list $i >/dev/null
6296 dpkg-statoverride --update --add sysuser root 4755 $i
6300 The corresponding <tt>dpkg-statoverride --remove</tt>
6301 calls can then be made unconditionally when the package is
6308 <chapt id="customized-programs">
6309 <heading>Customized programs</heading>
6311 <sect id="arch-spec">
6312 <heading>Architecture specification strings</heading>
6315 If a program needs to specify an <em>architecture specification
6316 string</em> in some place, the following format should be
6317 used: <var>arch</var>-<var>os</var><footnote>
6319 The following architectures and operating systems are
6320 currently recognised by <prgn>dpkg-archictecture</prgn>.
6321 The architecture, <tt><var>arch</var></tt>, is one of
6322 the following: <tt>alpha</tt>, <tt>arm</tt>,
6323 <tt>hppa</tt>, <tt>i386</tt>, <tt>ia64</tt>,
6324 <tt>m68k</tt>, <tt>mips</tt>, <tt>mipsel</tt>,
6325 <tt>powerpc</tt>, <tt>s390</tt>, <tt>sh</tt>,
6326 <tt>sheb</tt>, <tt>sparc</tt> and <tt>sparc64</tt>. The
6327 operating system, <tt><var>os</var></tt>, is one of:
6328 <tt>linux</tt>, <tt>gnu</tt>, <tt>freebsd</tt> and
6329 <tt>openbsd</tt>. Use of <tt>gnu</tt> in this string is
6330 reserved for the GNU/Hurd operating system.
6336 Note that we don't want to use
6337 <tt><var>arch</var>-debian-linux</tt> to apply to the rule
6338 <tt><var>architecture</var>-<var>vendor</var>-<var>os</var></tt>
6339 since this would make our programs incompatible with other
6340 Linux distributions. We also don't use something like
6341 <tt><var>arch</var>-unknown-linux</tt>, since the
6342 <tt>unknown</tt> does not look very good.
6347 <heading>Daemons</heading>
6350 The configuration files <tt>/etc/services</tt>,
6351 <tt>/etc/protocols</tt>, and <tt>/etc/rpc</tt> are managed
6352 by the <prgn>netbase</prgn> package and must not be modified
6357 If a package requires a new entry in one of these files, the
6358 maintainer should get in contact with the
6359 <prgn>netbase</prgn> maintainer, who will add the entries
6360 and release a new version of the <prgn>netbase</prgn>
6365 The configuration file <tt>/etc/inetd.conf</tt> must not be
6366 modified by the package's scripts except via the
6367 <prgn>update-inetd</prgn> script or the
6368 <tt>DebianNet.pm</tt> Perl module. See their documentation
6369 for details on how to add entries.
6373 If a package wants to install an example entry into
6374 <tt>/etc/inetd.conf</tt>, the entry must be preceded with
6375 exactly one hash character (<tt>#</tt>). Such lines are
6376 treated as `commented out by user' by the
6377 <prgn>update-inetd</prgn> script and are not changed or
6378 activated during package updates.
6383 <heading>Using pseudo-ttys and modifying wtmp, utmp and
6387 Some programs need to create pseudo-ttys. This should be done
6388 using Unix98 ptys if the C library supports it. The resulting
6389 program must not be installed setuid root, unless that
6390 is required for other functionality.
6394 The files <tt>/var/run/utmp</tt>, <tt>/var/log/wtmp</tt> and
6395 <tt>/var/log/lastlog</tt> must be installed writeable by
6396 group <tt>utmp</tt>. Programs which need to modify those
6397 files must be installed setgid <tt>utmp</tt>.
6402 <heading>Editors and pagers</heading>
6405 Some programs have the ability to launch an editor or pager
6406 program to edit or display a text document. Since there are
6407 lots of different editors and pagers available in the Debian
6408 distribution, the system administrator and each user should
6409 have the possibility to choose his/her preferred editor and
6414 In addition, every program should choose a good default
6415 editor/pager if none is selected by the user or system
6420 Thus, every program that launches an editor or pager must
6421 use the EDITOR or PAGER environment variable to determine
6422 the editor or pager the user wishes to use. If these
6423 variables are not set, the programs <tt>/usr/bin/editor</tt>
6424 and <tt>/usr/bin/pager</tt> should be used, respectively.
6428 These two files are managed through the <prgn>dpkg</prgn>
6429 `alternatives' mechanism. Thus every package providing an
6430 editor or pager must call the
6431 <prgn>update-alternatives</prgn> script to register these
6436 If it is very hard to adapt a program to make use of the
6437 EDITOR or PAGER variables, that program may be configured to
6438 use <tt>/usr/bin/sensible-editor</tt> and
6439 <tt>/usr/bin/sensible-pager</tt> as the editor or pager
6440 program respectively. These are two scripts provided in the
6441 Debian base system that check the EDITOR and PAGER variables
6442 and launch the appropriate program, and fall back to
6443 <tt>/usr/bin/editor</tt> and <tt>/usr/bin/pager</tt> if the
6444 variable is not set.
6448 A program may also use the VISUAL environment variable to
6449 determine the user's choice of editor. If it exists, it
6450 should take precedence over EDITOR. This is in fact what
6451 <tt>/usr/bin/sensible-editor</tt> does.
6455 It is not required for a package to depend on
6456 <tt>editor</tt> and <tt>pager</tt>, nor is it required for a
6457 package to provide such virtual packages.<footnote>
6459 The Debian base system already provides an editor and a
6466 <sect id="web-appl">
6467 <heading>Web servers and applications</heading>
6470 This section describes the locations and URLs that should
6471 be used by all web servers and web applications in the
6479 Cgi-bin executable files are installed in the
6481 <example compact="compact">
6482 /usr/lib/cgi-bin/<var>cgi-bin-name</var>
6484 and should be referred to as
6485 <example compact="compact">
6486 http://localhost/cgi-bin/<var>cgi-bin-name</var>
6491 <item><p>Access to HTML documents</p>
6494 HTML documents for a package are stored in
6495 <tt>/usr/share/doc/<var>package</var></tt>
6496 and can be referred to as
6497 <example compact="compact">
6498 http://localhost/doc/<var>package</var>/<var>filename</var>
6502 The web server should restrict access to the document
6503 tree so that only clients on the same host can read
6504 the documents. If the web server does not support such
6505 access controls, then it should not provide access at
6506 all, or ask about providing access during installation.
6510 <item><p>Web Document Root</p>
6513 Web Applications should try to avoid storing files in
6514 the Web Document Root. Instead they should use the
6515 /usr/share/doc/<var>package</var> directory for
6516 documents and register the Web Application via the
6517 menu package. If access to the web document root is
6518 unavoidable then use
6519 <example compact="compact">
6522 as the Document Root. This might be just a symbolic
6523 link to the location where the system administrator
6524 has put the real document root.
6528 </enumlist></p></sect>
6531 <sect id="mail-transport-agents">
6532 <heading>Mail transport, delivery and user agents</heading>
6535 Debian packages which process electronic mail, whether mail
6536 user agents (MUAs) or mail transport agents (MTAs), must
6537 ensure that they are compatible with the configuration
6538 decisions below. Failure to do this may result in lost
6539 mail, broken <tt>From:</tt> lines, and other serious brain
6544 The mail spool is <tt>/var/mail</tt> and the interface to
6545 send a mail message is <tt>/usr/sbin/sendmail</tt> (as per
6546 the FHS). On older systems, the mail spool may be
6547 physically located in <tt>/var/spool/mail</tt>, but all
6548 access to the mail spool should be via the
6549 <tt>/var/mail</tt> symlink. The mail spool is part of the
6550 base system and not part of the MTA package.
6554 All Debian MUAs, MTAs, MDAs and other mailbox accessing
6555 programs (such as IMAP daemons) must lock the mailbox in an
6556 NFS-safe way. This means that <tt>fcntl()</tt> locking must
6557 be combined with dot locking. To avoid deadlocks, a program
6558 should use <tt>fcntl()</tt> first and dot locking after
6559 this, or alternatively implement the two locking methods in
6560 a non blocking way<footnote>
6562 If it is not possible to establish both locks, the
6563 system shouldn't wait for the second lock to be
6564 established, but remove the first lock, wait a (random)
6565 time, and start over locking again.
6567 </footnote>. Using the functions <tt>maillock</tt> and
6568 <tt>mailunlock</tt> provided by the
6569 <tt>liblockfile*</tt><footnote>
6571 You will need to depend on <tt>liblockfile1
6572 (>>1.01)</tt> to use these functions.
6574 </footnote> packages is the recommended way to realize this.
6578 Mailboxes are generally mode 660
6579 <tt><var>user</var>.mail</tt> unless the system
6580 administrator has chosen otherwise. A MUA may remove a
6581 mailbox (unless it has nonstandard permissions) in which
6582 case the MTA or another MUA must recreate it if needed.
6583 Mailboxes must be writable by group mail.
6587 The mail spool is 2775 <tt>root.mail</tt>, and MUAs should
6588 be setgid mail to do the locking mentioned above (and
6589 must obviously avoid accessing other users' mailboxes
6590 using this privilege).</p>
6593 <tt>/etc/aliases</tt> is the source file for the system mail
6594 aliases (e.g., postmaster, usenet, etc.), it is the one
6595 which the sysadmin and <prgn>postinst</prgn> scripts may
6596 edit. After <tt>/etc/aliases</tt> is edited the program or
6597 human editing it must call <prgn>newaliases</prgn>. All MTA
6598 packages must come with a <prgn>newaliases</prgn> program,
6599 even if it does nothing, but older MTA packages did not do
6600 this so programs should not fail if <prgn>newaliases</prgn>
6601 cannot be found. Note that because of this, all MTA
6602 packages must have <tt>Provides</tt>, <tt>Conflicts</tt> and
6603 <tt>Replaces: mail-transport-agent</tt> control file
6608 The convention of writing <tt>forward to
6609 <var>address</var></tt> in the mailbox itself is not
6610 supported. Use a <tt>.forward</tt> file instead.</p>
6613 The <prgn>rmail</prgn> program used by UUCP
6614 for incoming mail should be <tt>/usr/sbin/rmail</tt>.
6615 Likewise, <prgn>rsmtp</prgn>, for receiving
6616 batch-SMTP-over-UUCP, should be <tt>/usr/sbin/rsmtp</tt> if it
6620 If your package needs to know what hostname to use on (for
6621 example) outgoing news and mail messages which are generated
6622 locally, you should use the file <tt>/etc/mailname</tt>. It
6623 will contain the portion after the username and <tt>@</tt>
6624 (at) sign for email addresses of users on the machine
6625 (followed by a newline).
6629 Such package should check for the existence of this file
6630 when it is being configured. If it exists, it should be
6631 used without comment, although an MTA's configuration script
6632 may wish to prompt the user even if it finds that this file
6633 exists. If the file does not exist, the package should
6634 prompt the user for the value (preferably using
6635 <prgn>debconf</prgn>) and store it in <tt>/etc/mailname</tt>
6636 as well as using it in the package's configuration. The
6637 prompt should make it clear that the name will not just be
6638 used by that package. For example, in this situation the
6639 <tt>inn</tt> package could say something like:
6640 <example compact="compact">
6641 Please enter the `mail name' of your system. This is the
6642 hostname portion of the address to be shown on outgoing
6643 news and mail messages. The default is
6644 <var>syshostname</var>, your system's host name. Mail
6645 name [`<var>syshostname</var>']:
6647 where <var>syshostname</var> is the output of <tt>hostname
6653 <heading>News system configuration</heading>
6656 All the configuration files related to the NNTP (news)
6657 servers and clients should be located under
6658 <tt>/etc/news</tt>.</p>
6661 There are some configuration issues that apply to a number
6662 of news clients and server packages on the machine. These
6666 <tag><tt>/etc/news/organization</tt></tag>
6667 <item><p>A string which should appear as the
6668 organization header for all messages posted
6669 by NNTP clients on the machine</p></item>
6671 <tag><tt>/etc/news/server</tt></tag>
6672 <item><p>Contains the FQDN of the upstream NNTP
6673 server, or localhost if the local machine is
6674 an NNTP server.</p></item>
6677 Other global files may be added as required for cross-package news
6678 configuration.</p></sect>
6682 <heading>Programs for the X Window System</heading>
6685 <heading>Providing X support and package priorities</heading>
6688 Programs that can be configured with support for the X
6689 Window System must be configured to do so and must declare
6690 any package dependencies necessary to satisfy their
6691 runtime requirements when using the X Window System. If
6692 such a package is of higher priority than the X packages
6693 on which it depends, it is required that either the
6694 X-specific components be split into a separate package, or
6695 that an alternative version of the package, which includes
6696 X support, be provided, or that the package's priority be
6702 <heading>Packages providing an X server</heading>
6705 Packages that provide an X server that, directly or
6706 indirectly, communicates with real input and display
6707 hardware should declare in their control data that they
6708 provide the virtual package <tt>xserver</tt>.<footnote>
6710 This implements current practice, and provides an
6711 actual policy for usage of the <tt>xserver</tt>
6712 virtual package which appears in the virtual packages
6713 list. In a nutshell, X servers that interface
6714 directly with the display and input hardware or via
6715 another subsystem (e.g., GGI) should provide
6716 <tt>xserver</tt>. Things like <tt>Xvfb</tt>,
6717 <tt>Xnest</tt>, and <tt>Xprt</tt> should not.
6724 <heading>Packages providing a terminal emulator</heading>
6727 Packages that provide a terminal emulator for the X Window
6728 System which meet the criteria listed below should declare
6729 in their control data that they provide the virtual
6730 package <tt>x-terminal-emulator</tt>. They should also
6731 register themselves as an alternative for
6732 <tt>/usr/bin/x-terminal-emulator</tt>, with a priority of
6737 To be an <tt>x-terminal-emulator</tt>, a program must:
6738 <list compact="compact">
6740 Be able to emulate a DEC VT100 terminal, or a
6741 compatible terminal.
6745 Support the command-line option <tt>-e
6746 <var>command</var></tt>, which creates a new
6747 terminal window<footnote>
6749 "New terminal window" does not necessarily mean
6750 a new top-level X window directly parented by
6751 the window manager; it could, if the terminal
6752 emulator application were so coded, be a new
6753 "view" in a multiple-document interface (MDI).
6756 and runs the specified <var>command</var>.
6760 Support the command-line option <tt>-T
6761 <var>title</var></tt>, which creates a new terminal
6762 window with the window title <var>title</var>.
