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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 dependancies 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 needs to 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 except where doing so would violate other terms of Debian
4142 Policy. The latest version of this document can be found
4143 in the <tt>debian-policy</tt> package or on
4144 <url id="http://www.debian.org/doc/packaging-manuals/fhs"
4145 name="FHS (Debian copy)"> alongside this manual or on
4146 <url id="http://www.pathname.com/fhs/" name="FHS (upstream)">.
4147 Specific questions about following the standard may be
4148 asked on the <tt>debian-devel</tt> mailing list, or
4149 referred to Daniel Quinlan, the FHS coordinator, at
4150 <email>quinlan@pathname.com</email>.
4155 <heading>Site-specific programs</heading>
4158 As mandated by the FHS, packages must not place any
4159 files in <tt>/usr/local</tt>, either by putting them in
4160 the file system archive to be unpacked by <prgn>dpkg</prgn>
4161 or by manipulating them in their maintainer scripts.
4165 However, the package may create empty directories below
4166 <tt>/usr/local</tt> so that the system administrator knows
4167 where to place site-specific files. These directories
4168 should be removed on package removal if they are
4173 Note, that this applies only to directories <em>below</em>
4174 <tt>/usr/local</tt>, not <em>in</em> <tt>/usr/local</tt>.
4175 Packages must not create sub-directories in the directory
4176 <tt>/usr/local</tt> itself, except those listed in FHS,
4177 section 4.5. However, you may create directories below
4178 them as you wish. You must not remove any of the
4179 directories listed in 4.5, even if you created them.
4183 Since <tt>/usr/local</tt> can be mounted read-only from a
4184 remote server, these directories must be created and
4185 removed by the <prgn>postinst</prgn> and <prgn>prerm</prgn>
4186 maintainer scripts and not be included in the
4187 <tt>.deb</tt> archive. These scripts must not fail if
4188 either of these operations fail.
4192 For example, the <tt>emacsen-common</tt> package could
4193 contain something like
4194 <example compact="compact">
4195 if [ ! -e /usr/local/share/emacs ]
4197 if mkdir /usr/local/share/emacs 2>/dev/null
4199 chown root:staff /usr/local/share/emacs
4200 chmod 2775 /usr/local/share/emacs
4204 in its <prgn>postinst</prgn> script, and
4205 <example compact="compact">
4206 rmdir /usr/local/share/emacs/site-lisp 2>/dev/null || true
4207 rmdir /usr/local/share/emacs 2>/dev/null || true
4209 in the <prgn>prerm</prgn> script. (Note that this form is
4210 used to ensure that if the script is interrupted, the
4211 directory <tt>/usr/local/share/emacs</tt> will still be
4216 If you do create a directory in <tt>/usr/local</tt> for
4217 local additions to a package, you should ensure that
4218 settings in <tt>/usr/local</tt> take precedence over the
4219 equivalents in <tt>/usr</tt>.
4223 However, because <tt>/usr/local</tt> and its contents are
4224 for exclusive use of the local administrator, a package
4225 must not rely on the presence or absence of files or
4226 directories in <tt>/usr/local</tt> for normal operation.
4230 The <tt>/usr/local</tt> directory itself and all the
4231 subdirectories created by the package should (by default) have
4232 permissions 2775 (group-writable and set-group-id) and be
4233 owned by <tt>root.staff</tt>.
4238 <heading>The system-wide mail directory</heading>
4240 The system-wide mail directory is <tt>/var/mail</tt>. This
4241 directory is part of the base system and should not owned
4242 by any particular mail agents. The use of the old
4243 location <tt>/var/spool/mail</tt> is deprecated, even
4244 though the spool may still be physically located there.
4245 To maintain partial upgrade compatibility for systems
4246 which have <tt>/var/spool/mail</tt> as their physical mail
4247 spool, packages using <tt>/var/mail</tt> must depend on
4248 either <package>libc6</package> (>= 2.1.3-13), or on
4249 <package>base-files</package> (>= 2.2.0), or on later
4250 versions of either one of these packages.
4256 <heading>Users and groups</heading>
4259 <heading>Introduction</heading>
4261 The Debian system can be configured to use either plain or
4266 Some user ids (UIDs) and group ids (GIDs) are reserved
4267 globally for use by certain packages. Because some
4268 packages need to include files which are owned by these
4269 users or groups, or need the ids compiled into binaries,
4270 these ids must be used on any Debian system only for the
4271 purpose for which they are allocated. This is a serious
4272 restriction, and we should avoid getting in the way of
4273 local administration policies. In particular, many sites
4274 allocate users and/or local system groups starting at 100.
4278 Apart from this we should have dynamically allocated ids,
4279 which should by default be arranged in some sensible
4280 order, but the behavior should be configurable.
4284 Packages other than <tt>base-passwd</tt> must not modify
4285 <tt>/etc/passwd</tt>, <tt>/etc/shadow</tt>,
4286 <tt>/etc/group</tt> or <tt>/etc/gshadow</tt>.
4291 <heading>UID and GID classes</heading>
4293 The UID and GID numbers are divided into classes as
4299 Globally allocated by the Debian project, the same
4300 on every Debian system. These ids will appear in
4301 the <tt>passwd</tt> and <tt>group</tt> files of all
4302 Debian systems, new ids in this range being added
4303 automatically as the <tt>base-passwd</tt> package is
4308 Packages which need a single statically allocated
4309 uid or gid should use one of these; their
4310 maintainers should ask the <tt>base-passwd</tt>
4318 Dynamically allocated system users and groups.
4319 Packages which need a user or group, but can have
4320 this user or group allocated dynamically and
4321 differently on each system, should use <tt>adduser
4322 --system</tt> to create the group and/or user.
4323 <prgn>adduser</prgn> will check for the existence of
4324 the user or group, and if necessary choose an unused
4325 id based on the ranges specified in
4326 <tt>adduser.conf</tt>.
4330 <tag>1000-29999:</tag>
4333 Dynamically allocated user accounts. By default
4334 <prgn>adduser</prgn> will choose UIDs and GIDs for
4335 user accounts in this range, though
4336 <tt>adduser.conf</tt> may be used to modify this
4341 <tag>30000-59999:</tag>
4346 <tag>60000-64999:</tag>
4349 Globally allocated by the Debian project, but only
4350 created on demand. The ids are allocated centrally
4351 and statically, but the actual accounts are only
4352 created on users' systems on demand.
4356 These ids are for packages which are obscure or
4357 which require many statically-allocated ids. These
4358 packages should check for and create the accounts in
4359 <tt>/etc/passwd</tt> or <tt>/etc/group</tt> (using
4360 <prgn>adduser</prgn> if it has this facility) if
4361 necessary. Packages which are likely to require
4362 further allocations should have a `hole' left after
4363 them in the allocation, to give them room to
4368 <tag>65000-65533:</tag>
4376 User <tt>nobody</tt>. The corresponding gid refers
4377 to the group <tt>nogroup</tt>.
4384 <tt>(uid_t)(-1) == (gid_t)(-1)</tt> <em>must
4385 not</em> be used, because it is the error return
4394 <sect id="sysvinit">
4395 <heading>System run levels and <tt>init.d</tt> scripts</heading>
4397 <sect1 id="/etc/init.d">
4398 <heading>Introduction</heading>
4401 The <tt>/etc/init.d</tt> directory contains the scripts
4402 executed by <prgn>init</prgn> at boot time and when the
4403 init state (or `runlevel') is changed (see <manref
4404 name="init" section="8">).
4408 There are at least two different, yet functionally
4409 equivalent, ways of handling these scripts. For the sake
4410 of simplicity, this document describes only the symbolic
4411 link method. However, it must not be assumed by maintainer
4412 scripts that this method is being used, and any automated
4413 manipulation of the various runlevel behaviours by
4414 maintainer scripts must be performed using
4415 <prgn>update-rc.d</prgn> as described below and not by
4416 manually installing or removing symlinks. For information
4417 on the implementation details of the other method,
4418 implemented in the <tt>file-rc</tt> package, please refer
4419 to the documentation of that package.
4423 These scripts are referenced by symbolic links in the
4424 <tt>/etc/rc<var>n</var>.d</tt> directories. When changing
4425 runlevels, <prgn>init</prgn> looks in the directory
4426 <tt>/etc/rc<var>n</var>.d</tt> for the scripts it should
4427 execute, where <tt><var>n</var></tt> is the runlevel that
4428 is being changed to, or <tt>S</tt> for the boot-up
4433 The names of the links all have the form
4434 <tt>S<var>mm</var><var>script</var></tt> or
4435 <tt>K<var>mm</var><var>script</var></tt> where
4436 <var>mm</var> is a two-digit number and <var>script</var>
4437 is the name of the script (this should be the same as the
4438 name of the actual script in <tt>/etc/init.d</tt>).
4442 When <prgn>init</prgn> changes runlevel first the targets
4443 of the links whose names start with a <tt>K</tt> are
4444 executed, each with the single argument <tt>stop</tt>,
4445 followed by the scripts prefixed with an <tt>S</tt>, each
4446 with the single argument <tt>start</tt>. (The links are
4447 those in the <tt>/etc/rc<var>n</var>.d</tt> directory
4448 corresponding to the new runlevel.) The <tt>K</tt> links
4449 are responsible for killing services and the <tt>S</tt>
4450 link for starting services upon entering the runlevel.
4454 For example, if we are changing from runlevel 2 to
4455 runlevel 3, init will first execute all of the <tt>K</tt>
4456 prefixed scripts it finds in <tt>/etc/rc3.d</tt>, and then
4457 all of the <tt>S</tt> prefixed scripts in that directory.
4458 The links starting with <tt>K</tt> will cause the
4459 referred-to file to be executed with an argument of
4460 <tt>stop</tt>, and the <tt>S</tt> links with an argument
4465 The two-digit number <var>mm</var> is used to determine
4466 the order in which to run the scripts: low-numbered links
4467 have their scripts run first. For example, the
4468 <tt>K20</tt> scripts will be executed before the
4469 <tt>K30</tt> scripts. This is used when a certain service
4470 must be started before another. For example, the name
4471 server <prgn>bind</prgn> might need to be started before
4472 the news server <prgn>inn</prgn> so that <prgn>inn</prgn>
4473 can set up its access lists. In this case, the script
4474 that starts <prgn>bind</prgn> would have a lower number
4475 than the script that starts <prgn>inn</prgn> so that it
4477 <example compact="compact">
4484 The two runlevels 0 (halt) and 6 (reboot) are slightly
4485 different. In these runlevels, the links with an
4486 <tt>S</tt> prefix are still called after those with a
4487 <tt>K</tt> prefix, but they too are called with the single
4488 argument <tt>stop</tt>.
4492 Also, if the script name ends <tt>.sh</tt>, the script
4493 will be sourced in runlevel <tt>S</tt> rather that being
4494 run in a forked subprocess, but will be explicitly run by
4495 <prgn>sh</prgn> in all other runlevels.
4500 <heading>Writing the scripts</heading>
4503 Packages that include daemons for system services should
4504 place scripts in <tt>/etc/init.d</tt> to start or stop
4505 services at boot time or during a change of runlevel.
4506 These scripts should be named
4507 <tt>/etc/init.d/<var>package</var></tt>, and they should
4508 accept one argument, saying what to do:
4511 <tag><tt>start</tt></tag>
4512 <item><p>start the service,</p></item>
4514 <tag><tt>stop</tt></tag>
4515 <item><p>stop the service,</p></item>
4517 <tag><tt>restart</tt></tag>
4518 <item><p>stop and restart the service,</p></item>
4520 <tag><tt>reload</tt></tag>
4521 <item><p>cause the configuration of the service to be
4522 reloaded without actually stopping and restarting
4523 the service,</p></item>
4525 <tag><tt>force-reload</tt></tag>
4526 <item><p>cause the configuration to be reloaded if the
4527 service supports this, otherwise restart the
4531 The <tt>start</tt>, <tt>stop</tt>, <tt>restart</tt>, and
4532 <tt>force-reload</tt> options should be supported by all
4533 scripts in <tt>/etc/init.d</tt>, the <tt>reload</tt>
4534 option is optional.</p>
4537 The <tt>init.d</tt> scripts should ensure that they will
4538 behave sensibly if invoked with <tt>start</tt> when the
4539 service is already running, or with <tt>stop</tt> when it
4540 isn't, and that they don't kill unfortunately-named user
4541 processes. The best way to achieve this is usually to use
4542 <prgn>start-stop-daemon</prgn>.</p>
4545 If a service reloads its configuration automatically (as
4546 in the case of <prgn>cron</prgn>, for example), the
4547 <tt>reload</tt> option of the <tt>init.d</tt> script
4548 should behave as if the configuration has been reloaded
4552 The <tt>/etc/init.d</tt> scripts should be treated as
4553 configuration files, either by marking them as
4554 <tt>conffile</tt>s or managing them correctly in the
4555 maintainer scripts (see <ref id="config files">). This is
4556 important since we want to give the local system
4557 administrator the chance to adapt the scripts to the local
4558 system, e.g., to disable a service without de-installing
4559 the package, or to specify some special command line
4560 options when starting a service, while making sure her
4561 changes aren't lost during the next package upgrade.
4565 These scripts should not fail obscurely when the
4566 configuration files remain but the package has been
4567 removed, as configuration files remain on the system after
4568 the package has been removed. Only when <prgn>dpkg</prgn>
4569 is executed with the <tt>--purge</tt> option will
4570 configuration files be removed. In particular, as the
4571 <tt>/etc/init.d/<var>package</var></tt> script itself is
4572 usually a <tt>conffile</tt>, it will remain on the system
4573 if the package is removed but not purged. Therefore, you
4574 should include a <tt>test</tt> statement at the top of the
4576 <example compact="compact">
4577 test -f <var>program-executed-later-in-script</var> || exit 0
4582 Often there are some variables in the <tt>init.d</tt>
4583 scripts whose values control the bahaviour of the scripts,
4584 and which a system administrator is likely to want to
4585 change. As the scripts themselves are frequently
4586 <tt>conffile</tt>s, modifying them requires that the
4587 administrator merge in their changes each time the package
4588 is upgraded and the <tt>conffile</tt> changes. To ease
4589 the burden on the system administrator, such configurable
4590 values should not be placed directly in the script.
4591 Instead, they should be placed in a file in
4592 <tt>/etc/default</tt>, which typically will have the same
4593 base name as the <tt>init.d</tt> script. This extra file
4594 should be sourced by the script when the script runs. It
4595 must contain only variable settings and comments in POSIX
4596 <prgn>sh</prgn> format. It may either be a
4597 <tt>conffile</tt> or a configuration file maintained by
4598 the package maintainer scripts. See <ref id="config files">
4603 To ensure that vital configurable values are always
4604 available, the <tt>init.d</tt> script should set default
4605 values for each of the shell variables it uses, either
4606 before sourcing the <tt>/etc/default/</tt> file or
4607 afterwards using something like the <tt>:
4608 ${VAR:=default}</tt> syntax. Also, the <tt>init.d</tt>
4609 script must behave sensibly and not fail if the
4610 <tt>/etc/default</tt> file is deleted.
4615 <heading>Managing the links</heading>
4618 The program <prgn>update-rc.d</prgn> is provided for
4619 package maintainers to arrange for the proper creation and
4620 removal of <tt>/etc/rc<var>n</var>.d</tt> symbolic links,
4621 or their functional equivalent if another method is being
4622 used. This may be used by maintainers in their packages'
4623 <prgn>postinst</prgn> and <prgn>postrm</prgn> scripts.</p>
4626 You must not include any <tt>/etc/rc<var>n</var>.d</tt>
4627 symbolic links in the actual archive or manually create or
4628 remove the symbolic links in maintainer scripts; you must
4629 use the <prgn>update-rc.d</prgn> program instead. (The
4630 former will fail if an alternative method of maintaining
4631 runlevel information is being used.) You must not include
4632 the <tt>/etc/rc<var>n</var>.d</tt> directories themselves
4633 in the archive either. (Only the <tt>sysvinit</tt>
4638 By default <prgn>update-rc.d</prgn> will start services in
4639 each of the multi-user state runlevels (2, 3, 4, and 5)
4640 and stop them in the halt runlevel (0), the single-user
4641 runlevel (1) and the reboot runlevel (6). The system
4642 administrator will have the opportunity to customize
4643 runlevels by simply adding, moving, or removing the
4644 symbolic links in <tt>/etc/rc<var>n</var>.d</tt> if
4645 symbolic links are being used, or by modifying
4646 <tt>/etc/runlevel.conf</tt> if the <tt>file-rc</tt> method
4651 To get the default behavior for your package, put in your
4652 <prgn>postinst</prgn> script
4653 <example compact="compact">
4654 update-rc.d <var>package</var> defaults >/dev/null
4656 and in your <prgn>postrm</prgn>
4657 <example compact="compact">
4658 if [ "$1" = purge ]; then
4659 update-rc.d <var>package</var> remove >/dev/null
4664 This will use a default sequence number of 20. If it does
4665 not matter when or in which order the <tt>init.d</tt>
4666 script is run, use this default. If it does, then you
4667 should talk to the maintainer of the <prgn>sysvinit</prgn>
4668 package or post to <tt>debian-devel</tt>, and they will
4669 help you choose a number.
4673 For more information about using <tt>update-rc.d</tt>,
4674 please consult its manpage <manref name="update-rc.d"
4681 <heading>Boot-time initialization</heading>
4684 There used to be another directory, <tt>/etc/rc.boot</tt>,
4685 which contained scripts which were run once per machine
4686 boot. This has been deprecated in favour of links from
4687 <tt>/etc/rcS.d</tt> to files in <tt>/etc/init.d</tt> as
4688 described in <ref id="/etc/init.d">. Packages must not
4689 place files in <tt>/etc/rc.boot</tt>.</p>
4692 <heading>Example</heading>
4695 The <prgn>bind</prgn> DNS (nameserver) package wants to
4696 make sure that the nameserver is running in multiuser
4697 runlevels, and is properly shut down with the system. It
4698 puts a script in <tt>/etc/init.d</tt>, naming the script
4699 appropriately <tt>bind</tt>. As you can see, the script
4700 interprets the argument <tt>reload</tt> to send the
4701 nameserver a <tt>HUP</tt> signal (causing it to reload its
4702 configuration); this way the system administrator can say
4703 <tt>/etc/init.d/bind reload</tt> to reload the name
4704 server. The script has one configurable value, which can
4705 be used to pass parameters to the named program at
4706 startup; this value is read from
4707 <tt>/etc/default/bind</tt> (see below).
4711 <example compact="compact">
4714 # Original version by Robert Leslie
4715 # <rob@mars.org>, edited by iwj and cs
4717 test -x /usr/sbin/named || exit 0
4719 # Source defaults file.
4721 if [ -f /etc/default/bind ]; then
4728 echo -n "Starting domain name service: named"
4729 start-stop-daemon --start --quiet --exec /usr/sbin/named \
4734 echo -n "Stopping domain name service: named"
4735 start-stop-daemon --stop --quiet \
4736 --pidfile /var/run/named.pid --exec /usr/sbin/named
4740 echo -n "Restarting domain name service: named"
4741 start-stop-daemon --stop --quiet \
4742 --pidfile /var/run/named.pid --exec /usr/sbin/named
4743 start-stop-daemon --start --verbose --exec /usr/sbin/named \
4747 force-reload|reload)
4748 echo -n "Reloading configuration of domain name service: named"
4749 start-stop-daemon --stop --signal 1 --quiet \
4750 --pidfile /var/run/named.pid --exec /usr/sbin/named
4754 echo "Usage: /etc/init.d/bind {start|stop|restart|reload|force-reload}" >&2
4764 Complementing the above init script is a configuration
4765 file <tt>/etc/default/bind</tt>, which contains
4766 configurable parameters used by the script. This would be
4767 created by the <prgn>postinst</prgn> script if it was not
4768 already present, and removed on purge by the
4769 <prgn>postrm</prgn> script.
4770 <example compact="compact">
4771 # Specified parameters to pass to named. See named(8).
4772 # You may uncomment the following line, and edit to taste.
4778 Another example on which you can base your
4779 <tt>/etc/init.d</tt> scripts is found in
4780 <tt>/etc/init.d/skeleton</tt>.
4784 If this package is happy with the default setup from
4785 <prgn>update-rc.d</prgn>, namely an ordering number of 20
4786 and having named running in all runlevels, it can say in
4787 its <prgn>postinst</prgn>:
4788 <example compact="compact">
4789 update-rc.d bind defaults >/dev/null
4791 And in its <prgn>postrm</prgn>, to remove the links when the
4793 <example compact="compact">
4794 if [ "$1" = purge ]; then
4795 update-rc.d bind remove >/dev/null
4803 <heading>Console messages from <tt>init.d</tt> scripts</heading>
4806 This section describes the formats to be used for messages
4807 written to standard output by the <tt>/etc/init.d</tt>
4808 scripts. The intent is to improve the consistency of
4809 Debian's startup and shutdown look and feel. For this
4810 reason, please look very carefully at the details. We want
4811 the messages to have the same format in terms of wording,
4812 spaces, punctuation and case of letters.
4816 Here is a list of overall rules that you should use when you
4817 create output messages. They can be useful if you have a
4818 non-standard message that is not covered specifically in the
4826 Every message should fit in one line (fewer than 80
4827 characters), start with a capital letter and end with
4828 a period (<tt>.</tt>) and line feed (<tt>"\n"</tt>).
4834 If you want to express that the computer is working on
4835 something (that is, performing a specific task, not
4836 starting or stopping a program), we use an "ellipsis"
4837 (three dots: <tt>...</tt>). Note that we don't insert
4838 spaces before or after the dots. If the task has been
4839 completed we write <tt>done.</tt> and a line feed.
4845 Design your messages as if the computer is telling you
4846 what he is doing (let him be polite :-), but don't
4847 mention "him" directly. For example, if you think of
4849 <example compact="compact">
4850 I'm starting network daemons: nfsd mountd.
4853 <example compact="compact">
4854 Starting network daemons: nfsd mountd.
4862 There are standard message formats for the following
4863 situations. They should be used by the <tt>init.d</tt>
4870 <p>When daemons are started</p>
4873 If your script starts one or more daemons, the output
4874 should look like this (a single line, no leading
4876 <example compact="compact">
4877 Starting <var>description</var>: <var>daemon-1</var> ... <var>daemon-n</var>.
4879 The <var>description</var> should describe the
4880 subsystem the daemon or set of daemons are part of,
4881 while <var>daemon-1</var> up to <var>daemon-n</var>
4882 denote each daemon's name (typically the file name of
4887 For example, the output of <tt>/etc/init.d/lpd</tt>
4889 <example compact="compact">
4890 Starting printer spooler: lpd.
4895 This can be achieved by saying
4896 <example compact="compact">
4897 echo -n "Starting printer spooler: lpd"
4898 start-stop-daemon --start --quiet --exec /usr/sbin/lpd
4901 in the script. If you have more than one daemon to
4902 start, you should do the following:
4903 <example compact="compact">
4904 echo -n "Starting remote file system services:"
4905 echo -n " nfsd"; start-stop-daemon --start --quiet nfsd
4906 echo -n " mountd"; start-stop-daemon --start --quiet mountd
4907 echo -n " ugidd"; start-stop-daemon --start --quiet ugidd
4910 This makes it possible for the user to see what takes
4911 so long and when the final daemon has been started.
