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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.
770 <tag><tt>optional</tt></tag>
773 (In a sense everything that isn't required is
774 optional, but that's not what is meant here.) This is
775 all the software that you might reasonably want to
776 install if you didn't know what it was and don't have
777 specialized requirements. This is a much larger system
778 and includes the X Window System, a full TeX
779 distribution, and many applications. Note that
780 optional packages should not conflict with each other.
783 <tag><tt>extra</tt></tag>
786 This contains all packages that conflict with others
787 with required, important, standard or optional
788 priorities, or are only likely to be useful if you
789 already know what they are or have specialised
796 Packages must not depend on packages with lower priority
797 values (excluding build-time dependencies). In order to
798 ensure this, the priorities of one or more packages may need
804 <heading>Binary packages</heading>
807 The Debian GNU/Linux distribution is based on the Debian
808 package management system, called <prgn>dpkg</prgn>. Thus,
809 all packages in the Debian distribution must be provided
810 in the <tt>.deb</tt> file format.</p>
814 <heading>The package name</heading>
817 Every package must have a name that's unique within the Debian
821 Package names must consist of lower case letters
822 (<tt>a-z</tt>), digits (<tt>0-9</tt>), plus (<tt>+</tt>)
823 and minus (<tt>-</tt>) signs, and periods (<tt>.</tt>).
824 They must be at least two characters long and must contain
829 The package name is part of the file name of the
830 <tt>.deb</tt> file and is included in the control field
836 <heading>The maintainer of a package</heading>
838 Every package must have a Debian maintainer (the
839 maintainer may be one person or a group of people
840 reachable from a common email address, such as a mailing
841 list). The maintainer is responsible for ensuring that
842 the package is placed in the appropriate distributions.
846 The maintainer must be specified in the
847 <tt>Maintainer</tt> control field with their correct name
848 and a working email address. If one person maintains
849 several packages, he/she should try to avoid having
850 different forms of their name and email address in
851 the <tt>Maintainer</tt> fields of those packages.
855 If the maintainer of a package quits from the Debian
856 project, "Debian QA Group"
857 <email>packages@qa.debian.org</email> takes over the
858 maintainership of the package until someone else
859 volunteers for that task. These packages are called
860 <em>orphaned packages</em>.<footnote>
862 The detailed procedure for doing this gracefully can
863 be found in the Debian Developer's Reference, either
864 in the <tt>developers-reference</tt> package, or on
865 the Debian FTP server
866 <ftpsite>ftp.debian.org</ftpsite> as
867 <ftppath>/debian/doc/package-developer/developers-reference.txt.gz</ftppath>
869 id="http://www.debian.org/doc/packaging-manuals/developers-reference/"
870 name="Debian Developer's Reference"> webpage.
878 <heading>The description of a package</heading>
881 Every Debian package must have an extended description
882 stored in the appropriate field of the control record.</p>
885 The description should be written so that it gives the
886 system administrator enough information to decide whether
887 to install the package. This description should not just
888 be copied verbatim from the program's documentation.
889 Instructions for configuring or using the package should
890 not be included (that is what installation scripts,
891 manual pages, info files, etc., are for). Copyright
892 statements and other administrivia should not be included
893 either (that is what the copyright file is for).
899 <heading>Dependencies</heading>
902 Every package must specify the dependency information
903 about other packages that are required for the first to
907 For example, a dependency entry must be provided for any
908 shared libraries required by a dynamically-linked executable
909 binary in a package.</p>
912 Packages are not required to declare any dependencies they
913 have on other packages which are marked <tt>Essential</tt>
914 (see below), and should not do so unless they depend on a
915 particular version of that package.</p>
918 Sometimes, a package requires another package to be installed
919 <em>and</em> configured before it can be installed. In this
920 case, you must specify a <tt>Pre-Depends</tt> entry for
924 You should not specify a <tt>Pre-Depends</tt> entry for a
925 package before this has been discussed on the
926 <tt>debian-devel</tt> mailing list and a consensus about
927 doing that has been reached.</p></sect1>
931 <heading>Virtual packages</heading>
934 Sometimes, there are several packages which offer
935 more-or-less the same functionality. In this case, it's
936 useful to define a <em>virtual package</em> whose name
937 describes that common functionality. (The virtual
938 packages only exist logically, not physically; that's why
939 they are called <em>virtual</em>.) The packages with this
940 particular function will then <em>provide</em> the virtual
941 package. Thus, any other package requiring that function
942 can simply depend on the virtual package without having to
943 specify all possible packages individually.</p>
946 All packages should use virtual package names where
947 appropriate, and arrange to create new ones if necessary.
948 They should not use virtual package names (except privately,
949 amongst a cooperating group of packages) unless they have
950 been agreed upon and appear in the list of virtual package
954 The latest version of the authoritative list of virtual
955 package names can be found on
956 <ftpsite>ftp.debian.org</ftpsite> in
957 <ftppath>/debian/doc/package-developer/virtual-package-names-list.txt</ftppath>
958 or your local mirror. In addition, it is included in the
959 <tt>debian-policy</tt> package. The procedure for updating
960 the list is described at the top of the file.</p></sect1>
964 <heading>Base packages</heading>
967 The packages included in the <tt>base</tt> section have a
968 special function. They form a minimum subset of the Debian
969 GNU/Linux system that is installed before everything else
970 on a new system. Thus, only very few packages are allowed
971 to go into the <tt>base</tt> section to keep the required
972 disk usage very small.</p>
975 Most of these packages will have the priority value
976 <tt>required</tt> or at least <tt>important</tt>, and many
977 of them will be tagged <tt>essential</tt> (see below).</p>
980 You must not place any packages into the <tt>base</tt>
981 section before this has been discussed on the
982 <tt>debian-devel</tt> mailing list and a consensus about
983 doing that has been reached.</p></sect1>
987 <heading>Essential packages</heading>
990 Some packages are tagged <tt>essential</tt>. (They have
991 <tt>Essential: yes</tt> in their package control record.)
992 This flag is used for packages that are <em>essential</em>
996 Since these packages cannot be easily removed (one has to
997 specify an extra <em>force option</em> to
998 <prgn>dpkg</prgn> to do so), this flag must not be used
999 unless absolutely necessary. A shared library package
1000 must not be tagged <tt>essential</tt>; dependencies will
1001 prevent its premature removal, and we need to be able to
1002 remove it when it has been superseded.
1006 Since dpkg will not prevent upgrading of other packages
1007 while an <tt>essential</tt> package is in an unconfigured
1008 state, all <tt>essential</tt> packages must supply all of
1009 their core functionality even when unconfigured. If the
1010 package cannot satisfy this requirement it must not be
1011 tagged as essential, and any packages depending on this
1012 package must instead have explicit dependency fields as
1017 You must not tag any packages <tt>essential</tt> before
1018 this has been discussed on the <tt>debian-devel</tt>
1019 mailing list and a consensus about doing that has been
1024 <sect1 id="maintscripts">
1025 <heading>Maintainer scripts</heading>
1028 The package installation scripts should avoid producing
1029 output which it is unnecessary for the user to see and
1030 should rely on <prgn>dpkg</prgn> to stave off boredom on
1031 the part of a user installing many packages. This means,
1032 amongst other things, using the <tt>--quiet</tt> option on
1033 <prgn>install-info</prgn>.</p>
1036 Errors which occur during the execution of an installation
1037 script must be checked and the installation must not
1038 continue after an error.
1042 Note that in general <ref id="scripts"> applies to package
1043 maintainer scripts, too.
1047 You should not use <tt>dpkg-divert</tt> on a file
1048 belonging to another package without consulting the
1049 maintainer of that package first.
1053 All packages which supply an instance of a common command
1054 name (or, in general, filename) should generally use
1055 <prgn>update-alternatives</prgn>, so that they may be
1056 installed together. If <prgn>update-alternatives</prgn>
1057 is not used, then each package must use
1058 <tt>Conflicts</tt> to ensure that other packages are
1059 de-installed. (In this case, it may be appropriate to
1060 specify a conflict against earlier versions of something
1061 that previously did not use
1062 <prgn>update-alternatives</prgn>; this is an exception to
1063 the usual rule that versioned conflicts should be
1069 <heading>Prompting in maintainer scripts</heading>
1071 Package maintainer scripts may prompt the user if
1072 necessary. Prompting may be accomplished by hand, or by
1073 communicating with a program, such as
1074 <prgn>debconf</prgn>, which conforms to the Debian
1075 Configuration management specification, version 2 or
1076 higher. These are included in the
1077 <tt>debconf_specification</tt> files in the
1078 <package>debian-policy</package> package.
1079 You may also find this file on the FTP site
1080 <ftpsite>ftp.debian.org</ftpsite> in
1081 <ftppath>/debian/doc/package-developer/debconf_specification.txt.gz</ftppath>
1082 or on your local mirror.<footnote>
1084 4% of Debian packages [see <url
1085 id="http://kitenet.net/programs/debconf/stats/"
1086 name="Debconf stats">] currently use
1087 <package>debconf</package> to prompt the user at
1088 install time, and this number is growing daily. The
1089 benefits of using debconf are briefly explained at
1091 id="http://kitenet.net/doc/debconf-doc/introduction.html"
1092 name="Debconf introduction">; they include
1093 preconfiguration, (mostly) noninteractive
1094 installation, elimination of redundant prompting,
1095 consistency of user interface, etc.
1098 With this increasing number of packages using
1099 <package>debconf</package>, plus the existance of a
1100 nascent second implementation of the Debian
1101 configuration management system
1102 (<package>cdebconf</package>), and the stabalization
1103 of the protocol these things use, the time has
1104 finally come to reflect the use of these things in
1111 Packages which use the Debian Configuration management
1112 specification may contain an additional
1113 <prgn>config</prgn> script and a <tt>templates</tt>
1114 file in their control archive. The <prgn>config</prgn>
1115 script might be run before the <prgn>preinst</prgn>
1116 script, and before the package is unpacked or any of its
1117 dependancies or pre-dependancies are satisfied.
1118 Therefore it must work using only the tools present in
1119 <em>essential</em> packages.<footnote>
1121 <package>Debconf</package> or another tool that
1122 implements the Debian Configuration management
1123 specification will also be installed, and any
1124 versioned dependencies on it will be satisfied
1125 before preconfiguration begins.
1131 Packages should try to minimize the amount of prompting
1132 they need to do, and they should ensure that the user
1133 will only ever be asked each question once. This means
1134 that packages should try to use appropriate shared
1135 configuration files (such as <tt>/etc/papersize</tt> and
1136 <tt>/etc/news/server</tt>), and shared
1137 <package>debconf</package> variables rather than each
1138 prompting for their own list of required pieces of
1143 It also means that an upgrade should not ask the same
1144 questions again, unless the user has used <tt>dpkg
1145 --purge</tt> to remove the package's configuration. The
1146 answers to configuration questions should be stored in an
1147 appropriate place in <tt>/etc</tt> so that the user can
1148 modify them, and how this has been done should be
1152 If a package has a vitally important piece of
1153 information to pass to the user (such as "don't run me
1154 as I am, you must edit the following configuration files
1155 first or you risk your system emitting badly-formatted
1156 messages"), it should display this in the
1157 <prgn>config</prgn> or <prgn>postinst</prgn> script and
1158 prompt the user to hit return to acknowledge the
1159 message. Copyright messages do not count as vitally
1160 important (they belong in
1161 <tt>/usr/share/doc/<var>package</var>/copyright</tt>);
1162 neither do instructions on how to use a program (these
1163 should be in on-line documentation, where all the users
1167 Any necessary prompting should almost always be confined
1168 to the <prgn>config</prgn> or <prgn>postinst</prgn>
1169 script. If it is done in the <prgn>postinst</prgn>, it
1170 should be protected with a conditional so that
1171 unnecessary prompting doesn't happen if a package's
1172 installation fails and the <prgn>postinst</prgn> is
1173 called with <tt>abort-upgrade</tt>,
1174 <tt>abort-remove</tt> or <tt>abort-deconfigure</tt>.</p>
1179 <heading>Source packages</heading>
1181 <sect1 id="standardsversion">
1182 <heading>Standards conformance</heading>
1185 In the source package's <tt>Standards-Version</tt> control
1186 field, you should specify the most recent version number
1187 of this policy document with which your package complied
1188 when it was last updated. The current version number is
1193 This information may be used to file bug reports
1194 automatically if your package becomes too much out of
1199 The version number has four components: major and minor
1200 version number and major and minor patch level. When the
1201 standards change in a way that requires every package to
1202 change the major number will be changed. Significant
1203 changes that will require work in many packages will be
1204 signaled by a change to the minor number. The major patch
1205 level will be changed for any change to the meaning of the
1206 standards, however small; the minor patch level will be
1207 changed when only cosmetic, typographical or other edits
1208 are made which neither change the meaning of the document
1209 nor affect the contents of packages.</p>
1212 Thus only the first three components of the policy version
1213 are significant in the <em>Standards-Version</em> control
1214 field, and so either these three components or the all
1215 four components may be specified.<footnote>
1217 In the past, people specified the full version number
1218 in the Standards-Version field, for example `2.3.0.0'.
1219 Since minor patch-level changes don't introduce new
1220 policy, it was thought it would be better to relax
1221 policy and only require the first 3 components to be
1222 specified, in this example `2.3.0'. All four
1223 components may still be used if someone wishes to do
1230 You should regularly, and especially if your package has
1231 become out of date, check for the newest Policy Manual
1232 available and update your package, if necessary. When your
1233 package complies with the new standards you should update the
1234 <tt>Standards-Version</tt> source package field and
1235 release it.<footnote>
1237 See the file <tt>upgrading-checklist</tt> for
1238 information about policy which has changed between
1239 different versions of this document.
1247 <heading>Package relationships</heading>
1250 Source packages should specify which binary packages they
1251 require to be installed or not to be installed in order to
1252 build correctly. For example, if building a package
1253 requires a certain compiler, then the compiler should be
1254 specified as a build-time dependency.
1258 It is not necessary to explicitly specify build-time
1259 relationships on a minimal set of packages that are always
1260 needed to compile, link and put in a Debian package a
1261 standard "Hello World!" program written in C or C++. The
1262 required packages are called <em>build-essential</em>, and
1263 an informational list can be found in
1264 <tt>/usr/share/doc/build-essential/list</tt> (which is
1265 contained in the <tt>build-essential</tt>
1268 <list compact="compact">
1270 <p>This allows maintaining the list separately
1271 from the policy documents (the list does not
1272 need the kind of control that the policy
1278 Having a separate package allows one to install
1279 the build-essential packages on a machine, as
1280 well as allowing other packages such as task
1281 packages to require installation of the
1282 build-essential packages using the depends
1288 The separate package allows bug reports against
1289 the list to be categorized separately from
1290 the policy management process in the BTS.
1300 When specifying the set of build-time dependencies, one
1301 should list only those packages explicitly required by the
1302 build. It is not necessary to list packages which are
1303 required merely because some other package in the list of
1304 build-time dependencies depends on them.<footnote>
1306 The reason for this is that dependencies change, and
1307 you should list all those packages, and <em>only</em>
1308 those packages that <em>you</em> need directly. What
1309 others need is their business. For example, if you
1310 only link against <tt>libimlib</tt>, you will need to
1311 build-depend on <package>libimlib2-dev</package> but
1312 not against any <tt>libjpeg*</tt> packages, even
1313 though <tt>libimlib2-dev</tt> currently depends on
1314 them: installation of <package>libimlib2-dev</package>
1315 will automatically ensure that all of its run-time
1316 dependencies are satisfied.
1322 If build-time dependencies are specified, it must be
1323 possible to build the package and produce working binaries
1324 on a system with only essential and build-essential
1325 packages installed and also those required to satisfy the
1326 build-time relationships (including any implied
1327 relationships). In particular, this means that version
1328 clauses should be used rigorously in build-time
1329 relationships so that one cannot produce bad or
1330 inconsistently configured packages when the relationships
1331 are properly satisfied.
1335 <heading>Changes to the upstream sources</heading>
1338 If changes to the source code are made that are not
1339 specific to the needs of the Debian system, they should be
1340 sent to the upstream authors in whatever form they prefer
1341 so as to be included in the upstream version of the
1345 If you need to configure the package differently for
1346 Debian or for Linux, and the upstream source doesn't
1347 provide a way to do so, you should add such configuration
1348 facilities (for example, a new <prgn>autoconf</prgn> test
1349 or <tt>#define</tt>) and send the patch to the upstream
1350 authors, with the default set to the way they originally
1351 had it. You can then easily override the default in your
1352 <tt>debian/rules</tt> or wherever is appropriate.</p>
1355 You should make sure that the <prgn>configure</prgn> utility
1356 detects the correct architecture specification string
1357 (refer to <ref id="arch-spec"> for details).</p>
1360 If you need to edit a <prgn>Makefile</prgn> where
1361 GNU-style <prgn>configure</prgn> scripts are used, you
1362 should edit the <tt>.in</tt> files rather than editing the
1363 <prgn>Makefile</prgn> directly. This allows the user to
1364 reconfigure the package if necessary. You should
1365 <em>not</em> configure the package and edit the generated
1366 <prgn>Makefile</prgn>! This makes it impossible for
1367 someone else to later reconfigure the package.</p></sect1>
1371 <heading>Documenting your changes</heading>
1374 You should document your changes and updates to the source
1375 package properly in the <tt>debian/changelog</tt> file. (Note
1376 that mistakes in changelogs are usually best rectified by
1377 making a new changelog entry rather than "rewriting history"
1378 by editing old changelog entries.)</p>
1381 In non-experimental packages you must use a format for
1382 <tt>debian/changelog</tt> which is supported by the most
1383 recent released version of <prgn>dpkg</prgn>.<footnote>
1385 If you wish to use an alternative format, you may do
1386 so as long as you include a parser for it in your
1387 source package. The parser must have an API
1388 compatible with that expected by
1389 <prgn>dpkg-genchanges</prgn> and
1390 <prgn>dpkg-gencontrol</prgn>. If there is general
1391 interest in the new format, you should contact the
1392 <package>dpkg</package> maintainer to have the parser
1393 script for it included in the <prgn>dpkg</prgn>
1394 package. (You will need to agree that the parser and
1395 its manpage may be distributed under the GNU GPL, just
1396 as the rest of `dpkg' is.)
1404 <heading>Error trapping in makefiles</heading>
1407 When <prgn>make</prgn> invokes a command in a makefile
1408 (including your package's upstream makefiles and
1409 <tt>debian/rules</tt>), it does so using <tt>sh</tt>. This
1410 means that <tt>sh</tt>'s usual bad error handling
1411 properties apply: if you include a miniature script as one
1412 of the commands in your makefile you'll find that if you
1413 don't do anything about it then errors are not detected
1414 and <prgn>make</prgn> will blithely continue after
1418 Every time you put more than one shell command (this
1419 includes using a loop) in a makefile command you
1420 must make sure that errors are trapped. For
1421 simple compound commands, such as changing directory and
1422 then running a program, using <tt>&&</tt> rather
1423 than semicolon as a command separator is sufficient. For
1424 more complex commands including most loops and
1425 conditionals you should include a separate <tt>set -e</tt>
1426 command at the start of every makefile command that's
1427 actually one of these miniature shell scripts.</p></sect1>
1431 <heading>Obsolete constructs and libraries</heading>
1434 The include file <tt><varargs.h></tt> is
1435 provided to support end-users compiling very old software;
1436 the library <tt>libtermcap</tt> is provided to support the
1437 execution of software which has been linked against it
1438 (either old programs or those such as Netscape which are
1439 only available in binary form).</p>
1442 Debian packages should be patched to use
1443 <tt><stdarg.h></tt> and <tt>ncurses</tt>
1450 <chapt id="controlfields"><heading>Control files and their fields</heading>
1453 Many of the tools in the package management suite manipulate
1454 data represented in a common format, known as <em>control
1455 data</em>. The data is often stored in <em>control
1456 files</em>. Binary and source packages have control files,
1457 and the <tt>.changes</tt> files which control the installation
1458 of uploaded files are also in control file format.
1459 <prgn>Dpkg</prgn>'s internal databases are in a similar
1463 <sect id="controlsyntax"><heading>Syntax of control files</heading>
1466 A control file consists of one or more paragraphs of fields.
1467 The paragraphs are separated by blank lines. Some control
1468 files allow only one paragraph; others allow several, in
1469 which case each paragraph usually refers to a different
1470 package. (For example, in source packages, the first
1471 paragraph refers to the source package, and later paragraphs
1472 refer to binary packages generated from the source.)
1476 Each paragraph consists of a series of data fields; each
1477 field consists of the field name, followed by a colon and
1478 then the data/value associated with that field. It ends at
1479 the end of the line. Horizontal whitespace (spaces and
1480 tabs) may occur immediately before or after the value and is
1481 ignored there; it is conventional to put a single space
1482 after the colon. For example, a field might be:
1483 <example compact="compact">
1486 the field name is <tt>Package</tt> and the field value
1491 Some fields' values may span several lines; in this case
1492 each continuation line <em>must</em> start with a space or
1493 tab. Any trailing spaces or tabs at the end of individual
1494 lines of a field value are ignored.
1498 Except where otherwise stated only a single line of data is
1499 allowed and whitespace is not significant in a field body.
1500 Whitespace must not appear inside names (of packages,
1501 architectures, files or anything else) or version numbers,
1502 or between the characters of multi-character version
1507 Field names are not case-sensitive, but it is usual to
1508 capitalize the field names using mixed case as shown below.
1512 Blank lines, or lines consisting only of spaces and tabs,
1513 are not allowed within field values or between fields - that
1514 would mean a new paragraph.
1519 <sect><heading>List of fields</heading>
1521 This list here is not supposed to be exhaustive. Most fields
1522 are dealt with elsewhere in this document.
1524 <sect1 id="f-Package"><heading><tt>Package</tt>
1528 The name of the binary package. Package names consist of
1529 the alphanumerics and <tt>+</tt> <tt>-</tt> <tt>.</tt>
1530 (plus, minus and full stop).
1534 They must be at least two characters long and must start
1535 with an alphanumeric character and not be all digits. The
1536 use of lowercase package names is strongly recommended
1537 unless the package you're building (or referring to, in
1538 other fields) is already using uppercase.</p>
1541 <sect1 id="f-Version"><heading><tt>Version</tt>
1545 This lists the source or binary package's version number -
1546 see <ref id="versions">.
1552 id="f-Standards-Version"><heading><tt>Standards-Version</tt>
1556 The most recent version of the standards (the policy
1557 manual and associated texts) with which the package
1558 complies. This is updated manually when editing the
1559 source package to conform to newer standards; it can
1560 sometimes be used to tell when a package needs attention.
1561 Its format is described above; see
1562 <ref id="standardsversion">.
1567 <sect1 id="f-Distribution"><heading><tt>Distribution</tt>
1571 In a <tt>.changes</tt> file or parsed changelog output
1572 this contains the (space-separated) name(s) of the
1573 distribution(s) where this version of the package should
1574 be installed. Valid distributions are determined by the
1575 archive maintainers.<footnote>
1576 Current distribution names are:
1577 <taglist compact="compact">
1578 <tag><em>stable</em></tag>
1581 This is the current `released' version of Debian
1582 GNU/Linux. Once the distribution is
1583 <em>stable</em> only security fixes and other
1584 major bug fixes are allowed. When changes are
1585 made to this distribution, the release number is
1586 increased (for example: 2.2r1 becomes 2.2r2 then
1591 <tag><em>unstable</em></tag>
1594 This distribution value refers to the
1595 <em>developmental</em> part of the Debian
1596 distribution tree. New packages, new upstream
1597 versions of packages and bug fixes go into the
1598 <em>unstable</em> directory tree. Download from
1599 this distribution at your own risk.
1603 <tag><em>testing</em></tag>
1606 This distribution value refers to the
1607 <em>testing</em> part of the Debian distribution
1608 tree. It receives its packages from the
1609 unstable distribution after a short time lag to
1610 ensure that there are no major issues with the
1611 unstable packages. It is less prone to breakage
1612 than unstable, but still risky. It is not
1613 possible to upload packages directly to
1618 <tag><em>frozen</em></tag>
1621 From time to time, the <em>testing</em>
1622 distribution enters a state of `code-freeze' in
1623 anticipation of release as a <em>stable</em>
1624 version. During this period of testing only
1625 fixes for existing or newly-discovered bugs will
1626 be allowed. The exact details of this stage are
1627 determined by the Release Manager.
1631 <tag><em>experimental</em></tag>
1634 The packages with this distribution value are
1635 deemed by their maintainers to be high
1636 risk. Oftentimes they represent early beta or
1637 developmental packages from various sources that
1638 the maintainers want people to try, but are not
1639 ready to be a part of the other parts of the
1640 Debian distribution tree. Download at your own
1646 You should list <em>all</em> distributions that the
1647 package should be installed into.
1656 <chapt id="versions"><heading>Version numbering</heading>
1659 Every package has a version number recorded in its
1660 <tt>Version</tt> control file field.
1664 The package management system imposes an ordering on version
1665 numbers, so that it can tell whether packages are being up- or
1666 downgraded and so that package system front end applications
1667 can tell whether a package it finds available is newer than
1668 the one installed on the system. The version number format
1669 has the most significant parts (as far as comparison is
1670 concerned) at the beginning.
1674 The version number format is:
1675 [<var>epoch</var><tt>:</tt>]<var>upstream_version</var>[<tt>-</tt><var>debian_revision</var>]
1679 The three components here are:
1681 <tag><var>epoch</var></tag>
1684 This is a single (generally small) unsigned integer. It
1685 may be omitted, in which case zero is assumed. If it is
1686 omitted then the <var>upstream_version</var> may not
1691 It is provided to allow mistakes in the version numbers
1692 of older versions of a package, and also a package's
1693 previous version numbering schemes, to be left behind.
1697 <tag><var>upstream_version</var></tag>
1700 This is the main part of the version number. It is
1701 usually the version number of the original (`upstream')
1702 package from which the <tt>.deb</tt> file has been made,
1703 if this is applicable. Usually this will be in the same
1704 format as that specified by the upstream author(s);
1705 however, it may need to be reformatted to fit into the
1706 package management system's format and comparison
1711 The comparison behavior of the package management system
1712 with respect to the <var>upstream_version</var> is
1713 described below. The <var>upstream_version</var>
1714 portion of the version number is mandatory.
1718 The <var>upstream_version</var> may contain only
1719 alphanumerics<footnote>
1720 <p>Alphanumerics are <tt>A-Za-z0-9</tt> only.</p>
1722 and the characters <tt>.</tt> <tt>+</tt> <tt>-</tt>
1723 <tt>:</tt> (full stop, plus, hyphen, colon) and should
1724 start with a digit. If there is no
1725 <var>debian_revision</var> then hyphens are not allowed;
1726 if there is no <var>epoch</var> then colons are not
1730 <tag><var>debian_revision</var></tag>
1733 This part of the version number specifies the version of
1734 the Debian package based on the upstream version. It
1735 may contain only alphanumerics and the characters
1736 <tt>+</tt> and <tt>.</tt> (plus and full stop) and is
1737 compared in the same way as the
1738 <var>upstream_version</var> is.
1742 It is optional; if it isn't present then the
1743 <var>upstream_version</var> may not contain a hyphen.
1744 This format represents the case where a piece of
1745 software was written specifically to be turned into a
1746 Debian package, and so there is only one `debianization'
1747 of it and therefore no revision indication is required.
1751 It is conventional to restart the
1752 <var>debian_revision</var> at <tt>1</tt> each time the
1753 <var>upstream_version</var> is increased.
1757 The package management system will break the version
1758 number apart at the last hyphen in the string (if there
1759 is one) to determine the <var>upstream_version</var> and
1760 <var>debian_revision</var>. The absence of a
1761 <var>debian_revision</var> compares earlier than the
1762 presence of one (but note that the
1763 <var>debian_revision</var> is the least significant part
1764 of the version number).
1771 The <var>upstream_version</var> and <var>debian_revision</var>
1772 parts are compared by the package management system using the
1777 The strings are compared from left to right.
1781 First the initial part of each string consisting entirely of
1782 non-digit characters is determined. These two parts (one of
1783 which may be empty) are compared lexically. If a difference
1784 is found it is returned. The lexical comparison is a
1785 comparison of ASCII values modified so that all the letters
1786 sort earlier than all the non-letters.
1790 Then the initial part of the remainder of each string which
1791 consists entirely of digit characters is determined. The
1792 numerical values of these two parts are compared, and any
1793 difference found is returned as the result of the comparison.
1794 For these purposes an empty string (which can only occur at
1795 the end of one or both version strings being compared) counts
1800 These two steps (comparing and removing initial non-digit
1801 strings and initial digit strings) are repeated until a
1802 difference is found or both strings are exhausted.
1806 Note that the purpose of epochs is to allow us to leave behind
1807 mistakes in version numbering, and to cope with situations
1808 where the version numbering scheme changes. It is
1809 <em>not</em> intended to cope with version numbers containing
1810 strings of letters which the package management system cannot
1811 interpret (such as <tt>ALPHA</tt> or <tt>pre-</tt>), or with
1812 silly orderings (the author of this manual has heard of a
1813 package whose versions went <tt>1.1</tt>, <tt>1.2</tt>,
1814 <tt>1.3</tt>, <tt>1</tt>, <tt>2.1</tt>, <tt>2.2</tt>,
1815 <tt>2</tt> and so forth).
1819 If an upstream package has problematic version numbers they
1820 should be converted to a sane form for use in the
1821 <tt>Version</tt> field.
1825 <heading>Version numbers based on dates</heading>
1827 In general, Debian packages should use the same version
1828 numbers as the upstream sources.</p>
1831 However, in some cases where the upstream version number is
1832 based on a date (e.g., a development `snapshot' release) the
1833 package management system cannot handle these version
1834 numbers without epochs. For example, dpkg will consider
1835 `96May01' to be greater than `96Dec24'.</p>
1838 To prevent having to use epochs for every new upstream
1839 version, the version number should be changed to the
1840 following format in such cases: `19960501', `19961224'. It
1841 is up to the maintainer whether he/she wants to bother the
1842 upstream maintainer to change the version numbers upstream,
1846 Note that other version formats based on dates which are
1847 parsed correctly by the package management system should
1848 <em>not</em> be changed.</p>
1851 Native Debian packages (i.e., packages which have been
1852 written especially for Debian) whose version numbers include
1853 dates should always use the `YYYYMMDD' format.</p>
1857 <chapt id="miscellaneous"><heading>Packaging Considerations</heading>
1859 <sect id="timestamps"><heading>Time Stamps</heading>
1861 Maintainers should preserve the modification times of the
1862 upstream source files in a package, as far as is reasonably
1865 The rationale is that there is some information conveyed
1866 by knowing the age of the file, for example, you could
1867 recognize that some documentation is very old by looking
1868 at the modification time, so it would be nice if the
1869 modification time of the upstream source would be
1876 <sect id="debianrules"><heading><tt>debian/rules</tt> - the
1877 main building script</heading>
1880 This file must be an executable makefile, and contains the
1881 package-specific recipes for compiling the package and
1882 building binary package(s) from the source.
1886 It must start with the line <tt>#!/usr/bin/make -f</tt>,
1887 so that it can be invoked by saying its name rather than
1888 invoking <prgn>make</prgn> explicitly.
1892 Since an interactive <tt>debian/rules</tt> script makes it
1893 impossible to auto-compile that package and also makes it
1894 hard for other people to reproduce the same binary
1895 package, all <em>required targets</em> MUST be
1896 non-interactive. At a minimum, required targets are the
1897 ones called by <prgn>dpkg-buildpackage</prgn>, namely,
1898 <em>clean</em>, <em>binary</em>, <em>binary-arch</em>,
1899 <em>binary-indep</em>, and <em>build</em>. It also follows
1900 that any target that these targets depend on must also be
1905 The required and optional targets are as follows:
1907 <tag><tt>build</tt>, <tt>build-arch</tt> (optional),
1908 <tt>build-indep</tt> (optional)</tag>
1911 The <tt>build</tt> target should perform all
1912 non-interactive configuration and compilation of the
1913 package. If a package has an interactive pre-build
1914 configuration routine, the Debianized source package
1915 must either be built after this has taken place (so
1916 that the binary package can be built without rerunning
1917 the configuration) or the configuration routine
1918 modified to become non-interactive. (The latter is
1919 preferable if there are architecture-specific features
1920 detected by the configuration routine.)
1924 For some packages, notably ones where the same
1925 source tree is compiled in different ways to produce
1926 two binary packages, the <tt>build</tt> target
1927 does not make much sense. For these packages it is
1928 good enough to provide two (or more) targets
1929 (<tt>build-a</tt> and <tt>build-b</tt> or whatever)
1930 for each of the ways of building the package, and a
1931 <tt>build</tt> target that does nothing. The
1932 <tt>binary</tt> target will have to build the
1933 package in each of the possible ways and make the
1934 binary package out of each.
1938 The <tt>build</tt> target must not do anything
1939 that might require root privilege.
1943 The <tt>build</tt> target may need to run the
1944 <tt>clean</tt> target first - see below.
1948 When a package has a configuration and build routine
1949 which takes a long time, or when the makefiles are
1950 poorly designed, or when <tt>build</tt> needs to
1951 run <tt>clean</tt> first, it is a good idea to
1952 <tt>touch build</tt> when the build process is
1953 complete. This will ensure that if <tt>debian/rules
1954 build</tt> is run again it will not rebuild the whole
1957 Another common way to do this is for <tt>build</tt>
1958 to depend on <prgn>build-stamp</prgn> and to do
1959 nothing else, and for the <prgn>build-stamp</prgn>
1960 target to do the building and to <tt>touch
1961 build-stamp</tt> on completion. This is
1962 especially useful if the build routine creates a
1963 file or directory called <tt>build</tt>; in such a
1964 case, <tt>build</tt> will need to be listed as
1965 a phony target (i.e., as a dependency of the
1966 <tt>.PHONY</tt> target). See the documentation of
1967 <prgn>make</prgn> for more information on phony
1974 <tag><tt>binary</tt>, <tt>binary-arch</tt>,
1975 <tt>binary-indep</tt>
1979 The <tt>binary</tt> target must be all that is
1980 necessary for the user to build the binary package(s)
1981 produced from this source package. All of these
1982 targets are required to be non-interactive. It is
1983 split into two parts: <prgn>binary-arch</prgn> builds
1984 the binary packages which are specific to a particular
1985 architecture, and <tt>binary-indep</tt> builds
1986 those which are not.
1989 <tt>binary</tt> may be (and commonly is) a target with
1990 no commands which simply depends on
1991 <tt>binary-arch</tt> and <tt>binary-indep</tt>.
1994 Both <tt>binary-*</tt> targets should depend on the
1995 <tt>build</tt> target, or on the appropriate
1996 <tt>build-arch</tt> or <tt>build-indep</tt> target, if
1997 provided, so that the package is built if it has not
1998 been already. It should then create the relevant
1999 binary package(s), using <tt>dpkg-gencontrol</tt> to
2000 make their control files and <tt>dpkg-deb</tt> to
2001 build them and place them in the parent of the top
2006 Both the <tt>binary-arch</tt> and
2007 <tt>binary-indep</tt> targets <em>must</em> exist.