6769 <heading>Packages providing a window manager</heading>
6772 Packages that provide a window manager should declare in
6773 their control data that they provide the virtual package
6774 <tt>x-window-manager</tt>. They should also register
6775 themselves as an alternative for
6776 <tt>/usr/bin/x-window-manager</tt>, with a priority
6777 calculated as follows:
6778 <list compact="compact">
6779 <item><p>Start with a priority of 20.</p></item>
6783 If the window manager supports the Debian menu
6784 system, add 20 points if this support is available
6785 in the package's default configuration (i.e., no
6786 configuration files belonging to the system or user
6787 have to be edited to activate the feature); if
6788 configuration files must be modified, add only 10
6795 If the window manager permits the X session to be
6796 restarted using a <em>different</em> window manager
6797 (without killing the X server) in its default
6798 configuration, add 10 points; otherwise add none.
6806 <heading>Packages providing fonts</heading>
6809 Packages that provide fonts for the X Window
6812 For the purposes of Debian Policy, a "font for the X
6813 Window System" is one which is accessed via X protocol
6814 requests. Fonts for the Linux console, for PostScript
6815 renderers, or any other purpose, do not fit this
6816 definition. Any tool which makes such fonts available
6817 to the X Window System, however, must abide by this
6821 must do a number of things to ensure that they are both
6822 available without modification of the X or font server
6823 configuration, and that they do not corrupt files used by
6824 other font packages to register information about
6829 Fonts of any type supported by the X Window System
6830 must be be in a separate binary package from any
6831 executables, libraries, or documentation (except
6832 that specific to the fonts shipped, such as their
6833 license information). If one or more of the fonts
6834 so packaged are necessary for proper operation of
6835 the package with which they are associated the font
6836 package may be Recommended; if the fonts merely
6837 provide an enhancement, a Suggests relationship may
6838 be used. Packages must not Depend on font
6841 This is because the X server may retrieve fonts
6842 from the local filesystem or over the network
6843 from an X font server; the Debian package system
6844 is empowered to deal only with the local
6853 BDF fonts must be converted to PCF fonts with the
6854 <prgn>bdftopcf</prgn> utility (available in the
6855 <tt>xutils</tt> package, <tt>gzip</tt>ped, and
6856 placed in a directory that corresponds to their
6858 <list compact="compact">
6860 100 dpi fonts must be placed in
6861 <tt>/usr/X11R6/lib/X11/fonts/100dpi/</tt>.
6865 75 dpi fonts must be placed in
6866 <tt>/usr/X11R6/lib/X11/fonts/75dpi/</tt>.
6870 Character-cell fonts, cursor fonts, and other
6871 low-resolution fonts must be placed in
6872 <tt>/usr/X11R6/lib/X11/fonts/misc/</tt>.
6879 Speedo fonts must be placed in
6880 <tt>/usr/X11R6/lib/X11/fonts/Speedo/</tt>.
6884 Type 1 fonts must be placed in
6885 <tt>/usr/X11R6/lib/X11/fonts/Type1/</tt>. If font
6886 metric files are available, they must be placed here
6892 Subdirectories of <tt>/usr/X11R6/lib/X11/fonts/</tt>
6893 other than those listed above must be neither
6894 created nor used. (The <tt>PEX</tt>, <tt>CID</tt>,
6895 and <tt>cyrillic</tt> directories are excepted for
6896 historical reasons, but installation of files into
6897 these directories remains discouraged.)
6903 Font packages may, instead of placing files directly
6904 in the X font directories listed above, provide
6905 symbolic links in the font directory which point to
6906 the files' actual location in the filesystem. Such
6907 a location must comply with the FHS.
6913 Font packages should not contain both 75dpi and
6914 100dpi versions of a font. If both are available,
6915 they should be provided in separate binary packages
6916 with <tt>-75dpi</tt> or <tt>-100dpi</tt> appended to
6917 the names of the packages containing the
6918 corresponding fonts.
6924 Fonts destined for the <tt>misc</tt> subdirectory
6925 should not be included in the same package as 75dpi
6926 or 100dpi fonts; instead, they should be provided in
6927 a separate package with <tt>-misc</tt> appended to
6934 Font packages must not provide the files
6935 <tt>fonts.dir</tt>, <tt>fonts.alias</tt>, or
6936 <tt>fonts.scale</tt> in a font directory:
6939 <tt>fonts.dir</tt> files must not be provided at all.
6944 <tt>fonts.alias</tt> and <tt>fonts.scale</tt>
6945 files, if needed, should be provided in the
6947 <tt>/etc/X11/fonts/<var>fontdir</var>/<var>package</var>.<var>extension</var></tt>,
6948 where <var>fontdir</var> is the name of the
6950 <tt>/usr/X11R6/lib/X11/fonts/</tt> where the
6951 package's corresponding fonts are stored
6952 (e.g., <tt>75dpi</tt> or <tt>misc</tt>),
6953 <var>package</var> is the name of the package
6954 that provides these fonts, and
6955 <var>extension</var> is either <tt>scale</tt>
6956 or <tt>alias</tt>, whichever corresponds to
6966 Font packages must declare a dependency on
6967 <tt>xutils (>> 4.0.3)</tt> in their control
6974 Font packages that provide one or more
6975 <tt>fonts.scale</tt> files as described above must
6976 invoke <prgn>update-fonts-scale</prgn> on each
6977 directory into which they installed fonts
6978 <em>before</em> invoking
6979 <prgn>update-fonts-dir</prgn> on that directory.
6980 This invocation must occur in both the
6981 <prgn>postinst</prgn> (for all arguments) and
6982 <prgn>postrm</prgn> (for all arguments except
6983 <tt>upgrade</tt>) scripts.
6989 Font packages that provide one or more
6990 <tt>fonts.alias</tt> files as described above must
6991 invoke <prgn>update-fonts-alias</prgn> on each
6992 directory into which they installed fonts. This
6993 invocation must occur in both the
6994 <prgn>postinst</prgn> (for all arguments) and
6995 <prgn>postrm</prgn> (for all arguments except
6996 <tt>upgrade</tt>) scripts.
7002 Font packages must invoke
7003 <prgn>update-fonts-dir</prgn> on each directory into
7004 which they installed fonts. This invocation must
7005 occur in both the <prgn>postinst</prgn> (for all
7006 arguments) and <prgn>postrm</prgn> (for all
7007 arguments except <tt>upgrade</tt>) scripts.
7013 Font packages must not provide alias names for the
7014 fonts they include which collide with alias names
7015 already in use by fonts already packaged.
7021 Font packages must not provide fonts with the same
7022 XLFD registry name as another font already packaged.
7030 <heading>Application defaults files</heading>
7033 Application defaults files must be installed in the
7034 directory <tt>/etc/X11/app-defaults/</tt> (use of a
7035 localized subdirectory of <tt>/etc/X11/</tt> as described
7036 in the <em>X Toolkit Intrinsics - C Language
7037 Interface</em> manual is also permitted). They must be
7038 registered as <tt>conffile</tt>s or handled as
7039 configuration files. Packages must not provide the
7040 directory <tt>/usr/X11R6/lib/X11/app-defaults/</tt>.
7044 Customization of programs' X resources may also be
7045 supported with the provision of a file with the same name
7046 as that of the package placed in the
7047 <tt>/etc/X11/Xresources/</tt> directory, which must
7048 registered as a <tt>conffile</tt> or handled as a
7049 configuration file.<footnote>
7051 Note that this mechanism is not the same as using
7052 app-defaults; app-defaults are tied to the client
7053 binary on the local filesystem, whereas X resources
7054 are stored in the X server and affect all connecting
7058 <em>Important:</em> packages that install files into the
7059 <tt>/etc/X11/Xresources/</tt> directory must conflict with
7060 <tt>xbase (<< 3.3.2.3a-2)</tt>; if this is not done
7061 it is possible for the installing package to destroy a
7062 previously-existing <tt>/etc/X11/Xresources</tt> file
7063 which had been customized by the system administrator.
7068 <heading>Installation directory issues</heading>
7071 Packages using the X Window System should not be
7072 configured to install files under the <tt>/usr/X11R6/</tt>
7073 directory unless they use <prgn>imake</prgn>. The
7074 <tt>/usr/X11R6/</tt> directory hierarchy should be
7075 regarded as deprecated for all packages except the X
7076 Window System itself, and those which use the
7077 <prgn>imake</prgn> program it provides, in which case the
7078 packages may transition out of the <tt>/usr/X11R6/</tt>
7079 directory at the maintainer's discretion.<footnote>
7081 <prgn>Imake</prgn>-using programs are exempt because,
7082 as long as they are written correctly, the pathnames
7083 they use to locate resources and install themselves
7084 are derived wholly from the X Window System
7085 configuration. Thus, in the event that the X Window
7086 System moves to <tt>/usr/X11R7/</tt>,
7087 <tt>/usr/X12/</tt>, or just plain <tt>/usr/</tt>, all
7088 that is required for these programs is a recompile
7089 against the corresponding X Window System library
7090 development packages.
7093 Programs that use GNU <prgn>autoconf</prgn> and
7094 <prgn>automake</prgn> are usually easily configured at
7095 compile time to use <tt>/usr/</tt> instead of
7096 <tt>/usr/X11R6/</tt>, and this should be done whenever
7097 possible. Configuration files for window managers and
7098 display managers should be placed in a subdirectory of
7099 <tt>/etc/X11/</tt> corresponding to the package name due
7100 to these programs' tight integration with the mechanisms
7101 of the X Window System. Application-level programs should
7102 use the <tt>/etc/</tt> directory unless otherwise mandated
7103 by policy. The installation of files into subdirectories
7104 of <tt>/usr/X11R6/include/X11/</tt> and
7105 <tt>/usr/X11R6/lib/X11/</tt> is permitted but discouraged;
7106 package maintainers should determine if subdirectories of
7107 <tt>/usr/lib/</tt> and <tt>/usr/share/</tt> can be used
7108 instead. (The use of symbolic links from the
7109 <tt>X11R6</tt> directories to other FHS-compliant
7110 locations is encouraged if the program is not easily
7111 configured to look elsewhere for its files.) Packages
7112 must not provide or install files into the directories
7113 <tt>/usr/bin/X11/</tt>, <tt>/usr/include/X11/</tt> or
7114 <tt>/usr/lib/X11/</tt>. Files within a package should,
7115 however, make reference to these directories, rather than
7116 their <tt>X11R6</tt>-named counterparts
7117 <tt>/usr/X11R6/bin/</tt>, <tt>/usr/X11R6/include/X11/</tt>
7118 and <tt>/usr/X11R6/lib/X11/</tt>, if the resources being
7119 referred to have not been moved to other FHS-compliant
7125 <heading>The OSF/Motif and OpenMotif libraries</heading>
7128 <em>Programs that require the non-DFSG-compliant OSF/Motif or
7129 OpenMotif libraries</em><footnote>
7131 OSF/Motif and OpenMotif are collectively referred to as
7132 "Motif" in this policy document.
7135 should be compiled against and tested with LessTif (a free
7136 re-implementation of Motif) instead. If the maintainer
7137 judges that the program or programs do not work
7138 sufficiently well with LessTif to be distributed and
7139 supported, but do so when compiled against Motif, then two
7140 versions of the package should be created; one linked
7141 statically against Motif and with <tt>-smotif</tt>
7142 appended to the package name, and one linked dynamically
7143 against Motif and with <tt>-dmotif</tt> appended to the
7144 package name. Both Motif-linked versions are dependent
7145 upon non-DFSG-compliant software and thus cannot be
7146 uploaded to the <em>main</em> distribution; if the
7147 software is itself DFSG-compliant it may be uploaded to
7148 the <em>contrib</em> distribution. While known existing
7149 versions of Motif permit unlimited redistribution of
7150 binaries linked against the library (whether statically or
7151 dynamically), it is the package maintainer's
7152 responsibility to determine whether this is permitted by
7153 the license of the copy of Motif in his or her possession.
7159 <heading>Perl programs and modules</heading>
7161 Perl programs and modules should follow the current Perl
7162 policy as defined in the file found on
7163 <ftpsite>ftp.debian.org</ftpsite> in
7164 <ftppath>/debian/doc/package-developer/perl-policy.txt.gz</ftppath>
7165 or your local mirror. In addition, it is included in the
7166 <tt>debian-policy</tt> package.
7171 <heading>Emacs lisp programs</heading>
7174 Please refer to the `Debian Emacs Policy' (documented in
7175 <tt>debian-emacs-policy.gz</tt> of the
7176 <prgn>emacsen-common</prgn> package) for details of how to
7177 package emacs lisp programs.
7182 <heading>Games</heading>
7185 The permissions on <tt>/var/games</tt> are mode 755, owner
7186 <tt>root</tt> and group <tt>root</tt>.
7190 Each game decides on its own security policy.</p>
7193 Games which require protected, privileged access to
7194 high-score files, savegames, etc., may be made
7195 set-<em>group</em>-id (mode 2755) and owned by
7196 <tt>root.games</tt>, and use files and directories with
7197 appropriate permissions (770 <tt>root.games</tt>, for
7198 example). They must not be made
7199 set-<em>user</em>-id, as this causes security problems. (If
7200 an attacker can subvert any set-user-id game they can
7201 overwrite the executable of any other, causing other players
7202 of these games to run a Trojan horse program. With a
7203 set-group-id game the attacker only gets access to less
7204 important game data, and if they can get at the other
7205 players' accounts at all it will take considerably more
7209 Some packages, for example some fortune cookie programs, are
7210 configured by the upstream authors to install with their
7211 data files or other static information made unreadable so
7212 that they can only be accessed through set-id programs
7213 provided. You should not do this in a Debian package: anyone can
7214 download the <tt>.deb</tt> file and read the data from it,
7215 so there is no point making the files unreadable. Not
7216 making the files unreadable also means that you don't have
7217 to make so many programs set-id, which reduces the risk of a
7221 As described in the FHS, binaries of games should be
7222 installed in the directory <tt>/usr/games</tt>. This also
7223 applies to games that use the X Window System. Manual pages
7224 for games (X and non-X games) should be installed in
7225 <tt>/usr/share/man/man6</tt>.</p>
7229 <chapt id="docs"><heading>Documentation</heading>
7233 <heading>Manual pages</heading>
7236 You should install manual pages in <prgn>nroff</prgn> source
7237 form, in appropriate places under <tt>/usr/share/man</tt>. You
7238 should only use sections 1 to 9 (see the FHS for more
7239 details). You must not install a preformatted `cat
7243 Each program, utility, and function should have an
7244 associated manpage included in the same package. It is
7245 suggested that all configuration files also have a manual
7246 page included as well.