4912 You should be careful where to put spaces: in the
4913 example above the system administrator can easily
4914 comment out a line if he don't wants to start a
4915 specific daemon, while the displayed message still
4921 <p>When a system parameter is being set</p>
4924 If you have to set up different system parameters
4925 during the system boot, you should use this format:
4926 <example compact="compact">
4927 Setting <var>parameter</var> to `<var>value</var>'.
4932 You can use a statement such as the following to get
4934 <example compact="compact">
4935 echo "Setting DNS domainname to \`$domainname'."
4940 Note that the left quotation mark (<tt>`</tt>) is
4941 different from the right one (<tt>'</tt>).
4946 <p>When a daemon is stopped or restarted</p>
4949 When you stop or restart a daemon, you should issue a
4950 message identical to the startup message, except that
4951 <tt>Starting</tt> is replaced with <tt>Stopping</tt>
4952 or <tt>Restarting</tt> respectively.
4956 For example, stopping the printer daemon will like
4958 <example compact="compact">
4959 Stopping printer spooler: lpd.
4965 <p>When something is executed</p>
4968 There are several examples where you have to run a
4969 program at system startup or shutdown to perform a
4970 specific task, for example, setting the system's clock
4971 using <prgn>netdate</prgn> or killing all processes
4972 when the system shuts down. Your message should look
4974 <example compact="compact">
4975 Doing something very useful...done.
4977 You should print the <tt>done.</tt> immediately after
4978 the job has been completed, so that the user is
4979 informed why she has to wait. You can get this
4981 <example compact="compact">
4982 echo -n "Doing something very useful..."
4991 <p>When the configuration is reloaded</p>
4994 When a daemon is forced to reload its configuration
4995 files you should use the following format:
4996 <example compact="compact">
4997 Reloading <var>description</var> configuration...done.
4999 where <var>description</var> is the same as in the
5000 daemon starting message.
5008 <heading>Cron jobs</heading>
5011 Packages must not modify the configuration file
5012 <tt>/etc/crontab</tt>, and they must not modify the files in
5013 <tt>/var/spool/cron/crontabs</tt>.</p>
5016 If a package wants to install a job that has to be executed
5017 via cron, it should place a file with the name of the
5018 package in one or more of the following directories:
5019 <example compact="compact">
5024 As these directory names imply, the files within them are
5025 executed on a daily, weekly, or monthly basis,
5026 respectively. The exact times are listed in
5027 <tt>/etc/crontab</tt>.</p>
5030 All files installed in any of these directories must be
5031 scripts (e.g., shell scripts or Perl scripts) so that they
5032 can easily be modified by the local system administrator.
5033 In addition, they should be treated as configuration
5038 If a certain job has to be executed more frequently than
5039 daily, the package should install a file
5040 <tt>/etc/cron.d/<var>package</var></tt>. This file uses the
5041 same syntax as <tt>/etc/crontab</tt> and is processed by
5042 <prgn>cron</prgn> automatically. The file must also be
5043 treated as a configuration file. (Note that entries in the
5044 <tt>/etc/cron.d</tt> directory are not handled by
5045 <prgn>anacron</prgn>. Thus, you should only use this
5046 directory for jobs which may be skipped if the system is not
5050 The scripts or crontab entries in these directories should
5051 check if all necessary programs are installed before they
5052 try to execute them. Otherwise, problems will arise when a
5053 package was removed but not purged since configuration files
5054 are kept on the system in this situation.</p>
5058 <heading>Menus</heading>
5061 Menu entries should follow the current menu policy found in
5062 the <tt>menu-policy</tt> files in the <tt>debian-policy</tt>
5063 package. It may also be found on the Debian FTP site
5064 <ftpsite>ftp.debian.org</ftpsite> as the file
5065 <ftppath>/debian/doc/package-developer/menu-policy.txt.gz</ftppath>,
5066 or in the equivalent location on your local mirror.
5070 The Debian <tt>menu</tt> package provides a standard
5071 interface between packages providing applications and
5072 documents, and <em>menu programs</em> (either X window
5073 managers or text-based menu programs such as
5074 <prgn>pdmenu</prgn>).
5078 All packages that provide applications that need not be
5079 passed any special command line arguments for normal
5080 operation should register a menu entry for those
5081 applications, so that users of the <tt>menu</tt> package
5082 will automatically get menu entries in their window
5083 managers, as well in shells like <tt>pdmenu</tt>.</p>
5086 Please also refer to the <em>Debian Menu System</em>
5087 documentation that comes with the <tt>menu</tt> package for
5088 information about how to register your applications and web
5094 <heading>Multimedia handlers</heading>
5097 Packages which provide the ability to view/show/play,
5098 compose, edit or print MIME types should register themselves
5099 as such following the current MIME support policy found in
5100 the <tt>mime-policy</tt> files in the <tt>debian-policy</tt>
5101 package. It may also be found on the Debian FTP site
5102 <ftpsite>ftp.debian.org</ftpsite> as the file
5103 <ftppath>/debian/doc/package-developer/mime-policy.txt.gz</ftppath>,
5104 or in the equivalent location on your local mirror.
5108 MIME (Multipurpose Internet Mail Extensions, RFCs 2045-2049)
5109 is a mechanism for encoding files and data streams and
5110 providing meta-information about them, in particular their
5111 type (e.g. audio or video) and format (e.g. PNG, HTML,
5116 Registration of MIME type handlers allows programs like mail
5117 user agents and web browsers to to invoke these handlers to
5118 view, edit or display MIME types they don't support
5124 <heading>Keyboard configuration</heading>
5127 To achieve a consistent keyboard configuration so that all
5128 applications interpret a keyboard event the same way, all
5129 programs in the Debian distribution must be configured to
5130 comply with the following guidelines.
5134 The following keys must have the specified interpretations:
5137 <tag><tt><--</tt></tag>
5138 <item><p>delete the character to the left of the cursor</p></item>
5140 <tag><tt>Delete</tt></tag>
5141 <item><p>delete the character to the right of the cursor</p></item>
5143 <tag><tt>Control+H</tt></tag>
5144 <item><p>emacs: the help prefix</p></item>
5147 The interpretation of any keyboard events should be
5148 independent of the terminal that is used, be it a virtual
5149 console, an X terminal emulator, an rlogin/telnet session,
5154 The following list explains how the different programs
5155 should be set up to achieve this:
5160 <item><p><tt><--</tt> generates <tt>KB_Backspace</tt>
5163 <item><p><tt>Delete</tt> generates <tt>KB_Delete</tt> in
5168 X translations are set up to make
5169 <tt>KB_Backspace</tt> generate ASCII DEL, and to make
5170 <tt>KB_Delete</tt> generate <tt>ESC [ 3 ~</tt> (this
5171 is the vt220 escape code for the `delete character'
5172 key). This must be done by loading the X resources
5173 using <prgn>xrdb</prgn> on all local X displays, not
5174 using the application defaults, so that the
5175 translation resources used correspond to the
5176 <prgn>xmodmap</prgn> settings.</p></item>
5180 The Linux console is configured to make
5181 <tt><--</tt> generate DEL, and <tt>Delete</tt>
5182 generate <tt>ESC [ 3 ~</tt>.</p></item>
5186 X applications are configured so that <tt><</tt>
5187 deletes left, and <tt>Delete</tt> deletes right. Motif
5188 applications already work like this.</p></item>
5190 <item><p>Terminals should have <tt>stty erase ^?</tt> .</p></item>
5194 The <tt>xterm</tt> terminfo entry should have <tt>ESC
5195 [ 3 ~</tt> for <tt>kdch1</tt>, just as for
5196 <tt>TERM=linux</tt> and <tt>TERM=vt220</tt>.</p></item>
5200 Emacs is programmed to map <tt>KB_Backspace</tt> or
5201 the <tt>stty erase</tt> character to
5202 <tt>delete-backward-char</tt>, and <tt>KB_Delete</tt>
5203 or <tt>kdch1</tt> to <tt>delete-forward-char</tt>, and
5204 <tt>^H</tt> to <tt>help</tt> as always.</p></item>
5208 Other applications use the <tt>stty erase</tt>
5209 character and <tt>kdch1</tt> for the two delete keys,
5210 with ASCII DEL being `delete previous character' and
5211 <tt>kdch1</tt> being `delete character under
5218 This will solve the problem except for the following
5226 Some terminals have a <tt><--</tt> key that cannot
5227 be made to produce anything except <tt>^H</tt>. On
5228 these terminals Emacs help will be unavailable on
5229 <tt>^H</tt> (assuming that the <tt>stty erase</tt>
5230 character takes precedence in Emacs, and has been set
5231 correctly). <tt>M-x help</tt> or <tt>F1</tt> (if
5232 available) can be used instead.</p></item>
5236 Some operating systems use <tt>^H</tt> for <tt>stty
5237 erase</tt>. However, modern telnet versions and all
5238 rlogin versions propagate <tt>stty</tt> settings, and
5239 almost all UNIX versions honour <tt>stty erase</tt>.
5240 Where the <tt>stty</tt> settings are not propagated
5241 correctly, things can be made to work by using
5242 <tt>stty</tt> manually.</p></item>
5246 Some systems (including previous Debian versions) use
5247 <prgn>xmodmap</prgn> to arrange for both
5248 <tt><--</tt> and <tt>Delete</tt> to generate
5249 <tt>KB_Delete</tt>. We can change the behavior of
5250 their X clients using the same X resources that we use
5251 to do it for our own clients, or configure our clients
5252 using their resources when things are the other way
5253 around. On displays configured like this
5254 <tt>Delete</tt> will not work, but <tt><--</tt>
5259 Some operating systems have different <tt>kdch1</tt>
5260 settings in their <tt>terminfo</tt> database for
5261 <tt>xterm</tt> and others. On these systems the
5262 <tt>Delete</tt> key will not work correctly when you
5263 log in from a system conforming to our policy, but
5264 <tt><--</tt> will.</p></item>
5270 <heading>Environment variables</heading>
5273 A program must not depend on environment variables to get
5274 reasonable defaults. (That's because these environment
5275 variables would have to be set in a system-wide
5276 configuration file like <tt>/etc/profile</tt>, which is not
5277 supported by all shells.)</p>
5280 If a program usually depends on environment variables for its
5281 configuration, the program should be changed to fall back to
5282 a reasonable default configuration if these environment
5283 variables are not present. If this cannot be done easily
5284 (e.g., if the source code of a non-free program is not
5285 available), the program must be replaced by a small
5286 `wrapper' shell script which sets the environment variables
5287 if they are not already defined, and calls the original program.</p>
5290 Here is an example of a wrapper script for this purpose:
5292 <example compact="compact">
5294 BAR=${BAR:-/var/lib/fubar}
5296 exec /usr/lib/foo/foo "$@"
5301 Furthermore, as <tt>/etc/profile</tt> is a configuration
5302 file of the <prgn>base-files</prgn> package, other packages must not
5303 put any environment variables or other commands into that
5309 <heading>Files</heading>
5312 <heading>Binaries</heading>
5315 Two different packages must not install programs with
5316 different functionality but with the same filenames. (The
5317 case of two programs having the same functionality but
5318 different implementations is handled via `alternatives' or
5319 the `Conflicts' mechanism. See <ref id="maintscripts"> and
5320 <ref id="conflicts"> respectively.) If this case happens,
5321 one of the programs must be renamed. The maintainers should
5322 report this to the <tt>debian-devel</tt> mailing list and
5323 try to find a consensus about which program will have to be
5324 renamed. If a consensus cannot be reached, <em>both</em>
5325 programs must be renamed.
5329 Generally the following compilation parameters should be used:
5330 <example compact="compact">
5332 CFLAGS = -O2 -Wall # sane warning options vary between programs
5334 install -s # (or use strip on the files in debian/tmp)
5338 Note that by default all installed binaries should be stripped,
5339 either by using the <tt>-s</tt> flag to
5340 <prgn>install</prgn>, or by calling <prgn>strip</prgn> on
5341 the binaries after they have been copied into
5342 <tt>debian/tmp</tt> but before the tree is made into a
5346 The <tt>-N</tt> flag should not be used. On <tt>a.out</tt>
5347 systems it may have been useful for some very small
5348 binaries, but for ELF it has no good effect.</p>
5351 Debugging symbols are useful for error diagnosis,
5352 investigation of core dumps (which may be submitted by users
5353 in bug reports), or testing and developing the software.
5354 Therefore it is recommended to support building the package
5355 with debugging information through the following interface:
5356 If the environment variable <tt>DEB_BUILD_OPTIONS</tt>
5357 contains the string <tt>debug</tt>, compile the software
5358 with debugging information (usually this involves adding the
5359 <tt>-g</tt> flag to <tt>CFLAGS</tt>). This allows the
5360 generation of a build tree with debugging information. If
5361 the environment variable <tt>DEB_BUILD_OPTIONS</tt> contains
5362 the string <tt>nostrip</tt>, do not strip the files at
5363 installation time. This allows one to generate a package
5364 with debugging information included.<footnote>
5366 Rationale: Using <tt>-g</tt> by default causes wasted
5367 CPU cycles since the information is stripped away
5368 anyway; this can have a significant impact on the
5369 efficiency of the autobuilders. Having a standard way
5370 to build a debugging variant also makes it easier to
5371 build debugging bins and libraries since it provides a
5372 documented way of getting this type of build; one does
5373 not have to manually edit <tt>debian/rules</tt> or
5377 The following makefile snippet is an example of how one may
5378 test for either condition; you will probably have to massage
5379 this example in order to make it work for your package.
5380 <example compact="compact">
5383 INSTALL_FILE = $(INSTALL) -p -o root -g root -m 644
5384 INSTALL_PROGRAM = $(INSTALL) -p -o root -g root -m 755
5385 INSTALL_SCRIPT = $(INSTALL) -p -o root -g root -m 755
5386 INSTALL_DIR = $(INSTALL) -p -d -o root -g root -m 755
5388 ifneq (,$(findstring debug,$(DEB_BUILD_OPTIONS)))
5391 ifeq (,$(findstring nostrip,$(DEB_BUILD_OPTIONS)))
5392 INSTALL_PROGRAM += -s
5398 It is up to the package maintainer to decide what
5399 compilation options are best for the package. Certain
5400 binaries (such as computationally-intensive programs) will
5401 function better with certain flags (<tt>-O3</tt>, for
5402 example); feel free to use them. Please use good judgment
5403 here. Don't use flags for the sake of it; only use them
5404 if there is good reason to do so. Feel free to override
5405 the upstream author's ideas about which compilation
5406 options are best: they are often inappropriate for our
5407 environment.</p></sect>
5411 <heading>Libraries</heading>
5414 All libraries must have a shared version in the
5415 <tt>lib*</tt> package and a static version in the
5416 <tt>lib*-dev</tt> package. The shared version must be
5417 compiled with <tt>-fPIC</tt>, and the static version must
5418 not be. In other words, each <tt>*.c</tt> file will need to
5419 be compiled twice.</p>
5422 You must specify the gcc option <tt>-D_REENTRANT</tt>
5423 when building a library (either static or shared) to make
5424 the library compatible with LinuxThreads.</p>
5427 Note that all installed shared libraries should be
5429 <example compact="compact">
5430 strip --strip-unneeded <var>your-lib</var>
5432 (The option <tt>--strip-unneeded</tt> makes
5433 <prgn>strip</prgn> remove only the symbols which aren't
5434 needed for relocation processing.) Shared libraries can
5435 function perfectly well when stripped, since the symbols for
5436 dynamic linking are in a separate part of the ELF object
5439 You might also want to use the options
5440 <tt>--remove-section=.comment</tt> and
5441 <tt>--remove-section=.note</tt> on both shared libraries
5442 and executables, and <tt>--strip-debug</tt> on static
5449 Note that under some circumstances it may be useful to
5450 install a shared library unstripped, for example when
5451 building a separate package to support debugging.
5455 Shared object files (often <tt>.so</tt> files) that are not
5456 public libraries, that is, they are not meant to be linked
5457 to by third party executables (binaries of other packages),
5458 should be installed in subdirectories of the
5459 <tt>/usr/lib</tt> directory. Such files are exempt from the
5460 rules that govern ordinary shared libraries, except that
5461 they must not be installed executable and should be
5464 A common example are the so-called ``plug-ins'',
5465 internal shared objects that are dynamically loaded by
5466 programs using <manref name="dlopen" section="3">.
5472 Packages containing shared libraries that may be linked to
5473 by other packages' binaries, but which for some
5474 <em>compelling</em> reason can not be installed in
5475 <tt>/usr/lib</tt> directory, may install the shared library
5476 files in subdirectories of the <tt>/usr/lib</tt> directory,
5477 in which case they should arrange to add that directory in
5478 <tt>/etc/ld.so.conf</tt> in the package's post-installation
5479 script, and remove it in the package's post-removal script.
5483 An ever increasing number of packages are using
5484 <prgn>libtool</prgn> to do their linking. The latest GNU
5485 libtools (>= 1.3a) can take advantage of the metadata in the
5486 installed <prgn>libtool</prgn> archive files (<tt>*.la</tt>
5487 files). The main advantage of <prgn>libtool</prgn>'s
5488 <tt>.la</tt> files is that it allows <prgn>libtool</prgn> to
5489 store and subsequently access metadata with respect to the
5490 libraries it builds. <prgn>libtool</prgn> will search for
5491 those files, which contain a lot of useful information about
5492 a library (such as library dependency information for static
5493 linking). Also, they're <em>essential</em> for programs
5494 using <tt>libltdl</tt>.<footnote>
5496 Although <prgn>libtool</prgn> is fully capable of
5497 linking against shared libraries which don't have
5498 <tt>.la</tt> files, as it is a mere shell script it can
5499 add considerably to the build time of a
5500 <prgn>libtool</prgn>-using package if that shell script
5501 has to derive all this information from first principles
5502 for each library every time it is linked. With the
5503 advent of <prgn>libtool</prgn> version 1.4 (and to a
5504 lesser extent <prgn>libtool</prgn> version 1.3), the
5505 <tt>.la</tt> files also store information about
5506 inter-library dependencies which cannot necessarily be
5507 derived after the <tt>.la</tt> file is deleted.
5513 Packages that use <prgn>libtool</prgn> to create shared
5514 libraries should include the <tt>.la</tt> files in the
5515 <tt>-dev</tt> package, unless the package relies on
5516 <tt>libtool</tt>'s <tt>libltdl</tt> library, in which case
5517 the <tt>.la</tt> files must go in the run-time library
5522 You must make sure that you use only released versions of
5523 shared libraries to build your packages; otherwise other
5524 users will not be able to run your binaries
5525 properly. Producing source packages that depend on
5526 unreleased compilers is also usually a bad
5532 <heading>Shared libraries</heading>
5535 Packages involving shared libraries should be split up
5536 into several binary packages.</p>
5539 For a straightforward library which has a development
5540 environment and a runtime kit including just shared
5541 libraries you need to create two packages:
5542 <tt><var>libraryname</var><var>soversion</var></tt>, where
5543 <tt><var>soversion</var></tt> is the version number in the
5544 soname of the shared library<footnote>
5546 The soname is the shared object name: it's the thing
5547 that has to match exactly between building an executable
5548 and running it for the dynamic linker to be able run the
5549 program. For example, if the soname of the library is
5550 <tt>libfoo.so.6</tt>, the library package would be
5551 called <tt>libfoo6</tt>.
5554 and <tt><var>libraryname</var><var>soversion</var>-dev</tt>.
5558 If you prefer only to support one development version at a
5559 time you may name the development package
5560 <tt><var>libraryname</var>-dev</tt>; otherwise you may need
5561 to use <prgn>dpkg</prgn>'s Conflicts mechanism (see <ref
5562 id="conflicts">) to ensure that the user only installs one
5563 development version at a time (as different development
5564 versions are likely to have the same header files in them,
5565 which would cause a filename clash if both were installed).
5566 Typically the development version should also have an exact
5567 version dependency on the runtime library, to make sure that
5568 compilation and linking happens correctly. The
5569 <tt>${Source-Version}</tt> substitution variable can be
5570 useful for this purpose.
5574 Packages which use the shared library should have a
5575 dependency on the name of the shared library package,
5576 <tt><var>libraryname</var><var>soversion</var></tt>. When
5577 the soname changes you can have both versions of the library
5578 installed while migrating from the old library to the new.
5582 If your package has some run-time support programs which use
5583 the shared library you must not put them in the shared
5584 library package. If you do that then you won't be able to
5585 install several versions of the shared library without
5586 getting filename clashes. Instead, either create a third
5587 package for the runtime binaries (this package might
5588 typically be named <tt><var>libraryname</var>-runtime</tt>;
5589 note the absence of the <var>soversion</var> in the package
5590 name), or if the development package is small you may
5591 include them in there.
5595 If you have several shared libraries built from the same
5596 source tree you may lump them all together into a single
5597 shared library package, provided that you change all of
5598 their sonames at once (so that you don't get filename
5599 clashes if you try to install different versions of the
5600 combined shared libraries package).
5604 Shared libraries should not be installed executable, since
5605 the dynamic linker does not require this and trying to
5606 execute a shared library usually results in a core dump.
5611 <heading>Scripts</heading>
5614 All command scripts, including the package maintainer
5615 scripts inside the package and used by <prgn>dpkg</prgn>,
5616 should have a <tt>#!</tt> line naming the shell to be used
5617 to interpret them.</p>
5620 In the case of Perl scripts this should be
5621 <tt>#!/usr/bin/perl</tt>.</p>
5624 Shell scripts (<prgn>sh</prgn> and <prgn>bash</prgn>)
5625 should almost certainly start with <tt>set -e</tt> so that
5626 errors are detected. Every script should use
5627 <tt>set -e</tt> or check the exit status of <em>every</em>
5631 The standard shell interpreter <tt>/bin/sh</tt> can be a
5632 symbolic link to any POSIX compatible shell, if <tt>echo
5633 -n</tt> does not generate a newline.<footnote>
5635 Debian policy specifies POSIX behavior for
5636 <tt>/bin/sh</tt>, but <tt>echo -n</tt> has widespread
5637 use in the Linux community (in particular including this
5638 policy, the Linux kernel source, many Debian scripts,
5639 etc.). This <tt>echo -n</tt> mechanism is valid but not
5640 required under POSIX, hence this explicit addition.