2008 If one of them has nothing to do (which will always be
2009 the case if the source generates only a single binary
2010 package, whether architecture-dependent or not), it
2011 must still exist and must always succeed.
2015 The <tt>binary</tt> targets must be invoked as
2018 The <prgn>fakeroot</prgn> package often allows one
2019 to build a package correctly even without being
2026 <tag><tt>clean</tt></tag>
2029 This must undo any effects that the <tt>build</tt>
2030 and <tt>binary</tt> targets may have had, except
2031 that it should leave alone any output files created in
2032 the parent directory by a run of a <tt>binary</tt>
2033 target. This target must be non-interactive.
2037 If a <tt>build</tt> file is touched at the end of
2038 the <tt>build</tt> target, as suggested above, it
2039 should be removed as the first action that
2040 <tt>clean</tt> performs, so that running
2041 <tt>build</tt> again after an interrupted
2042 <tt>clean</tt> doesn't think that everything is
2047 The <tt>clean</tt> target may need to be
2048 invoked as root if <tt>binary</tt> has been
2049 invoked since the last <tt>clean</tt>, or if
2050 <tt>build</tt> has been invoked as root (since
2051 <tt>build</tt> may create directories, for
2056 <tag><tt>get-orig-source</tt> (optional)</tag>
2059 This target fetches the most recent version of the
2060 original source package from a canonical archive site
2061 (via FTP or WWW, for example), does any necessary
2062 rearrangement to turn it into the original source
2063 tar file format described below, and leaves it in the
2068 This target may be invoked in any directory, and
2069 should take care to clean up any temporary files it
2074 This target is optional, but providing it if
2075 possible is a good idea.
2081 The <tt>build</tt>, <tt>binary</tt> and
2082 <tt>clean</tt> targets must be invoked with the current
2083 directory being the package's top-level directory.
2088 Additional targets may exist in <tt>debian/rules</tt>,
2089 either as published or undocumented interfaces or for the
2090 package's internal use.
2094 The architectures we build on and build for are determined
2095 by <prgn>make</prgn> variables using the utility
2096 <prgn>dpkg-architecture</prgn>. You can determine the
2097 Debian architecture and the GNU style architecture
2098 specification string for the build machine (the machine type
2099 we are building on) as well as for the host machine (the
2100 machine type we are building for). Here is a list of
2101 supported <prgn>make</prgn> variables:
2102 <list compact="compact">
2104 <p><tt>DEB_*_ARCH</tt> (the Debian architecture)</p>
2107 <p><tt>DEB_*_GNU_TYPE</tt> (the GNU style architecture
2108 specification string)</p>
2111 <p><tt>DEB_*_GNU_CPU</tt> (the CPU part of
2112 <tt>DEB_*_GNU_TYPE</tt>)</p>
2115 <p><tt>DEB_*_GNU_SYSTEM</tt> (the System part of
2116 <tt>DEB_*_GNU_TYPE</tt>)</p>
2118 where <tt>*</tt> is either <tt>BUILD</tt> for specification of
2119 the build machine or <tt>HOST</tt> for specification of the
2124 Backward compatibility can be provided in the rules file
2125 by setting the needed variables to suitable default
2126 values; please refer to the documentation of
2127 <prgn>dpkg-architecture</prgn> for details.
2131 It is important to understand that the <tt>DEB_*_ARCH</tt>
2132 string only determines which Debian architecture we are
2133 building on or for. It should not be used to get the CPU
2134 or system information; the GNU style variables should be
2139 <sect id="dpkgchangelog"><heading><tt>debian/changelog</tt>
2143 This file records the changes to the Debian-specific parts of the
2146 Though there is nothing stopping an author who is also
2147 the Debian maintainer from using it for all their
2148 changes, it will have to be renamed if the Debian and
2149 upstream maintainers become different people. In such a
2150 case, however, it might be better to maintain the
2151 package as a non-native package.
2157 It has a special format which allows the package building
2158 tools to discover which version of the package is being
2159 built and find out other release-specific information.
2163 That format is a series of entries like this:
2164 <example compact="compact">
2165 <var>package</var> (<var>version</var>) <var>distribution(s)</var>; urgency=<var>urgency</var>
2167 <p>[optional blank line(s), stripped]</p>
2169 * <var>change details</var>
2170 <var>more change details</var>
2172 <p>[blank line(s), included in output of dpkg-parsechangelog]</p>
2174 * <var>even more change details</var>
2176 <p>[optional blank line(s), stripped]</p>
2178 -- <var>maintainer name</var> <<var>email
2179 address</var>><var>[two spaces]</var> <var>date</var>
2184 <var>package</var> and <var>version</var> are the source
2185 package name and version number.
2189 <var>distribution(s)</var> lists the distributions where
2190 this version should be installed when it is uploaded - it
2191 is copied to the <tt>Distribution</tt> field in the
2192 <tt>.changes</tt> file. See <ref id="f-Distribution">.
2196 <var>urgency</var> is the value for the <tt>Urgency</tt>
2197 field in the <tt>.changes</tt> file for the upload. It is
2198 not possible to specify an urgency containing commas; commas
2199 are used to separate
2200 <tt><var>keyword</var>=<var>value</var></tt> settings in the
2201 <prgn>dpkg</prgn> changelog format (though there is
2202 currently only one useful <var>keyword</var>,
2203 <tt>urgency</tt>).<footnote>
2205 Recognised urgency values are <tt>low</tt>,
2206 <tt>medium</tt>, <tt>high</tt> and <tt>emergency</tt>.
2207 They have an effect on how quickly a package will be
2208 considered for inclusion into the <tt>testing</tt>
2209 distribution, and give an indication of the importance
2210 of any fixes included in this upload.
2216 The change details may in fact be any series of lines
2217 starting with at least two spaces, but conventionally each
2218 change starts with an asterisk and a separating space and
2219 continuation lines are indented so as to bring them in
2220 line with the start of the text above. Blank lines may be
2221 used here to separate groups of changes, if desired.
2225 If this upload resolves bugs recorded in the Bug Tracking
2226 System (BTS), they may be automatically closed on the
2227 inclusion of this package into the Debian archive by
2228 including the string: <tt>closes: Bug#<var>nnnnn</var></tt>
2229 in the change details.<footnote>
2231 To be precise, the string should match the following
2232 Perl regular expression:
2234 /closes:\s*(?:bug)?\#?\s?\d+(?:,\s*(?:bug)?\#?\s?\d+)*/i
2236 Then all of the bug numbers listed will be closed by the
2237 archive maintenance script (<prgn>katie</prgn>), or in
2238 the case of an NMU, marked as fixed.
2244 The maintainer name and email address used in the changelog
2245 should be the details of the person uploading <em>this</em>
2246 version. They are <em>not</em> necessarily those of the
2247 usual package maintainer. The information here will be
2248 copied to the <tt>Changed-By</tt> field in the
2249 <tt>.changes</tt> file, and then later used to send an
2250 acknowledgement when the upload has been installed.
2254 The <var>date</var> should be in RFC822 format<footnote>
2256 This is generated by the <prgn>822-date</prgn>
2259 </footnote>; it should include the time zone specified
2260 numerically, with the time zone name or abbreviation
2261 optionally present as a comment in parentheses.
2265 The first `title' line with the package name should start
2266 at the left hand margin; the `trailer' line with the
2267 maintainer and date details should be preceded by exactly
2268 one space. The maintainer details and the date must be
2269 separated by exactly two spaces.
2272 <sect1><heading>Defining alternative changelog formats</heading>
2275 It is possible to use a different format to the standard
2276 one, by providing a parser for the format you wish to
2280 A changelog parser must not interact with the user at
2286 <sect id="srcsubstvars"><heading><tt>debian/substvars</tt>
2287 and variable substitutions </heading>
2290 When <prgn>dpkg-gencontrol</prgn>,
2291 <prgn>dpkg-genchanges</prgn> and <prgn>dpkg-source</prgn>
2292 generate control files they perform variable substitutions
2293 on their output just before writing it. Variable
2294 substitutions have the form <tt>${<var>variable</var>}</tt>.
2295 The optional file <tt>debian/substvars</tt> contains
2296 variable substitutions to be used; variables can also be set
2297 directly from <tt>debian/rules</tt> using the <tt>-V</tt>
2298 option to the source packaging commands, and certain
2299 predefined variables are also available.
2303 The <tt>debian/substvars</tt> file is usually generated and
2304 modified dynamically by <tt>debian/rules</tt> targets; in
2305 this case it must be removed by the <tt>clean</tt>
2310 See <manref name="dpkg-source" section="1"> for full
2311 details about source variable substitutions, including the
2312 format of <tt>debian/substvars</tt>.</p>
2315 <sect id="debianfiles"><heading><tt>debian/files</tt>
2319 This file is not a permanent part of the source tree; it
2320 is used while building packages to record which files are
2321 being generated. <prgn>dpkg-genchanges</prgn> uses it
2322 when it generates a <tt>.changes</tt> file.
2326 It should not exist in a shipped source package, and so it
2327 (and any backup files or temporary files such as
2328 <tt>files.new</tt><footnote>
2330 <tt>files.new</tt> is used as a temporary file by
2331 <prgn>dpkg-gencontrol</prgn> and
2332 <prgn>dpkg-distaddfile</prgn> - they write a new
2333 version of <tt>files</tt> here before renaming it,
2334 to avoid leaving a corrupted copy if an error
2337 </footnote>) should be removed by the
2338 <tt>clean</tt> target. It may also be wise to
2339 ensure a fresh start by emptying or removing it at the
2340 start of the <tt>binary</tt> target.
2344 When <prgn>dpkg-gencontrol</prgn> is run for a binary
2345 package, it adds an entry to <tt>debian/files</tt> for the
2346 <tt>.deb</tt> file that will be created when <tt>dpkg-deb
2347 --build</tt> is run for that binary package. So for most
2348 packages all that needs to be done with this file is to
2349 delete it in the <tt>clean</tt> target.
2353 If a package upload includes files besides the source
2354 package and any binary packages whose control files were
2355 made with <prgn>dpkg-gencontrol</prgn> then they should be
2356 placed in the parent of the package's top-level directory
2357 and <prgn>dpkg-distaddfile</prgn> should be called to add
2358 the file to the list in <tt>debian/files</tt>.</p>
2361 <sect id="restrictions"><heading>Restrictions on objects in source packages
2365 The source package may not contain any hard links<footnote>
2367 This is not currently detected when building source
2368 packages, but only when extracting
2372 Hard links may be permitted at some point in the
2373 future, but would require a fair amount of
2376 </footnote>, device special files, sockets or setuid or
2377 setgid files.<footnote>
2379 Setgid directories are allowed.
2384 <sect id="descriptions"><heading>Descriptions of packages - the
2385 <tt>Description</tt> field </heading>
2388 The description is intended to describe the program to a user
2389 who has never met it before so that they know whether they
2390 want to install it. It should also give information about the
2391 significant dependencies and conflicts between this package
2392 and others, so that the user knows why these dependencies and
2393 conflicts have been declared.
2396 <sect1><heading>Notes about writing descriptions
2400 The single line synopsis should be kept brief - certainly
2401 under 80 characters.
2405 Do not include the package name in the synopsis line. The
2406 display software knows how to display this already, and you
2407 do not need to state it. Remember that in many situations
2408 the user may only see the synopsis line - make it as
2409 informative as you can.
2413 Do not try to continue the single line synopsis into the
2414 extended description. This will not work correctly when
2415 the full description is displayed, and makes no sense
2416 where only the summary (the single line synopsis) is
2421 The extended description should describe what the package
2422 does and how it relates to the rest of the system (in terms
2423 of, for example, which subsystem it is which part of).
2427 The description field needs to make sense to anyone, even
2428 people who have no idea about any of the things the
2429 package deals with.<footnote>
2431 The blurb that comes with a program in its
2432 announcements and/or <prgn>README</prgn> files is
2433 rarely suitable for use in a description. It is
2434 usually aimed at people who are already in the
2435 community where the package is used.
2441 Put important information first, both in the synopsis and
2442 extended description. Sometimes only the first part of the
2443 synopsis or of the description will be displayed. You can
2444 assume that there will usually be a way to see the whole
2445 extended description.
2449 You may include information about dependencies and so forth
2450 in the extended description, if you wish.
2454 Do not use tab characters. Their effect is not predictable.
2462 <chapt id="maintainerscripts"><heading>Package maintainer scripts
2463 and installation procedure
2466 <sect><heading>Introduction to package maintainer scripts
2470 It is possible to supply scripts as part of a package which
2471 the package management system will run for you when your
2472 package is installed, upgraded or removed.
2476 These scripts are the files <prgn>preinst</prgn>,
2477 <prgn>postinst</prgn>, <prgn>prerm</prgn> and <prgn>postrm</prgn> in the
2478 control area of the package. They must be proper executable
2479 files; if they are scripts (which is recommended), they must
2480 start with the usual <tt>#!</tt> convention. They should be
2481 readable and executable by anyone, and not world-writable.
2485 The package management system looks at the exit status from
2486 these scripts. It is important that they exit with a
2487 non-zero status if there is an error, so that the package
2488 management system can stop its processing. For shell
2489 scripts this means that you <em>almost always</em> need to
2490 use <tt>set -e</tt> (this is usually true when writing shell
2491 scripts, in fact). It is also important, of course, that
2492 they don't exit with a non-zero status if everything went
2497 When a package is upgraded a combination of the scripts from
2498 the old and new packages is called during the upgrade
2499 procedure. If your scripts are going to be at all
2500 complicated you need to be aware of this, and may need to
2501 check the arguments to your scripts.
2505 Broadly speaking the <prgn>preinst</prgn> is called before
2506 (a particular version of) a package is installed, and the
2507 <prgn>postinst</prgn> afterwards; the <prgn>prerm</prgn>
2508 before (a version of) a package is removed and the
2509 <prgn>postrm</prgn> afterwards.
2513 Programs called from maintainer scripts should not normally
2514 have a path prepended to them. Before installation is
2515 started, the package management system checks to see if the
2516 programs <prgn>ldconfig</prgn>,
2517 <prgn>start-stop-daemon</prgn>, <prgn>install-info</prgn>,
2518 and <prgn>update-rc.d</prgn> can be found via the
2519 <tt>PATH</tt> environment variable. Those programs, and any
2520 other program that one would expect to be on the
2521 <tt>PATH</tt>, should thus be invoked without an absolute
2522 pathname. Maintainer scripts should also not reset the
2523 <tt>PATH</tt>, though they might choose to modify it by
2524 prepending or appending package-specific directories. These
2525 considerations really apply to all shell scripts.</p>
2529 <heading>Maintainer scripts Idempotency</heading>
2532 It is necessary for the error recovery procedures that the
2533 scripts be idempotent. This means that if it is run
2534 successfully, and then it is called again, it doesn't bomb
2535 out or cause any harm, but just ensures that everything is
2536 the way it ought to be. If the first call failed, or
2537 aborted half way through for some reason, the second call
2538 should merely do the things that were left undone the first
2539 time, if any, and exit with a success status if everything
2542 This is so that if an error occurs, the user interrupts
2543 <prgn>dpkg</prgn> or some other unforeseen circumstance
2544 happens you don't leave the user with a badly-broken
2545 package when <prgn>dpkg</prgn> attempts to repeat the
2553 <heading>Controlling terminal for maintainer scripts</heading>
2556 The maintainer scripts are guaranteed to run with a
2557 controlling terminal and can interact with the user.
2558 If they need to prompt for passwords, do full-screen
2559 interaction or something similar you should do these
2560 things to and from <tt>/dev/tty</tt>, since
2561 <prgn>dpkg</prgn> will at some point redirect scripts'
2562 standard input and output so that it can log the
2563 installation process. Likewise, because these scripts
2564 may be executed with standard output redirected into a
2565 pipe for logging purposes, Perl scripts should set
2566 unbuffered output by setting <tt>$|=1</tt> so that the
2567 output is printed immediately rather than being
2572 Each script should return a zero exit status for
2573 success, or a nonzero one for failure.
2577 <sect id="mscriptsinstact"><heading>Summary of ways maintainer
2582 <list compact="compact">
2584 <p><var>new-preinst</var> <tt>install</tt></p>
2587 <p><var>new-preinst</var> <tt>install</tt>
2588 <var>old-version</var></p>
2591 <p><var>new-preinst</var> <tt>upgrade</tt>
2592 <var>old-version</var></p>
2595 <p><var>old-preinst</var> <tt>abort-upgrade</tt>
2596 <var>new-version</var>
2602 <list compact="compact">
2604 <p><var>postinst</var> <tt>configure</tt>
2605 <var>most-recently-configured-version</var></p>
2608 <p><var>old-postinst</var> <tt>abort-upgrade</tt>
2609 <var>new-version</var></p>
2612 <p><var>conflictor's-postinst</var> <tt>abort-remove</tt>
2613 <tt>in-favour</tt> <var>package</var>
2614 <var>new-version</var></p>
2618 <var>deconfigured's-postinst</var>
2619 <tt>abort-deconfigure</tt> <tt>in-favour</tt>
2620 <var>failed-install-package</var> <var>version</var>
2621 <tt>removing</tt> <var>conflicting-package</var>
2628 <list compact="compact">
2630 <p><var>prerm</var> <tt>remove</tt></p>
2633 <p><var>old-prerm</var> <tt>upgrade</tt>
2634 <var>new-version</var></p>
2637 <p><var>new-prerm</var> <tt>failed-upgrade</tt>
2638 <var>old-version</var></p>
2641 <p><var>conflictor's-prerm</var> <tt>remove</tt>
2642 <tt>in-favour</tt> <var>package</var>
2643 <var>new-version</var></p>
2647 <var>deconfigured's-prerm</var> <tt>deconfigure</tt>
2648 <tt>in-favour</tt> <var>package-being-installed</var>
2649 <var>version</var> <tt>removing</tt>
2650 <var>conflicting-package</var>
2657 <list compact="compact">
2659 <p><var>postrm</var> <tt>remove</tt></p>
2662 <p><var>postrm</var> <tt>purge</tt></p>
2666 <var>old-postrm</var> <tt>upgrade</tt>
2667 <var>new-version</var></p>
2670 <p><var>new-postrm</var> <tt>failed-upgrade</tt>
2671 <var>old-version</var></p>
2674 <p><var>new-postrm</var> <tt>abort-install</tt></p>
2677 <p><var>new-postrm</var> <tt>abort-install</tt>
2678 <var>old-version</var></p>
2681 <p><var>new-postrm</var> <tt>abort-upgrade</tt>
2682 <var>old-version</var></p>
2686 <var>disappearer's-postrm</var> <tt>disappear</tt>
2687 <var>overwriter</var>
2688 <var>overwriter-version</var></p></item>
2693 <sect id="unpackphase"><heading>Details of unpack phase of
2694 installation or upgrade
2698 The procedure on installation/upgrade/overwrite/disappear
2699 (i.e., when running <tt>dpkg --unpack</tt>, or the unpack
2700 stage of <tt>dpkg --install</tt>) is as follows. In each
2701 case, if a major error occurs (unless listed below) the
2702 actions are, in general, run backwards - this means that the
2703 maintainer scripts are run with different arguments in
2704 reverse order. These are the `error unwind' calls listed
2712 <p>If a version of the package is already
2714 <example compact="compact">
2715 <var>old-prerm</var> upgrade <var>new-version</var>
2720 If the script runs but exits with a non-zero
2721 exit status, <prgn>dpkg</prgn> will attempt:
2722 <example compact="compact">
2723 <var>new-prerm</var> failed-upgrade <var>old-version</var>
2725 Error unwind, for both the above cases:
2726 <example compact="compact">
2727 <var>old-postinst</var> abort-upgrade <var>new-version</var>
2735 <p>If a `conflicting' package is being removed at the same time:
2739 If any packages depended on that conflicting
2740 package and <tt>--auto-deconfigure</tt> is
2741 specified, call, for each such package:
2742 <example compact="compact">
2743 <var>deconfigured's-prerm</var> deconfigure \
2744 in-favour <var>package-being-installed</var> <var>version</var> \
2745 removing <var>conflicting-package</var> <var>version</var>
2748 <example compact="compact">
2749 <var>deconfigured's-postinst</var> abort-deconfigure \
2750 in-favour <var>package-being-installed-but-failed</var> <var>version</var> \
2751 removing <var>conflicting-package</var> <var>version</var>
2753 The deconfigured packages are marked as
2754 requiring configuration, so that if
2755 <tt>--install</tt> is used they will be
2756 configured again if possible.</p>
2759 <p>To prepare for removal of the conflicting package, call:
2760 <example compact="compact">
2761 <var>conflictor's-prerm</var> remove \
2762 in-favour <var>package</var> <var>new-version</var>
2765 <example compact="compact">
2766 <var>conflictor's-postinst</var> abort-remove \
2767 in-favour <var>package</var> <var>new-version</var>
2778 <p>If the package is being upgraded, call:
2779 <example compact="compact">
2780 <var>new-preinst</var> upgrade <var>old-version</var>
2785 Otherwise, if the package had some configuration
2786 files from a previous version installed (i.e., it
2787 is in the `configuration files only' state):
2788 <example compact="compact">
2789 <var>new-preinst</var> install <var>old-version</var>
2793 <p>Otherwise (i.e., the package was completely purged):
2794 <example compact="compact">
2795 <var>new-preinst</var> install
2797 Error unwind actions, respectively:
2798 <example compact="compact">
2799 <var>new-postrm</var> abort-upgrade <var>old-version</var>
2800 <var>new-postrm</var> abort-install <var>old-version</var>
2801 <var>new-postrm</var> abort-install
2810 The new package's files are unpacked, overwriting any
2811 that may be on the system already, for example any
2812 from the old version of the same package or from
2813 another package. Backups of the old files are kept
2814 temporarily, and if anything goes wrong the package
2815 management system will attempt to put them back as
2816 part of the error unwind.
2820 It is an error for a package to contains files which
2821 are on the system in another package, unless
2822 <tt>Replaces</tt> is used (see <ref id="replaces">).
2824 The following paragraph is not currently the case:
2825 Currently the <tt>- - force-overwrite</tt> flag is
2826 enabled, downgrading it to a warning, but this may not
2832 It is a more serious error for a package to contain a
2833 plain file or other kind of non-directory where another
2834 package has a directory (again, unless
2835 <tt>Replaces</tt> is used). This error can be
2836 overridden if desired using
2837 <tt>--force-overwrite-dir</tt>, but this is not
2842 Packages which overwrite each other's files produce
2843 behavior which, though deterministic, is hard for the
2844 system administrator to understand. It can easily
2845 lead to `missing' programs if, for example, a package
2846 is installed which overwrites a file from another
2847 package, and is then removed again.<footnote>
2849 Part of the problem is due to what is arguably a
2850 bug in <prgn>dpkg</prgn>.
2856 A directory will never be replaced by a symbolic link
2857 to a directory or vice versa; instead, the existing
2858 state (symlink or not) will be left alone and
2859 <prgn>dpkg</prgn> will follow the symlink if there is
2867 <p>If the package is being upgraded, call
2868 <example compact="compact">
2869 <var>old-postrm</var> upgrade <var>new-version</var>
2874 <p>If this fails, <prgn>dpkg</prgn> will attempt:
2875 <example compact="compact">
2876 <var>new-postrm</var> failed-upgrade <var>old-version</var>
2878 Error unwind, for both cases:
2879 <example compact="compact">
2880 <var>old-preinst</var> abort-upgrade <var>new-version</var>
2887 This is the point of no return - if
2888 <prgn>dpkg</prgn> gets this far, it won't back off
2889 past this point if an error occurs. This will
2890 leave the package in a fairly bad state, which
2891 will require a successful re-installation to clear
2892 up, but it's when <prgn>dpkg</prgn> starts doing
2893 things that are irreversible.
2898 Any files which were in the old version of the package
2899 but not in the new are removed.</p>
2902 <p>The new file list replaces the old.</p>
2905 <p>The new maintainer scripts replace the old.</p>
2909 <p>Any packages all of whose files have been overwritten during the
2910 installation, and which aren't required for
2911 dependencies, are considered to have been removed.
2912 For each such package
2915 <p><prgn>dpkg</prgn> calls:
2916 <example compact="compact">
2917 <var>disappearer's-postrm</var> disappear \
2918 <var>overwriter</var> <var>overwriter-version</var>
2923 <p>The package's maintainer scripts are removed.
2928 It is noted in the status database as being in a
2929 sane state, namely not installed (any conffiles
2930 it may have are ignored, rather than being
2931 removed by <prgn>dpkg</prgn>). Note that
2932 disappearing packages do not have their prerm
2933 called, because <prgn>dpkg</prgn> doesn't know
2934 in advance that the package is going to
2943 Any files in the package we're unpacking that are also
2944 listed in the file lists of other packages are removed
2945 from those lists. (This will lobotomize the file list
2946 of the `conflicting' package if there is one.)
2951 The backup files made during installation, above, are
2958 The new package's status is now sane, and recorded as
2963 Here is another point of no return - if the
2964 conflicting package's removal fails we do not unwind
2965 the rest of the installation; the conflicting package
2966 is left in a half-removed limbo.
2972 If there was a conflicting package we go and do the
2973 removal actions (described below), starting with the
2974 removal of the conflicting package's files (any that
2975 are also in the package being installed have already
2976 been removed from the conflicting package's file list,
2977 and so do not get removed now).
2984 <sect id="configdetails"><heading>Details of configuration</heading>
2987 When we configure a package (this happens with <tt>dpkg
2988 --install</tt> and <tt>dpkg --configure</tt>), we first
2989 update any <tt>conffile</tt>s and then call:
2990 <example compact="compact">
2991 <var>postinst</var> configure <var>most-recently-configured-version</var>
2996 No attempt is made to unwind after errors during
3001 If there is no most recently configured version
3002 <prgn>dpkg</prgn> will pass a null argument; older versions
3003 of dpkg may pass <tt><unknown></tt> (including the
3004 angle brackets) in this case. Even older ones do not pass a
3005 second argument at all, under any circumstances.
3009 <sect id="removedetails"><heading>Details of removal and/or
3010 configuration purging</heading>
3016 <example compact="compact">
3017 <var>prerm</var> remove
3023 The package's files are removed (except <tt>conffile</tt>s).
3028 <example compact="compact">
3029 <var>postrm</var> remove
3035 All the maintainer scripts except the <prgn>postrm</prgn>
3040 If we aren't purging the package we stop here. Note
3041 that packages which have no <prgn>postrm</prgn> and no
3042 <tt>conffile</tt>s are automatically purged when
3043 removed, as there is no difference except for the
3044 <prgn>dpkg</prgn> status.</p>
3048 The <tt>conffile</tt>s and any backup files
3049 (<tt>~</tt>-files, <tt>#*#</tt> files,
3050 <tt>%</tt>-files, <tt>.dpkg-{old,new,tmp}</tt>, etc.)
3055 <example compact="compact">
3056 <var>postrm</var> purge
3061 <p>The package's file list is removed.</p>
3064 No attempt is made to unwind after errors during
3071 <chapt id="relationships"><heading>Declaring relationships between
3075 Packages can declare in their control file that they have
3076 certain relationships to other packages - for example, that
3077 they may not be installed at the same time as certain other
3078 packages, and/or that they depend on the presence of others,
3079 or that they should overwrite files in certain other packages
3084 This is done using the <tt>Depends</tt>, <tt>Pre-Depends</tt>,
3085 <tt>Recommends</tt>, <tt>Suggests</tt>, <tt>Enhances</tt>,
3086 <tt>Conflicts</tt>, <tt>Provides</tt> and <tt>Replaces</tt>
3087 control file fields.
3091 Source packages may declare relationships to binary packages,
3092 saying that they require certain binary packages to be
3093 installed or absent at the time of building the package.
3097 This is done using the <tt>Build-Depends</tt>,
3098 <tt>Build-Depends-Indep</tt>, <tt>Build-Conflicts</tt> and
3099 <tt>Build-Conflicts-Indep</tt> control file fields.
3102 <sect id="depsyntax"><heading>Syntax of relationship fields
3106 These fields all have a uniform syntax. They are a list of
3107 package names separated by commas.
3111 In the <tt>Depends</tt>, <tt>Recommends</tt>,
3112 <tt>Suggests</tt>, <tt>Pre-Depends</tt>,
3113 <tt>Build-Depends</tt> and <tt>Build-Depends-Indep</tt>
3114 control file fields of the package, which declare
3115 dependencies on other packages, the package names listed may
3116 also include lists of alternative package names, separated
3117 by vertical bar (pipe) symbols <tt>|</tt>. In such a case,
3118 if any one of the alternative packages is installed, that
3119 part of the dependency is considered to be satisfied.
3123 All of the fields except for <tt>Provides</tt> may restrict
3124 their applicability to particular versions of each named
3125 package. This is done in parentheses after each individual
3126 package name; the parentheses should contain a relation from
3127 the list below followed by a version number, in the format
3128 described in <ref id="versions">.
3132 The relations allowed are <tt><<</tt>, <tt><=</tt>,
3133 <tt>=</tt>, <tt>>=</tt> and <tt>>></tt> for
3134 strictly earlier, earlier or equal, exactly equal, later or
3135 equal and strictly later, respectively. The deprecated
3136 forms <tt><</tt> and <tt>></tt> were used to mean
3137 earlier/later or equal, rather than strictly earlier/later,
3138 so they should not appear in new packages (though
3139 <prgn>dpkg</prgn> still supports them).
3143 Whitespace may appear at any point in the version
3144 specification subject to the rules in <ref
3145 id="controlsyntax">, and must appear where it's necessary to
3146 disambiguate; it is not otherwise significant. For
3147 consistency and in case of future changes to
3148 <prgn>dpkg</prgn> it is recommended that a single space be
3149 used after a version relationship and before a version
3150 number; it is also conventional to put a single space after
3151 each comma, on either side of each vertical bar, and before
3152 each open parenthesis.
3156 For example, a list of dependencies might appear as:
3157 <example compact="compact">
3160 Depends: libc6 (>= 2.2.1), exim | mail-transport-agent
3165 All fields that specify build-time relationships
3166 (<tt>Build-Depends</tt>, <tt>Build-Depends-Indep</tt>,
3167 <tt>Build-Conflicts</tt> and <tt>Build-Conflicts-Indep</tt>)
3168 may be restricted to a certain set of architectures. This
3169 is indicated in brackets after each individual package name and
3170 the optional version specification. The brackets enclose a
3171 list of Debian architecture names separated by whitespace.
3172 Exclamation marks may be prepended to each of the names.
3173 (It is not permitted for some names to be prepended with
3174 exclamation marks and others not.) If the current Debian
3175 host architecture is not in this list and there are no
3176 exclamation marks in the list, or it is in the list with a
3177 prepended exclamation mark, the package name and the
3178 associated version specification are ignored completely for
3179 the purposes of defining the relationships.
3184 <example compact="compact">
3186 Build-Depends-Indep: texinfo
3187 Build-Depends: kernel-headers-2.2.10 [!hurd-i386],
3188 hurd-dev [hurd-i386], gnumach-dev [hurd-i386]
3193 Note that the binary package relationship fields such as
3194 <tt>Depends</tt> appear in one of the binary package
3195 sections of the control file, whereas the build-time
3196 relationships such as <tt>Build-Depends</tt> appear in the
3197 source package section of the control file (which is the
3203 <heading>Binary Dependencies - <tt>Depends</tt>,
3204 <tt>Recommends</tt>, <tt>Suggests</tt>, <tt>Enhances</tt>,
3205 <tt>Pre-Depends</tt>
3209 These five fields are used to declare a dependency
3210 relationship by one package on another. Except for
3211 <tt>Enhances</tt>, they appear in the depending (binary)
3212 package's control file. (<tt>Enhances</tt> appears in the
3213 recommending package's control file.)
3217 A <tt>Depends</tt> field takes effect <em>only</em> when a
3218 package is to be configured. It does not prevent a package
3219 being on the system in an unconfigured state while its
3220 dependencies are unsatisfied, and it is possible to replace
3221 a package whose dependencies are satisfied and which is
3222 properly installed with a different version whose
3223 dependencies are not and cannot be satisfied; when this is
3224 done the depending package will be left unconfigured (since
3225 attempts to configure it will give errors) and will not
3226 function properly. If it is necessary, a
3227 <tt>Pre-Depends</tt> field can be used, which has a partial
3228 effect even when a package is being unpacked, as explained
3229 in detail below. (The other three dependency fields,
3230 <tt>Recommends</tt>, <tt>Suggests</tt> and
3231 <tt>Enhances</tt>, are only used by the various front-ends
3232 to <prgn>dpkg</prgn> such as <prgn>dselect</prgn>.)
3236 For this reason packages in an installation run are usually
3237 all unpacked first and all configured later; this gives
3238 later versions of packages with dependencies on later
3239 versions of other packages the opportunity to have their
3240 dependencies satisfied.
3244 The <tt>Depends</tt> field thus allows package maintainers
3245 to impose an order in which packages should be configured.
3249 The meaning of the five dependency fields is as follows:
3251 <tag><tt>Depends</tt></tag>
3254 This declares an absolute dependency. A package will
3255 not be configured unless all of the packages listed in
3256 its <tt>Depends</tt> field have been correctly
3261 The <tt>Depends</tt> field should be used if the
3262 depended-on package is required for the depending
3263 package to provide a significant amount of
3267 The <tt>Depends</tt> field should also be used if the
3268 <prgn>postinst</prgn>, <prgn>prerm</prgn> or
3269 <prgn>postrm</prgn> scripts require the package to be
3270 present in order to run. Note, however, that the
3271 <prgn>postrm</prgn> cannot rely on any non-essential
3272 packages to be present during the <tt>purge</tt>
3276 <tag><tt>Recommends</tt></tag>
3278 <p>This declares a strong, but not absolute, dependency.
3282 The <tt>Recommends</tt> field should list packages
3283 that would be found together with this one in all but
3284 unusual installations.</p>
3287 <tag><tt>Suggests</tt></tag>
3290 This is used to declare that one package may be more
3291 useful with one or more others. Using this field
3292 tells the packaging system and the user that the
3293 listed packages are related to this one and can
3294 perhaps enhance its usefulness, but that installing
3295 this one without them is perfectly reasonable.
3299 <tag><tt>Enhances</tt></tag>
3302 This field is similar to Suggests but works in the
3303 opposite direction. It is used to declare that a
3304 package can enhance the functionality of another
3309 <tag><tt>Pre-Depends</tt></tag>
3312 This field is like <tt>Depends</tt>, except that it
3313 also forces <prgn>dpkg</prgn> to complete installation
3314 of the packages named before even starting the
3315 installation of the package which declares the
3316 pre-dependency, as follows:
3320 When a package declaring a pre-dependency is about to
3321 be <em>unpacked</em> the pre-dependency can be
3322 satisfied if the depended-on package is either fully
3323 configured, <em>or even if</em> the depended-on
3324 package(s) are only unpacked or half-configured,
3325 provided that they have been configured correctly at
3326 some point in the past (and not removed or partially
3327 removed since). In this case, both the
3328 previously-configured and currently unpacked or
3329 half-configured versions must satisfy any version
3330 clause in the <tt>Pre-Depends</tt> field.