7250 If no manual page is available for a particular program,
7251 utility, function or configuration file and this is reported
7252 as a bug to the Debian Bug Tracking System, a symbolic link
7253 from the requested manual page to the <manref
7254 name="undocumented" section="7"> manual page may be
7255 provided. This symbolic link can be created from
7256 <tt>debian/rules</tt> like this:
7257 <example compact="compact">
7258 ln -s ../man7/undocumented.7.gz \
7259 debian/tmp/usr/share/man/man[1-9]/<var>requested_manpage</var>.[1-9].gz
7261 This manpage claims that the lack of a manpage has been
7262 reported as a bug, so you may only do this if it really has
7263 (you can report it yourself, if you like). Do not close the
7264 bug report until a proper manpage is available.</p>
7267 You may forward a complaint about a missing manpage to the
7268 upstream authors, and mark the bug as forwarded in the
7269 Debian bug tracking system. Even though the GNU Project do
7270 not in general consider the lack of a manpage to be a bug,
7271 we do; if they tell you that they don't consider it a bug
7272 you should leave the bug in our bug tracking system open
7276 Manual pages should be installed compressed using <tt>gzip
7280 If one manpage needs to be accessible via several names it
7281 is better to use a symbolic link than the <tt>.so</tt>
7282 feature, but there is no need to fiddle with the relevant
7283 parts of the upstream source to change from <tt>.so</tt> to
7284 symlinks: don't do it unless it's easy. You should not
7285 create hard links in the manual page directories, nor put
7286 absolute filenames in <tt>.so</tt> directives. The filename
7287 in a <tt>.so</tt> in a manpage should be relative to the
7288 base of the manpage tree (usually
7289 <tt>/usr/share/man</tt>). If you do not create any links
7290 (whether symlinks, hard links, or <tt>.so</tt> directives)
7291 in the filesystem to the alternate names of the manpage,
7292 then you should not rely on <prgn>man</prgn> finding your
7293 manpage under those names based solely on the information in
7294 the manpage's header.<footnote>
7296 Supporting this in <prgn>man</prgn> often requires
7297 unreasonable processing time to find a manual page or to
7298 report that none exists, and moves knowledge into man's
7299 database that would be better left in the filesystem.
7300 This support is therefore deprecated and will cease to
7301 be present in the future.
7308 <heading>Info documents</heading>
7311 Info documents should be installed in <tt>/usr/share/info</tt>.
7312 They should be compressed with <tt>gzip -9</tt>.</p>
7315 Your package should call <prgn>install-info</prgn> to update
7316 the Info <tt>dir</tt> file in its <prgn>postinst</prgn>
7317 script when called with a <tt>configure</tt> argument, for
7319 <example compact="compact">
7320 install-info --quiet --section Development Development \
7321 /usr/share/info/foobar.info
7325 It is a good idea to specify a section for the location of
7326 your program; this is done with the <tt>--section</tt>
7327 switch. To determine which section to use, you should look
7328 at <tt>/usr/share/info/dir</tt> on your system and choose the most
7329 relevant (or create a new section if none of the current
7330 sections are relevant). Note that the <tt>--section</tt>
7331 flag takes two arguments; the first is a regular expression
7332 to match (case-insensitively) against an existing section,
7333 the second is used when creating a new one.</p>
7336 You should remove the entries in the <prgn>prerm</prgn>
7337 script when called with a <tt>remove</tt> argument:
7338 <example compact="compact">
7339 install-info --quiet --remove /usr/share/info/foobar.info
7343 If <prgn>install-info</prgn> cannot find a description entry
7344 in the Info file you must supply one. See <manref
7345 name="install-info" section="8"> for details.</p>
7349 <heading>Additional documentation</heading>
7352 Any additional documentation that comes with the package may
7353 be installed at the discretion of the package maintainer.
7354 Text documentation should be installed in the directory
7355 <tt>/usr/share/doc/<var>package</var></tt>, where
7356 <var>package</var> is the name of the package, and
7357 compressed with <tt>gzip -9</tt> unless it is small.</p>
7360 If a package comes with large amounts of documentation which
7361 many users of the package will not require you should create
7362 a separate binary package to contain it, so that it does not
7363 take up disk space on the machines of users who do not need
7364 or want it installed.</p>
7367 It is often a good idea to put text information files
7368 (<tt>README</tt>s, changelogs, and so forth) that come with
7369 the source package in <tt>/usr/share/doc/<var>package</var></tt>
7370 in the binary package. However, you don't need to install
7371 the instructions for building and installing the package, of
7375 Files in <tt>/usr/share/doc</tt> should not be referenced by
7376 any program, and the system administrator should be able to
7377 delete them without causing any programs to break. Any files
7378 that are referenced by programs but are also useful as
7379 standalone documentation should be installed under
7380 <tt>/usr/share/<var>package</var>/</tt> with symbolic links
7381 from <tt>/usr/share/doc/<var>package</var>/</tt>.
7387 <heading>Accessing the documentation</heading>
7390 Former Debian releases placed all additional documentation
7391 in <tt>/usr/doc/<var>package</var></tt>. To realize a
7393 <tt>/usr/share/doc/<var>package</var></tt>, each package
7394 must maintain a symlink <tt>/usr/doc/<var>package</var></tt>
7395 that points to the new location of its documentation in
7396 <tt>/usr/share/doc/<var>package</var></tt><footnote>These
7397 symlinks will be removed in the future, but they have to be
7398 there for compatibility reasons until all packages have
7399 moved and the policy is changed accordingly.</footnote>.
7400 The symlink must be created when the package is installed;
7401 it cannot be contained in the package itself due to problems
7402 with <prgn>dpkg</prgn>. One reasonable way to accomplish
7403 this is to put the following in the package's
7404 <prgn>postinst</prgn><footnote>
7406 The <tt>debhelper</tt> script
7407 <prgn>dh_installdocs</prgn> does this automatically.
7410 <example compact="compact">
7411 if [ "$1" = "configure" ]; then
7412 if [ -d /usr/doc -a ! -e /usr/doc/<var>package</var> \
7413 -a -d /usr/share/doc/<var>package</var> ]; then
7414 ln -sf ../share/doc/<var>package</var> /usr/doc/<var>package</var>
7418 and the following in the package's <prgn>prerm</prgn>:
7419 <example compact="compact">
7420 if [ \( "$1" = "upgrade" -o "$1" = "remove" \) \
7421 -a -L /usr/doc/<var>package</var> ]; then
7422 rm -f /usr/doc/<var>package</var>
7429 <heading>Preferred documentation formats</heading>
7432 The unification of Debian documentation is being carried out
7436 If your package comes with extensive documentation in a
7437 markup format that can be converted to various other formats
7438 you should if possible ship HTML versions in a binary
7439 package, in the directory
7440 <tt>/usr/share/doc/<var>appropriate-package</var></tt> or
7441 its subdirectories.<footnote>
7443 The rationale: The important thing here is that HTML
7444 docs should be available in <em>some</em> package, not
7445 necessarily in the main binary package.
7451 Other formats such as PostScript may be provided at the
7452 package maintainer's discretion.
7456 <sect id="copyrightfile">
7457 <heading>Copyright information</heading>
7460 Every package must be accompanied by a verbatim copy of its
7461 copyright and distribution license in the file
7462 <tt>/usr/share/doc/<var>package</var>/copyright</tt>. This
7463 file must neither be compressed nor be a symbolic link.
7467 In addition, the copyright file must say where the upstream
7468 sources (if any) were obtained, and should explain briefly what
7469 modifications were made in the Debian version of the package
7470 compared to the upstream one. It should name the original
7471 authors of the package and the Debian maintainer(s) who were
7472 involved with its creation.</p>
7475 A copy of the file which will be installed in
7476 <tt>/usr/share/doc/<var>package</var>/copyright</tt> should
7477 be in <tt>debian/copyright</tt> in the source package.
7481 <tt>/usr/share/doc/<var>package</var></tt> may be a symbolic
7482 link to another directory in <tt>/usr/share/doc</tt> only if
7483 the two packages both come from the same source and the
7484 first package Depends on the second. These rules are
7485 important because copyrights must be extractable by
7490 Packages distributed under the UCB BSD license, the Artistic
7491 license, the GNU GPL, and the GNU LGPL should refer to the
7492 files <tt>/usr/share/common-licenses/BSD</tt>,
7493 <tt>/usr/share/common-licenses/Artistic</tt>,
7494 <tt>/usr/share/common-licenses/GPL</tt>, and
7495 <tt>/usr/share/common-licenses/LGPL</tt> respectively,
7496 rather than quoting them in the copyright file.
7500 You should not use the copyright file as a general <tt>README</tt>
7501 file. If your package has such a file it should be
7502 installed in <tt>/usr/share/doc/<var>package</var>/README</tt> or
7503 <tt>README.Debian</tt> or some other appropriate place.</p>
7507 <heading>Examples</heading>
7510 Any examples (configurations, source files, whatever),
7511 should be installed in a directory
7512 <tt>/usr/share/doc/<var>package</var>/examples</tt>. These
7513 files should not be referenced by any program: they're there
7514 for the benefit of the system administrator and users as
7515 documentation only. Architecture-specific example files
7516 should be installed in a directory
7517 <tt>/usr/lib/<var>package</var>/examples</tt> with symbolic
7519 <tt>/usr/share/doc/<var>package</var>/examples</tt>, or the
7520 latter directory itself may be a symbolic link to the
7525 <sect id="instchangelog">
7526 <heading>Changelog files</heading>
7529 Packages that are not Debian-native must contain a
7530 compressed copy of the <tt>debian/changelog</tt> file from
7531 the Debian source tree in
7532 <tt>/usr/share/doc/<var>package</var></tt> with the name
7533 <tt>changelog.Debian.gz</tt>. If an upstream changelog is
7534 available, it should be accessible as
7535 <tt>/usr/share/doc/<var>package</var>/changelog.gz</tt> in
7536 plain text. If the upstream changelog is distributed in
7537 HTML, it should be made available in that form as
7538 <tt>/usr/share/doc/<var>package</var>/changelog.html.gz</tt>
7539 and a plain text <tt>changelog.gz</tt> should be generated
7540 from it using, for example, <tt>lynx -dump -nolist</tt>. If
7541 the upstream changelog files do not already conform to this
7542 naming convention, then this may be achieved either by
7543 renaming the files, or by adding a symbolic link, at the
7544 maintainer's discretion.<footnote>
7546 Rationale: People should not have to look in places for
7547 upstream changelogs merely because they are given
7548 different names or are distributed in HTML format.
7554 All of these files should be installed compressed using
7555 <tt>gzip -9</tt>, as they will become large with time even
7556 if they start out small.
7560 If the package has only one changelog which is used both as
7561 the Debian changelog and the upstream one because there is
7562 no separate upstream maintainer then that changelog should
7563 usually be installed as
7564 <tt>/usr/share/doc/<var>package</var>/changelog.gz</tt>; if
7565 there is a separate upstream maintainer, but no upstream
7566 changelog, then the Debian changelog should still be called
7567 <tt>changelog.Debian.gz</tt>.</p>
7571 <appendix id="pkg-scope">
7572 <heading>Introduction and scope of these appendices</heading>
7575 These appendices are taken essentially verbatim from the
7576 now-deprecated Packaging Manual, version 3.2.1.0. They are
7577 the chapters which are likely to be of use to package
7578 maintainers and which have not already been included in the
7579 policy document itself. Most of these sections are very likely
7580 not relevant to policy; they should be treated as
7581 documentation for the packaging system. Please note that these
7582 appendices are included for convenience, and for historical
7583 reasons: they used to be part of policy package, and they have
7584 not yet been incorporated into dpkg documentation. However,
7585 they still have value, and hence they are presented here.
7588 They have not yet been checked to ensure that they are
7589 compatible with the contents of policy, and if there are any
7590 contradictions, the version in the main policy document takes
7591 precedence. The remaining chapters of the old Packaging
7592 Manual have also not been read in detail to ensure that there
7593 are not parts which have been left out. Both of these will be
7598 <prgn>dpkg</prgn> is a suite of programs for creating binary
7599 package files and installing and removing them on Unix
7602 <prgn>dpkg</prgn> is targetted primarily at Debian
7603 GNU/Linux, but may work on or be ported to other
7610 The binary packages are designed for the management of
7611 installed executable programs (usually compiled binaries) and
7612 their associated data, though source code examples and
7613 documentation are provided as part of some packages.</p>
7616 This manual describes the technical aspects of creating Debian
7617 binary packages (<tt>.deb</tt> files). It documents the
7618 behaviour of the package management programs
7619 <prgn>dpkg</prgn>, <prgn>dselect</prgn> et al. and the way
7620 they interact with packages.</p>
7623 It also documents the interaction between
7624 <prgn>dselect</prgn>'s core and the access method scripts it
7625 uses to actually install the selected packages, and describes
7626 how to create a new access method.</p>
7629 This manual does not go into detail about the options and
7630 usage of the package building and installation tools. It
7631 should therefore be read in conjuction with those programs'
7636 The utility programs which are provided with <prgn>dpkg</prgn>
7637 for managing various system configuration and similar issues,
7638 such as <prgn>update-rc.d</prgn> and
7639 <prgn>install-info</prgn>, are not described in detail here -
7640 please see their manpages.
7644 It does <em>not</em> describe the policy requirements imposed
7645 on Debian packages, such as the permissions on files and
7646 directories, documentation requirements, upload procedure, and
7647 so on. You should see the Debian packaging policy manual for
7648 these details. (Many of them will probably turn out to be
7649 helpful even if you don't plan to upload your package and make
7650 it available as part of the distribution.)
7654 It is assumed that the reader is reasonably familiar with the
7655 <prgn>dpkg</prgn> System Administrators' manual.
7656 Unfortunately this manual does not yet exist.
7660 The Debian version of the FSF's GNU hello program is provided
7661 as an example for people wishing to create Debian
7662 packages. The Debian <prgn>debmake</prgn> package is
7663 recommended as a very helpful tool in creating and maintaining
7664 Debian packages. However, while the tools and examples are
7665 helpful, they do not replace the need to read and follow the
7666 Policy and Programmer's Manual.</p>
7669 <appendix id="pkg-binarypkg"><heading>Binary packages (from old
7674 The binary package has two main sections. The first part
7675 consists of various control information files and scripts used
7676 by <prgn>dpkg</prgn> when installing and removing. See <ref
7677 id="pkg-controlarea">.
7681 The second part is an archive containing the files and
7682 directories to be installed.
7686 In the future binary packages may also contain other
7687 components, such as checksums and digital signatures. The
7688 format for the archive is described in full in the
7689 <tt>deb(5)</tt> manpage.