5641 Also, rumour has it that this shall be mandated under
5645 Thus, shell scripts specifying <tt>/bin/sh</tt> as
5646 interpreter should only use POSIX features. If a script
5647 requires non-POSIX features from the shell interpreter, the
5648 appropriate shell must be specified in the first line of the
5649 script (e.g., <tt>#!/bin/bash</tt>) and the package must
5650 depend on the package providing the shell (unless the shell
5651 package is marked `Essential', as in the case of
5656 You may wish to restrict your script to POSIX features when
5657 possible so that it may use <tt>/bin/sh</tt> as its
5658 interpreter. If your script works with <prgn>ash</prgn>,
5659 it's probably POSIX compliant, but if you are in doubt, use
5664 Perl scripts should check for errors when making any
5665 system calls, including <tt>open</tt>, <tt>print</tt>,
5666 <tt>close</tt>, <tt>rename</tt> and <tt>system</tt>.
5670 <prgn>csh</prgn> and <prgn>tcsh</prgn> should be avoided as
5671 scripting languages. See <em>Csh Programming Considered
5672 Harmful</em>, one of the <tt>comp.unix.*</tt> FAQs, which
5673 can be found at <url
5674 id="http://language.perl.com/versus/csh.whynot">.<footnote>
5676 It can also be found on
5677 <url id="http://www.cpan.org/doc/FMTEYEWTK/versus/csh.whynot">
5678 or on the ftp site <ftpsite>ftp.cpan.org</ftpsite> as
5679 <ftppath>/pub/perl/CPAN/doc/FMTEYEWTK/versus/csh.whynot</ftppath>.
5682 If an upstream package comes with <prgn>csh</prgn> scripts
5683 then you must make sure that they start with
5684 <tt>#!/bin/csh</tt> and make your package depend on the
5685 <prgn>c-shell</prgn> virtual package.
5689 Any scripts which create files in world-writeable
5690 directories (e.g., in <tt>/tmp</tt>) must use a
5691 mechanism which will fail if a file with the same name
5695 The Debian base system provides the <prgn>tempfile</prgn>
5696 and <prgn>mktemp</prgn> utilities for use by scripts for
5697 this purpose.</p></sect>
5701 <heading>Symbolic links</heading>
5704 In general, symbolic links within a top-level directory
5705 should be relative, and symbolic links pointing from one
5706 top-level directory into another should be absolute. (A
5707 top-level directory is a sub-directory of the root
5708 directory <tt>/</tt>.)</p>
5711 In addition, symbolic links should be specified as short as
5712 possible, i.e., link targets like <tt>foo/../bar</tt> are
5716 Note that when creating a relative link using
5717 <prgn>ln</prgn> it is not necessary for the target of the
5718 link to exist relative to the working directory you're
5719 running <prgn>ln</prgn> from, nor is it necessary to change
5720 directory to the directory where the link is to be made.
5721 Simply include the string that should appear as the target
5722 of the link (this will be a pathname relative to the
5723 directory in which the link resides) as the first argument
5724 to <prgn>ln</prgn>.</p>
5727 For example, in your <prgn>Makefile</prgn> or
5728 <tt>debian/rules</tt>, you can do things like:
5729 <example compact="compact">
5730 ln -fs gcc $(prefix)/bin/cc
5731 ln -fs gcc debian/tmp/usr/bin/cc
5732 ln -fs ../sbin/sendmail $(prefix)/bin/runq
5733 ln -fs ../sbin/sendmail debian/tmp/usr/bin/runq
5737 A symbolic link pointing to a compressed file should always
5738 have the same file extension as the referenced file. (For
5739 example, if a file <tt>foo.gz</tt> is referenced by a
5740 symbolic link, the filename of the link has to end with
5741 `<tt>.gz</tt>' too, as in <tt>bar.gz</tt>.)
5746 <heading>Device files</heading>
5749 Packages must not include device files in the package file
5753 If a package needs any special device files that are not
5754 included in the base system, it must call
5755 <prgn>MAKEDEV</prgn> in the <prgn>postinst</prgn> script,
5756 after asking the user for permission to do so.</p>
5759 Packages must not remove any device files in the
5760 <prgn>postrm</prgn> or any other script. This is left to the
5761 system administrator.</p>
5764 Debian uses the serial devices
5765 <tt>/dev/ttyS*</tt>. Programs using the old
5766 <tt>/dev/cu*</tt> devices should be changed to use
5767 <tt>/dev/ttyS*</tt>.</p>
5770 <sect id="config files">
5771 <heading>Configuration files</heading>
5773 <heading>Definitions</heading>
5776 <tag>configuration file</tag>
5779 A file that affects the operation of a program, or
5780 provides site- or host-specific information, or
5781 otherwise customizes the behavior of a program.
5782 Typically, configuration files are intended to be
5783 modified by the system administrator (if needed or
5784 desired) to conform to local policy or to provide
5785 more useful site-specific behavior.
5789 <tag><tt>conffile</tt></tag>
5792 A file listed in a package's <tt>conffiles</tt>
5793 file, and is treated specially by <prgn>dpkg</prgn>
5794 (see <ref id="configdetails">).
5801 The distinction between these two is important; they are
5802 not interchangeable concepts. Almost all
5803 <tt>conffile</tt>s are configuration files, but many
5804 configuration files are not <tt>conffiles</tt>.
5808 Note that a script that embeds configuration information
5809 (such as most of the files in <tt>/etc/default</tt> and
5810 <tt>/etc/cron.{daily,weekly,monthly}</tt>) is de-facto a
5811 configuration file and should be treated as such.
5816 <heading>Location</heading>
5818 Any configuration files created or used by your package
5819 must reside in <tt>/etc</tt>. If there are several you
5820 should consider creating a subdirectory of <tt>/etc</tt>
5821 named after your package.</p>
5824 If your package creates or uses configuration files
5825 outside of <tt>/etc</tt>, and it is not feasible to modify
5826 the package to use the <tt>/etc</tt>, you should still put
5827 the files in <tt>/etc</tt> and create symbolic links to
5828 those files from the location that the package
5833 <heading>Behavior</heading>
5835 Configuration file handling must conform to the following
5837 <list compact="compact">
5840 local changes must be preserved during a package
5846 configuration files must be preserved when the
5847 package is removed, and only deleted when the
5855 The easy way to achieve this behavior is to make the
5856 configuration file a <tt>conffile</tt>. This is
5857 appropriate only if it is possible to distribute a default
5858 version that will work for most installations, although
5859 some system administrators may choose to modify it. This
5860 implies that the default version will be part of the
5861 package distribution, and must not be modified by the
5862 maintainer scripts during installation (or at any other
5867 In order to ensure that local changes are preserved
5868 correctly, no package may contain or make hard links to
5869 conffiles.<footnote>
5871 Rationale: There are two problems with hard links.
5872 The first is that some editors break the link while
5873 editing one of the files, so that the two files may
5874 unwittingly become unlinked and different. The second
5875 is that <prgn>dpkg</prgn> might break the hard link
5876 while upgrading <tt>conffile</tt>s.
5882 The other way to do it is via the maintainer scripts. In
5883 this case, the configuration file must not be listed as a
5884 <tt>conffile</tt> and must not be part of the package
5885 distribution. If the existence of a file is required for
5886 the package to be sensibly configured it is the
5887 responsibility of the package maintainer to provide
5888 maintainer scripts which correctly create, update and
5889 maintain the file and remove it on purge. (See <ref
5890 id="maintainerscripts"> for more information.) These
5891 scripts must be idempotent (i.e., must work correctly if
5892 <prgn>dpkg</prgn> needs to re-run them due to errors
5893 during installation or removal), must cope with all the
5894 variety of ways <prgn>dpkg</prgn> can call maintainer
5895 scripts, must not overwrite or otherwise mangle the user's
5896 configuration without asking, must not ask unnecessary
5897 questions (particularly during upgrades), and otherwise be
5902 The scripts are not required to configure every possible
5903 option for the package, but only those necessary to get
5904 the package running on a given system. Ideally the
5905 sysadmin should not have to do any configuration other
5906 than that done (semi-)automatically by the
5907 <prgn>postinst</prgn> script.
5911 A common practice is to create a script called
5912 <tt><var>package</var>-configure</tt> and have the
5913 package's <prgn>postinst</prgn> call it if and only if the
5914 configuration file does not already exist. In certain
5915 cases it is useful for there to be an example or template
5916 file which the maintainer scripts use. Such files should
5917 be in <tt>/usr/share/<var>package</var></tt> or
5918 <tt>/usr/lib/<var>package</var></tt> (depending on whether
5919 they are architecture-independent or not). There should
5920 be symbolic links to them from
5921 <tt>/usr/share/doc/<var>package</var>/examples</tt> if
5922 they are examples, and should be perfectly ordinary
5923 <prgn>dpkg</prgn>-handled files (<em>not</em>
5924 configuration files).
5928 These two styles of configuration file handling must
5929 not be mixed, for that way lies madness:
5930 <prgn>dpkg</prgn> will ask about overwriting the file
5931 every time the package is upgraded.
5936 <heading>Sharing configuration files</heading>
5938 Packages which specify the same file as a
5939 <tt>conffile</tt> must be tagged as <em>conflicting</em>
5940 with each other. (This is an instance of the general rule
5941 about not sharing files. Note that neither alternatives
5942 nor diversions are likely to be appropriate in this case;
5943 in particular, <prgn>dpkg</prgn> does not handle diverted
5944 <tt>conffile</tt>s well.)
5948 The maintainer scripts must not alter a <tt>conffile</tt>
5949 of <em>any</em> package, including the one the scripts
5954 If two or more packages use the same configuration file
5955 and it is reasonable for both to be installed at the same
5956 time, one of these packages must be defined as
5957 <em>owner</em> of the configuration file, i.e., it will be
5958 the package which handles that file as a configuration
5959 file. Other packages that use the configuration file must
5960 depend on the owning package if they require the
5961 configuration file to operate. If the other package will
5962 use the configuration file if present, but is capable of
5963 operating without it, no dependency need be declared.</p>
5966 If it is desirable for two or more related packages to
5967 share a configuration file <em>and</em> for all of the
5968 related packages to be able to modify that configuration
5969 file, then the following should be done:
5970 <enumlist compact="compact">
5973 One of the related packages (the "owning" package)
5974 will manage the configuration file with maintainer
5975 scripts as described in the previous section.
5980 The owning package should also provide a program
5981 that the other packages may use to modify the
5987 The related packages must use the provided program
5988 to make any desired modifications to the
5989 configuration file. They should either depend on
5990 the core package to guarantee that the configuration
5991 modifier program is available or accept gracefully
5992 that they cannot modify the configuration file if it
5993 is not. (This is in addition to the fact that the
5994 configuration file may not even be present in the
6002 Sometimes it's appropriate to create a new package which
6003 provides the basic infrastructure for the other packages
6004 and which manages the shared configuration files. (The
6005 <tt>sgml-base</tt> package is a good example.)
6010 <heading>User configuration files ("dotfiles")</heading>
6013 The files in <tt>/etc/skel</tt> will automatically be
6014 copied into new user accounts by <prgn>adduser</prgn>.
6015 No other program should reference the files in
6020 Therefore, if a program needs a dotfile to exist in
6021 advance in <tt>$HOME</tt> to work sensibly, that dotfile
6022 should be installed in <tt>/etc/skel</tt> and treated as a
6027 However, programs that require dotfiles in order to
6028 operate sensibly (dotfiles that they do not create
6029 themselves automatically, that is) are a bad thing.
6030 Furthermore, programs should be configured by the Debian
6031 default installation to behave as closely to the upstream
6032 default behaviour as possible.
6036 Therefore, if a program in a Debian package needs to be
6037 configured in some way in order to operate sensibly, that
6038 should be done using a site-wide configuration file placed
6039 in <tt>/etc</tt>. Only if the program doesn't support a
6040 site-wide default configuration and the package maintainer
6041 doesn't have time to add it may a default per-user file be
6042 placed in <tt>/etc/skel</tt>.
6046 <tt>/etc/skel</tt> should be as empty as we can make it.
6047 This is particularly true because there is no easy (or
6048 necessarily desirable) mechanism for ensuring that the
6049 appropriate dotfiles are copied into the accounts of
6050 existing users when a package is installed.
6056 <heading>Log files</heading>
6058 Log files should usually be named
6059 <tt>/var/log/<var>package</var>.log</tt>. If you have many
6060 log files, or need a separate directory for permission
6061 reasons (<tt>/var/log</tt> is writable only by
6062 <tt>root</tt>), you should usually create a directory named
6063 <tt>/var/log/<var>package</var></tt> and place your log
6068 Log files must be rotated occasionally so that they don't
6069 grow indefinitely; the best way to do this is to drop a log
6070 rotation configuration file into the directory
6071 <tt>/etc/logrotate.d</tt> and use the facilities provided by
6072 logrotate.<footnote>
6074 The traditional approach to log files has been to set up
6075 <em>ad hoc</em> log rotation schemes using simple shell
6076 scripts and cron. While this approach is highly
6077 customizable, it requires quite a lot of sysadmin work.
6078 Even though the original Debian system helped a little
6079 by automatically installing a system which can be used
6080 as a template, this was deemed not enough.
6084 The use of <prgn>logrotate</prgn>, a program developed
6085 by Red Hat, is better, as it centralizes log management.
6086 It has both a configuration file
6087 (<tt>/etc/logrotate.conf</tt>) and a directory where
6088 packages can drop their individual log rotation
6089 configurations (<tt>/etc/logrotate.d</tt>).
6092 Here is a good example for a logrotate config
6093 file (for more information see <manref name="logrotate"
6095 <example compact="compact">
6101 /etc/init.d/foo force-reload
6105 This rotates all files under <tt>/var/log/foo</tt>, saves 12
6106 compressed generations, and forces the daemon to reload its
6107 configuration information after the log rotation.
6111 Log files should be removed when the package is
6112 purged (but not when it is only removed). This should be
6113 done by the <prgn>postrm</prgn> script when it is called
6114 with the argument <tt>purge</tt> (see <ref
6115 id="removedetails">).
6120 <heading>Permissions and owners</heading>
6123 The rules in this section are guidelines for general use.
6124 If necessary you may deviate from the details below.
6125 However, if you do so you must make sure that what is done
6126 is secure and you should try to be as consistent as possible
6127 with the rest of the system. You should probably also
6128 discuss it on <prgn>debian-devel</prgn> first.
6132 Files should be owned by <tt>root.root</tt>, and made
6133 writable only by the owner and universally readable (and
6134 executable, if appropriate), that is mode 644 or 755.
6138 Directories should be mode 755 or (for group-writability)
6139 mode 2775. The ownership of the directory should be
6140 consistent with its mode: if a directory is mode 2775, it
6141 should be owned by the group that needs write access to
6146 Setuid and setgid executables should be mode 4755 or 2755
6147 respectively, and owned by the appropriate user or group.
6148 They should not be made unreadable (modes like 4711 or
6149 2711 or even 4111); doing so achieves no extra security,
6150 because anyone can find the binary in the freely available
6151 Debian package; it is merely inconvenient. For the same
6152 reason you should not restrict read or execute permissions
6153 on non-set-id executables.
6157 Some setuid programs need to be restricted to particular
6158 sets of users, using file permissions. In this case they
6159 should be owned by the uid to which they are set-id, and by
6160 the group which should be allowed to execute them. They
6161 should have mode 4754; again there is no point in making
6162 them unreadable to those users who must not be allowed to
6167 It is possible to arrange that the system administrator can
6168 reconfigure the package to correspond to their local
6169 security policy by changing the permissions on a binary:
6170 they can do this by using <prgn>dpkg-statoverride</prgn>, as
6171 described below.<footnote>
6173 Ordinary files installed by <prgn>dpkg</prgn> (as
6174 opposed to <tt>conffile</tt>s and other similar objects)
6175 normally have their permissions reset to the distributed
6176 permissions when the package is reinstalled. However,
6177 the use of <prgn>dpkg-statoverride</prgn> overrides this
6178 default behaviour. If you use this method, you should
6179 remember to describe <prgn>dpkg-statoverride</prgn> in
6180 the package documentation; being a relatively new
6181 addition to Debian, it is probably not yet well-known.
6184 Another method you should consider is to create a group for
6185 people allowed to use the program(s) and make any setuid
6186 executables executable only by that group.
6190 If you need to create a new user or group for your package
6191 there are two possibilities. Firstly, you may need to
6192 make some files in the binary package be owned by this
6193 user or group, or you may need to compile the user or
6194 group id (rather than just the name) into the binary
6195 (though this latter should be avoided if possible, as in
6196 this case you need a statically allocated id).</p>
6199 If you need a statically allocated id, you must ask for a
6200 user or group id from the <tt>base-passwd</tt> maintainer,
6201 and must not release the package until you have been
6202 allocated one. Once you have been allocated one you must
6203 either make the package depend on a version of the
6204 <tt>base-passwd</tt> package with the id present in
6205 <tt>/etc/passwd</tt> or <tt>/etc/group</tt>, or arrange for
6206 your package to create the user or group itself with the
6207 correct id (using <tt>adduser</tt>) in its
6208 <prgn>preinst</prgn> or <prgn>postinst</prgn>. (Doing it in
6209 the <prgn>postinst</prgn> is to be preferred if it is
6210 possible, otherwise a pre-dependency will be needed on the
6211 <tt>adduser</tt> package.)
6215 On the other hand, the program might be able to determine
6216 the uid or gid from the user or group name at runtime, so
6217 that a dynamically allocated id can be used. In this case
6218 you should choose an appropriate user or group name,
6219 discussing this on <prgn>debian-devel</prgn> and checking
6220 with the base system maintainer that it is unique and that
6221 they do not wish you to use a statically allocated id
6222 instead. When this has been checked you must arrange for
6223 your package to create the user or group if necessary using
6224 <prgn>adduser</prgn> in the <prgn>preinst</prgn> or
6225 <prgn>postinst</prgn> script (again, the latter is to be
6226 preferred if it is possible).
6230 Note that changing the numeric value of an id associated
6231 with a name is very difficult, and involves searching the
6232 file system for all appropriate files. You need to think
6233 carefully whether a static or dynamic id is required, since
6234 changing your mind later will cause problems.
6237 <sect1><heading>The use of <prgn>dpkg-statoverride</prgn></heading>
6239 This section is not intended as policy, but as a
6240 description of the use of <prgn>dpkg-statoverride</prgn>.
6244 <prgn>dpkg-statoverride</prgn> is a replacement for the
6245 deprecated <tt>suidmanager</tt> package. Packages which
6246 previously used <tt>suidmanager</tt> should have a
6247 <tt>Conflicts: suidmanager (<< 0.50)</tt> entry (or even
6248 <tt>(<< 0.52)</tt>), and calls to <tt>suidregister</tt>
6249 and <tt>suidunregister</tt> should now be simply removed
6250 from the maintainer scripts.
6254 If a system administrator wishes to have a file (or
6255 directory or other such thing) installed with owner and
6256 permissions different from those in the distributed Debian
6257 package, he can use the <prgn>dpkg-statoverride</prgn>
6258 program to instruct <prgn>dpkg</prgn> to use the different
6259 settings every time the file is installed. Thus the
6260 package maintainer should distribute the files with their
6261 normal permissions, and leave it for the system
6262 administrator to make any desired changes. For example, a
6263 daemon which is normally required to be setuid root, but
6264 in certain situations could be used without being setuid,
6265 should be installed setuid in the <tt>.deb</tt>. Then the
6266 local system administrator can change this if they wish.
6267 If there are two standard ways of doing it, the package
6268 maintainer can use <tt>debconf</tt> to find out the
6269 preference, and call <prgn>dpkg-statoverride</prgn> in the
6270 maintainer script if necessary to accommodate the system
6271 administrator's choice.
6275 Given the above, <prgn>dpkg-statoverride</prgn> is
6276 essentially a tool for system administrators and would not
6277 normally be needed in the maintainer scripts. There is
6278 one type of situation, though, where calls to
6279 <prgn>dpkg-statoverride</prgn> would be needed in the
6280 maintainer scripts, and that involves packages which use
6281 dynamically allocated user or group ids. In such a
6282 situation, something like the following idiom can be very
6283 helpful in the package's <prgn>postinst</prgn>, where
6284 <tt>sysuser</tt> is a dynamically allocated id:
6286 for i in /usr/bin/foo /usr/sbin/bar
6288 if ! dpkg-statoverride --list $i >/dev/null
6290 dpkg-statoverride --update --add sysuser root 4755 $i
6294 The corresponding <tt>dpkg-statoverride --remove</tt>
6295 calls can then be made unconditionally when the package is
6302 <chapt id="customized-programs">
6303 <heading>Customized programs</heading>
6305 <sect id="arch-spec">
6306 <heading>Architecture specification strings</heading>
6309 If a program needs to specify an <em>architecture specification
6310 string</em> in some place, the following format should be
6311 used: <var>arch</var>-<var>os</var><footnote>
6313 The following architectures and operating systems are
6314 currently recognised by <prgn>dpkg-archictecture</prgn>.
6315 The architecture, <tt><var>arch</var></tt>, is one of
6316 the following: <tt>alpha</tt>, <tt>arm</tt>,
6317 <tt>hppa</tt>, <tt>i386</tt>, <tt>ia64</tt>,
6318 <tt>m68k</tt>, <tt>mips</tt>, <tt>mipsel</tt>,
6319 <tt>powerpc</tt>, <tt>s390</tt>, <tt>sh</tt>,
6320 <tt>sheb</tt>, <tt>sparc</tt> and <tt>sparc64</tt>. The
6321 operating system, <tt><var>os</var></tt>, is one of:
6322 <tt>linux</tt>, <tt>gnu</tt>, <tt>freebsd</tt> and
6323 <tt>openbsd</tt>. Use of <tt>gnu</tt> in this string is
6324 reserved for the GNU/Hurd operating system.
6330 Note that we don't want to use
6331 <tt><var>arch</var>-debian-linux</tt> to apply to the rule
6332 <tt><var>architecture</var>-<var>vendor</var>-<var>os</var></tt>
6333 since this would make our programs incompatible with other
6334 Linux distributions. We also don't use something like
6335 <tt><var>arch</var>-unknown-linux</tt>, since the
6336 <tt>unknown</tt> does not look very good.
6341 <heading>Daemons</heading>
6344 The configuration files <tt>/etc/services</tt>,
6345 <tt>/etc/protocols</tt>, and <tt>/etc/rpc</tt> are managed
6346 by the <prgn>netbase</prgn> package and must not be modified
6351 If a package requires a new entry in one of these files, the
6352 maintainer should get in contact with the
6353 <prgn>netbase</prgn> maintainer, who will add the entries
6354 and release a new version of the <prgn>netbase</prgn>
6359 The configuration file <tt>/etc/inetd.conf</tt> must not be
6360 modified by the package's scripts except via the
6361 <prgn>update-inetd</prgn> script or the
6362 <tt>DebianNet.pm</tt> Perl module. See their documentation
6363 for details on how to add entries.
