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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: The Debian Policy group </name>
37 <email>debian-policy@lists.debian.org</email>
39 <version>version &version;, &date;</version>
42 This manual describes the technical aspects of creating Debian
43 binary and source packages. It also documents the interface
44 between <prgn>dselect</prgn> and its access method scripts.
45 It does not deal with the Debian Project policy requirements,
46 and it assumes familiarity with <prgn>dpkg</prgn>'s functions
47 from the system administrator's perspective.
50 <copyrightsummary>Copyright ©1996 Ian Jackson.</copyrightsummary>
52 This manual is free software; you may redistribute it and/or
53 modify it under the terms of the GNU General Public License
54 as published by the Free Software Foundation; either version
55 2, or (at your option) any later version.
59 This is distributed in the hope that it will be useful, but
60 <em>without any warranty</em>; without even the implied
61 warranty of merchantability or fitness for a particular
62 purpose. See the GNU General Public License for more
67 A copy of the GNU General Public License is available as
68 <tt>/usr/doc/copyright/GPL</tt> in the Debian GNU/Linux
69 distribution or on the World Wide Web at
70 <tt>http://www.gnu.org/copyleft/gpl.html</tt>. You can also
71 obtain it by writing to the Free Software Foundation, Inc.,
72 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA.
78 <!-- Describes the technical interface between a package and dpkg.
80 How to safely put shared libraries in a package. Details of
81 dpkg's handling of individual files. Sections on when to use
82 which feature (eg Replaces vs. Replaces/Conflicts
83 vs. update-alternatives vs. diversions) Cross-references to the
84 policy document (see below) where appropriate. Description of the
85 interface between dselect and its access methods. Hints on where
86 to start with a new package (ie, the hello package). What to do
91 Manpages are required for: update-rc.d, diversions,
92 update-alternatives, install-info in a package.
97 <heading>Introduction and scope of this manual</heading>
100 <prgn>dpkg</prgn> is a suite of programs for creating binary
101 package files and installing and removing them on Unix
104 <prgn>dpkg</prgn> is targetted primarily at Debian
105 GNU/Linux, but may work on or be ported to other
112 The binary packages are designed for the management of
113 installed executable programs (usually compiled binaries) and
114 their associated data, though source code examples and
115 documentation are provided as part of some packages.</p>
118 This manual describes the technical aspects of creating Debian
119 binary packages (<tt>.deb</tt> files). It documents the
120 behaviour of the package management programs
121 <prgn>dpkg</prgn>, <prgn>dselect</prgn> et al. and and the way
122 they interact with packages.</p>
125 It also documents the interaction between
126 <prgn>dselect</prgn>'s core and the access method scripts it
127 uses to actually install the selected packages, and describes
128 how to create a new access method.</p>
131 This manual does not go into detail about the options and
132 usage of the package building and installation tools. It
133 should therefore be read in conjuction with those programs'
138 The utility programs which are provided with <prgn>dpkg</prgn>
139 for managing various system configuration and similar issues,
140 such as <prgn>update-rc.d</prgn> and
141 <prgn>install-info</prgn>, are not described in detail here -
142 please see their manpages.
146 It does <em>not</em> describe the policy requirements imposed
147 on Debian packages, such as the permissions on files and
148 directories, documentation requirements, upload procedure, and
149 so on. You should see the Debian packaging policy manual for
150 these details. (Many of them will probably turn out to be
151 helpful even if you don't plan to upload your package and make
152 it available as part of the distribution.)
156 It is assumed that the reader is reasonably familiar with the
157 <prgn>dpkg</prgn> System Administrators' manual.
158 Unfortunately this manual does not yet exist.
162 The Debian version of the FSF's GNU hello program is provided
163 as an example for people wishing to create Debian
164 packages. The Debian <prgn>debmake</prgn> package is
165 recommended as a very helpful tool in creating and maintaining
166 Debian packages. However, while the tools and examples are
167 helpful, they do not replace the need to read and follow the
168 Policy and Programmer's Manual.</p>
171 <chapt id="binarypkg"><heading>Binary packages
175 The binary package has two main sections. The first part
176 consists of various control information files and scripts used
177 by <prgn>dpkg</prgn> when installing and removing. See <ref
182 The second part is an archive containing the files and
183 directories to be installed.
187 In the future binary packages may also contain other
188 components, such as checksums and digital signatures. The
189 format for the archive is described in full in the
190 <tt>deb(5)</tt> manpage.
194 <sect id="bincreating"><heading>Creating package files -
195 <prgn>dpkg-deb</prgn>
199 All manipulation of binary package files is done by
200 <prgn>dpkg-deb</prgn>; it's the only program that has
201 knowledge of the format. (<prgn>dpkg-deb</prgn> may be
202 invoked by calling <prgn>dpkg</prgn>, as <prgn>dpkg</prgn>
203 will spot that the options requested are appropriate to
204 <prgn>dpkg-deb</prgn> and invoke that instead with the same
209 In order to create a binary package you must make a
210 directory tree which contains all the files and directories
211 you want to have in the filesystem data part of the package.
212 In Debian-format source packages this directory is usually
213 <tt>debian/tmp</tt>, relative to the top of the package's
218 They should have the locations (relative to the root of the
219 directory tree you're constructing) ownerships and
220 permissions which you want them to have on the system when
225 With current versions of <prgn>dpkg</prgn> the uid/username
226 and gid/groupname mappings for the users and groups being
227 used should be the same on the system where the package is
228 built and the one where it is installed.
232 You need to add one special directory to the root of the
233 miniature filesystem tree you're creating:
234 <prgn>DEBIAN</prgn>. It should contain the control
235 information files, notably the binary package control file
236 (see <ref id="controlfile">).
240 The <prgn>DEBIAN</prgn> directory will not appear in the
241 filesystem archive of the package, and so won't be installed
242 by <prgn>dpkg</prgn> when the package is installed.
246 When you've prepared the package, you should invoke:
248 dpkg --build <var>directory</var>
253 This will build the package in
254 <tt><var>directory</var>.deb</tt>. (<prgn>dpkg</prgn> knows
255 that <tt>--build</tt> is a <prgn>dpkg-deb</prgn> option, so
256 it invokes <prgn>dpkg-deb</prgn> with the same arguments to
261 See the manpage <manref name="dpkg-deb" section="8"> for details of how
262 to examine the contents of this newly-created file. You may find the
263 output of following commands enlightening:
265 dpkg-deb --info <var>filename</var>.deb
266 dpkg-deb --contents <var>filename</var>.deb
267 dpkg --contents <var>filename</var>.deb
269 To view the copyright file for a package you could use this command:
271 dpkg --fsys-tarfile <var>filename</var>.deb | tar xof usr/doc/<var>\*</var>copyright | less
274 <sect id="controlarea">
276 Package control information files
280 The control information portion of a binary package is a
281 collection of files with names known to <prgn>dpkg</prgn>.
282 It will treat the contents of these files specially - some
283 of them contain information used by <prgn>dpkg</prgn> when
284 installing or removing the package; others are scripts which
285 the package maintainer wants <prgn>dpkg</prgn> to run.
289 It is possible to put other files in the package control
290 area, but this is not generally a good idea (though they
291 will largely be ignored).
295 Here is a brief list of the control info files supported by
296 <prgn>dpkg</prgn> and a summary of what they're used for.
301 <tag><tt>control</tt>
305 This is the key description file used by
306 <prgn>dpkg</prgn>. It specifies the package's name
307 and version, gives its description for the user,
308 states its relationships with other packages, and so
309 forth. See <ref id="controlfile">.
313 It is usually generated automatically from information
314 in the source package by the
315 <prgn>dpkg-gencontrol</prgn> program, and with
316 assistance from <prgn>dpkg-shlibdeps</prgn>. See <ref
317 id="sourcetools">.</p>
320 <tag><tt>postinst</tt>, <tt>preinst</tt>, <tt>postrm</tt>,
326 These are exectuable files (usually scripts) which
327 <prgn>dpkg</prgn> runs during installation, upgrade
328 and removal of packages. They allow the package to
329 deal with matters which are particular to that package
330 or require more complicated processing than that
331 provided by <prgn>dpkg</prgn>. Details of when and
332 how they are called are in <ref
333 id="maintainerscripts">.
337 It is very important to make these scripts
341 That means that if it runs successfully or fails
342 and then you call it again it doesn't bomb out,
343 but just ensures that everything is the way it
346 </footnote> This is so that if an error occurs, the
347 user interrupts <prgn>dpkg</prgn> or some other
348 unforeseen circumstance happens you don't leave the
349 user with a badly-broken package.
353 The maintainer scripts are guaranteed to run with a
354 controlling terminal and can interact with the user.
355 If they need to prompt for passwords, do full-screen
356 interaction or something similar you should do these
357 things to and from <tt>/dev/tty</tt>, since
358 <prgn>dpkg</prgn> will at some point redirect scripts'
359 standard input and output so that it can log the
360 installation process. Likewise, because these scripts
361 may be executed with standard output redirected into a
362 pipe for logging purposes, Perl scripts should set
363 unbuffered output by setting <tt>$|=1</tt> so that the
364 output is printed immediately rather than being
369 Each script should return a zero exit status for
370 success, or a nonzero one for failure.</p>
373 <tag><tt>conffiles</tt>
378 This file contains a list of configuration files which
379 are to be handled automatically by <prgn>dpkg</prgn>
380 (see <ref id="conffiles">). Note that not necessarily
381 every configuration file should be listed here.</p>
389 This file contains a list of the shared libraries
390 supplied by the package, with dependency details for
391 each. This is used by <prgn>dpkg-shlibdeps</prgn>
392 when it determines what dependencies are required in a
393 package control file. The <tt>shlibs</tt> file format
394 is described on <ref id="shlibs">.
400 <sect id="controlfile">
402 The main control information file: <tt>control</tt>
405 The most important control information file used by
406 <prgn>dpkg</prgn> when it installs a package is
407 <tt>control</tt>. It contains all the package's `vital
412 The binary package control files of packages built from
413 Debian sources are made by a special tool,
414 <prgn>dpkg-gencontrol</prgn>, which reads
415 <tt>debian/control</tt> and <tt>debian/changelog</tt> to
416 find the information it needs. See <ref id="sourcepkg"> for
421 The fields in binary package control files are:
422 <list compact="compact">
424 <p><qref id="f-Package"><tt>Package</tt></qref> (mandatory)</p>
427 <p><qref id="versions"><tt>Version</tt></qref> (mandatory)</p>
429 <item><p><qref id="f-Architecture"><tt>Architecture</tt></qref>
433 This field should appear in all packages, though
434 <prgn>dpkg</prgn> doesn't require it yet so that
435 old packages can still be installed.
441 <p><qref id="relationships"><tt>Depends</tt>,
442 <tt>Provides</tt> et al.</qref></p>
445 <p><qref id="f-Essential"><tt>Essential</tt></qref></p>
448 <p><qref id="f-Maintainer"><tt>Maintainer</tt></qref></p>
451 <p><qref id="f-classification"><tt>Section</tt>,
452 <tt>Priority</tt></qref></p>
455 <p><qref id="f-Source"><tt>Source</tt></qref></p>
458 <p><qref id="descriptions"><tt>Description</tt></qref></p>
462 <qref id="f-Installed-Size"><tt>Installed-Size</tt></qref>
468 A description of the syntax of control files and the purpose
469 of these fields is available in <ref id="controlfields">.
473 <heading>Time Stamps</heading>
475 Maintainers are encouraged to preserve the modification
476 times of the upstream source files in a package, as far as
477 is reasonably possible.
480 The rationale is that there is some information conveyed
481 by knowing the age of the file, for example, you could
482 recognize that some documentation is very old by looking
483 at the modification time, so it would be nice if the
484 modification time of the upstream source would be
491 <chapt id="sourcepkg">
492 <heading>Source packages</heading>
495 The Debian binary packages in the distribution are generated
496 from Debian sources, which are in a special format to assist
497 the easy and automatic building of binaries.
501 There was a previous version of the Debian source format,
502 which is now being phased out. Instructions for converting an
503 old-style package are given in the Debian policy manual.
506 <sect id="sourcetools">
507 <heading>Tools for processing source packages</heading>
510 Various tools are provided for manipulating source packages;
511 they pack and unpack sources and help build of binary
512 packages and help manage the distribution of new versions.
516 They are introduced and typical uses described here; see
517 <manref name="dpkg-source" section="1"> for full
518 documentation about their arguments and operation.
522 For examples of how to construct a Debian source package,
523 and how to use those utilities that are used by Debian
524 source packages, please see the <prgn>hello</prgn> example
530 <prgn>dpkg-source</prgn> - packs and unpacks Debian source
535 This program is frequently used by hand, and is also
536 called from package-independent automated building scripts
537 such as <prgn>dpkg-buildpackage</prgn>.
541 To unpack a package it is typically invoked with
543 dpkg-source -x <var>.../path/to/filename</var>.dsc
548 with the <tt><var>filename</var>.tar.gz</tt> and
549 <tt><var>filename</var>.diff.gz</tt> (if applicable) in
550 the same directory. It unpacks into
551 <tt><var>package</var>-<var>version</var></tt>, and if
553 <tt><var>package</var>-<var>version</var>.orig</tt>, in
554 the current directory.
558 To create a packed source archive it is typically invoked:
560 dpkg-source -b <var>package</var>-<var>version</var>
565 This will create the <tt>.dsc</tt>, <tt>.tar.gz</tt> and
566 <tt>.diff.gz</tt> (if appropriate) in the current
567 directory. <prgn>dpkg-source</prgn> does not clean the
568 source tree first - this must be done separately if it is
573 See also <ref id="sourcearchives">.</p>
579 <prgn>dpkg-buildpackage</prgn> - overall package-building
584 <prgn>dpkg-buildpackage</prgn> is a script which invokes
585 <prgn>dpkg-source</prgn>, the <tt>debian/rules</tt>
586 targets <prgn>clean</prgn>, <prgn>build</prgn> and
587 <prgn>binary</prgn>, <prgn>dpkg-genchanges</prgn> and
588 <prgn>pgp</prgn> to build a signed source and binary
593 It is usually invoked by hand from the top level of the
594 built or unbuilt source directory. It may be invoked with
595 no arguments; useful arguments include:
596 <taglist compact="compact">
597 <tag><tt>-uc</tt>, <tt>-us</tt></tag>
600 Do not PGP-sign the <tt>.changes</tt> file or the
601 source package <tt>.dsc</tt> file, respectively.</p>
603 <tag><tt>-p<var>pgp-command</var></tt></tag>
606 Invoke <var>pgp-command</var> instead of finding
607 <tt>pgp</tt> on the <prgn>PATH</prgn>.
608 <var>pgp-command</var> must behave just like
609 <prgn>pgp</prgn>.</p>
611 <tag><tt>-r<var>root-command</var></tt></tag>
614 When root privilege is required, invoke the command
615 <var>root-command</var>. <var>root-command</var>
616 should invoke its first argument as a command, from
617 the <prgn>PATH</prgn> if necessary, and pass its
618 second and subsequent arguments to the command it
619 calls. If no <var>root-command</var> is supplied
620 then <var>dpkg-buildpackage</var> will take no
621 special action to gain root privilege, so that for
622 most packages it will have to be invoked as root to
625 <tag><tt>-b</tt>, <tt>-B</tt></tag>
628 Two types of binary-only build and upload - see
629 <manref name="dpkg-source" section="1">.
638 <prgn>dpkg-gencontrol</prgn> - generates binary package
643 This program is usually called from <tt>debian/rules</tt>
644 (see <ref id="sourcetree">) in the top level of the source
649 This is usually done just before the files and directories in the
650 temporary directory tree where the package is being built have their
651 permissions and ownerships set and the package is constructed using
652 <prgn>dpkg-deb/</prgn>
655 This is so that the control file which is produced has
656 the right permissions
662 <prgn>dpkg-gencontrol</prgn> must be called after all the
663 files which are to go into the package have been placed in
664 the temporary build directory, so that its calculation of
665 the installed size of a package is correct.
669 It is also necessary for <prgn>dpkg-gencontrol</prgn> to
670 be run after <prgn>dpkg-shlibdeps</prgn> so that the
671 variable substitutions created by
672 <prgn>dpkg-shlibdeps</prgn> in <tt>debian/substvars</tt>
677 For a package which generates only one binary package, and
678 which builds it in <tt>debian/tmp</tt> relative to the top
679 of the source package, it is usually sufficient to call:
686 Sources which build several binaries will typically need
689 dpkg-gencontrol -Pdebian/tmp-<var>pkg</var> -p<var>package</var>
690 </example> The <tt>-P</tt> tells
691 <prgn>dpkg-gencontrol</prgn> that the package is being
692 built in a non-default directory, and the <tt>-p</tt>
693 tells it which package's control file should be generated.
