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10 <title>Debian Policy Manual</title>
11 <author><ref id="authors"></author>
12 <version>version &version;, &date;</version>
15 This manual describes the policy requirements for the Debian
16 GNU/Linux distribution. This includes the structure and
17 contents of the Debian archive and several design issues of
18 the operating system, as well as technical requirements that
19 each package must satisfy to be included in the distribution.
24 Copyright © 1996,1997,1998 Ian Jackson
25 and Christian Schwarz.
28 This manual is free software; you may redistribute it and/or
29 modify it under the terms of the GNU General Public License
30 as published by the Free Software Foundation; either version
31 2, or (at your option) any later version.
35 This is distributed in the hope that it will be useful, but
36 <em>without any warranty</em>; without even the implied
37 warranty of merchantability or fitness for a particular
38 purpose. See the GNU General Public License for more
43 A copy of the GNU General Public License is available as
44 <file>/usr/share/common-licenses/GPL</file> in the Debian GNU/Linux
45 distribution or on the World Wide Web at
46 <url id="http://www.gnu.org/copyleft/gpl.html"
47 name="the GNU General Public Licence">. You can also
48 obtain it by writing to the Free Software Foundation, Inc.,
49 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA.
57 <heading>About this manual</heading>
59 <heading>Scope</heading>
61 This manual describes the policy requirements for the Debian
62 GNU/Linux distribution. This includes the structure and
63 contents of the Debian archive and several design issues of the
64 operating system, as well as technical requirements that
65 each package must satisfy to be included in the
71 This manual also describes Debian policy as it relates to
72 creating Debian packages. It is not a tutorial on how to build
73 packages, nor is it exhaustive where it comes to describing
74 the behavior of the packaging system. Instead, this manual
75 attempts to define the interface to the package management
76 system that the developers have to be conversant with.<footnote>
78 Informally, the criteria used for inclusion is that the
79 material meet one of the following requirements:
80 <taglist compact="compact">
81 <tag>Standard interfaces</tag>
84 The material presented represents an interface to
85 the packaging system that is mandated for use, and
86 is used by, a significant number of packages, and
87 therefore should not be changed without peer
88 review. Package maintainers can then rely on this
89 interfaces not changing, and the package
90 management software authors need to ensure
91 compatibility with these interface
92 definitions. (Control file and changelog file
93 formats are examples.)
96 <tag>Chosen Convention</tag>
99 If there are a number of technically viable choices
100 that can be made, but one needs to select one of
101 these options for inter-operability. The version
102 number format is one example.
106 Please note that these are not mutually exclusive;
107 selected conventions often become parts of standard
114 The footnotes present in this manual are
115 merely informative, and are not part of Debian policy itself.
119 In this manual, the words <em>must</em>, <em>should</em> and
120 <em>may</em>, and the adjectives <em>required</em>,
121 <em>recommended</em> and <em>optional</em>, are used to
122 distinguish the significance of the various guidelines in
123 this policy document. Packages that do not conform to the
124 guidelines denoted by <em>must</em> (or <em>required</em>)
125 will generally not be considered acceptable for the Debian
126 distribution. Non-conformance with guidelines denoted by
127 <em>should</em> (or <em>recommended</em>) will generally be
128 considered a bug, but will not necessarily render a package
129 unsuitable for distribution. Guidelines denoted by
130 <em>may</em> (or <em>optional</em>) are truly optional and
131 adherence is left to the maintainer's discretion.
134 These classifications are roughly equivalent to the bug
135 severities <em>serious</em> (for <em>must</em> or
136 <em>required</em> directive violations), <em>minor</em>,
137 <em>normal</em> or <em>important</em>
138 (for <em>should</em> or <em>recommended</em> directive
139 violations) and <em>wishlist</em> (for <em>optional</em>
141 <p>Compare RFC 2119. Note, however, that these words are
142 used in a different way in this document.</p>
146 Much of the information presented in this manual will be
147 useful even when building a package which is to be
148 distributed in some other way or is intended for local use
154 <heading>New versions of this document</heading>
156 The current version of this document is always accessible
157 from the Debian FTP server <ftpsite>ftp.debian.org</ftpsite>
159 <ftppath>/debian/doc/package-developer/policy.txt.gz</ftppath>
160 (also available from the same directory are several other
161 formats: <file>policy.html.tar.gz</file>, <file>policy.pdf.gz</file>
162 and <file>policy.ps.gz</file>) or from the <url
163 id="http://www.debian.org/doc/debian-policy/" name="Debian
164 Policy Manual"> webpage.</p>
167 In addition, this manual is distributed via the Debian package
168 <file>debian-policy</file>.
172 The <tt>debian-policy</tt> package also includes the file
173 <file>upgrading-checklist.txt</file> which indicates policy
174 changes between versions of this document.
179 <heading>Authors and Maintainers</heading>
182 Originally called "Debian GNU/Linux Policy Manual", this
183 manual was initially written in 1996 by Ian Jackson.
184 It was revised on November 27th, 1996 by David A. Morris.
185 Christian Schwarz added new sections on March 15th, 1997,
186 and reworked/restructured it in April-July 1997.
187 Christoph Lameter contributed the "Web Standard".
188 Julian Gilbey largely restructured it in 2001.
192 Since September 1998, the responsibility for the contents of
193 this document lies on the debian-policy mailing list. Proposals
194 are discussed there and inserted into policy after a certain
195 consensus is established.
196 <!-- insert shameless policy-process plug here eventually -->
197 The actual editing is done by a group of maintainers that have
198 no editorial powers. These are the current maintainers:
201 <item>Julian Gilbey</item>
202 <item>Branden Robinson</item>
203 <item>Josip Rodin</item>
204 <item>Manoj Srivastava</item>
209 While the authors of this document have tried hard to avoid
210 typos and other errors, these do still occur. If you discover
211 an error in this manual or if you want to give any
212 comments, suggestions, or criticisms please send an email to
213 the Debian Policy List,
214 <email>debian-policy@lists.debian.org</email>, or submit a
215 bug report against the <tt>debian-policy</tt> package.
219 Please do not try to reach the individual authors or maintainers
220 of the Policy Manual regarding changes to the Policy.
226 <heading>The Debian Archive</heading>
228 The Debian GNU/Linux system is maintained and distributed as a
229 collection of <em>packages</em>. Since there are so many of
230 them (currently well over 6000), they are split into
231 <em>sections</em> and given <em>priorities</em> to simplify
232 the handling of them.
235 The effort of the Debian project is to build a free operating
236 system, but not every package we want to make accessible is
237 <em>free</em> in our sense (see the Debian Free Software
238 Guidelines, below), or may be imported/exported without
239 restrictions. Thus, the archive is split into the sections
240 <em>main</em>, <em>non-free</em>, <em>contrib</em>,
241 <em>non-US/main</em>, <em>non-US/non-free</em>, and
242 <em>non-US/contrib</em>. The sections are explained in detail
247 The <em>main</em> and the <em>non-US/main</em> sections
248 together form the <em>Debian GNU/Linux distribution</em>.
252 Packages in the other sections are not considered to be part
253 of the Debian distribution, although we support their use and
254 provide infrastructure for them (such as our bug-tracking
255 system and mailing lists). This Debian Policy Manual applies
256 to these packages as well.</p>
258 <sect id="pkgcopyright">
259 <heading>Package copyright and sections</heading>
261 The aims of this section are:
263 <list compact="compact">
265 <p>to allow us to make as much software available as we
269 <p>to allow us to encourage everyone to write free
273 <p>to allow us to make it easy for people to produce
274 CD-ROMs of our system without violating any licenses,
275 import/export restrictions, or any other laws.</p>
280 <heading>The Debian Free Software Guidelines</heading>
282 The Debian Free Software Guidelines (DFSG) form our
283 definition of "free software". These are:
285 <tag>Free Redistribution
289 The license of a Debian component may not restrict any
290 party from selling or giving away the software as a
291 component of an aggregate software distribution
292 containing programs from several different
293 sources. The license may not require a royalty or
294 other fee for such sale.
301 The program must include source code, and must allow
302 distribution in source code as well as compiled form.
309 The license must allow modifications and derived
310 works, and must allow them to be distributed under the
311 same terms as the license of the original software.
314 <tag>Integrity of The Author's Source Code
318 The license may restrict source-code from being
319 distributed in modified form <em>only</em> if the
320 license allows the distribution of "patch files"
321 with the source code for the purpose of modifying the
322 program at build time. The license must explicitly
323 permit distribution of software built from modified
324 source code. The license may require derived works to
325 carry a different name or version number from the
326 original software. (This is a compromise. The Debian
327 Project encourages all authors to not restrict any
328 files, source or binary, from being modified.)
331 <tag>No Discrimination Against Persons or Groups
335 The license must not discriminate against any person
339 <tag>No Discrimination Against Fields of Endeavor
343 The license must not restrict anyone from making use
344 of the program in a specific field of endeavor. For
345 example, it may not restrict the program from being
346 used in a business, or from being used for genetic
350 <tag>Distribution of License
354 The rights attached to the program must apply to all
355 to whom the program is redistributed without the need
356 for execution of an additional license by those
360 <tag>License Must Not Be Specific to Debian
364 The rights attached to the program must not depend on
365 the program's being part of a Debian system. If the
366 program is extracted from Debian and used or
367 distributed without Debian but otherwise within the
368 terms of the program's license, all parties to whom
369 the program is redistributed must have the same
370 rights as those that are granted in conjunction with
374 <tag>License Must Not Contaminate Other Software
378 The license must not place restrictions on other
379 software that is distributed along with the licensed
380 software. For example, the license must not insist
381 that all other programs distributed on the same medium
382 must be free software.
385 <tag>Example Licenses
389 The "GPL," "BSD," and "Artistic" licenses are examples of
390 licenses that we consider <em>free</em>.
397 <heading>The main section</heading>
399 Every package in <em>main</em> and <em>non-US/main</em>
400 must comply with the DFSG (Debian Free Software
404 In addition, the packages in <em>main</em>
405 <list compact="compact">
408 must not require a package outside of <em>main</em>
409 for compilation or execution (thus, the package must
410 not declare a "Depends", "Recommends", or
411 "Build-Depends" relationship on a non-<em>main</em>
417 must not be so buggy that we refuse to support them,
423 must meet all policy requirements presented in this
430 Similarly, the packages in <em>non-US/main</em>
431 <list compact="compact">
434 must not require a package outside of <em>main</em>
435 or <em>non-US/main</em> for compilation or
441 must not be so buggy that we refuse to support them,
446 must meet all policy requirements presented in this
454 <heading>The contrib section</heading>
456 Every package in <em>contrib</em> and
457 <em>non-US/contrib</em> must comply with the DFSG.
461 In addition, the packages in <em>contrib</em> and
462 <em>non-US/contrib</em>
463 <list compact="compact">
466 must not be so buggy that we refuse to support them,
472 must meet all policy requirements presented in this
480 Furthermore, packages in <em>contrib</em> must not require
481 a package in a <em>non-US</em> section for compilation or
486 Examples of packages which would be included in
487 <em>contrib</em> or <em>non-US/contrib</em> are:
488 <list compact="compact">
491 free packages which require <em>contrib</em>,
492 <em>non-free</em> packages or packages which are not
493 in our archive at all for compilation or execution,
499 wrapper packages or other sorts of free accessories for
507 <heading>The non-free section</heading>
509 Packages must be placed in <em>non-free</em> or
510 <em>non-US/non-free</em> if they are not compliant with
511 the DFSG or are encumbered by patents or other legal
512 issues that make their distribution problematic.
515 In addition, the packages in <em>non-free</em> and
516 <em>non-US/non-free</em>
517 <list compact="compact">
520 must not be so buggy that we refuse to support them,
526 must meet all policy requirements presented in this
527 manual that it is possible for them to meet.<footnote>
529 It is possible that there are policy
530 requirements which the package is unable to
531 meet, for example, if the source is
532 unavailable. These situations will need to be
533 handled on a case-by-case basis.
543 <heading>The non-US sections</heading>
545 Non-free programs with cryptographic program code need to
546 be stored on the <em>non-us</em> server because of export
547 restrictions of the U.S.
550 Programs which use patented algorithms that have a
551 restrictied license also need to be stored on "non-us",
552 since that is located in a country where it is not allowed
553 to patent algorithms.
556 A package depends on another package which is distributed
557 via the non-us server has to be stored on the non-us
562 <heading>Further copyright considerations</heading>
564 Every package must be accompanied by a verbatim copy of
565 its copyright and distribution license in the file
566 <file>/usr/share/doc/<var>package</var>/copyright</file>
567 (see <ref id="copyrightfile"> for further details).
570 We reserve the right to restrict files from being included
571 anywhere in our archives if
572 <list compact="compact">
575 their use or distribution would break a law,
580 there is an ethical conflict in their distribution or
586 we would have to sign a license for them, or
591 their distribution would conflict with other project
599 Programs whose authors encourage the user to make
600 donations are fine for the main distribution, provided
601 that the authors do not claim that not donating is
602 immoral, unethical, illegal or something similar; in such
603 a case they must go in <em>non-free</em>.</p>
606 Packages whose copyright permission notices (or patent
607 problems) do not even allow redistribution of binaries
608 only, and where no special permission has been obtained,
609 must not be placed on the Debian FTP site and its mirrors
613 Note that under international copyright law (this applies
614 in the United States, too), <em>no</em> distribution or
615 modification of a work is allowed without an explicit
616 notice saying so. Therefore a program without a copyright
617 notice <em>is</em> copyrighted and you may not do anything
618 to it without risking being sued! Likewise if a program
619 has a copyright notice but no statement saying what is
620 permitted then nothing is permitted.</p>
623 Many authors are unaware of the problems that restrictive
624 copyrights (or lack of copyright notices) can cause for
625 the users of their supposedly-free software. It is often
626 worthwhile contacting such authors diplomatically to ask
627 them to modify their license terms. However, this can be a
628 politically difficult thing to do and you should ask for
629 advice on the <tt>debian-legal</tt> mailing list first, as
634 When in doubt about a copyright, send mail to
635 <email>debian-legal@lists.debian.org</email>. Be prepared
636 to provide us with the copyright statement. Software
637 covered by the GPL, public domain software and BSD-like
638 copyrights are safe; be wary of the phrases "commercial
639 use prohibited" and "distribution restricted".
643 <heading>Subsections</heading>
646 The packages in the sections <em>main</em>,
647 <em>contrib</em> and <em>non-free</em> are grouped further
648 into <em>subsections</em> to simplify handling.
652 The section and subsection for each package should be
653 specified in the package's <tt>Section</tt> control
654 record. However, the maintainer of the Debian archive
655 may override this selection to ensure the consistency of
656 the Debian distribution. The <tt>Section</tt> field
657 should be of the form:
658 <list compact="compact">
661 <em>subsection</em> if the package is in the
662 <em>main</em> section,
667 <em>section/subsection</em> if the package is in
668 the <em>contrib</em> or <em>non-free</em> section,
674 <tt>non-US</tt>, <tt>non-US/contrib</tt> or
675 <tt>non-US/non-free</tt> if the package is in
676 <em>non-US/main</em>, <em>non-US/contrib</em> or
677 <em>non-US/non-free</em> respectively.
684 The Debian archive maintainers provide the authoritative
685 list of subsections. At present, they are:
686 <em>admin</em>, <em>base</em>, <em>comm</em>,
687 <em>contrib</em>, <em>devel</em>, <em>doc</em>,
688 <em>editors</em>, <em>electronics</em>, <em>games</em>,
689 <em>graphics</em>, <em>hamradio</em>,
690 <em>interpreters</em>, <em>libs</em>, <em>mail</em>,
691 <em>math</em>, <em>misc</em>, <em>net</em>, <em>news</em>,
692 <em>non-US</em>, <em>non-free</em>, <em>oldlibs</em>,
693 <em>otherosfs</em>, <em>science</em>, <em>shells</em>,
694 <em>sound</em>, <em>tex</em>, <em>text</em>,
695 <em>utils</em>, <em>web</em>, <em>x11</em>.
699 <heading>Priorities</heading>
702 Each package should have a <em>priority</em> value, which is
703 included in the package's <em>control record</em>. This
704 information is used by the Debian package management tools
705 to separate high-priority packages from less-important
709 The following <em>priority levels</em> are recognised by the
710 Debian package management tools.
712 <tag><tt>required</tt></tag>
715 Packages which are necessary for the proper
716 functioning of the system. You must not remove these
717 packages or your system may become totally broken and
718 you may not even be able to use <prgn>dpkg</prgn> to
719 put things back. Systems with only the
720 <tt>required</tt> packages are probably unusable, but
721 they do have enough functionality to allow the
722 sysadmin to boot and install more software.</p>
724 <tag><tt>important</tt></tag>
727 Important programs, including those which one would
728 expect to find on any Unix-like system. If the
729 expectation is that an experienced Unix person who
730 found it missing would say "What on earth is going on,
731 where is <prgn>foo</prgn>?", it must be an
732 <tt>important</tt> package.<footnote>
734 This is an important criterion because we are
735 trying to produce, amongst other things, a free
739 Other packages without which the system will not run
740 well or be usable must also have priority
741 <tt>important</tt>. This does
742 <em>not</em> include Emacs, the X Window System, TeX
743 or any other large applications. The
744 <tt>important</tt> packages are just a bare minimum of
745 commonly-expected and necessary tools.</p>
747 <tag><tt>standard</tt></tag>
750 These packages provide a reasonably small but not too
751 limited character-mode system. This is what will be
752 installed by default if the user doesn't select anything
753 else. It doesn't include many large applications.</p>
755 <tag><tt>optional</tt></tag>
758 (In a sense everything that isn't required is
759 optional, but that's not what is meant here.) This is
760 all the software that you might reasonably want to
761 install if you didn't know what it was and don't have
762 specialized requirements. This is a much larger system
763 and includes the X Window System, a full TeX
764 distribution, and many applications. Note that
765 optional packages should not conflict with each other.
768 <tag><tt>extra</tt></tag>
771 This contains all packages that conflict with others
772 with required, important, standard or optional
773 priorities, or are only likely to be useful if you
774 already know what they are or have specialised
781 Packages must not depend on packages with lower priority
782 values (excluding build-time dependencies). In order to
783 ensure this, the priorities of one or more packages may need
789 <heading>Binary packages</heading>
792 The Debian GNU/Linux distribution is based on the Debian
793 package management system, called <prgn>dpkg</prgn>. Thus,
794 all packages in the Debian distribution must be provided
795 in the <tt>.deb</tt> file format.</p>
799 <heading>The package name</heading>
802 Every package must have a name that's unique within the Debian
806 Package names must consist of lower case letters
807 (<tt>a-z</tt>), digits (<tt>0-9</tt>), plus (<tt>+</tt>)
808 and minus (<tt>-</tt>) signs, and periods (<tt>.</tt>).
809 They must be at least two characters long and must start
810 with an alphanumeric character.
814 The package name is part of the file name of the
815 <tt>.deb</tt> file and is included in the control field
821 <heading>The maintainer of a package</heading>
823 Every package must have a Debian maintainer (the
824 maintainer may be one person or a group of people
825 reachable from a common email address, such as a mailing
826 list). The maintainer is responsible for ensuring that
827 the package is placed in the appropriate distributions.
831 The maintainer must be specified in the
832 <tt>Maintainer</tt> control field with their correct name
833 and a working email address. If one person maintains
834 several packages, he/she should try to avoid having
835 different forms of their name and email address in
836 the <tt>Maintainer</tt> fields of those packages.
840 If the maintainer of a package quits from the Debian
841 project, "Debian QA Group"
842 <email>packages@qa.debian.org</email> takes over the
843 maintainership of the package until someone else
844 volunteers for that task. These packages are called
845 <em>orphaned packages</em>.<footnote>
847 The detailed procedure for doing this gracefully can
848 be found in the Debian Developer's Reference, either
849 in the <tt>developers-reference</tt> package, or on
850 the Debian FTP server
851 <ftpsite>ftp.debian.org</ftpsite> as
852 <ftppath>/debian/doc/package-developer/developers-reference.txt.gz</ftppath>
854 id="http://www.debian.org/doc/packaging-manuals/developers-reference/"
855 name="Debian Developer's Reference"> webpage.
863 <heading>The description of a package</heading>
866 Every Debian package must have an extended description
867 stored in the appropriate field of the control record.</p>
870 The description should be written so that it gives the
871 system administrator enough information to decide whether
872 to install the package. This description should not just
873 be copied verbatim from the program's documentation.
874 Instructions for configuring or using the package should
875 not be included (that is what installation scripts,
876 manual pages, info files, etc., are for). Copyright
877 statements and other administrivia should not be included
878 either (that is what the copyright file is for).
882 Please refer to <ref id="descriptions"> for more information.
889 <heading>Dependencies</heading>
892 Every package must specify the dependency information
893 about other packages that are required for the first to
897 For example, a dependency entry must be provided for any
898 shared libraries required by a dynamically-linked executable
899 binary in a package.</p>
902 Packages are not required to declare any dependencies they
903 have on other packages which are marked <tt>Essential</tt>
904 (see below), and should not do so unless they depend on a
905 particular version of that package.</p>
908 Sometimes, a package requires another package to be installed
909 <em>and</em> configured before it can be installed. In this
910 case, you must specify a <tt>Pre-Depends</tt> entry for
914 You should not specify a <tt>Pre-Depends</tt> entry for a
915 package before this has been discussed on the
916 <tt>debian-devel</tt> mailing list and a consensus about
917 doing that has been reached.</p></sect1>
920 <sect1 id="virtual_pkg_sect">
921 <heading>Virtual packages</heading>
924 Sometimes, there are several packages which offer
925 more-or-less the same functionality. In this case, it's
926 useful to define a <em>virtual package</em> whose name
927 describes that common functionality. (The virtual
928 packages only exist logically, not physically; that's why
929 they are called <em>virtual</em>.) The packages with this
930 particular function will then <em>provide</em> the virtual
931 package. Thus, any other package requiring that function
932 can simply depend on the virtual package without having to
933 specify all possible packages individually.</p>
936 All packages should use virtual package names where
937 appropriate, and arrange to create new ones if necessary.
938 They should not use virtual package names (except privately,
939 amongst a cooperating group of packages) unless they have
940 been agreed upon and appear in the list of virtual package
941 names. (See also <ref id="virtual">)</p>
944 The latest version of the authoritative list of virtual
945 package names can be found on
946 <ftpsite>ftp.debian.org</ftpsite> in
947 <ftppath>/debian/doc/package-developer/virtual-package-names-list.txt</ftppath>
948 or your local mirror. In addition, it is included in the
949 <tt>debian-policy</tt> package. The procedure for updating
950 the list is described at the top of the file.</p></sect1>
954 <heading>Base system</heading>
957 The <tt>base system</tt> is a minimum subset of the Debian
958 GNU/Linux system that is installed before everything else
959 on a new system. Thus, only very few packages are allowed
960 to go into the <tt>base</tt> section to keep the required
961 disk usage very small.</p>
964 Most of these packages will have the priority value
965 <tt>required</tt> or at least <tt>important</tt>, and many
966 of them will be tagged <tt>essential</tt> (see below).</p>
973 <heading>Essential packages</heading>
976 Some packages are tagged <tt>essential</tt>. (They have
977 <tt>Essential: yes</tt> in their package control record.)
978 This flag is used for packages that are <em>essential</em>
982 Since these packages cannot be easily removed (one has to
983 specify an extra <em>force option</em> to
984 <prgn>dpkg</prgn> to do so), this flag must not be used
985 unless absolutely necessary. A shared library package
986 must not be tagged <tt>essential</tt>; dependencies will
987 prevent its premature removal, and we need to be able to
988 remove it when it has been superseded.
992 Since dpkg will not prevent upgrading of other packages
993 while an <tt>essential</tt> package is in an unconfigured
994 state, all <tt>essential</tt> packages must supply all of
995 their core functionality even when unconfigured. If the
996 package cannot satisfy this requirement it must not be
997 tagged as essential, and any packages depending on this
998 package must instead have explicit dependency fields as
1003 You must not tag any packages <tt>essential</tt> before
1004 this has been discussed on the <tt>debian-devel</tt>
1005 mailing list and a consensus about doing that has been
1010 <heading>Tasks</heading>
1013 The Debian install process allows the user to choose from
1014 a number of common tasks which a Debian system can be used to
1015 perform. Selecting a task with <prgn>tasksel</prgn> causes
1016 a set of packages that are useful in performing that task to be
1021 This set of packages is all available packages which have the
1022 name of the selected task in the <tt>Task</tt> field of their
1023 control file. The format of this field is a list of tasks,
1024 separated by commas.