6367 If a package wants to install an example entry into
6368 <tt>/etc/inetd.conf</tt>, the entry must be preceded with
6369 exactly one hash character (<tt>#</tt>). Such lines are
6370 treated as `commented out by user' by the
6371 <prgn>update-inetd</prgn> script and are not changed or
6372 activated during package updates.
6377 <heading>Using pseudo-ttys and modifying wtmp, utmp and
6381 Some programs need to create pseudo-ttys. This should be done
6382 using Unix98 ptys if the C library supports it. The resulting
6383 program must not be installed setuid root, unless that
6384 is required for other functionality.
6388 The files <tt>/var/run/utmp</tt>, <tt>/var/log/wtmp</tt> and
6389 <tt>/var/log/lastlog</tt> must be installed writeable by
6390 group <tt>utmp</tt>. Programs which need to modify those
6391 files must be installed setgid <tt>utmp</tt>.
6396 <heading>Editors and pagers</heading>
6399 Some programs have the ability to launch an editor or pager
6400 program to edit or display a text document. Since there are
6401 lots of different editors and pagers available in the Debian
6402 distribution, the system administrator and each user should
6403 have the possibility to choose his/her preferred editor and
6408 In addition, every program should choose a good default
6409 editor/pager if none is selected by the user or system
6414 Thus, every program that launches an editor or pager must
6415 use the EDITOR or PAGER environment variable to determine
6416 the editor or pager the user wishes to use. If these
6417 variables are not set, the programs <tt>/usr/bin/editor</tt>
6418 and <tt>/usr/bin/pager</tt> should be used, respectively.
6422 These two files are managed through the <prgn>dpkg</prgn>
6423 `alternatives' mechanism. Thus every package providing an
6424 editor or pager must call the
6425 <prgn>update-alternatives</prgn> script to register these
6430 If it is very hard to adapt a program to make use of the
6431 EDITOR or PAGER variables, that program may be configured to
6432 use <tt>/usr/bin/sensible-editor</tt> and
6433 <tt>/usr/bin/sensible-pager</tt> as the editor or pager
6434 program respectively. These are two scripts provided in the
6435 Debian base system that check the EDITOR and PAGER variables
6436 and launch the appropriate program, and fall back to
6437 <tt>/usr/bin/editor</tt> and <tt>/usr/bin/pager</tt> if the
6438 variable is not set.
6442 A program may also use the VISUAL environment variable to
6443 determine the user's choice of editor. If it exists, it
6444 should take precedence over EDITOR. This is in fact what
6445 <tt>/usr/bin/sensible-editor</tt> does.
6449 It is not required for a package to depend on
6450 <tt>editor</tt> and <tt>pager</tt>, nor is it required for a
6451 package to provide such virtual packages.<footnote>
6453 The Debian base system already provides an editor and a
6460 <sect id="web-appl">
6461 <heading>Web servers and applications</heading>
6464 This section describes the locations and URLs that should
6465 be used by all web servers and web applications in the
6473 Cgi-bin executable files are installed in the
6475 <example compact="compact">
6476 /usr/lib/cgi-bin/<var>cgi-bin-name</var>
6478 and should be referred to as
6479 <example compact="compact">
6480 http://localhost/cgi-bin/<var>cgi-bin-name</var>
6485 <item><p>Access to HTML documents</p>
6488 HTML documents for a package are stored in
6489 <tt>/usr/share/doc/<var>package</var></tt>
6490 and can be referred to as
6491 <example compact="compact">
6492 http://localhost/doc/<var>package</var>/<var>filename</var>
6496 The web server should restrict access to the document
6497 tree so that only clients on the same host can read
6498 the documents. If the web server does not support such
6499 access controls, then it should not provide access at
6500 all, or ask about providing access during installation.
6504 <item><p>Web Document Root</p>
6507 Web Applications should try to avoid storing files in
6508 the Web Document Root. Instead they should use the
6509 /usr/share/doc/<var>package</var> directory for
6510 documents and register the Web Application via the
6511 menu package. If access to the web document root is
6512 unavoidable then use
6513 <example compact="compact">
6516 as the Document Root. This might be just a symbolic
6517 link to the location where the system administrator
6518 has put the real document root.
6522 </enumlist></p></sect>
6525 <sect id="mail-transport-agents">
6526 <heading>Mail transport, delivery and user agents</heading>
6529 Debian packages which process electronic mail, whether mail
6530 user agents (MUAs) or mail transport agents (MTAs), must
6531 ensure that they are compatible with the configuration
6532 decisions below. Failure to do this may result in lost
6533 mail, broken <tt>From:</tt> lines, and other serious brain
6538 The mail spool is <tt>/var/mail</tt> and the interface to
6539 send a mail message is <tt>/usr/sbin/sendmail</tt> (as per
6540 the FHS). On older systems, the mail spool may be
6541 physically located in <tt>/var/spool/mail</tt>, but all
6542 access to the mail spool should be via the
6543 <tt>/var/mail</tt> symlink. The mail spool is part of the
6544 base system and not part of the MTA package.
6548 All Debian MUAs, MTAs, MDAs and other mailbox accessing
6549 programs (such as IMAP daemons) must lock the mailbox in an
6550 NFS-safe way. This means that <tt>fcntl()</tt> locking must
6551 be combined with dot locking. To avoid deadlocks, a program
6552 should use <tt>fcntl()</tt> first and dot locking after
6553 this, or alternatively implement the two locking methods in
6554 a non blocking way<footnote>
6556 If it is not possible to establish both locks, the
6557 system shouldn't wait for the second lock to be
6558 established, but remove the first lock, wait a (random)
6559 time, and start over locking again.
6561 </footnote>. Using the functions <tt>maillock</tt> and
6562 <tt>mailunlock</tt> provided by the
6563 <tt>liblockfile*</tt><footnote>
6565 You will need to depend on <tt>liblockfile1
6566 (>>1.01)</tt> to use these functions.
6568 </footnote> packages is the recommended way to realize this.
6572 Mailboxes are generally mode 660
6573 <tt><var>user</var>.mail</tt> unless the system
6574 administrator has chosen otherwise. A MUA may remove a
6575 mailbox (unless it has nonstandard permissions) in which
6576 case the MTA or another MUA must recreate it if needed.
6577 Mailboxes must be writable by group mail.
6581 The mail spool is 2775 <tt>root.mail</tt>, and MUAs should
6582 be setgid mail to do the locking mentioned above (and
6583 must obviously avoid accessing other users' mailboxes
6584 using this privilege).</p>
6587 <tt>/etc/aliases</tt> is the source file for the system mail
6588 aliases (e.g., postmaster, usenet, etc.), it is the one
6589 which the sysadmin and <prgn>postinst</prgn> scripts may
6590 edit. After <tt>/etc/aliases</tt> is edited the program or
6591 human editing it must call <prgn>newaliases</prgn>. All MTA
6592 packages must come with a <prgn>newaliases</prgn> program,
6593 even if it does nothing, but older MTA packages did not do
6594 this so programs should not fail if <prgn>newaliases</prgn>
6595 cannot be found. Note that because of this, all MTA
6596 packages must have <tt>Provides</tt>, <tt>Conflicts</tt> and
6597 <tt>Replaces: mail-transport-agent</tt> control file
6602 The convention of writing <tt>forward to
6603 <var>address</var></tt> in the mailbox itself is not
6604 supported. Use a <tt>.forward</tt> file instead.</p>
6607 The <prgn>rmail</prgn> program used by UUCP
6608 for incoming mail should be <tt>/usr/sbin/rmail</tt>.
6609 Likewise, <prgn>rsmtp</prgn>, for receiving
6610 batch-SMTP-over-UUCP, should be <tt>/usr/sbin/rsmtp</tt> if it
6614 If your package needs to know what hostname to use on (for
6615 example) outgoing news and mail messages which are generated
6616 locally, you should use the file <tt>/etc/mailname</tt>. It
6617 will contain the portion after the username and <tt>@</tt>
6618 (at) sign for email addresses of users on the machine
6619 (followed by a newline).
6623 Such package should check for the existence of this file
6624 when it is being configured. If it exists, it should be
6625 used without comment, although an MTA's configuration script
6626 may wish to prompt the user even if it finds that this file
6627 exists. If the file does not exist, the package should
6628 prompt the user for the value (preferably using
6629 <prgn>debconf</prgn>) and store it in <tt>/etc/mailname</tt>
6630 as well as using it in the package's configuration. The
6631 prompt should make it clear that the name will not just be
6632 used by that package. For example, in this situation the
6633 <tt>inn</tt> package could say something like:
6634 <example compact="compact">
6635 Please enter the `mail name' of your system. This is the
6636 hostname portion of the address to be shown on outgoing
6637 news and mail messages. The default is
6638 <var>syshostname</var>, your system's host name. Mail
6639 name [`<var>syshostname</var>']:
6641 where <var>syshostname</var> is the output of <tt>hostname
6647 <heading>News system configuration</heading>
6650 All the configuration files related to the NNTP (news)
6651 servers and clients should be located under
6652 <tt>/etc/news</tt>.</p>
6655 There are some configuration issues that apply to a number
6656 of news clients and server packages on the machine. These
6660 <tag><tt>/etc/news/organization</tt></tag>
6661 <item><p>A string which should appear as the
6662 organization header for all messages posted
6663 by NNTP clients on the machine</p></item>
6665 <tag><tt>/etc/news/server</tt></tag>
6666 <item><p>Contains the FQDN of the upstream NNTP
6667 server, or localhost if the local machine is
6668 an NNTP server.</p></item>
6671 Other global files may be added as required for cross-package news
6672 configuration.</p></sect>
6676 <heading>Programs for the X Window System</heading>
6679 <heading>Providing X support and package priorities</heading>
6682 Programs that can be configured with support for the X
6683 Window System must be configured to do so and must declare
6684 any package dependencies necessary to satisfy their
6685 runtime requirements when using the X Window System. If
6686 such a package is of higher priority than the X packages
6687 on which it depends, it is required that either the
6688 X-specific components be split into a separate package, or
6689 that an alternative version of the package, which includes
6690 X support, be provided, or that the package's priority be
6696 <heading>Packages providing an X server</heading>
6699 Packages that provide an X server that, directly or
6700 indirectly, communicates with real input and display
6701 hardware should declare in their control data that they
6702 provide the virtual package <tt>xserver</tt>.<footnote>
6704 This implements current practice, and provides an
6705 actual policy for usage of the <tt>xserver</tt>
6706 virtual package which appears in the virtual packages
6707 list. In a nutshell, X servers that interface
6708 directly with the display and input hardware or via
6709 another subsystem (e.g., GGI) should provide
6710 <tt>xserver</tt>. Things like <tt>Xvfb</tt>,
6711 <tt>Xnest</tt>, and <tt>Xprt</tt> should not.
6718 <heading>Packages providing a terminal emulator</heading>
6721 Packages that provide a terminal emulator for the X Window
6722 System which meet the criteria listed below should declare
6723 in their control data that they provide the virtual
6724 package <tt>x-terminal-emulator</tt>. They should also
6725 register themselves as an alternative for
6726 <tt>/usr/bin/x-terminal-emulator</tt>, with a priority of
6731 To be an <tt>x-terminal-emulator</tt>, a program must:
6732 <list compact="compact">
6734 Be able to emulate a DEC VT100 terminal, or a
6735 compatible terminal.
6739 Support the command-line option <tt>-e
6740 <var>command</var></tt>, which creates a new
6741 terminal window<footnote>
6743 "New terminal window" does not necessarily mean
6744 a new top-level X window directly parented by
6745 the window manager; it could, if the terminal
6746 emulator application were so coded, be a new
6747 "view" in a multiple-document interface (MDI).
6750 and runs the specified <var>command</var>.
6754 Support the command-line option <tt>-T
6755 <var>title</var></tt>, which creates a new terminal
6756 window with the window title <var>title</var>.
6763 <heading>Packages providing a window manager</heading>
6766 Packages that provide a window manager should declare in
6767 their control data that they provide the virtual package
6768 <tt>x-window-manager</tt>. They should also register
6769 themselves as an alternative for
6770 <tt>/usr/bin/x-window-manager</tt>, with a priority
6771 calculated as follows:
6772 <list compact="compact">
6773 <item><p>Start with a priority of 20.</p></item>
6777 If the window manager supports the Debian menu
6778 system, add 20 points if this support is available
6779 in the package's default configuration (i.e., no
6780 configuration files belonging to the system or user
6781 have to be edited to activate the feature); if
6782 configuration files must be modified, add only 10
6789 If the window manager permits the X session to be
6790 restarted using a <em>different</em> window manager
6791 (without killing the X server) in its default
6792 configuration, add 10 points; otherwise add none.
6800 <heading>Packages providing fonts</heading>
6803 Packages that provide fonts for the X Window
6806 For the purposes of Debian Policy, a "font for the X
6807 Window System" is one which is accessed via X protocol
6808 requests. Fonts for the Linux console, for PostScript
6809 renderers, or any other purpose, do not fit this
6810 definition. Any tool which makes such fonts available
6811 to the X Window System, however, must abide by this
6815 must do a number of things to ensure that they are both
6816 available without modification of the X or font server
6817 configuration, and that they do not corrupt files used by
6818 other font packages to register information about
6823 Fonts of any type supported by the X Window System
6824 must be be in a separate binary package from any
6825 executables, libraries, or documentation (except
6826 that specific to the fonts shipped, such as their
6827 license information). If one or more of the fonts
6828 so packaged are necessary for proper operation of
6829 the package with which they are associated the font
6830 package may be Recommended; if the fonts merely
6831 provide an enhancement, a Suggests relationship may
6832 be used. Packages must not Depend on font
6835 This is because the X server may retrieve fonts
6836 from the local filesystem or over the network
6837 from an X font server; the Debian package system
6838 is empowered to deal only with the local
6847 BDF fonts must be converted to PCF fonts with the
6848 <prgn>bdftopcf</prgn> utility (available in the
6849 <tt>xutils</tt> package, <tt>gzip</tt>ped, and
6850 placed in a directory that corresponds to their
6852 <list compact="compact">
6854 100 dpi fonts must be placed in
6855 <tt>/usr/X11R6/lib/X11/fonts/100dpi/</tt>.
6859 75 dpi fonts must be placed in
6860 <tt>/usr/X11R6/lib/X11/fonts/75dpi/</tt>.
6864 Character-cell fonts, cursor fonts, and other
6865 low-resolution fonts must be placed in
6866 <tt>/usr/X11R6/lib/X11/fonts/misc/</tt>.
6873 Speedo fonts must be placed in
6874 <tt>/usr/X11R6/lib/X11/fonts/Speedo/</tt>.
6878 Type 1 fonts must be placed in
6879 <tt>/usr/X11R6/lib/X11/fonts/Type1/</tt>. If font
6880 metric files are available, they must be placed here
6886 Subdirectories of <tt>/usr/X11R6/lib/X11/fonts/</tt>
6887 other than those listed above must be neither
6888 created nor used. (The <tt>PEX</tt>, <tt>CID</tt>,
6889 and <tt>cyrillic</tt> directories are excepted for
6890 historical reasons, but installation of files into
6891 these directories remains discouraged.)
6897 Font packages may, instead of placing files directly
6898 in the X font directories listed above, provide
6899 symbolic links in the font directory which point to
6900 the files' actual location in the filesystem. Such
6901 a location must comply with the FHS.
6907 Font packages should not contain both 75dpi and
6908 100dpi versions of a font. If both are available,
6909 they should be provided in separate binary packages
6910 with <tt>-75dpi</tt> or <tt>-100dpi</tt> appended to
6911 the names of the packages containing the
6912 corresponding fonts.
6918 Fonts destined for the <tt>misc</tt> subdirectory
6919 should not be included in the same package as 75dpi
6920 or 100dpi fonts; instead, they should be provided in
6921 a separate package with <tt>-misc</tt> appended to
6928 Font packages must not provide the files
6929 <tt>fonts.dir</tt>, <tt>fonts.alias</tt>, or
6930 <tt>fonts.scale</tt> in a font directory:
6933 <tt>fonts.dir</tt> files must not be provided at all.
6938 <tt>fonts.alias</tt> and <tt>fonts.scale</tt>
6939 files, if needed, should be provided in the
6941 <tt>/etc/X11/fonts/<var>fontdir</var>/<var>package</var>.<var>extension</var></tt>,
6942 where <var>fontdir</var> is the name of the
6944 <tt>/usr/X11R6/lib/X11/fonts/</tt> where the
6945 package's corresponding fonts are stored
6946 (e.g., <tt>75dpi</tt> or <tt>misc</tt>),
6947 <var>package</var> is the name of the package
6948 that provides these fonts, and
6949 <var>extension</var> is either <tt>scale</tt>
6950 or <tt>alias</tt>, whichever corresponds to
6960 Font packages must declare a dependency on
6961 <tt>xutils (>> 4.0.3)</tt> in their control
6968 Font packages that provide one or more
6969 <tt>fonts.scale</tt> files as described above must
6970 invoke <prgn>update-fonts-scale</prgn> on each
6971 directory into which they installed fonts
6972 <em>before</em> invoking
6973 <prgn>update-fonts-dir</prgn> on that directory.
6974 This invocation must occur in both the
6975 <prgn>postinst</prgn> (for all arguments) and
6976 <prgn>postrm</prgn> (for all arguments except
6977 <tt>upgrade</tt>) scripts.
6983 Font packages that provide one or more
6984 <tt>fonts.alias</tt> files as described above must
6985 invoke <prgn>update-fonts-alias</prgn> on each
6986 directory into which they installed fonts. This
6987 invocation must occur in both the
6988 <prgn>postinst</prgn> (for all arguments) and
6989 <prgn>postrm</prgn> (for all arguments except
6990 <tt>upgrade</tt>) scripts.
6996 Font packages must invoke
6997 <prgn>update-fonts-dir</prgn> on each directory into
6998 which they installed fonts. This invocation must
6999 occur in both the <prgn>postinst</prgn> (for all
7000 arguments) and <prgn>postrm</prgn> (for all
7001 arguments except <tt>upgrade</tt>) scripts.
7007 Font packages must not provide alias names for the
7008 fonts they include which collide with alias names
7009 already in use by fonts already packaged.
7015 Font packages must not provide fonts with the same
7016 XLFD registry name as another font already packaged.
7024 <heading>Application defaults files</heading>
7027 Application defaults files must be installed in the
7028 directory <tt>/etc/X11/app-defaults/</tt> (use of a
7029 localized subdirectory of <tt>/etc/X11/</tt> as described
7030 in the <em>X Toolkit Intrinsics - C Language
7031 Interface</em> manual is also permitted). They must be
7032 registered as <tt>conffile</tt>s or handled as
7033 configuration files. Packages must not provide the
7034 directory <tt>/usr/X11R6/lib/X11/app-defaults/</tt>.
7038 Customization of programs' X resources may also be
7039 supported with the provision of a file with the same name
7040 as that of the package placed in the
7041 <tt>/etc/X11/Xresources/</tt> directory, which must
7042 registered as a <tt>conffile</tt> or handled as a
7043 configuration file.<footnote>
7045 Note that this mechanism is not the same as using
7046 app-defaults; app-defaults are tied to the client
7047 binary on the local filesystem, whereas X resources
7048 are stored in the X server and affect all connecting
7052 <em>Important:</em> packages that install files into the
7053 <tt>/etc/X11/Xresources/</tt> directory must conflict with
7054 <tt>xbase (<< 3.3.2.3a-2)</tt>; if this is not done
7055 it is possible for the installing package to destroy a
7056 previously-existing <tt>/etc/X11/Xresources</tt> file
7057 which had been customized by the system administrator.
7062 <heading>Installation directory issues</heading>
7065 Packages using the X Window System should not be
7066 configured to install files under the <tt>/usr/X11R6/</tt>
7067 directory unless they use <prgn>imake</prgn>. The
7068 <tt>/usr/X11R6/</tt> directory hierarchy should be
7069 regarded as deprecated for all packages except the X
7070 Window System itself, and those which use the
7071 <prgn>imake</prgn> program it provides, in which case the
7072 packages may transition out of the <tt>/usr/X11R6/</tt>
7073 directory at the maintainer's discretion.<footnote>
7075 <prgn>Imake</prgn>-using programs are exempt because,
7076 as long as they are written correctly, the pathnames
7077 they use to locate resources and install themselves
7078 are derived wholly from the X Window System
7079 configuration. Thus, in the event that the X Window
7080 System moves to <tt>/usr/X11R7/</tt>,
7081 <tt>/usr/X12/</tt>, or just plain <tt>/usr/</tt>, all
7082 that is required for these programs is a recompile
7083 against the corresponding X Window System library
7084 development packages.
7087 Programs that use GNU <prgn>autoconf</prgn> and
7088 <prgn>automake</prgn> are usually easily configured at
7089 compile time to use <tt>/usr/</tt> instead of
7090 <tt>/usr/X11R6/</tt>, and this should be done whenever
7091 possible. Configuration files for window managers and
7092 display managers should be placed in a subdirectory of
7093 <tt>/etc/X11/</tt> corresponding to the package name due
7094 to these programs' tight integration with the mechanisms
7095 of the X Window System. Application-level programs should
7096 use the <tt>/etc/</tt> directory unless otherwise mandated
7097 by policy. The installation of files into subdirectories
7098 of <tt>/usr/X11R6/include/X11/</tt> and
7099 <tt>/usr/X11R6/lib/X11/</tt> is permitted but discouraged;
7100 package maintainers should determine if subdirectories of
7101 <tt>/usr/lib/</tt> and <tt>/usr/share/</tt> can be used
7102 instead. (The use of symbolic links from the
7103 <tt>X11R6</tt> directories to other FHS-compliant
7104 locations is encouraged if the program is not easily
7105 configured to look elsewhere for its files.) Packages
7106 must not provide or install files into the directories
7107 <tt>/usr/bin/X11/</tt>, <tt>/usr/include/X11/</tt> or
7108 <tt>/usr/lib/X11/</tt>. Files within a package should,
7109 however, make reference to these directories, rather than
7110 their <tt>X11R6</tt>-named counterparts
7111 <tt>/usr/X11R6/bin/</tt>, <tt>/usr/X11R6/include/X11/</tt>
7112 and <tt>/usr/X11R6/lib/X11/</tt>, if the resources being
7113 referred to have not been moved to other FHS-compliant
7119 <heading>The OSF/Motif and OpenMotif libraries</heading>
7122 <em>Programs that require the non-DFSG-compliant OSF/Motif or
7123 OpenMotif libraries</em><footnote>
7125 OSF/Motif and OpenMotif are collectively referred to as
7126 "Motif" in this policy document.