697 <prgn>dpkg-gencontrol</prgn> also adds information to the
698 list of files in <tt>debian/files</tt>, for the benefit of
699 (for example) a future invocation of
700 <prgn>dpkg-genchanges</prgn>.</p>
705 <prgn>dpkg-shlibdeps</prgn> - calculates shared library
710 This program is usually called from <tt>debian/rules</tt>
711 just before <prgn>dpkg-gencontrol</prgn> (see <ref
712 id="sourcetree">), in the top level of the source tree.
716 Its arguments are executables
719 They may be specified either in the locations in the
720 source tree where they are created or in the locations
721 in the temporary build tree where they are installed
722 prior to binary package creation.
724 </footnote> for which shared library dependencies should
725 be included in the binary package's control file.
729 If some of the executable(s) shared libraries should only
730 warrant a <tt>Recommends</tt> or <tt>Suggests</tt>, or if
731 some warrant a <tt>Pre-Depends</tt>, this can be achieved
732 by using the <tt>-d<var>dependency-field</var></tt> option
733 before those executable(s). (Each <tt>-d</tt> option
734 takes effect until the next <tt>-d</tt>.)
738 <prgn>dpkg-shlibdeps</prgn> does not directly cause the
739 output control file to be modified. Instead by default it
740 adds to the <tt>debian/substvars</tt> file variable
741 settings like <tt>shlibs:Depends</tt>. These variable
742 settings must be referenced in dependency fields in the
743 appropriate per-binary-package sections of the source
748 For example, the <prgn>procps</prgn> package generates two
749 kinds of binaries, simple C binaries like <prgn>ps</prgn>
750 which require a predependency and full-screen ncurses
751 binaries like <prgn>top</prgn> which require only a
752 recommendation. It can say in its <tt>debian/rules</tt>:
754 dpkg-shlibdeps -dPre-Depends ps -dRecommends top
756 and then in its main control file <tt>debian/control</tt>:
760 Pre-Depends: ${shlibs:Pre-Depends}
761 Recommends: ${shlibs:Recommends}
767 Sources which produce several binary packages with
768 different shared library dependency requirements can use
769 the <tt>-p<var>varnameprefix</var></tt> option to override
770 the default <tt>shlib:</tt> prefix (one invocation of
771 <prgn>dpkg-shlibdeps</prgn> per setting of this option).
772 They can thus produce several sets of dependency
773 variables, each of the form
774 <tt><var>varnameprefix</var>:<var>dependencyfield</var></tt>,
775 which can be referred to in the appropriate parts of the
776 binary package control files.
783 <prgn>dpkg-distaddfile</prgn> - adds a file to
784 <tt>debian/files</tt>
788 Some packages' uploads need to include files other than
789 the source and binary package files.
793 <prgn>dpkg-distaddfile</prgn> adds a file to the
794 <tt>debian/files</tt> file so that it will be included in
795 the <tt>.changes</tt> file when
796 <prgn>dpkg-genchanges</prgn> is run.
800 It is usually invoked from the <prgn>binary</prgn> target of
801 <tt>debian/rules</tt>:
803 dpkg-distaddfile <var>filename</var> <var>section</var> <var>priority</var>
805 The <var>filename</var> is relative to the directory where
806 <prgn>dpkg-genchanges</prgn> will expect to find it - this
807 is usually the directory above the top level of the source
808 tree. The <tt>debian/rules</tt> target should put the
809 file there just before or just after calling
810 <prgn>dpkg-distaddfile</prgn>.
814 The <var>section</var> and <var>priority</var> are passed
815 unchanged into the resulting <tt>.changes</tt> file. See
816 <ref id="f-classification">.
821 <sect1><heading><prgn>dpkg-genchanges</prgn> - generates a <tt>.changes</tt> upload
826 This program is usually called by package-independent
827 automatic building scripts such as
828 <prgn>dpkg-buildpackage</prgn>, but it may also be called
833 It is usually called in the top level of a built source
834 tree, and when invoked with no arguments will print out a
835 straightforward <tt>.changes</tt> file based on the
836 information in the source package's changelog and control
837 file and the binary and source packages which should have
843 <sect1><heading><prgn>dpkg-parsechangelog</prgn> - produces parsed representation of
848 This program is used internally by
849 <prgn>dpkg-source</prgn> et al. It may also occasionally
850 be useful in <tt>debian/rules</tt> and elsewhere. It
851 parses a changelog, <tt>debian/changelog</tt> by default,
852 and prints a control-file format representation of the
853 information in it to standard output.
858 <sect id="sourcetree"><heading>The Debianised source tree
862 The source archive scheme described later is intended to
863 allow a Debianised source tree with some associated control
864 information to be reproduced and transported easily. The
865 Debianised source tree is a version of the original program
866 with certain files added for the benefit of the
867 Debianisation process, and with any other changes required
868 made to the rest of the source code and installation
873 The extra files created for Debian are in the subdirectory
874 <tt>debian</tt> of the top level of the Debianised source
875 tree. They are described below.
878 <sect1><heading><tt>debian/rules</tt> - the main building
883 This file is an executable makefile, and contains the
884 package-specific recipies for compiling the package and
885 building binary package(s) out of the source.
889 It must start with the line <tt>#!/usr/bin/make -f</tt>,
890 so that it can be invoked by saying its name rather than
891 invoking <prgn>make</prgn> explicitly.
895 Since an interactive <tt>debian/rules</tt> script makes it
896 impossible to autocompile that package and also makes it
897 hard for other people to reproduce the same binary
898 package, all <strong>required targets</strong> have to be
899 non-interactive. At a minimul, required targets are the
900 ones called by <prgn>dpkg-buildpackage</prgn>, namely,
901 <em>clean</em>, <em>binary</em>, <em>binary-arch</em>, and
902 <em>build</em>. It also follows that any target that these
903 targets depend on must also be non-interactive.
907 The targets which are required to be present are:
909 <tag><tt>build</tt></tag>
912 This should perform all non-interactive
913 configuration and compilation of the package. If a
914 package has an interactive pre-build configuration
915 routine, the Debianised source package should be
916 built after this has taken place, so that it can be
917 built without rerunning the configuration.
921 For some packages, notably ones where the same
922 source tree is compiled in different ways to produce
923 two binary packages, the <prgn>build</prgn> target
924 does not make much sense. For these packages it is
925 good enough to provide two (or more) targets
926 (<tt>build-a</tt> and <tt>build-b</tt> or whatever)
927 for each of the ways of building the package, and a
928 <prgn>build</prgn> target that does nothing. The
929 <prgn>binary</prgn> target will have to build the
930 package in each of the possible ways and make the
931 binary package out of each.
935 The <prgn>build</prgn> target must not do anything
936 that might require root privilege.
940 The <prgn>build</prgn> target may need to run
941 <prgn>clean</prgn> first - see below.
945 When a package has a configuration routine that
946 takes a long time, or when the makefiles are poorly
947 designed, or when <prgn>build</prgn> needs to run
948 <prgn>clean</prgn> first, it is a good idea to
949 <tt>touch build</tt> when the build process is
950 complete. This will ensure that if <tt>debian/rules
951 build</tt> is run again it will not rebuild the
956 <tag><tt>binary</tt>, <tt>binary-arch</tt>,
957 <tt>binary-indep</tt>
961 The <prgn>binary</prgn> target should be all that is
962 necessary for the user to build the binary
963 package. All these targets are required to be
964 non-interactive. It is split into two parts:
965 <prgn>binary-arch</prgn> builds the packages' output
966 files which are specific to a particular
967 architecture, and <prgn>binary-indep</prgn> builds
972 <prgn>binary</prgn> should usually be a target with
973 no commands which simply depends on
974 <prgn>binary-arch</prgn> and
975 <prgn>binary-indep</prgn>.
979 Both <prgn>binary-*</prgn> targets should depend on
980 the <prgn>build</prgn> target, above, so that the
981 package is built if it has not been already. It
982 should then create the relevant binary package(s),
983 using <prgn>dpkg-gencontrol</prgn> to make their
984 control files and <prgn>dpkg-deb</prgn> to build
985 them and place them in the parent of the top level
990 If one of the <prgn>binary-*</prgn> targets has
991 nothing to do (this will be always be the case if
992 the source generates only a single binary package,
993 whether architecture-dependent or not) it
994 <em>must</em> still exist, but should always
999 <ref id="binarypkg"> describes how to construct
1004 The <prgn>binary</prgn> targets must be invoked as
1009 <tag><tt>clean</tt></tag>
1013 This should undo any effects that the
1014 <prgn>build</prgn> and <prgn>binary</prgn> targets
1015 may have had, except that it should leave alone any
1016 output files created in the parent directory by a
1017 run of <prgn>binary</prgn>. This target is required
1018 to be non-interactive.
1022 If a <prgn>build</prgn> file is touched at the end
1023 of the <prgn>build</prgn> target, as suggested
1024 above, it must be removed as the first thing that
1025 <prgn>clean</prgn> does, so that running
1026 <prgn>build</prgn> again after an interrupted
1027 <prgn>clean</prgn> doesn't think that everything is
1032 The <prgn>clean</prgn> target must be invoked as
1033 root if <prgn>binary</prgn> has been invoked since
1034 the last <prgn>clean</prgn>, or if
1035 <prgn>build</prgn> has been invoked as root (since
1036 <prgn>build</prgn> may create directories, for
1041 <tag><tt>get-orig-source</tt> (optional)</tag>
1045 This target fetches the most recent version of the
1046 original source package from a canonical archive
1047 site (via FTP or WWW, for example), does any
1048 necessary rearrangement to turn it into the original
1049 source tarfile format described below, and leaves it
1050 in the current directory.
1054 This target may be invoked in any directory, and
1055 should take care to clean up any temporary files it
1060 This target is optional, but providing it if
1061 possible is a good idea.
1067 The <prgn>build</prgn>, <prgn>binary</prgn> and
1068 <prgn>clean</prgn> targets must be invoked with a current
1069 directory of the package's top-level directory.
1074 Additional targets may exist in <tt>debian/rules</tt>,
1075 either as published or undocumented interfaces or for the
1076 package's internal use.
1081 <sect1><heading><tt>debian/control</tt>
1085 This file contains version-independent details about the
1086 source package and about the binary packages it creates.
1090 It is a series of sets of control fields, each
1091 syntactically similar to a binary package control file.
1092 The sets are separated by one or more blank lines. The
1093 first set is information about the source package in
1094 general; each subsequent set describes one binary package
1095 that the source tree builds.
1099 The syntax and semantics of the fields are described below
1100 in <ref id="controlfields">.
1104 The general (binary-package-independent) fields are:
1105 <list compact="compact">
1107 <p><qref id="f-Source"><tt>Source</tt></qref> (mandatory)</p>
1110 <p><qref id="f-Maintainer"><tt>Maintainer</tt></qref></p>
1114 <qref id="f-classification"><tt>Section</tt> and
1115 <tt>Priority</tt></qref>
1116 (classification, mandatory)
1121 <qref id="f-Standards-Version"><tt>Standards-Version</tt></qref>
1127 The per-binary-package fields are:
1128 <list compact="compact">
1130 <p><qref id="f-Package"><tt>Package</tt></qref> (mandatory)</p>
1134 <qref id="f-Architecture"><tt>Architecture</tt></qref>
1138 <p><qref id="descriptions"><tt>Description</tt></qref></p>
1142 <qref id="f-classification"><tt>Section</tt> and
1143 <tt>Priority</tt></qref> (classification)</p>
1146 <p><qref id="f-Essential"><tt>Essential</tt></qref></p>
1150 <qref id="relationships"><tt>Depends</tt> et
1151 al.</qref> (package interrelationships)
1157 These fields are used by <prgn>dpkg-gencontrol</prgn> to
1158 generate control files for binary packages (see below), by
1159 <prgn>dpkg-genchanges</prgn> to generate the
1160 <tt>.changes</tt> file to accompany the upload, and by
1161 <prgn>dpkg-source</prgn> when it creates the <tt>.dsc</tt>
1162 source control file as part of a source archive.
1166 The fields here may contain variable references - their
1167 values will be substituted by
1168 <prgn>dpkg-gencontrol</prgn>, <prgn>dpkg-genchanges</prgn>
1169 or <prgn>dpkg-source</prgn> when they generate output
1170 control files. See <ref id="srcsubstvars"> for details.
1173 <p> <sect2><heading>User-defined fields
1177 Additional user-defined fields may be added to the
1178 source package control file. Such fields will be
1179 ignored, and not copied to (for example) binary or
1180 source package control files or upload control files.
1184 If you wish to add additional unsupported fields to
1185 these output files you should use the mechanism
1190 Fields in the main source control information file with
1191 names starting <tt>X</tt>, followed by one or more of
1192 the letters <tt>BCS</tt> and a hyphen <tt>-</tt>, will
1193 be copied to the output files. Only the part of the
1194 field name after the hyphen will be used in the output
1195 file. Where the letter <tt>B</tt> is used the field
1196 will appear in binary package control files, where the
1197 letter <tt>S</tt> is used in source package control
1198 files and where <tt>C</tt> is used in upload control
1199 (<tt>.changes</tt>) files.
1203 For example, if the main source information control file
1206 XBS-Comment: I stand between the candle and the star.
1208 then the binary and source package control files will contain the
1211 Comment: I stand between the candle and the star.
1218 <sect1 id="dpkgchangelog"><heading><tt>debian/changelog</tt>
1222 This file records the changes to the Debian-specific parts of the
1226 Though there is nothing stopping an author who is also
1227 the Debian maintainer from using it for all their
1228 changes, it will have to be renamed if the Debian and
1229 upstream maintainers become different
1236 It has a special format which allows the package building
1237 tools to discover which version of the package is being
1238 built and find out other release-specific information.
1242 That format is a series of entries like this:
1244 <var>package</var> (<var>version</var>) <var>distribution(s)</var>;
1245 urgency=<var>urgency</var>
1247 * <var>change details</var>
1248 <var>more change details</var>
1249 * <var>even more change details</var>
1251 -- <var>maintainer name and email address</var> <var>date</var>
1256 <var>package</var> and <var>version</var> are the source
1257 package name and version number.
1261 <var>distribution(s)</var> lists the distributions where
1262 this version should be installed when it is uploaded - it
1263 is copied to the <tt>Distribution</tt> field in the
1264 <tt>.changes</tt> file. See <ref id="f-Distribution">.
1268 <var>urgency</var> is the value for the <tt>Urgency</tt>
1269 field in the <tt>.changes</tt> file for the upload. See
1270 <ref id="f-Urgency">. It is not possible to specify an
1271 urgency containing commas; commas are used to separate
1272 <tt><var>keyword</var>=<var>value</var></tt> settings in
1273 the <prgn>dpkg</prgn> changelog format (though there is
1274 currently only one useful <var>keyword</var>,
1279 The change details may in fact be any series of lines
1280 starting with at least two spaces, but conventionally each
1281 change starts with an asterisk and a separating space and
1282 continuation lines are indented so as to bring them in
1283 line with the start of the text above. Blank lines may be
1284 used here to separate groups of changes, if desired.
1288 The maintainer name and email address should <em>not</em>
1289 necessarily be those of the usual package maintainer.
1290 They should be the details of the person doing
1291 <em>this</em> version. The information here will be
1292 copied to the <tt>.changes</tt> file, and then later used
1293 to send an acknowledgement when the upload has been
1298 The <var>date</var> should be in RFC822 format
1301 This is generated by the <prgn>822-date</prgn>
1304 </footnote>; it should include the timezone specified
1305 numerically, with the timezone name or abbreviation
1306 optionally present as a comment.
1310 The first `title' line with the package name should start
1311 at the left hand margin; the `trailer' line with the
1312 maintainer and date details should be preceded by exactly
1313 one space. The maintainer details and the date must be
1314 separated by exactly two spaces.
1318 An Emacs mode for editing this format is available: it is
1319 called <tt>debian-changelog-mode</tt>. You can have this
1320 mode selected automatically when you edit a Debian
1321 changelog by adding a local variables clause to the end of
1325 <sect2><heading>Defining alternative changelog formats
1329 It is possible to use a different format to the standard
1330 one, by providing a parser for the format you wish to
1335 In order to have <tt>dpkg-parsechangelog</tt> run your
1336 parser, you must include a line within the last 40 lines
1337 of your file matching the Perl regular expression:
1338 <tt>\schangelog-format:\s+([0-9a-z]+)\W</tt> The part in
1339 parentheses should be the name of the format. For
1340 example, you might say:
1342 @@@ changelog-format: joebloggs @@@
1344 Changelog format names are non-empty strings of alphanumerics.
1348 If such a line exists then <tt>dpkg-parsechangelog</tt>
1349 will look for the parser as
1350 <tt>/usr/lib/dpkg/parsechangelog/<var>format-name</var></tt>
1352 <tt>/usr/local/lib/dpkg/parsechangelog/<var>format-name</var></tt>;
1353 it is an error for it not to find it, or for it not to
1354 be an executable program. The default changelog format
1355 is <tt>dpkg</tt>, and a parser for it is provided with
1356 the <tt>dpkg</tt> package.