7693 <sect id="pkg-bincreating"><heading>Creating package files -
7694 <prgn>dpkg-deb</prgn>
7698 All manipulation of binary package files is done by
7699 <prgn>dpkg-deb</prgn>; it's the only program that has
7700 knowledge of the format. (<prgn>dpkg-deb</prgn> may be
7701 invoked by calling <prgn>dpkg</prgn>, as <prgn>dpkg</prgn>
7702 will spot that the options requested are appropriate to
7703 <prgn>dpkg-deb</prgn> and invoke that instead with the same
7708 In order to create a binary package you must make a
7709 directory tree which contains all the files and directories
7710 you want to have in the filesystem data part of the package.
7711 In Debian-format source packages this directory is usually
7712 <tt>debian/tmp</tt>, relative to the top of the package's
7717 They should have the locations (relative to the root of the
7718 directory tree you're constructing) ownerships and
7719 permissions which you want them to have on the system when
7724 With current versions of <prgn>dpkg</prgn> the uid/username
7725 and gid/groupname mappings for the users and groups being
7726 used should be the same on the system where the package is
7727 built and the one where it is installed.
7731 You need to add one special directory to the root of the
7732 miniature filesystem tree you're creating:
7733 <prgn>DEBIAN</prgn>. It should contain the control
7734 information files, notably the binary package control file
7735 (see <ref id="pkg-controlfile">).
7739 The <prgn>DEBIAN</prgn> directory will not appear in the
7740 filesystem archive of the package, and so won't be installed
7741 by <prgn>dpkg</prgn> when the package is installed.
7745 When you've prepared the package, you should invoke:
7747 dpkg --build <var>directory</var>
7752 This will build the package in
7753 <tt><var>directory</var>.deb</tt>. (<prgn>dpkg</prgn> knows
7754 that <tt>--build</tt> is a <prgn>dpkg-deb</prgn> option, so
7755 it invokes <prgn>dpkg-deb</prgn> with the same arguments to
7760 See the manpage <manref name="dpkg-deb" section="8"> for details of how
7761 to examine the contents of this newly-created file. You may find the
7762 output of following commands enlightening:
7764 dpkg-deb --info <var>filename</var>.deb
7765 dpkg-deb --contents <var>filename</var>.deb
7766 dpkg --contents <var>filename</var>.deb
7768 To view the copyright file for a package you could use this command:
7770 dpkg --fsys-tarfile <var>filename</var>.deb | tar xof usr/share/doc/<var>\*</var>copyright | less
7775 <sect id="pkg-controlarea">
7777 Package control information files
7781 The control information portion of a binary package is a
7782 collection of files with names known to <prgn>dpkg</prgn>.
7783 It will treat the contents of these files specially - some
7784 of them contain information used by <prgn>dpkg</prgn> when
7785 installing or removing the package; others are scripts which
7786 the package maintainer wants <prgn>dpkg</prgn> to run.
7790 It is possible to put other files in the package control
7791 area, but this is not generally a good idea (though they
7792 will largely be ignored).
7796 Here is a brief list of the control info files supported by
7797 <prgn>dpkg</prgn> and a summary of what they're used for.
7802 <tag><tt>control</tt>
7806 This is the key description file used by
7807 <prgn>dpkg</prgn>. It specifies the package's name
7808 and version, gives its description for the user,
7809 states its relationships with other packages, and so
7810 forth. See <ref id="pkg-controlfile">.
7814 It is usually generated automatically from information
7815 in the source package by the
7816 <prgn>dpkg-gencontrol</prgn> program, and with
7817 assistance from <prgn>dpkg-shlibdeps</prgn>. See <ref
7818 id="pkg-sourcetools">.</p>
7821 <tag><tt>postinst</tt>, <tt>preinst</tt>, <tt>postrm</tt>,
7827 These are exectuable files (usually scripts) which
7828 <prgn>dpkg</prgn> runs during installation, upgrade
7829 and removal of packages. They allow the package to
7830 deal with matters which are particular to that package
7831 or require more complicated processing than that
7832 provided by <prgn>dpkg</prgn>. Details of when and
7833 how they are called are in <ref
7834 id="maintainerscripts">.
7838 It is very important to make these scripts
7842 That means that if it runs successfully or fails
7843 and then you call it again it doesn't bomb out,
7844 but just ensures that everything is the way it
7847 </footnote> This is so that if an error occurs, the
7848 user interrupts <prgn>dpkg</prgn> or some other
7849 unforeseen circumstance happens you don't leave the
7850 user with a badly-broken package.
7854 The maintainer scripts are guaranteed to run with a
7855 controlling terminal and can interact with the user.
7856 If they need to prompt for passwords, do full-screen
7857 interaction or something similar you should do these
7858 things to and from <tt>/dev/tty</tt>, since
7859 <prgn>dpkg</prgn> will at some point redirect scripts'
7860 standard input and output so that it can log the
7861 installation process. Likewise, because these scripts
7862 may be executed with standard output redirected into a
7863 pipe for logging purposes, Perl scripts should set
7864 unbuffered output by setting <tt>$|=1</tt> so that the
7865 output is printed immediately rather than being
7870 Each script should return a zero exit status for
7871 success, or a nonzero one for failure.</p>
7874 <tag><tt>conffiles</tt>
7879 This file contains a list of configuration files which
7880 are to be handled automatically by <prgn>dpkg</prgn>
7881 (see <ref id="pkg-conffiles">). Note that not necessarily
7882 every configuration file should be listed here.</p>
7885 <tag><tt>shlibs</tt>
7890 This file contains a list of the shared libraries
7891 supplied by the package, with dependency details for
7892 each. This is used by <prgn>dpkg-shlibdeps</prgn>
7893 when it determines what dependencies are required in a
7894 package control file. The <tt>shlibs</tt> file format
7895 is described on <ref id="shlibs">.
7901 <sect id="pkg-controlfile">
7903 The main control information file: <tt>control</tt>
7906 The most important control information file used by
7907 <prgn>dpkg</prgn> when it installs a package is
7908 <tt>control</tt>. It contains all the package's `vital
7913 The binary package control files of packages built from
7914 Debian sources are made by a special tool,
7915 <prgn>dpkg-gencontrol</prgn>, which reads
7916 <tt>debian/control</tt> and <tt>debian/changelog</tt> to
7917 find the information it needs. See <ref id="pkg-sourcepkg"> for
7922 The fields in binary package control files are:
7923 <list compact="compact">
7925 <p><qref id="pkg-f-Package"><tt>Package</tt></qref> (mandatory)</p>
7928 <p><qref id="versions"><tt>Version</tt></qref> (mandatory)</p>
7930 <item><p><qref id="pkg-f-Architecture"><tt>Architecture</tt></qref>
7934 This field should appear in all packages, though
7935 <prgn>dpkg</prgn> doesn't require it yet so that
7936 old packages can still be installed.
7942 <p><qref id="relationships"><tt>Depends</tt>,
7943 <tt>Provides</tt> et al.</qref></p>
7946 <p><qref id="pkg-f-Essential"><tt>Essential</tt></qref></p>
7949 <p><qref id="pkg-f-Maintainer"><tt>Maintainer</tt></qref></p>
7952 <p><qref id="pkg-f-classification"><tt>Section</tt>,
7953 <tt>Priority</tt></qref></p>
7956 <p><qref id="pkg-f-Source"><tt>Source</tt></qref></p>
7959 <p><qref id="descriptions"><tt>Description</tt></qref></p>
7963 <qref id="pkg-f-Installed-Size"><tt>Installed-Size</tt></qref>
7969 A description of the syntax of control files and the purpose
7970 of these fields is available in <ref id="pkg-controlfields">.
7975 <heading>Time Stamps</heading>
7977 Maintainers are encouraged to preserve the modification
7978 times of the upstream source files in a package, as far as
7979 is reasonably possible.
7982 The rationale is that there is some information conveyed
7983 by knowing the age of the file, for example, you could
7984 recognize that some documentation is very old by looking
7985 at the modification time, so it would be nice if the
7986 modification time of the upstream source would be
7994 <appendix id="pkg-sourcepkg">
7995 <heading>Source packages (from old Packaging Manual) </heading>
7998 The Debian binary packages in the distribution are generated
7999 from Debian sources, which are in a special format to assist
8000 the easy and automatic building of binaries.
8004 There was a previous version of the Debian source format,
8005 which is now being phased out. Instructions for converting an
8006 old-style package are given in the Debian policy manual.
8009 <sect id="pkg-sourcetools">
8010 <heading>Tools for processing source packages</heading>
8013 Various tools are provided for manipulating source packages;
8014 they pack and unpack sources and help build of binary
8015 packages and help manage the distribution of new versions.
8019 They are introduced and typical uses described here; see
8020 <manref name="dpkg-source" section="1"> for full
8021 documentation about their arguments and operation.
8025 For examples of how to construct a Debian source package,
8026 and how to use those utilities that are used by Debian
8027 source packages, please see the <prgn>hello</prgn> example
8033 <prgn>dpkg-source</prgn> - packs and unpacks Debian source
8038 This program is frequently used by hand, and is also
8039 called from package-independent automated building scripts
8040 such as <prgn>dpkg-buildpackage</prgn>.
8044 To unpack a package it is typically invoked with
8046 dpkg-source -x <var>.../path/to/filename</var>.dsc
8051 with the <tt><var>filename</var>.tar.gz</tt> and
8052 <tt><var>filename</var>.diff.gz</tt> (if applicable) in
8053 the same directory. It unpacks into
8054 <tt><var>package</var>-<var>version</var></tt>, and if
8056 <tt><var>package</var>-<var>version</var>.orig</tt>, in
8057 the current directory.
8061 To create a packed source archive it is typically invoked:
8063 dpkg-source -b <var>package</var>-<var>version</var>
8068 This will create the <tt>.dsc</tt>, <tt>.tar.gz</tt> and
8069 <tt>.diff.gz</tt> (if appropriate) in the current
8070 directory. <prgn>dpkg-source</prgn> does not clean the
8071 source tree first - this must be done separately if it is
8076 See also <ref id="pkg-sourcearchives">.</p>
8082 <prgn>dpkg-buildpackage</prgn> - overall package-building
8087 <prgn>dpkg-buildpackage</prgn> is a script which invokes
8088 <prgn>dpkg-source</prgn>, the <tt>debian/rules</tt>
8089 targets <tt>clean</tt>, <tt>build</tt> and
8090 <tt>binary</tt>, <prgn>dpkg-genchanges</prgn> and
8091 <prgn>pgp</prgn> to build a signed source and binary
8096 It is usually invoked by hand from the top level of the
8097 built or unbuilt source directory. It may be invoked with
8098 no arguments; useful arguments include:
8099 <taglist compact="compact">
8100 <tag><tt>-uc</tt>, <tt>-us</tt></tag>
8103 Do not PGP-sign the <tt>.changes</tt> file or the
8104 source package <tt>.dsc</tt> file, respectively.</p>
8106 <tag><tt>-p<var>pgp-command</var></tt></tag>
8109 Invoke <var>pgp-command</var> instead of finding
8110 <tt>pgp</tt> on the <prgn>PATH</prgn>.
8111 <var>pgp-command</var> must behave just like
8112 <prgn>pgp</prgn>.</p>
8114 <tag><tt>-r<var>root-command</var></tt></tag>
8117 When root privilege is required, invoke the command
8118 <var>root-command</var>. <var>root-command</var>
8119 should invoke its first argument as a command, from
8120 the <prgn>PATH</prgn> if necessary, and pass its
8121 second and subsequent arguments to the command it
8122 calls. If no <var>root-command</var> is supplied
8123 then <var>dpkg-buildpackage</var> will take no
8124 special action to gain root privilege, so that for
8125 most packages it will have to be invoked as root to
8128 <tag><tt>-b</tt>, <tt>-B</tt></tag>
8131 Two types of binary-only build and upload - see
8132 <manref name="dpkg-source" section="1">.
8141 <prgn>dpkg-gencontrol</prgn> - generates binary package
8146 This program is usually called from <tt>debian/rules</tt>
8147 (see <ref id="pkg-sourcetree">) in the top level of the source
8152 This is usually done just before the files and directories in the
8153 temporary directory tree where the package is being built have their
8154 permissions and ownerships set and the package is constructed using
8155 <prgn>dpkg-deb/</prgn>
8158 This is so that the control file which is produced has
8159 the right permissions
8165 <prgn>dpkg-gencontrol</prgn> must be called after all the
8166 files which are to go into the package have been placed in
8167 the temporary build directory, so that its calculation of
8168 the installed size of a package is correct.
8172 It is also necessary for <prgn>dpkg-gencontrol</prgn> to
8173 be run after <prgn>dpkg-shlibdeps</prgn> so that the
8174 variable substitutions created by
8175 <prgn>dpkg-shlibdeps</prgn> in <tt>debian/substvars</tt>
8180 For a package which generates only one binary package, and
8181 which builds it in <tt>debian/tmp</tt> relative to the top
8182 of the source package, it is usually sufficient to call
8183 <prgn>dpkg-gencontrol</prgn>.
8187 Sources which build several binaries will typically need
8190 dpkg-gencontrol -Pdebian/tmp-<var>pkg</var> -p<var>package</var>
8191 </example> The <tt>-P</tt> tells
8192 <prgn>dpkg-gencontrol</prgn> that the package is being
8193 built in a non-default directory, and the <tt>-p</tt>
8194 tells it which package's control file should be generated.
8198 <prgn>dpkg-gencontrol</prgn> also adds information to the
8199 list of files in <tt>debian/files</tt>, for the benefit of
8200 (for example) a future invocation of
8201 <prgn>dpkg-genchanges</prgn>.</p>
8206 <prgn>dpkg-shlibdeps</prgn> - calculates shared library
8211 This program is usually called from <tt>debian/rules</tt>
8212 just before <prgn>dpkg-gencontrol</prgn> (see <ref
8213 id="pkg-sourcetree">), in the top level of the source tree.
8217 Its arguments are executables.
8220 In a forthcoming dpkg version,
8221 <prgn>dpkg-shlibdeps</prgn> would be required to be
8222 called on shared libraries as well.
8225 They may be specified either in the locations in the
8226 source tree where they are created or in the locations
8227 in the temporary build tree where they are installed
8228 prior to binary package creation.
8230 </footnote> for which shared library dependencies should
8231 be included in the binary package's control file.
8235 If some of the found shared libraries should only
8236 warrant a <tt>Recommends</tt> or <tt>Suggests</tt>, or if
8237 some warrant a <tt>Pre-Depends</tt>, this can be achieved
8238 by using the <tt>-d<var>dependency-field</var></tt> option
8239 before those executable(s). (Each <tt>-d</tt> option
8240 takes effect until the next <tt>-d</tt>.)
