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8 Debian GNU/Linux Packaging Manual.
9 Copyright (C)1996 Ian Jackson; released under the terms of the GNU
10 General Public License, version 2 or (at your option) any later.
11 Revised: David A. Morris (bweaver@debian.org)
12 Maintainer since 1998, Christian Schwarz <schwarz@debian.org>
18 <titlepag><title>Debian Packaging Manual</title>
20 <name>Ian Jackson </name>
21 <email>ijackson@gnu.ai.mit.edu</email>
24 <name>Revised: David A. Morris</name>
25 <email>bweaver@debian.org</email>
28 <name>Maintainer: Christian Schwarz </name>
29 <email>schwarz@debian.org</email>
32 <name>Maintainer: Manoj Srivastava </name>
33 <email>srivasta@debian.org</email>
36 <name>Maintainer: Julian Gilbey </name>
37 <email>J.D.Gilbey@qmw.ac.uk</email>
40 <name>Maintainer: The Debian Policy group </name>
41 <email>debian-policy@lists.debian.org</email>
43 <version>version &version;, &date;</version>
46 This manual describes the technical aspects of creating Debian
47 binary and source packages. It does not deal with the Debian
48 Project policy requirements, and it assumes familiarity with
49 <prgn>dpkg</prgn>'s functions from the system administrator's
50 perspective. This package itself is maintained by a group of
51 maintainers that have no editorial powers. At the moment, the
52 list of maintainers is:
55 <p>Michael Alan Dorman <email>mdorman@debian.org</email></p>
58 <p>Richard Braakman <email>dark@xs4all.nl</email></p>
61 <p>Philip Hands <email>phil@hands.com</email></p>
64 <p>Julian Gilbey <email>J.D.Gilbey@qmw.ac.uk</email></p>
67 <p>Manoj Srivastava <email>srivasta@debian.org</email></p>
74 <copyrightsummary>Copyright ©1996 Ian Jackson.</copyrightsummary>
76 This manual is free software; you may redistribute it and/or
77 modify it under the terms of the GNU General Public License
78 as published by the Free Software Foundation; either version
79 2, or (at your option) any later version.
83 This is distributed in the hope that it will be useful, but
84 <em>without any warranty</em>; without even the implied
85 warranty of merchantability or fitness for a particular
86 purpose. See the GNU General Public License for more
91 A copy of the GNU General Public License is available as
92 <tt>/usr/doc/copyright/GPL</tt> in the Debian GNU/Linux
93 distribution or on the World Wide Web at
94 <tt>http://www.gnu.org/copyleft/gpl.html</tt>. You can also
95 obtain it by writing to the Free Software Foundation, Inc.,
96 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA.
102 <!-- Describes the technical interface between a package and dpkg.
104 How to safely put shared libraries in a package. Details of
105 dpkg's handling of individual files. Sections on when to use
106 which feature (eg Replaces vs. Replaces/Conflicts
107 vs. update-alternatives vs. diversions) Cross-references to the
108 policy document (see below) where appropriate. Description of the
109 interface between dselect and its access methods. Hints on where
110 to start with a new package (ie, the hello package). What to do
115 Manpages are required for: update-rc.d, diversions,
116 update-alternatives, install-info in a package.
121 <heading>Introduction and scope of this manual</heading>
124 <prgn>dpkg</prgn> is a suite of programs for creating binary
125 package files and installing and removing them on Unix
128 <prgn>dpkg</prgn> is targetted primarily at Debian
129 GNU/Linux, but may work on or be ported to other
136 The binary packages are designed for the management of
137 installed executable programs (usually compiled binaries) and
138 their associated data, though source code examples and
139 documentation are provided as part of some packages.</p>
142 This manual describes the technical aspects of creating Debian
143 binary packages (<tt>.deb</tt> files). It documents the
144 behaviour of the package management programs
145 <prgn>dpkg</prgn>, <prgn>dselect</prgn> et al. and the way
146 they interact with packages.</p>
149 It also documents the interaction between
150 <prgn>dselect</prgn>'s core and the access method scripts it
151 uses to actually install the selected packages, and describes
152 how to create a new access method.</p>
155 This manual does not go into detail about the options and
156 usage of the package building and installation tools. It
157 should therefore be read in conjuction with those programs'
162 The utility programs which are provided with <prgn>dpkg</prgn>
163 for managing various system configuration and similar issues,
164 such as <prgn>update-rc.d</prgn> and
165 <prgn>install-info</prgn>, are not described in detail here -
166 please see their manpages.
170 It does <em>not</em> describe the policy requirements imposed
171 on Debian packages, such as the permissions on files and
172 directories, documentation requirements, upload procedure, and
173 so on. You should see the Debian packaging policy manual for
174 these details. (Many of them will probably turn out to be
175 helpful even if you don't plan to upload your package and make
176 it available as part of the distribution.)
180 It is assumed that the reader is reasonably familiar with the
181 <prgn>dpkg</prgn> System Administrators' manual.
182 Unfortunately this manual does not yet exist.
186 The Debian version of the FSF's GNU hello program is provided
187 as an example for people wishing to create Debian
188 packages. The Debian <prgn>debmake</prgn> package is
189 recommended as a very helpful tool in creating and maintaining
190 Debian packages. However, while the tools and examples are
191 helpful, they do not replace the need to read and follow the
192 Policy and Programmer's Manual.</p>
195 <chapt id="binarypkg"><heading>Binary packages
199 The binary package has two main sections. The first part
200 consists of various control information files and scripts used
201 by <prgn>dpkg</prgn> when installing and removing. See <ref
206 The second part is an archive containing the files and
207 directories to be installed.
211 In the future binary packages may also contain other
212 components, such as checksums and digital signatures. The
213 format for the archive is described in full in the
214 <tt>deb(5)</tt> manpage.
218 <sect id="bincreating"><heading>Creating package files -
219 <prgn>dpkg-deb</prgn>
223 All manipulation of binary package files is done by
224 <prgn>dpkg-deb</prgn>; it's the only program that has
225 knowledge of the format. (<prgn>dpkg-deb</prgn> may be
226 invoked by calling <prgn>dpkg</prgn>, as <prgn>dpkg</prgn>
227 will spot that the options requested are appropriate to
228 <prgn>dpkg-deb</prgn> and invoke that instead with the same
233 In order to create a binary package you must make a
234 directory tree which contains all the files and directories
235 you want to have in the filesystem data part of the package.
236 In Debian-format source packages this directory is usually
237 <tt>debian/tmp</tt>, relative to the top of the package's
242 They should have the locations (relative to the root of the
243 directory tree you're constructing) ownerships and
244 permissions which you want them to have on the system when
249 With current versions of <prgn>dpkg</prgn> the uid/username
250 and gid/groupname mappings for the users and groups being
251 used should be the same on the system where the package is
252 built and the one where it is installed.
256 You need to add one special directory to the root of the
257 miniature filesystem tree you're creating:
258 <prgn>DEBIAN</prgn>. It should contain the control
259 information files, notably the binary package control file
260 (see <ref id="controlfile">).
264 The <prgn>DEBIAN</prgn> directory will not appear in the
265 filesystem archive of the package, and so won't be installed
266 by <prgn>dpkg</prgn> when the package is installed.
270 When you've prepared the package, you should invoke:
272 dpkg --build <var>directory</var>
277 This will build the package in
278 <tt><var>directory</var>.deb</tt>. (<prgn>dpkg</prgn> knows
279 that <tt>--build</tt> is a <prgn>dpkg-deb</prgn> option, so
280 it invokes <prgn>dpkg-deb</prgn> with the same arguments to
285 See the manpage <manref name="dpkg-deb" section="8"> for details of how
286 to examine the contents of this newly-created file. You may find the
287 output of following commands enlightening:
289 dpkg-deb --info <var>filename</var>.deb
290 dpkg-deb --contents <var>filename</var>.deb
291 dpkg --contents <var>filename</var>.deb
293 To view the copyright file for a package you could use this command:
295 dpkg --fsys-tarfile <var>filename</var>.deb | tar xof usr/doc/<var>\*</var>copyright | less
300 <sect id="controlarea">
302 Package control information files
306 The control information portion of a binary package is a
307 collection of files with names known to <prgn>dpkg</prgn>.
308 It will treat the contents of these files specially - some
309 of them contain information used by <prgn>dpkg</prgn> when
310 installing or removing the package; others are scripts which
311 the package maintainer wants <prgn>dpkg</prgn> to run.
315 It is possible to put other files in the package control
316 area, but this is not generally a good idea (though they
317 will largely be ignored).
321 Here is a brief list of the control info files supported by
322 <prgn>dpkg</prgn> and a summary of what they're used for.
327 <tag><tt>control</tt>
331 This is the key description file used by
332 <prgn>dpkg</prgn>. It specifies the package's name
333 and version, gives its description for the user,
334 states its relationships with other packages, and so
335 forth. See <ref id="controlfile">.
339 It is usually generated automatically from information
340 in the source package by the
341 <prgn>dpkg-gencontrol</prgn> program, and with
342 assistance from <prgn>dpkg-shlibdeps</prgn>. See <ref
343 id="sourcetools">.</p>
346 <tag><tt>postinst</tt>, <tt>preinst</tt>, <tt>postrm</tt>,
352 These are exectuable files (usually scripts) which
353 <prgn>dpkg</prgn> runs during installation, upgrade
354 and removal of packages. They allow the package to
355 deal with matters which are particular to that package
356 or require more complicated processing than that
357 provided by <prgn>dpkg</prgn>. Details of when and
358 how they are called are in <ref
359 id="maintainerscripts">.
363 It is very important to make these scripts
367 That means that if it runs successfully or fails
368 and then you call it again it doesn't bomb out,
369 but just ensures that everything is the way it
372 </footnote> This is so that if an error occurs, the
373 user interrupts <prgn>dpkg</prgn> or some other
374 unforeseen circumstance happens you don't leave the
375 user with a badly-broken package.
379 The maintainer scripts are guaranteed to run with a
380 controlling terminal and can interact with the user.
381 If they need to prompt for passwords, do full-screen
382 interaction or something similar you should do these
383 things to and from <tt>/dev/tty</tt>, since
384 <prgn>dpkg</prgn> will at some point redirect scripts'
385 standard input and output so that it can log the
386 installation process. Likewise, because these scripts
387 may be executed with standard output redirected into a
388 pipe for logging purposes, Perl scripts should set
389 unbuffered output by setting <tt>$|=1</tt> so that the
390 output is printed immediately rather than being
395 Each script should return a zero exit status for
396 success, or a nonzero one for failure.</p>
399 <tag><tt>conffiles</tt>
404 This file contains a list of configuration files which
405 are to be handled automatically by <prgn>dpkg</prgn>
406 (see <ref id="conffiles">). Note that not necessarily
407 every configuration file should be listed here.</p>
415 This file contains a list of the shared libraries
416 supplied by the package, with dependency details for
417 each. This is used by <prgn>dpkg-shlibdeps</prgn>
418 when it determines what dependencies are required in a
419 package control file. The <tt>shlibs</tt> file format
420 is described on <ref id="shlibs">.
426 <sect id="controlfile">
428 The main control information file: <tt>control</tt>
431 The most important control information file used by
432 <prgn>dpkg</prgn> when it installs a package is
433 <tt>control</tt>. It contains all the package's `vital
438 The binary package control files of packages built from
439 Debian sources are made by a special tool,
440 <prgn>dpkg-gencontrol</prgn>, which reads
441 <tt>debian/control</tt> and <tt>debian/changelog</tt> to
442 find the information it needs. See <ref id="sourcepkg"> for
447 The fields in binary package control files are:
448 <list compact="compact">
450 <p><qref id="f-Package"><tt>Package</tt></qref> (mandatory)</p>
453 <p><qref id="versions"><tt>Version</tt></qref> (mandatory)</p>
455 <item><p><qref id="f-Architecture"><tt>Architecture</tt></qref>
459 This field should appear in all packages, though
460 <prgn>dpkg</prgn> doesn't require it yet so that
461 old packages can still be installed.
467 <p><qref id="relationships"><tt>Depends</tt>,
468 <tt>Provides</tt> et al.</qref></p>
471 <p><qref id="f-Essential"><tt>Essential</tt></qref></p>
474 <p><qref id="f-Maintainer"><tt>Maintainer</tt></qref></p>
477 <p><qref id="f-classification"><tt>Section</tt>,
478 <tt>Priority</tt></qref></p>
481 <p><qref id="f-Source"><tt>Source</tt></qref></p>
484 <p><qref id="descriptions"><tt>Description</tt></qref></p>
488 <qref id="f-Installed-Size"><tt>Installed-Size</tt></qref>
494 A description of the syntax of control files and the purpose
495 of these fields is available in <ref id="controlfields">.
499 <heading>Time Stamps</heading>
501 Maintainers are encouraged to preserve the modification
502 times of the upstream source files in a package, as far as
503 is reasonably possible.
506 The rationale is that there is some information conveyed
507 by knowing the age of the file, for example, you could
508 recognize that some documentation is very old by looking
509 at the modification time, so it would be nice if the
510 modification time of the upstream source would be
518 <chapt id="sourcepkg">
519 <heading>Source packages</heading>
522 The Debian binary packages in the distribution are generated
523 from Debian sources, which are in a special format to assist
524 the easy and automatic building of binaries.
528 There was a previous version of the Debian source format,
529 which is now being phased out. Instructions for converting an
530 old-style package are given in the Debian policy manual.
533 <sect id="sourcetools">
534 <heading>Tools for processing source packages</heading>
537 Various tools are provided for manipulating source packages;
538 they pack and unpack sources and help build of binary
539 packages and help manage the distribution of new versions.
543 They are introduced and typical uses described here; see
544 <manref name="dpkg-source" section="1"> for full
545 documentation about their arguments and operation.
549 For examples of how to construct a Debian source package,
550 and how to use those utilities that are used by Debian
551 source packages, please see the <prgn>hello</prgn> example
557 <prgn>dpkg-source</prgn> - packs and unpacks Debian source
562 This program is frequently used by hand, and is also
563 called from package-independent automated building scripts
564 such as <prgn>dpkg-buildpackage</prgn>.
568 To unpack a package it is typically invoked with
570 dpkg-source -x <var>.../path/to/filename</var>.dsc
575 with the <tt><var>filename</var>.tar.gz</tt> and
576 <tt><var>filename</var>.diff.gz</tt> (if applicable) in
577 the same directory. It unpacks into
578 <tt><var>package</var>-<var>version</var></tt>, and if
580 <tt><var>package</var>-<var>version</var>.orig</tt>, in
581 the current directory.
585 To create a packed source archive it is typically invoked:
587 dpkg-source -b <var>package</var>-<var>version</var>
592 This will create the <tt>.dsc</tt>, <tt>.tar.gz</tt> and
593 <tt>.diff.gz</tt> (if appropriate) in the current
594 directory. <prgn>dpkg-source</prgn> does not clean the
595 source tree first - this must be done separately if it is
600 See also <ref id="sourcearchives">.</p>
606 <prgn>dpkg-buildpackage</prgn> - overall package-building
611 <prgn>dpkg-buildpackage</prgn> is a script which invokes
612 <prgn>dpkg-source</prgn>, the <tt>debian/rules</tt>
613 targets <prgn>clean</prgn>, <prgn>build</prgn> and
614 <prgn>binary</prgn>, <prgn>dpkg-genchanges</prgn> and
615 <prgn>pgp</prgn> to build a signed source and binary
620 It is usually invoked by hand from the top level of the
621 built or unbuilt source directory. It may be invoked with
622 no arguments; useful arguments include:
623 <taglist compact="compact">
624 <tag><tt>-uc</tt>, <tt>-us</tt></tag>
627 Do not PGP-sign the <tt>.changes</tt> file or the
628 source package <tt>.dsc</tt> file, respectively.</p>
630 <tag><tt>-p<var>pgp-command</var></tt></tag>
633 Invoke <var>pgp-command</var> instead of finding
634 <tt>pgp</tt> on the <prgn>PATH</prgn>.
635 <var>pgp-command</var> must behave just like
636 <prgn>pgp</prgn>.</p>
638 <tag><tt>-r<var>root-command</var></tt></tag>
641 When root privilege is required, invoke the command
642 <var>root-command</var>. <var>root-command</var>
643 should invoke its first argument as a command, from
644 the <prgn>PATH</prgn> if necessary, and pass its
645 second and subsequent arguments to the command it
646 calls. If no <var>root-command</var> is supplied
647 then <var>dpkg-buildpackage</var> will take no
648 special action to gain root privilege, so that for
649 most packages it will have to be invoked as root to
652 <tag><tt>-b</tt>, <tt>-B</tt></tag>
655 Two types of binary-only build and upload - see
656 <manref name="dpkg-source" section="1">.
665 <prgn>dpkg-gencontrol</prgn> - generates binary package
670 This program is usually called from <tt>debian/rules</tt>
671 (see <ref id="sourcetree">) in the top level of the source
676 This is usually done just before the files and directories in the
677 temporary directory tree where the package is being built have their
678 permissions and ownerships set and the package is constructed using
679 <prgn>dpkg-deb/</prgn>
682 This is so that the control file which is produced has
683 the right permissions
689 <prgn>dpkg-gencontrol</prgn> must be called after all the
690 files which are to go into the package have been placed in
691 the temporary build directory, so that its calculation of
692 the installed size of a package is correct.
696 It is also necessary for <prgn>dpkg-gencontrol</prgn> to
697 be run after <prgn>dpkg-shlibdeps</prgn> so that the
698 variable substitutions created by
699 <prgn>dpkg-shlibdeps</prgn> in <tt>debian/substvars</tt>
704 For a package which generates only one binary package, and
705 which builds it in <tt>debian/tmp</tt> relative to the top
706 of the source package, it is usually sufficient to call
707 <prgn>dpkg-gencontrol</prgn>.