7129 should be compiled against and tested with LessTif (a free
7130 re-implementation of Motif) instead. If the maintainer
7131 judges that the program or programs do not work
7132 sufficiently well with LessTif to be distributed and
7133 supported, but do so when compiled against Motif, then two
7134 versions of the package should be created; one linked
7135 statically against Motif and with <tt>-smotif</tt>
7136 appended to the package name, and one linked dynamically
7137 against Motif and with <tt>-dmotif</tt> appended to the
7138 package name. Both Motif-linked versions are dependent
7139 upon non-DFSG-compliant software and thus cannot be
7140 uploaded to the <em>main</em> distribution; if the
7141 software is itself DFSG-compliant it may be uploaded to
7142 the <em>contrib</em> distribution. While known existing
7143 versions of Motif permit unlimited redistribution of
7144 binaries linked against the library (whether statically or
7145 dynamically), it is the package maintainer's
7146 responsibility to determine whether this is permitted by
7147 the license of the copy of Motif in his or her possession.
7153 <heading>Perl programs and modules</heading>
7155 Perl programs and modules should follow the current Perl
7156 policy as defined in the file found on
7157 <ftpsite>ftp.debian.org</ftpsite> in
7158 <ftppath>/debian/doc/package-developer/perl-policy.txt.gz</ftppath>
7159 or your local mirror. In addition, it is included in the
7160 <tt>debian-policy</tt> package.
7165 <heading>Emacs lisp programs</heading>
7168 Please refer to the `Debian Emacs Policy' (documented in
7169 <tt>debian-emacs-policy.gz</tt> of the
7170 <prgn>emacsen-common</prgn> package) for details of how to
7171 package emacs lisp programs.
7176 <heading>Games</heading>
7179 The permissions on <tt>/var/games</tt> are mode 755, owner
7180 <tt>root</tt> and group <tt>root</tt>.
7184 Each game decides on its own security policy.</p>
7187 Games which require protected, privileged access to
7188 high-score files, savegames, etc., may be made
7189 set-<em>group</em>-id (mode 2755) and owned by
7190 <tt>root.games</tt>, and use files and directories with
7191 appropriate permissions (770 <tt>root.games</tt>, for
7192 example). They must not be made
7193 set-<em>user</em>-id, as this causes security problems. (If
7194 an attacker can subvert any set-user-id game they can
7195 overwrite the executable of any other, causing other players
7196 of these games to run a Trojan horse program. With a
7197 set-group-id game the attacker only gets access to less
7198 important game data, and if they can get at the other
7199 players' accounts at all it will take considerably more
7203 Some packages, for example some fortune cookie programs, are
7204 configured by the upstream authors to install with their
7205 data files or other static information made unreadable so
7206 that they can only be accessed through set-id programs
7207 provided. You should not do this in a Debian package: anyone can
7208 download the <tt>.deb</tt> file and read the data from it,
7209 so there is no point making the files unreadable. Not
7210 making the files unreadable also means that you don't have
7211 to make so many programs set-id, which reduces the risk of a
7215 As described in the FHS, binaries of games should be
7216 installed in the directory <tt>/usr/games</tt>. This also
7217 applies to games that use the X Window System. Manual pages
7218 for games (X and non-X games) should be installed in
7219 <tt>/usr/share/man/man6</tt>.</p>
7223 <chapt id="docs"><heading>Documentation</heading>
7227 <heading>Manual pages</heading>
7230 You should install manual pages in <prgn>nroff</prgn> source
7231 form, in appropriate places under <tt>/usr/share/man</tt>. You
7232 should only use sections 1 to 9 (see the FHS for more
7233 details). You must not install a preformatted `cat
7237 Each program, utility, and function should have an
7238 associated manpage included in the same package. It is
7239 suggested that all configuration files also have a manual
7240 page included as well.
7244 If no manual page is available for a particular program,
7245 utility, function or configuration file and this is reported
7246 as a bug to the Debian Bug Tracking System, a symbolic link
7247 from the requested manual page to the <manref
7248 name="undocumented" section="7"> manual page may be
7249 provided. This symbolic link can be created from
7250 <tt>debian/rules</tt> like this:
7251 <example compact="compact">
7252 ln -s ../man7/undocumented.7.gz \
7253 debian/tmp/usr/share/man/man[1-9]/<var>requested_manpage</var>.[1-9].gz
7255 This manpage claims that the lack of a manpage has been
7256 reported as a bug, so you may only do this if it really has
7257 (you can report it yourself, if you like). Do not close the
7258 bug report until a proper manpage is available.</p>
7261 You may forward a complaint about a missing manpage to the
7262 upstream authors, and mark the bug as forwarded in the
7263 Debian bug tracking system. Even though the GNU Project do
7264 not in general consider the lack of a manpage to be a bug,
7265 we do; if they tell you that they don't consider it a bug
7266 you should leave the bug in our bug tracking system open
7270 Manual pages should be installed compressed using <tt>gzip
7274 If one manpage needs to be accessible via several names it
7275 is better to use a symbolic link than the <tt>.so</tt>
7276 feature, but there is no need to fiddle with the relevant
7277 parts of the upstream source to change from <tt>.so</tt> to
7278 symlinks: don't do it unless it's easy. You should not
7279 create hard links in the manual page directories, nor put
7280 absolute filenames in <tt>.so</tt> directives. The filename
7281 in a <tt>.so</tt> in a manpage should be relative to the
7282 base of the manpage tree (usually
7283 <tt>/usr/share/man</tt>). If you do not create any links
7284 (whether symlinks, hard links, or <tt>.so</tt> directives)
7285 in the filesystem to the alternate names of the manpage,
7286 then you should not rely on <prgn>man</prgn> finding your
7287 manpage under those names based solely on the information in
7288 the manpage's header.<footnote>
7290 Supporting this in <prgn>man</prgn> often requires
7291 unreasonable processing time to find a manual page or to
7292 report that none exists, and moves knowledge into man's
7293 database that would be better left in the filesystem.
7294 This support is therefore deprecated and will cease to
7295 be present in the future.
7302 <heading>Info documents</heading>
7305 Info documents should be installed in <tt>/usr/share/info</tt>.
7306 They should be compressed with <tt>gzip -9</tt>.</p>
7309 Your package should call <prgn>install-info</prgn> to update
7310 the Info <tt>dir</tt> file in its <prgn>postinst</prgn>
7311 script when called with a <tt>configure</tt> argument, for
7313 <example compact="compact">
7314 install-info --quiet --section Development Development \
7315 /usr/share/info/foobar.info
7319 It is a good idea to specify a section for the location of
7320 your program; this is done with the <tt>--section</tt>
7321 switch. To determine which section to use, you should look
7322 at <tt>/usr/share/info/dir</tt> on your system and choose the most
7323 relevant (or create a new section if none of the current
7324 sections are relevant). Note that the <tt>--section</tt>
7325 flag takes two arguments; the first is a regular expression
7326 to match (case-insensitively) against an existing section,
7327 the second is used when creating a new one.</p>
7330 You should remove the entries in the <prgn>prerm</prgn>
7331 script when called with a <tt>remove</tt> argument:
7332 <example compact="compact">
7333 install-info --quiet --remove /usr/share/info/foobar.info
7337 If <prgn>install-info</prgn> cannot find a description entry
7338 in the Info file you must supply one. See <manref
7339 name="install-info" section="8"> for details.</p>
7343 <heading>Additional documentation</heading>
7346 Any additional documentation that comes with the package may
7347 be installed at the discretion of the package maintainer.
7348 Text documentation should be installed in the directory
7349 <tt>/usr/share/doc/<var>package</var></tt>, where
7350 <var>package</var> is the name of the package, and
7351 compressed with <tt>gzip -9</tt> unless it is small.</p>
7354 If a package comes with large amounts of documentation which
7355 many users of the package will not require you should create
7356 a separate binary package to contain it, so that it does not
7357 take up disk space on the machines of users who do not need
7358 or want it installed.</p>
7361 It is often a good idea to put text information files
7362 (<tt>README</tt>s, changelogs, and so forth) that come with
7363 the source package in <tt>/usr/share/doc/<var>package</var></tt>
7364 in the binary package. However, you don't need to install
7365 the instructions for building and installing the package, of
7369 Files in <tt>/usr/share/doc</tt> should not be referenced by
7370 any program, and the system administrator should be able to
7371 delete them without causing any programs to break. Any files
7372 that are referenced by programs but are also useful as
7373 standalone documentation should be installed under
7374 <tt>/usr/share/<var>package</var>/</tt> with symbolic links
7375 from <tt>/usr/share/doc/<var>package</var>/</tt>.
7381 <heading>Accessing the documentation</heading>
7384 Former Debian releases placed all additional documentation
7385 in <tt>/usr/doc/<var>package</var></tt>. To realize a
7387 <tt>/usr/share/doc/<var>package</var></tt>, each package
7388 must maintain a symlink <tt>/usr/doc/<var>package</var></tt>
7389 that points to the new location of its documentation in
7390 <tt>/usr/share/doc/<var>package</var></tt><footnote>These
7391 symlinks will be removed in the future, but they have to be
7392 there for compatibility reasons until all packages have
7393 moved and the policy is changed accordingly.</footnote>.
7394 The symlink must be created when the package is installed;
7395 it cannot be contained in the package itself due to problems
7396 with <prgn>dpkg</prgn>. One reasonable way to accomplish
7397 this is to put the following in the package's
7398 <prgn>postinst</prgn><footnote>
7400 The <tt>debhelper</tt> script
7401 <prgn>dh_installdocs</prgn> does this automatically.
7404 <example compact="compact">
7405 if [ "$1" = "configure" ]; then
7406 if [ -d /usr/doc -a ! -e /usr/doc/<var>package</var> \
7407 -a -d /usr/share/doc/<var>package</var> ]; then
7408 ln -sf ../share/doc/<var>package</var> /usr/doc/<var>package</var>
7412 and the following in the package's <prgn>prerm</prgn>:
7413 <example compact="compact">
7414 if [ \( "$1" = "upgrade" -o "$1" = "remove" \) \
7415 -a -L /usr/doc/<var>package</var> ]; then
7416 rm -f /usr/doc/<var>package</var>
7423 <heading>Preferred documentation formats</heading>
7426 The unification of Debian documentation is being carried out
7430 If your package comes with extensive documentation in a
7431 markup format that can be converted to various other formats
7432 you should if possible ship HTML versions in a binary
7433 package, in the directory
7434 <tt>/usr/share/doc/<var>appropriate-package</var></tt> or
7435 its subdirectories.<footnote>
7437 The rationale: The important thing here is that HTML
7438 docs should be available in <em>some</em> package, not
7439 necessarily in the main binary package.
7445 Other formats such as PostScript may be provided at the
7446 package maintainer's discretion.
7450 <sect id="copyrightfile">
7451 <heading>Copyright information</heading>
7454 Every package must be accompanied by a verbatim copy of its
7455 copyright and distribution license in the file
7456 <tt>/usr/share/doc/<var>package</var>/copyright</tt>. This
7457 file must neither be compressed nor be a symbolic link.
7461 In addition, the copyright file must say where the upstream
7462 sources (if any) were obtained, and should explain briefly what
7463 modifications were made in the Debian version of the package
7464 compared to the upstream one. It should name the original
7465 authors of the package and the Debian maintainer(s) who were
7466 involved with its creation.</p>
7469 A copy of the file which will be installed in
7470 <tt>/usr/share/doc/<var>package</var>/copyright</tt> should
7471 be in <tt>debian/copyright</tt> in the source package.
7475 <tt>/usr/share/doc/<var>package</var></tt> may be a symbolic
7476 link to another directory in <tt>/usr/share/doc</tt> only if
7477 the two packages both come from the same source and the
7478 first package Depends on the second. These rules are
7479 important because copyrights must be extractable by
7484 Packages distributed under the UCB BSD license, the Artistic
7485 license, the GNU GPL, and the GNU LGPL should refer to the
7486 files <tt>/usr/share/common-licenses/BSD</tt>,
7487 <tt>/usr/share/common-licenses/Artistic</tt>,
7488 <tt>/usr/share/common-licenses/GPL</tt>, and
7489 <tt>/usr/share/common-licenses/LGPL</tt> respectively,
7490 rather than quoting them in the copyright file.
7494 You should not use the copyright file as a general <tt>README</tt>
7495 file. If your package has such a file it should be
7496 installed in <tt>/usr/share/doc/<var>package</var>/README</tt> or
7497 <tt>README.Debian</tt> or some other appropriate place.</p>
7501 <heading>Examples</heading>
7504 Any examples (configurations, source files, whatever),
7505 should be installed in a directory
7506 <tt>/usr/share/doc/<var>package</var>/examples</tt>. These
7507 files should not be referenced by any program: they're there
7508 for the benefit of the system administrator and users as
7509 documentation only. Architecture-specific example files
7510 should be installed in a directory
7511 <tt>/usr/lib/<var>package</var>/examples</tt> with symbolic
7513 <tt>/usr/share/doc/<var>package</var>/examples</tt>, or the
7514 latter directory itself may be a symbolic link to the
7519 <sect id="instchangelog">
7520 <heading>Changelog files</heading>
7523 Packages that are not Debian-native must contain a
7524 compressed copy of the <tt>debian/changelog</tt> file from
7525 the Debian source tree in
7526 <tt>/usr/share/doc/<var>package</var></tt> with the name
7527 <tt>changelog.Debian.gz</tt>. If an upstream changelog is
7528 available, it should be accessible as
7529 <tt>/usr/share/doc/<var>package</var>/changelog.gz</tt> in
7530 plain text. If the upstream changelog is distributed in
7531 HTML, it should be made available in that form as
7532 <tt>/usr/share/doc/<var>package</var>/changelog.html.gz</tt>
7533 and a plain text <tt>changelog.gz</tt> should be generated
7534 from it using, for example, <tt>lynx -dump -nolist</tt>. If
7535 the upstream changelog files do not already conform to this
7536 naming convention, then this may be achieved either by
7537 renaming the files, or by adding a symbolic link, at the
7538 maintainer's discretion.<footnote>
7540 Rationale: People should not have to look in places for
7541 upstream changelogs merely because they are given
7542 different names or are distributed in HTML format.
7548 All of these files should be installed compressed using
7549 <tt>gzip -9</tt>, as they will become large with time even
7550 if they start out small.
7554 If the package has only one changelog which is used both as
7555 the Debian changelog and the upstream one because there is
7556 no separate upstream maintainer then that changelog should
7557 usually be installed as
7558 <tt>/usr/share/doc/<var>package</var>/changelog.gz</tt>; if
7559 there is a separate upstream maintainer, but no upstream
7560 changelog, then the Debian changelog should still be called
7561 <tt>changelog.Debian.gz</tt>.</p>
7565 <appendix id="pkg-scope">
7566 <heading>Introduction and scope of these appendices</heading>
7569 These appendices are taken essentially verbatim from the
7570 now-deprecated Packaging Manual, version 3.2.1.0. They are
7571 the chapters which are likely to be of use to package
7572 maintainers and which have not already been included in the
7573 policy document itself. Most of these sections are very likely
7574 not relevant to policy; they should be treated as
7575 documentation for the packaging system. Please note that these
7576 appendices are included for convenience, and for historical
7577 reasons: they used to be part of policy package, and they have
7578 not yet been incorporated into dpkg documentation. However,
7579 they still have value, and hence they are presented here.
7582 They have not yet been checked to ensure that they are
7583 compatible with the contents of policy, and if there are any
7584 contradictions, the version in the main policy document takes
7585 precedence. The remaining chapters of the old Packaging
7586 Manual have also not been read in detail to ensure that there
7587 are not parts which have been left out. Both of these will be
7592 <prgn>dpkg</prgn> is a suite of programs for creating binary
7593 package files and installing and removing them on Unix
7596 <prgn>dpkg</prgn> is targetted primarily at Debian
7597 GNU/Linux, but may work on or be ported to other
7604 The binary packages are designed for the management of
7605 installed executable programs (usually compiled binaries) and
7606 their associated data, though source code examples and
7607 documentation are provided as part of some packages.</p>
7610 This manual describes the technical aspects of creating Debian
7611 binary packages (<tt>.deb</tt> files). It documents the
7612 behaviour of the package management programs
7613 <prgn>dpkg</prgn>, <prgn>dselect</prgn> et al. and the way
7614 they interact with packages.</p>
7617 It also documents the interaction between
7618 <prgn>dselect</prgn>'s core and the access method scripts it
7619 uses to actually install the selected packages, and describes
7620 how to create a new access method.</p>
7623 This manual does not go into detail about the options and
7624 usage of the package building and installation tools. It
7625 should therefore be read in conjuction with those programs'
7630 The utility programs which are provided with <prgn>dpkg</prgn>
7631 for managing various system configuration and similar issues,
7632 such as <prgn>update-rc.d</prgn> and
7633 <prgn>install-info</prgn>, are not described in detail here -
7634 please see their manpages.
7638 It does <em>not</em> describe the policy requirements imposed
7639 on Debian packages, such as the permissions on files and
7640 directories, documentation requirements, upload procedure, and
7641 so on. You should see the Debian packaging policy manual for
7642 these details. (Many of them will probably turn out to be
7643 helpful even if you don't plan to upload your package and make
7644 it available as part of the distribution.)
7648 It is assumed that the reader is reasonably familiar with the
7649 <prgn>dpkg</prgn> System Administrators' manual.
7650 Unfortunately this manual does not yet exist.
7654 The Debian version of the FSF's GNU hello program is provided
7655 as an example for people wishing to create Debian
7656 packages. The Debian <prgn>debmake</prgn> package is
7657 recommended as a very helpful tool in creating and maintaining
7658 Debian packages. However, while the tools and examples are
7659 helpful, they do not replace the need to read and follow the
7660 Policy and Programmer's Manual.</p>
7663 <appendix id="pkg-binarypkg"><heading>Binary packages (from old
7668 The binary package has two main sections. The first part
7669 consists of various control information files and scripts used
7670 by <prgn>dpkg</prgn> when installing and removing. See <ref
7671 id="pkg-controlarea">.
7675 The second part is an archive containing the files and
7676 directories to be installed.
7680 In the future binary packages may also contain other
7681 components, such as checksums and digital signatures. The
7682 format for the archive is described in full in the
7683 <tt>deb(5)</tt> manpage.
7687 <sect id="pkg-bincreating"><heading>Creating package files -
7688 <prgn>dpkg-deb</prgn>
7692 All manipulation of binary package files is done by
7693 <prgn>dpkg-deb</prgn>; it's the only program that has
7694 knowledge of the format. (<prgn>dpkg-deb</prgn> may be
7695 invoked by calling <prgn>dpkg</prgn>, as <prgn>dpkg</prgn>
7696 will spot that the options requested are appropriate to
7697 <prgn>dpkg-deb</prgn> and invoke that instead with the same
7702 In order to create a binary package you must make a
7703 directory tree which contains all the files and directories
7704 you want to have in the filesystem data part of the package.
7705 In Debian-format source packages this directory is usually
7706 <tt>debian/tmp</tt>, relative to the top of the package's
7711 They should have the locations (relative to the root of the
7712 directory tree you're constructing) ownerships and
7713 permissions which you want them to have on the system when
7718 With current versions of <prgn>dpkg</prgn> the uid/username
7719 and gid/groupname mappings for the users and groups being
7720 used should be the same on the system where the package is
7721 built and the one where it is installed.
7725 You need to add one special directory to the root of the
7726 miniature filesystem tree you're creating:
7727 <prgn>DEBIAN</prgn>. It should contain the control
7728 information files, notably the binary package control file
7729 (see <ref id="pkg-controlfile">).
7733 The <prgn>DEBIAN</prgn> directory will not appear in the
7734 filesystem archive of the package, and so won't be installed
7735 by <prgn>dpkg</prgn> when the package is installed.
7739 When you've prepared the package, you should invoke:
7741 dpkg --build <var>directory</var>
7746 This will build the package in
7747 <tt><var>directory</var>.deb</tt>. (<prgn>dpkg</prgn> knows
7748 that <tt>--build</tt> is a <prgn>dpkg-deb</prgn> option, so
7749 it invokes <prgn>dpkg-deb</prgn> with the same arguments to
7754 See the manpage <manref name="dpkg-deb" section="8"> for details of how
7755 to examine the contents of this newly-created file. You may find the
7756 output of following commands enlightening:
7758 dpkg-deb --info <var>filename</var>.deb
7759 dpkg-deb --contents <var>filename</var>.deb
7760 dpkg --contents <var>filename</var>.deb
7762 To view the copyright file for a package you could use this command:
7764 dpkg --fsys-tarfile <var>filename</var>.deb | tar xof usr/share/doc/<var>\*</var>copyright | less
7769 <sect id="pkg-controlarea">
7771 Package control information files
7775 The control information portion of a binary package is a
7776 collection of files with names known to <prgn>dpkg</prgn>.
7777 It will treat the contents of these files specially - some
7778 of them contain information used by <prgn>dpkg</prgn> when
7779 installing or removing the package; others are scripts which
7780 the package maintainer wants <prgn>dpkg</prgn> to run.
7784 It is possible to put other files in the package control
7785 area, but this is not generally a good idea (though they
7786 will largely be ignored).
7790 Here is a brief list of the control info files supported by
7791 <prgn>dpkg</prgn> and a summary of what they're used for.
7796 <tag><tt>control</tt>
7800 This is the key description file used by
7801 <prgn>dpkg</prgn>. It specifies the package's name
7802 and version, gives its description for the user,
7803 states its relationships with other packages, and so
7804 forth. See <ref id="pkg-controlfile">.
7808 It is usually generated automatically from information
7809 in the source package by the
7810 <prgn>dpkg-gencontrol</prgn> program, and with
7811 assistance from <prgn>dpkg-shlibdeps</prgn>. See <ref
7812 id="pkg-sourcetools">.</p>
7815 <tag><tt>postinst</tt>, <tt>preinst</tt>, <tt>postrm</tt>,
7821 These are exectuable files (usually scripts) which
7822 <prgn>dpkg</prgn> runs during installation, upgrade
7823 and removal of packages. They allow the package to
7824 deal with matters which are particular to that package
7825 or require more complicated processing than that
7826 provided by <prgn>dpkg</prgn>. Details of when and
7827 how they are called are in <ref
7828 id="maintainerscripts">.
7832 It is very important to make these scripts
7836 That means that if it runs successfully or fails
7837 and then you call it again it doesn't bomb out,
7838 but just ensures that everything is the way it
7841 </footnote> This is so that if an error occurs, the
7842 user interrupts <prgn>dpkg</prgn> or some other
7843 unforeseen circumstance happens you don't leave the
7844 user with a badly-broken package.
7848 The maintainer scripts are guaranteed to run with a
7849 controlling terminal and can interact with the user.
