1 <!doctype debiandoc system [
2 <!-- include version information so we don't have to hard code it
3 within the document -->
4 <!entity % versiondata SYSTEM "version.ent"> %versiondata;
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 five 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 also 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 Packages which use the shared library should have a
3977 dependency on the name of the shared library package,
3978 <file><var>libraryname</var><var>soversion</var></file>. When
3979 the soname changes you can have both versions of the library
3980 installed while migrating from the old library to the new.
3984 <sect id="sharedlibs-shlibdeps">
3985 <heading>Dependencies between the library and other packages -
3986 the <tt>shlibs</tt> system</heading>
3989 If a package contains a binary or library which links to a
3990 shared library, we must ensure that when the package is
3991 installed on the system, all of the libraries needed are
3992 also installed. This requirement led to the creation of the
3993 <tt>shlibs</tt> system, which is very simple in its design:
3994 any package which <em>provides</em> a shared library also
3995 provides information on the package dependencies required to
3996 ensure the presence of this library, and any package which
3997 <em>uses</em> a shared library uses this information to
3998 determine the dependencies it requires. The files which
3999 contain the mapping from shared libraries to the necessary
4000 dependency information are called <file>shlibs</file> files.
4004 Thus, when a package is built which contains any shared
4005 libraries, it must provide a <file>shlibs</file> file for other
4006 packages to use, and when a package is built which contains
4007 any shared libraries or compiled binaries, it must run
4008 <prgn>dpkg-shlibdeps</prgn> on these to determine the
4009 libraries used and hence the dependencies needed by this
4012 In the past, the shared libraries linked to were
4013 determined by calling <prgn>ldd</prgn>, but now
4014 <prgn>objdump</prgn> is used to do this. The only
4015 change this makes to package building is that
4016 <prgn>dpkg-shlibdeps</prgn> must also be run on shared
4017 libraries, whereas in the past this was unnecessary.
4018 The rest of this footnote explains the advantage that
4023 We say that a binary <tt>foo</tt> <em>directly</em> uses
4024 a library <tt>libbar</tt> if it is explicitly linked
4025 with that library (that is, it uses the flag
4026 <tt>-lbar</tt> during the linking stage). Other
4027 libraries that are needed by <tt>libbar</tt> are linked
4028 <em>indirectly</em> to <tt>foo</tt>, and the dynamic
4029 linker will load them automatically when it loads
4030 <tt>libbar</tt>. A package should depend on
4031 the libraries it directly uses, and the dependencies for
4032 those libraries should automatically pull in the other
4037 Unfortunately, the <prgn>ldd</prgn> program shows both
4038 the directly and indirectly used libraries, meaning that
4039 the dependencies determined included both direct and
4040 indirect dependencies. The use of <prgn>objdump</prgn>
4041 avoids this problem by determining only the directly
4046 A good example of where this helps is the following. We
4047 could update <tt>libimlib</tt> with a new version that
4048 supports a new graphics format called dgf (but retaining
4049 the same major version number). If we used the old
4050 <prgn>ldd</prgn> method, every package that uses
4051 <tt>libimlib</tt> would need to be recompiled so it
4052 would also depend on <tt>libdgf</tt> or it wouldn't run
4053 due to missing symbols. However with the new system,
4054 packages using <tt>libimlib</tt> can rely on
4055 <tt>libimlib</tt> itself having the dependency on
4056 <tt>libdgf</tt> and so they would not need rebuilding.
4062 In the following sections, we will first describe where the
4063 various <tt>shlibs</tt> files are to be found, then how to
4064 use <prgn>dpkg-shlibdeps</prgn>, and finally the
4065 <tt>shlibs</tt> file format and how to create them if your
4066 package contains a shared library.
4070 <heading>The <tt>shlibs</tt> files present on the system</heading>
4073 There are several places where <tt>shlibs</tt> files are
4074 found. The following list gives them in the order in which
4075 they are read by <prgn>dpkg-shlibdeps</prgn>. (The first
4076 one which gives the required information is used.)
4082 <p><file>debian/shlibs.local</file></p>
4084 This lists overrides for this package. Its use is
4085 described below (see <ref id="shlibslocal">).
4090 <p><file>/etc/dpkg/shlibs.override</file></p>
4092 This lists global overrides. This list is normally
4093 empty. It is maintained by the local system
4099 <p><file>DEBIAN/shlibs</file> files in the "build directory"</p>
4101 When packages are being built, any
4102 <file>debian/shlibs</file> files are copied into the
4103 control file area of the temporary build directory and
4104 given the name <file>shlibs</file>. These files give
4105 details of any shared libraries included in the
4108 An example may help here. Let us say that the
4109 source package <tt>foo</tt> generates two binary
4110 packages, <tt>libfoo2</tt> and
4111 <tt>foo-runtime</tt>. When building the binary
4112 packages, the two packages are created in the
4113 directories <file>debian/libfoo2</file> and
4114 <file>debian/foo-runtime</file> respectively.
4115 (<file>debian/tmp</file> could be used instead of one
4116 of these.) Since <tt>libfoo2</tt> provides the
4117 <tt>libfoo</tt> shared library, it will require a
4118 <tt>shlibs</tt> file, which will be installed in
4119 <file>debian/libfoo2/DEBIAN/shlibs</file>, eventually
4121 <file>/var/lib/dpkg/info/libfoo2.shlibs</file>. Then
4122 when <prgn>dpkg-shlibdeps</prgn> is run on the
4124 <file>debian/foo-runtime/usr/bin/foo-prog</file>, it
4126 <file>debian/libfoo2/DEBIAN/shlibs</file> file to
4127 determine whether <tt>foo-prog</tt>'s library
4128 dependencies are satisfied by any of the libraries
4129 provided by <tt>libfoo2</tt>. For this reason,
4130 <prgn>dpkg-shlibdeps</prgn> must only be run once
4131 all of the individual binary packages'
4132 <tt>shlibs</tt> files have been installed into the
4140 <p><file>/var/lib/dpkg/info/*.shlibs</file></p>
4142 These are the <file>shlibs</file> files corresponding to
4143 all of the packages installed on the system, and are
4144 maintained by the relevant package maintainers.
4149 <p><file>/etc/dpkg/shlibs.default</file></p>
4151 This file lists any shared libraries whose packages
4152 have failed to provide correct <file>shlibs</file> files.
4153 It was used when the <file>shlibs</file> setup was first
4154 introduced, but it is now normally empty. It is
4155 maintained by the <tt>dpkg</tt> maintainer.
4163 <heading>How to use <prgn>dpkg-shlibdeps</prgn> and the
4164 <file>shlibs</file> files</heading>
4167 Put a call to <prgn>dpkg-shlibdeps</prgn> into your
4168 <file>debian/rules</file> file. If your package contains only
4169 compiled binaries and libraries (but no scripts), you can
4170 use a command such as:
4171 <example compact="compact">
4172 dpkg-shlibdeps debian/tmp/usr/bin/* debian/tmp/usr/sbin/* \
4173 debian/tmp/usr/lib/*
4175 Otherwise, you will need to explicitly list the compiled
4176 binaries and libraries.<footnote>
4178 If you are using <tt>debhelper</tt>, the
4179 <prgn>dh_shlibdeps</prgn> program will do this work for
4180 you. It will also correctly handle multi-binary
4187 This command puts the dependency information into the
4188 <file>debian/substvars</file> file, which is then used by
4189 <prgn>dpkg-gencontrol</prgn>. You will need to place a
4190 <tt>${shlib:Depends}</tt> variable in the <tt>Depends</tt>
4191 field in the control file for this to work.
4195 If <prgn>dpkg-shlibdeps</prgn> doesn't complain, you're
4196 done. If it does complain you might need to create your own
4197 <file>debian/shlibs.local</file> file, as explained below (see
4198 <ref id="shlibslocal">).
4202 If you have multiple binary packages, you will need to call
4203 <prgn>dpkg-shlibdeps</prgn> on each one which contains
4204 compiled libraries or binaries. In such a case, you will
4205 need to use the <tt>-T</tt> option to the <tt>dpkg</tt>
4206 utilities to specify a different <file>substvars</file> file.
4207 For more details on this and other options, see <manref
4208 name="dpkg-shlibdeps" section="1">.
4213 <heading>The <file>shlibs</file> File Format</heading>
4216 Each <file>shlibs</file> file has the same format. Lines
4217 beginning with <tt>#</tt> are considered to be comments and
4218 are ignored. Each line is of the form:
4219 <example compact="compact">
4220 <var>library-name</var> <var>soname-version-number</var> <var>dependencies ...</var>
4225 We will explain this by reference to the example of the
4226 <tt>zlib1g</tt> package, which (at the time of writing)
4227 installs the shared library <file>/usr/lib/libz.so.1.1.3</file>.
4231 <var>library-name</var> is the name of the shared library,
4232 in this case <tt>libz</tt>. (This must match the name part
4233 of the soname, see below.)
4237 <var>soname-version-number</var> is the version part of the
4238 soname of the library. The soname is the thing that must
4239 exactly match for the library to be recognized by the
4240 dynamic linker, and is usually of the form
4241 <tt><var>name</var>.so.<var>major-version</var></tt>, in our
4242 example, <tt>libz.so.1</tt>.<footnote>
4244 This can be determined using the command
4245 <example compact="compact">
4246 objdump -p /usr/lib/libz.so.1.1.3 | grep SONAME
4250 The version part is the part which comes after
4251 <tt>.so.</tt>, so in our case, it is <tt>1</tt>.
4255 <var>dependencies</var> has the same syntax as a dependency
4256 field in a binary package control file. It should give
4257 details of which packages are required to satisfy a binary
4258 built against the version of the library contained in the
4259 package. See <ref id="depsyntax"> for details.
4263 In our example, if the first version of the <tt>zlib1g</tt>
4264 package which contained a minor number of at least
4265 <tt>1.3</tt> was <var>1:1.1.3-1</var>, then the
4266 <tt>shlibs</tt> entry for this library could say:
4267 <example compact="compact">
4268 libz 1 zlib1g (>= 1:1.1.3)
4270 The version-specific dependency is to avoid warnings from
4271 the dynamic linker about using older shared libraries with
4277 <heading>Providing a <file>shlibs</file> file</heading>
4280 If your package provides a shared library, you should create
4281 a <file>shlibs</file> file following the format described above.
4282 It is usual to call this file <file>debian/shlibs</file> (but if
4283 you have multiple binary packages, you might want to call it
4284 <file>debian/shlibs.<var>package</var></file> instead). Then
4285 let <file>debian/rules</file> install it in the control area:
4286 <example compact="compact">
4287 install -m644 debian/shlibs debian/tmp/DEBIAN
4289 or, in the case of a multi-binary package:
4290 <example compact="compact">
4291 install -m644 debian/shlibs.<var>package</var> debian/<var>package</var>/DEBIAN/shlibs
4293 An alternative way of doing this is to create the
4294 <file>shlibs</file> file in the control area directly from
4295 <file>debian/rules</file> without using a <file>debian/shlibs</file>
4296 file at all,<footnote>
4298 This is what <prgn>dh_makeshlibs</prgn> in the
4299 <tt>debhelper</tt> suite does.
4302 since the <file>debian/shlibs</file> file itself is ignored by
4303 <prgn>dpkg-shlibdeps</prgn>.
4307 As <prgn>dpkg-shlibdeps</prgn> reads the
4308 <file>DEBIAN/shlibs</file> files in all of the binary packages
4309 being built from this source package, all of the
4310 <file>DEBIAN/shlibs</file> files should be installed before
4311 <prgn>dpkg-shlibdeps</prgn> is called on any of the binary
4316 <sect1 id="shlibslocal">
4317 <heading>Writing the <file>debian/shlibs.local</file> file</heading>
4320 This file is intended only as a <em>temporary</em> fix if
4321 your binaries or libraries depend on a library whose package
4322 does not yet provide a correct <file>shlibs</file> file.
4326 We will assume that you are trying to package a binary
4327 <tt>foo</tt>. When you try running
4328 <prgn>dpkg-shlibdeps</prgn> you get the following error
4329 message (<tt>-O</tt> displays the dependency information on
4330 <tt>stdout</tt> instead of writing it to
4331 <tt>debian/substvars</tt>, and the lines have been wrapped
4332 for ease of reading):
4333 <example compact="compact">
4334 $ dpkg-shlibdeps -O debian/tmp/usr/bin/foo
4335 dpkg-shlibdeps: warning: unable to find dependency
4336 information for shared library libbar (soname 1,
4337 path /usr/lib/libbar.so.1, dependency field Depends)
4338 shlibs:Depends=libc6 (>= 2.2.2-2)
4340 You can then run <prgn>ldd</prgn> on the binary to find the
4341 full location of the library concerned:
4342 <example compact="compact">
4344 libbar.so.1 => /usr/lib/libbar.so.1 (0x4001e000)
4345 libc.so.6 => /lib/libc.so.6 (0x40032000)
4346 /lib/ld-linux.so.2 => /lib/ld-linux.so.2 (0x40000000)
4348 So the <prgn>foo</prgn> binary depends on the
4349 <prgn>libbar</prgn> shared library, but no package seems to
4350 provide a <file>*.shlibs</file> file handling
4351 <file>libbar.so.1</file> in <file>/var/lib/dpkg/info/</file>. Let's
4352 determine the package responsible:
4353 <example compact="compact">
4354 $ dpkg -S /usr/lib/libbar.so.1
4355 bar1: /usr/lib/libbar.so.1
4356 $ dpkg -s bar1 | grep Version
4359 This tells us that the <tt>bar1</tt> package, version 1.0-1,
4360 is the one we are using. Now we can file a bug against the
4361 <tt>bar1</tt> package and create our own
4362 <file>debian/shlibs.local</file> to locally fix the problem.
4363 Including the following line into your
4364 <file>debian/shlibs.local</file> file:
4365 <example compact="compact">
4366 libbar 1 bar1 (>= 1.0-1)
4368 should allow the package build to work.
4372 As soon as the maintainer of <tt>bar1</tt> provides a
4373 correct <file>shlibs</file> file, you should remove this line
4374 from your <file>debian/shlibs.local</file> file. (You should
4375 probably also then have a versioned <tt>Build-Depends</tt>
4376 on <tt>bar1</tt> to help ensure that others do not have the
4377 same problem building your package.)
4385 <chapt id="opersys"><heading>The Operating System</heading>
4388 <heading>Filesystem hierarchy</heading>
4392 <heading>Filesystem Structure</heading>
4395 The location of all installed files and directories must
4396 comply with the Filesystem Hierarchy Standard (FHS),
4397 version 2.1, except where doing so would violate other
4398 terms of Debian Policy. The version of this document
4399 referred here can be found in the <tt>debian-policy</tt>
4401 <url id="http://www.debian.org/doc/packaging-manuals/fhs/"
4402 name="FHS (Debian copy)"> alongside this manual (or, if
4403 you have the <package>debian-policy</package> installed,
4405 id="file:///usr/share/doc/debian-policy/fhs/" name="FHS
4406 (local copy)">). The
4407 latest version, which may be a more recent version, may
4409 <url id="http://www.pathname.com/fhs/" name="FHS (upstream)">.
4410 Specific questions about following the standard may be
4411 asked on the <tt>debian-devel</tt> mailing list, or
4412 referred to the FHS mailing list (see the
4413 <url id="http://www.pathname.com/fhs/" name="FHS web site"> for
4419 <heading>Site-specific programs</heading>
4422 As mandated by the FHS, packages must not place any
4423 files in <file>/usr/local</file>, either by putting them in
4424 the file system archive to be unpacked by <prgn>dpkg</prgn>
4425 or by manipulating them in their maintainer scripts.
4429 However, the package may create empty directories below
4430 <file>/usr/local</file> so that the system administrator knows
4431 where to place site-specific files. These directories
4432 should be removed on package removal if they are
4437 Note, that this applies only to directories <em>below</em>
4438 <file>/usr/local</file>, not <em>in</em> <file>/usr/local</file>.
4439 Packages must not create sub-directories in the directory
4440 <file>/usr/local</file> itself, except those listed in FHS,
4441 section 4.5. However, you may create directories below
4442 them as you wish. You must not remove any of the
4443 directories listed in 4.5, even if you created them.
4447 Since <file>/usr/local</file> can be mounted read-only from a
4448 remote server, these directories must be created and
4449 removed by the <prgn>postinst</prgn> and <prgn>prerm</prgn>
4450 maintainer scripts and not be included in the
4451 <file>.deb</file> archive. These scripts must not fail if
4452 either of these operations fail.
4456 For example, the <tt>emacsen-common</tt> package could
4457 contain something like
4458 <example compact="compact">
4459 if [ ! -e /usr/local/share/emacs ]
4461 if mkdir /usr/local/share/emacs 2>/dev/null
4463 chown root:staff /usr/local/share/emacs
4464 chmod 2775 /usr/local/share/emacs
4468 in its <prgn>postinst</prgn> script, and
4469 <example compact="compact">
4470 rmdir /usr/local/share/emacs/site-lisp 2>/dev/null || true
4471 rmdir /usr/local/share/emacs 2>/dev/null || true
4473 in the <prgn>prerm</prgn> script. (Note that this form is
4474 used to ensure that if the script is interrupted, the
4475 directory <file>/usr/local/share/emacs</file> will still be
4480 If you do create a directory in <file>/usr/local</file> for
4481 local additions to a package, you should ensure that
4482 settings in <file>/usr/local</file> take precedence over the
4483 equivalents in <file>/usr</file>.
4487 However, because <file>/usr/local</file> and its contents are
4488 for exclusive use of the local administrator, a package
4489 must not rely on the presence or absence of files or
4490 directories in <file>/usr/local</file> for normal operation.
4494 The <file>/usr/local</file> directory itself and all the
4495 subdirectories created by the package should (by default) have
4496 permissions 2775 (group-writable and set-group-id) and be
4497 owned by <tt>root.staff</tt>.
4502 <heading>The system-wide mail directory</heading>
4504 The system-wide mail directory is <file>/var/mail</file>. This
4505 directory is part of the base system and should not owned
4506 by any particular mail agents. The use of the old
4507 location <file>/var/spool/mail</file> is deprecated, even
4508 though the spool may still be physically located there.
4509 To maintain partial upgrade compatibility for systems
4510 which have <file>/var/spool/mail</file> as their physical mail
4511 spool, packages using <file>/var/mail</file> must depend on
4512 either <package>libc6</package> (>= 2.1.3-13), or on
4513 <package>base-files</package> (>= 2.2.0), or on later
4514 versions of either one of these packages.
4520 <heading>Users and groups</heading>
4523 <heading>Introduction</heading>
4525 The Debian system can be configured to use either plain or
4530 Some user ids (UIDs) and group ids (GIDs) are reserved
4531 globally for use by certain packages. Because some
4532 packages need to include files which are owned by these
4533 users or groups, or need the ids compiled into binaries,
4534 these ids must be used on any Debian system only for the
4535 purpose for which they are allocated. This is a serious
4536 restriction, and we should avoid getting in the way of
4537 local administration policies. In particular, many sites
4538 allocate users and/or local system groups starting at 100.
4542 Apart from this we should have dynamically allocated ids,
4543 which should by default be arranged in some sensible
4544 order, but the behavior should be configurable.
4548 Packages other than <tt>base-passwd</tt> must not modify
4549 <file>/etc/passwd</file>, <file>/etc/shadow</file>,
4550 <file>/etc/group</file> or <file>/etc/gshadow</file>.
4555 <heading>UID and GID classes</heading>
4557 The UID and GID numbers are divided into classes as
4563 Globally allocated by the Debian project, the same
4564 on every Debian system. These ids will appear in
4565 the <file>passwd</file> and <file>group</file> files of all
4566 Debian systems, new ids in this range being added
4567 automatically as the <tt>base-passwd</tt> package is
4572 Packages which need a single statically allocated
4573 uid or gid should use one of these; their
4574 maintainers should ask the <tt>base-passwd</tt>
4582 Dynamically allocated system users and groups.
4583 Packages which need a user or group, but can have
4584 this user or group allocated dynamically and
4585 differently on each system, should use <tt>adduser
4586 --system</tt> to create the group and/or user.
4587 <prgn>adduser</prgn> will check for the existence of
4588 the user or group, and if necessary choose an unused
4589 id based on the ranges specified in
4590 <file>adduser.conf</file>.
4594 <tag>1000-29999:</tag>
4597 Dynamically allocated user accounts. By default
4598 <prgn>adduser</prgn> will choose UIDs and GIDs for
4599 user accounts in this range, though
4600 <file>adduser.conf</file> may be used to modify this
4605 <tag>30000-59999:</tag>
4610 <tag>60000-64999:</tag>
4613 Globally allocated by the Debian project, but only
4614 created on demand. The ids are allocated centrally
4615 and statically, but the actual accounts are only
4616 created on users' systems on demand.
4620 These ids are for packages which are obscure or
4621 which require many statically-allocated ids. These
4622 packages should check for and create the accounts in
4623 <file>/etc/passwd</file> or <file>/etc/group</file> (using
4624 <prgn>adduser</prgn> if it has this facility) if
4625 necessary. Packages which are likely to require
4626 further allocations should have a "hole" left after
4627 them in the allocation, to give them room to
4632 <tag>65000-65533:</tag>
4640 User <tt>nobody</tt>. The corresponding gid refers
4641 to the group <tt>nogroup</tt>.
4648 <tt>(uid_t)(-1) == (gid_t)(-1)</tt> <em>must
4649 not</em> be used, because it is the error return
4658 <sect id="sysvinit">
4659 <heading>System run levels and <file>init.d</file> scripts</heading>
4661 <sect1 id="/etc/init.d">
4662 <heading>Introduction</heading>
4665 The <file>/etc/init.d</file> directory contains the scripts
4666 executed by <prgn>init</prgn> at boot time and when the
4667 init state (or "runlevel") is changed (see <manref
4668 name="init" section="8">).
4672 There are at least two different, yet functionally
4673 equivalent, ways of handling these scripts. For the sake
4674 of simplicity, this document describes only the symbolic
4675 link method. However, it must not be assumed by maintainer
4676 scripts that this method is being used, and any automated
4677 manipulation of the various runlevel behaviours by
4678 maintainer scripts must be performed using
4679 <prgn>update-rc.d</prgn> as described below and not by
4680 manually installing or removing symlinks. For information
4681 on the implementation details of the other method,
4682 implemented in the <tt>file-rc</tt> package, please refer
4683 to the documentation of that package.
4687 These scripts are referenced by symbolic links in the
4688 <file>/etc/rc<var>n</var>.d</file> directories. When changing
4689 runlevels, <prgn>init</prgn> looks in the directory
4690 <file>/etc/rc<var>n</var>.d</file> for the scripts it should
4691 execute, where <tt><var>n</var></tt> is the runlevel that
4692 is being changed to, or <tt>S</tt> for the boot-up
4697 The names of the links all have the form
4698 <file>S<var>mm</var><var>script</var></file> or
4699 <file>K<var>mm</var><var>script</var></file> where
4700 <var>mm</var> is a two-digit number and <var>script</var>
4701 is the name of the script (this should be the same as the
4702 name of the actual script in <file>/etc/init.d</file>).
4706 When <prgn>init</prgn> changes runlevel first the targets
4707 of the links whose names start with a <tt>K</tt> are
4708 executed, each with the single argument <tt>stop</tt>,
4709 followed by the scripts prefixed with an <tt>S</tt>, each
4710 with the single argument <tt>start</tt>. (The links are
4711 those in the <file>/etc/rc<var>n</var>.d</file> directory
4712 corresponding to the new runlevel.) The <tt>K</tt> links
4713 are responsible for killing services and the <tt>S</tt>
4714 link for starting services upon entering the runlevel.
4718 For example, if we are changing from runlevel 2 to
4719 runlevel 3, init will first execute all of the <tt>K</tt>
4720 prefixed scripts it finds in <file>/etc/rc3.d</file>, and then
4721 all of the <tt>S</tt> prefixed scripts in that directory.
4722 The links starting with <tt>K</tt> will cause the
4723 referred-to file to be executed with an argument of
4724 <tt>stop</tt>, and the <tt>S</tt> links with an argument
4729 The two-digit number <var>mm</var> is used to determine
4730 the order in which to run the scripts: low-numbered links
4731 have their scripts run first. For example, the
4732 <tt>K20</tt> scripts will be executed before the
4733 <tt>K30</tt> scripts. This is used when a certain service
4734 must be started before another. For example, the name
4735 server <prgn>bind</prgn> might need to be started before
4736 the news server <prgn>inn</prgn> so that <prgn>inn</prgn>
4737 can set up its access lists. In this case, the script
4738 that starts <prgn>bind</prgn> would have a lower number
4739 than the script that starts <prgn>inn</prgn> so that it
4741 <example compact="compact">
4748 The two runlevels 0 (halt) and 6 (reboot) are slightly
4749 different. In these runlevels, the links with an
4750 <tt>S</tt> prefix are still called after those with a
4751 <tt>K</tt> prefix, but they too are called with the single
4752 argument <tt>stop</tt>.