1028 You should not tag any packages as belonging to a task
1029 before this has been discussed on the
1030 <em>debian-devel</em> mailing list and a consensus about
1031 doing that has been reached.
1035 For third parties (and historical reasons), tasksel also
1036 supports constructing tasks based on <em>task
1037 packages</em>. These are packages whose names begin with
1038 <em>task-</em>. Task packages should not be included in the
1043 <sect1 id="maintscripts">
1044 <heading>Maintainer Scripts</heading>
1047 The package installation scripts should avoid producing
1048 output which it is unnecessary for the user to see and
1049 should rely on <prgn>dpkg</prgn> to stave off boredom on
1050 the part of a user installing many packages. This means,
1051 amongst other things, using the <tt>--quiet</tt> option on
1052 <prgn>install-info</prgn>.</p>
1055 Errors which occur during the execution of an installation
1056 script must be checked and the installation must not
1057 continue after an error.
1061 Note that in general <ref id="scripts"> applies to package
1062 maintainer scripts, too.
1066 You should not use <prgn>dpkg-divert</prgn> on a file
1067 belonging to another package without consulting the
1068 maintainer of that package first.
1072 All packages which supply an instance of a common command
1073 name (or, in general, filename) should generally use
1074 <prgn>update-alternatives</prgn>, so that they may be
1075 installed together. If <prgn>update-alternatives</prgn>
1076 is not used, then each package must use
1077 <tt>Conflicts</tt> to ensure that other packages are
1078 de-installed. (In this case, it may be appropriate to
1079 specify a conflict against earlier versions of something
1080 that previously did not use
1081 <prgn>update-alternatives</prgn>; this is an exception to
1082 the usual rule that versioned conflicts should be
1088 <heading>Prompting in maintainer scripts</heading>
1090 Package maintainer scripts may prompt the user if
1091 necessary. Prompting may be accomplished by hand, or by
1092 communicating with a program, such as
1093 <prgn>debconf</prgn>, which conforms to the Debian
1094 Configuration management specification, version 2 or
1095 higher. These are included in the
1096 <file>debconf_specification</file> files in the
1097 <package>debian-policy</package> package.
1098 You may also find this file on the FTP site
1099 <ftpsite>ftp.debian.org</ftpsite> in
1100 <ftppath>/debian/doc/package-developer/debconf_specification.txt.gz</ftppath>
1101 or on your local mirror.<footnote>
1103 4% of Debian packages [see <url
1104 id="http://kitenet.net/programs/debconf/stats/"
1105 name="Debconf stats">] currently use
1106 <package>debconf</package> to prompt the user at
1107 install time, and this number is growing daily. The
1108 benefits of using debconf are briefly explained at
1110 id="http://kitenet.net/doc/debconf-doc/introduction.html"
1111 name="Debconf introduction">; they include
1112 preconfiguration, (mostly) noninteractive
1113 installation, elimination of redundant prompting,
1114 consistency of user interface, etc.
1117 With this increasing number of packages using
1118 <package>debconf</package>, plus the existance of a
1119 nascent second implementation of the Debian
1120 configuration management system
1121 (<package>cdebconf</package>), and the stabilization
1122 of the protocol these things use, the time has
1123 finally come to reflect the use of these things in
1130 Packages which use the Debian Configuration management
1131 specification may contain an additional
1132 <prgn>config</prgn> script and a <tt>templates</tt>
1133 file in their control archive. The <prgn>config</prgn>
1134 script might be run before the <prgn>preinst</prgn>
1135 script, and before the package is unpacked or any of its
1136 dependencies or pre-dependancies are satisfied.
1137 Therefore it must work using only the tools present in
1138 <em>essential</em> packages.<footnote>
1140 <package>Debconf</package> or another tool that
1141 implements the Debian Configuration management
1142 specification will also be installed, and any
1143 versioned dependencies on it will be satisfied
1144 before preconfiguration begins.
1150 Packages should try to minimize the amount of prompting
1151 they need to do, and they should ensure that the user
1152 will only ever be asked each question once. This means
1153 that packages should try to use appropriate shared
1154 configuration files (such as <file>/etc/papersize</file> and
1155 <file>/etc/news/server</file>), and shared
1156 <package>debconf</package> variables rather than each
1157 prompting for their own list of required pieces of
1162 It also means that an upgrade should not ask the same
1163 questions again, unless the user has used <tt>dpkg
1164 --purge</tt> to remove the package's configuration. The
1165 answers to configuration questions should be stored in an
1166 appropriate place in <file>/etc</file> so that the user can
1167 modify them, and how this has been done should be
1171 If a package has a vitally important piece of
1172 information to pass to the user (such as "don't run me
1173 as I am, you must edit the following configuration files
1174 first or you risk your system emitting badly-formatted
1175 messages"), it should display this in the
1176 <prgn>config</prgn> or <prgn>postinst</prgn> script and
1177 prompt the user to hit return to acknowledge the
1178 message. Copyright messages do not count as vitally
1179 important (they belong in
1180 <file>/usr/share/doc/<var>package</var>/copyright</file>);
1181 neither do instructions on how to use a program (these
1182 should be in on-line documentation, where all the users
1186 Any necessary prompting should almost always be confined
1187 to the <prgn>config</prgn> or <prgn>postinst</prgn>
1188 script. If it is done in the <prgn>postinst</prgn>, it
1189 should be protected with a conditional so that
1190 unnecessary prompting doesn't happen if a package's
1191 installation fails and the <prgn>postinst</prgn> is
1192 called with <tt>abort-upgrade</tt>,
1193 <tt>abort-remove</tt> or <tt>abort-deconfigure</tt>.</p>
1198 <heading>Source packages</heading>
1200 <sect1 id="standardsversion">
1201 <heading>Standards conformance</heading>
1204 In the source package's <tt>Standards-Version</tt> control
1205 field, you should specify the most recent version number
1206 of this policy document with which your package complied
1207 when it was last updated. The current version number is
1212 This information may be used to file bug reports
1213 automatically if your package becomes too much out of
1218 The version number has four components: major and minor
1219 version number and major and minor patch level. When the
1220 standards change in a way that requires every package to
1221 change the major number will be changed. Significant
1222 changes that will require work in many packages will be
1223 signaled by a change to the minor number. The major patch
1224 level will be changed for any change to the meaning of the
1225 standards, however small; the minor patch level will be
1226 changed when only cosmetic, typographical or other edits
1227 are made which neither change the meaning of the document
1228 nor affect the contents of packages.</p>
1231 Thus only the first three components of the policy version
1232 are significant in the <em>Standards-Version</em> control
1233 field, and so either these three components or the all
1234 four components may be specified.<footnote>
1236 In the past, people specified the full version number
1237 in the Standards-Version field, for example "2.3.0.0".
1238 Since minor patch-level changes don"t introduce new
1239 policy, it was thought it would be better to relax
1240 policy and only require the first 3 components to be
1241 specified, in this example "2.3.0". All four
1242 components may still be used if someone wishes to do
1249 You should regularly, and especially if your package has
1250 become out of date, check for the newest Policy Manual
1251 available and update your package, if necessary. When your
1252 package complies with the new standards you should update the
1253 <tt>Standards-Version</tt> source package field and
1254 release it.<footnote>
1256 See the file <file>upgrading-checklist</file> for
1257 information about policy which has changed between
1258 different versions of this document.
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 <heading>Changes to the upstream sources</heading>
1356 If changes to the source code are made that are not
1357 specific to the needs of the Debian system, they should be
1358 sent to the upstream authors in whatever form they prefer
1359 so as to be included in the upstream version of the
1363 If you need to configure the package differently for
1364 Debian or for Linux, and the upstream source doesn't
1365 provide a way to do so, you should add such configuration
1366 facilities (for example, a new <prgn>autoconf</prgn> test
1367 or <tt>#define</tt>) and send the patch to the upstream
1368 authors, with the default set to the way they originally
1369 had it. You can then easily override the default in your
1370 <file>debian/rules</file> or wherever is appropriate.</p>
1373 You should make sure that the <prgn>configure</prgn> utility
1374 detects the correct architecture specification string
1375 (refer to <ref id="arch-spec"> for details).</p>
1378 If you need to edit a <prgn>Makefile</prgn> where
1379 GNU-style <prgn>configure</prgn> scripts are used, you
1380 should edit the <file>.in</file> files rather than editing the
1381 <prgn>Makefile</prgn> directly. This allows the user to
1382 reconfigure the package if necessary. You should
1383 <em>not</em> configure the package and edit the generated
1384 <prgn>Makefile</prgn>! This makes it impossible for
1385 someone else to later reconfigure the package.</p>
1388 You should document your changes and updates to the source
1389 package properly in the <file>debian/changelog</file> file.
1390 For more information, please see <ref id="changelogs">.
1396 <heading>Error trapping in makefiles</heading>
1399 When <prgn>make</prgn> invokes a command in a makefile
1400 (including your package's upstream makefiles and
1401 <file>debian/rules</file>), it does so using <prgn>sh</prgn>. This
1402 means that <prgn>sh</prgn>'s usual bad error handling
1403 properties apply: if you include a miniature script as one
1404 of the commands in your makefile you'll find that if you
1405 don't do anything about it then errors are not detected
1406 and <prgn>make</prgn> will blithely continue after
1410 Every time you put more than one shell command (this
1411 includes using a loop) in a makefile command you
1412 must make sure that errors are trapped. For
1413 simple compound commands, such as changing directory and
1414 then running a program, using <tt>&&</tt> rather
1415 than semicolon as a command separator is sufficient. For
1416 more complex commands including most loops and
1417 conditionals you should include a separate <tt>set -e</tt>
1418 command at the start of every makefile command that's
1419 actually one of these miniature shell scripts.</p></sect1>
1423 <heading>Obsolete constructs and libraries</heading>
1426 The include file <tt><varargs.h></tt> is
1427 provided to support end-users compiling very old software;
1428 the library <tt>libtermcap</tt> is provided to support the
1429 execution of software which has been linked against it
1430 (either old programs or those such as Netscape which are
1431 only available in binary form).</p>
1434 Debian packages should be patched to use
1435 <tt><stdarg.h></tt> and <tt>ncurses</tt>
1442 <chapt id="controlfields"><heading>Control files and their fields</heading>
1445 Many of the tools in the package management suite manipulate
1446 data represented in a common format, known as <em>control
1447 data</em>. The data is often stored in <em>control
1448 files</em>. Binary and source packages have control files,
1449 and the <file>.changes</file> files which control the installation
1450 of uploaded files are also in control file format.
1451 <prgn>dpkg</prgn>'s internal databases are in a similar
1455 <sect id="controlsyntax"><heading>Syntax of control files</heading>
1458 A control file consists of one or more paragraphs of fields.
1459 The paragraphs are separated by blank lines. Some control
1460 files allow only one paragraph; others allow several, in
1461 which case each paragraph usually refers to a different
1462 package. (For example, in source packages, the first
1463 paragraph refers to the source package, and later paragraphs
1464 refer to binary packages generated from the source.)
1468 Each paragraph consists of a series of data fields; each
1469 field consists of the field name, followed by a colon and
1470 then the data/value associated with that field. It ends at
1471 the end of the line. Horizontal whitespace (spaces and
1472 tabs) may occur immediately before or after the value and is
1473 ignored there; it is conventional to put a single space
1474 after the colon. For example, a field might be:
1475 <example compact="compact">
1478 the field name is <tt>Package</tt> and the field value
1483 Some fields' values may span several lines; in this case
1484 each continuation line <em>must</em> start with a space or
1485 tab. Any trailing spaces or tabs at the end of individual
1486 lines of a field value are ignored.
1490 Except where otherwise stated only a single line of data is
1491 allowed and whitespace is not significant in a field body.
1492 Whitespace must not appear inside names (of packages,
1493 architectures, files or anything else) or version numbers,
1494 or between the characters of multi-character version
1499 Field names are not case-sensitive, but it is usual to
1500 capitalize the field names using mixed case as shown below.
1504 Blank lines, or lines consisting only of spaces and tabs,
1505 are not allowed within field values or between fields - that
1506 would mean a new paragraph.
1511 <sect><heading>List of fields</heading>
1513 This list here is not supposed to be exhaustive. Most fields
1514 are dealt with elsewhere in this document.
1516 <sect1 id="f-Package"><heading><tt>Package</tt>
1520 The name of the binary package. Package names consist of
1521 lower case letters (<tt>a-z</tt>), digits (<tt>0-9</tt>),
1522 plus (<tt>+</tt>) and minus (<tt>-</tt>) signs, and
1523 periods (<tt>.</tt>).
1527 They must be at least two characters long and must start
1528 with an alphanumeric character. The use of lowercase
1529 package names is required unless the package you're
1530 building (or referring to, in other fields) is already
1531 using uppercase characters.</p>
1534 <sect1 id="f-Version"><heading><tt>Version</tt>
1538 This lists the source or binary package's version number -
1539 see <ref id="versions">.
1545 id="f-Standards-Version"><heading><tt>Standards-Version</tt>
1549 The most recent version of the standards (the policy
1550 manual and associated texts) with which the package
1551 complies. This is updated manually when editing the
1552 source package to conform to newer standards; it can
1553 sometimes be used to tell when a package needs attention.
1554 Its format is described above; see
1555 <ref id="standardsversion">.
1560 <sect1 id="f-Distribution"><heading><tt>Distribution</tt>
1564 In a <file>.changes</file> file or parsed changelog output
1565 this contains the (space-separated) name(s) of the
1566 distribution(s) where this version of the package should
1567 be installed. Valid distributions are determined by the
1568 archive maintainers.<footnote>
1569 Current distribution names are:
1570 <taglist compact="compact">
1571 <tag><em>stable</em></tag>
1574 This is the current "released" version of Debian
1575 GNU/Linux. Once the distribution is
1576 <em>stable</em> only security fixes and other
1577 major bug fixes are allowed. When changes are
1578 made to this distribution, the release number is
1579 increased (for example: 2.2r1 becomes 2.2r2 then
1584 <tag><em>unstable</em></tag>
1587 This distribution value refers to the
1588 <em>developmental</em> part of the Debian
1589 distribution tree. New packages, new upstream
1590 versions of packages and bug fixes go into the
1591 <em>unstable</em> directory tree. Download from
1592 this distribution at your own risk.
1596 <tag><em>testing</em></tag>
1599 This distribution value refers to the
1600 <em>testing</em> part of the Debian distribution
1601 tree. It receives its packages from the
1602 unstable distribution after a short time lag to
1603 ensure that there are no major issues with the
1604 unstable packages. It is less prone to breakage
1605 than unstable, but still risky. It is not
1606 possible to upload packages directly to
1611 <tag><em>frozen</em></tag>
1614 From time to time, the <em>testing</em>
1615 distribution enters a state of "code-freeze" in
1616 anticipation of release as a <em>stable</em>
1617 version. During this period of testing only
1618 fixes for existing or newly-discovered bugs will
1619 be allowed. The exact details of this stage are
1620 determined by the Release Manager.
1624 <tag><em>experimental</em></tag>
1627 The packages with this distribution value are
1628 deemed by their maintainers to be high
1629 risk. Oftentimes they represent early beta or
1630 developmental packages from various sources that
1631 the maintainers want people to try, but are not
1632 ready to be a part of the other parts of the
1633 Debian distribution tree. Download at your own
1639 You should list <em>all</em> distributions that the
1640 package should be installed into.
1649 <chapt id="versions"><heading>Version numbering</heading>
1652 Every package has a version number recorded in its
1653 <tt>Version</tt> control file field.
1657 The package management system imposes an ordering on version
1658 numbers, so that it can tell whether packages are being up- or
1659 downgraded and so that package system front end applications
1660 can tell whether a package it finds available is newer than
1661 the one installed on the system. The version number format
1662 has the most significant parts (as far as comparison is
1663 concerned) at the beginning.
1667 The version number format is:
1668 [<var>epoch</var><tt>:</tt>]<var>upstream_version</var>[<tt>-</tt><var>debian_revision</var>]
1672 The three components here are:
1674 <tag><var>epoch</var></tag>
1677 This is a single (generally small) unsigned integer. It
1678 may be omitted, in which case zero is assumed. If it is
1679 omitted then the <var>upstream_version</var> may not
1684 It is provided to allow mistakes in the version numbers
1685 of older versions of a package, and also a package's
1686 previous version numbering schemes, to be left behind.
1690 <tag><var>upstream_version</var></tag>
1693 This is the main part of the version number. It is
1694 usually the version number of the original ("upstream")
1695 package from which the <file>.deb</file> file has been made,
1696 if this is applicable. Usually this will be in the same
1697 format as that specified by the upstream author(s);
1698 however, it may need to be reformatted to fit into the
1699 package management system's format and comparison
1704 The comparison behavior of the package management system
1705 with respect to the <var>upstream_version</var> is
1706 described below. The <var>upstream_version</var>
1707 portion of the version number is mandatory.
1711 The <var>upstream_version</var> may contain only
1712 alphanumerics<footnote>
1713 <p>Alphanumerics are <tt>A-Za-z0-9</tt> only.</p>
1715 and the characters <tt>.</tt> <tt>+</tt> <tt>-</tt>
1716 <tt>:</tt> (full stop, plus, hyphen, colon) and should
1717 start with a digit. If there is no
1718 <var>debian_revision</var> then hyphens are not allowed;
1719 if there is no <var>epoch</var> then colons are not
1723 <tag><var>debian_revision</var></tag>
1726 This part of the version number specifies the version of
1727 the Debian package based on the upstream version. It
1728 may contain only alphanumerics and the characters
1729 <tt>+</tt> and <tt>.</tt> (plus and full stop) and is
1730 compared in the same way as the
1731 <var>upstream_version</var> is.
1735 It is optional; if it isn't present then the
1736 <var>upstream_version</var> may not contain a hyphen.
1737 This format represents the case where a piece of
1738 software was written specifically to be turned into a
1739 Debian package, and so there is only one "debianization"
1740 of it and therefore no revision indication is required.
1744 It is conventional to restart the
1745 <var>debian_revision</var> at <tt>1</tt> each time the
1746 <var>upstream_version</var> is increased.
1750 The package management system will break the version
1751 number apart at the last hyphen in the string (if there
1752 is one) to determine the <var>upstream_version</var> and
1753 <var>debian_revision</var>. The absence of a
1754 <var>debian_revision</var> compares earlier than the
1755 presence of one (but note that the
1756 <var>debian_revision</var> is the least significant part
1757 of the version number).
1764 The <var>upstream_version</var> and <var>debian_revision</var>
1765 parts are compared by the package management system using the
1770 The strings are compared from left to right.
1774 First the initial part of each string consisting entirely of
1775 non-digit characters is determined. These two parts (one of
1776 which may be empty) are compared lexically. If a difference
1777 is found it is returned. The lexical comparison is a
1778 comparison of ASCII values modified so that all the letters
1779 sort earlier than all the non-letters.
1783 Then the initial part of the remainder of each string which
1784 consists entirely of digit characters is determined. The
1785 numerical values of these two parts are compared, and any
1786 difference found is returned as the result of the comparison.
1787 For these purposes an empty string (which can only occur at
1788 the end of one or both version strings being compared) counts
1793 These two steps (comparing and removing initial non-digit
1794 strings and initial digit strings) are repeated until a
1795 difference is found or both strings are exhausted.
1799 Note that the purpose of epochs is to allow us to leave behind
1800 mistakes in version numbering, and to cope with situations
1801 where the version numbering scheme changes. It is
1802 <em>not</em> intended to cope with version numbers containing
1803 strings of letters which the package management system cannot
1804 interpret (such as <tt>ALPHA</tt> or <tt>pre-</tt>), or with
1805 silly orderings (the author of this manual has heard of a
1806 package whose versions went <tt>1.1</tt>, <tt>1.2</tt>,
1807 <tt>1.3</tt>, <tt>1</tt>, <tt>2.1</tt>, <tt>2.2</tt>,
1808 <tt>2</tt> and so forth).
1812 If an upstream package has problematic version numbers they
1813 should be converted to a sane form for use in the
1814 <tt>Version</tt> field.
1818 <heading>Version numbers based on dates</heading>
1820 In general, Debian packages should use the same version
1821 numbers as the upstream sources.</p>
1824 However, in some cases where the upstream version number is
1825 based on a date (e.g., a development "snapshot" release) the
1826 package management system cannot handle these version
1827 numbers without epochs. For example, dpkg will consider
1828 "96May01" to be greater than "96Dec24".</p>
1831 To prevent having to use epochs for every new upstream
1832 version, the version number should be changed to the
1833 following format in such cases: "19960501", "19961224". It
1834 is up to the maintainer whether he/she wants to bother the
1835 upstream maintainer to change the version numbers upstream,
1839 Note that other version formats based on dates which are
1840 parsed correctly by the package management system should
1841 <em>not</em> be changed.</p>
1844 Native Debian packages (i.e., packages which have been
1845 written especially for Debian) whose version numbers include
1846 dates should always use the "YYYYMMDD" format.</p>
1850 <chapt id="miscellaneous"><heading>Packaging Considerations</heading>
1852 <sect id="timestamps"><heading>Time Stamps</heading>
1854 Maintainers should preserve the modification times of the
1855 upstream source files in a package, as far as is reasonably
1858 The rationale is that there is some information conveyed
1859 by knowing the age of the file, for example, you could
1860 recognize that some documentation is very old by looking
1861 at the modification time, so it would be nice if the
1862 modification time of the upstream source would be
1869 <sect id="debianrules"><heading><file>debian/rules</file> - the
1870 main building script</heading>
1873 This file must be an executable makefile, and contains the
1874 package-specific recipes for compiling the package and
1875 building binary package(s) from the source.
1879 It must start with the line <tt>#!/usr/bin/make -f</tt>,
1880 so that it can be invoked by saying its name rather than
1881 invoking <prgn>make</prgn> explicitly.
1885 Since an interactive <file>debian/rules</file> script makes it
1886 impossible to auto-compile that package and also makes it
1887 hard for other people to reproduce the same binary
1888 package, all <em>required targets</em> MUST be
1889 non-interactive. At a minimum, required targets are the
1890 ones called by <prgn>dpkg-buildpackage</prgn>, namely,
1891 <em>clean</em>, <em>binary</em>, <em>binary-arch</em>,
1892 <em>binary-indep</em>, and <em>build</em>. It also follows
1893 that any target that these targets depend on must also be
1898 The required and optional targets are as follows:
1900 <tag><tt>build</tt>, <tt>build-arch</tt> (optional),
1901 <tt>build-indep</tt> (optional)</tag>
1904 The <tt>build</tt> target should perform all
1905 non-interactive configuration and compilation of the
1906 package. If a package has an interactive pre-build
1907 configuration routine, the Debianized source package
1908 must either be built after this has taken place (so
1909 that the binary package can be built without rerunning
1910 the configuration) or the configuration routine
1911 modified to become non-interactive. (The latter is
1912 preferable if there are architecture-specific features
1913 detected by the configuration routine.)
1917 For some packages, notably ones where the same
1918 source tree is compiled in different ways to produce
1919 two binary packages, the <tt>build</tt> target
1920 does not make much sense. For these packages it is
1921 good enough to provide two (or more) targets
1922 (<tt>build-a</tt> and <tt>build-b</tt> or whatever)
1923 for each of the ways of building the package, and a
1924 <tt>build</tt> target that does nothing. The
1925 <tt>binary</tt> target will have to build the
1926 package in each of the possible ways and make the
1927 binary package out of each.
1931 The <tt>build</tt> target must not do anything
1932 that might require root privilege.
1936 The <tt>build</tt> target may need to run the
1937 <tt>clean</tt> target first - see below.
1941 When a package has a configuration and build routine
1942 which takes a long time, or when the makefiles are
1943 poorly designed, or when <tt>build</tt> needs to
1944 run <tt>clean</tt> first, it is a good idea to
1945 <tt>touch build</tt> when the build process is
1946 complete. This will ensure that if <tt>debian/rules
1947 build</tt> is run again it will not rebuild the whole
1950 Another common way to do this is for <tt>build</tt>
1951 to depend on <prgn>build-stamp</prgn> and to do
1952 nothing else, and for the <prgn>build-stamp</prgn>
1953 target to do the building and to <tt>touch
1954 build-stamp</tt> on completion. This is
1955 especially useful if the build routine creates a
1956 file or directory called <tt>build</tt>; in such a
1957 case, <tt>build</tt> will need to be listed as
1958 a phony target (i.e., as a dependency of the
1959 <tt>.PHONY</tt> target). See the documentation of
1960 <prgn>make</prgn> for more information on phony
1967 <tag><tt>binary</tt>, <tt>binary-arch</tt>,
1968 <tt>binary-indep</tt>
1972 The <tt>binary</tt> target must be all that is
1973 necessary for the user to build the binary package(s)
1974 produced from this source package. All of these
1975 targets are required to be non-interactive. It is
1976 split into two parts: <prgn>binary-arch</prgn> builds
1977 the binary packages which are specific to a particular
1978 architecture, and <tt>binary-indep</tt> builds
1979 those which are not.