7850 If they need to prompt for passwords, do full-screen
7851 interaction or something similar you should do these
7852 things to and from <tt>/dev/tty</tt>, since
7853 <prgn>dpkg</prgn> will at some point redirect scripts'
7854 standard input and output so that it can log the
7855 installation process. Likewise, because these scripts
7856 may be executed with standard output redirected into a
7857 pipe for logging purposes, Perl scripts should set
7858 unbuffered output by setting <tt>$|=1</tt> so that the
7859 output is printed immediately rather than being
7864 Each script should return a zero exit status for
7865 success, or a nonzero one for failure.</p>
7868 <tag><tt>conffiles</tt>
7873 This file contains a list of configuration files which
7874 are to be handled automatically by <prgn>dpkg</prgn>
7875 (see <ref id="pkg-conffiles">). Note that not necessarily
7876 every configuration file should be listed here.</p>
7879 <tag><tt>shlibs</tt>
7884 This file contains a list of the shared libraries
7885 supplied by the package, with dependency details for
7886 each. This is used by <prgn>dpkg-shlibdeps</prgn>
7887 when it determines what dependencies are required in a
7888 package control file. The <tt>shlibs</tt> file format
7889 is described on <ref id="shlibs">.
7895 <sect id="pkg-controlfile">
7897 The main control information file: <tt>control</tt>
7900 The most important control information file used by
7901 <prgn>dpkg</prgn> when it installs a package is
7902 <tt>control</tt>. It contains all the package's `vital
7907 The binary package control files of packages built from
7908 Debian sources are made by a special tool,
7909 <prgn>dpkg-gencontrol</prgn>, which reads
7910 <tt>debian/control</tt> and <tt>debian/changelog</tt> to
7911 find the information it needs. See <ref id="pkg-sourcepkg"> for
7916 The fields in binary package control files are:
7917 <list compact="compact">
7919 <p><qref id="pkg-f-Package"><tt>Package</tt></qref> (mandatory)</p>
7922 <p><qref id="versions"><tt>Version</tt></qref> (mandatory)</p>
7924 <item><p><qref id="pkg-f-Architecture"><tt>Architecture</tt></qref>
7928 This field should appear in all packages, though
7929 <prgn>dpkg</prgn> doesn't require it yet so that
7930 old packages can still be installed.
7936 <p><qref id="relationships"><tt>Depends</tt>,
7937 <tt>Provides</tt> et al.</qref></p>
7940 <p><qref id="pkg-f-Essential"><tt>Essential</tt></qref></p>
7943 <p><qref id="pkg-f-Maintainer"><tt>Maintainer</tt></qref></p>
7946 <p><qref id="pkg-f-classification"><tt>Section</tt>,
7947 <tt>Priority</tt></qref></p>
7950 <p><qref id="pkg-f-Source"><tt>Source</tt></qref></p>
7953 <p><qref id="descriptions"><tt>Description</tt></qref></p>
7957 <qref id="pkg-f-Installed-Size"><tt>Installed-Size</tt></qref>
7963 A description of the syntax of control files and the purpose
7964 of these fields is available in <ref id="pkg-controlfields">.
7969 <heading>Time Stamps</heading>
7971 Maintainers are encouraged to preserve the modification
7972 times of the upstream source files in a package, as far as
7973 is reasonably possible.
7976 The rationale is that there is some information conveyed
7977 by knowing the age of the file, for example, you could
7978 recognize that some documentation is very old by looking
7979 at the modification time, so it would be nice if the
7980 modification time of the upstream source would be
7988 <appendix id="pkg-sourcepkg">
7989 <heading>Source packages (from old Packaging Manual) </heading>
7992 The Debian binary packages in the distribution are generated
7993 from Debian sources, which are in a special format to assist
7994 the easy and automatic building of binaries.
7998 There was a previous version of the Debian source format,
7999 which is now being phased out. Instructions for converting an
8000 old-style package are given in the Debian policy manual.
8003 <sect id="pkg-sourcetools">
8004 <heading>Tools for processing source packages</heading>
8007 Various tools are provided for manipulating source packages;
8008 they pack and unpack sources and help build of binary
8009 packages and help manage the distribution of new versions.
8013 They are introduced and typical uses described here; see
8014 <manref name="dpkg-source" section="1"> for full
8015 documentation about their arguments and operation.
8019 For examples of how to construct a Debian source package,
8020 and how to use those utilities that are used by Debian
8021 source packages, please see the <prgn>hello</prgn> example
8027 <prgn>dpkg-source</prgn> - packs and unpacks Debian source
8032 This program is frequently used by hand, and is also
8033 called from package-independent automated building scripts
8034 such as <prgn>dpkg-buildpackage</prgn>.
8038 To unpack a package it is typically invoked with
8040 dpkg-source -x <var>.../path/to/filename</var>.dsc
8045 with the <tt><var>filename</var>.tar.gz</tt> and
8046 <tt><var>filename</var>.diff.gz</tt> (if applicable) in
8047 the same directory. It unpacks into
8048 <tt><var>package</var>-<var>version</var></tt>, and if
8050 <tt><var>package</var>-<var>version</var>.orig</tt>, in
8051 the current directory.
8055 To create a packed source archive it is typically invoked:
8057 dpkg-source -b <var>package</var>-<var>version</var>
8062 This will create the <tt>.dsc</tt>, <tt>.tar.gz</tt> and
8063 <tt>.diff.gz</tt> (if appropriate) in the current
8064 directory. <prgn>dpkg-source</prgn> does not clean the
8065 source tree first - this must be done separately if it is
8070 See also <ref id="pkg-sourcearchives">.</p>
8076 <prgn>dpkg-buildpackage</prgn> - overall package-building
8081 <prgn>dpkg-buildpackage</prgn> is a script which invokes
8082 <prgn>dpkg-source</prgn>, the <tt>debian/rules</tt>
8083 targets <tt>clean</tt>, <tt>build</tt> and
8084 <tt>binary</tt>, <prgn>dpkg-genchanges</prgn> and
8085 <prgn>pgp</prgn> to build a signed source and binary
8090 It is usually invoked by hand from the top level of the
8091 built or unbuilt source directory. It may be invoked with
8092 no arguments; useful arguments include:
8093 <taglist compact="compact">
8094 <tag><tt>-uc</tt>, <tt>-us</tt></tag>
8097 Do not PGP-sign the <tt>.changes</tt> file or the
8098 source package <tt>.dsc</tt> file, respectively.</p>
8100 <tag><tt>-p<var>pgp-command</var></tt></tag>
8103 Invoke <var>pgp-command</var> instead of finding
8104 <tt>pgp</tt> on the <prgn>PATH</prgn>.
8105 <var>pgp-command</var> must behave just like
8106 <prgn>pgp</prgn>.</p>
8108 <tag><tt>-r<var>root-command</var></tt></tag>
8111 When root privilege is required, invoke the command
8112 <var>root-command</var>. <var>root-command</var>
8113 should invoke its first argument as a command, from
8114 the <prgn>PATH</prgn> if necessary, and pass its
8115 second and subsequent arguments to the command it
8116 calls. If no <var>root-command</var> is supplied
8117 then <var>dpkg-buildpackage</var> will take no
8118 special action to gain root privilege, so that for
8119 most packages it will have to be invoked as root to
8122 <tag><tt>-b</tt>, <tt>-B</tt></tag>
8125 Two types of binary-only build and upload - see
8126 <manref name="dpkg-source" section="1">.
8135 <prgn>dpkg-gencontrol</prgn> - generates binary package
8140 This program is usually called from <tt>debian/rules</tt>
8141 (see <ref id="pkg-sourcetree">) in the top level of the source
8146 This is usually done just before the files and directories in the
8147 temporary directory tree where the package is being built have their
8148 permissions and ownerships set and the package is constructed using
8149 <prgn>dpkg-deb/</prgn>
8152 This is so that the control file which is produced has
8153 the right permissions
8159 <prgn>dpkg-gencontrol</prgn> must be called after all the
8160 files which are to go into the package have been placed in
8161 the temporary build directory, so that its calculation of
8162 the installed size of a package is correct.
8166 It is also necessary for <prgn>dpkg-gencontrol</prgn> to
8167 be run after <prgn>dpkg-shlibdeps</prgn> so that the
8168 variable substitutions created by
8169 <prgn>dpkg-shlibdeps</prgn> in <tt>debian/substvars</tt>
8174 For a package which generates only one binary package, and
8175 which builds it in <tt>debian/tmp</tt> relative to the top
8176 of the source package, it is usually sufficient to call
8177 <prgn>dpkg-gencontrol</prgn>.
8181 Sources which build several binaries will typically need
8184 dpkg-gencontrol -Pdebian/tmp-<var>pkg</var> -p<var>package</var>
8185 </example> The <tt>-P</tt> tells
8186 <prgn>dpkg-gencontrol</prgn> that the package is being
8187 built in a non-default directory, and the <tt>-p</tt>
8188 tells it which package's control file should be generated.
8192 <prgn>dpkg-gencontrol</prgn> also adds information to the
8193 list of files in <tt>debian/files</tt>, for the benefit of
8194 (for example) a future invocation of
8195 <prgn>dpkg-genchanges</prgn>.</p>
8200 <prgn>dpkg-shlibdeps</prgn> - calculates shared library
8205 This program is usually called from <tt>debian/rules</tt>
8206 just before <prgn>dpkg-gencontrol</prgn> (see <ref
8207 id="pkg-sourcetree">), in the top level of the source tree.
8211 Its arguments are executables.
8214 In a forthcoming dpkg version,
8215 <prgn>dpkg-shlibdeps</prgn> would be required to be
8216 called on shared libraries as well.
8219 They may be specified either in the locations in the
8220 source tree where they are created or in the locations
8221 in the temporary build tree where they are installed
8222 prior to binary package creation.
8224 </footnote> for which shared library dependencies should
8225 be included in the binary package's control file.
8229 If some of the found shared libraries should only
8230 warrant a <tt>Recommends</tt> or <tt>Suggests</tt>, or if
8231 some warrant a <tt>Pre-Depends</tt>, this can be achieved
8232 by using the <tt>-d<var>dependency-field</var></tt> option
8233 before those executable(s). (Each <tt>-d</tt> option
8234 takes effect until the next <tt>-d</tt>.)
8238 <prgn>dpkg-shlibdeps</prgn> does not directly cause the
8239 output control file to be modified. Instead by default it
8240 adds to the <tt>debian/substvars</tt> file variable
8241 settings like <tt>shlibs:Depends</tt>. These variable
8242 settings must be referenced in dependency fields in the
8243 appropriate per-binary-package sections of the source
8248 For example, the <prgn>procps</prgn> package generates two
8249 kinds of binaries, simple C binaries like <prgn>ps</prgn>
8250 which require a predependency and full-screen ncurses
8251 binaries like <prgn>top</prgn> which require only a
8252 recommendation. It can say in its <tt>debian/rules</tt>:
8254 dpkg-shlibdeps -dPre-Depends ps -dRecommends top
8256 and then in its main control file <tt>debian/control</tt>:
8260 Pre-Depends: ${shlibs:Pre-Depends}
8261 Recommends: ${shlibs:Recommends}
8267 Sources which produce several binary packages with
8268 different shared library dependency requirements can use
8269 the <tt>-p<var>varnameprefix</var></tt> option to override
8270 the default <tt>shlib:</tt> prefix (one invocation of
8271 <prgn>dpkg-shlibdeps</prgn> per setting of this option).
8272 They can thus produce several sets of dependency
8273 variables, each of the form
8274 <tt><var>varnameprefix</var>:<var>dependencyfield</var></tt>,
8275 which can be referred to in the appropriate parts of the
8276 binary package control files.
8283 <prgn>dpkg-distaddfile</prgn> - adds a file to
8284 <tt>debian/files</tt>
8288 Some packages' uploads need to include files other than
8289 the source and binary package files.
8293 <prgn>dpkg-distaddfile</prgn> adds a file to the
8294 <tt>debian/files</tt> file so that it will be included in
8295 the <tt>.changes</tt> file when
8296 <prgn>dpkg-genchanges</prgn> is run.
8300 It is usually invoked from the <tt>binary</tt> target of
8301 <tt>debian/rules</tt>:
8303 dpkg-distaddfile <var>filename</var> <var>section</var> <var>priority</var>
8305 The <var>filename</var> is relative to the directory where
8306 <prgn>dpkg-genchanges</prgn> will expect to find it - this
8307 is usually the directory above the top level of the source
8308 tree. The <tt>debian/rules</tt> target should put the
8309 file there just before or just after calling
8310 <prgn>dpkg-distaddfile</prgn>.
8314 The <var>section</var> and <var>priority</var> are passed
8315 unchanged into the resulting <tt>.changes</tt> file. See
8316 <ref id="pkg-f-classification">.
8321 <sect1><heading><prgn>dpkg-genchanges</prgn> - generates a <tt>.changes</tt> upload
8326 This program is usually called by package-independent
8327 automatic building scripts such as
8328 <prgn>dpkg-buildpackage</prgn>, but it may also be called
8333 It is usually called in the top level of a built source
8334 tree, and when invoked with no arguments will print out a
8335 straightforward <tt>.changes</tt> file based on the
8336 information in the source package's changelog and control
8337 file and the binary and source packages which should have
8343 <sect1><heading><prgn>dpkg-parsechangelog</prgn> - produces parsed representation of
8348 This program is used internally by
8349 <prgn>dpkg-source</prgn> et al. It may also occasionally
8350 be useful in <tt>debian/rules</tt> and elsewhere. It
8351 parses a changelog, <tt>debian/changelog</tt> by default,
8352 and prints a control-file format representation of the
8353 information in it to standard output.
8357 <sect1 id="pkg-dpkgarch"><heading><prgn>dpkg-architecture</prgn> -
8358 information about the build and host system
8362 This program can be used manually, but is also invoked by
8363 <tt>dpkg-buildpackage</tt> or <tt>debian/rules</tt> to set
8364 to set environment or make variables which specify the build and
8365 host architecture for the package building process.
8370 <sect id="pkg-sourcetree"><heading>The Debianised source tree
8374 The source archive scheme described later is intended to
8375 allow a Debianised source tree with some associated control
8376 information to be reproduced and transported easily. The
8377 Debianised source tree is a version of the original program
8378 with certain files added for the benefit of the
8379 Debianisation process, and with any other changes required
8380 made to the rest of the source code and installation
8385 The extra files created for Debian are in the subdirectory
8386 <tt>debian</tt> of the top level of the Debianised source
8387 tree. They are described below.
8390 <sect1 id="pkg-debianrules"><heading><tt>debian/rules</tt> - the main building
8395 This file is an executable makefile, and contains the
8396 package-specific recipies for compiling the package and
8397 building binary package(s) out of the source.
8401 It must start with the line <tt>#!/usr/bin/make -f</tt>,
8402 so that it can be invoked by saying its name rather than
8403 invoking <prgn>make</prgn> explicitly.
8407 Since an interactive <tt>debian/rules</tt> script makes it
8408 impossible to autocompile that package and also makes it
8409 hard for other people to reproduce the same binary
8410 package, all <strong>required targets</strong> have to be
8411 non-interactive. At a minimul, required targets are the
8412 ones called by <prgn>dpkg-buildpackage</prgn>, namely,
8413 <em>clean</em>, <em>binary</em>, <em>binary-arch</em>, and
8414 <em>build</em>. It also follows that any target that these
8415 targets depend on must also be non-interactive.
8419 The targets which are required to be present are:
8421 <tag><tt>build</tt></tag>
8424 This should perform all non-interactive
8425 configuration and compilation of the package. If a
8426 package has an interactive pre-build configuration
8427 routine, the Debianised source package should be
8428 built after this has taken place, so that it can be
8429 built without rerunning the configuration.
8433 A package may also provide both of the targets
8434 <tt>build-arch</tt> and <tt>build-indep</tt>. The
8435 <tt>build-arch</tt> target, if provided, should
8436 perform all non-interactive configuration and
8437 compilation required for producing all
8438 architecture-dependant binary packages (those packages
8439 for which the body of the <tt>Architecture</tt> field
8440 in <tt>debian/control</tt> is not <tt>all</tt>).
8441 Similarly, the <tt>build-indep</tt> target, if
8442 provided, should perform all non-interactive
8443 configuration and compilation required for producing
8444 all architecture-independent binary packages (those
8445 packages for which the body of the
8446 <tt>Architecture</tt> field in <tt>debian/control</tt>
8447 is <tt>all</tt>). The <tt>build</tt> target should
8448 depend on those of the targets <tt>build-arch</tt> and
8449 <tt>build-indep</tt> that are provided in the rules
8454 If one or both of the targets <tt>build-arch</tt> and
8455 <tt>build-indep</tt> are not provided, then invoking
8456 <tt>debian/rules</tt> with one of the not-provided
8457 targets as arguments should produce a exit status code
8458 of 2. Usually this is provided automatically by make
8459 if the target is missing.
8463 For some packages, notably ones where the same
8464 source tree is compiled in different ways to produce
8465 two binary packages, the <tt>build</tt> target does
8466 not make much sense. For these packages it is good
8467 enough to provide two (or more) targets
8468 (<tt>build-a</tt> and <tt>build-b</tt> or whatever)
8469 for each of the ways of building the package, and a
8470 <tt>build</tt> target that does nothing. The
8471 <tt>binary</tt> target will have to build the
8472 package in each of the possible ways and make the
8473 binary package out of each.
8477 The targets <tt>build</tt>, <tt>build-arch</tt>
8478 and <tt>build-indep</tt> target must not do
8479 anything that might require root privilege.
8483 The <tt>build</tt> target may need to run
8484 <tt>clean</tt> first - see below.
8488 When a package has a configuration routine that takes
8489 a long time, or when the makefiles are poorly
8490 designed, or when <tt>build</tt> needs to run
8491 <tt>clean</tt> first, it is a good idea to <tt>touch
8492 build</tt> when the build process is complete. This
8493 will ensure that if <tt>debian/rules build</tt> is run
8494 again it will not rebuild the whole program.
8498 <tag><tt>binary</tt>, <tt>binary-arch</tt>,
8499 <tt>binary-indep</tt>
8503 The <tt>binary</tt> target should be all that is
8504 necessary for the user to build the binary
8505 package. All these targets are required to be
8506 non-interactive. It is split into two parts:
8507 <tt>binary-arch</tt> builds the packages' output
8508 files which are specific to a particular
8509 architecture, and <tt>binary-indep</tt> builds
8510 those which are not.
8514 <tt>binary</tt> should usually be a target with
8515 no commands which simply depends on
8516 <prgn>binary-arch</prgn> and
8517 <prgn>binary-indep</prgn>.
8521 Both <prgn>binary-*</prgn> targets should depend on
8522 the <tt>build</tt> target, above, so that the
8523 package is built if it has not been already. It
8524 should then create the relevant binary package(s),
8525 using <prgn>dpkg-gencontrol</prgn> to make their
8526 control files and <prgn>dpkg-deb</prgn> to build
8527 them and place them in the parent of the top level
8532 If one of the <prgn>binary-*</prgn> targets has
8533 nothing to do (this will be always be the case if
8534 the source generates only a single binary package,
8535 whether architecture-dependent or not) it
8536 <em>must</em> still exist, but should always
8541 <ref id="pkg-binarypkg"> describes how to construct
8546 The <tt>binary</tt> targets must be invoked as
8551 <tag><tt>clean</tt></tag>
8555 This should undo any effects that the
8556 <tt>build</tt> and <tt>binary</tt> targets
8557 may have had, except that it should leave alone any
8558 output files created in the parent directory by a
8559 run of <tt>binary</tt>. This target is required
8560 to be non-interactive.
8564 If a <tt>build</tt> file is touched at the end
8565 of the <tt>build</tt> target, as suggested
8566 above, it must be removed as the first thing that
8567 <tt>clean</tt> does, so that running
8568 <tt>build</tt> again after an interrupted
8569 <tt>clean</tt> doesn't think that everything is
8574 The <tt>clean</tt> target must be invoked as
8575 root if <tt>binary</tt> has been invoked since
8576 the last <tt>clean</tt>, or if
8577 <tt>build</tt> has been invoked as root (since
8578 <tt>build</tt> may create directories, for
8583 <tag><tt>get-orig-source</tt> (optional)</tag>
8587 This target fetches the most recent version of the
8588 original source package from a canonical archive
8589 site (via FTP or WWW, for example), does any
8590 necessary rearrangement to turn it into the original
8591 source tarfile format described below, and leaves it
8592 in the current directory.
8596 This target may be invoked in any directory, and
8597 should take care to clean up any temporary files it
8602 This target is optional, but providing it if
8603 possible is a good idea.
8609 The <tt>build</tt>, <tt>binary</tt> and
8610 <tt>clean</tt> targets must be invoked with a current
8611 directory of the package's top-level directory.
8616 Additional targets may exist in <tt>debian/rules</tt>,
8617 either as published or undocumented interfaces or for the
8618 package's internal use.
8622 The architecture we build on and build for is determined by make
8623 variables via dpkg-architecture (see <ref id="pkg-dpkgarch">). You can
8624 get the Debian architecture and the GNU style architecture
8625 specification string for the build machine as well as the host
8626 machine. Here is a list of supported make variables:
8627 <list compact="compact">
8629 <p><tt>DEB_*_ARCH</tt> (the Debian architecture)</p>
8632 <p><tt>DEB_*_GNU_TYPE</tt> (the GNU style architecture
8633 specification string)</p>
8636 <p><tt>DEB_*_GNU_CPU</tt> (the CPU part of DEB_*_GNU_TYPE)</p>
8639 <p><tt>DEB_*_GNU_SYSTEM</tt> (the System part of
8645 where <tt>*</tt> is either <tt>BUILD</tt> for specification of
8646 the build machine or <tt>HOST</tt> for specification of the machine
8651 Backward compatibility can be provided in the rules file
8652 by setting the needed variables to suitable default
8653 values, please refer to the documentation of
8654 dpkg-architecture for details.
8658 It is important to understand that the <tt>DEB_*_ARCH</tt>
8659 string does only determine which Debian architecture we
8660 build on resp. for. It should not be used to get the CPU
8661 or System information, the GNU style variables should be
8667 <sect1><heading><tt>debian/control</tt>
8671 This file contains version-independent details about the
8672 source package and about the binary packages it creates.
8676 It is a series of sets of control fields, each
8677 syntactically similar to a binary package control file.
8678 The sets are separated by one or more blank lines. The
8679 first set is information about the source package in
8680 general; each subsequent set describes one binary package
8681 that the source tree builds.
8685 The syntax and semantics of the fields are described below
8686 in <ref id="pkg-controlfields">.