4756 Also, if the script name ends <tt>.sh</tt>, the script
4757 will be sourced in runlevel <tt>S</tt> rather that being
4758 run in a forked subprocess, but will be explicitly run by
4759 <prgn>sh</prgn> in all other runlevels.
4764 <heading>Writing the scripts</heading>
4767 Packages that include daemons for system services should
4768 place scripts in <file>/etc/init.d</file> to start or stop
4769 services at boot time or during a change of runlevel.
4770 These scripts should be named
4771 <file>/etc/init.d/<var>package</var></file>, and they should
4772 accept one argument, saying what to do:
4775 <tag><tt>start</tt></tag>
4776 <item><p>start the service,</p></item>
4778 <tag><tt>stop</tt></tag>
4779 <item><p>stop the service,</p></item>
4781 <tag><tt>restart</tt></tag>
4782 <item><p>stop and restart the service if it's already
4783 already running, otherwise start the service</p></item>
4785 <tag><tt>reload</tt></tag>
4786 <item><p>cause the configuration of the service to be
4787 reloaded without actually stopping and restarting
4788 the service,</p></item>
4790 <tag><tt>force-reload</tt></tag>
4791 <item><p>cause the configuration to be reloaded if the
4792 service supports this, otherwise restart the
4796 The <tt>start</tt>, <tt>stop</tt>, <tt>restart</tt>, and
4797 <tt>force-reload</tt> options should be supported by all
4798 scripts in <file>/etc/init.d</file>, the <tt>reload</tt>
4799 option is optional.</p>
4802 The <file>init.d</file> scripts should ensure that they will
4803 behave sensibly if invoked with <tt>start</tt> when the
4804 service is already running, or with <tt>stop</tt> when it
4805 isn't, and that they don't kill unfortunately-named user
4806 processes. The best way to achieve this is usually to use
4807 <prgn>start-stop-daemon</prgn>.</p>
4810 If a service reloads its configuration automatically (as
4811 in the case of <prgn>cron</prgn>, for example), the
4812 <tt>reload</tt> option of the <file>init.d</file> script
4813 should behave as if the configuration has been reloaded
4817 The <file>/etc/init.d</file> scripts must be treated as
4818 configuration files, either (if they are present in the
4819 package, that is, in the .deb file) by marking them as
4820 <tt>conffile</tt>s, or, (if they do not exist in the .deb)
4821 by managing them correctly in the maintainer scripts (see
4822 <ref id="config-files">). This is important since we want
4823 to give the local system administrator the chance to adapt
4824 the scripts to the local system, e.g., to disable a
4825 service without de-installing the package, or to specify
4826 some special command line options when starting a service,
4827 while making sure her changes aren't lost during the next
4832 These scripts should not fail obscurely when the
4833 configuration files remain but the package has been
4834 removed, as configuration files remain on the system after
4835 the package has been removed. Only when <prgn>dpkg</prgn>
4836 is executed with the <tt>--purge</tt> option will
4837 configuration files be removed. In particular, as the
4838 <file>/etc/init.d/<var>package</var></file> script itself is
4839 usually a <tt>conffile</tt>, it will remain on the system
4840 if the package is removed but not purged. Therefore, you
4841 should include a <tt>test</tt> statement at the top of the
4843 <example compact="compact">
4844 test -f <var>program-executed-later-in-script</var> || exit 0
4849 Often there are some variables in the <file>init.d</file>
4850 scripts whose values control the behaviour of the scripts,
4851 and which a system administrator is likely to want to
4852 change. As the scripts themselves are frequently
4853 <tt>conffile</tt>s, modifying them requires that the
4854 administrator merge in their changes each time the package
4855 is upgraded and the <tt>conffile</tt> changes. To ease
4856 the burden on the system administrator, such configurable
4857 values should not be placed directly in the script.
4858 Instead, they should be placed in a file in
4859 <file>/etc/default</file>, which typically will have the same
4860 base name as the <file>init.d</file> script. This extra file
4861 should be sourced by the script when the script runs. It
4862 must contain only variable settings and comments in POSIX
4863 <prgn>sh</prgn> format. It may either be a
4864 <tt>conffile</tt> or a configuration file maintained by
4865 the package maintainer scripts. See <ref id="config-files">
4870 To ensure that vital configurable values are always
4871 available, the <file>init.d</file> script should set default
4872 values for each of the shell variables it uses, either
4873 before sourcing the <file>/etc/default/</file> file or
4874 afterwards using something like the <tt>:
4875 ${VAR:=default}</tt> syntax. Also, the <file>init.d</file>
4876 script must behave sensibly and not fail if the
4877 <file>/etc/default</file> file is deleted.
4882 <heading>Interfacing with the initscript system</heading>
4885 Maintainers should use the abstraction layer provided by
4886 the <prgn>update-rc.d</prgn> and <prgn>invoke-rc.d</prgn>
4887 programs to deal with initscripts in their packages'
4888 scripts such as <prgn>postinst</prgn>, <prgn>prerm</prgn>
4889 and <prgn>postrm</prgn>.
4892 Directly managing the /etc/rc?.d links and directly
4893 invoking the <file>/etc/init.d/</file> initscripts should
4894 be done only by packages providing the initscript
4895 subsystem (such as <prgn>sysvinit</prgn> and
4896 <prgn>file-rc</prgn>).
4901 <heading>Managing the links</heading>
4904 The program <prgn>update-rc.d</prgn> is provided for
4905 package maintainers to arrange for the proper creation and
4906 removal of <file>/etc/rc<var>n</var>.d</file> symbolic links,
4907 or their functional equivalent if another method is being
4908 used. This may be used by maintainers in their packages'
4909 <prgn>postinst</prgn> and <prgn>postrm</prgn> scripts.</p>
4912 You must not include any <file>/etc/rc<var>n</var>.d</file>
4913 symbolic links in the actual archive or manually create or
4914 remove the symbolic links in maintainer scripts; you must
4915 use the <prgn>update-rc.d</prgn> program instead. (The
4916 former will fail if an alternative method of maintaining
4917 runlevel information is being used.) You must not include
4918 the <file>/etc/rc<var>n</var>.d</file> directories themselves
4919 in the archive either. (Only the <tt>sysvinit</tt>
4924 By default <prgn>update-rc.d</prgn> will start services in
4925 each of the multi-user state runlevels (2, 3, 4, and 5)
4926 and stop them in the halt runlevel (0), the single-user
4927 runlevel (1) and the reboot runlevel (6). The system
4928 administrator will have the opportunity to customize
4929 runlevels by simply adding, moving, or removing the
4930 symbolic links in <file>/etc/rc<var>n</var>.d</file> if
4931 symbolic links are being used, or by modifying
4932 <file>/etc/runlevel.conf</file> if the <tt>file-rc</tt> method
4937 To get the default behavior for your package, put in your
4938 <prgn>postinst</prgn> script
4939 <example compact="compact">
4940 update-rc.d <var>package</var> defaults
4942 and in your <prgn>postrm</prgn>
4943 <example compact="compact">
4944 if [ "$1" = purge ]; then
4945 update-rc.d <var>package</var> remove
4947 </example>. Note that if your package changes runlevels
4948 or priority, you may have to remove and recreate the links,
4949 since otherwise the old links may persist. Refer to the
4950 documentation of <prgn>update-rc.d</prgn></p>
4953 This will use a default sequence number of 20. If it does
4954 not matter when or in which order the <file>init.d</file>
4955 script is run, use this default. If it does, then you
4956 should talk to the maintainer of the <prgn>sysvinit</prgn>
4957 package or post to <tt>debian-devel</tt>, and they will
4958 help you choose a number.
4962 For more information about using <tt>update-rc.d</tt>,
4963 please consult its manpage <manref name="update-rc.d"
4969 <heading>Running initscripts</heading>
4971 The program <prgn>invoke-rc.d</prgn> is provided to make
4972 it easier for package maintainers to properly invoke an
4973 initscript, obeying runlevel and other locally-defined
4974 constraints that might limit a package's right to start,
4975 stop and otherwise manage services. This program may be
4976 used by maintainers in their packages' scripts.
4979 The use of <prgn>invoke-rc.d</prgn> to invoke the
4980 <file>/etc/init.d/*</file> initscripts is strongly
4981 recommended<footnote>
4983 In the future, the use of invoke-rc.d to invoke
4984 initscripts shall be made mandatory. Maintainers are
4985 advised to switch to invoke-rc.d as soon as
4987 </footnote>, instead of calling them directly.
4991 By default, <prgn>invoke-rc.d</prgn> will pass any
4992 action requests (start, stop, reload, restart...) to the
4993 <file>/etc/init.d</file> script, filtering out requests
4994 to start or restart a service out of its intended
4998 Most packages will simply need to change:
4999 <example compact="compact">/etc/init.d/<package>
5000 <action></example> in their <prgn>postinst</prgn>
5001 and <prgn>prerm</prgn> scripts to:
5002 <example compact="compact">
5003 if [ -x /usr/sbin/invoke-rc.d ] ; then
5004 invoke-rc.d <var>package</var> <action>
5006 /etc/init.d/<var>package</var> <action>
5010 A package should register its initscript services using
5011 <prgn>update-rc.d</prgn> before it tries to invoke them
5012 using <prgn>invoke-rc.d</prgn>. Invocation of
5013 unregistered services may fail.
5016 For more information about using
5017 <prgn>invoke-rc.d</prgn>, please consult its manpage
5018 <manref name="invoke-rc.d" section="8">.
5025 <heading>Boot-time initialization</heading>
5028 There used to be another directory, <file>/etc/rc.boot</file>,
5029 which contained scripts which were run once per machine
5030 boot. This has been deprecated in favour of links from
5031 <file>/etc/rcS.d</file> to files in <file>/etc/init.d</file> as
5032 described in <ref id="/etc/init.d">. Packages must not
5033 place files in <file>/etc/rc.boot</file>.</p>
5036 <heading>Example</heading>
5039 The <prgn>bind</prgn> DNS (nameserver) package wants to
5040 make sure that the nameserver is running in multiuser
5041 runlevels, and is properly shut down with the system. It
5042 puts a script in <file>/etc/init.d</file>, naming the script
5043 appropriately <tt>bind</tt>. As you can see, the script
5044 interprets the argument <tt>reload</tt> to send the
5045 nameserver a <tt>HUP</tt> signal (causing it to reload its
5046 configuration); this way the system administrator can say
5047 <tt>/etc/init.d/bind reload</tt> to reload the name
5048 server. The script has one configurable value, which can
5049 be used to pass parameters to the named program at
5050 startup; this value is read from
5051 <file>/etc/default/bind</file> (see below).
5055 <example compact="compact">
5058 # Original version by Robert Leslie
5059 # <rob@mars.org>, edited by iwj and cs
5061 test -x /usr/sbin/named || exit 0
5063 # Source defaults file.
5065 if [ -f /etc/default/bind ]; then
5072 echo -n "Starting domain name service: named"
5073 start-stop-daemon --start --quiet --exec /usr/sbin/named \
5078 echo -n "Stopping domain name service: named"
5079 start-stop-daemon --stop --quiet \
5080 --pidfile /var/run/named.pid --exec /usr/sbin/named
5084 echo -n "Restarting domain name service: named"
5085 start-stop-daemon --stop --quiet \
5086 --pidfile /var/run/named.pid --exec /usr/sbin/named
5087 start-stop-daemon --start --verbose --exec /usr/sbin/named \
5091 force-reload|reload)
5092 echo -n "Reloading configuration of domain name service: named"
5093 start-stop-daemon --stop --signal 1 --quiet \
5094 --pidfile /var/run/named.pid --exec /usr/sbin/named
5098 echo "Usage: /etc/init.d/bind " \
5099 " {start|stop|restart|reload|force-reload}" >&2
5109 Complementing the above init script is a configuration
5110 file <file>/etc/default/bind</file>, which contains
5111 configurable parameters used by the script. This would be
5112 created by the <prgn>postinst</prgn> script if it was not
5113 already present, and removed on purge by the
5114 <prgn>postrm</prgn> script.
5115 <example compact="compact">
5116 # Specified parameters to pass to named. See named(8).
5117 # You may uncomment the following line, and edit to taste.
5123 Another example on which you can base your
5124 <file>/etc/init.d</file> scripts is found in
5125 <file>/etc/init.d/skeleton</file>.
5129 If this package is happy with the default setup from
5130 <prgn>update-rc.d</prgn>, namely an ordering number of 20
5131 and having named running in all runlevels, it can say in
5132 its <prgn>postinst</prgn>:
5133 <example compact="compact">
5134 update-rc.d bind defaults >/dev/null
5136 And in its <prgn>postrm</prgn>, to remove the links when the
5138 <example compact="compact">
5139 if [ "$1" = purge ]; then
5140 update-rc.d bind remove >/dev/null
5148 <heading>Console messages from <file>init.d</file> scripts</heading>
5151 This section describes the formats to be used for messages
5152 written to standard output by the <file>/etc/init.d</file>
5153 scripts. The intent is to improve the consistency of
5154 Debian's startup and shutdown look and feel. For this
5155 reason, please look very carefully at the details. We want
5156 the messages to have the same format in terms of wording,
5157 spaces, punctuation and case of letters.
5161 Here is a list of overall rules that you should use when you
5162 create output messages. They can be useful if you have a
5163 non-standard message that is not covered specifically in the
5171 Every message should fit in one line (fewer than 80
5172 characters), start with a capital letter and end with
5173 a period (<tt>.</tt>) and line feed (<tt>"\n"</tt>).
5179 If you want to express that the computer is working on
5180 something (that is, performing a specific task, not
5181 starting or stopping a program), we use an "ellipsis"
5182 (three dots: <tt>...</tt>). Note that we don't insert
5183 spaces before or after the dots. If the task has been
5184 completed we write <tt>done.</tt> and a line feed.
5190 Design your messages as if the computer is telling you
5191 what he is doing (let him be polite :-), but don't
5192 mention "him" directly. For example, if you think of
5194 <example compact="compact">
5195 I'm starting network daemons: nfsd mountd.
5198 <example compact="compact">
5199 Starting network daemons: nfsd mountd.
5207 There are standard message formats for the following
5208 situations. They should be used by the <tt>init.d</tt>
5215 <p>When daemons are started</p>
5218 If your script starts one or more daemons, the output
5219 should look like this (a single line, no leading
5221 <example compact="compact">
5222 Starting <var>description</var>: <var>daemon-1</var> ... <var>daemon-n</var>.
5224 The <var>description</var> should describe the
5225 subsystem the daemon or set of daemons are part of,
5226 while <var>daemon-1</var> up to <var>daemon-n</var>
5227 denote each daemon's name (typically the file name of
5232 For example, the output of <file>/etc/init.d/lpd</file>
5234 <example compact="compact">
5235 Starting printer spooler: lpd.
5240 This can be achieved by saying
5241 <example compact="compact">
5242 echo -n "Starting printer spooler: lpd"
5243 start-stop-daemon --start --quiet --exec /usr/sbin/lpd
5246 in the script. If you have more than one daemon to
5247 start, you should do the following:
5248 <example compact="compact">
5249 echo -n "Starting remote file system services:"
5250 echo -n " nfsd"; start-stop-daemon --start --quiet nfsd
5251 echo -n " mountd"; start-stop-daemon --start --quiet mountd
5252 echo -n " ugidd"; start-stop-daemon --start --quiet ugidd
5255 This makes it possible for the user to see what takes
5256 so long and when the final daemon has been started.
5257 You should be careful where to put spaces: in the
5258 example above the system administrator can easily
5259 comment out a line if he don't wants to start a
5260 specific daemon, while the displayed message still
5266 <p>When a system parameter is being set</p>
5269 If you have to set up different system parameters
5270 during the system boot, you should use this format:
5271 <example compact="compact">
5272 Setting <var>parameter</var> to "<var>value</var>".
5277 You can use a statement such as the following to get
5279 <example compact="compact">
5280 echo "Setting DNS domainname to \"$domainname\"."
5285 Note that the same symbol (<tt>"</tt>) is used for the left
5286 and right quotation marks. A grave accent (<tt>`</tt>) is
5287 not a quote character; neither is an apostrophe
5293 <p>When a daemon is stopped or restarted</p>
5296 When you stop or restart a daemon, you should issue a
5297 message identical to the startup message, except that
5298 <tt>Starting</tt> is replaced with <tt>Stopping</tt>
5299 or <tt>Restarting</tt> respectively.
5303 For example, stopping the printer daemon will like
5305 <example compact="compact">
5306 Stopping printer spooler: lpd.
5312 <p>When something is executed</p>
5315 There are several examples where you have to run a
5316 program at system startup or shutdown to perform a
5317 specific task, for example, setting the system's clock
5318 using <prgn>netdate</prgn> or killing all processes
5319 when the system shuts down. Your message should look
5321 <example compact="compact">
5322 Doing something very useful...done.
5324 You should print the <tt>done.</tt> immediately after
5325 the job has been completed, so that the user is
5326 informed why she has to wait. You can get this
5328 <example compact="compact">
5329 echo -n "Doing something very useful..."
5338 <p>When the configuration is reloaded</p>
5341 When a daemon is forced to reload its configuration
5342 files you should use the following format:
5343 <example compact="compact">
5344 Reloading <var>description</var> configuration...done.
5346 where <var>description</var> is the same as in the
5347 daemon starting message.
5355 <heading>Cron jobs</heading>
5358 Packages must not modify the configuration file
5359 <file>/etc/crontab</file>, and they must not modify the files in
5360 <file>/var/spool/cron/crontabs</file>.</p>
5363 If a package wants to install a job that has to be executed
5364 via cron, it should place a file with the name of the
5365 package in one or more of the following directories:
5366 <example compact="compact">
5371 As these directory names imply, the files within them are
5372 executed on a daily, weekly, or monthly basis,
5373 respectively. The exact times are listed in
5374 <file>/etc/crontab</file>.</p>
5377 All files installed in any of these directories must be
5378 scripts (e.g., shell scripts or Perl scripts) so that they
5379 can easily be modified by the local system administrator.
5380 In addition, they should be treated as configuration
5385 If a certain job has to be executed more frequently than
5386 daily, the package should install a file
5387 <file>/etc/cron.d/<var>package</var></file>. This file uses the
5388 same syntax as <file>/etc/crontab</file> and is processed by
5389 <prgn>cron</prgn> automatically. The file must also be
5390 treated as a configuration file. (Note that entries in the
5391 <file>/etc/cron.d</file> directory are not handled by
5392 <prgn>anacron</prgn>. Thus, you should only use this
5393 directory for jobs which may be skipped if the system is not
5397 The scripts or crontab entries in these directories should
5398 check if all necessary programs are installed before they
5399 try to execute them. Otherwise, problems will arise when a
5400 package was removed but not purged since configuration files
5401 are kept on the system in this situation.</p>
5405 <heading>Menus</heading>
5408 Menu entries should follow the current menu policy found in
5409 the <tt>menu-policy</tt> files in the <tt>debian-policy</tt>
5410 package. It may also be found on the Debian FTP site
5411 <ftpsite>ftp.debian.org</ftpsite> as the file
5412 <ftppath>/debian/doc/package-developer/menu-policy.txt.gz</ftppath>,
5413 or in the equivalent location on your local mirror.
5417 The Debian <tt>menu</tt> package provides a standard
5418 interface between packages providing applications and
5419 documents, and <em>menu programs</em> (either X window
5420 managers or text-based menu programs such as
5421 <prgn>pdmenu</prgn>).
5425 All packages that provide applications that need not be
5426 passed any special command line arguments for normal
5427 operation should register a menu entry for those
5428 applications, so that users of the <tt>menu</tt> package
5429 will automatically get menu entries in their window
5430 managers, as well in shells like <tt>pdmenu</tt>.</p>
5433 Please also refer to the <em>Debian Menu System</em>
5434 documentation that comes with the <tt>menu</tt> package for
5435 information about how to register your applications and web
5441 <heading>Multimedia handlers</heading>
5444 Packages which provide the ability to view/show/play,
5445 compose, edit or print MIME types should register themselves
5446 as such following the current MIME support policy found in
5447 the <tt>mime-policy</tt> files in the <tt>debian-policy</tt>
5448 package. It may also be found on the Debian FTP site
5449 <ftpsite>ftp.debian.org</ftpsite> as the file
5450 <ftppath>/debian/doc/package-developer/mime-policy.txt.gz</ftppath>,
5451 or in the equivalent location on your local mirror.
5455 MIME (Multipurpose Internet Mail Extensions, RFCs 2045-2049)
5456 is a mechanism for encoding files and data streams and
5457 providing meta-information about them, in particular their
5458 type (e.g. audio or video) and format (e.g. PNG, HTML,
5463 Registration of MIME type handlers allows programs like mail
5464 user agents and web browsers to to invoke these handlers to
5465 view, edit or display MIME types they don't support
5471 <heading>Keyboard configuration</heading>
5474 To achieve a consistent keyboard configuration so that all
5475 applications interpret a keyboard event the same way, all
5476 programs in the Debian distribution must be configured to
5477 comply with the following guidelines.
5481 The following keys must have the specified interpretations:
5484 <tag><tt><--</tt></tag>
5485 <item><p>delete the character to the left of the cursor</p></item>
5487 <tag><tt>Delete</tt></tag>
5488 <item><p>delete the character to the right of the cursor</p></item>
5490 <tag><tt>Control+H</tt></tag>
5491 <item><p>emacs: the help prefix</p></item>
5494 The interpretation of any keyboard events should be
5495 independent of the terminal that is used, be it a virtual
5496 console, an X terminal emulator, an rlogin/telnet session,
5501 The following list explains how the different programs
5502 should be set up to achieve this:
5507 <item><p><tt><--</tt> generates <tt>KB_BackSpace</tt>
5510 <item><p><tt>Delete</tt> generates <tt>KB_Delete</tt> in
5515 X translations are set up to make
5516 <tt>KB_Backspace</tt> generate ASCII DEL, and to make
5517 <tt>KB_Delete</tt> generate <tt>ESC [ 3 ~</tt> (this
5518 is the vt220 escape code for the "delete character"
5519 key). This must be done by loading the X resources
5520 using <prgn>xrdb</prgn> on all local X displays, not
5521 using the application defaults, so that the
5522 translation resources used correspond to the
5523 <prgn>xmodmap</prgn> settings.</p></item>
5527 The Linux console is configured to make
5528 <tt><--</tt> generate DEL, and <tt>Delete</tt>
5529 generate <tt>ESC [ 3 ~</tt>.</p></item>
5533 X applications are configured so that <tt><</tt>
5534 deletes left, and <tt>Delete</tt> deletes right. Motif
5535 applications already work like this.</p></item>
5537 <item><p>Terminals should have <tt>stty erase ^?</tt> .</p></item>
5541 The <tt>xterm</tt> terminfo entry should have <tt>ESC
5542 [ 3 ~</tt> for <tt>kdch1</tt>, just as for
5543 <tt>TERM=linux</tt> and <tt>TERM=vt220</tt>.</p></item>
5547 Emacs is programmed to map <tt>KB_Backspace</tt> or
5548 the <tt>stty erase</tt> character to
5549 <tt>delete-backward-char</tt>, and <tt>KB_Delete</tt>
5550 or <tt>kdch1</tt> to <tt>delete-forward-char</tt>, and
5551 <tt>^H</tt> to <tt>help</tt> as always.</p></item>
5555 Other applications use the <tt>stty erase</tt>
5556 character and <tt>kdch1</tt> for the two delete keys,
5557 with ASCII DEL being "delete previous character" and
5558 <tt>kdch1</tt> being "delete character under
5565 This will solve the problem except for the following
5573 Some terminals have a <tt><--</tt> key that cannot
5574 be made to produce anything except <tt>^H</tt>. On
5575 these terminals Emacs help will be unavailable on
5576 <tt>^H</tt> (assuming that the <tt>stty erase</tt>
5577 character takes precedence in Emacs, and has been set
5578 correctly). <tt>M-x help</tt> or <tt>F1</tt> (if
5579 available) can be used instead.</p></item>
5583 Some operating systems use <tt>^H</tt> for <tt>stty
5584 erase</tt>. However, modern telnet versions and all
5585 rlogin versions propagate <tt>stty</tt> settings, and
5586 almost all UNIX versions honour <tt>stty erase</tt>.