8244 <prgn>dpkg-shlibdeps</prgn> does not directly cause the
8245 output control file to be modified. Instead by default it
8246 adds to the <tt>debian/substvars</tt> file variable
8247 settings like <tt>shlibs:Depends</tt>. These variable
8248 settings must be referenced in dependency fields in the
8249 appropriate per-binary-package sections of the source
8254 For example, the <prgn>procps</prgn> package generates two
8255 kinds of binaries, simple C binaries like <prgn>ps</prgn>
8256 which require a predependency and full-screen ncurses
8257 binaries like <prgn>top</prgn> which require only a
8258 recommendation. It can say in its <tt>debian/rules</tt>:
8260 dpkg-shlibdeps -dPre-Depends ps -dRecommends top
8262 and then in its main control file <tt>debian/control</tt>:
8266 Pre-Depends: ${shlibs:Pre-Depends}
8267 Recommends: ${shlibs:Recommends}
8273 Sources which produce several binary packages with
8274 different shared library dependency requirements can use
8275 the <tt>-p<var>varnameprefix</var></tt> option to override
8276 the default <tt>shlib:</tt> prefix (one invocation of
8277 <prgn>dpkg-shlibdeps</prgn> per setting of this option).
8278 They can thus produce several sets of dependency
8279 variables, each of the form
8280 <tt><var>varnameprefix</var>:<var>dependencyfield</var></tt>,
8281 which can be referred to in the appropriate parts of the
8282 binary package control files.
8289 <prgn>dpkg-distaddfile</prgn> - adds a file to
8290 <tt>debian/files</tt>
8294 Some packages' uploads need to include files other than
8295 the source and binary package files.
8299 <prgn>dpkg-distaddfile</prgn> adds a file to the
8300 <tt>debian/files</tt> file so that it will be included in
8301 the <tt>.changes</tt> file when
8302 <prgn>dpkg-genchanges</prgn> is run.
8306 It is usually invoked from the <tt>binary</tt> target of
8307 <tt>debian/rules</tt>:
8309 dpkg-distaddfile <var>filename</var> <var>section</var> <var>priority</var>
8311 The <var>filename</var> is relative to the directory where
8312 <prgn>dpkg-genchanges</prgn> will expect to find it - this
8313 is usually the directory above the top level of the source
8314 tree. The <tt>debian/rules</tt> target should put the
8315 file there just before or just after calling
8316 <prgn>dpkg-distaddfile</prgn>.
8320 The <var>section</var> and <var>priority</var> are passed
8321 unchanged into the resulting <tt>.changes</tt> file. See
8322 <ref id="pkg-f-classification">.
8327 <sect1><heading><prgn>dpkg-genchanges</prgn> - generates a <tt>.changes</tt> upload
8332 This program is usually called by package-independent
8333 automatic building scripts such as
8334 <prgn>dpkg-buildpackage</prgn>, but it may also be called
8339 It is usually called in the top level of a built source
8340 tree, and when invoked with no arguments will print out a
8341 straightforward <tt>.changes</tt> file based on the
8342 information in the source package's changelog and control
8343 file and the binary and source packages which should have
8349 <sect1><heading><prgn>dpkg-parsechangelog</prgn> - produces parsed representation of
8354 This program is used internally by
8355 <prgn>dpkg-source</prgn> et al. It may also occasionally
8356 be useful in <tt>debian/rules</tt> and elsewhere. It
8357 parses a changelog, <tt>debian/changelog</tt> by default,
8358 and prints a control-file format representation of the
8359 information in it to standard output.
8363 <sect1 id="pkg-dpkgarch"><heading><prgn>dpkg-architecture</prgn> -
8364 information about the build and host system
8368 This program can be used manually, but is also invoked by
8369 <tt>dpkg-buildpackage</tt> or <tt>debian/rules</tt> to set
8370 to set environment or make variables which specify the build and
8371 host architecture for the package building process.
8376 <sect id="pkg-sourcetree"><heading>The Debianised source tree
8380 The source archive scheme described later is intended to
8381 allow a Debianised source tree with some associated control
8382 information to be reproduced and transported easily. The
8383 Debianised source tree is a version of the original program
8384 with certain files added for the benefit of the
8385 Debianisation process, and with any other changes required
8386 made to the rest of the source code and installation
8391 The extra files created for Debian are in the subdirectory
8392 <tt>debian</tt> of the top level of the Debianised source
8393 tree. They are described below.
8396 <sect1 id="pkg-debianrules"><heading><tt>debian/rules</tt> - the main building
8401 This file is an executable makefile, and contains the
8402 package-specific recipies for compiling the package and
8403 building binary package(s) out of the source.
8407 It must start with the line <tt>#!/usr/bin/make -f</tt>,
8408 so that it can be invoked by saying its name rather than
8409 invoking <prgn>make</prgn> explicitly.
8413 Since an interactive <tt>debian/rules</tt> script makes it
8414 impossible to autocompile that package and also makes it
8415 hard for other people to reproduce the same binary
8416 package, all <strong>required targets</strong> have to be
8417 non-interactive. At a minimul, required targets are the
8418 ones called by <prgn>dpkg-buildpackage</prgn>, namely,
8419 <em>clean</em>, <em>binary</em>, <em>binary-arch</em>, and
8420 <em>build</em>. It also follows that any target that these
8421 targets depend on must also be non-interactive.
8425 The targets which are required to be present are:
8427 <tag><tt>build</tt></tag>
8430 This should perform all non-interactive
8431 configuration and compilation of the package. If a
8432 package has an interactive pre-build configuration
8433 routine, the Debianised source package should be
8434 built after this has taken place, so that it can be
8435 built without rerunning the configuration.
8439 A package may also provide both of the targets
8440 <tt>build-arch</tt> and <tt>build-indep</tt>. The
8441 <tt>build-arch</tt> target, if provided, should
8442 perform all non-interactive configuration and
8443 compilation required for producing all
8444 architecture-dependant binary packages (those packages
8445 for which the body of the <tt>Architecture</tt> field
8446 in <tt>debian/control</tt> is not <tt>all</tt>).
8447 Similarly, the <tt>build-indep</tt> target, if
8448 provided, should perform all non-interactive
8449 configuration and compilation required for producing
8450 all architecture-independent binary packages (those
8451 packages for which the body of the
8452 <tt>Architecture</tt> field in <tt>debian/control</tt>
8453 is <tt>all</tt>). The <tt>build</tt> target should
8454 depend on those of the targets <tt>build-arch</tt> and
8455 <tt>build-indep</tt> that are provided in the rules
8460 If one or both of the targets <tt>build-arch</tt> and
8461 <tt>build-indep</tt> are not provided, then invoking
8462 <tt>debian/rules</tt> with one of the not-provided
8463 targets as arguments should produce a exit status code
8464 of 2. Usually this is provided automatically by make
8465 if the target is missing.
8469 For some packages, notably ones where the same
8470 source tree is compiled in different ways to produce
8471 two binary packages, the <tt>build</tt> target does
8472 not make much sense. For these packages it is good
8473 enough to provide two (or more) targets
8474 (<tt>build-a</tt> and <tt>build-b</tt> or whatever)
8475 for each of the ways of building the package, and a
8476 <tt>build</tt> target that does nothing. The
8477 <tt>binary</tt> target will have to build the
8478 package in each of the possible ways and make the
8479 binary package out of each.
8483 The targets <tt>build</tt>, <tt>build-arch</tt>
8484 and <tt>build-indep</tt> target must not do
8485 anything that might require root privilege.
8489 The <tt>build</tt> target may need to run
8490 <tt>clean</tt> first - see below.
8494 When a package has a configuration routine that takes
8495 a long time, or when the makefiles are poorly
8496 designed, or when <tt>build</tt> needs to run
8497 <tt>clean</tt> first, it is a good idea to <tt>touch
8498 build</tt> when the build process is complete. This
8499 will ensure that if <tt>debian/rules build</tt> is run
8500 again it will not rebuild the whole program.
8504 <tag><tt>binary</tt>, <tt>binary-arch</tt>,
8505 <tt>binary-indep</tt>
8509 The <tt>binary</tt> target should be all that is
8510 necessary for the user to build the binary
8511 package. All these targets are required to be
8512 non-interactive. It is split into two parts:
8513 <tt>binary-arch</tt> builds the packages' output
8514 files which are specific to a particular
8515 architecture, and <tt>binary-indep</tt> builds
8516 those which are not.
8520 <tt>binary</tt> should usually be a target with
8521 no commands which simply depends on
8522 <prgn>binary-arch</prgn> and
8523 <prgn>binary-indep</prgn>.
8527 Both <prgn>binary-*</prgn> targets should depend on
8528 the <tt>build</tt> target, above, so that the
8529 package is built if it has not been already. It
8530 should then create the relevant binary package(s),
8531 using <prgn>dpkg-gencontrol</prgn> to make their
8532 control files and <prgn>dpkg-deb</prgn> to build
8533 them and place them in the parent of the top level
8538 If one of the <prgn>binary-*</prgn> targets has
8539 nothing to do (this will be always be the case if
8540 the source generates only a single binary package,
8541 whether architecture-dependent or not) it
8542 <em>must</em> still exist, but should always
8547 <ref id="pkg-binarypkg"> describes how to construct
8552 The <tt>binary</tt> targets must be invoked as
8557 <tag><tt>clean</tt></tag>
8561 This should undo any effects that the
8562 <tt>build</tt> and <tt>binary</tt> targets
8563 may have had, except that it should leave alone any
8564 output files created in the parent directory by a
8565 run of <tt>binary</tt>. This target is required
8566 to be non-interactive.
8570 If a <tt>build</tt> file is touched at the end
8571 of the <tt>build</tt> target, as suggested
8572 above, it must be removed as the first thing that
8573 <tt>clean</tt> does, so that running
8574 <tt>build</tt> again after an interrupted
8575 <tt>clean</tt> doesn't think that everything is
8580 The <tt>clean</tt> target must be invoked as
8581 root if <tt>binary</tt> has been invoked since
8582 the last <tt>clean</tt>, or if
8583 <tt>build</tt> has been invoked as root (since
8584 <tt>build</tt> may create directories, for
8589 <tag><tt>get-orig-source</tt> (optional)</tag>
8593 This target fetches the most recent version of the
8594 original source package from a canonical archive
8595 site (via FTP or WWW, for example), does any
8596 necessary rearrangement to turn it into the original
8597 source tarfile format described below, and leaves it
8598 in the current directory.
8602 This target may be invoked in any directory, and
8603 should take care to clean up any temporary files it
8608 This target is optional, but providing it if
8609 possible is a good idea.
8615 The <tt>build</tt>, <tt>binary</tt> and
8616 <tt>clean</tt> targets must be invoked with a current
8617 directory of the package's top-level directory.
8622 Additional targets may exist in <tt>debian/rules</tt>,
8623 either as published or undocumented interfaces or for the
8624 package's internal use.
8628 The architecture we build on and build for is determined by make
8629 variables via dpkg-architecture (see <ref id="pkg-dpkgarch">). You can
8630 get the Debian architecture and the GNU style architecture
8631 specification string for the build machine as well as the host
8632 machine. Here is a list of supported make variables:
8633 <list compact="compact">
8635 <p><tt>DEB_*_ARCH</tt> (the Debian architecture)</p>
8638 <p><tt>DEB_*_GNU_TYPE</tt> (the GNU style architecture
8639 specification string)</p>
8642 <p><tt>DEB_*_GNU_CPU</tt> (the CPU part of DEB_*_GNU_TYPE)</p>
8645 <p><tt>DEB_*_GNU_SYSTEM</tt> (the System part of
8651 where <tt>*</tt> is either <tt>BUILD</tt> for specification of
8652 the build machine or <tt>HOST</tt> for specification of the machine
8657 Backward compatibility can be provided in the rules file
8658 by setting the needed variables to suitable default
8659 values, please refer to the documentation of
8660 dpkg-architecture for details.
8664 It is important to understand that the <tt>DEB_*_ARCH</tt>
8665 string does only determine which Debian architecture we
8666 build on resp. for. It should not be used to get the CPU
8667 or System information, the GNU style variables should be
8673 <sect1><heading><tt>debian/control</tt>
8677 This file contains version-independent details about the
8678 source package and about the binary packages it creates.
8682 It is a series of sets of control fields, each
8683 syntactically similar to a binary package control file.
8684 The sets are separated by one or more blank lines. The
8685 first set is information about the source package in
8686 general; each subsequent set describes one binary package
8687 that the source tree builds.
8691 The syntax and semantics of the fields are described below
8692 in <ref id="pkg-controlfields">.
8696 The general (binary-package-independent) fields are:
8697 <list compact="compact">
8699 <p><qref id="pkg-f-Source"><tt>Source</tt></qref> (mandatory)</p>
8702 <p><qref id="pkg-f-Maintainer"><tt>Maintainer</tt></qref></p>
8706 <qref id="pkg-f-classification"><tt>Section</tt> and
8707 <tt>Priority</tt></qref>
8708 (classification, mandatory)
8713 <qref id="relationships"><tt>Build-Depends</tt> et
8714 al.</qref> (source package interrelationships)
8719 <qref id="pkg-f-Standards-Version"><tt>Standards-Version</tt></qref>
8725 The per-binary-package fields are:
8726 <list compact="compact">
8728 <p><qref id="pkg-f-Package"><tt>Package</tt></qref> (mandatory)</p>
8732 <qref id="pkg-f-Architecture"><tt>Architecture</tt></qref>
8736 <p><qref id="descriptions"><tt>Description</tt></qref></p>
8740 <qref id="pkg-f-classification"><tt>Section</tt> and
8741 <tt>Priority</tt></qref> (classification)</p>
8744 <p><qref id="pkg-f-Essential"><tt>Essential</tt></qref></p>
8748 <qref id="relationships"><tt>Depends</tt> et
8749 al.</qref> (binary package interrelationships)
8755 These fields are used by <prgn>dpkg-gencontrol</prgn> to
8756 generate control files for binary packages (see below), by
8757 <prgn>dpkg-genchanges</prgn> to generate the
8758 <tt>.changes</tt> file to accompany the upload, and by
8759 <prgn>dpkg-source</prgn> when it creates the <tt>.dsc</tt>
8760 source control file as part of a source archive.
8764 The fields here may contain variable references - their
8765 values will be substituted by
8766 <prgn>dpkg-gencontrol</prgn>, <prgn>dpkg-genchanges</prgn>
8767 or <prgn>dpkg-source</prgn> when they generate output
8768 control files. See <ref id="pkg-srcsubstvars"> for details.
8771 <p> <sect2><heading>User-defined fields
8775 Additional user-defined fields may be added to the
8776 source package control file. Such fields will be
8777 ignored, and not copied to (for example) binary or
8778 source package control files or upload control files.