3334 When the package declaring a pre-dependency is about
3335 to be <em>configured</em>, the pre-dependency will be
3336 treated as a normal <tt>Depends</tt>, that is, it will
3337 be considered satisfied only if the depended-on
3338 package has been correctly configured.
3342 <tt>Pre-Depends</tt> should be used sparingly,
3343 preferably only by packages whose premature upgrade or
3344 installation would hamper the ability of the system to
3345 continue with any upgrade that might be in progress.
3349 <tt>Pre-Depends</tt> are also required if the
3350 <prgn>preinst</prgn> script depends on the named
3351 package. It is best to avoid this situation if
3357 When selecting which level of dependency to use you should
3358 consider how important the depended-on package is to the
3359 functionality of the one declaring the dependency. Some
3360 packages are composed of components of varying degrees of
3361 importance. Such a package should list using
3362 <tt>Depends</tt> the package(s) which are required by the
3363 more important components. The other components'
3364 requirements may be mentioned as Suggestions or
3365 Recommendations, as appropriate to the components' relative
3370 <sect id="conflicts"><heading>Conflicting binary packages -
3371 <tt>Conflicts</tt></heading>
3374 When one binary package declares a conflict with another
3375 using a <tt>Conflicts</tt> field, <prgn>dpkg</prgn> will
3376 refuse to allow them to be installed on the system at the
3381 If one package is to be installed, the other must be removed
3382 first - if the package being installed is marked as
3383 replacing (see <ref id="replaces">) the one on the system,
3384 or the one on the system is marked as deselected, or both
3385 packages are marked <tt>Essential</tt>, then
3386 <prgn>dpkg</prgn> will automatically remove the package
3387 which is causing the conflict, otherwise it will halt the
3388 installation of the new package with an error. This
3389 mechanism is specifically designed to produce an error when
3390 the installed package is <tt>Essential</tt>, but the new
3395 A package will not cause a conflict merely because its
3396 configuration files are still installed; it must be at least
3401 A special exception is made for packages which declare a
3402 conflict with their own package name, or with a virtual
3403 package which they provide (see below): this does not
3404 prevent their installation, and allows a package to conflict
3405 with others providing a replacement for it. You use this
3406 feature when you want the package in question to be the only
3407 package providing some feature.
3411 A <tt>Conflicts</tt> entry should almost never have an
3412 `earlier than' version clause. This would prevent
3413 <prgn>dpkg</prgn> from upgrading or installing the package
3414 which declared such a conflict until the upgrade or removal
3415 of the conflicted-with package had been completed.
3419 <sect id="virtual"><heading>Virtual packages - <tt>Provides</tt>
3423 As well as the names of actual (`concrete') packages, the
3424 package relationship fields <tt>Depends</tt>,
3425 <tt>Recommends</tt>, <tt>Suggests</tt>, <tt>Enhances</tt>,
3426 <tt>Pre-Depends</tt>, <tt>Conflicts</tt>,
3427 <tt>Build-Depends</tt>, <tt>Build-Depends-Indep</tt>,
3428 <tt>Build-Conflicts</tt> and <tt>Build-Conflicts-Indep</tt>
3429 may mention `virtual packages'.
3433 A <em>virtual package</em> is one which appears in the
3434 <tt>Provides</tt> control file field of another package.
3435 The effect is as if the package(s) which provide a
3436 particular virtual package name had been listed by name
3437 everywhere the virtual package name appears.
3441 If there are both a real and a virtual package of the same
3442 name then the dependency may be satisfied (or the conflict
3443 caused) by either the real package or any of the virtual
3444 packages which provide it. This is so that, for example,
3446 <example compact="compact">
3450 and someone else releases an enhanced version of the
3451 <tt>bar</tt> package (for example, a non-US variant), they
3453 <example compact="compact">
3457 and the <tt>bar-plus</tt> package will now also satisfy the
3458 dependency for the <tt>foo</tt> package.
3462 If a dependency or a conflict has a version number attached
3463 then only real packages will be considered to see whether
3464 the relationship is satisfied (or the prohibition violated,
3465 for a conflict) - it is assumed that a real package which
3466 provides the virtual package is not of the `right' version.
3467 So, a <tt>Provides</tt> field may not contain version
3468 numbers, and the version number of the concrete package
3469 which provides a particular virtual package will not be
3470 looked at when considering a dependency on or conflict with
3471 the virtual package name.
3475 It is likely that the ability will be added in a future
3476 release of <prgn>dpkg</prgn> to specify a version number for
3477 each virtual package it provides. This feature is not yet
3478 present, however, and is expected to be used only
3483 If you want to specify which of a set of real packages
3484 should be the default to satisfy a particular dependency on
3485 a virtual package, you should list the real package as an
3486 alternative before the virtual one.
3491 <sect id="replaces"><heading>Overwriting files and replacing
3492 packages - <tt>Replaces</tt></heading>
3495 The <tt>Replaces</tt> control file field has two distinct
3496 purposes, which come into play in different situations.
3499 <sect1><heading>Overwriting files in other packages</heading>
3502 Firstly, as mentioned before, it is usually an error for a
3503 package to contain files which are on the system in
3508 However, if the overwriting package declares that it
3509 <tt>Replaces</tt> the one containing the file being
3510 overwritten, then <prgn>dpkg</prgn> will replace the file
3511 from the old package with that from the new. The file
3512 will no longer be listed as `owned' by the old package.
3516 If a package is completely replaced in this way, so that
3517 <prgn>dpkg</prgn> does not know of any files it still
3518 contains, it is considered to have `disappeared'. It will
3519 be marked as not wanted on the system (selected for
3520 removal) and not installed. Any <tt>conffile</tt>s
3521 details noted for the package will be ignored, as they
3522 will have been taken over by the overwriting package. The
3523 package's <prgn>postrm</prgn> script will be run with a
3524 special argument to allow the package to do any final
3525 cleanup required. See <ref id="mscriptsinstact">.
3529 If an installed package, <tt>foo</tt> say, declares that
3530 it replaces another, <tt>bar</tt>, and an attempt is made
3531 to install <tt>bar</tt>, <prgn>dpkg</prgn> will discard
3532 files in the <tt>bar</tt> package which would overwrite
3533 those already present in <tt>foo</tt>. This is so that
3534 you can install an older version of a package without
3539 For this usage of <tt>Replaces</tt>, virtual packages (see
3540 <ref id="virtual">) are not considered when looking at a
3541 <tt>Replaces</tt> field - the packages declared as being
3542 replaced must be mentioned by their real names.
3546 Furthermore, this usage of <tt>Replaces</tt> only takes
3547 effect when both packages are at least partially on the
3548 system at once, so that it can only happen if they do not
3549 conflict or if the conflict has been overridden.
3554 <sect1><heading>Replacing whole packages, forcing their
3558 Secondly, <tt>Replaces</tt> allows the packaging system to
3559 resolve which package should be removed when there is a
3560 conflict - see <ref id="conflicts">. This usage only
3561 takes effect when the two packages <em>do</em> conflict,
3562 so that the two usages of this field do not interfere with
3567 In this situation, the package declared as being replaced
3568 can be a virtual package, so for example, all mail
3569 transport agents (MTAs) would have the following fields in
3570 their control files:
3571 <example compact="compact">
3572 Provides: mail-transport-agent
3573 Conflicts: mail-transport-agent
3574 Replaces: mail-transport-agent
3576 ensuring that only one MTA can be installed at any one
3581 <sect><heading>Relationships between source and binary packages -
3582 <tt>Build-Depends</tt>, <tt>Build-Depends-Indep</tt>,
3583 <tt>Build-Conflicts</tt>, <tt>Build-Conflicts-Indep</tt>
3587 A source package may declare a dependency or a conflict on a
3588 binary package, indicating which packages are required to be
3589 present on the system in order to build the binary packages
3590 from the source package. This is done with the control file
3591 fields <tt>Build-Depends</tt>, <tt>Build-Depends-Indep</tt>,
3592 <tt>Build-Conflicts</tt> and <tt>Build-Conflicts-Indep</tt>.
3593 The dependencies and conflicts they define must be satisfied
3594 (as defined earlier for binary packages) in order to invoke
3595 the targets in <tt>debian/rules</tt>, as follows:
3598 <tag><tt>Build-Depends</tt>, <tt>Build-Conflicts</tt></tag>
3601 The <tt>Build-Depends</tt> and
3602 <tt>Build-Conflicts</tt> fields must be satisfied when
3603 any of the following targets is invoked:
3604 <tt>build</tt>, <tt>binary</tt>, <tt>binary-arch</tt>
3605 and <tt>binary-indep</tt>.
3608 <tag><tt>Build-Depends-Indep</tt>, <tt>Build-Conflicts-Indep</tt></tag>
3611 The <tt>Build-Depends-Indep</tt> and
3612 <tt>Build-Conflicts-Indep</tt> fields must be
3613 satisfied when any of the following targets is
3614 invoked: <tt>binary</tt> and <tt>binary-indep</tt>.
3625 <chapt id="conffiles"><heading>Configuration file handling
3629 This chapter has been superseded by <ref id="config files">.
3633 <chapt id="sharedlibs"><heading>Shared libraries</heading>
3636 Packages containing shared libraries must be constructed with
3637 a little care to make sure that the shared library is always
3638 available. This is especially important for packages whose
3639 shared libraries are vitally important, such as the C library
3640 (currently <tt>libc6</tt>).
3644 Firstly, the package should install the shared libraries under
3645 their normal names. For example, the <tt>libgdbmg1</tt>
3646 package should install <tt>libgdbm.so.1.7.3</tt> as
3647 <tt>/usr/lib/libgdbm.so.1.7.3</tt>. The files should not be
3648 renamed or re-linked by any <prgn>prerm</prgn> or
3649 <prgn>postrm</prgn> scripts; <prgn>dpkg</prgn> will take care
3650 of renaming things safely without affecting running programs,
3651 and attempts to interfere with this are likely to lead to
3656 Secondly, the package should include the symbolic link that
3657 <prgn>ldconfig</prgn> would create for the shared libraries.
3658 For example, the <prgn>libgdbmg1</prgn> package should include
3659 a symbolic link from <tt>/usr/lib/libgdbm.so.1</tt> to
3660 <tt>libgdbm.so.1.7.3</tt>. This is needed so that the dynamic
3661 linker (for example <prgn>ld.so</prgn> or
3662 <prgn>ld-linux.so.*</prgn>) can find the library between the
3663 time that <prgn>dpkg</prgn> installs it and the time that
3664 <prgn>ldconfig</prgn> is run in the <prgn>postinst</prgn>
3667 The package management system requires the library to be
3668 placed before the symbolic link pointing to it in the
3669 <tt>.deb</tt> file. This is so that when
3670 <prgn>dpkg</prgn> comes to install the symlink
3671 (overwriting the previous symlink pointing at an older
3672 version of the library), the new shared library is already
3673 in place. In the past, this was achieved by creating the
3674 library in the temporary packaging directory before
3675 creating the symlink. Unfortunately, this was not always
3676 effective, since the building of the tar file in the
3677 <tt>.deb</tt> depended on the behavior of the underlying
3678 file system. Some file systems (such as reiserfs) reorder
3679 the files so that the order of creation is forgotten.
3680 Starting with release <tt>1.7.0</tt>, <prgn>dpkg</prgn>
3681 will reorder the files itself as necessary when building a
3682 package. Thus it is no longer important to concern
3683 oneself with the order of file creation.
3689 Thirdly, the associated development package should contain a
3690 symlink for the shared library without a version number. For
3691 example, the <tt>libgdbmg1-dev</tt> package should include a
3692 symlink from <tt>/usr/lib/libgdbm.so</tt> to
3693 <tt>libgdbm.so.1.7.3</tt>. This symlink is needed by the
3694 linker (<prgn>ld</prgn>) when compiling packages, as it will
3695 only look for <tt>libgdbm.so</tt> when compiling dynamically.
3699 Any package installing shared libraries in one of the default
3700 library directories of the dynamic linker (which are currently
3701 <tt>/usr/lib</tt> and <tt>/lib</tt>) or a directory that is
3702 listed in <tt>/etc/ld.so.conf</tt><footnote>
3705 <list compact="compact">
3706 <item><p>/usr/X11R6/lib/Xaw3d</p></item>
3707 <item><p>/usr/local/lib</p></item>
3708 <item><p>/usr/lib/libc5-compat</p></item>
3709 <item><p>/lib/libc5-compat</p></item>
3710 <item><p>/usr/X11R6/lib</p></item>
3714 must call <prgn>ldconfig</prgn> in its <prgn>postinst</prgn>
3715 script if the first argument is <tt>configure</tt> and should
3716 call it in the <prgn>postrm</prgn> script if the first
3717 argument is <tt>remove</tt>.
3721 However, <prgn>postrm</prgn> and <prgn>preinst</prgn> scripts
3722 <em>must not</em> call <prgn>ldconfig</prgn> in the case where
3723 the package is being upgraded (see <ref id="unpackphase"> for
3724 details), as <prgn>ldconfig</prgn> will see the temporary
3725 names that <prgn>dpkg</prgn> uses for the files while it is
3726 installing them and will make the shared library links point
3727 to them, just before <prgn>dpkg</prgn> continues the
3728 installation and renames the temporary files!
3732 <heading>Handling shared library dependencies - the
3733 <tt>shlibs</tt> system</heading>
3736 If a package contains a binary or library which links to a
3737 shared library, we must ensure that when the package is
3738 installed on the system, all of the libraries needed are
3739 also installed. This requirement led to the creation of the
3740 <tt>shlibs</tt> system, which is very simple in its design:
3741 any package which <em>provides</em> a shared library also
3742 provides information on the package dependencies required to
3743 ensure the presence of this library, and any package which
3744 <em>uses</em> a shared library uses this information to
3745 determine the dependencies it requires. The files which
3746 contain the mapping from shared libraries to the necessary
3747 dependency information are called <tt>shlibs</tt> files.
3751 Thus, when a package is built which contains any shared
3752 libraries, it must provide a <tt>shlibs</tt> file for other
3753 packages to use, and when a package is built which contains
3754 any shared libraries or compiled binaries, it must run
3755 <prgn>dpkg-shlibdeps</prgn> on these to determine the
3756 libraries used and hence the dependencies needed by this
3759 In the past, the shared libraries linked to were
3760 determined by calling <prgn>ldd</prgn>, but now
3761 <prgn>objdump</prgn> to do this. The only change this
3762 makes to package building is that
3763 <prgn>dpkg-shlibdeps</prgn> must also be run on shared
3764 libraries, whereas in the past this was unnecessary.
3765 The rest of this footnote explains the advantage that
3770 We say that a binary <tt>foo</tt> <em>directly</em> uses
3771 a library <tt>libbar</tt> if it is explicitly linked
3772 with that library (that is, it uses the flag
3773 <tt>-lbar</tt> during the linking stage). Other
3774 libraries that are needed by <tt>libbar</tt> are linked
3775 <em>indirectly</em> to <tt>foo</tt>, and the dynamic
3776 linker will load them automatically when it loads
3777 <tt>libbar</tt>. A package should needs to depend on
3778 the libraries it directly uses, and the dependencies for
3779 those libraries should automatically pull in the other
3784 Unfortunately, the <prgn>ldd</prgn> program shows both
3785 the directly and indirectly used libraries, meaning that
3786 the dependencies determined included both direct and
3787 indirect dependencies. The use of <prgn>objdump</prgn>
3788 avoids this problem by determining only the directly
3793 A good example of where this helps is the following. We
3794 could update <tt>libimlib</tt> with a new version that
3795 supports a new graphics format called dgf (but retaining
3796 the same major version number). If we used the old
3797 <prgn>ldd</prgn> method, every package that uses
3798 <tt>libimlib</tt> would need to be recompiled so it
3799 would also depend on <tt>libdgf</tt> or it wouldn't run
3800 due to missing symbols. However with the new system,
3801 packages using <tt>libimlib</tt> can rely on
3802 <tt>libimlib</tt> itself having the dependency on
3803 <tt>libdgf</tt> and so they would not need rebuilding.
3809 In the following sections, we will first describe where the
3810 various <tt>shlibs</tt> files are to be found, then how to
3811 use <prgn>dpkg-shlibdeps</prgn>, and finally the
3812 <tt>shlibs</tt> file format and how to create them if your
3813 package contains a shared library.
3817 <sect><heading>The <tt>shlibs</tt> files present on the system
3821 There are several places where <tt>shlibs</tt> files are
3822 found. The following list gives them in the order in which
3823 they are read by <prgn>dpkg-shlibdeps</prgn>. (The first
3824 one which gives the required information is used.)
3830 <p><tt>debian/shlibs.local</tt></p>
3832 This lists overrides for this package. Its use is
3833 described below (see <ref id="shlibslocal">).
3838 <p><tt>/etc/dpkg/shlibs.override</tt></p>
3840 This lists global overrides. This list is normally
3841 empty. It is maintained by the local system
3847 <p><tt>DEBIAN/shlibs</tt> files in the `build directory'</p>
3849 When packages are being built, any
3850 <tt>debian/shlibs</tt> files are copied into the
3851 control file area of the temporary build directory and
3852 given the name <tt>shlibs</tt>. These files give
3853 details of any shared libraries included in the
3856 An example may help here. Let us say that the
3857 source package <tt>foo</tt> generates two binary
3858 packages, <tt>libfoo2</tt> and
3859 <tt>foo-runtime</tt>. When building the binary
3860 packages, the two packages are created in the
3861 directories <tt>debian/libfoo2</tt> and
3862 <tt>debian/foo-runtime</tt> respectively.
3863 (<tt>debian/tmp</tt> could be used instead of one
3864 of these.) Since <tt>libfoo2</tt> provides the
3865 <tt>libfoo</tt> shared library, it will require a
3866 <tt>shlibs</tt> file, which will be installed in
3867 <tt>debian/libfoo2/DEBIAN/shlibs</tt>, eventually
3869 <tt>/var/lib/dpkg/info/libfoo2.shlibs</tt>. Then
3870 when <prgn>dpkg-shlibdeps</prgn> is run on the
3872 <tt>debian/foo-runtime/usr/bin/foo-prog</tt>, it
3874 <tt>debian/libfoo2/DEBIAN/shlibs</tt> file to
3875 determine whether <tt>foo-prog</tt>'s library
3876 dependencies are satisfied by any of the libraries
3877 provided by <tt>libfoo2</tt>. For this reason,
3878 <prgn>dpkg-shlibdeps</prgn> must only be run once
3879 all of the individual binary packages'
3880 <tt>shlibs</tt> files have been installed into the
3888 <p><tt>/var/lib/dpkg/info/*.shlibs</tt></p>
3890 These are the <tt>shlibs</tt> files corresponding to
3891 all of the packages installed on the system, and are
3892 maintained by the relevant package maintainers.
3897 <p><tt>/etc/dpkg/shlibs.default</tt></p>
3899 This file lists any shared libraries whose packages
3900 have failed to provide correct <tt>shlibs</tt> files.
3901 It was used when the <tt>shlibs</tt> setup was first
3902 introduced, but it is now normally empty. It is
3903 maintained by the <tt>dpkg</tt> maintainer.
3911 <heading>How to use <prgn>dpkg-shlibdeps</prgn> and the
3912 <tt>shlibs</tt> files</heading>
3915 Put a call to <prgn>dpkg-shlibdeps</prgn> into your
3916 <tt>debian/rules</tt> file. If your package contains only
3917 compiled binaries and libraries (but no scripts), you can
3918 use a command such as:
3919 <example compact="compact">
3920 dpkg-shlibdeps debian/tmp/usr/bin/* debian/tmp/usr/sbin/* \
3921 debian/tmp/usr/lib/*
3923 Otherwise, you will need to explicitly list the compiled
3924 binaries and libraries.<footnote>
3926 If you are using <tt>debhelper</tt>, the
3927 <prgn>dh_shlibdeps</prgn> program will do this work for
3928 you. It will also correctly handle multi-binary
3935 This command puts the dependency information into the
3936 <tt>debian/substvars</tt> file, which is then used by
3937 <prgn>dpkg-gencontrol</prgn>. You will need to place a
3938 <tt>${shlib:Depends}</tt> variable in the <tt>Depends</tt>
3939 field in the control file for this to work.
3943 If <prgn>dpkg-shlibdeps</prgn> doesn't complain, you're
3944 done. If it does complain you might need to create your own
3945 <tt>debian/shlibs.local</tt> file, as explained below (see
3946 <ref id="shlibslocal">).
3950 If you have multiple binary packages, you will need to call
3951 <prgn>dpkg-shlibdeps</prgn> on each one which contains
3952 compiled libraries or binaries. In such a case, you will
3953 need to use the <tt>-T</tt> option to the <tt>dpkg</tt>
3954 utilities to specify a different <tt>substvars</tt> file.
3955 For more details on this and other options, see <manref
3956 name="dpkg-shlibdeps" section="1">.
3960 <sect id="shlibs"><heading>The <tt>shlibs</tt> File Format
3964 Each <tt>shlibs</tt> file has the same format. Lines
3965 beginning with <tt>#</tt> are considered to be commments and
3966 are ignored. Each line is of the form:
3967 <example compact="compact">
3968 <var>library-name</var> <var>soname-version-number</var> <var>dependencies ...</var>
3973 We will explain this by reference to the example of the
3974 <tt>zlib1g</tt> package, which (at the time of writing)
3975 installs the shared library <tt>/usr/lib/libz.so.1.1.3</tt>.
3979 <var>library-name</var> is the name of the shared library,
3980 in this case <tt>libz</tt>. (This must match the name part
3981 of the soname, see below.)
3985 <var>soname-version-number</var> is the version part of the
3986 soname of the library. The soname is the thing that must
3987 exactly match for the library to be recognized by the
3988 dynamic linker, and is usually of the form
3989 <tt><var>name</var>.so.<var>major-version</var></tt>, in our
3990 example, <tt>libz.so.1</tt>.<footnote>
3992 This can be determined using the command
3993 <example compact="compact">
3994 objdump -p /usr/lib/libz.so.1.1.3 | grep SONAME
3998 The version part is the part which comes after
3999 <tt>.so.</tt>, so in our case, it is <tt>1</tt>.
4003 <var>dependencies</var> has the same syntax as a dependency
4004 field in a binary package control file. It should give
4005 details of which packages are required to satisfy a binary
4006 built against the version of the library contained in the
4007 package. See <ref id="depsyntax"> for details.
4011 In our example, if the first version of the <tt>zlib1g</tt>
4012 package which contained a minor number of at least
4013 <tt>1.3</tt> was <var>1:1.1.3-1</var>, then the
4014 <tt>shlibs</tt> entry for this library could say:
4015 <example compact="compact">
4016 libz 1 zlib1g (>= 1:1.1.3)
4018 The version-specific dependency is to avoid warnings from
4019 the dynamic linker about using older shared libraries with
4025 <heading>Providing a <tt>shlibs</tt> file</heading>
4028 If your package provides a shared library, you should create
4029 a <tt>shlibs</tt> file following the format described above.
4030 It is usual to call this file <tt>debian/shlibs</tt> (but if
4031 you have multiple binary packages, you might want to call it
4032 <tt>debian/shlibs.<var>package</var></tt> instead). Then
4033 let <tt>debian/rules</tt> install it in the control area:
4034 <example compact="compact">
4035 install -m644 debian/shlibs debian/tmp/DEBIAN
4037 or, in the case of a multi-binary package:
4038 <example compact="compact">
4039 install -m644 debian/shlibs.<var>package</var> debian/<var>package</var>/DEBIAN/shlibs
4041 An alternative way of doing this is to create the
4042 <tt>shlibs</tt> file in the control area directly from
4043 <tt>debian/rules</tt> without using a <tt>debian/shlibs</tt>
4044 file at all,<footnote>
4046 This is what <prgn>dh_makeshlibs</prgn> in the
4047 <tt>debhelper</tt> suite does.
4050 since the <tt>debian/shlibs</tt> file itself is ignored by
4051 <prgn>dpkg-shlibdeps</prgn>.
4055 As <prgn>dpkg-shlibdeps</prgn> reads the
4056 <tt>DEBIAN/shlibs</tt> files in all of the binary packages
4057 being built from this source package, all of the
4058 <tt>DEBIAN/shlibs</tt> files should be installed before
4059 <prgn>dpkg-shlibdeps</prgn> is called on any of the binary
4064 <sect id="shlibslocal">
4065 <heading>Writing the <tt>debian/shlibs.local</tt> file</heading>
4068 This file is intended only as a <em>temporary</em> fix if
4069 your binaries or libraries depend on a library whose package
4070 does not yet provide a correct <tt>shlibs</tt> file.
4074 We will assume that you are trying to package a binary
4075 <tt>foo</tt>. When you try running
4076 <prgn>dpkg-shlibdeps</prgn> you get the following error
4077 message (<tt>-O</tt> displays the dependency information on
4078 <tt>stdout</tt> instead of writing it to
4079 <tt>debian/substvars</tt>, and the lines have been wrapped
4080 for ease of reading):
4081 <example compact="compact">
4082 $ dpkg-shlibdeps -O debian/tmp/usr/bin/foo
4083 dpkg-shlibdeps: warning: unable to find dependency
4084 information for shared library libbar (soname 1,
4085 path /usr/lib/libbar.so.1, dependency field Depends)
4086 shlibs:Depends=libc6 (>= 2.2.2-2)
4088 You can then run <prgn>ldd</prgn> on the binary to find the
4089 full location of the library concerned:
4090 <example compact="compact">
4092 libbar.so.1 => /usr/lib/libbar.so.1 (0x4001e000)
4093 libc.so.6 => /lib/libc.so.6 (0x40032000)
4094 /lib/ld-linux.so.2 => /lib/ld-linux.so.2 (0x40000000)
4096 So the <prgn>foo</prgn> binary depends on the
4097 <prgn>libbar</prgn> shared library, but no package seems to
4098 provide a <tt>*.shlibs</tt> file handling
4099 <tt>libbar.so.1</tt> in <tt>/var/lib/dpkg/info/</tt>. Let's
4100 determine the package responsible:
4101 <example compact="compact">
4102 $ dpkg -S /usr/lib/libbar.so.1
4103 bar1: /usr/lib/libbar.so.1
4104 $ dpkg -s bar1 | grep Version
4107 This tells us that the <tt>bar1</tt> package, version 1.0-1,
4108 is the one we are using. Now we can file a bug against the
4109 <tt>bar1</tt> package and create our own
4110 <tt>debian/shlibs.local</tt> to locally fix the problem.
4111 Including the following line into your
4112 <tt>debian/shlibs.local</tt> file:
4113 <example compact="compact">
4114 libbar 1 bar1 (>= 1.0-1)
4116 should allow the package build to work.
4120 As soon as the maintainer of <tt>bar1</tt> provides a
4121 correct <tt>shlibs</tt> file, you should remove this line
4122 from your <tt>debian/shlibs.local</tt> file. (You should
4123 probably also then have a versioned <tt>Build-Depends</tt>
4124 on <tt>bar1</tt> to help ensure that others do not have the
4125 same problem building your package.)
4130 <chapt id="opersys"><heading>The Operating System</heading>
4133 <heading>Filesystem hierarchy</heading>
4137 <heading>Filesystem Structure</heading>
4140 The location of all installed files and directories must
4141 comply with the Filesystem Hierarchy Standard (FHS),
4142 except where doing so would violate other terms of Debian
4143 Policy. The latest version of this document can be found
4144 in the <tt>debian-policy</tt> package or on
4145 <url id="http://www.debian.org/doc/packaging-manuals/fhs"
4146 name="FHS (Debian copy)"> alongside this manual or on
4147 <url id="http://www.pathname.com/fhs/" name="FHS (upstream)">.
4148 Specific questions about following the standard may be
4149 asked on the <tt>debian-devel</tt> mailing list, or
4150 referred to Daniel Quinlan, the FHS coordinator, at
4151 <email>quinlan@pathname.com</email>.
4156 <heading>Site-specific programs</heading>
4159 As mandated by the FHS, packages must not place any
4160 files in <tt>/usr/local</tt>, either by putting them in
4161 the file system archive to be unpacked by <prgn>dpkg</prgn>
4162 or by manipulating them in their maintainer scripts.
4166 However, the package may create empty directories below
4167 <tt>/usr/local</tt> so that the system administrator knows
4168 where to place site-specific files. These directories
4169 should be removed on package removal if they are
4174 Note, that this applies only to directories <em>below</em>
4175 <tt>/usr/local</tt>, not <em>in</em> <tt>/usr/local</tt>.
4176 Packages must not create sub-directories in the directory
4177 <tt>/usr/local</tt> itself, except those listed in FHS,
4178 section 4.5. However, you may create directories below
4179 them as you wish. You must not remove any of the
4180 directories listed in 4.5, even if you created them.
4184 Since <tt>/usr/local</tt> can be mounted read-only from a
4185 remote server, these directories must be created and
4186 removed by the <prgn>postinst</prgn> and <prgn>prerm</prgn>
4187 maintainer scripts and not be included in the
4188 <tt>.deb</tt> archive. These scripts must not fail if
4189 either of these operations fail.
4193 For example, the <tt>emacsen-common</tt> package could
4194 contain something like
4195 <example compact="compact">
4196 if [ ! -e /usr/local/share/emacs ]
4198 if mkdir /usr/local/share/emacs 2>/dev/null
4200 chown root:staff /usr/local/share/emacs
4201 chmod 2775 /usr/local/share/emacs
4205 in its <prgn>postinst</prgn> script, and
4206 <example compact="compact">
4207 rmdir /usr/local/share/emacs/site-lisp 2>/dev/null || true
4208 rmdir /usr/local/share/emacs 2>/dev/null || true
4210 in the <prgn>prerm</prgn> script. (Note that this form is
4211 used to ensure that if the script is interrupted, the
4212 directory <tt>/usr/local/share/emacs</tt> will still be
4217 If you do create a directory in <tt>/usr/local</tt> for
4218 local additions to a package, you should ensure that
4219 settings in <tt>/usr/local</tt> take precedence over the
4220 equivalents in <tt>/usr</tt>.
4224 However, because <tt>/usr/local</tt> and its contents are
4225 for exclusive use of the local administrator, a package
4226 must not rely on the presence or absence of files or
4227 directories in <tt>/usr/local</tt> for normal operation.
4231 The <tt>/usr/local</tt> directory itself and all the
4232 subdirectories created by the package should (by default) have
4233 permissions 2775 (group-writable and set-group-id) and be
4234 owned by <tt>root.staff</tt>.
4239 <heading>The system-wide mail directory</heading>
4241 The system-wide mail directory is <tt>/var/mail</tt>. This
4242 directory is part of the base system and should not owned
4243 by any particular mail agents. The use of the old
4244 location <tt>/var/spool/mail</tt> is deprecated, even
4245 though the spool may still be physically located there.
4246 To maintain partial upgrade compatibility for systems
4247 which have <tt>/var/spool/mail</tt> as their physical mail
4248 spool, packages using <tt>/var/mail</tt> must depend on
4249 either <package>libc6</package> (>= 2.1.3-13), or on
4250 <package>base-files</package> (>= 2.2.0), or on later
4251 versions of either one of these packages.
4257 <heading>Users and groups</heading>
4260 <heading>Introduction</heading>
4262 The Debian system can be configured to use either plain or
4267 Some user ids (UIDs) and group ids (GIDs) are reserved
4268 globally for use by certain packages. Because some
4269 packages need to include files which are owned by these
4270 users or groups, or need the ids compiled into binaries,
4271 these ids must be used on any Debian system only for the
4272 purpose for which they are allocated. This is a serious
4273 restriction, and we should avoid getting in the way of
4274 local administration policies. In particular, many sites
4275 allocate users and/or local system groups starting at 100.
4279 Apart from this we should have dynamically allocated ids,
4280 which should by default be arranged in some sensible
4281 order, but the behavior should be configurable.
4285 Packages other than <tt>base-passwd</tt> must not modify
4286 <tt>/etc/passwd</tt>, <tt>/etc/shadow</tt>,
4287 <tt>/etc/group</tt> or <tt>/etc/gshadow</tt>.
4292 <heading>UID and GID classes</heading>
4294 The UID and GID numbers are divided into classes as
4300 Globally allocated by the Debian project, the same
4301 on every Debian system. These ids will appear in
4302 the <tt>passwd</tt> and <tt>group</tt> files of all
4303 Debian systems, new ids in this range being added
4304 automatically as the <tt>base-passwd</tt> package is
4309 Packages which need a single statically allocated
4310 uid or gid should use one of these; their
4311 maintainers should ask the <tt>base-passwd</tt>
4319 Dynamically allocated system users and groups.
4320 Packages which need a user or group, but can have
4321 this user or group allocated dynamically and
4322 differently on each system, should use <tt>adduser
4323 --system</tt> to create the group and/or user.
4324 <prgn>adduser</prgn> will check for the existence of
4325 the user or group, and if necessary choose an unused
4326 id based on the ranges specified in
4327 <tt>adduser.conf</tt>.
4331 <tag>1000-29999:</tag>
4334 Dynamically allocated user accounts. By default
4335 <prgn>adduser</prgn> will choose UIDs and GIDs for
4336 user accounts in this range, though
4337 <tt>adduser.conf</tt> may be used to modify this
4342 <tag>30000-59999:</tag>
4347 <tag>60000-64999:</tag>
4350 Globally allocated by the Debian project, but only
4351 created on demand. The ids are allocated centrally
4352 and statically, but the actual accounts are only
4353 created on users' systems on demand.
4357 These ids are for packages which are obscure or
4358 which require many statically-allocated ids. These
4359 packages should check for and create the accounts in
4360 <tt>/etc/passwd</tt> or <tt>/etc/group</tt> (using
4361 <prgn>adduser</prgn> if it has this facility) if
4362 necessary. Packages which are likely to require
4363 further allocations should have a `hole' left after
4364 them in the allocation, to give them room to
4369 <tag>65000-65533:</tag>
4377 User <tt>nobody</tt>. The corresponding gid refers
4378 to the group <tt>nogroup</tt>.
4385 <tt>(uid_t)(-1) == (gid_t)(-1)</tt> <em>must
4386 not</em> be used, because it is the error return
4395 <sect id="sysvinit">
4396 <heading>System run levels and <tt>init.d</tt> scripts</heading>
4398 <sect1 id="/etc/init.d">
4399 <heading>Introduction</heading>
4402 The <tt>/etc/init.d</tt> directory contains the scripts
4403 executed by <prgn>init</prgn> at boot time and when the
4404 init state (or `runlevel') is changed (see <manref
4405 name="init" section="8">).
