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10 <title>Debian Policy Manual</title>
11 <author><ref id="authors"></author>
12 <version>version &version;, &date;</version>
15 This manual describes the policy requirements for the Debian
16 GNU/Linux distribution. This includes the structure and
17 contents of the Debian archive and several design issues of
18 the operating system, as well as technical requirements that
19 each package must satisfy to be included in the distribution.
24 Copyright © 1996,1997,1998 Ian Jackson
25 and Christian Schwarz.
28 This manual is free software; you may redistribute it and/or
29 modify it under the terms of the GNU General Public License
30 as published by the Free Software Foundation; either version
31 2, or (at your option) any later version.
35 This is distributed in the hope that it will be useful, but
36 <em>without any warranty</em>; without even the implied
37 warranty of merchantability or fitness for a particular
38 purpose. See the GNU General Public License for more
43 A copy of the GNU General Public License is available as
44 <file>/usr/share/common-licenses/GPL</file> in the Debian GNU/Linux
45 distribution or on the World Wide Web at
46 <url id="http://www.gnu.org/copyleft/gpl.html"
47 name="the GNU General Public Licence">. You can also
48 obtain it by writing to the Free Software Foundation, Inc.,
49 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA.
57 <heading>About this manual</heading>
59 <heading>Scope</heading>
61 This manual describes the policy requirements for the Debian
62 GNU/Linux distribution. This includes the structure and
63 contents of the Debian archive and several design issues of the
64 operating system, as well as technical requirements that
65 each package must satisfy to be included in the
71 This manual also describes Debian policy as it relates to
72 creating Debian packages. It is not a tutorial on how to build
73 packages, nor is it exhaustive where it comes to describing
74 the behavior of the packaging system. Instead, this manual
75 attempts to define the interface to the package management
76 system that the developers have to be conversant with.<footnote>
78 Informally, the criteria used for inclusion is that the
79 material meet one of the following requirements:
80 <taglist compact="compact">
81 <tag>Standard interfaces</tag>
84 The material presented represents an interface to
85 the packaging system that is mandated for use, and
86 is used by, a significant number of packages, and
87 therefore should not be changed without peer
88 review. Package maintainers can then rely on this
89 interfaces not changing, and the package
90 management software authors need to ensure
91 compatibility with these interface
92 definitions. (Control file and changelog file
93 formats are examples.)
96 <tag>Chosen Convention</tag>
99 If there are a number of technically viable choices
100 that can be made, but one needs to select one of
101 these options for inter-operability. The version
102 number format is one example.
106 Please note that these are not mutually exclusive;
107 selected conventions often become parts of standard
114 The footnotes present in this manual are
115 merely informative, and are not part of Debian policy itself.
119 In this manual, the words <em>must</em>, <em>should</em> and
120 <em>may</em>, and the adjectives <em>required</em>,
121 <em>recommended</em> and <em>optional</em>, are used to
122 distinguish the significance of the various guidelines in
123 this policy document. Packages that do not conform to the
124 guidelines denoted by <em>must</em> (or <em>required</em>)
125 will generally not be considered acceptable for the Debian
126 distribution. Non-conformance with guidelines denoted by
127 <em>should</em> (or <em>recommended</em>) will generally be
128 considered a bug, but will not necessarily render a package
129 unsuitable for distribution. Guidelines denoted by
130 <em>may</em> (or <em>optional</em>) are truly optional and
131 adherence is left to the maintainer's discretion.
134 These classifications are roughly equivalent to the bug
135 severities <em>serious</em> (for <em>must</em> or
136 <em>required</em> directive violations), <em>minor</em>,
137 <em>normal</em> or <em>important</em>
138 (for <em>should</em> or <em>recommended</em> directive
139 violations) and <em>wishlist</em> (for <em>optional</em>
141 <p>Compare RFC 2119. Note, however, that these words are
142 used in a different way in this document.</p>
146 Much of the information presented in this manual will be
147 useful even when building a package which is to be
148 distributed in some other way or is intended for local use
154 <heading>New versions of this document</heading>
156 The current version of this document is always accessible
157 from the Debian FTP server <ftpsite>ftp.debian.org</ftpsite>
159 <ftppath>/debian/doc/package-developer/policy.txt.gz</ftppath>
160 (also available from the same directory are several other
161 formats: <file>policy.html.tar.gz</file>, <file>policy.pdf.gz</file>
162 and <file>policy.ps.gz</file>) or from the <url
163 id="http://www.debian.org/doc/debian-policy/" name="Debian
164 Policy Manual"> webpage.</p>
167 In addition, this manual is distributed via the Debian package
168 <file>debian-policy</file>.
172 The <tt>debian-policy</tt> package also includes the file
173 <file>upgrading-checklist.txt</file> which indicates policy
174 changes between versions of this document.
179 <heading>Authors and Maintainers</heading>
182 Originally called "Debian GNU/Linux Policy Manual", this
183 manual was initially written in 1996 by Ian Jackson.
184 It was revised on November 27th, 1996 by David A. Morris.
185 Christian Schwarz added new sections on March 15th, 1997,
186 and reworked/restructured it in April-July 1997.
187 Christoph Lameter contributed the "Web Standard".
188 Julian Gilbey largely restructured it in 2001.
192 Since September 1998, the responsibility for the contents of
193 this document lies on the debian-policy mailing list. Proposals
194 are discussed there and inserted into policy after a certain
195 consensus is established.
196 <!-- insert shameless policy-process plug here eventually -->
197 The actual editing is done by a group of maintainers that have
198 no editorial powers. These are the current maintainers:
201 <item>Julian Gilbey</item>
202 <item>Branden Robinson</item>
203 <item>Josip Rodin</item>
204 <item>Manoj Srivastava</item>
209 While the authors of this document have tried hard to avoid
210 typos and other errors, these do still occur. If you discover
211 an error in this manual or if you want to give any
212 comments, suggestions, or criticisms please send an email to
213 the Debian Policy List,
214 <email>debian-policy@lists.debian.org</email>, or submit a
215 bug report against the <tt>debian-policy</tt> package.
219 Please do not try to reach the individual authors or maintainers
220 of the Policy Manual regarding changes to the Policy.
226 <heading>The Debian Archive</heading>
228 The Debian GNU/Linux system is maintained and distributed as a
229 collection of <em>packages</em>. Since there are so many of
230 them (currently well over 6000), they are split into
231 <em>sections</em> and given <em>priorities</em> to simplify
232 the handling of them.
235 The effort of the Debian project is to build a free operating
236 system, but not every package we want to make accessible is
237 <em>free</em> in our sense (see the Debian Free Software
238 Guidelines, below), or may be imported/exported without
239 restrictions. Thus, the archive is split into the sections
240 <em>main</em>, <em>non-free</em>, <em>contrib</em>,
241 <em>non-US/main</em>, <em>non-US/non-free</em>, and
242 <em>non-US/contrib</em>. The sections are explained in detail
247 The <em>main</em> and the <em>non-US/main</em> sections
248 together form the <em>Debian GNU/Linux distribution</em>.
252 Packages in the other sections are not considered to be part
253 of the Debian distribution, although we support their use and
254 provide infrastructure for them (such as our bug-tracking
255 system and mailing lists). This Debian Policy Manual applies
256 to these packages as well.</p>
258 <sect id="pkgcopyright">
259 <heading>Package copyright and sections</heading>
261 The aims of this section are:
263 <list compact="compact">
265 <p>to allow us to make as much software available as we
269 <p>to allow us to encourage everyone to write free
273 <p>to allow us to make it easy for people to produce
274 CD-ROMs of our system without violating any licenses,
275 import/export restrictions, or any other laws.</p>
280 <heading>The Debian Free Software Guidelines</heading>
282 The Debian Free Software Guidelines (DFSG) form our
283 definition of "free software". These are:
285 <tag>Free Redistribution
289 The license of a Debian component may not restrict any
290 party from selling or giving away the software as a
291 component of an aggregate software distribution
292 containing programs from several different
293 sources. The license may not require a royalty or
294 other fee for such sale.
301 The program must include source code, and must allow
302 distribution in source code as well as compiled form.
309 The license must allow modifications and derived
310 works, and must allow them to be distributed under the
311 same terms as the license of the original software.
314 <tag>Integrity of The Author's Source Code
318 The license may restrict source-code from being
319 distributed in modified form <em>only</em> if the
320 license allows the distribution of "patch files"
321 with the source code for the purpose of modifying the
322 program at build time. The license must explicitly
323 permit distribution of software built from modified
324 source code. The license may require derived works to
325 carry a different name or version number from the
326 original software. (This is a compromise. The Debian
327 Project encourages all authors to not restrict any
328 files, source or binary, from being modified.)
331 <tag>No Discrimination Against Persons or Groups
335 The license must not discriminate against any person
339 <tag>No Discrimination Against Fields of Endeavor
343 The license must not restrict anyone from making use
344 of the program in a specific field of endeavor. For
345 example, it may not restrict the program from being
346 used in a business, or from being used for genetic
350 <tag>Distribution of License
354 The rights attached to the program must apply to all
355 to whom the program is redistributed without the need
356 for execution of an additional license by those
360 <tag>License Must Not Be Specific to Debian
364 The rights attached to the program must not depend on
365 the program's being part of a Debian system. If the
366 program is extracted from Debian and used or
367 distributed without Debian but otherwise within the
368 terms of the program's license, all parties to whom
369 the program is redistributed must have the same
370 rights as those that are granted in conjunction with
374 <tag>License Must Not Contaminate Other Software
378 The license must not place restrictions on other
379 software that is distributed along with the licensed
380 software. For example, the license must not insist
381 that all other programs distributed on the same medium
382 must be free software.
385 <tag>Example Licenses
389 The "GPL," "BSD," and "Artistic" licenses are examples of
390 licenses that we consider <em>free</em>.
397 <heading>The main section</heading>
399 Every package in <em>main</em> and <em>non-US/main</em>
400 must comply with the DFSG (Debian Free Software
404 In addition, the packages in <em>main</em>
405 <list compact="compact">
408 must not require a package outside of <em>main</em>
409 for compilation or execution (thus, the package must
410 not declare a "Depends", "Recommends", or
411 "Build-Depends" relationship on a non-<em>main</em>
417 must not be so buggy that we refuse to support them,
423 must meet all policy requirements presented in this
430 Similarly, the packages in <em>non-US/main</em>
431 <list compact="compact">
434 must not require a package outside of <em>main</em>
435 or <em>non-US/main</em> for compilation or
441 must not be so buggy that we refuse to support them,
446 must meet all policy requirements presented in this
454 <heading>The contrib section</heading>
456 Every package in <em>contrib</em> and
457 <em>non-US/contrib</em> must comply with the DFSG.
461 In addition, the packages in <em>contrib</em> and
462 <em>non-US/contrib</em>
463 <list compact="compact">
466 must not be so buggy that we refuse to support them,
472 must meet all policy requirements presented in this
480 Furthermore, packages in <em>contrib</em> must not require
481 a package in a <em>non-US</em> section for compilation or
486 Examples of packages which would be included in
487 <em>contrib</em> or <em>non-US/contrib</em> are:
488 <list compact="compact">
491 free packages which require <em>contrib</em>,
492 <em>non-free</em> packages or packages which are not
493 in our archive at all for compilation or execution,
499 wrapper packages or other sorts of free accessories for
507 <heading>The non-free section</heading>
509 Packages must be placed in <em>non-free</em> or
510 <em>non-US/non-free</em> if they are not compliant with
511 the DFSG or are encumbered by patents or other legal
512 issues that make their distribution problematic.
515 In addition, the packages in <em>non-free</em> and
516 <em>non-US/non-free</em>
517 <list compact="compact">
520 must not be so buggy that we refuse to support them,
526 must meet all policy requirements presented in this
527 manual that it is possible for them to meet.<footnote>
529 It is possible that there are policy
530 requirements which the package is unable to
531 meet, for example, if the source is
532 unavailable. These situations will need to be
533 handled on a case-by-case basis.
543 <heading>The non-US sections</heading>
545 Non-free programs with cryptographic program code need to
546 be stored on the <em>non-us</em> server because of export
547 restrictions of the U.S.
550 Programs which use patented algorithms that have a
551 restrictied license also need to be stored on "non-us",
552 since that is located in a country where it is not allowed
553 to patent algorithms.
556 A package depends on another package which is distributed
557 via the non-us server has to be stored on the non-us
562 <heading>Further copyright considerations</heading>
564 Every package must be accompanied by a verbatim copy of
565 its copyright and distribution license in the file
566 <file>/usr/share/doc/<var>package</var>/copyright</file>
567 (see <ref id="copyrightfile"> for further details).
570 We reserve the right to restrict files from being included
571 anywhere in our archives if
572 <list compact="compact">
575 their use or distribution would break a law,
580 there is an ethical conflict in their distribution or
586 we would have to sign a license for them, or
591 their distribution would conflict with other project
599 Programs whose authors encourage the user to make
600 donations are fine for the main distribution, provided
601 that the authors do not claim that not donating is
602 immoral, unethical, illegal or something similar; in such
603 a case they must go in <em>non-free</em>.</p>
606 Packages whose copyright permission notices (or patent
607 problems) do not even allow redistribution of binaries
608 only, and where no special permission has been obtained,
609 must not be placed on the Debian FTP site and its mirrors
613 Note that under international copyright law (this applies
614 in the United States, too), <em>no</em> distribution or
615 modification of a work is allowed without an explicit
616 notice saying so. Therefore a program without a copyright
617 notice <em>is</em> copyrighted and you may not do anything
618 to it without risking being sued! Likewise if a program
619 has a copyright notice but no statement saying what is
620 permitted then nothing is permitted.</p>
623 Many authors are unaware of the problems that restrictive
624 copyrights (or lack of copyright notices) can cause for
625 the users of their supposedly-free software. It is often
626 worthwhile contacting such authors diplomatically to ask
627 them to modify their license terms. However, this can be a
628 politically difficult thing to do and you should ask for
629 advice on the <tt>debian-legal</tt> mailing list first, as
634 When in doubt about a copyright, send mail to
635 <email>debian-legal@lists.debian.org</email>. Be prepared
636 to provide us with the copyright statement. Software
637 covered by the GPL, public domain software and BSD-like
638 copyrights are safe; be wary of the phrases "commercial
639 use prohibited" and "distribution restricted".
643 <heading>Subsections</heading>
646 The packages in the sections <em>main</em>,
647 <em>contrib</em> and <em>non-free</em> are grouped further
648 into <em>subsections</em> to simplify handling.
652 The section and subsection for each package should be
653 specified in the package's <tt>Section</tt> control
654 record. However, the maintainer of the Debian archive
655 may override this selection to ensure the consistency of
656 the Debian distribution. The <tt>Section</tt> field
657 should be of the form:
658 <list compact="compact">
661 <em>subsection</em> if the package is in the
662 <em>main</em> section,
667 <em>section/subsection</em> if the package is in
668 the <em>contrib</em> or <em>non-free</em> section,
674 <tt>non-US</tt>, <tt>non-US/contrib</tt> or
675 <tt>non-US/non-free</tt> if the package is in
676 <em>non-US/main</em>, <em>non-US/contrib</em> or
677 <em>non-US/non-free</em> respectively.
684 The Debian archive maintainers provide the authoritative
685 list of subsections. At present, they are:
686 <em>admin</em>, <em>base</em>, <em>comm</em>,
687 <em>contrib</em>, <em>devel</em>, <em>doc</em>,
688 <em>editors</em>, <em>electronics</em>, <em>games</em>,
689 <em>graphics</em>, <em>hamradio</em>,
690 <em>interpreters</em>, <em>libs</em>, <em>mail</em>,
691 <em>math</em>, <em>misc</em>, <em>net</em>, <em>news</em>,
692 <em>non-US</em>, <em>non-free</em>, <em>oldlibs</em>,
693 <em>otherosfs</em>, <em>science</em>, <em>shells</em>,
694 <em>sound</em>, <em>tex</em>, <em>text</em>,
695 <em>utils</em>, <em>web</em>, <em>x11</em>.
699 <heading>Priorities</heading>
702 Each package should have a <em>priority</em> value, which is
703 included in the package's <em>control record</em>. This
704 information is used by the Debian package management tools
705 to separate high-priority packages from less-important
709 The following <em>priority levels</em> are recognised by the
710 Debian package management tools.
712 <tag><tt>required</tt></tag>
715 Packages which are necessary for the proper
716 functioning of the system. You must not remove these
717 packages or your system may become totally broken and
718 you may not even be able to use <prgn>dpkg</prgn> to
719 put things back. Systems with only the
720 <tt>required</tt> packages are probably unusable, but
721 they do have enough functionality to allow the
722 sysadmin to boot and install more software.</p>
724 <tag><tt>important</tt></tag>
727 Important programs, including those which one would
728 expect to find on any Unix-like system. If the
729 expectation is that an experienced Unix person who
730 found it missing would say "What on earth is going on,
731 where is <prgn>foo</prgn>?", it must be an
732 <tt>important</tt> package.<footnote>
734 This is an important criterion because we are
735 trying to produce, amongst other things, a free
739 Other packages without which the system will not run
740 well or be usable must also have priority
741 <tt>important</tt>. This does
742 <em>not</em> include Emacs, the X Window System, TeX
743 or any other large applications. The
744 <tt>important</tt> packages are just a bare minimum of
745 commonly-expected and necessary tools.</p>
747 <tag><tt>standard</tt></tag>
750 These packages provide a reasonably small but not too
751 limited character-mode system. This is what will be
752 installed by default if the user doesn't select anything
753 else. It doesn't include many large applications.</p>
755 <tag><tt>optional</tt></tag>
758 (In a sense everything that isn't required is
759 optional, but that's not what is meant here.) This is
760 all the software that you might reasonably want to
761 install if you didn't know what it was and don't have
762 specialized requirements. This is a much larger system
763 and includes the X Window System, a full TeX
764 distribution, and many applications. Note that
765 optional packages should not conflict with each other.
768 <tag><tt>extra</tt></tag>
771 This contains all packages that conflict with others
772 with required, important, standard or optional
773 priorities, or are only likely to be useful if you
774 already know what they are or have specialised
781 Packages must not depend on packages with lower priority
782 values (excluding build-time dependencies). In order to
783 ensure this, the priorities of one or more packages may need
789 <heading>Binary packages</heading>
792 The Debian GNU/Linux distribution is based on the Debian
793 package management system, called <prgn>dpkg</prgn>. Thus,
794 all packages in the Debian distribution must be provided
795 in the <tt>.deb</tt> file format.</p>
799 <heading>The package name</heading>
802 Every package must have a name that's unique within the Debian
806 Package names must consist of lower case letters
807 (<tt>a-z</tt>), digits (<tt>0-9</tt>), plus (<tt>+</tt>)
808 and minus (<tt>-</tt>) signs, and periods (<tt>.</tt>).
809 They must be at least two characters long and must start
810 with an alphanumeric character.
814 The package name is part of the file name of the
815 <tt>.deb</tt> file and is included in the control field
821 <heading>The maintainer of a package</heading>
823 Every package must have a Debian maintainer (the
824 maintainer may be one person or a group of people
825 reachable from a common email address, such as a mailing
826 list). The maintainer is responsible for ensuring that
827 the package is placed in the appropriate distributions.
831 The maintainer must be specified in the
832 <tt>Maintainer</tt> control field with their correct name
833 and a working email address. If one person maintains
834 several packages, he/she should try to avoid having
835 different forms of their name and email address in
836 the <tt>Maintainer</tt> fields of those packages.
840 If the maintainer of a package quits from the Debian
841 project, "Debian QA Group"
842 <email>packages@qa.debian.org</email> takes over the
843 maintainership of the package until someone else
844 volunteers for that task. These packages are called
845 <em>orphaned packages</em>.<footnote>
847 The detailed procedure for doing this gracefully can
848 be found in the Debian Developer's Reference, either
849 in the <tt>developers-reference</tt> package, or on
850 the Debian FTP server
851 <ftpsite>ftp.debian.org</ftpsite> as
852 <ftppath>/debian/doc/package-developer/developers-reference.txt.gz</ftppath>
854 id="http://www.debian.org/doc/packaging-manuals/developers-reference/"
855 name="Debian Developer's Reference"> webpage.
863 <heading>The description of a package</heading>
866 Every Debian package must have an extended description
867 stored in the appropriate field of the control record.</p>
870 The description should be written so that it gives the
871 system administrator enough information to decide whether
872 to install the package. This description should not just
873 be copied verbatim from the program's documentation.
874 Instructions for configuring or using the package should
875 not be included (that is what installation scripts,
876 manual pages, info files, etc., are for). Copyright
877 statements and other administrivia should not be included
878 either (that is what the copyright file is for).
882 Please refer to <ref id="descriptions"> for more information.
889 <heading>Dependencies</heading>
892 Every package must specify the dependency information
893 about other packages that are required for the first to
897 For example, a dependency entry must be provided for any
898 shared libraries required by a dynamically-linked executable
899 binary in a package.</p>
902 Packages are not required to declare any dependencies they
903 have on other packages which are marked <tt>Essential</tt>
904 (see below), and should not do so unless they depend on a
905 particular version of that package.</p>
908 Sometimes, a package requires another package to be installed
909 <em>and</em> configured before it can be installed. In this
910 case, you must specify a <tt>Pre-Depends</tt> entry for
914 You should not specify a <tt>Pre-Depends</tt> entry for a
915 package before this has been discussed on the
916 <tt>debian-devel</tt> mailing list and a consensus about
917 doing that has been reached.</p></sect1>
920 <sect1 id="virtual_pkg_sect">
921 <heading>Virtual packages</heading>
924 Sometimes, there are several packages which offer
925 more-or-less the same functionality. In this case, it's
926 useful to define a <em>virtual package</em> whose name
927 describes that common functionality. (The virtual
928 packages only exist logically, not physically; that's why
929 they are called <em>virtual</em>.) The packages with this
930 particular function will then <em>provide</em> the virtual
931 package. Thus, any other package requiring that function
932 can simply depend on the virtual package without having to
933 specify all possible packages individually.</p>
936 All packages should use virtual package names where
937 appropriate, and arrange to create new ones if necessary.
938 They should not use virtual package names (except privately,
939 amongst a cooperating group of packages) unless they have
940 been agreed upon and appear in the list of virtual package
941 names. (See also <ref id="virtual">)</p>
944 The latest version of the authoritative list of virtual
945 package names can be found on
946 <ftpsite>ftp.debian.org</ftpsite> in
947 <ftppath>/debian/doc/package-developer/virtual-package-names-list.txt</ftppath>
948 or your local mirror. In addition, it is included in the
949 <tt>debian-policy</tt> package. The procedure for updating
950 the list is described at the top of the file.</p></sect1>
954 <heading>Base system</heading>
957 The <tt>base system</tt> is a minimum subset of the Debian
958 GNU/Linux system that is installed before everything else
959 on a new system. Thus, only very few packages are allowed
960 to go into the <tt>base</tt> section to keep the required
961 disk usage very small.</p>
964 Most of these packages will have the priority value
965 <tt>required</tt> or at least <tt>important</tt>, and many
966 of them will be tagged <tt>essential</tt> (see below).</p>
973 <heading>Essential packages</heading>
976 Some packages are tagged <tt>essential</tt>. (They have
977 <tt>Essential: yes</tt> in their package control record.)
978 This flag is used for packages that are <em>essential</em>
982 Since these packages cannot be easily removed (one has to
983 specify an extra <em>force option</em> to
984 <prgn>dpkg</prgn> to do so), this flag must not be used
985 unless absolutely necessary. A shared library package
986 must not be tagged <tt>essential</tt>; dependencies will
987 prevent its premature removal, and we need to be able to
988 remove it when it has been superseded.
992 Since dpkg will not prevent upgrading of other packages
993 while an <tt>essential</tt> package is in an unconfigured
994 state, all <tt>essential</tt> packages must supply all of
995 their core functionality even when unconfigured. If the
996 package cannot satisfy this requirement it must not be
997 tagged as essential, and any packages depending on this
998 package must instead have explicit dependency fields as
1003 You must not tag any packages <tt>essential</tt> before
1004 this has been discussed on the <tt>debian-devel</tt>
1005 mailing list and a consensus about doing that has been
1010 <heading>Tasks</heading>
1013 The Debian install process allows the user to choose from
1014 a number of common tasks which a Debian system can be used to
1015 perform. Selecting a task with <prgn>tasksel</prgn> causes
1016 a set of packages that are useful in performing that task to be
1021 This set of packages is all available packages which have the
1022 name of the selected task in the <tt>Task</tt> field of their
1023 control file. The format of this field is a list of tasks,
1024 separated by commas.
1028 You should not tag any packages as belonging to a task
1029 before this has been discussed on the
1030 <em>debian-devel</em> mailing list and a consensus about
1031 doing that has been reached.
1035 For third parties (and historical reasons), tasksel also
1036 supports constructing tasks based on <em>task
1037 packages</em>. These are packages whose names begin with
1038 <em>task-</em>. Task packages should not be included in the
1043 <sect1 id="maintscripts">
1044 <heading>Maintainer Scripts</heading>
1047 The package installation scripts should avoid producing
1048 output which it is unnecessary for the user to see and
1049 should rely on <prgn>dpkg</prgn> to stave off boredom on
1050 the part of a user installing many packages. This means,
1051 amongst other things, using the <tt>--quiet</tt> option on
1052 <prgn>install-info</prgn>.</p>
1055 Errors which occur during the execution of an installation
1056 script must be checked and the installation must not
1057 continue after an error.
1061 Note that in general <ref id="scripts"> applies to package
1062 maintainer scripts, too.
1066 You should not use <prgn>dpkg-divert</prgn> on a file
1067 belonging to another package without consulting the
1068 maintainer of that package first.
1072 All packages which supply an instance of a common command
1073 name (or, in general, filename) should generally use
1074 <prgn>update-alternatives</prgn>, so that they may be
1075 installed together. If <prgn>update-alternatives</prgn>
1076 is not used, then each package must use
1077 <tt>Conflicts</tt> to ensure that other packages are
1078 de-installed. (In this case, it may be appropriate to
1079 specify a conflict against earlier versions of something
1080 that previously did not use
1081 <prgn>update-alternatives</prgn>; this is an exception to
1082 the usual rule that versioned conflicts should be
1088 <heading>Prompting in maintainer scripts</heading>
1090 Package maintainer scripts may prompt the user if
1091 necessary. Prompting may be accomplished by hand, or by
1092 communicating with a program, such as
1093 <prgn>debconf</prgn>, which conforms to the Debian
1094 Configuration management specification, version 2 or
1095 higher. These are included in the
1096 <file>debconf_specification</file> files in the
1097 <package>debian-policy</package> package.
1098 You may also find this file on the FTP site
1099 <ftpsite>ftp.debian.org</ftpsite> in
1100 <ftppath>/debian/doc/package-developer/debconf_specification.txt.gz</ftppath>
1101 or on your local mirror.<footnote>
1103 4% of Debian packages [see <url
1104 id="http://kitenet.net/programs/debconf/stats/"
1105 name="Debconf stats">] currently use
1106 <package>debconf</package> to prompt the user at
1107 install time, and this number is growing daily. The
1108 benefits of using debconf are briefly explained at
1110 id="http://kitenet.net/doc/debconf-doc/introduction.html"
1111 name="Debconf introduction">; they include
1112 preconfiguration, (mostly) noninteractive
1113 installation, elimination of redundant prompting,
1114 consistency of user interface, etc.
1117 With this increasing number of packages using
1118 <package>debconf</package>, plus the existance of a
1119 nascent second implementation of the Debian
1120 configuration management system
1121 (<package>cdebconf</package>), and the stabilization
1122 of the protocol these things use, the time has
1123 finally come to reflect the use of these things in
1130 Packages which use the Debian Configuration management
1131 specification may contain an additional
1132 <prgn>config</prgn> script and a <tt>templates</tt>
1133 file in their control archive. The <prgn>config</prgn>
1134 script might be run before the <prgn>preinst</prgn>
1135 script, and before the package is unpacked or any of its
1136 dependencies or pre-dependancies are satisfied.
1137 Therefore it must work using only the tools present in
1138 <em>essential</em> packages.<footnote>
1140 <package>Debconf</package> or another tool that
1141 implements the Debian Configuration management
1142 specification will also be installed, and any
1143 versioned dependencies on it will be satisfied
1144 before preconfiguration begins.
1150 Packages should try to minimize the amount of prompting
1151 they need to do, and they should ensure that the user
1152 will only ever be asked each question once. This means
1153 that packages should try to use appropriate shared
1154 configuration files (such as <file>/etc/papersize</file> and
1155 <file>/etc/news/server</file>), and shared
1156 <package>debconf</package> variables rather than each
1157 prompting for their own list of required pieces of
1162 It also means that an upgrade should not ask the same
1163 questions again, unless the user has used <tt>dpkg
1164 --purge</tt> to remove the package's configuration. The
1165 answers to configuration questions should be stored in an
1166 appropriate place in <file>/etc</file> so that the user can
1167 modify them, and how this has been done should be
1171 If a package has a vitally important piece of
1172 information to pass to the user (such as "don't run me
1173 as I am, you must edit the following configuration files
1174 first or you risk your system emitting badly-formatted
1175 messages"), it should display this in the
1176 <prgn>config</prgn> or <prgn>postinst</prgn> script and
1177 prompt the user to hit return to acknowledge the
1178 message. Copyright messages do not count as vitally
1179 important (they belong in
1180 <file>/usr/share/doc/<var>package</var>/copyright</file>);
1181 neither do instructions on how to use a program (these
1182 should be in on-line documentation, where all the users
1186 Any necessary prompting should almost always be confined
1187 to the <prgn>config</prgn> or <prgn>postinst</prgn>
1188 script. If it is done in the <prgn>postinst</prgn>, it
1189 should be protected with a conditional so that
1190 unnecessary prompting doesn't happen if a package's
1191 installation fails and the <prgn>postinst</prgn> is
1192 called with <tt>abort-upgrade</tt>,
1193 <tt>abort-remove</tt> or <tt>abort-deconfigure</tt>.</p>
1198 <heading>Source packages</heading>
1200 <sect1 id="standardsversion">
1201 <heading>Standards conformance</heading>
1204 In the source package's <tt>Standards-Version</tt> control
1205 field, you should specify the most recent version number
1206 of this policy document with which your package complied
1207 when it was last updated. The current version number is
1212 This information may be used to file bug reports
1213 automatically if your package becomes too much out of
1218 The version number has four components: major and minor
1219 version number and major and minor patch level. When the
1220 standards change in a way that requires every package to
1221 change the major number will be changed. Significant
1222 changes that will require work in many packages will be
1223 signaled by a change to the minor number. The major patch
1224 level will be changed for any change to the meaning of the
1225 standards, however small; the minor patch level will be
1226 changed when only cosmetic, typographical or other edits
1227 are made which neither change the meaning of the document
1228 nor affect the contents of packages.</p>
1231 Thus only the first three components of the policy version
1232 are significant in the <em>Standards-Version</em> control
1233 field, and so either these three components or the all
1234 four components may be specified.<footnote>
1236 In the past, people specified the full version number
1237 in the Standards-Version field, for example "2.3.0.0".
1238 Since minor patch-level changes don"t introduce new
1239 policy, it was thought it would be better to relax
1240 policy and only require the first 3 components to be
1241 specified, in this example "2.3.0". All four
1242 components may still be used if someone wishes to do
1249 You should regularly, and especially if your package has
1250 become out of date, check for the newest Policy Manual
1251 available and update your package, if necessary. When your
1252 package complies with the new standards you should update the
1253 <tt>Standards-Version</tt> source package field and
1254 release it.<footnote>
1256 See the file <file>upgrading-checklist</file> for
1257 information about policy which has changed between
1258 different versions of this document.
1265 <sect1 id="pkg-relations">
1266 <heading>Package relationships</heading>
1269 Source packages should specify which binary packages they
1270 require to be installed or not to be installed in order to
1271 build correctly. For example, if building a package
1272 requires a certain compiler, then the compiler should be
1273 specified as a build-time dependency.
1277 It is not necessary to explicitly specify build-time
1278 relationships on a minimal set of packages that are always
1279 needed to compile, link and put in a Debian package a
1280 standard "Hello World!" program written in C or C++. The
1281 required packages are called <em>build-essential</em>, and
1282 an informational list can be found in
1283 <file>/usr/share/doc/build-essential/list</file> (which is
1284 contained in the <tt>build-essential</tt>
1287 <list compact="compact">
1289 <p>This allows maintaining the list separately
1290 from the policy documents (the list does not
1291 need the kind of control that the policy
1297 Having a separate package allows one to install
1298 the build-essential packages on a machine, as
1299 well as allowing other packages such as tasks to
1300 require installation of the build-essential
1301 packages using the depends relation.
1306 The separate package allows bug reports against
1307 the list to be categorized separately from
1308 the policy management process in the BTS.
1318 When specifying the set of build-time dependencies, one
1319 should list only those packages explicitly required by the
1320 build. It is not necessary to list packages which are
1321 required merely because some other package in the list of
1322 build-time dependencies depends on them.<footnote>
1324 The reason for this is that dependencies change, and
1325 you should list all those packages, and <em>only</em>
1326 those packages that <em>you</em> need directly. What
1327 others need is their business. For example, if you
1328 only link against <file>libimlib</file>, you will need to
1329 build-depend on <package>libimlib2-dev</package> but
1330 not against any <tt>libjpeg*</tt> packages, even
1331 though <tt>libimlib2-dev</tt> currently depends on
1332 them: installation of <package>libimlib2-dev</package>
1333 will automatically ensure that all of its run-time
1334 dependencies are satisfied.
1340 If build-time dependencies are specified, it must be
1341 possible to build the package and produce working binaries
1342 on a system with only essential and build-essential
1343 packages installed and also those required to satisfy the
1344 build-time relationships (including any implied
1345 relationships). In particular, this means that version
1346 clauses should be used rigorously in build-time
1347 relationships so that one cannot produce bad or
1348 inconsistently configured packages when the relationships
1349 are properly satisfied.
1353 <ref id="relationships"> explains the technical details.
1357 <heading>Changes to the upstream sources</heading>
1360 If changes to the source code are made that are not
1361 specific to the needs of the Debian system, they should be
1362 sent to the upstream authors in whatever form they prefer
1363 so as to be included in the upstream version of the
1367 If you need to configure the package differently for
1368 Debian or for Linux, and the upstream source doesn't
1369 provide a way to do so, you should add such configuration
1370 facilities (for example, a new <prgn>autoconf</prgn> test
1371 or <tt>#define</tt>) and send the patch to the upstream
1372 authors, with the default set to the way they originally
1373 had it. You can then easily override the default in your
1374 <file>debian/rules</file> or wherever is appropriate.</p>
1377 You should make sure that the <prgn>configure</prgn> utility
1378 detects the correct architecture specification string
1379 (refer to <ref id="arch-spec"> for details).</p>
1382 If you need to edit a <prgn>Makefile</prgn> where
1383 GNU-style <prgn>configure</prgn> scripts are used, you
1384 should edit the <file>.in</file> files rather than editing the
1385 <prgn>Makefile</prgn> directly. This allows the user to
1386 reconfigure the package if necessary. You should
1387 <em>not</em> configure the package and edit the generated
1388 <prgn>Makefile</prgn>! This makes it impossible for
1389 someone else to later reconfigure the package.</p>
1392 You should document your changes and updates to the source
1393 package properly in the <file>debian/changelog</file> file.
1394 For more information, please see <ref id="changelogs">.
1400 <heading>Error trapping in makefiles</heading>
1403 When <prgn>make</prgn> invokes a command in a makefile
1404 (including your package's upstream makefiles and
1405 <file>debian/rules</file>), it does so using <prgn>sh</prgn>. This
1406 means that <prgn>sh</prgn>'s usual bad error handling
1407 properties apply: if you include a miniature script as one
1408 of the commands in your makefile you'll find that if you
1409 don't do anything about it then errors are not detected
1410 and <prgn>make</prgn> will blithely continue after
1414 Every time you put more than one shell command (this
1415 includes using a loop) in a makefile command you
1416 must make sure that errors are trapped. For
1417 simple compound commands, such as changing directory and
1418 then running a program, using <tt>&&</tt> rather
1419 than semicolon as a command separator is sufficient. For
1420 more complex commands including most loops and
1421 conditionals you should include a separate <tt>set -e</tt>
1422 command at the start of every makefile command that's
1423 actually one of these miniature shell scripts.</p></sect1>
1427 <heading>Obsolete constructs and libraries</heading>
1430 The include file <tt><varargs.h></tt> is
1431 provided to support end-users compiling very old software;
1432 the library <tt>libtermcap</tt> is provided to support the
1433 execution of software which has been linked against it
1434 (either old programs or those such as Netscape which are
1435 only available in binary form).</p>
1438 Debian packages should be patched to use
1439 <tt><stdarg.h></tt> and <tt>ncurses</tt>
1446 <chapt id="controlfields"><heading>Control files and their fields</heading>
1449 Many of the tools in the package management suite manipulate
1450 data represented in a common format, known as <em>control
1451 data</em>. The data is often stored in <em>control
1452 files</em>. Binary and source packages have control files,
1453 and the <file>.changes</file> files which control the installation
1454 of uploaded files are also in control file format.
1455 <prgn>dpkg</prgn>'s internal databases are in a similar
1459 <sect id="controlsyntax"><heading>Syntax of control files</heading>
1462 A control file consists of one or more paragraphs of fields.
1463 The paragraphs are separated by blank lines. Some control
1464 files allow only one paragraph; others allow several, in
1465 which case each paragraph usually refers to a different
1466 package. (For example, in source packages, the first
1467 paragraph refers to the source package, and later paragraphs
1468 refer to binary packages generated from the source.)