5587 Where the <tt>stty</tt> settings are not propagated
5588 correctly, things can be made to work by using
5589 <tt>stty</tt> manually.</p></item>
5593 Some systems (including previous Debian versions) use
5594 <prgn>xmodmap</prgn> to arrange for both
5595 <tt><--</tt> and <tt>Delete</tt> to generate
5596 <tt>KB_Delete</tt>. We can change the behavior of
5597 their X clients using the same X resources that we use
5598 to do it for our own clients, or configure our clients
5599 using their resources when things are the other way
5600 around. On displays configured like this
5601 <tt>Delete</tt> will not work, but <tt><--</tt>
5606 Some operating systems have different <tt>kdch1</tt>
5607 settings in their <tt>terminfo</tt> database for
5608 <tt>xterm</tt> and others. On these systems the
5609 <tt>Delete</tt> key will not work correctly when you
5610 log in from a system conforming to our policy, but
5611 <tt><--</tt> will.</p></item>
5617 <heading>Environment variables</heading>
5620 A program must not depend on environment variables to get
5621 reasonable defaults. (That's because these environment
5622 variables would have to be set in a system-wide
5623 configuration file like <file>/etc/profile</file>, which is not
5624 supported by all shells.)</p>
5627 If a program usually depends on environment variables for its
5628 configuration, the program should be changed to fall back to
5629 a reasonable default configuration if these environment
5630 variables are not present. If this cannot be done easily
5631 (e.g., if the source code of a non-free program is not
5632 available), the program must be replaced by a small
5633 "wrapper" shell script which sets the environment variables
5634 if they are not already defined, and calls the original program.</p>
5637 Here is an example of a wrapper script for this purpose:
5639 <example compact="compact">
5641 BAR=${BAR:-/var/lib/fubar}
5643 exec /usr/lib/foo/foo "$@"
5648 Furthermore, as <file>/etc/profile</file> is a configuration
5649 file of the <prgn>base-files</prgn> package, other packages must not
5650 put any environment variables or other commands into that
5656 <heading>Files</heading>
5659 <heading>Binaries</heading>
5662 Two different packages must not install programs with
5663 different functionality but with the same filenames. (The
5664 case of two programs having the same functionality but
5665 different implementations is handled via "alternatives" or
5666 the "Conflicts" mechanism. See <ref id="maintscripts"> and
5667 <ref id="conflicts"> respectively.) If this case happens,
5668 one of the programs must be renamed. The maintainers should
5669 report this to the <tt>debian-devel</tt> mailing list and
5670 try to find a consensus about which program will have to be
5671 renamed. If a consensus cannot be reached, <em>both</em>
5672 programs must be renamed.
5676 By default, when a package is being built, any binaries
5677 created should include debugging information, as well as
5678 being compiled with optimization. You should also turn on
5679 as many reasonable compilation warnings as possible; this
5680 makes life easier for porters, who can then look at build
5681 logs for possible problems. For the C programming language,
5682 this means the following compilation parameters should be
5684 <example compact="compact">
5686 CFLAGS = -O2 -g -Wall # sane warning options vary between programs
5688 install -s # (or use strip on the files in debian/tmp)
5693 Note that by default all installed binaries should be stripped,
5694 either by using the <tt>-s</tt> flag to
5695 <prgn>install</prgn>, or by calling <prgn>strip</prgn> on
5696 the binaries after they have been copied into
5697 <file>debian/tmp</file> but before the tree is made into a
5701 Although binaries in the build tree should be compiled with
5702 debugging information by default, it can often be difficult
5703 to debug programs if they are also subjected to compiler
5704 optimization. For this reason, it is recommended to support
5705 the standardized environment
5706 variable <tt>DEB_BUILD_OPTIONS</tt>. This variable can
5707 contain several flags to change how a package is compiled
5715 The presence of this string means that the package
5716 should be complied with a minimum of optimization.
5717 For C programs, it is best to add <tt>-O0</tt>
5718 to <tt>CFLAGS</tt> (although this is usually the
5719 default). Some programs might fail to build or run at
5720 this level of optimization; it may be necessary to
5721 use <tt>-O1</tt>, for example.
5727 This string means that the debugging symbols should
5728 not be stripped from the binary during installation,
5729 so that debugging information may be included in the package.
5735 The following makefile snippet is an example of how one may
5736 implement the build options; you will probably have to
5737 massage this example in order to make it work for your
5739 <example compact="compact">
5742 INSTALL_FILE = $(INSTALL) -p -o root -g root -m 644
5743 INSTALL_PROGRAM = $(INSTALL) -p -o root -g root -m 755
5744 INSTALL_SCRIPT = $(INSTALL) -p -o root -g root -m 755
5745 INSTALL_DIR = $(INSTALL) -p -d -o root -g root -m 755
5747 ifneq (,$(findstring noopt,$(DEB_BUILD_OPTIONS)))
5752 ifeq (,$(findstring nostrip,$(DEB_BUILD_OPTIONS)))
5753 INSTALL_PROGRAM += -s
5759 It is up to the package maintainer to decide what
5760 compilation options are best for the package. Certain
5761 binaries (such as computationally-intensive programs) will
5762 function better with certain flags (<tt>-O3</tt>, for
5763 example); feel free to use them. Please use good judgment
5764 here. Don't use flags for the sake of it; only use them
5765 if there is good reason to do so. Feel free to override
5766 the upstream author's ideas about which compilation
5767 options are best: they are often inappropriate for our
5773 <sect id="libraries">
5774 <heading>Libraries</heading>
5777 The shared version of a library must be compiled with
5778 <tt>-fPIC</tt>, and the static version must not be. In other
5779 words, each source unit (<tt>*.c</tt>, for example, for C files)
5780 will need to be compiled twice.
5785 You must specify the gcc option <tt>-D_REENTRANT</tt>
5786 when building a library (either static or shared) to make
5787 the library compatible with LinuxThreads.
5791 All installed shared libraries should be stripped with
5792 <example compact="compact">
5793 strip --strip-unneeded <var>your-lib</var>
5795 (The option <tt>--strip-unneeded</tt> makes
5796 <prgn>strip</prgn> remove only the symbols which aren't
5797 needed for relocation processing.) Shared libraries can
5798 function perfectly well when stripped, since the symbols for
5799 dynamic linking are in a separate part of the ELF object
5802 You might also want to use the options
5803 <tt>--remove-section=.comment</tt> and
5804 <tt>--remove-section=.note</tt> on both shared libraries
5805 and executables, and <tt>--strip-debug</tt> on static
5812 Note that under some circumstances it may be useful to
5813 install a shared library unstripped, for example when
5814 building a separate package to support debugging.
5818 Shared object files (often <file>.so</file> files) that are not
5819 public libraries, that is, they are not meant to be linked
5820 to by third party executables (binaries of other packages),
5821 should be installed in subdirectories of the
5822 <file>/usr/lib</file> directory. Such files are exempt from the
5823 rules that govern ordinary shared libraries, except that
5824 they must not be installed executable and should be
5827 A common example are the so-called "plug-ins",
5828 internal shared objects that are dynamically loaded by
5829 programs using <manref name="dlopen" section="3">.
5835 Packages containing shared libraries that may be linked to
5836 by other packages' binaries, but which for some
5837 <em>compelling</em> reason can not be installed in
5838 <file>/usr/lib</file> directory, may install the shared library
5839 files in subdirectories of the <file>/usr/lib</file> directory,
5840 in which case they should arrange to add that directory in
5841 <file>/etc/ld.so.conf</file> in the package's post-installation
5842 script, and remove it in the package's post-removal script.
5846 An ever increasing number of packages are using
5847 <prgn>libtool</prgn> to do their linking. The latest GNU
5848 libtools (>= 1.3a) can take advantage of the metadata in the
5849 installed <prgn>libtool</prgn> archive files (<file>*.la</file>
5850 files). The main advantage of <prgn>libtool</prgn>'s
5851 <file>.la</file> files is that it allows <prgn>libtool</prgn> to
5852 store and subsequently access metadata with respect to the
5853 libraries it builds. <prgn>libtool</prgn> will search for
5854 those files, which contain a lot of useful information about
5855 a library (such as library dependency information for static
5856 linking). Also, they're <em>essential</em> for programs
5857 using <tt>libltdl</tt>.<footnote>
5859 Although <prgn>libtool</prgn> is fully capable of
5860 linking against shared libraries which don't have
5861 <tt>.la</tt> files, as it is a mere shell script it can
5862 add considerably to the build time of a
5863 <prgn>libtool</prgn>-using package if that shell script
5864 has to derive all this information from first principles
5865 for each library every time it is linked. With the
5866 advent of <prgn>libtool</prgn> version 1.4 (and to a
5867 lesser extent <prgn>libtool</prgn> version 1.3), the
5868 <file>.la</file> files also store information about
5869 inter-library dependencies which cannot necessarily be
5870 derived after the <file>.la</file> file is deleted.
5876 Packages that use <prgn>libtool</prgn> to create shared
5877 libraries should include the <file>.la</file> files in the
5878 <tt>-dev</tt> package, unless the package relies on
5879 <tt>libtool</tt>'s <tt>libltdl</tt> library, in which case
5880 the <tt>.la</tt> files must go in the run-time library
5885 You must make sure that you use only released versions of
5886 shared libraries to build your packages; otherwise other
5887 users will not be able to run your binaries
5888 properly. Producing source packages that depend on
5889 unreleased compilers is also usually a bad
5896 <heading>Shared libraries</heading>
5898 This section has moved to <ref id="sharedlibs">.
5904 <heading>Scripts</heading>
5907 All command scripts, including the package maintainer
5908 scripts inside the package and used by <prgn>dpkg</prgn>,
5909 should have a <tt>#!</tt> line naming the shell to be used
5910 to interpret them.</p>
5913 In the case of Perl scripts this should be
5914 <tt>#!/usr/bin/perl</tt>.</p>
5917 Shell scripts (<prgn>sh</prgn> and <prgn>bash</prgn>)
5918 should almost certainly start with <tt>set -e</tt> so that
5919 errors are detected. Every script should use
5920 <tt>set -e</tt> or check the exit status of <em>every</em>
5924 The standard shell interpreter <file>/bin/sh</file> can be a
5925 symbolic link to any POSIX compatible shell, if <tt>echo
5926 -n</tt> does not generate a newline.<footnote>
5928 Debian policy specifies POSIX behavior for
5929 <file>/bin/sh</file>, but <tt>echo -n</tt> has widespread
5930 use in the Linux community (in particular including this
5931 policy, the Linux kernel source, many Debian scripts,
5932 etc.). This <tt>echo -n</tt> mechanism is valid but not
5933 required under POSIX, hence this explicit addition.
5934 Also, rumour has it that this shall be mandated under
5938 Thus, shell scripts specifying <file>/bin/sh</file> as
5939 interpreter should only use POSIX features. If a script
5940 requires non-POSIX features from the shell interpreter, the
5941 appropriate shell must be specified in the first line of the
5942 script (e.g., <tt>#!/bin/bash</tt>) and the package must
5943 depend on the package providing the shell (unless the shell
5944 package is marked "Essential", as in the case of
5949 You may wish to restrict your script to POSIX features when
5950 possible so that it may use <file>/bin/sh</file> as its
5951 interpreter. If your script works with <prgn>dash</prgn>
5952 (originally called <prgn>ash</prgn>), it's probably POSIX
5953 compliant, but if you are in doubt, use
5954 <file>/bin/bash</file>.
5958 Perl scripts should check for errors when making any
5959 system calls, including <tt>open</tt>, <tt>print</tt>,
5960 <tt>close</tt>, <tt>rename</tt> and <tt>system</tt>.
5964 <prgn>csh</prgn> and <prgn>tcsh</prgn> should be avoided as
5965 scripting languages. See <em>Csh Programming Considered
5966 Harmful</em>, one of the <tt>comp.unix.*</tt> FAQs, which
5967 can be found at <url
5968 id="http://language.perl.com/versus/csh.whynot">.<footnote>
5970 It can also be found on
5971 <url id="http://www.cpan.org/doc/FMTEYEWTK/versus/csh.whynot">
5972 or on the ftp site <ftpsite>ftp.cpan.org</ftpsite> as
5973 <ftppath>/pub/perl/CPAN/doc/FMTEYEWTK/versus/csh.whynot</ftppath>.
5976 If an upstream package comes with <prgn>csh</prgn> scripts
5977 then you must make sure that they start with
5978 <tt>#!/bin/csh</tt> and make your package depend on the
5979 <prgn>c-shell</prgn> virtual package.
5983 Any scripts which create files in world-writeable
5984 directories (e.g., in <file>/tmp</file>) must use a
5985 mechanism which will fail if a file with the same name
5989 The Debian base system provides the <prgn>tempfile</prgn>
5990 and <prgn>mktemp</prgn> utilities for use by scripts for
5991 this purpose.</p></sect>
5995 <heading>Symbolic links</heading>
5998 In general, symbolic links within a top-level directory
5999 should be relative, and symbolic links pointing from one
6000 top-level directory into another should be absolute. (A
6001 top-level directory is a sub-directory of the root
6002 directory <file>/</file>.)</p>
6005 In addition, symbolic links should be specified as short as
6006 possible, i.e., link targets like <file>foo/../bar</file> are
6010 Note that when creating a relative link using
6011 <prgn>ln</prgn> it is not necessary for the target of the
6012 link to exist relative to the working directory you're
6013 running <prgn>ln</prgn> from, nor is it necessary to change
6014 directory to the directory where the link is to be made.
6015 Simply include the string that should appear as the target
6016 of the link (this will be a pathname relative to the
6017 directory in which the link resides) as the first argument
6018 to <prgn>ln</prgn>.</p>
6021 For example, in your <prgn>Makefile</prgn> or
6022 <file>debian/rules</file>, you can do things like:
6023 <example compact="compact">
6024 ln -fs gcc $(prefix)/bin/cc
6025 ln -fs gcc debian/tmp/usr/bin/cc
6026 ln -fs ../sbin/sendmail $(prefix)/bin/runq
6027 ln -fs ../sbin/sendmail debian/tmp/usr/bin/runq
6031 A symbolic link pointing to a compressed file should always
6032 have the same file extension as the referenced file. (For
6033 example, if a file <file>foo.gz</file> is referenced by a
6034 symbolic link, the filename of the link has to end with
6035 "<file>.gz</file>" too, as in <file>bar.gz</file>.)
6040 <heading>Device files</heading>
6043 Packages must not include device files in the package file
6047 If a package needs any special device files that are not
6048 included in the base system, it must call
6049 <prgn>MAKEDEV</prgn> in the <prgn>postinst</prgn> script,
6050 after notifying the user<footnote>
6052 This notification could be done via a (low-priority)
6053 debconf message, or an echo (printf) statement.
6059 Packages must not remove any device files in the
6060 <prgn>postrm</prgn> or any other script. This is left to the
6061 system administrator.</p>
6064 Debian uses the serial devices
6065 <file>/dev/ttyS*</file>. Programs using the old
6066 <file>/dev/cu*</file> devices should be changed to use
6067 <file>/dev/ttyS*</file>.</p>
6070 <sect id="config-files">
6071 <heading>Configuration files</heading>
6073 <heading>Definitions</heading>
6076 <tag>configuration file</tag>
6079 A file that affects the operation of a program, or
6080 provides site- or host-specific information, or
6081 otherwise customizes the behavior of a program.
6082 Typically, configuration files are intended to be
6083 modified by the system administrator (if needed or
6084 desired) to conform to local policy or to provide
6085 more useful site-specific behavior.
6089 <tag><tt>conffile</tt></tag>
6092 A file listed in a package's <tt>conffiles</tt>
6093 file, and is treated specially by <prgn>dpkg</prgn>
6094 (see <ref id="configdetails">).
6101 The distinction between these two is important; they are
6102 not interchangeable concepts. Almost all
6103 <tt>conffile</tt>s are configuration files, but many
6104 configuration files are not <tt>conffiles</tt>.
6108 Note that a script that embeds configuration information
6109 (such as most of the files in <file>/etc/default</file> and
6110 <file>/etc/cron.{daily,weekly,monthly}</file>) is de-facto a
6111 configuration file and should be treated as such.
6116 <heading>Location</heading>
6118 Any configuration files created or used by your package
6119 must reside in <file>/etc</file>. If there are several,
6120 consider creating a subdirectory of <file>/etc</file>
6121 named after your package.</p>
6124 If your package creates or uses configuration files
6125 outside of <file>/etc</file>, and it is not feasible to modify
6126 the package to use <file>/etc</file> directly, put the files
6127 in <file>/etc</file> and create symbolic links to those files
6128 from the location that the package requires.</p>
6132 <heading>Behavior</heading>
6134 Configuration file handling must conform to the following
6136 <list compact="compact">
6139 local changes must be preserved during a package
6145 configuration files must be preserved when the
6146 package is removed, and only deleted when the
6154 The easy way to achieve this behavior is to make the
6155 configuration file a <tt>conffile</tt>. This is
6156 appropriate only if it is possible to distribute a default
6157 version that will work for most installations, although
6158 some system administrators may choose to modify it. This
6159 implies that the default version will be part of the
6160 package distribution, and must not be modified by the
6161 maintainer scripts during installation (or at any other
6166 In order to ensure that local changes are preserved
6167 correctly, no package may contain or make hard links to
6168 conffiles.<footnote>
6170 Rationale: There are two problems with hard links.
6171 The first is that some editors break the link while
6172 editing one of the files, so that the two files may
6173 unwittingly become unlinked and different. The second
6174 is that <prgn>dpkg</prgn> might break the hard link
6175 while upgrading <tt>conffile</tt>s.
6181 The other way to do it is via the maintainer scripts. In
6182 this case, the configuration file must not be listed as a
6183 <tt>conffile</tt> and must not be part of the package
6184 distribution. If the existence of a file is required for
6185 the package to be sensibly configured it is the
6186 responsibility of the package maintainer to provide
6187 maintainer scripts which correctly create, update and
6188 maintain the file and remove it on purge. (See <ref
6189 id="maintainerscripts"> for more information.) These
6190 scripts must be idempotent (i.e., must work correctly if
6191 <prgn>dpkg</prgn> needs to re-run them due to errors
6192 during installation or removal), must cope with all the
6193 variety of ways <prgn>dpkg</prgn> can call maintainer
6194 scripts, must not overwrite or otherwise mangle the user's
6195 configuration without asking, must not ask unnecessary
6196 questions (particularly during upgrades), and otherwise be
6201 The scripts are not required to configure every possible
6202 option for the package, but only those necessary to get
6203 the package running on a given system. Ideally the
6204 sysadmin should not have to do any configuration other
6205 than that done (semi-)automatically by the
6206 <prgn>postinst</prgn> script.
6210 A common practice is to create a script called
6211 <file><var>package</var>-configure</file> and have the
6212 package's <prgn>postinst</prgn> call it if and only if the
6213 configuration file does not already exist. In certain
6214 cases it is useful for there to be an example or template
6215 file which the maintainer scripts use. Such files should
6216 be in <file>/usr/share/<var>package</var></file> or
6217 <file>/usr/lib/<var>package</var></file> (depending on whether
6218 they are architecture-independent or not). There should
6219 be symbolic links to them from
6220 <file>/usr/share/doc/<var>package</var>/examples</file> if
6221 they are examples, and should be perfectly ordinary
6222 <prgn>dpkg</prgn>-handled files (<em>not</em>
6223 configuration files).
6227 These two styles of configuration file handling must
6228 not be mixed, for that way lies madness:
6229 <prgn>dpkg</prgn> will ask about overwriting the file
6230 every time the package is upgraded.
6235 <heading>Sharing configuration files</heading>
6237 Packages which specify the same file as a
6238 <tt>conffile</tt> must be tagged as <em>conflicting</em>
6239 with each other. (This is an instance of the general rule
6240 about not sharing files. Note that neither alternatives
6241 nor diversions are likely to be appropriate in this case;
6242 in particular, <prgn>dpkg</prgn> does not handle diverted
6243 <tt>conffile</tt>s well.)
6247 The maintainer scripts must not alter a <tt>conffile</tt>
6248 of <em>any</em> package, including the one the scripts
6253 If two or more packages use the same configuration file
6254 and it is reasonable for both to be installed at the same
6255 time, one of these packages must be defined as
6256 <em>owner</em> of the configuration file, i.e., it will be
6257 the package which handles that file as a configuration
6258 file. Other packages that use the configuration file must
6259 depend on the owning package if they require the
6260 configuration file to operate. If the other package will
6261 use the configuration file if present, but is capable of
6262 operating without it, no dependency need be declared.</p>
6265 If it is desirable for two or more related packages to
6266 share a configuration file <em>and</em> for all of the
6267 related packages to be able to modify that configuration
6268 file, then the following should be done:
6269 <enumlist compact="compact">
6272 One of the related packages (the "owning" package)
6273 will manage the configuration file with maintainer
6274 scripts as described in the previous section.
6279 The owning package should also provide a program
6280 that the other packages may use to modify the
6286 The related packages must use the provided program
6287 to make any desired modifications to the
6288 configuration file. They should either depend on
6289 the core package to guarantee that the configuration
6290 modifier program is available or accept gracefully
6291 that they cannot modify the configuration file if it
6292 is not. (This is in addition to the fact that the
6293 configuration file may not even be present in the
6301 Sometimes it's appropriate to create a new package which
6302 provides the basic infrastructure for the other packages
6303 and which manages the shared configuration files. (The
6304 <tt>sgml-base</tt> package is a good example.)
6309 <heading>User configuration files ("dotfiles")</heading>
6312 The files in <file>/etc/skel</file> will automatically be
6313 copied into new user accounts by <prgn>adduser</prgn>.
6314 No other program should reference the files in
6315 <file>/etc/skel</file>.
6319 Therefore, if a program needs a dotfile to exist in
6320 advance in <file>$HOME</file> to work sensibly, that dotfile
6321 should be installed in <file>/etc/skel</file> and treated as a
6326 However, programs that require dotfiles in order to
6327 operate sensibly are a bad thing, unless they do create
6328 the dotfiles themselves automatically.
6332 Furthermore, programs should be configured by the Debian
6333 default installation to behave as closely to the upstream
6334 default behaviour as possible.
6338 Therefore, if a program in a Debian package needs to be
6339 configured in some way in order to operate sensibly, that
6340 should be done using a site-wide configuration file placed
6341 in <file>/etc</file>. Only if the program doesn't support a
6342 site-wide default configuration and the package maintainer
6343 doesn't have time to add it may a default per-user file be
6344 placed in <file>/etc/skel</file>.
6348 <file>/etc/skel</file> should be as empty as we can make it.
6349 This is particularly true because there is no easy (or
6350 necessarily desirable) mechanism for ensuring that the
6351 appropriate dotfiles are copied into the accounts of
6352 existing users when a package is installed.
6358 <heading>Log files</heading>
6360 Log files should usually be named
6361 <file>/var/log/<var>package</var>.log</file>. If you have many
6362 log files, or need a separate directory for permission
6363 reasons (<file>/var/log</file> is writable only by
6364 <file>root</file>), you should usually create a directory named
6365 <file>/var/log/<var>package</var></file> and place your log
6370 Log files must be rotated occasionally so that they don't
6371 grow indefinitely; the best way to do this is to drop a log
6372 rotation configuration file into the directory
6373 <file>/etc/logrotate.d</file> and use the facilities provided by
6374 logrotate.<footnote>
6376 The traditional approach to log files has been to set up
6377 <em>ad hoc</em> log rotation schemes using simple shell
6378 scripts and cron. While this approach is highly
6379 customizable, it requires quite a lot of sysadmin work.
6380 Even though the original Debian system helped a little
6381 by automatically installing a system which can be used
6382 as a template, this was deemed not enough.
6386 The use of <prgn>logrotate</prgn>, a program developed
6387 by Red Hat, is better, as it centralizes log management.
6388 It has both a configuration file
6389 (<file>/etc/logrotate.conf</file>) and a directory where
6390 packages can drop their individual log rotation
6391 configurations (<file>/etc/logrotate.d</file>).
6394 Here is a good example for a logrotate config
6395 file (for more information see <manref name="logrotate"
6397 <example compact="compact">
6403 /etc/init.d/foo force-reload
6407 This rotates all files under <file>/var/log/foo</file>, saves 12
6408 compressed generations, and forces the daemon to reload its
6409 configuration information after the log rotation.
6413 Log files should be removed when the package is
6414 purged (but not when it is only removed). This should be
6415 done by the <prgn>postrm</prgn> script when it is called
6416 with the argument <tt>purge</tt> (see <ref
6417 id="removedetails">).