1360 The parser will be invoked with the changelog open on
1361 standard input at the start of the file. It should read
1362 the file (it may seek if it wishes) to determine the
1363 information required and return the parsed information
1364 to standard output in the form of a series of control
1365 fields in the standard format. By default it should
1366 return information about only the most recent version in
1367 the changelog; it should accept a
1368 <tt>-v<var>version</var></tt> option to return changes
1369 information from all versions present <em>strictly
1370 after</em> <var>version</var>, and it should then be an
1371 error for <var>version</var> not to be present in the
1377 <list compact="compact">
1379 <p><qref id="f-Source"><tt>Source</tt></qref></p>
1382 <p><qref id="versions"><tt>Version</tt></qref> (mandatory)</p>
1386 <qref id="f-Distribution"><tt>Distribution</tt></qref>
1391 <p><qref id="f-Urgency"><tt>Urgency</tt></qref> (mandatory)</p>
1395 <qref id="f-Maintainer"><tt>Maintainer</tt></qref>
1400 <p><qref id="f-Date"><tt>Date</tt></qref></p>
1404 <qref id="f-Changes"><tt>Changes</tt></qref>
1411 If several versions are being returned (due to the use
1412 of <tt>-v</tt>), the urgency value should be of the
1413 highest urgency code listed at the start of any of the
1414 versions requested followed by the concatenated
1415 (space-separated) comments from all the versions
1416 requested; the maintainer, version, distribution and
1417 date should always be from the most recent version.
1421 For the format of the <tt>Changes</tt> field see <ref
1426 If the changelog format which is being parsed always or
1427 almost always leaves a blank line between individual
1428 change notes these blank lines should be stripped out,
1429 so as to make the resulting output compact.
1433 If the changelog format does not contain date or package
1434 name information this information should be omitted from
1435 the output. The parser should not attempt to synthesise
1436 it or find it from other sources.
1440 If the changelog does not have the expected format the
1441 parser should exit with a nonzero exit status, rather
1442 than trying to muddle through and possibly generating
1447 A changelog parser may not interact with the user at
1451 <sect1 id="srcsubstvars"><heading><tt>debian/substvars</tt>
1452 and variable substitutions
1456 When <prgn>dpkg-gencontrol</prgn>,
1457 <prgn>dpkg-genchanges</prgn> and <prgn>dpkg-source</prgn>
1458 generate control files they do variable substitutions on
1459 their output just before writing it. Variable
1460 substitutions have the form
1461 <tt>${<var>variable-name</var>}</tt>. The optional file
1462 <tt>debian/substvars</tt> contains variable substitutions
1463 to be used; variables can also be set directly from
1464 <tt>debian/rules</tt> using the <tt>-V</tt> option to the
1465 source packaging commands, and certain predefined
1466 variables are available.
1470 The is usually generated and modified dynamically by
1471 <tt>debian/rules</tt> targets; in this case it must be
1472 removed by the <prgn>clean</prgn> target.
1476 See <manref name="dpkg-source" section="1"> for full
1477 details about source variable substitutions, including the
1478 format of <tt>debian/substvars</tt>.</p>
1481 <sect1><heading><tt>debian/files</tt>
1485 This file is not a permanent part of the source tree; it
1486 is used while building packages to record which files are
1487 being generated. <prgn>dpkg-genchanges</prgn> uses it
1488 when it generates a <tt>.changes</tt> file.
1492 It should not exist in a shipped source package, and so it
1493 (and any backup files or temporary files such as
1497 <tt>files.new</tt> is used as a temporary file by
1498 <prgn>dpkg-gencontrol</prgn> and
1499 <prgn>dpkg-distaddfile</prgn> - they write a new
1500 version of <tt>files</tt> here before renaming it,
1501 to avoid leaving a corrupted copy if an error
1504 </footnote>) should be removed by the
1505 <prgn>clean</prgn> target. It may also be wise to
1506 ensure a fresh start by emptying or removing it at the
1507 start of the <prgn>binary</prgn> target.
1511 <prgn>dpkg-gencontrol</prgn> adds an entry to this file
1512 for the <tt>.deb</tt> file that will be created by
1513 <prgn>dpkg-deb</prgn> from the control file that it
1514 generates, so for most packages all that needs to be done
1515 with this file is to delete it in <prgn>clean</prgn>.
1519 If a package upload includes files besides the source
1520 package and any binary packages whose control files were
1521 made with <prgn>dpkg-gencontrol</prgn> then they should be
1522 placed in the parent of the package's top-level directory
1523 and <prgn>dpkg-distaddfile</prgn> should be called to add
1524 the file to the list in <tt>debian/files</tt>.</p>
1527 <sect1><heading><tt>debian/tmp</tt>
1531 This is the canonical temporary location for the
1532 construction of binary packages by the <prgn>binary</prgn>
1533 target. The directory <tt>tmp</tt> serves as the root of
1534 the filesystem tree as it is being constructed (for
1535 example, by using the package's upstream makefiles install
1536 targets and redirecting the output there), and it also
1537 contains the <tt>DEBIAN</tt> subdirectory. See <ref
1542 If several binary packages are generated from the same
1543 source tree it is usual to use several
1544 <tt>debian/tmp<var>something</var></tt> directories, for
1545 example <tt>tmp-a</tt> or <tt>tmp-doc</tt>.
1549 Whatever <tt>tmp</tt> directories are created and used by
1550 <prgn>binary</prgn> must of course be removed by the
1551 <prgn>clean</prgn> target.</p></sect1>
1555 <sect id="sourcearchives"><heading>Source packages as archives
1559 As it exists on the FTP site, a Debian source package
1560 consists of three related files. You must have the right
1561 versions of all three to be able to use them.
1566 <tag>Debian source control file - <tt>.dsc</tt></tag>
1570 This file contains a series of fields, identified and
1571 separated just like the fields in the control file of
1572 a binary package. The fields are listed below; their
1573 syntax is described above, in <ref id="controlfields">.
1574 <list compact="compact">
1576 <p><qref id="f-Source"><tt>Source</tt></qref></p>
1579 <p><qref id="versions"><tt>Version</tt></qref></p>
1582 <p><qref id="f-Maintainer"><tt>Maintainer</tt></qref></p>
1585 <p><qref id="f-Binary"><tt>Binary</tt></qref></p>
1588 <p><qref id="f-Architecture"><tt>Architecture</tt></qref></p>
1592 <qref id="f-Standards-Version"><tt>Standards-Version</tt></qref></p>
1595 <p><qref id="f-Files"><tt>Files</tt></qref></p>
1600 The source package control file is generated by
1601 <prgn>dpkg-source</prgn> when it builds the source
1602 archive, from other files in the source package,
1603 described above. When unpacking it is checked against
1604 the files and directories in the other parts of the
1605 source package, as described below.</p>
1609 Original source archive -
1611 <var>package</var>_<var>upstream-version</var>.orig.tar.gz
1618 This is a compressed (with <tt>gzip -9</tt>)
1619 <prgn>tar</prgn> file containing the source code from
1620 the upstream authors of the program. The tarfile
1621 unpacks into a directory
1622 <tt><var>package</var>-<var>upstream-version</var>.orig</tt>,
1623 and does not contain files anywhere other than in
1624 there or in its subdirectories.</p>
1628 Debianisation diff -
1630 <var>package</var>_<var>upstream_version-revision</var>.diff.gz
1636 This is a unified context diff (<tt>diff -u</tt>)
1637 giving the changes which are required to turn the
1638 original source into the Debian source. These changes
1639 may only include editing and creating plain files.
1640 The permissions of files, the targets of symbolic
1641 links and the characteristics of special files or
1642 pipes may not be changed and no files may be removed
1647 All the directories in the diff must exist, except the
1648 <tt>debian</tt> subdirectory of the top of the source
1649 tree, which will be created by
1650 <prgn>dpkg-source</prgn> if necessary when unpacking.
1654 The <prgn>dpkg-source</prgn> program will
1655 automatically make the <tt>debian/rules</tt> file
1656 executable (see below).</p></item>
1661 If there is no original source code - for example, if the
1662 package is specially prepared for Debian or the Debian
1663 maintainer is the same as the upstream maintainer - the
1664 format is slightly different: then there is no diff, and the
1666 <tt><var>package</var>_<var>version</var>.tar.gz</tt> and
1667 contains a directory
1668 <tt><var>package</var>-<var>version</var></tt>.
1672 <sect><heading>Unpacking a Debian source package without
1673 <prgn>dpkg-source</prgn>
1677 <tt>dpkg-source -x</tt> is the recommended way to unpack a
1678 Debian source package. However, if it is not available it
1679 is possible to unpack a Debian source archive as follows:
1680 <enumlist compact="compact">
1683 Untar the tarfile, which will create a <tt>.orig</tt>
1687 <p>Rename the <tt>.orig</tt> directory to
1688 <tt><var>package</var>-<var>version</var></tt>.</p>
1692 Create the subdirectory <tt>debian</tt> at the top of
1693 the source tree.</p>
1695 <item><p>Apply the diff using <tt>patch -p0</tt>.</p>
1697 <item><p>Untar the tarfile again if you want a copy of the original
1698 source code alongside the Debianised version.</p>
1703 It is not possible to generate a valid Debian source archive
1704 without using <prgn>dpkg-source</prgn>. In particular,
1705 attempting to use <prgn>diff</prgn> directly to generate the
1706 <tt>.diff.gz</tt> file will not work.
1709 <sect1><heading>Restrictions on objects in source packages
1713 The source package may not contain any hard links
1716 This is not currently detected when building source
1717 packages, but only when extracting
1723 Hard links may be permitted at some point in the
1724 future, but would require a fair amount of
1727 </footnote>, device special files, sockets or setuid or
1731 Setgid directories are allowed.
1737 The source packaging tools manage the changes between the
1738 original and Debianised source using <prgn>diff</prgn> and
1739 <prgn>patch</prgn>. Turning the original source tree as
1740 included in the <tt>.orig.tar.gz</tt> into the debianised
1741 source must not involve any changes which cannot be
1742 handled by these tools. Problematic changes which cause
1743 <prgn>dpkg-source</prgn> to halt with an error when
1744 building the source package are:
1745 <list compact="compact">
1746 <item><p>Adding or removing symbolic links, sockets or pipes.</p>
1748 <item><p>Changing the targets of symbolic links.</p>
1750 <item><p>Creating directories, other than <tt>debian</tt>.</p>
1752 <item><p>Changes to the contents of binary files.</p></item>
1753 </list> Changes which cause <prgn>dpkg-source</prgn> to
1754 print a warning but continue anyway are:
1755 <list compact="compact">
1758 Removing files, directories or symlinks.
1761 Renaming a file is not treated specially - it is
1762 seen as the removal of the old file (which
1763 generates a warning, but is otherwise ignored),
1764 and the creation of the new
1771 Changed text files which are missing the usual final
1772 newline (either in the original or the modified
1777 Changes which are not represented, but which are not detected by
1778 <prgn>dpkg-source</prgn>, are:
1779 <list compact="compact">
1780 <item><p>Changing the permissions of files (other than
1781 <tt>debian/rules</tt>) and directories.</p></item>
1786 The <tt>debian</tt> directory and <tt>debian/rules</tt>
1787 are handled specially by <prgn>dpkg-source</prgn> - before
1788 applying the changes it will create the <tt>debian</tt>
1789 directory, and afterwards it will make
1790 <tt>debian/rules</tt> world-exectuable.
1796 <chapt id="controlfields"><heading>Control files and their fields
1800 Many of the tools in the <prgn>dpkg</prgn> suite manipulate
1801 data in a common format, known as control files. Binary and
1802 source packages have control data as do the <tt>.changes</tt>
1803 files which control the installation of uploaded files, and
1804 <prgn>dpkg</prgn>'s internal databases are in a similar
1808 <sect><heading>Syntax of control files
1812 A file consists of one or more paragraphs of fields. The
1813 paragraphs are separated by blank lines. Some control files
1814 only allow one paragraph; others allow several, in which
1815 case each paragraph often refers to a different package.
1819 Each paragraph is a series of fields and values; each field
1820 consists of a name, followed by a colon and the value. It
1821 ends at the end of the line. Horizontal whitespace (spaces
1822 and tabs) may occur before or after the value and is ignored
1823 there; it is conventional to put a single space after the
1828 Some fields' values may span several lines; in this case
1829 each continuation line <em>must</em> start with a space or
1830 tab. Any trailing spaces or tabs at the end of individual
1831 lines of a field value are ignored.
1835 Except where otherwise stated only a single line of data is
1836 allowed and whitespace is not significant in a field body.
1837 Whitespace may never appear inside names (of packages,
1838 architectures, files or anything else), version numbers or
1839 in between the characters of multi-character version
1844 Field names are not case-sensitive, but it is usual to
1845 capitalise the fields using mixed case as shown below.
1849 Blank lines, or lines consisting only of spaces and tabs,
1850 are not allowed within field values or between fields - that
1851 would mean a new paragraph.
1855 It is important to note that there are several fields which
1856 are optional as far as <prgn>dpkg</prgn> and the related
1857 tools are concerned, but which must appear in every Debian
1858 package, or whose omission may cause problems. When writing
1859 the control files for Debian packages you <em>must</em> read
1860 the Debian policy manual in conjuction with the details
1861 below and the list of fields for the particular file.</p>
1864 <sect><heading>List of fields
1867 <sect1 id="f-Package"><heading><tt>Package</tt>
1871 The name of the binary package. Package names consist of
1872 the alphanumerics and <tt>+</tt> <tt>-</tt> <tt>.</tt>
1873 (plus, minus and full stop).
1876 The characters <tt>@</tt> <tt>:</tt> <tt>=</tt>
1877 <tt>t</tt>t> <tt>_</tt> (at, colon, equals, percent
1878 and underscore) used to be legal and are still
1879 accepted when found in a package file, but may not be
1880 used in new packages
1886 They must be at least two characters and must start with
1887 an alphanumeric. In current versions of dpkg they are
1888 sort of case-sensitive<footnote><p>This is a
1889 bug.</p></footnote>; use lowercase package names unless
1890 the package you're building (or referring to, in other
1891 fields) is already using uppercase.</p>
1894 <sect1 id="f-Version"><heading><tt>Version</tt>
1898 This lists the source or binary package's version number -
1899 see <ref id="versions">.
1904 <sect1 id="f-Architecture"><heading><tt>Architecture</tt>
1908 This is the architecture string; it is a single word for
1909 the CPU architecture.
1913 <prgn>dpkg</prgn> will check the declared architecture of
1914 a binary package against its own compiled-in value before
1919 The special value <tt>all</tt> indicates that the package
1920 is architecture-independent.
1924 In the main <tt>debian/control</tt> file in the source
1925 package, or in the source package control file
1926 <tt>.dsc</tt>, a list of architectures (separated by
1927 spaces) is also allowed, as is the special value
1928 <tt>any</tt>. A list indicates that the source will build
1929 an architecture-dependent package, and will only work
1930 correctly on the listed architectures. <tt>any</tt>
1931 indicates that though the source package isn't dependent
1932 on any particular architecture and should compile fine on
1933 any one, the binary package(s) produced are not
1934 architecture-independent but will instead be specific to
1935 whatever the current build architecture is.
1939 In a <tt>.changes</tt> file the <tt>Architecture</tt>
1940 field lists the architecture(s) of the package(s)
1941 currently being uploaded. This will be a list; if the
1942 source for the package is being uploaded too the special
1943 entry <tt>source</tt> is also present.
1947 The current build architecture can be determined using <tt>dpkg
1948 --print-architecture</tt>.
1951 This actually invokes
1953 gcc --print-libgcc-file-name
1954 </example> and parses and decomposes the output and
1955 looks the CPU type from the GCC configuration in a
1956 table in <prgn>dpkg</prgn>. This is so that it will
1957 work if you're cross-compiling.
1959 </footnote> This value is automatically used by
1960 <prgn>dpkg-gencontrol</prgn> when building the control
1961 file for a binary package for which the source control
1962 information doesn't specify architecture <tt>all</tt>.
1966 There is a separate option,
1967 <tt>--print-installation-architecture</tt>, for finding
1968 out what architecture <prgn>dpkg</prgn> is willing to
1969 install. This information is also in the output of
1970 <tt>dpkg --version</tt>.</p>
1973 <sect1 id="f-Maintainer"><heading><tt>Maintainer</tt>
1977 The package maintainer's name and email address. The name
1978 should come first, then the email address inside angle
1979 brackets <tt><></tt> (in RFC822 format).
1983 If the maintainer's name contains a full stop then the
1984 whole field will not work directly as an email address due
1985 to a misfeature in the syntax specified in RFC822; a
1986 program using this field as an address must check for this
1987 and correct the problem if necessary (for example by
1988 putting the name in round brackets and moving it to the
1989 end, and bringing the email address forward).