1472 Each paragraph consists of a series of data fields; each
1473 field consists of the field name, followed by a colon and
1474 then the data/value associated with that field. It ends at
1475 the end of the line. Horizontal whitespace (spaces and
1476 tabs) may occur immediately before or after the value and is
1477 ignored there; it is conventional to put a single space
1478 after the colon. For example, a field might be:
1479 <example compact="compact">
1482 the field name is <tt>Package</tt> and the field value
1487 Some fields' values may span several lines; in this case
1488 each continuation line <em>must</em> start with a space or
1489 tab. Any trailing spaces or tabs at the end of individual
1490 lines of a field value are ignored.
1494 Except where otherwise stated only a single line of data is
1495 allowed and whitespace is not significant in a field body.
1496 Whitespace must not appear inside names (of packages,
1497 architectures, files or anything else) or version numbers,
1498 or between the characters of multi-character version
1503 Field names are not case-sensitive, but it is usual to
1504 capitalize the field names using mixed case as shown below.
1508 Blank lines, or lines consisting only of spaces and tabs,
1509 are not allowed within field values or between fields - that
1510 would mean a new paragraph.
1515 <sect><heading>List of fields</heading>
1517 This list here is not supposed to be exhaustive. Most fields
1518 are dealt with elsewhere in this document.
1520 <sect1 id="f-Package"><heading><tt>Package</tt>
1524 The name of the binary package. Package names consist of
1525 lower case letters (<tt>a-z</tt>), digits (<tt>0-9</tt>),
1526 plus (<tt>+</tt>) and minus (<tt>-</tt>) signs, and
1527 periods (<tt>.</tt>).
1531 They must be at least two characters long and must start
1532 with an alphanumeric character. The use of lowercase
1533 package names is required unless the package you're
1534 building (or referring to, in other fields) is already
1535 using uppercase characters.</p>
1538 <sect1 id="f-Version"><heading><tt>Version</tt>
1542 This lists the source or binary package's version number -
1543 see <ref id="versions">.
1549 id="f-Standards-Version"><heading><tt>Standards-Version</tt>
1553 The most recent version of the standards (the policy
1554 manual and associated texts) with which the package
1555 complies. This is updated manually when editing the
1556 source package to conform to newer standards; it can
1557 sometimes be used to tell when a package needs attention.
1558 Its format is described above; see
1559 <ref id="standardsversion">.
1564 <sect1 id="f-Distribution"><heading><tt>Distribution</tt>
1568 In a <file>.changes</file> file or parsed changelog output
1569 this contains the (space-separated) name(s) of the
1570 distribution(s) where this version of the package should
1571 be installed. Valid distributions are determined by the
1572 archive maintainers.<footnote>
1573 Current distribution names are:
1574 <taglist compact="compact">
1575 <tag><em>stable</em></tag>
1578 This is the current "released" version of Debian
1579 GNU/Linux. Once the distribution is
1580 <em>stable</em> only security fixes and other
1581 major bug fixes are allowed. When changes are
1582 made to this distribution, the release number is
1583 increased (for example: 2.2r1 becomes 2.2r2 then
1588 <tag><em>unstable</em></tag>
1591 This distribution value refers to the
1592 <em>developmental</em> part of the Debian
1593 distribution tree. New packages, new upstream
1594 versions of packages and bug fixes go into the
1595 <em>unstable</em> directory tree. Download from
1596 this distribution at your own risk.
1600 <tag><em>testing</em></tag>
1603 This distribution value refers to the
1604 <em>testing</em> part of the Debian distribution
1605 tree. It receives its packages from the
1606 unstable distribution after a short time lag to
1607 ensure that there are no major issues with the
1608 unstable packages. It is less prone to breakage
1609 than unstable, but still risky. It is not
1610 possible to upload packages directly to
1615 <tag><em>frozen</em></tag>
1618 From time to time, the <em>testing</em>
1619 distribution enters a state of "code-freeze" in
1620 anticipation of release as a <em>stable</em>
1621 version. During this period of testing only
1622 fixes for existing or newly-discovered bugs will
1623 be allowed. The exact details of this stage are
1624 determined by the Release Manager.
1628 <tag><em>experimental</em></tag>
1631 The packages with this distribution value are
1632 deemed by their maintainers to be high
1633 risk. Oftentimes they represent early beta or
1634 developmental packages from various sources that
1635 the maintainers want people to try, but are not
1636 ready to be a part of the other parts of the
1637 Debian distribution tree. Download at your own
1643 You should list <em>all</em> distributions that the
1644 package should be installed into.
1653 <chapt id="versions"><heading>Version numbering</heading>
1656 Every package has a version number recorded in its
1657 <tt>Version</tt> control file field.
1661 The package management system imposes an ordering on version
1662 numbers, so that it can tell whether packages are being up- or
1663 downgraded and so that package system front end applications
1664 can tell whether a package it finds available is newer than
1665 the one installed on the system. The version number format
1666 has the most significant parts (as far as comparison is
1667 concerned) at the beginning.
1671 The version number format is:
1672 [<var>epoch</var><tt>:</tt>]<var>upstream_version</var>[<tt>-</tt><var>debian_revision</var>]
1676 The three components here are:
1678 <tag><var>epoch</var></tag>
1681 This is a single (generally small) unsigned integer. It
1682 may be omitted, in which case zero is assumed. If it is
1683 omitted then the <var>upstream_version</var> may not
1688 It is provided to allow mistakes in the version numbers
1689 of older versions of a package, and also a package's
1690 previous version numbering schemes, to be left behind.
1694 <tag><var>upstream_version</var></tag>
1697 This is the main part of the version number. It is
1698 usually the version number of the original ("upstream")
1699 package from which the <file>.deb</file> file has been made,
1700 if this is applicable. Usually this will be in the same
1701 format as that specified by the upstream author(s);
1702 however, it may need to be reformatted to fit into the
1703 package management system's format and comparison
1708 The comparison behavior of the package management system
1709 with respect to the <var>upstream_version</var> is
1710 described below. The <var>upstream_version</var>
1711 portion of the version number is mandatory.
1715 The <var>upstream_version</var> may contain only
1716 alphanumerics<footnote>
1717 <p>Alphanumerics are <tt>A-Za-z0-9</tt> only.</p>
1719 and the characters <tt>.</tt> <tt>+</tt> <tt>-</tt>
1720 <tt>:</tt> (full stop, plus, hyphen, colon) and should
1721 start with a digit. If there is no
1722 <var>debian_revision</var> then hyphens are not allowed;
1723 if there is no <var>epoch</var> then colons are not
1727 <tag><var>debian_revision</var></tag>
1730 This part of the version number specifies the version of
1731 the Debian package based on the upstream version. It
1732 may contain only alphanumerics and the characters
1733 <tt>+</tt> and <tt>.</tt> (plus and full stop) and is
1734 compared in the same way as the
1735 <var>upstream_version</var> is.
1739 It is optional; if it isn't present then the
1740 <var>upstream_version</var> may not contain a hyphen.
1741 This format represents the case where a piece of
1742 software was written specifically to be turned into a
1743 Debian package, and so there is only one "debianization"
1744 of it and therefore no revision indication is required.
1748 It is conventional to restart the
1749 <var>debian_revision</var> at <tt>1</tt> each time the
1750 <var>upstream_version</var> is increased.
1754 The package management system will break the version
1755 number apart at the last hyphen in the string (if there
1756 is one) to determine the <var>upstream_version</var> and
1757 <var>debian_revision</var>. The absence of a
1758 <var>debian_revision</var> compares earlier than the
1759 presence of one (but note that the
1760 <var>debian_revision</var> is the least significant part
1761 of the version number).
1768 The <var>upstream_version</var> and <var>debian_revision</var>
1769 parts are compared by the package management system using the
1774 The strings are compared from left to right.
1778 First the initial part of each string consisting entirely of
1779 non-digit characters is determined. These two parts (one of
1780 which may be empty) are compared lexically. If a difference
1781 is found it is returned. The lexical comparison is a
1782 comparison of ASCII values modified so that all the letters
1783 sort earlier than all the non-letters.
1787 Then the initial part of the remainder of each string which
1788 consists entirely of digit characters is determined. The
1789 numerical values of these two parts are compared, and any
1790 difference found is returned as the result of the comparison.
1791 For these purposes an empty string (which can only occur at
1792 the end of one or both version strings being compared) counts
1797 These two steps (comparing and removing initial non-digit
1798 strings and initial digit strings) are repeated until a
1799 difference is found or both strings are exhausted.
1803 Note that the purpose of epochs is to allow us to leave behind
1804 mistakes in version numbering, and to cope with situations
1805 where the version numbering scheme changes. It is
1806 <em>not</em> intended to cope with version numbers containing
1807 strings of letters which the package management system cannot
1808 interpret (such as <tt>ALPHA</tt> or <tt>pre-</tt>), or with
1809 silly orderings (the author of this manual has heard of a
1810 package whose versions went <tt>1.1</tt>, <tt>1.2</tt>,
1811 <tt>1.3</tt>, <tt>1</tt>, <tt>2.1</tt>, <tt>2.2</tt>,
1812 <tt>2</tt> and so forth).
1816 If an upstream package has problematic version numbers they
1817 should be converted to a sane form for use in the
1818 <tt>Version</tt> field.
1822 <heading>Version numbers based on dates</heading>
1824 In general, Debian packages should use the same version
1825 numbers as the upstream sources.</p>
1828 However, in some cases where the upstream version number is
1829 based on a date (e.g., a development "snapshot" release) the
1830 package management system cannot handle these version
1831 numbers without epochs. For example, dpkg will consider
1832 "96May01" to be greater than "96Dec24".</p>
1835 To prevent having to use epochs for every new upstream
1836 version, the version number should be changed to the
1837 following format in such cases: "19960501", "19961224". It
1838 is up to the maintainer whether he/she wants to bother the
1839 upstream maintainer to change the version numbers upstream,
1843 Note that other version formats based on dates which are
1844 parsed correctly by the package management system should
1845 <em>not</em> be changed.</p>
1848 Native Debian packages (i.e., packages which have been
1849 written especially for Debian) whose version numbers include
1850 dates should always use the "YYYYMMDD" format.</p>
1854 <chapt id="miscellaneous"><heading>Packaging Considerations</heading>
1856 <sect id="timestamps"><heading>Time Stamps</heading>
1858 Maintainers should preserve the modification times of the
1859 upstream source files in a package, as far as is reasonably
1862 The rationale is that there is some information conveyed
1863 by knowing the age of the file, for example, you could
1864 recognize that some documentation is very old by looking
1865 at the modification time, so it would be nice if the
1866 modification time of the upstream source would be
1873 <sect id="debianrules"><heading><file>debian/rules</file> - the
1874 main building script</heading>
1877 This file must be an executable makefile, and contains the
1878 package-specific recipes for compiling the package and
1879 building binary package(s) from the source.
1883 It must start with the line <tt>#!/usr/bin/make -f</tt>,
1884 so that it can be invoked by saying its name rather than
1885 invoking <prgn>make</prgn> explicitly.
1889 Since an interactive <file>debian/rules</file> script makes it
1890 impossible to auto-compile that package and also makes it
1891 hard for other people to reproduce the same binary
1892 package, all <em>required targets</em> MUST be
1893 non-interactive. At a minimum, required targets are the
1894 ones called by <prgn>dpkg-buildpackage</prgn>, namely,
1895 <em>clean</em>, <em>binary</em>, <em>binary-arch</em>,
1896 <em>binary-indep</em>, and <em>build</em>. It also follows
1897 that any target that these targets depend on must also be
1902 The required and optional targets are as follows:
1904 <tag><tt>build</tt>, <tt>build-arch</tt> (optional),
1905 <tt>build-indep</tt> (optional)</tag>
1908 The <tt>build</tt> target should perform all
1909 non-interactive configuration and compilation of the
1910 package. If a package has an interactive pre-build
1911 configuration routine, the Debianized source package
1912 must either be built after this has taken place (so
1913 that the binary package can be built without rerunning
1914 the configuration) or the configuration routine
1915 modified to become non-interactive. (The latter is
1916 preferable if there are architecture-specific features
1917 detected by the configuration routine.)
1921 For some packages, notably ones where the same
1922 source tree is compiled in different ways to produce
1923 two binary packages, the <tt>build</tt> target
1924 does not make much sense. For these packages it is
1925 good enough to provide two (or more) targets
1926 (<tt>build-a</tt> and <tt>build-b</tt> or whatever)
1927 for each of the ways of building the package, and a
1928 <tt>build</tt> target that does nothing. The
1929 <tt>binary</tt> target will have to build the
1930 package in each of the possible ways and make the
1931 binary package out of each.
1935 The <tt>build</tt> target must not do anything
1936 that might require root privilege.
1940 The <tt>build</tt> target may need to run the
1941 <tt>clean</tt> target first - see below.
1945 When a package has a configuration and build routine
1946 which takes a long time, or when the makefiles are
1947 poorly designed, or when <tt>build</tt> needs to
1948 run <tt>clean</tt> first, it is a good idea to
1949 <tt>touch build</tt> when the build process is
1950 complete. This will ensure that if <tt>debian/rules
1951 build</tt> is run again it will not rebuild the whole
1954 Another common way to do this is for <tt>build</tt>
1955 to depend on <prgn>build-stamp</prgn> and to do
1956 nothing else, and for the <prgn>build-stamp</prgn>
1957 target to do the building and to <tt>touch
1958 build-stamp</tt> on completion. This is
1959 especially useful if the build routine creates a
1960 file or directory called <tt>build</tt>; in such a
1961 case, <tt>build</tt> will need to be listed as
1962 a phony target (i.e., as a dependency of the
1963 <tt>.PHONY</tt> target). See the documentation of
1964 <prgn>make</prgn> for more information on phony
1971 <tag><tt>binary</tt>, <tt>binary-arch</tt>,
1972 <tt>binary-indep</tt>
1976 The <tt>binary</tt> target must be all that is
1977 necessary for the user to build the binary package(s)
1978 produced from this source package. All of these
1979 targets are required to be non-interactive. It is
1980 split into two parts: <prgn>binary-arch</prgn> builds
1981 the binary packages which are specific to a particular
1982 architecture, and <tt>binary-indep</tt> builds
1983 those which are not.
1986 <tt>binary</tt> may be (and commonly is) a target with
1987 no commands which simply depends on
1988 <tt>binary-arch</tt> and <tt>binary-indep</tt>.
1991 Both <tt>binary-*</tt> targets should depend on the
1992 <tt>build</tt> target, or on the appropriate
1993 <tt>build-arch</tt> or <tt>build-indep</tt> target, if
1994 provided, so that the package is built if it has not
1995 been already. It should then create the relevant
1996 binary package(s), using <prgn>dpkg-gencontrol</prgn> to
1997 make their control files and <prgn>dpkg-deb</prgn> to
1998 build them and place them in the parent of the top
2003 Both the <tt>binary-arch</tt> and
2004 <tt>binary-indep</tt> targets <em>must</em> exist.
2005 If one of them has nothing to do (which will always be
2006 the case if the source generates only a single binary
2007 package, whether architecture-dependent or not), it
2008 must still exist and must always succeed.
2012 The <tt>binary</tt> targets must be invoked as
2015 The <prgn>fakeroot</prgn> package often allows one
2016 to build a package correctly even without being
2023 <tag><tt>clean</tt></tag>
2026 This must undo any effects that the <tt>build</tt>
2027 and <tt>binary</tt> targets may have had, except
2028 that it should leave alone any output files created in
2029 the parent directory by a run of a <tt>binary</tt>
2030 target. This target must be non-interactive.
2034 If a <tt>build</tt> file is touched at the end of
2035 the <tt>build</tt> target, as suggested above, it
2036 should be removed as the first action that
2037 <tt>clean</tt> performs, so that running
2038 <tt>build</tt> again after an interrupted
2039 <tt>clean</tt> doesn't think that everything is
2044 The <tt>clean</tt> target may need to be
2045 invoked as root if <tt>binary</tt> has been
2046 invoked since the last <tt>clean</tt>, or if
2047 <tt>build</tt> has been invoked as root (since
2048 <tt>build</tt> may create directories, for
2053 <tag><tt>get-orig-source</tt> (optional)</tag>
2056 This target fetches the most recent version of the
2057 original source package from a canonical archive site
2058 (via FTP or WWW, for example), does any necessary
2059 rearrangement to turn it into the original source
2060 tar file format described below, and leaves it in the
2065 This target may be invoked in any directory, and
2066 should take care to clean up any temporary files it
2071 This target is optional, but providing it if
2072 possible is a good idea.
2078 The <tt>build</tt>, <tt>binary</tt> and
2079 <tt>clean</tt> targets must be invoked with the current
2080 directory being the package's top-level directory.
2085 Additional targets may exist in <file>debian/rules</file>,
2086 either as published or undocumented interfaces or for the
2087 package's internal use.
2091 The architectures we build on and build for are determined
2092 by <prgn>make</prgn> variables using the utility
2093 <prgn>dpkg-architecture</prgn>. You can determine the
2094 Debian architecture and the GNU style architecture
2095 specification string for the build machine (the machine type
2096 we are building on) as well as for the host machine (the
2097 machine type we are building for). Here is a list of
2098 supported <prgn>make</prgn> variables:
2099 <list compact="compact">
2101 <p><tt>DEB_*_ARCH</tt> (the Debian architecture)</p>
2104 <p><tt>DEB_*_GNU_TYPE</tt> (the GNU style architecture
2105 specification string)</p>
2108 <p><tt>DEB_*_GNU_CPU</tt> (the CPU part of
2109 <tt>DEB_*_GNU_TYPE</tt>)</p>
2112 <p><tt>DEB_*_GNU_SYSTEM</tt> (the System part of
2113 <tt>DEB_*_GNU_TYPE</tt>)</p>
2115 where <tt>*</tt> is either <tt>BUILD</tt> for specification of
2116 the build machine or <tt>HOST</tt> for specification of the
2121 Backward compatibility can be provided in the rules file
2122 by setting the needed variables to suitable default
2123 values; please refer to the documentation of
2124 <prgn>dpkg-architecture</prgn> for details.
2128 It is important to understand that the <tt>DEB_*_ARCH</tt>
2129 string only determines which Debian architecture we are
2130 building on or for. It should not be used to get the CPU
2131 or system information; the GNU style variables should be
2136 <sect id="dpkgchangelog"><heading><file>debian/changelog</file>
2140 This file records the changes to the Debian-specific parts of the
2143 Though there is nothing stopping an author who is also
2144 the Debian maintainer from using it for all their
2145 changes, it will have to be renamed if the Debian and
2146 upstream maintainers become different people. In such a
2147 case, however, it might be better to maintain the
2148 package as a non-native package.
2154 It has a special format which allows the package building
2155 tools to discover which version of the package is being
2156 built and find out other release-specific information.
2160 That format is a series of entries like this:
2161 <example compact="compact">
2162 <var>package</var> (<var>version</var>) <var>distribution(s)</var>; urgency=<var>urgency</var>
2164 <p>[optional blank line(s), stripped]</p>
2166 * <var>change details</var>
2167 <var>more change details</var>
2169 <p>[blank line(s), included in output of dpkg-parsechangelog]</p>
2171 * <var>even more change details</var>
2173 <p>[optional blank line(s), stripped]</p>
2175 -- <var>maintainer name</var> <<var>email
2176 address</var>><var>[two spaces]</var> <var>date</var>
2181 <var>package</var> and <var>version</var> are the source
2182 package name and version number.
2186 <var>distribution(s)</var> lists the distributions where
2187 this version should be installed when it is uploaded - it
2188 is copied to the <tt>Distribution</tt> field in the
2189 <file>.changes</file> file. See <ref id="f-Distribution">.
2193 <var>urgency</var> is the value for the <tt>Urgency</tt>
2194 field in the <file>.changes</file> file for the upload. It is
2195 not possible to specify an urgency containing commas; commas
2196 are used to separate
2197 <tt><var>keyword</var>=<var>value</var></tt> settings in the
2198 <prgn>dpkg</prgn> changelog format (though there is
2199 currently only one useful <var>keyword</var>,
2200 <tt>urgency</tt>).<footnote>
2202 Recognised urgency values are <tt>low</tt>,
2203 <tt>medium</tt>, <tt>high</tt> and <tt>emergency</tt>.
2204 They have an effect on how quickly a package will be
2205 considered for inclusion into the <tt>testing</tt>
2206 distribution, and give an indication of the importance
2207 of any fixes included in this upload.
2213 The change details may in fact be any series of lines
2214 starting with at least two spaces, but conventionally each
2215 change starts with an asterisk and a separating space and
2216 continuation lines are indented so as to bring them in
2217 line with the start of the text above. Blank lines may be
2218 used here to separate groups of changes, if desired.
2222 If this upload resolves bugs recorded in the Bug Tracking
2223 System (BTS), they may be automatically closed on the
2224 inclusion of this package into the Debian archive by
2225 including the string: <tt>closes: Bug#<var>nnnnn</var></tt>
2226 in the change details.<footnote>
2228 To be precise, the string should match the following
2229 Perl regular expression:
2231 /closes:\s*(?:bug)?\#?\s?\d+(?:,\s*(?:bug)?\#?\s?\d+)*/i
2233 Then all of the bug numbers listed will be closed by the
2234 archive maintenance script (<prgn>katie</prgn>), or in
2235 the case of an NMU, marked as fixed.
2241 The maintainer name and email address used in the changelog
2242 should be the details of the person uploading <em>this</em>
2243 version. They are <em>not</em> necessarily those of the
2244 usual package maintainer. The information here will be
2245 copied to the <tt>Changed-By</tt> field in the
2246 <tt>.changes</tt> file, and then later used to send an
2247 acknowledgement when the upload has been installed.
2251 The <var>date</var> should be in RFC822 format<footnote>
2253 This is generated by the <prgn>822-date</prgn>
2256 </footnote>; it should include the time zone specified
2257 numerically, with the time zone name or abbreviation
2258 optionally present as a comment in parentheses.
2262 The first "title" line with the package name should start
2263 at the left hand margin; the "trailer" line with the
2264 maintainer and date details should be preceded by exactly
2265 one space. The maintainer details and the date must be
2266 separated by exactly two spaces.
2269 <sect1><heading>Defining alternative changelog formats</heading>
2272 It is possible to use a different format to the standard
2273 one, by providing a parser for the format you wish to
2277 A changelog parser must not interact with the user at
2283 <!-- FIXME: section pkg-srcsubstvars is the same as srcsubstvars -->
2285 <sect id="srcsubstvars"><heading><file>debian/substvars</file>
2286 and variable substitutions </heading>
2289 When <prgn>dpkg-gencontrol</prgn>,
2290 <prgn>dpkg-genchanges</prgn> and <prgn>dpkg-source</prgn>
2291 generate control files they perform variable substitutions
2292 on their output just before writing it. Variable
2293 substitutions have the form <tt>${<var>variable</var>}</tt>.
2294 The optional file <file>debian/substvars</file> contains
2295 variable substitutions to be used; variables can also be set
2296 directly from <file>debian/rules</file> using the <tt>-V</tt>
2297 option to the source packaging commands, and certain
2298 predefined variables are also available.
2302 The <file>debian/substvars</file> file is usually generated and
2303 modified dynamically by <file>debian/rules</file> targets, in
2304 which case it must be removed by the <tt>clean</tt> target.
2308 See <manref name="dpkg-source" section="1"> for full
2309 details about source variable substitutions, including the
2310 format of <file>debian/substvars</file>.</p>
2313 <sect id="debianfiles"><heading><file>debian/files</file>
2317 This file is not a permanent part of the source tree; it
2318 is used while building packages to record which files are
2319 being generated. <prgn>dpkg-genchanges</prgn> uses it
2320 when it generates a <file>.changes</file> file.
2324 It should not exist in a shipped source package, and so it
2325 (and any backup files or temporary files such as
2326 <file>files.new</file><footnote>
2328 <file>files.new</file> is used as a temporary file by
2329 <prgn>dpkg-gencontrol</prgn> and
2330 <prgn>dpkg-distaddfile</prgn> - they write a new
2331 version of <tt>files</tt> here before renaming it,
2332 to avoid leaving a corrupted copy if an error
2335 </footnote>) should be removed by the
2336 <tt>clean</tt> target. It may also be wise to
2337 ensure a fresh start by emptying or removing it at the
2338 start of the <tt>binary</tt> target.
2342 When <prgn>dpkg-gencontrol</prgn> is run for a binary
2343 package, it adds an entry to <file>debian/files</file> for the
2344 <file>.deb</file> file that will be created when <tt>dpkg-deb
2345 --build</tt> is run for that binary package. So for most
2346 packages all that needs to be done with this file is to
2347 delete it in the <tt>clean</tt> target.
2351 If a package upload includes files besides the source
2352 package and any binary packages whose control files were
2353 made with <prgn>dpkg-gencontrol</prgn> then they should be
2354 placed in the parent of the package's top-level directory
2355 and <prgn>dpkg-distaddfile</prgn> should be called to add
2356 the file to the list in <file>debian/files</file>.</p>
2359 <sect id="restrictions"><heading>Restrictions on objects in source packages
2363 The source package may not contain any hard links<footnote>
2365 This is not currently detected when building source
2366 packages, but only when extracting
2370 Hard links may be permitted at some point in the
2371 future, but would require a fair amount of
2374 </footnote>, device special files, sockets or setuid or
2375 setgid files.<footnote>
2377 Setgid directories are allowed.
2383 <sect id="descriptions"><heading>Descriptions of packages - the
2384 <tt>Description</tt> field</heading>
2387 The "Description" control file field consists of two parts,
2388 the synopsis or the short description, and the long description.
2389 The field's format is as follows:
2393 Description: <single line synopsis>
2394 <extended description over several lines>
2398 The description is intended to describe the program to a user
2399 who has never met it before so that they know whether they
2400 want to install it. It should also give information about the
2401 significant dependencies and conflicts between this package
2402 and others, so that the user knows why these dependencies and
2403 conflicts have been declared.
2407 Put important information first, both in the synopsis and
2408 extended description. Sometimes only the first part of the
2409 synopsis or of the description will be displayed. You can
2410 assume that there will usually be a way to see the whole
2411 extended description.
2414 <sect1 id="synopsis"><heading>The single line synopsis</heading>
2417 The single line synopsis should be kept brief - certainly
2418 under 80 characters.
2422 Do not include the package name in the synopsis line. The
2423 display software knows how to display this already, and you
2424 do not need to state it. Remember that in many situations
2425 the user may only see the synopsis line - make it as
2426 informative as you can.
2431 <sect1 id="extendeddesc"><heading>The extended description</heading>
2434 Do not try to continue the single line synopsis into the
2435 extended description. This will not work correctly when
2436 the full description is displayed, and makes no sense
2437 where only the summary (the single line synopsis) is
2442 The extended description should describe what the package
2443 does and how it relates to the rest of the system (in terms
2444 of, for example, which subsystem it is which part of).
2448 The description field needs to make sense to anyone, even
2449 people who have no idea about any of the things the
2450 package deals with.<footnote>
2451 The blurb that comes with a program in its
2452 announcements and/or <prgn>README</prgn> files is
2453 rarely suitable for use in a description. It is
2454 usually aimed at people who are already in the
2455 community where the package is used.
2460 The lines in the extended description can have these formats:
2466 Those starting with a single space are part of a paragraph.
2467 Successive lines of this form will be word-wrapped when
2468 displayed. The leading space will usually be stripped off.
2472 Those starting with two or more spaces. These will be
2473 displayed verbatim. If the display cannot be panned
2474 horizontally, the displaying program will linewrap them "hard"
2475 (i.e., without taking account of word breaks). If it can they
2476 will be allowed to trail off to the right. None, one or two
2477 initial spaces may be deleted, but the number of spaces
2478 deleted from each line will be the same (so that you can have
2479 indenting work correctly, for example).
2483 Those containing a single space followed by a single full stop
2484 character. These are rendered as blank lines. This is the
2485 <em>only</em> way to get a blank line<footnote>
2486 Completely empty lines will not be rendered as blank lines.
2487 Instead, they will cause the parser to think you're starting
2488 a whole new record in the control file, and will therefore
2489 likely abort with an error.
2494 Those containing a space, a full stop and some more characters.
2495 These are for future expansion. Do not use them.
2501 Do not use tab characters. Their effect is not predictable.
2511 <chapt id="maintainerscripts"><heading>Package maintainer scripts
2512 and installation procedure
2515 <sect><heading>Introduction to package maintainer scripts
2519 It is possible to supply scripts as part of a package which
2520 the package management system will run for you when your
2521 package is installed, upgraded or removed.
2525 These scripts are the files <prgn>preinst</prgn>,
2526 <prgn>postinst</prgn>, <prgn>prerm</prgn> and <prgn>postrm</prgn> in the
2527 control area of the package. They must be proper executable
2528 files; if they are scripts (which is recommended), they must
2529 start with the usual <tt>#!</tt> convention. They should be
2530 readable and executable by anyone, and not world-writable.
2534 The package management system looks at the exit status from
2535 these scripts. It is important that they exit with a
2536 non-zero status if there is an error, so that the package
2537 management system can stop its processing. For shell
2538 scripts this means that you <em>almost always</em> need to
2539 use <tt>set -e</tt> (this is usually true when writing shell
2540 scripts, in fact). It is also important, of course, that
2541 they don't exit with a non-zero status if everything went
2546 When a package is upgraded a combination of the scripts from
2547 the old and new packages is called during the upgrade
2548 procedure. If your scripts are going to be at all
2549 complicated you need to be aware of this, and may need to
2550 check the arguments to your scripts.
2554 Broadly speaking the <prgn>preinst</prgn> is called before
2555 (a particular version of) a package is installed, and the
2556 <prgn>postinst</prgn> afterwards; the <prgn>prerm</prgn>
2557 before (a version of) a package is removed and the
2558 <prgn>postrm</prgn> afterwards.
2562 Programs called from maintainer scripts should not normally
2563 have a path prepended to them. Before installation is
2564 started, the package management system checks to see if the
2565 programs <prgn>ldconfig</prgn>,
2566 <prgn>start-stop-daemon</prgn>, <prgn>install-info</prgn>,
2567 and <prgn>update-rc.d</prgn> can be found via the
2568 <tt>PATH</tt> environment variable. Those programs, and any
2569 other program that one would expect to be on the
2570 <tt>PATH</tt>, should thus be invoked without an absolute
2571 pathname. Maintainer scripts should also not reset the
2572 <tt>PATH</tt>, though they might choose to modify it by
2573 prepending or appending package-specific directories. These
2574 considerations really apply to all shell scripts.</p>
2578 <heading>Maintainer scripts Idempotency</heading>
2581 It is necessary for the error recovery procedures that the
2582 scripts be idempotent. This means that if it is run
2583 successfully, and then it is called again, it doesn't bomb
2584 out or cause any harm, but just ensures that everything is
2585 the way it ought to be. If the first call failed, or
2586 aborted half way through for some reason, the second call
2587 should merely do the things that were left undone the first
2588 time, if any, and exit with a success status if everything
2591 This is so that if an error occurs, the user interrupts
2592 <prgn>dpkg</prgn> or some other unforeseen circumstance
2593 happens you don't leave the user with a badly-broken
2594 package when <prgn>dpkg</prgn> attempts to repeat the
2602 <heading>Controlling terminal for maintainer scripts</heading>
2605 The maintainer scripts are guaranteed to run with a
2606 controlling terminal and can interact with the user.
2607 If they need to prompt for passwords, do full-screen
2608 interaction or something similar you should do these
2609 things to and from <file>/dev/tty</file>, since
2610 <prgn>dpkg</prgn> will at some point redirect scripts'
2611 standard input and output so that it can log the
2612 installation process. Likewise, because these scripts
2613 may be executed with standard output redirected into a
2614 pipe for logging purposes, Perl scripts should set
2615 unbuffered output by setting <tt>$|=1</tt> so that the
2616 output is printed immediately rather than being
2621 Each script should return a zero exit status for
2622 success, or a nonzero one for failure.
2626 <sect id="mscriptsinstact"><heading>Summary of ways maintainer
2631 <list compact="compact">
2633 <p><var>new-preinst</var> <tt>install</tt></p>
2636 <p><var>new-preinst</var> <tt>install</tt>
2637 <var>old-version</var></p>
2640 <p><var>new-preinst</var> <tt>upgrade</tt>
2641 <var>old-version</var></p>
2644 <p><var>old-preinst</var> <tt>abort-upgrade</tt>
2645 <var>new-version</var>
2651 <list compact="compact">
2653 <p><var>postinst</var> <tt>configure</tt>
2654 <var>most-recently-configured-version</var></p>
2657 <p><var>old-postinst</var> <tt>abort-upgrade</tt>
2658 <var>new-version</var></p>
2661 <p><var>conflictor's-postinst</var> <tt>abort-remove</tt>
2662 <tt>in-favour</tt> <var>package</var>
2663 <var>new-version</var></p>
2667 <var>deconfigured's-postinst</var>
2668 <tt>abort-deconfigure</tt> <tt>in-favour</tt>
2669 <var>failed-install-package</var> <var>version</var>
2670 <tt>removing</tt> <var>conflicting-package</var>
2677 <list compact="compact">
2679 <p><var>prerm</var> <tt>remove</tt></p>
2682 <p><var>old-prerm</var> <tt>upgrade</tt>
2683 <var>new-version</var></p>
2686 <p><var>new-prerm</var> <tt>failed-upgrade</tt>
2687 <var>old-version</var></p>
2690 <p><var>conflictor's-prerm</var> <tt>remove</tt>
2691 <tt>in-favour</tt> <var>package</var>
2692 <var>new-version</var></p>
2696 <var>deconfigured's-prerm</var> <tt>deconfigure</tt>
2697 <tt>in-favour</tt> <var>package-being-installed</var>
2698 <var>version</var> <tt>removing</tt>
2699 <var>conflicting-package</var>
2706 <list compact="compact">
2708 <p><var>postrm</var> <tt>remove</tt></p>
2711 <p><var>postrm</var> <tt>purge</tt></p>
2715 <var>old-postrm</var> <tt>upgrade</tt>
2716 <var>new-version</var></p>
2719 <p><var>new-postrm</var> <tt>failed-upgrade</tt>
2720 <var>old-version</var></p>
2723 <p><var>new-postrm</var> <tt>abort-install</tt></p>
2726 <p><var>new-postrm</var> <tt>abort-install</tt>
2727 <var>old-version</var></p>
2730 <p><var>new-postrm</var> <tt>abort-upgrade</tt>
2731 <var>old-version</var></p>
2735 <var>disappearer's-postrm</var> <tt>disappear</tt>
2736 <var>overwriter</var>
2737 <var>overwriter-version</var></p></item>
2742 <sect id="unpackphase"><heading>Details of unpack phase of
2743 installation or upgrade
2747 The procedure on installation/upgrade/overwrite/disappear
2748 (i.e., when running <tt>dpkg --unpack</tt>, or the unpack
2749 stage of <tt>dpkg --install</tt>) is as follows. In each
2750 case, if a major error occurs (unless listed below) the
2751 actions are, in general, run backwards - this means that the
2752 maintainer scripts are run with different arguments in
2753 reverse order. These are the "error unwind" calls listed
2761 <p>If a version of the package is already
2763 <example compact="compact">
2764 <var>old-prerm</var> upgrade <var>new-version</var>
2769 If the script runs but exits with a non-zero
2770 exit status, <prgn>dpkg</prgn> will attempt:
2771 <example compact="compact">
2772 <var>new-prerm</var> failed-upgrade <var>old-version</var>
2774 Error unwind, for both the above cases:
2775 <example compact="compact">
2776 <var>old-postinst</var> abort-upgrade <var>new-version</var>
2784 <p>If a "conflicting" package is being removed at the same time:
2788 If any packages depended on that conflicting
2789 package and <tt>--auto-deconfigure</tt> is
2790 specified, call, for each such package:
2791 <example compact="compact">
2792 <var>deconfigured's-prerm</var> deconfigure \
2793 in-favour <var>package-being-installed</var> <var>version</var> \
2794 removing <var>conflicting-package</var> <var>version</var>
2797 <example compact="compact">
2798 <var>deconfigured's-postinst</var> abort-deconfigure \
2799 in-favour <var>package-being-installed-but-failed</var> <var>version</var> \
2800 removing <var>conflicting-package</var> <var>version</var>
2802 The deconfigured packages are marked as
2803 requiring configuration, so that if
2804 <tt>--install</tt> is used they will be
2805 configured again if possible.</p>
2808 <p>To prepare for removal of the conflicting package, call:
2809 <example compact="compact">
2810 <var>conflictor's-prerm</var> remove \
2811 in-favour <var>package</var> <var>new-version</var>
2814 <example compact="compact">
2815 <var>conflictor's-postinst</var> abort-remove \
2816 in-favour <var>package</var> <var>new-version</var>
2827 <p>If the package is being upgraded, call:
2828 <example compact="compact">
2829 <var>new-preinst</var> upgrade <var>old-version</var>
2834 Otherwise, if the package had some configuration
2835 files from a previous version installed (i.e., it
2836 is in the "configuration files only" state):
2837 <example compact="compact">
2838 <var>new-preinst</var> install <var>old-version</var>
2842 <p>Otherwise (i.e., the package was completely purged):
2843 <example compact="compact">
2844 <var>new-preinst</var> install
2846 Error unwind actions, respectively:
2847 <example compact="compact">
2848 <var>new-postrm</var> abort-upgrade <var>old-version</var>
2849 <var>new-postrm</var> abort-install <var>old-version</var>
2850 <var>new-postrm</var> abort-install
2859 The new package's files are unpacked, overwriting any
2860 that may be on the system already, for example any
2861 from the old version of the same package or from
2862 another package. Backups of the old files are kept
2863 temporarily, and if anything goes wrong the package
2864 management system will attempt to put them back as
2865 part of the error unwind.
2869 It is an error for a package to contains files which
2870 are on the system in another package, unless
2871 <tt>Replaces</tt> is used (see <ref id="replaces">).