6422 <heading>Permissions and owners</heading>
6425 The rules in this section are guidelines for general use.
6426 If necessary you may deviate from the details below.
6427 However, if you do so you must make sure that what is done
6428 is secure and you should try to be as consistent as possible
6429 with the rest of the system. You should probably also
6430 discuss it on <prgn>debian-devel</prgn> first.
6434 Files should be owned by <tt>root.root</tt>, and made
6435 writable only by the owner and universally readable (and
6436 executable, if appropriate), that is mode 644 or 755.
6440 Directories should be mode 755 or (for group-writability)
6441 mode 2775. The ownership of the directory should be
6442 consistent with its mode: if a directory is mode 2775, it
6443 should be owned by the group that needs write access to
6448 Setuid and setgid executables should be mode 4755 or 2755
6449 respectively, and owned by the appropriate user or group.
6450 They should not be made unreadable (modes like 4711 or
6451 2711 or even 4111); doing so achieves no extra security,
6452 because anyone can find the binary in the freely available
6453 Debian package; it is merely inconvenient. For the same
6454 reason you should not restrict read or execute permissions
6455 on non-set-id executables.
6459 Some setuid programs need to be restricted to particular
6460 sets of users, using file permissions. In this case they
6461 should be owned by the uid to which they are set-id, and by
6462 the group which should be allowed to execute them. They
6463 should have mode 4754; again there is no point in making
6464 them unreadable to those users who must not be allowed to
6469 It is possible to arrange that the system administrator can
6470 reconfigure the package to correspond to their local
6471 security policy by changing the permissions on a binary:
6472 they can do this by using <prgn>dpkg-statoverride</prgn>, as
6473 described below.<footnote>
6475 Ordinary files installed by <prgn>dpkg</prgn> (as
6476 opposed to <tt>conffile</tt>s and other similar objects)
6477 normally have their permissions reset to the distributed
6478 permissions when the package is reinstalled. However,
6479 the use of <prgn>dpkg-statoverride</prgn> overrides this
6480 default behaviour. If you use this method, you should
6481 remember to describe <prgn>dpkg-statoverride</prgn> in
6482 the package documentation; being a relatively new
6483 addition to Debian, it is probably not yet well-known.
6486 Another method you should consider is to create a group for
6487 people allowed to use the program(s) and make any setuid
6488 executables executable only by that group.
6492 If you need to create a new user or group for your package
6493 there are two possibilities. Firstly, you may need to
6494 make some files in the binary package be owned by this
6495 user or group, or you may need to compile the user or
6496 group id (rather than just the name) into the binary
6497 (though this latter should be avoided if possible, as in
6498 this case you need a statically allocated id).</p>
6501 If you need a statically allocated id, you must ask for a
6502 user or group id from the <tt>base-passwd</tt> maintainer,
6503 and must not release the package until you have been
6504 allocated one. Once you have been allocated one you must
6505 either make the package depend on a version of the
6506 <tt>base-passwd</tt> package with the id present in
6507 <file>/etc/passwd</file> or <file>/etc/group</file>, or arrange for
6508 your package to create the user or group itself with the
6509 correct id (using <tt>adduser</tt>) in its
6510 <prgn>preinst</prgn> or <prgn>postinst</prgn>. (Doing it in
6511 the <prgn>postinst</prgn> is to be preferred if it is
6512 possible, otherwise a pre-dependency will be needed on the
6513 <tt>adduser</tt> package.)
6517 On the other hand, the program might be able to determine
6518 the uid or gid from the user or group name at runtime, so
6519 that a dynamically allocated id can be used. In this case
6520 you should choose an appropriate user or group name,
6521 discussing this on <prgn>debian-devel</prgn> and checking
6522 with the <package/base-passwd/ maintainer that it is unique and that
6523 they do not wish you to use a statically allocated id
6524 instead. When this has been checked you must arrange for
6525 your package to create the user or group if necessary using
6526 <prgn>adduser</prgn> in the <prgn>preinst</prgn> or
6527 <prgn>postinst</prgn> script (again, the latter is to be
6528 preferred if it is possible).
6532 Note that changing the numeric value of an id associated
6533 with a name is very difficult, and involves searching the
6534 file system for all appropriate files. You need to think
6535 carefully whether a static or dynamic id is required, since
6536 changing your mind later will cause problems.
6539 <sect1><heading>The use of <prgn>dpkg-statoverride</prgn></heading>
6541 This section is not intended as policy, but as a
6542 description of the use of <prgn>dpkg-statoverride</prgn>.
6546 <prgn>dpkg-statoverride</prgn> is a replacement for the
6547 deprecated <tt>suidmanager</tt> package. Packages which
6548 previously used <tt>suidmanager</tt> should have a
6549 <tt>Conflicts: suidmanager (<< 0.50)</tt> entry (or even
6550 <tt>(<< 0.52)</tt>), and calls to <tt>suidregister</tt>
6551 and <tt>suidunregister</tt> should now be simply removed
6552 from the maintainer scripts.
6556 If a system administrator wishes to have a file (or
6557 directory or other such thing) installed with owner and
6558 permissions different from those in the distributed Debian
6559 package, he can use the <prgn>dpkg-statoverride</prgn>
6560 program to instruct <prgn>dpkg</prgn> to use the different
6561 settings every time the file is installed. Thus the
6562 package maintainer should distribute the files with their
6563 normal permissions, and leave it for the system
6564 administrator to make any desired changes. For example, a
6565 daemon which is normally required to be setuid root, but
6566 in certain situations could be used without being setuid,
6567 should be installed setuid in the <tt>.deb</tt>. Then the
6568 local system administrator can change this if they wish.
6569 If there are two standard ways of doing it, the package
6570 maintainer can use <tt>debconf</tt> to find out the
6571 preference, and call <prgn>dpkg-statoverride</prgn> in the
6572 maintainer script if necessary to accommodate the system
6573 administrator's choice.
6577 Given the above, <prgn>dpkg-statoverride</prgn> is
6578 essentially a tool for system administrators and would not
6579 normally be needed in the maintainer scripts. There is
6580 one type of situation, though, where calls to
6581 <prgn>dpkg-statoverride</prgn> would be needed in the
6582 maintainer scripts, and that involves packages which use
6583 dynamically allocated user or group ids. In such a
6584 situation, something like the following idiom can be very
6585 helpful in the package's <prgn>postinst</prgn>, where
6586 <tt>sysuser</tt> is a dynamically allocated id:
6588 for i in /usr/bin/foo /usr/sbin/bar
6590 if ! dpkg-statoverride --list $i >/dev/null
6592 dpkg-statoverride --update --add sysuser root 4755 $i
6596 The corresponding <tt>dpkg-statoverride --remove</tt>
6597 calls can then be made unconditionally when the package is
6604 <chapt id="customized-programs">
6605 <heading>Customized programs</heading>
6607 <sect id="arch-spec">
6608 <heading>Architecture specification strings</heading>
6611 If a program needs to specify an <em>architecture specification
6612 string</em> in some place, the following format should be
6613 used: <var>arch</var>-<var>os</var><footnote>
6615 The following architectures and operating systems are
6616 currently recognised by <prgn>dpkg-archictecture</prgn>.
6617 The architecture, <tt><var>arch</var></tt>, is one of
6618 the following: <tt>alpha</tt>, <tt>arm</tt>,
6619 <tt>hppa</tt>, <tt>i386</tt>, <tt>ia64</tt>,
6620 <tt>m68k</tt>, <tt>mips</tt>, <tt>mipsel</tt>,
6621 <tt>powerpc</tt>, <tt>s390</tt>, <tt>sh</tt>,
6622 <tt>sheb</tt>, <tt>sparc</tt> and <tt>sparc64</tt>. The
6623 operating system, <tt><var>os</var></tt>, is one of:
6624 <tt>linux</tt>, <tt>gnu</tt>, <tt>freebsd</tt> and
6625 <tt>openbsd</tt>. Use of <tt>gnu</tt> in this string is
6626 reserved for the GNU/Hurd operating system.
6632 Note that we don't want to use
6633 <tt><var>arch</var>-debian-linux</tt> to apply to the rule
6634 <tt><var>architecture</var>-<var>vendor</var>-<var>os</var></tt>
6635 since this would make our programs incompatible with other
6636 Linux distributions. We also don't use something like
6637 <tt><var>arch</var>-unknown-linux</tt>, since the
6638 <tt>unknown</tt> does not look very good.
6643 <heading>Daemons</heading>
6646 The configuration files <file>/etc/services</file>,
6647 <file>/etc/protocols</file>, and <file>/etc/rpc</file> are managed
6648 by the <prgn>netbase</prgn> package and must not be modified
6653 If a package requires a new entry in one of these files, the
6654 maintainer should get in contact with the
6655 <prgn>netbase</prgn> maintainer, who will add the entries
6656 and release a new version of the <prgn>netbase</prgn>
6661 The configuration file <file>/etc/inetd.conf</file> must not be
6662 modified by the package's scripts except via the
6663 <prgn>update-inetd</prgn> script or the
6664 <file>DebianNet.pm</file> Perl module. See their documentation
6665 for details on how to add entries.
6669 If a package wants to install an example entry into
6670 <file>/etc/inetd.conf</file>, the entry must be preceded with
6671 exactly one hash character (<tt>#</tt>). Such lines are
6672 treated as "commented out by user" by the
6673 <prgn>update-inetd</prgn> script and are not changed or
6674 activated during package updates.
6679 <heading>Using pseudo-ttys and modifying wtmp, utmp and
6683 Some programs need to create pseudo-ttys. This should be done
6684 using Unix98 ptys if the C library supports it. The resulting
6685 program must not be installed setuid root, unless that
6686 is required for other functionality.
6690 The files <file>/var/run/utmp</file>, <file>/var/log/wtmp</file> and
6691 <file>/var/log/lastlog</file> must be installed writeable by
6692 group <tt>utmp</tt>. Programs which need to modify those
6693 files must be installed setgid <tt>utmp</tt>.
6698 <heading>Editors and pagers</heading>
6701 Some programs have the ability to launch an editor or pager
6702 program to edit or display a text document. Since there are
6703 lots of different editors and pagers available in the Debian
6704 distribution, the system administrator and each user should
6705 have the possibility to choose his/her preferred editor and
6710 In addition, every program should choose a good default
6711 editor/pager if none is selected by the user or system
6716 Thus, every program that launches an editor or pager must
6717 use the EDITOR or PAGER environment variable to determine
6718 the editor or pager the user wishes to use. If these
6719 variables are not set, the programs <file>/usr/bin/editor</file>
6720 and <file>/usr/bin/pager</file> should be used, respectively.
6724 These two files are managed through the <prgn>dpkg</prgn>
6725 "alternatives" mechanism. Thus every package providing an
6726 editor or pager must call the
6727 <prgn>update-alternatives</prgn> script to register these
6732 If it is very hard to adapt a program to make use of the
6733 EDITOR or PAGER variables, that program may be configured to
6734 use <file>/usr/bin/sensible-editor</file> and
6735 <file>/usr/bin/sensible-pager</file> as the editor or pager
6736 program respectively. These are two scripts provided in the
6737 Debian base system that check the EDITOR and PAGER variables
6738 and launch the appropriate program, and fall back to
6739 <file>/usr/bin/editor</file> and <file>/usr/bin/pager</file> if the
6740 variable is not set.
6744 A program may also use the VISUAL environment variable to
6745 determine the user's choice of editor. If it exists, it
6746 should take precedence over EDITOR. This is in fact what
6747 <file>/usr/bin/sensible-editor</file> does.
6751 It is not required for a package to depend on
6752 <tt>editor</tt> and <tt>pager</tt>, nor is it required for a
6753 package to provide such virtual packages.<footnote>
6755 The Debian base system already provides an editor and a
6762 <sect id="web-appl">
6763 <heading>Web servers and applications</heading>
6766 This section describes the locations and URLs that should
6767 be used by all web servers and web applications in the
6775 Cgi-bin executable files are installed in the
6777 <example compact="compact">
6778 /usr/lib/cgi-bin/<var>cgi-bin-name</var>
6780 and should be referred to as
6781 <example compact="compact">
6782 http://localhost/cgi-bin/<var>cgi-bin-name</var>
6787 <item><p>Access to HTML documents</p>
6790 HTML documents for a package are stored in
6791 <file>/usr/share/doc/<var>package</var></file>
6792 and can be referred to as
6793 <example compact="compact">
6794 http://localhost/doc/<var>package</var>/<var>filename</var>
6798 The web server should restrict access to the document
6799 tree so that only clients on the same host can read
6800 the documents. If the web server does not support such
6801 access controls, then it should not provide access at
6802 all, or ask about providing access during installation.
6806 <item><p>Web Document Root</p>
6809 Web Applications should try to avoid storing files in
6810 the Web Document Root. Instead they should use the
6811 /usr/share/doc/<var>package</var> directory for
6812 documents and register the Web Application via the
6813 menu package. If access to the web document root is
6814 unavoidable then use
6815 <example compact="compact">
6818 as the Document Root. This might be just a symbolic
6819 link to the location where the system administrator
6820 has put the real document root.
6824 </enumlist></p></sect>
6827 <sect id="mail-transport-agents">
6828 <heading>Mail transport, delivery and user agents</heading>
6831 Debian packages which process electronic mail, whether mail
6832 user agents (MUAs) or mail transport agents (MTAs), must
6833 ensure that they are compatible with the configuration
6834 decisions below. Failure to do this may result in lost
6835 mail, broken <tt>From:</tt> lines, and other serious brain
6840 The mail spool is <file>/var/mail</file> and the interface to
6841 send a mail message is <file>/usr/sbin/sendmail</file> (as per
6842 the FHS). On older systems, the mail spool may be
6843 physically located in <file>/var/spool/mail</file>, but all
6844 access to the mail spool should be via the
6845 <file>/var/mail</file> symlink. The mail spool is part of the
6846 base system and not part of the MTA package.
6850 All Debian MUAs, MTAs, MDAs and other mailbox accessing
6851 programs (such as IMAP daemons) must lock the mailbox in an
6852 NFS-safe way. This means that <tt>fcntl()</tt> locking must
6853 be combined with dot locking. To avoid deadlocks, a program
6854 should use <tt>fcntl()</tt> first and dot locking after
6855 this, or alternatively implement the two locking methods in
6856 a non blocking way<footnote>
6858 If it is not possible to establish both locks, the
6859 system shouldn't wait for the second lock to be
6860 established, but remove the first lock, wait a (random)
6861 time, and start over locking again.
6863 </footnote>. Using the functions <tt>maillock</tt> and
6864 <tt>mailunlock</tt> provided by the
6865 <tt>liblockfile*</tt><footnote>
6867 You will need to depend on <tt>liblockfile1
6868 (>>1.01)</tt> to use these functions.
6870 </footnote> packages is the recommended way to realize this.
6874 Mailboxes are generally mode 660
6875 <tt><var>user</var>.mail</tt> unless the system
6876 administrator has chosen otherwise. A MUA may remove a
6877 mailbox (unless it has nonstandard permissions) in which
6878 case the MTA or another MUA must recreate it if needed.
6879 Mailboxes must be writable by group mail.
6883 The mail spool is 2775 <tt>root.mail</tt>, and MUAs should
6884 be setgid mail to do the locking mentioned above (and
6885 must obviously avoid accessing other users' mailboxes
6886 using this privilege).</p>
6889 <file>/etc/aliases</file> is the source file for the system mail
6890 aliases (e.g., postmaster, usenet, etc.), it is the one
6891 which the sysadmin and <prgn>postinst</prgn> scripts may
6892 edit. After <file>/etc/aliases</file> is edited the program or
6893 human editing it must call <prgn>newaliases</prgn>. All MTA
6894 packages must come with a <prgn>newaliases</prgn> program,
6895 even if it does nothing, but older MTA packages did not do
6896 this so programs should not fail if <prgn>newaliases</prgn>
6897 cannot be found. Note that because of this, all MTA
6898 packages must have <tt>Provides</tt>, <tt>Conflicts</tt> and
6899 <tt>Replaces: mail-transport-agent</tt> control file
6904 The convention of writing <tt>forward to
6905 <var>address</var></tt> in the mailbox itself is not
6906 supported. Use a <tt>.forward</tt> file instead.</p>
6909 The <prgn>rmail</prgn> program used by UUCP
6910 for incoming mail should be <file>/usr/sbin/rmail</file>.
6911 Likewise, <prgn>rsmtp</prgn>, for receiving
6912 batch-SMTP-over-UUCP, should be <file>/usr/sbin/rsmtp</file> if it
6916 If your package needs to know what hostname to use on (for
6917 example) outgoing news and mail messages which are generated
6918 locally, you should use the file <file>/etc/mailname</file>. It
6919 will contain the portion after the username and <tt>@</tt>
6920 (at) sign for email addresses of users on the machine
6921 (followed by a newline).
6925 Such package should check for the existence of this file
6926 when it is being configured. If it exists, it should be
6927 used without comment, although an MTA's configuration script
6928 may wish to prompt the user even if it finds that this file
6929 exists. If the file does not exist, the package should
6930 prompt the user for the value (preferably using
6931 <prgn>debconf</prgn>) and store it in <file>/etc/mailname</file>
6932 as well as using it in the package's configuration. The
6933 prompt should make it clear that the name will not just be
6934 used by that package. For example, in this situation the
6935 <tt>inn</tt> package could say something like:
6936 <example compact="compact">
6937 Please enter the "mail name" of your system. This is the
6938 hostname portion of the address to be shown on outgoing
6939 news and mail messages. The default is
6940 <var>syshostname</var>, your system's host name. Mail
6941 name ["<var>syshostname</var>"]:
6943 where <var>syshostname</var> is the output of <tt>hostname
6949 <heading>News system configuration</heading>
6952 All the configuration files related to the NNTP (news)
6953 servers and clients should be located under
6954 <file>/etc/news</file>.</p>
6957 There are some configuration issues that apply to a number
6958 of news clients and server packages on the machine. These
6962 <tag><file>/etc/news/organization</file></tag>
6963 <item><p>A string which should appear as the
6964 organization header for all messages posted
6965 by NNTP clients on the machine</p></item>
6967 <tag><file>/etc/news/server</file></tag>
6968 <item><p>Contains the FQDN of the upstream NNTP
6969 server, or localhost if the local machine is
6970 an NNTP server.</p></item>
6973 Other global files may be added as required for cross-package news
6974 configuration.</p></sect>
6978 <heading>Programs for the X Window System</heading>
6981 <heading>Providing X support and package priorities</heading>
6984 Programs that can be configured with support for the X
6985 Window System must be configured to do so and must declare
6986 any package dependencies necessary to satisfy their
6987 runtime requirements when using the X Window System. If
6988 such a package is of higher priority than the X packages
6989 on which it depends, it is required that either the
6990 X-specific components be split into a separate package, or
6991 that an alternative version of the package, which includes
6992 X support, be provided, or that the package's priority be
6998 <heading>Packages providing an X server</heading>
7001 Packages that provide an X server that, directly or
7002 indirectly, communicates with real input and display
7003 hardware should declare in their control data that they
7004 provide the virtual package <tt>xserver</tt>.<footnote>
7006 This implements current practice, and provides an
7007 actual policy for usage of the <tt>xserver</tt>
7008 virtual package which appears in the virtual packages
7009 list. In a nutshell, X servers that interface
7010 directly with the display and input hardware or via
7011 another subsystem (e.g., GGI) should provide
7012 <tt>xserver</tt>. Things like <tt>Xvfb</tt>,
7013 <tt>Xnest</tt>, and <tt>Xprt</tt> should not.
7020 <heading>Packages providing a terminal emulator</heading>
7023 Packages that provide a terminal emulator for the X Window
7024 System which meet the criteria listed below should declare
7025 in their control data that they provide the virtual
7026 package <tt>x-terminal-emulator</tt>. They should also
7027 register themselves as an alternative for
7028 <file>/usr/bin/x-terminal-emulator</file>, with a priority of
7033 To be an <tt>x-terminal-emulator</tt>, a program must:
7034 <list compact="compact">
7036 Be able to emulate a DEC VT100 terminal, or a
7037 compatible terminal.
7041 Support the command-line option <tt>-e
7042 <var>command</var></tt>, which creates a new
7043 terminal window<footnote>
7045 "New terminal window" does not necessarily mean
7046 a new top-level X window directly parented by
7047 the window manager; it could, if the terminal
7048 emulator application were so coded, be a new
7049 "view" in a multiple-document interface (MDI).
7052 and runs the specified <var>command</var>.
7056 Support the command-line option <tt>-T
7057 <var>title</var></tt>, which creates a new terminal
7058 window with the window title <var>title</var>.
7065 <heading>Packages providing a window manager</heading>
7068 Packages that provide a window manager should declare in
7069 their control data that they provide the virtual package
7070 <tt>x-window-manager</tt>. They should also register
7071 themselves as an alternative for
7072 <file>/usr/bin/x-window-manager</file>, with a priority
7073 calculated as follows:
7074 <list compact="compact">
7075 <item><p>Start with a priority of 20.</p></item>
7079 If the window manager supports the Debian menu
7080 system, add 20 points if this support is available
7081 in the package's default configuration (i.e., no
7082 configuration files belonging to the system or user
7083 have to be edited to activate the feature); if
7084 configuration files must be modified, add only 10
7090 If the window manager complies with <url
7091 id="http://www.freedesktop.org/standards/wm-spec.html"
7092 name="The Window Manager Specification Project">,
7093 written by the <url id="http://www.freedesktop.org"
7094 name="Free Desktop Group">, add 20 points.
7100 If the window manager permits the X session to be
7101 restarted using a <em>different</em> window manager
7102 (without killing the X server) in its default
7103 configuration, add 10 points; otherwise add none.
7111 <heading>Packages providing fonts</heading>
7114 Packages that provide fonts for the X Window
7117 For the purposes of Debian Policy, a "font for the X
7118 Window System" is one which is accessed via X protocol
7119 requests. Fonts for the Linux console, for PostScript
7120 renderers, or any other purpose, do not fit this
7121 definition. Any tool which makes such fonts available
7122 to the X Window System, however, must abide by this
7126 must do a number of things to ensure that they are both
7127 available without modification of the X or font server
7128 configuration, and that they do not corrupt files used by
7129 other font packages to register information about
7134 Fonts of any type supported by the X Window System
7135 must be in a separate binary package from any
7136 executables, libraries, or documentation (except
7137 that specific to the fonts shipped, such as their
7138 license information). If one or more of the fonts
7139 so packaged are necessary for proper operation of
7140 the package with which they are associated the font
7141 package may be Recommended; if the fonts merely
7142 provide an enhancement, a Suggests relationship may
7143 be used. Packages must not Depend on font
7146 This is because the X server may retrieve fonts
7147 from the local filesystem or over the network
7148 from an X font server; the Debian package system
7149 is empowered to deal only with the local
7158 BDF fonts must be converted to PCF fonts with the
7159 <prgn>bdftopcf</prgn> utility (available in the
7160 <tt>xutils</tt> package, <prgn>gzip</prgn>ped, and
7161 placed in a directory that corresponds to their
7163 <list compact="compact">
7165 100 dpi fonts must be placed in
7166 <file>/usr/X11R6/lib/X11/fonts/100dpi/</file>.
7170 75 dpi fonts must be placed in
7171 <file>/usr/X11R6/lib/X11/fonts/75dpi/</file>.
7175 Character-cell fonts, cursor fonts, and other
7176 low-resolution fonts must be placed in
7177 <file>/usr/X11R6/lib/X11/fonts/misc/</file>.
7184 Speedo fonts must be placed in
7185 <file>/usr/X11R6/lib/X11/fonts/Speedo/</file>.
7189 Type 1 fonts must be placed in
7190 <file>/usr/X11R6/lib/X11/fonts/Type1/</file>. If font
7191 metric files are available, they must be placed here
7197 Subdirectories of <file>/usr/X11R6/lib/X11/fonts/</file>
7198 other than those listed above must be neither
7199 created nor used. (The <file>PEX</file>, <file>CID</file>,
7200 and <file>cyrillic</file> directories are excepted for
7201 historical reasons, but installation of files into
7202 these directories remains discouraged.)
7208 Font packages may, instead of placing files directly
7209 in the X font directories listed above, provide
7210 symbolic links in that font directory pointing to
7211 the files' actual location in the filesystem. Such
7212 a location must comply with the FHS.
7218 Font packages should not contain both 75dpi and
7219 100dpi versions of a font. If both are available,
7220 they should be provided in separate binary packages
7221 with <tt>-75dpi</tt> or <tt>-100dpi</tt> appended to
7222 the names of the packages containing the
7223 corresponding fonts.