1993 In a <tt>.changes</tt> file or parsed changelog data this
1994 contains the name and email address of the person
1995 responsible for the particular version in question - this
1996 may not be the package's usual maintainer.
2000 This field is usually optional in as far as the
2001 <prgn>dpkg</prgn> are concerned, but its absence when
2002 building packages usually generates a warning.</p>
2005 <sect1 id="f-Source"><heading><tt>Source</tt>
2009 This field identifies the source package name.
2013 In a main source control information or a
2014 <tt>.changes</tt> or <tt>.dsc</tt> file or parsed
2015 changelog data this may contain only the name of the
2020 In the control file of a binary package (or in a
2021 <tt>Packages</tt> file) it may be followed by a version
2022 number in parentheses.
2025 It is usual to leave a space after the package name if
2026 a version number is specified.
2028 </footnote> This version number may be omitted (and is, by
2029 <prgn>dpkg-gencontrol</prgn>) if it has the same value as
2030 the <tt>Version</tt> field of the binary package in
2031 question. The field itself may be omitted from a binary
2032 package control file when the source package has the same
2033 name and version as the binary package.
2037 <sect1><heading>Package interrelationship fields:
2038 <tt>Depends</tt>, <tt>Pre-Depends</tt>,
2039 <tt>Recommends</tt> <tt>Suggests</tt>, <tt>Conflicts</tt>,
2040 <tt>Provides</tt>, <tt>Replaces</tt>
2044 These fields describe the package's relationships with
2045 other packages. Their syntax and semantics are described
2046 in <ref id="relationships">.</p>
2049 <sect1 id="f-Description"><heading><tt>Description</tt>
2053 In a binary package <tt>Packages</tt> file or main source
2054 control file this field contains a description of the
2055 binary package, in a special format. See <ref
2056 id="descriptions"> for details.
2060 In a <tt>.changes</tt> file it contains a summary of the
2061 descriptions for the packages being uploaded. The part of
2062 the field before the first newline is empty; thereafter
2063 each line has the name of a binary package and the summary
2064 description line from that binary package. Each line is
2065 indented by one space.</p>
2068 <sect1 id="f-Essential"><heading><tt>Essential</tt>
2072 This is a boolean field which may occur only in the
2073 control file of a binary package (or in the
2074 <tt>Packages</tt> file) or in a per-package fields
2075 paragraph of a main source control data file.
2079 If set to <tt>yes</tt> then <prgn>dpkg</prgn> and
2080 <prgn>dselect</prgn> will refuse to remove the package
2081 (though it can be upgraded and/or replaced). The other
2082 possible value is <tt>no</tt>, which is the same as not
2083 having the field at all.</p>
2086 <sect1 id="f-classification"><heading><tt>Section</tt> and
2091 These two fields classify the package. The
2092 <tt>Priority</tt> represents how important that it is that
2093 the user have it installed; the <tt>Section</tt>
2094 represents an application area into which the package has
2099 When they appear in the <tt>debian/control</tt> file these
2100 fields give values for the section and priority subfields
2101 of the <tt>Files</tt> field of the <tt>.changes</tt> file,
2102 and give defaults for the section and priority of the
2107 The section and priority are represented, though not as
2108 separate fields, in the information for each file in the
2109 <qref id="f-Files"><tt>-File</tt></qref>field of a
2110 <tt>.changes</tt> file. The section value in a
2111 <tt>.changes</tt> file is used to decide where to install
2112 a package in the FTP archive.
2116 These fields are not used by by <prgn>dpkg</prgn> proper,
2117 but by <prgn>dselect</prgn> when it sorts packages and
2118 selects defaults. See the Debian policy manual for the
2119 priorities in use and the criteria for selecting the
2120 priority for a Debian package, and look at the Debian FTP
2121 archive for a list of currently in-use priorities.
2125 These fields may appear in binary package control files,
2126 in which case they provide a default value in case the
2127 <tt>Packages</tt> files are missing the information.
2128 <prgn>dpkg</prgn> and <prgn>dselect</prgn> will only use
2129 the value from a <tt>.deb</tt> file if they have no other
2130 information; a value listed in a <tt>Packages</tt> file
2131 will always take precedence. By default
2132 <prgn>dpkg-genchanges</prgn> does not include the section
2133 and priority in the control file of a binary package - use
2134 the <tt>-isp</tt>, <tt>-is</tt> or <tt>-ip</tt> options to
2135 achieve this effect.</p>
2138 <sect1 id="f-Binary"><heading><tt>Binary</tt>
2142 This field is a list of binary packages.
2146 When it appears in the <tt>.dsc</tt> file it is the list
2147 of binary packages which a source package can produce. It
2148 does not necessarily produce all of these binary packages
2149 for every architecture. The source control file doesn't
2150 contain details of which architectures are appropriate for
2151 which of the binary packages.
2155 When it appears in a <tt>.changes</tt> file it lists the
2156 names of the binary packages actually being uploaded.
2160 The syntax is a list of binary packages separated by
2164 A space after each comma is conventional.
2166 </footnote> Currently the packages must be separated using
2167 only spaces in the <tt>.changes</tt> file.</p>
2170 <sect1 id="f-Installed-Size"><heading><tt>Installed-Size</tt>
2174 This field appears in the control files of binary
2175 packages, and in the <tt>Packages</tt> files. It gives
2176 the total amount of disk space required to install the
2181 The disk space is represented in kilobytes as a simple
2185 <sect1 id="f-Files"><heading><tt>Files</tt>
2189 This field contains a list of files with information about
2190 each one. The exact information and syntax varies with
2191 the context. In all cases the the part of the field
2192 contents on the same line as the field name is empty. The
2193 remainder of the field is one line per file, each line
2194 being indented by one space and containing a number of
2195 sub-fields separated by spaces.
2199 In the <tt>.dsc</tt> (Debian source control) file each
2200 line contains the MD5 checksum, size and filename of the
2201 tarfile and (if applicable) diff file which make up the
2202 remainder of the source package.
2205 That is, the parts which are not the
2208 </footnote> The exact forms of the filenames are described
2209 in <ref id="sourcearchives">.
2213 In the <tt>.changes</tt> file this contains one line per
2214 file being uploaded. Each line contains the MD5 checksum,
2215 size, section and priority and the filename. The section
2216 and priority are the values of the corresponding fields in
2217 the main source control file - see <ref
2218 id="f-classification">. If no section or priority is
2219 specified then <tt>-</tt> should be used, though section
2220 and priority values must be specified for new packages to
2221 be installed properly.
2225 The special value <tt>byhand</tt> for the section in a
2226 <tt>.changes</tt> file indicates that the file in question
2227 is not an ordinary package file and must by installed by
2228 hand by the distribution maintainers. If the section is
2229 <tt>byhand</tt> the priority should be <tt>-</tt>.
2233 If a new Debian revision of a package is being shipped and
2234 no new original source archive is being distributed the
2235 <tt>.dsc</tt> must still contain the <tt>Files</tt> field
2236 entry for the original source archive
2237 <tt><var>package</var>-<var>upstream-version</var>.orig.tar.gz</tt>,
2238 but the <tt>.changes</tt> file should leave it out. In
2239 this case the original source archive on the distribution
2240 site must match exactly, byte-for-byte, the original
2241 source archive which was used to generate the
2242 <tt>.dsc</tt> file and diff which are being uploaded.</p>
2247 id="f-Standards-Version"><heading><tt>Standards-Version</tt>
2251 The most recent version of the standards (the
2252 <prgn>dpkg</prgn> programmers' and policy manuals and
2253 associated texts) with which the package complies. This
2254 is updated manually when editing the source package to
2255 conform to newer standards; it can sometimes be used to
2256 tell when a package needs attention.
2260 Its format is the same as that of a version number except
2261 that no epoch or Debian revision is allowed - see <ref
2266 <sect1 id="f-Distribution"><heading><tt>Distribution</tt>
2270 In a <tt>.changes</tt> file or parsed changelog output
2271 this contains the (space-separated) name(s) of the
2272 distribution(s) where this version of the package should
2273 be or was installed. Distribution names follow the rules
2274 for package names. (See <ref id="f-Package">).
2278 Current distribution values are:
2280 <tag><em>stable</em></tag>
2283 This is the current `released' version of Debian
2284 GNU/Linux. A new version is released approximately
2285 every 3 months after the <em>development</em> code has
2286 been <em>frozen</em> for a month of testing. Once the
2287 distribution is <em>stable</em> only major bug fixes
2288 are allowed. When changes are made to this
2289 distribution, the minor version number is increased
2290 (for example: 1.2 becomes 1.2.1 then 1.2.2, etc).
2294 <tag><em>unstable</em></tag>
2297 This distribution value refers to the
2298 <em>developmental</em> part of the Debian distribution
2299 tree. New packages, new upstream versions of packages
2300 and bug fixes go into the <em>unstable</em> directory
2301 tree. Download from this distribution at your own
2305 <tag><em>contrib</em></tag>
2308 The packages with this distribution value do not meet
2309 the criteria for inclusion in the main Debian
2310 distribution as defined by the Policy Manual, but meet
2311 the criteria for the <em>contrib</em>
2312 Distribution. There is currently no distinction
2313 between stable and unstable packages in the
2314 <em>contrib</em> or <em>non-free</em>
2315 distributions. Use your best judgement in downloading
2316 from this Distribution.</p>
2319 <tag><em>non-free</em></tag>
2322 Like the packages in the <em>contrib</em> seciton,
2323 the packages in <em>non-free</em> do not meet the
2324 criteria for inclusion in the main Debian distribution
2325 as defined by the Policy Manual. Again, use your best
2326 judgement in downloading from this Distribution.</p>
2328 <tag><em>experimental</em></tag>
2331 The packages with this distribution value are deemed
2332 by their maintainers to be high risk. Oftentimes they
2333 represent early beta or developmental packages from
2334 various sources that the maintainers want people to
2335 try, but are not ready to be a part of the other parts
2336 of the Debian distribution tree. Download at your own
2340 <tag><em>frozen</em></tag>
2343 From time to time, (currently, every 3 months) the
2344 <em>unstable</em> distribution enters a state of
2345 `code-freeze' in anticipation of release as a
2346 <em>stable</em> version. During this period of testing
2347 (usually 4 weeks) only fixes for existing or
2348 newly-discovered bugs will be allowed.
2351 </taglist> You should list <em>all</em> distributions that
2352 the package should be installed into. Except in unusual
2353 circumstances, installations to <em>stable</em> should also
2354 go into <em>frozen</em> (if it exists) and
2355 <em>unstable</em>. Likewise, installations into
2356 <em>frozen</em> should also go into <em>unstable</em>.</p>
2359 <sect1 id="f-Urgency"><heading><tt>Urgency</tt>
2363 This is a description of how important it is to upgrade to
2364 this version from previous ones. It consists of a single
2365 keyword usually taking one of the values <tt>LOW</tt>,
2366 <tt>MEDIUM</tt> or <tt>HIGH</tt>) followed by an optional
2367 commentary (separated by a space) which is usually in
2368 parentheses. For example:
2370 Urgency: LOW (HIGH for diversions users)
2375 This field appears in the <tt>.changes</tt> file and in
2376 parsed changelogs; its value appears as the value of the
2377 <tt>urgency</tt> attribute in a <prgn>dpkg</prgn>-style
2378 changelog (see <ref id="dpkgchangelog">).
2382 Urgency keywords are not case-sensitive.</p>
2385 <sect1 id="f-Date"><heading><tt>Date</tt>
2389 In <tt>.changes</tt> files and parsed changelogs, this
2390 gives the date the package was built or last edited.</p>
2393 <sect1 id="f-Format"><heading><tt>Format</tt>
2397 This field occurs in <tt>.changes</tt> files, and
2398 specifies a format revision for the file. The format
2399 described here is version <tt>1.5</tt>. The syntax of the
2400 format value is the same as that of a package version
2401 number except that no epoch or Debian revision is allowed
2402 - see <ref id="versions">.</p>
2405 <sect1 id="f-Changes"><heading><tt>Changes</tt>
2409 In a <tt>.changes</tt> file or parsed changelog this field
2410 contains the human-readable changes data, describing the
2411 differences between the last version and the current one.
2415 There should be nothing in this field before the first
2416 newline; all the subsequent lines must be indented by at
2417 least one space; blank lines must be represented by a line
2418 consiting only of a space and a full stop.
2422 Each version's change information should be preceded by a
2423 `title' line giving at least the version, distribution(s)
2424 and urgency, in a human-readable way.
2428 If data from several versions is being returned the entry
2429 for the most recent version should be returned first, and
2430 entries should be separated by the representation of a
2431 blank line (the `title' line may also be followed by the
2432 representation of blank line).</p>
2435 <sect1 id="f-Filename"><heading><tt>Filename</tt> and
2436 <tt>MSDOS-Filename</tt>
2440 These fields in <tt>Packages</tt> files give the
2441 filename(s) of (the parts of) a package in the
2442 distribution directories, relative to the root of the
2443 Debian hierarchy. If the package has been split into
2444 several parts the parts are all listed in order, separated
2448 <sect1 id="f-Size"><heading><tt>Size</tt> and <tt>MD5sum</tt>
2452 These fields in <tt>Packages</tt> files give the size (in
2453 bytes, expressed in decimal) and MD5 checksum of the
2454 file(s) which make(s) up a binary package in the
2455 distribution. If the package is split into several parts
2456 the values for the parts are listed in order, separated by
2460 <sect1 id="f-Status"><heading><tt>Status</tt>
2464 This field in <prgn>dpkg</prgn>'s status file records
2465 whether the user wants a package installed, removed or
2466 left alone, whether it is broken (requiring
2467 reinstallation) or not and what its current state on the
2468 system is. Each of these pieces of information is a
2472 <sect1 id="f-Config-Version"><heading><tt>Config-Version</tt>
2476 If a package is not installed or not configured, this
2477 field in <prgn>dpkg</prgn>'s status file records the last
2478 version of the package which was successfully
2482 <sect1 id="f-Conffiles"><heading><tt>Conffiles</tt>
2486 This field in <prgn>dpkg</prgn>'s status file contains
2487 information about the automatically-managed configuration
2488 files held by a package. This field should <em>not</em>
2489 appear anywhere in a package!</p>
2492 <sect1><heading>Obsolete fields
2496 These are still recognised by <prgn>dpkg</prgn> but should
2497 not appear anywhere any more.
2498 <taglist compact="compact">
2500 <tag><tt>Revision</tt></tag>
2501 <tag><tt>Package-Revision</tt></tag>
2502 <tag><tt>Package_Revision</tt></tag>
2505 The Debian revision part of the package version was
2506 at one point in a separate control file field. This
2507 field went through several names.</p>
2510 <tag><tt>Recommended</tt></tag>
2511 <item><p>Old name for <tt>Recommends</tt></p>
2514 <tag><tt>Optional</tt></tag>
2515 <item><p>Old name for <tt>Suggests</tt>.</p>
2517 <tag><tt>Class</tt></tag>
2518 <item><p>Old name for <tt>Priority</tt>.</p>
2526 <chapt id="versions"><heading>Version numbering
2530 Every package has a version number, in its <tt>Version</tt>
2535 <prgn>dpkg</prgn> imposes an ordering on version numbers, so
2536 that it can tell whether packages are being up- or downgraded
2537 and so that <prgn>dselect</prgn> can tell whether a package it
2538 finds available is newer than the one installed on the system.
2539 The version number format has the most significant parts (as
2540 far as comparison is concerned) at the beginning.
2544 The version number format is:
2545 &lsqb<var>epoch/<tt>:</tt>]<var>upstream-version</var>[<tt>-/<var>debian-revision</var>].</tt></var>
2549 The three components here are:
2551 <tag><var>epoch</var></tag>
2555 This is a single unsigned integer, which should usually
2556 be small. It may be omitted, in which case zero is
2557 assumed. If it is omitted then the
2558 <var>upstream-version</var> may not contain any colons.
2562 It is provided to allow mistakes in the version numbers
2563 of older versions of a package, and also a package's
2564 previous version numbering schemes, to be left behind.
2568 <prgn>dpkg</prgn> will not usually display the epoch
2569 unless it is essential (non-zero, or if the
2570 <var>upstream-version</var> contains a colon);
2571 <prgn>dselect</prgn> does not display epochs at all in
2572 the main part of the package selection display.</p>
2575 <tag><var>upstream-version</var></tag>
2579 This is the main part of the version. It is usually
2580 version number of the original (`upstream') package of
2581 which the <tt>.deb</tt> file has been made, if this is
2582 applicable. Usually this will be in the same format as
2583 that specified by the upstream author(s); however, it
2584 may need to be reformatted to fit into
2585 <prgn>dpkg</prgn>'s format and comparison scheme.