711 Sources which build several binaries will typically need
714 dpkg-gencontrol -Pdebian/tmp-<var>pkg</var> -p<var>package</var>
715 </example> The <tt>-P</tt> tells
716 <prgn>dpkg-gencontrol</prgn> that the package is being
717 built in a non-default directory, and the <tt>-p</tt>
718 tells it which package's control file should be generated.
722 <prgn>dpkg-gencontrol</prgn> also adds information to the
723 list of files in <tt>debian/files</tt>, for the benefit of
724 (for example) a future invocation of
725 <prgn>dpkg-genchanges</prgn>.</p>
730 <prgn>dpkg-shlibdeps</prgn> - calculates shared library
735 This program is usually called from <tt>debian/rules</tt>
736 just before <prgn>dpkg-gencontrol</prgn> (see <ref
737 id="sourcetree">), in the top level of the source tree.
741 Its arguments are executables and libraries
744 They may be specified either in the locations in the
745 source tree where they are created or in the locations
746 in the temporary build tree where they are installed
747 prior to binary package creation.
749 </footnote> for which shared library dependencies should
750 be included in the binary package's control file.
754 If some of the found shared libraries should only
755 warrant a <tt>Recommends</tt> or <tt>Suggests</tt>, or if
756 some warrant a <tt>Pre-Depends</tt>, this can be achieved
757 by using the <tt>-d<var>dependency-field</var></tt> option
758 before those executable(s). (Each <tt>-d</tt> option
759 takes effect until the next <tt>-d</tt>.)
763 <prgn>dpkg-shlibdeps</prgn> does not directly cause the
764 output control file to be modified. Instead by default it
765 adds to the <tt>debian/substvars</tt> file variable
766 settings like <tt>shlibs:Depends</tt>. These variable
767 settings must be referenced in dependency fields in the
768 appropriate per-binary-package sections of the source
773 For example, the <prgn>procps</prgn> package generates two
774 kinds of binaries, simple C binaries like <prgn>ps</prgn>
775 which require a predependency and full-screen ncurses
776 binaries like <prgn>top</prgn> which require only a
777 recommendation. It can say in its <tt>debian/rules</tt>:
779 dpkg-shlibdeps -dPre-Depends ps -dRecommends top
781 and then in its main control file <tt>debian/control</tt>:
785 Pre-Depends: ${shlibs:Pre-Depends}
786 Recommends: ${shlibs:Recommends}
792 Sources which produce several binary packages with
793 different shared library dependency requirements can use
794 the <tt>-p<var>varnameprefix</var></tt> option to override
795 the default <tt>shlib:</tt> prefix (one invocation of
796 <prgn>dpkg-shlibdeps</prgn> per setting of this option).
797 They can thus produce several sets of dependency
798 variables, each of the form
799 <tt><var>varnameprefix</var>:<var>dependencyfield</var></tt>,
800 which can be referred to in the appropriate parts of the
801 binary package control files.
808 <prgn>dpkg-distaddfile</prgn> - adds a file to
809 <tt>debian/files</tt>
813 Some packages' uploads need to include files other than
814 the source and binary package files.
818 <prgn>dpkg-distaddfile</prgn> adds a file to the
819 <tt>debian/files</tt> file so that it will be included in
820 the <tt>.changes</tt> file when
821 <prgn>dpkg-genchanges</prgn> is run.
825 It is usually invoked from the <prgn>binary</prgn> target of
826 <tt>debian/rules</tt>:
828 dpkg-distaddfile <var>filename</var> <var>section</var> <var>priority</var>
830 The <var>filename</var> is relative to the directory where
831 <prgn>dpkg-genchanges</prgn> will expect to find it - this
832 is usually the directory above the top level of the source
833 tree. The <tt>debian/rules</tt> target should put the
834 file there just before or just after calling
835 <prgn>dpkg-distaddfile</prgn>.
839 The <var>section</var> and <var>priority</var> are passed
840 unchanged into the resulting <tt>.changes</tt> file. See
841 <ref id="f-classification">.
846 <sect1><heading><prgn>dpkg-genchanges</prgn> - generates a <tt>.changes</tt> upload
851 This program is usually called by package-independent
852 automatic building scripts such as
853 <prgn>dpkg-buildpackage</prgn>, but it may also be called
858 It is usually called in the top level of a built source
859 tree, and when invoked with no arguments will print out a
860 straightforward <tt>.changes</tt> file based on the
861 information in the source package's changelog and control
862 file and the binary and source packages which should have
868 <sect1><heading><prgn>dpkg-parsechangelog</prgn> - produces parsed representation of
873 This program is used internally by
874 <prgn>dpkg-source</prgn> et al. It may also occasionally
875 be useful in <tt>debian/rules</tt> and elsewhere. It
876 parses a changelog, <tt>debian/changelog</tt> by default,
877 and prints a control-file format representation of the
878 information in it to standard output.
882 <sect1 id="dpkgarch"><heading><prgn>dpkg-architecture</prgn> -
883 information about the build and host system
887 This program can be used manually, but is also invoked by
888 <tt>dpkg-buildpackage</tt> or <tt>debian/rules</tt> to set
889 to set environment or make variables which specify the build and
890 host architecture for the package building process.
895 <sect id="sourcetree"><heading>The Debianised source tree
899 The source archive scheme described later is intended to
900 allow a Debianised source tree with some associated control
901 information to be reproduced and transported easily. The
902 Debianised source tree is a version of the original program
903 with certain files added for the benefit of the
904 Debianisation process, and with any other changes required
905 made to the rest of the source code and installation
910 The extra files created for Debian are in the subdirectory
911 <tt>debian</tt> of the top level of the Debianised source
912 tree. They are described below.
915 <sect1 id="debianrules"><heading><tt>debian/rules</tt> - the main building
920 This file is an executable makefile, and contains the
921 package-specific recipies for compiling the package and
922 building binary package(s) out of the source.
926 It must start with the line <tt>#!/usr/bin/make -f</tt>,
927 so that it can be invoked by saying its name rather than
928 invoking <prgn>make</prgn> explicitly.
932 Since an interactive <tt>debian/rules</tt> script makes it
933 impossible to autocompile that package and also makes it
934 hard for other people to reproduce the same binary
935 package, all <strong>required targets</strong> have to be
936 non-interactive. At a minimul, required targets are the
937 ones called by <prgn>dpkg-buildpackage</prgn>, namely,
938 <em>clean</em>, <em>binary</em>, <em>binary-arch</em>, and
939 <em>build</em>. It also follows that any target that these
940 targets depend on must also be non-interactive.
944 The targets which are required to be present are:
946 <tag><tt>build</tt></tag>
949 This should perform all non-interactive
950 configuration and compilation of the package. If a
951 package has an interactive pre-build configuration
952 routine, the Debianised source package should be
953 built after this has taken place, so that it can be
954 built without rerunning the configuration.
958 For some packages, notably ones where the same
959 source tree is compiled in different ways to produce
960 two binary packages, the <prgn>build</prgn> target
961 does not make much sense. For these packages it is
962 good enough to provide two (or more) targets
963 (<tt>build-a</tt> and <tt>build-b</tt> or whatever)
964 for each of the ways of building the package, and a
965 <prgn>build</prgn> target that does nothing. The
966 <prgn>binary</prgn> target will have to build the
967 package in each of the possible ways and make the
968 binary package out of each.
972 The <prgn>build</prgn> target must not do anything
973 that might require root privilege.
977 The <prgn>build</prgn> target may need to run
978 <prgn>clean</prgn> first - see below.
982 When a package has a configuration routine that
983 takes a long time, or when the makefiles are poorly
984 designed, or when <prgn>build</prgn> needs to run
985 <prgn>clean</prgn> first, it is a good idea to
986 <tt>touch build</tt> when the build process is
987 complete. This will ensure that if <tt>debian/rules
988 build</tt> is run again it will not rebuild the
993 <tag><tt>binary</tt>, <tt>binary-arch</tt>,
994 <tt>binary-indep</tt>
998 The <prgn>binary</prgn> target should be all that is
999 necessary for the user to build the binary
1000 package. All these targets are required to be
1001 non-interactive. It is split into two parts:
1002 <prgn>binary-arch</prgn> builds the packages' output
1003 files which are specific to a particular
1004 architecture, and <prgn>binary-indep</prgn> builds
1005 those which are not.
1009 <prgn>binary</prgn> should usually be a target with
1010 no commands which simply depends on
1011 <prgn>binary-arch</prgn> and
1012 <prgn>binary-indep</prgn>.
1016 Both <prgn>binary-*</prgn> targets should depend on
1017 the <prgn>build</prgn> target, above, so that the
1018 package is built if it has not been already. It
1019 should then create the relevant binary package(s),
1020 using <prgn>dpkg-gencontrol</prgn> to make their
1021 control files and <prgn>dpkg-deb</prgn> to build
1022 them and place them in the parent of the top level
1027 If one of the <prgn>binary-*</prgn> targets has
1028 nothing to do (this will be always be the case if
1029 the source generates only a single binary package,
1030 whether architecture-dependent or not) it
1031 <em>must</em> still exist, but should always
1036 <ref id="binarypkg"> describes how to construct
1041 The <prgn>binary</prgn> targets must be invoked as
1046 <tag><tt>clean</tt></tag>
1050 This should undo any effects that the
1051 <prgn>build</prgn> and <prgn>binary</prgn> targets
1052 may have had, except that it should leave alone any
1053 output files created in the parent directory by a
1054 run of <prgn>binary</prgn>. This target is required
1055 to be non-interactive.
1059 If a <prgn>build</prgn> file is touched at the end
1060 of the <prgn>build</prgn> target, as suggested
1061 above, it must be removed as the first thing that
1062 <prgn>clean</prgn> does, so that running
1063 <prgn>build</prgn> again after an interrupted
1064 <prgn>clean</prgn> doesn't think that everything is
1069 The <prgn>clean</prgn> target must be invoked as
1070 root if <prgn>binary</prgn> has been invoked since
1071 the last <prgn>clean</prgn>, or if
1072 <prgn>build</prgn> has been invoked as root (since
1073 <prgn>build</prgn> may create directories, for
1078 <tag><tt>get-orig-source</tt> (optional)</tag>
1082 This target fetches the most recent version of the
1083 original source package from a canonical archive
1084 site (via FTP or WWW, for example), does any
1085 necessary rearrangement to turn it into the original
1086 source tarfile format described below, and leaves it
1087 in the current directory.
1091 This target may be invoked in any directory, and
1092 should take care to clean up any temporary files it
1097 This target is optional, but providing it if
1098 possible is a good idea.
1104 The <prgn>build</prgn>, <prgn>binary</prgn> and
1105 <prgn>clean</prgn> targets must be invoked with a current
1106 directory of the package's top-level directory.
1111 Additional targets may exist in <tt>debian/rules</tt>,
1112 either as published or undocumented interfaces or for the
1113 package's internal use.
1117 The architecture we build on and build for is determined by make
1118 variables via dpkg-architecture (see <ref id="dpkgarch">). You can
1119 get the Debian architecture and the GNU style architecture
1120 specification string for the build machine as well as the host
1121 machine. Here is a list of supported make variables:
1122 <list compact="compact">
1124 <p><tt>DEB_*_ARCH</tt> (the Debian architecture)</p>
1127 <p><tt>DEB_*_GNU_TYPE</tt> (the GNU style architecture
1128 specification string)</p>
1131 <p><tt>DEB_*_GNU_CPU</tt> (the CPU part of DEB_*_GNU_TYPE)</p>
1134 <p><tt>DEB_*_GNU_SYSTEM</tt> (the System part of
1140 where <tt>*</tt> is either <tt>BUILD</tt> for specification of
1141 the build machine or <tt>HOST</tt> for specification of the machine
1146 Backward compatibility can be provided in the rules file
1147 by setting the needed variables to suitable default
1148 values, please refer to the documentation of
1149 dpkg-architecture for details.
1153 It is important to understand that the <tt>DEB_*_ARCH</tt>
1154 string does only determine which Debian architecture we
1155 build on resp. for. It should not be used to get the CPU
1156 or System information, the GNU style variables should be
1162 <sect1><heading><tt>debian/control</tt>
1166 This file contains version-independent details about the
1167 source package and about the binary packages it creates.
1171 It is a series of sets of control fields, each
1172 syntactically similar to a binary package control file.
1173 The sets are separated by one or more blank lines. The
1174 first set is information about the source package in
1175 general; each subsequent set describes one binary package
1176 that the source tree builds.
1180 The syntax and semantics of the fields are described below
1181 in <ref id="controlfields">.
1185 The general (binary-package-independent) fields are:
1186 <list compact="compact">
1188 <p><qref id="f-Source"><tt>Source</tt></qref> (mandatory)</p>
1191 <p><qref id="f-Maintainer"><tt>Maintainer</tt></qref></p>
1195 <qref id="f-classification"><tt>Section</tt> and
1196 <tt>Priority</tt></qref>
1197 (classification, mandatory)
1202 <qref id="relationships"><tt>Build-Depends</tt> et
1203 al.</qref> (source package interrelationships)
1208 <qref id="f-Standards-Version"><tt>Standards-Version</tt></qref>
1214 The per-binary-package fields are:
1215 <list compact="compact">
1217 <p><qref id="f-Package"><tt>Package</tt></qref> (mandatory)</p>
1221 <qref id="f-Architecture"><tt>Architecture</tt></qref>
1225 <p><qref id="descriptions"><tt>Description</tt></qref></p>
1229 <qref id="f-classification"><tt>Section</tt> and
1230 <tt>Priority</tt></qref> (classification)</p>
1233 <p><qref id="f-Essential"><tt>Essential</tt></qref></p>
1237 <qref id="relationships"><tt>Depends</tt> et
1238 al.</qref> (binary package interrelationships)
1244 These fields are used by <prgn>dpkg-gencontrol</prgn> to
1245 generate control files for binary packages (see below), by
1246 <prgn>dpkg-genchanges</prgn> to generate the
1247 <tt>.changes</tt> file to accompany the upload, and by
1248 <prgn>dpkg-source</prgn> when it creates the <tt>.dsc</tt>
1249 source control file as part of a source archive.
1253 The fields here may contain variable references - their
1254 values will be substituted by
1255 <prgn>dpkg-gencontrol</prgn>, <prgn>dpkg-genchanges</prgn>
1256 or <prgn>dpkg-source</prgn> when they generate output
1257 control files. See <ref id="srcsubstvars"> for details.
1260 <p> <sect2><heading>User-defined fields
1264 Additional user-defined fields may be added to the
1265 source package control file. Such fields will be
1266 ignored, and not copied to (for example) binary or
1267 source package control files or upload control files.
1271 If you wish to add additional unsupported fields to
1272 these output files you should use the mechanism
1277 Fields in the main source control information file with
1278 names starting <tt>X</tt>, followed by one or more of
1279 the letters <tt>BCS</tt> and a hyphen <tt>-</tt>, will
1280 be copied to the output files. Only the part of the
1281 field name after the hyphen will be used in the output
1282 file. Where the letter <tt>B</tt> is used the field
1283 will appear in binary package control files, where the
1284 letter <tt>S</tt> is used in source package control
1285 files and where <tt>C</tt> is used in upload control
1286 (<tt>.changes</tt>) files.
1290 For example, if the main source information control file
1293 XBS-Comment: I stand between the candle and the star.
1295 then the binary and source package control files will contain the
1298 Comment: I stand between the candle and the star.
1305 <sect1 id="dpkgchangelog"><heading><tt>debian/changelog</tt>
1309 This file records the changes to the Debian-specific parts of the
1313 Though there is nothing stopping an author who is also
1314 the Debian maintainer from using it for all their
1315 changes, it will have to be renamed if the Debian and
1316 upstream maintainers become different
1323 It has a special format which allows the package building
1324 tools to discover which version of the package is being
1325 built and find out other release-specific information.
1329 That format is a series of entries like this:
1331 <var>package</var> (<var>version</var>) <var>distribution(s)</var>; urgency=<var>urgency</var>
1333 * <var>change details</var>
1334 <var>more change details</var>
1335 * <var>even more change details</var>
1337 -- <var>maintainer name and email address</var> <var>date</var>
1342 <var>package</var> and <var>version</var> are the source
1343 package name and version number.
1347 <var>distribution(s)</var> lists the distributions where
1348 this version should be installed when it is uploaded - it
1349 is copied to the <tt>Distribution</tt> field in the
1350 <tt>.changes</tt> file. See <ref id="f-Distribution">.
1354 <var>urgency</var> is the value for the <tt>Urgency</tt>
1355 field in the <tt>.changes</tt> file for the upload. See
1356 <ref id="f-Urgency">. It is not possible to specify an
1357 urgency containing commas; commas are used to separate
1358 <tt><var>keyword</var>=<var>value</var></tt> settings in
1359 the <prgn>dpkg</prgn> changelog format (though there is
1360 currently only one useful <var>keyword</var>,
1365 The change details may in fact be any series of lines
1366 starting with at least two spaces, but conventionally each
1367 change starts with an asterisk and a separating space and
1368 continuation lines are indented so as to bring them in
1369 line with the start of the text above. Blank lines may be
1370 used here to separate groups of changes, if desired.
1374 The maintainer name and email address should <em>not</em>
1375 necessarily be those of the usual package maintainer.
1376 They should be the details of the person doing
1377 <em>this</em> version. The information here will be
1378 copied to the <tt>.changes</tt> file, and then later used
1379 to send an acknowledgement when the upload has been
1384 The <var>date</var> should be in RFC822 format
1387 This is generated by the <prgn>822-date</prgn>
1390 </footnote>; it should include the timezone specified
1391 numerically, with the timezone name or abbreviation
1392 optionally present as a comment.