4409 There are at least two different, yet functionally
4410 equivalent, ways of handling these scripts. For the sake
4411 of simplicity, this document describes only the symbolic
4412 link method. However, it must not be assumed by maintainer
4413 scripts that this method is being used, and any automated
4414 manipulation of the various runlevel behaviours by
4415 maintainer scripts must be performed using
4416 <prgn>update-rc.d</prgn> as described below and not by
4417 manually installing or removing symlinks. For information
4418 on the implementation details of the other method,
4419 implemented in the <tt>file-rc</tt> package, please refer
4420 to the documentation of that package.
4424 These scripts are referenced by symbolic links in the
4425 <tt>/etc/rc<var>n</var>.d</tt> directories. When changing
4426 runlevels, <prgn>init</prgn> looks in the directory
4427 <tt>/etc/rc<var>n</var>.d</tt> for the scripts it should
4428 execute, where <tt><var>n</var></tt> is the runlevel that
4429 is being changed to, or <tt>S</tt> for the boot-up
4434 The names of the links all have the form
4435 <tt>S<var>mm</var><var>script</var></tt> or
4436 <tt>K<var>mm</var><var>script</var></tt> where
4437 <var>mm</var> is a two-digit number and <var>script</var>
4438 is the name of the script (this should be the same as the
4439 name of the actual script in <tt>/etc/init.d</tt>).
4443 When <prgn>init</prgn> changes runlevel first the targets
4444 of the links whose names start with a <tt>K</tt> are
4445 executed, each with the single argument <tt>stop</tt>,
4446 followed by the scripts prefixed with an <tt>S</tt>, each
4447 with the single argument <tt>start</tt>. (The links are
4448 those in the <tt>/etc/rc<var>n</var>.d</tt> directory
4449 corresponding to the new runlevel.) The <tt>K</tt> links
4450 are responsible for killing services and the <tt>S</tt>
4451 link for starting services upon entering the runlevel.
4455 For example, if we are changing from runlevel 2 to
4456 runlevel 3, init will first execute all of the <tt>K</tt>
4457 prefixed scripts it finds in <tt>/etc/rc3.d</tt>, and then
4458 all of the <tt>S</tt> prefixed scripts in that directory.
4459 The links starting with <tt>K</tt> will cause the
4460 referred-to file to be executed with an argument of
4461 <tt>stop</tt>, and the <tt>S</tt> links with an argument
4466 The two-digit number <var>mm</var> is used to determine
4467 the order in which to run the scripts: low-numbered links
4468 have their scripts run first. For example, the
4469 <tt>K20</tt> scripts will be executed before the
4470 <tt>K30</tt> scripts. This is used when a certain service
4471 must be started before another. For example, the name
4472 server <prgn>bind</prgn> might need to be started before
4473 the news server <prgn>inn</prgn> so that <prgn>inn</prgn>
4474 can set up its access lists. In this case, the script
4475 that starts <prgn>bind</prgn> would have a lower number
4476 than the script that starts <prgn>inn</prgn> so that it
4478 <example compact="compact">
4485 The two runlevels 0 (halt) and 6 (reboot) are slightly
4486 different. In these runlevels, the links with an
4487 <tt>S</tt> prefix are still called after those with a
4488 <tt>K</tt> prefix, but they too are called with the single
4489 argument <tt>stop</tt>.
4493 Also, if the script name ends <tt>.sh</tt>, the script
4494 will be sourced in runlevel <tt>S</tt> rather that being
4495 run in a forked subprocess, but will be explicitly run by
4496 <prgn>sh</prgn> in all other runlevels.
4501 <heading>Writing the scripts</heading>
4504 Packages that include daemons for system services should
4505 place scripts in <tt>/etc/init.d</tt> to start or stop
4506 services at boot time or during a change of runlevel.
4507 These scripts should be named
4508 <tt>/etc/init.d/<var>package</var></tt>, and they should
4509 accept one argument, saying what to do:
4512 <tag><tt>start</tt></tag>
4513 <item><p>start the service,</p></item>
4515 <tag><tt>stop</tt></tag>
4516 <item><p>stop the service,</p></item>
4518 <tag><tt>restart</tt></tag>
4519 <item><p>stop and restart the service,</p></item>
4521 <tag><tt>reload</tt></tag>
4522 <item><p>cause the configuration of the service to be
4523 reloaded without actually stopping and restarting
4524 the service,</p></item>
4526 <tag><tt>force-reload</tt></tag>
4527 <item><p>cause the configuration to be reloaded if the
4528 service supports this, otherwise restart the
4532 The <tt>start</tt>, <tt>stop</tt>, <tt>restart</tt>, and
4533 <tt>force-reload</tt> options should be supported by all
4534 scripts in <tt>/etc/init.d</tt>, the <tt>reload</tt>
4535 option is optional.</p>
4538 The <tt>init.d</tt> scripts should ensure that they will
4539 behave sensibly if invoked with <tt>start</tt> when the
4540 service is already running, or with <tt>stop</tt> when it
4541 isn't, and that they don't kill unfortunately-named user
4542 processes. The best way to achieve this is usually to use
4543 <prgn>start-stop-daemon</prgn>.</p>
4546 If a service reloads its configuration automatically (as
4547 in the case of <prgn>cron</prgn>, for example), the
4548 <tt>reload</tt> option of the <tt>init.d</tt> script
4549 should behave as if the configuration has been reloaded
4553 The <tt>/etc/init.d</tt> scripts should be treated as
4554 configuration files, either by marking them as
4555 <tt>conffile</tt>s or managing them correctly in the
4556 maintainer scripts (see <ref id="config files">). This is
4557 important since we want to give the local system
4558 administrator the chance to adapt the scripts to the local
4559 system, e.g., to disable a service without de-installing
4560 the package, or to specify some special command line
4561 options when starting a service, while making sure her
4562 changes aren't lost during the next package upgrade.
4566 These scripts should not fail obscurely when the
4567 configuration files remain but the package has been
4568 removed, as configuration files remain on the system after
4569 the package has been removed. Only when <prgn>dpkg</prgn>
4570 is executed with the <tt>--purge</tt> option will
4571 configuration files be removed. In particular, as the
4572 <tt>/etc/init.d/<var>package</var></tt> script itself is
4573 usually a <tt>conffile</tt>, it will remain on the system
4574 if the package is removed but not purged. Therefore, you
4575 should include a <tt>test</tt> statement at the top of the
4577 <example compact="compact">
4578 test -f <var>program-executed-later-in-script</var> || exit 0
4583 Often there are some variables in the <tt>init.d</tt>
4584 scripts whose values control the bahaviour of the scripts,
4585 and which a system administrator is likely to want to
4586 change. As the scripts themselves are frequently
4587 <tt>conffile</tt>s, modifying them requires that the
4588 administrator merge in their changes each time the package
4589 is upgraded and the <tt>conffile</tt> changes. To ease
4590 the burden on the system administrator, such configurable
4591 values should not be placed directly in the script.
4592 Instead, they should be placed in a file in
4593 <tt>/etc/default</tt>, which typically will have the same
4594 base name as the <tt>init.d</tt> script. This extra file
4595 should be sourced by the script when the script runs. It
4596 must contain only variable settings and comments in POSIX
4597 <prgn>sh</prgn> format. It may either be a
4598 <tt>conffile</tt> or a configuration file maintained by
4599 the package maintainer scripts. See <ref id="config
4600 files"> for more details.
4604 To ensure that vital configurable values are always
4605 available, the <tt>init.d</tt> script should set default
4606 values for each of the shell variables it uses, either
4607 before sourcing the <tt>/etc/default/</tt> file or
4608 afterwards using something like the <tt>:
4609 ${VAR:=default}</tt> syntax. Also, the <tt>init.d</tt>
4610 script must behave sensibly and not fail if the
4611 <tt>/etc/default</tt> file is deleted.
4616 <heading>Managing the links</heading>
4619 The program <prgn>update-rc.d</prgn> is provided for
4620 package maintainers to arrange for the proper creation and
4621 removal of <tt>/etc/rc<var>n</var>.d</tt> symbolic links,
4622 or their functional equivalent if another method is being
4623 used. This may be used by maintainers in their packages'
4624 <prgn>postinst</prgn> and <prgn>postrm</prgn> scripts.</p>
4627 You must not include any <tt>/etc/rc<var>n</var>.d</tt>
4628 symbolic links in the actual archive or manually create or
4629 remove the symbolic links in maintainer scripts; you must
4630 use the <prgn>update-rc.d</prgn> program instead. (The
4631 former will fail if an alternative method of maintaining
4632 runlevel information is being used.) You must not include
4633 the <tt>/etc/rc<var>n</var>.d</tt> directories themselves
4634 in the archive either. (Only the <tt>sysvinit</tt>
4639 By default <prgn>update-rc.d</prgn> will start services in
4640 each of the multi-user state runlevels (2, 3, 4, and 5)
4641 and stop them in the halt runlevel (0), the single-user
4642 runlevel (1) and the reboot runlevel (6). The system
4643 administrator will have the opportunity to customize
4644 runlevels by simply adding, moving, or removing the
4645 symbolic links in <tt>/etc/rc<var>n</var>.d</tt> if
4646 symbolic links are being used, or by modifying
4647 <tt>/etc/runlevel.conf</tt> if the <tt>file-rc</tt> method
4652 To get the default behavior for your package, put in your
4653 <prgn>postinst</prgn> script
4654 <example compact="compact">
4655 update-rc.d <var>package</var> defaults >/dev/null
4657 and in your <prgn>postrm</prgn>
4658 <example compact="compact">
4659 if [ "$1" = purge ]; then
4660 update-rc.d <var>package</var> remove >/dev/null
4665 This will use a default sequence number of 20. If it does
4666 not matter when or in which order the <tt>init.d</tt>
4667 script is run, use this default. If it does, then you
4668 should talk to the maintainer of the <prgn>sysvinit</prgn>
4669 package or post to <tt>debian-devel</tt>, and they will
4670 help you choose a number.
4674 For more information about using <tt>update-rc.d</tt>,
4675 please consult its manpage <manref name="update-rc.d"
4682 <heading>Boot-time initialization</heading>
4685 There used to be another directory, <tt>/etc/rc.boot</tt>,
4686 which contained scripts which were run once per machine
4687 boot. This has been deprecated in favour of links from
4688 <tt>/etc/rcS.d</tt> to files in <tt>/etc/init.d</tt> as
4689 described in <ref id="/etc/init.d">. Packages must not
4690 place files in <tt>/etc/rc.boot</tt>.</p>
4693 <heading>Example</heading>
4696 The <prgn>bind</prgn> DNS (nameserver) package wants to
4697 make sure that the nameserver is running in multiuser
4698 runlevels, and is properly shut down with the system. It
4699 puts a script in <tt>/etc/init.d</tt>, naming the script
4700 appropriately <tt>bind</tt>. As you can see, the script
4701 interprets the argument <tt>reload</tt> to send the
4702 nameserver a <tt>HUP</tt> signal (causing it to reload its
4703 configuration); this way the system administrator can say
4704 <tt>/etc/init.d/bind reload</tt> to reload the name
4705 server. The script has one configurable value, which can
4706 be used to pass parameters to the named program at
4707 startup; this value is read from
4708 <tt>/etc/default/bind</tt> (see below).
4712 <example compact="compact">
4715 # Original version by Robert Leslie
4716 # <rob@mars.org>, edited by iwj and cs
4718 test -x /usr/sbin/named || exit 0
4720 # Source defaults file.
4722 if [ -f /etc/default/bind ]; then
4729 echo -n "Starting domain name service: named"
4730 start-stop-daemon --start --quiet --exec /usr/sbin/named \
4735 echo -n "Stopping domain name service: named"
4736 start-stop-daemon --stop --quiet \
4737 --pidfile /var/run/named.pid --exec /usr/sbin/named
4741 echo -n "Restarting domain name service: named"
4742 start-stop-daemon --stop --quiet \
4743 --pidfile /var/run/named.pid --exec /usr/sbin/named
4744 start-stop-daemon --start --verbose --exec /usr/sbin/named \
4748 force-reload|reload)
4749 echo -n "Reloading configuration of domain name service: named"
4750 start-stop-daemon --stop --signal 1 --quiet \
4751 --pidfile /var/run/named.pid --exec /usr/sbin/named
4755 echo "Usage: /etc/init.d/bind {start|stop|restart|reload|force-reload}" >&2
4765 Complementing the above init script is a configuration
4766 file <tt>/etc/default/bind</tt>, which contains
4767 configurable parameters used by the script. This would be
4768 created by the <prgn>postinst</prgn> script if it was not
4769 already present, and removed on purge by the
4770 <prgn>postrm</prgn> script.
4771 <example compact="compact">
4772 # Specified parameters to pass to named. See named(8).
4773 # You may uncomment the following line, and edit to taste.
4779 Another example on which you can base your
4780 <tt>/etc/init.d</tt> scripts is found in
4781 <tt>/etc/init.d/skeleton</tt>.
4785 If this package is happy with the default setup from
4786 <prgn>update-rc.d</prgn>, namely an ordering number of 20
4787 and having named running in all runlevels, it can say in
4788 its <prgn>postinst</prgn>:
4789 <example compact="compact">
4790 update-rc.d bind defaults >/dev/null
4792 And in its <prgn>postrm</prgn>, to remove the links when the
4794 <example compact="compact">
4795 if [ "$1" = purge ]; then
4796 update-rc.d bind remove >/dev/null
4804 <heading>Console messages from <tt>init.d</tt> scripts</heading>
4807 This section describes the formats to be used for messages
4808 written to standard output by the <tt>/etc/init.d</tt>
4809 scripts. The intent is to improve the consistency of
4810 Debian's startup and shutdown look and feel. For this
4811 reason, please look very carefully at the details. We want
4812 the messages to have the same format in terms of wording,
4813 spaces, punctuation and case of letters.
4817 Here is a list of overall rules that you should use when you
4818 create output messages. They can be useful if you have a
4819 non-standard message that is not covered specifically in the
4827 Every message should fit in one line (fewer than 80
4828 characters), start with a capital letter and end with
4829 a period (<tt>.</tt>) and line feed (<tt>"\n"</tt>).
4835 If you want to express that the computer is working on
4836 something (that is, performing a specific task, not
4837 starting or stopping a program), we use an "ellipsis"
4838 (three dots: <tt>...</tt>). Note that we don't insert
4839 spaces before or after the dots. If the task has been
4840 completed we write <tt>done.</tt> and a line feed.
4846 Design your messages as if the computer is telling you
4847 what he is doing (let him be polite :-), but don't
4848 mention "him" directly. For example, if you think of
4850 <example compact="compact">
4851 I'm starting network daemons: nfsd mountd.
4854 <example compact="compact">
4855 Starting network daemons: nfsd mountd.
4863 There are standard message formats for the following
4864 situations. They should be used by the <tt>init.d</tt>
4871 <p>When daemons are started</p>
4874 If your script starts one or more daemons, the output
4875 should look like this (a single line, no leading
4877 <example compact="compact">
4878 Starting <var>description</var>: <var>daemon-1</var> ... <var>daemon-n</var>.
4880 The <var>description</var> should describe the
4881 subsystem the daemon or set of daemons are part of,
4882 while <var>daemon-1</var> up to <var>daemon-n</var>
4883 denote each daemon's name (typically the file name of
4888 For example, the output of <tt>/etc/init.d/lpd</tt>
4890 <example compact="compact">
4891 Starting printer spooler: lpd.
4896 This can be achieved by saying
4897 <example compact="compact">
4898 echo -n "Starting printer spooler: lpd"
4899 start-stop-daemon --start --quiet --exec /usr/sbin/lpd
4902 in the script. If you have more than one daemon to
4903 start, you should do the following:
4904 <example compact="compact">
4905 echo -n "Starting remote file system services:"
4906 echo -n " nfsd"; start-stop-daemon --start --quiet nfsd
4907 echo -n " mountd"; start-stop-daemon --start --quiet mountd
4908 echo -n " ugidd"; start-stop-daemon --start --quiet ugidd
4911 This makes it possible for the user to see what takes
4912 so long and when the final daemon has been started.
4913 You should be careful where to put spaces: in the
4914 example above the system administrator can easily
4915 comment out a line if he don't wants to start a
4916 specific daemon, while the displayed message still
4922 <p>When a system parameter is being set</p>
4925 If you have to set up different system parameters
4926 during the system boot, you should use this format:
4927 <example compact="compact">
4928 Setting <var>parameter</var> to `<var>value</var>'.
4933 You can use a statement such as the following to get
4935 <example compact="compact">
4936 echo "Setting DNS domainname to \`$domainname'."
4941 Note that the left quotation mark (<tt>`</tt>) is
4942 different from the right one (<tt>'</tt>).
4947 <p>When a daemon is stopped or restarted</p>
4950 When you stop or restart a daemon, you should issue a
4951 message identical to the startup message, except that
4952 <tt>Starting</tt> is replaced with <tt>Stopping</tt>
4953 or <tt>Restarting</tt> respectively.
4957 For example, stopping the printer daemon will like
4959 <example compact="compact">
4960 Stopping printer spooler: lpd.
4966 <p>When something is executed</p>
4969 There are several examples where you have to run a
4970 program at system startup or shutdown to perform a
4971 specific task, for example, setting the system's clock
4972 using <prgn>netdate</prgn> or killing all processes
4973 when the system shuts down. Your message should look
4975 <example compact="compact">
4976 Doing something very useful...done.
4978 You should print the <tt>done.</tt> immediately after
4979 the job has been completed, so that the user is
4980 informed why she has to wait. You can get this
4982 <example compact="compact">
4983 echo -n "Doing something very useful..."
4992 <p>When the configuration is reloaded</p>
4995 When a daemon is forced to reload its configuration
4996 files you should use the following format:
4997 <example compact="compact">
4998 Reloading <var>description</var> configuration...done.
5000 where <var>description</var> is the same as in the
5001 daemon starting message.
5009 <heading>Cron jobs</heading>
5012 Packages must not modify the configuration file
5013 <tt>/etc/crontab</tt>, and they must not modify the files in
5014 <tt>/var/spool/cron/crontabs</tt>.</p>
5017 If a package wants to install a job that has to be executed
5018 via cron, it should place a file with the name of the
5019 package in one or more of the following directories:
5020 <example compact="compact">
5025 As these directory names imply, the files within them are
5026 executed on a daily, weekly, or monthly basis,
5027 respectively. The exact times are listed in
5028 <tt>/etc/crontab</tt>.</p>
5031 All files installed in any of these directories must be
5032 scripts (e.g., shell scripts or Perl scripts) so that they
5033 can easily be modified by the local system administrator.
5034 In addition, they should be treated as configuration
5039 If a certain job has to be executed more frequently than
5040 daily, the package should install a file
5041 <tt>/etc/cron.d/<var>package</var></tt>. This file uses the
5042 same syntax as <tt>/etc/crontab</tt> and is processed by
5043 <prgn>cron</prgn> automatically. The file must also be
5044 treated as a configuration file. (Note that entries in the
5045 <tt>/etc/cron.d</tt> directory are not handled by
5046 <prgn>anacron</prgn>. Thus, you should only use this
5047 directory for jobs which may be skipped if the system is not
5051 The scripts or crontab entries in these directories should
5052 check if all necessary programs are installed before they
5053 try to execute them. Otherwise, problems will arise when a
5054 package was removed but not purged since configuration files
5055 are kept on the system in this situation.</p>
5059 <heading>Menus</heading>
5062 Menu entries should follow the current menu policy found in
5063 the <tt>menu-policy</tt> files in the <tt>debian-policy</tt>
5064 package. It may also be found on the Debian FTP site
5065 <ftpsite>ftp.debian.org</ftpsite> as the file
5066 <ftppath>/debian/doc/package-developer/menu-policy.txt.gz</ftppath>,
5067 or in the equivalent location on your local mirror.
5071 The Debian <tt>menu</tt> package provides a standard
5072 interface between packages providing applications and
5073 documents, and <em>menu programs</em> (either X window
5074 managers or text-based menu programs such as
5075 <prgn>pdmenu</prgn>).
5079 All packages that provide applications that need not be
5080 passed any special command line arguments for normal
5081 operation should register a menu entry for those
5082 applications, so that users of the <tt>menu</tt> package
5083 will automatically get menu entries in their window
5084 managers, as well in shells like <tt>pdmenu</tt>.</p>
5087 Please also refer to the <em>Debian Menu System</em>
5088 documentation that comes with the <tt>menu</tt> package for
5089 information about how to register your applications and web
5095 <heading>Multimedia handlers</heading>
5098 Packages which provide the ability to view/show/play,
5099 compose, edit or print MIME types should register themselves
5100 as such following the current MIME support policy found in
5101 the <tt>mime-policy</tt> files in the <tt>debian-policy</tt>
5102 package. It may also be found on the Debian FTP site
5103 <ftpsite>ftp.debian.org</ftpsite> as the file
5104 <ftppath>/debian/doc/package-developer/mime-policy.txt.gz</ftppath>,
5105 or in the equivalent location on your local mirror.
5109 MIME (Multipurpose Internet Mail Extensions, RFCs 2045-2049)
5110 is a mechanism for encoding files and data streams and
5111 providing meta-information about them, in particular their
5112 type (e.g. audio or video) and format (e.g. PNG, HTML,
5117 Registration of MIME type handlers allows programs like mail
5118 user agents and web browsers to to invoke these handlers to
5119 view, edit or display MIME types they don't support
5125 <heading>Keyboard configuration</heading>
5128 To achieve a consistent keyboard configuration so that all
5129 applications interpret a keyboard event the same way, all
5130 programs in the Debian distribution must be configured to
5131 comply with the following guidelines.
5135 The following keys must have the specified interpretations:
5138 <tag><tt><--</tt></tag>
5139 <item><p>delete the character to the left of the cursor</p></item>
5141 <tag><tt>Delete</tt></tag>
5142 <item><p>delete the character to the right of the cursor</p></item>
5144 <tag><tt>Control+H</tt></tag>
5145 <item><p>emacs: the help prefix</p></item>
5148 The interpretation of any keyboard events should be
5149 independent of the terminal that is used, be it a virtual
5150 console, an X terminal emulator, an rlogin/telnet session,
5155 The following list explains how the different programs
5156 should be set up to achieve this:
5161 <item><p><tt><--</tt> generates <tt>KB_Backspace</tt>
5164 <item><p><tt>Delete</tt> generates <tt>KB_Delete</tt> in
5169 X translations are set up to make
5170 <tt>KB_Backspace</tt> generate ASCII DEL, and to make
5171 <tt>KB_Delete</tt> generate <tt>ESC [ 3 ~</tt> (this
5172 is the vt220 escape code for the `delete character'
5173 key). This must be done by loading the X resources
5174 using <prgn>xrdb</prgn> on all local X displays, not
5175 using the application defaults, so that the
5176 translation resources used correspond to the
5177 <prgn>xmodmap</prgn> settings.</p></item>
5181 The Linux console is configured to make
5182 <tt><--</tt> generate DEL, and <tt>Delete</tt>
5183 generate <tt>ESC [ 3 ~</tt>.</p></item>
5187 X applications are configured so that <tt><</tt>
5188 deletes left, and <tt>Delete</tt> deletes right. Motif
5189 applications already work like this.</p></item>
5191 <item><p>Terminals should have <tt>stty erase ^?</tt> .</p></item>
5195 The <tt>xterm</tt> terminfo entry should have <tt>ESC
5196 [ 3 ~</tt> for <tt>kdch1</tt>, just as for
5197 <tt>TERM=linux</tt> and <tt>TERM=vt220</tt>.</p></item>
5201 Emacs is programmed to map <tt>KB_Backspace</tt> or
5202 the <tt>stty erase</tt> character to
5203 <tt>delete-backward-char</tt>, and <tt>KB_Delete</tt>
5204 or <tt>kdch1</tt> to <tt>delete-forward-char</tt>, and
5205 <tt>^H</tt> to <tt>help</tt> as always.</p></item>
5209 Other applications use the <tt>stty erase</tt>
5210 character and <tt>kdch1</tt> for the two delete keys,
5211 with ASCII DEL being `delete previous character' and
5212 <tt>kdch1</tt> being `delete character under
5219 This will solve the problem except for the following
5227 Some terminals have a <tt><--</tt> key that cannot
5228 be made to produce anything except <tt>^H</tt>. On
5229 these terminals Emacs help will be unavailable on
5230 <tt>^H</tt> (assuming that the <tt>stty erase</tt>
5231 character takes precedence in Emacs, and has been set
5232 correctly). <tt>M-x help</tt> or <tt>F1</tt> (if
5233 available) can be used instead.</p></item>
5237 Some operating systems use <tt>^H</tt> for <tt>stty
5238 erase</tt>. However, modern telnet versions and all
5239 rlogin versions propagate <tt>stty</tt> settings, and
5240 almost all UNIX versions honour <tt>stty erase</tt>.
5241 Where the <tt>stty</tt> settings are not propagated
5242 correctly, things can be made to work by using
5243 <tt>stty</tt> manually.</p></item>
5247 Some systems (including previous Debian versions) use
5248 <prgn>xmodmap</prgn> to arrange for both
5249 <tt><--</tt> and <tt>Delete</tt> to generate
5250 <tt>KB_Delete</tt>. We can change the behavior of
5251 their X clients using the same X resources that we use
5252 to do it for our own clients, or configure our clients
5253 using their resources when things are the other way
5254 around. On displays configured like this
5255 <tt>Delete</tt> will not work, but <tt><--</tt>
5260 Some operating systems have different <tt>kdch1</tt>
5261 settings in their <tt>terminfo</tt> database for
5262 <tt>xterm</tt> and others. On these systems the
5263 <tt>Delete</tt> key will not work correctly when you
5264 log in from a system conforming to our policy, but
5265 <tt><--</tt> will.</p></item>
5271 <heading>Environment variables</heading>
5274 A program must not depend on environment variables to get
5275 reasonable defaults. (That's because these environment
5276 variables would have to be set in a system-wide
5277 configuration file like <tt>/etc/profile</tt>, which is not
5278 supported by all shells.)</p>
5281 If a program usually depends on environment variables for its
5282 configuration, the program should be changed to fall back to
5283 a reasonable default configuration if these environment
5284 variables are not present. If this cannot be done easily
5285 (e.g., if the source code of a non-free program is not
5286 available), the program must be replaced by a small
5287 `wrapper' shell script which sets the environment variables
5288 if they are not already defined, and calls the original program.</p>
5291 Here is an example of a wrapper script for this purpose:
5293 <example compact="compact">
5295 BAR=${BAR:-/var/lib/fubar}
5297 exec /usr/lib/foo/foo "$@"
5302 Furthermore, as <tt>/etc/profile</tt> is a configuration
5303 file of the <prgn>base-files</prgn> package, other packages must not
5304 put any environment variables or other commands into that
5310 <heading>Files</heading>
5313 <heading>Binaries</heading>
5316 Two different packages must not install programs with
5317 different functionality but with the same filenames. (The
5318 case of two programs having the same functionality but
5319 different implementations is handled via `alternatives' or
5320 the `Conflicts' mechanism. See <ref id="maintscripts"> and
5321 <ref id="conflicts"> respectively.) If this case happens,
5322 one of the programs must be renamed. The maintainers should
5323 report this to the <tt>debian-devel</tt> mailing list and
5324 try to find a consensus about which program will have to be
5325 renamed. If a consensus cannot be reached, <em>both</em>
5326 programs must be renamed.
5330 Generally the following compilation parameters should be used:
5331 <example compact="compact">
5333 CFLAGS = -O2 -Wall # sane warning options vary between programs
5335 install -s # (or use strip on the files in debian/tmp)
5339 Note that by default all installed binaries should be stripped,
5340 either by using the <tt>-s</tt> flag to
5341 <prgn>install</prgn>, or by calling <prgn>strip</prgn> on
5342 the binaries after they have been copied into
5343 <tt>debian/tmp</tt> but before the tree is made into a
5347 The <tt>-N</tt> flag should not be used. On <tt>a.out</tt>
5348 systems it may have been useful for some very small
5349 binaries, but for ELF it has no good effect.</p>
5352 Debugging symbols are useful for error diagnosis,
5353 investigation of core dumps (which may be submitted by users
5354 in bug reports), or testing and developing the software.
5355 Therefore it is recommended to support building the package
5356 with debugging information through the following interface:
5357 If the environment variable <tt>DEB_BUILD_OPTIONS</tt>
5358 contains the string <tt>debug</tt>, compile the software
5359 with debugging information (usually this involves adding the
5360 <tt>-g</tt> flag to <tt>CFLAGS</tt>). This allows the
5361 generation of a build tree with debugging information. If
5362 the environment variable <tt>DEB_BUILD_OPTIONS</tt> contains
5363 the string <tt>nostrip</tt>, do not strip the files at
5364 installation time. This allows one to generate a package
5365 with debugging information included.<footnote>
5367 Rationale: Using <tt>-g</tt> by default causes wasted
5368 CPU cycles since the information is stripped away
5369 anyway; this can have a significant impact on the
5370 efficiency of the autobuilders. Having a standard way
5371 to build a debugging variant also makes it easier to
5372 build debugging bins and libraries since it provides a
5373 documented way of getting this type of build; one does
5374 not have to manually edit <tt>debian/rules</tt> or
5378 The following makefile snippet is an example of how one may
5379 test for either condition; you will probably have to massage
5380 this example in order to make it work for your package.
5381 <example compact="compact">
5384 INSTALL_FILE = $(INSTALL) -p -o root -g root -m 644
5385 INSTALL_PROGRAM = $(INSTALL) -p -o root -g root -m 755
5386 INSTALL_SCRIPT = $(INSTALL) -p -o root -g root -m 755
5387 INSTALL_DIR = $(INSTALL) -p -d -o root -g root -m 755
5389 ifneq (,$(findstring debug,$(DEB_BUILD_OPTIONS)))
5392 ifeq (,$(findstring nostrip,$(DEB_BUILD_OPTIONS)))
5393 INSTALL_PROGRAM += -s
5399 It is up to the package maintainer to decide what
5400 compilation options are best for the package. Certain
5401 binaries (such as computationally-intensive programs) will
5402 function better with certain flags (<tt>-O3</tt>, for
5403 example); feel free to use them. Please use good judgment
5404 here. Don't use flags for the sake of it; only use them
5405 if there is good reason to do so. Feel free to override
5406 the upstream author's ideas about which compilation
5407 options are best: they are often inappropriate for our
5408 environment.</p></sect>
5412 <heading>Libraries</heading>
5415 All libraries must have a shared version in the
5416 <tt>lib*</tt> package and a static version in the
5417 <tt>lib*-dev</tt> package. The shared version must be
5418 compiled with <tt>-fPIC</tt>, and the static version must
5419 not be. In other words, each <tt>*.c</tt> file will need to
5420 be compiled twice.</p>
5423 You must specify the gcc option <tt>-D_REENTRANT</tt>
5424 when building a library (either static or shared) to make
5425 the library compatible with LinuxThreads.</p>
5428 Note that all installed shared libraries should be
5430 <example compact="compact">
5431 strip --strip-unneeded <var>your-lib</var>
5433 (The option <tt>--strip-unneeded</tt> makes
5434 <prgn>strip</prgn> remove only the symbols which aren't
5435 needed for relocation processing.) Shared libraries can
5436 function perfectly well when stripped, since the symbols for
5437 dynamic linking are in a separate part of the ELF object
5440 You might also want to use the options
5441 <tt>--remove-section=.comment</tt> and
5442 <tt>--remove-section=.note</tt> on both shared libraries
5443 and executables, and <tt>--strip-debug</tt> on static
5450 Note that under some circumstances it may be useful to
5451 install a shared library unstripped, for example when
5452 building a separate package to support debugging.
5456 Shared object files (often <tt>.so</tt> files) that are not
5457 public libraries, that is, they are not meant to be linked
5458 to by third party executables (binaries of other packages),
5459 should be installed in subdirectories of the
5460 <tt>/usr/lib</tt> directory. Such files are exempt from the
5461 rules that govern ordinary shared libraries, except that
5462 they must not be installed executable and should be
5465 A common example are the so-called ``plug-ins'',
5466 internal shared objects that are dynamically loaded by
5467 programs using <manref name="dlopen" section="3">.
5473 Packages containing shared libraries that may be linked to
5474 by other packages' binaries, but which for some
5475 <em>compelling</em> reason can not be installed in
5476 <tt>/usr/lib</tt> directory, may install the shared library
5477 files in subdirectories of the <tt>/usr/lib</tt> directory,
5478 in which case they should arrange to add that directory in
5479 <tt>/etc/ld.so.conf</tt> in the package's post-installation
5480 script, and remove it in the package's post-removal script.
5484 An ever increasing number of packages are using
5485 <prgn>libtool</prgn> to do their linking. The latest GNU
5486 libtools (>= 1.3a) can take advantage of the metadata in the
5487 installed <prgn>libtool</prgn> archive files (<tt>*.la</tt>
5488 files). The main advantage of <prgn>libtool</prgn>'s
5489 <tt>.la</tt> files is that it allows <prgn>libtool</prgn> to
5490 store and subsequently access metadata with respect to the
5491 libraries it builds. <prgn>libtool</prgn> will search for
5492 those files, which contain a lot of useful information about
5493 a library (such as library dependency information for static
5494 linking). Also, they're <em>essential</em> for programs
5495 using <tt>libltdl</tt>.<footnote>
5497 Although <prgn>libtool</prgn> is fully capable of
5498 linking against shared libraries which don't have
5499 <tt>.la</tt> files, as it is a mere shell script it can
5500 add considerably to the build time of a
5501 <prgn>libtool</prgn>-using package if that shell script
5502 has to derive all this information from first principles
5503 for each library every time it is linked. With the
5504 advent of <prgn>libtool</prgn> version 1.4 (and to a
5505 lesser extent <prgn>libtool</prgn> version 1.3), the
5506 <tt>.la</tt> files also store information about
5507 inter-library dependencies which cannot necessarily be
5508 derived after the <tt>.la</tt> file is deleted.
5514 Packages that use <prgn>libtool</prgn> to create shared
5515 libraries should include the <tt>.la</tt> files in the
5516 <tt>-dev</tt> package, unless the package relies on
5517 <tt>libtool</tt>'s <tt>libltdl</tt> library, in which case
5518 the <tt>.la</tt> files must go in the run-time library
5523 You must make sure that you use only released versions of
5524 shared libraries to build your packages; otherwise other
5525 users will not be able to run your binaries
5526 properly. Producing source packages that depend on
5527 unreleased compilers is also usually a bad
5533 <heading>Shared libraries</heading>
5536 Packages involving shared libraries should be split up
5537 into several binary packages.</p>
5540 For a straightforward library which has a development
5541 environment and a runtime kit including just shared
5542 libraries you need to create two packages:
5543 <tt><var>libraryname</var><var>soversion</var></tt>, where
5544 <tt><var>soversion</var></tt> is the version number in the
5545 soname of the shared library<footnote>
5547 The soname is the shared object name: it's the thing
5548 that has to match exactly between building an executable
5549 and running it for the dynamic linker to be able run the
5550 program. For example, if the soname of the library is
5551 <tt>libfoo.so.6</tt>, the library package would be
5552 called <tt>libfoo6</tt>.