2589 The comparison behaviour of <prgn>dpkg</prgn> with
2590 respect to the <var>upstream-version</var> is described
2591 below. The <var>upstream-version</var> portion of the
2592 version number is mandatory.
2596 The <var>upstream-version</var> may contain only
2597 alphanumerics and the characters <tt>+</tt> <tt>.</tt>
2598 <tt>-</tt> <tt>:</tt> (full stop, plus, hyphen, colon)
2599 and should start with a digit. If there is no
2600 <var>debian-revision</var> then hyphens are not allowed;
2601 if there is no <var>epoch</var> then colons are not
2605 <tag><var>debian-revision</var></tag>
2609 This part of the version represents the version of the
2610 modifications that were made to the package to make it a
2611 Debian binary package. It is in the same format as the
2612 <var>upstream-version</var> and <prgn>dpkg</prgn>
2613 compares it in the same way.
2617 It is optional; if it isn't present then the
2618 <var>upstream-version</var> may not contain a hyphen.
2619 This format represents the case where a piece of
2620 software was written specifically to be turned into a
2621 Debian binary package, and so there is only one
2622 `debianization' of it and therefore no revision
2623 indication is required.
2627 It is conventional to restart the
2628 <var>debian-revision</var> at <tt>1</tt> each time the
2629 <var>upstream-version</var> is increased.
2633 <prgn>dpkg</prgn> will break the
2634 <var>upstream-version</var> and
2635 <var>debian-revision</var> apart at the last hyphen in
2636 the string. The absence of a <var>debian-revision</var>
2637 compares earlier than the presence of one (but note that
2638 the <var>debian-revision</var> is the least significant
2639 part of the version number).
2643 The <var>debian-revision</var> may contain only
2644 alphanumerics and the characters <tt>+</tt> and
2645 <tt>.</tt> (plus and full stop).
2649 The <var>upstream-version</var> and <var>debian-revision</var> parts are
2650 compared by <prgn>dpkg</prgn> using the same algorithm:
2654 The strings are compared from left to right.
2658 First the initial part of each string consisting entirely of
2659 non-digit characters is determined. These two parts (one of
2660 which may be empty) are compared lexically. If a difference
2661 is found it is returned. The lexical comparison is a
2662 comparison of ASCII values modified so that all the letters
2663 sort earlier than all the non-letters.
2667 Then the initial part of the remainder of each string which
2668 consists entirely of digit characters is determined. The
2669 numerical values of these two parts are compared, and any
2670 difference found is returned as the result of the comparison.
2671 For these purposes an empty string (which can only occur at
2672 the end of one or both version strings being compared) counts
2677 These two steps are repeated (chopping initial non-digit
2678 strings and initial digit strings off from the start) until a
2679 difference is found or both strings are exhausted.
2683 Note that the purpose of epochs is to allow us to leave behind
2684 mistakes in version numbering, and to cope with situations
2685 where the version numbering changes. It is <em>not</em> there
2686 to cope with version numbers containing strings of letters
2687 which <prgn>dpkg</prgn> cannot interpret (such as
2688 <tt>ALPHA</tt> or <tt>pre-</tt>), or with silly orderings (the
2689 author of this manual has heard of a package whose versions
2690 went <tt>1.1</tt>, <tt>1.2</tt>, <tt>1.3</tt>, <tt>1</tt>,
2691 <tt>2.1</tt>, <tt>2.2</tt>, <tt>2</tt> and so forth).
2695 If an upstream package has problematic version numbers they
2696 should be converted to a sane form for use in the
2697 <tt>Version</tt> field.
2701 If you need to compare version numbers in a script, you may use
2702 <tt>dpkg --compare-versions ...</tt>. Type <tt>dpkg
2703 --help</tt> --> --for details on arguments.
2707 <chapt id="maintainerscripts"><heading>Package maintainer scripts
2708 and installation procedure
2711 <sect><heading>Introduction to package maintainer scripts
2715 It is possible supply scripts as part of a package which
2716 <prgn>dpkg</prgn> will run for you when your package is
2717 installed, upgraded or removed.
2721 These scripts should be the files <tt>preinst</tt>,
2722 <tt>postinst</tt>, <tt>prerm</tt> and <tt>postrm</tt> in the
2723 control area of the package. They must be proper exectuable
2724 files; if they are scripts (which is recommended) they must
2725 start with the usual <tt>#!</tt> convention. They should be
2726 readable and executable to anyone, and not world-writeable.
2730 <prgn>dpkg</prgn> looks at the exit status from these
2731 scripts. It is important that they exit with a non-zero
2732 status if there is an error, so that <prgn>dpkg</prgn> can
2733 stop its processing. For shell scripts this means that you
2734 <em>almost always</em> need to use <tt>set -e</tt> (this is
2735 usually true when writing shell scripts, in fact). It is
2736 also important, of course, that they don't exit with a
2737 non-zero status if everything went well.
2741 It is necessary for the error recovery procedures that the
2742 scripts be idempotent: ie, invoking the same script several
2743 times in the same situation should do no harm. If the first
2744 call failed, or aborted half way through for some reason,
2745 the second call should merely do the things that were left
2746 undone the first time, if any, and exit with a success
2751 When a package is upgraded a combination of the scripts from
2752 the old and new packages is called in amongst the other
2753 steps of the upgrade procedure. If your scripts are going
2754 to be at all complicated you need to be aware of this, and
2755 may need to check the arguments to your scripts.
2759 Broadly speaking the <prgn>preinst</prgn> is called before
2760 (a particular version of) a package is installed, and the
2761 <prgn>postinst</prgn> afterwards; the <prgn>prerm</prgn>
2762 before (a version of) a package is removed and the
2763 <prgn>postrm</prgn> afterwards.
2766 next paragraph by Guy Maor to close bug #2481
2769 <p> Programs called from maintainer scripts should not
2770 normally have a path prepended to them. Before installation
2771 is started <prgn>dpkg</prgn> checks to see if the programs
2772 <prgn>ldconfig</prgn>, <prgn>start-stop-daemon</prgn>,
2773 <prgn>install-info</prgn>, and <prgn>update-rc.d</prgn> can
2774 be found via the <tt>PATH</tt> environment variable. Those
2775 programs, and any other program that one would expect to on
2776 the <tt>PATH</tt>, should thus be invoked without an
2777 absolute pathname. Maintainer scripts should also not reset
2778 the <tt>PATH</tt>, though they might choose to modify it by
2779 pre- or appending package-specific directories. These
2780 considerations really apply to all shell scripts.</p>
2783 <sect id="mscriptsinstact"><heading>Summary of ways maintainer
2788 <list compact="compact">
2790 <p><var>new-preinst</var> <tt>install</tt></p>
2793 <p><var>new-preinst</var> <tt>install</tt>
2794 <var>old-version</var></p>
2797 <p><var>new-preinst</var> <tt>upgrade</tt>
2798 <var>old-version</var></p>
2801 <p><var>old-preinst</var> <tt>abort-upgrade</tt>
2802 <var>new-version</var>
2808 <list compact="compact">
2810 <p><var>postinst</var> <tt>configure</tt>
2811 <var>most-recently-configured-version</var></p>
2814 <p><var>old-postinst</var> <tt>abort-upgrade</tt>
2815 <var>new version</var></p>
2818 <p><var>conflictor's-postinst</var> <tt>abort-remove</tt>
2819 <tt>in-favour</tt> <var>package</var>
2820 <var>new-version</var></p>
2824 <var>deconfigured's-postinst</var>
2825 <tt>abort-deconfigure</tt> <tt>in-favour</tt>
2826 <var>failed-install-package</var> <var>version</var>
2827 <tt>removing</tt> <var>conflicting-package</var>
2834 <list compact="compact">
2836 <p><var>prerm</var> <tt>remove</tt></p>
2839 <p><var>old-prerm</var> <tt>upgrade</tt>
2840 <var>new-version</var></p>
2843 <p><var>new-prerm</var> <tt>failed-upgrade</tt>
2844 <var>old-version</var></p>
2847 <p><var>conflictor's-prerm</var> <tt>remove</tt>
2848 <tt>in-favour</tt> <var>package</var>
2849 <var>new-version</var></p>
2853 <var>deconfigured's-prerm</var> <tt>deconfigure</tt>
2854 <tt>in-favour</tt> <var>package-being-installed</var>
2855 <var>version</var> <tt>removing</tt>
2856 <var>conflicting-package</var>
2863 <list compact="compact">
2865 <p><var>postrm</var> <tt>remove</tt></p>
2868 <p><var>postrm</var> <tt>purge</tt></p>
2872 <var>old-postrm</var> <tt>upgrade</tt>
2873 <var>new-version</var></p>
2876 <p><var>new-postrm</var> <tt>failed-upgrade</tt>
2877 <var>old-version</var></p>
2880 <p><var>new-postrm</var> <tt>abort-install</tt></p>
2883 <p><var>new-postrm</var> <tt>abort-install</tt>
2884 <var>old-version</var></p>
2887 <p><var>new-postrm</var> <tt>abort-upgrade</tt>
2888 <var>old-version</var></p>
2892 <var>disappearer's-postrm</var> <tt>disappear</tt>
2893 <var>r>overwrit</var>r>
2894 <var>new-version</var></p></item>
2899 <sect id="unpackphase"><heading>Details of unpack phase of
2900 installation or upgrade
2904 The procedure on installation/upgrade/overwrite/disappear
2905 (ie, when running <tt>dpkg --unpack</tt>, or the unpack
2907 --install</tt>) is as follows. In each case if an error occurs the
2908 actions in are general run backwards - this means that the maintainer
2909 scripts are run with different arguments in reverse order. These are
2910 the `error unwind' calls listed below.
2917 <p>If a version the package is already
2920 <var>old-prerm</var> upgrade <var>new-version</var>
2925 If this gives an error (ie, a non-zero exit
2926 status), dpkg will attempt instead:
2928 <var>new-prerm</var> failed-upgrade <var>old-version</var>
2930 Error unwind, for both the above cases:
2932 <var>old-postinst</var> abort-upgrade <var>new-version</var>
2940 <p>If a `conflicting' package is being removed at the same time:
2944 If any packages depended on that conflicting
2945 package and <tt>--auto-deconfigure</tt> is
2946 specified, call, for each such package:
2948 <var>deconfigured's-prerm</var> deconfigure \
2949 in-favour <var>package-being-installed</var> <var>version</var> \
2950 removing <var>conflicting-package</var> <var>version</var>
2954 <var>deconfigured's-postinst</var> abort-deconfigure \
2955 in-favour <var>package-being-installed-but-failed</var> <var>version</var> \
2956 removing <var>conflicting-package</var> <var>version</var>
2958 The deconfigured packages are marked as
2959 requiring configuration, so that if
2960 <tt>--install</tt> is used they will be
2961 configured again if possible.</p>
2964 <p>To prepare for removal of the conflicting package, call:
2966 <var>conflictor's-prerm</var> remove in-favour <var>package</var> <var>new-version</var>
2970 <var>conflictor's-postinst</var> abort-remove \
2971 in-favour <var>package</var> <var>new-version</var>
2982 <p>If the package is being upgraded, call:
2984 <var>new-preinst</var> upgrade <var>old-version</var>
2989 Otherwise, if the package had some configuration
2990 files from a previous version installed (ie, it
2991 is in the `configuration files only' state):
2993 <var>new-preinst</var> install <var>old-version</var>
2997 <p>Otherwise (ie, the package was completely purged):
2999 <var>new-preinst</var> install
3001 Error unwind versions, respectively:
3003 <var>new-postrm</var> abort-upgrade <var>old-version</var>
3004 <var>new-postrm</var> abort-install <var>old-version</var>
3005 <var>new-postrm</var> abort-install
3015 The new package's files are unpacked, overwriting any
3016 that may be on the system already, for example any
3017 from the old version of the same package or from
3018 another package (backups of the old files are left
3019 around, and if anything goes wrong dpkg will attempt
3020 to put them back as part of the error unwind).
3024 It is an error for a package to contains files which
3025 are on the system in another package, unless
3026 <tt>Replaces</tt> is used (see <ref id="replaces">).
3027 Currently the <tt>--force-overwrite</tt> flag is
3028 enabled, downgrading it to a warning, but this may not
3033 It is a more serious error for a package to contain a
3034 plain file or other kind of nondirectory where another
3035 package has a directory (again, unless
3036 <tt>Replaces</tt> is used). This error can be
3037 overridden if desired using
3038 <tt>--force-overwrite-dir</tt>, but this is not
3043 Packages which overwrite each other's files produce
3044 behaviour which though deterministic is hard for the
3045 system administrator to understand. It can easily
3046 lead to `missing' programs if, for example, a package
3047 is installed which overwrites a file from another
3048 package, and is then removed again.
3051 Part of the problem is due to what is arguably a
3052 bug in <prgn>dpkg</prgn> .
3058 A directory will never be replaced by a symbolic links
3059 to a directory or vice versa; instead, the existing
3060 state (symlink or not) will be left alone and
3061 <prgn>dpkg</prgn> will follow the symlink if there is
3069 <p>If the package is being upgraded, call
3071 <var>old-postrm</var> upgrade <var>new-version</var>
3075 <p>If this fails, <prgn>dpkg</prgn> will attempt:
3077 <var>new-postrm</var> failed-upgrade <var>old-version</var>
3079 Error unwind, for both cases:
3081 <var>old-preinst</var> abort-upgrade <var>new-version</var>
3086 This is the point of no return - if <prgn>dpkg</prgn>
3087 gets this far, it won't back off past this point if an
3088 error occurs. This will leave the package in a fairly
3089 bad state, which will require a successful
3090 reinstallation to clear up, but it's when
3091 <prgn>dpkg</prgn> starts doing things that are
3096 Any files which were in the old version of the package
3097 but not in the new are removed.</p>
3100 <p>The new file list replaces the old.</p>
3103 <p>The new maintainer scripts replace the old.</p>
3107 <p>Any packages all of whose files have been overwritten during the
3108 installation, and which aren't required for
3109 dependencies, are considered to have been removed.
3110 For each such package,
3113 <p><prgn>dpkg</prgn> calls:
3115 <var>disappearer's-postrm</var> disappear \
3116 <var>overwriter</var> <var>overwriter-version</var>
3120 <p>The package's maintainer scripts are removed.
3125 It is noted in the status database as being in a
3126 sane state, namely not installed (any conffiles
3127 it may have are ignored, rather than being
3128 removed by <prgn>dpkg</prgn>). Note that
3129 disappearing packages do not have their prerm
3130 called, because <prgn>dpkg</prgn> doesn't know
3131 in advance that the package is going to
3140 Any files in the package we're unpacking that are also
3141 listed in the file lists of other packages are removed
3142 from those lists. (This will lobotomise the file list
3143 of the `conflicting' package if there is one.)
3148 The backup files made during installation, above, are
3155 The new package's status is now sane, and recorded as
3156 `unpacked'. Here is another point of no return - if
3157 the conflicting package's removal fails we do not
3158 unwind the rest of the installation; the conflicting
3159 package is left in a half-removed limbo.
3164 If there was a conflicting package we go and do the
3165 removal actions (described below), starting with the
3166 removal of the conflicting package's files (any that
3167 are also in the package being installed have already
3168 been removed from the conflicting package's file list,
3169 and so do not get removed now).
3176 <sect><heading>Details of configuration
3180 When we configure a package (this happens with <tt>dpkg
3181 --install</tt>, or with <tt>--configure</tt>), we first
3182 update the conffiles and then call:
3184 <var>postinst</var> configure <var>most-recently-configured-version</var>
3189 No attempt is made to unwind after errors during
3194 If there is no most recently configured version
3195 <prgn>dpkg</prgn> will pass a null argument; older versions
3196 of dpkg may pass <tt><unknown></tt> (including the
3197 angle brackets) in this case. Even older ones do not pass a
3198 second argument at all, under any circumstances.
3202 <sect><heading>Details of removal and/or configuration purging
3209 <var>prerm</var> remove
3214 The package's files are removed (except conffiles).
3219 <var>postrm</var> remove
3223 <p>All the maintainer scripts except the postrm are removed.
3227 If we aren't purging the package we stop here. Note
3228 that packages which have no postrm and no conffiles
3229 are automatically purged when removed, as there is no
3230 difference except for the <prgn>dpkg</prgn>
3235 The conffiles and any backup files (<tt>~</tt>-files,
3236 <tt>#*#</tt> files, <tt>%</tt>-files,
3237 <tt>.dpkg-{old,new,tmp}</tt>, etc.) are removed.</p>
3241 <var>postrm</var> purge
3245 <p>The package's file list is removed.</p>
3248 No attempt is made to unwind after errors during
3253 <chapt id="descriptions"><heading>Descriptions of packages - the
3254 <tt>Description</tt> field
3258 The <tt>Description</tt> control file field is used by
3259 <prgn>dselect</prgn> when the user is selecting which packages
3260 to install and by <prgn>dpkg</prgn> when it displays
3261 information about the status of packages and so forth. It is
3262 included on the FTP site in the <prgn>Packages</prgn> files,
3263 and may also be used by the Debian WWW pages.