1396 The first `title' line with the package name should start
1397 at the left hand margin; the `trailer' line with the
1398 maintainer and date details should be preceded by exactly
1399 one space. The maintainer details and the date must be
1400 separated by exactly two spaces.
1404 An Emacs mode for editing this format is available: it is
1405 called <tt>debian-changelog-mode</tt>. You can have this
1406 mode selected automatically when you edit a Debian
1407 changelog by adding a local variables clause to the end of
1411 <sect2><heading>Defining alternative changelog formats
1415 It is possible to use a different format to the standard
1416 one, by providing a parser for the format you wish to
1421 In order to have <tt>dpkg-parsechangelog</tt> run your
1422 parser, you must include a line within the last 40 lines
1423 of your file matching the Perl regular expression:
1424 <tt>\schangelog-format:\s+([0-9a-z]+)\W</tt> The part in
1425 parentheses should be the name of the format. For
1426 example, you might say:
1428 @@@ changelog-format: joebloggs @@@
1430 Changelog format names are non-empty strings of alphanumerics.
1434 If such a line exists then <tt>dpkg-parsechangelog</tt>
1435 will look for the parser as
1436 <tt>/usr/lib/dpkg/parsechangelog/<var>format-name</var></tt>
1438 <tt>/usr/local/lib/dpkg/parsechangelog/<var>format-name</var></tt>;
1439 it is an error for it not to find it, or for it not to
1440 be an executable program. The default changelog format
1441 is <tt>dpkg</tt>, and a parser for it is provided with
1442 the <tt>dpkg</tt> package.
1446 The parser will be invoked with the changelog open on
1447 standard input at the start of the file. It should read
1448 the file (it may seek if it wishes) to determine the
1449 information required and return the parsed information
1450 to standard output in the form of a series of control
1451 fields in the standard format. By default it should
1452 return information about only the most recent version in
1453 the changelog; it should accept a
1454 <tt>-v<var>version</var></tt> option to return changes
1455 information from all versions present <em>strictly
1456 after</em> <var>version</var>, and it should then be an
1457 error for <var>version</var> not to be present in the
1463 <list compact="compact">
1465 <p><qref id="f-Source"><tt>Source</tt></qref></p>
1468 <p><qref id="versions"><tt>Version</tt></qref> (mandatory)</p>
1472 <qref id="f-Distribution"><tt>Distribution</tt></qref>
1477 <p><qref id="f-Urgency"><tt>Urgency</tt></qref> (mandatory)</p>
1481 <qref id="f-Maintainer"><tt>Maintainer</tt></qref>
1486 <p><qref id="f-Date"><tt>Date</tt></qref></p>
1490 <qref id="f-Changes"><tt>Changes</tt></qref>
1497 If several versions are being returned (due to the use
1498 of <tt>-v</tt>), the urgency value should be of the
1499 highest urgency code listed at the start of any of the
1500 versions requested followed by the concatenated
1501 (space-separated) comments from all the versions
1502 requested; the maintainer, version, distribution and
1503 date should always be from the most recent version.
1507 For the format of the <tt>Changes</tt> field see <ref
1512 If the changelog format which is being parsed always or
1513 almost always leaves a blank line between individual
1514 change notes these blank lines should be stripped out,
1515 so as to make the resulting output compact.
1519 If the changelog format does not contain date or package
1520 name information this information should be omitted from
1521 the output. The parser should not attempt to synthesise
1522 it or find it from other sources.
1526 If the changelog does not have the expected format the
1527 parser should exit with a nonzero exit status, rather
1528 than trying to muddle through and possibly generating
1533 A changelog parser may not interact with the user at
1537 <sect1 id="srcsubstvars"><heading><tt>debian/substvars</tt>
1538 and variable substitutions
1542 When <prgn>dpkg-gencontrol</prgn>,
1543 <prgn>dpkg-genchanges</prgn> and <prgn>dpkg-source</prgn>
1544 generate control files they do variable substitutions on
1545 their output just before writing it. Variable
1546 substitutions have the form
1547 <tt>${<var>variable-name</var>}</tt>. The optional file
1548 <tt>debian/substvars</tt> contains variable substitutions
1549 to be used; variables can also be set directly from
1550 <tt>debian/rules</tt> using the <tt>-V</tt> option to the
1551 source packaging commands, and certain predefined
1552 variables are available.
1556 The is usually generated and modified dynamically by
1557 <tt>debian/rules</tt> targets; in this case it must be
1558 removed by the <prgn>clean</prgn> target.
1562 See <manref name="dpkg-source" section="1"> for full
1563 details about source variable substitutions, including the
1564 format of <tt>debian/substvars</tt>.</p>
1567 <sect1><heading><tt>debian/files</tt>
1571 This file is not a permanent part of the source tree; it
1572 is used while building packages to record which files are
1573 being generated. <prgn>dpkg-genchanges</prgn> uses it
1574 when it generates a <tt>.changes</tt> file.
1578 It should not exist in a shipped source package, and so it
1579 (and any backup files or temporary files such as
1583 <tt>files.new</tt> is used as a temporary file by
1584 <prgn>dpkg-gencontrol</prgn> and
1585 <prgn>dpkg-distaddfile</prgn> - they write a new
1586 version of <tt>files</tt> here before renaming it,
1587 to avoid leaving a corrupted copy if an error
1590 </footnote>) should be removed by the
1591 <prgn>clean</prgn> target. It may also be wise to
1592 ensure a fresh start by emptying or removing it at the
1593 start of the <prgn>binary</prgn> target.
1597 <prgn>dpkg-gencontrol</prgn> adds an entry to this file
1598 for the <tt>.deb</tt> file that will be created by
1599 <prgn>dpkg-deb</prgn> from the control file that it
1600 generates, so for most packages all that needs to be done
1601 with this file is to delete it in <prgn>clean</prgn>.
1605 If a package upload includes files besides the source
1606 package and any binary packages whose control files were
1607 made with <prgn>dpkg-gencontrol</prgn> then they should be
1608 placed in the parent of the package's top-level directory
1609 and <prgn>dpkg-distaddfile</prgn> should be called to add
1610 the file to the list in <tt>debian/files</tt>.</p>
1613 <sect1><heading><tt>debian/tmp</tt>
1617 This is the canonical temporary location for the
1618 construction of binary packages by the <prgn>binary</prgn>
1619 target. The directory <tt>tmp</tt> serves as the root of
1620 the filesystem tree as it is being constructed (for
1621 example, by using the package's upstream makefiles install
1622 targets and redirecting the output there), and it also
1623 contains the <tt>DEBIAN</tt> subdirectory. See <ref
1628 If several binary packages are generated from the same
1629 source tree it is usual to use several
1630 <tt>debian/tmp<var>something</var></tt> directories, for
1631 example <tt>tmp-a</tt> or <tt>tmp-doc</tt>.
1635 Whatever <tt>tmp</tt> directories are created and used by
1636 <prgn>binary</prgn> must of course be removed by the
1637 <prgn>clean</prgn> target.</p></sect1>
1641 <sect id="sourcearchives"><heading>Source packages as archives
1645 As it exists on the FTP site, a Debian source package
1646 consists of three related files. You must have the right
1647 versions of all three to be able to use them.
1652 <tag>Debian source control file - <tt>.dsc</tt></tag>
1656 This file contains a series of fields, identified and
1657 separated just like the fields in the control file of
1658 a binary package. The fields are listed below; their
1659 syntax is described above, in <ref id="controlfields">.
1660 <list compact="compact">
1662 <p><qref id="f-Source"><tt>Source</tt></qref></p>
1665 <p><qref id="versions"><tt>Version</tt></qref></p>
1668 <p><qref id="f-Maintainer"><tt>Maintainer</tt></qref></p>
1671 <p><qref id="f-Binary"><tt>Binary</tt></qref></p>
1674 <p><qref id="f-Architecture"><tt>Architecture</tt></qref></p>
1678 <qref id="relationships"><tt>Build-Depends</tt> et
1679 al.</qref> (source package interrelationships)
1684 <qref id="f-Standards-Version"><tt>Standards-Version</tt></qref></p>
1687 <p><qref id="f-Files"><tt>Files</tt></qref></p>
1692 The source package control file is generated by
1693 <prgn>dpkg-source</prgn> when it builds the source
1694 archive, from other files in the source package,
1695 described above. When unpacking it is checked against
1696 the files and directories in the other parts of the
1697 source package, as described below.</p>
1701 Original source archive -
1703 <var>package</var>_<var>upstream-version</var>.orig.tar.gz
1710 This is a compressed (with <tt>gzip -9</tt>)
1711 <prgn>tar</prgn> file containing the source code from
1712 the upstream authors of the program. The tarfile
1713 unpacks into a directory
1714 <tt><var>package</var>-<var>upstream-version</var>.orig</tt>,
1715 and does not contain files anywhere other than in
1716 there or in its subdirectories.</p>
1720 Debianisation diff -
1722 <var>package</var>_<var>upstream_version-revision</var>.diff.gz
1728 This is a unified context diff (<tt>diff -u</tt>)
1729 giving the changes which are required to turn the
1730 original source into the Debian source. These changes
1731 may only include editing and creating plain files.
1732 The permissions of files, the targets of symbolic
1733 links and the characteristics of special files or
1734 pipes may not be changed and no files may be removed
1739 All the directories in the diff must exist, except the
1740 <tt>debian</tt> subdirectory of the top of the source
1741 tree, which will be created by
1742 <prgn>dpkg-source</prgn> if necessary when unpacking.
1746 The <prgn>dpkg-source</prgn> program will
1747 automatically make the <tt>debian/rules</tt> file
1748 executable (see below).</p></item>
1753 If there is no original source code - for example, if the
1754 package is specially prepared for Debian or the Debian
1755 maintainer is the same as the upstream maintainer - the
1756 format is slightly different: then there is no diff, and the
1758 <tt><var>package</var>_<var>version</var>.tar.gz</tt> and
1759 contains a directory
1760 <tt><var>package</var>-<var>version</var></tt>.
1764 <sect><heading>Unpacking a Debian source package without
1765 <prgn>dpkg-source</prgn>
1769 <tt>dpkg-source -x</tt> is the recommended way to unpack a
1770 Debian source package. However, if it is not available it
1771 is possible to unpack a Debian source archive as follows:
1772 <enumlist compact="compact">
1775 Untar the tarfile, which will create a <tt>.orig</tt>
1779 <p>Rename the <tt>.orig</tt> directory to
1780 <tt><var>package</var>-<var>version</var></tt>.</p>
1784 Create the subdirectory <tt>debian</tt> at the top of
1785 the source tree.</p>
1787 <item><p>Apply the diff using <tt>patch -p0</tt>.</p>
1789 <item><p>Untar the tarfile again if you want a copy of the original
1790 source code alongside the Debianised version.</p>
1795 It is not possible to generate a valid Debian source archive
1796 without using <prgn>dpkg-source</prgn>. In particular,
1797 attempting to use <prgn>diff</prgn> directly to generate the
1798 <tt>.diff.gz</tt> file will not work.
1801 <sect1><heading>Restrictions on objects in source packages
1805 The source package may not contain any hard links
1808 This is not currently detected when building source
1809 packages, but only when extracting
1815 Hard links may be permitted at some point in the
1816 future, but would require a fair amount of
1819 </footnote>, device special files, sockets or setuid or
1823 Setgid directories are allowed.
1829 The source packaging tools manage the changes between the
1830 original and Debianised source using <prgn>diff</prgn> and
1831 <prgn>patch</prgn>. Turning the original source tree as
1832 included in the <tt>.orig.tar.gz</tt> into the debianised
1833 source must not involve any changes which cannot be
1834 handled by these tools. Problematic changes which cause
1835 <prgn>dpkg-source</prgn> to halt with an error when
1836 building the source package are:
1837 <list compact="compact">
1838 <item><p>Adding or removing symbolic links, sockets or pipes.</p>
1840 <item><p>Changing the targets of symbolic links.</p>
1842 <item><p>Creating directories, other than <tt>debian</tt>.</p>
1844 <item><p>Changes to the contents of binary files.</p></item>
1845 </list> Changes which cause <prgn>dpkg-source</prgn> to
1846 print a warning but continue anyway are:
1847 <list compact="compact">
1850 Removing files, directories or symlinks.
1853 Renaming a file is not treated specially - it is
1854 seen as the removal of the old file (which
1855 generates a warning, but is otherwise ignored),
1856 and the creation of the new
1863 Changed text files which are missing the usual final
1864 newline (either in the original or the modified
1869 Changes which are not represented, but which are not detected by
1870 <prgn>dpkg-source</prgn>, are:
1871 <list compact="compact">
1872 <item><p>Changing the permissions of files (other than
1873 <tt>debian/rules</tt>) and directories.</p></item>
1878 The <tt>debian</tt> directory and <tt>debian/rules</tt>
1879 are handled specially by <prgn>dpkg-source</prgn> - before
1880 applying the changes it will create the <tt>debian</tt>
1881 directory, and afterwards it will make
1882 <tt>debian/rules</tt> world-exectuable.
1888 <chapt id="controlfields"><heading>Control files and their fields
1892 Many of the tools in the <prgn>dpkg</prgn> suite manipulate
1893 data in a common format, known as control files. Binary and
1894 source packages have control data as do the <tt>.changes</tt>
1895 files which control the installation of uploaded files, and
1896 <prgn>dpkg</prgn>'s internal databases are in a similar
1900 <sect><heading>Syntax of control files
1904 A file consists of one or more paragraphs of fields. The
1905 paragraphs are separated by blank lines. Some control files
1906 only allow one paragraph; others allow several, in which
1907 case each paragraph often refers to a different package.
1911 Each paragraph is a series of fields and values; each field
1912 consists of a name, followed by a colon and the value. It
1913 ends at the end of the line. Horizontal whitespace (spaces
1914 and tabs) may occur before or after the value and is ignored
1915 there; it is conventional to put a single space after the
1920 Some fields' values may span several lines; in this case
1921 each continuation line <em>must</em> start with a space or
1922 tab. Any trailing spaces or tabs at the end of individual
1923 lines of a field value are ignored.
1927 Except where otherwise stated only a single line of data is
1928 allowed and whitespace is not significant in a field body.
1929 Whitespace may never appear inside names (of packages,
1930 architectures, files or anything else), version numbers or
1931 in between the characters of multi-character version
1936 Field names are not case-sensitive, but it is usual to
1937 capitalise the field names using mixed case as shown below.
1941 Blank lines, or lines consisting only of spaces and tabs,
1942 are not allowed within field values or between fields - that
1943 would mean a new paragraph.
1947 It is important to note that there are several fields which
1948 are optional as far as <prgn>dpkg</prgn> and the related
1949 tools are concerned, but which must appear in every Debian
1950 package, or whose omission may cause problems. When writing
1951 the control files for Debian packages you <em>must</em> read
1952 the Debian policy manual in conjuction with the details
1953 below and the list of fields for the particular file.</p>
1956 <sect><heading>List of fields
1959 <sect1 id="f-Package"><heading><tt>Package</tt>
1963 The name of the binary package. Package names consist of
1964 the alphanumerics and <tt>+</tt> <tt>-</tt> <tt>.</tt>
1965 (plus, minus and full stop).
1968 The characters <tt>@</tt> <tt>:</tt> <tt>=</tt>
1969 <tt>%</tt> <tt>_</tt> (at, colon, equals, percent
1970 and underscore) used to be legal and are still
1971 accepted when found in a package file, but may not be
1972 used in new packages
1978 They must be at least two characters and must start with
1979 an alphanumeric. In current versions of dpkg they are
1980 sort of case-sensitive<footnote><p>This is a
1981 bug.</p></footnote>; use lowercase package names unless
1982 the package you're building (or referring to, in other
1983 fields) is already using uppercase.</p>
1986 <sect1 id="f-Version"><heading><tt>Version</tt>
1990 This lists the source or binary package's version number -
1991 see <ref id="versions">.
1996 <sect1 id="f-Architecture"><heading><tt>Architecture</tt>
2000 This is the architecture string; it is a single word for
2001 the Debian architecture.
2005 <prgn>dpkg</prgn> will check the declared architecture of
2006 a binary package against its own compiled-in value before
2011 The special value <tt>all</tt> indicates that the package
2012 is architecture-independent.
2016 In the main <tt>debian/control</tt> file in the source
2017 package, or in the source package control file
2018 <tt>.dsc</tt>, a list of architectures (separated by
2019 spaces) is also allowed, as is the special value
2020 <tt>any</tt>. A list indicates that the source will build
2021 an architecture-dependent package, and will only work
2022 correctly on the listed architectures. <tt>any</tt>
2023 indicates that though the source package isn't dependent
2024 on any particular architecture and should compile fine on
2025 any one, the binary package(s) produced are not
2026 architecture-independent but will instead be specific to
2027 whatever the current build architecture is.
2031 In a <tt>.changes</tt> file the <tt>Architecture</tt>
2032 field lists the architecture(s) of the package(s)
2033 currently being uploaded. This will be a list; if the
2034 source for the package is being uploaded too the special
2035 entry <tt>source</tt> is also present.
2039 See <ref id="debianrules"> for information how to get the
2040 architecture for the build process.
2044 <sect1 id="f-Maintainer"><heading><tt>Maintainer</tt>
2048 The package maintainer's name and email address. The name
2049 should come first, then the email address inside angle
2050 brackets <tt><></tt> (in RFC822 format).
2054 If the maintainer's name contains a full stop then the
2055 whole field will not work directly as an email address due
2056 to a misfeature in the syntax specified in RFC822; a
2057 program using this field as an address must check for this
2058 and correct the problem if necessary (for example by
2059 putting the name in round brackets and moving it to the
2060 end, and bringing the email address forward).