1982 <tt>binary</tt> may be (and commonly is) a target with
1983 no commands which simply depends on
1984 <tt>binary-arch</tt> and <tt>binary-indep</tt>.
1987 Both <tt>binary-*</tt> targets should depend on the
1988 <tt>build</tt> target, or on the appropriate
1989 <tt>build-arch</tt> or <tt>build-indep</tt> target, if
1990 provided, so that the package is built if it has not
1991 been already. It should then create the relevant
1992 binary package(s), using <prgn>dpkg-gencontrol</prgn> to
1993 make their control files and <prgn>dpkg-deb</prgn> to
1994 build them and place them in the parent of the top
1999 Both the <tt>binary-arch</tt> and
2000 <tt>binary-indep</tt> targets <em>must</em> exist.
2001 If one of them has nothing to do (which will always be
2002 the case if the source generates only a single binary
2003 package, whether architecture-dependent or not), it
2004 must still exist and must always succeed.
2008 The <tt>binary</tt> targets must be invoked as
2011 The <prgn>fakeroot</prgn> package often allows one
2012 to build a package correctly even without being
2019 <tag><tt>clean</tt></tag>
2022 This must undo any effects that the <tt>build</tt>
2023 and <tt>binary</tt> targets may have had, except
2024 that it should leave alone any output files created in
2025 the parent directory by a run of a <tt>binary</tt>
2026 target. This target must be non-interactive.
2030 If a <tt>build</tt> file is touched at the end of
2031 the <tt>build</tt> target, as suggested above, it
2032 should be removed as the first action that
2033 <tt>clean</tt> performs, so that running
2034 <tt>build</tt> again after an interrupted
2035 <tt>clean</tt> doesn't think that everything is
2040 The <tt>clean</tt> target may need to be
2041 invoked as root if <tt>binary</tt> has been
2042 invoked since the last <tt>clean</tt>, or if
2043 <tt>build</tt> has been invoked as root (since
2044 <tt>build</tt> may create directories, for
2049 <tag><tt>get-orig-source</tt> (optional)</tag>
2052 This target fetches the most recent version of the
2053 original source package from a canonical archive site
2054 (via FTP or WWW, for example), does any necessary
2055 rearrangement to turn it into the original source
2056 tar file format described below, and leaves it in the
2061 This target may be invoked in any directory, and
2062 should take care to clean up any temporary files it
2067 This target is optional, but providing it if
2068 possible is a good idea.
2074 The <tt>build</tt>, <tt>binary</tt> and
2075 <tt>clean</tt> targets must be invoked with the current
2076 directory being the package's top-level directory.
2081 Additional targets may exist in <file>debian/rules</file>,
2082 either as published or undocumented interfaces or for the
2083 package's internal use.
2087 The architectures we build on and build for are determined
2088 by <prgn>make</prgn> variables using the utility
2089 <prgn>dpkg-architecture</prgn>. You can determine the
2090 Debian architecture and the GNU style architecture
2091 specification string for the build machine (the machine type
2092 we are building on) as well as for the host machine (the
2093 machine type we are building for). Here is a list of
2094 supported <prgn>make</prgn> variables:
2095 <list compact="compact">
2097 <p><tt>DEB_*_ARCH</tt> (the Debian architecture)</p>
2100 <p><tt>DEB_*_GNU_TYPE</tt> (the GNU style architecture
2101 specification string)</p>
2104 <p><tt>DEB_*_GNU_CPU</tt> (the CPU part of
2105 <tt>DEB_*_GNU_TYPE</tt>)</p>
2108 <p><tt>DEB_*_GNU_SYSTEM</tt> (the System part of
2109 <tt>DEB_*_GNU_TYPE</tt>)</p>
2111 where <tt>*</tt> is either <tt>BUILD</tt> for specification of
2112 the build machine or <tt>HOST</tt> for specification of the
2117 Backward compatibility can be provided in the rules file
2118 by setting the needed variables to suitable default
2119 values; please refer to the documentation of
2120 <prgn>dpkg-architecture</prgn> for details.
2124 It is important to understand that the <tt>DEB_*_ARCH</tt>
2125 string only determines which Debian architecture we are
2126 building on or for. It should not be used to get the CPU
2127 or system information; the GNU style variables should be
2132 <sect id="dpkgchangelog"><heading><file>debian/changelog</file>
2136 This file records the changes to the Debian-specific parts of the
2139 Though there is nothing stopping an author who is also
2140 the Debian maintainer from using it for all their
2141 changes, it will have to be renamed if the Debian and
2142 upstream maintainers become different people. In such a
2143 case, however, it might be better to maintain the
2144 package as a non-native package.
2150 It has a special format which allows the package building
2151 tools to discover which version of the package is being
2152 built and find out other release-specific information.
2156 That format is a series of entries like this:
2157 <example compact="compact">
2158 <var>package</var> (<var>version</var>) <var>distribution(s)</var>; urgency=<var>urgency</var>
2160 <p>[optional blank line(s), stripped]</p>
2162 * <var>change details</var>
2163 <var>more change details</var>
2165 <p>[blank line(s), included in output of dpkg-parsechangelog]</p>
2167 * <var>even more change details</var>
2169 <p>[optional blank line(s), stripped]</p>
2171 -- <var>maintainer name</var> <<var>email
2172 address</var>><var>[two spaces]</var> <var>date</var>
2177 <var>package</var> and <var>version</var> are the source
2178 package name and version number.
2182 <var>distribution(s)</var> lists the distributions where
2183 this version should be installed when it is uploaded - it
2184 is copied to the <tt>Distribution</tt> field in the
2185 <file>.changes</file> file. See <ref id="f-Distribution">.
2189 <var>urgency</var> is the value for the <tt>Urgency</tt>
2190 field in the <file>.changes</file> file for the upload. It is
2191 not possible to specify an urgency containing commas; commas
2192 are used to separate
2193 <tt><var>keyword</var>=<var>value</var></tt> settings in the
2194 <prgn>dpkg</prgn> changelog format (though there is
2195 currently only one useful <var>keyword</var>,
2196 <tt>urgency</tt>).<footnote>
2198 Recognised urgency values are <tt>low</tt>,
2199 <tt>medium</tt>, <tt>high</tt> and <tt>emergency</tt>.
2200 They have an effect on how quickly a package will be
2201 considered for inclusion into the <tt>testing</tt>
2202 distribution, and give an indication of the importance
2203 of any fixes included in this upload.
2209 The change details may in fact be any series of lines
2210 starting with at least two spaces, but conventionally each
2211 change starts with an asterisk and a separating space and
2212 continuation lines are indented so as to bring them in
2213 line with the start of the text above. Blank lines may be
2214 used here to separate groups of changes, if desired.
2218 If this upload resolves bugs recorded in the Bug Tracking
2219 System (BTS), they may be automatically closed on the
2220 inclusion of this package into the Debian archive by
2221 including the string: <tt>closes: Bug#<var>nnnnn</var></tt>
2222 in the change details.<footnote>
2224 To be precise, the string should match the following
2225 Perl regular expression:
2227 /closes:\s*(?:bug)?\#?\s?\d+(?:,\s*(?:bug)?\#?\s?\d+)*/i
2229 Then all of the bug numbers listed will be closed by the
2230 archive maintenance script (<prgn>katie</prgn>), or in
2231 the case of an NMU, marked as fixed.
2237 The maintainer name and email address used in the changelog
2238 should be the details of the person uploading <em>this</em>
2239 version. They are <em>not</em> necessarily those of the
2240 usual package maintainer. The information here will be
2241 copied to the <tt>Changed-By</tt> field in the
2242 <tt>.changes</tt> file, and then later used to send an
2243 acknowledgement when the upload has been installed.
2247 The <var>date</var> should be in RFC822 format<footnote>
2249 This is generated by the <prgn>822-date</prgn>
2252 </footnote>; it should include the time zone specified
2253 numerically, with the time zone name or abbreviation
2254 optionally present as a comment in parentheses.
2258 The first "title" line with the package name should start
2259 at the left hand margin; the "trailer" line with the
2260 maintainer and date details should be preceded by exactly
2261 one space. The maintainer details and the date must be
2262 separated by exactly two spaces.
2265 <sect1><heading>Defining alternative changelog formats</heading>
2268 It is possible to use a different format to the standard
2269 one, by providing a parser for the format you wish to
2273 A changelog parser must not interact with the user at
2279 <!-- FIXME: section pkg-srcsubstvars is the same as srcsubstvars -->
2281 <sect id="srcsubstvars"><heading><file>debian/substvars</file>
2282 and variable substitutions </heading>
2285 When <prgn>dpkg-gencontrol</prgn>,
2286 <prgn>dpkg-genchanges</prgn> and <prgn>dpkg-source</prgn>
2287 generate control files they perform variable substitutions
2288 on their output just before writing it. Variable
2289 substitutions have the form <tt>${<var>variable</var>}</tt>.
2290 The optional file <file>debian/substvars</file> contains
2291 variable substitutions to be used; variables can also be set
2292 directly from <file>debian/rules</file> using the <tt>-V</tt>
2293 option to the source packaging commands, and certain
2294 predefined variables are also available.
2298 The <file>debian/substvars</file> file is usually generated and
2299 modified dynamically by <file>debian/rules</file> targets, in
2300 which case it must be removed by the <tt>clean</tt> target.
2304 See <manref name="dpkg-source" section="1"> for full
2305 details about source variable substitutions, including the
2306 format of <file>debian/substvars</file>.</p>
2309 <sect id="debianfiles"><heading><file>debian/files</file>
2313 This file is not a permanent part of the source tree; it
2314 is used while building packages to record which files are
2315 being generated. <prgn>dpkg-genchanges</prgn> uses it
2316 when it generates a <file>.changes</file> file.
2320 It should not exist in a shipped source package, and so it
2321 (and any backup files or temporary files such as
2322 <file>files.new</file><footnote>
2324 <file>files.new</file> is used as a temporary file by
2325 <prgn>dpkg-gencontrol</prgn> and
2326 <prgn>dpkg-distaddfile</prgn> - they write a new
2327 version of <tt>files</tt> here before renaming it,
2328 to avoid leaving a corrupted copy if an error
2331 </footnote>) should be removed by the
2332 <tt>clean</tt> target. It may also be wise to
2333 ensure a fresh start by emptying or removing it at the
2334 start of the <tt>binary</tt> target.
2338 When <prgn>dpkg-gencontrol</prgn> is run for a binary
2339 package, it adds an entry to <file>debian/files</file> for the
2340 <file>.deb</file> file that will be created when <tt>dpkg-deb
2341 --build</tt> is run for that binary package. So for most
2342 packages all that needs to be done with this file is to
2343 delete it in the <tt>clean</tt> target.
2347 If a package upload includes files besides the source
2348 package and any binary packages whose control files were
2349 made with <prgn>dpkg-gencontrol</prgn> then they should be
2350 placed in the parent of the package's top-level directory
2351 and <prgn>dpkg-distaddfile</prgn> should be called to add
2352 the file to the list in <file>debian/files</file>.</p>
2355 <sect id="restrictions"><heading>Restrictions on objects in source packages
2359 The source package may not contain any hard links<footnote>
2361 This is not currently detected when building source
2362 packages, but only when extracting
2366 Hard links may be permitted at some point in the
2367 future, but would require a fair amount of
2370 </footnote>, device special files, sockets or setuid or
2371 setgid files.<footnote>
2373 Setgid directories are allowed.
2379 <sect id="descriptions"><heading>Descriptions of packages - the
2380 <tt>Description</tt> field</heading>
2383 The "Description" control file field consists of two parts,
2384 the synopsis or the short description, and the long description.
2385 The field's format is as follows:
2389 Description: <single line synopsis>
2390 <extended description over several lines>
2394 The description is intended to describe the program to a user
2395 who has never met it before so that they know whether they
2396 want to install it. It should also give information about the
2397 significant dependencies and conflicts between this package
2398 and others, so that the user knows why these dependencies and
2399 conflicts have been declared.
2403 Put important information first, both in the synopsis and
2404 extended description. Sometimes only the first part of the
2405 synopsis or of the description will be displayed. You can
2406 assume that there will usually be a way to see the whole
2407 extended description.
2410 <sect1 id="synopsis"><heading>The single line synopsis</heading>
2413 The single line synopsis should be kept brief - certainly
2414 under 80 characters.
2418 Do not include the package name in the synopsis line. The
2419 display software knows how to display this already, and you
2420 do not need to state it. Remember that in many situations
2421 the user may only see the synopsis line - make it as
2422 informative as you can.
2427 <sect1 id="extendeddesc"><heading>The extended description</heading>
2430 Do not try to continue the single line synopsis into the
2431 extended description. This will not work correctly when
2432 the full description is displayed, and makes no sense
2433 where only the summary (the single line synopsis) is
2438 The extended description should describe what the package
2439 does and how it relates to the rest of the system (in terms
2440 of, for example, which subsystem it is which part of).
2444 The description field needs to make sense to anyone, even
2445 people who have no idea about any of the things the
2446 package deals with.<footnote>
2447 The blurb that comes with a program in its
2448 announcements and/or <prgn>README</prgn> files is
2449 rarely suitable for use in a description. It is
2450 usually aimed at people who are already in the
2451 community where the package is used.
2456 The lines in the extended description can have these formats:
2462 Those starting with a single space are part of a paragraph.
2463 Successive lines of this form will be word-wrapped when
2464 displayed. The leading space will usually be stripped off.
2468 Those starting with two or more spaces. These will be
2469 displayed verbatim. If the display cannot be panned
2470 horizontally, the displaying program will linewrap them "hard"
2471 (i.e., without taking account of word breaks). If it can they
2472 will be allowed to trail off to the right. None, one or two
2473 initial spaces may be deleted, but the number of spaces
2474 deleted from each line will be the same (so that you can have
2475 indenting work correctly, for example).
2479 Those containing a single space followed by a single full stop
2480 character. These are rendered as blank lines. This is the
2481 <em>only</em> way to get a blank line<footnote>
2482 Completely empty lines will not be rendered as blank lines.
2483 Instead, they will cause the parser to think you're starting
2484 a whole new record in the control file, and will therefore
2485 likely abort with an error.
2490 Those containing a space, a full stop and some more characters.
2491 These are for future expansion. Do not use them.
2497 Do not use tab characters. Their effect is not predictable.
2507 <chapt id="maintainerscripts"><heading>Package maintainer scripts
2508 and installation procedure
2511 <sect><heading>Introduction to package maintainer scripts
2515 It is possible to supply scripts as part of a package which
2516 the package management system will run for you when your
2517 package is installed, upgraded or removed.
2521 These scripts are the files <prgn>preinst</prgn>,
2522 <prgn>postinst</prgn>, <prgn>prerm</prgn> and <prgn>postrm</prgn> in the
2523 control area of the package. They must be proper executable
2524 files; if they are scripts (which is recommended), they must
2525 start with the usual <tt>#!</tt> convention. They should be
2526 readable and executable by anyone, and not world-writable.
2530 The package management system looks at the exit status from
2531 these scripts. It is important that they exit with a
2532 non-zero status if there is an error, so that the package
2533 management system can stop its processing. For shell
2534 scripts this means that you <em>almost always</em> need to
2535 use <tt>set -e</tt> (this is usually true when writing shell
2536 scripts, in fact). It is also important, of course, that
2537 they don't exit with a non-zero status if everything went
2542 When a package is upgraded a combination of the scripts from
2543 the old and new packages is called during the upgrade
2544 procedure. If your scripts are going to be at all
2545 complicated you need to be aware of this, and may need to
2546 check the arguments to your scripts.
2550 Broadly speaking the <prgn>preinst</prgn> is called before
2551 (a particular version of) a package is installed, and the
2552 <prgn>postinst</prgn> afterwards; the <prgn>prerm</prgn>
2553 before (a version of) a package is removed and the
2554 <prgn>postrm</prgn> afterwards.
2558 Programs called from maintainer scripts should not normally
2559 have a path prepended to them. Before installation is
2560 started, the package management system checks to see if the
2561 programs <prgn>ldconfig</prgn>,
2562 <prgn>start-stop-daemon</prgn>, <prgn>install-info</prgn>,
2563 and <prgn>update-rc.d</prgn> can be found via the
2564 <tt>PATH</tt> environment variable. Those programs, and any
2565 other program that one would expect to be on the
2566 <tt>PATH</tt>, should thus be invoked without an absolute
2567 pathname. Maintainer scripts should also not reset the
2568 <tt>PATH</tt>, though they might choose to modify it by
2569 prepending or appending package-specific directories. These
2570 considerations really apply to all shell scripts.</p>
2574 <heading>Maintainer scripts Idempotency</heading>
2577 It is necessary for the error recovery procedures that the
2578 scripts be idempotent. This means that if it is run
2579 successfully, and then it is called again, it doesn't bomb
2580 out or cause any harm, but just ensures that everything is
2581 the way it ought to be. If the first call failed, or
2582 aborted half way through for some reason, the second call
2583 should merely do the things that were left undone the first
2584 time, if any, and exit with a success status if everything
2587 This is so that if an error occurs, the user interrupts
2588 <prgn>dpkg</prgn> or some other unforeseen circumstance
2589 happens you don't leave the user with a badly-broken
2590 package when <prgn>dpkg</prgn> attempts to repeat the
2598 <heading>Controlling terminal for maintainer scripts</heading>
2601 The maintainer scripts are guaranteed to run with a
2602 controlling terminal and can interact with the user.
2603 If they need to prompt for passwords, do full-screen
2604 interaction or something similar you should do these
2605 things to and from <file>/dev/tty</file>, since
2606 <prgn>dpkg</prgn> will at some point redirect scripts'
2607 standard input and output so that it can log the
2608 installation process. Likewise, because these scripts
2609 may be executed with standard output redirected into a
2610 pipe for logging purposes, Perl scripts should set
2611 unbuffered output by setting <tt>$|=1</tt> so that the
2612 output is printed immediately rather than being
2617 Each script should return a zero exit status for
2618 success, or a nonzero one for failure.
2622 <sect id="mscriptsinstact"><heading>Summary of ways maintainer
2627 <list compact="compact">
2629 <p><var>new-preinst</var> <tt>install</tt></p>
2632 <p><var>new-preinst</var> <tt>install</tt>
2633 <var>old-version</var></p>
2636 <p><var>new-preinst</var> <tt>upgrade</tt>
2637 <var>old-version</var></p>
2640 <p><var>old-preinst</var> <tt>abort-upgrade</tt>
2641 <var>new-version</var>
2647 <list compact="compact">
2649 <p><var>postinst</var> <tt>configure</tt>
2650 <var>most-recently-configured-version</var></p>
2653 <p><var>old-postinst</var> <tt>abort-upgrade</tt>
2654 <var>new-version</var></p>
2657 <p><var>conflictor's-postinst</var> <tt>abort-remove</tt>
2658 <tt>in-favour</tt> <var>package</var>
2659 <var>new-version</var></p>
2663 <var>deconfigured's-postinst</var>
2664 <tt>abort-deconfigure</tt> <tt>in-favour</tt>
2665 <var>failed-install-package</var> <var>version</var>
2666 <tt>removing</tt> <var>conflicting-package</var>
2673 <list compact="compact">
2675 <p><var>prerm</var> <tt>remove</tt></p>
2678 <p><var>old-prerm</var> <tt>upgrade</tt>
2679 <var>new-version</var></p>
2682 <p><var>new-prerm</var> <tt>failed-upgrade</tt>
2683 <var>old-version</var></p>
2686 <p><var>conflictor's-prerm</var> <tt>remove</tt>
2687 <tt>in-favour</tt> <var>package</var>
2688 <var>new-version</var></p>
2692 <var>deconfigured's-prerm</var> <tt>deconfigure</tt>
2693 <tt>in-favour</tt> <var>package-being-installed</var>
2694 <var>version</var> <tt>removing</tt>
2695 <var>conflicting-package</var>
2702 <list compact="compact">
2704 <p><var>postrm</var> <tt>remove</tt></p>
2707 <p><var>postrm</var> <tt>purge</tt></p>
2711 <var>old-postrm</var> <tt>upgrade</tt>
2712 <var>new-version</var></p>
2715 <p><var>new-postrm</var> <tt>failed-upgrade</tt>
2716 <var>old-version</var></p>
2719 <p><var>new-postrm</var> <tt>abort-install</tt></p>
2722 <p><var>new-postrm</var> <tt>abort-install</tt>
2723 <var>old-version</var></p>
2726 <p><var>new-postrm</var> <tt>abort-upgrade</tt>
2727 <var>old-version</var></p>
2731 <var>disappearer's-postrm</var> <tt>disappear</tt>
2732 <var>overwriter</var>
2733 <var>overwriter-version</var></p></item>
2738 <sect id="unpackphase"><heading>Details of unpack phase of
2739 installation or upgrade
2743 The procedure on installation/upgrade/overwrite/disappear
2744 (i.e., when running <tt>dpkg --unpack</tt>, or the unpack
2745 stage of <tt>dpkg --install</tt>) is as follows. In each
2746 case, if a major error occurs (unless listed below) the
2747 actions are, in general, run backwards - this means that the
2748 maintainer scripts are run with different arguments in
2749 reverse order. These are the "error unwind" calls listed
2757 <p>If a version of the package is already
2759 <example compact="compact">
2760 <var>old-prerm</var> upgrade <var>new-version</var>
2765 If the script runs but exits with a non-zero
2766 exit status, <prgn>dpkg</prgn> will attempt:
2767 <example compact="compact">
2768 <var>new-prerm</var> failed-upgrade <var>old-version</var>
2770 Error unwind, for both the above cases:
2771 <example compact="compact">
2772 <var>old-postinst</var> abort-upgrade <var>new-version</var>
2780 <p>If a "conflicting" package is being removed at the same time:
2784 If any packages depended on that conflicting
2785 package and <tt>--auto-deconfigure</tt> is
2786 specified, call, for each such package:
2787 <example compact="compact">
2788 <var>deconfigured's-prerm</var> deconfigure \
2789 in-favour <var>package-being-installed</var> <var>version</var> \
2790 removing <var>conflicting-package</var> <var>version</var>
2793 <example compact="compact">
2794 <var>deconfigured's-postinst</var> abort-deconfigure \
2795 in-favour <var>package-being-installed-but-failed</var> <var>version</var> \
2796 removing <var>conflicting-package</var> <var>version</var>
2798 The deconfigured packages are marked as
2799 requiring configuration, so that if
2800 <tt>--install</tt> is used they will be
2801 configured again if possible.</p>
2804 <p>To prepare for removal of the conflicting package, call:
2805 <example compact="compact">
2806 <var>conflictor's-prerm</var> remove \
2807 in-favour <var>package</var> <var>new-version</var>
2810 <example compact="compact">
2811 <var>conflictor's-postinst</var> abort-remove \
2812 in-favour <var>package</var> <var>new-version</var>
2823 <p>If the package is being upgraded, call:
2824 <example compact="compact">
2825 <var>new-preinst</var> upgrade <var>old-version</var>
2830 Otherwise, if the package had some configuration
2831 files from a previous version installed (i.e., it
2832 is in the "configuration files only" state):
2833 <example compact="compact">
2834 <var>new-preinst</var> install <var>old-version</var>
2838 <p>Otherwise (i.e., the package was completely purged):
2839 <example compact="compact">
2840 <var>new-preinst</var> install
2842 Error unwind actions, respectively:
2843 <example compact="compact">
2844 <var>new-postrm</var> abort-upgrade <var>old-version</var>
2845 <var>new-postrm</var> abort-install <var>old-version</var>
2846 <var>new-postrm</var> abort-install
2855 The new package's files are unpacked, overwriting any
2856 that may be on the system already, for example any
2857 from the old version of the same package or from
2858 another package. Backups of the old files are kept
2859 temporarily, and if anything goes wrong the package
2860 management system will attempt to put them back as
2861 part of the error unwind.
2865 It is an error for a package to contains files which
2866 are on the system in another package, unless
2867 <tt>Replaces</tt> is used (see <ref id="replaces">).