3267 The description is intended to describe the program to a user
3268 who has never met it before so that they know whether they
3269 want to install it. It should also give information about the
3270 significant dependencies and conflicts between this package
3271 and others, so that the user knows why these dependencies and
3272 conflicts have been declared.
3276 The field's format is as follows:
3278 Description: <var>single line synopsis</var>
3279 <var>extended description over several lines</var>
3284 The synopsis is often printed in lists of packages and so
3285 forth, and should be as informative as possible. Every
3286 package should also have an extended description.
3289 <sect><heading>Types of formatting line in the extended
3297 Those starting with a single space are part of a
3298 paragraph. Successive lines of this form will be
3299 word-wrapped when displayed. The leading space will
3300 usually be stripped off.
3306 Those starting with two or more spaces. These will be
3307 displayed verbatim. If the display cannot be panned
3308 horizontally the displaying program will linewrap them
3309 `hard' (ie, without taking account of word breaks).
3310 If it can they will be allowed to trail off to the
3311 right. None, one or two initial spaces may be
3312 deleted, but the number of spaces deleted from each
3313 line will be the same (so that you can have indenting
3314 work correctly, for example).
3319 <p>Those containing a single space followed by a single full stop
3320 character. These are rendered as blank lines. This
3321 is the <em>only</em> way to get a blank line - see
3327 Those containing a space, a full stop and some more
3328 characters. These are for future expansion. Do not
3335 <sect><heading>Notes about writing descriptions
3339 <em>Always</em> start extended description lines with at least one
3340 whitespace character. Fields in the control file and in the Packages
3341 file are separated by field names starting in the first column, just
3342 as message header fields are in RFC822. Forgetting the whitespace
3343 will cause <prgn>dpkg-deb</prgn>
3346 Version 0.93.23 or later.
3348 </footnote> to produce a syntax error when trying to build
3349 the package. If you force it to build anyway
3350 <prgn>dpkg</prgn> will refuse to install the resulting
3355 <em>Do not</em> include any completely <em>empty</em>
3356 lines. These separate different records in the Packages file
3357 and different packages in the <tt>debian/control</tt> file,
3358 and are forbidden in package control files. See the
3359 previous paragraph for what happens if you get this wrong.
3363 The single line synopsis should be kept brief - certainly
3364 under 80 characters. <prgn>dselect</prgn> displays between
3365 25 and 49 characters without panning if you're using an
3366 80-column terminal, depending on what display options are in
3371 Do not include the package name in the synopsis line. The
3372 display software knows how to display this already, and you
3373 do not need to state it. Remember that in many situations
3374 the user may only see the synopsis line - make it as
3375 informative as you can.
3379 The extended description should describe what the package
3380 does and how it relates to the rest of the system (in terms
3381 of, for example, which subsystem it is which part of).
3385 The blurb that comes with a program in its announcements
3386 and/or <prgn>README</prgn> files is rarely suitable for use
3387 in a description. It is usually aimed at people who are
3388 already in the community where the package is used. The
3389 description field needs to make sense to anyone, even people
3390 who have no idea about any of the things the package deals
3395 Put important information first, both in the synopis and
3396 extended description. Sometimes only the first part of the
3397 synopsis or of the description will be displayed. You can
3398 assume that there will usually be a way to see the whole
3399 extended description.
3403 You may include information about dependencies and so forth
3404 in the extended description, if you wish.
3408 Do not use tab characters. Their effect is not predictable.
3412 Do not try to linewrap the summary (the part on the same
3413 line as the field name <tt>Description</tt>) into the
3414 extended description. This will not work correctly when the
3415 full description is displayed, and makes no sense where only
3416 the summary is available.</p>
3419 <sect><heading>Example description in control file for Smail
3425 Version: 3.1.29.1-13
3426 Maintainer: Ian Jackson <iwj10@cus.cam.ac.uk>
3427 Recommends: pine | mailx | elm | emacs | mail-user-agent
3429 Depends: cron, libc5
3431 Provides: mail-transport-agent
3432 Description: Electronic mail transport system.
3433 Smail is the recommended mail transport agent (MTA) for Debian.
3435 An MTA is the innards of the mail system - it takes messages from
3436 user-friendly mailer programs and arranges for them to be delivered
3437 locally or passed on to other systems as required.
3439 In order to make use of it you must have one or more user level
3440 mailreader programs such as elm, pine, mailx or Emacs (which has Rmail
3441 and VM as mailreaders) installed. If you wish to send messages other
3442 than just to other users of your system you must also have appropriate
3443 networking support, in the form of IP or UUCP.
3449 <chapt id="relationships"><heading>Declaring relationships between
3454 Packages can declare in their control file that they have
3455 certain relationships to other packages - for example, that
3456 they may not be installed at the same time as certain other
3457 packages, and/or that they depend on the presence of others,
3458 or that they should overwrite files in certain other packages
3463 This is done using the <tt>Depends</tt>, <tt>Recommends</tt>,
3464 <tt>Suggests</tt>, <tt>Conflicts</tt>, <tt>Provides</tt> and
3465 <tt>Replaces</tt> control file fields.
3468 <sect id="depsyntax"><heading>Syntax of relationship fields
3472 These fields all have a uniform syntax. They are a list of
3473 package names separated by commas.
3477 In <tt>Depends</tt>, <tt>Recommends</tt>, <tt>Suggests</tt>
3478 and <tt>Pre-Depends</tt> (the fields which declare
3479 dependencies of the package in which they occur on other
3480 packages) these package names may also be lists of
3481 alternative package names, separated by vertical bar symbols
3482 <tt>|</tt> (pipe symbols).
3486 All the fields except <tt>Provides</tt> may restrict their
3487 applicability to particular versions of each named package.
3488 This is done in parentheses after each individual package
3489 name; the parentheses should contain a relation from the
3490 list below followed by a version number, in the format
3491 described in <ref id="versions">.
3495 The relations allowed are <tt><<</tt>, <tt><=</tt>,
3496 <tt>=</tt>, <tt>>=</tt> and <tt>>></tt> for
3497 strictly earlier, earlier or equal, exactly equal, later or
3498 equal and strictly later, respectively. The forms
3499 <tt><</tt> and <tt>></tt> were used to mean
3500 earlier/later or equal, rather than strictly earlier/later,
3501 so they should not appear in new packages (though
3502 <prgn>dpkg</prgn> still supports them).
3506 Whitespace may appear at any point in the version
3507 specification, and must appear where it's necessary to
3508 disambiguate; it is not otherwise significant. For
3509 consistency and in case of future changes to
3510 <prgn>dpkg</prgn> it is recommended that a single space be
3511 used after a version relationship and before a version
3512 number; it is usual also to put a single space after each
3513 comma, on either side of each vertical bar, and before each
3522 Depends: libc5 (>= 5.2.18-4), mime-support, csh | tcsh
3527 <sect><heading>Dependencies - <tt>Depends</tt>, <tt>Recommends</tt>,
3528 <tt>tt>Sugge</tt>tt>, <tt>Pre-Depends</tt>
3532 These four fields are used to declare a dependency by one
3533 package on another. They appear in the depending package's
3538 All but <tt>Pre-Depends</tt> (discussed below) take effect
3539 <em>only</em> when a package is to be configured. They do
3540 not prevent a package being on the system in an unconfigured
3541 state while its dependencies are unsatisfied, and it is
3542 possible to replace a package whose dependencies are
3543 satisfied and which is properly installed with a different
3544 version whose dependencies are not and cannot be satisfied;
3545 when this is done the depending package will be left
3546 unconfigured (since attempts to configure it will give
3547 errors) and will not function properly.
3551 For this reason packages in an installation run are usually
3552 all unpacked first and all configured later; this gives
3553 later versions of packages with dependencies on later
3554 versions of other packages the opportunity to have their
3555 dependencies satisfied.
3559 Thus <tt>Depends</tt> allows package maintainers to impose
3560 an order in which packages should be configured.
3562 <tag><tt>Depends</tt></tag>
3565 <p>This declares an absolute dependency.
3569 <prgn>dpkg</prgn> will not configure packages whose
3570 dependencies aren't satisfied. If it is asked to make
3571 an installation which would cause an installed
3572 package's dependencies to become unsatisfied it will
3576 Current versions (1.2.4) of <prgn>dpkg</prgn> have
3577 a bug in this area which will cause some of these
3578 problems to be ignored.
3580 </footnote>, unless <tt>--auto-deconfigure</tt> is
3581 specified, in which case those packages will be
3582 deconfigured before the installation proceeds.
3586 <prgn>dselect</prgn> makes it hard for the user to
3587 select packages for installation, removal or upgrade
3588 in a way that would mean that packages'
3589 <prgn>Depends</prgn> fields would be unsatisfied. The
3590 user can override this if they wish, for example if
3591 they know that <prgn>dselect</prgn> has an out-of-date
3592 view of the real package relationships.
3596 The <tt>Depends</tt> field should be used if the
3597 depended-on package is required for the depending
3598 package to provide a significant amount of
3602 <tag><tt>Recommends</tt></tag>
3604 <p>This declares a strong, but not absolute, dependency.
3608 <tt>Recommends</tt> is ignored by <prgn>dpkg</prgn>,
3609 so that users using the command-line (who are presumed
3610 to know what they're doing) will not be impeded.
3614 It is treated by <prgn>dselect</prgn> exactly as
3615 <tt>Depends</tt> is; this makes it hard for the user
3616 to select things so as to leave <tt>Recommends</tt>
3617 fields unsatisfied, but they are able to do so by
3622 The <tt>Recommends</tt> field should list packages
3623 that would be found together with this one in all but
3624 unusual installations.</p>
3627 <tag><tt>Suggests</tt></tag>
3631 This is used to declare that one package may be more
3632 useful with one or more others. Using this field
3633 tells the packaging system and the user that the
3634 listed packages are be related to this one and can
3635 perhaps enhance its usefulness, but that installing
3636 this one without them is perfectly reasonable.
3640 <prgn>dselect</prgn> will offer suggsted packages to
3641 the system administrator when they select the
3642 suggesting package, but the default is not to install
3643 the suggested package.</p>
3646 <tag><tt>Pre-Depends</tt></tag>
3649 <p>This field is like <tt>Depends</tt>, except that it also forces
3650 <prgn>dpkg</prgn> to complete installation of the
3651 packages named before even starting the installation
3652 of the package which declares the predependency.
3656 <prgn>dselect</prgn> checks for predependencies when
3657 it is doing an installation run, and will attempt to
3658 find the packages which are required to be installed
3659 first and do so in the right order.
3663 However, this process is slow (because it requires
3664 repeated invocations of <prgn>dpkg</prgn>) and
3665 troublesome (because it requires guessing where to
3666 find the appropriate files).
3670 For these reasons, and because this field imposes
3671 restrictions on the order in which packages may be
3672 unpacked (which can be difficult for installations
3673 from multipart media, for example),
3674 <tt>Pre-Depends</tt> should be used sparingly,
3675 preferably only by packages whose premature upgrade or
3676 installation would hamper the ability of the system to
3677 continue with any upgrade that might be in progress.
3681 When the package declaring it is being configured, a
3682 <tt>Pre-Dependency</tt> will be considered satisfied
3683 only if the depending package has been correctly
3684 configured, just as if an ordinary <tt>Depends</tt>
3689 However, when a package declaring a predependency is
3690 being unpacked the predependency can be satisfied even
3691 if the depended-on package(s) are only unpacked or
3692 half-configured, provided that they have been
3693 configured correctly at some point in the past (and
3694 not removed or partially removed since). In this case
3695 both the previously-configured and currently unpacked
3696 or half-configured versions must satisfy any version
3697 clause in the <tt>Pre-Depends</tt> field.
3703 When selecting which level of dependency to use you should
3704 consider how important the depended-on package is to the
3705 functionality of the one declaring the dependency. Some
3706 packages are composed of components of varying degrees of
3707 importance. Such a package should list using
3708 <tt>Depends</tt> the package(s) which are required by the
3709 more important components. The other components'
3710 requirements may be mentioned as Suggestions or
3711 Recommendations, as appropriate to the components' relative
3715 <sect1><heading>Dependencies on shared libraries
3719 The dependency fields listed above are used by packages
3720 which need shared libraries to declare dependencies on the
3721 appropriate packages.
3725 These dependencies are usually determined automatically
3726 using <prgn>dpkg-shlibdeps</prgn> and inserted in the
3727 package control file using the control file substitution
3728 variables mechanism; see <ref id="srcsubstvars"> and
3729 <ref id="sourcetools">.
3733 <sect1><heading>Deconfiguration due to removal during bulk
3738 If <prgn>dpkg</prgn> would like to remove a package due to a
3739 conflict, as described above, but this would violate a
3740 dependency of some other package on the system,
3741 <prgn>dpkg</prgn> will usually not remove the conflicting
3742 package and halt with an error.
3746 However, if the <tt>--auto-deconfigure</tt> (<tt>-B</tt>)
3747 option is used <prgn>dpkg</prgn> will automatically
3748 `deconfigure' the package with the problematic dependency,
3749 so that the conflicting package can be removed and the
3750 package we're trying to install can be installed. If
3751 <prgn>dpkg</prgn> is being asked to install packages (rather
3752 than just unpacking them) it will try to reconfigure the
3753 package when it has unpacked all its arguments, in the hope
3754 that one of the other packages it is installing will satisfy
3755 the problematic dependency.
3759 <prgn>dselect</prgn> supplies this argument to
3760 <prgn>dpkg</prgn> when it invokes it, so that bulk
3761 installations proceed smoothly.
3765 <sect id="conflicts"><heading>Alternative packages -
3766 <tt>tt>Confli</tt>tt> and <tt>Replaces</tt>
3770 When one package declares a conflict with another
3771 <prgn>dpkg</prgn> will refuse to allow them to be installed
3772 on the system at the same time.
3776 If one package is to be installed, the other must be removed first -
3777 if the package being installed is marked as replacing (<ref
3778 id="replaces">) the one on the system, or the one on the system is
3779 marked as deselected, or both packages are marked
3780 <tt>Essential</tt>, then <prgn>dpkg</prgn> will
3781 automatically remove the package which is causing the
3782 conflict, otherwise it will halt the installation of the new
3783 package with an error.
3787 <prgn>dselect</prgn> makes it hard to select conflicting
3788 packages, though the user can override this if they wish.
3789 If they do not override it then <prgn>dselect</prgn> will
3790 select one of the packages for removal, and the user must
3791 make sure it is the right one. In the future
3792 <prgn>dselect</prgn> will look for the presence of a
3793 <tt>Replaces</tt> field to help decide which package should
3794 be installed and which removed.
3798 A package will not cause a conflict merely because its
3799 configuration files are still installed; it must be at least
3804 A special exception is made for packages which declare a
3805 conflict with their own package name, or with a virtual
3806 package which they provide (see below): this does not
3807 prevent their installation, and allows a package to conflict
3808 with others providing a replacement for it. You use this
3809 feature when you want the package in question to be the only
3810 package providing something.
3814 A <tt>Conflicts</tt> entry should almost never have an
3815 `earlier than' version clause. This would prevent
3816 <prgn>dpkg</prgn> from upgrading or installing the package
3817 which declared such a conflict until the upgrade or removal
3818 of the conflicted-with package had been completed. This
3819 aspect of installation ordering is not handled by
3820 <prgn>dselect</prgn>, so that the use <tt>Conflicts</tt> in
3821 this way is likely to cause problems for `bulk run' upgrades
3826 <sect id="virtual"><heading>Virtual packages - <tt>Provides</tt>
3830 As well as the names of actual (`concrete') packages, the
3831 package relationship fields <tt>Depends</tt>,
3832 <tt>Recommends</tt>, <tt>Suggests</tt> and
3833 <tt>Conflicts</tt> may mention virtual packages.
3837 A virtual package is one which appears in the
3838 <tt>Provides</tt> control file field of another package.
3839 The effect is as if the package(s) which provide a
3840 particular virtual package name had been listed by name
3841 everywhere were the virtual package name appears.
3845 If there are both a real and a virtual package of the same
3846 name then the dependency may be satisfied (or the conflict
3847 caused) by either the real package or any of the virtual
3848 packages which provide it. This is so that, for example,
3854 and someone else releases an xemacs package they can say
3858 </example> and all will work in the interim (until a purely
3859 virtual package name is decided on and the <tt>emacs</tt>
3860 and <tt>vm</tt> packages are changed to use it).
3864 If a dependency or a conflict has a version number attached
3865 then only real packages will be considered to see whether
3866 the relationship is satisfied (or the prohibition violated,
3867 for a conflict) - it is assumed that a real package which
3868 provides virtual package is not of the `right' version. So,
3869 a <tt>Provides</tt> field may not contain version numbers,
3870 and the version number of the concrete package which
3871 provides a particular virtual package will not be looked at
3872 when considering a dependency on or conflict with the
3873 virtual package name.