8690 The general (binary-package-independent) fields are:
8691 <list compact="compact">
8693 <p><qref id="pkg-f-Source"><tt>Source</tt></qref> (mandatory)</p>
8696 <p><qref id="pkg-f-Maintainer"><tt>Maintainer</tt></qref></p>
8700 <qref id="pkg-f-classification"><tt>Section</tt> and
8701 <tt>Priority</tt></qref>
8702 (classification, mandatory)
8707 <qref id="relationships"><tt>Build-Depends</tt> et
8708 al.</qref> (source package interrelationships)
8713 <qref id="pkg-f-Standards-Version"><tt>Standards-Version</tt></qref>
8719 The per-binary-package fields are:
8720 <list compact="compact">
8722 <p><qref id="pkg-f-Package"><tt>Package</tt></qref> (mandatory)</p>
8726 <qref id="pkg-f-Architecture"><tt>Architecture</tt></qref>
8730 <p><qref id="descriptions"><tt>Description</tt></qref></p>
8734 <qref id="pkg-f-classification"><tt>Section</tt> and
8735 <tt>Priority</tt></qref> (classification)</p>
8738 <p><qref id="pkg-f-Essential"><tt>Essential</tt></qref></p>
8742 <qref id="relationships"><tt>Depends</tt> et
8743 al.</qref> (binary package interrelationships)
8749 These fields are used by <prgn>dpkg-gencontrol</prgn> to
8750 generate control files for binary packages (see below), by
8751 <prgn>dpkg-genchanges</prgn> to generate the
8752 <tt>.changes</tt> file to accompany the upload, and by
8753 <prgn>dpkg-source</prgn> when it creates the <tt>.dsc</tt>
8754 source control file as part of a source archive.
8758 The fields here may contain variable references - their
8759 values will be substituted by
8760 <prgn>dpkg-gencontrol</prgn>, <prgn>dpkg-genchanges</prgn>
8761 or <prgn>dpkg-source</prgn> when they generate output
8762 control files. See <ref id="pkg-srcsubstvars"> for details.
8765 <p> <sect2><heading>User-defined fields
8769 Additional user-defined fields may be added to the
8770 source package control file. Such fields will be
8771 ignored, and not copied to (for example) binary or
8772 source package control files or upload control files.
8776 If you wish to add additional unsupported fields to
8777 these output files you should use the mechanism
8782 Fields in the main source control information file with
8783 names starting <tt>X</tt>, followed by one or more of
8784 the letters <tt>BCS</tt> and a hyphen <tt>-</tt>, will
8785 be copied to the output files. Only the part of the
8786 field name after the hyphen will be used in the output
8787 file. Where the letter <tt>B</tt> is used the field
8788 will appear in binary package control files, where the
8789 letter <tt>S</tt> is used in source package control
8790 files and where <tt>C</tt> is used in upload control
8791 (<tt>.changes</tt>) files.
8795 For example, if the main source information control file
8798 XBS-Comment: I stand between the candle and the star.
8800 then the binary and source package control files will contain the
8803 Comment: I stand between the candle and the star.
8810 <sect1 id="pkg-dpkgchangelog"><heading><tt>debian/changelog</tt>
8814 This file records the changes to the Debian-specific parts of the
8818 Though there is nothing stopping an author who is also
8819 the Debian maintainer from using it for all their
8820 changes, it will have to be renamed if the Debian and
8821 upstream maintainers become different
8828 It has a special format which allows the package building
8829 tools to discover which version of the package is being
8830 built and find out other release-specific information.
8834 That format is a series of entries like this:
8836 <var>package</var> (<var>version</var>) <var>distribution(s)</var>; urgency=<var>urgency</var>
8838 * <var>change details</var>
8839 <var>more change details</var>
8840 * <var>even more change details</var>
8842 -- <var>maintainer name and email address</var> <var>date</var>
8847 <var>package</var> and <var>version</var> are the source
8848 package name and version number.
8852 <var>distribution(s)</var> lists the distributions where
8853 this version should be installed when it is uploaded - it
8854 is copied to the <tt>Distribution</tt> field in the
8855 <tt>.changes</tt> file. See <ref id="pkg-f-Distribution">.
8859 <var>urgency</var> is the value for the <tt>Urgency</tt>
8860 field in the <tt>.changes</tt> file for the upload. See
8861 <ref id="pkg-f-Urgency">. It is not possible to specify an
8862 urgency containing commas; commas are used to separate
8863 <tt><var>keyword</var>=<var>value</var></tt> settings in
8864 the <prgn>dpkg</prgn> changelog format (though there is
8865 currently only one useful <var>keyword</var>,
8870 The change details may in fact be any series of lines
8871 starting with at least two spaces, but conventionally each
8872 change starts with an asterisk and a separating space and
8873 continuation lines are indented so as to bring them in
8874 line with the start of the text above. Blank lines may be
8875 used here to separate groups of changes, if desired.
8879 The maintainer name and email address should <em>not</em>
8880 necessarily be those of the usual package maintainer.
8881 They should be the details of the person doing
8882 <em>this</em> version. The information here will be
8883 copied to the <tt>.changes</tt> file, and then later used
8884 to send an acknowledgement when the upload has been
8889 The <var>date</var> should be in RFC822 format
8892 This is generated by the <prgn>822-date</prgn>
8895 </footnote>; it should include the timezone specified
8896 numerically, with the timezone name or abbreviation
8897 optionally present as a comment.
8901 The first `title' line with the package name should start
8902 at the left hand margin; the `trailer' line with the
8903 maintainer and date details should be preceded by exactly
8904 one space. The maintainer details and the date must be
8905 separated by exactly two spaces.
8909 An Emacs mode for editing this format is available: it is
8910 called <tt>debian-changelog-mode</tt>. You can have this
8911 mode selected automatically when you edit a Debian
8912 changelog by adding a local variables clause to the end of
8916 <sect2><heading>Defining alternative changelog formats
8920 It is possible to use a different format to the standard
8921 one, by providing a parser for the format you wish to
8926 In order to have <tt>dpkg-parsechangelog</tt> run your
8927 parser, you must include a line within the last 40 lines
8928 of your file matching the Perl regular expression:
8929 <tt>\schangelog-format:\s+([0-9a-z]+)\W</tt> The part in
8930 parentheses should be the name of the format. For
8931 example, you might say:
8933 @@@ changelog-format: joebloggs @@@
8935 Changelog format names are non-empty strings of alphanumerics.
8939 If such a line exists then <tt>dpkg-parsechangelog</tt>
8940 will look for the parser as
8941 <tt>/usr/lib/dpkg/parsechangelog/<var>format-name</var></tt>
8943 <tt>/usr/local/lib/dpkg/parsechangelog/<var>format-name</var></tt>;
8944 it is an error for it not to find it, or for it not to
8945 be an executable program. The default changelog format
8946 is <tt>dpkg</tt>, and a parser for it is provided with
8947 the <tt>dpkg</tt> package.
8951 The parser will be invoked with the changelog open on
8952 standard input at the start of the file. It should read
8953 the file (it may seek if it wishes) to determine the
8954 information required and return the parsed information
8955 to standard output in the form of a series of control
8956 fields in the standard format. By default it should
8957 return information about only the most recent version in
8958 the changelog; it should accept a
8959 <tt>-v<var>version</var></tt> option to return changes
8960 information from all versions present <em>strictly
8961 after</em> <var>version</var>, and it should then be an
8962 error for <var>version</var> not to be present in the
8968 <list compact="compact">
8970 <p><qref id="pkg-f-Source"><tt>Source</tt></qref></p>
8973 <p><qref id="versions"><tt>Version</tt></qref> (mandatory)</p>
8977 <qref id="pkg-f-Distribution"><tt>Distribution</tt></qref>
8982 <p><qref id="pkg-f-Urgency"><tt>Urgency</tt></qref> (mandatory)</p>
8986 <qref id="pkg-f-Maintainer"><tt>Maintainer</tt></qref>
8991 <p><qref id="pkg-f-Date"><tt>Date</tt></qref></p>
8995 <qref id="pkg-f-Changes"><tt>Changes</tt></qref>
9002 If several versions are being returned (due to the use
9003 of <tt>-v</tt>), the urgency value should be of the
9004 highest urgency code listed at the start of any of the
9005 versions requested followed by the concatenated
9006 (space-separated) comments from all the versions
9007 requested; the maintainer, version, distribution and
9008 date should always be from the most recent version.
9012 For the format of the <tt>Changes</tt> field see <ref
9013 id="pkg-f-Changes">.
9017 If the changelog format which is being parsed always or
9018 almost always leaves a blank line between individual
9019 change notes these blank lines should be stripped out,
9020 so as to make the resulting output compact.
9024 If the changelog format does not contain date or package
9025 name information this information should be omitted from
9026 the output. The parser should not attempt to synthesise
9027 it or find it from other sources.
9031 If the changelog does not have the expected format the
9032 parser should exit with a nonzero exit status, rather
9033 than trying to muddle through and possibly generating
9038 A changelog parser may not interact with the user at
9042 <sect1 id="pkg-srcsubstvars"><heading><tt>debian/substvars</tt>
9043 and variable substitutions
9047 When <prgn>dpkg-gencontrol</prgn>,
9048 <prgn>dpkg-genchanges</prgn> and <prgn>dpkg-source</prgn>
9049 generate control files they do variable substitutions on
9050 their output just before writing it. Variable
9051 substitutions have the form
9052 <tt>${<var>variable-name</var>}</tt>. The optional file
9053 <tt>debian/substvars</tt> contains variable substitutions
9054 to be used; variables can also be set directly from
9055 <tt>debian/rules</tt> using the <tt>-V</tt> option to the
9056 source packaging commands, and certain predefined
9057 variables are available.
9061 The is usually generated and modified dynamically by
9062 <tt>debian/rules</tt> targets; in this case it must be
9063 removed by the <tt>clean</tt> target.
9067 See <manref name="dpkg-source" section="1"> for full
9068 details about source variable substitutions, including the
9069 format of <tt>debian/substvars</tt>.</p>
9072 <sect1><heading><tt>debian/files</tt>
9076 This file is not a permanent part of the source tree; it
9077 is used while building packages to record which files are
9078 being generated. <prgn>dpkg-genchanges</prgn> uses it
9079 when it generates a <tt>.changes</tt> file.
9083 It should not exist in a shipped source package, and so it
9084 (and any backup files or temporary files such as
9088 <tt>files.new</tt> is used as a temporary file by
9089 <prgn>dpkg-gencontrol</prgn> and
9090 <prgn>dpkg-distaddfile</prgn> - they write a new
9091 version of <tt>files</tt> here before renaming it,
9092 to avoid leaving a corrupted copy if an error
9095 </footnote>) should be removed by the
9096 <tt>clean</tt> target. It may also be wise to
9097 ensure a fresh start by emptying or removing it at the
9098 start of the <tt>binary</tt> target.
9102 <prgn>dpkg-gencontrol</prgn> adds an entry to this file
9103 for the <tt>.deb</tt> file that will be created by
9104 <prgn>dpkg-deb</prgn> from the control file that it
9105 generates, so for most packages all that needs to be done
9106 with this file is to delete it in <tt>clean</tt>.
9110 If a package upload includes files besides the source
9111 package and any binary packages whose control files were
9112 made with <prgn>dpkg-gencontrol</prgn> then they should be
9113 placed in the parent of the package's top-level directory
9114 and <prgn>dpkg-distaddfile</prgn> should be called to add
9115 the file to the list in <tt>debian/files</tt>.</p>
9118 <sect1><heading><tt>debian/tmp</tt>
9122 This is the canonical temporary location for the
9123 construction of binary packages by the <tt>binary</tt>
9124 target. The directory <tt>tmp</tt> serves as the root of
9125 the filesystem tree as it is being constructed (for
9126 example, by using the package's upstream makefiles install
9127 targets and redirecting the output there), and it also
9128 contains the <tt>DEBIAN</tt> subdirectory. See <ref
9129 id="pkg-bincreating">.
9133 If several binary packages are generated from the same
9134 source tree it is usual to use several
9135 <tt>debian/tmp<var>something</var></tt> directories, for
9136 example <tt>tmp-a</tt> or <tt>tmp-doc</tt>.
9140 Whatever <tt>tmp</tt> directories are created and used by
9141 <tt>binary</tt> must of course be removed by the
9142 <tt>clean</tt> target.</p></sect1>
9146 <sect id="pkg-sourcearchives"><heading>Source packages as archives
9150 As it exists on the FTP site, a Debian source package
9151 consists of three related files. You must have the right
9152 versions of all three to be able to use them.
9157 <tag>Debian source control file - <tt>.dsc</tt></tag>
9161 This file contains a series of fields, identified and
9162 separated just like the fields in the control file of
9163 a binary package. The fields are listed below; their
9164 syntax is described above, in <ref id="pkg-controlfields">.
9165 <list compact="compact">
9167 <p><qref id="pkg-f-Source"><tt>Source</tt></qref></p>
9170 <p><qref id="versions"><tt>Version</tt></qref></p>
9173 <p><qref id="pkg-f-Maintainer"><tt>Maintainer</tt></qref></p>
9176 <p><qref id="pkg-f-Binary"><tt>Binary</tt></qref></p>
9179 <p><qref id="pkg-f-Architecture"><tt>Architecture</tt></qref></p>
9183 <qref id="relationships"><tt>Build-Depends</tt> et
9184 al.</qref> (source package interrelationships)
9189 <qref id="pkg-f-Standards-Version"><tt>Standards-Version</tt></qref></p>
9192 <p><qref id="pkg-f-Files"><tt>Files</tt></qref></p>
9197 The source package control file is generated by
9198 <prgn>dpkg-source</prgn> when it builds the source
9199 archive, from other files in the source package,
9200 described above. When unpacking it is checked against
9201 the files and directories in the other parts of the
9202 source package, as described below.</p>
9206 Original source archive -
9208 <var>package</var>_<var>upstream-version</var>.orig.tar.gz
9215 This is a compressed (with <tt>gzip -9</tt>)
9216 <prgn>tar</prgn> file containing the source code from
9217 the upstream authors of the program. The tarfile
9218 unpacks into a directory
9219 <tt><var>package</var>-<var>upstream-version</var>.orig</tt>,
9220 and does not contain files anywhere other than in
9221 there or in its subdirectories.</p>
9225 Debianisation diff -
9227 <var>package</var>_<var>upstream_version-revision</var>.diff.gz
9233 This is a unified context diff (<tt>diff -u</tt>)
9234 giving the changes which are required to turn the
9235 original source into the Debian source. These changes
9236 may only include editing and creating plain files.
9237 The permissions of files, the targets of symbolic
9238 links and the characteristics of special files or
9239 pipes may not be changed and no files may be removed
9244 All the directories in the diff must exist, except the
9245 <tt>debian</tt> subdirectory of the top of the source
9246 tree, which will be created by
9247 <prgn>dpkg-source</prgn> if necessary when unpacking.
9251 The <prgn>dpkg-source</prgn> program will
9252 automatically make the <tt>debian/rules</tt> file
9253 executable (see below).</p></item>
9258 If there is no original source code - for example, if the
9259 package is specially prepared for Debian or the Debian
9260 maintainer is the same as the upstream maintainer - the
9261 format is slightly different: then there is no diff, and the
9263 <tt><var>package</var>_<var>version</var>.tar.gz</tt> and
9264 contains a directory
9265 <tt><var>package</var>-<var>version</var></tt>.
9269 <sect><heading>Unpacking a Debian source package without
9270 <prgn>dpkg-source</prgn>
9274 <tt>dpkg-source -x</tt> is the recommended way to unpack a
9275 Debian source package. However, if it is not available it
9276 is possible to unpack a Debian source archive as follows:
9277 <enumlist compact="compact">
9280 Untar the tarfile, which will create a <tt>.orig</tt>
9284 <p>Rename the <tt>.orig</tt> directory to
9285 <tt><var>package</var>-<var>version</var></tt>.</p>
9289 Create the subdirectory <tt>debian</tt> at the top of
9290 the source tree.</p>
9292 <item><p>Apply the diff using <tt>patch -p0</tt>.</p>
9294 <item><p>Untar the tarfile again if you want a copy of the original
9295 source code alongside the Debianised version.</p>
9300 It is not possible to generate a valid Debian source archive
9301 without using <prgn>dpkg-source</prgn>. In particular,
9302 attempting to use <prgn>diff</prgn> directly to generate the
9303 <tt>.diff.gz</tt> file will not work.
9306 <sect1><heading>Restrictions on objects in source packages
9310 The source package may not contain any hard links
9313 This is not currently detected when building source
9314 packages, but only when extracting
9320 Hard links may be permitted at some point in the
9321 future, but would require a fair amount of
9324 </footnote>, device special files, sockets or setuid or
9328 Setgid directories are allowed.
9334 The source packaging tools manage the changes between the
9335 original and Debianised source using <prgn>diff</prgn> and
9336 <prgn>patch</prgn>. Turning the original source tree as
9337 included in the <tt>.orig.tar.gz</tt> into the debianised
9338 source must not involve any changes which cannot be
9339 handled by these tools. Problematic changes which cause
9340 <prgn>dpkg-source</prgn> to halt with an error when
9341 building the source package are:
9342 <list compact="compact">
9343 <item><p>Adding or removing symbolic links, sockets or pipes.</p>
9345 <item><p>Changing the targets of symbolic links.</p>
9347 <item><p>Creating directories, other than <tt>debian</tt>.</p>
9349 <item><p>Changes to the contents of binary files.</p></item>
9350 </list> Changes which cause <prgn>dpkg-source</prgn> to
9351 print a warning but continue anyway are:
9352 <list compact="compact">
9355 Removing files, directories or symlinks.
9358 Renaming a file is not treated specially - it is
9359 seen as the removal of the old file (which
9360 generates a warning, but is otherwise ignored),
9361 and the creation of the new
9368 Changed text files which are missing the usual final
9369 newline (either in the original or the modified
9374 Changes which are not represented, but which are not detected by
9375 <prgn>dpkg-source</prgn>, are:
9376 <list compact="compact">
9377 <item><p>Changing the permissions of files (other than
9378 <tt>debian/rules</tt>) and directories.</p></item>
9383 The <tt>debian</tt> directory and <tt>debian/rules</tt>
9384 are handled specially by <prgn>dpkg-source</prgn> - before
9385 applying the changes it will create the <tt>debian</tt>
9386 directory, and afterwards it will make
9387 <tt>debian/rules</tt> world-exectuable.
9393 <appendix id="pkg-controlfields"><heading>Control files and their
9394 fields (from old Packaging Manual)
9398 Many of the tools in the <prgn>dpkg</prgn> suite manipulate
9399 data in a common format, known as control files. Binary and
9400 source packages have control data as do the <tt>.changes</tt>
9401 files which control the installation of uploaded files, and
9402 <prgn>dpkg</prgn>'s internal databases are in a similar
9406 <sect><heading>Syntax of control files
9410 A file consists of one or more paragraphs of fields. The
9411 paragraphs are separated by blank lines. Some control files
9412 only allow one paragraph; others allow several, in which
9413 case each paragraph often refers to a different package.
9417 Each paragraph is a series of fields and values; each field
9418 consists of a name, followed by a colon and the value. It
9419 ends at the end of the line. Horizontal whitespace (spaces
9420 and tabs) may occur before or after the value and is ignored
9421 there; it is conventional to put a single space after the
9426 Some fields' values may span several lines; in this case
9427 each continuation line <em>must</em> start with a space or
9428 tab. Any trailing spaces or tabs at the end of individual
9429 lines of a field value are ignored.
9433 Except where otherwise stated only a single line of data is
9434 allowed and whitespace is not significant in a field body.
9435 Whitespace may never appear inside names (of packages,
9436 architectures, files or anything else), version numbers or
9437 in between the characters of multi-character version
9442 Field names are not case-sensitive, but it is usual to
9443 capitalise the field names using mixed case as shown below.
9447 Blank lines, or lines consisting only of spaces and tabs,
9448 are not allowed within field values or between fields - that
9449 would mean a new paragraph.
9453 It is important to note that there are several fields which
9454 are optional as far as <prgn>dpkg</prgn> and the related
9455 tools are concerned, but which must appear in every Debian
9456 package, or whose omission may cause problems. When writing
9457 the control files for Debian packages you <em>must</em> read
9458 the Debian policy manual in conjuction with the details
9459 below and the list of fields for the particular file.</p>
9462 <sect><heading>List of fields
9465 <sect1 id="pkg-f-Package"><heading><tt>Package</tt>
9469 The name of the binary package. Package names consist of
9470 the alphanumerics and <tt>+</tt> <tt>-</tt> <tt>.</tt>
9471 (plus, minus and full stop).
9474 The characters <tt>@</tt> <tt>:</tt> <tt>=</tt>
9475 <tt>%</tt> <tt>_</tt> (at, colon, equals, percent
9476 and underscore) used to be legal and are still
9477 accepted when found in a package file, but may not be
9478 used in new packages
9484 They must be at least two characters and must start with
9485 an alphanumeric. In current versions of dpkg they are
9486 sort of case-sensitive<footnote><p>This is a
9487 bug.</p></footnote>; use lowercase package names unless
9488 the package you're building (or referring to, in other
9489 fields) is already using uppercase.</p>
9492 <sect1 id="pkg-f-Version"><heading><tt>Version</tt>
9496 This lists the source or binary package's version number -
9497 see <ref id="versions">.
9502 <sect1 id="pkg-f-Architecture"><heading><tt>Architecture</tt>
9506 This is the architecture string; it is a single word for
9507 the Debian architecture.
9511 <prgn>dpkg</prgn> will check the declared architecture of
9512 a binary package against its own compiled-in value before
9517 The special value <tt>all</tt> indicates that the package
9518 is architecture-independent.
9522 In the main <tt>debian/control</tt> file in the source
9523 package, or in the source package control file
9524 <tt>.dsc</tt>, a list of architectures (separated by
9525 spaces) is also allowed, as is the special value
9526 <tt>any</tt>. A list indicates that the source will build
9527 an architecture-dependent package, and will only work
9528 correctly on the listed architectures. <tt>any</tt>
9529 indicates that though the source package isn't dependent
9530 on any particular architecture and should compile fine on
9531 any one, the binary package(s) produced are not
9532 architecture-independent but will instead be specific to
9533 whatever the current build architecture is.
9537 In a <tt>.changes</tt> file the <tt>Architecture</tt>
9538 field lists the architecture(s) of the package(s)
9539 currently being uploaded. This will be a list; if the
9540 source for the package is being uploaded too the special
9541 entry <tt>source</tt> is also present.
9545 See <ref id="pkg-debianrules"> for information how to get the
9546 architecture for the build process.
9550 <sect1 id="pkg-f-Maintainer"><heading><tt>Maintainer</tt>
9554 The package maintainer's name and email address. The name
9555 should come first, then the email address inside angle
9556 brackets <tt><></tt> (in RFC822 format).
9560 If the maintainer's name contains a full stop then the
9561 whole field will not work directly as an email address due
9562 to a misfeature in the syntax specified in RFC822; a
9563 program using this field as an address must check for this
9564 and correct the problem if necessary (for example by
9565 putting the name in round brackets and moving it to the
9566 end, and bringing the email address forward).
9570 In a <tt>.changes</tt> file or parsed changelog data this
9571 contains the name and email address of the person
9572 responsible for the particular version in question - this
9573 may not be the package's usual maintainer.