2869 The following paragraph is not currently the case:
2870 Currently the <tt>- - force-overwrite</tt> flag is
2871 enabled, downgrading it to a warning, but this may not
2877 It is a more serious error for a package to contain a
2878 plain file or other kind of non-directory where another
2879 package has a directory (again, unless
2880 <tt>Replaces</tt> is used). This error can be
2881 overridden if desired using
2882 <tt>--force-overwrite-dir</tt>, but this is not
2887 Packages which overwrite each other's files produce
2888 behavior which, though deterministic, is hard for the
2889 system administrator to understand. It can easily
2890 lead to "missing" programs if, for example, a package
2891 is installed which overwrites a file from another
2892 package, and is then removed again.<footnote>
2894 Part of the problem is due to what is arguably a
2895 bug in <prgn>dpkg</prgn>.
2901 A directory will never be replaced by a symbolic link
2902 to a directory or vice versa; instead, the existing
2903 state (symlink or not) will be left alone and
2904 <prgn>dpkg</prgn> will follow the symlink if there is
2912 <p>If the package is being upgraded, call
2913 <example compact="compact">
2914 <var>old-postrm</var> upgrade <var>new-version</var>
2919 <p>If this fails, <prgn>dpkg</prgn> will attempt:
2920 <example compact="compact">
2921 <var>new-postrm</var> failed-upgrade <var>old-version</var>
2923 Error unwind, for both cases:
2924 <example compact="compact">
2925 <var>old-preinst</var> abort-upgrade <var>new-version</var>
2932 This is the point of no return - if
2933 <prgn>dpkg</prgn> gets this far, it won't back off
2934 past this point if an error occurs. This will
2935 leave the package in a fairly bad state, which
2936 will require a successful re-installation to clear
2937 up, but it's when <prgn>dpkg</prgn> starts doing
2938 things that are irreversible.
2943 Any files which were in the old version of the package
2944 but not in the new are removed.</p>
2947 <p>The new file list replaces the old.</p>
2950 <p>The new maintainer scripts replace the old.</p>
2954 <p>Any packages all of whose files have been overwritten during the
2955 installation, and which aren't required for
2956 dependencies, are considered to have been removed.
2957 For each such package
2960 <p><prgn>dpkg</prgn> calls:
2961 <example compact="compact">
2962 <var>disappearer's-postrm</var> disappear \
2963 <var>overwriter</var> <var>overwriter-version</var>
2968 <p>The package's maintainer scripts are removed.
2973 It is noted in the status database as being in a
2974 sane state, namely not installed (any conffiles
2975 it may have are ignored, rather than being
2976 removed by <prgn>dpkg</prgn>). Note that
2977 disappearing packages do not have their prerm
2978 called, because <prgn>dpkg</prgn> doesn't know
2979 in advance that the package is going to
2988 Any files in the package we're unpacking that are also
2989 listed in the file lists of other packages are removed
2990 from those lists. (This will lobotomize the file list
2991 of the "conflicting" package if there is one.)
2996 The backup files made during installation, above, are
3003 The new package's status is now sane, and recorded as
3008 Here is another point of no return - if the
3009 conflicting package's removal fails we do not unwind
3010 the rest of the installation; the conflicting package
3011 is left in a half-removed limbo.
3017 If there was a conflicting package we go and do the
3018 removal actions (described below), starting with the
3019 removal of the conflicting package's files (any that
3020 are also in the package being installed have already
3021 been removed from the conflicting package's file list,
3022 and so do not get removed now).
3029 <sect id="configdetails"><heading>Details of configuration</heading>
3032 When we configure a package (this happens with <tt>dpkg
3033 --install</tt> and <tt>dpkg --configure</tt>), we first
3034 update any <tt>conffile</tt>s and then call:
3035 <example compact="compact">
3036 <var>postinst</var> configure <var>most-recently-configured-version</var>
3041 No attempt is made to unwind after errors during
3046 If there is no most recently configured version
3047 <prgn>dpkg</prgn> will pass a null argument; older versions
3048 of dpkg may pass <tt><unknown></tt> (including the
3049 angle brackets) in this case. Even older ones do not pass a
3050 second argument at all, under any circumstances.
3054 <sect id="removedetails"><heading>Details of removal and/or
3055 configuration purging</heading>
3061 <example compact="compact">
3062 <var>prerm</var> remove
3068 The package's files are removed (except <tt>conffile</tt>s).
3073 <example compact="compact">
3074 <var>postrm</var> remove
3080 All the maintainer scripts except the <prgn>postrm</prgn>
3085 If we aren't purging the package we stop here. Note
3086 that packages which have no <prgn>postrm</prgn> and no
3087 <tt>conffile</tt>s are automatically purged when
3088 removed, as there is no difference except for the
3089 <prgn>dpkg</prgn> status.</p>
3093 The <tt>conffile</tt>s and any backup files
3094 (<tt>~</tt>-files, <tt>#*#</tt> files,
3095 <tt>%</tt>-files, <tt>.dpkg-{old,new,tmp}</tt>, etc.)
3100 <example compact="compact">
3101 <var>postrm</var> purge
3106 <p>The package's file list is removed.</p>
3109 No attempt is made to unwind after errors during
3116 <chapt id="relationships"><heading>Declaring relationships between
3120 Packages can declare in their control file that they have
3121 certain relationships to other packages - for example, that
3122 they may not be installed at the same time as certain other
3123 packages, and/or that they depend on the presence of others,
3124 or that they should overwrite files in certain other packages
3129 This is done using the <tt>Depends</tt>, <tt>Pre-Depends</tt>,
3130 <tt>Recommends</tt>, <tt>Suggests</tt>, <tt>Enhances</tt>,
3131 <tt>Conflicts</tt>, <tt>Provides</tt> and <tt>Replaces</tt>
3132 control file fields.
3136 Source packages may declare relationships to binary packages,
3137 saying that they require certain binary packages to be
3138 installed or absent at the time of building the package.
3142 This is done using the <tt>Build-Depends</tt>,
3143 <tt>Build-Depends-Indep</tt>, <tt>Build-Conflicts</tt> and
3144 <tt>Build-Conflicts-Indep</tt> control file fields.
3147 <sect id="depsyntax"><heading>Syntax of relationship fields
3151 These fields all have a uniform syntax. They are a list of
3152 package names separated by commas.
3156 In the <tt>Depends</tt>, <tt>Recommends</tt>,
3157 <tt>Suggests</tt>, <tt>Pre-Depends</tt>,
3158 <tt>Build-Depends</tt> and <tt>Build-Depends-Indep</tt>
3159 control file fields of the package, which declare
3160 dependencies on other packages, the package names listed may
3161 also include lists of alternative package names, separated
3162 by vertical bar (pipe) symbols <tt>|</tt>. In such a case,
3163 if any one of the alternative packages is installed, that
3164 part of the dependency is considered to be satisfied.
3168 All of the fields except for <tt>Provides</tt> may restrict
3169 their applicability to particular versions of each named
3170 package. This is done in parentheses after each individual
3171 package name; the parentheses should contain a relation from
3172 the list below followed by a version number, in the format
3173 described in <ref id="versions">.
3177 The relations allowed are <tt><<</tt>, <tt><=</tt>,
3178 <tt>=</tt>, <tt>>=</tt> and <tt>>></tt> for
3179 strictly earlier, earlier or equal, exactly equal, later or
3180 equal and strictly later, respectively. The deprecated
3181 forms <tt><</tt> and <tt>></tt> were used to mean
3182 earlier/later or equal, rather than strictly earlier/later,
3183 so they should not appear in new packages (though
3184 <prgn>dpkg</prgn> still supports them).
3188 Whitespace may appear at any point in the version
3189 specification subject to the rules in <ref
3190 id="controlsyntax">, and must appear where it's necessary to
3191 disambiguate; it is not otherwise significant. For
3192 consistency and in case of future changes to
3193 <prgn>dpkg</prgn> it is recommended that a single space be
3194 used after a version relationship and before a version
3195 number; it is also conventional to put a single space after
3196 each comma, on either side of each vertical bar, and before
3197 each open parenthesis.
3201 For example, a list of dependencies might appear as:
3202 <example compact="compact">
3205 Depends: libc6 (>= 2.2.1), exim | mail-transport-agent
3210 All fields that specify build-time relationships
3211 (<tt>Build-Depends</tt>, <tt>Build-Depends-Indep</tt>,
3212 <tt>Build-Conflicts</tt> and <tt>Build-Conflicts-Indep</tt>)
3213 may be restricted to a certain set of architectures. This
3214 is indicated in brackets after each individual package name and
3215 the optional version specification. The brackets enclose a
3216 list of Debian architecture names separated by whitespace.
3217 Exclamation marks may be prepended to each of the names.
3218 (It is not permitted for some names to be prepended with
3219 exclamation marks and others not.) If the current Debian
3220 host architecture is not in this list and there are no
3221 exclamation marks in the list, or it is in the list with a
3222 prepended exclamation mark, the package name and the
3223 associated version specification are ignored completely for
3224 the purposes of defining the relationships.
3229 <example compact="compact">
3231 Build-Depends-Indep: texinfo
3232 Build-Depends: kernel-headers-2.2.10 [!hurd-i386],
3233 hurd-dev [hurd-i386], gnumach-dev [hurd-i386]
3238 Note that the binary package relationship fields such as
3239 <tt>Depends</tt> appear in one of the binary package
3240 sections of the control file, whereas the build-time
3241 relationships such as <tt>Build-Depends</tt> appear in the
3242 source package section of the control file (which is the
3248 <heading>Binary Dependencies - <tt>Depends</tt>,
3249 <tt>Recommends</tt>, <tt>Suggests</tt>, <tt>Enhances</tt>,
3250 <tt>Pre-Depends</tt>
3254 These five fields are used to declare a dependency
3255 relationship by one package on another. Except for
3256 <tt>Enhances</tt>, they appear in the depending (binary)
3257 package's control file. (<tt>Enhances</tt> appears in the
3258 recommending package's control file.)
3262 A <tt>Depends</tt> field takes effect <em>only</em> when a
3263 package is to be configured. It does not prevent a package
3264 being on the system in an unconfigured state while its
3265 dependencies are unsatisfied, and it is possible to replace
3266 a package whose dependencies are satisfied and which is
3267 properly installed with a different version whose
3268 dependencies are not and cannot be satisfied; when this is
3269 done the depending package will be left unconfigured (since
3270 attempts to configure it will give errors) and will not
3271 function properly. If it is necessary, a
3272 <tt>Pre-Depends</tt> field can be used, which has a partial
3273 effect even when a package is being unpacked, as explained
3274 in detail below. (The other three dependency fields,
3275 <tt>Recommends</tt>, <tt>Suggests</tt> and
3276 <tt>Enhances</tt>, are only used by the various front-ends
3277 to <prgn>dpkg</prgn> such as <prgn>dselect</prgn>.)
3281 For this reason packages in an installation run are usually
3282 all unpacked first and all configured later; this gives
3283 later versions of packages with dependencies on later
3284 versions of other packages the opportunity to have their
3285 dependencies satisfied.
3289 The <tt>Depends</tt> field thus allows package maintainers
3290 to impose an order in which packages should be configured.
3294 The meaning of the five dependency fields is as follows:
3296 <tag><tt>Depends</tt></tag>
3299 This declares an absolute dependency. A package will
3300 not be configured unless all of the packages listed in
3301 its <tt>Depends</tt> field have been correctly
3306 The <tt>Depends</tt> field should be used if the
3307 depended-on package is required for the depending
3308 package to provide a significant amount of
3312 The <tt>Depends</tt> field should also be used if the
3313 <prgn>postinst</prgn>, <prgn>prerm</prgn> or
3314 <prgn>postrm</prgn> scripts require the package to be
3315 present in order to run. Note, however, that the
3316 <prgn>postrm</prgn> cannot rely on any non-essential
3317 packages to be present during the <tt>purge</tt>
3321 <tag><tt>Recommends</tt></tag>
3323 <p>This declares a strong, but not absolute, dependency.
3327 The <tt>Recommends</tt> field should list packages
3328 that would be found together with this one in all but
3329 unusual installations.</p>
3332 <tag><tt>Suggests</tt></tag>
3335 This is used to declare that one package may be more
3336 useful with one or more others. Using this field
3337 tells the packaging system and the user that the
3338 listed packages are related to this one and can
3339 perhaps enhance its usefulness, but that installing
3340 this one without them is perfectly reasonable.
3344 <tag><tt>Enhances</tt></tag>
3347 This field is similar to Suggests but works in the
3348 opposite direction. It is used to declare that a
3349 package can enhance the functionality of another
3354 <tag><tt>Pre-Depends</tt></tag>
3357 This field is like <tt>Depends</tt>, except that it
3358 also forces <prgn>dpkg</prgn> to complete installation
3359 of the packages named before even starting the
3360 installation of the package which declares the
3361 pre-dependency, as follows:
3365 When a package declaring a pre-dependency is about to
3366 be <em>unpacked</em> the pre-dependency can be
3367 satisfied if the depended-on package is either fully
3368 configured, <em>or even if</em> the depended-on
3369 package(s) are only unpacked or half-configured,
3370 provided that they have been configured correctly at
3371 some point in the past (and not removed or partially
3372 removed since). In this case, both the
3373 previously-configured and currently unpacked or
3374 half-configured versions must satisfy any version
3375 clause in the <tt>Pre-Depends</tt> field.
3379 When the package declaring a pre-dependency is about
3380 to be <em>configured</em>, the pre-dependency will be
3381 treated as a normal <tt>Depends</tt>, that is, it will
3382 be considered satisfied only if the depended-on
3383 package has been correctly configured.
3387 <tt>Pre-Depends</tt> should be used sparingly,
3388 preferably only by packages whose premature upgrade or
3389 installation would hamper the ability of the system to
3390 continue with any upgrade that might be in progress.
3394 <tt>Pre-Depends</tt> are also required if the
3395 <prgn>preinst</prgn> script depends on the named
3396 package. It is best to avoid this situation if
3402 When selecting which level of dependency to use you should
3403 consider how important the depended-on package is to the
3404 functionality of the one declaring the dependency. Some
3405 packages are composed of components of varying degrees of
3406 importance. Such a package should list using
3407 <tt>Depends</tt> the package(s) which are required by the
3408 more important components. The other components'
3409 requirements may be mentioned as Suggestions or
3410 Recommendations, as appropriate to the components' relative
3415 <sect id="conflicts"><heading>Conflicting binary packages -
3416 <tt>Conflicts</tt></heading>
3419 When one binary package declares a conflict with another
3420 using a <tt>Conflicts</tt> field, <prgn>dpkg</prgn> will
3421 refuse to allow them to be installed on the system at the
3426 If one package is to be installed, the other must be removed
3427 first - if the package being installed is marked as
3428 replacing (see <ref id="replaces">) the one on the system,
3429 or the one on the system is marked as deselected, or both
3430 packages are marked <tt>Essential</tt>, then
3431 <prgn>dpkg</prgn> will automatically remove the package
3432 which is causing the conflict, otherwise it will halt the
3433 installation of the new package with an error. This
3434 mechanism is specifically designed to produce an error when
3435 the installed package is <tt>Essential</tt>, but the new
3440 A package will not cause a conflict merely because its
3441 configuration files are still installed; it must be at least
3446 A special exception is made for packages which declare a
3447 conflict with their own package name, or with a virtual
3448 package which they provide (see below): this does not
3449 prevent their installation, and allows a package to conflict
3450 with others providing a replacement for it. You use this
3451 feature when you want the package in question to be the only
3452 package providing some feature.
3456 A <tt>Conflicts</tt> entry should almost never have an
3457 "earlier than" version clause. This would prevent
3458 <prgn>dpkg</prgn> from upgrading or installing the package
3459 which declared such a conflict until the upgrade or removal
3460 of the conflicted-with package had been completed.
3464 <sect id="virtual"><heading>Virtual packages - <tt>Provides</tt>
3468 As well as the names of actual ("concrete") packages, the
3469 package relationship fields <tt>Depends</tt>,
3470 <tt>Recommends</tt>, <tt>Suggests</tt>, <tt>Enhances</tt>,
3471 <tt>Pre-Depends</tt>, <tt>Conflicts</tt>,
3472 <tt>Build-Depends</tt>, <tt>Build-Depends-Indep</tt>,
3473 <tt>Build-Conflicts</tt> and <tt>Build-Conflicts-Indep</tt>
3474 may mention "virtual packages".
3478 A <em>virtual package</em> is one which appears in the
3479 <tt>Provides</tt> control file field of another package.
3480 The effect is as if the package(s) which provide a
3481 particular virtual package name had been listed by name
3482 everywhere the virtual package name appears. (See also <ref
3483 id="virtual_pkg_sect">)
3487 If there are both concrete and virtual packages of the same
3488 name, then the dependency may be satisfied (or the conflict
3489 caused) by either the concrete package with the name in
3490 question or any other concrete package which provides the
3491 virtual package with the name in question. This is so that,
3492 for example, supposing we have
3493 <example compact="compact">
3497 and someone else releases an enhanced version of the
3498 <tt>bar</tt> package (for example, a non-US variant), they
3500 <example compact="compact">
3504 and the <tt>bar-plus</tt> package will now also satisfy the
3505 dependency for the <tt>foo</tt> package.
3509 If a dependency or a conflict has a version number attached
3510 then only real packages will be considered to see whether
3511 the relationship is satisfied (or the prohibition violated,
3512 for a conflict) - it is assumed that a real package which
3513 provides the virtual package is not of the "right" version.
3514 So, a <tt>Provides</tt> field may not contain version
3515 numbers, and the version number of the concrete package
3516 which provides a particular virtual package will not be
3517 looked at when considering a dependency on or conflict with
3518 the virtual package name.
3522 It is likely that the ability will be added in a future
3523 release of <prgn>dpkg</prgn> to specify a version number for
3524 each virtual package it provides. This feature is not yet
3525 present, however, and is expected to be used only
3530 If you want to specify which of a set of real packages
3531 should be the default to satisfy a particular dependency on
3532 a virtual package, you should list the real package as an
3533 alternative before the virtual one.
3538 <sect id="replaces"><heading>Overwriting files and replacing
3539 packages - <tt>Replaces</tt></heading>
3542 The <tt>Replaces</tt> control file field has two distinct
3543 purposes, which come into play in different situations.
3546 <sect1><heading>Overwriting files in other packages</heading>
3549 Firstly, as mentioned before, it is usually an error for a
3550 package to contain files which are on the system in
3555 However, if the overwriting package declares that it
3556 <tt>Replaces</tt> the one containing the file being
3557 overwritten, then <prgn>dpkg</prgn> will replace the file
3558 from the old package with that from the new. The file
3559 will no longer be listed as "owned" by the old package.
3563 If a package is completely replaced in this way, so that
3564 <prgn>dpkg</prgn> does not know of any files it still
3565 contains, it is considered to have "disappeared". It will
3566 be marked as not wanted on the system (selected for
3567 removal) and not installed. Any <tt>conffile</tt>s
3568 details noted for the package will be ignored, as they
3569 will have been taken over by the overwriting package. The
3570 package's <prgn>postrm</prgn> script will be run with a
3571 special argument to allow the package to do any final
3572 cleanup required. See <ref id="mscriptsinstact">.
3576 If an installed package, <tt>foo</tt> say, declares that
3577 it replaces another, <tt>bar</tt>, and an attempt is made
3578 to install <tt>bar</tt>, <prgn>dpkg</prgn> will discard
3579 files in the <tt>bar</tt> package which would overwrite
3580 those already present in <tt>foo</tt>. This is so that
3581 you can install an older version of a package without
3586 For this usage of <tt>Replaces</tt>, virtual packages (see
3587 <ref id="virtual">) are not considered when looking at a
3588 <tt>Replaces</tt> field - the packages declared as being
3589 replaced must be mentioned by their real names.
3593 Furthermore, this usage of <tt>Replaces</tt> only takes
3594 effect when both packages are at least partially on the
3595 system at once, so that it can only happen if they do not
3596 conflict or if the conflict has been overridden.
3601 <sect1><heading>Replacing whole packages, forcing their
3605 Secondly, <tt>Replaces</tt> allows the packaging system to
3606 resolve which package should be removed when there is a
3607 conflict - see <ref id="conflicts">. This usage only
3608 takes effect when the two packages <em>do</em> conflict,
3609 so that the two usages of this field do not interfere with
3614 In this situation, the package declared as being replaced
3615 can be a virtual package, so for example, all mail
3616 transport agents (MTAs) would have the following fields in
3617 their control files:
3618 <example compact="compact">
3619 Provides: mail-transport-agent
3620 Conflicts: mail-transport-agent
3621 Replaces: mail-transport-agent
3623 ensuring that only one MTA can be installed at any one
3628 <sect><heading>Relationships between source and binary packages -
3629 <tt>Build-Depends</tt>, <tt>Build-Depends-Indep</tt>,
3630 <tt>Build-Conflicts</tt>, <tt>Build-Conflicts-Indep</tt>
3634 A source package may declare a dependency or a conflict on a
3635 binary package, indicating which packages are required to be
3636 present on the system in order to build the binary packages
3637 from the source package. This is done with the control file
3638 fields <tt>Build-Depends</tt>, <tt>Build-Depends-Indep</tt>,
3639 <tt>Build-Conflicts</tt> and <tt>Build-Conflicts-Indep</tt>.
3640 The dependencies and conflicts they define must be satisfied
3641 (as defined earlier for binary packages) in order to invoke
3642 the targets in <tt>debian/rules</tt>, as follows:<footnote>
3644 If you make "build-arch" or "binary-arch", you need
3645 Build-Depends. If you make "build-indep" or
3646 "binary-indep", you need Build-Depends and
3647 Build-Depends-Indep. If you make "build" or "binary",
3651 There is no Build-Depends-Arch; the autobuilders will
3652 only need the Build-Depends if they know how to build
3653 only build-arch and binary-arch. Anyone building the
3654 build-indep/binary-indep targets is basically assumed to
3655 be building the whole package and so installs all build
3659 The purpose of the original split, I recall, was so that
3660 the autobuilders wouldn't need to install extra packages
3661 needed only for the binary-indep targets. But without a
3662 build-arch/build-indep split, this didn't work, since
3663 most of the work is done in the build target, not in the
3669 <tag><tt>Build-Depends</tt>, <tt>Build-Conflicts</tt></tag>
3672 The <tt>Build-Depends</tt> and
3673 <tt>Build-Conflicts</tt> fields must be satisfied when
3674 any of the following targets is invoked:
3675 <tt>build</tt>, <tt>clean</tt>, <tt>binary</tt>,
3676 <tt>binary-arch</tt>, <tt>build-arch</tt>,
3677 <tt>build-indep</tt> and <tt>binary-indep</tt>.
3680 <tag><tt>Build-Depends-Indep</tt>,
3681 <tt>Build-Conflicts-Indep</tt></tag>
3684 The <tt>Build-Depends-Indep</tt> and
3685 <tt>Build-Conflicts-Indep</tt> fields must be
3686 satisfied when any of the following targets is
3687 invoked: <tt>build</tt>, <tt>clean</tt>,
3688 <tt>build-indep</tt>, <tt>binary</tt> and
3689 <tt>binary-indep</tt>.
3700 <chapt id="conffiles"><heading>Configuration file handling
3704 This chapter has been superseded by <ref id="config-files">.
3708 <chapt id="sharedlibs"><heading>Shared libraries</heading>
3711 Packages containing shared libraries must be constructed with
3712 a little care to make sure that the shared library is always
3713 available. This is especially important for packages whose
3714 shared libraries are vitally important, such as the C library
3715 (currently <tt>libc6</tt>).
3719 Firstly, the package should install the shared libraries under
3720 their normal names. For example, the <tt>libgdbmg1</tt>
3721 package should install <tt>libgdbm.so.1.7.3</tt> as
3722 <file>/usr/lib/libgdbm.so.1.7.3</file>. The files should not be
3723 renamed or re-linked by any <prgn>prerm</prgn> or
3724 <prgn>postrm</prgn> scripts; <prgn>dpkg</prgn> will take care
3725 of renaming things safely without affecting running programs,
3726 and attempts to interfere with this are likely to lead to
3731 Secondly, the package should include the symbolic link that
3732 <prgn>ldconfig</prgn> would create for the shared libraries.