2873 The following paragraph is not currently the case:
2874 Currently the <tt>- - force-overwrite</tt> flag is
2875 enabled, downgrading it to a warning, but this may not
2881 It is a more serious error for a package to contain a
2882 plain file or other kind of non-directory where another
2883 package has a directory (again, unless
2884 <tt>Replaces</tt> is used). This error can be
2885 overridden if desired using
2886 <tt>--force-overwrite-dir</tt>, but this is not
2891 Packages which overwrite each other's files produce
2892 behavior which, though deterministic, is hard for the
2893 system administrator to understand. It can easily
2894 lead to "missing" programs if, for example, a package
2895 is installed which overwrites a file from another
2896 package, and is then removed again.<footnote>
2898 Part of the problem is due to what is arguably a
2899 bug in <prgn>dpkg</prgn>.
2905 A directory will never be replaced by a symbolic link
2906 to a directory or vice versa; instead, the existing
2907 state (symlink or not) will be left alone and
2908 <prgn>dpkg</prgn> will follow the symlink if there is
2916 <p>If the package is being upgraded, call
2917 <example compact="compact">
2918 <var>old-postrm</var> upgrade <var>new-version</var>
2923 <p>If this fails, <prgn>dpkg</prgn> will attempt:
2924 <example compact="compact">
2925 <var>new-postrm</var> failed-upgrade <var>old-version</var>
2927 Error unwind, for both cases:
2928 <example compact="compact">
2929 <var>old-preinst</var> abort-upgrade <var>new-version</var>
2936 This is the point of no return - if
2937 <prgn>dpkg</prgn> gets this far, it won't back off
2938 past this point if an error occurs. This will
2939 leave the package in a fairly bad state, which
2940 will require a successful re-installation to clear
2941 up, but it's when <prgn>dpkg</prgn> starts doing
2942 things that are irreversible.
2947 Any files which were in the old version of the package
2948 but not in the new are removed.</p>
2951 <p>The new file list replaces the old.</p>
2954 <p>The new maintainer scripts replace the old.</p>
2958 <p>Any packages all of whose files have been overwritten during the
2959 installation, and which aren't required for
2960 dependencies, are considered to have been removed.
2961 For each such package
2964 <p><prgn>dpkg</prgn> calls:
2965 <example compact="compact">
2966 <var>disappearer's-postrm</var> disappear \
2967 <var>overwriter</var> <var>overwriter-version</var>
2972 <p>The package's maintainer scripts are removed.
2977 It is noted in the status database as being in a
2978 sane state, namely not installed (any conffiles
2979 it may have are ignored, rather than being
2980 removed by <prgn>dpkg</prgn>). Note that
2981 disappearing packages do not have their prerm
2982 called, because <prgn>dpkg</prgn> doesn't know
2983 in advance that the package is going to
2992 Any files in the package we're unpacking that are also
2993 listed in the file lists of other packages are removed
2994 from those lists. (This will lobotomize the file list
2995 of the "conflicting" package if there is one.)
3000 The backup files made during installation, above, are
3007 The new package's status is now sane, and recorded as
3012 Here is another point of no return - if the
3013 conflicting package's removal fails we do not unwind
3014 the rest of the installation; the conflicting package
3015 is left in a half-removed limbo.
3021 If there was a conflicting package we go and do the
3022 removal actions (described below), starting with the
3023 removal of the conflicting package's files (any that
3024 are also in the package being installed have already
3025 been removed from the conflicting package's file list,
3026 and so do not get removed now).
3033 <sect id="configdetails"><heading>Details of configuration</heading>
3036 When we configure a package (this happens with <tt>dpkg
3037 --install</tt> and <tt>dpkg --configure</tt>), we first
3038 update any <tt>conffile</tt>s and then call:
3039 <example compact="compact">
3040 <var>postinst</var> configure <var>most-recently-configured-version</var>
3045 No attempt is made to unwind after errors during
3050 If there is no most recently configured version
3051 <prgn>dpkg</prgn> will pass a null argument; older versions
3052 of dpkg may pass <tt><unknown></tt> (including the
3053 angle brackets) in this case. Even older ones do not pass a
3054 second argument at all, under any circumstances.
3058 <sect id="removedetails"><heading>Details of removal and/or
3059 configuration purging</heading>
3065 <example compact="compact">
3066 <var>prerm</var> remove
3072 The package's files are removed (except <tt>conffile</tt>s).
3077 <example compact="compact">
3078 <var>postrm</var> remove
3084 All the maintainer scripts except the <prgn>postrm</prgn>
3089 If we aren't purging the package we stop here. Note
3090 that packages which have no <prgn>postrm</prgn> and no
3091 <tt>conffile</tt>s are automatically purged when
3092 removed, as there is no difference except for the
3093 <prgn>dpkg</prgn> status.</p>
3097 The <tt>conffile</tt>s and any backup files
3098 (<tt>~</tt>-files, <tt>#*#</tt> files,
3099 <tt>%</tt>-files, <tt>.dpkg-{old,new,tmp}</tt>, etc.)
3104 <example compact="compact">
3105 <var>postrm</var> purge
3110 <p>The package's file list is removed.</p>
3113 No attempt is made to unwind after errors during
3120 <chapt id="relationships"><heading>Declaring relationships between
3123 <sect id="depsyntax"><heading>Syntax of relationship fields
3127 These fields all have a uniform syntax. They are a list of
3128 package names separated by commas.
3132 In the <tt>Depends</tt>, <tt>Recommends</tt>,
3133 <tt>Suggests</tt>, <tt>Pre-Depends</tt>,
3134 <tt>Build-Depends</tt> and <tt>Build-Depends-Indep</tt>
3135 control file fields of the package, which declare
3136 dependencies on other packages, the package names listed may
3137 also include lists of alternative package names, separated
3138 by vertical bar (pipe) symbols <tt>|</tt>. In such a case,
3139 if any one of the alternative packages is installed, that
3140 part of the dependency is considered to be satisfied.
3144 All of the fields except for <tt>Provides</tt> may restrict
3145 their applicability to particular versions of each named
3146 package. This is done in parentheses after each individual
3147 package name; the parentheses should contain a relation from
3148 the list below followed by a version number, in the format
3149 described in <ref id="versions">.
3153 The relations allowed are <tt><<</tt>, <tt><=</tt>,
3154 <tt>=</tt>, <tt>>=</tt> and <tt>>></tt> for
3155 strictly earlier, earlier or equal, exactly equal, later or
3156 equal and strictly later, respectively. The deprecated
3157 forms <tt><</tt> and <tt>></tt> were used to mean
3158 earlier/later or equal, rather than strictly earlier/later,
3159 so they should not appear in new packages (though
3160 <prgn>dpkg</prgn> still supports them).
3164 Whitespace may appear at any point in the version
3165 specification subject to the rules in <ref
3166 id="controlsyntax">, and must appear where it's necessary to
3167 disambiguate; it is not otherwise significant. For
3168 consistency and in case of future changes to
3169 <prgn>dpkg</prgn> it is recommended that a single space be
3170 used after a version relationship and before a version
3171 number; it is also conventional to put a single space after
3172 each comma, on either side of each vertical bar, and before
3173 each open parenthesis.
3177 For example, a list of dependencies might appear as:
3178 <example compact="compact">
3181 Depends: libc6 (>= 2.2.1), exim | mail-transport-agent
3186 All fields that specify build-time relationships
3187 (<tt>Build-Depends</tt>, <tt>Build-Depends-Indep</tt>,
3188 <tt>Build-Conflicts</tt> and <tt>Build-Conflicts-Indep</tt>)
3189 may be restricted to a certain set of architectures. This
3190 is indicated in brackets after each individual package name and
3191 the optional version specification. The brackets enclose a
3192 list of Debian architecture names separated by whitespace.
3193 Exclamation marks may be prepended to each of the names.
3194 (It is not permitted for some names to be prepended with
3195 exclamation marks and others not.) If the current Debian
3196 host architecture is not in this list and there are no
3197 exclamation marks in the list, or it is in the list with a
3198 prepended exclamation mark, the package name and the
3199 associated version specification are ignored completely for
3200 the purposes of defining the relationships.
3205 <example compact="compact">
3207 Build-Depends-Indep: texinfo
3208 Build-Depends: kernel-headers-2.2.10 [!hurd-i386],
3209 hurd-dev [hurd-i386], gnumach-dev [hurd-i386]
3214 Note that the binary package relationship fields such as
3215 <tt>Depends</tt> appear in one of the binary package
3216 sections of the control file, whereas the build-time
3217 relationships such as <tt>Build-Depends</tt> appear in the
3218 source package section of the control file (which is the
3224 <heading>Binary Dependencies - <tt>Depends</tt>,
3225 <tt>Recommends</tt>, <tt>Suggests</tt>, <tt>Enhances</tt>,
3226 <tt>Pre-Depends</tt>
3230 Packages can declare in their control file that they have
3231 certain relationships to other packages - for example, that
3232 they may not be installed at the same time as certain other
3233 packages, and/or that they depend on the presence of others.
3237 This is done using the <tt>Depends</tt>, <tt>Pre-Depends</tt>,
3238 <tt>Recommends</tt>, <tt>Suggests</tt>, <tt>Enhances</tt> and
3239 <tt>Conflicts</tt> control file fields.
3243 These six fields are used to declare a dependency
3244 relationship by one package on another. Except for
3245 <tt>Enhances</tt>, they appear in the depending (binary)
3246 package's control file. (<tt>Enhances</tt> appears in the
3247 recommending package's control file.)
3251 A <tt>Depends</tt> field takes effect <em>only</em> when a
3252 package is to be configured. It does not prevent a package
3253 being on the system in an unconfigured state while its
3254 dependencies are unsatisfied, and it is possible to replace
3255 a package whose dependencies are satisfied and which is
3256 properly installed with a different version whose
3257 dependencies are not and cannot be satisfied; when this is
3258 done the depending package will be left unconfigured (since
3259 attempts to configure it will give errors) and will not
3260 function properly. If it is necessary, a
3261 <tt>Pre-Depends</tt> field can be used, which has a partial
3262 effect even when a package is being unpacked, as explained
3263 in detail below. (The other three dependency fields,
3264 <tt>Recommends</tt>, <tt>Suggests</tt> and
3265 <tt>Enhances</tt>, are only used by the various front-ends
3266 to <prgn>dpkg</prgn> such as <prgn>dselect</prgn>.)
3270 For this reason packages in an installation run are usually
3271 all unpacked first and all configured later; this gives
3272 later versions of packages with dependencies on later
3273 versions of other packages the opportunity to have their
3274 dependencies satisfied.
3278 The <tt>Depends</tt> field thus allows package maintainers
3279 to impose an order in which packages should be configured.
3283 The meaning of the five dependency fields is as follows:
3285 <tag><tt>Depends</tt></tag>
3288 This declares an absolute dependency. A package will
3289 not be configured unless all of the packages listed in
3290 its <tt>Depends</tt> field have been correctly
3295 The <tt>Depends</tt> field should be used if the
3296 depended-on package is required for the depending
3297 package to provide a significant amount of
3301 The <tt>Depends</tt> field should also be used if the
3302 <prgn>postinst</prgn>, <prgn>prerm</prgn> or
3303 <prgn>postrm</prgn> scripts require the package to be
3304 present in order to run. Note, however, that the
3305 <prgn>postrm</prgn> cannot rely on any non-essential
3306 packages to be present during the <tt>purge</tt>
3310 <tag><tt>Recommends</tt></tag>
3312 <p>This declares a strong, but not absolute, dependency.
3316 The <tt>Recommends</tt> field should list packages
3317 that would be found together with this one in all but
3318 unusual installations.</p>
3321 <tag><tt>Suggests</tt></tag>
3324 This is used to declare that one package may be more
3325 useful with one or more others. Using this field
3326 tells the packaging system and the user that the
3327 listed packages are related to this one and can
3328 perhaps enhance its usefulness, but that installing
3329 this one without them is perfectly reasonable.
3333 <tag><tt>Enhances</tt></tag>
3336 This field is similar to Suggests but works in the
3337 opposite direction. It is used to declare that a
3338 package can enhance the functionality of another
3343 <tag><tt>Pre-Depends</tt></tag>
3346 This field is like <tt>Depends</tt>, except that it
3347 also forces <prgn>dpkg</prgn> to complete installation
3348 of the packages named before even starting the
3349 installation of the package which declares the
3350 pre-dependency, as follows:
3354 When a package declaring a pre-dependency is about to
3355 be <em>unpacked</em> the pre-dependency can be
3356 satisfied if the depended-on package is either fully
3357 configured, <em>or even if</em> the depended-on
3358 package(s) are only unpacked or half-configured,
3359 provided that they have been configured correctly at
3360 some point in the past (and not removed or partially
3361 removed since). In this case, both the
3362 previously-configured and currently unpacked or
3363 half-configured versions must satisfy any version
3364 clause in the <tt>Pre-Depends</tt> field.
3368 When the package declaring a pre-dependency is about
3369 to be <em>configured</em>, the pre-dependency will be
3370 treated as a normal <tt>Depends</tt>, that is, it will
3371 be considered satisfied only if the depended-on
3372 package has been correctly configured.
3376 <tt>Pre-Depends</tt> should be used sparingly,
3377 preferably only by packages whose premature upgrade or
3378 installation would hamper the ability of the system to
3379 continue with any upgrade that might be in progress.
3383 <tt>Pre-Depends</tt> are also required if the
3384 <prgn>preinst</prgn> script depends on the named
3385 package. It is best to avoid this situation if
3391 When selecting which level of dependency to use you should
3392 consider how important the depended-on package is to the
3393 functionality of the one declaring the dependency. Some
3394 packages are composed of components of varying degrees of
3395 importance. Such a package should list using
3396 <tt>Depends</tt> the package(s) which are required by the
3397 more important components. The other components'
3398 requirements may be mentioned as Suggestions or
3399 Recommendations, as appropriate to the components' relative
3404 <sect id="conflicts"><heading>Conflicting binary packages -
3405 <tt>Conflicts</tt></heading>
3408 When one binary package declares a conflict with another
3409 using a <tt>Conflicts</tt> field, <prgn>dpkg</prgn> will
3410 refuse to allow them to be installed on the system at the
3415 If one package is to be installed, the other must be removed
3416 first - if the package being installed is marked as
3417 replacing (see <ref id="replaces">) the one on the system,
3418 or the one on the system is marked as deselected, or both
3419 packages are marked <tt>Essential</tt>, then
3420 <prgn>dpkg</prgn> will automatically remove the package
3421 which is causing the conflict, otherwise it will halt the
3422 installation of the new package with an error. This
3423 mechanism is specifically designed to produce an error when
3424 the installed package is <tt>Essential</tt>, but the new
3429 A package will not cause a conflict merely because its
3430 configuration files are still installed; it must be at least
3435 A special exception is made for packages which declare a
3436 conflict with their own package name, or with a virtual
3437 package which they provide (see below): this does not
3438 prevent their installation, and allows a package to conflict
3439 with others providing a replacement for it. You use this
3440 feature when you want the package in question to be the only
3441 package providing some feature.
3445 A <tt>Conflicts</tt> entry should almost never have an
3446 "earlier than" version clause. This would prevent
3447 <prgn>dpkg</prgn> from upgrading or installing the package
3448 which declared such a conflict until the upgrade or removal
3449 of the conflicted-with package had been completed.
3453 <sect id="virtual"><heading>Virtual packages - <tt>Provides</tt>
3457 As well as the names of actual ("concrete") packages, the
3458 package relationship fields <tt>Depends</tt>,
3459 <tt>Recommends</tt>, <tt>Suggests</tt>, <tt>Enhances</tt>,
3460 <tt>Pre-Depends</tt>, <tt>Conflicts</tt>,
3461 <tt>Build-Depends</tt>, <tt>Build-Depends-Indep</tt>,
3462 <tt>Build-Conflicts</tt> and <tt>Build-Conflicts-Indep</tt>
3463 may mention "virtual packages".
3467 A <em>virtual package</em> is one which appears in the
3468 <tt>Provides</tt> control file field of another package.
3469 The effect is as if the package(s) which provide a
3470 particular virtual package name had been listed by name
3471 everywhere the virtual package name appears. (See also <ref
3472 id="virtual_pkg_sect">)
3476 If there are both concrete and virtual packages of the same
3477 name, then the dependency may be satisfied (or the conflict
3478 caused) by either the concrete package with the name in
3479 question or any other concrete package which provides the
3480 virtual package with the name in question. This is so that,
3481 for example, supposing we have
3482 <example compact="compact">
3486 and someone else releases an enhanced version of the
3487 <tt>bar</tt> package (for example, a non-US variant), they
3489 <example compact="compact">
3493 and the <tt>bar-plus</tt> package will now also satisfy the
3494 dependency for the <tt>foo</tt> package.
3498 If a dependency or a conflict has a version number attached
3499 then only real packages will be considered to see whether
3500 the relationship is satisfied (or the prohibition violated,
3501 for a conflict) - it is assumed that a real package which
3502 provides the virtual package is not of the "right" version.
3503 So, a <tt>Provides</tt> field may not contain version
3504 numbers, and the version number of the concrete package
3505 which provides a particular virtual package will not be
3506 looked at when considering a dependency on or conflict with
3507 the virtual package name.
3511 It is likely that the ability will be added in a future
3512 release of <prgn>dpkg</prgn> to specify a version number for
3513 each virtual package it provides. This feature is not yet
3514 present, however, and is expected to be used only
3519 If you want to specify which of a set of real packages
3520 should be the default to satisfy a particular dependency on
3521 a virtual package, you should list the real package as an
3522 alternative before the virtual one.
3527 <sect id="replaces"><heading>Overwriting files and replacing
3528 packages - <tt>Replaces</tt></heading>
3531 Packages can declare in their control file that they should
3532 overwrite files in certain other packages, or completely
3533 replace other packages. The <tt>Replaces</tt> control file
3534 field has these two distinct purposes.
3537 <sect1><heading>Overwriting files in other packages</heading>
3540 Firstly, as mentioned before, it is usually an error for a
3541 package to contain files which are on the system in
3546 However, if the overwriting package declares that it
3547 <tt>Replaces</tt> the one containing the file being
3548 overwritten, then <prgn>dpkg</prgn> will replace the file
3549 from the old package with that from the new. The file
3550 will no longer be listed as "owned" by the old package.
3554 If a package is completely replaced in this way, so that
3555 <prgn>dpkg</prgn> does not know of any files it still
3556 contains, it is considered to have "disappeared". It will
3557 be marked as not wanted on the system (selected for
3558 removal) and not installed. Any <tt>conffile</tt>s
3559 details noted for the package will be ignored, as they
3560 will have been taken over by the overwriting package. The
3561 package's <prgn>postrm</prgn> script will be run with a
3562 special argument to allow the package to do any final
3563 cleanup required. See <ref id="mscriptsinstact">.
3567 If an installed package, <tt>foo</tt> say, declares that
3568 it replaces another, <tt>bar</tt>, and an attempt is made
3569 to install <tt>bar</tt>, <prgn>dpkg</prgn> will discard
3570 files in the <tt>bar</tt> package which would overwrite
3571 those already present in <tt>foo</tt>. This is so that
3572 you can install an older version of a package without
3577 For this usage of <tt>Replaces</tt>, virtual packages (see
3578 <ref id="virtual">) are not considered when looking at a
3579 <tt>Replaces</tt> field - the packages declared as being
3580 replaced must be mentioned by their real names.
3584 Furthermore, this usage of <tt>Replaces</tt> only takes
3585 effect when both packages are at least partially on the
3586 system at once, so that it can only happen if they do not
3587 conflict or if the conflict has been overridden.
3592 <sect1><heading>Replacing whole packages, forcing their
3596 Secondly, <tt>Replaces</tt> allows the packaging system to
3597 resolve which package should be removed when there is a
3598 conflict - see <ref id="conflicts">. This usage only
3599 takes effect when the two packages <em>do</em> conflict,
3600 so that the two usages of this field do not interfere with
3605 In this situation, the package declared as being replaced
3606 can be a virtual package, so for example, all mail
3607 transport agents (MTAs) would have the following fields in
3608 their control files:
3609 <example compact="compact">
3610 Provides: mail-transport-agent
3611 Conflicts: mail-transport-agent
3612 Replaces: mail-transport-agent
3614 ensuring that only one MTA can be installed at any one
3619 <sect><heading>Relationships between source and binary packages -
3620 <tt>Build-Depends</tt>, <tt>Build-Depends-Indep</tt>,
3621 <tt>Build-Conflicts</tt>, <tt>Build-Conflicts-Indep</tt>
3625 Source packages that require certain binary packages to be
3626 installed or absent at the time of building the package
3627 can declare relationships to those binary packages.
3631 This is done using the <tt>Build-Depends</tt>,
3632 <tt>Build-Depends-Indep</tt>, <tt>Build-Conflicts</tt> and
3633 <tt>Build-Conflicts-Indep</tt> control file fields.
3637 Build-dependencies on "build-essential" binary packages can be
3638 omitted. Please see <ref id="pkg-relations"> for more information.
3642 The dependencies and conflicts they define must be satisfied
3643 (as defined earlier for binary packages) in order to invoke
3644 the targets in <tt>debian/rules</tt>, as follows:<footnote>
3646 If you make "build-arch" or "binary-arch", you need
3647 Build-Depends. If you make "build-indep" or
3648 "binary-indep", you need Build-Depends and
3649 Build-Depends-Indep. If you make "build" or "binary",
3653 There is no Build-Depends-Arch; the autobuilders will
3654 only need the Build-Depends if they know how to build
3655 only build-arch and binary-arch. Anyone building the
3656 build-indep/binary-indep targets is basically assumed to
3657 be building the whole package and so installs all build
3661 The purpose of the original split, I recall, was so that
3662 the autobuilders wouldn't need to install extra packages
3663 needed only for the binary-indep targets. But without a
3664 build-arch/build-indep split, this didn't work, since
3665 most of the work is done in the build target, not in the
3671 <tag><tt>Build-Depends</tt>, <tt>Build-Conflicts</tt></tag>
3674 The <tt>Build-Depends</tt> and
3675 <tt>Build-Conflicts</tt> fields must be satisfied when
3676 any of the following targets is invoked:
3677 <tt>build</tt>, <tt>clean</tt>, <tt>binary</tt>,
3678 <tt>binary-arch</tt>, <tt>build-arch</tt>,
3679 <tt>build-indep</tt> and <tt>binary-indep</tt>.
3682 <tag><tt>Build-Depends-Indep</tt>,
3683 <tt>Build-Conflicts-Indep</tt></tag>
3686 The <tt>Build-Depends-Indep</tt> and
3687 <tt>Build-Conflicts-Indep</tt> fields must be
3688 satisfied when any of the following targets is
3689 invoked: <tt>build</tt>, <tt>clean</tt>,
3690 <tt>build-indep</tt>, <tt>binary</tt> and
3691 <tt>binary-indep</tt>.
3702 <chapt id="conffiles"><heading>Configuration file handling
3706 This chapter has been superseded by <ref id="config-files">.
3710 <chapt id="sharedlibs"><heading>Shared libraries</heading>
3713 Packages containing shared libraries must be constructed with
3714 a little care to make sure that the shared library is always
3715 available. This is especially important for packages whose
3716 shared libraries are vitally important, such as the C library
3717 (currently <tt>libc6</tt>).
3721 Packages involving shared libraries should be split up into
3722 several binary packages. This section mostly deals with how
3723 this separation is to be accomplished; rules for files within
3724 the shared library packages are in <ref id="libraries"> instead.
3727 <sect id="sharedlibs-runtime">
3728 <heading>Run-time shared libraries</heading>
3731 The run-time shared library needs to be placed in a package called
3732 <package><var>libraryname</var><var>soversion</var></package>, where
3733 <file><var>soversion</var></file> is the version number in the
3734 soname of the shared library<footnote>
3736 The soname is the shared object name: it's the thing
3737 that has to match exactly between building an executable
3738 and running it for the dynamic linker to be able run the
3739 program. For example, if the soname of the library is
3740 <file>libfoo.so.6</file>, the library package would be
3741 called <file>libfoo6</file>.
3744 Alternatively, if it would be confusing to directly append
3745 <var>soversion</var> to <var>libraryname</var> (e.g. because
3746 <var>libraryname</var> itself ends in a number), you may use
3747 <package><var>libraryname</var>-<var>soversion</var></package> and
3748 <package><var>libraryname</var>-<var>soversion</var>-dev</package>
3753 If you have several shared libraries built from the same
3754 source tree you may lump them all together into a single
3755 shared library package, provided that you change all of
3756 their sonames at once (so that you don't get filename
3757 clashes if you try to install different versions of the
3758 combined shared libraries package).
3762 The package should install the shared libraries under
3763 their normal names. For example, the <package>libgdbmg1</package>
3764 package should install <file>libgdbm.so.1.7.3</file> as
3765 <file>/usr/lib/libgdbm.so.1.7.3</file>. The files should not be
3766 renamed or re-linked by any <prgn>prerm</prgn> or
3767 <prgn>postrm</prgn> scripts; <prgn>dpkg</prgn> will take care
3768 of renaming things safely without affecting running programs,
3769 and attempts to interfere with this are likely to lead to
3774 Shared libraries should not be installed executable, since
3775 the dynamic linker does not require this and trying to
3776 execute a shared library usually results in a core dump.
3780 The run-time library package should include the symbolic link that
3781 <prgn>ldconfig</prgn> would create for the shared libraries.
3782 For example, the <package>libgdbmg1</package> package should include
3783 a symbolic link from <file>/usr/lib/libgdbm.so.1</file> to
3784 <file>libgdbm.so.1.7.3</file>. This is needed so that the dynamic
3785 linker (for example <prgn>ld.so</prgn> or
3786 <prgn>ld-linux.so.*</prgn>) can find the library between the
3787 time that <prgn>dpkg</prgn> installs it and the time that
3788 <prgn>ldconfig</prgn> is run in the <prgn>postinst</prgn>
3791 The package management system requires the library to be
3792 placed before the symbolic link pointing to it in the
3793 <file>.deb</file> file. This is so that when
3794 <prgn>dpkg</prgn> comes to install the symlink
3795 (overwriting the previous symlink pointing at an older
3796 version of the library), the new shared library is already
3797 in place. In the past, this was achieved by creating the
3798 library in the temporary packaging directory before
3799 creating the symlink. Unfortunately, this was not always
3800 effective, since the building of the tar file in the
3801 <file>.deb</file> depended on the behavior of the underlying
3802 file system. Some file systems (such as reiserfs) reorder
3803 the files so that the order of creation is forgotten.
3804 Since version 1.7.0, <prgn>dpkg</prgn>
3805 reorders the files itself as necessary when building a
3806 package. Thus it is no longer important to concern
3807 oneself with the order of file creation.
3812 <sect1 id="ldconfig">
3813 <heading><tt>ldconfig</tt></heading>
3816 Any package installing shared libraries in one of the default
3817 library directories of the dynamic linker (which are currently
3818 <file>/usr/lib</file> and <file>/lib</file>) or a directory that is
3819 listed in <file>/etc/ld.so.conf</file><footnote>
3822 <list compact="compact">
3823 <item><p>/usr/X11R6/lib/Xaw3d</p></item>
3824 <item><p>/usr/local/lib</p></item>
3825 <item><p>/usr/lib/libc5-compat</p></item>
3826 <item><p>/lib/libc5-compat</p></item>
3827 <item><p>/usr/X11R6/lib</p></item>
3831 must use <prgn>ldconfig</prgn> to update the shared library
3836 The package must call <prgn>ldconfig</prgn> in the
3837 <prgn>postinst</prgn> script if the first argument is
3838 <tt>configure</tt>; the <prgn>postinst</prgn> script may
3839 optionally invoke <prgn>ldconfig</prgn> at other times. The
3840 package should call <prgn>ldconfig</prgn> in the
3841 <prgn>postrm</prgn> script if the first argument is
3842 <tt>remove</tt>. The maintainer scripts must not invoke
3843 <prgn>ldconfig</prgn> under any circumstances other than those
3844 described in this paragraph.<footnote>
3845 <p>During install or upgrade, the preinst is called before
3846 the new files are installed, so calling "ldconfig" is
3847 pointless. The preinst of an existing package can also be
3848 called if an upgrade fails. However, this happens during
3849 the critical time when a shared libs may exist on-disk
3850 under a temporary name. Thus, it is dangerous and
3851 forbidden by current policy to call "ldconfig" at this
3854 <p>When a package is installed or upgraded, "postinst
3855 configure" runs after the new files are safely on-disk.
3856 Since it is perfectly safe to invoke ldconfig
3857 unconditionally in a postinst, it is OK for a package to
3858 simply put ldconfig in its postinst without checking the
3859 argument. The postinst can also be called to recover from
3860 a failed upgrade. This happens before any new files are
3861 unpacked, so there is no reason to call "ldconfig" at this
3864 <p>For a package that is being removed, prerm is
3865 called with all the files intact, so calling ldconfig is
3866 useless. The other calls to "prerm" happen in the case of
3867 upgrade at a time when all the files of the old package
3868 are on-disk, so again calling "ldconfig" is pointless.
3870 <p>postrm, on the other hand, is called with the "remove"
3871 argument just after the files are removed, so this is the
3872 proper time to call "ldconfig" to notify the system of the
3873 fact shared libraries from the package are removed.
3874 The postrm can be called at several other times. At the
3875 time of "postrm purge", "postrm abort-install", or "postrm
3876 abort-upgrade", calling "ldconfig" is useless because the
3877 shared lib files are not on-disk. However, when "postrm"
3878 is invoked with arguments "upgrade", "failed-upgrade", or
3879 "disappear", a shared lib may exist on-disk under a
3888 <sect id="sharedlibs-runtime-progs">
3889 <heading>Run-time support programs</heading>
3892 If your package has some run-time support programs which use
3893 the shared library you must not put them in the shared
3894 library package. If you do that then you won't be able to
3895 install several versions of the shared library without
3896 getting filename clashes.
3900 Instead, either create another package for the runtime binaries
3901 (this package might typically be named
3902 <package><var>libraryname</var>-runtime</package>; note the absence
3903 of the <var>soversion</var> in the package name), or if the
3904 development package is small, include them in there.
3908 <sect id="sharedlibs-static">
3909 <heading>Static libraries</heading>
3912 The static library (<file><var>libraryname.a</var></file>)
3913 is usually provided in addition to the shared version.
3914 It is placed into the development package (see below).
3918 In some cases, it is acceptable for a library to be
3919 available in static form only; these cases include:
3921 <item>libraries for languages whose shared library support
3922 is immature or unstable</item>
3923 <item>libraries whose interfaces are in flux or under
3924 development (commonly the case when the library's
3925 major version number is zero, or where the ABI breaks
3926 across patchlevels)</item>
3927 <item>libraries which are explicitly intended to be
3928 available only in static form by their upstream
3933 <sect id="sharedlibs-dev">
3934 <heading>Development files</heading>
3937 The development files associated to a shared library need to be
3938 placed in a package called
3939 <package><var>libraryname</var><var>soversion</var>-dev</package>,
3940 or if you prefer only to support one development version at a
3941 time, <package><var>libraryname</var>-dev</package>.
3945 In case several development versions of a library exist, you may
3946 need to use <prgn>dpkg</prgn>'s Conflicts mechanism (see
3947 <ref id="conflicts">) to ensure that the user only installs one
3948 development version at a time (as different development versions are
3949 likely to have the same header files in them, which would cause a
3950 filename clash if both were installed).
3954 The development package should contain a symlink for the associated
3955 shared library without a version number. For example, the
3956 <package>libgdbmg1-dev</package> package should include a symlink
3957 from <file>/usr/lib/libgdbm.so</file> to
3958 <file>libgdbm.so.1.7.3</file>. This symlink is needed by the linker
3959 (<prgn>ld</prgn>) when compiling packages, as it will only look for
3960 <file>libgdbm.so</file> when compiling dynamically.
3964 <sect id="sharedlibs-intradeps">
3965 <heading>Dependencies between the packages of the same library</heading>
3968 Typically the development version should have an exact
3969 version dependency on the runtime library, to make sure that
3970 compilation and linking happens correctly. The
3971 <tt>${Source-Version}</tt> substitution variable can be
3972 useful for this purpose.
3976 <sect id="sharedlibs-shlibdeps">
3977 <heading>Dependencies between the library and other packages -
3978 the <tt>shlibs</tt> system</heading>
3981 If a package contains a binary or library which links to a
3982 shared library, we must ensure that when the package is
3983 installed on the system, all of the libraries needed are
3984 also installed. This requirement led to the creation of the
3985 <tt>shlibs</tt> system, which is very simple in its design:
3986 any package which <em>provides</em> a shared library also
3987 provides information on the package dependencies required to
3988 ensure the presence of this library, and any package which
3989 <em>uses</em> a shared library uses this information to
3990 determine the dependencies it requires. The files which
3991 contain the mapping from shared libraries to the necessary
3992 dependency information are called <file>shlibs</file> files.
3996 Thus, when a package is built which contains any shared
3997 libraries, it must provide a <file>shlibs</file> file for other
3998 packages to use, and when a package is built which contains
3999 any shared libraries or compiled binaries, it must run
4000 <prgn>dpkg-shlibdeps</prgn> on these to determine the
4001 libraries used and hence the dependencies needed by this
4004 In the past, the shared libraries linked to were
4005 determined by calling <prgn>ldd</prgn>, but now
4006 <prgn>objdump</prgn> is used to do this. The only
4007 change this makes to package building is that
4008 <prgn>dpkg-shlibdeps</prgn> must also be run on shared
4009 libraries, whereas in the past this was unnecessary.
4010 The rest of this footnote explains the advantage that
4015 We say that a binary <tt>foo</tt> <em>directly</em> uses
4016 a library <tt>libbar</tt> if it is explicitly linked
4017 with that library (that is, it uses the flag
4018 <tt>-lbar</tt> during the linking stage). Other
4019 libraries that are needed by <tt>libbar</tt> are linked
4020 <em>indirectly</em> to <tt>foo</tt>, and the dynamic
4021 linker will load them automatically when it loads
4022 <tt>libbar</tt>. A package should depend on
4023 the libraries it directly uses, and the dependencies for
4024 those libraries should automatically pull in the other
4029 Unfortunately, the <prgn>ldd</prgn> program shows both
4030 the directly and indirectly used libraries, meaning that
4031 the dependencies determined included both direct and
4032 indirect dependencies. The use of <prgn>objdump</prgn>
4033 avoids this problem by determining only the directly
4038 A good example of where this helps is the following. We
4039 could update <tt>libimlib</tt> with a new version that
4040 supports a new graphics format called dgf (but retaining
4041 the same major version number). If we used the old
4042 <prgn>ldd</prgn> method, every package that uses
4043 <tt>libimlib</tt> would need to be recompiled so it
4044 would also depend on <tt>libdgf</tt> or it wouldn't run
4045 due to missing symbols. However with the new system,
4046 packages using <tt>libimlib</tt> can rely on
4047 <tt>libimlib</tt> itself having the dependency on
4048 <tt>libdgf</tt> and so they would not need rebuilding.
4054 In the following sections, we will first describe where the
4055 various <tt>shlibs</tt> files are to be found, then how to
4056 use <prgn>dpkg-shlibdeps</prgn>, and finally the
4057 <tt>shlibs</tt> file format and how to create them if your
4058 package contains a shared library.
4062 <heading>The <tt>shlibs</tt> files present on the system</heading>
4065 There are several places where <tt>shlibs</tt> files are
4066 found. The following list gives them in the order in which
4067 they are read by <prgn>dpkg-shlibdeps</prgn>. (The first
4068 one which gives the required information is used.)
4074 <p><file>debian/shlibs.local</file></p>
4076 This lists overrides for this package. Its use is
4077 described below (see <ref id="shlibslocal">).
4082 <p><file>/etc/dpkg/shlibs.override</file></p>
4084 This lists global overrides. This list is normally
4085 empty. It is maintained by the local system
4091 <p><file>DEBIAN/shlibs</file> files in the "build directory"</p>
4093 When packages are being built, any
4094 <file>debian/shlibs</file> files are copied into the
4095 control file area of the temporary build directory and
4096 given the name <file>shlibs</file>. These files give
4097 details of any shared libraries included in the
4100 An example may help here. Let us say that the
4101 source package <tt>foo</tt> generates two binary
4102 packages, <tt>libfoo2</tt> and
4103 <tt>foo-runtime</tt>. When building the binary
4104 packages, the two packages are created in the
4105 directories <file>debian/libfoo2</file> and
4106 <file>debian/foo-runtime</file> respectively.
4107 (<file>debian/tmp</file> could be used instead of one
4108 of these.) Since <tt>libfoo2</tt> provides the
4109 <tt>libfoo</tt> shared library, it will require a
4110 <tt>shlibs</tt> file, which will be installed in
4111 <file>debian/libfoo2/DEBIAN/shlibs</file>, eventually
4113 <file>/var/lib/dpkg/info/libfoo2.shlibs</file>. Then
4114 when <prgn>dpkg-shlibdeps</prgn> is run on the
4116 <file>debian/foo-runtime/usr/bin/foo-prog</file>, it
4118 <file>debian/libfoo2/DEBIAN/shlibs</file> file to
4119 determine whether <tt>foo-prog</tt>'s library
4120 dependencies are satisfied by any of the libraries
4121 provided by <tt>libfoo2</tt>. For this reason,
4122 <prgn>dpkg-shlibdeps</prgn> must only be run once
4123 all of the individual binary packages'
4124 <tt>shlibs</tt> files have been installed into the
4132 <p><file>/var/lib/dpkg/info/*.shlibs</file></p>
4134 These are the <file>shlibs</file> files corresponding to
4135 all of the packages installed on the system, and are
4136 maintained by the relevant package maintainers.