9577 This field is usually optional in as far as the
9578 <prgn>dpkg</prgn> are concerned, but its absence when
9579 building packages usually generates a warning.</p>
9582 <sect1 id="pkg-f-Source"><heading><tt>Source</tt>
9586 This field identifies the source package name.
9590 In a main source control information or a
9591 <tt>.changes</tt> or <tt>.dsc</tt> file or parsed
9592 changelog data this may contain only the name of the
9597 In the control file of a binary package (or in a
9598 <tt>Packages</tt> file) it may be followed by a version
9599 number in parentheses.
9602 It is usual to leave a space after the package name if
9603 a version number is specified.
9605 </footnote> This version number may be omitted (and is, by
9606 <prgn>dpkg-gencontrol</prgn>) if it has the same value as
9607 the <tt>Version</tt> field of the binary package in
9608 question. The field itself may be omitted from a binary
9609 package control file when the source package has the same
9610 name and version as the binary package.
9614 <sect1><heading>Package interrelationship fields:
9615 <tt>Depends</tt>, <tt>Pre-Depends</tt>,
9616 <tt>Recommends</tt> <tt>Suggests</tt>, <tt>Conflicts</tt>,
9617 <tt>Provides</tt>, <tt>Replaces</tt>
9621 These fields describe the package's relationships with
9622 other packages. Their syntax and semantics are described
9623 in <ref id="relationships">.</p>
9626 <sect1 id="pkg-f-Description"><heading><tt>Description</tt>
9630 In a binary package <tt>Packages</tt> file or main source
9631 control file this field contains a description of the
9632 binary package, in a special format. See <ref
9633 id="descriptions"> for details.
9637 In a <tt>.changes</tt> file it contains a summary of the
9638 descriptions for the packages being uploaded. The part of
9639 the field before the first newline is empty; thereafter
9640 each line has the name of a binary package and the summary
9641 description line from that binary package. Each line is
9642 indented by one space.</p>
9645 <sect1 id="pkg-f-Essential"><heading><tt>Essential</tt>
9649 This is a boolean field which may occur only in the
9650 control file of a binary package (or in the
9651 <tt>Packages</tt> file) or in a per-package fields
9652 paragraph of a main source control data file.
9656 If set to <tt>yes</tt> then <prgn>dpkg</prgn> and
9657 <prgn>dselect</prgn> will refuse to remove the package
9658 (though it can be upgraded and/or replaced). The other
9659 possible value is <tt>no</tt>, which is the same as not
9660 having the field at all.</p>
9663 <sect1 id="pkg-f-classification"><heading><tt>Section</tt> and
9668 These two fields classify the package. The
9669 <tt>Priority</tt> represents how important that it is that
9670 the user have it installed; the <tt>Section</tt>
9671 represents an application area into which the package has
9676 When they appear in the <tt>debian/control</tt> file these
9677 fields give values for the section and priority subfields
9678 of the <tt>Files</tt> field of the <tt>.changes</tt> file,
9679 and give defaults for the section and priority of the
9684 The section and priority are represented, though not as
9685 separate fields, in the information for each file in the
9686 <qref id="pkg-f-Files"><tt>-File</tt></qref>field of a
9687 <tt>.changes</tt> file. The section value in a
9688 <tt>.changes</tt> file is used to decide where to install
9689 a package in the FTP archive.
9693 These fields are not used by by <prgn>dpkg</prgn> proper,
9694 but by <prgn>dselect</prgn> when it sorts packages and
9695 selects defaults. See the Debian policy manual for the
9696 priorities in use and the criteria for selecting the
9697 priority for a Debian package, and look at the Debian FTP
9698 archive for a list of currently in-use priorities.
9702 These fields may appear in binary package control files,
9703 in which case they provide a default value in case the
9704 <tt>Packages</tt> files are missing the information.
9705 <prgn>dpkg</prgn> and <prgn>dselect</prgn> will only use
9706 the value from a <tt>.deb</tt> file if they have no other
9707 information; a value listed in a <tt>Packages</tt> file
9708 will always take precedence. By default
9709 <prgn>dpkg-gencontrol</prgn> does not include the section
9710 and priority in the control file of a binary package - use
9711 the <tt>-isp</tt>, <tt>-is</tt> or <tt>-ip</tt> options to
9712 achieve this effect.</p>
9715 <sect1 id="pkg-f-Binary"><heading><tt>Binary</tt>
9719 This field is a list of binary packages.
9723 When it appears in the <tt>.dsc</tt> file it is the list
9724 of binary packages which a source package can produce. It
9725 does not necessarily produce all of these binary packages
9726 for every architecture. The source control file doesn't
9727 contain details of which architectures are appropriate for
9728 which of the binary packages.
9732 When it appears in a <tt>.changes</tt> file it lists the
9733 names of the binary packages actually being uploaded.
9737 The syntax is a list of binary packages separated by
9741 A space after each comma is conventional.
9743 </footnote> Currently the packages must be separated using
9744 only spaces in the <tt>.changes</tt> file.</p>
9747 <sect1 id="pkg-f-Installed-Size"><heading><tt>Installed-Size</tt>
9751 This field appears in the control files of binary
9752 packages, and in the <tt>Packages</tt> files. It gives
9753 the total amount of disk space required to install the
9758 The disk space is represented in kilobytes as a simple
9762 <sect1 id="pkg-f-Files"><heading><tt>Files</tt>
9766 This field contains a list of files with information about
9767 each one. The exact information and syntax varies with
9768 the context. In all cases the the part of the field
9769 contents on the same line as the field name is empty. The
9770 remainder of the field is one line per file, each line
9771 being indented by one space and containing a number of
9772 sub-fields separated by spaces.
9776 In the <tt>.dsc</tt> (Debian source control) file each
9777 line contains the MD5 checksum, size and filename of the
9778 tarfile and (if applicable) diff file which make up the
9779 remainder of the source package.
9782 That is, the parts which are not the
9785 </footnote> The exact forms of the filenames are described
9786 in <ref id="pkg-sourcearchives">.
9790 In the <tt>.changes</tt> file this contains one line per
9791 file being uploaded. Each line contains the MD5 checksum,
9792 size, section and priority and the filename. The section
9793 and priority are the values of the corresponding fields in
9794 the main source control file - see <ref
9795 id="pkg-f-classification">. If no section or priority is
9796 specified then <tt>-</tt> should be used, though section
9797 and priority values must be specified for new packages to
9798 be installed properly.
9802 The special value <tt>byhand</tt> for the section in a
9803 <tt>.changes</tt> file indicates that the file in question
9804 is not an ordinary package file and must by installed by
9805 hand by the distribution maintainers. If the section is
9806 <tt>byhand</tt> the priority should be <tt>-</tt>.
9810 If a new Debian revision of a package is being shipped and
9811 no new original source archive is being distributed the
9812 <tt>.dsc</tt> must still contain the <tt>Files</tt> field
9813 entry for the original source archive
9814 <tt><var>package</var>-<var>upstream-version</var>.orig.tar.gz</tt>,
9815 but the <tt>.changes</tt> file should leave it out. In
9816 this case the original source archive on the distribution
9817 site must match exactly, byte-for-byte, the original
9818 source archive which was used to generate the
9819 <tt>.dsc</tt> file and diff which are being uploaded.</p>
9824 id="pkg-f-Standards-Version"><heading><tt>Standards-Version</tt>
9828 The most recent version of the standards (the
9829 <prgn>dpkg</prgn> programmers' and policy manuals and
9830 associated texts) with which the package complies. This
9831 is updated manually when editing the source package to
9832 conform to newer standards; it can sometimes be used to
9833 tell when a package needs attention.
9837 Its format is the same as that of a version number except
9838 that no epoch or Debian revision is allowed - see <ref
9843 <sect1 id="pkg-f-Distribution"><heading><tt>Distribution</tt>
9847 In a <tt>.changes</tt> file or parsed changelog output
9848 this contains the (space-separated) name(s) of the
9849 distribution(s) where this version of the package should
9850 be or was installed. Distribution names follow the rules
9851 for package names. (See <ref id="pkg-f-Package">).
9855 Current distribution values are:
9857 <tag><em>stable</em></tag>
9860 This is the current `released' version of Debian
9861 GNU/Linux. A new version is released approximately
9862 every 3 months after the <em>development</em> code has
9863 been <em>frozen</em> for a month of testing. Once the
9864 distribution is <em>stable</em> only major bug fixes
9865 are allowed. When changes are made to this
9866 distribution, the release number is increased
9867 (for example: 1.2r1 becomes 1.2r2 then 1.2r3, etc).
9871 <tag><em>unstable</em></tag>
9874 This distribution value refers to the
9875 <em>developmental</em> part of the Debian distribution
9876 tree. New packages, new upstream versions of packages
9877 and bug fixes go into the <em>unstable</em> directory
9878 tree. Download from this distribution at your own
9882 <tag><em>contrib</em></tag>
9885 The packages with this distribution value do not meet
9886 the criteria for inclusion in the main Debian
9887 distribution as defined by the Policy Manual, but meet
9888 the criteria for the <em>contrib</em>
9889 Distribution. There is currently no distinction
9890 between stable and unstable packages in the
9891 <em>contrib</em> or <em>non-free</em>
9892 distributions. Use your best judgement in downloading
9893 from this Distribution.</p>
9896 <tag><em>non-free</em></tag>
9899 Like the packages in the <em>contrib</em> seciton,
9900 the packages in <em>non-free</em> do not meet the
9901 criteria for inclusion in the main Debian distribution
9902 as defined by the Policy Manual. Again, use your best
9903 judgement in downloading from this Distribution.</p>
9905 <tag><em>experimental</em></tag>
9908 The packages with this distribution value are deemed
9909 by their maintainers to be high risk. Oftentimes they
9910 represent early beta or developmental packages from
9911 various sources that the maintainers want people to
9912 try, but are not ready to be a part of the other parts
9913 of the Debian distribution tree. Download at your own
9917 <tag><em>frozen</em></tag>
9920 From time to time, (currently, every 3 months) the
9921 <em>unstable</em> distribution enters a state of
9922 `code-freeze' in anticipation of release as a
9923 <em>stable</em> version. During this period of testing
9924 (usually 4 weeks) only fixes for existing or
9925 newly-discovered bugs will be allowed.
9928 </taglist> You should list <em>all</em> distributions that
9929 the package should be installed into. Except in unusual
9930 circumstances, installations to <em>stable</em> should also
9931 go into <em>frozen</em> (if it exists) and
9932 <em>unstable</em>. Likewise, installations into
9933 <em>frozen</em> should also go into <em>unstable</em>.</p>
9936 <sect1 id="pkg-f-Urgency"><heading><tt>Urgency</tt>
9940 This is a description of how important it is to upgrade to
9941 this version from previous ones. It consists of a single
9942 keyword usually taking one of the values <tt>LOW</tt>,
9943 <tt>MEDIUM</tt> or <tt>HIGH</tt>) followed by an optional
9944 commentary (separated by a space) which is usually in
9945 parentheses. For example:
9947 Urgency: LOW (HIGH for diversions users)
9952 This field appears in the <tt>.changes</tt> file and in
9953 parsed changelogs; its value appears as the value of the
9954 <tt>urgency</tt> attribute in a <prgn>dpkg</prgn>-style
9955 changelog (see <ref id="pkg-dpkgchangelog">).
9959 Urgency keywords are not case-sensitive.</p>
9962 <sect1 id="pkg-f-Date"><heading><tt>Date</tt>
9966 In <tt>.changes</tt> files and parsed changelogs, this
9967 gives the date the package was built or last edited.</p>
9970 <sect1 id="pkg-f-Format"><heading><tt>Format</tt>
9974 This field occurs in <tt>.changes</tt> files, and
9975 specifies a format revision for the file. The format
9976 described here is version <tt>1.5</tt>. The syntax of the
9977 format value is the same as that of a package version
9978 number except that no epoch or Debian revision is allowed
9979 - see <ref id="versions">.</p>
9982 <sect1 id="pkg-f-Changes"><heading><tt>Changes</tt>
9986 In a <tt>.changes</tt> file or parsed changelog this field
9987 contains the human-readable changes data, describing the
9988 differences between the last version and the current one.
9992 There should be nothing in this field before the first
9993 newline; all the subsequent lines must be indented by at
9994 least one space; blank lines must be represented by a line
9995 consiting only of a space and a full stop.
9999 Each version's change information should be preceded by a
10000 `title' line giving at least the version, distribution(s)
10001 and urgency, in a human-readable way.
10005 If data from several versions is being returned the entry
10006 for the most recent version should be returned first, and
10007 entries should be separated by the representation of a
10008 blank line (the `title' line may also be followed by the
10009 representation of blank line).</p>
10012 <sect1 id="pkg-f-Filename"><heading><tt>Filename</tt> and
10013 <tt>MSDOS-Filename</tt>
10017 These fields in <tt>Packages</tt> files give the
10018 filename(s) of (the parts of) a package in the
10019 distribution directories, relative to the root of the
10020 Debian hierarchy. If the package has been split into
10021 several parts the parts are all listed in order, separated
10025 <sect1 id="pkg-f-Size"><heading><tt>Size</tt> and <tt>MD5sum</tt>
10029 These fields in <tt>Packages</tt> files give the size (in
10030 bytes, expressed in decimal) and MD5 checksum of the
10031 file(s) which make(s) up a binary package in the
10032 distribution. If the package is split into several parts
10033 the values for the parts are listed in order, separated by
10037 <sect1 id="pkg-f-Status"><heading><tt>Status</tt>
10041 This field in <prgn>dpkg</prgn>'s status file records
10042 whether the user wants a package installed, removed or
10043 left alone, whether it is broken (requiring
10044 reinstallation) or not and what its current state on the
10045 system is. Each of these pieces of information is a
10049 <sect1 id="pkg-f-Config-Version"><heading><tt>Config-Version</tt>
10053 If a package is not installed or not configured, this
10054 field in <prgn>dpkg</prgn>'s status file records the last
10055 version of the package which was successfully
10059 <sect1 id="pkg-f-Conffiles"><heading><tt>Conffiles</tt>
10063 This field in <prgn>dpkg</prgn>'s status file contains
10064 information about the automatically-managed configuration
10065 files held by a package. This field should <em>not</em>
10066 appear anywhere in a package!</p>
10069 <sect1><heading>Obsolete fields
10073 These are still recognised by <prgn>dpkg</prgn> but should
10074 not appear anywhere any more.
10075 <taglist compact="compact">
10077 <tag><tt>Revision</tt></tag>
10078 <tag><tt>Package-Revision</tt></tag>
10079 <tag><tt>Package_Revision</tt></tag>
10082 The Debian revision part of the package version was
10083 at one point in a separate control file field. This
10084 field went through several names.</p>
10087 <tag><tt>Recommended</tt></tag>
10088 <item><p>Old name for <tt>Recommends</tt></p>
10091 <tag><tt>Optional</tt></tag>
10092 <item><p>Old name for <tt>Suggests</tt>.</p>
10094 <tag><tt>Class</tt></tag>
10095 <item><p>Old name for <tt>Priority</tt>.</p>
10103 <appendix id="pkg-conffiles"><heading>Configuration file handling
10104 (from old Packaging Manual)
10108 <prgn>dpkg</prgn> can do a certain amount of automatic
10109 handling of package configuration files.
10113 Whether this mechanism is appropriate depends on a number of
10114 factors, but basically there are two approaches to any
10115 particular configuration file.
10119 The easy method is to ship a best-effort configuration in the
10120 package, and use <prgn>dpkg</prgn>'s conffile mechanism to
10121 handle updates. If the user is unlikely to want to edit the
10122 file, but you need them to be able to without losing their
10123 changes, and a new package with a changed version of the file
10124 is only released infrequently, this is a good approach.
10128 The hard method is to build the configuration file from
10129 scratch in the <prgn>postinst</prgn> script, and to take the
10130 responsibility for fixing any mistakes made in earlier
10131 versions of the package automatically. This will be
10132 appropriate if the file is likely to need to be different on
10136 <sect><heading>Automatic handling of configuration files by
10141 A package may contain a control area file called
10142 <tt>conffiles</tt>. This file should be a list of filenames
10143 of configuration files needing automatic handling, separated
10144 by newlines. The filenames should be absolute pathnames,
10145 and the files referred to should actually exist in the
10150 When a package is upgraded <prgn>dpkg</prgn> will process
10151 the configuration files during the configuration stage,
10152 shortly before it runs the package's <prgn>postinst</prgn>
10157 For each file it checks to see whether the version of the
10158 file included in the package is the same as the one that was
10159 included in the last version of the package (the one that is
10160 being upgraded from); it also compares the version currently
10161 installed on the system with the one shipped with the last
10166 If neither the user nor the package maintainer has changed
10167 the file, it is left alone. If one or the other has changed
10168 their version, then the changed version is preferred - i.e.,
10169 if the user edits their file, but the package maintainer
10170 doesn't ship a different version, the user's changes will
10171 stay, silently, but if the maintainer ships a new version
10172 and the user hasn't edited it the new version will be
10173 installed (with an informative message). If both have
10174 changed their version the user is prompted about the problem
10175 and must resolve the differences themselves.
10179 The comparisons are done by calculating the MD5 message
10180 digests of the files, and storing the MD5 of the file as it
10181 was included in the most recent version of the package.
10185 When a package is installed for the first time
10186 <prgn>dpkg</prgn> will install the file that comes with it,
10187 unless that would mean overwriting a file already on the
10192 However, note that <prgn>dpkg</prgn> will <em>not</em>
10193 replace a conffile that was removed by the user (or by a
10194 script). This is necessary because with some programs a
10195 missing file produces an effect hard or impossible to
10196 achieve in another way, so that a missing file needs to be
10197 kept that way if the user did it.
10201 Note that a package should <em>not</em> modify a
10202 <prgn>dpkg</prgn>-handled conffile in its maintainer
10203 scripts. Doing this will lead to <prgn>dpkg</prgn> giving
10204 the user confusing and possibly dangerous options for
10205 conffile update when the package is upgraded.</p>
10208 <sect><heading>Fully-featured maintainer script configuration
10213 For files which contain site-specific information such as
10214 the hostname and networking details and so forth, it is
10215 better to create the file in the package's
10216 <prgn>postinst</prgn> script.
10220 This will typically involve examining the state of the rest
10221 of the system to determine values and other information, and
10222 may involve prompting the user for some information which
10223 can't be obtained some other way.
10227 When using this method there are a couple of important
10228 issues which should be considered:
10232 If you discover a bug in the program which generates the
10233 configuration file, or if the format of the file changes
10234 from one version to the next, you will have to arrange for
10235 the postinst script to do something sensible - usually this
10236 will mean editing the installed configuration file to remove
10237 the problem or change the syntax. You will have to do this
10238 very carefully, since the user may have changed the file,
10239 perhaps to fix the very problem that your script is trying
10240 to deal with - you will have to detect these situations and
10241 deal with them correctly.
10245 If you do go down this route it's probably a good idea to
10246 make the program that generates the configuration file(s) a
10247 separate program in <tt>/usr/sbin</tt>, by convention called
10248 <tt><var>package</var>config</tt> and then run that if
10249 appropriate from the post-installation script. The
10250 <tt><var>package</var>config</tt> program should not
10251 unquestioningly overwrite an existing configuration - if its
10252 mode of operation is geared towards setting up a package for
10253 the first time (rather than any arbitrary reconfiguration
10254 later) you should have it check whether the configuration
10255 already exists, and require a <tt>--force</tt> flag to
10256 overwrite it.</p></sect>
10259 <appendix id="pkg-alternatives"><heading>Alternative versions of
10260 an interface - <prgn>update-alternatives</prgn> (from old
10265 When several packages all provide different versions of the
10266 same program or file it is useful to have the system select a
10267 default, but to allow the system administrator to change it
10268 and have their decisions respected.
10272 For example, there are several versions of the <prgn>vi</prgn>
10273 editor, and there is no reason to prevent all of them from
10274 being installed at once, each under their own name
10275 (<prgn>nvi</prgn>, <prgn>vim</prgn> or whatever).
10276 Nevertheless it is desirable to have the name <tt>vi</tt>
10277 refer to something, at least by default.
10281 If all the packages involved cooperate, this can be done with
10282 <prgn>update-alternatives</prgn>.
10286 Each package provides its own version under its own name, and
10287 calls <prgn>update-alternatives</prgn> in its postinst to
10288 register its version (and again in its prerm to deregister
10293 See the manpage <manref name="update-alternatives"
10294 section="8"> for details.
10298 If <prgn>update-alternatives</prgn> does not seem appropriate
10299 you may wish to consider using diversions instead.</p>
10302 <appendix id="pkg-diversions"><heading>Diversions - overriding a
10303 package's version of a file (from old Packaging Manual)
10307 It is possible to have <prgn>dpkg</prgn> not overwrite a file
10308 when it reinstalls the package it belongs to, and to have it
10309 put the file from the package somewhere else instead.
10313 This can be used locally to override a package's version of a
10314 file, or by one package to override another's version (or
10315 provide a wrapper for it).
10319 Before deciding to use a diversion, read <ref
10320 id="pkg-alternatives"> to see if you really want a diversion
10321 rather than several alternative versions of a program.
10325 There is a diversion list, which is read by <prgn>dpkg</prgn>,
10326 and updated by a special program <prgn>dpkg-divert</prgn>.
10327 Please see <manref name="dpkg-divert" section="8"> for full
10328 details of its operation.
10332 When a package wishes to divert a file from another, it should
10333 call <prgn>dpkg-divert</prgn> in its preinst to add the
10334 diversion and rename the existing file. For example,
10335 supposing that a <prgn>smailwrapper</prgn> package wishes to
10336 install a wrapper around <tt>/usr/sbin/smail</tt>:
10338 if [ install = "$1" -o upgrade = "$1" ]; then
10339 dpkg-divert --package smailwrapper --add --rename \
10340 --divert /usr/sbin/smail.real /usr/sbin/smail
10342 </example> Testing <tt>$1</tt> is necessary so that the script
10343 doesn't try to add the diversion again when
10344 <prgn>smailwrapper</prgn> is upgraded. The <tt>--package
10345 smailwrapper</tt> ensures that <prgn>smailwrapper</prgn>'s
10346 copy of <tt>/usr/sbin/smail</tt> can bypass the diversion and
10347 get installed as the true version.
10351 The postrm has to do the reverse:
10353 if [ remove = "$1" ]; then
10354 dpkg-divert --package smailwrapper --remove --rename \
10355 --divert /usr/sbin/smail.real /usr/sbin/smail
10361 Do not attempt to divert a file which is vitally important for
10362 the system's operation - when using <prgn>dpkg-divert</prgn>
10363 there is a time, after it has been diverted but before
10364 <prgn>dpkg</prgn> has installed the new version, when the file
10365 does not exist.</p>