7229 Fonts destined for the <file>misc</file> subdirectory
7230 should not be included in the same package as 75dpi
7231 or 100dpi fonts; instead, they should be provided in
7232 a separate package with <tt>-misc</tt> appended to
7239 Font packages must not provide the files
7240 <file>fonts.dir</file>, <file>fonts.alias</file>, or
7241 <file>fonts.scale</file> in a font directory:
7244 <file>fonts.dir</file> files must not be provided at all.
7249 <file>fonts.alias</file> and <file>fonts.scale</file>
7250 files, if needed, should be provided in the
7252 <file>/etc/X11/fonts/<var>fontdir</var>/<var>package</var>.<var>extension</var></file>,
7253 where <var>fontdir</var> is the name of the
7255 <file>/usr/X11R6/lib/X11/fonts/</file> where the
7256 package's corresponding fonts are stored
7257 (e.g., <tt>75dpi</tt> or <tt>misc</tt>),
7258 <var>package</var> is the name of the package
7259 that provides these fonts, and
7260 <var>extension</var> is either <tt>scale</tt>
7261 or <tt>alias</tt>, whichever corresponds to
7271 Font packages must declare a dependency on
7272 <tt>xutils (>> 4.0.3)</tt> in their control
7279 Font packages that provide one or more
7280 <file>fonts.scale</file> files as described above must
7281 invoke <prgn>update-fonts-scale</prgn> on each
7282 directory into which they installed fonts
7283 <em>before</em> invoking
7284 <prgn>update-fonts-dir</prgn> on that directory.
7285 This invocation must occur in both the
7286 <prgn>postinst</prgn> (for all arguments) and
7287 <prgn>postrm</prgn> (for all arguments except
7288 <tt>upgrade</tt>) scripts.
7294 Font packages that provide one or more
7295 <file>fonts.alias</file> files as described above must
7296 invoke <prgn>update-fonts-alias</prgn> on each
7297 directory into which they installed fonts. This
7298 invocation must occur in both the
7299 <prgn>postinst</prgn> (for all arguments) and
7300 <prgn>postrm</prgn> (for all arguments except
7301 <tt>upgrade</tt>) scripts.
7307 Font packages must invoke
7308 <prgn>update-fonts-dir</prgn> on each directory into
7309 which they installed fonts. This invocation must
7310 occur in both the <prgn>postinst</prgn> (for all
7311 arguments) and <prgn>postrm</prgn> (for all
7312 arguments except <tt>upgrade</tt>) scripts.
7318 Font packages must not provide alias names for the
7319 fonts they include which collide with alias names
7320 already in use by fonts already packaged.
7326 Font packages must not provide fonts with the same
7327 XLFD registry name as another font already packaged.
7335 <heading>Application defaults files</heading>
7338 Application defaults files must be installed in the
7339 directory <file>/etc/X11/app-defaults/</file> (use of a
7340 localized subdirectory of <file>/etc/X11/</file> as described
7341 in the <em>X Toolkit Intrinsics - C Language
7342 Interface</em> manual is also permitted). They must be
7343 registered as <tt>conffile</tt>s or handled as
7344 configuration files. Packages must not provide the
7345 directory <file>/usr/X11R6/lib/X11/app-defaults/</file>.
7349 Customization of programs' X resources may also be
7350 supported with the provision of a file with the same name
7351 as that of the package placed in the
7352 <file>/etc/X11/Xresources/</file> directory, which must
7353 registered as a <tt>conffile</tt> or handled as a
7354 configuration file.<footnote>
7356 Note that this mechanism is not the same as using
7357 app-defaults; app-defaults are tied to the client
7358 binary on the local filesystem, whereas X resources
7359 are stored in the X server and affect all connecting
7363 <em>Important:</em> packages that install files into the
7364 <file>/etc/X11/Xresources/</file> directory must conflict with
7365 <tt>xbase (<< 3.3.2.3a-2)</tt>; if this is not done
7366 it is possible for the installing package to destroy a
7367 previously-existing <file>/etc/X11/Xresources</file> file
7368 which had been customized by the system administrator.
7373 <heading>Installation directory issues</heading>
7376 Packages using the X Window System should not be
7377 configured to install files under the <file>/usr/X11R6/</file>
7378 directory unless they use <prgn>imake</prgn>. The
7379 <file>/usr/X11R6/</file> directory hierarchy should be
7380 regarded as deprecated for all packages except the X
7381 Window System itself, and those which use the
7382 <prgn>imake</prgn> program it provides, in which case the
7383 packages may transition out of the <file>/usr/X11R6/</file>
7384 directory at the maintainer's discretion.<footnote>
7386 <prgn>Imake</prgn>-using programs are exempt because,
7387 as long as they are written correctly, the pathnames
7388 they use to locate resources and install themselves
7389 are derived wholly from the X Window System
7390 configuration. Thus, in the event that the X Window
7391 System moves to <file>/usr/X11R7/</file>,
7392 <file>/usr/X12/</file>, or just plain <file>/usr/</file>, all
7393 that is required for these programs is a recompile
7394 against the corresponding X Window System library
7395 development packages.
7398 Programs that use GNU <prgn>autoconf</prgn> and
7399 <prgn>automake</prgn> are usually easily configured at
7400 compile time to use <file>/usr/</file> instead of
7401 <file>/usr/X11R6/</file>, and this should be done whenever
7402 possible. Configuration files for window managers and
7403 display managers should be placed in a subdirectory of
7404 <file>/etc/X11/</file> corresponding to the package name due
7405 to these programs' tight integration with the mechanisms
7406 of the X Window System. Application-level programs should
7407 use the <file>/etc/</file> directory unless otherwise mandated
7408 by policy. The installation of files into subdirectories
7409 of <file>/usr/X11R6/include/X11/</file> and
7410 <file>/usr/X11R6/lib/X11/</file> is permitted but discouraged;
7411 package maintainers should determine if subdirectories of
7412 <file>/usr/lib/</file> and <file>/usr/share/</file> can be used
7413 instead. (The use of symbolic links from the
7414 <file>X11R6</file> directories to other FHS-compliant
7415 locations is encouraged if the program is not easily
7416 configured to look elsewhere for its files.) Packages
7417 must not provide or install files into the directories
7418 <file>/usr/bin/X11/</file>, <file>/usr/include/X11/</file> or
7419 <file>/usr/lib/X11/</file>. Files within a package should,
7420 however, make reference to these directories, rather than
7421 their <tt>X11R6</tt>-named counterparts
7422 <file>/usr/X11R6/bin/</file>, <file>/usr/X11R6/include/X11/</file>
7423 and <file>/usr/X11R6/lib/X11/</file>, if the resources being
7424 referred to have not been moved to other FHS-compliant
7430 <heading>The OSF/Motif and OpenMotif libraries</heading>
7433 <em>Programs that require the non-DFSG-compliant OSF/Motif or
7434 OpenMotif libraries</em><footnote>
7436 OSF/Motif and OpenMotif are collectively referred to as
7437 "Motif" in this policy document.
7440 should be compiled against and tested with LessTif (a free
7441 re-implementation of Motif) instead. If the maintainer
7442 judges that the program or programs do not work
7443 sufficiently well with LessTif to be distributed and
7444 supported, but do so when compiled against Motif, then two
7445 versions of the package should be created; one linked
7446 statically against Motif and with <tt>-smotif</tt>
7447 appended to the package name, and one linked dynamically
7448 against Motif and with <tt>-dmotif</tt> appended to the
7449 package name. Both Motif-linked versions are dependent
7450 upon non-DFSG-compliant software and thus cannot be
7451 uploaded to the <em>main</em> distribution; if the
7452 software is itself DFSG-compliant it may be uploaded to
7453 the <em>contrib</em> distribution. While known existing
7454 versions of Motif permit unlimited redistribution of
7455 binaries linked against the library (whether statically or
7456 dynamically), it is the package maintainer's
7457 responsibility to determine whether this is permitted by
7458 the license of the copy of Motif in his or her possession.
7464 <heading>Perl programs and modules</heading>
7466 Perl programs and modules should follow the current Perl
7467 policy as defined in the file found on
7468 <ftpsite>ftp.debian.org</ftpsite> in
7469 <ftppath>/debian/doc/package-developer/perl-policy.txt.gz</ftppath>
7470 or your local mirror. In addition, it is included in the
7471 <tt>debian-policy</tt> package.
7476 <heading>Emacs lisp programs</heading>
7479 Please refer to the "Debian Emacs Policy" (documented in
7480 <file>debian-emacs-policy.gz</file> of the
7481 <prgn>emacsen-common</prgn> package) for details of how to
7482 package emacs lisp programs.
7487 <heading>Games</heading>
7490 The permissions on <file>/var/games</file> are mode 755, owner
7491 <tt>root</tt> and group <tt>root</tt>.
7495 Each game decides on its own security policy.</p>
7498 Games which require protected, privileged access to
7499 high-score files, savegames, etc., may be made
7500 set-<em>group</em>-id (mode 2755) and owned by
7501 <tt>root.games</tt>, and use files and directories with
7502 appropriate permissions (770 <tt>root.games</tt>, for
7503 example). They must not be made
7504 set-<em>user</em>-id, as this causes security problems. (If
7505 an attacker can subvert any set-user-id game they can
7506 overwrite the executable of any other, causing other players
7507 of these games to run a Trojan horse program. With a
7508 set-group-id game the attacker only gets access to less
7509 important game data, and if they can get at the other
7510 players' accounts at all it will take considerably more
7514 Some packages, for example some fortune cookie programs, are
7515 configured by the upstream authors to install with their
7516 data files or other static information made unreadable so
7517 that they can only be accessed through set-id programs
7518 provided. You should not do this in a Debian package: anyone can
7519 download the <file>.deb</file> file and read the data from it,
7520 so there is no point making the files unreadable. Not
7521 making the files unreadable also means that you don't have
7522 to make so many programs set-id, which reduces the risk of a
7526 As described in the FHS, binaries of games should be
7527 installed in the directory <file>/usr/games</file>. This also
7528 applies to games that use the X Window System. Manual pages
7529 for games (X and non-X games) should be installed in
7530 <file>/usr/share/man/man6</file>.</p>
7534 <chapt id="docs"><heading>Documentation</heading>
7538 <heading>Manual pages</heading>
7541 You should install manual pages in <prgn>nroff</prgn> source
7542 form, in appropriate places under <file>/usr/share/man</file>.
7543 You should only use sections 1 to 9 (see the FHS for more
7544 details). You must not install a preformatted "cat page".
7548 Each program, utility, and function should have an
7549 associated manual page included in the same package. It is
7550 suggested that all configuration files also have a manual
7551 page included as well. Manual pages for protocols and other
7552 auxiliary things are optional.
7556 If no manual page is available, this is considered as a bug
7557 and should be reported to the Debian Bug Tracking System (the
7558 maintainer of the package is allowed to write this bug report
7559 themselves, if they so desire). Do not close the bug report
7560 until a proper manpage is available.<footnote>
7562 It is not very hard to write a man page. See the
7563 <url id="http://www.schweikhardt.net/man_page_howto.html"
7564 name="Man-Page-HOWTO">,
7565 <manref name="man" section="7">, the examples
7566 created by <prgn>debmake</prgn> or <prgn>dh_make</prgn>,
7567 the helper programs <prgn>help2man</prgn>, or the
7568 directory <file>/usr/share/doc/man-db/examples</file>.
7574 You may forward a complaint about a missing manpage to the
7575 upstream authors, and mark the bug as forwarded in the
7576 Debian bug tracking system. Even though the GNU Project do
7577 not in general consider the lack of a manpage to be a bug,
7578 we do; if they tell you that they don't consider it a bug
7579 you should leave the bug in our bug tracking system open
7584 Manual pages should be installed compressed using <tt>gzip -9</tt>.
7588 If one manpage needs to be accessible via several names it
7589 is better to use a symbolic link than the <file>.so</file>
7590 feature, but there is no need to fiddle with the relevant
7591 parts of the upstream source to change from <file>.so</file> to
7592 symlinks: don't do it unless it's easy. You should not
7593 create hard links in the manual page directories, nor put
7594 absolute filenames in <file>.so</file> directives. The filename
7595 in a <file>.so</file> in a manpage should be relative to the
7596 base of the manpage tree (usually
7597 <file>/usr/share/man</file>). If you do not create any links
7598 (whether symlinks, hard links, or <tt>.so</tt> directives)
7599 in the filesystem to the alternate names of the manpage,
7600 then you should not rely on <prgn>man</prgn> finding your
7601 manpage under those names based solely on the information in
7602 the manpage's header.<footnote>
7604 Supporting this in <prgn>man</prgn> often requires
7605 unreasonable processing time to find a manual page or to
7606 report that none exists, and moves knowledge into man's
7607 database that would be better left in the filesystem.
7608 This support is therefore deprecated and will cease to
7609 be present in the future.
7616 <heading>Info documents</heading>
7619 Info documents should be installed in <file>/usr/share/info</file>.
7620 They should be compressed with <tt>gzip -9</tt>.
7624 Your package should call <prgn>install-info</prgn> to update
7625 the Info <file>dir</file> file in its <prgn>postinst</prgn>
7626 script when called with a <tt>configure</tt> argument, for
7628 <example compact="compact">
7629 install-info --quiet --section Development Development \
7630 /usr/share/info/foobar.info
7634 It is a good idea to specify a section for the location of
7635 your program; this is done with the <tt>--section</tt>
7636 switch. To determine which section to use, you should look
7637 at <file>/usr/share/info/dir</file> on your system and choose the most
7638 relevant (or create a new section if none of the current
7639 sections are relevant). Note that the <tt>--section</tt>
7640 flag takes two arguments; the first is a regular expression
7641 to match (case-insensitively) against an existing section,
7642 the second is used when creating a new one.</p>
7645 You should remove the entries in the <prgn>prerm</prgn>
7646 script when called with a <tt>remove</tt> argument:
7647 <example compact="compact">
7648 install-info --quiet --remove /usr/share/info/foobar.info
7652 If <prgn>install-info</prgn> cannot find a description entry
7653 in the Info file you must supply one. See <manref
7654 name="install-info" section="8"> for details.</p>
7658 <heading>Additional documentation</heading>
7661 Any additional documentation that comes with the package may
7662 be installed at the discretion of the package maintainer.
7663 Text documentation should be installed in the directory
7664 <file>/usr/share/doc/<var>package</var></file>, where
7665 <var>package</var> is the name of the package, and
7666 compressed with <tt>gzip -9</tt> unless it is small.
7670 If a package comes with large amounts of documentation which
7671 many users of the package will not require you should create
7672 a separate binary package to contain it, so that it does not
7673 take up disk space on the machines of users who do not need
7674 or want it installed.</p>
7677 It is often a good idea to put text information files
7678 (<file>README</file>s, changelogs, and so forth) that come with
7679 the source package in <file>/usr/share/doc/<var>package</var></file>
7680 in the binary package. However, you don't need to install
7681 the instructions for building and installing the package, of
7685 Packages must not require the existance of any files in
7686 <file>/usr/share/doc/</file> in order to function
7689 The system administrator should be able to
7690 delete files in <file>/usr/share/doc/</file> without causing
7691 any programs to break.
7694 Any files that are referenced by programs but are also
7695 useful as standalone documentation should be installed under
7696 <file>/usr/share/<var>package</var>/</file> with symbolic links from
7697 <file>/usr/share/doc/<var>package</var></file>.
7701 <file>/usr/share/doc/<var>package</var></file> may be a symbolic
7702 link to another directory in <file>/usr/share/doc</file> only if
7703 the two packages both come from the same source and the
7704 first package Depends on the second.
7708 Former Debian releases placed all additional documentation
7709 in <file>/usr/doc/<var>package</var></file>. This has been
7710 changed to <file>/usr/share/doc/<var>package</var></file>,
7711 and packages must not put documentation in the directory
7712 <file>/usr/doc/<var>package</var></file>. <footnote>
7713 <p>At this phase of the transition, we no longer require a
7714 symbolic link in <file>/usr/doc/</file>. At a later point,
7715 policy shall change to make the symbolic links a bug.</p>
7721 <heading>Preferred documentation formats</heading>
7724 The unification of Debian documentation is being carried out
7728 If your package comes with extensive documentation in a
7729 markup format that can be converted to various other formats
7730 you should if possible ship HTML versions in a binary
7731 package, in the directory
7732 <file>/usr/share/doc/<var>appropriate-package</var></file> or
7733 its subdirectories.<footnote>
7735 The rationale: The important thing here is that HTML
7736 docs should be available in <em>some</em> package, not
7737 necessarily in the main binary package.
7743 Other formats such as PostScript may be provided at the
7744 package maintainer's discretion.
7748 <sect id="copyrightfile">
7749 <heading>Copyright information</heading>
7752 Every package must be accompanied by a verbatim copy of its
7753 copyright and distribution license in the file
7754 <file>/usr/share/doc/<var>package</var>/copyright</file>. This
7755 file must neither be compressed nor be a symbolic link.
7759 In addition, the copyright file must say where the upstream
7760 sources (if any) were obtained. It should name the original
7761 authors of the package and the Debian maintainer(s) who were
7762 involved with its creation.</p>
7765 A copy of the file which will be installed in
7766 <file>/usr/share/doc/<var>package</var>/copyright</file> should
7767 be in <file>debian/copyright</file> in the source package.
7771 <file>/usr/share/doc/<var>package</var></file> may be a symbolic
7772 link to another directory in <file>/usr/share/doc</file> only if
7773 the two packages both come from the same source and the
7774 first package Depends on the second. These rules are
7775 important because copyrights must be extractable by
7780 Packages distributed under the UCB BSD license, the Artistic
7781 license, the GNU GPL, and the GNU LGPL should refer to the
7782 files <file>/usr/share/common-licenses/BSD</file>,
7783 <file>/usr/share/common-licenses/Artistic</file>,
7784 <file>/usr/share/common-licenses/GPL</file>, and
7785 <file>/usr/share/common-licenses/LGPL</file> respectively,
7786 rather than quoting them in the copyright file.
7790 You should not use the copyright file as a general <file>README</file>
7791 file. If your package has such a file it should be
7792 installed in <file>/usr/share/doc/<var>package</var>/README</file> or
7793 <file>README.Debian</file> or some other appropriate place.</p>
7797 <heading>Examples</heading>
7800 Any examples (configurations, source files, whatever),
7801 should be installed in a directory
7802 <file>/usr/share/doc/<var>package</var>/examples</file>. These
7803 files should not be referenced by any program: they're there
7804 for the benefit of the system administrator and users as
7805 documentation only. Architecture-specific example files
7806 should be installed in a directory
7807 <file>/usr/lib/<var>package</var>/examples</file> with symbolic
7809 <file>/usr/share/doc/<var>package</var>/examples</file>, or the
7810 latter directory itself may be a symbolic link to the
7815 If the purpose of a package to provide examples, then the
7816 example files may be installed into
7817 <file>/usr/share/doc/<var>package</var></file>.
7821 <sect id="changelogs">
7822 <heading>Changelog files</heading>
7825 The Debian changelog file (<file>debian/changelog</file>) should
7826 explain briefly what modifications were made in the Debian version
7827 of the package compared to the upstream one. Other changes and
7828 updates to the package should also be documented in this file.
7832 Mistakes in changelogs are usually best rectified by
7833 making a new changelog entry rather than "rewriting history"
7834 by editing old changelog entries.
7838 The format of the <file>debian/changelog</file> file is described
7839 in <ref id="dpkgchangelog">. In non-experimental packages you must
7840 use a format for <file>debian/changelog</file> which is supported
7841 by the most recent released version of <prgn>dpkg</prgn>.<footnote>
7843 If you wish to use an alternative format, you may do so as
7844 long as you include a parser for it in your source package.
7845 The parser must have an API compatible with that expected by
7846 <prgn>dpkg-genchanges</prgn> and <prgn>dpkg-gencontrol</prgn>.
7847 If there is general interest in the new format, you should
7848 contact the <package>dpkg</package> maintainer to have the
7849 parser script for it included in the <prgn>dpkg</prgn>
7850 package. (You will need to agree that the parser and its
7851 manpage may be distributed under the GNU GPL, just as the rest
7852 of <prgn>dpkg</prgn> is.)
7858 Packages that are not Debian-native must contain a
7859 compressed copy of the <file>debian/changelog</file> file from
7860 the Debian source tree in
7861 <file>/usr/share/doc/<var>package</var></file> with the name
7862 <file>changelog.Debian.gz</file>.
7866 If an upstream changelog is available, it should be accessible as
7867 <file>/usr/share/doc/<var>package</var>/changelog.gz</file> in
7868 plain text. If the upstream changelog is distributed in
7869 HTML, it should be made available in that form as
7870 <file>/usr/share/doc/<var>package</var>/changelog.html.gz</file>
7871 and a plain text <file>changelog.gz</file> should be generated
7872 from it using, for example, <tt>lynx -dump -nolist</tt>. If
7873 the upstream changelog files do not already conform to this
7874 naming convention, then this may be achieved either by
7875 renaming the files, or by adding a symbolic link, at the
7876 maintainer's discretion.<footnote>
7878 Rationale: People should not have to look in places for
7879 upstream changelogs merely because they are given
7880 different names or are distributed in HTML format.
7886 All of these files should be installed compressed using
7887 <tt>gzip -9</tt>, as they will become large with time even
7888 if they start out small.
7892 If the package has only one changelog which is used both as
7893 the Debian changelog and the upstream one because there is
7894 no separate upstream maintainer then that changelog should
7895 usually be installed as
7896 <file>/usr/share/doc/<var>package</var>/changelog.gz</file>; if
7897 there is a separate upstream maintainer, but no upstream
7898 changelog, then the Debian changelog should still be called
7899 <file>changelog.Debian.gz</file>.</p>
7904 <appendix id="pkg-scope">
7905 <heading>Introduction and scope of these appendices</heading>
7908 These appendices are taken essentially verbatim from the
7909 now-deprecated Packaging Manual, version 3.2.1.0. They are
7910 the chapters which are likely to be of use to package
7911 maintainers and which have not already been included in the
7912 policy document itself. Most of these sections are very likely
7913 not relevant to policy; they should be treated as
7914 documentation for the packaging system. Please note that these
7915 appendices are included for convenience, and for historical
7916 reasons: they used to be part of policy package, and they have
7917 not yet been incorporated into dpkg documentation. However,
7918 they still have value, and hence they are presented here.
7921 They have not yet been checked to ensure that they are
7922 compatible with the contents of policy, and if there are any
7923 contradictions, the version in the main policy document takes
7924 precedence. The remaining chapters of the old Packaging
7925 Manual have also not been read in detail to ensure that there
7926 are not parts which have been left out. Both of these will be
7931 <prgn>dpkg</prgn> is a suite of programs for creating binary
7932 package files and installing and removing them on Unix
7935 <prgn>dpkg</prgn> is targetted primarily at Debian
7936 GNU/Linux, but may work on or be ported to other
7943 The binary packages are designed for the management of
7944 installed executable programs (usually compiled binaries) and
7945 their associated data, though source code examples and
7946 documentation are provided as part of some packages.</p>
7949 This manual describes the technical aspects of creating Debian
7950 binary packages (<file>.deb</file> files). It documents the
7951 behaviour of the package management programs
7952 <prgn>dpkg</prgn>, <prgn>dselect</prgn> et al. and the way
7953 they interact with packages.</p>
7956 It also documents the interaction between
7957 <prgn>dselect</prgn>'s core and the access method scripts it
7958 uses to actually install the selected packages, and describes
7959 how to create a new access method.</p>
7962 This manual does not go into detail about the options and
7963 usage of the package building and installation tools. It
7964 should therefore be read in conjuction with those programs'
7969 The utility programs which are provided with <prgn>dpkg</prgn>
7970 for managing various system configuration and similar issues,
7971 such as <prgn>update-rc.d</prgn> and
7972 <prgn>install-info</prgn>, are not described in detail here -
7973 please see their manpages.
7977 It does <em>not</em> describe the policy requirements imposed
7978 on Debian packages, such as the permissions on files and
7979 directories, documentation requirements, upload procedure, and
7980 so on. You should see the Debian packaging policy manual for
7981 these details. (Many of them will probably turn out to be
7982 helpful even if you don't plan to upload your package and make
7983 it available as part of the distribution.)
7987 It is assumed that the reader is reasonably familiar with the
7988 <prgn>dpkg</prgn> System Administrators' manual.