4141 <p><file>/etc/dpkg/shlibs.default</file></p>
4143 This file lists any shared libraries whose packages
4144 have failed to provide correct <file>shlibs</file> files.
4145 It was used when the <file>shlibs</file> setup was first
4146 introduced, but it is now normally empty. It is
4147 maintained by the <tt>dpkg</tt> maintainer.
4155 <heading>How to use <prgn>dpkg-shlibdeps</prgn> and the
4156 <file>shlibs</file> files</heading>
4159 Put a call to <prgn>dpkg-shlibdeps</prgn> into your
4160 <file>debian/rules</file> file. If your package contains only
4161 compiled binaries and libraries (but no scripts), you can
4162 use a command such as:
4163 <example compact="compact">
4164 dpkg-shlibdeps debian/tmp/usr/bin/* debian/tmp/usr/sbin/* \
4165 debian/tmp/usr/lib/*
4167 Otherwise, you will need to explicitly list the compiled
4168 binaries and libraries.<footnote>
4170 If you are using <tt>debhelper</tt>, the
4171 <prgn>dh_shlibdeps</prgn> program will do this work for
4172 you. It will also correctly handle multi-binary
4179 This command puts the dependency information into the
4180 <file>debian/substvars</file> file, which is then used by
4181 <prgn>dpkg-gencontrol</prgn>. You will need to place a
4182 <tt>${shlib:Depends}</tt> variable in the <tt>Depends</tt>
4183 field in the control file for this to work.
4187 If <prgn>dpkg-shlibdeps</prgn> doesn't complain, you're
4188 done. If it does complain you might need to create your own
4189 <file>debian/shlibs.local</file> file, as explained below (see
4190 <ref id="shlibslocal">).
4194 If you have multiple binary packages, you will need to call
4195 <prgn>dpkg-shlibdeps</prgn> on each one which contains
4196 compiled libraries or binaries. In such a case, you will
4197 need to use the <tt>-T</tt> option to the <tt>dpkg</tt>
4198 utilities to specify a different <file>substvars</file> file.
4199 For more details on this and other options, see <manref
4200 name="dpkg-shlibdeps" section="1">.
4205 <heading>The <file>shlibs</file> File Format</heading>
4208 Each <file>shlibs</file> file has the same format. Lines
4209 beginning with <tt>#</tt> are considered to be comments and
4210 are ignored. Each line is of the form:
4211 <example compact="compact">
4212 <var>library-name</var> <var>soname-version-number</var> <var>dependencies ...</var>
4217 We will explain this by reference to the example of the
4218 <tt>zlib1g</tt> package, which (at the time of writing)
4219 installs the shared library <file>/usr/lib/libz.so.1.1.3</file>.
4223 <var>library-name</var> is the name of the shared library,
4224 in this case <tt>libz</tt>. (This must match the name part
4225 of the soname, see below.)
4229 <var>soname-version-number</var> is the version part of the
4230 soname of the library. The soname is the thing that must
4231 exactly match for the library to be recognized by the
4232 dynamic linker, and is usually of the form
4233 <tt><var>name</var>.so.<var>major-version</var></tt>, in our
4234 example, <tt>libz.so.1</tt>.<footnote>
4236 This can be determined using the command
4237 <example compact="compact">
4238 objdump -p /usr/lib/libz.so.1.1.3 | grep SONAME
4242 The version part is the part which comes after
4243 <tt>.so.</tt>, so in our case, it is <tt>1</tt>.
4247 <var>dependencies</var> has the same syntax as a dependency
4248 field in a binary package control file. It should give
4249 details of which packages are required to satisfy a binary
4250 built against the version of the library contained in the
4251 package. See <ref id="depsyntax"> for details.
4255 In our example, if the first version of the <tt>zlib1g</tt>
4256 package which contained a minor number of at least
4257 <tt>1.3</tt> was <var>1:1.1.3-1</var>, then the
4258 <tt>shlibs</tt> entry for this library could say:
4259 <example compact="compact">
4260 libz 1 zlib1g (>= 1:1.1.3)
4262 The version-specific dependency is to avoid warnings from
4263 the dynamic linker about using older shared libraries with
4269 <heading>Providing a <file>shlibs</file> file</heading>
4272 If your package provides a shared library, you should create
4273 a <file>shlibs</file> file following the format described above.
4274 It is usual to call this file <file>debian/shlibs</file> (but if
4275 you have multiple binary packages, you might want to call it
4276 <file>debian/shlibs.<var>package</var></file> instead). Then
4277 let <file>debian/rules</file> install it in the control area:
4278 <example compact="compact">
4279 install -m644 debian/shlibs debian/tmp/DEBIAN
4281 or, in the case of a multi-binary package:
4282 <example compact="compact">
4283 install -m644 debian/shlibs.<var>package</var> debian/<var>package</var>/DEBIAN/shlibs
4285 An alternative way of doing this is to create the
4286 <file>shlibs</file> file in the control area directly from
4287 <file>debian/rules</file> without using a <file>debian/shlibs</file>
4288 file at all,<footnote>
4290 This is what <prgn>dh_makeshlibs</prgn> in the
4291 <tt>debhelper</tt> suite does.
4294 since the <file>debian/shlibs</file> file itself is ignored by
4295 <prgn>dpkg-shlibdeps</prgn>.
4299 As <prgn>dpkg-shlibdeps</prgn> reads the
4300 <file>DEBIAN/shlibs</file> files in all of the binary packages
4301 being built from this source package, all of the
4302 <file>DEBIAN/shlibs</file> files should be installed before
4303 <prgn>dpkg-shlibdeps</prgn> is called on any of the binary
4308 <sect1 id="shlibslocal">
4309 <heading>Writing the <file>debian/shlibs.local</file> file</heading>
4312 This file is intended only as a <em>temporary</em> fix if
4313 your binaries or libraries depend on a library whose package
4314 does not yet provide a correct <file>shlibs</file> file.
4318 We will assume that you are trying to package a binary
4319 <tt>foo</tt>. When you try running
4320 <prgn>dpkg-shlibdeps</prgn> you get the following error
4321 message (<tt>-O</tt> displays the dependency information on
4322 <tt>stdout</tt> instead of writing it to
4323 <tt>debian/substvars</tt>, and the lines have been wrapped
4324 for ease of reading):
4325 <example compact="compact">
4326 $ dpkg-shlibdeps -O debian/tmp/usr/bin/foo
4327 dpkg-shlibdeps: warning: unable to find dependency
4328 information for shared library libbar (soname 1,
4329 path /usr/lib/libbar.so.1, dependency field Depends)
4330 shlibs:Depends=libc6 (>= 2.2.2-2)
4332 You can then run <prgn>ldd</prgn> on the binary to find the
4333 full location of the library concerned:
4334 <example compact="compact">
4336 libbar.so.1 => /usr/lib/libbar.so.1 (0x4001e000)
4337 libc.so.6 => /lib/libc.so.6 (0x40032000)
4338 /lib/ld-linux.so.2 => /lib/ld-linux.so.2 (0x40000000)
4340 So the <prgn>foo</prgn> binary depends on the
4341 <prgn>libbar</prgn> shared library, but no package seems to
4342 provide a <file>*.shlibs</file> file handling
4343 <file>libbar.so.1</file> in <file>/var/lib/dpkg/info/</file>. Let's
4344 determine the package responsible:
4345 <example compact="compact">
4346 $ dpkg -S /usr/lib/libbar.so.1
4347 bar1: /usr/lib/libbar.so.1
4348 $ dpkg -s bar1 | grep Version
4351 This tells us that the <tt>bar1</tt> package, version 1.0-1,
4352 is the one we are using. Now we can file a bug against the
4353 <tt>bar1</tt> package and create our own
4354 <file>debian/shlibs.local</file> to locally fix the problem.
4355 Including the following line into your
4356 <file>debian/shlibs.local</file> file:
4357 <example compact="compact">
4358 libbar 1 bar1 (>= 1.0-1)
4360 should allow the package build to work.
4364 As soon as the maintainer of <tt>bar1</tt> provides a
4365 correct <file>shlibs</file> file, you should remove this line
4366 from your <file>debian/shlibs.local</file> file. (You should
4367 probably also then have a versioned <tt>Build-Depends</tt>
4368 on <tt>bar1</tt> to help ensure that others do not have the
4369 same problem building your package.)
4377 <chapt id="opersys"><heading>The Operating System</heading>
4380 <heading>Filesystem hierarchy</heading>
4384 <heading>Filesystem Structure</heading>
4387 The location of all installed files and directories must
4388 comply with the Filesystem Hierarchy Standard (FHS),
4389 version 2.1, except where doing so would violate other
4390 terms of Debian Policy. The version of this document
4391 referred here can be found in the <tt>debian-policy</tt>
4393 <url id="http://www.debian.org/doc/packaging-manuals/fhs/"
4394 name="FHS (Debian copy)"> alongside this manual (or, if
4395 you have the <package>debian-policy</package> installed,
4397 id="file:///usr/share/doc/debian-policy/fhs/" name="FHS
4398 (local copy)">). The
4399 latest version, which may be a more recent version, may
4401 <url id="http://www.pathname.com/fhs/" name="FHS (upstream)">.
4402 Specific questions about following the standard may be
4403 asked on the <tt>debian-devel</tt> mailing list, or
4404 referred to the FHS mailing list (see the
4405 <url id="http://www.pathname.com/fhs/" name="FHS web site"> for
4411 <heading>Site-specific programs</heading>
4414 As mandated by the FHS, packages must not place any
4415 files in <file>/usr/local</file>, either by putting them in
4416 the file system archive to be unpacked by <prgn>dpkg</prgn>
4417 or by manipulating them in their maintainer scripts.
4421 However, the package may create empty directories below
4422 <file>/usr/local</file> so that the system administrator knows
4423 where to place site-specific files. These directories
4424 should be removed on package removal if they are
4429 Note, that this applies only to directories <em>below</em>
4430 <file>/usr/local</file>, not <em>in</em> <file>/usr/local</file>.
4431 Packages must not create sub-directories in the directory
4432 <file>/usr/local</file> itself, except those listed in FHS,
4433 section 4.5. However, you may create directories below
4434 them as you wish. You must not remove any of the
4435 directories listed in 4.5, even if you created them.
4439 Since <file>/usr/local</file> can be mounted read-only from a
4440 remote server, these directories must be created and
4441 removed by the <prgn>postinst</prgn> and <prgn>prerm</prgn>
4442 maintainer scripts and not be included in the
4443 <file>.deb</file> archive. These scripts must not fail if
4444 either of these operations fail.
4448 For example, the <tt>emacsen-common</tt> package could
4449 contain something like
4450 <example compact="compact">
4451 if [ ! -e /usr/local/share/emacs ]
4453 if mkdir /usr/local/share/emacs 2>/dev/null
4455 chown root:staff /usr/local/share/emacs
4456 chmod 2775 /usr/local/share/emacs
4460 in its <prgn>postinst</prgn> script, and
4461 <example compact="compact">
4462 rmdir /usr/local/share/emacs/site-lisp 2>/dev/null || true
4463 rmdir /usr/local/share/emacs 2>/dev/null || true
4465 in the <prgn>prerm</prgn> script. (Note that this form is
4466 used to ensure that if the script is interrupted, the
4467 directory <file>/usr/local/share/emacs</file> will still be
4472 If you do create a directory in <file>/usr/local</file> for
4473 local additions to a package, you should ensure that
4474 settings in <file>/usr/local</file> take precedence over the
4475 equivalents in <file>/usr</file>.
4479 However, because <file>/usr/local</file> and its contents are
4480 for exclusive use of the local administrator, a package
4481 must not rely on the presence or absence of files or
4482 directories in <file>/usr/local</file> for normal operation.
4486 The <file>/usr/local</file> directory itself and all the
4487 subdirectories created by the package should (by default) have
4488 permissions 2775 (group-writable and set-group-id) and be
4489 owned by <tt>root.staff</tt>.
4494 <heading>The system-wide mail directory</heading>
4496 The system-wide mail directory is <file>/var/mail</file>. This
4497 directory is part of the base system and should not owned
4498 by any particular mail agents. The use of the old
4499 location <file>/var/spool/mail</file> is deprecated, even
4500 though the spool may still be physically located there.
4501 To maintain partial upgrade compatibility for systems
4502 which have <file>/var/spool/mail</file> as their physical mail
4503 spool, packages using <file>/var/mail</file> must depend on
4504 either <package>libc6</package> (>= 2.1.3-13), or on
4505 <package>base-files</package> (>= 2.2.0), or on later
4506 versions of either one of these packages.
4512 <heading>Users and groups</heading>
4515 <heading>Introduction</heading>
4517 The Debian system can be configured to use either plain or
4522 Some user ids (UIDs) and group ids (GIDs) are reserved
4523 globally for use by certain packages. Because some
4524 packages need to include files which are owned by these
4525 users or groups, or need the ids compiled into binaries,
4526 these ids must be used on any Debian system only for the
4527 purpose for which they are allocated. This is a serious
4528 restriction, and we should avoid getting in the way of
4529 local administration policies. In particular, many sites
4530 allocate users and/or local system groups starting at 100.
4534 Apart from this we should have dynamically allocated ids,
4535 which should by default be arranged in some sensible
4536 order, but the behavior should be configurable.
4540 Packages other than <tt>base-passwd</tt> must not modify
4541 <file>/etc/passwd</file>, <file>/etc/shadow</file>,
4542 <file>/etc/group</file> or <file>/etc/gshadow</file>.
4547 <heading>UID and GID classes</heading>
4549 The UID and GID numbers are divided into classes as
4555 Globally allocated by the Debian project, the same
4556 on every Debian system. These ids will appear in
4557 the <file>passwd</file> and <file>group</file> files of all
4558 Debian systems, new ids in this range being added
4559 automatically as the <tt>base-passwd</tt> package is
4564 Packages which need a single statically allocated
4565 uid or gid should use one of these; their
4566 maintainers should ask the <tt>base-passwd</tt>
4574 Dynamically allocated system users and groups.
4575 Packages which need a user or group, but can have
4576 this user or group allocated dynamically and
4577 differently on each system, should use <tt>adduser
4578 --system</tt> to create the group and/or user.
4579 <prgn>adduser</prgn> will check for the existence of
4580 the user or group, and if necessary choose an unused
4581 id based on the ranges specified in
4582 <file>adduser.conf</file>.
4586 <tag>1000-29999:</tag>
4589 Dynamically allocated user accounts. By default
4590 <prgn>adduser</prgn> will choose UIDs and GIDs for
4591 user accounts in this range, though
4592 <file>adduser.conf</file> may be used to modify this
4597 <tag>30000-59999:</tag>
4602 <tag>60000-64999:</tag>
4605 Globally allocated by the Debian project, but only
4606 created on demand. The ids are allocated centrally
4607 and statically, but the actual accounts are only
4608 created on users' systems on demand.
4612 These ids are for packages which are obscure or
4613 which require many statically-allocated ids. These
4614 packages should check for and create the accounts in
4615 <file>/etc/passwd</file> or <file>/etc/group</file> (using
4616 <prgn>adduser</prgn> if it has this facility) if
4617 necessary. Packages which are likely to require
4618 further allocations should have a "hole" left after
4619 them in the allocation, to give them room to
4624 <tag>65000-65533:</tag>
4632 User <tt>nobody</tt>. The corresponding gid refers
4633 to the group <tt>nogroup</tt>.
4640 <tt>(uid_t)(-1) == (gid_t)(-1)</tt> <em>must
4641 not</em> be used, because it is the error return
4650 <sect id="sysvinit">
4651 <heading>System run levels and <file>init.d</file> scripts</heading>
4653 <sect1 id="/etc/init.d">
4654 <heading>Introduction</heading>
4657 The <file>/etc/init.d</file> directory contains the scripts
4658 executed by <prgn>init</prgn> at boot time and when the
4659 init state (or "runlevel") is changed (see <manref
4660 name="init" section="8">).
4664 There are at least two different, yet functionally
4665 equivalent, ways of handling these scripts. For the sake
4666 of simplicity, this document describes only the symbolic
4667 link method. However, it must not be assumed by maintainer
4668 scripts that this method is being used, and any automated
4669 manipulation of the various runlevel behaviours by
4670 maintainer scripts must be performed using
4671 <prgn>update-rc.d</prgn> as described below and not by
4672 manually installing or removing symlinks. For information
4673 on the implementation details of the other method,
4674 implemented in the <tt>file-rc</tt> package, please refer
4675 to the documentation of that package.
4679 These scripts are referenced by symbolic links in the
4680 <file>/etc/rc<var>n</var>.d</file> directories. When changing
4681 runlevels, <prgn>init</prgn> looks in the directory
4682 <file>/etc/rc<var>n</var>.d</file> for the scripts it should
4683 execute, where <tt><var>n</var></tt> is the runlevel that
4684 is being changed to, or <tt>S</tt> for the boot-up
4689 The names of the links all have the form
4690 <file>S<var>mm</var><var>script</var></file> or
4691 <file>K<var>mm</var><var>script</var></file> where
4692 <var>mm</var> is a two-digit number and <var>script</var>
4693 is the name of the script (this should be the same as the
4694 name of the actual script in <file>/etc/init.d</file>).
4698 When <prgn>init</prgn> changes runlevel first the targets
4699 of the links whose names start with a <tt>K</tt> are
4700 executed, each with the single argument <tt>stop</tt>,
4701 followed by the scripts prefixed with an <tt>S</tt>, each
4702 with the single argument <tt>start</tt>. (The links are
4703 those in the <file>/etc/rc<var>n</var>.d</file> directory
4704 corresponding to the new runlevel.) The <tt>K</tt> links
4705 are responsible for killing services and the <tt>S</tt>
4706 link for starting services upon entering the runlevel.
4710 For example, if we are changing from runlevel 2 to
4711 runlevel 3, init will first execute all of the <tt>K</tt>
4712 prefixed scripts it finds in <file>/etc/rc3.d</file>, and then
4713 all of the <tt>S</tt> prefixed scripts in that directory.
4714 The links starting with <tt>K</tt> will cause the
4715 referred-to file to be executed with an argument of
4716 <tt>stop</tt>, and the <tt>S</tt> links with an argument
4721 The two-digit number <var>mm</var> is used to determine
4722 the order in which to run the scripts: low-numbered links
4723 have their scripts run first. For example, the
4724 <tt>K20</tt> scripts will be executed before the
4725 <tt>K30</tt> scripts. This is used when a certain service
4726 must be started before another. For example, the name
4727 server <prgn>bind</prgn> might need to be started before
4728 the news server <prgn>inn</prgn> so that <prgn>inn</prgn>
4729 can set up its access lists. In this case, the script
4730 that starts <prgn>bind</prgn> would have a lower number
4731 than the script that starts <prgn>inn</prgn> so that it
4733 <example compact="compact">
4740 The two runlevels 0 (halt) and 6 (reboot) are slightly
4741 different. In these runlevels, the links with an
4742 <tt>S</tt> prefix are still called after those with a
4743 <tt>K</tt> prefix, but they too are called with the single
4744 argument <tt>stop</tt>.
4748 Also, if the script name ends <tt>.sh</tt>, the script
4749 will be sourced in runlevel <tt>S</tt> rather that being
4750 run in a forked subprocess, but will be explicitly run by
4751 <prgn>sh</prgn> in all other runlevels.
4756 <heading>Writing the scripts</heading>
4759 Packages that include daemons for system services should
4760 place scripts in <file>/etc/init.d</file> to start or stop
4761 services at boot time or during a change of runlevel.
4762 These scripts should be named
4763 <file>/etc/init.d/<var>package</var></file>, and they should
4764 accept one argument, saying what to do:
4767 <tag><tt>start</tt></tag>
4768 <item><p>start the service,</p></item>
4770 <tag><tt>stop</tt></tag>
4771 <item><p>stop the service,</p></item>
4773 <tag><tt>restart</tt></tag>
4774 <item><p>stop and restart the service if it's already
4775 running, otherwise start the service</p></item>
4777 <tag><tt>reload</tt></tag>
4778 <item><p>cause the configuration of the service to be
4779 reloaded without actually stopping and restarting
4780 the service,</p></item>
4782 <tag><tt>force-reload</tt></tag>
4783 <item><p>cause the configuration to be reloaded if the
4784 service supports this, otherwise restart the
4788 The <tt>start</tt>, <tt>stop</tt>, <tt>restart</tt>, and
4789 <tt>force-reload</tt> options should be supported by all
4790 scripts in <file>/etc/init.d</file>, the <tt>reload</tt>
4791 option is optional.</p>
4794 The <file>init.d</file> scripts should ensure that they will
4795 behave sensibly if invoked with <tt>start</tt> when the
4796 service is already running, or with <tt>stop</tt> when it
4797 isn't, and that they don't kill unfortunately-named user
4798 processes. The best way to achieve this is usually to use
4799 <prgn>start-stop-daemon</prgn>.</p>
4802 If a service reloads its configuration automatically (as
4803 in the case of <prgn>cron</prgn>, for example), the
4804 <tt>reload</tt> option of the <file>init.d</file> script
4805 should behave as if the configuration has been reloaded
4809 The <file>/etc/init.d</file> scripts must be treated as
4810 configuration files, either (if they are present in the
4811 package, that is, in the .deb file) by marking them as
4812 <tt>conffile</tt>s, or, (if they do not exist in the .deb)
4813 by managing them correctly in the maintainer scripts (see
4814 <ref id="config-files">). This is important since we want
4815 to give the local system administrator the chance to adapt
4816 the scripts to the local system, e.g., to disable a
4817 service without de-installing the package, or to specify
4818 some special command line options when starting a service,
4819 while making sure her changes aren't lost during the next
4824 These scripts should not fail obscurely when the
4825 configuration files remain but the package has been
4826 removed, as configuration files remain on the system after
4827 the package has been removed. Only when <prgn>dpkg</prgn>
4828 is executed with the <tt>--purge</tt> option will
4829 configuration files be removed. In particular, as the
4830 <file>/etc/init.d/<var>package</var></file> script itself is
4831 usually a <tt>conffile</tt>, it will remain on the system
4832 if the package is removed but not purged. Therefore, you
4833 should include a <tt>test</tt> statement at the top of the
4835 <example compact="compact">
4836 test -f <var>program-executed-later-in-script</var> || exit 0
4841 Often there are some variables in the <file>init.d</file>
4842 scripts whose values control the behaviour of the scripts,
4843 and which a system administrator is likely to want to
4844 change. As the scripts themselves are frequently
4845 <tt>conffile</tt>s, modifying them requires that the
4846 administrator merge in their changes each time the package
4847 is upgraded and the <tt>conffile</tt> changes. To ease
4848 the burden on the system administrator, such configurable
4849 values should not be placed directly in the script.
4850 Instead, they should be placed in a file in
4851 <file>/etc/default</file>, which typically will have the same
4852 base name as the <file>init.d</file> script. This extra file
4853 should be sourced by the script when the script runs. It
4854 must contain only variable settings and comments in POSIX
4855 <prgn>sh</prgn> format. It may either be a
4856 <tt>conffile</tt> or a configuration file maintained by
4857 the package maintainer scripts. See <ref id="config-files">
4862 To ensure that vital configurable values are always
4863 available, the <file>init.d</file> script should set default
4864 values for each of the shell variables it uses, either
4865 before sourcing the <file>/etc/default/</file> file or
4866 afterwards using something like the <tt>:
4867 ${VAR:=default}</tt> syntax. Also, the <file>init.d</file>
4868 script must behave sensibly and not fail if the
4869 <file>/etc/default</file> file is deleted.
4874 <heading>Interfacing with the initscript system</heading>
4877 Maintainers should use the abstraction layer provided by
4878 the <prgn>update-rc.d</prgn> and <prgn>invoke-rc.d</prgn>
4879 programs to deal with initscripts in their packages'
4880 scripts such as <prgn>postinst</prgn>, <prgn>prerm</prgn>
4881 and <prgn>postrm</prgn>.
4884 Directly managing the /etc/rc?.d links and directly
4885 invoking the <file>/etc/init.d/</file> initscripts should
4886 be done only by packages providing the initscript
4887 subsystem (such as <prgn>sysvinit</prgn> and
4888 <prgn>file-rc</prgn>).
4893 <heading>Managing the links</heading>
4896 The program <prgn>update-rc.d</prgn> is provided for
4897 package maintainers to arrange for the proper creation and
4898 removal of <file>/etc/rc<var>n</var>.d</file> symbolic links,
4899 or their functional equivalent if another method is being
4900 used. This may be used by maintainers in their packages'
4901 <prgn>postinst</prgn> and <prgn>postrm</prgn> scripts.</p>
4904 You must not include any <file>/etc/rc<var>n</var>.d</file>
4905 symbolic links in the actual archive or manually create or
4906 remove the symbolic links in maintainer scripts; you must
4907 use the <prgn>update-rc.d</prgn> program instead. (The
4908 former will fail if an alternative method of maintaining
4909 runlevel information is being used.) You must not include
4910 the <file>/etc/rc<var>n</var>.d</file> directories themselves
4911 in the archive either. (Only the <tt>sysvinit</tt>
4916 By default <prgn>update-rc.d</prgn> will start services in
4917 each of the multi-user state runlevels (2, 3, 4, and 5)
4918 and stop them in the halt runlevel (0), the single-user
4919 runlevel (1) and the reboot runlevel (6). The system
4920 administrator will have the opportunity to customize
4921 runlevels by simply adding, moving, or removing the
4922 symbolic links in <file>/etc/rc<var>n</var>.d</file> if
4923 symbolic links are being used, or by modifying
4924 <file>/etc/runlevel.conf</file> if the <tt>file-rc</tt> method
4929 To get the default behavior for your package, put in your
4930 <prgn>postinst</prgn> script
4931 <example compact="compact">
4932 update-rc.d <var>package</var> defaults
4934 and in your <prgn>postrm</prgn>
4935 <example compact="compact">
4936 if [ "$1" = purge ]; then
4937 update-rc.d <var>package</var> remove
4939 </example>. Note that if your package changes runlevels
4940 or priority, you may have to remove and recreate the links,
4941 since otherwise the old links may persist. Refer to the
4942 documentation of <prgn>update-rc.d</prgn></p>
4945 This will use a default sequence number of 20. If it does
4946 not matter when or in which order the <file>init.d</file>
4947 script is run, use this default. If it does, then you
4948 should talk to the maintainer of the <prgn>sysvinit</prgn>
4949 package or post to <tt>debian-devel</tt>, and they will
4950 help you choose a number.
4954 For more information about using <tt>update-rc.d</tt>,
4955 please consult its manpage <manref name="update-rc.d"
4961 <heading>Running initscripts</heading>
4963 The program <prgn>invoke-rc.d</prgn> is provided to make
4964 it easier for package maintainers to properly invoke an
4965 initscript, obeying runlevel and other locally-defined
4966 constraints that might limit a package's right to start,
4967 stop and otherwise manage services. This program may be
4968 used by maintainers in their packages' scripts.
4971 The use of <prgn>invoke-rc.d</prgn> to invoke the
4972 <file>/etc/init.d/*</file> initscripts is strongly
4973 recommended<footnote>
4975 In the future, the use of invoke-rc.d to invoke
4976 initscripts shall be made mandatory. Maintainers are
4977 advised to switch to invoke-rc.d as soon as
4979 </footnote>, instead of calling them directly.
4983 By default, <prgn>invoke-rc.d</prgn> will pass any
4984 action requests (start, stop, reload, restart...) to the
4985 <file>/etc/init.d</file> script, filtering out requests
4986 to start or restart a service out of its intended
4990 Most packages will simply need to change:
4991 <example compact="compact">/etc/init.d/<package>
4992 <action></example> in their <prgn>postinst</prgn>
4993 and <prgn>prerm</prgn> scripts to:
4994 <example compact="compact">
4995 if [ -x /usr/sbin/invoke-rc.d ] ; then
4996 invoke-rc.d <var>package</var> <action>
4998 /etc/init.d/<var>package</var> <action>
5002 A package should register its initscript services using
5003 <prgn>update-rc.d</prgn> before it tries to invoke them
5004 using <prgn>invoke-rc.d</prgn>. Invocation of
5005 unregistered services may fail.
5008 For more information about using
5009 <prgn>invoke-rc.d</prgn>, please consult its manpage
5010 <manref name="invoke-rc.d" section="8">.
5017 <heading>Boot-time initialization</heading>
5020 There used to be another directory, <file>/etc/rc.boot</file>,
5021 which contained scripts which were run once per machine
5022 boot. This has been deprecated in favour of links from
5023 <file>/etc/rcS.d</file> to files in <file>/etc/init.d</file> as
5024 described in <ref id="/etc/init.d">. Packages must not
5025 place files in <file>/etc/rc.boot</file>.</p>
5028 <heading>Example</heading>
5031 The <prgn>bind</prgn> DNS (nameserver) package wants to
5032 make sure that the nameserver is running in multiuser
5033 runlevels, and is properly shut down with the system. It
5034 puts a script in <file>/etc/init.d</file>, naming the script
5035 appropriately <tt>bind</tt>. As you can see, the script
5036 interprets the argument <tt>reload</tt> to send the
5037 nameserver a <tt>HUP</tt> signal (causing it to reload its
5038 configuration); this way the system administrator can say
5039 <tt>/etc/init.d/bind reload</tt> to reload the name
5040 server. The script has one configurable value, which can
5041 be used to pass parameters to the named program at
5042 startup; this value is read from
5043 <file>/etc/default/bind</file> (see below).
5047 <example compact="compact">
5050 # Original version by Robert Leslie
5051 # <rob@mars.org>, edited by iwj and cs
5053 test -x /usr/sbin/named || exit 0
5055 # Source defaults file.
5057 if [ -f /etc/default/bind ]; then
5064 echo -n "Starting domain name service: named"
5065 start-stop-daemon --start --quiet --exec /usr/sbin/named \
5070 echo -n "Stopping domain name service: named"
5071 start-stop-daemon --stop --quiet \
5072 --pidfile /var/run/named.pid --exec /usr/sbin/named
5076 echo -n "Restarting domain name service: named"
5077 start-stop-daemon --stop --quiet \
5078 --pidfile /var/run/named.pid --exec /usr/sbin/named
5079 start-stop-daemon --start --verbose --exec /usr/sbin/named \
5083 force-reload|reload)
5084 echo -n "Reloading configuration of domain name service: named"
5085 start-stop-daemon --stop --signal 1 --quiet \
5086 --pidfile /var/run/named.pid --exec /usr/sbin/named
5090 echo "Usage: /etc/init.d/bind " \
5091 " {start|stop|restart|reload|force-reload}" >&2
5101 Complementing the above init script is a configuration
5102 file <file>/etc/default/bind</file>, which contains
5103 configurable parameters used by the script. This would be
5104 created by the <prgn>postinst</prgn> script if it was not
5105 already present, and removed on purge by the
5106 <prgn>postrm</prgn> script.
5107 <example compact="compact">
5108 # Specified parameters to pass to named. See named(8).
5109 # You may uncomment the following line, and edit to taste.
5115 Another example on which you can base your
5116 <file>/etc/init.d</file> scripts is found in
5117 <file>/etc/init.d/skeleton</file>.
5121 If this package is happy with the default setup from
5122 <prgn>update-rc.d</prgn>, namely an ordering number of 20
5123 and having named running in all runlevels, it can say in
5124 its <prgn>postinst</prgn>:
5125 <example compact="compact">
5126 update-rc.d bind defaults >/dev/null
5128 And in its <prgn>postrm</prgn>, to remove the links when the
5130 <example compact="compact">
5131 if [ "$1" = purge ]; then
5132 update-rc.d bind remove >/dev/null
5140 <heading>Console messages from <file>init.d</file> scripts</heading>
5143 This section describes the formats to be used for messages
5144 written to standard output by the <file>/etc/init.d</file>
5145 scripts. The intent is to improve the consistency of
5146 Debian's startup and shutdown look and feel. For this
5147 reason, please look very carefully at the details. We want
5148 the messages to have the same format in terms of wording,
5149 spaces, punctuation and case of letters.
5153 Here is a list of overall rules that you should use when you
5154 create output messages. They can be useful if you have a
5155 non-standard message that is not covered specifically in the
5163 Every message should fit in one line (fewer than 80
5164 characters), start with a capital letter and end with
5165 a period (<tt>.</tt>) and line feed (<tt>"\n"</tt>).
5171 If you want to express that the computer is working on
5172 something (that is, performing a specific task, not
5173 starting or stopping a program), we use an "ellipsis"
5174 (three dots: <tt>...</tt>). Note that we don't insert
5175 spaces before or after the dots. If the task has been
5176 completed we write <tt>done.</tt> and a line feed.
5182 Design your messages as if the computer is telling you
5183 what he is doing (let him be polite :-), but don't
5184 mention "him" directly. For example, if you think of
5186 <example compact="compact">
5187 I'm starting network daemons: nfsd mountd.
5190 <example compact="compact">
5191 Starting network daemons: nfsd mountd.
5199 There are standard message formats for the following
5200 situations. They should be used by the <tt>init.d</tt>
5207 <p>When daemons are started</p>
5210 If your script starts one or more daemons, the output
5211 should look like this (a single line, no leading
5213 <example compact="compact">
5214 Starting <var>description</var>: <var>daemon-1</var> ... <var>daemon-n</var>.
5216 The <var>description</var> should describe the
5217 subsystem the daemon or set of daemons are part of,
5218 while <var>daemon-1</var> up to <var>daemon-n</var>
5219 denote each daemon's name (typically the file name of
5224 For example, the output of <file>/etc/init.d/lpd</file>
5226 <example compact="compact">
5227 Starting printer spooler: lpd.
5232 This can be achieved by saying
5233 <example compact="compact">
5234 echo -n "Starting printer spooler: lpd"
5235 start-stop-daemon --start --quiet --exec /usr/sbin/lpd
5238 in the script. If you have more than one daemon to
5239 start, you should do the following:
5240 <example compact="compact">
5241 echo -n "Starting remote file system services:"
5242 echo -n " nfsd"; start-stop-daemon --start --quiet nfsd
5243 echo -n " mountd"; start-stop-daemon --start --quiet mountd
5244 echo -n " ugidd"; start-stop-daemon --start --quiet ugidd
5247 This makes it possible for the user to see what takes
5248 so long and when the final daemon has been started.
5249 You should be careful where to put spaces: in the
5250 example above the system administrator can easily
5251 comment out a line if he don't wants to start a
5252 specific daemon, while the displayed message still
5258 <p>When a system parameter is being set</p>
5261 If you have to set up different system parameters
5262 during the system boot, you should use this format:
5263 <example compact="compact">
5264 Setting <var>parameter</var> to "<var>value</var>".
5269 You can use a statement such as the following to get
5271 <example compact="compact">
5272 echo "Setting DNS domainname to \"$domainname\"."
5277 Note that the same symbol (<tt>"</tt>) is used for the left
5278 and right quotation marks. A grave accent (<tt>`</tt>) is
5279 not a quote character; neither is an apostrophe
5285 <p>When a daemon is stopped or restarted</p>
5288 When you stop or restart a daemon, you should issue a
5289 message identical to the startup message, except that
5290 <tt>Starting</tt> is replaced with <tt>Stopping</tt>
5291 or <tt>Restarting</tt> respectively.
5295 For example, stopping the printer daemon will like
5297 <example compact="compact">
5298 Stopping printer spooler: lpd.
5304 <p>When something is executed</p>
5307 There are several examples where you have to run a
5308 program at system startup or shutdown to perform a
5309 specific task, for example, setting the system's clock
5310 using <prgn>netdate</prgn> or killing all processes
5311 when the system shuts down. Your message should look
5313 <example compact="compact">
5314 Doing something very useful...done.
5316 You should print the <tt>done.</tt> immediately after
5317 the job has been completed, so that the user is
5318 informed why she has to wait. You can get this
5320 <example compact="compact">
5321 echo -n "Doing something very useful..."
5330 <p>When the configuration is reloaded</p>
5333 When a daemon is forced to reload its configuration
5334 files you should use the following format:
5335 <example compact="compact">
5336 Reloading <var>description</var> configuration...done.
5338 where <var>description</var> is the same as in the
5339 daemon starting message.
5347 <heading>Cron jobs</heading>
5350 Packages must not modify the configuration file
5351 <file>/etc/crontab</file>, and they must not modify the files in
5352 <file>/var/spool/cron/crontabs</file>.</p>
5355 If a package wants to install a job that has to be executed
5356 via cron, it should place a file with the name of the
5357 package in one or more of the following directories:
5358 <example compact="compact">
5363 As these directory names imply, the files within them are
5364 executed on a daily, weekly, or monthly basis,
5365 respectively. The exact times are listed in
5366 <file>/etc/crontab</file>.</p>
5369 All files installed in any of these directories must be
5370 scripts (e.g., shell scripts or Perl scripts) so that they
5371 can easily be modified by the local system administrator.
5372 In addition, they should be treated as configuration
5377 If a certain job has to be executed more frequently than
5378 daily, the package should install a file
5379 <file>/etc/cron.d/<var>package</var></file>. This file uses the
5380 same syntax as <file>/etc/crontab</file> and is processed by
5381 <prgn>cron</prgn> automatically. The file must also be
5382 treated as a configuration file. (Note that entries in the
5383 <file>/etc/cron.d</file> directory are not handled by
5384 <prgn>anacron</prgn>. Thus, you should only use this
5385 directory for jobs which may be skipped if the system is not
5389 The scripts or crontab entries in these directories should
5390 check if all necessary programs are installed before they
5391 try to execute them. Otherwise, problems will arise when a
5392 package was removed but not purged since configuration files
5393 are kept on the system in this situation.</p>
5397 <heading>Menus</heading>
5400 Menu entries should follow the current menu policy found in
5401 the <tt>menu-policy</tt> files in the <tt>debian-policy</tt>
5402 package. It may also be found on the Debian FTP site
5403 <ftpsite>ftp.debian.org</ftpsite> as the file
5404 <ftppath>/debian/doc/package-developer/menu-policy.txt.gz</ftppath>,
5405 or in the equivalent location on your local mirror.