2064 In a <tt>.changes</tt> file or parsed changelog data this
2065 contains the name and email address of the person
2066 responsible for the particular version in question - this
2067 may not be the package's usual maintainer.
2071 This field is usually optional in as far as the
2072 <prgn>dpkg</prgn> are concerned, but its absence when
2073 building packages usually generates a warning.</p>
2076 <sect1 id="f-Source"><heading><tt>Source</tt>
2080 This field identifies the source package name.
2084 In a main source control information or a
2085 <tt>.changes</tt> or <tt>.dsc</tt> file or parsed
2086 changelog data this may contain only the name of the
2091 In the control file of a binary package (or in a
2092 <tt>Packages</tt> file) it may be followed by a version
2093 number in parentheses.
2096 It is usual to leave a space after the package name if
2097 a version number is specified.
2099 </footnote> This version number may be omitted (and is, by
2100 <prgn>dpkg-gencontrol</prgn>) if it has the same value as
2101 the <tt>Version</tt> field of the binary package in
2102 question. The field itself may be omitted from a binary
2103 package control file when the source package has the same
2104 name and version as the binary package.
2108 <sect1><heading>Package interrelationship fields:
2109 <tt>Depends</tt>, <tt>Pre-Depends</tt>,
2110 <tt>Recommends</tt> <tt>Suggests</tt>, <tt>Conflicts</tt>,
2111 <tt>Provides</tt>, <tt>Replaces</tt>
2115 These fields describe the package's relationships with
2116 other packages. Their syntax and semantics are described
2117 in <ref id="relationships">.</p>
2120 <sect1 id="f-Description"><heading><tt>Description</tt>
2124 In a binary package <tt>Packages</tt> file or main source
2125 control file this field contains a description of the
2126 binary package, in a special format. See <ref
2127 id="descriptions"> for details.
2131 In a <tt>.changes</tt> file it contains a summary of the
2132 descriptions for the packages being uploaded. The part of
2133 the field before the first newline is empty; thereafter
2134 each line has the name of a binary package and the summary
2135 description line from that binary package. Each line is
2136 indented by one space.</p>
2139 <sect1 id="f-Essential"><heading><tt>Essential</tt>
2143 This is a boolean field which may occur only in the
2144 control file of a binary package (or in the
2145 <tt>Packages</tt> file) or in a per-package fields
2146 paragraph of a main source control data file.
2150 If set to <tt>yes</tt> then <prgn>dpkg</prgn> and
2151 <prgn>dselect</prgn> will refuse to remove the package
2152 (though it can be upgraded and/or replaced). The other
2153 possible value is <tt>no</tt>, which is the same as not
2154 having the field at all.</p>
2157 <sect1 id="f-classification"><heading><tt>Section</tt> and
2162 These two fields classify the package. The
2163 <tt>Priority</tt> represents how important that it is that
2164 the user have it installed; the <tt>Section</tt>
2165 represents an application area into which the package has
2170 When they appear in the <tt>debian/control</tt> file these
2171 fields give values for the section and priority subfields
2172 of the <tt>Files</tt> field of the <tt>.changes</tt> file,
2173 and give defaults for the section and priority of the
2178 The section and priority are represented, though not as
2179 separate fields, in the information for each file in the
2180 <qref id="f-Files"><tt>-File</tt></qref>field of a
2181 <tt>.changes</tt> file. The section value in a
2182 <tt>.changes</tt> file is used to decide where to install
2183 a package in the FTP archive.
2187 These fields are not used by by <prgn>dpkg</prgn> proper,
2188 but by <prgn>dselect</prgn> when it sorts packages and
2189 selects defaults. See the Debian policy manual for the
2190 priorities in use and the criteria for selecting the
2191 priority for a Debian package, and look at the Debian FTP
2192 archive for a list of currently in-use priorities.
2196 These fields may appear in binary package control files,
2197 in which case they provide a default value in case the
2198 <tt>Packages</tt> files are missing the information.
2199 <prgn>dpkg</prgn> and <prgn>dselect</prgn> will only use
2200 the value from a <tt>.deb</tt> file if they have no other
2201 information; a value listed in a <tt>Packages</tt> file
2202 will always take precedence. By default
2203 <prgn>dpkg-gencontrol</prgn> does not include the section
2204 and priority in the control file of a binary package - use
2205 the <tt>-isp</tt>, <tt>-is</tt> or <tt>-ip</tt> options to
2206 achieve this effect.</p>
2209 <sect1 id="f-Binary"><heading><tt>Binary</tt>
2213 This field is a list of binary packages.
2217 When it appears in the <tt>.dsc</tt> file it is the list
2218 of binary packages which a source package can produce. It
2219 does not necessarily produce all of these binary packages
2220 for every architecture. The source control file doesn't
2221 contain details of which architectures are appropriate for
2222 which of the binary packages.
2226 When it appears in a <tt>.changes</tt> file it lists the
2227 names of the binary packages actually being uploaded.
2231 The syntax is a list of binary packages separated by
2235 A space after each comma is conventional.
2237 </footnote> Currently the packages must be separated using
2238 only spaces in the <tt>.changes</tt> file.</p>
2241 <sect1 id="f-Installed-Size"><heading><tt>Installed-Size</tt>
2245 This field appears in the control files of binary
2246 packages, and in the <tt>Packages</tt> files. It gives
2247 the total amount of disk space required to install the
2252 The disk space is represented in kilobytes as a simple
2256 <sect1 id="f-Files"><heading><tt>Files</tt>
2260 This field contains a list of files with information about
2261 each one. The exact information and syntax varies with
2262 the context. In all cases the the part of the field
2263 contents on the same line as the field name is empty. The
2264 remainder of the field is one line per file, each line
2265 being indented by one space and containing a number of
2266 sub-fields separated by spaces.
2270 In the <tt>.dsc</tt> (Debian source control) file each
2271 line contains the MD5 checksum, size and filename of the
2272 tarfile and (if applicable) diff file which make up the
2273 remainder of the source package.
2276 That is, the parts which are not the
2279 </footnote> The exact forms of the filenames are described
2280 in <ref id="sourcearchives">.
2284 In the <tt>.changes</tt> file this contains one line per
2285 file being uploaded. Each line contains the MD5 checksum,
2286 size, section and priority and the filename. The section
2287 and priority are the values of the corresponding fields in
2288 the main source control file - see <ref
2289 id="f-classification">. If no section or priority is
2290 specified then <tt>-</tt> should be used, though section
2291 and priority values must be specified for new packages to
2292 be installed properly.
2296 The special value <tt>byhand</tt> for the section in a
2297 <tt>.changes</tt> file indicates that the file in question
2298 is not an ordinary package file and must by installed by
2299 hand by the distribution maintainers. If the section is
2300 <tt>byhand</tt> the priority should be <tt>-</tt>.
2304 If a new Debian revision of a package is being shipped and
2305 no new original source archive is being distributed the
2306 <tt>.dsc</tt> must still contain the <tt>Files</tt> field
2307 entry for the original source archive
2308 <tt><var>package</var>-<var>upstream-version</var>.orig.tar.gz</tt>,
2309 but the <tt>.changes</tt> file should leave it out. In
2310 this case the original source archive on the distribution
2311 site must match exactly, byte-for-byte, the original
2312 source archive which was used to generate the
2313 <tt>.dsc</tt> file and diff which are being uploaded.</p>
2318 id="f-Standards-Version"><heading><tt>Standards-Version</tt>
2322 The most recent version of the standards (the
2323 <prgn>dpkg</prgn> programmers' and policy manuals and
2324 associated texts) with which the package complies. This
2325 is updated manually when editing the source package to
2326 conform to newer standards; it can sometimes be used to
2327 tell when a package needs attention.
2331 Its format is the same as that of a version number except
2332 that no epoch or Debian revision is allowed - see <ref
2337 <sect1 id="f-Distribution"><heading><tt>Distribution</tt>
2341 In a <tt>.changes</tt> file or parsed changelog output
2342 this contains the (space-separated) name(s) of the
2343 distribution(s) where this version of the package should
2344 be or was installed. Distribution names follow the rules
2345 for package names. (See <ref id="f-Package">).
2349 Current distribution values are:
2351 <tag><em>stable</em></tag>
2354 This is the current `released' version of Debian
2355 GNU/Linux. A new version is released approximately
2356 every 3 months after the <em>development</em> code has
2357 been <em>frozen</em> for a month of testing. Once the
2358 distribution is <em>stable</em> only major bug fixes
2359 are allowed. When changes are made to this
2360 distribution, the release number is increased
2361 (for example: 1.2r1 becomes 1.2r2 then 1.2r3, etc).
2365 <tag><em>unstable</em></tag>
2368 This distribution value refers to the
2369 <em>developmental</em> part of the Debian distribution
2370 tree. New packages, new upstream versions of packages
2371 and bug fixes go into the <em>unstable</em> directory
2372 tree. Download from this distribution at your own
2376 <tag><em>contrib</em></tag>
2379 The packages with this distribution value do not meet
2380 the criteria for inclusion in the main Debian
2381 distribution as defined by the Policy Manual, but meet
2382 the criteria for the <em>contrib</em>
2383 Distribution. There is currently no distinction
2384 between stable and unstable packages in the
2385 <em>contrib</em> or <em>non-free</em>
2386 distributions. Use your best judgement in downloading
2387 from this Distribution.</p>
2390 <tag><em>non-free</em></tag>
2393 Like the packages in the <em>contrib</em> seciton,
2394 the packages in <em>non-free</em> do not meet the
2395 criteria for inclusion in the main Debian distribution
2396 as defined by the Policy Manual. Again, use your best
2397 judgement in downloading from this Distribution.</p>
2399 <tag><em>experimental</em></tag>
2402 The packages with this distribution value are deemed
2403 by their maintainers to be high risk. Oftentimes they
2404 represent early beta or developmental packages from
2405 various sources that the maintainers want people to
2406 try, but are not ready to be a part of the other parts
2407 of the Debian distribution tree. Download at your own
2411 <tag><em>frozen</em></tag>
2414 From time to time, (currently, every 3 months) the
2415 <em>unstable</em> distribution enters a state of
2416 `code-freeze' in anticipation of release as a
2417 <em>stable</em> version. During this period of testing
2418 (usually 4 weeks) only fixes for existing or
2419 newly-discovered bugs will be allowed.
2422 </taglist> You should list <em>all</em> distributions that
2423 the package should be installed into. Except in unusual
2424 circumstances, installations to <em>stable</em> should also
2425 go into <em>frozen</em> (if it exists) and
2426 <em>unstable</em>. Likewise, installations into
2427 <em>frozen</em> should also go into <em>unstable</em>.</p>
2430 <sect1 id="f-Urgency"><heading><tt>Urgency</tt>
2434 This is a description of how important it is to upgrade to
2435 this version from previous ones. It consists of a single
2436 keyword usually taking one of the values <tt>LOW</tt>,
2437 <tt>MEDIUM</tt> or <tt>HIGH</tt>) followed by an optional
2438 commentary (separated by a space) which is usually in
2439 parentheses. For example:
2441 Urgency: LOW (HIGH for diversions users)
2446 This field appears in the <tt>.changes</tt> file and in
2447 parsed changelogs; its value appears as the value of the
2448 <tt>urgency</tt> attribute in a <prgn>dpkg</prgn>-style
2449 changelog (see <ref id="dpkgchangelog">).
2453 Urgency keywords are not case-sensitive.</p>
2456 <sect1 id="f-Date"><heading><tt>Date</tt>
2460 In <tt>.changes</tt> files and parsed changelogs, this
2461 gives the date the package was built or last edited.</p>
2464 <sect1 id="f-Format"><heading><tt>Format</tt>
2468 This field occurs in <tt>.changes</tt> files, and
2469 specifies a format revision for the file. The format
2470 described here is version <tt>1.5</tt>. The syntax of the
2471 format value is the same as that of a package version
2472 number except that no epoch or Debian revision is allowed
2473 - see <ref id="versions">.</p>
2476 <sect1 id="f-Changes"><heading><tt>Changes</tt>
2480 In a <tt>.changes</tt> file or parsed changelog this field
2481 contains the human-readable changes data, describing the
2482 differences between the last version and the current one.
2486 There should be nothing in this field before the first
2487 newline; all the subsequent lines must be indented by at
2488 least one space; blank lines must be represented by a line
2489 consiting only of a space and a full stop.
2493 Each version's change information should be preceded by a
2494 `title' line giving at least the version, distribution(s)
2495 and urgency, in a human-readable way.
2499 If data from several versions is being returned the entry
2500 for the most recent version should be returned first, and
2501 entries should be separated by the representation of a
2502 blank line (the `title' line may also be followed by the
2503 representation of blank line).</p>
2506 <sect1 id="f-Filename"><heading><tt>Filename</tt> and
2507 <tt>MSDOS-Filename</tt>
2511 These fields in <tt>Packages</tt> files give the
2512 filename(s) of (the parts of) a package in the
2513 distribution directories, relative to the root of the
2514 Debian hierarchy. If the package has been split into
2515 several parts the parts are all listed in order, separated
2519 <sect1 id="f-Size"><heading><tt>Size</tt> and <tt>MD5sum</tt>
2523 These fields in <tt>Packages</tt> files give the size (in
2524 bytes, expressed in decimal) and MD5 checksum of the
2525 file(s) which make(s) up a binary package in the
2526 distribution. If the package is split into several parts
2527 the values for the parts are listed in order, separated by
2531 <sect1 id="f-Status"><heading><tt>Status</tt>
2535 This field in <prgn>dpkg</prgn>'s status file records
2536 whether the user wants a package installed, removed or
2537 left alone, whether it is broken (requiring
2538 reinstallation) or not and what its current state on the
2539 system is. Each of these pieces of information is a
2543 <sect1 id="f-Config-Version"><heading><tt>Config-Version</tt>
2547 If a package is not installed or not configured, this
2548 field in <prgn>dpkg</prgn>'s status file records the last
2549 version of the package which was successfully
2553 <sect1 id="f-Conffiles"><heading><tt>Conffiles</tt>
2557 This field in <prgn>dpkg</prgn>'s status file contains
2558 information about the automatically-managed configuration
2559 files held by a package. This field should <em>not</em>
2560 appear anywhere in a package!</p>
2563 <sect1><heading>Obsolete fields
2567 These are still recognised by <prgn>dpkg</prgn> but should
2568 not appear anywhere any more.
2569 <taglist compact="compact">
2571 <tag><tt>Revision</tt></tag>
2572 <tag><tt>Package-Revision</tt></tag>
2573 <tag><tt>Package_Revision</tt></tag>
2576 The Debian revision part of the package version was
2577 at one point in a separate control file field. This
2578 field went through several names.</p>
2581 <tag><tt>Recommended</tt></tag>
2582 <item><p>Old name for <tt>Recommends</tt></p>
2585 <tag><tt>Optional</tt></tag>
2586 <item><p>Old name for <tt>Suggests</tt>.</p>
2588 <tag><tt>Class</tt></tag>
2589 <item><p>Old name for <tt>Priority</tt>.</p>
2597 <chapt id="versions"><heading>Version numbering
2601 Every package has a version number, in its <tt>Version</tt>
2606 <prgn>dpkg</prgn> imposes an ordering on version numbers, so
2607 that it can tell whether packages are being up- or downgraded
2608 and so that <prgn>dselect</prgn> can tell whether a package it
2609 finds available is newer than the one installed on the system.
2610 The version number format has the most significant parts (as
2611 far as comparison is concerned) at the beginning.
2615 The version number format is:
2616 &lsqb<var>epoch/<tt>:</tt>]<var>upstream-version</var>[<tt>-/<var>debian-revision</var>].</tt></var>
2620 The three components here are:
2622 <tag><var>epoch</var></tag>
2626 This is a single unsigned integer, which should usually
2627 be small. It may be omitted, in which case zero is
2628 assumed. If it is omitted then the
2629 <var>upstream-version</var> may not contain any colons.
2633 It is provided to allow mistakes in the version numbers
2634 of older versions of a package, and also a package's
2635 previous version numbering schemes, to be left behind.
2639 <prgn>dpkg</prgn> will not usually display the epoch
2640 unless it is essential (non-zero, or if the
2641 <var>upstream-version</var> contains a colon);
2642 <prgn>dselect</prgn> does not display epochs at all in
2643 the main part of the package selection display.</p>
2646 <tag><var>upstream-version</var></tag>
2650 This is the main part of the version. It is usually
2651 version number of the original (`upstream') package of
2652 which the <tt>.deb</tt> file has been made, if this is
2653 applicable. Usually this will be in the same format as
2654 that specified by the upstream author(s); however, it
2655 may need to be reformatted to fit into
2656 <prgn>dpkg</prgn>'s format and comparison scheme.
2660 The comparison behaviour of <prgn>dpkg</prgn> with
2661 respect to the <var>upstream-version</var> is described
2662 below. The <var>upstream-version</var> portion of the
2663 version number is mandatory.
2667 The <var>upstream-version</var> may contain only
2668 alphanumerics and the characters <tt>.</tt> <tt>+</tt>
2669 <tt>-</tt> <tt>:</tt> (full stop, plus, hyphen, colon)
2670 and should start with a digit. If there is no
2671 <var>debian-revision</var> then hyphens are not allowed;
2672 if there is no <var>epoch</var> then colons are not
2676 <tag><var>debian-revision</var></tag>
2680 This part of the version represents the version of the
2681 modifications that were made to the package to make it a
2682 Debian binary package. It is in the same format as the
2683 <var>upstream-version</var> and <prgn>dpkg</prgn>
2684 compares it in the same way.
2688 It is optional; if it isn't present then the
2689 <var>upstream-version</var> may not contain a hyphen.