7989 Unfortunately this manual does not yet exist.
7993 The Debian version of the FSF's GNU hello program is provided
7994 as an example for people wishing to create Debian
7995 packages. The Debian <prgn>debmake</prgn> package is
7996 recommended as a very helpful tool in creating and maintaining
7997 Debian packages. However, while the tools and examples are
7998 helpful, they do not replace the need to read and follow the
7999 Policy and Programmer's Manual.</p>
8002 <appendix id="pkg-binarypkg"><heading>Binary packages (from old
8007 The binary package has two main sections. The first part
8008 consists of various control information files and scripts used
8009 by <prgn>dpkg</prgn> when installing and removing. See <ref
8010 id="pkg-controlarea">.
8014 The second part is an archive containing the files and
8015 directories to be installed.
8019 In the future binary packages may also contain other
8020 components, such as checksums and digital signatures. The
8021 format for the archive is described in full in the
8022 <file>deb(5)</file> manpage.
8026 <sect id="pkg-bincreating"><heading>Creating package files -
8027 <prgn>dpkg-deb</prgn>
8031 All manipulation of binary package files is done by
8032 <prgn>dpkg-deb</prgn>; it's the only program that has
8033 knowledge of the format. (<prgn>dpkg-deb</prgn> may be
8034 invoked by calling <prgn>dpkg</prgn>, as <prgn>dpkg</prgn>
8035 will spot that the options requested are appropriate to
8036 <prgn>dpkg-deb</prgn> and invoke that instead with the same
8041 In order to create a binary package you must make a
8042 directory tree which contains all the files and directories
8043 you want to have in the filesystem data part of the package.
8044 In Debian-format source packages this directory is usually
8045 <file>debian/tmp</file>, relative to the top of the package's
8050 They should have the locations (relative to the root of the
8051 directory tree you're constructing) ownerships and
8052 permissions which you want them to have on the system when
8057 With current versions of <prgn>dpkg</prgn> the uid/username
8058 and gid/groupname mappings for the users and groups being
8059 used should be the same on the system where the package is
8060 built and the one where it is installed.
8064 You need to add one special directory to the root of the
8065 miniature filesystem tree you're creating:
8066 <prgn>DEBIAN</prgn>. It should contain the control
8067 information files, notably the binary package control file
8068 (see <ref id="pkg-controlfile">).
8072 The <prgn>DEBIAN</prgn> directory will not appear in the
8073 filesystem archive of the package, and so won't be installed
8074 by <prgn>dpkg</prgn> when the package is installed.
8078 When you've prepared the package, you should invoke:
8080 dpkg --build <var>directory</var>
8085 This will build the package in
8086 <file><var>directory</var>.deb</file>. (<prgn>dpkg</prgn> knows
8087 that <tt>--build</tt> is a <prgn>dpkg-deb</prgn> option, so
8088 it invokes <prgn>dpkg-deb</prgn> with the same arguments to
8093 See the manpage <manref name="dpkg-deb" section="8"> for details of how
8094 to examine the contents of this newly-created file. You may find the
8095 output of following commands enlightening:
8097 dpkg-deb --info <var>filename</var>.deb
8098 dpkg-deb --contents <var>filename</var>.deb
8099 dpkg --contents <var>filename</var>.deb
8101 To view the copyright file for a package you could use this command:
8103 dpkg --fsys-tarfile <var>filename</var>.deb | tar xof usr/share/doc/<var>\*</var>copyright | less
8108 <sect id="pkg-controlarea">
8110 Package control information files
8114 The control information portion of a binary package is a
8115 collection of files with names known to <prgn>dpkg</prgn>.
8116 It will treat the contents of these files specially - some
8117 of them contain information used by <prgn>dpkg</prgn> when
8118 installing or removing the package; others are scripts which
8119 the package maintainer wants <prgn>dpkg</prgn> to run.
8123 It is possible to put other files in the package control
8124 area, but this is not generally a good idea (though they
8125 will largely be ignored).
8129 Here is a brief list of the control info files supported by
8130 <prgn>dpkg</prgn> and a summary of what they're used for.
8135 <tag><tt>control</tt>
8139 This is the key description file used by
8140 <prgn>dpkg</prgn>. It specifies the package's name
8141 and version, gives its description for the user,
8142 states its relationships with other packages, and so
8143 forth. See <ref id="pkg-controlfile">.
8147 It is usually generated automatically from information
8148 in the source package by the
8149 <prgn>dpkg-gencontrol</prgn> program, and with
8150 assistance from <prgn>dpkg-shlibdeps</prgn>. See <ref
8151 id="pkg-sourcetools">.</p>
8154 <tag><tt>postinst</tt>, <tt>preinst</tt>, <tt>postrm</tt>,
8160 These are exectuable files (usually scripts) which
8161 <prgn>dpkg</prgn> runs during installation, upgrade
8162 and removal of packages. They allow the package to
8163 deal with matters which are particular to that package
8164 or require more complicated processing than that
8165 provided by <prgn>dpkg</prgn>. Details of when and
8166 how they are called are in <ref
8167 id="maintainerscripts">.
8171 It is very important to make these scripts
8175 That means that if it runs successfully or fails
8176 and then you call it again it doesn't bomb out,
8177 but just ensures that everything is the way it
8180 </footnote> This is so that if an error occurs, the
8181 user interrupts <prgn>dpkg</prgn> or some other
8182 unforeseen circumstance happens you don't leave the
8183 user with a badly-broken package.
8187 The maintainer scripts are guaranteed to run with a
8188 controlling terminal and can interact with the user.
8189 If they need to prompt for passwords, do full-screen
8190 interaction or something similar you should do these
8191 things to and from <file>/dev/tty</file>, since
8192 <prgn>dpkg</prgn> will at some point redirect scripts'
8193 standard input and output so that it can log the
8194 installation process. Likewise, because these scripts
8195 may be executed with standard output redirected into a
8196 pipe for logging purposes, Perl scripts should set
8197 unbuffered output by setting <tt>$|=1</tt> so that the
8198 output is printed immediately rather than being
8203 Each script should return a zero exit status for
8204 success, or a nonzero one for failure.</p>
8207 <tag><tt>conffiles</tt>
8212 This file contains a list of configuration files which
8213 are to be handled automatically by <prgn>dpkg</prgn>
8214 (see <ref id="pkg-conffiles">). Note that not necessarily
8215 every configuration file should be listed here.</p>
8218 <tag><tt>shlibs</tt>
8223 This file contains a list of the shared libraries
8224 supplied by the package, with dependency details for
8225 each. This is used by <prgn>dpkg-shlibdeps</prgn>
8226 when it determines what dependencies are required in a
8227 package control file. The <tt>shlibs</tt> file format
8228 is described on <ref id="shlibs">.
8234 <sect id="pkg-controlfile">
8236 The main control information file: <tt>control</tt>
8239 The most important control information file used by
8240 <prgn>dpkg</prgn> when it installs a package is
8241 <tt>control</tt>. It contains all the package"s "vital
8246 The binary package control files of packages built from
8247 Debian sources are made by a special tool,
8248 <prgn>dpkg-gencontrol</prgn>, which reads
8249 <file>debian/control</file> and <file>debian/changelog</file> to
8250 find the information it needs. See <ref id="pkg-sourcepkg"> for
8255 The fields in binary package control files are:
8256 <list compact="compact">
8258 <p><qref id="pkg-f-Package"><tt>Package</tt></qref> (mandatory)</p>
8261 <p><qref id="versions"><tt>Version</tt></qref> (mandatory)</p>
8263 <item><p><qref id="pkg-f-Architecture"><tt>Architecture</tt></qref>
8267 This field should appear in all packages, though
8268 <prgn>dpkg</prgn> doesn't require it yet so that
8269 old packages can still be installed.
8275 <p><qref id="relationships"><tt>Depends</tt>,
8276 <tt>Provides</tt> et al.</qref></p>
8279 <p><qref id="pkg-f-Essential"><tt>Essential</tt></qref></p>
8282 <p><qref id="pkg-f-Maintainer"><tt>Maintainer</tt></qref></p>
8285 <p><qref id="pkg-f-classification"><tt>Section</tt>,
8286 <tt>Priority</tt></qref></p>
8289 <p><qref id="pkg-f-Source"><tt>Source</tt></qref></p>
8292 <p><qref id="descriptions"><tt>Description</tt></qref></p>
8296 <qref id="pkg-f-Installed-Size"><tt>Installed-Size</tt></qref>
8302 A description of the syntax of control files and the purpose
8303 of these fields is available in <ref id="pkg-controlfields">.
8308 <heading>Time Stamps</heading>
8310 Maintainers are encouraged to preserve the modification
8311 times of the upstream source files in a package, as far as
8312 is reasonably possible.
8315 The rationale is that there is some information conveyed
8316 by knowing the age of the file, for example, you could
8317 recognize that some documentation is very old by looking
8318 at the modification time, so it would be nice if the
8319 modification time of the upstream source would be
8327 <appendix id="pkg-sourcepkg">
8328 <heading>Source packages (from old Packaging Manual) </heading>
8331 The Debian binary packages in the distribution are generated
8332 from Debian sources, which are in a special format to assist
8333 the easy and automatic building of binaries.
8337 There was a previous version of the Debian source format,
8338 which is now being phased out. Instructions for converting an
8339 old-style package are given in the Debian policy manual.
8342 <sect id="pkg-sourcetools">
8343 <heading>Tools for processing source packages</heading>
8346 Various tools are provided for manipulating source packages;
8347 they pack and unpack sources and help build of binary
8348 packages and help manage the distribution of new versions.
8352 They are introduced and typical uses described here; see
8353 <manref name="dpkg-source" section="1"> for full
8354 documentation about their arguments and operation.
8358 For examples of how to construct a Debian source package,
8359 and how to use those utilities that are used by Debian
8360 source packages, please see the <prgn>hello</prgn> example
8366 <prgn>dpkg-source</prgn> - packs and unpacks Debian source
8371 This program is frequently used by hand, and is also
8372 called from package-independent automated building scripts
8373 such as <prgn>dpkg-buildpackage</prgn>.
8377 To unpack a package it is typically invoked with
8379 dpkg-source -x <var>.../path/to/filename</var>.dsc
8384 with the <file><var>filename</var>.tar.gz</file> and
8385 <file><var>filename</var>.diff.gz</file> (if applicable) in
8386 the same directory. It unpacks into
8387 <file><var>package</var>-<var>version</var></file>, and if
8389 <file><var>package</var>-<var>version</var>.orig</file>, in
8390 the current directory.
8394 To create a packed source archive it is typically invoked:
8396 dpkg-source -b <var>package</var>-<var>version</var>
8401 This will create the <file>.dsc</file>, <file>.tar.gz</file> and
8402 <file>.diff.gz</file> (if appropriate) in the current
8403 directory. <prgn>dpkg-source</prgn> does not clean the
8404 source tree first - this must be done separately if it is
8409 See also <ref id="pkg-sourcearchives">.</p>
8415 <prgn>dpkg-buildpackage</prgn> - overall package-building
8420 <prgn>dpkg-buildpackage</prgn> is a script which invokes
8421 <prgn>dpkg-source</prgn>, the <file>debian/rules</file>
8422 targets <tt>clean</tt>, <tt>build</tt> and
8423 <tt>binary</tt>, <prgn>dpkg-genchanges</prgn> and
8424 <prgn>pgp</prgn> to build a signed source and binary
8429 It is usually invoked by hand from the top level of the
8430 built or unbuilt source directory. It may be invoked with
8431 no arguments; useful arguments include:
8432 <taglist compact="compact">
8433 <tag><tt>-uc</tt>, <tt>-us</tt></tag>
8436 Do not PGP-sign the <tt>.changes</tt> file or the
8437 source package <tt>.dsc</tt> file, respectively.</p>
8439 <tag><tt>-p<var>pgp-command</var></tt></tag>
8442 Invoke <var>pgp-command</var> instead of finding
8443 <tt>pgp</tt> on the <prgn>PATH</prgn>.
8444 <var>pgp-command</var> must behave just like
8445 <prgn>pgp</prgn>.</p>
8447 <tag><tt>-r<var>root-command</var></tt></tag>
8450 When root privilege is required, invoke the command
8451 <var>root-command</var>. <var>root-command</var>
8452 should invoke its first argument as a command, from
8453 the <prgn>PATH</prgn> if necessary, and pass its
8454 second and subsequent arguments to the command it
8455 calls. If no <var>root-command</var> is supplied
8456 then <var>dpkg-buildpackage</var> will take no
8457 special action to gain root privilege, so that for
8458 most packages it will have to be invoked as root to
8461 <tag><tt>-b</tt>, <tt>-B</tt></tag>
8464 Two types of binary-only build and upload - see
8465 <manref name="dpkg-source" section="1">.
8474 <prgn>dpkg-gencontrol</prgn> - generates binary package
8479 This program is usually called from <file>debian/rules</file>
8480 (see <ref id="pkg-sourcetree">) in the top level of the source
8485 This is usually done just before the files and directories in the
8486 temporary directory tree where the package is being built have their
8487 permissions and ownerships set and the package is constructed using
8488 <prgn>dpkg-deb/</prgn>
8491 This is so that the control file which is produced has
8492 the right permissions
8498 <prgn>dpkg-gencontrol</prgn> must be called after all the
8499 files which are to go into the package have been placed in
8500 the temporary build directory, so that its calculation of
8501 the installed size of a package is correct.
8505 It is also necessary for <prgn>dpkg-gencontrol</prgn> to
8506 be run after <prgn>dpkg-shlibdeps</prgn> so that the
8507 variable substitutions created by
8508 <prgn>dpkg-shlibdeps</prgn> in <file>debian/substvars</file>
8513 For a package which generates only one binary package, and
8514 which builds it in <file>debian/tmp</file> relative to the top
8515 of the source package, it is usually sufficient to call
8516 <prgn>dpkg-gencontrol</prgn>.
8520 Sources which build several binaries will typically need
8523 dpkg-gencontrol -Pdebian/tmp-<var>pkg</var> -p<var>package</var>
8524 </example> The <tt>-P</tt> tells
8525 <prgn>dpkg-gencontrol</prgn> that the package is being
8526 built in a non-default directory, and the <tt>-p</tt>
8527 tells it which package's control file should be generated.
8531 <prgn>dpkg-gencontrol</prgn> also adds information to the
8532 list of files in <file>debian/files</file>, for the benefit of
8533 (for example) a future invocation of
8534 <prgn>dpkg-genchanges</prgn>.</p>
8539 <prgn>dpkg-shlibdeps</prgn> - calculates shared library
8544 This program is usually called from <file>debian/rules</file>
8545 just before <prgn>dpkg-gencontrol</prgn> (see <ref
8546 id="pkg-sourcetree">), in the top level of the source tree.
8550 Its arguments are executables.
8553 In a forthcoming dpkg version,
8554 <prgn>dpkg-shlibdeps</prgn> would be required to be
8555 called on shared libraries as well.
8558 They may be specified either in the locations in the
8559 source tree where they are created or in the locations
8560 in the temporary build tree where they are installed
8561 prior to binary package creation.
8563 </footnote> for which shared library dependencies should
8564 be included in the binary package's control file.
8568 If some of the found shared libraries should only
8569 warrant a <tt>Recommends</tt> or <tt>Suggests</tt>, or if
8570 some warrant a <tt>Pre-Depends</tt>, this can be achieved
8571 by using the <tt>-d<var>dependency-field</var></tt> option
8572 before those executable(s). (Each <tt>-d</tt> option
8573 takes effect until the next <tt>-d</tt>.)
8577 <prgn>dpkg-shlibdeps</prgn> does not directly cause the
8578 output control file to be modified. Instead by default it
8579 adds to the <file>debian/substvars</file> file variable
8580 settings like <tt>shlibs:Depends</tt>. These variable
8581 settings must be referenced in dependency fields in the
8582 appropriate per-binary-package sections of the source
8587 For example, the <prgn>procps</prgn> package generates two
8588 kinds of binaries, simple C binaries like <prgn>ps</prgn>
8589 which require a predependency and full-screen ncurses
8590 binaries like <prgn>top</prgn> which require only a
8591 recommendation. It can say in its <file>debian/rules</file>:
8593 dpkg-shlibdeps -dPre-Depends ps -dRecommends top
8595 and then in its main control file <file>debian/control</file>:
8599 Pre-Depends: ${shlibs:Pre-Depends}
8600 Recommends: ${shlibs:Recommends}
8606 Sources which produce several binary packages with
8607 different shared library dependency requirements can use
8608 the <tt>-p<var>varnameprefix</var></tt> option to override
8609 the default <tt>shlibs:</tt> prefix (one invocation of
8610 <prgn>dpkg-shlibdeps</prgn> per setting of this option).
8611 They can thus produce several sets of dependency
8612 variables, each of the form
8613 <tt><var>varnameprefix</var>:<var>dependencyfield</var></tt>,
8614 which can be referred to in the appropriate parts of the
8615 binary package control files.
8622 <prgn>dpkg-distaddfile</prgn> - adds a file to
8623 <file>debian/files</file>
8627 Some packages' uploads need to include files other than
8628 the source and binary package files.
8632 <prgn>dpkg-distaddfile</prgn> adds a file to the
8633 <file>debian/files</file> file so that it will be included in
8634 the <file>.changes</file> file when
8635 <prgn>dpkg-genchanges</prgn> is run.
8639 It is usually invoked from the <tt>binary</tt> target of
8640 <file>debian/rules</file>:
8642 dpkg-distaddfile <var>filename</var> <var>section</var> <var>priority</var>
8644 The <var>filename</var> is relative to the directory where
8645 <prgn>dpkg-genchanges</prgn> will expect to find it - this
8646 is usually the directory above the top level of the source
8647 tree. The <file>debian/rules</file> target should put the
8648 file there just before or just after calling
8649 <prgn>dpkg-distaddfile</prgn>.
8653 The <var>section</var> and <var>priority</var> are passed
8654 unchanged into the resulting <file>.changes</file> file. See
8655 <ref id="pkg-f-classification">.
8660 <sect1><heading><prgn>dpkg-genchanges</prgn> - generates a <file>.changes</file> upload
8665 This program is usually called by package-independent
8666 automatic building scripts such as
8667 <prgn>dpkg-buildpackage</prgn>, but it may also be called
8672 It is usually called in the top level of a built source
8673 tree, and when invoked with no arguments will print out a
8674 straightforward <file>.changes</file> file based on the
8675 information in the source package's changelog and control
8676 file and the binary and source packages which should have
8682 <sect1><heading><prgn>dpkg-parsechangelog</prgn> - produces parsed representation of
8687 This program is used internally by
8688 <prgn>dpkg-source</prgn> et al. It may also occasionally
8689 be useful in <file>debian/rules</file> and elsewhere. It
8690 parses a changelog, <file>debian/changelog</file> by default,
8691 and prints a control-file format representation of the
8692 information in it to standard output.
8696 <sect1 id="pkg-dpkgarch"><heading><prgn>dpkg-architecture</prgn> -
8697 information about the build and host system
8701 This program can be used manually, but is also invoked by
8702 <tt>dpkg-buildpackage</tt> or <file>debian/rules</file> to set
8703 to set environment or make variables which specify the build and
8704 host architecture for the package building process.
8709 <sect id="pkg-sourcetree"><heading>The Debianised source tree
8713 The source archive scheme described later is intended to
8714 allow a Debianised source tree with some associated control
8715 information to be reproduced and transported easily. The
8716 Debianised source tree is a version of the original program
8717 with certain files added for the benefit of the
8718 Debianisation process, and with any other changes required
8719 made to the rest of the source code and installation
8724 The extra files created for Debian are in the subdirectory
8725 <file>debian</file> of the top level of the Debianised source
8726 tree. They are described below.
8729 <sect1 id="pkg-debianrules"><heading><file>debian/rules</file> - the main building
8734 This file is an executable makefile, and contains the
8735 package-specific recipies for compiling the package and
8736 building binary package(s) out of the source.
8740 It must start with the line <tt>#!/usr/bin/make -f</tt>,
8741 so that it can be invoked by saying its name rather than
8742 invoking <prgn>make</prgn> explicitly.
8746 Since an interactive <file>debian/rules</file> script makes it
8747 impossible to autocompile that package and also makes it
8748 hard for other people to reproduce the same binary
8749 package, all <strong>required targets</strong> have to be
8750 non-interactive. At a minimul, required targets are the
8751 ones called by <prgn>dpkg-buildpackage</prgn>, namely,
8752 <em>clean</em>, <em>binary</em>, <em>binary-arch</em>, and
8753 <em>build</em>. It also follows that any target that these
8754 targets depend on must also be non-interactive.
8758 The targets which are required to be present are:
8760 <tag><tt>build</tt></tag>
8763 This should perform all non-interactive
8764 configuration and compilation of the package. If a
8765 package has an interactive pre-build configuration
8766 routine, the Debianised source package should be
8767 built after this has taken place, so that it can be
8768 built without rerunning the configuration.
8772 A package may also provide both of the targets
8773 <tt>build-arch</tt> and <tt>build-indep</tt>. The
8774 <tt>build-arch</tt> target, if provided, should
8775 perform all non-interactive configuration and
8776 compilation required for producing all
8777 architecture-dependant binary packages (those packages
8778 for which the body of the <tt>Architecture</tt> field
8779 in <tt>debian/control</tt> is not <tt>all</tt>).
8780 Similarly, the <tt>build-indep</tt> target, if
8781 provided, should perform all non-interactive
8782 configuration and compilation required for producing
8783 all architecture-independent binary packages (those
8784 packages for which the body of the
8785 <tt>Architecture</tt> field in <tt>debian/control</tt>
8786 is <tt>all</tt>). The <tt>build</tt> target should
8787 depend on those of the targets <tt>build-arch</tt> and
8788 <tt>build-indep</tt> that are provided in the rules
8793 If one or both of the targets <tt>build-arch</tt> and
8794 <tt>build-indep</tt> are not provided, then invoking
8795 <file>debian/rules</file> with one of the not-provided
8796 targets as arguments should produce a exit status code
8797 of 2. Usually this is provided automatically by make
8798 if the target is missing.
8802 For some packages, notably ones where the same
8803 source tree is compiled in different ways to produce
8804 two binary packages, the <tt>build</tt> target does
8805 not make much sense. For these packages it is good
8806 enough to provide two (or more) targets
8807 (<tt>build-a</tt> and <tt>build-b</tt> or whatever)
8808 for each of the ways of building the package, and a
8809 <tt>build</tt> target that does nothing. The
8810 <tt>binary</tt> target will have to build the
8811 package in each of the possible ways and make the
8812 binary package out of each.
8816 The targets <tt>build</tt>, <tt>build-arch</tt>
8817 and <tt>build-indep</tt> target must not do
8818 anything that might require root privilege.
8822 The <tt>build</tt> target may need to run
8823 <tt>clean</tt> first - see below.
8827 When a package has a configuration routine that takes
8828 a long time, or when the makefiles are poorly
8829 designed, or when <tt>build</tt> needs to run
8830 <tt>clean</tt> first, it is a good idea to <tt>touch
8831 build</tt> when the build process is complete. This
8832 will ensure that if <tt>debian/rules build</tt> is run
8833 again it will not rebuild the whole program.
8837 <tag><tt>binary</tt>, <tt>binary-arch</tt>,
8838 <tt>binary-indep</tt>
8842 The <tt>binary</tt> target should be all that is
8843 necessary for the user to build the binary
8844 package. All these targets are required to be
8845 non-interactive. It is split into two parts:
8846 <tt>binary-arch</tt> builds the packages' output
8847 files which are specific to a particular
8848 architecture, and <tt>binary-indep</tt> builds
8849 those which are not.
8853 <tt>binary</tt> should usually be a target with
8854 no commands which simply depends on
8855 <prgn>binary-arch</prgn> and
8856 <prgn>binary-indep</prgn>.
8860 Both <prgn>binary-*</prgn> targets should depend on
8861 the <tt>build</tt> target, above, so that the
8862 package is built if it has not been already. It
8863 should then create the relevant binary package(s),
8864 using <prgn>dpkg-gencontrol</prgn> to make their
8865 control files and <prgn>dpkg-deb</prgn> to build
8866 them and place them in the parent of the top level
8871 If one of the <prgn>binary-*</prgn> targets has
8872 nothing to do (this will be always be the case if
8873 the source generates only a single binary package,
8874 whether architecture-dependent or not) it
8875 <em>must</em> still exist, but should always
8880 <ref id="pkg-binarypkg"> describes how to construct
8885 The <tt>binary</tt> targets must be invoked as
8890 <tag><tt>clean</tt></tag>
8894 This should undo any effects that the
8895 <tt>build</tt> and <tt>binary</tt> targets
8896 may have had, except that it should leave alone any
8897 output files created in the parent directory by a
8898 run of <tt>binary</tt>. This target is required
8899 to be non-interactive.