5409 The Debian <tt>menu</tt> package provides a standard
5410 interface between packages providing applications and
5411 documents, and <em>menu programs</em> (either X window
5412 managers or text-based menu programs such as
5413 <prgn>pdmenu</prgn>).
5417 All packages that provide applications that need not be
5418 passed any special command line arguments for normal
5419 operation should register a menu entry for those
5420 applications, so that users of the <tt>menu</tt> package
5421 will automatically get menu entries in their window
5422 managers, as well in shells like <tt>pdmenu</tt>.</p>
5425 Please also refer to the <em>Debian Menu System</em>
5426 documentation that comes with the <tt>menu</tt> package for
5427 information about how to register your applications and web
5433 <heading>Multimedia handlers</heading>
5436 Packages which provide the ability to view/show/play,
5437 compose, edit or print MIME types should register themselves
5438 as such following the current MIME support policy found in
5439 the <tt>mime-policy</tt> files in the <tt>debian-policy</tt>
5440 package. It may also be found on the Debian FTP site
5441 <ftpsite>ftp.debian.org</ftpsite> as the file
5442 <ftppath>/debian/doc/package-developer/mime-policy.txt.gz</ftppath>,
5443 or in the equivalent location on your local mirror.
5447 MIME (Multipurpose Internet Mail Extensions, RFCs 2045-2049)
5448 is a mechanism for encoding files and data streams and
5449 providing meta-information about them, in particular their
5450 type (e.g. audio or video) and format (e.g. PNG, HTML,
5455 Registration of MIME type handlers allows programs like mail
5456 user agents and web browsers to to invoke these handlers to
5457 view, edit or display MIME types they don't support
5463 <heading>Keyboard configuration</heading>
5466 To achieve a consistent keyboard configuration so that all
5467 applications interpret a keyboard event the same way, all
5468 programs in the Debian distribution must be configured to
5469 comply with the following guidelines.
5473 The following keys must have the specified interpretations:
5476 <tag><tt><--</tt></tag>
5477 <item><p>delete the character to the left of the cursor</p></item>
5479 <tag><tt>Delete</tt></tag>
5480 <item><p>delete the character to the right of the cursor</p></item>
5482 <tag><tt>Control+H</tt></tag>
5483 <item><p>emacs: the help prefix</p></item>
5486 The interpretation of any keyboard events should be
5487 independent of the terminal that is used, be it a virtual
5488 console, an X terminal emulator, an rlogin/telnet session,
5493 The following list explains how the different programs
5494 should be set up to achieve this:
5499 <item><p><tt><--</tt> generates <tt>KB_BackSpace</tt>
5502 <item><p><tt>Delete</tt> generates <tt>KB_Delete</tt> in
5507 X translations are set up to make
5508 <tt>KB_Backspace</tt> generate ASCII DEL, and to make
5509 <tt>KB_Delete</tt> generate <tt>ESC [ 3 ~</tt> (this
5510 is the vt220 escape code for the "delete character"
5511 key). This must be done by loading the X resources
5512 using <prgn>xrdb</prgn> on all local X displays, not
5513 using the application defaults, so that the
5514 translation resources used correspond to the
5515 <prgn>xmodmap</prgn> settings.</p></item>
5519 The Linux console is configured to make
5520 <tt><--</tt> generate DEL, and <tt>Delete</tt>
5521 generate <tt>ESC [ 3 ~</tt>.</p></item>
5525 X applications are configured so that <tt><</tt>
5526 deletes left, and <tt>Delete</tt> deletes right. Motif
5527 applications already work like this.</p></item>
5529 <item><p>Terminals should have <tt>stty erase ^?</tt> .</p></item>
5533 The <tt>xterm</tt> terminfo entry should have <tt>ESC
5534 [ 3 ~</tt> for <tt>kdch1</tt>, just as for
5535 <tt>TERM=linux</tt> and <tt>TERM=vt220</tt>.</p></item>
5539 Emacs is programmed to map <tt>KB_Backspace</tt> or
5540 the <tt>stty erase</tt> character to
5541 <tt>delete-backward-char</tt>, and <tt>KB_Delete</tt>
5542 or <tt>kdch1</tt> to <tt>delete-forward-char</tt>, and
5543 <tt>^H</tt> to <tt>help</tt> as always.</p></item>
5547 Other applications use the <tt>stty erase</tt>
5548 character and <tt>kdch1</tt> for the two delete keys,
5549 with ASCII DEL being "delete previous character" and
5550 <tt>kdch1</tt> being "delete character under
5557 This will solve the problem except for the following
5565 Some terminals have a <tt><--</tt> key that cannot
5566 be made to produce anything except <tt>^H</tt>. On
5567 these terminals Emacs help will be unavailable on
5568 <tt>^H</tt> (assuming that the <tt>stty erase</tt>
5569 character takes precedence in Emacs, and has been set
5570 correctly). <tt>M-x help</tt> or <tt>F1</tt> (if
5571 available) can be used instead.</p></item>
5575 Some operating systems use <tt>^H</tt> for <tt>stty
5576 erase</tt>. However, modern telnet versions and all
5577 rlogin versions propagate <tt>stty</tt> settings, and
5578 almost all UNIX versions honour <tt>stty erase</tt>.
5579 Where the <tt>stty</tt> settings are not propagated
5580 correctly, things can be made to work by using
5581 <tt>stty</tt> manually.</p></item>
5585 Some systems (including previous Debian versions) use
5586 <prgn>xmodmap</prgn> to arrange for both
5587 <tt><--</tt> and <tt>Delete</tt> to generate
5588 <tt>KB_Delete</tt>. We can change the behavior of
5589 their X clients using the same X resources that we use
5590 to do it for our own clients, or configure our clients
5591 using their resources when things are the other way
5592 around. On displays configured like this
5593 <tt>Delete</tt> will not work, but <tt><--</tt>
5598 Some operating systems have different <tt>kdch1</tt>
5599 settings in their <tt>terminfo</tt> database for
5600 <tt>xterm</tt> and others. On these systems the
5601 <tt>Delete</tt> key will not work correctly when you
5602 log in from a system conforming to our policy, but
5603 <tt><--</tt> will.</p></item>
5609 <heading>Environment variables</heading>
5612 A program must not depend on environment variables to get
5613 reasonable defaults. (That's because these environment
5614 variables would have to be set in a system-wide
5615 configuration file like <file>/etc/profile</file>, which is not
5616 supported by all shells.)</p>
5619 If a program usually depends on environment variables for its
5620 configuration, the program should be changed to fall back to
5621 a reasonable default configuration if these environment
5622 variables are not present. If this cannot be done easily
5623 (e.g., if the source code of a non-free program is not
5624 available), the program must be replaced by a small
5625 "wrapper" shell script which sets the environment variables
5626 if they are not already defined, and calls the original program.</p>
5629 Here is an example of a wrapper script for this purpose:
5631 <example compact="compact">
5633 BAR=${BAR:-/var/lib/fubar}
5635 exec /usr/lib/foo/foo "$@"
5640 Furthermore, as <file>/etc/profile</file> is a configuration
5641 file of the <prgn>base-files</prgn> package, other packages must not
5642 put any environment variables or other commands into that
5648 <heading>Files</heading>
5651 <heading>Binaries</heading>
5654 Two different packages must not install programs with
5655 different functionality but with the same filenames. (The
5656 case of two programs having the same functionality but
5657 different implementations is handled via "alternatives" or
5658 the "Conflicts" mechanism. See <ref id="maintscripts"> and
5659 <ref id="conflicts"> respectively.) If this case happens,
5660 one of the programs must be renamed. The maintainers should
5661 report this to the <tt>debian-devel</tt> mailing list and
5662 try to find a consensus about which program will have to be
5663 renamed. If a consensus cannot be reached, <em>both</em>
5664 programs must be renamed.
5668 By default, when a package is being built, any binaries
5669 created should include debugging information, as well as
5670 being compiled with optimization. You should also turn on
5671 as many reasonable compilation warnings as possible; this
5672 makes life easier for porters, who can then look at build
5673 logs for possible problems. For the C programming language,
5674 this means the following compilation parameters should be
5676 <example compact="compact">
5678 CFLAGS = -O2 -g -Wall # sane warning options vary between programs
5680 install -s # (or use strip on the files in debian/tmp)
5685 Note that by default all installed binaries should be stripped,
5686 either by using the <tt>-s</tt> flag to
5687 <prgn>install</prgn>, or by calling <prgn>strip</prgn> on
5688 the binaries after they have been copied into
5689 <file>debian/tmp</file> but before the tree is made into a
5693 Although binaries in the build tree should be compiled with
5694 debugging information by default, it can often be difficult
5695 to debug programs if they are also subjected to compiler
5696 optimization. For this reason, it is recommended to support
5697 the standardized environment
5698 variable <tt>DEB_BUILD_OPTIONS</tt>. This variable can
5699 contain several flags to change how a package is compiled
5707 The presence of this string means that the package
5708 should be complied with a minimum of optimization.
5709 For C programs, it is best to add <tt>-O0</tt>
5710 to <tt>CFLAGS</tt> (although this is usually the
5711 default). Some programs might fail to build or run at
5712 this level of optimization; it may be necessary to
5713 use <tt>-O1</tt>, for example.
5719 This string means that the debugging symbols should
5720 not be stripped from the binary during installation,
5721 so that debugging information may be included in the package.
5727 The following makefile snippet is an example of how one may
5728 implement the build options; you will probably have to
5729 massage this example in order to make it work for your
5731 <example compact="compact">
5734 INSTALL_FILE = $(INSTALL) -p -o root -g root -m 644
5735 INSTALL_PROGRAM = $(INSTALL) -p -o root -g root -m 755
5736 INSTALL_SCRIPT = $(INSTALL) -p -o root -g root -m 755
5737 INSTALL_DIR = $(INSTALL) -p -d -o root -g root -m 755
5739 ifneq (,$(findstring noopt,$(DEB_BUILD_OPTIONS)))
5744 ifeq (,$(findstring nostrip,$(DEB_BUILD_OPTIONS)))
5745 INSTALL_PROGRAM += -s
5751 It is up to the package maintainer to decide what
5752 compilation options are best for the package. Certain
5753 binaries (such as computationally-intensive programs) will
5754 function better with certain flags (<tt>-O3</tt>, for
5755 example); feel free to use them. Please use good judgment
5756 here. Don't use flags for the sake of it; only use them
5757 if there is good reason to do so. Feel free to override
5758 the upstream author's ideas about which compilation
5759 options are best: they are often inappropriate for our
5765 <sect id="libraries">
5766 <heading>Libraries</heading>
5769 The shared version of a library must be compiled with
5770 <tt>-fPIC</tt>, and the static version must not be. In other
5771 words, each source unit (<tt>*.c</tt>, for example, for C files)
5772 will need to be compiled twice.
5777 You must specify the gcc option <tt>-D_REENTRANT</tt>
5778 when building a library (either static or shared) to make
5779 the library compatible with LinuxThreads.
5783 All installed shared libraries should be stripped with
5784 <example compact="compact">
5785 strip --strip-unneeded <var>your-lib</var>
5787 (The option <tt>--strip-unneeded</tt> makes
5788 <prgn>strip</prgn> remove only the symbols which aren't
5789 needed for relocation processing.) Shared libraries can
5790 function perfectly well when stripped, since the symbols for
5791 dynamic linking are in a separate part of the ELF object
5794 You might also want to use the options
5795 <tt>--remove-section=.comment</tt> and
5796 <tt>--remove-section=.note</tt> on both shared libraries
5797 and executables, and <tt>--strip-debug</tt> on static
5804 Note that under some circumstances it may be useful to
5805 install a shared library unstripped, for example when
5806 building a separate package to support debugging.
5810 Shared object files (often <file>.so</file> files) that are not
5811 public libraries, that is, they are not meant to be linked
5812 to by third party executables (binaries of other packages),
5813 should be installed in subdirectories of the
5814 <file>/usr/lib</file> directory. Such files are exempt from the
5815 rules that govern ordinary shared libraries, except that
5816 they must not be installed executable and should be
5819 A common example are the so-called "plug-ins",
5820 internal shared objects that are dynamically loaded by
5821 programs using <manref name="dlopen" section="3">.
5827 Packages containing shared libraries that may be linked to
5828 by other packages' binaries, but which for some
5829 <em>compelling</em> reason can not be installed in
5830 <file>/usr/lib</file> directory, may install the shared library
5831 files in subdirectories of the <file>/usr/lib</file> directory,
5832 in which case they should arrange to add that directory in
5833 <file>/etc/ld.so.conf</file> in the package's post-installation
5834 script, and remove it in the package's post-removal script.
5838 An ever increasing number of packages are using
5839 <prgn>libtool</prgn> to do their linking. The latest GNU
5840 libtools (>= 1.3a) can take advantage of the metadata in the
5841 installed <prgn>libtool</prgn> archive files (<file>*.la</file>
5842 files). The main advantage of <prgn>libtool</prgn>'s
5843 <file>.la</file> files is that it allows <prgn>libtool</prgn> to
5844 store and subsequently access metadata with respect to the
5845 libraries it builds. <prgn>libtool</prgn> will search for
5846 those files, which contain a lot of useful information about
5847 a library (such as library dependency information for static
5848 linking). Also, they're <em>essential</em> for programs
5849 using <tt>libltdl</tt>.<footnote>
5851 Although <prgn>libtool</prgn> is fully capable of
5852 linking against shared libraries which don't have
5853 <tt>.la</tt> files, as it is a mere shell script it can
5854 add considerably to the build time of a
5855 <prgn>libtool</prgn>-using package if that shell script
5856 has to derive all this information from first principles
5857 for each library every time it is linked. With the
5858 advent of <prgn>libtool</prgn> version 1.4 (and to a
5859 lesser extent <prgn>libtool</prgn> version 1.3), the
5860 <file>.la</file> files also store information about
5861 inter-library dependencies which cannot necessarily be
5862 derived after the <file>.la</file> file is deleted.
5868 Packages that use <prgn>libtool</prgn> to create shared
5869 libraries should include the <file>.la</file> files in the
5870 <tt>-dev</tt> package, unless the package relies on
5871 <tt>libtool</tt>'s <tt>libltdl</tt> library, in which case
5872 the <tt>.la</tt> files must go in the run-time library
5877 You must make sure that you use only released versions of
5878 shared libraries to build your packages; otherwise other
5879 users will not be able to run your binaries
5880 properly. Producing source packages that depend on
5881 unreleased compilers is also usually a bad
5888 <heading>Shared libraries</heading>
5890 This section has moved to <ref id="sharedlibs">.
5896 <heading>Scripts</heading>
5899 All command scripts, including the package maintainer
5900 scripts inside the package and used by <prgn>dpkg</prgn>,
5901 should have a <tt>#!</tt> line naming the shell to be used
5902 to interpret them.</p>
5905 In the case of Perl scripts this should be
5906 <tt>#!/usr/bin/perl</tt>.</p>
5909 Shell scripts (<prgn>sh</prgn> and <prgn>bash</prgn>)
5910 should almost certainly start with <tt>set -e</tt> so that
5911 errors are detected. Every script should use
5912 <tt>set -e</tt> or check the exit status of <em>every</em>
5916 The standard shell interpreter <file>/bin/sh</file> can be a
5917 symbolic link to any POSIX compatible shell, if <tt>echo
5918 -n</tt> does not generate a newline.<footnote>
5920 Debian policy specifies POSIX behavior for
5921 <file>/bin/sh</file>, but <tt>echo -n</tt> has widespread
5922 use in the Linux community (in particular including this
5923 policy, the Linux kernel source, many Debian scripts,
5924 etc.). This <tt>echo -n</tt> mechanism is valid but not
5925 required under POSIX, hence this explicit addition.
5926 Also, rumour has it that this shall be mandated under
5930 Thus, shell scripts specifying <file>/bin/sh</file> as
5931 interpreter should only use POSIX features. If a script
5932 requires non-POSIX features from the shell interpreter, the
5933 appropriate shell must be specified in the first line of the
5934 script (e.g., <tt>#!/bin/bash</tt>) and the package must
5935 depend on the package providing the shell (unless the shell
5936 package is marked "Essential", as in the case of
5941 You may wish to restrict your script to POSIX features when
5942 possible so that it may use <file>/bin/sh</file> as its
5943 interpreter. If your script works with <prgn>dash</prgn>
5944 (originally called <prgn>ash</prgn>), it's probably POSIX
5945 compliant, but if you are in doubt, use
5946 <file>/bin/bash</file>.
5950 Perl scripts should check for errors when making any
5951 system calls, including <tt>open</tt>, <tt>print</tt>,
5952 <tt>close</tt>, <tt>rename</tt> and <tt>system</tt>.
5956 <prgn>csh</prgn> and <prgn>tcsh</prgn> should be avoided as
5957 scripting languages. See <em>Csh Programming Considered
5958 Harmful</em>, one of the <tt>comp.unix.*</tt> FAQs, which
5959 can be found at <url
5960 id="http://language.perl.com/versus/csh.whynot">.<footnote>
5962 It can also be found on
5963 <url id="http://www.cpan.org/doc/FMTEYEWTK/versus/csh.whynot">
5964 or on the ftp site <ftpsite>ftp.cpan.org</ftpsite> as
5965 <ftppath>/pub/perl/CPAN/doc/FMTEYEWTK/versus/csh.whynot</ftppath>.
5968 If an upstream package comes with <prgn>csh</prgn> scripts
5969 then you must make sure that they start with
5970 <tt>#!/bin/csh</tt> and make your package depend on the
5971 <prgn>c-shell</prgn> virtual package.
5975 Any scripts which create files in world-writeable
5976 directories (e.g., in <file>/tmp</file>) must use a
5977 mechanism which will fail if a file with the same name
5981 The Debian base system provides the <prgn>tempfile</prgn>
5982 and <prgn>mktemp</prgn> utilities for use by scripts for
5983 this purpose.</p></sect>
5987 <heading>Symbolic links</heading>
5990 In general, symbolic links within a top-level directory
5991 should be relative, and symbolic links pointing from one
5992 top-level directory into another should be absolute. (A
5993 top-level directory is a sub-directory of the root
5994 directory <file>/</file>.)</p>
5997 In addition, symbolic links should be specified as short as
5998 possible, i.e., link targets like <file>foo/../bar</file> are
6002 Note that when creating a relative link using
6003 <prgn>ln</prgn> it is not necessary for the target of the
6004 link to exist relative to the working directory you're
6005 running <prgn>ln</prgn> from, nor is it necessary to change
6006 directory to the directory where the link is to be made.
6007 Simply include the string that should appear as the target
6008 of the link (this will be a pathname relative to the
6009 directory in which the link resides) as the first argument
6010 to <prgn>ln</prgn>.</p>
6013 For example, in your <prgn>Makefile</prgn> or
6014 <file>debian/rules</file>, you can do things like:
6015 <example compact="compact">
6016 ln -fs gcc $(prefix)/bin/cc
6017 ln -fs gcc debian/tmp/usr/bin/cc
6018 ln -fs ../sbin/sendmail $(prefix)/bin/runq
6019 ln -fs ../sbin/sendmail debian/tmp/usr/bin/runq
6023 A symbolic link pointing to a compressed file should always
6024 have the same file extension as the referenced file. (For
6025 example, if a file <file>foo.gz</file> is referenced by a
6026 symbolic link, the filename of the link has to end with
6027 "<file>.gz</file>" too, as in <file>bar.gz</file>.)
6032 <heading>Device files</heading>
6035 Packages must not include device files in the package file
6039 If a package needs any special device files that are not
6040 included in the base system, it must call
6041 <prgn>MAKEDEV</prgn> in the <prgn>postinst</prgn> script,
6042 after notifying the user<footnote>
6044 This notification could be done via a (low-priority)
6045 debconf message, or an echo (printf) statement.
6051 Packages must not remove any device files in the
6052 <prgn>postrm</prgn> or any other script. This is left to the
6053 system administrator.</p>
6056 Debian uses the serial devices
6057 <file>/dev/ttyS*</file>. Programs using the old
6058 <file>/dev/cu*</file> devices should be changed to use
6059 <file>/dev/ttyS*</file>.</p>
6062 <sect id="config-files">
6063 <heading>Configuration files</heading>
6065 <heading>Definitions</heading>
6068 <tag>configuration file</tag>
6071 A file that affects the operation of a program, or
6072 provides site- or host-specific information, or
6073 otherwise customizes the behavior of a program.
6074 Typically, configuration files are intended to be
6075 modified by the system administrator (if needed or
6076 desired) to conform to local policy or to provide
6077 more useful site-specific behavior.
6081 <tag><tt>conffile</tt></tag>
6084 A file listed in a package's <tt>conffiles</tt>
6085 file, and is treated specially by <prgn>dpkg</prgn>
6086 (see <ref id="configdetails">).
6093 The distinction between these two is important; they are
6094 not interchangeable concepts. Almost all
6095 <tt>conffile</tt>s are configuration files, but many
6096 configuration files are not <tt>conffiles</tt>.
6100 Note that a script that embeds configuration information
6101 (such as most of the files in <file>/etc/default</file> and
6102 <file>/etc/cron.{daily,weekly,monthly}</file>) is de-facto a
6103 configuration file and should be treated as such.
6108 <heading>Location</heading>
6110 Any configuration files created or used by your package
6111 must reside in <file>/etc</file>. If there are several,
6112 consider creating a subdirectory of <file>/etc</file>
6113 named after your package.</p>
6116 If your package creates or uses configuration files
6117 outside of <file>/etc</file>, and it is not feasible to modify
6118 the package to use <file>/etc</file> directly, put the files
6119 in <file>/etc</file> and create symbolic links to those files
6120 from the location that the package requires.</p>
6124 <heading>Behavior</heading>
6126 Configuration file handling must conform to the following
6128 <list compact="compact">
6131 local changes must be preserved during a package
6137 configuration files must be preserved when the
6138 package is removed, and only deleted when the
6146 The easy way to achieve this behavior is to make the
6147 configuration file a <tt>conffile</tt>. This is
6148 appropriate only if it is possible to distribute a default
6149 version that will work for most installations, although
6150 some system administrators may choose to modify it. This
6151 implies that the default version will be part of the
6152 package distribution, and must not be modified by the
6153 maintainer scripts during installation (or at any other
6158 In order to ensure that local changes are preserved
6159 correctly, no package may contain or make hard links to
6160 conffiles.<footnote>
6162 Rationale: There are two problems with hard links.
6163 The first is that some editors break the link while
6164 editing one of the files, so that the two files may
6165 unwittingly become unlinked and different. The second
6166 is that <prgn>dpkg</prgn> might break the hard link
6167 while upgrading <tt>conffile</tt>s.
6173 The other way to do it is via the maintainer scripts. In
6174 this case, the configuration file must not be listed as a
6175 <tt>conffile</tt> and must not be part of the package
6176 distribution. If the existence of a file is required for
6177 the package to be sensibly configured it is the
6178 responsibility of the package maintainer to provide
6179 maintainer scripts which correctly create, update and
6180 maintain the file and remove it on purge. (See <ref
6181 id="maintainerscripts"> for more information.) These
6182 scripts must be idempotent (i.e., must work correctly if
6183 <prgn>dpkg</prgn> needs to re-run them due to errors
6184 during installation or removal), must cope with all the
6185 variety of ways <prgn>dpkg</prgn> can call maintainer
6186 scripts, must not overwrite or otherwise mangle the user's
6187 configuration without asking, must not ask unnecessary
6188 questions (particularly during upgrades), and otherwise be
6193 The scripts are not required to configure every possible
6194 option for the package, but only those necessary to get
6195 the package running on a given system. Ideally the
6196 sysadmin should not have to do any configuration other
6197 than that done (semi-)automatically by the
6198 <prgn>postinst</prgn> script.
6202 A common practice is to create a script called
6203 <file><var>package</var>-configure</file> and have the
6204 package's <prgn>postinst</prgn> call it if and only if the
6205 configuration file does not already exist. In certain
6206 cases it is useful for there to be an example or template
6207 file which the maintainer scripts use. Such files should
6208 be in <file>/usr/share/<var>package</var></file> or
6209 <file>/usr/lib/<var>package</var></file> (depending on whether
6210 they are architecture-independent or not). There should
6211 be symbolic links to them from
6212 <file>/usr/share/doc/<var>package</var>/examples</file> if
6213 they are examples, and should be perfectly ordinary
6214 <prgn>dpkg</prgn>-handled files (<em>not</em>
6215 configuration files).
6219 These two styles of configuration file handling must
6220 not be mixed, for that way lies madness:
6221 <prgn>dpkg</prgn> will ask about overwriting the file
6222 every time the package is upgraded.
6227 <heading>Sharing configuration files</heading>
6229 Packages which specify the same file as a
6230 <tt>conffile</tt> must be tagged as <em>conflicting</em>
6231 with each other. (This is an instance of the general rule
6232 about not sharing files. Note that neither alternatives
6233 nor diversions are likely to be appropriate in this case;
6234 in particular, <prgn>dpkg</prgn> does not handle diverted
6235 <tt>conffile</tt>s well.)
6239 The maintainer scripts must not alter a <tt>conffile</tt>
6240 of <em>any</em> package, including the one the scripts
6245 If two or more packages use the same configuration file
6246 and it is reasonable for both to be installed at the same
6247 time, one of these packages must be defined as
6248 <em>owner</em> of the configuration file, i.e., it will be
6249 the package which handles that file as a configuration
6250 file. Other packages that use the configuration file must
6251 depend on the owning package if they require the
6252 configuration file to operate. If the other package will
6253 use the configuration file if present, but is capable of
6254 operating without it, no dependency need be declared.</p>
6257 If it is desirable for two or more related packages to
6258 share a configuration file <em>and</em> for all of the
6259 related packages to be able to modify that configuration
6260 file, then the following should be done:
6261 <enumlist compact="compact">
6264 One of the related packages (the "owning" package)
6265 will manage the configuration file with maintainer
6266 scripts as described in the previous section.
6271 The owning package should also provide a program
6272 that the other packages may use to modify the
6278 The related packages must use the provided program
6279 to make any desired modifications to the
6280 configuration file. They should either depend on
6281 the core package to guarantee that the configuration
6282 modifier program is available or accept gracefully
6283 that they cannot modify the configuration file if it
6284 is not. (This is in addition to the fact that the
6285 configuration file may not even be present in the
6293 Sometimes it's appropriate to create a new package which
6294 provides the basic infrastructure for the other packages
6295 and which manages the shared configuration files. (The
6296 <tt>sgml-base</tt> package is a good example.)
6301 <heading>User configuration files ("dotfiles")</heading>
6304 The files in <file>/etc/skel</file> will automatically be
6305 copied into new user accounts by <prgn>adduser</prgn>.
6306 No other program should reference the files in
6307 <file>/etc/skel</file>.
6311 Therefore, if a program needs a dotfile to exist in
6312 advance in <file>$HOME</file> to work sensibly, that dotfile
6313 should be installed in <file>/etc/skel</file> and treated as a
6318 However, programs that require dotfiles in order to
6319 operate sensibly are a bad thing, unless they do create
6320 the dotfiles themselves automatically.
6324 Furthermore, programs should be configured by the Debian
6325 default installation to behave as closely to the upstream
6326 default behaviour as possible.
6330 Therefore, if a program in a Debian package needs to be
6331 configured in some way in order to operate sensibly, that
6332 should be done using a site-wide configuration file placed
6333 in <file>/etc</file>. Only if the program doesn't support a
6334 site-wide default configuration and the package maintainer
6335 doesn't have time to add it may a default per-user file be
6336 placed in <file>/etc/skel</file>.
6340 <file>/etc/skel</file> should be as empty as we can make it.
6341 This is particularly true because there is no easy (or
6342 necessarily desirable) mechanism for ensuring that the
6343 appropriate dotfiles are copied into the accounts of
6344 existing users when a package is installed.
6350 <heading>Log files</heading>
6352 Log files should usually be named
6353 <file>/var/log/<var>package</var>.log</file>. If you have many
6354 log files, or need a separate directory for permission
6355 reasons (<file>/var/log</file> is writable only by
6356 <file>root</file>), you should usually create a directory named
6357 <file>/var/log/<var>package</var></file> and place your log
6362 Log files must be rotated occasionally so that they don't
6363 grow indefinitely; the best way to do this is to drop a log
6364 rotation configuration file into the directory
6365 <file>/etc/logrotate.d</file> and use the facilities provided by
6366 logrotate.<footnote>
6368 The traditional approach to log files has been to set up
6369 <em>ad hoc</em> log rotation schemes using simple shell
6370 scripts and cron. While this approach is highly
6371 customizable, it requires quite a lot of sysadmin work.
6372 Even though the original Debian system helped a little
6373 by automatically installing a system which can be used
6374 as a template, this was deemed not enough.
6378 The use of <prgn>logrotate</prgn>, a program developed
6379 by Red Hat, is better, as it centralizes log management.
6380 It has both a configuration file
6381 (<file>/etc/logrotate.conf</file>) and a directory where
6382 packages can drop their individual log rotation
6383 configurations (<file>/etc/logrotate.d</file>).
6386 Here is a good example for a logrotate config
6387 file (for more information see <manref name="logrotate"
6389 <example compact="compact">
6395 /etc/init.d/foo force-reload
6399 This rotates all files under <file>/var/log/foo</file>, saves 12
6400 compressed generations, and forces the daemon to reload its
6401 configuration information after the log rotation.
6405 Log files should be removed when the package is
6406 purged (but not when it is only removed). This should be
6407 done by the <prgn>postrm</prgn> script when it is called
6408 with the argument <tt>purge</tt> (see <ref
6409 id="removedetails">).
6414 <heading>Permissions and owners</heading>
6417 The rules in this section are guidelines for general use.
6418 If necessary you may deviate from the details below.
6419 However, if you do so you must make sure that what is done
6420 is secure and you should try to be as consistent as possible
6421 with the rest of the system. You should probably also
6422 discuss it on <prgn>debian-devel</prgn> first.
6426 Files should be owned by <tt>root.root</tt>, and made
6427 writable only by the owner and universally readable (and
6428 executable, if appropriate), that is mode 644 or 755.
6432 Directories should be mode 755 or (for group-writability)
6433 mode 2775. The ownership of the directory should be
6434 consistent with its mode: if a directory is mode 2775, it
6435 should be owned by the group that needs write access to
6440 Setuid and setgid executables should be mode 4755 or 2755
6441 respectively, and owned by the appropriate user or group.
6442 They should not be made unreadable (modes like 4711 or
6443 2711 or even 4111); doing so achieves no extra security,
6444 because anyone can find the binary in the freely available
6445 Debian package; it is merely inconvenient. For the same
6446 reason you should not restrict read or execute permissions
6447 on non-set-id executables.
6451 Some setuid programs need to be restricted to particular
6452 sets of users, using file permissions. In this case they
6453 should be owned by the uid to which they are set-id, and by
6454 the group which should be allowed to execute them. They
6455 should have mode 4754; again there is no point in making
6456 them unreadable to those users who must not be allowed to
6461 It is possible to arrange that the system administrator can
6462 reconfigure the package to correspond to their local
6463 security policy by changing the permissions on a binary:
6464 they can do this by using <prgn>dpkg-statoverride</prgn>, as
6465 described below.<footnote>
6467 Ordinary files installed by <prgn>dpkg</prgn> (as
6468 opposed to <tt>conffile</tt>s and other similar objects)
6469 normally have their permissions reset to the distributed
6470 permissions when the package is reinstalled. However,
6471 the use of <prgn>dpkg-statoverride</prgn> overrides this
6472 default behaviour. If you use this method, you should
6473 remember to describe <prgn>dpkg-statoverride</prgn> in
6474 the package documentation; being a relatively new
6475 addition to Debian, it is probably not yet well-known.
6478 Another method you should consider is to create a group for
6479 people allowed to use the program(s) and make any setuid
6480 executables executable only by that group.
6484 If you need to create a new user or group for your package
6485 there are two possibilities. Firstly, you may need to
6486 make some files in the binary package be owned by this
6487 user or group, or you may need to compile the user or
6488 group id (rather than just the name) into the binary
6489 (though this latter should be avoided if possible, as in
6490 this case you need a statically allocated id).</p>
6493 If you need a statically allocated id, you must ask for a
6494 user or group id from the <tt>base-passwd</tt> maintainer,
6495 and must not release the package until you have been
6496 allocated one. Once you have been allocated one you must
6497 either make the package depend on a version of the
6498 <tt>base-passwd</tt> package with the id present in
6499 <file>/etc/passwd</file> or <file>/etc/group</file>, or arrange for
6500 your package to create the user or group itself with the
6501 correct id (using <tt>adduser</tt>) in its
6502 <prgn>preinst</prgn> or <prgn>postinst</prgn>. (Doing it in
6503 the <prgn>postinst</prgn> is to be preferred if it is
6504 possible, otherwise a pre-dependency will be needed on the
6505 <tt>adduser</tt> package.)
6509 On the other hand, the program might be able to determine
6510 the uid or gid from the user or group name at runtime, so
6511 that a dynamically allocated id can be used. In this case
6512 you should choose an appropriate user or group name,
6513 discussing this on <prgn>debian-devel</prgn> and checking
6514 with the <package/base-passwd/ maintainer that it is unique and that
6515 they do not wish you to use a statically allocated id
6516 instead. When this has been checked you must arrange for
6517 your package to create the user or group if necessary using
6518 <prgn>adduser</prgn> in the <prgn>preinst</prgn> or
6519 <prgn>postinst</prgn> script (again, the latter is to be
6520 preferred if it is possible).
6524 Note that changing the numeric value of an id associated
6525 with a name is very difficult, and involves searching the
6526 file system for all appropriate files. You need to think
6527 carefully whether a static or dynamic id is required, since
6528 changing your mind later will cause problems.
6531 <sect1><heading>The use of <prgn>dpkg-statoverride</prgn></heading>
6533 This section is not intended as policy, but as a
6534 description of the use of <prgn>dpkg-statoverride</prgn>.
6538 <prgn>dpkg-statoverride</prgn> is a replacement for the
6539 deprecated <tt>suidmanager</tt> package. Packages which
6540 previously used <tt>suidmanager</tt> should have a
6541 <tt>Conflicts: suidmanager (<< 0.50)</tt> entry (or even
6542 <tt>(<< 0.52)</tt>), and calls to <tt>suidregister</tt>
6543 and <tt>suidunregister</tt> should now be simply removed
6544 from the maintainer scripts.
6548 If a system administrator wishes to have a file (or
6549 directory or other such thing) installed with owner and
6550 permissions different from those in the distributed Debian
6551 package, he can use the <prgn>dpkg-statoverride</prgn>
6552 program to instruct <prgn>dpkg</prgn> to use the different
6553 settings every time the file is installed. Thus the
6554 package maintainer should distribute the files with their
6555 normal permissions, and leave it for the system
6556 administrator to make any desired changes. For example, a
6557 daemon which is normally required to be setuid root, but
6558 in certain situations could be used without being setuid,
6559 should be installed setuid in the <tt>.deb</tt>. Then the
6560 local system administrator can change this if they wish.
6561 If there are two standard ways of doing it, the package
6562 maintainer can use <tt>debconf</tt> to find out the
6563 preference, and call <prgn>dpkg-statoverride</prgn> in the
6564 maintainer script if necessary to accommodate the system
6565 administrator's choice.
6569 Given the above, <prgn>dpkg-statoverride</prgn> is
6570 essentially a tool for system administrators and would not
6571 normally be needed in the maintainer scripts. There is
6572 one type of situation, though, where calls to
6573 <prgn>dpkg-statoverride</prgn> would be needed in the
6574 maintainer scripts, and that involves packages which use
6575 dynamically allocated user or group ids. In such a
6576 situation, something like the following idiom can be very
6577 helpful in the package's <prgn>postinst</prgn>, where
6578 <tt>sysuser</tt> is a dynamically allocated id:
6580 for i in /usr/bin/foo /usr/sbin/bar
6582 if ! dpkg-statoverride --list $i >/dev/null
6584 dpkg-statoverride --update --add sysuser root 4755 $i
6588 The corresponding <tt>dpkg-statoverride --remove</tt>
6589 calls can then be made unconditionally when the package is
6596 <chapt id="customized-programs">
6597 <heading>Customized programs</heading>
6599 <sect id="arch-spec">
6600 <heading>Architecture specification strings</heading>
6603 If a program needs to specify an <em>architecture specification
6604 string</em> in some place, the following format should be
6605 used: <var>arch</var>-<var>os</var><footnote>
6607 The following architectures and operating systems are
6608 currently recognised by <prgn>dpkg-archictecture</prgn>.
6609 The architecture, <tt><var>arch</var></tt>, is one of
6610 the following: <tt>alpha</tt>, <tt>arm</tt>,
6611 <tt>hppa</tt>, <tt>i386</tt>, <tt>ia64</tt>,
6612 <tt>m68k</tt>, <tt>mips</tt>, <tt>mipsel</tt>,
6613 <tt>powerpc</tt>, <tt>s390</tt>, <tt>sh</tt>,
6614 <tt>sheb</tt>, <tt>sparc</tt> and <tt>sparc64</tt>. The
6615 operating system, <tt><var>os</var></tt>, is one of:
6616 <tt>linux</tt>, <tt>gnu</tt>, <tt>freebsd</tt> and
6617 <tt>openbsd</tt>. Use of <tt>gnu</tt> in this string is
6618 reserved for the GNU/Hurd operating system.
6624 Note that we don't want to use
6625 <tt><var>arch</var>-debian-linux</tt> to apply to the rule
6626 <tt><var>architecture</var>-<var>vendor</var>-<var>os</var></tt>
6627 since this would make our programs incompatible with other
6628 Linux distributions. We also don't use something like
6629 <tt><var>arch</var>-unknown-linux</tt>, since the
6630 <tt>unknown</tt> does not look very good.