5555 and <tt><var>libraryname</var><var>soversion</var>-dev</tt>.
5559 If you prefer only to support one development version at a
5560 time you may name the development package
5561 <tt><var>libraryname</var>-dev</tt>; otherwise you may need
5562 to use <prgn>dpkg</prgn>'s Conflicts mechanism (see <ref
5563 id="conflicts">) to ensure that the user only installs one
5564 development version at a time (as different development
5565 versions are likely to have the same header files in them,
5566 which would cause a filename clash if both were installed).
5567 Typically the development version should also have an exact
5568 version dependency on the runtime library, to make sure that
5569 compilation and linking happens correctly. The
5570 <tt>${Source-Version}</tt> substitution variable can be
5571 useful for this purpose.
5575 Packages which use the shared library should have a
5576 dependency on the name of the shared library package,
5577 <tt><var>libraryname</var><var>soversion</var></tt>. When
5578 the soname changes you can have both versions of the library
5579 installed while migrating from the old library to the new.
5583 If your package has some run-time support programs which use
5584 the shared library you must not put them in the shared
5585 library package. If you do that then you won't be able to
5586 install several versions of the shared library without
5587 getting filename clashes. Instead, either create a third
5588 package for the runtime binaries (this package might
5589 typically be named <tt><var>libraryname</var>-runtime</tt>;
5590 note the absence of the <var>soversion</var> in the package
5591 name), or if the development package is small you may
5592 include them in there.
5596 If you have several shared libraries built from the same
5597 source tree you may lump them all together into a single
5598 shared library package, provided that you change all of
5599 their sonames at once (so that you don't get filename
5600 clashes if you try to install different versions of the
5601 combined shared libraries package).
5605 Shared libraries should not be installed executable, since
5606 the dynamic linker does not require this and trying to
5607 execute a shared library usually results in a core dump.
5612 <heading>Scripts</heading>
5615 All command scripts, including the package maintainer
5616 scripts inside the package and used by <prgn>dpkg</prgn>,
5617 should have a <tt>#!</tt> line naming the shell to be used
5618 to interpret them.</p>
5621 In the case of Perl scripts this should be
5622 <tt>#!/usr/bin/perl</tt>.</p>
5625 Shell scripts (<prgn>sh</prgn> and <prgn>bash</prgn>)
5626 should almost certainly start with <tt>set -e</tt> so that
5627 errors are detected. Every script should use
5628 <tt>set -e</tt> or check the exit status of <em>every</em>
5632 The standard shell interpreter <tt>/bin/sh</tt> can be a
5633 symbolic link to any POSIX compatible shell, if <tt>echo
5634 -n</tt> does not generate a newline.<footnote>
5636 Debian policy specifies POSIX behavior for
5637 <tt>/bin/sh</tt>, but <tt>echo -n</tt> has widespread
5638 use in the Linux community (in particular including this
5639 policy, the Linux kernel source, many Debian scripts,
5640 etc.). This <tt>echo -n</tt> mechanism is valid but not
5641 required under POSIX, hence this explicit addition.
5642 Also, rumour has it that this shall be mandated under
5646 Thus, shell scripts specifying <tt>/bin/sh</tt> as
5647 interpreter should only use POSIX features. If a script
5648 requires non-POSIX features from the shell interpreter, the
5649 appropriate shell must be specified in the first line of the
5650 script (e.g., <tt>#!/bin/bash</tt>) and the package must
5651 depend on the package providing the shell (unless the shell
5652 package is marked `Essential', as in the case of
5657 You may wish to restrict your script to POSIX features when
5658 possible so that it may use <tt>/bin/sh</tt> as its
5659 interpreter. If your script works with <prgn>ash</prgn>,
5660 it's probably POSIX compliant, but if you are in doubt, use
5665 Perl scripts should check for errors when making any
5666 system calls, including <tt>open</tt>, <tt>print</tt>,
5667 <tt>close</tt>, <tt>rename</tt> and <tt>system</tt>.
5671 <prgn>csh</prgn> and <prgn>tcsh</prgn> should be avoided as
5672 scripting languages. See <em>Csh Programming Considered
5673 Harmful</em>, one of the <tt>comp.unix.*</tt> FAQs, which
5674 can be found at <url
5675 id="http://language.perl.com/versus/csh.whynot">.<footnote>
5677 It can also be found on
5678 <url id="http://www.cpan.org/doc/FMTEYEWTK/versus/csh.whynot">
5679 or on the ftp site <ftpsite>ftp.cpan.org</ftpsite> as
5680 <ftppath>/pub/perl/CPAN/doc/FMTEYEWTK/versus/csh.whynot</ftppath>.
5683 If an upstream package comes with <prgn>csh</prgn> scripts
5684 then you must make sure that they start with
5685 <tt>#!/bin/csh</tt> and make your package depend on the
5686 <prgn>c-shell</prgn> virtual package.
5690 Any scripts which create files in world-writeable
5691 directories (e.g., in <tt>/tmp</tt>) must use a
5692 mechanism which will fail if a file with the same name
5696 The Debian base system provides the <prgn>tempfile</prgn>
5697 and <prgn>mktemp</prgn> utilities for use by scripts for
5698 this purpose.</p></sect>
5702 <heading>Symbolic links</heading>
5705 In general, symbolic links within a top-level directory
5706 should be relative, and symbolic links pointing from one
5707 top-level directory into another should be absolute. (A
5708 top-level directory is a sub-directory of the root
5709 directory <tt>/</tt>.)</p>
5712 In addition, symbolic links should be specified as short as
5713 possible, i.e., link targets like <tt>foo/../bar</tt> are
5717 Note that when creating a relative link using
5718 <prgn>ln</prgn> it is not necessary for the target of the
5719 link to exist relative to the working directory you're
5720 running <prgn>ln</prgn> from, nor is it necessary to change
5721 directory to the directory where the link is to be made.
5722 Simply include the string that should appear as the target
5723 of the link (this will be a pathname relative to the
5724 directory in which the link resides) as the first argument
5725 to <prgn>ln</prgn>.</p>
5728 For example, in your <prgn>Makefile</prgn> or
5729 <tt>debian/rules</tt>, you can do things like:
5730 <example compact="compact">
5731 ln -fs gcc $(prefix)/bin/cc
5732 ln -fs gcc debian/tmp/usr/bin/cc
5733 ln -fs ../sbin/sendmail $(prefix)/bin/runq
5734 ln -fs ../sbin/sendmail debian/tmp/usr/bin/runq
5738 A symbolic link pointing to a compressed file should always
5739 have the same file extension as the referenced file. (For
5740 example, if a file <tt>foo.gz</tt> is referenced by a
5741 symbolic link, the filename of the link has to end with
5742 `<tt>.gz</tt>' too, as in <tt>bar.gz</tt>.)
5747 <heading>Device files</heading>
5750 Packages must not include device files in the package file
5754 If a package needs any special device files that are not
5755 included in the base system, it must call
5756 <prgn>MAKEDEV</prgn> in the <prgn>postinst</prgn> script,
5757 after asking the user for permission to do so.</p>
5760 Packages must not remove any device files in the
5761 <prgn>postrm</prgn> or any other script. This is left to the
5762 system administrator.</p>
5765 Debian uses the serial devices
5766 <tt>/dev/ttyS*</tt>. Programs using the old
5767 <tt>/dev/cu*</tt> devices should be changed to use
5768 <tt>/dev/ttyS*</tt>.</p>
5771 <sect id="config files">
5772 <heading>Configuration files</heading>
5774 <heading>Definitions</heading>
5777 <tag>configuration file</tag>
5780 A file that affects the operation of a program, or
5781 provides site- or host-specific information, or
5782 otherwise customizes the behavior of a program.
5783 Typically, configuration files are intended to be
5784 modified by the system administrator (if needed or
5785 desired) to conform to local policy or to provide
5786 more useful site-specific behavior.
5790 <tag><tt>conffile</tt></tag>
5793 A file listed in a package's <tt>conffiles</tt>
5794 file, and is treated specially by <prgn>dpkg</prgn>
5795 (see <ref id="configdetails">).
5802 The distinction between these two is important; they are
5803 not interchangeable concepts. Almost all
5804 <tt>conffile</tt>s are configuration files, but many
5805 configuration files are not <tt>conffiles</tt>.
5809 Note that a script that embeds configuration information
5810 (such as most of the files in <tt>/etc/default</tt> and
5811 <tt>/etc/cron.{daily,weekly,monthly}</tt>) is de-facto a
5812 configuration file and should be treated as such.
5817 <heading>Location</heading>
5819 Any configuration files created or used by your package
5820 must reside in <tt>/etc</tt>. If there are several you
5821 should consider creating a subdirectory of <tt>/etc</tt>
5822 named after your package.</p>
5825 If your package creates or uses configuration files
5826 outside of <tt>/etc</tt>, and it is not feasible to modify
5827 the package to use the <tt>/etc</tt>, you should still put
5828 the files in <tt>/etc</tt> and create symbolic links to
5829 those files from the location that the package
5834 <heading>Behavior</heading>
5836 Configuration file handling must conform to the following
5838 <list compact="compact">
5841 local changes must be preserved during a package
5847 configuration files must be preserved when the
5848 package is removed, and only deleted when the
5856 The easy way to achieve this behavior is to make the
5857 configuration file a <tt>conffile</tt>. This is
5858 appropriate only if it is possible to distribute a default
5859 version that will work for most installations, although
5860 some system administrators may choose to modify it. This
5861 implies that the default version will be part of the
5862 package distribution, and must not be modified by the
5863 maintainer scripts during installation (or at any other
5868 In order to ensure that local changes are preserved
5869 correctly, no package may contain or make hard links to
5870 conffiles.<footnote>
5872 Rationale: There are two problems with hard links.
5873 The first is that some editors break the link while
5874 editing one of the files, so that the two files may
5875 unwittingly become unlinked and different. The second
5876 is that <prgn>dpkg</prgn> might break the hard link
5877 while upgrading <tt>conffile</tt>s.
5883 The other way to do it is via the maintainer scripts. In
5884 this case, the configuration file must not be listed as a
5885 <tt>conffile</tt> and must not be part of the package
5886 distribution. If the existence of a file is required for
5887 the package to be sensibly configured it is the
5888 responsibility of the package maintainer to provide
5889 maintainer scripts which correctly create, update and
5890 maintain the file and remove it on purge. (See <ref
5891 id="maintainerscripts"> for more information.) These
5892 scripts must be idempotent (i.e., must work correctly if
5893 <prgn>dpkg</prgn> needs to re-run them due to errors
5894 during installation or removal), must cope with all the
5895 variety of ways <prgn>dpkg</prgn> can call maintainer
5896 scripts, must not overwrite or otherwise mangle the user's
5897 configuration without asking, must not ask unnecessary
5898 questions (particularly during upgrades), and otherwise be
5903 The scripts are not required to configure every possible
5904 option for the package, but only those necessary to get
5905 the package running on a given system. Ideally the
5906 sysadmin should not have to do any configuration other
5907 than that done (semi-)automatically by the
5908 <prgn>postinst</prgn> script.
5912 A common practice is to create a script called
5913 <tt><var>package</var>-configure</tt> and have the
5914 package's <prgn>postinst</prgn> call it if and only if the
5915 configuration file does not already exist. In certain
5916 cases it is useful for there to be an example or template
5917 file which the maintainer scripts use. Such files should
5918 be in <tt>/usr/share/<var>package</var></tt> or
5919 <tt>/usr/lib/<var>package</var></tt> (depending on whether
5920 they are architecture-independent or not). There should
5921 be symbolic links to them from
5922 <tt>/usr/share/doc/<var>package</var>/examples</tt> if
5923 they are examples, and should be perfectly ordinary
5924 <prgn>dpkg</prgn>-handled files (<em>not</em>
5925 configuration files).
5929 These two styles of configuration file handling must
5930 not be mixed, for that way lies madness:
5931 <prgn>dpkg</prgn> will ask about overwriting the file
5932 every time the package is upgraded.
5937 <heading>Sharing configuration files</heading>
5939 Packages which specify the same file as a
5940 <tt>conffile</tt> must be tagged as <em>conflicting</em>
5941 with each other. (This is an instance of the general rule
5942 about not sharing files. Note that neither alternatives
5943 nor diversions are likely to be appropriate in this case;
5944 in particular, <prgn>dpkg</prgn> does not handle diverted
5945 <tt>conffile</tt>s well.)
5949 The maintainer scripts must not alter a <tt>conffile</tt>
5950 of <em>any</em> package, including the one the scripts
5955 If two or more packages use the same configuration file
5956 and it is reasonable for both to be installed at the same
5957 time, one of these packages must be defined as
5958 <em>owner</em> of the configuration file, i.e., it will be
5959 the package which handles that file as a configuration
5960 file. Other packages that use the configuration file must
5961 depend on the owning package if they require the
5962 configuration file to operate. If the other package will
5963 use the configuration file if present, but is capable of
5964 operating without it, no dependency need be declared.</p>
5967 If it is desirable for two or more related packages to
5968 share a configuration file <em>and</em> for all of the
5969 related packages to be able to modify that configuration
5970 file, then the following should be done:
5971 <enumlist compact="compact">
5974 One of the related packages (the "owning" package)
5975 will manage the configuration file with maintainer
5976 scripts as described in the previous section.
5981 The owning package should also provide a program
5982 that the other packages may use to modify the
5988 The related packages must use the provided program
5989 to make any desired modifications to the
5990 configuration file. They should either depend on
5991 the core package to guarantee that the configuration
5992 modifier program is available or accept gracefully
5993 that they cannot modify the configuration file if it
5994 is not. (This is in addition to the fact that the
5995 configuration file may not even be present in the
6003 Sometimes it's appropriate to create a new package which
6004 provides the basic infrastructure for the other packages
6005 and which manages the shared configuration files. (The
6006 <tt>sgml-base</tt> package is a good example.)
6011 <heading>User configuration files ("dotfiles")</heading>
6014 The files in <tt>/etc/skel</tt> will automatically be
6015 copied into new user accounts by <prgn>adduser</prgn>.
6016 No other program should reference the files in
6021 Therefore, if a program needs a dotfile to exist in
6022 advance in <tt>$HOME</tt> to work sensibly, that dotfile
6023 should be installed in <tt>/etc/skel</tt> and treated as a
6028 However, programs that require dotfiles in order to
6029 operate sensibly (dotfiles that they do not create
6030 themselves automatically, that is) are a bad thing.
6031 Furthermore, programs should be configured by the Debian
6032 default installation to behave as closely to the upstream
6033 default behaviour as possible.
6037 Therefore, if a program in a Debian package needs to be
6038 configured in some way in order to operate sensibly, that
6039 should be done using a site-wide configuration file placed
6040 in <tt>/etc</tt>. Only if the program doesn't support a
6041 site-wide default configuration and the package maintainer
6042 doesn't have time to add it may a default per-user file be
6043 placed in <tt>/etc/skel</tt>.
6047 <tt>/etc/skel</tt> should be as empty as we can make it.
6048 This is particularly true because there is no easy (or
6049 necessarily desirable) mechanism for ensuring that the
6050 appropriate dotfiles are copied into the accounts of
6051 existing users when a package is installed.
6057 <heading>Log files</heading>
6059 Log files should usually be named
6060 <tt>/var/log/<var>package</var>.log</tt>. If you have many
6061 log files, or need a separate directory for permission
6062 reasons (<tt>/var/log</tt> is writable only by
6063 <tt>root</tt>), you should usually create a directory named
6064 <tt>/var/log/<var>package</var></tt> and place your log
6069 Log files must be rotated occasionally so that they don't
6070 grow indefinitely; the best way to do this is to drop a log
6071 rotation configuration file into the directory
6072 <tt>/etc/logrotate.d</tt> and use the facilities provided by
6073 logrotate.<footnote>
6075 The traditional approach to log files has been to set up
6076 <em>ad hoc</em> log rotation schemes using simple shell
6077 scripts and cron. While this approach is highly
6078 customizable, it requires quite a lot of sysadmin work.
6079 Even though the original Debian system helped a little
6080 by automatically installing a system which can be used
6081 as a template, this was deemed not enough.
6085 The use of <prgn>logrotate</prgn>, a program developed
6086 by Red Hat, is better, as it centralizes log management.
6087 It has both a configuration file
6088 (<tt>/etc/logrotate.conf</tt>) and a directory where
6089 packages can drop their individual log rotation
6090 configurations (<tt>/etc/logrotate.d</tt>).
6093 Here is a good example for a logrotate config
6094 file (for more information see <manref name="logrotate"
6096 <example compact="compact">
6102 /etc/init.d/foo force-reload
6106 This rotates all files under <tt>/var/log/foo</tt>, saves 12
6107 compressed generations, and forces the daemon to reload its
6108 configuration information after the log rotation.
6112 Log files should be removed when the package is
6113 purged (but not when it is only removed). This should be
6114 done by the <prgn>postrm</prgn> script when it is called
6115 with the argument <tt>purge</tt> (see <ref
6116 id="removedetails">).
6121 <heading>Permissions and owners</heading>
6124 The rules in this section are guidelines for general use.
6125 If necessary you may deviate from the details below.
6126 However, if you do so you must make sure that what is done
6127 is secure and you should try to be as consistent as possible
6128 with the rest of the system. You should probably also
6129 discuss it on <prgn>debian-devel</prgn> first.
6133 Files should be owned by <tt>root.root</tt>, and made
6134 writable only by the owner and universally readable (and
6135 executable, if appropriate), that is mode 644 or 755.
6139 Directories should be mode 755 or (for group-writability)
6140 mode 2775. The ownership of the directory should be
6141 consistent with its mode: if a directory is mode 2775, it
6142 should be owned by the group that needs write access to
6147 Setuid and setgid executables should be mode 4755 or 2755
6148 respectively, and owned by the appropriate user or group.
6149 They should not be made unreadable (modes like 4711 or
6150 2711 or even 4111); doing so achieves no extra security,
6151 because anyone can find the binary in the freely available
6152 Debian package; it is merely inconvenient. For the same
6153 reason you should not restrict read or execute permissions
6154 on non-set-id executables.
6158 Some setuid programs need to be restricted to particular
6159 sets of users, using file permissions. In this case they
6160 should be owned by the uid to which they are set-id, and by
6161 the group which should be allowed to execute them. They
6162 should have mode 4754; again there is no point in making
6163 them unreadable to those users who must not be allowed to
6168 It is possible to arrange that the system administrator can
6169 reconfigure the package to correspond to their local
6170 security policy by changing the permissions on a binary:
6171 they can do this by using <prgn>dpkg-statoverride</prgn>, as
6172 described below.<footnote>
6174 Ordinary files installed by <prgn>dpkg</prgn> (as
6175 opposed to <tt>conffile</tt>s and other similar objects)
6176 normally have their permissions reset to the distributed
6177 permissions when the package is reinstalled. However,
6178 the use of <prgn>dpkg-statoverride</prgn> overrides this
6179 default behaviour. If you use this method, you should
6180 remember to describe <prgn>dpkg-statoverride</prgn> in
6181 the package documentation; being a relatively new
6182 addition to Debian, it is probably not yet well-known.
6185 Another method you should consider is to create a group for
6186 people allowed to use the program(s) and make any setuid
6187 executables executable only by that group.
6191 If you need to create a new user or group for your package
6192 there are two possibilities. Firstly, you may need to
6193 make some files in the binary package be owned by this
6194 user or group, or you may need to compile the user or
6195 group id (rather than just the name) into the binary
6196 (though this latter should be avoided if possible, as in
6197 this case you need a statically allocated id).</p>
6200 If you need a statically allocated id, you must ask for a
6201 user or group id from the <tt>base-passwd</tt> maintainer,
6202 and must not release the package until you have been
6203 allocated one. Once you have been allocated one you must
6204 either make the package depend on a version of the
6205 <tt>base-passwd</tt> package with the id present in
6206 <tt>/etc/passwd</tt> or <tt>/etc/group</tt>, or arrange for
6207 your package to create the user or group itself with the
6208 correct id (using <tt>adduser</tt>) in its
6209 <prgn>preinst</prgn> or <prgn>postinst</prgn>. (Doing it in
6210 the <prgn>postinst</prgn> is to be preferred if it is
6211 possible, otherwise a pre-dependency will be needed on the
6212 <tt>adduser</tt> package.)
6216 On the other hand, the program might be able to determine
6217 the uid or gid from the user or group name at runtime, so
6218 that a dynamically allocated id can be used. In this case
6219 you should choose an appropriate user or group name,
6220 discussing this on <prgn>debian-devel</prgn> and checking
6221 with the base system maintainer that it is unique and that
6222 they do not wish you to use a statically allocated id
6223 instead. When this has been checked you must arrange for
6224 your package to create the user or group if necessary using
6225 <prgn>adduser</prgn> in the <prgn>preinst</prgn> or
6226 <prgn>postinst</prgn> script (again, the latter is to be
6227 preferred if it is possible).
6231 Note that changing the numeric value of an id associated
6232 with a name is very difficult, and involves searching the
6233 file system for all appropriate files. You need to think
6234 carefully whether a static or dynamic id is required, since
6235 changing your mind later will cause problems.
6238 <sect1><heading>The use of <prgn>dpkg-statoverride</prgn></heading>
6240 This section is not intended as policy, but as a
6241 description of the use of <prgn>dpkg-statoverride</prgn>.
6245 <prgn>dpkg-statoverride</prgn> is a replacement for the
6246 deprecated <tt>suidmanager</tt> package. Packages which
6247 previously used <tt>suidmanager</tt> should have a
6248 <tt>Conflicts: suidmanager (<< 0.50)</tt> entry (or even
6249 <tt>(<< 0.52)</tt>), and calls to <tt>suidregister</tt>
6250 and <tt>suidunregister</tt> should now be simply removed
6251 from the maintainer scripts.
6255 If a system administrator wishes to have a file (or
6256 directory or other such thing) installed with owner and
6257 permissions different from those in the distributed Debian
6258 package, he can use the <prgn>dpkg-statoverride</prgn>
6259 program to instruct <prgn>dpkg</prgn> to use the different
6260 settings every time the file is installed. Thus the
6261 package maintainer should distribute the files with their
6262 normal permissions, and leave it for the system
6263 administrator to make any desired changes. For example, a
6264 daemon which is normally required to be setuid root, but
6265 in certain situations could be used without being setuid,
6266 should be installed setuid in the <tt>.deb</tt>. Then the
6267 local system administrator can change this if they wish.
6268 If there are two standard ways of doing it, the package
6269 maintainer can use <tt>debconf</tt> to find out the
6270 preference, and call <prgn>dpkg-statoverride</prgn> in the
6271 maintainer script if necessary to accommodate the system
6272 administrator's choice.
6276 Given the above, <prgn>dpkg-statoverride</prgn> is
6277 essentially a tool for system administrators and would not
6278 normally be needed in the maintainer scripts. There is
6279 one type of situation, though, where calls to
6280 <prgn>dpkg-statoverride</prgn> would be needed in the
6281 maintainer scripts, and that involves packages which use
6282 dynamically allocated user or group ids. In such a
6283 situation, something like the following idiom can be very
6284 helpful in the package's <prgn>postinst</prgn>, where
6285 <tt>sysuser</tt> is a dynamically allocated id:
6287 for i in /usr/bin/foo /usr/sbin/bar
6289 if ! dpkg-statoverride --list $i >/dev/null
6291 dpkg-statoverride --update --add sysuser root 4755 $i
6295 The corresponding <tt>dpkg-statoverride --remove</tt>
6296 calls can then be made unconditionally when the package is
6303 <chapt id="customized-programs">
6304 <heading>Customized programs</heading>
6306 <sect id="arch-spec">
6307 <heading>Architecture specification strings</heading>
6310 If a program needs to specify an <em>architecture specification
6311 string</em> in some place, the following format should be
6312 used: <var>arch</var>-<var>os</var><footnote>
6314 The following architectures and operating systems are
6315 currently recognised by <prgn>dpkg-archictecture</prgn>.
6316 The architecture, <tt><var>arch</var></tt>, is one of
6317 the following: <tt>alpha</tt>, <tt>arm</tt>,
6318 <tt>hppa</tt>, <tt>i386</tt>, <tt>ia64</tt>,
6319 <tt>m68k</tt>, <tt>mips</tt>, <tt>mipsel</tt>,
6320 <tt>powerpc</tt>, <tt>s390</tt>, <tt>sh</tt>,
6321 <tt>sheb</tt>, <tt>sparc</tt> and <tt>sparc64</tt>. The
6322 operating system, <tt><var>os</var></tt>, is one of:
6323 <tt>linux</tt>, <tt>gnu</tt>, <tt>freebsd</tt> and
6324 <tt>openbsd</tt>. Use of <tt>gnu</tt> in this string is
6325 reserved for the GNU/Hurd operating system.
6331 Note that we don't want to use
6332 <tt><var>arch</var>-debian-linux</tt> to apply to the rule
6333 <tt><var>architecture</var>-<var>vendor</var>-<var>os</var></tt>
6334 since this would make our programs incompatible with other
6335 Linux distributions. We also don't use something like
6336 <tt><var>arch</var>-unknown-linux</tt>, since the
6337 <tt>unknown</tt> does not look very good.
6342 <heading>Daemons</heading>
6345 The configuration files <tt>/etc/services</tt>,
6346 <tt>/etc/protocols</tt>, and <tt>/etc/rpc</tt> are managed
6347 by the <prgn>netbase</prgn> package and must not be modified
6352 If a package requires a new entry in one of these files, the
6353 maintainer should get in contact with the
6354 <prgn>netbase</prgn> maintainer, who will add the entries
6355 and release a new version of the <prgn>netbase</prgn>
6360 The configuration file <tt>/etc/inetd.conf</tt> must not be
6361 modified by the package's scripts except via the
6362 <prgn>update-inetd</prgn> script or the
6363 <tt>DebianNet.pm</tt> Perl module. See their documentation
6364 for details on how to add entries.
6368 If a package wants to install an example entry into
6369 <tt>/etc/inetd.conf</tt>, the entry must be preceded with
6370 exactly one hash character (<tt>#</tt>). Such lines are
6371 treated as `commented out by user' by the
6372 <prgn>update-inetd</prgn> script and are not changed or
6373 activated during package updates.
6378 <heading>Using pseudo-ttys and modifying wtmp, utmp and
6382 Some programs need to create pseudo-ttys. This should be done
6383 using Unix98 ptys if the C library supports it. The resulting
6384 program must not be installed setuid root, unless that
6385 is required for other functionality.
6389 The files <tt>/var/run/utmp</tt>, <tt>/var/log/wtmp</tt> and
6390 <tt>/var/log/lastlog</tt> must be installed writeable by
6391 group <tt>utmp</tt>. Programs which need to modify those
6392 files must be installed setgid <tt>utmp</tt>.
6397 <heading>Editors and pagers</heading>
6400 Some programs have the ability to launch an editor or pager
6401 program to edit or display a text document. Since there are
6402 lots of different editors and pagers available in the Debian
6403 distribution, the system administrator and each user should
6404 have the possibility to choose his/her preferred editor and
6409 In addition, every program should choose a good default
6410 editor/pager if none is selected by the user or system
6415 Thus, every program that launches an editor or pager must
6416 use the EDITOR or PAGER environment variable to determine
6417 the editor or pager the user wishes to use. If these
6418 variables are not set, the programs <tt>/usr/bin/editor</tt>
6419 and <tt>/usr/bin/pager</tt> should be used, respectively.
6423 These two files are managed through the <prgn>dpkg</prgn>
6424 `alternatives' mechanism. Thus every package providing an
6425 editor or pager must call the
6426 <prgn>update-alternatives</prgn> script to register these
6431 If it is very hard to adapt a program to make use of the
6432 EDITOR or PAGER variables, that program may be configured to
6433 use <tt>/usr/bin/sensible-editor</tt> and
6434 <tt>/usr/bin/sensible-pager</tt> as the editor or pager
6435 program respectively. These are two scripts provided in the
6436 Debian base system that check the EDITOR and PAGER variables
6437 and launch the appropriate program, and fall back to
6438 <tt>/usr/bin/editor</tt> and <tt>/usr/bin/pager</tt> if the
6439 variable is not set.
6443 A program may also use the VISUAL environment variable to
6444 determine the user's choice of editor. If it exists, it
6445 should take precedence over EDITOR. This is in fact what
6446 <tt>/usr/bin/sensible-editor</tt> does.
6450 It is not required for a package to depend on
6451 <tt>editor</tt> and <tt>pager</tt>, nor is it required for a
6452 package to provide such virtual packages.<footnote>
6454 The Debian base system already provides an editor and a
6461 <sect id="web-appl">
6462 <heading>Web servers and applications</heading>
6465 This section describes the locations and URLs that should
6466 be used by all web servers and web applications in the
6474 Cgi-bin executable files are installed in the
6476 <example compact="compact">
6477 /usr/lib/cgi-bin/<var>cgi-bin-name</var>
6479 and should be referred to as
6480 <example compact="compact">
6481 http://localhost/cgi-bin/<var>cgi-bin-name</var>
6486 <item><p>Access to HTML documents</p>
6489 HTML documents for a package are stored in
6490 <tt>/usr/share/doc/<var>package</var></tt>
6491 and can be referred to as
6492 <example compact="compact">
6493 http://localhost/doc/<var>package</var>/<var>filename</var>
6497 The web server should restrict access to the document
6498 tree so that only clients on the same host can read
6499 the documents. If the web server does not support such
6500 access controls, then it should not provide access at
6501 all, or ask about providing access during installation.
6505 <item><p>Web Document Root</p>
6508 Web Applications should try to avoid storing files in
6509 the Web Document Root. Instead they should use the
6510 /usr/share/doc/<var>package</var> directory for
6511 documents and register the Web Application via the
6512 menu package. If access to the web document root is
6513 unavoidable then use
6514 <example compact="compact">
6517 as the Document Root. This might be just a symbolic
6518 link to the location where the system administrator
6519 has put the real document root.
6523 </enumlist></p></sect>
6526 <sect id="mail-transport-agents">
6527 <heading>Mail transport, delivery and user agents</heading>
6530 Debian packages which process electronic mail, whether mail
6531 user agents (MUAs) or mail transport agents (MTAs), must
6532 ensure that they are compatible with the configuration
6533 decisions below. Failure to do this may result in lost
6534 mail, broken <tt>From:</tt> lines, and other serious brain
6539 The mail spool is <tt>/var/mail</tt> and the interface to
6540 send a mail message is <tt>/usr/sbin/sendmail</tt> (as per
6541 the FHS). On older systems, the mail spool may be
6542 physically located in <tt>/var/spool/mail</tt>, but all
6543 access to the mail spool should be via the
6544 <tt>/var/mail</tt> symlink. The mail spool is part of the
6545 base system and not part of the MTA package.
6549 All Debian MUAs, MTAs, MDAs and other mailbox accessing
6550 programs (such as IMAP daemons) must lock the mailbox in an
6551 NFS-safe way. This means that <tt>fcntl()</tt> locking must
6552 be combined with dot locking. To avoid deadlocks, a program
6553 should use <tt>fcntl()</tt> first and dot locking after
6554 this, or alternatively implement the two locking methods in
6555 a non blocking way<footnote>
6557 If it is not possible to establish both locks, the
6558 system shouldn't wait for the second lock to be
6559 established, but remove the first lock, wait a (random)
6560 time, and start over locking again.
6562 </footnote>. Using the functions <tt>maillock</tt> and
6563 <tt>mailunlock</tt> provided by the
6564 <tt>liblockfile*</tt><footnote>
6566 You will need to depend on <tt>liblockfile1
6567 (>>1.01)</tt> to use these functions.
6569 </footnote> packages is the recommended way to realize this.
6573 Mailboxes are generally mode 660
6574 <tt><var>user</var>.mail</tt> unless the system
6575 administrator has chosen otherwise. A MUA may remove a
6576 mailbox (unless it has nonstandard permissions) in which
6577 case the MTA or another MUA must recreate it if needed.
6578 Mailboxes must be writable by group mail.
6582 The mail spool is 2775 <tt>root.mail</tt>, and MUAs should
6583 be setgid mail to do the locking mentioned above (and
6584 must obviously avoid accessing other users' mailboxes
6585 using this privilege).</p>
6588 <tt>/etc/aliases</tt> is the source file for the system mail
6589 aliases (e.g., postmaster, usenet, etc.), it is the one
6590 which the sysadmin and <prgn>postinst</prgn> scripts may
6591 edit. After <tt>/etc/aliases</tt> is edited the program or
6592 human editing it must call <prgn>newaliases</prgn>. All MTA
6593 packages must come with a <prgn>newaliases</prgn> program,
6594 even if it does nothing, but older MTA packages did not do
6595 this so programs should not fail if <prgn>newaliases</prgn>
6596 cannot be found. Note that because of this, all MTA
6597 packages must have <tt>Provides</tt>, <tt>Conflicts</tt> and
6598 <tt>Replaces: mail-transport-agent</tt> control file
6603 The convention of writing <tt>forward to
6604 <var>address</var></tt> in the mailbox itself is not
6605 supported. Use a <tt>.forward</tt> file instead.</p>
6608 The <prgn>rmail</prgn> program used by UUCP
6609 for incoming mail should be <tt>/usr/sbin/rmail</tt>.
6610 Likewise, <prgn>rsmtp</prgn>, for receiving
6611 batch-SMTP-over-UUCP, should be <tt>/usr/sbin/rsmtp</tt> if it
6615 If your package needs to know what hostname to use on (for
6616 example) outgoing news and mail messages which are generated
6617 locally, you should use the file <tt>/etc/mailname</tt>. It
6618 will contain the portion after the username and <tt>@</tt>
6619 (at) sign for email addresses of users on the machine
6620 (followed by a newline).