8782 If you wish to add additional unsupported fields to
8783 these output files you should use the mechanism
8788 Fields in the main source control information file with
8789 names starting <tt>X</tt>, followed by one or more of
8790 the letters <tt>BCS</tt> and a hyphen <tt>-</tt>, will
8791 be copied to the output files. Only the part of the
8792 field name after the hyphen will be used in the output
8793 file. Where the letter <tt>B</tt> is used the field
8794 will appear in binary package control files, where the
8795 letter <tt>S</tt> is used in source package control
8796 files and where <tt>C</tt> is used in upload control
8797 (<tt>.changes</tt>) files.
8801 For example, if the main source information control file
8804 XBS-Comment: I stand between the candle and the star.
8806 then the binary and source package control files will contain the
8809 Comment: I stand between the candle and the star.
8816 <sect1 id="pkg-dpkgchangelog"><heading><tt>debian/changelog</tt>
8820 This file records the changes to the Debian-specific parts of the
8824 Though there is nothing stopping an author who is also
8825 the Debian maintainer from using it for all their
8826 changes, it will have to be renamed if the Debian and
8827 upstream maintainers become different
8834 It has a special format which allows the package building
8835 tools to discover which version of the package is being
8836 built and find out other release-specific information.
8840 That format is a series of entries like this:
8842 <var>package</var> (<var>version</var>) <var>distribution(s)</var>; urgency=<var>urgency</var>
8844 * <var>change details</var>
8845 <var>more change details</var>
8846 * <var>even more change details</var>
8848 -- <var>maintainer name and email address</var> <var>date</var>
8853 <var>package</var> and <var>version</var> are the source
8854 package name and version number.
8858 <var>distribution(s)</var> lists the distributions where
8859 this version should be installed when it is uploaded - it
8860 is copied to the <tt>Distribution</tt> field in the
8861 <tt>.changes</tt> file. See <ref id="pkg-f-Distribution">.
8865 <var>urgency</var> is the value for the <tt>Urgency</tt>
8866 field in the <tt>.changes</tt> file for the upload. See
8867 <ref id="pkg-f-Urgency">. It is not possible to specify an
8868 urgency containing commas; commas are used to separate
8869 <tt><var>keyword</var>=<var>value</var></tt> settings in
8870 the <prgn>dpkg</prgn> changelog format (though there is
8871 currently only one useful <var>keyword</var>,
8876 The change details may in fact be any series of lines
8877 starting with at least two spaces, but conventionally each
8878 change starts with an asterisk and a separating space and
8879 continuation lines are indented so as to bring them in
8880 line with the start of the text above. Blank lines may be
8881 used here to separate groups of changes, if desired.
8885 The maintainer name and email address should <em>not</em>
8886 necessarily be those of the usual package maintainer.
8887 They should be the details of the person doing
8888 <em>this</em> version. The information here will be
8889 copied to the <tt>.changes</tt> file, and then later used
8890 to send an acknowledgement when the upload has been
8895 The <var>date</var> should be in RFC822 format
8898 This is generated by the <prgn>822-date</prgn>
8901 </footnote>; it should include the timezone specified
8902 numerically, with the timezone name or abbreviation
8903 optionally present as a comment.
8907 The first `title' line with the package name should start
8908 at the left hand margin; the `trailer' line with the
8909 maintainer and date details should be preceded by exactly
8910 one space. The maintainer details and the date must be
8911 separated by exactly two spaces.
8915 An Emacs mode for editing this format is available: it is
8916 called <tt>debian-changelog-mode</tt>. You can have this
8917 mode selected automatically when you edit a Debian
8918 changelog by adding a local variables clause to the end of
8922 <sect2><heading>Defining alternative changelog formats
8926 It is possible to use a different format to the standard
8927 one, by providing a parser for the format you wish to
8932 In order to have <tt>dpkg-parsechangelog</tt> run your
8933 parser, you must include a line within the last 40 lines
8934 of your file matching the Perl regular expression:
8935 <tt>\schangelog-format:\s+([0-9a-z]+)\W</tt> The part in
8936 parentheses should be the name of the format. For
8937 example, you might say:
8939 @@@ changelog-format: joebloggs @@@
8941 Changelog format names are non-empty strings of alphanumerics.
8945 If such a line exists then <tt>dpkg-parsechangelog</tt>
8946 will look for the parser as
8947 <tt>/usr/lib/dpkg/parsechangelog/<var>format-name</var></tt>
8949 <tt>/usr/local/lib/dpkg/parsechangelog/<var>format-name</var></tt>;
8950 it is an error for it not to find it, or for it not to
8951 be an executable program. The default changelog format
8952 is <tt>dpkg</tt>, and a parser for it is provided with
8953 the <tt>dpkg</tt> package.
8957 The parser will be invoked with the changelog open on
8958 standard input at the start of the file. It should read
8959 the file (it may seek if it wishes) to determine the
8960 information required and return the parsed information
8961 to standard output in the form of a series of control
8962 fields in the standard format. By default it should
8963 return information about only the most recent version in
8964 the changelog; it should accept a
8965 <tt>-v<var>version</var></tt> option to return changes
8966 information from all versions present <em>strictly
8967 after</em> <var>version</var>, and it should then be an
8968 error for <var>version</var> not to be present in the
8974 <list compact="compact">
8976 <p><qref id="pkg-f-Source"><tt>Source</tt></qref></p>
8979 <p><qref id="versions"><tt>Version</tt></qref> (mandatory)</p>
8983 <qref id="pkg-f-Distribution"><tt>Distribution</tt></qref>
8988 <p><qref id="pkg-f-Urgency"><tt>Urgency</tt></qref> (mandatory)</p>
8992 <qref id="pkg-f-Maintainer"><tt>Maintainer</tt></qref>
8997 <p><qref id="pkg-f-Date"><tt>Date</tt></qref></p>
9001 <qref id="pkg-f-Changes"><tt>Changes</tt></qref>
9008 If several versions are being returned (due to the use
9009 of <tt>-v</tt>), the urgency value should be of the
9010 highest urgency code listed at the start of any of the
9011 versions requested followed by the concatenated
9012 (space-separated) comments from all the versions
9013 requested; the maintainer, version, distribution and
9014 date should always be from the most recent version.
9018 For the format of the <tt>Changes</tt> field see <ref
9019 id="pkg-f-Changes">.
9023 If the changelog format which is being parsed always or
9024 almost always leaves a blank line between individual
9025 change notes these blank lines should be stripped out,
9026 so as to make the resulting output compact.
9030 If the changelog format does not contain date or package
9031 name information this information should be omitted from
9032 the output. The parser should not attempt to synthesise
9033 it or find it from other sources.
9037 If the changelog does not have the expected format the
9038 parser should exit with a nonzero exit status, rather
9039 than trying to muddle through and possibly generating
9044 A changelog parser may not interact with the user at
9048 <sect1 id="pkg-srcsubstvars"><heading><tt>debian/substvars</tt>
9049 and variable substitutions
9053 When <prgn>dpkg-gencontrol</prgn>,
9054 <prgn>dpkg-genchanges</prgn> and <prgn>dpkg-source</prgn>
9055 generate control files they do variable substitutions on
9056 their output just before writing it. Variable
9057 substitutions have the form
9058 <tt>${<var>variable-name</var>}</tt>. The optional file
9059 <tt>debian/substvars</tt> contains variable substitutions
9060 to be used; variables can also be set directly from
9061 <tt>debian/rules</tt> using the <tt>-V</tt> option to the
9062 source packaging commands, and certain predefined
9063 variables are available.
9067 The is usually generated and modified dynamically by
9068 <tt>debian/rules</tt> targets; in this case it must be
9069 removed by the <tt>clean</tt> target.
9073 See <manref name="dpkg-source" section="1"> for full
9074 details about source variable substitutions, including the
9075 format of <tt>debian/substvars</tt>.</p>
9078 <sect1><heading><tt>debian/files</tt>
9082 This file is not a permanent part of the source tree; it
9083 is used while building packages to record which files are
9084 being generated. <prgn>dpkg-genchanges</prgn> uses it
9085 when it generates a <tt>.changes</tt> file.
9089 It should not exist in a shipped source package, and so it
9090 (and any backup files or temporary files such as
9094 <tt>files.new</tt> is used as a temporary file by
9095 <prgn>dpkg-gencontrol</prgn> and
9096 <prgn>dpkg-distaddfile</prgn> - they write a new
9097 version of <tt>files</tt> here before renaming it,
9098 to avoid leaving a corrupted copy if an error
9101 </footnote>) should be removed by the
9102 <tt>clean</tt> target. It may also be wise to
9103 ensure a fresh start by emptying or removing it at the
9104 start of the <tt>binary</tt> target.
9108 <prgn>dpkg-gencontrol</prgn> adds an entry to this file
9109 for the <tt>.deb</tt> file that will be created by
9110 <prgn>dpkg-deb</prgn> from the control file that it
9111 generates, so for most packages all that needs to be done
9112 with this file is to delete it in <tt>clean</tt>.
9116 If a package upload includes files besides the source
9117 package and any binary packages whose control files were
9118 made with <prgn>dpkg-gencontrol</prgn> then they should be
9119 placed in the parent of the package's top-level directory
9120 and <prgn>dpkg-distaddfile</prgn> should be called to add
9121 the file to the list in <tt>debian/files</tt>.</p>
9124 <sect1><heading><tt>debian/tmp</tt>
9128 This is the canonical temporary location for the
9129 construction of binary packages by the <tt>binary</tt>
9130 target. The directory <tt>tmp</tt> serves as the root of
9131 the filesystem tree as it is being constructed (for
9132 example, by using the package's upstream makefiles install
9133 targets and redirecting the output there), and it also
9134 contains the <tt>DEBIAN</tt> subdirectory. See <ref
9135 id="pkg-bincreating">.
9139 If several binary packages are generated from the same
9140 source tree it is usual to use several
9141 <tt>debian/tmp<var>something</var></tt> directories, for
9142 example <tt>tmp-a</tt> or <tt>tmp-doc</tt>.
9146 Whatever <tt>tmp</tt> directories are created and used by
9147 <tt>binary</tt> must of course be removed by the
9148 <tt>clean</tt> target.</p></sect1>
9152 <sect id="pkg-sourcearchives"><heading>Source packages as archives
9156 As it exists on the FTP site, a Debian source package
9157 consists of three related files. You must have the right
9158 versions of all three to be able to use them.
9163 <tag>Debian source control file - <tt>.dsc</tt></tag>
9167 This file contains a series of fields, identified and
9168 separated just like the fields in the control file of
9169 a binary package. The fields are listed below; their
9170 syntax is described above, in <ref id="pkg-controlfields">.
9171 <list compact="compact">
9173 <p><qref id="pkg-f-Source"><tt>Source</tt></qref></p>
9176 <p><qref id="versions"><tt>Version</tt></qref></p>
9179 <p><qref id="pkg-f-Maintainer"><tt>Maintainer</tt></qref></p>
9182 <p><qref id="pkg-f-Binary"><tt>Binary</tt></qref></p>
9185 <p><qref id="pkg-f-Architecture"><tt>Architecture</tt></qref></p>
9189 <qref id="relationships"><tt>Build-Depends</tt> et
9190 al.</qref> (source package interrelationships)
9195 <qref id="pkg-f-Standards-Version"><tt>Standards-Version</tt></qref></p>
9198 <p><qref id="pkg-f-Files"><tt>Files</tt></qref></p>
9203 The source package control file is generated by
9204 <prgn>dpkg-source</prgn> when it builds the source
9205 archive, from other files in the source package,
9206 described above. When unpacking it is checked against
9207 the files and directories in the other parts of the
9208 source package, as described below.</p>
9212 Original source archive -
9214 <var>package</var>_<var>upstream-version</var>.orig.tar.gz
9221 This is a compressed (with <tt>gzip -9</tt>)
9222 <prgn>tar</prgn> file containing the source code from
9223 the upstream authors of the program. The tarfile
9224 unpacks into a directory
9225 <tt><var>package</var>-<var>upstream-version</var>.orig</tt>,
9226 and does not contain files anywhere other than in
9227 there or in its subdirectories.</p>
9231 Debianisation diff -
9233 <var>package</var>_<var>upstream_version-revision</var>.diff.gz
9239 This is a unified context diff (<tt>diff -u</tt>)
9240 giving the changes which are required to turn the
9241 original source into the Debian source. These changes
9242 may only include editing and creating plain files.
9243 The permissions of files, the targets of symbolic
9244 links and the characteristics of special files or
9245 pipes may not be changed and no files may be removed
9250 All the directories in the diff must exist, except the
9251 <tt>debian</tt> subdirectory of the top of the source
9252 tree, which will be created by
9253 <prgn>dpkg-source</prgn> if necessary when unpacking.
9257 The <prgn>dpkg-source</prgn> program will
9258 automatically make the <tt>debian/rules</tt> file
9259 executable (see below).</p></item>
9264 If there is no original source code - for example, if the
9265 package is specially prepared for Debian or the Debian
9266 maintainer is the same as the upstream maintainer - the
9267 format is slightly different: then there is no diff, and the
9269 <tt><var>package</var>_<var>version</var>.tar.gz</tt> and
9270 contains a directory
9271 <tt><var>package</var>-<var>version</var></tt>.
9275 <sect><heading>Unpacking a Debian source package without
9276 <prgn>dpkg-source</prgn>
9280 <tt>dpkg-source -x</tt> is the recommended way to unpack a
9281 Debian source package. However, if it is not available it
9282 is possible to unpack a Debian source archive as follows:
9283 <enumlist compact="compact">
9286 Untar the tarfile, which will create a <tt>.orig</tt>
9290 <p>Rename the <tt>.orig</tt> directory to
9291 <tt><var>package</var>-<var>version</var></tt>.</p>
9295 Create the subdirectory <tt>debian</tt> at the top of
9296 the source tree.</p>
9298 <item><p>Apply the diff using <tt>patch -p0</tt>.</p>
9300 <item><p>Untar the tarfile again if you want a copy of the original
9301 source code alongside the Debianised version.</p>
9306 It is not possible to generate a valid Debian source archive
9307 without using <prgn>dpkg-source</prgn>. In particular,
9308 attempting to use <prgn>diff</prgn> directly to generate the
9309 <tt>.diff.gz</tt> file will not work.