6635 <heading>Daemons</heading>
6638 The configuration files <file>/etc/services</file>,
6639 <file>/etc/protocols</file>, and <file>/etc/rpc</file> are managed
6640 by the <prgn>netbase</prgn> package and must not be modified
6645 If a package requires a new entry in one of these files, the
6646 maintainer should get in contact with the
6647 <prgn>netbase</prgn> maintainer, who will add the entries
6648 and release a new version of the <prgn>netbase</prgn>
6653 The configuration file <file>/etc/inetd.conf</file> must not be
6654 modified by the package's scripts except via the
6655 <prgn>update-inetd</prgn> script or the
6656 <file>DebianNet.pm</file> Perl module. See their documentation
6657 for details on how to add entries.
6661 If a package wants to install an example entry into
6662 <file>/etc/inetd.conf</file>, the entry must be preceded with
6663 exactly one hash character (<tt>#</tt>). Such lines are
6664 treated as "commented out by user" by the
6665 <prgn>update-inetd</prgn> script and are not changed or
6666 activated during package updates.
6671 <heading>Using pseudo-ttys and modifying wtmp, utmp and
6675 Some programs need to create pseudo-ttys. This should be done
6676 using Unix98 ptys if the C library supports it. The resulting
6677 program must not be installed setuid root, unless that
6678 is required for other functionality.
6682 The files <file>/var/run/utmp</file>, <file>/var/log/wtmp</file> and
6683 <file>/var/log/lastlog</file> must be installed writeable by
6684 group <tt>utmp</tt>. Programs which need to modify those
6685 files must be installed setgid <tt>utmp</tt>.
6690 <heading>Editors and pagers</heading>
6693 Some programs have the ability to launch an editor or pager
6694 program to edit or display a text document. Since there are
6695 lots of different editors and pagers available in the Debian
6696 distribution, the system administrator and each user should
6697 have the possibility to choose his/her preferred editor and
6702 In addition, every program should choose a good default
6703 editor/pager if none is selected by the user or system
6708 Thus, every program that launches an editor or pager must
6709 use the EDITOR or PAGER environment variable to determine
6710 the editor or pager the user wishes to use. If these
6711 variables are not set, the programs <file>/usr/bin/editor</file>
6712 and <file>/usr/bin/pager</file> should be used, respectively.
6716 These two files are managed through the <prgn>dpkg</prgn>
6717 "alternatives" mechanism. Thus every package providing an
6718 editor or pager must call the
6719 <prgn>update-alternatives</prgn> script to register these
6724 If it is very hard to adapt a program to make use of the
6725 EDITOR or PAGER variables, that program may be configured to
6726 use <file>/usr/bin/sensible-editor</file> and
6727 <file>/usr/bin/sensible-pager</file> as the editor or pager
6728 program respectively. These are two scripts provided in the
6729 Debian base system that check the EDITOR and PAGER variables
6730 and launch the appropriate program, and fall back to
6731 <file>/usr/bin/editor</file> and <file>/usr/bin/pager</file> if the
6732 variable is not set.
6736 A program may also use the VISUAL environment variable to
6737 determine the user's choice of editor. If it exists, it
6738 should take precedence over EDITOR. This is in fact what
6739 <file>/usr/bin/sensible-editor</file> does.
6743 It is not required for a package to depend on
6744 <tt>editor</tt> and <tt>pager</tt>, nor is it required for a
6745 package to provide such virtual packages.<footnote>
6747 The Debian base system already provides an editor and a
6754 <sect id="web-appl">
6755 <heading>Web servers and applications</heading>
6758 This section describes the locations and URLs that should
6759 be used by all web servers and web applications in the
6767 Cgi-bin executable files are installed in the
6769 <example compact="compact">
6770 /usr/lib/cgi-bin/<var>cgi-bin-name</var>
6772 and should be referred to as
6773 <example compact="compact">
6774 http://localhost/cgi-bin/<var>cgi-bin-name</var>
6779 <item><p>Access to HTML documents</p>
6782 HTML documents for a package are stored in
6783 <file>/usr/share/doc/<var>package</var></file>
6784 and can be referred to as
6785 <example compact="compact">
6786 http://localhost/doc/<var>package</var>/<var>filename</var>
6790 The web server should restrict access to the document
6791 tree so that only clients on the same host can read
6792 the documents. If the web server does not support such
6793 access controls, then it should not provide access at
6794 all, or ask about providing access during installation.
6798 <item><p>Web Document Root</p>
6801 Web Applications should try to avoid storing files in
6802 the Web Document Root. Instead they should use the
6803 /usr/share/doc/<var>package</var> directory for
6804 documents and register the Web Application via the
6805 menu package. If access to the web document root is
6806 unavoidable then use
6807 <example compact="compact">
6810 as the Document Root. This might be just a symbolic
6811 link to the location where the system administrator
6812 has put the real document root.
6816 </enumlist></p></sect>
6819 <sect id="mail-transport-agents">
6820 <heading>Mail transport, delivery and user agents</heading>
6823 Debian packages which process electronic mail, whether mail
6824 user agents (MUAs) or mail transport agents (MTAs), must
6825 ensure that they are compatible with the configuration
6826 decisions below. Failure to do this may result in lost
6827 mail, broken <tt>From:</tt> lines, and other serious brain
6832 The mail spool is <file>/var/mail</file> and the interface to
6833 send a mail message is <file>/usr/sbin/sendmail</file> (as per
6834 the FHS). On older systems, the mail spool may be
6835 physically located in <file>/var/spool/mail</file>, but all
6836 access to the mail spool should be via the
6837 <file>/var/mail</file> symlink. The mail spool is part of the
6838 base system and not part of the MTA package.
6842 All Debian MUAs, MTAs, MDAs and other mailbox accessing
6843 programs (such as IMAP daemons) must lock the mailbox in an
6844 NFS-safe way. This means that <tt>fcntl()</tt> locking must
6845 be combined with dot locking. To avoid deadlocks, a program
6846 should use <tt>fcntl()</tt> first and dot locking after
6847 this, or alternatively implement the two locking methods in
6848 a non blocking way<footnote>
6850 If it is not possible to establish both locks, the
6851 system shouldn't wait for the second lock to be
6852 established, but remove the first lock, wait a (random)
6853 time, and start over locking again.
6855 </footnote>. Using the functions <tt>maillock</tt> and
6856 <tt>mailunlock</tt> provided by the
6857 <tt>liblockfile*</tt><footnote>
6859 You will need to depend on <tt>liblockfile1
6860 (>>1.01)</tt> to use these functions.
6862 </footnote> packages is the recommended way to realize this.
6866 Mailboxes are generally mode 660
6867 <tt><var>user</var>.mail</tt> unless the system
6868 administrator has chosen otherwise. A MUA may remove a
6869 mailbox (unless it has nonstandard permissions) in which
6870 case the MTA or another MUA must recreate it if needed.
6871 Mailboxes must be writable by group mail.
6875 The mail spool is 2775 <tt>root.mail</tt>, and MUAs should
6876 be setgid mail to do the locking mentioned above (and
6877 must obviously avoid accessing other users' mailboxes
6878 using this privilege).</p>
6881 <file>/etc/aliases</file> is the source file for the system mail
6882 aliases (e.g., postmaster, usenet, etc.), it is the one
6883 which the sysadmin and <prgn>postinst</prgn> scripts may
6884 edit. After <file>/etc/aliases</file> is edited the program or
6885 human editing it must call <prgn>newaliases</prgn>. All MTA
6886 packages must come with a <prgn>newaliases</prgn> program,
6887 even if it does nothing, but older MTA packages did not do
6888 this so programs should not fail if <prgn>newaliases</prgn>
6889 cannot be found. Note that because of this, all MTA
6890 packages must have <tt>Provides</tt>, <tt>Conflicts</tt> and
6891 <tt>Replaces: mail-transport-agent</tt> control file
6896 The convention of writing <tt>forward to
6897 <var>address</var></tt> in the mailbox itself is not
6898 supported. Use a <tt>.forward</tt> file instead.</p>
6901 The <prgn>rmail</prgn> program used by UUCP
6902 for incoming mail should be <file>/usr/sbin/rmail</file>.
6903 Likewise, <prgn>rsmtp</prgn>, for receiving
6904 batch-SMTP-over-UUCP, should be <file>/usr/sbin/rsmtp</file> if it
6908 If your package needs to know what hostname to use on (for
6909 example) outgoing news and mail messages which are generated
6910 locally, you should use the file <file>/etc/mailname</file>. It
6911 will contain the portion after the username and <tt>@</tt>
6912 (at) sign for email addresses of users on the machine
6913 (followed by a newline).
6917 Such package should check for the existence of this file
6918 when it is being configured. If it exists, it should be
6919 used without comment, although an MTA's configuration script
6920 may wish to prompt the user even if it finds that this file
6921 exists. If the file does not exist, the package should
6922 prompt the user for the value (preferably using
6923 <prgn>debconf</prgn>) and store it in <file>/etc/mailname</file>
6924 as well as using it in the package's configuration. The
6925 prompt should make it clear that the name will not just be
6926 used by that package. For example, in this situation the
6927 <tt>inn</tt> package could say something like:
6928 <example compact="compact">
6929 Please enter the "mail name" of your system. This is the
6930 hostname portion of the address to be shown on outgoing
6931 news and mail messages. The default is
6932 <var>syshostname</var>, your system's host name. Mail
6933 name ["<var>syshostname</var>"]:
6935 where <var>syshostname</var> is the output of <tt>hostname
6941 <heading>News system configuration</heading>
6944 All the configuration files related to the NNTP (news)
6945 servers and clients should be located under
6946 <file>/etc/news</file>.</p>
6949 There are some configuration issues that apply to a number
6950 of news clients and server packages on the machine. These
6954 <tag><file>/etc/news/organization</file></tag>
6955 <item><p>A string which should appear as the
6956 organization header for all messages posted
6957 by NNTP clients on the machine</p></item>
6959 <tag><file>/etc/news/server</file></tag>
6960 <item><p>Contains the FQDN of the upstream NNTP
6961 server, or localhost if the local machine is
6962 an NNTP server.</p></item>
6965 Other global files may be added as required for cross-package news
6966 configuration.</p></sect>
6970 <heading>Programs for the X Window System</heading>
6973 <heading>Providing X support and package priorities</heading>
6976 Programs that can be configured with support for the X
6977 Window System must be configured to do so and must declare
6978 any package dependencies necessary to satisfy their
6979 runtime requirements when using the X Window System. If
6980 such a package is of higher priority than the X packages
6981 on which it depends, it is required that either the
6982 X-specific components be split into a separate package, or
6983 that an alternative version of the package, which includes
6984 X support, be provided, or that the package's priority be
6990 <heading>Packages providing an X server</heading>
6993 Packages that provide an X server that, directly or
6994 indirectly, communicates with real input and display
6995 hardware should declare in their control data that they
6996 provide the virtual package <tt>xserver</tt>.<footnote>
6998 This implements current practice, and provides an
6999 actual policy for usage of the <tt>xserver</tt>
7000 virtual package which appears in the virtual packages
7001 list. In a nutshell, X servers that interface
7002 directly with the display and input hardware or via
7003 another subsystem (e.g., GGI) should provide
7004 <tt>xserver</tt>. Things like <tt>Xvfb</tt>,
7005 <tt>Xnest</tt>, and <tt>Xprt</tt> should not.
7012 <heading>Packages providing a terminal emulator</heading>
7015 Packages that provide a terminal emulator for the X Window
7016 System which meet the criteria listed below should declare
7017 in their control data that they provide the virtual
7018 package <tt>x-terminal-emulator</tt>. They should also
7019 register themselves as an alternative for
7020 <file>/usr/bin/x-terminal-emulator</file>, with a priority of
7025 To be an <tt>x-terminal-emulator</tt>, a program must:
7026 <list compact="compact">
7028 Be able to emulate a DEC VT100 terminal, or a
7029 compatible terminal.
7033 Support the command-line option <tt>-e
7034 <var>command</var></tt>, which creates a new
7035 terminal window<footnote>
7037 "New terminal window" does not necessarily mean
7038 a new top-level X window directly parented by
7039 the window manager; it could, if the terminal
7040 emulator application were so coded, be a new
7041 "view" in a multiple-document interface (MDI).
7044 and runs the specified <var>command</var>.
7048 Support the command-line option <tt>-T
7049 <var>title</var></tt>, which creates a new terminal
7050 window with the window title <var>title</var>.
7057 <heading>Packages providing a window manager</heading>
7060 Packages that provide a window manager should declare in
7061 their control data that they provide the virtual package
7062 <tt>x-window-manager</tt>. They should also register
7063 themselves as an alternative for
7064 <file>/usr/bin/x-window-manager</file>, with a priority
7065 calculated as follows:
7066 <list compact="compact">
7067 <item><p>Start with a priority of 20.</p></item>
7071 If the window manager supports the Debian menu
7072 system, add 20 points if this support is available
7073 in the package's default configuration (i.e., no
7074 configuration files belonging to the system or user
7075 have to be edited to activate the feature); if
7076 configuration files must be modified, add only 10
7082 If the window manager complies with <url
7083 id="http://www.freedesktop.org/standards/wm-spec.html"
7084 name="The Window Manager Specification Project">,
7085 written by the <url id="http://www.freedesktop.org"
7086 name="Free Desktop Group">, add 20 points.
7092 If the window manager permits the X session to be
7093 restarted using a <em>different</em> window manager
7094 (without killing the X server) in its default
7095 configuration, add 10 points; otherwise add none.
7103 <heading>Packages providing fonts</heading>
7106 Packages that provide fonts for the X Window
7109 For the purposes of Debian Policy, a "font for the X
7110 Window System" is one which is accessed via X protocol
7111 requests. Fonts for the Linux console, for PostScript
7112 renderers, or any other purpose, do not fit this
7113 definition. Any tool which makes such fonts available
7114 to the X Window System, however, must abide by this
7118 must do a number of things to ensure that they are both
7119 available without modification of the X or font server
7120 configuration, and that they do not corrupt files used by
7121 other font packages to register information about
7126 Fonts of any type supported by the X Window System
7127 must be in a separate binary package from any
7128 executables, libraries, or documentation (except
7129 that specific to the fonts shipped, such as their
7130 license information). If one or more of the fonts
7131 so packaged are necessary for proper operation of
7132 the package with which they are associated the font
7133 package may be Recommended; if the fonts merely
7134 provide an enhancement, a Suggests relationship may
7135 be used. Packages must not Depend on font
7138 This is because the X server may retrieve fonts
7139 from the local filesystem or over the network
7140 from an X font server; the Debian package system
7141 is empowered to deal only with the local
7150 BDF fonts must be converted to PCF fonts with the
7151 <prgn>bdftopcf</prgn> utility (available in the
7152 <tt>xutils</tt> package, <prgn>gzip</prgn>ped, and
7153 placed in a directory that corresponds to their
7155 <list compact="compact">
7157 100 dpi fonts must be placed in
7158 <file>/usr/X11R6/lib/X11/fonts/100dpi/</file>.
7162 75 dpi fonts must be placed in
7163 <file>/usr/X11R6/lib/X11/fonts/75dpi/</file>.
7167 Character-cell fonts, cursor fonts, and other
7168 low-resolution fonts must be placed in
7169 <file>/usr/X11R6/lib/X11/fonts/misc/</file>.
7176 Speedo fonts must be placed in
7177 <file>/usr/X11R6/lib/X11/fonts/Speedo/</file>.
7181 Type 1 fonts must be placed in
7182 <file>/usr/X11R6/lib/X11/fonts/Type1/</file>. If font
7183 metric files are available, they must be placed here
7189 Subdirectories of <file>/usr/X11R6/lib/X11/fonts/</file>
7190 other than those listed above must be neither
7191 created nor used. (The <file>PEX</file>, <file>CID</file>,
7192 and <file>cyrillic</file> directories are excepted for
7193 historical reasons, but installation of files into
7194 these directories remains discouraged.)
7200 Font packages may, instead of placing files directly
7201 in the X font directories listed above, provide
7202 symbolic links in that font directory pointing to
7203 the files' actual location in the filesystem. Such
7204 a location must comply with the FHS.
7210 Font packages should not contain both 75dpi and
7211 100dpi versions of a font. If both are available,
7212 they should be provided in separate binary packages
7213 with <tt>-75dpi</tt> or <tt>-100dpi</tt> appended to
7214 the names of the packages containing the
7215 corresponding fonts.
7221 Fonts destined for the <file>misc</file> subdirectory
7222 should not be included in the same package as 75dpi
7223 or 100dpi fonts; instead, they should be provided in
7224 a separate package with <tt>-misc</tt> appended to
7231 Font packages must not provide the files
7232 <file>fonts.dir</file>, <file>fonts.alias</file>, or
7233 <file>fonts.scale</file> in a font directory:
7236 <file>fonts.dir</file> files must not be provided at all.
7241 <file>fonts.alias</file> and <file>fonts.scale</file>
7242 files, if needed, should be provided in the
7244 <file>/etc/X11/fonts/<var>fontdir</var>/<var>package</var>.<var>extension</var></file>,
7245 where <var>fontdir</var> is the name of the
7247 <file>/usr/X11R6/lib/X11/fonts/</file> where the
7248 package's corresponding fonts are stored
7249 (e.g., <tt>75dpi</tt> or <tt>misc</tt>),
7250 <var>package</var> is the name of the package
7251 that provides these fonts, and
7252 <var>extension</var> is either <tt>scale</tt>
7253 or <tt>alias</tt>, whichever corresponds to
7263 Font packages must declare a dependency on
7264 <tt>xutils (>> 4.0.3)</tt> in their control
7271 Font packages that provide one or more
7272 <file>fonts.scale</file> files as described above must
7273 invoke <prgn>update-fonts-scale</prgn> on each
7274 directory into which they installed fonts
7275 <em>before</em> invoking
7276 <prgn>update-fonts-dir</prgn> on that directory.
7277 This invocation must occur in both the
7278 <prgn>postinst</prgn> (for all arguments) and
7279 <prgn>postrm</prgn> (for all arguments except
7280 <tt>upgrade</tt>) scripts.
7286 Font packages that provide one or more
7287 <file>fonts.alias</file> files as described above must
7288 invoke <prgn>update-fonts-alias</prgn> on each
7289 directory into which they installed fonts. This
7290 invocation must occur in both the
7291 <prgn>postinst</prgn> (for all arguments) and
7292 <prgn>postrm</prgn> (for all arguments except
7293 <tt>upgrade</tt>) scripts.
7299 Font packages must invoke
7300 <prgn>update-fonts-dir</prgn> on each directory into
7301 which they installed fonts. This invocation must
7302 occur in both the <prgn>postinst</prgn> (for all
7303 arguments) and <prgn>postrm</prgn> (for all
7304 arguments except <tt>upgrade</tt>) scripts.
7310 Font packages must not provide alias names for the
7311 fonts they include which collide with alias names
7312 already in use by fonts already packaged.
7318 Font packages must not provide fonts with the same
7319 XLFD registry name as another font already packaged.
7327 <heading>Application defaults files</heading>
7330 Application defaults files must be installed in the
7331 directory <file>/etc/X11/app-defaults/</file> (use of a
7332 localized subdirectory of <file>/etc/X11/</file> as described
7333 in the <em>X Toolkit Intrinsics - C Language
7334 Interface</em> manual is also permitted). They must be
7335 registered as <tt>conffile</tt>s or handled as
7336 configuration files. Packages must not provide the
7337 directory <file>/usr/X11R6/lib/X11/app-defaults/</file>.
7341 Customization of programs' X resources may also be
7342 supported with the provision of a file with the same name
7343 as that of the package placed in the
7344 <file>/etc/X11/Xresources/</file> directory, which must
7345 registered as a <tt>conffile</tt> or handled as a
7346 configuration file.<footnote>
7348 Note that this mechanism is not the same as using
7349 app-defaults; app-defaults are tied to the client
7350 binary on the local filesystem, whereas X resources
7351 are stored in the X server and affect all connecting
7355 <em>Important:</em> packages that install files into the
7356 <file>/etc/X11/Xresources/</file> directory must conflict with
7357 <tt>xbase (<< 3.3.2.3a-2)</tt>; if this is not done
7358 it is possible for the installing package to destroy a
7359 previously-existing <file>/etc/X11/Xresources</file> file
7360 which had been customized by the system administrator.
7365 <heading>Installation directory issues</heading>
7368 Packages using the X Window System should not be
7369 configured to install files under the <file>/usr/X11R6/</file>
7370 directory unless they use <prgn>imake</prgn>. The
7371 <file>/usr/X11R6/</file> directory hierarchy should be
7372 regarded as deprecated for all packages except the X
7373 Window System itself, and those which use the
7374 <prgn>imake</prgn> program it provides, in which case the
7375 packages may transition out of the <file>/usr/X11R6/</file>
7376 directory at the maintainer's discretion.<footnote>
7378 <prgn>Imake</prgn>-using programs are exempt because,
7379 as long as they are written correctly, the pathnames
7380 they use to locate resources and install themselves
7381 are derived wholly from the X Window System
7382 configuration. Thus, in the event that the X Window
7383 System moves to <file>/usr/X11R7/</file>,
7384 <file>/usr/X12/</file>, or just plain <file>/usr/</file>, all
7385 that is required for these programs is a recompile
7386 against the corresponding X Window System library
7387 development packages.
7390 Programs that use GNU <prgn>autoconf</prgn> and
7391 <prgn>automake</prgn> are usually easily configured at
7392 compile time to use <file>/usr/</file> instead of
7393 <file>/usr/X11R6/</file>, and this should be done whenever
7394 possible. Configuration files for window managers and
7395 display managers should be placed in a subdirectory of
7396 <file>/etc/X11/</file> corresponding to the package name due
7397 to these programs' tight integration with the mechanisms
7398 of the X Window System. Application-level programs should
7399 use the <file>/etc/</file> directory unless otherwise mandated
7400 by policy. The installation of files into subdirectories
7401 of <file>/usr/X11R6/include/X11/</file> and
7402 <file>/usr/X11R6/lib/X11/</file> is permitted but discouraged;
7403 package maintainers should determine if subdirectories of
7404 <file>/usr/lib/</file> and <file>/usr/share/</file> can be used
7405 instead. (The use of symbolic links from the
7406 <file>X11R6</file> directories to other FHS-compliant
7407 locations is encouraged if the program is not easily
7408 configured to look elsewhere for its files.) Packages
7409 must not provide or install files into the directories
7410 <file>/usr/bin/X11/</file>, <file>/usr/include/X11/</file> or
7411 <file>/usr/lib/X11/</file>. Files within a package should,
7412 however, make reference to these directories, rather than
7413 their <tt>X11R6</tt>-named counterparts
7414 <file>/usr/X11R6/bin/</file>, <file>/usr/X11R6/include/X11/</file>
7415 and <file>/usr/X11R6/lib/X11/</file>, if the resources being
7416 referred to have not been moved to other FHS-compliant
7422 <heading>The OSF/Motif and OpenMotif libraries</heading>
7425 <em>Programs that require the non-DFSG-compliant OSF/Motif or
7426 OpenMotif libraries</em><footnote>
7428 OSF/Motif and OpenMotif are collectively referred to as
7429 "Motif" in this policy document.
7432 should be compiled against and tested with LessTif (a free
7433 re-implementation of Motif) instead. If the maintainer
7434 judges that the program or programs do not work
7435 sufficiently well with LessTif to be distributed and
7436 supported, but do so when compiled against Motif, then two
7437 versions of the package should be created; one linked
7438 statically against Motif and with <tt>-smotif</tt>
7439 appended to the package name, and one linked dynamically
7440 against Motif and with <tt>-dmotif</tt> appended to the
7441 package name. Both Motif-linked versions are dependent
7442 upon non-DFSG-compliant software and thus cannot be
7443 uploaded to the <em>main</em> distribution; if the
7444 software is itself DFSG-compliant it may be uploaded to
7445 the <em>contrib</em> distribution. While known existing
7446 versions of Motif permit unlimited redistribution of
7447 binaries linked against the library (whether statically or
7448 dynamically), it is the package maintainer's
7449 responsibility to determine whether this is permitted by
7450 the license of the copy of Motif in his or her possession.
7456 <heading>Perl programs and modules</heading>
7458 Perl programs and modules should follow the current Perl
7459 policy as defined in the file found on
7460 <ftpsite>ftp.debian.org</ftpsite> in
7461 <ftppath>/debian/doc/package-developer/perl-policy.txt.gz</ftppath>
7462 or your local mirror. In addition, it is included in the
7463 <tt>debian-policy</tt> package.
7468 <heading>Emacs lisp programs</heading>
7471 Please refer to the "Debian Emacs Policy" (documented in
7472 <file>debian-emacs-policy.gz</file> of the
7473 <prgn>emacsen-common</prgn> package) for details of how to
7474 package emacs lisp programs.
7479 <heading>Games</heading>
7482 The permissions on <file>/var/games</file> are mode 755, owner
7483 <tt>root</tt> and group <tt>root</tt>.
7487 Each game decides on its own security policy.</p>
7490 Games which require protected, privileged access to
7491 high-score files, savegames, etc., may be made
7492 set-<em>group</em>-id (mode 2755) and owned by
7493 <tt>root.games</tt>, and use files and directories with
7494 appropriate permissions (770 <tt>root.games</tt>, for
7495 example). They must not be made
7496 set-<em>user</em>-id, as this causes security problems. (If
7497 an attacker can subvert any set-user-id game they can
7498 overwrite the executable of any other, causing other players
7499 of these games to run a Trojan horse program. With a
7500 set-group-id game the attacker only gets access to less
7501 important game data, and if they can get at the other
7502 players' accounts at all it will take considerably more
7506 Some packages, for example some fortune cookie programs, are
7507 configured by the upstream authors to install with their
7508 data files or other static information made unreadable so
7509 that they can only be accessed through set-id programs
7510 provided. You should not do this in a Debian package: anyone can
7511 download the <file>.deb</file> file and read the data from it,
7512 so there is no point making the files unreadable. Not
7513 making the files unreadable also means that you don't have
7514 to make so many programs set-id, which reduces the risk of a
7518 As described in the FHS, binaries of games should be
7519 installed in the directory <file>/usr/games</file>. This also
7520 applies to games that use the X Window System. Manual pages
7521 for games (X and non-X games) should be installed in
7522 <file>/usr/share/man/man6</file>.</p>
7526 <chapt id="docs"><heading>Documentation</heading>
7530 <heading>Manual pages</heading>
7533 You should install manual pages in <prgn>nroff</prgn> source
7534 form, in appropriate places under <file>/usr/share/man</file>.
7535 You should only use sections 1 to 9 (see the FHS for more
7536 details). You must not install a preformatted "cat page".
7540 Each program, utility, and function should have an
7541 associated manual page included in the same package. It is
7542 suggested that all configuration files also have a manual
7543 page included as well. Manual pages for protocols and other
7544 auxiliary things are optional.
7548 If no manual page is available, this is considered as a bug
7549 and should be reported to the Debian Bug Tracking System (the
7550 maintainer of the package is allowed to write this bug report
7551 themselves, if they so desire). Do not close the bug report
7552 until a proper manpage is available.<footnote>
7554 It is not very hard to write a man page. See the
7555 <url id="http://www.schweikhardt.net/man_page_howto.html"
7556 name="Man-Page-HOWTO">,
7557 <manref name="man" section="7">, the examples
7558 created by <prgn>debmake</prgn> or <prgn>dh_make</prgn>,
7559 the helper programs <prgn>help2man</prgn>, or the
7560 directory <file>/usr/share/doc/man-db/examples</file>.
7566 You may forward a complaint about a missing manpage to the
7567 upstream authors, and mark the bug as forwarded in the
7568 Debian bug tracking system. Even though the GNU Project do
7569 not in general consider the lack of a manpage to be a bug,
7570 we do; if they tell you that they don't consider it a bug
7571 you should leave the bug in our bug tracking system open
7576 Manual pages should be installed compressed using <tt>gzip -9</tt>.
7580 If one manpage needs to be accessible via several names it
7581 is better to use a symbolic link than the <file>.so</file>
7582 feature, but there is no need to fiddle with the relevant
7583 parts of the upstream source to change from <file>.so</file> to
7584 symlinks: don't do it unless it's easy. You should not
7585 create hard links in the manual page directories, nor put
7586 absolute filenames in <file>.so</file> directives. The filename
7587 in a <file>.so</file> in a manpage should be relative to the
7588 base of the manpage tree (usually
7589 <file>/usr/share/man</file>). If you do not create any links
7590 (whether symlinks, hard links, or <tt>.so</tt> directives)
7591 in the filesystem to the alternate names of the manpage,
7592 then you should not rely on <prgn>man</prgn> finding your
7593 manpage under those names based solely on the information in
7594 the manpage's header.<footnote>
7596 Supporting this in <prgn>man</prgn> often requires
7597 unreasonable processing time to find a manual page or to
7598 report that none exists, and moves knowledge into man's
7599 database that would be better left in the filesystem.
7600 This support is therefore deprecated and will cease to
7601 be present in the future.
7608 <heading>Info documents</heading>
7611 Info documents should be installed in <file>/usr/share/info</file>.
7612 They should be compressed with <tt>gzip -9</tt>.
7616 Your package should call <prgn>install-info</prgn> to update
7617 the Info <file>dir</file> file in its <prgn>postinst</prgn>
7618 script when called with a <tt>configure</tt> argument, for
7620 <example compact="compact">
7621 install-info --quiet --section Development Development \
7622 /usr/share/info/foobar.info
7626 It is a good idea to specify a section for the location of
7627 your program; this is done with the <tt>--section</tt>
7628 switch. To determine which section to use, you should look
7629 at <file>/usr/share/info/dir</file> on your system and choose the most
7630 relevant (or create a new section if none of the current
7631 sections are relevant). Note that the <tt>--section</tt>
7632 flag takes two arguments; the first is a regular expression
7633 to match (case-insensitively) against an existing section,
7634 the second is used when creating a new one.</p>
7637 You should remove the entries in the <prgn>prerm</prgn>
7638 script when called with a <tt>remove</tt> argument:
7639 <example compact="compact">
7640 install-info --quiet --remove /usr/share/info/foobar.info
7644 If <prgn>install-info</prgn> cannot find a description entry
7645 in the Info file you must supply one. See <manref
7646 name="install-info" section="8"> for details.</p>
7650 <heading>Additional documentation</heading>
7653 Any additional documentation that comes with the package may
7654 be installed at the discretion of the package maintainer.
7655 Text documentation should be installed in the directory
7656 <file>/usr/share/doc/<var>package</var></file>, where
7657 <var>package</var> is the name of the package, and
7658 compressed with <tt>gzip -9</tt> unless it is small.
7662 If a package comes with large amounts of documentation which
7663 many users of the package will not require you should create
7664 a separate binary package to contain it, so that it does not
7665 take up disk space on the machines of users who do not need
7666 or want it installed.</p>
7669 It is often a good idea to put text information files
7670 (<file>README</file>s, changelogs, and so forth) that come with
7671 the source package in <file>/usr/share/doc/<var>package</var></file>
7672 in the binary package. However, you don't need to install
7673 the instructions for building and installing the package, of
7677 Packages must not require the existance of any files in
7678 <file>/usr/share/doc/</file> in order to function
7681 The system administrator should be able to
7682 delete files in <file>/usr/share/doc/</file> without causing
7683 any programs to break.
7686 Any files that are referenced by programs but are also
7687 useful as standalone documentation should be installed under
7688 <file>/usr/share/<var>package</var>/</file> with symbolic links from
7689 <file>/usr/share/doc/<var>package</var></file>.
7693 <file>/usr/share/doc/<var>package</var></file> may be a symbolic
7694 link to another directory in <file>/usr/share/doc</file> only if
7695 the two packages both come from the same source and the
7696 first package Depends on the second.
7700 Former Debian releases placed all additional documentation
7701 in <file>/usr/doc/<var>package</var></file>. This has been
7702 changed to <file>/usr/share/doc/<var>package</var></file>,
7703 and packages must not put documentation in the directory
7704 <file>/usr/doc/<var>package</var></file>. <footnote>
7705 <p>At this phase of the transition, we no longer require a
7706 symbolic link in <file>/usr/doc/</file>. At a later point,
7707 policy shall change to make the symbolic links a bug.</p>
7713 <heading>Preferred documentation formats</heading>
7716 The unification of Debian documentation is being carried out
7720 If your package comes with extensive documentation in a
7721 markup format that can be converted to various other formats
7722 you should if possible ship HTML versions in a binary
7723 package, in the directory
7724 <file>/usr/share/doc/<var>appropriate-package</var></file> or
7725 its subdirectories.<footnote>
7727 The rationale: The important thing here is that HTML
7728 docs should be available in <em>some</em> package, not
7729 necessarily in the main binary package.
7735 Other formats such as PostScript may be provided at the
7736 package maintainer's discretion.
7740 <sect id="copyrightfile">
7741 <heading>Copyright information</heading>
7744 Every package must be accompanied by a verbatim copy of its
7745 copyright and distribution license in the file
7746 <file>/usr/share/doc/<var>package</var>/copyright</file>. This
7747 file must neither be compressed nor be a symbolic link.
7751 In addition, the copyright file must say where the upstream
7752 sources (if any) were obtained. It should name the original
7753 authors of the package and the Debian maintainer(s) who were
7754 involved with its creation.</p>
7757 A copy of the file which will be installed in
7758 <file>/usr/share/doc/<var>package</var>/copyright</file> should
7759 be in <file>debian/copyright</file> in the source package.
7763 <file>/usr/share/doc/<var>package</var></file> may be a symbolic
7764 link to another directory in <file>/usr/share/doc</file> only if
7765 the two packages both come from the same source and the
7766 first package Depends on the second. These rules are
7767 important because copyrights must be extractable by
7772 Packages distributed under the UCB BSD license, the Artistic
7773 license, the GNU GPL, and the GNU LGPL should refer to the
7774 files <file>/usr/share/common-licenses/BSD</file>,
7775 <file>/usr/share/common-licenses/Artistic</file>,
7776 <file>/usr/share/common-licenses/GPL</file>, and
7777 <file>/usr/share/common-licenses/LGPL</file> respectively,
7778 rather than quoting them in the copyright file.
7782 You should not use the copyright file as a general <file>README</file>
7783 file. If your package has such a file it should be
7784 installed in <file>/usr/share/doc/<var>package</var>/README</file> or
7785 <file>README.Debian</file> or some other appropriate place.</p>
7789 <heading>Examples</heading>
7792 Any examples (configurations, source files, whatever),
7793 should be installed in a directory
7794 <file>/usr/share/doc/<var>package</var>/examples</file>. These
7795 files should not be referenced by any program: they're there
7796 for the benefit of the system administrator and users as
7797 documentation only. Architecture-specific example files
7798 should be installed in a directory
7799 <file>/usr/lib/<var>package</var>/examples</file> with symbolic
7801 <file>/usr/share/doc/<var>package</var>/examples</file>, or the
7802 latter directory itself may be a symbolic link to the
7807 If the purpose of a package is to provide examples, then the
7808 example files may be installed into
7809 <file>/usr/share/doc/<var>package</var></file>.
7813 <sect id="changelogs">
7814 <heading>Changelog files</heading>
7817 The Debian changelog file (<file>debian/changelog</file>) should
7818 explain briefly what modifications were made in the Debian version
7819 of the package compared to the upstream one. Other changes and
7820 updates to the package should also be documented in this file.
7824 Mistakes in changelogs are usually best rectified by
7825 making a new changelog entry rather than "rewriting history"
7826 by editing old changelog entries.
7830 The format of the <file>debian/changelog</file> file is described
7831 in <ref id="dpkgchangelog">. In non-experimental packages you must
7832 use a format for <file>debian/changelog</file> which is supported
7833 by the most recent released version of <prgn>dpkg</prgn>.<footnote>
7835 If you wish to use an alternative format, you may do so as
7836 long as you include a parser for it in your source package.
7837 The parser must have an API compatible with that expected by
7838 <prgn>dpkg-genchanges</prgn> and <prgn>dpkg-gencontrol</prgn>.
7839 If there is general interest in the new format, you should
7840 contact the <package>dpkg</package> maintainer to have the
7841 parser script for it included in the <prgn>dpkg</prgn>
7842 package. (You will need to agree that the parser and its
7843 manpage may be distributed under the GNU GPL, just as the rest
7844 of <prgn>dpkg</prgn> is.)
7850 Packages that are not Debian-native must contain a
7851 compressed copy of the <file>debian/changelog</file> file from
7852 the Debian source tree in
7853 <file>/usr/share/doc/<var>package</var></file> with the name
7854 <file>changelog.Debian.gz</file>.
7858 If an upstream changelog is available, it should be accessible as
7859 <file>/usr/share/doc/<var>package</var>/changelog.gz</file> in
7860 plain text. If the upstream changelog is distributed in
7861 HTML, it should be made available in that form as
7862 <file>/usr/share/doc/<var>package</var>/changelog.html.gz</file>
7863 and a plain text <file>changelog.gz</file> should be generated
7864 from it using, for example, <tt>lynx -dump -nolist</tt>. If
7865 the upstream changelog files do not already conform to this
7866 naming convention, then this may be achieved either by
7867 renaming the files, or by adding a symbolic link, at the
7868 maintainer's discretion.<footnote>
7870 Rationale: People should not have to look in places for
7871 upstream changelogs merely because they are given
7872 different names or are distributed in HTML format.
7878 All of these files should be installed compressed using
7879 <tt>gzip -9</tt>, as they will become large with time even
7880 if they start out small.