3877 It is likely that the ability will be added in a future
3878 release of <prgn>dpkg</prgn> to specify a version number for
3879 each virtual package it provides. This feature is not yet
3880 present, however, and is expected to be used only
3885 If you want to specify which of a set of real packages should be the
3886 default to satisfy a particular dependency on a virtual package, you
3887 should list the real package as alternative before the virtual.
3892 <sect id="replaces"><heading><tt>Replaces</tt> - overwriting
3893 files and replacing packages
3897 The <tt>Replaces</tt> control file field has two purposes,
3898 which come into play in different situations.
3902 Virtual packages (<ref id="virtual">) are not considered
3903 when looking at a <tt>Replaces</tt> field - the packages
3904 declared as being replaced must be mentioned by their real
3908 <sect1><heading>Overwriting files in other packages
3912 Firstly, as mentioned before, it is usually an error for a
3913 package to contains files which are on the system in
3914 another package, though currently the
3915 <tt>--force-overwrite</tt> flag is enabled by default,
3916 downgrading the error to a warning,
3920 If the overwriting package declares that it replaces the
3921 one containing the file being overwritten then
3922 <prgn>dpkg</prgn> will proceed, and replace the file from
3923 the old package with that from the new. The file will no
3924 longer be listed as `owned' by the old package.
3928 If a package is completely replaced in this way, so that
3929 <prgn>dpkg</prgn> does not know of any files it still
3930 contains, it is considered to have disappeared. It will
3931 be marked as not wanted on the system (selected for
3932 removal) and not installed. Any conffiles details noted
3933 in the package will be ignored, as they will have been
3934 taken over by the replacing package(s). The package's
3935 <prgn>postrm</prgn> script will be run to allow the
3936 package to do any final cleanup required. See <ref
3937 id="mscriptsinstact">.
3941 In the future <prgn>dpkg</prgn> will discard files which
3942 overwrite those from another package which declares that
3943 it replaces the one being installed (so that you can
3944 install an older version of a package without problems).
3948 This usage of <tt>Replaces</tt> only takes effect when
3949 both packages are at least partially on the system at
3950 once, so that it can only happen if they do not conflict
3951 or if the conflict has been overridden.</p>
3954 <sect1><heading>Replacing whole packages, forcing their
3959 Secondly, <tt>Replaces</tt> allows <prgn>dpkg</prgn> and
3960 <prgn>dselect</prgn> to resolve which package should be
3961 removed when a conflict - see <ref id="conflicts">. This
3962 usage only takes effect when the two packages <em>do</em>
3963 conflict, so that the two effects do not interfere with
3969 <sect><heading>Defaults for satisfying dependencies - ordering
3973 Ordering is significant in dependency fields.
3977 Usually dselect will suggest to the user that they select
3978 the package with the most `fundamental' class (eg, it will
3979 prefer Base packages to Optional ones), or the one that they
3980 `most wanted' to select in some sense.
3984 In the absence of other information <prgn>dselect</prgn>
3985 will offer a default selection of the first named package in
3986 a list of alternatives.
3990 However, there is no way to specify the `order' of several
3991 packages which all provide the same thing, when that thing
3992 is listed as a dependency.
3996 Therefore a dependency on a virtual package should contain a
3997 concrete package name as the first alternative, so that this
4002 For example, consider the set of packages:
4005 Recommends: info-browser
4008 Provides: info-browser
4011 Provides: info-browser
4016 If <prgn>emacs</prgn> and <prgn>info</prgn> both have the
4017 same priority then <prgn>dselect</prgn>'s choice is
4018 essentially random. Better would be
4021 Recommends: info | info-browser
4023 so that <prgn>dselect</prgn> defaults to selecting the
4024 lightweight standalone info browser.
4029 <chapt id="conffiles"><heading>Configuration file handling
4033 <prgn>dpkg</prgn> can do a certain amount of automatic
4034 handling of package configuration files.
4038 Whether this mechanism is appropriate depends on a number of
4039 factors, but basically there are two approaches to any
4040 particular configuration file.
4044 The easy method is to ship a best-effort configuration in the
4045 package, and use <prgn>dpkg</prgn>'s conffile mechanism to
4046 handle updates. If the user is unlikely to want to edit the
4047 file, but you need them to be able to without losing their
4048 changes, and a new package with a changed version of the file
4049 is only released infrequently, this is a good approach.
4053 The hard method is to build the configuration file from
4054 scratch in the <prgn>postinst</prgn> script, and to take the
4055 responsibility for fixing any mistakes made in earlier
4056 versions of the package automatically. This will be
4057 appropriate if the file is likely to need to be different on
4061 <sect><heading>Automatic handling of configuration files by
4066 A package may contain a control area file called
4067 <tt>conffiles</tt>. This file should be a list of filenames
4068 of configuration files needing automatic handling, separated
4069 by newlines. The filenames should be absolute pathnames,
4070 and the files referred to should actually exist in the
4075 When a package is upgraded <prgn>dpkg</prgn> will process
4076 the configuration files during the configuration stage,
4077 shortly before it runs the package's <prgn>postinst</prgn>
4082 For each file it checks to see whether the version of the
4083 file included in the package is the same as the one that was
4084 included in the last version of the package (the one that is
4085 being upgraded from); it also compares the version currently
4086 installed on the system with the one shipped with the last
4091 If neither the user nor the package maintainer has changed
4092 the file, it is left alone. If one or the other has changed
4093 their version, then the changed version is preferred - ie,
4094 if the user edits their file, but the package maintainer
4095 doesn't ship a different version, the user's changes will
4096 stay, silently, but if the maintainer ships a new version
4097 and the user hasn't edited it the new version will be
4098 installed (with an informative message). If both have
4099 changed their version the user is prompted about the problem
4100 and must resolve the differences themselves.
4104 The comparisons are done by calculating the MD5 message
4105 digests of the files, and storing the MD5 of the file as it
4106 was included in the most recent version of the package.
4110 When a package is installed for the first time
4111 <prgn>dpkg</prgn> will install the file that comes with it,
4112 unless that would mean overwriting a file already on the
4117 However, note that <prgn>dpkg</prgn> will <em>not</em>
4118 replace a conffile that was removed by the user (or by a
4119 script). This is necessary because with some programs a
4120 missing file produces an effect hard or impossible to
4121 achieve in another way, so that a missing file needs to be
4122 kept that way if the user did it.
4126 Note that a package should <em>not</em> modify a
4127 <prgn>dpkg</prgn>-handled conffile in its maintainer
4128 scripts. Doing this will lead to <prgn>dpkg</prgn> giving
4129 the user confusing and possibly dangerous options for
4130 conffile update when the package is upgraded.</p>
4133 <sect><heading>Fully-featured maintainer script configuration
4138 For files which contain site-specific information such as
4139 the hostname and networking details and so forth, it is
4140 better to create the file in the package's
4141 <prgn>postinst</prgn> script.
4145 This will typically involve examining the state of the rest
4146 of the system to determine values and other information, and
4147 may involve prompting the user for some information which
4148 can't be obtained some other way.
4152 When using this method there are a couple of important
4153 issues which should be considered:
4157 If you discover a bug in the program which generates the
4158 configuration file, or if the format of the file changes
4159 from one version to the next, you will have to arrange for
4160 the postinst script to do something sensible - usually this
4161 will mean editing the installed configuration file to remove
4162 the problem or change the syntax. You will have to do this
4163 very carefully, since the user may have changed the file,
4164 perhaps to fix the very problem that your script is trying
4165 to deal with - you will have to detect these situations and
4166 deal with them correctly.
4170 If you do go down this route it's probably a good idea to
4171 make the program that generates the configuration file(s) a
4172 separate program in <tt>/usr/sbin</tt>, by convention called
4173 <tt><var>package</var>config</tt> and then run that if
4174 appropriate from the post-installation script. The
4175 <tt><var>package</var>config</tt> program should not
4176 unquestioningly overwrite an existing configuration - if its
4177 mode of operation is geared towards setting up a package for
4178 the first time (rather than any arbitrary reconfiguration
4179 later) you should have it check whether the configuration
4180 already exists, and require a <tt>--force</tt> flag to
4181 overwrite it.</p></sect>
4186 <chapt id="alternatives"><heading>Alternative versions of an interface -
4187 <prgn>update-alternatives</prgn>
4191 When several packages all provide different versions of the
4192 same program or file it is useful to have the system select a
4193 default, but to allow the system administrator to change it
4194 and have their decisions respected.
4198 For example, there are several versions of the <prgn>vi</prgn>
4199 editor, and there is no reason to prevent all of them from
4200 being installed at once, each under their own name
4201 (<prgn>nvi</prgn>, <prgn>vim</prgn> or whatever).
4202 Nevertheless it is desirable to have the name <tt>vi</tt>
4203 refer to something, at least by default.
4207 If all the packages involved cooperate, this can be done with
4208 <prgn>update-alternatives</prgn>.
4212 Each package provides its own version under its own name, and
4213 calls <prgn>update-alternatives</prgn> in its postinst to
4214 register its version (and again in its prerm to deregister
4219 See the manpage <manref name="update-alternatives"
4220 section="8"> for details.
4224 If <prgn>update-alternatives</prgn> does not seem appropriate
4225 you may wish to consider using diversions instead.</p>
4229 <chapt id="diversions"><heading>Diversions - overriding a
4230 package's version of a file
4234 It is possible to have <prgn>dpkg</prgn> not overwrite a file
4235 when it reinstalls the package it belongs to, and to have it
4236 put the file from the package somewhere else instead.
4240 This can be used locally to override a package's version of a
4241 file, or by one package to override another's version (or
4242 provide a wrapper for it).
4246 Before deciding to use a diversion, read <ref
4247 id="alternatives"> to see if you really want a diversion
4248 rather than several alternative versions of a program.
4252 There is a diversion list, which is read by <prgn>dpkg</prgn>,
4253 and updated by a special program <prgn>dpkg-divert</prgn>.
4254 Please see <manref name="dpkg-divert" section="8"> for full
4255 details of its operation.
4259 When a package wishes to divert a file from another, it should
4260 call <prgn>dpkg-divert</prgn> in its preinst to add the
4261 diversion and rename the existing file. For example,
4262 supposing that a <prgn>smailwrapper</prgn> package wishes to
4263 install a wrapper around <tt>/usr/sbin/smail</tt>:
4265 if [ install = "$1" ]; then
4266 dpkg-divert --package smailwrapper --add --rename \
4267 --divert /usr/sbin/smail.real /usr/sbin/smail
4269 </example> Testing <tt>$1</tt> is necessary so that the script
4270 doesn't try to add the diversion again when
4271 <prgn>smailwrapper</prgn> is upgraded. The <tt>--package
4272 smailwrapper</tt> ensures that <prgn>smailwrapper</prgn>'s
4273 copy of <tt>/usr/sbin/smail</tt> can bypass the diversion and
4274 get installed as the true version.
4278 The postrm has to do the reverse:
4280 if [ remove = "$1" ]; then
4281 dpkg-divert --package smailwrapper --remove --rename \
4282 --divert /usr/sbin/smail.real /usr/sbin/smail
4288 Do not attempt to divert a file which is vitally important for
4289 the system's operation - when using <prgn>dpkg-divert</prgn>
4290 there is a time, after it has been diverted but before
4291 <prgn>dpkg</prgn> has installed the new version, when the file
4296 <chapt id="sharedlibs"><heading>Shared libraries
4300 Packages containing shared libraries must be constructed with
4301 a little care to make sure that the shared library is always
4302 available. This is especially important for packages whose
4303 shared libraries are vitally important, such as the libc.
4307 Firstly, your package should install the shared libraries
4308 under their normal names. For example, the
4309 <prgn>libgdbm1</prgn> package should install
4310 <tt>libgdbm.so.1.7.3</tt> as
4311 <tt>/usr/lib/libgdbm.so.1.7.3</tt>. The files should not be
4312 renamed or relinked by any prerm or postrm scripts;
4313 <prgn>dpkg</prgn> will take care of renaming things safely
4314 without affecting running programs, and attempts to interfere
4315 with this are likely to lead to problems.
4319 Secondly, your package should include the symlink that
4320 <prgn>ldconfig</prgn> would create for the shared libraries.
4321 For example, the <prgn>libgdbm1</prgn> package should include
4322 a symlink from <tt>/usr/lib/libgdbm.so.1</tt> to
4323 <tt>libgdbm.so.1.7.3</tt>. This is needed so that
4324 <prgn>ld.so</prgn> can find the library in between the time
4325 <prgn>dpkg</prgn> installs it and <prgn>ldconfig</prgn> is run
4326 in the <prgn>postinst</prgn> script. Futhermore, and <em>this
4327 is very important</em>, the library must be placed before the
4328 symlink pointing to it in the <tt>.deb</tt> file. This is so
4329 that by the time <prgn>dpkg</prgn> comes to install the
4330 symlink (overwriting the previous symlink pointing at an older
4331 version of the library) the new shared library is already in
4332 place. Currently the way to ensure the ordering is done
4333 properly is to install the library in the appropriate
4334 <tt>debian/tmp/.../lib</tt> directory before creating the
4335 symlink, by putting the commands in the <tt>debian/rules</tt>
4336 in the appropriate order.
4340 next Paragraph added to close Bug #5299, Guy Maor
4344 Thirdly, the development package should contain a symlink for
4345 the shared library without a version number. For example, the
4346 <tt>libgdbm1-dev</tt> package should include a symlink from
4347 <tt>/usr/lib/libgdm.so</tt> to <tt>libgdm.so.1.7.3</tt>. This
4348 symlink is needed by <prgn>ld</prgn> when compiling packages
4349 as it will only look for <tt>libgdm.so</tt> and
4350 <tt>libgdm.a</tt> when compiling dynamically or statically,
4355 next paragraph changed by Christian Schwarz (see policy weekly #6)
4359 Any package installing shared libraries in a directory that's listed
4360 in <tt>/etc/ld.so.conf</tt> or in one of the default library
4361 directories of <prgn>ld.so</prgn> (currently, these are <tt>/usr/lib</tt>
4362 and <tt>/lib</tt>) must call <prgn>ldconfig</prgn> in its <prgn>postinst</prgn>
4363 script if and only if the first argument is `configure'. However, it
4364 is important not to call <prgn>ldconfig</prgn> in the postrm or preinst
4365 scripts in the case where the package is being upgraded (see <ref
4366 id="unpackphase">), as <prgn>ldconfig</prgn> will see the temporary names
4367 that <prgn>dpkg</prgn> uses for the files while it is
4368 installing them and will make the shared library links point
4369 to them, just before <prgn>dpkg</prgn> continues the
4370 installation and removes the links!
4374 moved from section 2.2 , DMorris
4377 <sect id="shlibs"><heading>The <tt>shlibs</tt> File Format
4381 This file is for use by <prgn>dpkg-shlibdeps</prgn> and is
4382 required when your package provides shared libraries.
4386 Each line is of the form:
4388 <var>library-name</var> <var>version-or-soname</var> <var>dependencies ...</var>
4393 <var>library-name</var> is the name of the shared library,
4394 for example <tt>libc5</tt>.
4398 <var>version-or-soname</var> is the soname of the library -
4399 ie, the thing that must exactly match for the library to be
4400 recognised by <prgn>ld.so</prgn>. Usually this is major
4401 version number of the library.
4405 <var>dependencies</var> has the same syntax as a dependency
4406 field in a binary package control file. It should give
4407 details of which package(s) are required to satisfy a binary
4408 built against the version of the library contained in the
4409 package. See <ref id="depsyntax">.
4413 For example, if the package <tt>foo</tt> contains
4414 <tt>libfoo.so.1.2.3</tt>, where the soname of the library is
4415 <tt>libfoo.so.1</tt>, and the first version of the package
4416 which contained a minor number of at least <tt>2.3</tt> was
4417 <var>1.2.3-1</var>, then the package's <var>shlibs</var>
4420 libfoo 1 foo (>= 1.2.3-1)
4425 The version-specific dependency is to avoid warnings from
4426 <prgn>ld.so</prgn> about using older shared libraries with
4430 <sect><heading>Further Technical information on
4431 <tt>shlibs</tt></heading>
4435 following section mostly provided by Heiko Schlittermann
4439 <sect1><heading><em>What</em> are the <tt>shlibs</tt> files?
4443 The <tt>debian/shlibs</tt> file provides a way of checking
4444 for shared library dependencies on packaged binaries.
4445 They are intended to be used by package maintainers to
4446 make their lives easier.