2690 This format represents the case where a piece of
2691 software was written specifically to be turned into a
2692 Debian binary package, and so there is only one
2693 `debianization' of it and therefore no revision
2694 indication is required.
2698 It is conventional to restart the
2699 <var>debian-revision</var> at <tt>1</tt> each time the
2700 <var>upstream-version</var> is increased.
2704 <prgn>dpkg</prgn> will break the
2705 <var>upstream-version</var> and
2706 <var>debian-revision</var> apart at the last hyphen in
2707 the string. The absence of a <var>debian-revision</var>
2708 compares earlier than the presence of one (but note that
2709 the <var>debian-revision</var> is the least significant
2710 part of the version number).
2714 The <var>debian-revision</var> may contain only
2715 alphanumerics and the characters <tt>+</tt> and
2716 <tt>.</tt> (plus and full stop).
2720 The <var>upstream-version</var> and <var>debian-revision</var> parts are
2721 compared by <prgn>dpkg</prgn> using the same algorithm:
2725 The strings are compared from left to right.
2729 First the initial part of each string consisting entirely of
2730 non-digit characters is determined. These two parts (one of
2731 which may be empty) are compared lexically. If a difference
2732 is found it is returned. The lexical comparison is a
2733 comparison of ASCII values modified so that all the letters
2734 sort earlier than all the non-letters.
2738 Then the initial part of the remainder of each string which
2739 consists entirely of digit characters is determined. The
2740 numerical values of these two parts are compared, and any
2741 difference found is returned as the result of the comparison.
2742 For these purposes an empty string (which can only occur at
2743 the end of one or both version strings being compared) counts
2748 These two steps are repeated (chopping initial non-digit
2749 strings and initial digit strings off from the start) until a
2750 difference is found or both strings are exhausted.
2754 Note that the purpose of epochs is to allow us to leave behind
2755 mistakes in version numbering, and to cope with situations
2756 where the version numbering changes. It is <em>not</em> there
2757 to cope with version numbers containing strings of letters
2758 which <prgn>dpkg</prgn> cannot interpret (such as
2759 <tt>ALPHA</tt> or <tt>pre-</tt>), or with silly orderings (the
2760 author of this manual has heard of a package whose versions
2761 went <tt>1.1</tt>, <tt>1.2</tt>, <tt>1.3</tt>, <tt>1</tt>,
2762 <tt>2.1</tt>, <tt>2.2</tt>, <tt>2</tt> and so forth).
2766 If an upstream package has problematic version numbers they
2767 should be converted to a sane form for use in the
2768 <tt>Version</tt> field.
2772 If you need to compare version numbers in a script, you may use
2773 <tt>dpkg --compare-versions ...</tt>. Type <tt>dpkg
2774 --help</tt> for details on arguments.
2778 <heading>Version numbers based on dates</heading>
2780 In general, Debian packages should use the same version
2781 numbers as the upstream sources.</p>
2784 However, in some cases where the upstream version number is
2785 based on a date (e.g., a development `snapshot' release)
2786 dpkg cannot handle these version numbers currently, without
2787 epochs. For example, dpkg will consider `96May01' to be
2788 greater than `96Dec24'.</p>
2791 To prevent having to use epochs for every new upstream
2792 version, the version number should be changed to the
2793 following format in such cases: `19960501', `19961224'. It
2794 is up to the maintainer whether he/she wants to bother the
2795 upstream maintainer to change the version numbers upstream,
2799 Note, that other version formats based on dates which are
2800 parsed correctly by dpkg should <em>not</em> be changed.</p>
2803 Native Debian packages (i.e., packages which have been
2804 written especially for Debian) whose version numbers include
2805 dates should always use the `YYYYMMDD' format.</p>
2809 <chapt id="maintainerscripts"><heading>Package maintainer scripts
2810 and installation procedure
2813 <sect><heading>Introduction to package maintainer scripts
2817 It is possible to supply scripts as part of a package which
2818 <prgn>dpkg</prgn> will run for you when your package is
2819 installed, upgraded or removed.
2823 These scripts should be the files <tt>preinst</tt>,
2824 <tt>postinst</tt>, <tt>prerm</tt> and <tt>postrm</tt> in the
2825 control area of the package. They must be proper exectuable
2826 files; if they are scripts (which is recommended) they must
2827 start with the usual <tt>#!</tt> convention. They should be
2828 readable and executable to anyone, and not world-writeable.
2832 <prgn>dpkg</prgn> looks at the exit status from these
2833 scripts. It is important that they exit with a non-zero
2834 status if there is an error, so that <prgn>dpkg</prgn> can
2835 stop its processing. For shell scripts this means that you
2836 <em>almost always</em> need to use <tt>set -e</tt> (this is
2837 usually true when writing shell scripts, in fact). It is
2838 also important, of course, that they don't exit with a
2839 non-zero status if everything went well.
2843 It is necessary for the error recovery procedures that the
2844 scripts be idempotent: ie, invoking the same script several
2845 times in the same situation should do no harm. If the first
2846 call failed, or aborted half way through for some reason,
2847 the second call should merely do the things that were left
2848 undone the first time, if any, and exit with a success
2853 When a package is upgraded a combination of the scripts from
2854 the old and new packages is called in amongst the other
2855 steps of the upgrade procedure. If your scripts are going
2856 to be at all complicated you need to be aware of this, and
2857 may need to check the arguments to your scripts.
2861 Broadly speaking the <prgn>preinst</prgn> is called before
2862 (a particular version of) a package is installed, and the
2863 <prgn>postinst</prgn> afterwards; the <prgn>prerm</prgn>
2864 before (a version of) a package is removed and the
2865 <prgn>postrm</prgn> afterwards.
2868 next paragraph by Guy Maor to close bug #2481
2871 <p> Programs called from maintainer scripts should not
2872 normally have a path prepended to them. Before installation
2873 is started <prgn>dpkg</prgn> checks to see if the programs
2874 <prgn>ldconfig</prgn>, <prgn>start-stop-daemon</prgn>,
2875 <prgn>install-info</prgn>, and <prgn>update-rc.d</prgn> can
2876 be found via the <tt>PATH</tt> environment variable. Those
2877 programs, and any other program that one would expect to on
2878 the <tt>PATH</tt>, should thus be invoked without an
2879 absolute pathname. Maintainer scripts should also not reset
2880 the <tt>PATH</tt>, though they might choose to modify it by
2881 pre- or appending package-specific directories. These
2882 considerations really apply to all shell scripts.</p>
2885 <sect id="mscriptsinstact"><heading>Summary of ways maintainer
2890 <list compact="compact">
2892 <p><var>new-preinst</var> <tt>install</tt></p>
2895 <p><var>new-preinst</var> <tt>install</tt>
2896 <var>old-version</var></p>
2899 <p><var>new-preinst</var> <tt>upgrade</tt>
2900 <var>old-version</var></p>
2903 <p><var>old-preinst</var> <tt>abort-upgrade</tt>
2904 <var>new-version</var>
2910 <list compact="compact">
2912 <p><var>postinst</var> <tt>configure</tt>
2913 <var>most-recently-configured-version</var></p>
2916 <p><var>old-postinst</var> <tt>abort-upgrade</tt>
2917 <var>new version</var></p>
2920 <p><var>conflictor's-postinst</var> <tt>abort-remove</tt>
2921 <tt>in-favour</tt> <var>package</var>
2922 <var>new-version</var></p>
2926 <var>deconfigured's-postinst</var>
2927 <tt>abort-deconfigure</tt> <tt>in-favour</tt>
2928 <var>failed-install-package</var> <var>version</var>
2929 <tt>removing</tt> <var>conflicting-package</var>
2936 <list compact="compact">
2938 <p><var>prerm</var> <tt>remove</tt></p>
2941 <p><var>old-prerm</var> <tt>upgrade</tt>
2942 <var>new-version</var></p>
2945 <p><var>new-prerm</var> <tt>failed-upgrade</tt>
2946 <var>old-version</var></p>
2949 <p><var>conflictor's-prerm</var> <tt>remove</tt>
2950 <tt>in-favour</tt> <var>package</var>
2951 <var>new-version</var></p>
2955 <var>deconfigured's-prerm</var> <tt>deconfigure</tt>
2956 <tt>in-favour</tt> <var>package-being-installed</var>
2957 <var>version</var> <tt>removing</tt>
2958 <var>conflicting-package</var>
2965 <list compact="compact">
2967 <p><var>postrm</var> <tt>remove</tt></p>
2970 <p><var>postrm</var> <tt>purge</tt></p>
2974 <var>old-postrm</var> <tt>upgrade</tt>
2975 <var>new-version</var></p>
2978 <p><var>new-postrm</var> <tt>failed-upgrade</tt>
2979 <var>old-version</var></p>
2982 <p><var>new-postrm</var> <tt>abort-install</tt></p>
2985 <p><var>new-postrm</var> <tt>abort-install</tt>
2986 <var>old-version</var></p>
2989 <p><var>new-postrm</var> <tt>abort-upgrade</tt>
2990 <var>old-version</var></p>
2994 <var>disappearer's-postrm</var> <tt>disappear</tt>
2995 <var>overwriter</var>
2996 <var>overwriter-version</var></p></item>
3001 <sect id="unpackphase"><heading>Details of unpack phase of
3002 installation or upgrade
3006 The procedure on installation/upgrade/overwrite/disappear
3007 (ie, when running <tt>dpkg --unpack</tt>, or the unpack
3009 --install</tt>) is as follows. In each case if an error occurs the
3010 actions in are general run backwards - this means that the maintainer
3011 scripts are run with different arguments in reverse order. These are
3012 the `error unwind' calls listed below.
3019 <p>If a version the package is already
3022 <var>old-prerm</var> upgrade <var>new-version</var>
3027 If this gives an error (ie, a non-zero exit
3028 status), dpkg will attempt instead:
3030 <var>new-prerm</var> failed-upgrade <var>old-version</var>
3032 Error unwind, for both the above cases:
3034 <var>old-postinst</var> abort-upgrade <var>new-version</var>
3042 <p>If a `conflicting' package is being removed at the same time:
3046 If any packages depended on that conflicting
3047 package and <tt>--auto-deconfigure</tt> is
3048 specified, call, for each such package:
3050 <var>deconfigured's-prerm</var> deconfigure \
3051 in-favour <var>package-being-installed</var> <var>version</var> \
3052 removing <var>conflicting-package</var> <var>version</var>
3056 <var>deconfigured's-postinst</var> abort-deconfigure \
3057 in-favour <var>package-being-installed-but-failed</var> <var>version</var> \
3058 removing <var>conflicting-package</var> <var>version</var>
3060 The deconfigured packages are marked as
3061 requiring configuration, so that if
3062 <tt>--install</tt> is used they will be
3063 configured again if possible.</p>
3066 <p>To prepare for removal of the conflicting package, call:
3068 <var>conflictor's-prerm</var> remove in-favour <var>package</var> <var>new-version</var>
3072 <var>conflictor's-postinst</var> abort-remove \
3073 in-favour <var>package</var> <var>new-version</var>
3084 <p>If the package is being upgraded, call:
3086 <var>new-preinst</var> upgrade <var>old-version</var>
3091 Otherwise, if the package had some configuration
3092 files from a previous version installed (ie, it
3093 is in the `configuration files only' state):
3095 <var>new-preinst</var> install <var>old-version</var>
3099 <p>Otherwise (ie, the package was completely purged):
3101 <var>new-preinst</var> install
3103 Error unwind versions, respectively:
3105 <var>new-postrm</var> abort-upgrade <var>old-version</var>
3106 <var>new-postrm</var> abort-install <var>old-version</var>
3107 <var>new-postrm</var> abort-install
3117 The new package's files are unpacked, overwriting any
3118 that may be on the system already, for example any
3119 from the old version of the same package or from
3120 another package (backups of the old files are left
3121 around, and if anything goes wrong dpkg will attempt
3122 to put them back as part of the error unwind).
3126 It is an error for a package to contains files which
3127 are on the system in another package, unless
3128 <tt>Replaces</tt> is used (see <ref id="replaces">).
3129 Currently the <tt>--force-overwrite</tt> flag is
3130 enabled, downgrading it to a warning, but this may not
3135 It is a more serious error for a package to contain a
3136 plain file or other kind of nondirectory where another
3137 package has a directory (again, unless
3138 <tt>Replaces</tt> is used). This error can be
3139 overridden if desired using
3140 <tt>--force-overwrite-dir</tt>, but this is not
3145 Packages which overwrite each other's files produce
3146 behaviour which though deterministic is hard for the
3147 system administrator to understand. It can easily
3148 lead to `missing' programs if, for example, a package
3149 is installed which overwrites a file from another
3150 package, and is then removed again.
3153 Part of the problem is due to what is arguably a
3154 bug in <prgn>dpkg</prgn>.
3160 A directory will never be replaced by a symbolic links
3161 to a directory or vice versa; instead, the existing
3162 state (symlink or not) will be left alone and
3163 <prgn>dpkg</prgn> will follow the symlink if there is
3171 <p>If the package is being upgraded, call
3173 <var>old-postrm</var> upgrade <var>new-version</var>
3177 <p>If this fails, <prgn>dpkg</prgn> will attempt:
3179 <var>new-postrm</var> failed-upgrade <var>old-version</var>
3181 Error unwind, for both cases:
3183 <var>old-preinst</var> abort-upgrade <var>new-version</var>
3188 This is the point of no return - if <prgn>dpkg</prgn>
3189 gets this far, it won't back off past this point if an
3190 error occurs. This will leave the package in a fairly
3191 bad state, which will require a successful
3192 reinstallation to clear up, but it's when
3193 <prgn>dpkg</prgn> starts doing things that are
3198 Any files which were in the old version of the package
3199 but not in the new are removed.</p>
3202 <p>The new file list replaces the old.</p>
3205 <p>The new maintainer scripts replace the old.</p>
3209 <p>Any packages all of whose files have been overwritten during the
3210 installation, and which aren't required for
3211 dependencies, are considered to have been removed.
3212 For each such package,
3215 <p><prgn>dpkg</prgn> calls:
3217 <var>disappearer's-postrm</var> disappear \
3218 <var>overwriter</var> <var>overwriter-version</var>
3223 <p>The package's maintainer scripts are removed.
3228 It is noted in the status database as being in a
3229 sane state, namely not installed (any conffiles
3230 it may have are ignored, rather than being
3231 removed by <prgn>dpkg</prgn>). Note that
3232 disappearing packages do not have their prerm
3233 called, because <prgn>dpkg</prgn> doesn't know
3234 in advance that the package is going to
3243 Any files in the package we're unpacking that are also
3244 listed in the file lists of other packages are removed
3245 from those lists. (This will lobotomise the file list
3246 of the `conflicting' package if there is one.)
3251 The backup files made during installation, above, are
3258 The new package's status is now sane, and recorded as
3259 `unpacked'. Here is another point of no return - if
3260 the conflicting package's removal fails we do not
3261 unwind the rest of the installation; the conflicting
3262 package is left in a half-removed limbo.
3267 If there was a conflicting package we go and do the
3268 removal actions (described below), starting with the
3269 removal of the conflicting package's files (any that
3270 are also in the package being installed have already
3271 been removed from the conflicting package's file list,
3272 and so do not get removed now).
3279 <sect><heading>Details of configuration
3283 When we configure a package (this happens with <tt>dpkg
3284 --install</tt>, or with <tt>--configure</tt>), we first
3285 update the conffiles and then call:
3287 <var>postinst</var> configure <var>most-recently-configured-version</var>
3292 No attempt is made to unwind after errors during
3297 If there is no most recently configured version
3298 <prgn>dpkg</prgn> will pass a null argument; older versions
3299 of dpkg may pass <tt><unknown></tt> (including the
3300 angle brackets) in this case. Even older ones do not pass a
3301 second argument at all, under any circumstances.
3305 <sect><heading>Details of removal and/or configuration purging
3313 <var>prerm</var> remove
3319 The package's files are removed (except conffiles).
3324 <var>postrm</var> remove
3328 <p>All the maintainer scripts except the postrm are removed.
3332 If we aren't purging the package we stop here. Note
3333 that packages which have no postrm and no conffiles
3334 are automatically purged when removed, as there is no
3335 difference except for the <prgn>dpkg</prgn>
3340 The conffiles and any backup files (<tt>~</tt>-files,
3341 <tt>#*#</tt> files, <tt>%</tt>-files,
3342 <tt>.dpkg-{old,new,tmp}</tt>, etc.) are removed.</p>
3346 <var>postrm</var> purge
3350 <p>The package's file list is removed.</p>
3353 No attempt is made to unwind after errors during
3358 <chapt id="descriptions"><heading>Descriptions of packages - the
3359 <tt>Description</tt> field
3363 The <tt>Description</tt> control file field is used by
3364 <prgn>dselect</prgn> when the user is selecting which packages
3365 to install and by <prgn>dpkg</prgn> when it displays
3366 information about the status of packages and so forth. It is
3367 included on the FTP site in the <prgn>Packages</prgn> files,
3368 and may also be used by the Debian WWW pages.
3372 The description is intended to describe the program to a user
3373 who has never met it before so that they know whether they
3374 want to install it. It should also give information about the
3375 significant dependencies and conflicts between this package
3376 and others, so that the user knows why these dependencies and
3377 conflicts have been declared.
3381 The field's format is as follows:
3383 Description: <var>single line synopsis</var>
3384 <var>extended description over several lines</var>
3389 The synopsis is often printed in lists of packages and so
3390 forth, and should be as informative as possible. Every
3391 package should also have an extended description.
3394 <sect><heading>Types of formatting line in the extended
3402 Those starting with a single space are part of a
3403 paragraph. Successive lines of this form will be
3404 word-wrapped when displayed. The leading space will
3405 usually be stripped off.