9312 <sect1><heading>Restrictions on objects in source packages
9316 The source package may not contain any hard links
9319 This is not currently detected when building source
9320 packages, but only when extracting
9326 Hard links may be permitted at some point in the
9327 future, but would require a fair amount of
9330 </footnote>, device special files, sockets or setuid or
9334 Setgid directories are allowed.
9340 The source packaging tools manage the changes between the
9341 original and Debianised source using <prgn>diff</prgn> and
9342 <prgn>patch</prgn>. Turning the original source tree as
9343 included in the <tt>.orig.tar.gz</tt> into the debianised
9344 source must not involve any changes which cannot be
9345 handled by these tools. Problematic changes which cause
9346 <prgn>dpkg-source</prgn> to halt with an error when
9347 building the source package are:
9348 <list compact="compact">
9349 <item><p>Adding or removing symbolic links, sockets or pipes.</p>
9351 <item><p>Changing the targets of symbolic links.</p>
9353 <item><p>Creating directories, other than <tt>debian</tt>.</p>
9355 <item><p>Changes to the contents of binary files.</p></item>
9356 </list> Changes which cause <prgn>dpkg-source</prgn> to
9357 print a warning but continue anyway are:
9358 <list compact="compact">
9361 Removing files, directories or symlinks.
9364 Renaming a file is not treated specially - it is
9365 seen as the removal of the old file (which
9366 generates a warning, but is otherwise ignored),
9367 and the creation of the new
9374 Changed text files which are missing the usual final
9375 newline (either in the original or the modified
9380 Changes which are not represented, but which are not detected by
9381 <prgn>dpkg-source</prgn>, are:
9382 <list compact="compact">
9383 <item><p>Changing the permissions of files (other than
9384 <tt>debian/rules</tt>) and directories.</p></item>
9389 The <tt>debian</tt> directory and <tt>debian/rules</tt>
9390 are handled specially by <prgn>dpkg-source</prgn> - before
9391 applying the changes it will create the <tt>debian</tt>
9392 directory, and afterwards it will make
9393 <tt>debian/rules</tt> world-exectuable.
9399 <appendix id="pkg-controlfields"><heading>Control files and their
9400 fields (from old Packaging Manual)
9404 Many of the tools in the <prgn>dpkg</prgn> suite manipulate
9405 data in a common format, known as control files. Binary and
9406 source packages have control data as do the <tt>.changes</tt>
9407 files which control the installation of uploaded files, and
9408 <prgn>dpkg</prgn>'s internal databases are in a similar
9412 <sect><heading>Syntax of control files
9416 A file consists of one or more paragraphs of fields. The
9417 paragraphs are separated by blank lines. Some control files
9418 only allow one paragraph; others allow several, in which
9419 case each paragraph often refers to a different package.
9423 Each paragraph is a series of fields and values; each field
9424 consists of a name, followed by a colon and the value. It
9425 ends at the end of the line. Horizontal whitespace (spaces
9426 and tabs) may occur before or after the value and is ignored
9427 there; it is conventional to put a single space after the
9432 Some fields' values may span several lines; in this case
9433 each continuation line <em>must</em> start with a space or
9434 tab. Any trailing spaces or tabs at the end of individual
9435 lines of a field value are ignored.
9439 Except where otherwise stated only a single line of data is
9440 allowed and whitespace is not significant in a field body.
9441 Whitespace may never appear inside names (of packages,
9442 architectures, files or anything else), version numbers or
9443 in between the characters of multi-character version
9448 Field names are not case-sensitive, but it is usual to
9449 capitalise the field names using mixed case as shown below.
9453 Blank lines, or lines consisting only of spaces and tabs,
9454 are not allowed within field values or between fields - that
9455 would mean a new paragraph.
9459 It is important to note that there are several fields which
9460 are optional as far as <prgn>dpkg</prgn> and the related
9461 tools are concerned, but which must appear in every Debian
9462 package, or whose omission may cause problems. When writing
9463 the control files for Debian packages you <em>must</em> read
9464 the Debian policy manual in conjuction with the details
9465 below and the list of fields for the particular file.</p>
9468 <sect><heading>List of fields
9471 <sect1 id="pkg-f-Package"><heading><tt>Package</tt>
9475 The name of the binary package. Package names consist of
9476 the alphanumerics and <tt>+</tt> <tt>-</tt> <tt>.</tt>
9477 (plus, minus and full stop).
9480 The characters <tt>@</tt> <tt>:</tt> <tt>=</tt>
9481 <tt>%</tt> <tt>_</tt> (at, colon, equals, percent
9482 and underscore) used to be legal and are still
9483 accepted when found in a package file, but may not be
9484 used in new packages
9490 They must be at least two characters and must start with
9491 an alphanumeric. In current versions of dpkg they are
9492 sort of case-sensitive<footnote><p>This is a
9493 bug.</p></footnote>; use lowercase package names unless
9494 the package you're building (or referring to, in other
9495 fields) is already using uppercase.</p>
9498 <sect1 id="pkg-f-Version"><heading><tt>Version</tt>
9502 This lists the source or binary package's version number -
9503 see <ref id="versions">.
9508 <sect1 id="pkg-f-Architecture"><heading><tt>Architecture</tt>
9512 This is the architecture string; it is a single word for
9513 the Debian architecture.
9517 <prgn>dpkg</prgn> will check the declared architecture of
9518 a binary package against its own compiled-in value before
9523 The special value <tt>all</tt> indicates that the package
9524 is architecture-independent.
9528 In the main <tt>debian/control</tt> file in the source
9529 package, or in the source package control file
9530 <tt>.dsc</tt>, a list of architectures (separated by
9531 spaces) is also allowed, as is the special value
9532 <tt>any</tt>. A list indicates that the source will build
9533 an architecture-dependent package, and will only work
9534 correctly on the listed architectures. <tt>any</tt>
9535 indicates that though the source package isn't dependent
9536 on any particular architecture and should compile fine on
9537 any one, the binary package(s) produced are not
9538 architecture-independent but will instead be specific to
9539 whatever the current build architecture is.
9543 In a <tt>.changes</tt> file the <tt>Architecture</tt>
9544 field lists the architecture(s) of the package(s)
9545 currently being uploaded. This will be a list; if the
9546 source for the package is being uploaded too the special
9547 entry <tt>source</tt> is also present.
9551 See <ref id="pkg-debianrules"> for information how to get the
9552 architecture for the build process.
9556 <sect1 id="pkg-f-Maintainer"><heading><tt>Maintainer</tt>
9560 The package maintainer's name and email address. The name
9561 should come first, then the email address inside angle
9562 brackets <tt><></tt> (in RFC822 format).
9566 If the maintainer's name contains a full stop then the
9567 whole field will not work directly as an email address due
9568 to a misfeature in the syntax specified in RFC822; a
9569 program using this field as an address must check for this
9570 and correct the problem if necessary (for example by
9571 putting the name in round brackets and moving it to the
9572 end, and bringing the email address forward).
9576 In a <tt>.changes</tt> file or parsed changelog data this
9577 contains the name and email address of the person
9578 responsible for the particular version in question - this
9579 may not be the package's usual maintainer.
9583 This field is usually optional in as far as the
9584 <prgn>dpkg</prgn> are concerned, but its absence when
9585 building packages usually generates a warning.</p>
9588 <sect1 id="pkg-f-Source"><heading><tt>Source</tt>
9592 This field identifies the source package name.
9596 In a main source control information or a
9597 <tt>.changes</tt> or <tt>.dsc</tt> file or parsed
9598 changelog data this may contain only the name of the
9603 In the control file of a binary package (or in a
9604 <tt>Packages</tt> file) it may be followed by a version
9605 number in parentheses.
9608 It is usual to leave a space after the package name if
9609 a version number is specified.
9611 </footnote> This version number may be omitted (and is, by
9612 <prgn>dpkg-gencontrol</prgn>) if it has the same value as
9613 the <tt>Version</tt> field of the binary package in
9614 question. The field itself may be omitted from a binary
9615 package control file when the source package has the same
9616 name and version as the binary package.
9620 <sect1><heading>Package interrelationship fields:
9621 <tt>Depends</tt>, <tt>Pre-Depends</tt>,
9622 <tt>Recommends</tt> <tt>Suggests</tt>, <tt>Conflicts</tt>,
9623 <tt>Provides</tt>, <tt>Replaces</tt>
9627 These fields describe the package's relationships with
9628 other packages. Their syntax and semantics are described
9629 in <ref id="relationships">.</p>
9632 <sect1 id="pkg-f-Description"><heading><tt>Description</tt>
9636 In a binary package <tt>Packages</tt> file or main source
9637 control file this field contains a description of the
9638 binary package, in a special format. See <ref
9639 id="descriptions"> for details.
9643 In a <tt>.changes</tt> file it contains a summary of the
9644 descriptions for the packages being uploaded. The part of
9645 the field before the first newline is empty; thereafter
9646 each line has the name of a binary package and the summary
9647 description line from that binary package. Each line is
9648 indented by one space.</p>
9651 <sect1 id="pkg-f-Essential"><heading><tt>Essential</tt>
9655 This is a boolean field which may occur only in the
9656 control file of a binary package (or in the
9657 <tt>Packages</tt> file) or in a per-package fields
9658 paragraph of a main source control data file.
9662 If set to <tt>yes</tt> then <prgn>dpkg</prgn> and
9663 <prgn>dselect</prgn> will refuse to remove the package
9664 (though it can be upgraded and/or replaced). The other
9665 possible value is <tt>no</tt>, which is the same as not
9666 having the field at all.</p>
9669 <sect1 id="pkg-f-classification"><heading><tt>Section</tt> and
9674 These two fields classify the package. The
9675 <tt>Priority</tt> represents how important that it is that
9676 the user have it installed; the <tt>Section</tt>
9677 represents an application area into which the package has
9682 When they appear in the <tt>debian/control</tt> file these
9683 fields give values for the section and priority subfields
9684 of the <tt>Files</tt> field of the <tt>.changes</tt> file,
9685 and give defaults for the section and priority of the
9690 The section and priority are represented, though not as
9691 separate fields, in the information for each file in the
9692 <qref id="pkg-f-Files"><tt>-File</tt></qref>field of a
9693 <tt>.changes</tt> file. The section value in a
9694 <tt>.changes</tt> file is used to decide where to install
9695 a package in the FTP archive.
9699 These fields are not used by by <prgn>dpkg</prgn> proper,
9700 but by <prgn>dselect</prgn> when it sorts packages and
9701 selects defaults. See the Debian policy manual for the
9702 priorities in use and the criteria for selecting the
9703 priority for a Debian package, and look at the Debian FTP
9704 archive for a list of currently in-use priorities.
9708 These fields may appear in binary package control files,
9709 in which case they provide a default value in case the
9710 <tt>Packages</tt> files are missing the information.
9711 <prgn>dpkg</prgn> and <prgn>dselect</prgn> will only use
9712 the value from a <tt>.deb</tt> file if they have no other
9713 information; a value listed in a <tt>Packages</tt> file
9714 will always take precedence. By default
9715 <prgn>dpkg-gencontrol</prgn> does not include the section
9716 and priority in the control file of a binary package - use
9717 the <tt>-isp</tt>, <tt>-is</tt> or <tt>-ip</tt> options to
9718 achieve this effect.</p>
9721 <sect1 id="pkg-f-Binary"><heading><tt>Binary</tt>
9725 This field is a list of binary packages.
9729 When it appears in the <tt>.dsc</tt> file it is the list
9730 of binary packages which a source package can produce. It
9731 does not necessarily produce all of these binary packages
9732 for every architecture. The source control file doesn't
9733 contain details of which architectures are appropriate for
9734 which of the binary packages.
9738 When it appears in a <tt>.changes</tt> file it lists the
9739 names of the binary packages actually being uploaded.
9743 The syntax is a list of binary packages separated by
9747 A space after each comma is conventional.
9749 </footnote> Currently the packages must be separated using
9750 only spaces in the <tt>.changes</tt> file.</p>
9753 <sect1 id="pkg-f-Installed-Size"><heading><tt>Installed-Size</tt>
9757 This field appears in the control files of binary
9758 packages, and in the <tt>Packages</tt> files. It gives
9759 the total amount of disk space required to install the
9764 The disk space is represented in kilobytes as a simple
9768 <sect1 id="pkg-f-Files"><heading><tt>Files</tt>
9772 This field contains a list of files with information about
9773 each one. The exact information and syntax varies with
9774 the context. In all cases the the part of the field
9775 contents on the same line as the field name is empty. The
9776 remainder of the field is one line per file, each line
9777 being indented by one space and containing a number of
9778 sub-fields separated by spaces.
9782 In the <tt>.dsc</tt> (Debian source control) file each
9783 line contains the MD5 checksum, size and filename of the
9784 tarfile and (if applicable) diff file which make up the
9785 remainder of the source package.
9788 That is, the parts which are not the
9791 </footnote> The exact forms of the filenames are described
9792 in <ref id="pkg-sourcearchives">.
9796 In the <tt>.changes</tt> file this contains one line per
9797 file being uploaded. Each line contains the MD5 checksum,
9798 size, section and priority and the filename. The section
9799 and priority are the values of the corresponding fields in
9800 the main source control file - see <ref
9801 id="pkg-f-classification">. If no section or priority is
9802 specified then <tt>-</tt> should be used, though section
9803 and priority values must be specified for new packages to
9804 be installed properly.
9808 The special value <tt>byhand</tt> for the section in a
9809 <tt>.changes</tt> file indicates that the file in question
9810 is not an ordinary package file and must by installed by
9811 hand by the distribution maintainers. If the section is
9812 <tt>byhand</tt> the priority should be <tt>-</tt>.
9816 If a new Debian revision of a package is being shipped and
9817 no new original source archive is being distributed the
9818 <tt>.dsc</tt> must still contain the <tt>Files</tt> field
9819 entry for the original source archive
9820 <tt><var>package</var>-<var>upstream-version</var>.orig.tar.gz</tt>,
9821 but the <tt>.changes</tt> file should leave it out. In
9822 this case the original source archive on the distribution
9823 site must match exactly, byte-for-byte, the original
9824 source archive which was used to generate the
9825 <tt>.dsc</tt> file and diff which are being uploaded.</p>
9830 id="pkg-f-Standards-Version"><heading><tt>Standards-Version</tt>
9834 The most recent version of the standards (the
9835 <prgn>dpkg</prgn> programmers' and policy manuals and
9836 associated texts) with which the package complies. This
9837 is updated manually when editing the source package to
9838 conform to newer standards; it can sometimes be used to
9839 tell when a package needs attention.
9843 Its format is the same as that of a version number except
9844 that no epoch or Debian revision is allowed - see <ref
9849 <sect1 id="pkg-f-Distribution"><heading><tt>Distribution</tt>
9853 In a <tt>.changes</tt> file or parsed changelog output
9854 this contains the (space-separated) name(s) of the
9855 distribution(s) where this version of the package should
9856 be or was installed. Distribution names follow the rules
9857 for package names. (See <ref id="pkg-f-Package">).