3733 For example, the <prgn>libgdbmg1</prgn> package should include
3734 a symbolic link from <file>/usr/lib/libgdbm.so.1</file> to
3735 <file>libgdbm.so.1.7.3</file>. This is needed so that the dynamic
3736 linker (for example <prgn>ld.so</prgn> or
3737 <prgn>ld-linux.so.*</prgn>) can find the library between the
3738 time that <prgn>dpkg</prgn> installs it and the time that
3739 <prgn>ldconfig</prgn> is run in the <prgn>postinst</prgn>
3742 The package management system requires the library to be
3743 placed before the symbolic link pointing to it in the
3744 <file>.deb</file> file. This is so that when
3745 <prgn>dpkg</prgn> comes to install the symlink
3746 (overwriting the previous symlink pointing at an older
3747 version of the library), the new shared library is already
3748 in place. In the past, this was achieved by creating the
3749 library in the temporary packaging directory before
3750 creating the symlink. Unfortunately, this was not always
3751 effective, since the building of the tar file in the
3752 <file>.deb</file> depended on the behavior of the underlying
3753 file system. Some file systems (such as reiserfs) reorder
3754 the files so that the order of creation is forgotten.
3755 Starting with release <tt>1.7.0</tt>, <prgn>dpkg</prgn>
3756 will reorder the files itself as necessary when building a
3757 package. Thus it is no longer important to concern
3758 oneself with the order of file creation.
3764 Thirdly, the associated development package should contain a
3765 symlink for the shared library without a version number. For
3766 example, the <tt>libgdbmg1-dev</tt> package should include a
3767 symlink from <tt>/usr/lib/libgdbm.so</tt> to
3768 <file>libgdbm.so.1.7.3</file>. This symlink is needed by the
3769 linker (<prgn>ld</prgn>) when compiling packages, as it will
3770 only look for <file>libgdbm.so</file> when compiling dynamically.
3774 Any package installing shared libraries in one of the default
3775 library directories of the dynamic linker (which are currently
3776 <file>/usr/lib</file> and <file>/lib</file>) or a directory that is
3777 listed in <file>/etc/ld.so.conf</file><footnote>
3780 <list compact="compact">
3781 <item><p>/usr/X11R6/lib/Xaw3d</p></item>
3782 <item><p>/usr/local/lib</p></item>
3783 <item><p>/usr/lib/libc5-compat</p></item>
3784 <item><p>/lib/libc5-compat</p></item>
3785 <item><p>/usr/X11R6/lib</p></item>
3789 must use <prgn>ldconfig</prgn> to update the shared library
3790 system. The package must call <prgn>ldconfig</prgn> in the
3791 <prgn>postinst</prgn> script if the first argument is
3792 <tt>configure</tt>; the <prgn>postinst</prgn> script may
3793 optionally invoke <prgn>ldconfig</prgn> at other times. The
3794 package should call <prgn>ldconfig</prgn> in the
3795 <prgn>postrm</prgn> script if the first argument is
3796 <tt>remove</tt>. The maintainer scripts must not invoke
3797 <prgn>ldconfig</prgn> under any circumstances other than those
3798 described in this paragraph.<footnote>
3799 <p>During install or upgrade, the preinst is called before
3800 the new files are installed, so calling "ldconfig" is
3801 pointless. The preinst of an existing package can also be
3802 called if an upgrade fails. However, this happens during
3803 the critical time when a shared libs may exist on-disk
3804 under a temporary name. Thus, it is dangerous and
3805 forbidden by current policy to call "ldconfig" at this
3808 <p>When a package is installed or upgraded, "postinst
3809 configure" runs after the new files are safely on-disk.
3810 Since it is perfectly safe to invoke ldconfig
3811 unconditionally in a postinst, it is OK for a package to
3812 simply put ldconfig in its postinst without checking the
3813 argument. The postinst can also be called to recover from
3814 a failed upgrade. This happens before any new files are
3815 unpacked, so there is no reason to call "ldconfig" at this
3818 <p>For a package that is being removed, prerm is
3819 called with all the files intact, so calling ldconfig is
3820 useless. The other calls to "prerm" happen in the case of
3821 upgrade at a time when all the files of the old package
3822 are on-disk, so again calling "ldconfig" is pointless.
3824 <p>postrm, on the other hand, is called with the "remove"
3825 argument just after the files are removed, so this is the
3826 proper time to call "ldconfig" to notify the system of the
3827 fact shared libraries from the package are removed.
3828 The postrm can be called at several other times. At the
3829 time of "postrm purge", "postrm abort-install", or "postrm
3830 abort-upgrade", calling "ldconfig" is useless because the
3831 shared lib files are not on-disk. However, when "postrm"
3832 is invoked with arguments "upgrade", "failed-upgrade", or
3833 "disappear", a shared lib may exist on-disk under a
3840 <heading>Handling shared library dependencies - the
3841 <tt>shlibs</tt> system</heading>
3844 If a package contains a binary or library which links to a
3845 shared library, we must ensure that when the package is
3846 installed on the system, all of the libraries needed are
3847 also installed. This requirement led to the creation of the
3848 <tt>shlibs</tt> system, which is very simple in its design:
3849 any package which <em>provides</em> a shared library also
3850 provides information on the package dependencies required to
3851 ensure the presence of this library, and any package which
3852 <em>uses</em> a shared library uses this information to
3853 determine the dependencies it requires. The files which
3854 contain the mapping from shared libraries to the necessary
3855 dependency information are called <file>shlibs</file> files.
3859 Thus, when a package is built which contains any shared
3860 libraries, it must provide a <file>shlibs</file> file for other
3861 packages to use, and when a package is built which contains
3862 any shared libraries or compiled binaries, it must run
3863 <prgn>dpkg-shlibdeps</prgn> on these to determine the
3864 libraries used and hence the dependencies needed by this
3867 In the past, the shared libraries linked to were
3868 determined by calling <prgn>ldd</prgn>, but now
3869 <prgn>objdump</prgn> is used to do this. The only
3870 change this makes to package building is that
3871 <prgn>dpkg-shlibdeps</prgn> must also be run on shared
3872 libraries, whereas in the past this was unnecessary.
3873 The rest of this footnote explains the advantage that
3878 We say that a binary <tt>foo</tt> <em>directly</em> uses
3879 a library <tt>libbar</tt> if it is explicitly linked
3880 with that library (that is, it uses the flag
3881 <tt>-lbar</tt> during the linking stage). Other
3882 libraries that are needed by <tt>libbar</tt> are linked
3883 <em>indirectly</em> to <tt>foo</tt>, and the dynamic
3884 linker will load them automatically when it loads
3885 <tt>libbar</tt>. A package should depend on
3886 the libraries it directly uses, and the dependencies for
3887 those libraries should automatically pull in the other
3892 Unfortunately, the <prgn>ldd</prgn> program shows both
3893 the directly and indirectly used libraries, meaning that
3894 the dependencies determined included both direct and
3895 indirect dependencies. The use of <prgn>objdump</prgn>
3896 avoids this problem by determining only the directly
3901 A good example of where this helps is the following. We
3902 could update <tt>libimlib</tt> with a new version that
3903 supports a new graphics format called dgf (but retaining
3904 the same major version number). If we used the old
3905 <prgn>ldd</prgn> method, every package that uses
3906 <tt>libimlib</tt> would need to be recompiled so it
3907 would also depend on <tt>libdgf</tt> or it wouldn't run
3908 due to missing symbols. However with the new system,
3909 packages using <tt>libimlib</tt> can rely on
3910 <tt>libimlib</tt> itself having the dependency on
3911 <tt>libdgf</tt> and so they would not need rebuilding.
3917 In the following sections, we will first describe where the
3918 various <tt>shlibs</tt> files are to be found, then how to
3919 use <prgn>dpkg-shlibdeps</prgn>, and finally the
3920 <tt>shlibs</tt> file format and how to create them if your
3921 package contains a shared library.
3925 <sect><heading>The <tt>shlibs</tt> files present on the system
3929 There are several places where <tt>shlibs</tt> files are
3930 found. The following list gives them in the order in which
3931 they are read by <prgn>dpkg-shlibdeps</prgn>. (The first
3932 one which gives the required information is used.)
3938 <p><file>debian/shlibs.local</file></p>
3940 This lists overrides for this package. Its use is
3941 described below (see <ref id="shlibslocal">).
3946 <p><file>/etc/dpkg/shlibs.override</file></p>
3948 This lists global overrides. This list is normally
3949 empty. It is maintained by the local system
3955 <p><file>DEBIAN/shlibs</file> files in the "build directory"</p>
3957 When packages are being built, any
3958 <file>debian/shlibs</file> files are copied into the
3959 control file area of the temporary build directory and
3960 given the name <file>shlibs</file>. These files give
3961 details of any shared libraries included in the
3964 An example may help here. Let us say that the
3965 source package <tt>foo</tt> generates two binary
3966 packages, <tt>libfoo2</tt> and
3967 <tt>foo-runtime</tt>. When building the binary
3968 packages, the two packages are created in the
3969 directories <file>debian/libfoo2</file> and
3970 <file>debian/foo-runtime</file> respectively.
3971 (<file>debian/tmp</file> could be used instead of one
3972 of these.) Since <tt>libfoo2</tt> provides the
3973 <tt>libfoo</tt> shared library, it will require a
3974 <tt>shlibs</tt> file, which will be installed in
3975 <file>debian/libfoo2/DEBIAN/shlibs</file>, eventually
3977 <file>/var/lib/dpkg/info/libfoo2.shlibs</file>. Then
3978 when <prgn>dpkg-shlibdeps</prgn> is run on the
3980 <file>debian/foo-runtime/usr/bin/foo-prog</file>, it
3982 <file>debian/libfoo2/DEBIAN/shlibs</file> file to
3983 determine whether <tt>foo-prog</tt>'s library
3984 dependencies are satisfied by any of the libraries
3985 provided by <tt>libfoo2</tt>. For this reason,
3986 <prgn>dpkg-shlibdeps</prgn> must only be run once
3987 all of the individual binary packages'
3988 <tt>shlibs</tt> files have been installed into the
3996 <p><file>/var/lib/dpkg/info/*.shlibs</file></p>
3998 These are the <file>shlibs</file> files corresponding to
3999 all of the packages installed on the system, and are
4000 maintained by the relevant package maintainers.
4005 <p><file>/etc/dpkg/shlibs.default</file></p>
4007 This file lists any shared libraries whose packages
4008 have failed to provide correct <file>shlibs</file> files.
4009 It was used when the <file>shlibs</file> setup was first
4010 introduced, but it is now normally empty. It is
4011 maintained by the <tt>dpkg</tt> maintainer.
4019 <heading>How to use <prgn>dpkg-shlibdeps</prgn> and the
4020 <file>shlibs</file> files</heading>
4023 Put a call to <prgn>dpkg-shlibdeps</prgn> into your
4024 <file>debian/rules</file> file. If your package contains only
4025 compiled binaries and libraries (but no scripts), you can
4026 use a command such as:
4027 <example compact="compact">
4028 dpkg-shlibdeps debian/tmp/usr/bin/* debian/tmp/usr/sbin/* \
4029 debian/tmp/usr/lib/*
4031 Otherwise, you will need to explicitly list the compiled
4032 binaries and libraries.<footnote>
4034 If you are using <tt>debhelper</tt>, the
4035 <prgn>dh_shlibdeps</prgn> program will do this work for
4036 you. It will also correctly handle multi-binary
4043 This command puts the dependency information into the
4044 <file>debian/substvars</file> file, which is then used by
4045 <prgn>dpkg-gencontrol</prgn>. You will need to place a
4046 <tt>${shlib:Depends}</tt> variable in the <tt>Depends</tt>
4047 field in the control file for this to work.
4051 If <prgn>dpkg-shlibdeps</prgn> doesn't complain, you're
4052 done. If it does complain you might need to create your own
4053 <file>debian/shlibs.local</file> file, as explained below (see
4054 <ref id="shlibslocal">).
4058 If you have multiple binary packages, you will need to call
4059 <prgn>dpkg-shlibdeps</prgn> on each one which contains
4060 compiled libraries or binaries. In such a case, you will
4061 need to use the <tt>-T</tt> option to the <tt>dpkg</tt>
4062 utilities to specify a different <file>substvars</file> file.
4063 For more details on this and other options, see <manref
4064 name="dpkg-shlibdeps" section="1">.
4068 <sect id="shlibs"><heading>The <file>shlibs</file> File Format
4072 Each <file>shlibs</file> file has the same format. Lines
4073 beginning with <tt>#</tt> are considered to be comments and
4074 are ignored. Each line is of the form:
4075 <example compact="compact">
4076 <var>library-name</var> <var>soname-version-number</var> <var>dependencies ...</var>
4081 We will explain this by reference to the example of the
4082 <tt>zlib1g</tt> package, which (at the time of writing)
4083 installs the shared library <file>/usr/lib/libz.so.1.1.3</file>.
4087 <var>library-name</var> is the name of the shared library,
4088 in this case <tt>libz</tt>. (This must match the name part
4089 of the soname, see below.)
4093 <var>soname-version-number</var> is the version part of the
4094 soname of the library. The soname is the thing that must
4095 exactly match for the library to be recognized by the
4096 dynamic linker, and is usually of the form
4097 <tt><var>name</var>.so.<var>major-version</var></tt>, in our
4098 example, <tt>libz.so.1</tt>.<footnote>
4100 This can be determined using the command
4101 <example compact="compact">
4102 objdump -p /usr/lib/libz.so.1.1.3 | grep SONAME
4106 The version part is the part which comes after
4107 <tt>.so.</tt>, so in our case, it is <tt>1</tt>.
4111 <var>dependencies</var> has the same syntax as a dependency
4112 field in a binary package control file. It should give
4113 details of which packages are required to satisfy a binary
4114 built against the version of the library contained in the
4115 package. See <ref id="depsyntax"> for details.
4119 In our example, if the first version of the <tt>zlib1g</tt>
4120 package which contained a minor number of at least
4121 <tt>1.3</tt> was <var>1:1.1.3-1</var>, then the
4122 <tt>shlibs</tt> entry for this library could say:
4123 <example compact="compact">
4124 libz 1 zlib1g (>= 1:1.1.3)
4126 The version-specific dependency is to avoid warnings from
4127 the dynamic linker about using older shared libraries with
4133 <heading>Providing a <file>shlibs</file> file</heading>
4136 If your package provides a shared library, you should create
4137 a <file>shlibs</file> file following the format described above.
4138 It is usual to call this file <file>debian/shlibs</file> (but if
4139 you have multiple binary packages, you might want to call it
4140 <file>debian/shlibs.<var>package</var></file> instead). Then
4141 let <file>debian/rules</file> install it in the control area:
4142 <example compact="compact">
4143 install -m644 debian/shlibs debian/tmp/DEBIAN
4145 or, in the case of a multi-binary package:
4146 <example compact="compact">
4147 install -m644 debian/shlibs.<var>package</var> debian/<var>package</var>/DEBIAN/shlibs
4149 An alternative way of doing this is to create the
4150 <file>shlibs</file> file in the control area directly from
4151 <file>debian/rules</file> without using a <file>debian/shlibs</file>
4152 file at all,<footnote>
4154 This is what <prgn>dh_makeshlibs</prgn> in the
4155 <tt>debhelper</tt> suite does.
4158 since the <file>debian/shlibs</file> file itself is ignored by
4159 <prgn>dpkg-shlibdeps</prgn>.
4163 As <prgn>dpkg-shlibdeps</prgn> reads the
4164 <file>DEBIAN/shlibs</file> files in all of the binary packages
4165 being built from this source package, all of the
4166 <file>DEBIAN/shlibs</file> files should be installed before
4167 <prgn>dpkg-shlibdeps</prgn> is called on any of the binary
4172 <sect id="shlibslocal">
4173 <heading>Writing the <file>debian/shlibs.local</file> file</heading>
4176 This file is intended only as a <em>temporary</em> fix if
4177 your binaries or libraries depend on a library whose package
4178 does not yet provide a correct <file>shlibs</file> file.
4182 We will assume that you are trying to package a binary
4183 <tt>foo</tt>. When you try running
4184 <prgn>dpkg-shlibdeps</prgn> you get the following error
4185 message (<tt>-O</tt> displays the dependency information on
4186 <tt>stdout</tt> instead of writing it to
4187 <tt>debian/substvars</tt>, and the lines have been wrapped
4188 for ease of reading):
4189 <example compact="compact">
4190 $ dpkg-shlibdeps -O debian/tmp/usr/bin/foo
4191 dpkg-shlibdeps: warning: unable to find dependency
4192 information for shared library libbar (soname 1,
4193 path /usr/lib/libbar.so.1, dependency field Depends)
4194 shlibs:Depends=libc6 (>= 2.2.2-2)
4196 You can then run <prgn>ldd</prgn> on the binary to find the
4197 full location of the library concerned:
4198 <example compact="compact">
4200 libbar.so.1 => /usr/lib/libbar.so.1 (0x4001e000)
4201 libc.so.6 => /lib/libc.so.6 (0x40032000)
4202 /lib/ld-linux.so.2 => /lib/ld-linux.so.2 (0x40000000)
4204 So the <prgn>foo</prgn> binary depends on the
4205 <prgn>libbar</prgn> shared library, but no package seems to
4206 provide a <file>*.shlibs</file> file handling
4207 <file>libbar.so.1</file> in <file>/var/lib/dpkg/info/</file>. Let's
4208 determine the package responsible:
4209 <example compact="compact">
4210 $ dpkg -S /usr/lib/libbar.so.1
4211 bar1: /usr/lib/libbar.so.1
4212 $ dpkg -s bar1 | grep Version
4215 This tells us that the <tt>bar1</tt> package, version 1.0-1,
4216 is the one we are using. Now we can file a bug against the
4217 <tt>bar1</tt> package and create our own
4218 <file>debian/shlibs.local</file> to locally fix the problem.
4219 Including the following line into your
4220 <file>debian/shlibs.local</file> file:
4221 <example compact="compact">
4222 libbar 1 bar1 (>= 1.0-1)
4224 should allow the package build to work.
4228 As soon as the maintainer of <tt>bar1</tt> provides a
4229 correct <file>shlibs</file> file, you should remove this line
4230 from your <file>debian/shlibs.local</file> file. (You should
4231 probably also then have a versioned <tt>Build-Depends</tt>
4232 on <tt>bar1</tt> to help ensure that others do not have the
4233 same problem building your package.)
4238 <chapt id="opersys"><heading>The Operating System</heading>
4241 <heading>Filesystem hierarchy</heading>
4245 <heading>Filesystem Structure</heading>
4248 The location of all installed files and directories must
4249 comply with the Filesystem Hierarchy Standard (FHS),
4250 version 2.1, except where doing so would violate other
4251 terms of Debian Policy. The version of this document
4252 referred here can be found in the <tt>debian-policy</tt>
4254 <url id="http://www.debian.org/doc/packaging-manuals/fhs/"
4255 name="FHS (Debian copy)"> alongside this manual (or, if
4256 you have the <package>debian-policy</package> installed,
4258 id="file:///usr/share/doc/debian-policy/fhs/" name="FHS
4259 (local copy)">). The
4260 latest version, which may be a more recent version, may
4262 <url id="http://www.pathname.com/fhs/" name="FHS (upstream)">.
4263 Specific questions about following the standard may be
4264 asked on the <tt>debian-devel</tt> mailing list, or
4265 referred to the FHS mailing list (see the
4266 <url id="http://www.pathname.com/fhs/" name="FHS web site"> for
4272 <heading>Site-specific programs</heading>
4275 As mandated by the FHS, packages must not place any
4276 files in <file>/usr/local</file>, either by putting them in
4277 the file system archive to be unpacked by <prgn>dpkg</prgn>
4278 or by manipulating them in their maintainer scripts.
4282 However, the package may create empty directories below
4283 <file>/usr/local</file> so that the system administrator knows
4284 where to place site-specific files. These directories
4285 should be removed on package removal if they are
4290 Note, that this applies only to directories <em>below</em>
4291 <file>/usr/local</file>, not <em>in</em> <file>/usr/local</file>.
4292 Packages must not create sub-directories in the directory
4293 <file>/usr/local</file> itself, except those listed in FHS,
4294 section 4.5. However, you may create directories below
4295 them as you wish. You must not remove any of the
4296 directories listed in 4.5, even if you created them.
4300 Since <file>/usr/local</file> can be mounted read-only from a
4301 remote server, these directories must be created and
4302 removed by the <prgn>postinst</prgn> and <prgn>prerm</prgn>
4303 maintainer scripts and not be included in the
4304 <file>.deb</file> archive. These scripts must not fail if
4305 either of these operations fail.
4309 For example, the <tt>emacsen-common</tt> package could
4310 contain something like
4311 <example compact="compact">
4312 if [ ! -e /usr/local/share/emacs ]
4314 if mkdir /usr/local/share/emacs 2>/dev/null
4316 chown root:staff /usr/local/share/emacs
4317 chmod 2775 /usr/local/share/emacs
4321 in its <prgn>postinst</prgn> script, and
4322 <example compact="compact">
4323 rmdir /usr/local/share/emacs/site-lisp 2>/dev/null || true
4324 rmdir /usr/local/share/emacs 2>/dev/null || true
4326 in the <prgn>prerm</prgn> script. (Note that this form is
4327 used to ensure that if the script is interrupted, the
4328 directory <file>/usr/local/share/emacs</file> will still be
4333 If you do create a directory in <file>/usr/local</file> for
4334 local additions to a package, you should ensure that
4335 settings in <file>/usr/local</file> take precedence over the
4336 equivalents in <file>/usr</file>.
4340 However, because <file>/usr/local</file> and its contents are
4341 for exclusive use of the local administrator, a package
4342 must not rely on the presence or absence of files or
4343 directories in <file>/usr/local</file> for normal operation.
4347 The <file>/usr/local</file> directory itself and all the
4348 subdirectories created by the package should (by default) have
4349 permissions 2775 (group-writable and set-group-id) and be
4350 owned by <tt>root.staff</tt>.
4355 <heading>The system-wide mail directory</heading>
4357 The system-wide mail directory is <file>/var/mail</file>. This
4358 directory is part of the base system and should not owned
4359 by any particular mail agents. The use of the old
4360 location <file>/var/spool/mail</file> is deprecated, even
4361 though the spool may still be physically located there.
4362 To maintain partial upgrade compatibility for systems
4363 which have <file>/var/spool/mail</file> as their physical mail
4364 spool, packages using <file>/var/mail</file> must depend on
4365 either <package>libc6</package> (>= 2.1.3-13), or on
4366 <package>base-files</package> (>= 2.2.0), or on later
4367 versions of either one of these packages.
4373 <heading>Users and groups</heading>
4376 <heading>Introduction</heading>
4378 The Debian system can be configured to use either plain or
4383 Some user ids (UIDs) and group ids (GIDs) are reserved
4384 globally for use by certain packages. Because some
4385 packages need to include files which are owned by these
4386 users or groups, or need the ids compiled into binaries,
4387 these ids must be used on any Debian system only for the
4388 purpose for which they are allocated. This is a serious
4389 restriction, and we should avoid getting in the way of
4390 local administration policies. In particular, many sites
4391 allocate users and/or local system groups starting at 100.
4395 Apart from this we should have dynamically allocated ids,
4396 which should by default be arranged in some sensible
4397 order, but the behavior should be configurable.
4401 Packages other than <tt>base-passwd</tt> must not modify
4402 <file>/etc/passwd</file>, <file>/etc/shadow</file>,
4403 <file>/etc/group</file> or <file>/etc/gshadow</file>.
4408 <heading>UID and GID classes</heading>
4410 The UID and GID numbers are divided into classes as
4416 Globally allocated by the Debian project, the same
4417 on every Debian system. These ids will appear in
4418 the <file>passwd</file> and <file>group</file> files of all
4419 Debian systems, new ids in this range being added
4420 automatically as the <tt>base-passwd</tt> package is
4425 Packages which need a single statically allocated
4426 uid or gid should use one of these; their
4427 maintainers should ask the <tt>base-passwd</tt>
4435 Dynamically allocated system users and groups.
4436 Packages which need a user or group, but can have
4437 this user or group allocated dynamically and
4438 differently on each system, should use <tt>adduser
4439 --system</tt> to create the group and/or user.
4440 <prgn>adduser</prgn> will check for the existence of
4441 the user or group, and if necessary choose an unused
4442 id based on the ranges specified in
4443 <file>adduser.conf</file>.
4447 <tag>1000-29999:</tag>
4450 Dynamically allocated user accounts. By default
4451 <prgn>adduser</prgn> will choose UIDs and GIDs for
4452 user accounts in this range, though
4453 <file>adduser.conf</file> may be used to modify this
4458 <tag>30000-59999:</tag>
4463 <tag>60000-64999:</tag>
4466 Globally allocated by the Debian project, but only
4467 created on demand. The ids are allocated centrally
4468 and statically, but the actual accounts are only
4469 created on users' systems on demand.