7884 If the package has only one changelog which is used both as
7885 the Debian changelog and the upstream one because there is
7886 no separate upstream maintainer then that changelog should
7887 usually be installed as
7888 <file>/usr/share/doc/<var>package</var>/changelog.gz</file>; if
7889 there is a separate upstream maintainer, but no upstream
7890 changelog, then the Debian changelog should still be called
7891 <file>changelog.Debian.gz</file>.</p>
7896 <appendix id="pkg-scope">
7897 <heading>Introduction and scope of these appendices</heading>
7900 These appendices are taken essentially verbatim from the
7901 now-deprecated Packaging Manual, version 3.2.1.0. They are
7902 the chapters which are likely to be of use to package
7903 maintainers and which have not already been included in the
7904 policy document itself. Most of these sections are very likely
7905 not relevant to policy; they should be treated as
7906 documentation for the packaging system. Please note that these
7907 appendices are included for convenience, and for historical
7908 reasons: they used to be part of policy package, and they have
7909 not yet been incorporated into dpkg documentation. However,
7910 they still have value, and hence they are presented here.
7913 They have not yet been checked to ensure that they are
7914 compatible with the contents of policy, and if there are any
7915 contradictions, the version in the main policy document takes
7916 precedence. The remaining chapters of the old Packaging
7917 Manual have also not been read in detail to ensure that there
7918 are not parts which have been left out. Both of these will be
7923 <prgn>dpkg</prgn> is a suite of programs for creating binary
7924 package files and installing and removing them on Unix
7927 <prgn>dpkg</prgn> is targetted primarily at Debian
7928 GNU/Linux, but may work on or be ported to other
7935 The binary packages are designed for the management of
7936 installed executable programs (usually compiled binaries) and
7937 their associated data, though source code examples and
7938 documentation are provided as part of some packages.</p>
7941 This manual describes the technical aspects of creating Debian
7942 binary packages (<file>.deb</file> files). It documents the
7943 behaviour of the package management programs
7944 <prgn>dpkg</prgn>, <prgn>dselect</prgn> et al. and the way
7945 they interact with packages.</p>
7948 It also documents the interaction between
7949 <prgn>dselect</prgn>'s core and the access method scripts it
7950 uses to actually install the selected packages, and describes
7951 how to create a new access method.</p>
7954 This manual does not go into detail about the options and
7955 usage of the package building and installation tools. It
7956 should therefore be read in conjuction with those programs'
7961 The utility programs which are provided with <prgn>dpkg</prgn>
7962 for managing various system configuration and similar issues,
7963 such as <prgn>update-rc.d</prgn> and
7964 <prgn>install-info</prgn>, are not described in detail here -
7965 please see their manpages.
7969 It is assumed that the reader is reasonably familiar with the
7970 <prgn>dpkg</prgn> System Administrators' manual.
7971 Unfortunately this manual does not yet exist.
7975 The Debian version of the FSF's GNU hello program is provided
7976 as an example for people wishing to create Debian
7977 packages. The Debian <prgn>debmake</prgn> package is
7978 recommended as a very helpful tool in creating and maintaining
7979 Debian packages. However, while the tools and examples are
7980 helpful, they do not replace the need to read and follow the
7981 Policy and Programmer's Manual.</p>
7984 <appendix id="pkg-binarypkg"><heading>Binary packages (from old
7989 The binary package has two main sections. The first part
7990 consists of various control information files and scripts used
7991 by <prgn>dpkg</prgn> when installing and removing. See <ref
7992 id="pkg-controlarea">.
7996 The second part is an archive containing the files and
7997 directories to be installed.
8001 In the future binary packages may also contain other
8002 components, such as checksums and digital signatures. The
8003 format for the archive is described in full in the
8004 <file>deb(5)</file> manpage.
8008 <sect id="pkg-bincreating"><heading>Creating package files -
8009 <prgn>dpkg-deb</prgn>
8013 All manipulation of binary package files is done by
8014 <prgn>dpkg-deb</prgn>; it's the only program that has
8015 knowledge of the format. (<prgn>dpkg-deb</prgn> may be
8016 invoked by calling <prgn>dpkg</prgn>, as <prgn>dpkg</prgn>
8017 will spot that the options requested are appropriate to
8018 <prgn>dpkg-deb</prgn> and invoke that instead with the same
8023 In order to create a binary package you must make a
8024 directory tree which contains all the files and directories
8025 you want to have in the filesystem data part of the package.
8026 In Debian-format source packages this directory is usually
8027 <file>debian/tmp</file>, relative to the top of the package's
8032 They should have the locations (relative to the root of the
8033 directory tree you're constructing) ownerships and
8034 permissions which you want them to have on the system when
8039 With current versions of <prgn>dpkg</prgn> the uid/username
8040 and gid/groupname mappings for the users and groups being
8041 used should be the same on the system where the package is
8042 built and the one where it is installed.
8046 You need to add one special directory to the root of the
8047 miniature filesystem tree you're creating:
8048 <prgn>DEBIAN</prgn>. It should contain the control
8049 information files, notably the binary package control file
8050 (see <ref id="pkg-controlfile">).
8054 The <prgn>DEBIAN</prgn> directory will not appear in the
8055 filesystem archive of the package, and so won't be installed
8056 by <prgn>dpkg</prgn> when the package is installed.
8060 When you've prepared the package, you should invoke:
8062 dpkg --build <var>directory</var>
8067 This will build the package in
8068 <file><var>directory</var>.deb</file>. (<prgn>dpkg</prgn> knows
8069 that <tt>--build</tt> is a <prgn>dpkg-deb</prgn> option, so
8070 it invokes <prgn>dpkg-deb</prgn> with the same arguments to
8075 See the manpage <manref name="dpkg-deb" section="8"> for details of how
8076 to examine the contents of this newly-created file. You may find the
8077 output of following commands enlightening:
8079 dpkg-deb --info <var>filename</var>.deb
8080 dpkg-deb --contents <var>filename</var>.deb
8081 dpkg --contents <var>filename</var>.deb
8083 To view the copyright file for a package you could use this command:
8085 dpkg --fsys-tarfile <var>filename</var>.deb | tar xof usr/share/doc/<var>\*</var>copyright | less
8090 <sect id="pkg-controlarea">
8092 Package control information files
8096 The control information portion of a binary package is a
8097 collection of files with names known to <prgn>dpkg</prgn>.
8098 It will treat the contents of these files specially - some
8099 of them contain information used by <prgn>dpkg</prgn> when
8100 installing or removing the package; others are scripts which
8101 the package maintainer wants <prgn>dpkg</prgn> to run.
8105 It is possible to put other files in the package control
8106 area, but this is not generally a good idea (though they
8107 will largely be ignored).
8111 Here is a brief list of the control info files supported by
8112 <prgn>dpkg</prgn> and a summary of what they're used for.
8117 <tag><tt>control</tt>
8121 This is the key description file used by
8122 <prgn>dpkg</prgn>. It specifies the package's name
8123 and version, gives its description for the user,
8124 states its relationships with other packages, and so
8125 forth. See <ref id="pkg-controlfile">.
8129 It is usually generated automatically from information
8130 in the source package by the
8131 <prgn>dpkg-gencontrol</prgn> program, and with
8132 assistance from <prgn>dpkg-shlibdeps</prgn>. See <ref
8133 id="pkg-sourcetools">.</p>
8136 <tag><tt>postinst</tt>, <tt>preinst</tt>, <tt>postrm</tt>,
8142 These are exectuable files (usually scripts) which
8143 <prgn>dpkg</prgn> runs during installation, upgrade
8144 and removal of packages. They allow the package to
8145 deal with matters which are particular to that package
8146 or require more complicated processing than that
8147 provided by <prgn>dpkg</prgn>. Details of when and
8148 how they are called are in <ref
8149 id="maintainerscripts">.
8153 It is very important to make these scripts
8157 That means that if it runs successfully or fails
8158 and then you call it again it doesn't bomb out,
8159 but just ensures that everything is the way it
8162 </footnote> This is so that if an error occurs, the
8163 user interrupts <prgn>dpkg</prgn> or some other
8164 unforeseen circumstance happens you don't leave the
8165 user with a badly-broken package.
8169 The maintainer scripts are guaranteed to run with a
8170 controlling terminal and can interact with the user.
8171 If they need to prompt for passwords, do full-screen
8172 interaction or something similar you should do these
8173 things to and from <file>/dev/tty</file>, since
8174 <prgn>dpkg</prgn> will at some point redirect scripts'
8175 standard input and output so that it can log the
8176 installation process. Likewise, because these scripts
8177 may be executed with standard output redirected into a
8178 pipe for logging purposes, Perl scripts should set
8179 unbuffered output by setting <tt>$|=1</tt> so that the
8180 output is printed immediately rather than being
8185 Each script should return a zero exit status for
8186 success, or a nonzero one for failure.</p>
8189 <tag><tt>conffiles</tt>
8194 This file contains a list of configuration files which
8195 are to be handled automatically by <prgn>dpkg</prgn>
8196 (see <ref id="pkg-conffiles">). Note that not necessarily
8197 every configuration file should be listed here.</p>
8200 <tag><tt>shlibs</tt>
8205 This file contains a list of the shared libraries
8206 supplied by the package, with dependency details for
8207 each. This is used by <prgn>dpkg-shlibdeps</prgn>
8208 when it determines what dependencies are required in a
8209 package control file. The <tt>shlibs</tt> file format
8210 is described on <ref id="shlibs">.
8216 <sect id="pkg-controlfile">
8218 The main control information file: <tt>control</tt>
8221 The most important control information file used by
8222 <prgn>dpkg</prgn> when it installs a package is
8223 <tt>control</tt>. It contains all the package"s "vital
8228 The binary package control files of packages built from
8229 Debian sources are made by a special tool,
8230 <prgn>dpkg-gencontrol</prgn>, which reads
8231 <file>debian/control</file> and <file>debian/changelog</file> to
8232 find the information it needs. See <ref id="pkg-sourcepkg"> for
8237 The fields in binary package control files are:
8238 <list compact="compact">
8240 <p><qref id="pkg-f-Package"><tt>Package</tt></qref> (mandatory)</p>
8243 <p><qref id="versions"><tt>Version</tt></qref> (mandatory)</p>
8245 <item><p><qref id="pkg-f-Architecture"><tt>Architecture</tt></qref>
8249 This field should appear in all packages, though
8250 <prgn>dpkg</prgn> doesn't require it yet so that
8251 old packages can still be installed.
8257 <p><qref id="relationships"><tt>Depends</tt>,
8258 <tt>Provides</tt> et al.</qref></p>
8261 <p><qref id="pkg-f-Essential"><tt>Essential</tt></qref></p>
8264 <p><qref id="pkg-f-Maintainer"><tt>Maintainer</tt></qref></p>
8267 <p><qref id="pkg-f-classification"><tt>Section</tt>,
8268 <tt>Priority</tt></qref></p>
8271 <p><qref id="pkg-f-Source"><tt>Source</tt></qref></p>
8274 <p><qref id="descriptions"><tt>Description</tt></qref></p>
8278 <qref id="pkg-f-Installed-Size"><tt>Installed-Size</tt></qref>
8284 A description of the syntax of control files and the purpose
8285 of these fields is available in <ref id="pkg-controlfields">.
8290 <heading>Time Stamps</heading>
8292 Maintainers are encouraged to preserve the modification
8293 times of the upstream source files in a package, as far as
8294 is reasonably possible.
8297 The rationale is that there is some information conveyed
8298 by knowing the age of the file, for example, you could
8299 recognize that some documentation is very old by looking
8300 at the modification time, so it would be nice if the
8301 modification time of the upstream source would be
8309 <appendix id="pkg-sourcepkg">
8310 <heading>Source packages (from old Packaging Manual) </heading>
8313 The Debian binary packages in the distribution are generated
8314 from Debian sources, which are in a special format to assist
8315 the easy and automatic building of binaries.
8318 <sect id="pkg-sourcetools">
8319 <heading>Tools for processing source packages</heading>
8322 Various tools are provided for manipulating source packages;
8323 they pack and unpack sources and help build of binary
8324 packages and help manage the distribution of new versions.
8328 They are introduced and typical uses described here; see
8329 <manref name="dpkg-source" section="1"> for full
8330 documentation about their arguments and operation.
8334 For examples of how to construct a Debian source package,
8335 and how to use those utilities that are used by Debian
8336 source packages, please see the <prgn>hello</prgn> example
8342 <prgn>dpkg-source</prgn> - packs and unpacks Debian source
8347 This program is frequently used by hand, and is also
8348 called from package-independent automated building scripts
8349 such as <prgn>dpkg-buildpackage</prgn>.
8353 To unpack a package it is typically invoked with
8355 dpkg-source -x <var>.../path/to/filename</var>.dsc
8360 with the <file><var>filename</var>.tar.gz</file> and
8361 <file><var>filename</var>.diff.gz</file> (if applicable) in
8362 the same directory. It unpacks into
8363 <file><var>package</var>-<var>version</var></file>, and if
8365 <file><var>package</var>-<var>version</var>.orig</file>, in
8366 the current directory.
8370 To create a packed source archive it is typically invoked:
8372 dpkg-source -b <var>package</var>-<var>version</var>
8377 This will create the <file>.dsc</file>, <file>.tar.gz</file> and
8378 <file>.diff.gz</file> (if appropriate) in the current
8379 directory. <prgn>dpkg-source</prgn> does not clean the
8380 source tree first - this must be done separately if it is
8385 See also <ref id="pkg-sourcearchives">.</p>
8391 <prgn>dpkg-buildpackage</prgn> - overall package-building
8396 <prgn>dpkg-buildpackage</prgn> is a script which invokes
8397 <prgn>dpkg-source</prgn>, the <file>debian/rules</file>
8398 targets <tt>clean</tt>, <tt>build</tt> and
8399 <tt>binary</tt>, <prgn>dpkg-genchanges</prgn> and
8400 <prgn>pgp</prgn> to build a signed source and binary
8405 It is usually invoked by hand from the top level of the
8406 built or unbuilt source directory. It may be invoked with
8407 no arguments; useful arguments include:
8408 <taglist compact="compact">
8409 <tag><tt>-uc</tt>, <tt>-us</tt></tag>
8412 Do not PGP-sign the <tt>.changes</tt> file or the
8413 source package <tt>.dsc</tt> file, respectively.</p>
8415 <tag><tt>-p<var>pgp-command</var></tt></tag>
8418 Invoke <var>pgp-command</var> instead of finding
8419 <tt>pgp</tt> on the <prgn>PATH</prgn>.
8420 <var>pgp-command</var> must behave just like
8421 <prgn>pgp</prgn>.</p>
8423 <tag><tt>-r<var>root-command</var></tt></tag>
8426 When root privilege is required, invoke the command
8427 <var>root-command</var>. <var>root-command</var>
8428 should invoke its first argument as a command, from
8429 the <prgn>PATH</prgn> if necessary, and pass its
8430 second and subsequent arguments to the command it
8431 calls. If no <var>root-command</var> is supplied
8432 then <var>dpkg-buildpackage</var> will take no
8433 special action to gain root privilege, so that for
8434 most packages it will have to be invoked as root to
8437 <tag><tt>-b</tt>, <tt>-B</tt></tag>
8440 Two types of binary-only build and upload - see
8441 <manref name="dpkg-source" section="1">.
8450 <prgn>dpkg-gencontrol</prgn> - generates binary package
8455 This program is usually called from <file>debian/rules</file>
8456 (see <ref id="pkg-sourcetree">) in the top level of the source
8461 This is usually done just before the files and directories in the
8462 temporary directory tree where the package is being built have their
8463 permissions and ownerships set and the package is constructed using
8464 <prgn>dpkg-deb/</prgn>
8467 This is so that the control file which is produced has
8468 the right permissions
8474 <prgn>dpkg-gencontrol</prgn> must be called after all the
8475 files which are to go into the package have been placed in
8476 the temporary build directory, so that its calculation of
8477 the installed size of a package is correct.
8481 It is also necessary for <prgn>dpkg-gencontrol</prgn> to
8482 be run after <prgn>dpkg-shlibdeps</prgn> so that the
8483 variable substitutions created by
8484 <prgn>dpkg-shlibdeps</prgn> in <file>debian/substvars</file>
8489 For a package which generates only one binary package, and
8490 which builds it in <file>debian/tmp</file> relative to the top
8491 of the source package, it is usually sufficient to call
8492 <prgn>dpkg-gencontrol</prgn>.
8496 Sources which build several binaries will typically need
8499 dpkg-gencontrol -Pdebian/tmp-<var>pkg</var> -p<var>package</var>
8500 </example> The <tt>-P</tt> tells
8501 <prgn>dpkg-gencontrol</prgn> that the package is being
8502 built in a non-default directory, and the <tt>-p</tt>
8503 tells it which package's control file should be generated.
8507 <prgn>dpkg-gencontrol</prgn> also adds information to the
8508 list of files in <file>debian/files</file>, for the benefit of
8509 (for example) a future invocation of
8510 <prgn>dpkg-genchanges</prgn>.</p>
8515 <prgn>dpkg-shlibdeps</prgn> - calculates shared library
8520 This program is usually called from <file>debian/rules</file>
8521 just before <prgn>dpkg-gencontrol</prgn> (see <ref
8522 id="pkg-sourcetree">), in the top level of the source tree.
8526 Its arguments are executables.
8529 In a forthcoming dpkg version,
8530 <prgn>dpkg-shlibdeps</prgn> would be required to be
8531 called on shared libraries as well.
8534 They may be specified either in the locations in the
8535 source tree where they are created or in the locations
8536 in the temporary build tree where they are installed
8537 prior to binary package creation.
8539 </footnote> for which shared library dependencies should
8540 be included in the binary package's control file.
8544 If some of the found shared libraries should only
8545 warrant a <tt>Recommends</tt> or <tt>Suggests</tt>, or if
8546 some warrant a <tt>Pre-Depends</tt>, this can be achieved
8547 by using the <tt>-d<var>dependency-field</var></tt> option
8548 before those executable(s). (Each <tt>-d</tt> option
8549 takes effect until the next <tt>-d</tt>.)
8553 <prgn>dpkg-shlibdeps</prgn> does not directly cause the
8554 output control file to be modified. Instead by default it
8555 adds to the <file>debian/substvars</file> file variable
8556 settings like <tt>shlibs:Depends</tt>. These variable
8557 settings must be referenced in dependency fields in the
8558 appropriate per-binary-package sections of the source
8563 For example, the <prgn>procps</prgn> package generates two
8564 kinds of binaries, simple C binaries like <prgn>ps</prgn>
8565 which require a predependency and full-screen ncurses
8566 binaries like <prgn>top</prgn> which require only a
8567 recommendation. It can say in its <file>debian/rules</file>:
8569 dpkg-shlibdeps -dPre-Depends ps -dRecommends top
8571 and then in its main control file <file>debian/control</file>:
8575 Pre-Depends: ${shlibs:Pre-Depends}
8576 Recommends: ${shlibs:Recommends}
8582 Sources which produce several binary packages with
8583 different shared library dependency requirements can use
8584 the <tt>-p<var>varnameprefix</var></tt> option to override
8585 the default <tt>shlibs:</tt> prefix (one invocation of
8586 <prgn>dpkg-shlibdeps</prgn> per setting of this option).
8587 They can thus produce several sets of dependency
8588 variables, each of the form
8589 <tt><var>varnameprefix</var>:<var>dependencyfield</var></tt>,
8590 which can be referred to in the appropriate parts of the
8591 binary package control files.
8598 <prgn>dpkg-distaddfile</prgn> - adds a file to
8599 <file>debian/files</file>
8603 Some packages' uploads need to include files other than
8604 the source and binary package files.
8608 <prgn>dpkg-distaddfile</prgn> adds a file to the
8609 <file>debian/files</file> file so that it will be included in
8610 the <file>.changes</file> file when
8611 <prgn>dpkg-genchanges</prgn> is run.
8615 It is usually invoked from the <tt>binary</tt> target of
8616 <file>debian/rules</file>:
8618 dpkg-distaddfile <var>filename</var> <var>section</var> <var>priority</var>
8620 The <var>filename</var> is relative to the directory where
8621 <prgn>dpkg-genchanges</prgn> will expect to find it - this
8622 is usually the directory above the top level of the source
8623 tree. The <file>debian/rules</file> target should put the
8624 file there just before or just after calling
8625 <prgn>dpkg-distaddfile</prgn>.
8629 The <var>section</var> and <var>priority</var> are passed
8630 unchanged into the resulting <file>.changes</file> file. See
8631 <ref id="pkg-f-classification">.
8636 <sect1><heading><prgn>dpkg-genchanges</prgn> - generates a <file>.changes</file> upload
8641 This program is usually called by package-independent
8642 automatic building scripts such as
8643 <prgn>dpkg-buildpackage</prgn>, but it may also be called
8648 It is usually called in the top level of a built source
8649 tree, and when invoked with no arguments will print out a
8650 straightforward <file>.changes</file> file based on the
8651 information in the source package's changelog and control
8652 file and the binary and source packages which should have
8658 <sect1><heading><prgn>dpkg-parsechangelog</prgn> - produces parsed representation of
8663 This program is used internally by
8664 <prgn>dpkg-source</prgn> et al. It may also occasionally
8665 be useful in <file>debian/rules</file> and elsewhere. It
8666 parses a changelog, <file>debian/changelog</file> by default,
8667 and prints a control-file format representation of the
8668 information in it to standard output.
8672 <sect1 id="pkg-dpkgarch"><heading><prgn>dpkg-architecture</prgn> -
8673 information about the build and host system
8677 This program can be used manually, but is also invoked by
8678 <tt>dpkg-buildpackage</tt> or <file>debian/rules</file> to set
8679 to set environment or make variables which specify the build and
8680 host architecture for the package building process.
8685 <sect id="pkg-sourcetree"><heading>The Debianised source tree
8689 The source archive scheme described later is intended to
8690 allow a Debianised source tree with some associated control
8691 information to be reproduced and transported easily. The
8692 Debianised source tree is a version of the original program
8693 with certain files added for the benefit of the
8694 Debianisation process, and with any other changes required
8695 made to the rest of the source code and installation
8700 The extra files created for Debian are in the subdirectory
8701 <file>debian</file> of the top level of the Debianised source
8702 tree. They are described below.
8705 <sect1 id="pkg-debianrules"><heading><file>debian/rules</file> - the main building
8710 This file is an executable makefile, and contains the
8711 package-specific recipies for compiling the package and
8712 building binary package(s) out of the source.
8716 It must start with the line <tt>#!/usr/bin/make -f</tt>,
8717 so that it can be invoked by saying its name rather than
8718 invoking <prgn>make</prgn> explicitly.
8722 Since an interactive <file>debian/rules</file> script makes it
8723 impossible to autocompile that package and also makes it
8724 hard for other people to reproduce the same binary
8725 package, all <strong>required targets</strong> have to be
8726 non-interactive. At a minimul, required targets are the
8727 ones called by <prgn>dpkg-buildpackage</prgn>, namely,
8728 <em>clean</em>, <em>binary</em>, <em>binary-arch</em>, and
8729 <em>build</em>. It also follows that any target that these
8730 targets depend on must also be non-interactive.
8734 The targets which are required to be present are:
8736 <tag><tt>build</tt></tag>
8739 This should perform all non-interactive
8740 configuration and compilation of the package. If a
8741 package has an interactive pre-build configuration
8742 routine, the Debianised source package should be
8743 built after this has taken place, so that it can be
8744 built without rerunning the configuration.
8748 A package may also provide both of the targets
8749 <tt>build-arch</tt> and <tt>build-indep</tt>. The
8750 <tt>build-arch</tt> target, if provided, should
8751 perform all non-interactive configuration and
8752 compilation required for producing all
8753 architecture-dependant binary packages (those packages
8754 for which the body of the <tt>Architecture</tt> field
8755 in <tt>debian/control</tt> is not <tt>all</tt>).
8756 Similarly, the <tt>build-indep</tt> target, if
8757 provided, should perform all non-interactive
8758 configuration and compilation required for producing
8759 all architecture-independent binary packages (those
8760 packages for which the body of the
8761 <tt>Architecture</tt> field in <tt>debian/control</tt>
8762 is <tt>all</tt>). The <tt>build</tt> target should
8763 depend on those of the targets <tt>build-arch</tt> and
8764 <tt>build-indep</tt> that are provided in the rules
8769 If one or both of the targets <tt>build-arch</tt> and
8770 <tt>build-indep</tt> are not provided, then invoking
8771 <file>debian/rules</file> with one of the not-provided
8772 targets as arguments should produce a exit status code
8773 of 2. Usually this is provided automatically by make
8774 if the target is missing.
8778 For some packages, notably ones where the same
8779 source tree is compiled in different ways to produce
8780 two binary packages, the <tt>build</tt> target does
8781 not make much sense. For these packages it is good
8782 enough to provide two (or more) targets
8783 (<tt>build-a</tt> and <tt>build-b</tt> or whatever)
8784 for each of the ways of building the package, and a
8785 <tt>build</tt> target that does nothing. The
8786 <tt>binary</tt> target will have to build the
8787 package in each of the possible ways and make the
8788 binary package out of each.
8792 The targets <tt>build</tt>, <tt>build-arch</tt>
8793 and <tt>build-indep</tt> target must not do
8794 anything that might require root privilege.
8798 The <tt>build</tt> target may need to run
8799 <tt>clean</tt> first - see below.
8803 When a package has a configuration routine that takes
8804 a long time, or when the makefiles are poorly
8805 designed, or when <tt>build</tt> needs to run
8806 <tt>clean</tt> first, it is a good idea to <tt>touch
8807 build</tt> when the build process is complete. This
8808 will ensure that if <tt>debian/rules build</tt> is run
8809 again it will not rebuild the whole program.
8813 <tag><tt>binary</tt>, <tt>binary-arch</tt>,
8814 <tt>binary-indep</tt>
8818 The <tt>binary</tt> target should be all that is
8819 necessary for the user to build the binary
8820 package. All these targets are required to be
8821 non-interactive. It is split into two parts:
8822 <tt>binary-arch</tt> builds the packages' output
8823 files which are specific to a particular
8824 architecture, and <tt>binary-indep</tt> builds
8825 those which are not.
8829 <tt>binary</tt> should usually be a target with
8830 no commands which simply depends on
8831 <prgn>binary-arch</prgn> and
8832 <prgn>binary-indep</prgn>.
8836 Both <prgn>binary-*</prgn> targets should depend on
8837 the <tt>build</tt> target, above, so that the
8838 package is built if it has not been already. It
8839 should then create the relevant binary package(s),
8840 using <prgn>dpkg-gencontrol</prgn> to make their
8841 control files and <prgn>dpkg-deb</prgn> to build
8842 them and place them in the parent of the top level
8847 If one of the <prgn>binary-*</prgn> targets has
8848 nothing to do (this will be always be the case if
8849 the source generates only a single binary package,
8850 whether architecture-dependent or not) it
8851 <em>must</em> still exist, but should always
8856 <ref id="pkg-binarypkg"> describes how to construct
8861 The <tt>binary</tt> targets must be invoked as
8866 <tag><tt>clean</tt></tag>
8870 This should undo any effects that the
8871 <tt>build</tt> and <tt>binary</tt> targets
8872 may have had, except that it should leave alone any
8873 output files created in the parent directory by a
8874 run of <tt>binary</tt>. This target is required
8875 to be non-interactive.
8879 If a <tt>build</tt> file is touched at the end
8880 of the <tt>build</tt> target, as suggested
8881 above, it must be removed as the first thing that
8882 <tt>clean</tt> does, so that running
8883 <tt>build</tt> again after an interrupted
8884 <tt>clean</tt> doesn't think that everything is
8889 The <tt>clean</tt> target must be invoked as
8890 root if <tt>binary</tt> has been invoked since
8891 the last <tt>clean</tt>, or if
8892 <tt>build</tt> has been invoked as root (since
8893 <tt>build</tt> may create directories, for
8898 <tag><tt>get-orig-source</tt> (optional)</tag>
8902 This target fetches the most recent version of the
8903 original source package from a canonical archive
8904 site (via FTP or WWW, for example), does any
8905 necessary rearrangement to turn it into the original
8906 source tarfile format described below, and leaves it
8907 in the current directory.
8911 This target may be invoked in any directory, and
8912 should take care to clean up any temporary files it
8917 This target is optional, but providing it if
8918 possible is a good idea.
8924 The <tt>build</tt>, <tt>binary</tt> and
8925 <tt>clean</tt> targets must be invoked with a current
8926 directory of the package's top-level directory.
8931 Additional targets may exist in <file>debian/rules</file>,
8932 either as published or undocumented interfaces or for the
8933 package's internal use.
8937 The architecture we build on and build for is determined by make
8938 variables via dpkg-architecture (see <ref id="pkg-dpkgarch">). You can
8939 get the Debian architecture and the GNU style architecture
8940 specification string for the build machine as well as the host
8941 machine. Here is a list of supported make variables:
8942 <list compact="compact">
8944 <p><tt>DEB_*_ARCH</tt> (the Debian architecture)</p>
8947 <p><tt>DEB_*_GNU_TYPE</tt> (the GNU style architecture
8948 specification string)</p>
8951 <p><tt>DEB_*_GNU_CPU</tt> (the CPU part of DEB_*_GNU_TYPE)</p>
8954 <p><tt>DEB_*_GNU_SYSTEM</tt> (the System part of
8960 where <tt>*</tt> is either <tt>BUILD</tt> for specification of
8961 the build machine or <tt>HOST</tt> for specification of the machine
8966 Backward compatibility can be provided in the rules file
8967 by setting the needed variables to suitable default
8968 values, please refer to the documentation of
8969 dpkg-architecture for details.
8973 It is important to understand that the <tt>DEB_*_ARCH</tt>
8974 string does only determine which Debian architecture we
8975 build on resp. for. It should not be used to get the CPU
8976 or System information, the GNU style variables should be
8982 <sect1><heading><file>debian/control</file>
8986 This file contains version-independent details about the
8987 source package and about the binary packages it creates.
8991 It is a series of sets of control fields, each
8992 syntactically similar to a binary package control file.
8993 The sets are separated by one or more blank lines. The
8994 first set is information about the source package in
8995 general; each subsequent set describes one binary package
8996 that the source tree builds.
9000 The syntax and semantics of the fields are described below
9001 in <ref id="pkg-controlfields">.
9005 The general (binary-package-independent) fields are:
9006 <list compact="compact">
9008 <p><qref id="pkg-f-Source"><tt>Source</tt></qref> (mandatory)</p>
9011 <p><qref id="pkg-f-Maintainer"><tt>Maintainer</tt></qref></p>
9015 <qref id="pkg-f-classification"><tt>Section</tt> and
9016 <tt>Priority</tt></qref>
9017 (classification, mandatory)
9022 <qref id="relationships"><tt>Build-Depends</tt> et
9023 al.</qref> (source package interrelationships)
9028 <qref id="pkg-f-Standards-Version"><tt>Standards-Version</tt></qref>
9034 The per-binary-package fields are:
9035 <list compact="compact">
9037 <p><qref id="pkg-f-Package"><tt>Package</tt></qref> (mandatory)</p>
9041 <qref id="pkg-f-Architecture"><tt>Architecture</tt></qref>
9045 <p><qref id="descriptions"><tt>Description</tt></qref></p>
9049 <qref id="pkg-f-classification"><tt>Section</tt> and
9050 <tt>Priority</tt></qref> (classification)</p>
9053 <p><qref id="pkg-f-Essential"><tt>Essential</tt></qref></p>
9057 <qref id="relationships"><tt>Depends</tt> et
9058 al.</qref> (binary package interrelationships)
9064 These fields are used by <prgn>dpkg-gencontrol</prgn> to
9065 generate control files for binary packages (see below), by
9066 <prgn>dpkg-genchanges</prgn> to generate the
9067 <tt>.changes</tt> file to accompany the upload, and by
9068 <prgn>dpkg-source</prgn> when it creates the <file>.dsc</file>
9069 source control file as part of a source archive.
9073 The fields here may contain variable references - their
9074 values will be substituted by
9075 <prgn>dpkg-gencontrol</prgn>, <prgn>dpkg-genchanges</prgn>
9076 or <prgn>dpkg-source</prgn> when they generate output
9077 control files. See <ref id="pkg-srcsubstvars"> for details.
9080 <p> <sect2><heading>User-defined fields
9084 Additional user-defined fields may be added to the
9085 source package control file. Such fields will be
9086 ignored, and not copied to (for example) binary or
9087 source package control files or upload control files.
9091 If you wish to add additional unsupported fields to
9092 these output files you should use the mechanism
9097 Fields in the main source control information file with
9098 names starting <tt>X</tt>, followed by one or more of
9099 the letters <tt>BCS</tt> and a hyphen <tt>-</tt>, will
9100 be copied to the output files. Only the part of the
9101 field name after the hyphen will be used in the output
9102 file. Where the letter <tt>B</tt> is used the field
9103 will appear in binary package control files, where the
9104 letter <tt>S</tt> is used in source package control
9105 files and where <tt>C</tt> is used in upload control
9106 (<tt>.changes</tt>) files.
9110 For example, if the main source information control file
9113 XBS-Comment: I stand between the candle and the star.
9115 then the binary and source package control files will contain the
9118 Comment: I stand between the candle and the star.
9125 <sect1 id="pkg-dpkgchangelog"><heading><file>debian/changelog</file>
9129 This file records the changes to the Debian-specific parts of the
9133 Though there is nothing stopping an author who is also
9134 the Debian maintainer from using it for all their
9135 changes, it will have to be renamed if the Debian and
9136 upstream maintainers become different
9143 It has a special format which allows the package building
9144 tools to discover which version of the package is being
9145 built and find out other release-specific information.
9149 That format is a series of entries like this:
9151 <var>package</var> (<var>version</var>) <var>distribution(s)</var>; urgency=<var>urgency</var>
9153 * <var>change details</var>
9154 <var>more change details</var>
9155 * <var>even more change details</var>
9157 -- <var>maintainer name and email address</var> <var>date</var>
9162 <var>package</var> and <var>version</var> are the source
9163 package name and version number.
9167 <var>distribution(s)</var> lists the distributions where
9168 this version should be installed when it is uploaded - it
9169 is copied to the <tt>Distribution</tt> field in the
9170 <tt>.changes</tt> file. See <ref id="pkg-f-Distribution">.
9174 <var>urgency</var> is the value for the <tt>Urgency</tt>
9175 field in the <file>.changes</file> file for the upload. See
9176 <ref id="pkg-f-Urgency">. It is not possible to specify an
9177 urgency containing commas; commas are used to separate
9178 <tt><var>keyword</var>=<var>value</var></tt> settings in
9179 the <prgn>dpkg</prgn> changelog format (though there is
9180 currently only one useful <var>keyword</var>,
9185 The change details may in fact be any series of lines
9186 starting with at least two spaces, but conventionally each
9187 change starts with an asterisk and a separating space and
9188 continuation lines are indented so as to bring them in
9189 line with the start of the text above. Blank lines may be
9190 used here to separate groups of changes, if desired.
9194 The maintainer name and email address should <em>not</em>
9195 necessarily be those of the usual package maintainer.
9196 They should be the details of the person doing
9197 <em>this</em> version. The information here will be
9198 copied to the <file>.changes</file> file, and then later used
9199 to send an acknowledgement when the upload has been
9204 The <var>date</var> should be in RFC822 format
9207 This is generated by the <prgn>822-date</prgn>
9210 </footnote>; it should include the timezone specified
9211 numerically, with the timezone name or abbreviation
9212 optionally present as a comment.
9216 The first "title" line with the package name should start
9217 at the left hand margin; the "trailer" line with the
9218 maintainer and date details should be preceded by exactly
9219 one space. The maintainer details and the date must be
9220 separated by exactly two spaces.
9224 An Emacs mode for editing this format is available: it is
9225 called <tt>debian-changelog-mode</tt>. You can have this
9226 mode selected automatically when you edit a Debian
9227 changelog by adding a local variables clause to the end of
9231 <sect2><heading>Defining alternative changelog formats
9235 It is possible to use a different format to the standard
9236 one, by providing a parser for the format you wish to
9241 In order to have <tt>dpkg-parsechangelog</tt> run your
9242 parser, you must include a line within the last 40 lines
9243 of your file matching the Perl regular expression:
9244 <tt>\schangelog-format:\s+([0-9a-z]+)\W</tt> The part in
9245 parentheses should be the name of the format. For
9246 example, you might say:
9248 @@@ changelog-format: joebloggs @@@
9250 Changelog format names are non-empty strings of alphanumerics.
9254 If such a line exists then <tt>dpkg-parsechangelog</tt>
9255 will look for the parser as
9256 <file>/usr/lib/dpkg/parsechangelog/<var>format-name</var></file>
9258 <file>/usr/local/lib/dpkg/parsechangelog/<var>format-name</var></file>;
9259 it is an error for it not to find it, or for it not to
9260 be an executable program. The default changelog format
9261 is <tt>dpkg</tt>, and a parser for it is provided with
9262 the <tt>dpkg</tt> package.
9266 The parser will be invoked with the changelog open on
9267 standard input at the start of the file. It should read
9268 the file (it may seek if it wishes) to determine the
9269 information required and return the parsed information
9270 to standard output in the form of a series of control
9271 fields in the standard format. By default it should
9272 return information about only the most recent version in
9273 the changelog; it should accept a
9274 <tt>-v<var>version</var></tt> option to return changes
9275 information from all versions present <em>strictly
9276 after</em> <var>version</var>, and it should then be an
9277 error for <var>version</var> not to be present in the
9283 <list compact="compact">
9285 <p><qref id="pkg-f-Source"><tt>Source</tt></qref></p>
9288 <p><qref id="versions"><tt>Version</tt></qref> (mandatory)</p>
9292 <qref id="pkg-f-Distribution"><tt>Distribution</tt></qref>
9297 <p><qref id="pkg-f-Urgency"><tt>Urgency</tt></qref> (mandatory)</p>
9301 <qref id="pkg-f-Maintainer"><tt>Maintainer</tt></qref>
9306 <p><qref id="pkg-f-Date"><tt>Date</tt></qref></p>
9310 <qref id="pkg-f-Changes"><tt>Changes</tt></qref>
9317 If several versions are being returned (due to the use
9318 of <tt>-v</tt>), the urgency value should be of the
9319 highest urgency code listed at the start of any of the
9320 versions requested followed by the concatenated
9321 (space-separated) comments from all the versions
9322 requested; the maintainer, version, distribution and
9323 date should always be from the most recent version.