6624 Such package should check for the existence of this file
6625 when it is being configured. If it exists, it should be
6626 used without comment, although an MTA's configuration script
6627 may wish to prompt the user even if it finds that this file
6628 exists. If the file does not exist, the package should
6629 prompt the user for the value (preferably using
6630 <prgn>debconf</prgn>) and store it in <tt>/etc/mailname</tt>
6631 as well as using it in the package's configuration. The
6632 prompt should make it clear that the name will not just be
6633 used by that package. For example, in this situation the
6634 <tt>inn</tt> package could say something like:
6635 <example compact="compact">
6636 Please enter the `mail name' of your system. This is the
6637 hostname portion of the address to be shown on outgoing
6638 news and mail messages. The default is
6639 <var>syshostname</var>, your system's host name. Mail
6640 name [`<var>syshostname</var>']:
6642 where <var>syshostname</var> is the output of <tt>hostname
6648 <heading>News system configuration</heading>
6651 All the configuration files related to the NNTP (news)
6652 servers and clients should be located under
6653 <tt>/etc/news</tt>.</p>
6656 There are some configuration issues that apply to a number
6657 of news clients and server packages on the machine. These
6661 <tag><tt>/etc/news/organization</tt></tag>
6662 <item><p>A string which should appear as the
6663 organization header for all messages posted
6664 by NNTP clients on the machine</p></item>
6666 <tag><tt>/etc/news/server</tt></tag>
6667 <item><p>Contains the FQDN of the upstream NNTP
6668 server, or localhost if the local machine is
6669 an NNTP server.</p></item>
6672 Other global files may be added as required for cross-package news
6673 configuration.</p></sect>
6677 <heading>Programs for the X Window System</heading>
6680 <heading>Providing X support and package priorities</heading>
6683 Programs that can be configured with support for the X
6684 Window System must be configured to do so and must declare
6685 any package dependencies necessary to satisfy their
6686 runtime requirements when using the X Window System. If
6687 such a package is of higher priority than the X packages
6688 on which it depends, it is required that either the
6689 X-specific components be split into a separate package, or
6690 that an alternative version of the package, which includes
6691 X support, be provided, or that the package's priority be
6697 <heading>Packages providing an X server</heading>
6700 Packages that provide an X server that, directly or
6701 indirectly, communicates with real input and display
6702 hardware should declare in their control data that they
6703 provide the virtual package <tt>xserver</tt>.<footnote>
6705 This implements current practice, and provides an
6706 actual policy for usage of the <tt>xserver</tt>
6707 virtual package which appears in the virtual packages
6708 list. In a nutshell, X servers that interface
6709 directly with the display and input hardware or via
6710 another subsystem (e.g., GGI) should provide
6711 <tt>xserver</tt>. Things like <tt>Xvfb</tt>,
6712 <tt>Xnest</tt>, and <tt>Xprt</tt> should not.
6719 <heading>Packages providing a terminal emulator</heading>
6722 Packages that provide a terminal emulator for the X Window
6723 System which meet the criteria listed below should declare
6724 in their control data that they provide the virtual
6725 package <tt>x-terminal-emulator</tt>. They should also
6726 register themselves as an alternative for
6727 <tt>/usr/bin/x-terminal-emulator</tt>, with a priority of
6732 To be an <tt>x-terminal-emulator</tt>, a program must:
6733 <list compact="compact">
6735 Be able to emulate a DEC VT100 terminal, or a
6736 compatible terminal.
6740 Support the command-line option <tt>-e
6741 <var>command</var></tt>, which creates a new
6742 terminal window<footnote>
6744 "New terminal window" does not necessarily mean
6745 a new top-level X window directly parented by
6746 the window manager; it could, if the terminal
6747 emulator application were so coded, be a new
6748 "view" in a multiple-document interface (MDI).
6751 and runs the specified <var>command</var>.
6755 Support the command-line option <tt>-T
6756 <var>title</var></tt>, which creates a new terminal
6757 window with the window title <var>title</var>.
6764 <heading>Packages providing a window manager</heading>
6767 Packages that provide a window manager should declare in
6768 their control data that they provide the virtual package
6769 <tt>x-window-manager</tt>. They should also register
6770 themselves as an alternative for
6771 <tt>/usr/bin/x-window-manager</tt>, with a priority
6772 calculated as follows:
6773 <list compact="compact">
6774 <item><p>Start with a priority of 20.</p></item>
6778 If the window manager supports the Debian menu
6779 system, add 20 points if this support is available
6780 in the package's default configuration (i.e., no
6781 configuration files belonging to the system or user
6782 have to be edited to activate the feature); if
6783 configuration files must be modified, add only 10
6790 If the window manager permits the X session to be
6791 restarted using a <em>different</em> window manager
6792 (without killing the X server) in its default
6793 configuration, add 10 points; otherwise add none.
6801 <heading>Packages providing fonts</heading>
6804 Packages that provide fonts for the X Window
6807 For the purposes of Debian Policy, a "font for the X
6808 Window System" is one which is accessed via X protocol
6809 requests. Fonts for the Linux console, for PostScript
6810 renderers, or any other purpose, do not fit this
6811 definition. Any tool which makes such fonts available
6812 to the X Window System, however, must abide by this
6816 must do a number of things to ensure that they are both
6817 available without modification of the X or font server
6818 configuration, and that they do not corrupt files used by
6819 other font packages to register information about
6824 Fonts of any type supported by the X Window System
6825 must be be in a separate binary package from any
6826 executables, libraries, or documentation (except
6827 that specific to the fonts shipped, such as their
6828 license information). If one or more of the fonts
6829 so packaged are necessary for proper operation of
6830 the package with which they are associated the font
6831 package may be Recommended; if the fonts merely
6832 provide an enhancement, a Suggests relationship may
6833 be used. Packages must not Depend on font
6836 This is because the X server may retrieve fonts
6837 from the local filesystem or over the network
6838 from an X font server; the Debian package system
6839 is empowered to deal only with the local
6848 BDF fonts must be converted to PCF fonts with the
6849 <prgn>bdftopcf</prgn> utility (available in the
6850 <tt>xutils</tt> package, <tt>gzip</tt>ped, and
6851 placed in a directory that corresponds to their
6853 <list compact="compact">
6855 100 dpi fonts must be placed in
6856 <tt>/usr/X11R6/lib/X11/fonts/100dpi/</tt>.
6860 75 dpi fonts must be placed in
6861 <tt>/usr/X11R6/lib/X11/fonts/75dpi/</tt>.
6865 Character-cell fonts, cursor fonts, and other
6866 low-resolution fonts must be placed in
6867 <tt>/usr/X11R6/lib/X11/fonts/misc/</tt>.
6874 Speedo fonts must be placed in
6875 <tt>/usr/X11R6/lib/X11/fonts/Speedo/</tt>.
6879 Type 1 fonts must be placed in
6880 <tt>/usr/X11R6/lib/X11/fonts/Type1/</tt>. If font
6881 metric files are available, they must be placed here
6887 Subdirectories of <tt>/usr/X11R6/lib/X11/fonts/</tt>
6888 other than those listed above must be neither
6889 created nor used. (The <tt>PEX</tt>, <tt>CID</tt>,
6890 and <tt>cyrillic</tt> directories are excepted for
6891 historical reasons, but installation of files into
6892 these directories remains discouraged.)
6898 Font packages may, instead of placing files directly
6899 in the X font directories listed above, provide
6900 symbolic links in the font directory which point to
6901 the files' actual location in the filesystem. Such
6902 a location must comply with the FHS.
6908 Font packages should not contain both 75dpi and
6909 100dpi versions of a font. If both are available,
6910 they should be provided in separate binary packages
6911 with <tt>-75dpi</tt> or <tt>-100dpi</tt> appended to
6912 the names of the packages containing the
6913 corresponding fonts.
6919 Fonts destined for the <tt>misc</tt> subdirectory
6920 should not be included in the same package as 75dpi
6921 or 100dpi fonts; instead, they should be provided in
6922 a separate package with <tt>-misc</tt> appended to
6929 Font packages must not provide the files
6930 <tt>fonts.dir</tt>, <tt>fonts.alias</tt>, or
6931 <tt>fonts.scale</tt> in a font directory:
6934 <tt>fonts.dir</tt> files must not be provided at all.
6939 <tt>fonts.alias</tt> and <tt>fonts.scale</tt>
6940 files, if needed, should be provided in the
6942 <tt>/etc/X11/fonts/<var>fontdir</var>/<var>package</var>.<var>extension</var></tt>,
6943 where <var>fontdir</var> is the name of the
6945 <tt>/usr/X11R6/lib/X11/fonts/</tt> where the
6946 package's corresponding fonts are stored
6947 (e.g., <tt>75dpi</tt> or <tt>misc</tt>),
6948 <var>package</var> is the name of the package
6949 that provides these fonts, and
6950 <var>extension</var> is either <tt>scale</tt>
6951 or <tt>alias</tt>, whichever corresponds to
6961 Font packages must declare a dependency on
6962 <tt>xutils (>> 4.0.3)</tt> in their control
6969 Font packages that provide one or more
6970 <tt>fonts.scale</tt> files as described above must
6971 invoke <prgn>update-fonts-scale</prgn> on each
6972 directory into which they installed fonts
6973 <em>before</em> invoking
6974 <prgn>update-fonts-dir</prgn> on that directory.
6975 This invocation must occur in both the
6976 <prgn>postinst</prgn> (for all arguments) and
6977 <prgn>postrm</prgn> (for all arguments except
6978 <tt>upgrade</tt>) scripts.
6984 Font packages that provide one or more
6985 <tt>fonts.alias</tt> files as described above must
6986 invoke <prgn>update-fonts-alias</prgn> on each
6987 directory into which they installed fonts. This
6988 invocation must occur in both the
6989 <prgn>postinst</prgn> (for all arguments) and
6990 <prgn>postrm</prgn> (for all arguments except
6991 <tt>upgrade</tt>) scripts.
6997 Font packages must invoke
6998 <prgn>update-fonts-dir</prgn> on each directory into
6999 which they installed fonts. This invocation must
7000 occur in both the <prgn>postinst</prgn> (for all
7001 arguments) and <prgn>postrm</prgn> (for all
7002 arguments except <tt>upgrade</tt>) scripts.
7008 Font packages must not provide alias names for the
7009 fonts they include which collide with alias names
7010 already in use by fonts already packaged.
7016 Font packages must not provide fonts with the same
7017 XLFD registry name as another font already packaged.
7025 <heading>Application defaults files</heading>
7028 Application defaults files must be installed in the
7029 directory <tt>/etc/X11/app-defaults/</tt> (use of a
7030 localized subdirectory of <tt>/etc/X11/</tt> as described
7031 in the <em>X Toolkit Intrinsics - C Language
7032 Interface</em> manual is also permitted). They must be
7033 registered as <tt>conffile</tt>s or handled as
7034 configuration files. Packages must not provide the
7035 directory <tt>/usr/X11R6/lib/X11/app-defaults/</tt>.
7039 Customization of programs' X resources may also be
7040 supported with the provision of a file with the same name
7041 as that of the package placed in the
7042 <tt>/etc/X11/Xresources/</tt> directory, which must
7043 registered as a <tt>conffile</tt> or handled as a
7044 configuration file.<footnote>
7046 Note that this mechanism is not the same as using
7047 app-defaults; app-defaults are tied to the client
7048 binary on the local filesystem, whereas X resources
7049 are stored in the X server and affect all connecting
7053 <em>Important:</em> packages that install files into the
7054 <tt>/etc/X11/Xresources/</tt> directory must conflict with
7055 <tt>xbase (<< 3.3.2.3a-2)</tt>; if this is not done
7056 it is possible for the installing package to destroy a
7057 previously-existing <tt>/etc/X11/Xresources</tt> file
7058 which had been customized by the system administrator.
7063 <heading>Installation directory issues</heading>
7066 Packages using the X Window System should not be
7067 configured to install files under the <tt>/usr/X11R6/</tt>
7068 directory unless they use <prgn>imake</prgn>. The
7069 <tt>/usr/X11R6/</tt> directory hierarchy should be
7070 regarded as deprecated for all packages except the X
7071 Window System itself, and those which use the
7072 <prgn>imake</prgn> program it provides, in which case the
7073 packages may transition out of the <tt>/usr/X11R6/</tt>
7074 directory at the maintainer's discretion.<footnote>
7076 <prgn>Imake</prgn>-using programs are exempt because,
7077 as long as they are written correctly, the pathnames
7078 they use to locate resources and install themselves
7079 are derived wholly from the X Window System
7080 configuration. Thus, in the event that the X Window
7081 System moves to <tt>/usr/X11R7/</tt>,
7082 <tt>/usr/X12/</tt>, or just plain <tt>/usr/</tt>, all
7083 that is required for these programs is a recompile
7084 against the corresponding X Window System library
7085 development packages.
7088 Programs that use GNU <prgn>autoconf</prgn> and
7089 <prgn>automake</prgn> are usually easily configured at
7090 compile time to use <tt>/usr/</tt> instead of
7091 <tt>/usr/X11R6/</tt>, and this should be done whenever
7092 possible. Configuration files for window managers and
7093 display managers should be placed in a subdirectory of
7094 <tt>/etc/X11/</tt> corresponding to the package name due
7095 to these programs' tight integration with the mechanisms
7096 of the X Window System. Application-level programs should
7097 use the <tt>/etc/</tt> directory unless otherwise mandated
7098 by policy. The installation of files into subdirectories
7099 of <tt>/usr/X11R6/include/X11/</tt> and
7100 <tt>/usr/X11R6/lib/X11/</tt> is permitted but discouraged;
7101 package maintainers should determine if subdirectories of
7102 <tt>/usr/lib/</tt> and <tt>/usr/share/</tt> can be used
7103 instead. (The use of symbolic links from the
7104 <tt>X11R6</tt> directories to other FHS-compliant
7105 locations is encouraged if the program is not easily
7106 configured to look elsewhere for its files.) Packages
7107 must not provide or install files into the directories
7108 <tt>/usr/bin/X11/</tt>, <tt>/usr/include/X11/</tt> or
7109 <tt>/usr/lib/X11/</tt>. Files within a package should,
7110 however, make reference to these directories, rather than
7111 their <tt>X11R6</tt>-named counterparts
7112 <tt>/usr/X11R6/bin/</tt>, <tt>/usr/X11R6/include/X11/</tt>
7113 and <tt>/usr/X11R6/lib/X11/</tt>, if the resources being
7114 referred to have not been moved to other FHS-compliant
7120 <heading>The OSF/Motif and OpenMotif libraries</heading>
7123 <em>Programs that require the non-DFSG-compliant OSF/Motif or
7124 OpenMotif libraries</em><footnote>
7126 OSF/Motif and OpenMotif are collectively referred to as
7127 "Motif" in this policy document.
7130 should be compiled against and tested with LessTif (a free
7131 re-implementation of Motif) instead. If the maintainer
7132 judges that the program or programs do not work
7133 sufficiently well with LessTif to be distributed and
7134 supported, but do so when compiled against Motif, then two
7135 versions of the package should be created; one linked
7136 statically against Motif and with <tt>-smotif</tt>
7137 appended to the package name, and one linked dynamically
7138 against Motif and with <tt>-dmotif</tt> appended to the
7139 package name. Both Motif-linked versions are dependent
7140 upon non-DFSG-compliant software and thus cannot be
7141 uploaded to the <em>main</em> distribution; if the
7142 software is itself DFSG-compliant it may be uploaded to
7143 the <em>contrib</em> distribution. While known existing
7144 versions of Motif permit unlimited redistribution of
7145 binaries linked against the library (whether statically or
7146 dynamically), it is the package maintainer's
7147 responsibility to determine whether this is permitted by
7148 the license of the copy of Motif in his or her possession.
7154 <heading>Perl programs and modules</heading>
7156 Perl programs and modules should follow the current Perl
7157 policy as defined in the file found on
7158 <ftpsite>ftp.debian.org</ftpsite> in
7159 <ftppath>/debian/doc/package-developer/perl-policy.txt.gz</ftppath>
7160 or your local mirror. In addition, it is included in the
7161 <tt>debian-policy</tt> package.
7166 <heading>Emacs lisp programs</heading>
7169 Please refer to the `Debian Emacs Policy' (documented in
7170 <tt>debian-emacs-policy.gz</tt> of the
7171 <prgn>emacsen-common</prgn> package) for details of how to
7172 package emacs lisp programs.
7177 <heading>Games</heading>
7180 The permissions on <tt>/var/games</tt> are mode 755, owner
7181 <tt>root</tt> and group <tt>root</tt>.
7185 Each game decides on its own security policy.</p>
7188 Games which require protected, privileged access to
7189 high-score files, savegames, etc., may be made
7190 set-<em>group</em>-id (mode 2755) and owned by
7191 <tt>root.games</tt>, and use files and directories with
7192 appropriate permissions (770 <tt>root.games</tt>, for
7193 example). They must not be made
7194 set-<em>user</em>-id, as this causes security problems. (If
7195 an attacker can subvert any set-user-id game they can
7196 overwrite the executable of any other, causing other players
7197 of these games to run a Trojan horse program. With a
7198 set-group-id game the attacker only gets access to less
7199 important game data, and if they can get at the other
7200 players' accounts at all it will take considerably more
7204 Some packages, for example some fortune cookie programs, are
7205 configured by the upstream authors to install with their
7206 data files or other static information made unreadable so
7207 that they can only be accessed through set-id programs
7208 provided. You should not do this in a Debian package: anyone can
7209 download the <tt>.deb</tt> file and read the data from it,
7210 so there is no point making the files unreadable. Not
7211 making the files unreadable also means that you don't have
7212 to make so many programs set-id, which reduces the risk of a
7216 As described in the FHS, binaries of games should be
7217 installed in the directory <tt>/usr/games</tt>. This also
7218 applies to games that use the X Window System. Manual pages
7219 for games (X and non-X games) should be installed in
7220 <tt>/usr/share/man/man6</tt>.</p>
7224 <chapt id="docs"><heading>Documentation</heading>
7228 <heading>Manual pages</heading>
7231 You should install manual pages in <prgn>nroff</prgn> source
7232 form, in appropriate places under <tt>/usr/share/man</tt>. You
7233 should only use sections 1 to 9 (see the FHS for more
7234 details). You must not install a preformatted `cat
7238 Each program, utility, and function should have an
7239 associated manpage included in the same package. It is
7240 suggested that all configuration files also have a manual
7241 page included as well.
7245 If no manual page is available for a particular program,
7246 utility, function or configuration file and this is reported
7247 as a bug to the Debian Bug Tracking System, a symbolic link
7248 from the requested manual page to the <manref
7249 name="undocumented" section="7"> manual page may be
7250 provided. This symbolic link can be created from
7251 <tt>debian/rules</tt> like this:
7252 <example compact="compact">
7253 ln -s ../man7/undocumented.7.gz \
7254 debian/tmp/usr/share/man/man[1-9]/<var>requested_manpage</var>.[1-9].gz
7256 This manpage claims that the lack of a manpage has been
7257 reported as a bug, so you may only do this if it really has
7258 (you can report it yourself, if you like). Do not close the
7259 bug report until a proper manpage is available.</p>
7262 You may forward a complaint about a missing manpage to the
7263 upstream authors, and mark the bug as forwarded in the
7264 Debian bug tracking system. Even though the GNU Project do
7265 not in general consider the lack of a manpage to be a bug,
7266 we do; if they tell you that they don't consider it a bug
7267 you should leave the bug in our bug tracking system open
7271 Manual pages should be installed compressed using <tt>gzip
7275 If one manpage needs to be accessible via several names it
7276 is better to use a symbolic link than the <tt>.so</tt>
7277 feature, but there is no need to fiddle with the relevant
7278 parts of the upstream source to change from <tt>.so</tt> to
7279 symlinks: don't do it unless it's easy. You should not
7280 create hard links in the manual page directories, nor put
7281 absolute filenames in <tt>.so</tt> directives. The filename
7282 in a <tt>.so</tt> in a manpage should be relative to the
7283 base of the manpage tree (usually
7284 <tt>/usr/share/man</tt>). If you do not create any links
7285 (whether symlinks, hard links, or <tt>.so</tt> directives)
7286 in the filesystem to the alternate names of the manpage,
7287 then you should not rely on <prgn>man</prgn> finding your
7288 manpage under those names based solely on the information in
7289 the manpage's header.<footnote>
7291 Supporting this in <prgn>man</prgn> often requires
7292 unreasonable processing time to find a manual page or to
7293 report that none exists, and moves knowledge into man's
7294 database that would be better left in the filesystem.
7295 This support is therefore deprecated and will cease to
7296 be present in the future.
7303 <heading>Info documents</heading>
7306 Info documents should be installed in <tt>/usr/share/info</tt>.
7307 They should be compressed with <tt>gzip -9</tt>.</p>
7310 Your package should call <prgn>install-info</prgn> to update
7311 the Info <tt>dir</tt> file in its <prgn>postinst</prgn>
7312 script when called with a <tt>configure</tt> argument, for
7314 <example compact="compact">
7315 install-info --quiet --section Development Development \
7316 /usr/share/info/foobar.info
7320 It is a good idea to specify a section for the location of
7321 your program; this is done with the <tt>--section</tt>
7322 switch. To determine which section to use, you should look
7323 at <tt>/usr/share/info/dir</tt> on your system and choose the most
7324 relevant (or create a new section if none of the current
7325 sections are relevant). Note that the <tt>--section</tt>
7326 flag takes two arguments; the first is a regular expression
7327 to match (case-insensitively) against an existing section,
7328 the second is used when creating a new one.</p>
7331 You should remove the entries in the <prgn>prerm</prgn>
7332 script when called with a <tt>remove</tt> argument:
7333 <example compact="compact">
7334 install-info --quiet --remove /usr/share/info/foobar.info
7338 If <prgn>install-info</prgn> cannot find a description entry
7339 in the Info file you must supply one. See <manref
7340 name="install-info" section="8"> for details.</p>
7344 <heading>Additional documentation</heading>
7347 Any additional documentation that comes with the package may
7348 be installed at the discretion of the package maintainer.
7349 Text documentation should be installed in the directory
7350 <tt>/usr/share/doc/<var>package</var></tt>, where
7351 <var>package</var> is the name of the package, and
7352 compressed with <tt>gzip -9</tt> unless it is small.</p>
7355 If a package comes with large amounts of documentation which
7356 many users of the package will not require you should create
7357 a separate binary package to contain it, so that it does not
7358 take up disk space on the machines of users who do not need
7359 or want it installed.</p>
7362 It is often a good idea to put text information files
7363 (<tt>README</tt>s, changelogs, and so forth) that come with
7364 the source package in <tt>/usr/share/doc/<var>package</var></tt>
7365 in the binary package. However, you don't need to install
7366 the instructions for building and installing the package, of
7370 Files in <tt>/usr/share/doc</tt> should not be referenced by
7371 any program, and the system administrator should be able to
7372 delete them without causing any programs to break. Any files
7373 that are referenced by programs but are also useful as
7374 standalone documentation should be installed under
7375 <tt>/usr/share/<var>package</var>/</tt> with symbolic links
7376 from <tt>/usr/share/doc/<var>package</var>/</tt>.
7382 <heading>Accessing the documentation</heading>
7385 Former Debian releases placed all additional documentation
7386 in <tt>/usr/doc/<var>package</var></tt>. To realize a
7388 <tt>/usr/share/doc/<var>package</var></tt>, each package
7389 must maintain a symlink <tt>/usr/doc/<var>package</var></tt>
7390 that points to the new location of its documentation in
7391 <tt>/usr/share/doc/<var>package</var></tt><footnote>These
7392 symlinks will be removed in the future, but they have to be
7393 there for compatibility reasons until all packages have
7394 moved and the policy is changed accordingly.</footnote>.
7395 The symlink must be created when the package is installed;
7396 it cannot be contained in the package itself due to problems
7397 with <prgn>dpkg</prgn>. One reasonable way to accomplish
7398 this is to put the following in the package's
7399 <prgn>postinst</prgn><footnote>
7401 The <tt>debhelper</tt> script
7402 <prgn>dh_installdocs</prgn> does this automatically.
7405 <example compact="compact">
7406 if [ "$1" = "configure" ]; then
7407 if [ -d /usr/doc -a ! -e /usr/doc/<var>package</var> \
7408 -a -d /usr/share/doc/<var>package</var> ]; then
7409 ln -sf ../share/doc/<var>package</var> /usr/doc/<var>package</var>
7413 and the following in the package's <prgn>prerm</prgn>:
7414 <example compact="compact">
7415 if [ \( "$1" = "upgrade" -o "$1" = "remove" \) \
7416 -a -L /usr/doc/<var>package</var> ]; then
7417 rm -f /usr/doc/<var>package</var>
7424 <heading>Preferred documentation formats</heading>
7427 The unification of Debian documentation is being carried out
7431 If your package comes with extensive documentation in a
7432 markup format that can be converted to various other formats
7433 you should if possible ship HTML versions in a binary
7434 package, in the directory
7435 <tt>/usr/share/doc/<var>appropriate-package</var></tt> or
7436 its subdirectories.<footnote>
7438 The rationale: The important thing here is that HTML
7439 docs should be available in <em>some</em> package, not
7440 necessarily in the main binary package.
7446 Other formats such as PostScript may be provided at the
7447 package maintainer's discretion.
7451 <sect id="copyrightfile">
7452 <heading>Copyright information</heading>
7455 Every package must be accompanied by a verbatim copy of its
7456 copyright and distribution license in the file
7457 <tt>/usr/share/doc/<var>package</var>/copyright</tt>. This
7458 file must neither be compressed nor be a symbolic link.
7462 In addition, the copyright file must say where the upstream
7463 sources (if any) were obtained, and should explain briefly what
7464 modifications were made in the Debian version of the package
7465 compared to the upstream one. It should name the original
7466 authors of the package and the Debian maintainer(s) who were
7467 involved with its creation.</p>
7470 A copy of the file which will be installed in
7471 <tt>/usr/share/doc/<var>package</var>/copyright</tt> should
7472 be in <tt>debian/copyright</tt> in the source package.
7476 <tt>/usr/share/doc/<var>package</var></tt> may be a symbolic
7477 link to another directory in <tt>/usr/share/doc</tt> only if
7478 the two packages both come from the same source and the
7479 first package Depends on the second. These rules are
7480 important because copyrights must be extractable by
7485 Packages distributed under the UCB BSD license, the Artistic
7486 license, the GNU GPL, and the GNU LGPL should refer to the
7487 files <tt>/usr/share/common-licenses/BSD</tt>,
7488 <tt>/usr/share/common-licenses/Artistic</tt>,
7489 <tt>/usr/share/common-licenses/GPL</tt>, and
7490 <tt>/usr/share/common-licenses/LGPL</tt> respectively,
7491 rather than quoting them in the copyright file.
7495 You should not use the copyright file as a general <tt>README</tt>
7496 file. If your package has such a file it should be
7497 installed in <tt>/usr/share/doc/<var>package</var>/README</tt> or
7498 <tt>README.Debian</tt> or some other appropriate place.</p>
7502 <heading>Examples</heading>
7505 Any examples (configurations, source files, whatever),
7506 should be installed in a directory
7507 <tt>/usr/share/doc/<var>package</var>/examples</tt>. These
7508 files should not be referenced by any program: they're there
7509 for the benefit of the system administrator and users as
7510 documentation only. Architecture-specific example files
7511 should be installed in a directory
7512 <tt>/usr/lib/<var>package</var>/examples</tt> with symbolic
7514 <tt>/usr/share/doc/<var>package</var>/examples</tt>, or the
7515 latter directory itself may be a symbolic link to the
7520 <sect id="instchangelog">
7521 <heading>Changelog files</heading>
7524 Packages that are not Debian-native must contain a
7525 compressed copy of the <tt>debian/changelog</tt> file from
7526 the Debian source tree in
7527 <tt>/usr/share/doc/<var>package</var></tt> with the name
7528 <tt>changelog.Debian.gz</tt>. If an upstream changelog is
7529 available, it should be accessible as
7530 <tt>/usr/share/doc/<var>package</var>/changelog.gz</tt> in
7531 plain text. If the upstream changelog is distributed in
7532 HTML, it should be made available in that form as
7533 <tt>/usr/share/doc/<var>package</var>/changelog.html.gz</tt>
7534 and a plain text <tt>changelog.gz</tt> should be generated
7535 from it using, for example, <tt>lynx -dump -nolist</tt>. If
7536 the upstream changelog files do not already conform to this
7537 naming convention, then this may be achieved either by
7538 renaming the files, or by adding a symbolic link, at the
7539 maintainer's discretion.<footnote>
7541 Rationale: People should not have to look in places for
7542 upstream changelogs merely because they are given
7543 different names or are distributed in HTML format.
7549 All of these files should be installed compressed using
7550 <tt>gzip -9</tt>, as they will become large with time even
7551 if they start out small.
7555 If the package has only one changelog which is used both as
7556 the Debian changelog and the upstream one because there is
7557 no separate upstream maintainer then that changelog should
7558 usually be installed as
7559 <tt>/usr/share/doc/<var>package</var>/changelog.gz</tt>; if
7560 there is a separate upstream maintainer, but no upstream
7561 changelog, then the Debian changelog should still be called
7562 <tt>changelog.Debian.gz</tt>.</p>
7566 <appendix id="pkg-scope">
7567 <heading>Introduction and scope of these appendices</heading>
7570 These appendices are taken essentially verbatim from the
7571 now-deprecated Packaging Manual, version 3.2.1.0. They are
7572 the chapters which are likely to be of use to package
7573 maintainers and which have not already been included in the
7574 policy document itself. Most of these sections are very likely
7575 not relevant to policy; they should be treated as
7576 documentation for the packaging system. Please note that these
7577 appendices are included for convenience, and for historical
7578 reasons: they used to be part of policy package, and they have
7579 not yet been incorporated into dpkg documentation. However,
7580 they still have value, and hence they are presented here.
7583 They have not yet been checked to ensure that they are
7584 compatible with the contents of policy, and if there are any
7585 contradictions, the version in the main policy document takes
7586 precedence. The remaining chapters of the old Packaging
7587 Manual have also not been read in detail to ensure that there
7588 are not parts which have been left out. Both of these will be
7593 <prgn>dpkg</prgn> is a suite of programs for creating binary
7594 package files and installing and removing them on Unix
7597 <prgn>dpkg</prgn> is targetted primarily at Debian
7598 GNU/Linux, but may work on or be ported to other
7605 The binary packages are designed for the management of
7606 installed executable programs (usually compiled binaries) and
7607 their associated data, though source code examples and
7608 documentation are provided as part of some packages.</p>
7611 This manual describes the technical aspects of creating Debian
7612 binary packages (<tt>.deb</tt> files). It documents the
7613 behaviour of the package management programs
7614 <prgn>dpkg</prgn>, <prgn>dselect</prgn> et al. and the way
7615 they interact with packages.</p>
7618 It also documents the interaction between
7619 <prgn>dselect</prgn>'s core and the access method scripts it
7620 uses to actually install the selected packages, and describes
7621 how to create a new access method.</p>
7624 This manual does not go into detail about the options and
7625 usage of the package building and installation tools. It
7626 should therefore be read in conjuction with those programs'
7631 The utility programs which are provided with <prgn>dpkg</prgn>
7632 for managing various system configuration and similar issues,
7633 such as <prgn>update-rc.d</prgn> and
7634 <prgn>install-info</prgn>, are not described in detail here -
7635 please see their manpages.
7639 It does <em>not</em> describe the policy requirements imposed
7640 on Debian packages, such as the permissions on files and
7641 directories, documentation requirements, upload procedure, and
7642 so on. You should see the Debian packaging policy manual for
7643 these details. (Many of them will probably turn out to be
7644 helpful even if you don't plan to upload your package and make
7645 it available as part of the distribution.)
7649 It is assumed that the reader is reasonably familiar with the
7650 <prgn>dpkg</prgn> System Administrators' manual.
7651 Unfortunately this manual does not yet exist.
7655 The Debian version of the FSF's GNU hello program is provided
7656 as an example for people wishing to create Debian
7657 packages. The Debian <prgn>debmake</prgn> package is
7658 recommended as a very helpful tool in creating and maintaining
7659 Debian packages. However, while the tools and examples are
7660 helpful, they do not replace the need to read and follow the
7661 Policy and Programmer's Manual.</p>
7664 <appendix id="pkg-binarypkg"><heading>Binary packages (from old
7669 The binary package has two main sections. The first part
7670 consists of various control information files and scripts used
7671 by <prgn>dpkg</prgn> when installing and removing. See <ref
7672 id="pkg-controlarea">.
7676 The second part is an archive containing the files and
7677 directories to be installed.
7681 In the future binary packages may also contain other
7682 components, such as checksums and digital signatures. The
7683 format for the archive is described in full in the
7684 <tt>deb(5)</tt> manpage.
7688 <sect id="pkg-bincreating"><heading>Creating package files -
7689 <prgn>dpkg-deb</prgn>
7693 All manipulation of binary package files is done by
7694 <prgn>dpkg-deb</prgn>; it's the only program that has
7695 knowledge of the format. (<prgn>dpkg-deb</prgn> may be
7696 invoked by calling <prgn>dpkg</prgn>, as <prgn>dpkg</prgn>
7697 will spot that the options requested are appropriate to
7698 <prgn>dpkg-deb</prgn> and invoke that instead with the same
7703 In order to create a binary package you must make a
7704 directory tree which contains all the files and directories
7705 you want to have in the filesystem data part of the package.
7706 In Debian-format source packages this directory is usually
7707 <tt>debian/tmp</tt>, relative to the top of the package's
7712 They should have the locations (relative to the root of the
7713 directory tree you're constructing) ownerships and
7714 permissions which you want them to have on the system when
7719 With current versions of <prgn>dpkg</prgn> the uid/username
7720 and gid/groupname mappings for the users and groups being
7721 used should be the same on the system where the package is
7722 built and the one where it is installed.
7726 You need to add one special directory to the root of the
7727 miniature filesystem tree you're creating:
7728 <prgn>DEBIAN</prgn>. It should contain the control
7729 information files, notably the binary package control file
7730 (see <ref id="pkg-controlfile">).
7734 The <prgn>DEBIAN</prgn> directory will not appear in the
7735 filesystem archive of the package, and so won't be installed
7736 by <prgn>dpkg</prgn> when the package is installed.
7740 When you've prepared the package, you should invoke:
7742 dpkg --build <var>directory</var>
7747 This will build the package in
7748 <tt><var>directory</var>.deb</tt>. (<prgn>dpkg</prgn> knows
7749 that <tt>--build</tt> is a <prgn>dpkg-deb</prgn> option, so
7750 it invokes <prgn>dpkg-deb</prgn> with the same arguments to
7755 See the manpage <manref name="dpkg-deb" section="8"> for details of how
7756 to examine the contents of this newly-created file. You may find the
7757 output of following commands enlightening:
7759 dpkg-deb --info <var>filename</var>.deb
7760 dpkg-deb --contents <var>filename</var>.deb
7761 dpkg --contents <var>filename</var>.deb
7763 To view the copyright file for a package you could use this command:
7765 dpkg --fsys-tarfile <var>filename</var>.deb | tar xof usr/share/doc/<var>\*</var>copyright | less
7770 <sect id="pkg-controlarea">
7772 Package control information files
7776 The control information portion of a binary package is a
7777 collection of files with names known to <prgn>dpkg</prgn>.
7778 It will treat the contents of these files specially - some
7779 of them contain information used by <prgn>dpkg</prgn> when
7780 installing or removing the package; others are scripts which
7781 the package maintainer wants <prgn>dpkg</prgn> to run.
7785 It is possible to put other files in the package control
7786 area, but this is not generally a good idea (though they
7787 will largely be ignored).
7791 Here is a brief list of the control info files supported by
7792 <prgn>dpkg</prgn> and a summary of what they're used for.