4473 These ids are for packages which are obscure or
4474 which require many statically-allocated ids. These
4475 packages should check for and create the accounts in
4476 <file>/etc/passwd</file> or <file>/etc/group</file> (using
4477 <prgn>adduser</prgn> if it has this facility) if
4478 necessary. Packages which are likely to require
4479 further allocations should have a "hole" left after
4480 them in the allocation, to give them room to
4485 <tag>65000-65533:</tag>
4493 User <tt>nobody</tt>. The corresponding gid refers
4494 to the group <tt>nogroup</tt>.
4501 <tt>(uid_t)(-1) == (gid_t)(-1)</tt> <em>must
4502 not</em> be used, because it is the error return
4511 <sect id="sysvinit">
4512 <heading>System run levels and <file>init.d</file> scripts</heading>
4514 <sect1 id="/etc/init.d">
4515 <heading>Introduction</heading>
4518 The <file>/etc/init.d</file> directory contains the scripts
4519 executed by <prgn>init</prgn> at boot time and when the
4520 init state (or "runlevel") is changed (see <manref
4521 name="init" section="8">).
4525 There are at least two different, yet functionally
4526 equivalent, ways of handling these scripts. For the sake
4527 of simplicity, this document describes only the symbolic
4528 link method. However, it must not be assumed by maintainer
4529 scripts that this method is being used, and any automated
4530 manipulation of the various runlevel behaviours by
4531 maintainer scripts must be performed using
4532 <prgn>update-rc.d</prgn> as described below and not by
4533 manually installing or removing symlinks. For information
4534 on the implementation details of the other method,
4535 implemented in the <tt>file-rc</tt> package, please refer
4536 to the documentation of that package.
4540 These scripts are referenced by symbolic links in the
4541 <file>/etc/rc<var>n</var>.d</file> directories. When changing
4542 runlevels, <prgn>init</prgn> looks in the directory
4543 <file>/etc/rc<var>n</var>.d</file> for the scripts it should
4544 execute, where <tt><var>n</var></tt> is the runlevel that
4545 is being changed to, or <tt>S</tt> for the boot-up
4550 The names of the links all have the form
4551 <file>S<var>mm</var><var>script</var></file> or
4552 <file>K<var>mm</var><var>script</var></file> where
4553 <var>mm</var> is a two-digit number and <var>script</var>
4554 is the name of the script (this should be the same as the
4555 name of the actual script in <file>/etc/init.d</file>).
4559 When <prgn>init</prgn> changes runlevel first the targets
4560 of the links whose names start with a <tt>K</tt> are
4561 executed, each with the single argument <tt>stop</tt>,
4562 followed by the scripts prefixed with an <tt>S</tt>, each
4563 with the single argument <tt>start</tt>. (The links are
4564 those in the <file>/etc/rc<var>n</var>.d</file> directory
4565 corresponding to the new runlevel.) The <tt>K</tt> links
4566 are responsible for killing services and the <tt>S</tt>
4567 link for starting services upon entering the runlevel.
4571 For example, if we are changing from runlevel 2 to
4572 runlevel 3, init will first execute all of the <tt>K</tt>
4573 prefixed scripts it finds in <file>/etc/rc3.d</file>, and then
4574 all of the <tt>S</tt> prefixed scripts in that directory.
4575 The links starting with <tt>K</tt> will cause the
4576 referred-to file to be executed with an argument of
4577 <tt>stop</tt>, and the <tt>S</tt> links with an argument
4582 The two-digit number <var>mm</var> is used to determine
4583 the order in which to run the scripts: low-numbered links
4584 have their scripts run first. For example, the
4585 <tt>K20</tt> scripts will be executed before the
4586 <tt>K30</tt> scripts. This is used when a certain service
4587 must be started before another. For example, the name
4588 server <prgn>bind</prgn> might need to be started before
4589 the news server <prgn>inn</prgn> so that <prgn>inn</prgn>
4590 can set up its access lists. In this case, the script
4591 that starts <prgn>bind</prgn> would have a lower number
4592 than the script that starts <prgn>inn</prgn> so that it
4594 <example compact="compact">
4601 The two runlevels 0 (halt) and 6 (reboot) are slightly
4602 different. In these runlevels, the links with an
4603 <tt>S</tt> prefix are still called after those with a
4604 <tt>K</tt> prefix, but they too are called with the single
4605 argument <tt>stop</tt>.
4609 Also, if the script name ends <tt>.sh</tt>, the script
4610 will be sourced in runlevel <tt>S</tt> rather that being
4611 run in a forked subprocess, but will be explicitly run by
4612 <prgn>sh</prgn> in all other runlevels.
4617 <heading>Writing the scripts</heading>
4620 Packages that include daemons for system services should
4621 place scripts in <file>/etc/init.d</file> to start or stop
4622 services at boot time or during a change of runlevel.
4623 These scripts should be named
4624 <file>/etc/init.d/<var>package</var></file>, and they should
4625 accept one argument, saying what to do:
4628 <tag><tt>start</tt></tag>
4629 <item><p>start the service,</p></item>
4631 <tag><tt>stop</tt></tag>
4632 <item><p>stop the service,</p></item>
4634 <tag><tt>restart</tt></tag>
4635 <item><p>stop and restart the service,</p></item>
4637 <tag><tt>reload</tt></tag>
4638 <item><p>cause the configuration of the service to be
4639 reloaded without actually stopping and restarting
4640 the service,</p></item>
4642 <tag><tt>force-reload</tt></tag>
4643 <item><p>cause the configuration to be reloaded if the
4644 service supports this, otherwise restart the
4648 The <tt>start</tt>, <tt>stop</tt>, <tt>restart</tt>, and
4649 <tt>force-reload</tt> options should be supported by all
4650 scripts in <file>/etc/init.d</file>, the <tt>reload</tt>
4651 option is optional.</p>
4654 The <file>init.d</file> scripts should ensure that they will
4655 behave sensibly if invoked with <tt>start</tt> when the
4656 service is already running, or with <tt>stop</tt> when it
4657 isn't, and that they don't kill unfortunately-named user
4658 processes. The best way to achieve this is usually to use
4659 <prgn>start-stop-daemon</prgn>.</p>
4662 If a service reloads its configuration automatically (as
4663 in the case of <prgn>cron</prgn>, for example), the
4664 <tt>reload</tt> option of the <file>init.d</file> script
4665 should behave as if the configuration has been reloaded
4669 The <file>/etc/init.d</file> scripts must be treated as
4670 configuration files, either (if they are present in the
4671 package, that is, in the .deb file) by marking them as
4672 <tt>conffile</tt>s, or, (if they do not exist in the .deb)
4673 by managing them correctly in the maintainer scripts (see
4674 <ref id="config-files">). This is important since we want
4675 to give the local system administrator the chance to adapt
4676 the scripts to the local system, e.g., to disable a
4677 service without de-installing the package, or to specify
4678 some special command line options when starting a service,
4679 while making sure her changes aren't lost during the next
4684 These scripts should not fail obscurely when the
4685 configuration files remain but the package has been
4686 removed, as configuration files remain on the system after
4687 the package has been removed. Only when <prgn>dpkg</prgn>
4688 is executed with the <tt>--purge</tt> option will
4689 configuration files be removed. In particular, as the
4690 <file>/etc/init.d/<var>package</var></file> script itself is
4691 usually a <tt>conffile</tt>, it will remain on the system
4692 if the package is removed but not purged. Therefore, you
4693 should include a <tt>test</tt> statement at the top of the
4695 <example compact="compact">
4696 test -f <var>program-executed-later-in-script</var> || exit 0
4701 Often there are some variables in the <file>init.d</file>
4702 scripts whose values control the behaviour of the scripts,
4703 and which a system administrator is likely to want to
4704 change. As the scripts themselves are frequently
4705 <tt>conffile</tt>s, modifying them requires that the
4706 administrator merge in their changes each time the package
4707 is upgraded and the <tt>conffile</tt> changes. To ease
4708 the burden on the system administrator, such configurable
4709 values should not be placed directly in the script.
4710 Instead, they should be placed in a file in
4711 <file>/etc/default</file>, which typically will have the same
4712 base name as the <file>init.d</file> script. This extra file
4713 should be sourced by the script when the script runs. It
4714 must contain only variable settings and comments in POSIX
4715 <prgn>sh</prgn> format. It may either be a
4716 <tt>conffile</tt> or a configuration file maintained by
4717 the package maintainer scripts. See <ref id="config-files">
4722 To ensure that vital configurable values are always
4723 available, the <file>init.d</file> script should set default
4724 values for each of the shell variables it uses, either
4725 before sourcing the <file>/etc/default/</file> file or
4726 afterwards using something like the <tt>:
4727 ${VAR:=default}</tt> syntax. Also, the <file>init.d</file>
4728 script must behave sensibly and not fail if the
4729 <file>/etc/default</file> file is deleted.
4734 <heading>Interfacing with the initscript system</heading>
4737 Maintainers should use the abstraction layer provided by
4738 the <prgn>update-rc.d</prgn> and <prgn>invoke-rc.d</prgn>
4739 programs to deal with initscripts in their packages'
4740 scripts such as <prgn>postinst</prgn>, <prgn>prerm</prgn>
4741 and <prgn>postrm</prgn>.
4744 Directly managing the /etc/rc?.d links and directly
4745 invoking the <file>/etc/init.d/</file> initscripts should
4746 be done only by packages providing the initscript
4747 subsystem (such as <prgn>sysvinit</prgn> and
4748 <prgn>file-rc</prgn>).
4753 <heading>Managing the links</heading>
4756 The program <prgn>update-rc.d</prgn> is provided for
4757 package maintainers to arrange for the proper creation and
4758 removal of <file>/etc/rc<var>n</var>.d</file> symbolic links,
4759 or their functional equivalent if another method is being
4760 used. This may be used by maintainers in their packages'
4761 <prgn>postinst</prgn> and <prgn>postrm</prgn> scripts.</p>
4764 You must not include any <file>/etc/rc<var>n</var>.d</file>
4765 symbolic links in the actual archive or manually create or
4766 remove the symbolic links in maintainer scripts; you must
4767 use the <prgn>update-rc.d</prgn> program instead. (The
4768 former will fail if an alternative method of maintaining
4769 runlevel information is being used.) You must not include
4770 the <file>/etc/rc<var>n</var>.d</file> directories themselves
4771 in the archive either. (Only the <tt>sysvinit</tt>
4776 By default <prgn>update-rc.d</prgn> will start services in
4777 each of the multi-user state runlevels (2, 3, 4, and 5)
4778 and stop them in the halt runlevel (0), the single-user
4779 runlevel (1) and the reboot runlevel (6). The system
4780 administrator will have the opportunity to customize
4781 runlevels by simply adding, moving, or removing the
4782 symbolic links in <file>/etc/rc<var>n</var>.d</file> if
4783 symbolic links are being used, or by modifying
4784 <file>/etc/runlevel.conf</file> if the <tt>file-rc</tt> method
4789 To get the default behavior for your package, put in your
4790 <prgn>postinst</prgn> script
4791 <example compact="compact">
4792 update-rc.d <var>package</var> defaults
4794 and in your <prgn>postrm</prgn>
4795 <example compact="compact">
4796 if [ "$1" = purge ]; then
4797 update-rc.d <var>package</var> remove
4799 </example>. Note that if your package changes runlevels
4800 or priority, you may have to remove and recreate the links,
4801 since otherwise the old links may persist. Refer to the
4802 documentation of <prgn>update-rc.d</prgn></p>
4805 This will use a default sequence number of 20. If it does
4806 not matter when or in which order the <file>init.d</file>
4807 script is run, use this default. If it does, then you
4808 should talk to the maintainer of the <prgn>sysvinit</prgn>
4809 package or post to <tt>debian-devel</tt>, and they will
4810 help you choose a number.
4814 For more information about using <tt>update-rc.d</tt>,
4815 please consult its manpage <manref name="update-rc.d"
4821 <heading>Running initscripts</heading>
4823 The program <prgn>invoke-rc.d</prgn> is provided to make
4824 it easier for package maintainers to properly invoke an
4825 initscript, obeying runlevel and other locally-defined
4826 constraints that might limit a package's right to start,
4827 stop and otherwise manage services. This program may be
4828 used by maintainers in their packages' scripts.
4831 The use of <prgn>invoke-rc.d</prgn> to invoke the
4832 <file>/etc/init.d/*</file> initscripts is strongly
4833 recommended<footnote>
4835 In the future, the use of invoke-rc.d to invoke
4836 initscripts shall be made mandatory. Maintainers are
4837 advised to switch to invoke-rc.d as soon as
4839 </footnote>, instead of calling them directly.
4843 By default, <prgn>invoke-rc.d</prgn> will pass any
4844 action requests (start, stop, reload, restart...) to the
4845 <file>/etc/init.d</file> script, filtering out requests
4846 to start or restart a service out of its intended
4850 Most packages will simply need to change:
4851 <example compact="compact">/etc/init.d/<package>
4852 <action></example> in their <prgn>postinst</prgn>
4853 and <prgn>prerm</prgn> scripts to:
4854 <example compact="compact">
4855 if [ -x /usr/sbin/invoke-rc.d ] ; then
4856 invoke-rc.d <var>package</var> <action>
4858 /etc/init.d/<var>package</var> <action>
4862 A package should register its initscript services using
4863 <prgn>update-rc.d</prgn> before it tries to invoke them
4864 using <prgn>invoke-rc.d</prgn>. Invocation of
4865 unregistered services may fail.
4868 For more information about using
4869 <prgn>invoke-rc.d</prgn>, please consult its manpage
4870 <manref name="invoke-rc.d" section="8">.
4877 <heading>Boot-time initialization</heading>
4880 There used to be another directory, <file>/etc/rc.boot</file>,
4881 which contained scripts which were run once per machine
4882 boot. This has been deprecated in favour of links from
4883 <file>/etc/rcS.d</file> to files in <file>/etc/init.d</file> as
4884 described in <ref id="/etc/init.d">. Packages must not
4885 place files in <file>/etc/rc.boot</file>.</p>
4888 <heading>Example</heading>
4891 The <prgn>bind</prgn> DNS (nameserver) package wants to
4892 make sure that the nameserver is running in multiuser
4893 runlevels, and is properly shut down with the system. It
4894 puts a script in <file>/etc/init.d</file>, naming the script
4895 appropriately <tt>bind</tt>. As you can see, the script
4896 interprets the argument <tt>reload</tt> to send the
4897 nameserver a <tt>HUP</tt> signal (causing it to reload its
4898 configuration); this way the system administrator can say
4899 <tt>/etc/init.d/bind reload</tt> to reload the name
4900 server. The script has one configurable value, which can
4901 be used to pass parameters to the named program at
4902 startup; this value is read from
4903 <file>/etc/default/bind</file> (see below).
4907 <example compact="compact">
4910 # Original version by Robert Leslie
4911 # <rob@mars.org>, edited by iwj and cs
4913 test -x /usr/sbin/named || exit 0
4915 # Source defaults file.
4917 if [ -f /etc/default/bind ]; then
4924 echo -n "Starting domain name service: named"
4925 start-stop-daemon --start --quiet --exec /usr/sbin/named \
4930 echo -n "Stopping domain name service: named"
4931 start-stop-daemon --stop --quiet \
4932 --pidfile /var/run/named.pid --exec /usr/sbin/named
4936 echo -n "Restarting domain name service: named"
4937 start-stop-daemon --stop --quiet \
4938 --pidfile /var/run/named.pid --exec /usr/sbin/named
4939 start-stop-daemon --start --verbose --exec /usr/sbin/named \
4943 force-reload|reload)
4944 echo -n "Reloading configuration of domain name service: named"
4945 start-stop-daemon --stop --signal 1 --quiet \
4946 --pidfile /var/run/named.pid --exec /usr/sbin/named
4950 echo "Usage: /etc/init.d/bind " \
4951 " {start|stop|restart|reload|force-reload}" >&2
4961 Complementing the above init script is a configuration
4962 file <file>/etc/default/bind</file>, which contains
4963 configurable parameters used by the script. This would be
4964 created by the <prgn>postinst</prgn> script if it was not
4965 already present, and removed on purge by the
4966 <prgn>postrm</prgn> script.
4967 <example compact="compact">
4968 # Specified parameters to pass to named. See named(8).
4969 # You may uncomment the following line, and edit to taste.
4975 Another example on which you can base your
4976 <file>/etc/init.d</file> scripts is found in
4977 <file>/etc/init.d/skeleton</file>.
4981 If this package is happy with the default setup from
4982 <prgn>update-rc.d</prgn>, namely an ordering number of 20
4983 and having named running in all runlevels, it can say in
4984 its <prgn>postinst</prgn>:
4985 <example compact="compact">
4986 update-rc.d bind defaults >/dev/null
4988 And in its <prgn>postrm</prgn>, to remove the links when the
4990 <example compact="compact">
4991 if [ "$1" = purge ]; then
4992 update-rc.d bind remove >/dev/null
5000 <heading>Console messages from <file>init.d</file> scripts</heading>
5003 This section describes the formats to be used for messages
5004 written to standard output by the <file>/etc/init.d</file>
5005 scripts. The intent is to improve the consistency of
5006 Debian's startup and shutdown look and feel. For this
5007 reason, please look very carefully at the details. We want
5008 the messages to have the same format in terms of wording,
5009 spaces, punctuation and case of letters.
5013 Here is a list of overall rules that you should use when you
5014 create output messages. They can be useful if you have a
5015 non-standard message that is not covered specifically in the
5023 Every message should fit in one line (fewer than 80
5024 characters), start with a capital letter and end with
5025 a period (<tt>.</tt>) and line feed (<tt>"\n"</tt>).
5031 If you want to express that the computer is working on
5032 something (that is, performing a specific task, not
5033 starting or stopping a program), we use an "ellipsis"
5034 (three dots: <tt>...</tt>). Note that we don't insert
5035 spaces before or after the dots. If the task has been
5036 completed we write <tt>done.</tt> and a line feed.
5042 Design your messages as if the computer is telling you
5043 what he is doing (let him be polite :-), but don't
5044 mention "him" directly. For example, if you think of
5046 <example compact="compact">
5047 I'm starting network daemons: nfsd mountd.
5050 <example compact="compact">
5051 Starting network daemons: nfsd mountd.
5059 There are standard message formats for the following
5060 situations. They should be used by the <tt>init.d</tt>
5067 <p>When daemons are started</p>
5070 If your script starts one or more daemons, the output
5071 should look like this (a single line, no leading
5073 <example compact="compact">
5074 Starting <var>description</var>: <var>daemon-1</var> ... <var>daemon-n</var>.
5076 The <var>description</var> should describe the
5077 subsystem the daemon or set of daemons are part of,
5078 while <var>daemon-1</var> up to <var>daemon-n</var>
5079 denote each daemon's name (typically the file name of
5084 For example, the output of <file>/etc/init.d/lpd</file>
5086 <example compact="compact">
5087 Starting printer spooler: lpd.
5092 This can be achieved by saying
5093 <example compact="compact">
5094 echo -n "Starting printer spooler: lpd"
5095 start-stop-daemon --start --quiet --exec /usr/sbin/lpd
5098 in the script. If you have more than one daemon to
5099 start, you should do the following:
5100 <example compact="compact">
5101 echo -n "Starting remote file system services:"
5102 echo -n " nfsd"; start-stop-daemon --start --quiet nfsd
5103 echo -n " mountd"; start-stop-daemon --start --quiet mountd
5104 echo -n " ugidd"; start-stop-daemon --start --quiet ugidd
5107 This makes it possible for the user to see what takes
5108 so long and when the final daemon has been started.
5109 You should be careful where to put spaces: in the
5110 example above the system administrator can easily
5111 comment out a line if he don't wants to start a
5112 specific daemon, while the displayed message still
5118 <p>When a system parameter is being set</p>
5121 If you have to set up different system parameters
5122 during the system boot, you should use this format:
5123 <example compact="compact">
5124 Setting <var>parameter</var> to "<var>value</var>".
5129 You can use a statement such as the following to get
5131 <example compact="compact">
5132 echo "Setting DNS domainname to \"$domainname\"."
5137 Note that the same symbol (<tt>"</tt>) is used for the left
5138 and right quotation marks. A grave accent (<tt>`</tt>) is
5139 not a quote character; neither is an apostrophe
5145 <p>When a daemon is stopped or restarted</p>
5148 When you stop or restart a daemon, you should issue a
5149 message identical to the startup message, except that
5150 <tt>Starting</tt> is replaced with <tt>Stopping</tt>
5151 or <tt>Restarting</tt> respectively.
5155 For example, stopping the printer daemon will like
5157 <example compact="compact">
5158 Stopping printer spooler: lpd.
5164 <p>When something is executed</p>
5167 There are several examples where you have to run a
5168 program at system startup or shutdown to perform a
5169 specific task, for example, setting the system's clock
5170 using <prgn>netdate</prgn> or killing all processes
5171 when the system shuts down. Your message should look
5173 <example compact="compact">
5174 Doing something very useful...done.
5176 You should print the <tt>done.</tt> immediately after
5177 the job has been completed, so that the user is
5178 informed why she has to wait. You can get this
5180 <example compact="compact">
5181 echo -n "Doing something very useful..."
5190 <p>When the configuration is reloaded</p>
5193 When a daemon is forced to reload its configuration
5194 files you should use the following format:
5195 <example compact="compact">
5196 Reloading <var>description</var> configuration...done.
5198 where <var>description</var> is the same as in the
5199 daemon starting message.
5207 <heading>Cron jobs</heading>
5210 Packages must not modify the configuration file
5211 <file>/etc/crontab</file>, and they must not modify the files in
5212 <file>/var/spool/cron/crontabs</file>.</p>
5215 If a package wants to install a job that has to be executed
5216 via cron, it should place a file with the name of the
5217 package in one or more of the following directories:
5218 <example compact="compact">
5223 As these directory names imply, the files within them are
5224 executed on a daily, weekly, or monthly basis,
5225 respectively. The exact times are listed in
5226 <file>/etc/crontab</file>.</p>
5229 All files installed in any of these directories must be
5230 scripts (e.g., shell scripts or Perl scripts) so that they
5231 can easily be modified by the local system administrator.
5232 In addition, they should be treated as configuration
5237 If a certain job has to be executed more frequently than
5238 daily, the package should install a file
5239 <file>/etc/cron.d/<var>package</var></file>. This file uses the
5240 same syntax as <file>/etc/crontab</file> and is processed by
5241 <prgn>cron</prgn> automatically. The file must also be
5242 treated as a configuration file. (Note that entries in the
5243 <file>/etc/cron.d</file> directory are not handled by
5244 <prgn>anacron</prgn>. Thus, you should only use this
5245 directory for jobs which may be skipped if the system is not
5249 The scripts or crontab entries in these directories should
5250 check if all necessary programs are installed before they
5251 try to execute them. Otherwise, problems will arise when a
5252 package was removed but not purged since configuration files
5253 are kept on the system in this situation.</p>
5257 <heading>Menus</heading>
5260 Menu entries should follow the current menu policy found in
5261 the <tt>menu-policy</tt> files in the <tt>debian-policy</tt>
5262 package. It may also be found on the Debian FTP site
5263 <ftpsite>ftp.debian.org</ftpsite> as the file
5264 <ftppath>/debian/doc/package-developer/menu-policy.txt.gz</ftppath>,
5265 or in the equivalent location on your local mirror.
5269 The Debian <tt>menu</tt> package provides a standard
5270 interface between packages providing applications and
5271 documents, and <em>menu programs</em> (either X window
5272 managers or text-based menu programs such as
5273 <prgn>pdmenu</prgn>).
5277 All packages that provide applications that need not be
5278 passed any special command line arguments for normal
5279 operation should register a menu entry for those
5280 applications, so that users of the <tt>menu</tt> package
5281 will automatically get menu entries in their window
5282 managers, as well in shells like <tt>pdmenu</tt>.</p>
5285 Please also refer to the <em>Debian Menu System</em>
5286 documentation that comes with the <tt>menu</tt> package for
5287 information about how to register your applications and web
5293 <heading>Multimedia handlers</heading>
5296 Packages which provide the ability to view/show/play,
5297 compose, edit or print MIME types should register themselves
5298 as such following the current MIME support policy found in
5299 the <tt>mime-policy</tt> files in the <tt>debian-policy</tt>
5300 package. It may also be found on the Debian FTP site
5301 <ftpsite>ftp.debian.org</ftpsite> as the file
5302 <ftppath>/debian/doc/package-developer/mime-policy.txt.gz</ftppath>,
5303 or in the equivalent location on your local mirror.