3411 Those starting with two or more spaces. These will be
3412 displayed verbatim. If the display cannot be panned
3413 horizontally the displaying program will linewrap them
3414 `hard' (ie, without taking account of word breaks).
3415 If it can they will be allowed to trail off to the
3416 right. None, one or two initial spaces may be
3417 deleted, but the number of spaces deleted from each
3418 line will be the same (so that you can have indenting
3419 work correctly, for example).
3424 <p>Those containing a single space followed by a single full stop
3425 character. These are rendered as blank lines. This
3426 is the <em>only</em> way to get a blank line - see
3432 Those containing a space, a full stop and some more
3433 characters. These are for future expansion. Do not
3440 <sect><heading>Notes about writing descriptions
3444 <em>Always</em> start extended description lines with at least one
3445 whitespace character. Fields in the control file and in the Packages
3446 file are separated by field names starting in the first column, just
3447 as message header fields are in RFC822. Forgetting the whitespace
3448 will cause <prgn>dpkg-deb</prgn>
3451 Version 0.93.23 or later.
3453 </footnote> to produce a syntax error when trying to build
3454 the package. If you force it to build anyway
3455 <prgn>dpkg</prgn> will refuse to install the resulting
3460 <em>Do not</em> include any completely <em>empty</em>
3461 lines. These separate different records in the Packages file
3462 and different packages in the <tt>debian/control</tt> file,
3463 and are forbidden in package control files. See the
3464 previous paragraph for what happens if you get this wrong.
3468 The single line synopsis should be kept brief - certainly
3469 under 80 characters. <prgn>dselect</prgn> displays between
3470 25 and 49 characters without panning if you're using an
3471 80-column terminal, depending on what display options are in
3476 Do not include the package name in the synopsis line. The
3477 display software knows how to display this already, and you
3478 do not need to state it. Remember that in many situations
3479 the user may only see the synopsis line - make it as
3480 informative as you can.
3484 The extended description should describe what the package
3485 does and how it relates to the rest of the system (in terms
3486 of, for example, which subsystem it is which part of).
3490 The blurb that comes with a program in its announcements
3491 and/or <prgn>README</prgn> files is rarely suitable for use
3492 in a description. It is usually aimed at people who are
3493 already in the community where the package is used. The
3494 description field needs to make sense to anyone, even people
3495 who have no idea about any of the things the package deals
3500 Put important information first, both in the synopis and
3501 extended description. Sometimes only the first part of the
3502 synopsis or of the description will be displayed. You can
3503 assume that there will usually be a way to see the whole
3504 extended description.
3508 You may include information about dependencies and so forth
3509 in the extended description, if you wish.
3513 Do not use tab characters. Their effect is not predictable.
3517 Do not try to linewrap the summary (the part on the same
3518 line as the field name <tt>Description</tt>) into the
3519 extended description. This will not work correctly when the
3520 full description is displayed, and makes no sense where only
3521 the summary is available.</p>
3524 <sect><heading>Example description in control file for Smail
3530 Version: 3.1.29.1-13
3531 Maintainer: Ian Jackson <iwj10@cus.cam.ac.uk>
3532 Recommends: pine | mailx | elm | emacs | mail-user-agent
3534 Depends: cron, libc5
3536 Provides: mail-transport-agent
3537 Description: Electronic mail transport system.
3538 Smail is the recommended mail transport agent (MTA) for Debian.
3540 An MTA is the innards of the mail system - it takes messages from
3541 user-friendly mailer programs and arranges for them to be delivered
3542 locally or passed on to other systems as required.
3544 In order to make use of it you must have one or more user level
3545 mailreader programs such as elm, pine, mailx or Emacs (which has Rmail
3546 and VM as mailreaders) installed. If you wish to send messages other
3547 than just to other users of your system you must also have appropriate
3548 networking support, in the form of IP or UUCP.
3554 <chapt id="relationships"><heading>Declaring relationships between
3559 Packages can declare in their control file that they have
3560 certain relationships to other packages - for example, that
3561 they may not be installed at the same time as certain other
3562 packages, and/or that they depend on the presence of others,
3563 or that they should overwrite files in certain other packages
3568 This is done using the <tt>Depends</tt>, <tt>Recommends</tt>,
3569 <tt>Suggests</tt>, <tt>Conflicts</tt>, <tt>Provides</tt> and
3570 <tt>Replaces</tt> control file fields.
3574 Source packages may declare relationships to binary packages,
3575 saying that they require certain binary packages being
3576 installed or absent at the time of building the package.
3580 This is done using the <tt>Build-Depends</tt>,
3581 <tt>Build-Depends-Indep</tt>, <tt>Build-Conflicts</tt>, and
3582 <tt>Build-Conflicts-Indep</tt> control file fields.
3585 <sect id="depsyntax"><heading>Syntax of relationship fields
3589 These fields all have a uniform syntax. They are a list of
3590 package names separated by commas.
3594 In <tt>Depends</tt>, <tt>Recommends</tt>, <tt>Suggests</tt>,
3595 <tt>Pre-Depends</tt>, <tt>Build-Depends</tt> and
3596 <tt>Build-Depends-Indep</tt>(the fields which declare
3597 dependencies of the package in which they occur on other
3598 packages) these package names may also be lists of
3599 alternative package names, separated by vertical bar symbols
3600 <tt>|</tt> (pipe symbols).
3604 All the fields except <tt>Provides</tt> may restrict their
3605 applicability to particular versions of each named package.
3606 This is done in parentheses after each individual package
3607 name; the parentheses should contain a relation from the
3608 list below followed by a version number, in the format
3609 described in <ref id="versions">.
3613 The relations allowed are <tt><<</tt>, <tt><=</tt>,
3614 <tt>=</tt>, <tt>>=</tt> and <tt>>></tt> for
3615 strictly earlier, earlier or equal, exactly equal, later or
3616 equal and strictly later, respectively. The forms
3617 <tt><</tt> and <tt>></tt> were used to mean
3618 earlier/later or equal, rather than strictly earlier/later,
3619 so they should not appear in new packages (though
3620 <prgn>dpkg</prgn> still supports them).
3624 Whitespace may appear at any point in the version
3625 specification, and must appear where it's necessary to
3626 disambiguate; it is not otherwise significant. For
3627 consistency and in case of future changes to
3628 <prgn>dpkg</prgn> it is recommended that a single space be
3629 used after a version relationship and before a version
3630 number; it is usual also to put a single space after each
3631 comma, on either side of each vertical bar, and before each
3640 Depends: libc5 (>= 5.2.18-4), mime-support, csh | tcsh
3645 All fields that specify build-time relationships
3646 (<tt>Build-Depends</tt>, <tt>Build-Depends-Indep</tt>,
3647 <tt>Build-Conflicts</tt> and <tt>Build-Conflicts-Indep</tt>)
3648 may be restricted to a certain set of architectures. This
3649 is done in brackets after each individual package name and
3650 the optional version specification. The brackets enclose a
3651 list of Debian architecture names separated by whitespace.
3652 An exclamation mark may be prepended to each name. If the
3653 current Debian host architecture is not in this list and
3654 there are no exclamation marks in the list, or it is in the
3655 list with a prepended exclamation mark, the package name and
3656 the associated version specification are ignored completely
3657 for the purposes of defining the relationships.
3664 Build-Depends-Indep: texinfo
3665 Build-Depends: kernel-headers-2.2.10 [!hurd-i386],
3666 hurd-dev [hurd-i386], gnumach-dev [hurd-i386]
3672 <heading>Binary Dependencies - <tt>Depends</tt>,
3673 <tt>Recommends</tt>, <tt>Suggests</tt>, <tt>Pre-Depends</tt>
3677 These four fields are used to declare a dependency by one
3678 package on another. They appear in the depending package's
3683 All but <tt>Pre-Depends</tt> (discussed below) take effect
3684 <em>only</em> when a package is to be configured. They do
3685 not prevent a package being on the system in an unconfigured
3686 state while its dependencies are unsatisfied, and it is
3687 possible to replace a package whose dependencies are
3688 satisfied and which is properly installed with a different
3689 version whose dependencies are not and cannot be satisfied;
3690 when this is done the depending package will be left
3691 unconfigured (since attempts to configure it will give
3692 errors) and will not function properly.
3696 For this reason packages in an installation run are usually
3697 all unpacked first and all configured later; this gives
3698 later versions of packages with dependencies on later
3699 versions of other packages the opportunity to have their
3700 dependencies satisfied.
3704 Thus <tt>Depends</tt> allows package maintainers to impose
3705 an order in which packages should be configured.
3707 <tag><tt>Depends</tt></tag>
3710 <p>This declares an absolute dependency.
3714 <prgn>dpkg</prgn> will not configure packages whose
3715 dependencies aren't satisfied. If it is asked to make
3716 an installation which would cause an installed
3717 package's dependencies to become unsatisfied it will
3721 Current versions (1.2.4) of <prgn>dpkg</prgn> have
3722 a bug in this area which will cause some of these
3723 problems to be ignored.
3725 </footnote>, unless <tt>--auto-deconfigure</tt> is
3726 specified, in which case those packages will be
3727 deconfigured before the installation proceeds.
3731 <prgn>dselect</prgn> makes it hard for the user to
3732 select packages for installation, removal or upgrade
3733 in a way that would mean that packages'
3734 <prgn>Depends</prgn> fields would be unsatisfied. The
3735 user can override this if they wish, for example if
3736 they know that <prgn>dselect</prgn> has an out-of-date
3737 view of the real package relationships.
3741 The <tt>Depends</tt> field should be used if the
3742 depended-on package is required for the depending
3743 package to provide a significant amount of
3747 <tag><tt>Recommends</tt></tag>
3749 <p>This declares a strong, but not absolute, dependency.
3753 <tt>Recommends</tt> is ignored by <prgn>dpkg</prgn>,
3754 so that users using the command-line (who are presumed
3755 to know what they're doing) will not be impeded.
3759 It is treated by <prgn>dselect</prgn> exactly as
3760 <tt>Depends</tt> is; this makes it hard for the user
3761 to select things so as to leave <tt>Recommends</tt>
3762 fields unsatisfied, but they are able to do so by
3767 The <tt>Recommends</tt> field should list packages
3768 that would be found together with this one in all but
3769 unusual installations.</p>
3772 <tag><tt>Suggests</tt></tag>
3776 This is used to declare that one package may be more
3777 useful with one or more others. Using this field
3778 tells the packaging system and the user that the
3779 listed packages are related to this one and can
3780 perhaps enhance its usefulness, but that installing
3781 this one without them is perfectly reasonable.
3785 <prgn>dselect</prgn> will offer suggsted packages to
3786 the system administrator when they select the
3787 suggesting package, but the default is not to install
3788 the suggested package.</p>
3791 <tag><tt>Pre-Depends</tt></tag>
3794 <p>This field is like <tt>Depends</tt>, except that it also forces
3795 <prgn>dpkg</prgn> to complete installation of the
3796 packages named before even starting the installation
3797 of the package which declares the predependency.
3801 <prgn>dselect</prgn> checks for predependencies when
3802 it is doing an installation run, and will attempt to
3803 find the packages which are required to be installed
3804 first and do so in the right order.
3808 However, this process is slow (because it requires
3809 repeated invocations of <prgn>dpkg</prgn>) and
3810 troublesome (because it requires guessing where to
3811 find the appropriate files).
3815 For these reasons, and because this field imposes
3816 restrictions on the order in which packages may be
3817 unpacked (which can be difficult for installations
3818 from multipart media, for example),
3819 <tt>Pre-Depends</tt> should be used sparingly,
3820 preferably only by packages whose premature upgrade or
3821 installation would hamper the ability of the system to
3822 continue with any upgrade that might be in progress.
3826 When the package declaring it is being configured, a
3827 <tt>Pre-Dependency</tt> will be considered satisfied
3828 only if the depending package has been correctly
3829 configured, just as if an ordinary <tt>Depends</tt>
3834 However, when a package declaring a predependency is
3835 being unpacked the predependency can be satisfied even
3836 if the depended-on package(s) are only unpacked or
3837 half-configured, provided that they have been
3838 configured correctly at some point in the past (and
3839 not removed or partially removed since). In this case
3840 both the previously-configured and currently unpacked
3841 or half-configured versions must satisfy any version
3842 clause in the <tt>Pre-Depends</tt> field.
3848 When selecting which level of dependency to use you should
3849 consider how important the depended-on package is to the
3850 functionality of the one declaring the dependency. Some
3851 packages are composed of components of varying degrees of
3852 importance. Such a package should list using
3853 <tt>Depends</tt> the package(s) which are required by the
3854 more important components. The other components'
3855 requirements may be mentioned as Suggestions or
3856 Recommendations, as appropriate to the components' relative
3860 <sect1><heading>Dependencies on shared libraries
3864 The dependency fields listed above are used by packages
3865 which need shared libraries to declare dependencies on the
3866 appropriate packages.
3870 These dependencies are usually determined automatically
3871 using <prgn>dpkg-shlibdeps</prgn> and inserted in the
3872 package control file using the control file substitution
3873 variables mechanism; see <ref id="srcsubstvars"> and
3874 <ref id="sourcetools">.
3878 <sect1><heading>Deconfiguration due to removal during bulk
3883 If <prgn>dpkg</prgn> would like to remove a package due to a
3884 conflict, as described above, but this would violate a
3885 dependency of some other package on the system,
3886 <prgn>dpkg</prgn> will usually not remove the conflicting
3887 package and halt with an error.
3891 However, if the <tt>--auto-deconfigure</tt> (<tt>-B</tt>)
3892 option is used <prgn>dpkg</prgn> will automatically
3893 `deconfigure' the package with the problematic dependency,
3894 so that the conflicting package can be removed and the
3895 package we're trying to install can be installed. If
3896 <prgn>dpkg</prgn> is being asked to install packages (rather
3897 than just unpacking them) it will try to reconfigure the
3898 package when it has unpacked all its arguments, in the hope
3899 that one of the other packages it is installing will satisfy
3900 the problematic dependency.
3904 <prgn>dselect</prgn> supplies this argument to
3905 <prgn>dpkg</prgn> when it invokes it, so that bulk
3906 installations proceed smoothly.
3910 <sect id="conflicts"><heading>Alternative binary packages -
3911 <tt>Conflicts</tt> and <tt>Replaces</tt>
3915 When one binary package declares a conflict with another
3916 <prgn>dpkg</prgn> will refuse to allow them to be installed
3917 on the system at the same time.
3921 If one package is to be installed, the other must be removed
3922 first - if the package being installed is marked as
3923 replacing (<ref id="replaces">) the one on the system, or
3924 the one on the system is marked as deselected, or both
3925 packages are marked <tt>Essential</tt>, then
3926 <prgn>dpkg</prgn> will automatically remove the package
3927 which is causing the conflict, otherwise it will halt the
3928 installation of the new package with an error. This
3929 mechanism specifically doesn't work when the installed
3930 package is <tt>Essential</tt>, but the new package is not.
3934 <prgn>dselect</prgn> makes it hard to select conflicting
3935 packages, though the user can override this if they wish.
3936 If they do not override it then <prgn>dselect</prgn> will
3937 select one of the packages for removal, and the user must
3938 make sure it is the right one. In the future
3939 <prgn>dselect</prgn> will look for the presence of a
3940 <tt>Replaces</tt> field to help decide which package should
3941 be installed and which removed.
3945 A package will not cause a conflict merely because its
3946 configuration files are still installed; it must be at least
3951 A special exception is made for packages which declare a
3952 conflict with their own package name, or with a virtual
3953 package which they provide (see below): this does not
3954 prevent their installation, and allows a package to conflict
3955 with others providing a replacement for it. You use this
3956 feature when you want the package in question to be the only
3957 package providing something.
3961 A <tt>Conflicts</tt> entry should almost never have an
3962 `earlier than' version clause. This would prevent
3963 <prgn>dpkg</prgn> from upgrading or installing the package
3964 which declared such a conflict until the upgrade or removal
3965 of the conflicted-with package had been completed. This
3966 aspect of installation ordering is not handled by
3967 <prgn>dselect</prgn>, so that the use <tt>Conflicts</tt> in
3968 this way is likely to cause problems for `bulk run' upgrades
3973 <sect id="virtual"><heading>Virtual packages - <tt>Provides</tt>
3977 As well as the names of actual (`concrete') packages, the
3978 package relationship fields <tt>Depends</tt>,
3979 <tt>Build-Depends</tt>, <tt>Build-Depends-Indep</tt>,
3980 <tt>Recommends</tt>, <tt>Suggests</tt>, <tt>Conflicts</tt>,
3981 <tt>Build-Conflicts</tt> and <tt>Build-Conflicts-Indep</tt> may
3982 mention virtual packages.
3986 A virtual package is one which appears in the
3987 <tt>Provides</tt> control file field of another package.
3988 The effect is as if the package(s) which provide a
3989 particular virtual package name had been listed by name
3990 everywhere the virtual package name appears.
3994 If there are both a real and a virtual package of the same
3995 name then the dependency may be satisfied (or the conflict
3996 caused) by either the real package or any of the virtual
3997 packages which provide it. This is so that, for example,
4003 and someone else releases an xemacs package they can say
4007 </example> and all will work in the interim (until a purely
4008 virtual package name is decided on and the <tt>emacs</tt>
4009 and <tt>vm</tt> packages are changed to use it).
4013 If a dependency or a conflict has a version number attached
4014 then only real packages will be considered to see whether
4015 the relationship is satisfied (or the prohibition violated,
4016 for a conflict) - it is assumed that a real package which
4017 provides virtual package is not of the `right' version. So,
4018 a <tt>Provides</tt> field may not contain version numbers,
4019 and the version number of the concrete package which
4020 provides a particular virtual package will not be looked at
4021 when considering a dependency on or conflict with the
4022 virtual package name.