4450 Other <tt>shlibs</tt> files that exist on a Debian system are
4452 <item> <p><tt>/etc/dpkg/shlibs.default</tt></p></item>
4453 <item> <p><tt>/etc/dpkg/shlibs.override</tt></p></item>
4454 <item> <p><tt>/var/lib/dpkg/info/*.shlibs</tt></p></item>
4455 <item> <p><tt>debian/shlibs.local</tt></p></item>
4457 These files are used by <prgn>dpkg-shlibdeps</prgn> when
4458 creating a binary package.</p>
4461 <sect1><heading><em>How</em> does <prgn>dpkg-shlibdeps</prgn>
4466 <prgn>dpkg-shlibdeps</prgn> calls <prgn>ldd</prgn> to
4467 determine the shared libraries used by the compiled
4468 binaries passed through its command line.
4472 For each shared library, <prgn>dpkg-shlibdeps</prgn> needs to know
4473 <list compact="compact">
4474 <item><p>the package containing the library, and</p></item>
4475 <item><p>the library version number,</p></item>
4478 it scans the following files in this order.
4479 <enumlist compact="compact">
4480 <item><p><tt>debian/shlibs.local</tt></p></item>
4481 <item><p><tt>/etc/dpkg/shlibs.override</tt></p></item>
4482 <item><p><tt>/var/lib/dpkg/info/*.shlibs</tt></p></item>
4483 <item><p><tt>/etc/dpkg/shlibs.default</tt></p></item>
4487 <sect1><heading><em>Who</em> maintains the various
4488 <tt>shlibs</tt> files?
4492 <list compact="compact">
4494 <p><tt>/etc/dpkg/shlibs.default</tt> - the maintainer
4499 <tt>/var/lib/dpkg/info/<var>package</var>.shlibs</tt>
4500 - the maintainer of each package</p>
4504 <tt>/etc/dpkg/shlibs.override</tt> - the local
4505 system administrator</p>
4508 <p><tt>debian/shlibs.local</tt> - the maintainer of
4513 The <tt>shlibs.default</tt> file is managed by
4514 <prgn>dpkg</prgn>. The entries in <tt>shlibs.default</tt>
4515 that are provided by <prgn>dpkg</prgn> are just there to
4516 fix things until the shared library packages all have
4517 <tt>shlibs</tt> files.
4521 <sect1><heading><em>How</em> to use <prgn>dpkg-shlibdeps</prgn> and
4522 the <tt>shlibs</tt> files?
4525 <sect2><heading>If your package doesn't provide a shared
4530 Put a call to <prgn>dpkg-shlibdeps</prgn> into your
4531 <tt>debian/rules</tt> file. If your package contains
4532 only binaries (e.g. no scripts) use:
4534 dpkg-shlibdeps debian/tmp/usr/bin/* debian/tmp/usr/sbin/*
4536 If <prgn>dpkg-shlibdeps</prgn> doesn't complain, you're
4537 done. If it does complain you might need to create your
4538 own <tt>debian/shlibs.local</tt> file.</p>
4541 <sect2><heading>If your package provides a shared library
4545 Create a <tt>debian/shlibs</tt> file and let
4546 <tt>debian/rules</tt> install it in the control area:
4548 install -m644 debian/shlibs debian/tmp/DEBIAN
4550 If your package contains additional binaries see above.
4555 <sect1><heading><em>How</em> to write
4556 <tt>debian/shlibs.local</tt>
4560 This file is intended only as a <em>temporary</em> fix if
4561 your binaries depend on a library which doesn't provide
4562 its own <tt>/var/lib/dpkg/*.shlibs</tt> file yet.
4566 Let's assume you are packaging a binary <tt>foo</tt>. Your
4567 output in building the package might look like this.
4570 libbar.so.1 => /usr/X11R6/lib/libbar.so.1.0
4571 libc.so.5 => /lib/libc.so.5.2.18
4572 libX11.so.6 => /usr/X11R6/lib/libX11.so.6.0
4574 And when you ran <prgn>dpkg-shlibdeps</prgn>
4576 $ dpkg-shlibdeps -o foo
4577 dpkg-shlibdeps: warning: unable to find dependency information
4578 for shared library libbar
4579 (soname 1, path /usr/X11R6/lib/libbar.so.1.0, dependency field Depends)
4580 shlibs:Depends=elf-x11r6lib, libc5 (>= 5.2.18)
4582 The <prgn>foo</prgn> binary depends on the
4583 <prgn>libbar</prgn> shared library, but no package seems
4584 to provide a <tt>*.shlibs</tt> file in
4585 <tt></tt>var/lib/dpkg/info/. Let's determine the package
4591 $ dpkg -S /usr/X11R6/lib/libbar.so.1.0
4592 bar1: /usr/X11R6/lib/libbar.so.1.0
4593 $ dpkg -s bar1 | grep Version
4596 This tells us that the <prgn>bar1</prgn> package, version
4597 1.0-1 is the one we are using. Now we can create our own
4598 <tt>debian/shlibs.local</tt> to temporarly fix the above
4599 problem. Include the following line into your
4600 <tt>debian/shlibs.local</tt> file.
4602 libbar 1 bar1 (>= 1.0-1)
4604 Now your package build should work. As soon as the
4605 maintainer of <prgn>libbar1</prgn> provides a
4606 <tt>shlibs</tt> file, you can remove your
4607 <tt>debian/shlibs.local</tt> file.
4613 <chapt id="methif"><heading><prgn>dselect</prgn>'s interface to
4614 its installation methods
4618 <prgn>dselect</prgn> calls scripts from its installation
4619 methods when it needs to actually access data from the
4620 distribution. The core program <prgn>dselect</prgn> itself
4621 just calls these scripts and provides the package and access
4622 method selection interfaces. The installation methods are
4623 responsible for invoking <prgn>dpkg</prgn> as appropriate.
4627 Each installation method has three scripts:
4628 <list compact="compact">
4629 <item><p>Setup installation parameters.</p></item>
4630 <item><p>Update list of available packages.</p></item>
4631 <item><p>Install.</p></item>
4635 <prgn>dselect</prgn> searches for methods in
4636 <tt>/usr/lib/dpkg/methods</tt> and
4637 <tt>/usr/local/lib/dpkg/methods</tt>.
4640 <sect><heading>Functions of the method scripts
4644 The setup script is run just after the user has chosen an
4645 installation method. It should prompt the user for
4646 parameters like the site to NFS-mount or FTP from, the
4647 directory to use, or the directory or filesystem where the
4648 <tt>.deb</tt> files can be found, or the tape or floppy
4649 device to install from. It should store the responses under
4650 <tt>/var/lib/dpkg/methods</tt> - see below. If no available
4651 packages list is available it should perhaps offer to scan
4652 the available packages.
4656 The update script should obtain a list of available packages
4657 if possible, and run <tt>dpkg --update-avail</tt>, <tt>dpkg
4658 --merge-avail</tt> and/or <tt>dpkg --forget-old-unavail</tt>
4659 to load it into <prgn>dpkg</prgn> and <prgn>dselect</prgn>'s
4660 database of available packages. If no packages list was
4661 available and the user was offered and accepted the option
4662 of scanning the actual files available this scan should be
4663 done here, using <tt>dpkg --record-avail</tt>.
4667 The install script should feed all the available
4668 <tt>.deb</tt> files to <tt>dpkg --iGOEB</tt> (this is
4669 equivalent to <tt>dpkg --install
4670 --refuse-downgrade --selected-only --skip-same-version
4671 --auto-deconfigure</tt>). The <tt>-R</tt>
4672 (<tt>--recursive</tt>) option for traversing subdirectories
4673 may also be useful here).
4677 If any of these scripts needs to display a message for the
4678 user, it should wait for the user to hit `return' before
4679 exiting so that dselect doesn't immediately rewrite the
4684 If a method script succeeds (returns a zero exit status)
4685 <prgn>dselect</prgn> will return immediately to the main
4686 menu, with the `next' option highlighted ready for the user
4687 to select it. If it fails <prgn>dselect</prgn> will display
4688 a message and wait for the user to hit return.</p>
4691 <sect><heading>Location and arguments of the method scripts
4695 A set of scripts (henceforth known as a group) may provide
4696 several methods on the `main menu' with different behaviour.
4697 For example, there might be a generic get-packages-by-FTP
4698 group which might provide methods in the main menu for
4699 installation directly from one of the Debian mirror sites as
4700 well as for installation from a user-specified site.
4704 Each group of methods implemented by the same set of scripts
4705 should have a subdirectory
4706 <tt>/usr/lib/dpkg/methods/<var>group</var></tt> or
4707 <tt>/usr/local/lib/dpkg/methods/<var>group</var></tt>,
4709 <taglist compact="compact">
4710 <tag><tt>names</tt></tag>
4711 <item><p>a list of user-visible methods provided by these scripts.</p>
4713 <tag><tt>setup</tt></tag>
4714 <tag><tt>update</tt></tag>
4715 <tag><tt>install</tt></tag>
4716 <item><p>executable programs, the scripts themselves.</p>
4718 <tag><tt>desc.<var>option</var></tt></tag>
4719 <item><p>description file.</p></item>
4724 <tt>names</tt> will be formatted as a list of lines, each containing:
4726 <var>sequence</var> <var>method</var> <var>summary</var>
4730 <var>sequence</var> is a two-digit number that will be used
4731 much like <tt>rc.d</tt> prefixes to control the order in the
4732 main menu. If in doubt use 50.
4736 <var>method</var> is a name which is displayed by
4737 <prgn>dselect</prgn> as the name of the method, and which
4738 will be passed to <tt>setup</tt>, <tt>update</tt> and
4739 <tt>unpack</tt> as their first argument.
4743 <var>summary</var> is the brief description string for
4744 <prgn>dselect</prgn>'s menu.
4748 Each of the three scripts gets the same three arguments:
4749 <var>vardir</var>, <var>group</var> and <var>method</var>.
4750 <var>vardir</var> is the base directory for storing
4751 <prgn>dpkg</prgn> and <prgn>dselect</prgn>'s state, usually
4752 <tt>/var/lib/dpkg</tt>; this is passed in so that the
4753 <tt>--admindir</tt> option to <prgn>dselect</prgn> is
4758 Each option may have an extended description in
4759 <tt>desc.<var>option</var></tt>. This should be formatted
4760 like the extended description part of a <tt>Description</tt>
4761 field entry <em>shifted one character to the left</em>.
4765 <tt><var>vardir</var>/methods</tt> will exist, and a method
4767 <tt><var>vardir</var>/methods/<var>group</var></tt>
4768 directory to store its state.
4772 The group name and method name must follow the rules for C
4778 <chapt id="conversion"><heading>Conversion procedure from old
4783 This is a brief summary of the procedure for converting a
4784 pre-2.0.0.0-format source package into the new format.
4788 You are strongly advised to download and examine the <prgn>hello</prgn>
4789 package, and to read the section in the <prgn>dpkg</prgn> programmers'
4790 manual describing the source packaging tools. More detail about the
4791 exact functionality of these tools is available in
4792 <manref name="dpkg-source" section="1">.
4799 Download the original source code from wherever it can
4800 be found and do any rearrangement required to make it
4801 look like the original tree of the Debian source. Put
4803 <tt><var>package</var>-<var>upstream-version</var>.orig/</tt>
4805 <tt><var>package</var>_<var>upstream-version</var>.orig.tar.gz</tt>.
4811 Rename all files <tt>debian.*</tt> to <tt>debian/*</tt>.
4812 There may be some exceptions to this, but this is a good
4818 Edit the <tt>debian/changelog</tt> - create or rename it
4819 if necessary. Add a new revision to the top with the
4820 appropriate details, and a local variables entry to the
4821 bottom to set Emacs to the right mode:
4824 mode: debian-changelog
4832 Edit/create <tt>debian/control</tt>:
4833 <list compact="compact">
4836 Remove the <tt>Version</tt> field. If it is
4837 generated unusually (not equal to the source
4838 version) you must use the -v option to
4839 dpkg-gencontrol (see below). <tt>Section</tt>,
4840 <tt>Priority</tt>, <tt>Maintainer</tt> go above
4841 the first blank line, most of the rest
4848 Reorder the fields and add a blank line at an
4849 appropriate point, separating the source package
4850 fields from the binary package fields.
4855 <p>Add the <tt>Source</tt> field.</p></item>
4859 Add the <tt>Standards-Version</tt> field. (Please
4860 check out the Debian Policy Manual for details
4861 about this field.)</p>
4866 Change the <tt>Architecture</tt> field for each
4867 package to <tt>any</tt>, <tt>all</tt> or whatever.
4868 If there isn't an <tt>Architecture</tt> field add
4874 If any other use of sed or things used to happen
4875 to make the binary control files use
4876 <prgn>dpkg-gencontrol</prgn>'s variable
4877 substitution features to achieve the same effect.
4878 Use <tt>debian/substvars</tt> if you need to put
4879 unusally-generated information (apart from details
4880 of <tt>.deb</tt> files) in the <tt>.changes</tt>
4888 <p>Edit the <tt>debian/rules</tt>:
4889 <list compact="compact">
4892 Remove the <prgn>source</prgn> and
4893 <prgn>diff</prgn> and any <prgn>changes</prgn> and
4894 <prgn>dist</prgn> targets. These things now
4895 happen in a package-independent way and are not
4896 done by <tt>debian/rules</tt>.</p>
4900 Split the <prgn>binary</prgn> target into
4901 <prgn>binary-arch</prgn> and
4902 <prgn>binary-indep</prgn>; in many cases all of
4903 <prgn>binary</prgn> should go into
4904 <prgn>binary-arch</prgn>. Create the
4905 <prgn>binary</prgn> target and the unused of the
4906 two other <prgn>binary-*</prgn> targets if there
4907 is one - you can copy the ones from the
4908 <prgn>hello</prgn> package.</p>
4912 Change the <prgn>binary</prgn> target to use
4913 <prgn>dpkg-gencontrol</prgn> to make the package
4914 control file(s). Move it to after all the files
4915 have been installed but just before the last
4916 <prgn>chown</prgn> and <prgn>chmod</prgn> in the
4921 Change occurrences of <tt>debian-tmp</tt> to
4922 <tt>debian/tmp</tt>.</p>
4926 Change occurrences of
4927 <tt>debian.{post,pre}{inst,rm}</tt> to
4928 <tt>debian/*</tt>.</p>
4932 Remove the version number setting at the top, if
4937 Ensure that the package's Debian-specific and
4938 upstream changelogs are installed.</p>
4946 Change the package to use <prgn>dpkg-shlibdeps</prgn> to
4947 determine its shared library dependencies and substitute
4948 them in. Shared library dependencies should no longer
4949 be hardwired in the source package.</p>
4954 Check that the <tt>debian/README</tt> is really the
4955 copyright file, and if so rename it to
4956 <tt>debian/copyright</tt> and edit <tt>debian/rules</tt>
4957 to cope with this and to change the installation of the
4959 <tt>/usr/doc/<var>package</var>/copyright</tt> to
4960 <tt>/usr/doc/copyright/<var>package</var></tt>. If it
4961 isn't then find <tt>debian/copyright</tt> and decide
4962 what to do with the <tt>README</tt>.</p>
4966 <p>Check for various other anachronisms and problems:
4967 <list compact="compact">
4970 Remove any <tt>Package_Revision</tt>,
4971 <tt>Package-Revision</tt> or <tt>Revision</tt>
4976 Rename <tt>Optional</tt> to <tt>Suggests</tt>,
4977 <tt>Recommended</tt> to
4978 <tt>Recommends</tt>.</p>
4983 <tt>/usr/doc/examples/<var>package</var></tt> to
4984 <tt>/usr/doc/<var>package</var>/examples</tt>.</p>
4988 Make sure that manpages are installed
4993 Check that the description has an extended
4994 description, is well-formatted and meaningful and
4995 helpful to people wanting to know whether to
4996 install a package.</p>
5003 <p>Look everything over.</p></item>
5007 Do a test build using <tt>dpkg-buildpackage -us -uc -sa
5008 -r<var>whatever</var></tt>. Check the permissions and
5009 locations of files in the resulting package by examining
5010 the output of <tt>dpkg-deb --contents</tt>, and check
5011 that the source build happened OK. Test install the
5012 binary package(s) and test extract the source
5018 Sign the release: either rebuild everything with
5019 <tt>dpkg-buildpackage -sa</tt>, or PGP-sign the
5020 <tt>.dsc</tt>, rebuild the <tt>.changes</tt> using
5021 <tt>dpkg-genchanges -sa</tt>, and then PGP-sign the
5022 <tt>.changes</tt>.</p>
5029 The use of <tt>-sa</tt> on <prgn>dpkg-buildpackage</prgn> and
5030 <prgn>dpkg-genchanges</prgn> is important when doing the first
5031 build/uploading of a new-format source package. Unless this
5032 happens to be Debian revision <tt>0</tt> or <tt>1</tt> by
5033 default the original source tarfile will not be included in
5034 the uploaded files listed in the <tt>.changes</tt> file, and
5035 so it won't be installed on the FTP site. <tt>-sa</tt>
5036 requests that the original source be included