8903 If a <tt>build</tt> file is touched at the end
8904 of the <tt>build</tt> target, as suggested
8905 above, it must be removed as the first thing that
8906 <tt>clean</tt> does, so that running
8907 <tt>build</tt> again after an interrupted
8908 <tt>clean</tt> doesn't think that everything is
8913 The <tt>clean</tt> target must be invoked as
8914 root if <tt>binary</tt> has been invoked since
8915 the last <tt>clean</tt>, or if
8916 <tt>build</tt> has been invoked as root (since
8917 <tt>build</tt> may create directories, for
8922 <tag><tt>get-orig-source</tt> (optional)</tag>
8926 This target fetches the most recent version of the
8927 original source package from a canonical archive
8928 site (via FTP or WWW, for example), does any
8929 necessary rearrangement to turn it into the original
8930 source tarfile format described below, and leaves it
8931 in the current directory.
8935 This target may be invoked in any directory, and
8936 should take care to clean up any temporary files it
8941 This target is optional, but providing it if
8942 possible is a good idea.
8948 The <tt>build</tt>, <tt>binary</tt> and
8949 <tt>clean</tt> targets must be invoked with a current
8950 directory of the package's top-level directory.
8955 Additional targets may exist in <file>debian/rules</file>,
8956 either as published or undocumented interfaces or for the
8957 package's internal use.
8961 The architecture we build on and build for is determined by make
8962 variables via dpkg-architecture (see <ref id="pkg-dpkgarch">). You can
8963 get the Debian architecture and the GNU style architecture
8964 specification string for the build machine as well as the host
8965 machine. Here is a list of supported make variables:
8966 <list compact="compact">
8968 <p><tt>DEB_*_ARCH</tt> (the Debian architecture)</p>
8971 <p><tt>DEB_*_GNU_TYPE</tt> (the GNU style architecture
8972 specification string)</p>
8975 <p><tt>DEB_*_GNU_CPU</tt> (the CPU part of DEB_*_GNU_TYPE)</p>
8978 <p><tt>DEB_*_GNU_SYSTEM</tt> (the System part of
8984 where <tt>*</tt> is either <tt>BUILD</tt> for specification of
8985 the build machine or <tt>HOST</tt> for specification of the machine
8990 Backward compatibility can be provided in the rules file
8991 by setting the needed variables to suitable default
8992 values, please refer to the documentation of
8993 dpkg-architecture for details.
8997 It is important to understand that the <tt>DEB_*_ARCH</tt>
8998 string does only determine which Debian architecture we
8999 build on resp. for. It should not be used to get the CPU
9000 or System information, the GNU style variables should be
9006 <sect1><heading><file>debian/control</file>
9010 This file contains version-independent details about the
9011 source package and about the binary packages it creates.
9015 It is a series of sets of control fields, each
9016 syntactically similar to a binary package control file.
9017 The sets are separated by one or more blank lines. The
9018 first set is information about the source package in
9019 general; each subsequent set describes one binary package
9020 that the source tree builds.
9024 The syntax and semantics of the fields are described below
9025 in <ref id="pkg-controlfields">.
9029 The general (binary-package-independent) fields are:
9030 <list compact="compact">
9032 <p><qref id="pkg-f-Source"><tt>Source</tt></qref> (mandatory)</p>
9035 <p><qref id="pkg-f-Maintainer"><tt>Maintainer</tt></qref></p>
9039 <qref id="pkg-f-classification"><tt>Section</tt> and
9040 <tt>Priority</tt></qref>
9041 (classification, mandatory)
9046 <qref id="relationships"><tt>Build-Depends</tt> et
9047 al.</qref> (source package interrelationships)
9052 <qref id="pkg-f-Standards-Version"><tt>Standards-Version</tt></qref>
9058 The per-binary-package fields are:
9059 <list compact="compact">
9061 <p><qref id="pkg-f-Package"><tt>Package</tt></qref> (mandatory)</p>
9065 <qref id="pkg-f-Architecture"><tt>Architecture</tt></qref>
9069 <p><qref id="descriptions"><tt>Description</tt></qref></p>
9073 <qref id="pkg-f-classification"><tt>Section</tt> and
9074 <tt>Priority</tt></qref> (classification)</p>
9077 <p><qref id="pkg-f-Essential"><tt>Essential</tt></qref></p>
9081 <qref id="relationships"><tt>Depends</tt> et
9082 al.</qref> (binary package interrelationships)
9088 These fields are used by <prgn>dpkg-gencontrol</prgn> to
9089 generate control files for binary packages (see below), by
9090 <prgn>dpkg-genchanges</prgn> to generate the
9091 <tt>.changes</tt> file to accompany the upload, and by
9092 <prgn>dpkg-source</prgn> when it creates the <file>.dsc</file>
9093 source control file as part of a source archive.
9097 The fields here may contain variable references - their
9098 values will be substituted by
9099 <prgn>dpkg-gencontrol</prgn>, <prgn>dpkg-genchanges</prgn>
9100 or <prgn>dpkg-source</prgn> when they generate output
9101 control files. See <ref id="pkg-srcsubstvars"> for details.
9104 <p> <sect2><heading>User-defined fields
9108 Additional user-defined fields may be added to the
9109 source package control file. Such fields will be
9110 ignored, and not copied to (for example) binary or
9111 source package control files or upload control files.
9115 If you wish to add additional unsupported fields to
9116 these output files you should use the mechanism
9121 Fields in the main source control information file with
9122 names starting <tt>X</tt>, followed by one or more of
9123 the letters <tt>BCS</tt> and a hyphen <tt>-</tt>, will
9124 be copied to the output files. Only the part of the
9125 field name after the hyphen will be used in the output
9126 file. Where the letter <tt>B</tt> is used the field
9127 will appear in binary package control files, where the
9128 letter <tt>S</tt> is used in source package control
9129 files and where <tt>C</tt> is used in upload control
9130 (<tt>.changes</tt>) files.
9134 For example, if the main source information control file
9137 XBS-Comment: I stand between the candle and the star.
9139 then the binary and source package control files will contain the
9142 Comment: I stand between the candle and the star.
9149 <sect1 id="pkg-dpkgchangelog"><heading><file>debian/changelog</file>
9153 This file records the changes to the Debian-specific parts of the
9157 Though there is nothing stopping an author who is also
9158 the Debian maintainer from using it for all their
9159 changes, it will have to be renamed if the Debian and
9160 upstream maintainers become different
9167 It has a special format which allows the package building
9168 tools to discover which version of the package is being
9169 built and find out other release-specific information.
9173 That format is a series of entries like this:
9175 <var>package</var> (<var>version</var>) <var>distribution(s)</var>; urgency=<var>urgency</var>
9177 * <var>change details</var>
9178 <var>more change details</var>
9179 * <var>even more change details</var>
9181 -- <var>maintainer name and email address</var> <var>date</var>
9186 <var>package</var> and <var>version</var> are the source
9187 package name and version number.
9191 <var>distribution(s)</var> lists the distributions where
9192 this version should be installed when it is uploaded - it
9193 is copied to the <tt>Distribution</tt> field in the
9194 <tt>.changes</tt> file. See <ref id="pkg-f-Distribution">.
9198 <var>urgency</var> is the value for the <tt>Urgency</tt>
9199 field in the <file>.changes</file> file for the upload. See
9200 <ref id="pkg-f-Urgency">. It is not possible to specify an
9201 urgency containing commas; commas are used to separate
9202 <tt><var>keyword</var>=<var>value</var></tt> settings in
9203 the <prgn>dpkg</prgn> changelog format (though there is
9204 currently only one useful <var>keyword</var>,
9209 The change details may in fact be any series of lines
9210 starting with at least two spaces, but conventionally each
9211 change starts with an asterisk and a separating space and
9212 continuation lines are indented so as to bring them in
9213 line with the start of the text above. Blank lines may be
9214 used here to separate groups of changes, if desired.
9218 The maintainer name and email address should <em>not</em>
9219 necessarily be those of the usual package maintainer.
9220 They should be the details of the person doing
9221 <em>this</em> version. The information here will be
9222 copied to the <file>.changes</file> file, and then later used
9223 to send an acknowledgement when the upload has been
9228 The <var>date</var> should be in RFC822 format
9231 This is generated by the <prgn>822-date</prgn>
9234 </footnote>; it should include the timezone specified
9235 numerically, with the timezone name or abbreviation
9236 optionally present as a comment.
9240 The first "title" line with the package name should start
9241 at the left hand margin; the "trailer" line with the
9242 maintainer and date details should be preceded by exactly
9243 one space. The maintainer details and the date must be
9244 separated by exactly two spaces.
9248 An Emacs mode for editing this format is available: it is
9249 called <tt>debian-changelog-mode</tt>. You can have this
9250 mode selected automatically when you edit a Debian
9251 changelog by adding a local variables clause to the end of
9255 <sect2><heading>Defining alternative changelog formats
9259 It is possible to use a different format to the standard
9260 one, by providing a parser for the format you wish to
9265 In order to have <tt>dpkg-parsechangelog</tt> run your
9266 parser, you must include a line within the last 40 lines
9267 of your file matching the Perl regular expression:
9268 <tt>\schangelog-format:\s+([0-9a-z]+)\W</tt> The part in
9269 parentheses should be the name of the format. For
9270 example, you might say:
9272 @@@ changelog-format: joebloggs @@@
9274 Changelog format names are non-empty strings of alphanumerics.
9278 If such a line exists then <tt>dpkg-parsechangelog</tt>
9279 will look for the parser as
9280 <file>/usr/lib/dpkg/parsechangelog/<var>format-name</var></file>
9282 <file>/usr/local/lib/dpkg/parsechangelog/<var>format-name</var></file>;
9283 it is an error for it not to find it, or for it not to
9284 be an executable program. The default changelog format
9285 is <tt>dpkg</tt>, and a parser for it is provided with
9286 the <tt>dpkg</tt> package.
9290 The parser will be invoked with the changelog open on
9291 standard input at the start of the file. It should read
9292 the file (it may seek if it wishes) to determine the
9293 information required and return the parsed information
9294 to standard output in the form of a series of control
9295 fields in the standard format. By default it should
9296 return information about only the most recent version in
9297 the changelog; it should accept a
9298 <tt>-v<var>version</var></tt> option to return changes
9299 information from all versions present <em>strictly
9300 after</em> <var>version</var>, and it should then be an
9301 error for <var>version</var> not to be present in the
9307 <list compact="compact">
9309 <p><qref id="pkg-f-Source"><tt>Source</tt></qref></p>
9312 <p><qref id="versions"><tt>Version</tt></qref> (mandatory)</p>
9316 <qref id="pkg-f-Distribution"><tt>Distribution</tt></qref>
9321 <p><qref id="pkg-f-Urgency"><tt>Urgency</tt></qref> (mandatory)</p>
9325 <qref id="pkg-f-Maintainer"><tt>Maintainer</tt></qref>
9330 <p><qref id="pkg-f-Date"><tt>Date</tt></qref></p>
9334 <qref id="pkg-f-Changes"><tt>Changes</tt></qref>
9341 If several versions are being returned (due to the use
9342 of <tt>-v</tt>), the urgency value should be of the
9343 highest urgency code listed at the start of any of the
9344 versions requested followed by the concatenated
9345 (space-separated) comments from all the versions
9346 requested; the maintainer, version, distribution and
9347 date should always be from the most recent version.
9351 For the format of the <tt>Changes</tt> field see <ref
9352 id="pkg-f-Changes">.
9356 If the changelog format which is being parsed always or
9357 almost always leaves a blank line between individual
9358 change notes these blank lines should be stripped out,
9359 so as to make the resulting output compact.
9363 If the changelog format does not contain date or package
9364 name information this information should be omitted from
9365 the output. The parser should not attempt to synthesise
9366 it or find it from other sources.
9370 If the changelog does not have the expected format the
9371 parser should exit with a nonzero exit status, rather
9372 than trying to muddle through and possibly generating
9377 A changelog parser may not interact with the user at
9381 <!-- FIXME: section pkg-srcsubstvars is the same as srcsubstvars -->
9383 <sect1 id="pkg-srcsubstvars"><heading><file>debian/substvars</file>
9384 and variable substitutions
9388 When <prgn>dpkg-gencontrol</prgn>,
9389 <prgn>dpkg-genchanges</prgn> and <prgn>dpkg-source</prgn>
9390 generate control files they do variable substitutions on
9391 their output just before writing it. Variable
9392 substitutions have the form
9393 <tt>${<var>variable-name</var>}</tt>. The optional file
9394 <file>debian/substvars</file> contains variable substitutions
9395 to be used; variables can also be set directly from
9396 <file>debian/rules</file> using the <tt>-V</tt> option to the
9397 source packaging commands, and certain predefined
9398 variables are available.
9402 This file is usually generated and modified dynamically by
9403 <file>debian/rules</file> targets, in which case it must be
9404 removed by the <tt>clean</tt> target.
9408 See <manref name="dpkg-source" section="1"> for full
9409 details about source variable substitutions, including the
9410 format of <file>debian/substvars</file>.</p>
9413 <sect1><heading><file>debian/files</file>
9417 This file is not a permanent part of the source tree; it
9418 is used while building packages to record which files are
9419 being generated. <prgn>dpkg-genchanges</prgn> uses it
9420 when it generates a <file>.changes</file> file.
9424 It should not exist in a shipped source package, and so it
9425 (and any backup files or temporary files such as
9426 <file>files.new</file>
9429 <file>files.new</file> is used as a temporary file by
9430 <prgn>dpkg-gencontrol</prgn> and
9431 <prgn>dpkg-distaddfile</prgn> - they write a new
9432 version of <file>files</file> here before renaming it,
9433 to avoid leaving a corrupted copy if an error
9436 </footnote>) should be removed by the
9437 <tt>clean</tt> target. It may also be wise to
9438 ensure a fresh start by emptying or removing it at the
9439 start of the <tt>binary</tt> target.
9443 <prgn>dpkg-gencontrol</prgn> adds an entry to this file
9444 for the <file>.deb</file> file that will be created by
9445 <prgn>dpkg-deb</prgn> from the control file that it
9446 generates, so for most packages all that needs to be done
9447 with this file is to delete it in <tt>clean</tt>.
9451 If a package upload includes files besides the source
9452 package and any binary packages whose control files were
9453 made with <prgn>dpkg-gencontrol</prgn> then they should be
9454 placed in the parent of the package's top-level directory
9455 and <prgn>dpkg-distaddfile</prgn> should be called to add
9456 the file to the list in <file>debian/files</file>.</p>
9459 <sect1><heading><file>debian/tmp</file>
9463 This is the canonical temporary location for the
9464 construction of binary packages by the <tt>binary</tt>
9465 target. The directory <file>tmp</file> serves as the root of
9466 the filesystem tree as it is being constructed (for
9467 example, by using the package's upstream makefiles install
9468 targets and redirecting the output there), and it also
9469 contains the <tt>DEBIAN</tt> subdirectory. See <ref
9470 id="pkg-bincreating">.
9474 If several binary packages are generated from the same
9475 source tree it is usual to use several
9476 <file>debian/tmp<var>something</var></file> directories, for
9477 example <file>tmp-a</file> or <file>tmp-doc</file>.
9481 Whatever <file>tmp</file> directories are created and used by
9482 <tt>binary</tt> must of course be removed by the
9483 <tt>clean</tt> target.</p></sect1>
9487 <sect id="pkg-sourcearchives"><heading>Source packages as archives
9491 As it exists on the FTP site, a Debian source package
9492 consists of three related files. You must have the right
9493 versions of all three to be able to use them.
9498 <tag>Debian source control file - <tt>.dsc</tt></tag>
9502 This file contains a series of fields, identified and
9503 separated just like the fields in the control file of
9504 a binary package. The fields are listed below; their
9505 syntax is described above, in <ref id="pkg-controlfields">.
9506 <list compact="compact">
9508 <p><qref id="pkg-f-Source"><tt>Source</tt></qref></p>
9511 <p><qref id="versions"><tt>Version</tt></qref></p>
9514 <p><qref id="pkg-f-Maintainer"><tt>Maintainer</tt></qref></p>
9517 <p><qref id="pkg-f-Binary"><tt>Binary</tt></qref></p>
9520 <p><qref id="pkg-f-Architecture"><tt>Architecture</tt></qref></p>
9524 <qref id="relationships"><tt>Build-Depends</tt> et
9525 al.</qref> (source package interrelationships)
9530 <qref id="pkg-f-Standards-Version"><tt>Standards-Version</tt></qref></p>
9533 <p><qref id="pkg-f-Files"><tt>Files</tt></qref></p>
9538 The source package control file is generated by
9539 <prgn>dpkg-source</prgn> when it builds the source
9540 archive, from other files in the source package,
9541 described above. When unpacking it is checked against
9542 the files and directories in the other parts of the
9543 source package, as described below.</p>
9547 Original source archive -
9549 <var>package</var>_<var>upstream-version</var>.orig.tar.gz
9556 This is a compressed (with <tt>gzip -9</tt>)
9557 <prgn>tar</prgn> file containing the source code from
9558 the upstream authors of the program. The tarfile
9559 unpacks into a directory
9560 <file><var>package</var>-<var>upstream-version</var>.orig</file>,
9561 and does not contain files anywhere other than in
9562 there or in its subdirectories.</p>
9566 Debianisation diff -
9568 <var>package</var>_<var>upstream_version-revision</var>.diff.gz
9574 This is a unified context diff (<tt>diff -u</tt>)
9575 giving the changes which are required to turn the
9576 original source into the Debian source. These changes
9577 may only include editing and creating plain files.
9578 The permissions of files, the targets of symbolic
9579 links and the characteristics of special files or
9580 pipes may not be changed and no files may be removed
9585 All the directories in the diff must exist, except the
9586 <file>debian</file> subdirectory of the top of the source
9587 tree, which will be created by
9588 <prgn>dpkg-source</prgn> if necessary when unpacking.
9592 The <prgn>dpkg-source</prgn> program will
9593 automatically make the <file>debian/rules</file> file
9594 executable (see below).</p></item>
9599 If there is no original source code - for example, if the
9600 package is specially prepared for Debian or the Debian
9601 maintainer is the same as the upstream maintainer - the
9602 format is slightly different: then there is no diff, and the
9604 <file><var>package</var>_<var>version</var>.tar.gz</file> and
9605 contains a directory
9606 <file><var>package</var>-<var>version</var></file>.
9610 <sect><heading>Unpacking a Debian source package without
9611 <prgn>dpkg-source</prgn>
9615 <tt>dpkg-source -x</tt> is the recommended way to unpack a
9616 Debian source package. However, if it is not available it
9617 is possible to unpack a Debian source archive as follows:
9618 <enumlist compact="compact">
9621 Untar the tarfile, which will create a <file>.orig</file>
9625 <p>Rename the <file>.orig</file> directory to
9626 <file><var>package</var>-<var>version</var></file>.</p>
9630 Create the subdirectory <file>debian</file> at the top of
9631 the source tree.</p>
9633 <item><p>Apply the diff using <tt>patch -p0</tt>.</p>
9635 <item><p>Untar the tarfile again if you want a copy of the original
9636 source code alongside the Debianised version.</p>
9641 It is not possible to generate a valid Debian source archive
9642 without using <prgn>dpkg-source</prgn>. In particular,
9643 attempting to use <prgn>diff</prgn> directly to generate the
9644 <file>.diff.gz</file> file will not work.
9647 <sect1><heading>Restrictions on objects in source packages
9651 The source package may not contain any hard links
9654 This is not currently detected when building source
9655 packages, but only when extracting
9661 Hard links may be permitted at some point in the
9662 future, but would require a fair amount of
9665 </footnote>, device special files, sockets or setuid or
9669 Setgid directories are allowed.
9675 The source packaging tools manage the changes between the
9676 original and Debianised source using <prgn>diff</prgn> and
9677 <prgn>patch</prgn>. Turning the original source tree as
9678 included in the <file>.orig.tar.gz</file> into the debianised
9679 source must not involve any changes which cannot be
9680 handled by these tools. Problematic changes which cause
9681 <prgn>dpkg-source</prgn> to halt with an error when
9682 building the source package are:
9683 <list compact="compact">
9684 <item><p>Adding or removing symbolic links, sockets or pipes.</p>
9686 <item><p>Changing the targets of symbolic links.</p>
9688 <item><p>Creating directories, other than <file>debian</file>.</p>
9690 <item><p>Changes to the contents of binary files.</p></item>
9691 </list> Changes which cause <prgn>dpkg-source</prgn> to
9692 print a warning but continue anyway are:
9693 <list compact="compact">
9696 Removing files, directories or symlinks.
9699 Renaming a file is not treated specially - it is
9700 seen as the removal of the old file (which
9701 generates a warning, but is otherwise ignored),
9702 and the creation of the new
9709 Changed text files which are missing the usual final
9710 newline (either in the original or the modified
9715 Changes which are not represented, but which are not detected by
9716 <prgn>dpkg-source</prgn>, are:
9717 <list compact="compact">
9718 <item><p>Changing the permissions of files (other than
9719 <file>debian/rules</file>) and directories.</p></item>
9724 The <file>debian</file> directory and <file>debian/rules</file>
9725 are handled specially by <prgn>dpkg-source</prgn> - before
9726 applying the changes it will create the <file>debian</file>
9727 directory, and afterwards it will make
9728 <file>debian/rules</file> world-exectuable.
9734 <appendix id="pkg-controlfields"><heading>Control files and their
9735 fields (from old Packaging Manual)
9739 Many of the tools in the <prgn>dpkg</prgn> suite manipulate
9740 data in a common format, known as control files. Binary and
9741 source packages have control data as do the <file>.changes</file>
9742 files which control the installation of uploaded files, and
9743 <prgn>dpkg</prgn>'s internal databases are in a similar
9747 <sect><heading>Syntax of control files
9751 A file consists of one or more paragraphs of fields. The
9752 paragraphs are separated by blank lines. Some control files
9753 only allow one paragraph; others allow several, in which
9754 case each paragraph often refers to a different package.
9758 Each paragraph is a series of fields and values; each field
9759 consists of a name, followed by a colon and the value. It
9760 ends at the end of the line. Horizontal whitespace (spaces
9761 and tabs) may occur before or after the value and is ignored
9762 there; it is conventional to put a single space after the
9767 Some fields' values may span several lines; in this case
9768 each continuation line <em>must</em> start with a space or
9769 tab. Any trailing spaces or tabs at the end of individual
9770 lines of a field value are ignored.
9774 Except where otherwise stated only a single line of data is
9775 allowed and whitespace is not significant in a field body.
9776 Whitespace may never appear inside names (of packages,
9777 architectures, files or anything else), version numbers or
9778 in between the characters of multi-character version
9783 Field names are not case-sensitive, but it is usual to
9784 capitalise the field names using mixed case as shown below.
9788 Blank lines, or lines consisting only of spaces and tabs,
9789 are not allowed within field values or between fields - that
9790 would mean a new paragraph.
9794 It is important to note that there are several fields which
9795 are optional as far as <prgn>dpkg</prgn> and the related
9796 tools are concerned, but which must appear in every Debian
9797 package, or whose omission may cause problems. When writing
9798 the control files for Debian packages you <em>must</em> read
9799 the Debian policy manual in conjuction with the details
9800 below and the list of fields for the particular file.</p>
9803 <sect><heading>List of fields
9806 <sect1 id="pkg-f-Package"><heading><tt>Package</tt>
9810 The name of the binary package. Package names consist of
9811 the alphanumerics and <tt>+</tt> <tt>-</tt> <tt>.</tt>
9812 (plus, minus and full stop).
9815 The characters <tt>@</tt> <tt>:</tt> <tt>=</tt>
9816 <tt>%</tt> <tt>_</tt> (at, colon, equals, percent
9817 and underscore) used to be legal and are still
9818 accepted when found in a package file, but may not be
9819 used in new packages
9825 They must be at least two characters and must start with
9826 an alphanumeric. In current versions of dpkg they are
9827 sort of case-sensitive<footnote><p>This is a
9828 bug.</p></footnote>; use lowercase package names unless
9829 the package you're building (or referring to, in other
9830 fields) is already using uppercase.</p>
9833 <sect1 id="pkg-f-Version"><heading><tt>Version</tt>
9837 This lists the source or binary package's version number -
9838 see <ref id="versions">.
9843 <sect1 id="pkg-f-Architecture"><heading><tt>Architecture</tt>
9847 This is the architecture string; it is a single word for
9848 the Debian architecture.