7797 <tag><tt>control</tt>
7801 This is the key description file used by
7802 <prgn>dpkg</prgn>. It specifies the package's name
7803 and version, gives its description for the user,
7804 states its relationships with other packages, and so
7805 forth. See <ref id="pkg-controlfile">.
7809 It is usually generated automatically from information
7810 in the source package by the
7811 <prgn>dpkg-gencontrol</prgn> program, and with
7812 assistance from <prgn>dpkg-shlibdeps</prgn>. See <ref
7813 id="pkg-sourcetools">.</p>
7816 <tag><tt>postinst</tt>, <tt>preinst</tt>, <tt>postrm</tt>,
7822 These are exectuable files (usually scripts) which
7823 <prgn>dpkg</prgn> runs during installation, upgrade
7824 and removal of packages. They allow the package to
7825 deal with matters which are particular to that package
7826 or require more complicated processing than that
7827 provided by <prgn>dpkg</prgn>. Details of when and
7828 how they are called are in <ref
7829 id="maintainerscripts">.
7833 It is very important to make these scripts
7837 That means that if it runs successfully or fails
7838 and then you call it again it doesn't bomb out,
7839 but just ensures that everything is the way it
7842 </footnote> This is so that if an error occurs, the
7843 user interrupts <prgn>dpkg</prgn> or some other
7844 unforeseen circumstance happens you don't leave the
7845 user with a badly-broken package.
7849 The maintainer scripts are guaranteed to run with a
7850 controlling terminal and can interact with the user.
7851 If they need to prompt for passwords, do full-screen
7852 interaction or something similar you should do these
7853 things to and from <tt>/dev/tty</tt>, since
7854 <prgn>dpkg</prgn> will at some point redirect scripts'
7855 standard input and output so that it can log the
7856 installation process. Likewise, because these scripts
7857 may be executed with standard output redirected into a
7858 pipe for logging purposes, Perl scripts should set
7859 unbuffered output by setting <tt>$|=1</tt> so that the
7860 output is printed immediately rather than being
7865 Each script should return a zero exit status for
7866 success, or a nonzero one for failure.</p>
7869 <tag><tt>conffiles</tt>
7874 This file contains a list of configuration files which
7875 are to be handled automatically by <prgn>dpkg</prgn>
7876 (see <ref id="pkg-conffiles">). Note that not necessarily
7877 every configuration file should be listed here.</p>
7880 <tag><tt>shlibs</tt>
7885 This file contains a list of the shared libraries
7886 supplied by the package, with dependency details for
7887 each. This is used by <prgn>dpkg-shlibdeps</prgn>
7888 when it determines what dependencies are required in a
7889 package control file. The <tt>shlibs</tt> file format
7890 is described on <ref id="shlibs">.
7896 <sect id="pkg-controlfile">
7898 The main control information file: <tt>control</tt>
7901 The most important control information file used by
7902 <prgn>dpkg</prgn> when it installs a package is
7903 <tt>control</tt>. It contains all the package's `vital
7908 The binary package control files of packages built from
7909 Debian sources are made by a special tool,
7910 <prgn>dpkg-gencontrol</prgn>, which reads
7911 <tt>debian/control</tt> and <tt>debian/changelog</tt> to
7912 find the information it needs. See <ref id="pkg-sourcepkg"> for
7917 The fields in binary package control files are:
7918 <list compact="compact">
7920 <p><qref id="pkg-f-Package"><tt>Package</tt></qref> (mandatory)</p>
7923 <p><qref id="versions"><tt>Version</tt></qref> (mandatory)</p>
7925 <item><p><qref id="pkg-f-Architecture"><tt>Architecture</tt></qref>
7929 This field should appear in all packages, though
7930 <prgn>dpkg</prgn> doesn't require it yet so that
7931 old packages can still be installed.
7937 <p><qref id="relationships"><tt>Depends</tt>,
7938 <tt>Provides</tt> et al.</qref></p>
7941 <p><qref id="pkg-f-Essential"><tt>Essential</tt></qref></p>
7944 <p><qref id="pkg-f-Maintainer"><tt>Maintainer</tt></qref></p>
7947 <p><qref id="pkg-f-classification"><tt>Section</tt>,
7948 <tt>Priority</tt></qref></p>
7951 <p><qref id="pkg-f-Source"><tt>Source</tt></qref></p>
7954 <p><qref id="descriptions"><tt>Description</tt></qref></p>
7958 <qref id="pkg-f-Installed-Size"><tt>Installed-Size</tt></qref>
7964 A description of the syntax of control files and the purpose
7965 of these fields is available in <ref id="pkg-controlfields">.
7970 <heading>Time Stamps</heading>
7972 Maintainers are encouraged to preserve the modification
7973 times of the upstream source files in a package, as far as
7974 is reasonably possible.
7977 The rationale is that there is some information conveyed
7978 by knowing the age of the file, for example, you could
7979 recognize that some documentation is very old by looking
7980 at the modification time, so it would be nice if the
7981 modification time of the upstream source would be
7989 <appendix id="pkg-sourcepkg">
7990 <heading>Source packages (from old Packaging Manual) </heading>
7993 The Debian binary packages in the distribution are generated
7994 from Debian sources, which are in a special format to assist
7995 the easy and automatic building of binaries.
7999 There was a previous version of the Debian source format,
8000 which is now being phased out. Instructions for converting an
8001 old-style package are given in the Debian policy manual.
8004 <sect id="pkg-sourcetools">
8005 <heading>Tools for processing source packages</heading>
8008 Various tools are provided for manipulating source packages;
8009 they pack and unpack sources and help build of binary
8010 packages and help manage the distribution of new versions.
8014 They are introduced and typical uses described here; see
8015 <manref name="dpkg-source" section="1"> for full
8016 documentation about their arguments and operation.
8020 For examples of how to construct a Debian source package,
8021 and how to use those utilities that are used by Debian
8022 source packages, please see the <prgn>hello</prgn> example
8028 <prgn>dpkg-source</prgn> - packs and unpacks Debian source
8033 This program is frequently used by hand, and is also
8034 called from package-independent automated building scripts
8035 such as <prgn>dpkg-buildpackage</prgn>.
8039 To unpack a package it is typically invoked with
8041 dpkg-source -x <var>.../path/to/filename</var>.dsc
8046 with the <tt><var>filename</var>.tar.gz</tt> and
8047 <tt><var>filename</var>.diff.gz</tt> (if applicable) in
8048 the same directory. It unpacks into
8049 <tt><var>package</var>-<var>version</var></tt>, and if
8051 <tt><var>package</var>-<var>version</var>.orig</tt>, in
8052 the current directory.
8056 To create a packed source archive it is typically invoked:
8058 dpkg-source -b <var>package</var>-<var>version</var>
8063 This will create the <tt>.dsc</tt>, <tt>.tar.gz</tt> and
8064 <tt>.diff.gz</tt> (if appropriate) in the current
8065 directory. <prgn>dpkg-source</prgn> does not clean the
8066 source tree first - this must be done separately if it is
8071 See also <ref id="pkg-sourcearchives">.</p>
8077 <prgn>dpkg-buildpackage</prgn> - overall package-building
8082 <prgn>dpkg-buildpackage</prgn> is a script which invokes
8083 <prgn>dpkg-source</prgn>, the <tt>debian/rules</tt>
8084 targets <tt>clean</tt>, <tt>build</tt> and
8085 <tt>binary</tt>, <prgn>dpkg-genchanges</prgn> and
8086 <prgn>pgp</prgn> to build a signed source and binary
8091 It is usually invoked by hand from the top level of the
8092 built or unbuilt source directory. It may be invoked with
8093 no arguments; useful arguments include:
8094 <taglist compact="compact">
8095 <tag><tt>-uc</tt>, <tt>-us</tt></tag>
8098 Do not PGP-sign the <tt>.changes</tt> file or the
8099 source package <tt>.dsc</tt> file, respectively.</p>
8101 <tag><tt>-p<var>pgp-command</var></tt></tag>
8104 Invoke <var>pgp-command</var> instead of finding
8105 <tt>pgp</tt> on the <prgn>PATH</prgn>.
8106 <var>pgp-command</var> must behave just like
8107 <prgn>pgp</prgn>.</p>
8109 <tag><tt>-r<var>root-command</var></tt></tag>
8112 When root privilege is required, invoke the command
8113 <var>root-command</var>. <var>root-command</var>
8114 should invoke its first argument as a command, from
8115 the <prgn>PATH</prgn> if necessary, and pass its
8116 second and subsequent arguments to the command it
8117 calls. If no <var>root-command</var> is supplied
8118 then <var>dpkg-buildpackage</var> will take no
8119 special action to gain root privilege, so that for
8120 most packages it will have to be invoked as root to
8123 <tag><tt>-b</tt>, <tt>-B</tt></tag>
8126 Two types of binary-only build and upload - see
8127 <manref name="dpkg-source" section="1">.
8136 <prgn>dpkg-gencontrol</prgn> - generates binary package
8141 This program is usually called from <tt>debian/rules</tt>
8142 (see <ref id="pkg-sourcetree">) in the top level of the source
8147 This is usually done just before the files and directories in the
8148 temporary directory tree where the package is being built have their
8149 permissions and ownerships set and the package is constructed using
8150 <prgn>dpkg-deb/</prgn>
8153 This is so that the control file which is produced has
8154 the right permissions
8160 <prgn>dpkg-gencontrol</prgn> must be called after all the
8161 files which are to go into the package have been placed in
8162 the temporary build directory, so that its calculation of
8163 the installed size of a package is correct.
8167 It is also necessary for <prgn>dpkg-gencontrol</prgn> to
8168 be run after <prgn>dpkg-shlibdeps</prgn> so that the
8169 variable substitutions created by
8170 <prgn>dpkg-shlibdeps</prgn> in <tt>debian/substvars</tt>
8175 For a package which generates only one binary package, and
8176 which builds it in <tt>debian/tmp</tt> relative to the top
8177 of the source package, it is usually sufficient to call
8178 <prgn>dpkg-gencontrol</prgn>.
8182 Sources which build several binaries will typically need
8185 dpkg-gencontrol -Pdebian/tmp-<var>pkg</var> -p<var>package</var>
8186 </example> The <tt>-P</tt> tells
8187 <prgn>dpkg-gencontrol</prgn> that the package is being
8188 built in a non-default directory, and the <tt>-p</tt>
8189 tells it which package's control file should be generated.
8193 <prgn>dpkg-gencontrol</prgn> also adds information to the
8194 list of files in <tt>debian/files</tt>, for the benefit of
8195 (for example) a future invocation of
8196 <prgn>dpkg-genchanges</prgn>.</p>
8201 <prgn>dpkg-shlibdeps</prgn> - calculates shared library
8206 This program is usually called from <tt>debian/rules</tt>
8207 just before <prgn>dpkg-gencontrol</prgn> (see <ref
8208 id="pkg-sourcetree">), in the top level of the source tree.
8212 Its arguments are executables.
8215 In a forthcoming dpkg version,
8216 <prgn>dpkg-shlibdeps</prgn> would be required to be
8217 called on shared libraries as well.
8220 They may be specified either in the locations in the
8221 source tree where they are created or in the locations
8222 in the temporary build tree where they are installed
8223 prior to binary package creation.
8225 </footnote> for which shared library dependencies should
8226 be included in the binary package's control file.
8230 If some of the found shared libraries should only
8231 warrant a <tt>Recommends</tt> or <tt>Suggests</tt>, or if
8232 some warrant a <tt>Pre-Depends</tt>, this can be achieved
8233 by using the <tt>-d<var>dependency-field</var></tt> option
8234 before those executable(s). (Each <tt>-d</tt> option
8235 takes effect until the next <tt>-d</tt>.)
8239 <prgn>dpkg-shlibdeps</prgn> does not directly cause the
8240 output control file to be modified. Instead by default it
8241 adds to the <tt>debian/substvars</tt> file variable
8242 settings like <tt>shlibs:Depends</tt>. These variable
8243 settings must be referenced in dependency fields in the
8244 appropriate per-binary-package sections of the source
8249 For example, the <prgn>procps</prgn> package generates two
8250 kinds of binaries, simple C binaries like <prgn>ps</prgn>
8251 which require a predependency and full-screen ncurses
8252 binaries like <prgn>top</prgn> which require only a
8253 recommendation. It can say in its <tt>debian/rules</tt>:
8255 dpkg-shlibdeps -dPre-Depends ps -dRecommends top
8257 and then in its main control file <tt>debian/control</tt>:
8261 Pre-Depends: ${shlibs:Pre-Depends}
8262 Recommends: ${shlibs:Recommends}
8268 Sources which produce several binary packages with
8269 different shared library dependency requirements can use
8270 the <tt>-p<var>varnameprefix</var></tt> option to override
8271 the default <tt>shlib:</tt> prefix (one invocation of
8272 <prgn>dpkg-shlibdeps</prgn> per setting of this option).
8273 They can thus produce several sets of dependency
8274 variables, each of the form
8275 <tt><var>varnameprefix</var>:<var>dependencyfield</var></tt>,
8276 which can be referred to in the appropriate parts of the
8277 binary package control files.
8284 <prgn>dpkg-distaddfile</prgn> - adds a file to
8285 <tt>debian/files</tt>
8289 Some packages' uploads need to include files other than
8290 the source and binary package files.
8294 <prgn>dpkg-distaddfile</prgn> adds a file to the
8295 <tt>debian/files</tt> file so that it will be included in
8296 the <tt>.changes</tt> file when
8297 <prgn>dpkg-genchanges</prgn> is run.
8301 It is usually invoked from the <tt>binary</tt> target of
8302 <tt>debian/rules</tt>:
8304 dpkg-distaddfile <var>filename</var> <var>section</var> <var>priority</var>
8306 The <var>filename</var> is relative to the directory where
8307 <prgn>dpkg-genchanges</prgn> will expect to find it - this
8308 is usually the directory above the top level of the source
8309 tree. The <tt>debian/rules</tt> target should put the
8310 file there just before or just after calling
8311 <prgn>dpkg-distaddfile</prgn>.
8315 The <var>section</var> and <var>priority</var> are passed
8316 unchanged into the resulting <tt>.changes</tt> file. See
8317 <ref id="pkg-f-classification">.
8322 <sect1><heading><prgn>dpkg-genchanges</prgn> - generates a <tt>.changes</tt> upload
8327 This program is usually called by package-independent
8328 automatic building scripts such as
8329 <prgn>dpkg-buildpackage</prgn>, but it may also be called
8334 It is usually called in the top level of a built source
8335 tree, and when invoked with no arguments will print out a
8336 straightforward <tt>.changes</tt> file based on the
8337 information in the source package's changelog and control
8338 file and the binary and source packages which should have
8344 <sect1><heading><prgn>dpkg-parsechangelog</prgn> - produces parsed representation of
8349 This program is used internally by
8350 <prgn>dpkg-source</prgn> et al. It may also occasionally
8351 be useful in <tt>debian/rules</tt> and elsewhere. It
8352 parses a changelog, <tt>debian/changelog</tt> by default,
8353 and prints a control-file format representation of the
8354 information in it to standard output.
8358 <sect1 id="pkg-dpkgarch"><heading><prgn>dpkg-architecture</prgn> -
8359 information about the build and host system
8363 This program can be used manually, but is also invoked by
8364 <tt>dpkg-buildpackage</tt> or <tt>debian/rules</tt> to set
8365 to set environment or make variables which specify the build and
8366 host architecture for the package building process.
8371 <sect id="pkg-sourcetree"><heading>The Debianised source tree
8375 The source archive scheme described later is intended to
8376 allow a Debianised source tree with some associated control
8377 information to be reproduced and transported easily. The
8378 Debianised source tree is a version of the original program
8379 with certain files added for the benefit of the
8380 Debianisation process, and with any other changes required
8381 made to the rest of the source code and installation
8386 The extra files created for Debian are in the subdirectory
8387 <tt>debian</tt> of the top level of the Debianised source
8388 tree. They are described below.
8391 <sect1 id="pkg-debianrules"><heading><tt>debian/rules</tt> - the main building
8396 This file is an executable makefile, and contains the
8397 package-specific recipies for compiling the package and
8398 building binary package(s) out of the source.
8402 It must start with the line <tt>#!/usr/bin/make -f</tt>,
8403 so that it can be invoked by saying its name rather than
8404 invoking <prgn>make</prgn> explicitly.
8408 Since an interactive <tt>debian/rules</tt> script makes it
8409 impossible to autocompile that package and also makes it
8410 hard for other people to reproduce the same binary
8411 package, all <strong>required targets</strong> have to be
8412 non-interactive. At a minimul, required targets are the
8413 ones called by <prgn>dpkg-buildpackage</prgn>, namely,
8414 <em>clean</em>, <em>binary</em>, <em>binary-arch</em>, and
8415 <em>build</em>. It also follows that any target that these
8416 targets depend on must also be non-interactive.
8420 The targets which are required to be present are:
8422 <tag><tt>build</tt></tag>
8425 This should perform all non-interactive
8426 configuration and compilation of the package. If a
8427 package has an interactive pre-build configuration
8428 routine, the Debianised source package should be
8429 built after this has taken place, so that it can be
8430 built without rerunning the configuration.
8434 A package may also provide both of the targets
8435 <tt>build-arch</tt> and <tt>build-indep</tt>. The
8436 <tt>build-arch</tt> target, if provided, should
8437 perform all non-interactive configuration and
8438 compilation required for producing all
8439 architecture-dependant binary packages (those packages
8440 for which the body of the <tt>Architecture</tt> field
8441 in <tt>debian/control</tt> is not <tt>all</tt>).
8442 Similarly, the <tt>build-indep</tt> target, if
8443 provided, should perform all non-interactive
8444 configuration and compilation required for producing
8445 all architecture-independent binary packages (those
8446 packages for which the body of the
8447 <tt>Architecture</tt> field in <tt>debian/control</tt>
8448 is <tt>all</tt>). The <tt>build</tt> target should
8449 depend on those of the targets <tt>build-arch</tt> and
8450 <tt>build-indep</tt> that are provided in the rules
8455 If one or both of the targets <tt>build-arch</tt> and
8456 <tt>build-indep</tt> are not provided, then invoking
8457 <tt>debian/rules</tt> with one of the not-provided
8458 targets as arguments should produce a exit status code
8459 of 2. Usually this is provided automatically by make
8460 if the target is missing.
8464 For some packages, notably ones where the same
8465 source tree is compiled in different ways to produce
8466 two binary packages, the <tt>build</tt> target does
8467 not make much sense. For these packages it is good
8468 enough to provide two (or more) targets
8469 (<tt>build-a</tt> and <tt>build-b</tt> or whatever)
8470 for each of the ways of building the package, and a
8471 <tt>build</tt> target that does nothing. The
8472 <tt>binary</tt> target will have to build the
8473 package in each of the possible ways and make the
8474 binary package out of each.
8478 The targets <tt>build</tt>, <tt>build-arch</tt>
8479 and <tt>build-indep</tt> target must not do
8480 anything that might require root privilege.
8484 The <tt>build</tt> target may need to run
8485 <tt>clean</tt> first - see below.
8489 When a package has a configuration routine that takes
8490 a long time, or when the makefiles are poorly
8491 designed, or when <tt>build</tt> needs to run
8492 <tt>clean</tt> first, it is a good idea to <tt>touch
8493 build</tt> when the build process is complete. This
8494 will ensure that if <tt>debian/rules build</tt> is run
8495 again it will not rebuild the whole program.
8499 <tag><tt>binary</tt>, <tt>binary-arch</tt>,
8500 <tt>binary-indep</tt>
8504 The <tt>binary</tt> target should be all that is
8505 necessary for the user to build the binary
8506 package. All these targets are required to be
8507 non-interactive. It is split into two parts:
8508 <tt>binary-arch</tt> builds the packages' output
8509 files which are specific to a particular
8510 architecture, and <tt>binary-indep</tt> builds
8511 those which are not.
8515 <tt>binary</tt> should usually be a target with
8516 no commands which simply depends on
8517 <prgn>binary-arch</prgn> and
8518 <prgn>binary-indep</prgn>.
8522 Both <prgn>binary-*</prgn> targets should depend on
8523 the <tt>build</tt> target, above, so that the
8524 package is built if it has not been already. It
8525 should then create the relevant binary package(s),
8526 using <prgn>dpkg-gencontrol</prgn> to make their
8527 control files and <prgn>dpkg-deb</prgn> to build
8528 them and place them in the parent of the top level
8533 If one of the <prgn>binary-*</prgn> targets has
8534 nothing to do (this will be always be the case if
8535 the source generates only a single binary package,
8536 whether architecture-dependent or not) it
8537 <em>must</em> still exist, but should always
8542 <ref id="pkg-binarypkg"> describes how to construct
8547 The <tt>binary</tt> targets must be invoked as
8552 <tag><tt>clean</tt></tag>
8556 This should undo any effects that the
8557 <tt>build</tt> and <tt>binary</tt> targets
8558 may have had, except that it should leave alone any
8559 output files created in the parent directory by a
8560 run of <tt>binary</tt>. This target is required
8561 to be non-interactive.
8565 If a <tt>build</tt> file is touched at the end
8566 of the <tt>build</tt> target, as suggested
8567 above, it must be removed as the first thing that
8568 <tt>clean</tt> does, so that running
8569 <tt>build</tt> again after an interrupted
8570 <tt>clean</tt> doesn't think that everything is
8575 The <tt>clean</tt> target must be invoked as
8576 root if <tt>binary</tt> has been invoked since
8577 the last <tt>clean</tt>, or if
8578 <tt>build</tt> has been invoked as root (since
8579 <tt>build</tt> may create directories, for
8584 <tag><tt>get-orig-source</tt> (optional)</tag>
8588 This target fetches the most recent version of the
8589 original source package from a canonical archive
8590 site (via FTP or WWW, for example), does any
8591 necessary rearrangement to turn it into the original
8592 source tarfile format described below, and leaves it
8593 in the current directory.
8597 This target may be invoked in any directory, and
8598 should take care to clean up any temporary files it
8603 This target is optional, but providing it if
8604 possible is a good idea.
8610 The <tt>build</tt>, <tt>binary</tt> and
8611 <tt>clean</tt> targets must be invoked with a current
8612 directory of the package's top-level directory.
8617 Additional targets may exist in <tt>debian/rules</tt>,
8618 either as published or undocumented interfaces or for the
8619 package's internal use.
8623 The architecture we build on and build for is determined by make
8624 variables via dpkg-architecture (see <ref id="pkg-dpkgarch">). You can
8625 get the Debian architecture and the GNU style architecture
8626 specification string for the build machine as well as the host
8627 machine. Here is a list of supported make variables:
8628 <list compact="compact">
8630 <p><tt>DEB_*_ARCH</tt> (the Debian architecture)</p>
8633 <p><tt>DEB_*_GNU_TYPE</tt> (the GNU style architecture
8634 specification string)</p>
8637 <p><tt>DEB_*_GNU_CPU</tt> (the CPU part of DEB_*_GNU_TYPE)</p>
8640 <p><tt>DEB_*_GNU_SYSTEM</tt> (the System part of
8646 where <tt>*</tt> is either <tt>BUILD</tt> for specification of
8647 the build machine or <tt>HOST</tt> for specification of the machine
8652 Backward compatibility can be provided in the rules file
8653 by setting the needed variables to suitable default
8654 values, please refer to the documentation of
8655 dpkg-architecture for details.
8659 It is important to understand that the <tt>DEB_*_ARCH</tt>
8660 string does only determine which Debian architecture we
8661 build on resp. for. It should not be used to get the CPU
8662 or System information, the GNU style variables should be
8668 <sect1><heading><tt>debian/control</tt>
8672 This file contains version-independent details about the
8673 source package and about the binary packages it creates.
8677 It is a series of sets of control fields, each
8678 syntactically similar to a binary package control file.
8679 The sets are separated by one or more blank lines. The
8680 first set is information about the source package in
8681 general; each subsequent set describes one binary package
8682 that the source tree builds.
8686 The syntax and semantics of the fields are described below
8687 in <ref id="pkg-controlfields">.
8691 The general (binary-package-independent) fields are:
8692 <list compact="compact">
8694 <p><qref id="pkg-f-Source"><tt>Source</tt></qref> (mandatory)</p>
8697 <p><qref id="pkg-f-Maintainer"><tt>Maintainer</tt></qref></p>
8701 <qref id="pkg-f-classification"><tt>Section</tt> and
8702 <tt>Priority</tt></qref>
8703 (classification, mandatory)
8708 <qref id="relationships"><tt>Build-Depends</tt> et
8709 al.</qref> (source package interrelationships)
8714 <qref id="pkg-f-Standards-Version"><tt>Standards-Version</tt></qref>
8720 The per-binary-package fields are:
8721 <list compact="compact">
8723 <p><qref id="pkg-f-Package"><tt>Package</tt></qref> (mandatory)</p>
8727 <qref id="pkg-f-Architecture"><tt>Architecture</tt></qref>
8731 <p><qref id="descriptions"><tt>Description</tt></qref></p>
8735 <qref id="pkg-f-classification"><tt>Section</tt> and
8736 <tt>Priority</tt></qref> (classification)</p>
8739 <p><qref id="pkg-f-Essential"><tt>Essential</tt></qref></p>
8743 <qref id="relationships"><tt>Depends</tt> et
8744 al.</qref> (binary package interrelationships)
8750 These fields are used by <prgn>dpkg-gencontrol</prgn> to
8751 generate control files for binary packages (see below), by
8752 <prgn>dpkg-genchanges</prgn> to generate the
8753 <tt>.changes</tt> file to accompany the upload, and by
8754 <prgn>dpkg-source</prgn> when it creates the <tt>.dsc</tt>
8755 source control file as part of a source archive.
8759 The fields here may contain variable references - their
8760 values will be substituted by
8761 <prgn>dpkg-gencontrol</prgn>, <prgn>dpkg-genchanges</prgn>
8762 or <prgn>dpkg-source</prgn> when they generate output
8763 control files. See <ref id="pkg-srcsubstvars"> for details.
8766 <p> <sect2><heading>User-defined fields
8770 Additional user-defined fields may be added to the
8771 source package control file. Such fields will be
8772 ignored, and not copied to (for example) binary or
8773 source package control files or upload control files.
8777 If you wish to add additional unsupported fields to
8778 these output files you should use the mechanism
8783 Fields in the main source control information file with
8784 names starting <tt>X</tt>, followed by one or more of
8785 the letters <tt>BCS</tt> and a hyphen <tt>-</tt>, will
8786 be copied to the output files. Only the part of the
8787 field name after the hyphen will be used in the output
8788 file. Where the letter <tt>B</tt> is used the field
8789 will appear in binary package control files, where the
8790 letter <tt>S</tt> is used in source package control
8791 files and where <tt>C</tt> is used in upload control
8792 (<tt>.changes</tt>) files.
8796 For example, if the main source information control file
8799 XBS-Comment: I stand between the candle and the star.
8801 then the binary and source package control files will contain the
8804 Comment: I stand between the candle and the star.
8811 <sect1 id="pkg-dpkgchangelog"><heading><tt>debian/changelog</tt>
8815 This file records the changes to the Debian-specific parts of the
8819 Though there is nothing stopping an author who is also
8820 the Debian maintainer from using it for all their
8821 changes, it will have to be renamed if the Debian and
8822 upstream maintainers become different
8829 It has a special format which allows the package building
8830 tools to discover which version of the package is being
8831 built and find out other release-specific information.
8835 That format is a series of entries like this:
8837 <var>package</var> (<var>version</var>) <var>distribution(s)</var>; urgency=<var>urgency</var>
8839 * <var>change details</var>
8840 <var>more change details</var>
8841 * <var>even more change details</var>
8843 -- <var>maintainer name and email address</var> <var>date</var>
8848 <var>package</var> and <var>version</var> are the source
8849 package name and version number.
8853 <var>distribution(s)</var> lists the distributions where
8854 this version should be installed when it is uploaded - it
8855 is copied to the <tt>Distribution</tt> field in the
8856 <tt>.changes</tt> file. See <ref id="pkg-f-Distribution">.
8860 <var>urgency</var> is the value for the <tt>Urgency</tt>
8861 field in the <tt>.changes</tt> file for the upload. See
8862 <ref id="pkg-f-Urgency">. It is not possible to specify an
8863 urgency containing commas; commas are used to separate
8864 <tt><var>keyword</var>=<var>value</var></tt> settings in
8865 the <prgn>dpkg</prgn> changelog format (though there is
8866 currently only one useful <var>keyword</var>,
8871 The change details may in fact be any series of lines
8872 starting with at least two spaces, but conventionally each
8873 change starts with an asterisk and a separating space and
8874 continuation lines are indented so as to bring them in
8875 line with the start of the text above. Blank lines may be
8876 used here to separate groups of changes, if desired.
8880 The maintainer name and email address should <em>not</em>
8881 necessarily be those of the usual package maintainer.
8882 They should be the details of the person doing
8883 <em>this</em> version. The information here will be
8884 copied to the <tt>.changes</tt> file, and then later used
8885 to send an acknowledgement when the upload has been
8890 The <var>date</var> should be in RFC822 format
8893 This is generated by the <prgn>822-date</prgn>
8896 </footnote>; it should include the timezone specified
8897 numerically, with the timezone name or abbreviation
8898 optionally present as a comment.
8902 The first `title' line with the package name should start
8903 at the left hand margin; the `trailer' line with the
8904 maintainer and date details should be preceded by exactly
8905 one space. The maintainer details and the date must be
8906 separated by exactly two spaces.
8910 An Emacs mode for editing this format is available: it is
8911 called <tt>debian-changelog-mode</tt>. You can have this
8912 mode selected automatically when you edit a Debian
8913 changelog by adding a local variables clause to the end of
8917 <sect2><heading>Defining alternative changelog formats
8921 It is possible to use a different format to the standard
8922 one, by providing a parser for the format you wish to
8927 In order to have <tt>dpkg-parsechangelog</tt> run your
8928 parser, you must include a line within the last 40 lines
8929 of your file matching the Perl regular expression:
8930 <tt>\schangelog-format:\s+([0-9a-z]+)\W</tt> The part in
8931 parentheses should be the name of the format. For
8932 example, you might say:
8934 @@@ changelog-format: joebloggs @@@
8936 Changelog format names are non-empty strings of alphanumerics.
8940 If such a line exists then <tt>dpkg-parsechangelog</tt>
8941 will look for the parser as
8942 <tt>/usr/lib/dpkg/parsechangelog/<var>format-name</var></tt>
8944 <tt>/usr/local/lib/dpkg/parsechangelog/<var>format-name</var></tt>;
8945 it is an error for it not to find it, or for it not to
8946 be an executable program. The default changelog format
8947 is <tt>dpkg</tt>, and a parser for it is provided with
8948 the <tt>dpkg</tt> package.
8952 The parser will be invoked with the changelog open on
8953 standard input at the start of the file. It should read
8954 the file (it may seek if it wishes) to determine the
8955 information required and return the parsed information
8956 to standard output in the form of a series of control
8957 fields in the standard format. By default it should
8958 return information about only the most recent version in
8959 the changelog; it should accept a
8960 <tt>-v<var>version</var></tt> option to return changes
8961 information from all versions present <em>strictly
8962 after</em> <var>version</var>, and it should then be an
8963 error for <var>version</var> not to be present in the
8969 <list compact="compact">
8971 <p><qref id="pkg-f-Source"><tt>Source</tt></qref></p>
8974 <p><qref id="versions"><tt>Version</tt></qref> (mandatory)</p>
8978 <qref id="pkg-f-Distribution"><tt>Distribution</tt></qref>
8983 <p><qref id="pkg-f-Urgency"><tt>Urgency</tt></qref> (mandatory)</p>
8987 <qref id="pkg-f-Maintainer"><tt>Maintainer</tt></qref>
8992 <p><qref id="pkg-f-Date"><tt>Date</tt></qref></p>
8996 <qref id="pkg-f-Changes"><tt>Changes</tt></qref>
9003 If several versions are being returned (due to the use
9004 of <tt>-v</tt>), the urgency value should be of the
9005 highest urgency code listed at the start of any of the
9006 versions requested followed by the concatenated
9007 (space-separated) comments from all the versions
9008 requested; the maintainer, version, distribution and
9009 date should always be from the most recent version.
9013 For the format of the <tt>Changes</tt> field see <ref
9014 id="pkg-f-Changes">.
9018 If the changelog format which is being parsed always or
9019 almost always leaves a blank line between individual
9020 change notes these blank lines should be stripped out,
9021 so as to make the resulting output compact.
9025 If the changelog format does not contain date or package
9026 name information this information should be omitted from
9027 the output. The parser should not attempt to synthesise
9028 it or find it from other sources.
9032 If the changelog does not have the expected format the
9033 parser should exit with a nonzero exit status, rather
9034 than trying to muddle through and possibly generating
9039 A changelog parser may not interact with the user at
9043 <sect1 id="pkg-srcsubstvars"><heading><tt>debian/substvars</tt>
9044 and variable substitutions
9048 When <prgn>dpkg-gencontrol</prgn>,
9049 <prgn>dpkg-genchanges</prgn> and <prgn>dpkg-source</prgn>
9050 generate control files they do variable substitutions on
9051 their output just before writing it. Variable
9052 substitutions have the form
9053 <tt>${<var>variable-name</var>}</tt>. The optional file
9054 <tt>debian/substvars</tt> contains variable substitutions
9055 to be used; variables can also be set directly from
9056 <tt>debian/rules</tt> using the <tt>-V</tt> option to the
9057 source packaging commands, and certain predefined
9058 variables are available.
9062 The is usually generated and modified dynamically by
9063 <tt>debian/rules</tt> targets; in this case it must be
9064 removed by the <tt>clean</tt> target.
9068 See <manref name="dpkg-source" section="1"> for full
9069 details about source variable substitutions, including the
9070 format of <tt>debian/substvars</tt>.</p>
9073 <sect1><heading><tt>debian/files</tt>
9077 This file is not a permanent part of the source tree; it
9078 is used while building packages to record which files are
9079 being generated. <prgn>dpkg-genchanges</prgn> uses it
9080 when it generates a <tt>.changes</tt> file.
9084 It should not exist in a shipped source package, and so it
9085 (and any backup files or temporary files such as
9089 <tt>files.new</tt> is used as a temporary file by
9090 <prgn>dpkg-gencontrol</prgn> and
9091 <prgn>dpkg-distaddfile</prgn> - they write a new
9092 version of <tt>files</tt> here before renaming it,
9093 to avoid leaving a corrupted copy if an error
9096 </footnote>) should be removed by the
9097 <tt>clean</tt> target. It may also be wise to
9098 ensure a fresh start by emptying or removing it at the
9099 start of the <tt>binary</tt> target.
9103 <prgn>dpkg-gencontrol</prgn> adds an entry to this file
9104 for the <tt>.deb</tt> file that will be created by
9105 <prgn>dpkg-deb</prgn> from the control file that it
9106 generates, so for most packages all that needs to be done
9107 with this file is to delete it in <tt>clean</tt>.