4026 It is likely that the ability will be added in a future
4027 release of <prgn>dpkg</prgn> to specify a version number for
4028 each virtual package it provides. This feature is not yet
4029 present, however, and is expected to be used only
4034 If you want to specify which of a set of real packages should be the
4035 default to satisfy a particular dependency on a virtual package, you
4036 should list the real package as an alternative before the virtual.
4041 <sect id="replaces"><heading><tt>Replaces</tt> - overwriting
4042 files and replacing packages
4046 The <tt>Replaces</tt> control file field has two purposes,
4047 which come into play in different situations.
4051 Virtual packages (<ref id="virtual">) are not considered
4052 when looking at a <tt>Replaces</tt> field - the packages
4053 declared as being replaced must be mentioned by their real
4057 <sect1><heading>Overwriting files in other packages
4061 Firstly, as mentioned before, it is usually an error for a
4062 package to contains files which are on the system in
4063 another package, though currently the
4064 <tt>--force-overwrite</tt> flag is enabled by default,
4065 downgrading the error to a warning,
4069 If the overwriting package declares that it replaces the
4070 one containing the file being overwritten then
4071 <prgn>dpkg</prgn> will proceed, and replace the file from
4072 the old package with that from the new. The file will no
4073 longer be listed as `owned' by the old package.
4077 If a package is completely replaced in this way, so that
4078 <prgn>dpkg</prgn> does not know of any files it still
4079 contains, it is considered to have disappeared. It will
4080 be marked as not wanted on the system (selected for
4081 removal) and not installed. Any conffiles details noted
4082 in the package will be ignored, as they will have been
4083 taken over by the replacing package(s). The package's
4084 <prgn>postrm</prgn> script will be run to allow the
4085 package to do any final cleanup required. See <ref
4086 id="mscriptsinstact">.
4090 In the future <prgn>dpkg</prgn> will discard files which
4091 overwrite those from another package which declares that
4092 it replaces the one being installed (so that you can
4093 install an older version of a package without problems).
4097 This usage of <tt>Replaces</tt> only takes effect when
4098 both packages are at least partially on the system at
4099 once, so that it can only happen if they do not conflict
4100 or if the conflict has been overridden.</p>
4103 <sect1><heading>Replacing whole packages, forcing their
4108 Secondly, <tt>Replaces</tt> allows <prgn>dpkg</prgn> and
4109 <prgn>dselect</prgn> to resolve which package should be
4110 removed when there is a conflict - see <ref id="conflicts">. This
4111 usage only takes effect when the two packages <em>do</em>
4112 conflict, so that the two effects do not interfere with
4118 <sect><heading>Defaults for satisfying dependencies - ordering
4122 Ordering is significant in dependency fields.
4126 Usually dselect will suggest to the user that they select
4127 the package with the most `fundamental' class (eg, it will
4128 prefer Base packages to Optional ones), or the one that they
4129 `most wanted' to select in some sense.
4133 In the absence of other information <prgn>dselect</prgn>
4134 will offer a default selection of the first named package in
4135 a list of alternatives.
4139 However, there is no way to specify the `order' of several
4140 packages which all provide the same thing, when that thing
4141 is listed as a dependency.
4145 Therefore a dependency on a virtual package should contain a
4146 concrete package name as the first alternative, so that this
4151 For example, consider the set of packages:
4154 Recommends: info-browser
4157 Provides: info-browser
4160 Provides: info-browser
4165 If <prgn>emacs</prgn> and <prgn>info</prgn> both have the
4166 same priority then <prgn>dselect</prgn>'s choice is
4167 essentially random. Better would be
4170 Recommends: info | info-browser
4172 so that <prgn>dselect</prgn> defaults to selecting the
4173 lightweight standalone info browser.
4178 <sect><heading>Relationships between source and binary packages -
4179 <tt>Build-Depends</tt>, <tt>Build-Depends-Indep</tt>,
4180 <tt>Build-Conflicts</tt>, <tt>Build-Conflicts-Indep</tt>
4184 A source package may declare a dependency or a conflict on a
4185 binary package. This is done with the control file fields
4186 <tt>Build-Depends</tt>, <tt>Build-Depends-Indep</tt>,
4187 <tt>Build-Conflicts</tt>, and <tt>Build-Conflicts-Indep</tt>. Their
4188 semantics is that the dependencies and conflicts they define
4189 must be satisfied (as defined earlier for binary packages),
4190 when one of the targets in <tt>debian/rules</tt> that the
4191 particular field applies to is invoked.
4194 <tag><tt>Build-Depends</tt>, <tt>Build-Conflicts</tt></tag>
4197 The <tt>Build-Depends</tt> and
4198 <tt>Build-Conflicts</tt> fields apply to the targets
4199 <tt>build</tt>, <tt>binary</tt>, <tt>binary-arch</tt>
4200 and <tt>binary-indep</tt>.
4203 <tag><tt>Build-Depends-Indep</tt>, <tt>Build-Conflicts-Indep</tt></tag>
4206 The <tt>Build-Depends-Indep</tt> and
4207 <tt>Build-Conflicts-Indep</tt> fields apply to the
4208 targets <tt>binary</tt> and <tt>binary-indep</tt>.
4219 <chapt id="conffiles"><heading>Configuration file handling
4223 <prgn>dpkg</prgn> can do a certain amount of automatic
4224 handling of package configuration files.
4228 Whether this mechanism is appropriate depends on a number of
4229 factors, but basically there are two approaches to any
4230 particular configuration file.
4234 The easy method is to ship a best-effort configuration in the
4235 package, and use <prgn>dpkg</prgn>'s conffile mechanism to
4236 handle updates. If the user is unlikely to want to edit the
4237 file, but you need them to be able to without losing their
4238 changes, and a new package with a changed version of the file
4239 is only released infrequently, this is a good approach.
4243 The hard method is to build the configuration file from
4244 scratch in the <prgn>postinst</prgn> script, and to take the
4245 responsibility for fixing any mistakes made in earlier
4246 versions of the package automatically. This will be
4247 appropriate if the file is likely to need to be different on
4251 <sect><heading>Automatic handling of configuration files by
4256 A package may contain a control area file called
4257 <tt>conffiles</tt>. This file should be a list of filenames
4258 of configuration files needing automatic handling, separated
4259 by newlines. The filenames should be absolute pathnames,
4260 and the files referred to should actually exist in the
4265 When a package is upgraded <prgn>dpkg</prgn> will process
4266 the configuration files during the configuration stage,
4267 shortly before it runs the package's <prgn>postinst</prgn>
4272 For each file it checks to see whether the version of the
4273 file included in the package is the same as the one that was
4274 included in the last version of the package (the one that is
4275 being upgraded from); it also compares the version currently
4276 installed on the system with the one shipped with the last
4281 If neither the user nor the package maintainer has changed
4282 the file, it is left alone. If one or the other has changed
4283 their version, then the changed version is preferred - i.e.,
4284 if the user edits their file, but the package maintainer
4285 doesn't ship a different version, the user's changes will
4286 stay, silently, but if the maintainer ships a new version
4287 and the user hasn't edited it the new version will be
4288 installed (with an informative message). If both have
4289 changed their version the user is prompted about the problem
4290 and must resolve the differences themselves.
4294 The comparisons are done by calculating the MD5 message
4295 digests of the files, and storing the MD5 of the file as it
4296 was included in the most recent version of the package.
4300 When a package is installed for the first time
4301 <prgn>dpkg</prgn> will install the file that comes with it,
4302 unless that would mean overwriting a file already on the
4307 However, note that <prgn>dpkg</prgn> will <em>not</em>
4308 replace a conffile that was removed by the user (or by a
4309 script). This is necessary because with some programs a
4310 missing file produces an effect hard or impossible to
4311 achieve in another way, so that a missing file needs to be
4312 kept that way if the user did it.
4316 Note that a package should <em>not</em> modify a
4317 <prgn>dpkg</prgn>-handled conffile in its maintainer
4318 scripts. Doing this will lead to <prgn>dpkg</prgn> giving
4319 the user confusing and possibly dangerous options for
4320 conffile update when the package is upgraded.</p>
4323 <sect><heading>Fully-featured maintainer script configuration
4328 For files which contain site-specific information such as
4329 the hostname and networking details and so forth, it is
4330 better to create the file in the package's
4331 <prgn>postinst</prgn> script.
4335 This will typically involve examining the state of the rest
4336 of the system to determine values and other information, and
4337 may involve prompting the user for some information which
4338 can't be obtained some other way.
4342 When using this method there are a couple of important
4343 issues which should be considered:
4347 If you discover a bug in the program which generates the
4348 configuration file, or if the format of the file changes
4349 from one version to the next, you will have to arrange for
4350 the postinst script to do something sensible - usually this
4351 will mean editing the installed configuration file to remove
4352 the problem or change the syntax. You will have to do this
4353 very carefully, since the user may have changed the file,
4354 perhaps to fix the very problem that your script is trying
4355 to deal with - you will have to detect these situations and
4356 deal with them correctly.
4360 If you do go down this route it's probably a good idea to
4361 make the program that generates the configuration file(s) a
4362 separate program in <tt>/usr/sbin</tt>, by convention called
4363 <tt><var>package</var>config</tt> and then run that if
4364 appropriate from the post-installation script. The
4365 <tt><var>package</var>config</tt> program should not
4366 unquestioningly overwrite an existing configuration - if its
4367 mode of operation is geared towards setting up a package for
4368 the first time (rather than any arbitrary reconfiguration
4369 later) you should have it check whether the configuration
4370 already exists, and require a <tt>--force</tt> flag to
4371 overwrite it.</p></sect>
4376 <chapt id="alternatives"><heading>Alternative versions of an interface -
4377 <prgn>update-alternatives</prgn>
4381 When several packages all provide different versions of the
4382 same program or file it is useful to have the system select a
4383 default, but to allow the system administrator to change it
4384 and have their decisions respected.
4388 For example, there are several versions of the <prgn>vi</prgn>
4389 editor, and there is no reason to prevent all of them from
4390 being installed at once, each under their own name
4391 (<prgn>nvi</prgn>, <prgn>vim</prgn> or whatever).
4392 Nevertheless it is desirable to have the name <tt>vi</tt>
4393 refer to something, at least by default.
4397 If all the packages involved cooperate, this can be done with
4398 <prgn>update-alternatives</prgn>.
4402 Each package provides its own version under its own name, and
4403 calls <prgn>update-alternatives</prgn> in its postinst to
4404 register its version (and again in its prerm to deregister
4409 See the manpage <manref name="update-alternatives"
4410 section="8"> for details.
4414 If <prgn>update-alternatives</prgn> does not seem appropriate
4415 you may wish to consider using diversions instead.</p>
4419 <chapt id="diversions"><heading>Diversions - overriding a
4420 package's version of a file
4424 It is possible to have <prgn>dpkg</prgn> not overwrite a file
4425 when it reinstalls the package it belongs to, and to have it
4426 put the file from the package somewhere else instead.
4430 This can be used locally to override a package's version of a
4431 file, or by one package to override another's version (or
4432 provide a wrapper for it).
4436 Before deciding to use a diversion, read <ref
4437 id="alternatives"> to see if you really want a diversion
4438 rather than several alternative versions of a program.
4442 There is a diversion list, which is read by <prgn>dpkg</prgn>,
4443 and updated by a special program <prgn>dpkg-divert</prgn>.
4444 Please see <manref name="dpkg-divert" section="8"> for full
4445 details of its operation.
4449 When a package wishes to divert a file from another, it should
4450 call <prgn>dpkg-divert</prgn> in its preinst to add the
4451 diversion and rename the existing file. For example,
4452 supposing that a <prgn>smailwrapper</prgn> package wishes to
4453 install a wrapper around <tt>/usr/sbin/smail</tt>:
4455 if [ install = "$1" -o upgrade = "$1" ]; then
4456 dpkg-divert --package smailwrapper --add --rename \
4457 --divert /usr/sbin/smail.real /usr/sbin/smail
4459 </example> Testing <tt>$1</tt> is necessary so that the script
4460 doesn't try to add the diversion again when
4461 <prgn>smailwrapper</prgn> is upgraded. The <tt>--package
4462 smailwrapper</tt> ensures that <prgn>smailwrapper</prgn>'s
4463 copy of <tt>/usr/sbin/smail</tt> can bypass the diversion and
4464 get installed as the true version.
4468 The postrm has to do the reverse:
4470 if [ remove = "$1" ]; then
4471 dpkg-divert --package smailwrapper --remove --rename \
4472 --divert /usr/sbin/smail.real /usr/sbin/smail
4478 Do not attempt to divert a file which is vitally important for
4479 the system's operation - when using <prgn>dpkg-divert</prgn>
4480 there is a time, after it has been diverted but before
4481 <prgn>dpkg</prgn> has installed the new version, when the file
4486 <chapt id="sharedlibs"><heading>Shared libraries
4490 Packages containing shared libraries must be constructed with
4491 a little care to make sure that the shared library is always
4492 available. This is especially important for packages whose
4493 shared libraries are vitally important, such as the libc.
4497 Firstly, your package should install the shared libraries
4498 under their normal names. For example, the
4499 <prgn>libgdbm1</prgn> package should install
4500 <tt>libgdbm.so.1.7.3</tt> as
4501 <tt>/usr/lib/libgdbm.so.1.7.3</tt>. The files should not be
4502 renamed or relinked by any prerm or postrm scripts;
4503 <prgn>dpkg</prgn> will take care of renaming things safely
4504 without affecting running programs, and attempts to interfere
4505 with this are likely to lead to problems.
4509 Secondly, your package should include the symlink that
4510 <prgn>ldconfig</prgn> would create for the shared libraries.
4511 For example, the <prgn>libgdbm1</prgn> package should include
4512 a symlink from <tt>/usr/lib/libgdbm.so.1</tt> to
4513 <tt>libgdbm.so.1.7.3</tt>. This is needed so that
4514 <prgn>ld.so</prgn> can find the library in between the time
4515 <prgn>dpkg</prgn> installs it and <prgn>ldconfig</prgn> is run
4516 in the <prgn>postinst</prgn> script. Futhermore, older
4517 versions of the package management system required the library
4518 must be placed before the symlink pointing to it in the
4519 <tt>.deb</tt> file. This is so that by the time
4520 <prgn>dpkg</prgn> comes to install the symlink (overwriting
4521 the previous symlink pointing at an older version of the
4522 library) the new shared library is already in place.
4523 Unfortunately, this was not not always possible, since it
4524 highly depends on the behaviour of the filesystem. Some
4525 filesystems (such as reisefs) will reorder the files so it
4526 doesn't matter in what order you create them. In newer
4527 versions of <prgn>dpkg</prgn>, this is handled automatically.
4531 next Paragraph added to close Bug #5299, Guy Maor
4535 Thirdly, the development package should contain a symlink for
4536 the shared library without a version number. For example, the
4537 <tt>libgdbm1-dev</tt> package should include a symlink from
4538 <tt>/usr/lib/libgdm.so</tt> to <tt>libgdm.so.1.7.3</tt>. This
4539 symlink is needed by <prgn>ld</prgn> when compiling packages
4540 as it will only look for <tt>libgdm.so</tt> and
4541 <tt>libgdm.a</tt> when compiling dynamically or statically,
4546 next paragraph changed by Christian Schwarz (see policy weekly #6)
4550 Any package installing shared libraries in a directory that's listed
4551 in <tt>/etc/ld.so.conf</tt> or in one of the default library
4552 directories of <prgn>ld.so</prgn> (currently, these are <tt>/usr/lib</tt>
4553 and <tt>/lib</tt>) must call <prgn>ldconfig</prgn> in its <prgn>postinst</prgn>
4554 script if and only if the first argument is `configure'. However, it
4555 is important not to call <prgn>ldconfig</prgn> in the postrm or preinst
4556 scripts in the case where the package is being upgraded (see <ref
4557 id="unpackphase">), as <prgn>ldconfig</prgn> will see the temporary names
4558 that <prgn>dpkg</prgn> uses for the files while it is
4559 installing them and will make the shared library links point
4560 to them, just before <prgn>dpkg</prgn> continues the
4561 installation and removes the links!
4565 moved from section 2.2 , DMorris
4568 <sect id="shlibs"><heading>The <tt>shlibs</tt> File Format
4572 This file is for use by <prgn>dpkg-shlibdeps</prgn> and is
4573 required when your package provides shared libraries.
4577 Each line is of the form:
4579 <var>library-name</var> <var>version-or-soname</var> <var>dependencies ...</var>
4584 <var>library-name</var> is the name of the shared library,
4585 for example <tt>libc5</tt>.
4589 <var>version-or-soname</var> is the soname of the library -
4590 ie, the thing that must exactly match for the library to be
4591 recognised by <prgn>ld.so</prgn>. Usually this is major
4592 version number of the library.
4596 <var>dependencies</var> has the same syntax as a dependency
4597 field in a binary package control file. It should give
4598 details of which package(s) are required to satisfy a binary
4599 built against the version of the library contained in the
4600 package. See <ref id="depsyntax">.
4604 For example, if the package <tt>foo</tt> contains
4605 <tt>libfoo.so.1.2.3</tt>, where the soname of the library is
4606 <tt>libfoo.so.1</tt>, and the first version of the package
4607 which contained a minor number of at least <tt>2.3</tt> was
4608 <var>1.2.3-1</var>, then the package's <var>shlibs</var>
4611 libfoo 1 foo (>= 1.2.3-1)
4616 The version-specific dependency is to avoid warnings from
4617 <prgn>ld.so</prgn> about using older shared libraries with
4621 <sect><heading>Further Technical information on
4622 <tt>shlibs</tt></heading>
4626 following section mostly provided by Heiko Schlittermann
4630 <sect1><heading><em>What</em> are the <tt>shlibs</tt> files?