9852 <prgn>dpkg</prgn> will check the declared architecture of
9853 a binary package against its own compiled-in value before
9858 The special value <tt>all</tt> indicates that the package
9859 is architecture-independent.
9863 In the main <file>debian/control</file> file in the source
9864 package, or in the source package control file
9865 <file>.dsc</file>, a list of architectures (separated by
9866 spaces) is also allowed, as is the special value
9867 <tt>any</tt>. A list indicates that the source will build
9868 an architecture-dependent package, and will only work
9869 correctly on the listed architectures. <tt>any</tt>
9870 indicates that though the source package isn't dependent
9871 on any particular architecture and should compile fine on
9872 any one, the binary package(s) produced are not
9873 architecture-independent but will instead be specific to
9874 whatever the current build architecture is.
9878 In a <file>.changes</file> file the <tt>Architecture</tt>
9879 field lists the architecture(s) of the package(s)
9880 currently being uploaded. This will be a list; if the
9881 source for the package is being uploaded too the special
9882 entry <tt>source</tt> is also present.
9886 See <ref id="pkg-debianrules"> for information how to get the
9887 architecture for the build process.
9891 <sect1 id="pkg-f-Maintainer"><heading><tt>Maintainer</tt>
9895 The package maintainer's name and email address. The name
9896 should come first, then the email address inside angle
9897 brackets <tt><></tt> (in RFC822 format).
9901 If the maintainer's name contains a full stop then the
9902 whole field will not work directly as an email address due
9903 to a misfeature in the syntax specified in RFC822; a
9904 program using this field as an address must check for this
9905 and correct the problem if necessary (for example by
9906 putting the name in round brackets and moving it to the
9907 end, and bringing the email address forward).
9911 In a <file>.changes</file> file or parsed changelog data this
9912 contains the name and email address of the person
9913 responsible for the particular version in question - this
9914 may not be the package's usual maintainer.
9918 This field is usually optional in as far as the
9919 <prgn>dpkg</prgn> are concerned, but its absence when
9920 building packages usually generates a warning.</p>
9923 <sect1 id="pkg-f-Source"><heading><tt>Source</tt>
9927 This field identifies the source package name.
9931 In a main source control information or a
9932 <file>.changes</file> or <file>.dsc</file> file or parsed
9933 changelog data this may contain only the name of the
9938 In the control file of a binary package (or in a
9939 <file>Packages</file> file) it may be followed by a version
9940 number in parentheses.
9943 It is usual to leave a space after the package name if
9944 a version number is specified.
9946 </footnote> This version number may be omitted (and is, by
9947 <prgn>dpkg-gencontrol</prgn>) if it has the same value as
9948 the <tt>Version</tt> field of the binary package in
9949 question. The field itself may be omitted from a binary
9950 package control file when the source package has the same
9951 name and version as the binary package.
9955 <sect1><heading>Package interrelationship fields:
9956 <tt>Depends</tt>, <tt>Pre-Depends</tt>,
9957 <tt>Recommends</tt> <tt>Suggests</tt>, <tt>Conflicts</tt>,
9958 <tt>Provides</tt>, <tt>Replaces</tt>
9962 These fields describe the package's relationships with
9963 other packages. Their syntax and semantics are described
9964 in <ref id="relationships">.</p>
9967 <sect1 id="pkg-f-Description"><heading><tt>Description</tt>
9971 In a binary package <tt>Packages</tt> file or main source
9972 control file this field contains a description of the
9973 binary package, in a special format. See <ref
9974 id="descriptions"> for details.
9978 In a <file>.changes</file> file it contains a summary of the
9979 descriptions for the packages being uploaded. The part of
9980 the field before the first newline is empty; thereafter
9981 each line has the name of a binary package and the summary
9982 description line from that binary package. Each line is
9983 indented by one space.</p>
9986 <sect1 id="pkg-f-Essential"><heading><tt>Essential</tt>
9990 This is a boolean field which may occur only in the
9991 control file of a binary package (or in the
9992 <file>Packages</file> file) or in a per-package fields
9993 paragraph of a main source control data file.
9997 If set to <tt>yes</tt> then <prgn>dpkg</prgn> and
9998 <prgn>dselect</prgn> will refuse to remove the package
9999 (though it can be upgraded and/or replaced). The other
10000 possible value is <tt>no</tt>, which is the same as not
10001 having the field at all.</p>
10004 <sect1 id="pkg-f-classification"><heading><tt>Section</tt> and
10009 These two fields classify the package. The
10010 <tt>Priority</tt> represents how important that it is that
10011 the user have it installed; the <tt>Section</tt>
10012 represents an application area into which the package has
10017 When they appear in the <file>debian/control</file> file these
10018 fields give values for the section and priority subfields
10019 of the <tt>Files</tt> field of the <file>.changes</file> file,
10020 and give defaults for the section and priority of the
10025 The section and priority are represented, though not as
10026 separate fields, in the information for each file in the
10027 <qref id="pkg-f-Files"><tt>-File</tt></qref>field of a
10028 <file>.changes</file> file. The section value in a
10029 <file>.changes</file> file is used to decide where to install
10030 a package in the FTP archive.
10034 These fields are not used by by <prgn>dpkg</prgn> proper,
10035 but by <prgn>dselect</prgn> when it sorts packages and
10036 selects defaults. See the Debian policy manual for the
10037 priorities in use and the criteria for selecting the
10038 priority for a Debian package, and look at the Debian FTP
10039 archive for a list of currently in-use priorities.
10043 These fields may appear in binary package control files,
10044 in which case they provide a default value in case the
10045 <file>Packages</file> files are missing the information.
10046 <prgn>dpkg</prgn> and <prgn>dselect</prgn> will only use
10047 the value from a <file>.deb</file> file if they have no other
10048 information; a value listed in a <file>Packages</file> file
10049 will always take precedence. By default
10050 <prgn>dpkg-gencontrol</prgn> does not include the section
10051 and priority in the control file of a binary package - use
10052 the <tt>-isp</tt>, <tt>-is</tt> or <tt>-ip</tt> options to
10053 achieve this effect.</p>
10056 <sect1 id="pkg-f-Binary"><heading><tt>Binary</tt>
10060 This field is a list of binary packages.
10064 When it appears in the <file>.dsc</file> file it is the list
10065 of binary packages which a source package can produce. It
10066 does not necessarily produce all of these binary packages
10067 for every architecture. The source control file doesn't
10068 contain details of which architectures are appropriate for
10069 which of the binary packages.
10073 When it appears in a <file>.changes</file> file it lists the
10074 names of the binary packages actually being uploaded.
10078 The syntax is a list of binary packages separated by
10082 A space after each comma is conventional.
10084 </footnote> Currently the packages must be separated using
10085 only spaces in the <file>.changes</file> file.</p>
10088 <sect1 id="pkg-f-Installed-Size"><heading><tt>Installed-Size</tt>
10092 This field appears in the control files of binary
10093 packages, and in the <file>Packages</file> files. It gives
10094 the total amount of disk space required to install the
10099 The disk space is represented in kilobytes as a simple
10100 decimal number.</p>
10103 <sect1 id="pkg-f-Files"><heading><tt>Files</tt>
10107 This field contains a list of files with information about
10108 each one. The exact information and syntax varies with
10109 the context. In all cases the part of the field
10110 contents on the same line as the field name is empty. The
10111 remainder of the field is one line per file, each line
10112 being indented by one space and containing a number of
10113 sub-fields separated by spaces.
10117 In the <file>.dsc</file> (Debian source control) file each
10118 line contains the MD5 checksum, size and filename of the
10119 tarfile and (if applicable) diff file which make up the
10120 remainder of the source package.
10123 That is, the parts which are not the
10126 </footnote> The exact forms of the filenames are described
10127 in <ref id="pkg-sourcearchives">.
10131 In the <file>.changes</file> file this contains one line per
10132 file being uploaded. Each line contains the MD5 checksum,
10133 size, section and priority and the filename. The section
10134 and priority are the values of the corresponding fields in
10135 the main source control file - see <ref
10136 id="pkg-f-classification">. If no section or priority is
10137 specified then <tt>-</tt> should be used, though section
10138 and priority values must be specified for new packages to
10139 be installed properly.
10143 The special value <tt>byhand</tt> for the section in a
10144 <tt>.changes</tt> file indicates that the file in question
10145 is not an ordinary package file and must by installed by
10146 hand by the distribution maintainers. If the section is
10147 <tt>byhand</tt> the priority should be <tt>-</tt>.
10151 If a new Debian revision of a package is being shipped and
10152 no new original source archive is being distributed the
10153 <tt>.dsc</tt> must still contain the <tt>Files</tt> field
10154 entry for the original source archive
10155 <file><var>package</var>-<var>upstream-version</var>.orig.tar.gz</file>,
10156 but the <file>.changes</file> file should leave it out. In
10157 this case the original source archive on the distribution
10158 site must match exactly, byte-for-byte, the original
10159 source archive which was used to generate the
10160 <file>.dsc</file> file and diff which are being uploaded.</p>
10165 id="pkg-f-Standards-Version"><heading><tt>Standards-Version</tt>
10169 The most recent version of the standards (the
10170 <prgn>dpkg</prgn> programmers' and policy manuals and
10171 associated texts) with which the package complies. This
10172 is updated manually when editing the source package to
10173 conform to newer standards; it can sometimes be used to
10174 tell when a package needs attention.
10178 Its format is the same as that of a version number except
10179 that no epoch or Debian revision is allowed - see <ref
10180 id="versions">.</p>
10184 <sect1 id="pkg-f-Distribution"><heading><tt>Distribution</tt>
10188 In a <file>.changes</file> file or parsed changelog output
10189 this contains the (space-separated) name(s) of the
10190 distribution(s) where this version of the package should
10191 be or was installed. Distribution names follow the rules
10192 for package names. (See <ref id="pkg-f-Package">).
10196 Current distribution values are:
10198 <tag><em>stable</em></tag>
10201 This is the current "released" version of Debian
10202 GNU/Linux. A new version is released approximately
10203 every 3 months after the <em>development</em> code has
10204 been <em>frozen</em> for a month of testing. Once the
10205 distribution is <em>stable</em> only major bug fixes
10206 are allowed. When changes are made to this
10207 distribution, the release number is increased
10208 (for example: 1.2r1 becomes 1.2r2 then 1.2r3, etc).
10212 <tag><em>unstable</em></tag>
10215 This distribution value refers to the
10216 <em>developmental</em> part of the Debian distribution
10217 tree. New packages, new upstream versions of packages
10218 and bug fixes go into the <em>unstable</em> directory
10219 tree. Download from this distribution at your own
10223 <tag><em>contrib</em></tag>
10226 The packages with this distribution value do not meet
10227 the criteria for inclusion in the main Debian
10228 distribution as defined by the Policy Manual, but meet
10229 the criteria for the <em>contrib</em>
10230 Distribution. There is currently no distinction
10231 between stable and unstable packages in the
10232 <em>contrib</em> or <em>non-free</em>
10233 distributions. Use your best judgement in downloading
10234 from this Distribution.</p>
10237 <tag><em>non-free</em></tag>
10240 Like the packages in the <em>contrib</em> seciton,
10241 the packages in <em>non-free</em> do not meet the
10242 criteria for inclusion in the main Debian distribution
10243 as defined by the Policy Manual. Again, use your best
10244 judgement in downloading from this Distribution.</p>
10246 <tag><em>experimental</em></tag>
10249 The packages with this distribution value are deemed
10250 by their maintainers to be high risk. Oftentimes they
10251 represent early beta or developmental packages from
10252 various sources that the maintainers want people to
10253 try, but are not ready to be a part of the other parts
10254 of the Debian distribution tree. Download at your own
10258 <tag><em>frozen</em></tag>
10261 From time to time, (currently, every 3 months) the
10262 <em>unstable</em> distribution enters a state of
10263 "code-freeze" in anticipation of release as a
10264 <em>stable</em> version. During this period of testing
10265 (usually 4 weeks) only fixes for existing or
10266 newly-discovered bugs will be allowed.
10269 </taglist> You should list <em>all</em> distributions that
10270 the package should be installed into. Except in unusual
10271 circumstances, installations to <em>stable</em> should also
10272 go into <em>frozen</em> (if it exists) and
10273 <em>unstable</em>. Likewise, installations into
10274 <em>frozen</em> should also go into <em>unstable</em>.</p>
10277 <sect1 id="pkg-f-Urgency"><heading><tt>Urgency</tt>
10281 This is a description of how important it is to upgrade to
10282 this version from previous ones. It consists of a single
10283 keyword usually taking one of the values <tt>LOW</tt>,
10284 <tt>MEDIUM</tt> or <tt>HIGH</tt>) followed by an optional
10285 commentary (separated by a space) which is usually in
10286 parentheses. For example:
10288 Urgency: LOW (HIGH for diversions users)
10293 This field appears in the <file>.changes</file> file and in
10294 parsed changelogs; its value appears as the value of the
10295 <tt>urgency</tt> attribute in a <prgn>dpkg</prgn>-style
10296 changelog (see <ref id="pkg-dpkgchangelog">).
10300 Urgency keywords are not case-sensitive.</p>
10303 <sect1 id="pkg-f-Date"><heading><tt>Date</tt>
10307 In <tt>.changes</tt> files and parsed changelogs, this
10308 gives the date the package was built or last edited.</p>
10311 <sect1 id="pkg-f-Format"><heading><tt>Format</tt>
10315 This field occurs in <file>.changes</file> files, and
10316 specifies a format revision for the file. The format
10317 described here is version <tt>1.5</tt>. The syntax of the
10318 format value is the same as that of a package version
10319 number except that no epoch or Debian revision is allowed
10320 - see <ref id="versions">.</p>
10323 <sect1 id="pkg-f-Changes"><heading><tt>Changes</tt>
10327 In a <file>.changes</file> file or parsed changelog this field
10328 contains the human-readable changes data, describing the
10329 differences between the last version and the current one.
10333 There should be nothing in this field before the first
10334 newline; all the subsequent lines must be indented by at
10335 least one space; blank lines must be represented by a line
10336 consiting only of a space and a full stop.
10340 Each version's change information should be preceded by a
10341 "title" line giving at least the version, distribution(s)
10342 and urgency, in a human-readable way.
10346 If data from several versions is being returned the entry
10347 for the most recent version should be returned first, and
10348 entries should be separated by the representation of a
10349 blank line (the "title" line may also be followed by the
10350 representation of blank line).</p>
10353 <sect1 id="pkg-f-Filename"><heading><tt>Filename</tt> and
10354 <tt>MSDOS-Filename</tt>
10358 These fields in <tt>Packages</tt> files give the
10359 filename(s) of (the parts of) a package in the
10360 distribution directories, relative to the root of the
10361 Debian hierarchy. If the package has been split into
10362 several parts the parts are all listed in order, separated
10366 <sect1 id="pkg-f-Size"><heading><tt>Size</tt> and <tt>MD5sum</tt>
10370 These fields in <file>Packages</file> files give the size (in
10371 bytes, expressed in decimal) and MD5 checksum of the
10372 file(s) which make(s) up a binary package in the
10373 distribution. If the package is split into several parts
10374 the values for the parts are listed in order, separated by
10378 <sect1 id="pkg-f-Status"><heading><tt>Status</tt>
10382 This field in <prgn>dpkg</prgn>'s status file records
10383 whether the user wants a package installed, removed or
10384 left alone, whether it is broken (requiring
10385 reinstallation) or not and what its current state on the
10386 system is. Each of these pieces of information is a
10390 <sect1 id="pkg-f-Config-Version"><heading><tt>Config-Version</tt>
10394 If a package is not installed or not configured, this
10395 field in <prgn>dpkg</prgn>'s status file records the last
10396 version of the package which was successfully
10400 <sect1 id="pkg-f-Conffiles"><heading><tt>Conffiles</tt>
10404 This field in <prgn>dpkg</prgn>'s status file contains
10405 information about the automatically-managed configuration
10406 files held by a package. This field should <em>not</em>
10407 appear anywhere in a package!</p>
10410 <sect1><heading>Obsolete fields
10414 These are still recognised by <prgn>dpkg</prgn> but should
10415 not appear anywhere any more.
10416 <taglist compact="compact">
10418 <tag><tt>Revision</tt></tag>
10419 <tag><tt>Package-Revision</tt></tag>
10420 <tag><tt>Package_Revision</tt></tag>
10423 The Debian revision part of the package version was
10424 at one point in a separate control file field. This
10425 field went through several names.</p>
10428 <tag><tt>Recommended</tt></tag>
10429 <item><p>Old name for <tt>Recommends</tt></p>
10432 <tag><tt>Optional</tt></tag>
10433 <item><p>Old name for <tt>Suggests</tt>.</p>
10435 <tag><tt>Class</tt></tag>
10436 <item><p>Old name for <tt>Priority</tt>.</p>
10444 <appendix id="pkg-conffiles"><heading>Configuration file handling
10445 (from old Packaging Manual)
10449 <prgn>dpkg</prgn> can do a certain amount of automatic
10450 handling of package configuration files.
10454 Whether this mechanism is appropriate depends on a number of
10455 factors, but basically there are two approaches to any
10456 particular configuration file.
10460 The easy method is to ship a best-effort configuration in the
10461 package, and use <prgn>dpkg</prgn>'s conffile mechanism to
10462 handle updates. If the user is unlikely to want to edit the
10463 file, but you need them to be able to without losing their
10464 changes, and a new package with a changed version of the file
10465 is only released infrequently, this is a good approach.
10469 The hard method is to build the configuration file from
10470 scratch in the <prgn>postinst</prgn> script, and to take the
10471 responsibility for fixing any mistakes made in earlier
10472 versions of the package automatically. This will be
10473 appropriate if the file is likely to need to be different on
10477 <sect><heading>Automatic handling of configuration files by
10482 A package may contain a control area file called
10483 <tt>conffiles</tt>. This file should be a list of filenames
10484 of configuration files needing automatic handling, separated
10485 by newlines. The filenames should be absolute pathnames,
10486 and the files referred to should actually exist in the
10491 When a package is upgraded <prgn>dpkg</prgn> will process
10492 the configuration files during the configuration stage,
10493 shortly before it runs the package's <prgn>postinst</prgn>
10498 For each file it checks to see whether the version of the
10499 file included in the package is the same as the one that was
10500 included in the last version of the package (the one that is
10501 being upgraded from); it also compares the version currently
10502 installed on the system with the one shipped with the last
10507 If neither the user nor the package maintainer has changed
10508 the file, it is left alone. If one or the other has changed
10509 their version, then the changed version is preferred - i.e.,
10510 if the user edits their file, but the package maintainer
10511 doesn't ship a different version, the user's changes will
10512 stay, silently, but if the maintainer ships a new version
10513 and the user hasn't edited it the new version will be
10514 installed (with an informative message). If both have
10515 changed their version the user is prompted about the problem
10516 and must resolve the differences themselves.
10520 The comparisons are done by calculating the MD5 message
10521 digests of the files, and storing the MD5 of the file as it
10522 was included in the most recent version of the package.
10526 When a package is installed for the first time
10527 <prgn>dpkg</prgn> will install the file that comes with it,
10528 unless that would mean overwriting a file already on the
10533 However, note that <prgn>dpkg</prgn> will <em>not</em>
10534 replace a conffile that was removed by the user (or by a
10535 script). This is necessary because with some programs a
10536 missing file produces an effect hard or impossible to
10537 achieve in another way, so that a missing file needs to be
10538 kept that way if the user did it.
10542 Note that a package should <em>not</em> modify a
10543 <prgn>dpkg</prgn>-handled conffile in its maintainer
10544 scripts. Doing this will lead to <prgn>dpkg</prgn> giving
10545 the user confusing and possibly dangerous options for
10546 conffile update when the package is upgraded.</p>
10549 <sect><heading>Fully-featured maintainer script configuration
10554 For files which contain site-specific information such as
10555 the hostname and networking details and so forth, it is
10556 better to create the file in the package's
10557 <prgn>postinst</prgn> script.
10561 This will typically involve examining the state of the rest
10562 of the system to determine values and other information, and
10563 may involve prompting the user for some information which
10564 can't be obtained some other way.
10568 When using this method there are a couple of important
10569 issues which should be considered:
10573 If you discover a bug in the program which generates the
10574 configuration file, or if the format of the file changes
10575 from one version to the next, you will have to arrange for
10576 the postinst script to do something sensible - usually this
10577 will mean editing the installed configuration file to remove
10578 the problem or change the syntax. You will have to do this
10579 very carefully, since the user may have changed the file,
10580 perhaps to fix the very problem that your script is trying
10581 to deal with - you will have to detect these situations and
10582 deal with them correctly.
10586 If you do go down this route it's probably a good idea to
10587 make the program that generates the configuration file(s) a
10588 separate program in <file>/usr/sbin</file>, by convention called
10589 <file><var>package</var>config</file> and then run that if
10590 appropriate from the post-installation script. The
10591 <tt><var>package</var>config</tt> program should not
10592 unquestioningly overwrite an existing configuration - if its
10593 mode of operation is geared towards setting up a package for
10594 the first time (rather than any arbitrary reconfiguration
10595 later) you should have it check whether the configuration
10596 already exists, and require a <tt>--force</tt> flag to
10597 overwrite it.</p></sect>
10600 <appendix id="pkg-alternatives"><heading>Alternative versions of
10601 an interface - <prgn>update-alternatives</prgn> (from old
10606 When several packages all provide different versions of the
10607 same program or file it is useful to have the system select a
10608 default, but to allow the system administrator to change it
10609 and have their decisions respected.
10613 For example, there are several versions of the <prgn>vi</prgn>
10614 editor, and there is no reason to prevent all of them from
10615 being installed at once, each under their own name
10616 (<prgn>nvi</prgn>, <prgn>vim</prgn> or whatever).
10617 Nevertheless it is desirable to have the name <tt>vi</tt>
10618 refer to something, at least by default.
10622 If all the packages involved cooperate, this can be done with
10623 <prgn>update-alternatives</prgn>.
10627 Each package provides its own version under its own name, and
10628 calls <prgn>update-alternatives</prgn> in its postinst to
10629 register its version (and again in its prerm to deregister
10634 See the manpage <manref name="update-alternatives"
10635 section="8"> for details.
10639 If <prgn>update-alternatives</prgn> does not seem appropriate
10640 you may wish to consider using diversions instead.</p>
10643 <appendix id="pkg-diversions"><heading>Diversions - overriding a
10644 package's version of a file (from old Packaging Manual)
10648 It is possible to have <prgn>dpkg</prgn> not overwrite a file
10649 when it reinstalls the package it belongs to, and to have it
10650 put the file from the package somewhere else instead.
10654 This can be used locally to override a package's version of a
10655 file, or by one package to override another's version (or
10656 provide a wrapper for it).
10660 Before deciding to use a diversion, read <ref
10661 id="pkg-alternatives"> to see if you really want a diversion
10662 rather than several alternative versions of a program.
10666 There is a diversion list, which is read by <prgn>dpkg</prgn>,
10667 and updated by a special program <prgn>dpkg-divert</prgn>.
10668 Please see <manref name="dpkg-divert" section="8"> for full
10669 details of its operation.
10673 When a package wishes to divert a file from another, it should
10674 call <prgn>dpkg-divert</prgn> in its preinst to add the
10675 diversion and rename the existing file. For example,
10676 supposing that a <prgn>smailwrapper</prgn> package wishes to
10677 install a wrapper around <file>/usr/sbin/smail</file>:
10679 if [ install = "$1" ]; then
10680 dpkg-divert --package smailwrapper --add --rename \
10681 --divert /usr/sbin/smail.real /usr/sbin/smail
10683 </example> Testing <tt>$1</tt> is necessary so that the script
10684 doesn't try to add the diversion again when
10685 <prgn>smailwrapper</prgn> is upgraded. The <tt>--package
10686 smailwrapper</tt> ensures that <prgn>smailwrapper</prgn>'s
10687 copy of <file>/usr/sbin/smail</file> can bypass the diversion and
10688 get installed as the true version.
10692 The postrm has to do the reverse:
10694 if [ remove = "$1" ]; then
10695 dpkg-divert --package smailwrapper --remove --rename \
10696 --divert /usr/sbin/smail.real /usr/sbin/smail
10702 Do not attempt to divert a file which is vitally important for
10703 the system's operation - when using <prgn>dpkg-divert</prgn>
10704 there is a time, after it has been diverted but before
10705 <prgn>dpkg</prgn> has installed the new version, when the file
10706 does not exist.</p>
10711 <!-- vim:set ai et sts=2 sw=2 tw=76: -->