9327 For the format of the <tt>Changes</tt> field see <ref
9328 id="pkg-f-Changes">.
9332 If the changelog format which is being parsed always or
9333 almost always leaves a blank line between individual
9334 change notes these blank lines should be stripped out,
9335 so as to make the resulting output compact.
9339 If the changelog format does not contain date or package
9340 name information this information should be omitted from
9341 the output. The parser should not attempt to synthesise
9342 it or find it from other sources.
9346 If the changelog does not have the expected format the
9347 parser should exit with a nonzero exit status, rather
9348 than trying to muddle through and possibly generating
9353 A changelog parser may not interact with the user at
9357 <!-- FIXME: section pkg-srcsubstvars is the same as srcsubstvars -->
9359 <sect1 id="pkg-srcsubstvars"><heading><file>debian/substvars</file>
9360 and variable substitutions
9364 When <prgn>dpkg-gencontrol</prgn>,
9365 <prgn>dpkg-genchanges</prgn> and <prgn>dpkg-source</prgn>
9366 generate control files they do variable substitutions on
9367 their output just before writing it. Variable
9368 substitutions have the form
9369 <tt>${<var>variable-name</var>}</tt>. The optional file
9370 <file>debian/substvars</file> contains variable substitutions
9371 to be used; variables can also be set directly from
9372 <file>debian/rules</file> using the <tt>-V</tt> option to the
9373 source packaging commands, and certain predefined
9374 variables are available.
9378 This file is usually generated and modified dynamically by
9379 <file>debian/rules</file> targets, in which case it must be
9380 removed by the <tt>clean</tt> target.
9384 See <manref name="dpkg-source" section="1"> for full
9385 details about source variable substitutions, including the
9386 format of <file>debian/substvars</file>.</p>
9389 <sect1><heading><file>debian/files</file>
9393 This file is not a permanent part of the source tree; it
9394 is used while building packages to record which files are
9395 being generated. <prgn>dpkg-genchanges</prgn> uses it
9396 when it generates a <file>.changes</file> file.
9400 It should not exist in a shipped source package, and so it
9401 (and any backup files or temporary files such as
9402 <file>files.new</file>
9405 <file>files.new</file> is used as a temporary file by
9406 <prgn>dpkg-gencontrol</prgn> and
9407 <prgn>dpkg-distaddfile</prgn> - they write a new
9408 version of <file>files</file> here before renaming it,
9409 to avoid leaving a corrupted copy if an error
9412 </footnote>) should be removed by the
9413 <tt>clean</tt> target. It may also be wise to
9414 ensure a fresh start by emptying or removing it at the
9415 start of the <tt>binary</tt> target.
9419 <prgn>dpkg-gencontrol</prgn> adds an entry to this file
9420 for the <file>.deb</file> file that will be created by
9421 <prgn>dpkg-deb</prgn> from the control file that it
9422 generates, so for most packages all that needs to be done
9423 with this file is to delete it in <tt>clean</tt>.
9427 If a package upload includes files besides the source
9428 package and any binary packages whose control files were
9429 made with <prgn>dpkg-gencontrol</prgn> then they should be
9430 placed in the parent of the package's top-level directory
9431 and <prgn>dpkg-distaddfile</prgn> should be called to add
9432 the file to the list in <file>debian/files</file>.</p>
9435 <sect1><heading><file>debian/tmp</file>
9439 This is the canonical temporary location for the
9440 construction of binary packages by the <tt>binary</tt>
9441 target. The directory <file>tmp</file> serves as the root of
9442 the filesystem tree as it is being constructed (for
9443 example, by using the package's upstream makefiles install
9444 targets and redirecting the output there), and it also
9445 contains the <tt>DEBIAN</tt> subdirectory. See <ref
9446 id="pkg-bincreating">.
9450 If several binary packages are generated from the same
9451 source tree it is usual to use several
9452 <file>debian/tmp<var>something</var></file> directories, for
9453 example <file>tmp-a</file> or <file>tmp-doc</file>.
9457 Whatever <file>tmp</file> directories are created and used by
9458 <tt>binary</tt> must of course be removed by the
9459 <tt>clean</tt> target.</p></sect1>
9463 <sect id="pkg-sourcearchives"><heading>Source packages as archives
9467 As it exists on the FTP site, a Debian source package
9468 consists of three related files. You must have the right
9469 versions of all three to be able to use them.
9474 <tag>Debian source control file - <tt>.dsc</tt></tag>
9478 This file contains a series of fields, identified and
9479 separated just like the fields in the control file of
9480 a binary package. The fields are listed below; their
9481 syntax is described above, in <ref id="pkg-controlfields">.
9482 <list compact="compact">
9484 <p><qref id="pkg-f-Source"><tt>Source</tt></qref></p>
9487 <p><qref id="versions"><tt>Version</tt></qref></p>
9490 <p><qref id="pkg-f-Maintainer"><tt>Maintainer</tt></qref></p>
9493 <p><qref id="pkg-f-Binary"><tt>Binary</tt></qref></p>
9496 <p><qref id="pkg-f-Architecture"><tt>Architecture</tt></qref></p>
9500 <qref id="relationships"><tt>Build-Depends</tt> et
9501 al.</qref> (source package interrelationships)
9506 <qref id="pkg-f-Standards-Version"><tt>Standards-Version</tt></qref></p>
9509 <p><qref id="pkg-f-Files"><tt>Files</tt></qref></p>
9514 The source package control file is generated by
9515 <prgn>dpkg-source</prgn> when it builds the source
9516 archive, from other files in the source package,
9517 described above. When unpacking it is checked against
9518 the files and directories in the other parts of the
9519 source package, as described below.</p>
9523 Original source archive -
9525 <var>package</var>_<var>upstream-version</var>.orig.tar.gz
9532 This is a compressed (with <tt>gzip -9</tt>)
9533 <prgn>tar</prgn> file containing the source code from
9534 the upstream authors of the program. The tarfile
9535 unpacks into a directory
9536 <file><var>package</var>-<var>upstream-version</var>.orig</file>,
9537 and does not contain files anywhere other than in
9538 there or in its subdirectories.</p>
9542 Debianisation diff -
9544 <var>package</var>_<var>upstream_version-revision</var>.diff.gz
9550 This is a unified context diff (<tt>diff -u</tt>)
9551 giving the changes which are required to turn the
9552 original source into the Debian source. These changes
9553 may only include editing and creating plain files.
9554 The permissions of files, the targets of symbolic
9555 links and the characteristics of special files or
9556 pipes may not be changed and no files may be removed
9561 All the directories in the diff must exist, except the
9562 <file>debian</file> subdirectory of the top of the source
9563 tree, which will be created by
9564 <prgn>dpkg-source</prgn> if necessary when unpacking.
9568 The <prgn>dpkg-source</prgn> program will
9569 automatically make the <file>debian/rules</file> file
9570 executable (see below).</p></item>
9575 If there is no original source code - for example, if the
9576 package is specially prepared for Debian or the Debian
9577 maintainer is the same as the upstream maintainer - the
9578 format is slightly different: then there is no diff, and the
9580 <file><var>package</var>_<var>version</var>.tar.gz</file> and
9581 contains a directory
9582 <file><var>package</var>-<var>version</var></file>.
9586 <sect><heading>Unpacking a Debian source package without
9587 <prgn>dpkg-source</prgn>
9591 <tt>dpkg-source -x</tt> is the recommended way to unpack a
9592 Debian source package. However, if it is not available it
9593 is possible to unpack a Debian source archive as follows:
9594 <enumlist compact="compact">
9597 Untar the tarfile, which will create a <file>.orig</file>
9601 <p>Rename the <file>.orig</file> directory to
9602 <file><var>package</var>-<var>version</var></file>.</p>
9606 Create the subdirectory <file>debian</file> at the top of
9607 the source tree.</p>
9609 <item><p>Apply the diff using <tt>patch -p0</tt>.</p>
9611 <item><p>Untar the tarfile again if you want a copy of the original
9612 source code alongside the Debianised version.</p>
9617 It is not possible to generate a valid Debian source archive
9618 without using <prgn>dpkg-source</prgn>. In particular,
9619 attempting to use <prgn>diff</prgn> directly to generate the
9620 <file>.diff.gz</file> file will not work.
9623 <sect1><heading>Restrictions on objects in source packages
9627 The source package may not contain any hard links
9630 This is not currently detected when building source
9631 packages, but only when extracting
9637 Hard links may be permitted at some point in the
9638 future, but would require a fair amount of
9641 </footnote>, device special files, sockets or setuid or
9645 Setgid directories are allowed.
9651 The source packaging tools manage the changes between the
9652 original and Debianised source using <prgn>diff</prgn> and
9653 <prgn>patch</prgn>. Turning the original source tree as
9654 included in the <file>.orig.tar.gz</file> into the debianised
9655 source must not involve any changes which cannot be
9656 handled by these tools. Problematic changes which cause
9657 <prgn>dpkg-source</prgn> to halt with an error when
9658 building the source package are:
9659 <list compact="compact">
9660 <item><p>Adding or removing symbolic links, sockets or pipes.</p>
9662 <item><p>Changing the targets of symbolic links.</p>
9664 <item><p>Creating directories, other than <file>debian</file>.</p>
9666 <item><p>Changes to the contents of binary files.</p></item>
9667 </list> Changes which cause <prgn>dpkg-source</prgn> to
9668 print a warning but continue anyway are:
9669 <list compact="compact">
9672 Removing files, directories or symlinks.
9675 Renaming a file is not treated specially - it is
9676 seen as the removal of the old file (which
9677 generates a warning, but is otherwise ignored),
9678 and the creation of the new
9685 Changed text files which are missing the usual final
9686 newline (either in the original or the modified
9691 Changes which are not represented, but which are not detected by
9692 <prgn>dpkg-source</prgn>, are:
9693 <list compact="compact">
9694 <item><p>Changing the permissions of files (other than
9695 <file>debian/rules</file>) and directories.</p></item>
9700 The <file>debian</file> directory and <file>debian/rules</file>
9701 are handled specially by <prgn>dpkg-source</prgn> - before
9702 applying the changes it will create the <file>debian</file>
9703 directory, and afterwards it will make
9704 <file>debian/rules</file> world-exectuable.
9710 <appendix id="pkg-controlfields"><heading>Control files and their
9711 fields (from old Packaging Manual)
9715 Many of the tools in the <prgn>dpkg</prgn> suite manipulate
9716 data in a common format, known as control files. Binary and
9717 source packages have control data as do the <file>.changes</file>
9718 files which control the installation of uploaded files, and
9719 <prgn>dpkg</prgn>'s internal databases are in a similar
9723 <sect><heading>Syntax of control files
9727 A file consists of one or more paragraphs of fields. The
9728 paragraphs are separated by blank lines. Some control files
9729 only allow one paragraph; others allow several, in which
9730 case each paragraph often refers to a different package.
9734 Each paragraph is a series of fields and values; each field
9735 consists of a name, followed by a colon and the value. It
9736 ends at the end of the line. Horizontal whitespace (spaces
9737 and tabs) may occur before or after the value and is ignored
9738 there; it is conventional to put a single space after the
9743 Some fields' values may span several lines; in this case
9744 each continuation line <em>must</em> start with a space or
9745 tab. Any trailing spaces or tabs at the end of individual
9746 lines of a field value are ignored.
9750 Except where otherwise stated only a single line of data is
9751 allowed and whitespace is not significant in a field body.
9752 Whitespace may never appear inside names (of packages,
9753 architectures, files or anything else), version numbers or
9754 in between the characters of multi-character version
9759 Field names are not case-sensitive, but it is usual to
9760 capitalise the field names using mixed case as shown below.
9764 Blank lines, or lines consisting only of spaces and tabs,
9765 are not allowed within field values or between fields - that
9766 would mean a new paragraph.
9770 It is important to note that there are several fields which
9771 are optional as far as <prgn>dpkg</prgn> and the related
9772 tools are concerned, but which must appear in every Debian
9773 package, or whose omission may cause problems.
9777 <sect><heading>List of fields
9780 <sect1 id="pkg-f-Package"><heading><tt>Package</tt>
9784 The name of the binary package. Package names consist of
9785 the alphanumerics and <tt>+</tt> <tt>-</tt> <tt>.</tt>
9786 (plus, minus and full stop).
9789 The characters <tt>@</tt> <tt>:</tt> <tt>=</tt>
9790 <tt>%</tt> <tt>_</tt> (at, colon, equals, percent
9791 and underscore) used to be legal and are still
9792 accepted when found in a package file, but may not be
9793 used in new packages
9799 They must be at least two characters and must start with
9800 an alphanumeric. In current versions of dpkg they are
9801 sort of case-sensitive<footnote><p>This is a
9802 bug.</p></footnote>; use lowercase package names unless
9803 the package you're building (or referring to, in other
9804 fields) is already using uppercase.</p>
9807 <sect1 id="pkg-f-Version"><heading><tt>Version</tt>
9811 This lists the source or binary package's version number -
9812 see <ref id="versions">.
9817 <sect1 id="pkg-f-Architecture"><heading><tt>Architecture</tt>
9821 This is the architecture string; it is a single word for
9822 the Debian architecture.
9826 <prgn>dpkg</prgn> will check the declared architecture of
9827 a binary package against its own compiled-in value before
9832 The special value <tt>all</tt> indicates that the package
9833 is architecture-independent.
9837 In the main <file>debian/control</file> file in the source
9838 package, or in the source package control file
9839 <file>.dsc</file>, a list of architectures (separated by
9840 spaces) is also allowed, as is the special value
9841 <tt>any</tt>. A list indicates that the source will build
9842 an architecture-dependent package, and will only work
9843 correctly on the listed architectures. <tt>any</tt>
9844 indicates that though the source package isn't dependent
9845 on any particular architecture and should compile fine on
9846 any one, the binary package(s) produced are not
9847 architecture-independent but will instead be specific to
9848 whatever the current build architecture is.
9852 In a <file>.changes</file> file the <tt>Architecture</tt>
9853 field lists the architecture(s) of the package(s)
9854 currently being uploaded. This will be a list; if the
9855 source for the package is being uploaded too the special
9856 entry <tt>source</tt> is also present.
9860 See <ref id="pkg-debianrules"> for information how to get the
9861 architecture for the build process.
9865 <sect1 id="pkg-f-Maintainer"><heading><tt>Maintainer</tt>
9869 The package maintainer's name and email address. The name
9870 should come first, then the email address inside angle
9871 brackets <tt><></tt> (in RFC822 format).
9875 If the maintainer's name contains a full stop then the
9876 whole field will not work directly as an email address due
9877 to a misfeature in the syntax specified in RFC822; a
9878 program using this field as an address must check for this
9879 and correct the problem if necessary (for example by
9880 putting the name in round brackets and moving it to the
9881 end, and bringing the email address forward).
9885 In a <file>.changes</file> file or parsed changelog data this
9886 contains the name and email address of the person
9887 responsible for the particular version in question - this
9888 may not be the package's usual maintainer.
9892 This field is usually optional in as far as the
9893 <prgn>dpkg</prgn> are concerned, but its absence when
9894 building packages usually generates a warning.</p>
9897 <sect1 id="pkg-f-Source"><heading><tt>Source</tt>
9901 This field identifies the source package name.
9905 In a main source control information or a
9906 <file>.changes</file> or <file>.dsc</file> file or parsed
9907 changelog data this may contain only the name of the
9912 In the control file of a binary package (or in a
9913 <file>Packages</file> file) it may be followed by a version
9914 number in parentheses.
9917 It is usual to leave a space after the package name if
9918 a version number is specified.
9920 </footnote> This version number may be omitted (and is, by
9921 <prgn>dpkg-gencontrol</prgn>) if it has the same value as
9922 the <tt>Version</tt> field of the binary package in
9923 question. The field itself may be omitted from a binary
9924 package control file when the source package has the same
9925 name and version as the binary package.
9929 <sect1><heading>Package interrelationship fields:
9930 <tt>Depends</tt>, <tt>Pre-Depends</tt>,
9931 <tt>Recommends</tt> <tt>Suggests</tt>, <tt>Conflicts</tt>,
9932 <tt>Provides</tt>, <tt>Replaces</tt>
9936 These fields describe the package's relationships with
9937 other packages. Their syntax and semantics are described
9938 in <ref id="relationships">.</p>
9941 <sect1 id="pkg-f-Description"><heading><tt>Description</tt>
9945 In a binary package <tt>Packages</tt> file or main source
9946 control file this field contains a description of the
9947 binary package, in a special format. See <ref
9948 id="descriptions"> for details.
9952 In a <file>.changes</file> file it contains a summary of the
9953 descriptions for the packages being uploaded. The part of
9954 the field before the first newline is empty; thereafter
9955 each line has the name of a binary package and the summary
9956 description line from that binary package. Each line is
9957 indented by one space.</p>
9960 <sect1 id="pkg-f-Essential"><heading><tt>Essential</tt>
9964 This is a boolean field which may occur only in the
9965 control file of a binary package (or in the
9966 <file>Packages</file> file) or in a per-package fields
9967 paragraph of a main source control data file.
9971 If set to <tt>yes</tt> then <prgn>dpkg</prgn> and
9972 <prgn>dselect</prgn> will refuse to remove the package
9973 (though it can be upgraded and/or replaced). The other
9974 possible value is <tt>no</tt>, which is the same as not
9975 having the field at all.</p>
9978 <sect1 id="pkg-f-classification"><heading><tt>Section</tt> and
9983 These two fields classify the package. The
9984 <tt>Priority</tt> represents how important that it is that
9985 the user have it installed; the <tt>Section</tt>
9986 represents an application area into which the package has
9991 When they appear in the <file>debian/control</file> file these
9992 fields give values for the section and priority subfields
9993 of the <tt>Files</tt> field of the <file>.changes</file> file,
9994 and give defaults for the section and priority of the
9999 The section and priority are represented, though not as
10000 separate fields, in the information for each file in the
10001 <qref id="pkg-f-Files"><tt>-File</tt></qref>field of a
10002 <file>.changes</file> file. The section value in a
10003 <file>.changes</file> file is used to decide where to install
10004 a package in the FTP archive.
10008 These fields are not used by by <prgn>dpkg</prgn> proper,
10009 but by <prgn>dselect</prgn> when it sorts packages and
10014 These fields may appear in binary package control files,
10015 in which case they provide a default value in case the
10016 <file>Packages</file> files are missing the information.
10017 <prgn>dpkg</prgn> and <prgn>dselect</prgn> will only use
10018 the value from a <file>.deb</file> file if they have no other
10019 information; a value listed in a <file>Packages</file> file
10020 will always take precedence. By default
10021 <prgn>dpkg-gencontrol</prgn> does not include the section
10022 and priority in the control file of a binary package - use
10023 the <tt>-isp</tt>, <tt>-is</tt> or <tt>-ip</tt> options to
10024 achieve this effect.</p>
10027 <sect1 id="pkg-f-Binary"><heading><tt>Binary</tt>
10031 This field is a list of binary packages.
10035 When it appears in the <file>.dsc</file> file it is the list
10036 of binary packages which a source package can produce. It
10037 does not necessarily produce all of these binary packages
10038 for every architecture. The source control file doesn't
10039 contain details of which architectures are appropriate for
10040 which of the binary packages.
10044 When it appears in a <file>.changes</file> file it lists the
10045 names of the binary packages actually being uploaded.
10049 The syntax is a list of binary packages separated by
10053 A space after each comma is conventional.
10055 </footnote> Currently the packages must be separated using
10056 only spaces in the <file>.changes</file> file.</p>
10059 <sect1 id="pkg-f-Installed-Size"><heading><tt>Installed-Size</tt>
10063 This field appears in the control files of binary
10064 packages, and in the <file>Packages</file> files. It gives
10065 the total amount of disk space required to install the
10070 The disk space is represented in kilobytes as a simple
10071 decimal number.</p>
10074 <sect1 id="pkg-f-Files"><heading><tt>Files</tt>
10078 This field contains a list of files with information about
10079 each one. The exact information and syntax varies with
10080 the context. In all cases the part of the field
10081 contents on the same line as the field name is empty. The
10082 remainder of the field is one line per file, each line
10083 being indented by one space and containing a number of
10084 sub-fields separated by spaces.
10088 In the <file>.dsc</file> (Debian source control) file each
10089 line contains the MD5 checksum, size and filename of the
10090 tarfile and (if applicable) diff file which make up the
10091 remainder of the source package.
10094 That is, the parts which are not the
10097 </footnote> The exact forms of the filenames are described
10098 in <ref id="pkg-sourcearchives">.
10102 In the <file>.changes</file> file this contains one line per
10103 file being uploaded. Each line contains the MD5 checksum,
10104 size, section and priority and the filename. The section
10105 and priority are the values of the corresponding fields in
10106 the main source control file - see <ref
10107 id="pkg-f-classification">. If no section or priority is
10108 specified then <tt>-</tt> should be used, though section
10109 and priority values must be specified for new packages to
10110 be installed properly.
10114 The special value <tt>byhand</tt> for the section in a
10115 <tt>.changes</tt> file indicates that the file in question
10116 is not an ordinary package file and must by installed by
10117 hand by the distribution maintainers. If the section is
10118 <tt>byhand</tt> the priority should be <tt>-</tt>.
10122 If a new Debian revision of a package is being shipped and
10123 no new original source archive is being distributed the
10124 <tt>.dsc</tt> must still contain the <tt>Files</tt> field
10125 entry for the original source archive
10126 <file><var>package</var>-<var>upstream-version</var>.orig.tar.gz</file>,
10127 but the <file>.changes</file> file should leave it out. In
10128 this case the original source archive on the distribution
10129 site must match exactly, byte-for-byte, the original
10130 source archive which was used to generate the
10131 <file>.dsc</file> file and diff which are being uploaded.</p>
10136 id="pkg-f-Standards-Version"><heading><tt>Standards-Version</tt>
10140 The most recent version of the standards (the Debian Policy
10141 and associated texts) with which the package complies. This
10142 is updated manually when editing the source package to
10143 conform to newer standards; it can sometimes be used to
10144 tell when a package needs attention.
10148 Its format is the same as that of a version number except
10149 that no epoch or Debian revision is allowed - see <ref
10150 id="versions">.</p>
10154 <sect1 id="pkg-f-Distribution"><heading><tt>Distribution</tt>
10158 In a <file>.changes</file> file or parsed changelog output
10159 this contains the (space-separated) name(s) of the
10160 distribution(s) where this version of the package should
10161 be or was installed. Distribution names follow the rules
10162 for package names. (See <ref id="pkg-f-Package">).
10166 Current distribution values are:
10168 <tag><em>stable</em></tag>
10171 This is the current "released" version of Debian
10172 GNU/Linux. A new version is released approximately
10173 every 3 months after the <em>development</em> code has
10174 been <em>frozen</em> for a month of testing. Once the
10175 distribution is <em>stable</em> only major bug fixes
10176 are allowed. When changes are made to this
10177 distribution, the release number is increased
10178 (for example: 1.2r1 becomes 1.2r2 then 1.2r3, etc).
10182 <tag><em>unstable</em></tag>
10185 This distribution value refers to the
10186 <em>developmental</em> part of the Debian distribution
10187 tree. New packages, new upstream versions of packages
10188 and bug fixes go into the <em>unstable</em> directory
10189 tree. Download from this distribution at your own
10193 <tag><em>contrib</em></tag>
10196 The packages with this distribution value do not meet
10197 the criteria for inclusion in the main Debian
10198 distribution as defined by the Policy Manual, but meet
10199 the criteria for the <em>contrib</em>
10200 Distribution. There is currently no distinction
10201 between stable and unstable packages in the
10202 <em>contrib</em> or <em>non-free</em>
10203 distributions. Use your best judgement in downloading
10204 from this Distribution.</p>
10207 <tag><em>non-free</em></tag>
10210 Like the packages in the <em>contrib</em> seciton,
10211 the packages in <em>non-free</em> do not meet the
10212 criteria for inclusion in the main Debian distribution
10213 as defined by the Policy Manual. Again, use your best
10214 judgement in downloading from this Distribution.</p>
10216 <tag><em>experimental</em></tag>
10219 The packages with this distribution value are deemed
10220 by their maintainers to be high risk. Oftentimes they
10221 represent early beta or developmental packages from
10222 various sources that the maintainers want people to
10223 try, but are not ready to be a part of the other parts
10224 of the Debian distribution tree. Download at your own
10228 <tag><em>frozen</em></tag>
10231 From time to time, (currently, every 3 months) the
10232 <em>unstable</em> distribution enters a state of
10233 "code-freeze" in anticipation of release as a
10234 <em>stable</em> version. During this period of testing
10235 (usually 4 weeks) only fixes for existing or
10236 newly-discovered bugs will be allowed.
10239 </taglist> You should list <em>all</em> distributions that
10240 the package should be installed into. Except in unusual
10241 circumstances, installations to <em>stable</em> should also
10242 go into <em>frozen</em> (if it exists) and
10243 <em>unstable</em>. Likewise, installations into
10244 <em>frozen</em> should also go into <em>unstable</em>.</p>
10247 <sect1 id="pkg-f-Urgency"><heading><tt>Urgency</tt>
10251 This is a description of how important it is to upgrade to
10252 this version from previous ones. It consists of a single
10253 keyword usually taking one of the values <tt>LOW</tt>,
10254 <tt>MEDIUM</tt> or <tt>HIGH</tt>) followed by an optional
10255 commentary (separated by a space) which is usually in
10256 parentheses. For example:
10258 Urgency: LOW (HIGH for diversions users)
10263 This field appears in the <file>.changes</file> file and in
10264 parsed changelogs; its value appears as the value of the
10265 <tt>urgency</tt> attribute in a <prgn>dpkg</prgn>-style
10266 changelog (see <ref id="pkg-dpkgchangelog">).
10270 Urgency keywords are not case-sensitive.</p>
10273 <sect1 id="pkg-f-Date"><heading><tt>Date</tt>
10277 In <tt>.changes</tt> files and parsed changelogs, this
10278 gives the date the package was built or last edited.</p>
10281 <sect1 id="pkg-f-Format"><heading><tt>Format</tt>
10285 This field occurs in <file>.changes</file> files, and
10286 specifies a format revision for the file. The format
10287 described here is version <tt>1.5</tt>. The syntax of the
10288 format value is the same as that of a package version
10289 number except that no epoch or Debian revision is allowed
10290 - see <ref id="versions">.</p>
10293 <sect1 id="pkg-f-Changes"><heading><tt>Changes</tt>
10297 In a <file>.changes</file> file or parsed changelog this field
10298 contains the human-readable changes data, describing the
10299 differences between the last version and the current one.
10303 There should be nothing in this field before the first
10304 newline; all the subsequent lines must be indented by at
10305 least one space; blank lines must be represented by a line
10306 consiting only of a space and a full stop.
10310 Each version's change information should be preceded by a
10311 "title" line giving at least the version, distribution(s)
10312 and urgency, in a human-readable way.
10316 If data from several versions is being returned the entry
10317 for the most recent version should be returned first, and
10318 entries should be separated by the representation of a
10319 blank line (the "title" line may also be followed by the
10320 representation of blank line).</p>
10323 <sect1 id="pkg-f-Filename"><heading><tt>Filename</tt> and
10324 <tt>MSDOS-Filename</tt>
10328 These fields in <tt>Packages</tt> files give the
10329 filename(s) of (the parts of) a package in the
10330 distribution directories, relative to the root of the
10331 Debian hierarchy. If the package has been split into
10332 several parts the parts are all listed in order, separated
10336 <sect1 id="pkg-f-Size"><heading><tt>Size</tt> and <tt>MD5sum</tt>
10340 These fields in <file>Packages</file> files give the size (in
10341 bytes, expressed in decimal) and MD5 checksum of the
10342 file(s) which make(s) up a binary package in the
10343 distribution. If the package is split into several parts
10344 the values for the parts are listed in order, separated by
10348 <sect1 id="pkg-f-Status"><heading><tt>Status</tt>
10352 This field in <prgn>dpkg</prgn>'s status file records
10353 whether the user wants a package installed, removed or
10354 left alone, whether it is broken (requiring
10355 reinstallation) or not and what its current state on the
10356 system is. Each of these pieces of information is a
10360 <sect1 id="pkg-f-Config-Version"><heading><tt>Config-Version</tt>
10364 If a package is not installed or not configured, this
10365 field in <prgn>dpkg</prgn>'s status file records the last
10366 version of the package which was successfully
10370 <sect1 id="pkg-f-Conffiles"><heading><tt>Conffiles</tt>
10374 This field in <prgn>dpkg</prgn>'s status file contains
10375 information about the automatically-managed configuration
10376 files held by a package. This field should <em>not</em>
10377 appear anywhere in a package!</p>
10380 <sect1><heading>Obsolete fields
10384 These are still recognised by <prgn>dpkg</prgn> but should
10385 not appear anywhere any more.
10386 <taglist compact="compact">
10388 <tag><tt>Revision</tt></tag>
10389 <tag><tt>Package-Revision</tt></tag>
10390 <tag><tt>Package_Revision</tt></tag>
10393 The Debian revision part of the package version was
10394 at one point in a separate control file field. This
10395 field went through several names.</p>
10398 <tag><tt>Recommended</tt></tag>
10399 <item><p>Old name for <tt>Recommends</tt></p>
10402 <tag><tt>Optional</tt></tag>
10403 <item><p>Old name for <tt>Suggests</tt>.</p>
10405 <tag><tt>Class</tt></tag>
10406 <item><p>Old name for <tt>Priority</tt>.</p>
10414 <appendix id="pkg-conffiles"><heading>Configuration file handling
10415 (from old Packaging Manual)
10419 <prgn>dpkg</prgn> can do a certain amount of automatic
10420 handling of package configuration files.
10424 Whether this mechanism is appropriate depends on a number of
10425 factors, but basically there are two approaches to any
10426 particular configuration file.
10430 The easy method is to ship a best-effort configuration in the
10431 package, and use <prgn>dpkg</prgn>'s conffile mechanism to
10432 handle updates. If the user is unlikely to want to edit the
10433 file, but you need them to be able to without losing their
10434 changes, and a new package with a changed version of the file
10435 is only released infrequently, this is a good approach.
10439 The hard method is to build the configuration file from
10440 scratch in the <prgn>postinst</prgn> script, and to take the
10441 responsibility for fixing any mistakes made in earlier
10442 versions of the package automatically. This will be
10443 appropriate if the file is likely to need to be different on
10447 <sect><heading>Automatic handling of configuration files by
10452 A package may contain a control area file called
10453 <tt>conffiles</tt>. This file should be a list of filenames
10454 of configuration files needing automatic handling, separated
10455 by newlines. The filenames should be absolute pathnames,
10456 and the files referred to should actually exist in the
10461 When a package is upgraded <prgn>dpkg</prgn> will process
10462 the configuration files during the configuration stage,
10463 shortly before it runs the package's <prgn>postinst</prgn>
10468 For each file it checks to see whether the version of the
10469 file included in the package is the same as the one that was
10470 included in the last version of the package (the one that is
10471 being upgraded from); it also compares the version currently
10472 installed on the system with the one shipped with the last
10477 If neither the user nor the package maintainer has changed
10478 the file, it is left alone. If one or the other has changed
10479 their version, then the changed version is preferred - i.e.,
10480 if the user edits their file, but the package maintainer
10481 doesn't ship a different version, the user's changes will
10482 stay, silently, but if the maintainer ships a new version
10483 and the user hasn't edited it the new version will be
10484 installed (with an informative message). If both have
10485 changed their version the user is prompted about the problem
10486 and must resolve the differences themselves.
10490 The comparisons are done by calculating the MD5 message
10491 digests of the files, and storing the MD5 of the file as it
10492 was included in the most recent version of the package.
10496 When a package is installed for the first time
10497 <prgn>dpkg</prgn> will install the file that comes with it,
10498 unless that would mean overwriting a file already on the
10503 However, note that <prgn>dpkg</prgn> will <em>not</em>
10504 replace a conffile that was removed by the user (or by a
10505 script). This is necessary because with some programs a
10506 missing file produces an effect hard or impossible to
10507 achieve in another way, so that a missing file needs to be
10508 kept that way if the user did it.
10512 Note that a package should <em>not</em> modify a
10513 <prgn>dpkg</prgn>-handled conffile in its maintainer
10514 scripts. Doing this will lead to <prgn>dpkg</prgn> giving
10515 the user confusing and possibly dangerous options for
10516 conffile update when the package is upgraded.</p>
10519 <sect><heading>Fully-featured maintainer script configuration
10524 For files which contain site-specific information such as
10525 the hostname and networking details and so forth, it is
10526 better to create the file in the package's
10527 <prgn>postinst</prgn> script.
10531 This will typically involve examining the state of the rest
10532 of the system to determine values and other information, and
10533 may involve prompting the user for some information which
10534 can't be obtained some other way.
10538 When using this method there are a couple of important
10539 issues which should be considered:
10543 If you discover a bug in the program which generates the
10544 configuration file, or if the format of the file changes
10545 from one version to the next, you will have to arrange for
10546 the postinst script to do something sensible - usually this
10547 will mean editing the installed configuration file to remove
10548 the problem or change the syntax. You will have to do this
10549 very carefully, since the user may have changed the file,
10550 perhaps to fix the very problem that your script is trying
10551 to deal with - you will have to detect these situations and
10552 deal with them correctly.
10556 If you do go down this route it's probably a good idea to
10557 make the program that generates the configuration file(s) a
10558 separate program in <file>/usr/sbin</file>, by convention called
10559 <file><var>package</var>config</file> and then run that if
10560 appropriate from the post-installation script. The
10561 <tt><var>package</var>config</tt> program should not
10562 unquestioningly overwrite an existing configuration - if its
10563 mode of operation is geared towards setting up a package for
10564 the first time (rather than any arbitrary reconfiguration
10565 later) you should have it check whether the configuration
10566 already exists, and require a <tt>--force</tt> flag to
10567 overwrite it.</p></sect>
10570 <appendix id="pkg-alternatives"><heading>Alternative versions of
10571 an interface - <prgn>update-alternatives</prgn> (from old
10576 When several packages all provide different versions of the
10577 same program or file it is useful to have the system select a
10578 default, but to allow the system administrator to change it
10579 and have their decisions respected.
10583 For example, there are several versions of the <prgn>vi</prgn>
10584 editor, and there is no reason to prevent all of them from
10585 being installed at once, each under their own name
10586 (<prgn>nvi</prgn>, <prgn>vim</prgn> or whatever).
10587 Nevertheless it is desirable to have the name <tt>vi</tt>
10588 refer to something, at least by default.
10592 If all the packages involved cooperate, this can be done with
10593 <prgn>update-alternatives</prgn>.
10597 Each package provides its own version under its own name, and
10598 calls <prgn>update-alternatives</prgn> in its postinst to
10599 register its version (and again in its prerm to deregister
10604 See the manpage <manref name="update-alternatives"
10605 section="8"> for details.
10609 If <prgn>update-alternatives</prgn> does not seem appropriate
10610 you may wish to consider using diversions instead.</p>
10613 <appendix id="pkg-diversions"><heading>Diversions - overriding a
10614 package's version of a file (from old Packaging Manual)
10618 It is possible to have <prgn>dpkg</prgn> not overwrite a file
10619 when it reinstalls the package it belongs to, and to have it
10620 put the file from the package somewhere else instead.
10624 This can be used locally to override a package's version of a
10625 file, or by one package to override another's version (or
10626 provide a wrapper for it).
10630 Before deciding to use a diversion, read <ref
10631 id="pkg-alternatives"> to see if you really want a diversion
10632 rather than several alternative versions of a program.
10636 There is a diversion list, which is read by <prgn>dpkg</prgn>,
10637 and updated by a special program <prgn>dpkg-divert</prgn>.
10638 Please see <manref name="dpkg-divert" section="8"> for full
10639 details of its operation.
10643 When a package wishes to divert a file from another, it should
10644 call <prgn>dpkg-divert</prgn> in its preinst to add the
10645 diversion and rename the existing file. For example,
10646 supposing that a <prgn>smailwrapper</prgn> package wishes to
10647 install a wrapper around <file>/usr/sbin/smail</file>:
10649 if [ install = "$1" ]; then
10650 dpkg-divert --package smailwrapper --add --rename \
10651 --divert /usr/sbin/smail.real /usr/sbin/smail
10653 </example> Testing <tt>$1</tt> is necessary so that the script
10654 doesn't try to add the diversion again when
10655 <prgn>smailwrapper</prgn> is upgraded. The <tt>--package
10656 smailwrapper</tt> ensures that <prgn>smailwrapper</prgn>'s
10657 copy of <file>/usr/sbin/smail</file> can bypass the diversion and
10658 get installed as the true version.
10662 The postrm has to do the reverse:
10664 if [ remove = "$1" ]; then
10665 dpkg-divert --package smailwrapper --remove --rename \
10666 --divert /usr/sbin/smail.real /usr/sbin/smail
10672 Do not attempt to divert a file which is vitally important for
10673 the system's operation - when using <prgn>dpkg-divert</prgn>
10674 there is a time, after it has been diverted but before
10675 <prgn>dpkg</prgn> has installed the new version, when the file
10676 does not exist.</p>
10681 <!-- vim:set ai et sts=2 sw=2 tw=76: -->