4634 The <tt>debian/shlibs</tt> file provides a way of checking
4635 for shared library dependencies on packaged binaries.
4636 They are intended to be used by package maintainers to
4637 make their lives easier.
4641 Other <tt>shlibs</tt> files that exist on a Debian system are
4643 <item> <p><tt>/etc/dpkg/shlibs.default</tt></p></item>
4644 <item> <p><tt>/etc/dpkg/shlibs.override</tt></p></item>
4645 <item> <p><tt>/var/lib/dpkg/info/*.shlibs</tt></p></item>
4646 <item> <p><tt>debian/shlibs.local</tt></p></item>
4648 These files are used by <prgn>dpkg-shlibdeps</prgn> when
4649 creating a binary package.</p>
4652 <sect1><heading><em>How</em> does <prgn>dpkg-shlibdeps</prgn>
4656 <prgn>dpkg-shlibdeps</prgn> calls <prgn>objdump</prgn> to
4657 determine the shared libraries directly
4658 <footnote> a binary <tt>foo</tt> directly use a library
4659 <tt>libbar</tt> if it is linked with that library. Other
4660 libraries that are needed by <tt>libbar</tt> are linked
4661 indirectly to <tt>foo</tt>, and the dynamic linker will load
4662 the automatically when it loads <tt>libbar</tt>.
4663 </footnote> used by the compiled binaries and libraries
4664 passed through its command line.
4668 For each shared library, <prgn>dpkg-shlibdeps</prgn> needs to know
4669 <list compact="compact">
4670 <item><p>the package containing the library, and</p></item>
4671 <item><p>the library version number,</p></item>
4674 it scans the following files in this order.
4675 <enumlist compact="compact">
4676 <item><p><tt>debian/shlibs.local</tt></p></item>
4677 <item><p><tt>/etc/dpkg/shlibs.override</tt></p></item>
4678 <item><p><tt>/var/lib/dpkg/info/*.shlibs</tt></p></item>
4679 <item><p><tt>/etc/dpkg/shlibs.default</tt></p></item>
4683 <sect1><heading><em>Who</em> maintains the various
4684 <tt>shlibs</tt> files?
4688 <list compact="compact">
4690 <p><tt>/etc/dpkg/shlibs.default</tt> - the maintainer
4695 <tt>/var/lib/dpkg/info/<var>package</var>.shlibs</tt>
4696 - the maintainer of each package</p>
4700 <tt>/etc/dpkg/shlibs.override</tt> - the local
4701 system administrator</p>
4704 <p><tt>debian/shlibs.local</tt> - the maintainer of
4709 The <tt>shlibs.default</tt> file is managed by
4710 <prgn>dpkg</prgn>. The entries in <tt>shlibs.default</tt>
4711 that are provided by <prgn>dpkg</prgn> are just there to
4712 fix things until the shared library packages all have
4713 <tt>shlibs</tt> files.
4717 <sect1><heading><em>How</em> to use <prgn>dpkg-shlibdeps</prgn> and
4718 the <tt>shlibs</tt> files?
4721 <sect2><heading>If your package doesn't provide a shared
4726 Put a call to <prgn>dpkg-shlibdeps</prgn> into your
4727 <tt>debian/rules</tt> file. If your package contains
4728 only binaries (e.g. no scripts) use:
4730 dpkg-shlibdeps debian/tmp/usr/bin/* debian/tmp/usr/sbin/*
4732 If <prgn>dpkg-shlibdeps</prgn> doesn't complain, you're
4733 done. If it does complain you might need to create your
4734 own <tt>debian/shlibs.local</tt> file.</p>
4737 <sect2><heading>If your package provides a shared library
4741 Create a <tt>debian/shlibs</tt> file and let
4742 <tt>debian/rules</tt> install it in the control area:
4744 install -m644 debian/shlibs debian/tmp/DEBIAN
4746 If your package contains additional binaries see above.
4751 <sect1><heading><em>How</em> to write
4752 <tt>debian/shlibs.local</tt>
4756 This file is intended only as a <em>temporary</em> fix if
4757 your binaries depend on a library which doesn't provide
4758 its own <tt>/var/lib/dpkg/info/*.shlibs</tt> file yet.
4762 Let's assume you are packaging a binary <tt>foo</tt>. Your
4763 output in building the package might look like this.
4766 libbar.so.1 => /usr/X11R6/lib/libbar.so.1.0
4767 libc.so.5 => /lib/libc.so.5.2.18
4768 libX11.so.6 => /usr/X11R6/lib/libX11.so.6.0
4770 And when you ran <prgn>dpkg-shlibdeps</prgn>
4772 $ dpkg-shlibdeps -o foo
4773 dpkg-shlibdeps: warning: unable to find dependency information
4774 for shared library libbar
4775 (soname 1, path /usr/X11R6/lib/libbar.so.1.0, dependency field Depends)
4776 shlibs:Depends=elf-x11r6lib, libc5 (>= 5.2.18)
4778 The <prgn>foo</prgn> binary depends on the
4779 <prgn>libbar</prgn> shared library, but no package seems
4780 to provide a <tt>*.shlibs</tt> file in
4781 <tt></tt>var/lib/dpkg/info/. Let's determine the package
4787 $ dpkg -S /usr/X11R6/lib/libbar.so.1.0
4788 bar1: /usr/X11R6/lib/libbar.so.1.0
4789 $ dpkg -s bar1 | grep Version
4792 This tells us that the <prgn>bar1</prgn> package, version
4793 1.0-1 is the one we are using. Now we can create our own
4794 <tt>debian/shlibs.local</tt> to temporarly fix the above
4795 problem. Include the following line into your
4796 <tt>debian/shlibs.local</tt> file.
4798 libbar 1 bar1 (>= 1.0-1)
4800 Now your package build should work. As soon as the
4801 maintainer of <prgn>libbar1</prgn> provides a
4802 <tt>shlibs</tt> file, you can remove your
4803 <tt>debian/shlibs.local</tt> file.
4809 <chapt id="methif"><heading><prgn>dselect</prgn>'s interface to
4810 its installation methods
4814 <prgn>dselect</prgn> calls scripts from its installation
4815 methods when it needs to actually access data from the
4816 distribution. The core program <prgn>dselect</prgn> itself
4817 just calls these scripts and provides the package and access
4818 method selection interfaces. The installation methods are
4819 responsible for invoking <prgn>dpkg</prgn> as appropriate.
4823 Each installation method has three scripts:
4824 <list compact="compact">
4825 <item><p>Setup installation parameters.</p></item>
4826 <item><p>Update list of available packages.</p></item>
4827 <item><p>Install.</p></item>
4831 <prgn>dselect</prgn> searches for methods in
4832 <tt>/usr/lib/dpkg/methods</tt> and
4833 <tt>/usr/local/lib/dpkg/methods</tt>.
4836 <sect><heading>Functions of the method scripts
4840 The setup script is run just after the user has chosen an
4841 installation method. It should prompt the user for
4842 parameters like the site to NFS-mount or FTP from, the
4843 directory to use, or the directory or filesystem where the
4844 <tt>.deb</tt> files can be found, or the tape or floppy
4845 device to install from. It should store the responses under
4846 <tt>/var/lib/dpkg/methods</tt> - see below. If no available
4847 packages list is available it should perhaps offer to scan
4848 the available packages.
4852 The update script should obtain a list of available packages
4853 if possible, and run <tt>dpkg --update-avail</tt>, <tt>dpkg
4854 --merge-avail</tt> and/or <tt>dpkg --forget-old-unavail</tt>
4855 to load it into <prgn>dpkg</prgn> and <prgn>dselect</prgn>'s
4856 database of available packages. If no packages list was
4857 available and the user was offered and accepted the option
4858 of scanning the actual files available this scan should be
4859 done here, using <tt>dpkg --record-avail</tt>.
4863 The install script should feed all the available
4864 <tt>.deb</tt> files to <tt>dpkg --iGOEB</tt> (this is
4865 equivalent to <tt>dpkg --install
4866 --refuse-downgrade --selected-only --skip-same-version
4867 --auto-deconfigure</tt>). The <tt>-R</tt>
4868 (<tt>--recursive</tt>) option for traversing subdirectories
4869 may also be useful here).
4873 If any of these scripts needs to display a message for the
4874 user, it should wait for the user to hit `return' before
4875 exiting so that dselect doesn't immediately rewrite the
4880 If a method script succeeds (returns a zero exit status)
4881 <prgn>dselect</prgn> will return immediately to the main
4882 menu, with the `next' option highlighted ready for the user
4883 to select it. If it fails <prgn>dselect</prgn> will display
4884 a message and wait for the user to hit return.</p>
4887 <sect><heading>Location and arguments of the method scripts
4891 A set of scripts (henceforth known as a group) may provide
4892 several methods on the `main menu' with different behaviour.
4893 For example, there might be a generic get-packages-by-FTP
4894 group which might provide methods in the main menu for
4895 installation directly from one of the Debian mirror sites as
4896 well as for installation from a user-specified site.
4900 Each group of methods implemented by the same set of scripts
4901 should have a subdirectory
4902 <tt>/usr/lib/dpkg/methods/<var>group</var></tt> or
4903 <tt>/usr/local/lib/dpkg/methods/<var>group</var></tt>,
4905 <taglist compact="compact">
4906 <tag><tt>names</tt></tag>
4907 <item><p>a list of user-visible methods provided by these scripts.</p>
4909 <tag><tt>setup</tt></tag>
4910 <tag><tt>update</tt></tag>
4911 <tag><tt>install</tt></tag>
4912 <item><p>executable programs, the scripts themselves.</p>
4914 <tag><tt>desc.<var>option</var></tt></tag>
4915 <item><p>description file.</p></item>
4920 <tt>names</tt> will be formatted as a list of lines, each containing:
4922 <var>sequence</var> <var>method</var> <var>summary</var>
4926 <var>sequence</var> is a two-digit number that will be used
4927 much like <tt>rc.d</tt> prefixes to control the order in the
4928 main menu. If in doubt use 50.
4932 <var>method</var> is a name which is displayed by
4933 <prgn>dselect</prgn> as the name of the method, and which
4934 will be passed to <tt>setup</tt>, <tt>update</tt> and
4935 <tt>unpack</tt> as their first argument.
4939 <var>summary</var> is the brief description string for
4940 <prgn>dselect</prgn>'s menu.
4944 Each of the three scripts gets the same three arguments:
4945 <var>vardir</var>, <var>group</var> and <var>method</var>.
4946 <var>vardir</var> is the base directory for storing
4947 <prgn>dpkg</prgn> and <prgn>dselect</prgn>'s state, usually
4948 <tt>/var/lib/dpkg</tt>; this is passed in so that the
4949 <tt>--admindir</tt> option to <prgn>dselect</prgn> is
4954 Each option may have an extended description in
4955 <tt>desc.<var>option</var></tt>. This should be formatted
4956 like the extended description part of a <tt>Description</tt>
4957 field entry <em>shifted one character to the left</em>.
4961 <tt><var>vardir</var>/methods</tt> will exist, and a method
4963 <tt><var>vardir</var>/methods/<var>group</var></tt>
4964 directory to store its state.
4968 The group name and method name must follow the rules for C
4974 <chapt id="conversion"><heading>Conversion procedure from old
4979 This is a brief summary of the procedure for converting a
4980 pre-2.0.0.0-format source package into the new format.
4984 You are strongly advised to download and examine the <prgn>hello</prgn>
4985 package, and to read the section in the <prgn>dpkg</prgn> programmers'
4986 manual describing the source packaging tools. More detail about the
4987 exact functionality of these tools is available in
4988 <manref name="dpkg-source" section="1">.
4995 Download the original source code from wherever it can
4996 be found and do any rearrangement required to make it
4997 look like the original tree of the Debian source. Put
4999 <tt><var>package</var>-<var>upstream-version</var>.orig/</tt>
5001 <tt><var>package</var>_<var>upstream-version</var>.orig.tar.gz</tt>.
5007 Rename all files <tt>debian.*</tt> to <tt>debian/*</tt>.
5008 There may be some exceptions to this, but this is a good
5014 Edit the <tt>debian/changelog</tt> - create or rename it
5015 if necessary. Add a new revision to the top with the
5016 appropriate details, and a local variables entry to the
5017 bottom to set Emacs to the right mode:
5020 mode: debian-changelog
5028 Edit/create <tt>debian/control</tt>:
5029 <list compact="compact">
5032 Remove the <tt>Version</tt> field. If it is
5033 generated unusually (not equal to the source
5034 version) you must use the -v option to
5035 dpkg-gencontrol (see below). <tt>Section</tt>,
5036 <tt>Priority</tt>, <tt>Maintainer</tt> go above
5037 the first blank line, most of the rest
5044 Reorder the fields and add a blank line at an
5045 appropriate point, separating the source package
5046 fields from the binary package fields.
5051 <p>Add the <tt>Source</tt> field.</p></item>
5055 Add the <tt>Standards-Version</tt> field. (Please
5056 check out the Debian Policy Manual for details
5057 about this field.)</p>
5062 Change the <tt>Architecture</tt> field for each
5063 package to <tt>any</tt>, <tt>all</tt> or whatever.
5064 If there isn't an <tt>Architecture</tt> field add
5070 If any other use of sed or things used to happen
5071 to make the binary control files use
5072 <prgn>dpkg-gencontrol</prgn>'s variable
5073 substitution features to achieve the same effect.
5074 Use <tt>debian/substvars</tt> if you need to put
5075 unusally-generated information (apart from details
5076 of <tt>.deb</tt> files) in the <tt>.changes</tt>
5084 <p>Edit the <tt>debian/rules</tt>:
5085 <list compact="compact">
5088 Remove the <prgn>source</prgn> and
5089 <prgn>diff</prgn> and any <prgn>changes</prgn> and
5090 <prgn>dist</prgn> targets. These things now
5091 happen in a package-independent way and are not
5092 done by <tt>debian/rules</tt>.</p>
5096 Split the <prgn>binary</prgn> target into
5097 <prgn>binary-arch</prgn> and
5098 <prgn>binary-indep</prgn>; in many cases all of
5099 <prgn>binary</prgn> should go into
5100 <prgn>binary-arch</prgn>. Create the
5101 <prgn>binary</prgn> target and the unused of the
5102 two other <prgn>binary-*</prgn> targets if there
5103 is one - you can copy the ones from the
5104 <prgn>hello</prgn> package.</p>
5108 Change the <prgn>binary</prgn> target to use
5109 <prgn>dpkg-gencontrol</prgn> to make the package
5110 control file(s). Move it to after all the files
5111 have been installed but just before the last
5112 <prgn>chown</prgn> and <prgn>chmod</prgn> in the
5117 Change occurrences of <tt>debian-tmp</tt> to
5118 <tt>debian/tmp</tt>.</p>
5122 Change occurrences of
5123 <tt>debian.{post,pre}{inst,rm}</tt> to
5124 <tt>debian/*</tt>.</p>
5128 Remove the version number setting at the top, if
5133 Ensure that the package's Debian-specific and
5134 upstream changelogs are installed.</p>
5142 Change the package to use <prgn>dpkg-shlibdeps</prgn> to
5143 determine its shared library dependencies and substitute
5144 them in. Shared library dependencies should no longer
5145 be hardwired in the source package.</p>
5150 Check that the <tt>debian/README</tt> is really the
5151 copyright file, and if so rename it to
5152 <tt>debian/copyright</tt> and edit <tt>debian/rules</tt>
5153 to cope with this and to change the installation of the
5155 <tt>/usr/doc/<var>package</var>/copyright</tt> to
5156 <tt>/usr/doc/copyright/<var>package</var></tt>. If it
5157 isn't then find <tt>debian/copyright</tt> and decide
5158 what to do with the <tt>README</tt>.</p>
5162 <p>Check for various other anachronisms and problems:
5163 <list compact="compact">
5166 Remove any <tt>Package_Revision</tt>,
5167 <tt>Package-Revision</tt> or <tt>Revision</tt>
5172 Rename <tt>Optional</tt> to <tt>Suggests</tt>,
5173 <tt>Recommended</tt> to
5174 <tt>Recommends</tt>.</p>
5179 <tt>/usr/doc/examples/<var>package</var></tt> to
5180 <tt>/usr/doc/<var>package</var>/examples</tt>.</p>
5184 Make sure that manpages are installed
5189 Check that the description has an extended
5190 description, is well-formatted and meaningful and
5191 helpful to people wanting to know whether to
5192 install a package.</p>
5199 <p>Look everything over.</p></item>
5203 Do a test build using <tt>dpkg-buildpackage -us -uc -sa
5204 -r<var>whatever</var></tt>. Check the permissions and
5205 locations of files in the resulting package by examining
5206 the output of <tt>dpkg-deb --contents</tt>, and check
5207 that the source build happened OK. Test install the
5208 binary package(s) and test extract the source
5214 Sign the release: either rebuild everything with
5215 <tt>dpkg-buildpackage -sa</tt>, or PGP-sign the
5216 <tt>.dsc</tt>, rebuild the <tt>.changes</tt> using
5217 <tt>dpkg-genchanges -sa</tt>, and then PGP-sign the
5218 <tt>.changes</tt>.</p>
5225 The use of <tt>-sa</tt> on <prgn>dpkg-buildpackage</prgn> and
5226 <prgn>dpkg-genchanges</prgn> is important when doing the first
5227 build/uploading of a new-format source package. Unless this
5228 happens to be Debian revision <tt>0</tt> or <tt>1</tt> by
5229 default the original source tarfile will not be included in
5230 the uploaded files listed in the <tt>.changes</tt> file, and
5231 so it won't be installed on the FTP site. <tt>-sa</tt>
5232 requests that the original source be included