5307 MIME (Multipurpose Internet Mail Extensions, RFCs 2045-2049)
5308 is a mechanism for encoding files and data streams and
5309 providing meta-information about them, in particular their
5310 type (e.g. audio or video) and format (e.g. PNG, HTML,
5315 Registration of MIME type handlers allows programs like mail
5316 user agents and web browsers to to invoke these handlers to
5317 view, edit or display MIME types they don't support
5323 <heading>Keyboard configuration</heading>
5326 To achieve a consistent keyboard configuration so that all
5327 applications interpret a keyboard event the same way, all
5328 programs in the Debian distribution must be configured to
5329 comply with the following guidelines.
5333 The following keys must have the specified interpretations:
5336 <tag><tt><--</tt></tag>
5337 <item><p>delete the character to the left of the cursor</p></item>
5339 <tag><tt>Delete</tt></tag>
5340 <item><p>delete the character to the right of the cursor</p></item>
5342 <tag><tt>Control+H</tt></tag>
5343 <item><p>emacs: the help prefix</p></item>
5346 The interpretation of any keyboard events should be
5347 independent of the terminal that is used, be it a virtual
5348 console, an X terminal emulator, an rlogin/telnet session,
5353 The following list explains how the different programs
5354 should be set up to achieve this:
5359 <item><p><tt><--</tt> generates <tt>KB_BackSpace</tt>
5362 <item><p><tt>Delete</tt> generates <tt>KB_Delete</tt> in
5367 X translations are set up to make
5368 <tt>KB_Backspace</tt> generate ASCII DEL, and to make
5369 <tt>KB_Delete</tt> generate <tt>ESC [ 3 ~</tt> (this
5370 is the vt220 escape code for the "delete character"
5371 key). This must be done by loading the X resources
5372 using <prgn>xrdb</prgn> on all local X displays, not
5373 using the application defaults, so that the
5374 translation resources used correspond to the
5375 <prgn>xmodmap</prgn> settings.</p></item>
5379 The Linux console is configured to make
5380 <tt><--</tt> generate DEL, and <tt>Delete</tt>
5381 generate <tt>ESC [ 3 ~</tt>.</p></item>
5385 X applications are configured so that <tt><</tt>
5386 deletes left, and <tt>Delete</tt> deletes right. Motif
5387 applications already work like this.</p></item>
5389 <item><p>Terminals should have <tt>stty erase ^?</tt> .</p></item>
5393 The <tt>xterm</tt> terminfo entry should have <tt>ESC
5394 [ 3 ~</tt> for <tt>kdch1</tt>, just as for
5395 <tt>TERM=linux</tt> and <tt>TERM=vt220</tt>.</p></item>
5399 Emacs is programmed to map <tt>KB_Backspace</tt> or
5400 the <tt>stty erase</tt> character to
5401 <tt>delete-backward-char</tt>, and <tt>KB_Delete</tt>
5402 or <tt>kdch1</tt> to <tt>delete-forward-char</tt>, and
5403 <tt>^H</tt> to <tt>help</tt> as always.</p></item>
5407 Other applications use the <tt>stty erase</tt>
5408 character and <tt>kdch1</tt> for the two delete keys,
5409 with ASCII DEL being "delete previous character" and
5410 <tt>kdch1</tt> being "delete character under
5417 This will solve the problem except for the following
5425 Some terminals have a <tt><--</tt> key that cannot
5426 be made to produce anything except <tt>^H</tt>. On
5427 these terminals Emacs help will be unavailable on
5428 <tt>^H</tt> (assuming that the <tt>stty erase</tt>
5429 character takes precedence in Emacs, and has been set
5430 correctly). <tt>M-x help</tt> or <tt>F1</tt> (if
5431 available) can be used instead.</p></item>
5435 Some operating systems use <tt>^H</tt> for <tt>stty
5436 erase</tt>. However, modern telnet versions and all
5437 rlogin versions propagate <tt>stty</tt> settings, and
5438 almost all UNIX versions honour <tt>stty erase</tt>.
5439 Where the <tt>stty</tt> settings are not propagated
5440 correctly, things can be made to work by using
5441 <tt>stty</tt> manually.</p></item>
5445 Some systems (including previous Debian versions) use
5446 <prgn>xmodmap</prgn> to arrange for both
5447 <tt><--</tt> and <tt>Delete</tt> to generate
5448 <tt>KB_Delete</tt>. We can change the behavior of
5449 their X clients using the same X resources that we use
5450 to do it for our own clients, or configure our clients
5451 using their resources when things are the other way
5452 around. On displays configured like this
5453 <tt>Delete</tt> will not work, but <tt><--</tt>
5458 Some operating systems have different <tt>kdch1</tt>
5459 settings in their <tt>terminfo</tt> database for
5460 <tt>xterm</tt> and others. On these systems the
5461 <tt>Delete</tt> key will not work correctly when you
5462 log in from a system conforming to our policy, but
5463 <tt><--</tt> will.</p></item>
5469 <heading>Environment variables</heading>
5472 A program must not depend on environment variables to get
5473 reasonable defaults. (That's because these environment
5474 variables would have to be set in a system-wide
5475 configuration file like <file>/etc/profile</file>, which is not
5476 supported by all shells.)</p>
5479 If a program usually depends on environment variables for its
5480 configuration, the program should be changed to fall back to
5481 a reasonable default configuration if these environment
5482 variables are not present. If this cannot be done easily
5483 (e.g., if the source code of a non-free program is not
5484 available), the program must be replaced by a small
5485 "wrapper" shell script which sets the environment variables
5486 if they are not already defined, and calls the original program.</p>
5489 Here is an example of a wrapper script for this purpose:
5491 <example compact="compact">
5493 BAR=${BAR:-/var/lib/fubar}
5495 exec /usr/lib/foo/foo "$@"
5500 Furthermore, as <file>/etc/profile</file> is a configuration
5501 file of the <prgn>base-files</prgn> package, other packages must not
5502 put any environment variables or other commands into that
5508 <heading>Files</heading>
5511 <heading>Binaries</heading>
5514 Two different packages must not install programs with
5515 different functionality but with the same filenames. (The
5516 case of two programs having the same functionality but
5517 different implementations is handled via "alternatives" or
5518 the "Conflicts" mechanism. See <ref id="maintscripts"> and
5519 <ref id="conflicts"> respectively.) If this case happens,
5520 one of the programs must be renamed. The maintainers should
5521 report this to the <tt>debian-devel</tt> mailing list and
5522 try to find a consensus about which program will have to be
5523 renamed. If a consensus cannot be reached, <em>both</em>
5524 programs must be renamed.
5528 By default, when a package is being built, any binaries
5529 created should include debugging information, as well as
5530 being compiled with optimization. You should also turn on
5531 as many reasonable compilation warnings as possible; this
5532 makes life easier for porters, who can then look at build
5533 logs for possible problems. For the C programming language,
5534 this means the following compilation parameters should be
5536 <example compact="compact">
5538 CFLAGS = -O2 -g -Wall # sane warning options vary between programs
5540 install -s # (or use strip on the files in debian/tmp)
5545 Note that by default all installed binaries should be stripped,
5546 either by using the <tt>-s</tt> flag to
5547 <prgn>install</prgn>, or by calling <prgn>strip</prgn> on
5548 the binaries after they have been copied into
5549 <file>debian/tmp</file> but before the tree is made into a
5553 Although binaries in the build tree should be compiled with
5554 debugging information by default, it can often be difficult
5555 to debug programs if they are also subjected to compiler
5556 optimization. For this reason, it is recommended to support
5557 the standardized environment
5558 variable <tt>DEB_BUILD_OPTIONS</tt>. This variable can
5559 contain several flags to change how a package is compiled
5567 The presence of this string means that the package
5568 should be complied with a minimum of optimization.
5569 For C programs, it is best to add <tt>-O0</tt>
5570 to <tt>CFLAGS</tt> (although this is usually the
5571 default). Some programs might fail to build or run at
5572 this level of optimization; it may be necessary to
5573 use <tt>-O1</tt>, for example.
5579 This string means that the debugging symbols should
5580 not be stripped from the binary during installation,
5581 so that debugging information may be included in the package.
5587 The following makefile snippet is an example of how one may
5588 implement the build options; you will probably have to
5589 massage this example in order to make it work for your
5591 <example compact="compact">
5594 INSTALL_FILE = $(INSTALL) -p -o root -g root -m 644
5595 INSTALL_PROGRAM = $(INSTALL) -p -o root -g root -m 755
5596 INSTALL_SCRIPT = $(INSTALL) -p -o root -g root -m 755
5597 INSTALL_DIR = $(INSTALL) -p -d -o root -g root -m 755
5599 ifneq (,$(findstring noopt,$(DEB_BUILD_OPTIONS)))
5604 ifeq (,$(findstring nostrip,$(DEB_BUILD_OPTIONS)))
5605 INSTALL_PROGRAM += -s
5611 It is up to the package maintainer to decide what
5612 compilation options are best for the package. Certain
5613 binaries (such as computationally-intensive programs) will
5614 function better with certain flags (<tt>-O3</tt>, for
5615 example); feel free to use them. Please use good judgment
5616 here. Don't use flags for the sake of it; only use them
5617 if there is good reason to do so. Feel free to override
5618 the upstream author's ideas about which compilation
5619 options are best: they are often inappropriate for our
5626 <heading>Libraries</heading>
5629 In general, libraries must have a shared version in the
5630 library package (<package>lib*</package>) and a static
5631 version in the development package (<package>lib*-dev</package>).
5632 The shared version must be compiled with <tt>-fPIC</tt>,
5633 and the static version must not be. In other words, each source
5634 unit (<tt>*.c</tt>, for example, for C files) will need to be
5639 In some cases, it is acceptable for a library to be
5640 available in static form only; these cases include:
5643 <p>libraries for languages whose shared library support
5644 is immature or unstable</p>
5648 libraries whose interfaces are in flux or under
5649 development (commonly the case when the library's
5650 major version number is zero, or where the ABI breaks
5656 libraries which are explicitly intended to be
5657 available only in static form by their upstream
5661 If a library is available only in static form, then it must follow
5662 the conventions for a development package.
5666 You must specify the gcc option <tt>-D_REENTRANT</tt>
5667 when building a library (either static or shared) to make
5668 the library compatible with LinuxThreads.
5672 Note that all installed shared libraries should be
5674 <example compact="compact">
5675 strip --strip-unneeded <var>your-lib</var>
5677 (The option <tt>--strip-unneeded</tt> makes
5678 <prgn>strip</prgn> remove only the symbols which aren't
5679 needed for relocation processing.) Shared libraries can
5680 function perfectly well when stripped, since the symbols for
5681 dynamic linking are in a separate part of the ELF object
5684 You might also want to use the options
5685 <tt>--remove-section=.comment</tt> and
5686 <tt>--remove-section=.note</tt> on both shared libraries
5687 and executables, and <tt>--strip-debug</tt> on static
5694 Note that under some circumstances it may be useful to
5695 install a shared library unstripped, for example when
5696 building a separate package to support debugging.
5700 Shared object files (often <file>.so</file> files) that are not
5701 public libraries, that is, they are not meant to be linked
5702 to by third party executables (binaries of other packages),
5703 should be installed in subdirectories of the
5704 <file>/usr/lib</file> directory. Such files are exempt from the
5705 rules that govern ordinary shared libraries, except that
5706 they must not be installed executable and should be
5709 A common example are the so-called "plug-ins",
5710 internal shared objects that are dynamically loaded by
5711 programs using <manref name="dlopen" section="3">.
5717 Packages containing shared libraries that may be linked to
5718 by other packages' binaries, but which for some
5719 <em>compelling</em> reason can not be installed in
5720 <file>/usr/lib</file> directory, may install the shared library
5721 files in subdirectories of the <file>/usr/lib</file> directory,
5722 in which case they should arrange to add that directory in
5723 <file>/etc/ld.so.conf</file> in the package's post-installation
5724 script, and remove it in the package's post-removal script.
5728 An ever increasing number of packages are using
5729 <prgn>libtool</prgn> to do their linking. The latest GNU
5730 libtools (>= 1.3a) can take advantage of the metadata in the
5731 installed <prgn>libtool</prgn> archive files (<file>*.la</file>
5732 files). The main advantage of <prgn>libtool</prgn>'s
5733 <file>.la</file> files is that it allows <prgn>libtool</prgn> to
5734 store and subsequently access metadata with respect to the
5735 libraries it builds. <prgn>libtool</prgn> will search for
5736 those files, which contain a lot of useful information about
5737 a library (such as library dependency information for static
5738 linking). Also, they're <em>essential</em> for programs
5739 using <tt>libltdl</tt>.<footnote>
5741 Although <prgn>libtool</prgn> is fully capable of
5742 linking against shared libraries which don't have
5743 <tt>.la</tt> files, as it is a mere shell script it can
5744 add considerably to the build time of a
5745 <prgn>libtool</prgn>-using package if that shell script
5746 has to derive all this information from first principles
5747 for each library every time it is linked. With the
5748 advent of <prgn>libtool</prgn> version 1.4 (and to a
5749 lesser extent <prgn>libtool</prgn> version 1.3), the
5750 <file>.la</file> files also store information about
5751 inter-library dependencies which cannot necessarily be
5752 derived after the <file>.la</file> file is deleted.
5758 Packages that use <prgn>libtool</prgn> to create shared
5759 libraries should include the <file>.la</file> files in the
5760 <tt>-dev</tt> package, unless the package relies on
5761 <tt>libtool</tt>'s <tt>libltdl</tt> library, in which case
5762 the <tt>.la</tt> files must go in the run-time library
5767 You must make sure that you use only released versions of
5768 shared libraries to build your packages; otherwise other
5769 users will not be able to run your binaries
5770 properly. Producing source packages that depend on
5771 unreleased compilers is also usually a bad
5777 <heading>Shared libraries</heading>
5780 Packages involving shared libraries should be split up
5781 into several binary packages.</p>
5784 For a straightforward library which has a development
5785 environment and a runtime kit including just shared
5786 libraries you need to create two packages:
5787 <file><var>libraryname</var><var>soversion</var></file>, where
5788 <file><var>soversion</var></file> is the version number in the
5789 soname of the shared library<footnote>
5791 The soname is the shared object name: it's the thing
5792 that has to match exactly between building an executable
5793 and running it for the dynamic linker to be able run the
5794 program. For example, if the soname of the library is
5795 <file>libfoo.so.6</file>, the library package would be
5796 called <file>libfoo6</file>.
5799 and <tt><var>libraryname</var><var>soversion</var>-dev</tt>.
5800 Alternatively, if it would be confusing to directly append
5801 <var>soversion</var> to <var>libraryname</var> (e.g. because
5802 <var>libraryname</var> itself ends in a number), you may use
5803 <tt><var>libraryname</var>-<var>soversion</var></tt> and
5804 <tt><var>libraryname</var>-<var>soversion</var>-dev</tt>
5809 If you prefer only to support one development version at a
5810 time you may name the development package
5811 <file><var>libraryname</var>-dev</file>; otherwise you may need
5812 to use <prgn>dpkg</prgn>'s Conflicts mechanism (see <ref
5813 id="conflicts">) to ensure that the user only installs one
5814 development version at a time (as different development
5815 versions are likely to have the same header files in them,
5816 which would cause a filename clash if both were installed).
5817 Typically the development version should also have an exact
5818 version dependency on the runtime library, to make sure that
5819 compilation and linking happens correctly. The
5820 <tt>${Source-Version}</tt> substitution variable can be
5821 useful for this purpose.
5825 Packages which use the shared library should have a
5826 dependency on the name of the shared library package,
5827 <file><var>libraryname</var><var>soversion</var></file>. When
5828 the soname changes you can have both versions of the library
5829 installed while migrating from the old library to the new.
5833 If your package has some run-time support programs which use
5834 the shared library you must not put them in the shared
5835 library package. If you do that then you won't be able to
5836 install several versions of the shared library without
5837 getting filename clashes. Instead, either create a third
5838 package for the runtime binaries (this package might
5839 typically be named <tt><var>libraryname</var>-runtime</tt>;
5840 note the absence of the <var>soversion</var> in the package
5841 name), or if the development package is small you may
5842 include them in there.
5846 If you have several shared libraries built from the same
5847 source tree you may lump them all together into a single
5848 shared library package, provided that you change all of
5849 their sonames at once (so that you don't get filename
5850 clashes if you try to install different versions of the
5851 combined shared libraries package).
5855 Shared libraries should not be installed executable, since
5856 the dynamic linker does not require this and trying to
5857 execute a shared library usually results in a core dump.
5862 <heading>Scripts</heading>
5865 All command scripts, including the package maintainer
5866 scripts inside the package and used by <prgn>dpkg</prgn>,
5867 should have a <tt>#!</tt> line naming the shell to be used
5868 to interpret them.</p>
5871 In the case of Perl scripts this should be
5872 <tt>#!/usr/bin/perl</tt>.</p>
5875 Shell scripts (<prgn>sh</prgn> and <prgn>bash</prgn>)
5876 should almost certainly start with <tt>set -e</tt> so that
5877 errors are detected. Every script should use
5878 <tt>set -e</tt> or check the exit status of <em>every</em>
5882 The standard shell interpreter <file>/bin/sh</file> can be a
5883 symbolic link to any POSIX compatible shell, if <tt>echo
5884 -n</tt> does not generate a newline.<footnote>
5886 Debian policy specifies POSIX behavior for
5887 <file>/bin/sh</file>, but <tt>echo -n</tt> has widespread
5888 use in the Linux community (in particular including this
5889 policy, the Linux kernel source, many Debian scripts,
5890 etc.). This <tt>echo -n</tt> mechanism is valid but not
5891 required under POSIX, hence this explicit addition.
5892 Also, rumour has it that this shall be mandated under
5896 Thus, shell scripts specifying <file>/bin/sh</file> as
5897 interpreter should only use POSIX features. If a script
5898 requires non-POSIX features from the shell interpreter, the
5899 appropriate shell must be specified in the first line of the
5900 script (e.g., <tt>#!/bin/bash</tt>) and the package must
5901 depend on the package providing the shell (unless the shell
5902 package is marked "Essential", as in the case of
5907 You may wish to restrict your script to POSIX features when
5908 possible so that it may use <file>/bin/sh</file> as its
5909 interpreter. If your script works with <prgn>dash</prgn>
5910 (originally called <prgn>ash</prgn>), it's probably POSIX
5911 compliant, but if you are in doubt, use
5912 <file>/bin/bash</file>.
5916 Perl scripts should check for errors when making any
5917 system calls, including <tt>open</tt>, <tt>print</tt>,
5918 <tt>close</tt>, <tt>rename</tt> and <tt>system</tt>.
5922 <prgn>csh</prgn> and <prgn>tcsh</prgn> should be avoided as
5923 scripting languages. See <em>Csh Programming Considered
5924 Harmful</em>, one of the <tt>comp.unix.*</tt> FAQs, which
5925 can be found at <url
5926 id="http://language.perl.com/versus/csh.whynot">.<footnote>
5928 It can also be found on
5929 <url id="http://www.cpan.org/doc/FMTEYEWTK/versus/csh.whynot">
5930 or on the ftp site <ftpsite>ftp.cpan.org</ftpsite> as
5931 <ftppath>/pub/perl/CPAN/doc/FMTEYEWTK/versus/csh.whynot</ftppath>.
5934 If an upstream package comes with <prgn>csh</prgn> scripts
5935 then you must make sure that they start with
5936 <tt>#!/bin/csh</tt> and make your package depend on the
5937 <prgn>c-shell</prgn> virtual package.
5941 Any scripts which create files in world-writeable
5942 directories (e.g., in <file>/tmp</file>) must use a
5943 mechanism which will fail if a file with the same name
5947 The Debian base system provides the <prgn>tempfile</prgn>
5948 and <prgn>mktemp</prgn> utilities for use by scripts for
5949 this purpose.</p></sect>
5953 <heading>Symbolic links</heading>
5956 In general, symbolic links within a top-level directory
5957 should be relative, and symbolic links pointing from one
5958 top-level directory into another should be absolute. (A
5959 top-level directory is a sub-directory of the root
5960 directory <file>/</file>.)</p>
5963 In addition, symbolic links should be specified as short as
5964 possible, i.e., link targets like <file>foo/../bar</file> are
5968 Note that when creating a relative link using
5969 <prgn>ln</prgn> it is not necessary for the target of the
5970 link to exist relative to the working directory you're
5971 running <prgn>ln</prgn> from, nor is it necessary to change
5972 directory to the directory where the link is to be made.
5973 Simply include the string that should appear as the target
5974 of the link (this will be a pathname relative to the
5975 directory in which the link resides) as the first argument
5976 to <prgn>ln</prgn>.</p>
5979 For example, in your <prgn>Makefile</prgn> or
5980 <file>debian/rules</file>, you can do things like:
5981 <example compact="compact">
5982 ln -fs gcc $(prefix)/bin/cc
5983 ln -fs gcc debian/tmp/usr/bin/cc
5984 ln -fs ../sbin/sendmail $(prefix)/bin/runq
5985 ln -fs ../sbin/sendmail debian/tmp/usr/bin/runq
5989 A symbolic link pointing to a compressed file should always
5990 have the same file extension as the referenced file. (For
5991 example, if a file <file>foo.gz</file> is referenced by a
5992 symbolic link, the filename of the link has to end with
5993 "<file>.gz</file>" too, as in <file>bar.gz</file>.)
5998 <heading>Device files</heading>
6001 Packages must not include device files in the package file
6005 If a package needs any special device files that are not
6006 included in the base system, it must call
6007 <prgn>MAKEDEV</prgn> in the <prgn>postinst</prgn> script,
6008 after notifying the user<footnote>
6010 This notification could be done via a (low-priority)
6011 debconf message, or an echo (printf) statement.
6017 Packages must not remove any device files in the
6018 <prgn>postrm</prgn> or any other script. This is left to the
6019 system administrator.</p>
6022 Debian uses the serial devices
6023 <file>/dev/ttyS*</file>. Programs using the old
6024 <file>/dev/cu*</file> devices should be changed to use
6025 <file>/dev/ttyS*</file>.</p>
6028 <sect id="config-files">
6029 <heading>Configuration files</heading>
6031 <heading>Definitions</heading>
6034 <tag>configuration file</tag>
6037 A file that affects the operation of a program, or
6038 provides site- or host-specific information, or
6039 otherwise customizes the behavior of a program.
6040 Typically, configuration files are intended to be
6041 modified by the system administrator (if needed or
6042 desired) to conform to local policy or to provide
6043 more useful site-specific behavior.
6047 <tag><tt>conffile</tt></tag>
6050 A file listed in a package's <tt>conffiles</tt>
6051 file, and is treated specially by <prgn>dpkg</prgn>
6052 (see <ref id="configdetails">).
6059 The distinction between these two is important; they are
6060 not interchangeable concepts. Almost all
6061 <tt>conffile</tt>s are configuration files, but many
6062 configuration files are not <tt>conffiles</tt>.
6066 Note that a script that embeds configuration information
6067 (such as most of the files in <file>/etc/default</file> and
6068 <file>/etc/cron.{daily,weekly,monthly}</file>) is de-facto a
6069 configuration file and should be treated as such.
6074 <heading>Location</heading>
6076 Any configuration files created or used by your package
6077 must reside in <file>/etc</file>. If there are several you
6078 should consider creating a subdirectory of <file>/etc</file>
6079 named after your package.</p>
6082 If your package creates or uses configuration files
6083 outside of <file>/etc</file>, and it is not feasible to modify
6084 the package to use the <file>/etc</file>, you should still put
6085 the files in <file>/etc</file> and create symbolic links to
6086 those files from the location that the package
6091 <heading>Behavior</heading>
6093 Configuration file handling must conform to the following
6095 <list compact="compact">
6098 local changes must be preserved during a package
6104 configuration files must be preserved when the
6105 package is removed, and only deleted when the
6113 The easy way to achieve this behavior is to make the
6114 configuration file a <tt>conffile</tt>. This is
6115 appropriate only if it is possible to distribute a default
6116 version that will work for most installations, although
6117 some system administrators may choose to modify it. This
6118 implies that the default version will be part of the
6119 package distribution, and must not be modified by the
6120 maintainer scripts during installation (or at any other
6125 In order to ensure that local changes are preserved
6126 correctly, no package may contain or make hard links to
6127 conffiles.<footnote>
6129 Rationale: There are two problems with hard links.
6130 The first is that some editors break the link while
6131 editing one of the files, so that the two files may
6132 unwittingly become unlinked and different. The second
6133 is that <prgn>dpkg</prgn> might break the hard link
6134 while upgrading <tt>conffile</tt>s.