9111 If a package upload includes files besides the source
9112 package and any binary packages whose control files were
9113 made with <prgn>dpkg-gencontrol</prgn> then they should be
9114 placed in the parent of the package's top-level directory
9115 and <prgn>dpkg-distaddfile</prgn> should be called to add
9116 the file to the list in <tt>debian/files</tt>.</p>
9119 <sect1><heading><tt>debian/tmp</tt>
9123 This is the canonical temporary location for the
9124 construction of binary packages by the <tt>binary</tt>
9125 target. The directory <tt>tmp</tt> serves as the root of
9126 the filesystem tree as it is being constructed (for
9127 example, by using the package's upstream makefiles install
9128 targets and redirecting the output there), and it also
9129 contains the <tt>DEBIAN</tt> subdirectory. See <ref
9130 id="pkg-bincreating">.
9134 If several binary packages are generated from the same
9135 source tree it is usual to use several
9136 <tt>debian/tmp<var>something</var></tt> directories, for
9137 example <tt>tmp-a</tt> or <tt>tmp-doc</tt>.
9141 Whatever <tt>tmp</tt> directories are created and used by
9142 <tt>binary</tt> must of course be removed by the
9143 <tt>clean</tt> target.</p></sect1>
9147 <sect id="pkg-sourcearchives"><heading>Source packages as archives
9151 As it exists on the FTP site, a Debian source package
9152 consists of three related files. You must have the right
9153 versions of all three to be able to use them.
9158 <tag>Debian source control file - <tt>.dsc</tt></tag>
9162 This file contains a series of fields, identified and
9163 separated just like the fields in the control file of
9164 a binary package. The fields are listed below; their
9165 syntax is described above, in <ref id="pkg-controlfields">.
9166 <list compact="compact">
9168 <p><qref id="pkg-f-Source"><tt>Source</tt></qref></p>
9171 <p><qref id="versions"><tt>Version</tt></qref></p>
9174 <p><qref id="pkg-f-Maintainer"><tt>Maintainer</tt></qref></p>
9177 <p><qref id="pkg-f-Binary"><tt>Binary</tt></qref></p>
9180 <p><qref id="pkg-f-Architecture"><tt>Architecture</tt></qref></p>
9184 <qref id="relationships"><tt>Build-Depends</tt> et
9185 al.</qref> (source package interrelationships)
9190 <qref id="pkg-f-Standards-Version"><tt>Standards-Version</tt></qref></p>
9193 <p><qref id="pkg-f-Files"><tt>Files</tt></qref></p>
9198 The source package control file is generated by
9199 <prgn>dpkg-source</prgn> when it builds the source
9200 archive, from other files in the source package,
9201 described above. When unpacking it is checked against
9202 the files and directories in the other parts of the
9203 source package, as described below.</p>
9207 Original source archive -
9209 <var>package</var>_<var>upstream-version</var>.orig.tar.gz
9216 This is a compressed (with <tt>gzip -9</tt>)
9217 <prgn>tar</prgn> file containing the source code from
9218 the upstream authors of the program. The tarfile
9219 unpacks into a directory
9220 <tt><var>package</var>-<var>upstream-version</var>.orig</tt>,
9221 and does not contain files anywhere other than in
9222 there or in its subdirectories.</p>
9226 Debianisation diff -
9228 <var>package</var>_<var>upstream_version-revision</var>.diff.gz
9234 This is a unified context diff (<tt>diff -u</tt>)
9235 giving the changes which are required to turn the
9236 original source into the Debian source. These changes
9237 may only include editing and creating plain files.
9238 The permissions of files, the targets of symbolic
9239 links and the characteristics of special files or
9240 pipes may not be changed and no files may be removed
9245 All the directories in the diff must exist, except the
9246 <tt>debian</tt> subdirectory of the top of the source
9247 tree, which will be created by
9248 <prgn>dpkg-source</prgn> if necessary when unpacking.
9252 The <prgn>dpkg-source</prgn> program will
9253 automatically make the <tt>debian/rules</tt> file
9254 executable (see below).</p></item>
9259 If there is no original source code - for example, if the
9260 package is specially prepared for Debian or the Debian
9261 maintainer is the same as the upstream maintainer - the
9262 format is slightly different: then there is no diff, and the
9264 <tt><var>package</var>_<var>version</var>.tar.gz</tt> and
9265 contains a directory
9266 <tt><var>package</var>-<var>version</var></tt>.
9270 <sect><heading>Unpacking a Debian source package without
9271 <prgn>dpkg-source</prgn>
9275 <tt>dpkg-source -x</tt> is the recommended way to unpack a
9276 Debian source package. However, if it is not available it
9277 is possible to unpack a Debian source archive as follows:
9278 <enumlist compact="compact">
9281 Untar the tarfile, which will create a <tt>.orig</tt>
9285 <p>Rename the <tt>.orig</tt> directory to
9286 <tt><var>package</var>-<var>version</var></tt>.</p>
9290 Create the subdirectory <tt>debian</tt> at the top of
9291 the source tree.</p>
9293 <item><p>Apply the diff using <tt>patch -p0</tt>.</p>
9295 <item><p>Untar the tarfile again if you want a copy of the original
9296 source code alongside the Debianised version.</p>
9301 It is not possible to generate a valid Debian source archive
9302 without using <prgn>dpkg-source</prgn>. In particular,
9303 attempting to use <prgn>diff</prgn> directly to generate the
9304 <tt>.diff.gz</tt> file will not work.
9307 <sect1><heading>Restrictions on objects in source packages
9311 The source package may not contain any hard links
9314 This is not currently detected when building source
9315 packages, but only when extracting
9321 Hard links may be permitted at some point in the
9322 future, but would require a fair amount of
9325 </footnote>, device special files, sockets or setuid or
9329 Setgid directories are allowed.
9335 The source packaging tools manage the changes between the
9336 original and Debianised source using <prgn>diff</prgn> and
9337 <prgn>patch</prgn>. Turning the original source tree as
9338 included in the <tt>.orig.tar.gz</tt> into the debianised
9339 source must not involve any changes which cannot be
9340 handled by these tools. Problematic changes which cause
9341 <prgn>dpkg-source</prgn> to halt with an error when
9342 building the source package are:
9343 <list compact="compact">
9344 <item><p>Adding or removing symbolic links, sockets or pipes.</p>
9346 <item><p>Changing the targets of symbolic links.</p>
9348 <item><p>Creating directories, other than <tt>debian</tt>.</p>
9350 <item><p>Changes to the contents of binary files.</p></item>
9351 </list> Changes which cause <prgn>dpkg-source</prgn> to
9352 print a warning but continue anyway are:
9353 <list compact="compact">
9356 Removing files, directories or symlinks.
9359 Renaming a file is not treated specially - it is
9360 seen as the removal of the old file (which
9361 generates a warning, but is otherwise ignored),
9362 and the creation of the new
9369 Changed text files which are missing the usual final
9370 newline (either in the original or the modified
9375 Changes which are not represented, but which are not detected by
9376 <prgn>dpkg-source</prgn>, are:
9377 <list compact="compact">
9378 <item><p>Changing the permissions of files (other than
9379 <tt>debian/rules</tt>) and directories.</p></item>
9384 The <tt>debian</tt> directory and <tt>debian/rules</tt>
9385 are handled specially by <prgn>dpkg-source</prgn> - before
9386 applying the changes it will create the <tt>debian</tt>
9387 directory, and afterwards it will make
9388 <tt>debian/rules</tt> world-exectuable.
9394 <appendix id="pkg-controlfields"><heading>Control files and their
9395 fields (from old Packaging Manual)
9399 Many of the tools in the <prgn>dpkg</prgn> suite manipulate
9400 data in a common format, known as control files. Binary and
9401 source packages have control data as do the <tt>.changes</tt>
9402 files which control the installation of uploaded files, and
9403 <prgn>dpkg</prgn>'s internal databases are in a similar
9407 <sect><heading>Syntax of control files
9411 A file consists of one or more paragraphs of fields. The
9412 paragraphs are separated by blank lines. Some control files
9413 only allow one paragraph; others allow several, in which
9414 case each paragraph often refers to a different package.
9418 Each paragraph is a series of fields and values; each field
9419 consists of a name, followed by a colon and the value. It
9420 ends at the end of the line. Horizontal whitespace (spaces
9421 and tabs) may occur before or after the value and is ignored
9422 there; it is conventional to put a single space after the
9427 Some fields' values may span several lines; in this case
9428 each continuation line <em>must</em> start with a space or
9429 tab. Any trailing spaces or tabs at the end of individual
9430 lines of a field value are ignored.
9434 Except where otherwise stated only a single line of data is
9435 allowed and whitespace is not significant in a field body.
9436 Whitespace may never appear inside names (of packages,
9437 architectures, files or anything else), version numbers or
9438 in between the characters of multi-character version
9443 Field names are not case-sensitive, but it is usual to
9444 capitalise the field names using mixed case as shown below.
9448 Blank lines, or lines consisting only of spaces and tabs,
9449 are not allowed within field values or between fields - that
9450 would mean a new paragraph.
9454 It is important to note that there are several fields which
9455 are optional as far as <prgn>dpkg</prgn> and the related
9456 tools are concerned, but which must appear in every Debian
9457 package, or whose omission may cause problems. When writing
9458 the control files for Debian packages you <em>must</em> read
9459 the Debian policy manual in conjuction with the details
9460 below and the list of fields for the particular file.</p>
9463 <sect><heading>List of fields
9466 <sect1 id="pkg-f-Package"><heading><tt>Package</tt>
9470 The name of the binary package. Package names consist of
9471 the alphanumerics and <tt>+</tt> <tt>-</tt> <tt>.</tt>
9472 (plus, minus and full stop).
9475 The characters <tt>@</tt> <tt>:</tt> <tt>=</tt>
9476 <tt>%</tt> <tt>_</tt> (at, colon, equals, percent
9477 and underscore) used to be legal and are still
9478 accepted when found in a package file, but may not be
9479 used in new packages
9485 They must be at least two characters and must start with
9486 an alphanumeric. In current versions of dpkg they are
9487 sort of case-sensitive<footnote><p>This is a
9488 bug.</p></footnote>; use lowercase package names unless
9489 the package you're building (or referring to, in other
9490 fields) is already using uppercase.</p>
9493 <sect1 id="pkg-f-Version"><heading><tt>Version</tt>
9497 This lists the source or binary package's version number -
9498 see <ref id="versions">.
9503 <sect1 id="pkg-f-Architecture"><heading><tt>Architecture</tt>
9507 This is the architecture string; it is a single word for
9508 the Debian architecture.
9512 <prgn>dpkg</prgn> will check the declared architecture of
9513 a binary package against its own compiled-in value before
9518 The special value <tt>all</tt> indicates that the package
9519 is architecture-independent.
9523 In the main <tt>debian/control</tt> file in the source
9524 package, or in the source package control file
9525 <tt>.dsc</tt>, a list of architectures (separated by
9526 spaces) is also allowed, as is the special value
9527 <tt>any</tt>. A list indicates that the source will build
9528 an architecture-dependent package, and will only work
9529 correctly on the listed architectures. <tt>any</tt>
9530 indicates that though the source package isn't dependent
9531 on any particular architecture and should compile fine on
9532 any one, the binary package(s) produced are not
9533 architecture-independent but will instead be specific to
9534 whatever the current build architecture is.
9538 In a <tt>.changes</tt> file the <tt>Architecture</tt>
9539 field lists the architecture(s) of the package(s)
9540 currently being uploaded. This will be a list; if the
9541 source for the package is being uploaded too the special
9542 entry <tt>source</tt> is also present.
9546 See <ref id="pkg-debianrules"> for information how to get the
9547 architecture for the build process.
9551 <sect1 id="pkg-f-Maintainer"><heading><tt>Maintainer</tt>
9555 The package maintainer's name and email address. The name
9556 should come first, then the email address inside angle
9557 brackets <tt><></tt> (in RFC822 format).
9561 If the maintainer's name contains a full stop then the
9562 whole field will not work directly as an email address due
9563 to a misfeature in the syntax specified in RFC822; a
9564 program using this field as an address must check for this
9565 and correct the problem if necessary (for example by
9566 putting the name in round brackets and moving it to the
9567 end, and bringing the email address forward).
9571 In a <tt>.changes</tt> file or parsed changelog data this
9572 contains the name and email address of the person
9573 responsible for the particular version in question - this
9574 may not be the package's usual maintainer.
9578 This field is usually optional in as far as the
9579 <prgn>dpkg</prgn> are concerned, but its absence when
9580 building packages usually generates a warning.</p>
9583 <sect1 id="pkg-f-Source"><heading><tt>Source</tt>
9587 This field identifies the source package name.
9591 In a main source control information or a
9592 <tt>.changes</tt> or <tt>.dsc</tt> file or parsed
9593 changelog data this may contain only the name of the
9598 In the control file of a binary package (or in a
9599 <tt>Packages</tt> file) it may be followed by a version
9600 number in parentheses.
9603 It is usual to leave a space after the package name if
9604 a version number is specified.
9606 </footnote> This version number may be omitted (and is, by
9607 <prgn>dpkg-gencontrol</prgn>) if it has the same value as
9608 the <tt>Version</tt> field of the binary package in
9609 question. The field itself may be omitted from a binary
9610 package control file when the source package has the same
9611 name and version as the binary package.
9615 <sect1><heading>Package interrelationship fields:
9616 <tt>Depends</tt>, <tt>Pre-Depends</tt>,
9617 <tt>Recommends</tt> <tt>Suggests</tt>, <tt>Conflicts</tt>,
9618 <tt>Provides</tt>, <tt>Replaces</tt>
9622 These fields describe the package's relationships with
9623 other packages. Their syntax and semantics are described
9624 in <ref id="relationships">.</p>
9627 <sect1 id="pkg-f-Description"><heading><tt>Description</tt>
9631 In a binary package <tt>Packages</tt> file or main source
9632 control file this field contains a description of the
9633 binary package, in a special format. See <ref
9634 id="descriptions"> for details.
9638 In a <tt>.changes</tt> file it contains a summary of the
9639 descriptions for the packages being uploaded. The part of
9640 the field before the first newline is empty; thereafter
9641 each line has the name of a binary package and the summary
9642 description line from that binary package. Each line is
9643 indented by one space.</p>
9646 <sect1 id="pkg-f-Essential"><heading><tt>Essential</tt>
9650 This is a boolean field which may occur only in the
9651 control file of a binary package (or in the
9652 <tt>Packages</tt> file) or in a per-package fields
9653 paragraph of a main source control data file.
9657 If set to <tt>yes</tt> then <prgn>dpkg</prgn> and
9658 <prgn>dselect</prgn> will refuse to remove the package
9659 (though it can be upgraded and/or replaced). The other
9660 possible value is <tt>no</tt>, which is the same as not
9661 having the field at all.</p>
9664 <sect1 id="pkg-f-classification"><heading><tt>Section</tt> and
9669 These two fields classify the package. The
9670 <tt>Priority</tt> represents how important that it is that
9671 the user have it installed; the <tt>Section</tt>
9672 represents an application area into which the package has
9677 When they appear in the <tt>debian/control</tt> file these
9678 fields give values for the section and priority subfields
9679 of the <tt>Files</tt> field of the <tt>.changes</tt> file,
9680 and give defaults for the section and priority of the
9685 The section and priority are represented, though not as
9686 separate fields, in the information for each file in the
9687 <qref id="pkg-f-Files"><tt>-File</tt></qref>field of a
9688 <tt>.changes</tt> file. The section value in a
9689 <tt>.changes</tt> file is used to decide where to install
9690 a package in the FTP archive.
9694 These fields are not used by by <prgn>dpkg</prgn> proper,
9695 but by <prgn>dselect</prgn> when it sorts packages and
9696 selects defaults. See the Debian policy manual for the
9697 priorities in use and the criteria for selecting the
9698 priority for a Debian package, and look at the Debian FTP
9699 archive for a list of currently in-use priorities.
9703 These fields may appear in binary package control files,
9704 in which case they provide a default value in case the
9705 <tt>Packages</tt> files are missing the information.
9706 <prgn>dpkg</prgn> and <prgn>dselect</prgn> will only use
9707 the value from a <tt>.deb</tt> file if they have no other
9708 information; a value listed in a <tt>Packages</tt> file
9709 will always take precedence. By default
9710 <prgn>dpkg-gencontrol</prgn> does not include the section
9711 and priority in the control file of a binary package - use
9712 the <tt>-isp</tt>, <tt>-is</tt> or <tt>-ip</tt> options to
9713 achieve this effect.</p>
9716 <sect1 id="pkg-f-Binary"><heading><tt>Binary</tt>
9720 This field is a list of binary packages.
9724 When it appears in the <tt>.dsc</tt> file it is the list
9725 of binary packages which a source package can produce. It
9726 does not necessarily produce all of these binary packages
9727 for every architecture. The source control file doesn't
9728 contain details of which architectures are appropriate for
9729 which of the binary packages.
9733 When it appears in a <tt>.changes</tt> file it lists the
9734 names of the binary packages actually being uploaded.
9738 The syntax is a list of binary packages separated by
9742 A space after each comma is conventional.
9744 </footnote> Currently the packages must be separated using
9745 only spaces in the <tt>.changes</tt> file.</p>
9748 <sect1 id="pkg-f-Installed-Size"><heading><tt>Installed-Size</tt>
9752 This field appears in the control files of binary
9753 packages, and in the <tt>Packages</tt> files. It gives
9754 the total amount of disk space required to install the
9759 The disk space is represented in kilobytes as a simple
9763 <sect1 id="pkg-f-Files"><heading><tt>Files</tt>
9767 This field contains a list of files with information about
9768 each one. The exact information and syntax varies with
9769 the context. In all cases the the part of the field
9770 contents on the same line as the field name is empty. The
9771 remainder of the field is one line per file, each line
9772 being indented by one space and containing a number of
9773 sub-fields separated by spaces.
9777 In the <tt>.dsc</tt> (Debian source control) file each
9778 line contains the MD5 checksum, size and filename of the
9779 tarfile and (if applicable) diff file which make up the
9780 remainder of the source package.
9783 That is, the parts which are not the
9786 </footnote> The exact forms of the filenames are described
9787 in <ref id="pkg-sourcearchives">.
9791 In the <tt>.changes</tt> file this contains one line per
9792 file being uploaded. Each line contains the MD5 checksum,
9793 size, section and priority and the filename. The section
9794 and priority are the values of the corresponding fields in
9795 the main source control file - see <ref
9796 id="pkg-f-classification">. If no section or priority is
9797 specified then <tt>-</tt> should be used, though section
9798 and priority values must be specified for new packages to
9799 be installed properly.
9803 The special value <tt>byhand</tt> for the section in a
9804 <tt>.changes</tt> file indicates that the file in question
9805 is not an ordinary package file and must by installed by
9806 hand by the distribution maintainers. If the section is
9807 <tt>byhand</tt> the priority should be <tt>-</tt>.
9811 If a new Debian revision of a package is being shipped and
9812 no new original source archive is being distributed the
9813 <tt>.dsc</tt> must still contain the <tt>Files</tt> field
9814 entry for the original source archive
9815 <tt><var>package</var>-<var>upstream-version</var>.orig.tar.gz</tt>,
9816 but the <tt>.changes</tt> file should leave it out. In
9817 this case the original source archive on the distribution
9818 site must match exactly, byte-for-byte, the original
9819 source archive which was used to generate the
9820 <tt>.dsc</tt> file and diff which are being uploaded.</p>
9825 id="pkg-f-Standards-Version"><heading><tt>Standards-Version</tt>
9829 The most recent version of the standards (the
9830 <prgn>dpkg</prgn> programmers' and policy manuals and
9831 associated texts) with which the package complies. This
9832 is updated manually when editing the source package to
9833 conform to newer standards; it can sometimes be used to
9834 tell when a package needs attention.
9838 Its format is the same as that of a version number except
9839 that no epoch or Debian revision is allowed - see <ref
9844 <sect1 id="pkg-f-Distribution"><heading><tt>Distribution</tt>
9848 In a <tt>.changes</tt> file or parsed changelog output
9849 this contains the (space-separated) name(s) of the
9850 distribution(s) where this version of the package should
9851 be or was installed. Distribution names follow the rules
9852 for package names. (See <ref id="pkg-f-Package">).
9856 Current distribution values are:
9858 <tag><em>stable</em></tag>
9861 This is the current `released' version of Debian
9862 GNU/Linux. A new version is released approximately
9863 every 3 months after the <em>development</em> code has
9864 been <em>frozen</em> for a month of testing. Once the
9865 distribution is <em>stable</em> only major bug fixes
9866 are allowed. When changes are made to this
9867 distribution, the release number is increased
9868 (for example: 1.2r1 becomes 1.2r2 then 1.2r3, etc).
9872 <tag><em>unstable</em></tag>
9875 This distribution value refers to the
9876 <em>developmental</em> part of the Debian distribution
9877 tree. New packages, new upstream versions of packages
9878 and bug fixes go into the <em>unstable</em> directory
9879 tree. Download from this distribution at your own
9883 <tag><em>contrib</em></tag>
9886 The packages with this distribution value do not meet
9887 the criteria for inclusion in the main Debian
9888 distribution as defined by the Policy Manual, but meet
9889 the criteria for the <em>contrib</em>
9890 Distribution. There is currently no distinction
9891 between stable and unstable packages in the
9892 <em>contrib</em> or <em>non-free</em>
9893 distributions. Use your best judgement in downloading
9894 from this Distribution.</p>
9897 <tag><em>non-free</em></tag>
9900 Like the packages in the <em>contrib</em> seciton,
9901 the packages in <em>non-free</em> do not meet the
9902 criteria for inclusion in the main Debian distribution
9903 as defined by the Policy Manual. Again, use your best
9904 judgement in downloading from this Distribution.</p>
9906 <tag><em>experimental</em></tag>
9909 The packages with this distribution value are deemed
9910 by their maintainers to be high risk. Oftentimes they
9911 represent early beta or developmental packages from
9912 various sources that the maintainers want people to
9913 try, but are not ready to be a part of the other parts
9914 of the Debian distribution tree. Download at your own
9918 <tag><em>frozen</em></tag>
9921 From time to time, (currently, every 3 months) the
9922 <em>unstable</em> distribution enters a state of
9923 `code-freeze' in anticipation of release as a
9924 <em>stable</em> version. During this period of testing
9925 (usually 4 weeks) only fixes for existing or
9926 newly-discovered bugs will be allowed.
9929 </taglist> You should list <em>all</em> distributions that
9930 the package should be installed into. Except in unusual
9931 circumstances, installations to <em>stable</em> should also
9932 go into <em>frozen</em> (if it exists) and
9933 <em>unstable</em>. Likewise, installations into
9934 <em>frozen</em> should also go into <em>unstable</em>.</p>
9937 <sect1 id="pkg-f-Urgency"><heading><tt>Urgency</tt>
9941 This is a description of how important it is to upgrade to
9942 this version from previous ones. It consists of a single
9943 keyword usually taking one of the values <tt>LOW</tt>,
9944 <tt>MEDIUM</tt> or <tt>HIGH</tt>) followed by an optional
9945 commentary (separated by a space) which is usually in
9946 parentheses. For example:
9948 Urgency: LOW (HIGH for diversions users)
9953 This field appears in the <tt>.changes</tt> file and in
9954 parsed changelogs; its value appears as the value of the
9955 <tt>urgency</tt> attribute in a <prgn>dpkg</prgn>-style
9956 changelog (see <ref id="pkg-dpkgchangelog">).
9960 Urgency keywords are not case-sensitive.</p>
9963 <sect1 id="pkg-f-Date"><heading><tt>Date</tt>
9967 In <tt>.changes</tt> files and parsed changelogs, this
9968 gives the date the package was built or last edited.</p>
9971 <sect1 id="pkg-f-Format"><heading><tt>Format</tt>
9975 This field occurs in <tt>.changes</tt> files, and
9976 specifies a format revision for the file. The format
9977 described here is version <tt>1.5</tt>. The syntax of the
9978 format value is the same as that of a package version
9979 number except that no epoch or Debian revision is allowed
9980 - see <ref id="versions">.</p>
9983 <sect1 id="pkg-f-Changes"><heading><tt>Changes</tt>
9987 In a <tt>.changes</tt> file or parsed changelog this field
9988 contains the human-readable changes data, describing the
9989 differences between the last version and the current one.
9993 There should be nothing in this field before the first
9994 newline; all the subsequent lines must be indented by at
9995 least one space; blank lines must be represented by a line
9996 consiting only of a space and a full stop.
10000 Each version's change information should be preceded by a
10001 `title' line giving at least the version, distribution(s)
10002 and urgency, in a human-readable way.
10006 If data from several versions is being returned the entry
10007 for the most recent version should be returned first, and
10008 entries should be separated by the representation of a
10009 blank line (the `title' line may also be followed by the
10010 representation of blank line).</p>
10013 <sect1 id="pkg-f-Filename"><heading><tt>Filename</tt> and
10014 <tt>MSDOS-Filename</tt>
10018 These fields in <tt>Packages</tt> files give the
10019 filename(s) of (the parts of) a package in the
10020 distribution directories, relative to the root of the
10021 Debian hierarchy. If the package has been split into
10022 several parts the parts are all listed in order, separated
10026 <sect1 id="pkg-f-Size"><heading><tt>Size</tt> and <tt>MD5sum</tt>
10030 These fields in <tt>Packages</tt> files give the size (in
10031 bytes, expressed in decimal) and MD5 checksum of the
10032 file(s) which make(s) up a binary package in the
10033 distribution. If the package is split into several parts
10034 the values for the parts are listed in order, separated by
10038 <sect1 id="pkg-f-Status"><heading><tt>Status</tt>
10042 This field in <prgn>dpkg</prgn>'s status file records
10043 whether the user wants a package installed, removed or
10044 left alone, whether it is broken (requiring
10045 reinstallation) or not and what its current state on the
10046 system is. Each of these pieces of information is a
10050 <sect1 id="pkg-f-Config-Version"><heading><tt>Config-Version</tt>
10054 If a package is not installed or not configured, this
10055 field in <prgn>dpkg</prgn>'s status file records the last
10056 version of the package which was successfully
10060 <sect1 id="pkg-f-Conffiles"><heading><tt>Conffiles</tt>
10064 This field in <prgn>dpkg</prgn>'s status file contains
10065 information about the automatically-managed configuration
10066 files held by a package. This field should <em>not</em>
10067 appear anywhere in a package!</p>
10070 <sect1><heading>Obsolete fields
10074 These are still recognised by <prgn>dpkg</prgn> but should
10075 not appear anywhere any more.
10076 <taglist compact="compact">
10078 <tag><tt>Revision</tt></tag>
10079 <tag><tt>Package-Revision</tt></tag>
10080 <tag><tt>Package_Revision</tt></tag>
10083 The Debian revision part of the package version was
10084 at one point in a separate control file field. This
10085 field went through several names.</p>
10088 <tag><tt>Recommended</tt></tag>
10089 <item><p>Old name for <tt>Recommends</tt></p>
10092 <tag><tt>Optional</tt></tag>
10093 <item><p>Old name for <tt>Suggests</tt>.</p>
10095 <tag><tt>Class</tt></tag>
10096 <item><p>Old name for <tt>Priority</tt>.</p>
10104 <appendix id="pkg-conffiles"><heading>Configuration file handling
10105 (from old Packaging Manual)
10109 <prgn>dpkg</prgn> can do a certain amount of automatic
10110 handling of package configuration files.
10114 Whether this mechanism is appropriate depends on a number of
10115 factors, but basically there are two approaches to any
10116 particular configuration file.
10120 The easy method is to ship a best-effort configuration in the
10121 package, and use <prgn>dpkg</prgn>'s conffile mechanism to
10122 handle updates. If the user is unlikely to want to edit the
10123 file, but you need them to be able to without losing their
10124 changes, and a new package with a changed version of the file
10125 is only released infrequently, this is a good approach.
10129 The hard method is to build the configuration file from
10130 scratch in the <prgn>postinst</prgn> script, and to take the
10131 responsibility for fixing any mistakes made in earlier
10132 versions of the package automatically. This will be
10133 appropriate if the file is likely to need to be different on
10137 <sect><heading>Automatic handling of configuration files by
10142 A package may contain a control area file called
10143 <tt>conffiles</tt>. This file should be a list of filenames
10144 of configuration files needing automatic handling, separated
10145 by newlines. The filenames should be absolute pathnames,
10146 and the files referred to should actually exist in the
10151 When a package is upgraded <prgn>dpkg</prgn> will process
10152 the configuration files during the configuration stage,
10153 shortly before it runs the package's <prgn>postinst</prgn>
10158 For each file it checks to see whether the version of the
10159 file included in the package is the same as the one that was
10160 included in the last version of the package (the one that is
10161 being upgraded from); it also compares the version currently
10162 installed on the system with the one shipped with the last
10167 If neither the user nor the package maintainer has changed
10168 the file, it is left alone. If one or the other has changed
10169 their version, then the changed version is preferred - i.e.,
10170 if the user edits their file, but the package maintainer
10171 doesn't ship a different version, the user's changes will
10172 stay, silently, but if the maintainer ships a new version
10173 and the user hasn't edited it the new version will be
10174 installed (with an informative message). If both have
10175 changed their version the user is prompted about the problem
10176 and must resolve the differences themselves.
10180 The comparisons are done by calculating the MD5 message
10181 digests of the files, and storing the MD5 of the file as it
10182 was included in the most recent version of the package.
10186 When a package is installed for the first time
10187 <prgn>dpkg</prgn> will install the file that comes with it,
10188 unless that would mean overwriting a file already on the
10193 However, note that <prgn>dpkg</prgn> will <em>not</em>
10194 replace a conffile that was removed by the user (or by a
10195 script). This is necessary because with some programs a
10196 missing file produces an effect hard or impossible to
10197 achieve in another way, so that a missing file needs to be
10198 kept that way if the user did it.
10202 Note that a package should <em>not</em> modify a
10203 <prgn>dpkg</prgn>-handled conffile in its maintainer
10204 scripts. Doing this will lead to <prgn>dpkg</prgn> giving
10205 the user confusing and possibly dangerous options for
10206 conffile update when the package is upgraded.</p>
10209 <sect><heading>Fully-featured maintainer script configuration
10214 For files which contain site-specific information such as
10215 the hostname and networking details and so forth, it is
10216 better to create the file in the package's
10217 <prgn>postinst</prgn> script.
10221 This will typically involve examining the state of the rest
10222 of the system to determine values and other information, and
10223 may involve prompting the user for some information which
10224 can't be obtained some other way.
10228 When using this method there are a couple of important
10229 issues which should be considered:
10233 If you discover a bug in the program which generates the
10234 configuration file, or if the format of the file changes
10235 from one version to the next, you will have to arrange for
10236 the postinst script to do something sensible - usually this
10237 will mean editing the installed configuration file to remove
10238 the problem or change the syntax. You will have to do this
10239 very carefully, since the user may have changed the file,
10240 perhaps to fix the very problem that your script is trying
10241 to deal with - you will have to detect these situations and
10242 deal with them correctly.
10246 If you do go down this route it's probably a good idea to
10247 make the program that generates the configuration file(s) a
10248 separate program in <tt>/usr/sbin</tt>, by convention called
10249 <tt><var>package</var>config</tt> and then run that if
10250 appropriate from the post-installation script. The
10251 <tt><var>package</var>config</tt> program should not
10252 unquestioningly overwrite an existing configuration - if its
10253 mode of operation is geared towards setting up a package for
10254 the first time (rather than any arbitrary reconfiguration
10255 later) you should have it check whether the configuration
10256 already exists, and require a <tt>--force</tt> flag to
10257 overwrite it.</p></sect>
10260 <appendix id="pkg-alternatives"><heading>Alternative versions of
10261 an interface - <prgn>update-alternatives</prgn> (from old
10266 When several packages all provide different versions of the
10267 same program or file it is useful to have the system select a
10268 default, but to allow the system administrator to change it
10269 and have their decisions respected.
10273 For example, there are several versions of the <prgn>vi</prgn>
10274 editor, and there is no reason to prevent all of them from
10275 being installed at once, each under their own name
10276 (<prgn>nvi</prgn>, <prgn>vim</prgn> or whatever).
10277 Nevertheless it is desirable to have the name <tt>vi</tt>
10278 refer to something, at least by default.
10282 If all the packages involved cooperate, this can be done with
10283 <prgn>update-alternatives</prgn>.
10287 Each package provides its own version under its own name, and
10288 calls <prgn>update-alternatives</prgn> in its postinst to
10289 register its version (and again in its prerm to deregister
10294 See the manpage <manref name="update-alternatives"
10295 section="8"> for details.
10299 If <prgn>update-alternatives</prgn> does not seem appropriate
10300 you may wish to consider using diversions instead.</p>
10303 <appendix id="pkg-diversions"><heading>Diversions - overriding a
10304 package's version of a file (from old Packaging Manual)
10308 It is possible to have <prgn>dpkg</prgn> not overwrite a file
10309 when it reinstalls the package it belongs to, and to have it
10310 put the file from the package somewhere else instead.
10314 This can be used locally to override a package's version of a
10315 file, or by one package to override another's version (or
10316 provide a wrapper for it).
10320 Before deciding to use a diversion, read <ref
10321 id="pkg-alternatives"> to see if you really want a diversion
10322 rather than several alternative versions of a program.
10326 There is a diversion list, which is read by <prgn>dpkg</prgn>,
10327 and updated by a special program <prgn>dpkg-divert</prgn>.
10328 Please see <manref name="dpkg-divert" section="8"> for full
10329 details of its operation.
10333 When a package wishes to divert a file from another, it should
10334 call <prgn>dpkg-divert</prgn> in its preinst to add the
10335 diversion and rename the existing file. For example,
10336 supposing that a <prgn>smailwrapper</prgn> package wishes to
10337 install a wrapper around <tt>/usr/sbin/smail</tt>:
10339 if [ install = "$1" -o upgrade = "$1" ]; then
10340 dpkg-divert --package smailwrapper --add --rename \
10341 --divert /usr/sbin/smail.real /usr/sbin/smail
10343 </example> Testing <tt>$1</tt> is necessary so that the script
10344 doesn't try to add the diversion again when
10345 <prgn>smailwrapper</prgn> is upgraded. The <tt>--package
10346 smailwrapper</tt> ensures that <prgn>smailwrapper</prgn>'s
10347 copy of <tt>/usr/sbin/smail</tt> can bypass the diversion and
10348 get installed as the true version.
10352 The postrm has to do the reverse:
10354 if [ remove = "$1" ]; then
10355 dpkg-divert --package smailwrapper --remove --rename \
10356 --divert /usr/sbin/smail.real /usr/sbin/smail
10362 Do not attempt to divert a file which is vitally important for
10363 the system's operation - when using <prgn>dpkg-divert</prgn>
10364 there is a time, after it has been diverted but before
10365 <prgn>dpkg</prgn> has installed the new version, when the file
10366 does not exist.</p>