9861 Current distribution values are:
9863 <tag><em>stable</em></tag>
9866 This is the current `released' version of Debian
9867 GNU/Linux. A new version is released approximately
9868 every 3 months after the <em>development</em> code has
9869 been <em>frozen</em> for a month of testing. Once the
9870 distribution is <em>stable</em> only major bug fixes
9871 are allowed. When changes are made to this
9872 distribution, the release number is increased
9873 (for example: 1.2r1 becomes 1.2r2 then 1.2r3, etc).
9877 <tag><em>unstable</em></tag>
9880 This distribution value refers to the
9881 <em>developmental</em> part of the Debian distribution
9882 tree. New packages, new upstream versions of packages
9883 and bug fixes go into the <em>unstable</em> directory
9884 tree. Download from this distribution at your own
9888 <tag><em>contrib</em></tag>
9891 The packages with this distribution value do not meet
9892 the criteria for inclusion in the main Debian
9893 distribution as defined by the Policy Manual, but meet
9894 the criteria for the <em>contrib</em>
9895 Distribution. There is currently no distinction
9896 between stable and unstable packages in the
9897 <em>contrib</em> or <em>non-free</em>
9898 distributions. Use your best judgement in downloading
9899 from this Distribution.</p>
9902 <tag><em>non-free</em></tag>
9905 Like the packages in the <em>contrib</em> seciton,
9906 the packages in <em>non-free</em> do not meet the
9907 criteria for inclusion in the main Debian distribution
9908 as defined by the Policy Manual. Again, use your best
9909 judgement in downloading from this Distribution.</p>
9911 <tag><em>experimental</em></tag>
9914 The packages with this distribution value are deemed
9915 by their maintainers to be high risk. Oftentimes they
9916 represent early beta or developmental packages from
9917 various sources that the maintainers want people to
9918 try, but are not ready to be a part of the other parts
9919 of the Debian distribution tree. Download at your own
9923 <tag><em>frozen</em></tag>
9926 From time to time, (currently, every 3 months) the
9927 <em>unstable</em> distribution enters a state of
9928 `code-freeze' in anticipation of release as a
9929 <em>stable</em> version. During this period of testing
9930 (usually 4 weeks) only fixes for existing or
9931 newly-discovered bugs will be allowed.
9934 </taglist> You should list <em>all</em> distributions that
9935 the package should be installed into. Except in unusual
9936 circumstances, installations to <em>stable</em> should also
9937 go into <em>frozen</em> (if it exists) and
9938 <em>unstable</em>. Likewise, installations into
9939 <em>frozen</em> should also go into <em>unstable</em>.</p>
9942 <sect1 id="pkg-f-Urgency"><heading><tt>Urgency</tt>
9946 This is a description of how important it is to upgrade to
9947 this version from previous ones. It consists of a single
9948 keyword usually taking one of the values <tt>LOW</tt>,
9949 <tt>MEDIUM</tt> or <tt>HIGH</tt>) followed by an optional
9950 commentary (separated by a space) which is usually in
9951 parentheses. For example:
9953 Urgency: LOW (HIGH for diversions users)
9958 This field appears in the <tt>.changes</tt> file and in
9959 parsed changelogs; its value appears as the value of the
9960 <tt>urgency</tt> attribute in a <prgn>dpkg</prgn>-style
9961 changelog (see <ref id="pkg-dpkgchangelog">).
9965 Urgency keywords are not case-sensitive.</p>
9968 <sect1 id="pkg-f-Date"><heading><tt>Date</tt>
9972 In <tt>.changes</tt> files and parsed changelogs, this
9973 gives the date the package was built or last edited.</p>
9976 <sect1 id="pkg-f-Format"><heading><tt>Format</tt>
9980 This field occurs in <tt>.changes</tt> files, and
9981 specifies a format revision for the file. The format
9982 described here is version <tt>1.5</tt>. The syntax of the
9983 format value is the same as that of a package version
9984 number except that no epoch or Debian revision is allowed
9985 - see <ref id="versions">.</p>
9988 <sect1 id="pkg-f-Changes"><heading><tt>Changes</tt>
9992 In a <tt>.changes</tt> file or parsed changelog this field
9993 contains the human-readable changes data, describing the
9994 differences between the last version and the current one.
9998 There should be nothing in this field before the first
9999 newline; all the subsequent lines must be indented by at
10000 least one space; blank lines must be represented by a line
10001 consiting only of a space and a full stop.
10005 Each version's change information should be preceded by a
10006 `title' line giving at least the version, distribution(s)
10007 and urgency, in a human-readable way.
10011 If data from several versions is being returned the entry
10012 for the most recent version should be returned first, and
10013 entries should be separated by the representation of a
10014 blank line (the `title' line may also be followed by the
10015 representation of blank line).</p>
10018 <sect1 id="pkg-f-Filename"><heading><tt>Filename</tt> and
10019 <tt>MSDOS-Filename</tt>
10023 These fields in <tt>Packages</tt> files give the
10024 filename(s) of (the parts of) a package in the
10025 distribution directories, relative to the root of the
10026 Debian hierarchy. If the package has been split into
10027 several parts the parts are all listed in order, separated
10031 <sect1 id="pkg-f-Size"><heading><tt>Size</tt> and <tt>MD5sum</tt>
10035 These fields in <tt>Packages</tt> files give the size (in
10036 bytes, expressed in decimal) and MD5 checksum of the
10037 file(s) which make(s) up a binary package in the
10038 distribution. If the package is split into several parts
10039 the values for the parts are listed in order, separated by
10043 <sect1 id="pkg-f-Status"><heading><tt>Status</tt>
10047 This field in <prgn>dpkg</prgn>'s status file records
10048 whether the user wants a package installed, removed or
10049 left alone, whether it is broken (requiring
10050 reinstallation) or not and what its current state on the
10051 system is. Each of these pieces of information is a
10055 <sect1 id="pkg-f-Config-Version"><heading><tt>Config-Version</tt>
10059 If a package is not installed or not configured, this
10060 field in <prgn>dpkg</prgn>'s status file records the last
10061 version of the package which was successfully
10065 <sect1 id="pkg-f-Conffiles"><heading><tt>Conffiles</tt>
10069 This field in <prgn>dpkg</prgn>'s status file contains
10070 information about the automatically-managed configuration
10071 files held by a package. This field should <em>not</em>
10072 appear anywhere in a package!</p>
10075 <sect1><heading>Obsolete fields
10079 These are still recognised by <prgn>dpkg</prgn> but should
10080 not appear anywhere any more.
10081 <taglist compact="compact">
10083 <tag><tt>Revision</tt></tag>
10084 <tag><tt>Package-Revision</tt></tag>
10085 <tag><tt>Package_Revision</tt></tag>
10088 The Debian revision part of the package version was
10089 at one point in a separate control file field. This
10090 field went through several names.</p>
10093 <tag><tt>Recommended</tt></tag>
10094 <item><p>Old name for <tt>Recommends</tt></p>
10097 <tag><tt>Optional</tt></tag>
10098 <item><p>Old name for <tt>Suggests</tt>.</p>
10100 <tag><tt>Class</tt></tag>
10101 <item><p>Old name for <tt>Priority</tt>.</p>
10109 <appendix id="pkg-conffiles"><heading>Configuration file handling
10110 (from old Packaging Manual)
10114 <prgn>dpkg</prgn> can do a certain amount of automatic
10115 handling of package configuration files.
10119 Whether this mechanism is appropriate depends on a number of
10120 factors, but basically there are two approaches to any
10121 particular configuration file.
10125 The easy method is to ship a best-effort configuration in the
10126 package, and use <prgn>dpkg</prgn>'s conffile mechanism to
10127 handle updates. If the user is unlikely to want to edit the
10128 file, but you need them to be able to without losing their
10129 changes, and a new package with a changed version of the file
10130 is only released infrequently, this is a good approach.
10134 The hard method is to build the configuration file from
10135 scratch in the <prgn>postinst</prgn> script, and to take the
10136 responsibility for fixing any mistakes made in earlier
10137 versions of the package automatically. This will be
10138 appropriate if the file is likely to need to be different on
10142 <sect><heading>Automatic handling of configuration files by
10147 A package may contain a control area file called
10148 <tt>conffiles</tt>. This file should be a list of filenames
10149 of configuration files needing automatic handling, separated
10150 by newlines. The filenames should be absolute pathnames,
10151 and the files referred to should actually exist in the
10156 When a package is upgraded <prgn>dpkg</prgn> will process
10157 the configuration files during the configuration stage,
10158 shortly before it runs the package's <prgn>postinst</prgn>
10163 For each file it checks to see whether the version of the
10164 file included in the package is the same as the one that was
10165 included in the last version of the package (the one that is
10166 being upgraded from); it also compares the version currently
10167 installed on the system with the one shipped with the last
10172 If neither the user nor the package maintainer has changed
10173 the file, it is left alone. If one or the other has changed
10174 their version, then the changed version is preferred - i.e.,
10175 if the user edits their file, but the package maintainer
10176 doesn't ship a different version, the user's changes will
10177 stay, silently, but if the maintainer ships a new version
10178 and the user hasn't edited it the new version will be
10179 installed (with an informative message). If both have
10180 changed their version the user is prompted about the problem
10181 and must resolve the differences themselves.
10185 The comparisons are done by calculating the MD5 message
10186 digests of the files, and storing the MD5 of the file as it
10187 was included in the most recent version of the package.
10191 When a package is installed for the first time
10192 <prgn>dpkg</prgn> will install the file that comes with it,
10193 unless that would mean overwriting a file already on the
10198 However, note that <prgn>dpkg</prgn> will <em>not</em>
10199 replace a conffile that was removed by the user (or by a
10200 script). This is necessary because with some programs a
10201 missing file produces an effect hard or impossible to
10202 achieve in another way, so that a missing file needs to be
10203 kept that way if the user did it.
10207 Note that a package should <em>not</em> modify a
10208 <prgn>dpkg</prgn>-handled conffile in its maintainer
10209 scripts. Doing this will lead to <prgn>dpkg</prgn> giving
10210 the user confusing and possibly dangerous options for
10211 conffile update when the package is upgraded.</p>
10214 <sect><heading>Fully-featured maintainer script configuration
10219 For files which contain site-specific information such as
10220 the hostname and networking details and so forth, it is
10221 better to create the file in the package's
10222 <prgn>postinst</prgn> script.
10226 This will typically involve examining the state of the rest
10227 of the system to determine values and other information, and
10228 may involve prompting the user for some information which
10229 can't be obtained some other way.
10233 When using this method there are a couple of important
10234 issues which should be considered:
10238 If you discover a bug in the program which generates the
10239 configuration file, or if the format of the file changes
10240 from one version to the next, you will have to arrange for
10241 the postinst script to do something sensible - usually this
10242 will mean editing the installed configuration file to remove
10243 the problem or change the syntax. You will have to do this
10244 very carefully, since the user may have changed the file,
10245 perhaps to fix the very problem that your script is trying
10246 to deal with - you will have to detect these situations and
10247 deal with them correctly.
10251 If you do go down this route it's probably a good idea to
10252 make the program that generates the configuration file(s) a
10253 separate program in <tt>/usr/sbin</tt>, by convention called
10254 <tt><var>package</var>config</tt> and then run that if
10255 appropriate from the post-installation script. The
10256 <tt><var>package</var>config</tt> program should not
10257 unquestioningly overwrite an existing configuration - if its
10258 mode of operation is geared towards setting up a package for
10259 the first time (rather than any arbitrary reconfiguration
10260 later) you should have it check whether the configuration
10261 already exists, and require a <tt>--force</tt> flag to
10262 overwrite it.</p></sect>
10265 <appendix id="pkg-alternatives"><heading>Alternative versions of
10266 an interface - <prgn>update-alternatives</prgn> (from old
10271 When several packages all provide different versions of the
10272 same program or file it is useful to have the system select a
10273 default, but to allow the system administrator to change it
10274 and have their decisions respected.
10278 For example, there are several versions of the <prgn>vi</prgn>
10279 editor, and there is no reason to prevent all of them from
10280 being installed at once, each under their own name
10281 (<prgn>nvi</prgn>, <prgn>vim</prgn> or whatever).
10282 Nevertheless it is desirable to have the name <tt>vi</tt>
10283 refer to something, at least by default.
10287 If all the packages involved cooperate, this can be done with
10288 <prgn>update-alternatives</prgn>.
10292 Each package provides its own version under its own name, and
10293 calls <prgn>update-alternatives</prgn> in its postinst to
10294 register its version (and again in its prerm to deregister
10299 See the manpage <manref name="update-alternatives"
10300 section="8"> for details.
10304 If <prgn>update-alternatives</prgn> does not seem appropriate
10305 you may wish to consider using diversions instead.</p>
10308 <appendix id="pkg-diversions"><heading>Diversions - overriding a
10309 package's version of a file (from old Packaging Manual)
10313 It is possible to have <prgn>dpkg</prgn> not overwrite a file
10314 when it reinstalls the package it belongs to, and to have it
10315 put the file from the package somewhere else instead.
10319 This can be used locally to override a package's version of a
10320 file, or by one package to override another's version (or
10321 provide a wrapper for it).
10325 Before deciding to use a diversion, read <ref
10326 id="pkg-alternatives"> to see if you really want a diversion
10327 rather than several alternative versions of a program.
10331 There is a diversion list, which is read by <prgn>dpkg</prgn>,
10332 and updated by a special program <prgn>dpkg-divert</prgn>.
10333 Please see <manref name="dpkg-divert" section="8"> for full
10334 details of its operation.
10338 When a package wishes to divert a file from another, it should
10339 call <prgn>dpkg-divert</prgn> in its preinst to add the
10340 diversion and rename the existing file. For example,
10341 supposing that a <prgn>smailwrapper</prgn> package wishes to
10342 install a wrapper around <tt>/usr/sbin/smail</tt>:
10344 if [ install = "$1" -o upgrade = "$1" ]; then
10345 dpkg-divert --package smailwrapper --add --rename \
10346 --divert /usr/sbin/smail.real /usr/sbin/smail
10348 </example> Testing <tt>$1</tt> is necessary so that the script
10349 doesn't try to add the diversion again when
10350 <prgn>smailwrapper</prgn> is upgraded. The <tt>--package
10351 smailwrapper</tt> ensures that <prgn>smailwrapper</prgn>'s
10352 copy of <tt>/usr/sbin/smail</tt> can bypass the diversion and
10353 get installed as the true version.
10357 The postrm has to do the reverse:
10359 if [ remove = "$1" ]; then
10360 dpkg-divert --package smailwrapper --remove --rename \
10361 --divert /usr/sbin/smail.real /usr/sbin/smail
10367 Do not attempt to divert a file which is vitally important for
10368 the system's operation - when using <prgn>dpkg-divert</prgn>
10369 there is a time, after it has been diverted but before
10370 <prgn>dpkg</prgn> has installed the new version, when the file
10371 does not exist.</p>