6140 The other way to do it is via the maintainer scripts. In
6141 this case, the configuration file must not be listed as a
6142 <tt>conffile</tt> and must not be part of the package
6143 distribution. If the existence of a file is required for
6144 the package to be sensibly configured it is the
6145 responsibility of the package maintainer to provide
6146 maintainer scripts which correctly create, update and
6147 maintain the file and remove it on purge. (See <ref
6148 id="maintainerscripts"> for more information.) These
6149 scripts must be idempotent (i.e., must work correctly if
6150 <prgn>dpkg</prgn> needs to re-run them due to errors
6151 during installation or removal), must cope with all the
6152 variety of ways <prgn>dpkg</prgn> can call maintainer
6153 scripts, must not overwrite or otherwise mangle the user's
6154 configuration without asking, must not ask unnecessary
6155 questions (particularly during upgrades), and otherwise be
6160 The scripts are not required to configure every possible
6161 option for the package, but only those necessary to get
6162 the package running on a given system. Ideally the
6163 sysadmin should not have to do any configuration other
6164 than that done (semi-)automatically by the
6165 <prgn>postinst</prgn> script.
6169 A common practice is to create a script called
6170 <file><var>package</var>-configure</file> and have the
6171 package's <prgn>postinst</prgn> call it if and only if the
6172 configuration file does not already exist. In certain
6173 cases it is useful for there to be an example or template
6174 file which the maintainer scripts use. Such files should
6175 be in <file>/usr/share/<var>package</var></file> or
6176 <file>/usr/lib/<var>package</var></file> (depending on whether
6177 they are architecture-independent or not). There should
6178 be symbolic links to them from
6179 <file>/usr/share/doc/<var>package</var>/examples</file> if
6180 they are examples, and should be perfectly ordinary
6181 <prgn>dpkg</prgn>-handled files (<em>not</em>
6182 configuration files).
6186 These two styles of configuration file handling must
6187 not be mixed, for that way lies madness:
6188 <prgn>dpkg</prgn> will ask about overwriting the file
6189 every time the package is upgraded.
6194 <heading>Sharing configuration files</heading>
6196 Packages which specify the same file as a
6197 <tt>conffile</tt> must be tagged as <em>conflicting</em>
6198 with each other. (This is an instance of the general rule
6199 about not sharing files. Note that neither alternatives
6200 nor diversions are likely to be appropriate in this case;
6201 in particular, <prgn>dpkg</prgn> does not handle diverted
6202 <tt>conffile</tt>s well.)
6206 The maintainer scripts must not alter a <tt>conffile</tt>
6207 of <em>any</em> package, including the one the scripts
6212 If two or more packages use the same configuration file
6213 and it is reasonable for both to be installed at the same
6214 time, one of these packages must be defined as
6215 <em>owner</em> of the configuration file, i.e., it will be
6216 the package which handles that file as a configuration
6217 file. Other packages that use the configuration file must
6218 depend on the owning package if they require the
6219 configuration file to operate. If the other package will
6220 use the configuration file if present, but is capable of
6221 operating without it, no dependency need be declared.</p>
6224 If it is desirable for two or more related packages to
6225 share a configuration file <em>and</em> for all of the
6226 related packages to be able to modify that configuration
6227 file, then the following should be done:
6228 <enumlist compact="compact">
6231 One of the related packages (the "owning" package)
6232 will manage the configuration file with maintainer
6233 scripts as described in the previous section.
6238 The owning package should also provide a program
6239 that the other packages may use to modify the
6245 The related packages must use the provided program
6246 to make any desired modifications to the
6247 configuration file. They should either depend on
6248 the core package to guarantee that the configuration
6249 modifier program is available or accept gracefully
6250 that they cannot modify the configuration file if it
6251 is not. (This is in addition to the fact that the
6252 configuration file may not even be present in the
6260 Sometimes it's appropriate to create a new package which
6261 provides the basic infrastructure for the other packages
6262 and which manages the shared configuration files. (The
6263 <tt>sgml-base</tt> package is a good example.)
6268 <heading>User configuration files ("dotfiles")</heading>
6271 The files in <file>/etc/skel</file> will automatically be
6272 copied into new user accounts by <prgn>adduser</prgn>.
6273 No other program should reference the files in
6274 <file>/etc/skel</file>.
6278 Therefore, if a program needs a dotfile to exist in
6279 advance in <file>$HOME</file> to work sensibly, that dotfile
6280 should be installed in <file>/etc/skel</file> and treated as a
6285 However, programs that require dotfiles in order to
6286 operate sensibly are a bad thing, unless they do create
6287 the dotfiles themselves automatically.
6291 Furthermore, programs should be configured by the Debian
6292 default installation to behave as closely to the upstream
6293 default behaviour as possible.
6297 Therefore, if a program in a Debian package needs to be
6298 configured in some way in order to operate sensibly, that
6299 should be done using a site-wide configuration file placed
6300 in <file>/etc</file>. Only if the program doesn't support a
6301 site-wide default configuration and the package maintainer
6302 doesn't have time to add it may a default per-user file be
6303 placed in <file>/etc/skel</file>.
6307 <file>/etc/skel</file> should be as empty as we can make it.
6308 This is particularly true because there is no easy (or
6309 necessarily desirable) mechanism for ensuring that the
6310 appropriate dotfiles are copied into the accounts of
6311 existing users when a package is installed.
6317 <heading>Log files</heading>
6319 Log files should usually be named
6320 <file>/var/log/<var>package</var>.log</file>. If you have many
6321 log files, or need a separate directory for permission
6322 reasons (<file>/var/log</file> is writable only by
6323 <file>root</file>), you should usually create a directory named
6324 <file>/var/log/<var>package</var></file> and place your log
6329 Log files must be rotated occasionally so that they don't
6330 grow indefinitely; the best way to do this is to drop a log
6331 rotation configuration file into the directory
6332 <file>/etc/logrotate.d</file> and use the facilities provided by
6333 logrotate.<footnote>
6335 The traditional approach to log files has been to set up
6336 <em>ad hoc</em> log rotation schemes using simple shell
6337 scripts and cron. While this approach is highly
6338 customizable, it requires quite a lot of sysadmin work.
6339 Even though the original Debian system helped a little
6340 by automatically installing a system which can be used
6341 as a template, this was deemed not enough.
6345 The use of <prgn>logrotate</prgn>, a program developed
6346 by Red Hat, is better, as it centralizes log management.
6347 It has both a configuration file
6348 (<file>/etc/logrotate.conf</file>) and a directory where
6349 packages can drop their individual log rotation
6350 configurations (<file>/etc/logrotate.d</file>).
6353 Here is a good example for a logrotate config
6354 file (for more information see <manref name="logrotate"
6356 <example compact="compact">
6362 /etc/init.d/foo force-reload
6366 This rotates all files under <file>/var/log/foo</file>, saves 12
6367 compressed generations, and forces the daemon to reload its
6368 configuration information after the log rotation.
6372 Log files should be removed when the package is
6373 purged (but not when it is only removed). This should be
6374 done by the <prgn>postrm</prgn> script when it is called
6375 with the argument <tt>purge</tt> (see <ref
6376 id="removedetails">).
6381 <heading>Permissions and owners</heading>
6384 The rules in this section are guidelines for general use.
6385 If necessary you may deviate from the details below.
6386 However, if you do so you must make sure that what is done
6387 is secure and you should try to be as consistent as possible
6388 with the rest of the system. You should probably also
6389 discuss it on <prgn>debian-devel</prgn> first.
6393 Files should be owned by <tt>root.root</tt>, and made
6394 writable only by the owner and universally readable (and
6395 executable, if appropriate), that is mode 644 or 755.
6399 Directories should be mode 755 or (for group-writability)
6400 mode 2775. The ownership of the directory should be
6401 consistent with its mode: if a directory is mode 2775, it
6402 should be owned by the group that needs write access to
6407 Setuid and setgid executables should be mode 4755 or 2755
6408 respectively, and owned by the appropriate user or group.
6409 They should not be made unreadable (modes like 4711 or
6410 2711 or even 4111); doing so achieves no extra security,
6411 because anyone can find the binary in the freely available
6412 Debian package; it is merely inconvenient. For the same
6413 reason you should not restrict read or execute permissions
6414 on non-set-id executables.
6418 Some setuid programs need to be restricted to particular
6419 sets of users, using file permissions. In this case they
6420 should be owned by the uid to which they are set-id, and by
6421 the group which should be allowed to execute them. They
6422 should have mode 4754; again there is no point in making
6423 them unreadable to those users who must not be allowed to
6428 It is possible to arrange that the system administrator can
6429 reconfigure the package to correspond to their local
6430 security policy by changing the permissions on a binary:
6431 they can do this by using <prgn>dpkg-statoverride</prgn>, as
6432 described below.<footnote>
6434 Ordinary files installed by <prgn>dpkg</prgn> (as
6435 opposed to <tt>conffile</tt>s and other similar objects)
6436 normally have their permissions reset to the distributed
6437 permissions when the package is reinstalled. However,
6438 the use of <prgn>dpkg-statoverride</prgn> overrides this
6439 default behaviour. If you use this method, you should
6440 remember to describe <prgn>dpkg-statoverride</prgn> in
6441 the package documentation; being a relatively new
6442 addition to Debian, it is probably not yet well-known.
6445 Another method you should consider is to create a group for
6446 people allowed to use the program(s) and make any setuid
6447 executables executable only by that group.
6451 If you need to create a new user or group for your package
6452 there are two possibilities. Firstly, you may need to
6453 make some files in the binary package be owned by this
6454 user or group, or you may need to compile the user or
6455 group id (rather than just the name) into the binary
6456 (though this latter should be avoided if possible, as in
6457 this case you need a statically allocated id).</p>
6460 If you need a statically allocated id, you must ask for a
6461 user or group id from the <tt>base-passwd</tt> maintainer,
6462 and must not release the package until you have been
6463 allocated one. Once you have been allocated one you must
6464 either make the package depend on a version of the
6465 <tt>base-passwd</tt> package with the id present in
6466 <file>/etc/passwd</file> or <file>/etc/group</file>, or arrange for
6467 your package to create the user or group itself with the
6468 correct id (using <tt>adduser</tt>) in its
6469 <prgn>preinst</prgn> or <prgn>postinst</prgn>. (Doing it in
6470 the <prgn>postinst</prgn> is to be preferred if it is
6471 possible, otherwise a pre-dependency will be needed on the
6472 <tt>adduser</tt> package.)
6476 On the other hand, the program might be able to determine
6477 the uid or gid from the user or group name at runtime, so
6478 that a dynamically allocated id can be used. In this case
6479 you should choose an appropriate user or group name,
6480 discussing this on <prgn>debian-devel</prgn> and checking
6481 with the <package/base-passwd/ maintainer that it is unique and that
6482 they do not wish you to use a statically allocated id
6483 instead. When this has been checked you must arrange for
6484 your package to create the user or group if necessary using
6485 <prgn>adduser</prgn> in the <prgn>preinst</prgn> or
6486 <prgn>postinst</prgn> script (again, the latter is to be
6487 preferred if it is possible).
6491 Note that changing the numeric value of an id associated
6492 with a name is very difficult, and involves searching the
6493 file system for all appropriate files. You need to think
6494 carefully whether a static or dynamic id is required, since
6495 changing your mind later will cause problems.
6498 <sect1><heading>The use of <prgn>dpkg-statoverride</prgn></heading>
6500 This section is not intended as policy, but as a
6501 description of the use of <prgn>dpkg-statoverride</prgn>.
6505 <prgn>dpkg-statoverride</prgn> is a replacement for the
6506 deprecated <tt>suidmanager</tt> package. Packages which
6507 previously used <tt>suidmanager</tt> should have a
6508 <tt>Conflicts: suidmanager (<< 0.50)</tt> entry (or even
6509 <tt>(<< 0.52)</tt>), and calls to <tt>suidregister</tt>
6510 and <tt>suidunregister</tt> should now be simply removed
6511 from the maintainer scripts.
6515 If a system administrator wishes to have a file (or
6516 directory or other such thing) installed with owner and
6517 permissions different from those in the distributed Debian
6518 package, he can use the <prgn>dpkg-statoverride</prgn>
6519 program to instruct <prgn>dpkg</prgn> to use the different
6520 settings every time the file is installed. Thus the
6521 package maintainer should distribute the files with their
6522 normal permissions, and leave it for the system
6523 administrator to make any desired changes. For example, a
6524 daemon which is normally required to be setuid root, but
6525 in certain situations could be used without being setuid,
6526 should be installed setuid in the <tt>.deb</tt>. Then the
6527 local system administrator can change this if they wish.
6528 If there are two standard ways of doing it, the package
6529 maintainer can use <tt>debconf</tt> to find out the
6530 preference, and call <prgn>dpkg-statoverride</prgn> in the
6531 maintainer script if necessary to accommodate the system
6532 administrator's choice.
6536 Given the above, <prgn>dpkg-statoverride</prgn> is
6537 essentially a tool for system administrators and would not
6538 normally be needed in the maintainer scripts. There is
6539 one type of situation, though, where calls to
6540 <prgn>dpkg-statoverride</prgn> would be needed in the
6541 maintainer scripts, and that involves packages which use
6542 dynamically allocated user or group ids. In such a
6543 situation, something like the following idiom can be very
6544 helpful in the package's <prgn>postinst</prgn>, where
6545 <tt>sysuser</tt> is a dynamically allocated id:
6547 for i in /usr/bin/foo /usr/sbin/bar
6549 if ! dpkg-statoverride --list $i >/dev/null
6551 dpkg-statoverride --update --add sysuser root 4755 $i
6555 The corresponding <tt>dpkg-statoverride --remove</tt>
6556 calls can then be made unconditionally when the package is
6563 <chapt id="customized-programs">
6564 <heading>Customized programs</heading>
6566 <sect id="arch-spec">
6567 <heading>Architecture specification strings</heading>
6570 If a program needs to specify an <em>architecture specification
6571 string</em> in some place, the following format should be
6572 used: <var>arch</var>-<var>os</var><footnote>
6574 The following architectures and operating systems are
6575 currently recognised by <prgn>dpkg-archictecture</prgn>.
6576 The architecture, <tt><var>arch</var></tt>, is one of
6577 the following: <tt>alpha</tt>, <tt>arm</tt>,
6578 <tt>hppa</tt>, <tt>i386</tt>, <tt>ia64</tt>,
6579 <tt>m68k</tt>, <tt>mips</tt>, <tt>mipsel</tt>,
6580 <tt>powerpc</tt>, <tt>s390</tt>, <tt>sh</tt>,
6581 <tt>sheb</tt>, <tt>sparc</tt> and <tt>sparc64</tt>. The
6582 operating system, <tt><var>os</var></tt>, is one of:
6583 <tt>linux</tt>, <tt>gnu</tt>, <tt>freebsd</tt> and
6584 <tt>openbsd</tt>. Use of <tt>gnu</tt> in this string is
6585 reserved for the GNU/Hurd operating system.
6591 Note that we don't want to use
6592 <tt><var>arch</var>-debian-linux</tt> to apply to the rule
6593 <tt><var>architecture</var>-<var>vendor</var>-<var>os</var></tt>
6594 since this would make our programs incompatible with other
6595 Linux distributions. We also don't use something like
6596 <tt><var>arch</var>-unknown-linux</tt>, since the
6597 <tt>unknown</tt> does not look very good.
6602 <heading>Daemons</heading>
6605 The configuration files <file>/etc/services</file>,
6606 <file>/etc/protocols</file>, and <file>/etc/rpc</file> are managed
6607 by the <prgn>netbase</prgn> package and must not be modified
6612 If a package requires a new entry in one of these files, the
6613 maintainer should get in contact with the
6614 <prgn>netbase</prgn> maintainer, who will add the entries
6615 and release a new version of the <prgn>netbase</prgn>
6620 The configuration file <file>/etc/inetd.conf</file> must not be
6621 modified by the package's scripts except via the
6622 <prgn>update-inetd</prgn> script or the
6623 <file>DebianNet.pm</file> Perl module. See their documentation
6624 for details on how to add entries.
6628 If a package wants to install an example entry into
6629 <file>/etc/inetd.conf</file>, the entry must be preceded with
6630 exactly one hash character (<tt>#</tt>). Such lines are
6631 treated as "commented out by user" by the
6632 <prgn>update-inetd</prgn> script and are not changed or
6633 activated during package updates.
6638 <heading>Using pseudo-ttys and modifying wtmp, utmp and
6642 Some programs need to create pseudo-ttys. This should be done
6643 using Unix98 ptys if the C library supports it. The resulting
6644 program must not be installed setuid root, unless that
6645 is required for other functionality.
6649 The files <file>/var/run/utmp</file>, <file>/var/log/wtmp</file> and
6650 <file>/var/log/lastlog</file> must be installed writeable by
6651 group <tt>utmp</tt>. Programs which need to modify those
6652 files must be installed setgid <tt>utmp</tt>.
6657 <heading>Editors and pagers</heading>
6660 Some programs have the ability to launch an editor or pager
6661 program to edit or display a text document. Since there are
6662 lots of different editors and pagers available in the Debian
6663 distribution, the system administrator and each user should
6664 have the possibility to choose his/her preferred editor and
6669 In addition, every program should choose a good default
6670 editor/pager if none is selected by the user or system
6675 Thus, every program that launches an editor or pager must
6676 use the EDITOR or PAGER environment variable to determine
6677 the editor or pager the user wishes to use. If these
6678 variables are not set, the programs <file>/usr/bin/editor</file>
6679 and <file>/usr/bin/pager</file> should be used, respectively.
6683 These two files are managed through the <prgn>dpkg</prgn>
6684 "alternatives" mechanism. Thus every package providing an
6685 editor or pager must call the
6686 <prgn>update-alternatives</prgn> script to register these
6691 If it is very hard to adapt a program to make use of the
6692 EDITOR or PAGER variables, that program may be configured to
6693 use <file>/usr/bin/sensible-editor</file> and
6694 <file>/usr/bin/sensible-pager</file> as the editor or pager
6695 program respectively. These are two scripts provided in the
6696 Debian base system that check the EDITOR and PAGER variables
6697 and launch the appropriate program, and fall back to
6698 <file>/usr/bin/editor</file> and <file>/usr/bin/pager</file> if the
6699 variable is not set.
6703 A program may also use the VISUAL environment variable to
6704 determine the user's choice of editor. If it exists, it
6705 should take precedence over EDITOR. This is in fact what
6706 <file>/usr/bin/sensible-editor</file> does.
6710 It is not required for a package to depend on
6711 <tt>editor</tt> and <tt>pager</tt>, nor is it required for a
6712 package to provide such virtual packages.<footnote>
6714 The Debian base system already provides an editor and a
6721 <sect id="web-appl">
6722 <heading>Web servers and applications</heading>
6725 This section describes the locations and URLs that should
6726 be used by all web servers and web applications in the
6734 Cgi-bin executable files are installed in the
6736 <example compact="compact">
6737 /usr/lib/cgi-bin/<var>cgi-bin-name</var>
6739 and should be referred to as
6740 <example compact="compact">
6741 http://localhost/cgi-bin/<var>cgi-bin-name</var>
6746 <item><p>Access to HTML documents</p>
6749 HTML documents for a package are stored in
6750 <file>/usr/share/doc/<var>package</var></file>
6751 and can be referred to as
6752 <example compact="compact">
6753 http://localhost/doc/<var>package</var>/<var>filename</var>
6757 The web server should restrict access to the document
6758 tree so that only clients on the same host can read
6759 the documents. If the web server does not support such
6760 access controls, then it should not provide access at
6761 all, or ask about providing access during installation.
6765 <item><p>Web Document Root</p>
6768 Web Applications should try to avoid storing files in
6769 the Web Document Root. Instead they should use the
6770 /usr/share/doc/<var>package</var> directory for
6771 documents and register the Web Application via the
6772 menu package. If access to the web document root is
6773 unavoidable then use
6774 <example compact="compact">
6777 as the Document Root. This might be just a symbolic
6778 link to the location where the system administrator
6779 has put the real document root.
6783 </enumlist></p></sect>
6786 <sect id="mail-transport-agents">
6787 <heading>Mail transport, delivery and user agents</heading>
6790 Debian packages which process electronic mail, whether mail
6791 user agents (MUAs) or mail transport agents (MTAs), must
6792 ensure that they are compatible with the configuration
6793 decisions below. Failure to do this may result in lost
6794 mail, broken <tt>From:</tt> lines, and other serious brain
6799 The mail spool is <file>/var/mail</file> and the interface to
6800 send a mail message is <file>/usr/sbin/sendmail</file> (as per
6801 the FHS). On older systems, the mail spool may be
6802 physically located in <file>/var/spool/mail</file>, but all
6803 access to the mail spool should be via the
6804 <file>/var/mail</file> symlink. The mail spool is part of the
6805 base system and not part of the MTA package.
6809 All Debian MUAs, MTAs, MDAs and other mailbox accessing
6810 programs (such as IMAP daemons) must lock the mailbox in an
6811 NFS-safe way. This means that <tt>fcntl()</tt> locking must
6812 be combined with dot locking. To avoid deadlocks, a program
6813 should use <tt>fcntl()</tt> first and dot locking after
6814 this, or alternatively implement the two locking methods in
6815 a non blocking way<footnote>
6817 If it is not possible to establish both locks, the
6818 system shouldn't wait for the second lock to be
6819 established, but remove the first lock, wait a (random)
6820 time, and start over locking again.
6822 </footnote>. Using the functions <tt>maillock</tt> and
6823 <tt>mailunlock</tt> provided by the
6824 <tt>liblockfile*</tt><footnote>
6826 You will need to depend on <tt>liblockfile1
6827 (>>1.01)</tt> to use these functions.
6829 </footnote> packages is the recommended way to realize this.
6833 Mailboxes are generally mode 660
6834 <tt><var>user</var>.mail</tt> unless the system
6835 administrator has chosen otherwise. A MUA may remove a
6836 mailbox (unless it has nonstandard permissions) in which
6837 case the MTA or another MUA must recreate it if needed.
6838 Mailboxes must be writable by group mail.
6842 The mail spool is 2775 <tt>root.mail</tt>, and MUAs should
6843 be setgid mail to do the locking mentioned above (and
6844 must obviously avoid accessing other users' mailboxes
6845 using this privilege).</p>
6848 <file>/etc/aliases</file> is the source file for the system mail
6849 aliases (e.g., postmaster, usenet, etc.), it is the one
6850 which the sysadmin and <prgn>postinst</prgn> scripts may
6851 edit. After <file>/etc/aliases</file> is edited the program or
6852 human editing it must call <prgn>newaliases</prgn>. All MTA
6853 packages must come with a <prgn>newaliases</prgn> program,
6854 even if it does nothing, but older MTA packages did not do
6855 this so programs should not fail if <prgn>newaliases</prgn>
6856 cannot be found. Note that because of this, all MTA
6857 packages must have <tt>Provides</tt>, <tt>Conflicts</tt> and
6858 <tt>Replaces: mail-transport-agent</tt> control file
6863 The convention of writing <tt>forward to
6864 <var>address</var></tt> in the mailbox itself is not
6865 supported. Use a <tt>.forward</tt> file instead.</p>
6868 The <prgn>rmail</prgn> program used by UUCP
6869 for incoming mail should be <file>/usr/sbin/rmail</file>.
6870 Likewise, <prgn>rsmtp</prgn>, for receiving
6871 batch-SMTP-over-UUCP, should be <file>/usr/sbin/rsmtp</file> if it
6875 If your package needs to know what hostname to use on (for
6876 example) outgoing news and mail messages which are generated
6877 locally, you should use the file <file>/etc/mailname</file>. It
6878 will contain the portion after the username and <tt>@</tt>
6879 (at) sign for email addresses of users on the machine
6880 (followed by a newline).
6884 Such package should check for the existence of this file
6885 when it is being configured. If it exists, it should be
6886 used without comment, although an MTA's configuration script
6887 may wish to prompt the user even if it finds that this file
6888 exists. If the file does not exist, the package should
6889 prompt the user for the value (preferably using
6890 <prgn>debconf</prgn>) and store it in <file>/etc/mailname</file>
6891 as well as using it in the package's configuration. The
6892 prompt should make it clear that the name will not just be
6893 used by that package. For example, in this situation the
6894 <tt>inn</tt> package could say something like:
6895 <example compact="compact">
6896 Please enter the "mail name" of your system. This is the
6897 hostname portion of the address to be shown on outgoing
6898 news and mail messages. The default is
6899 <var>syshostname</var>, your system's host name. Mail
6900 name ["<var>syshostname</var>"]:
6902 where <var>syshostname</var> is the output of <tt>hostname
6908 <heading>News system configuration</heading>
6911 All the configuration files related to the NNTP (news)
6912 servers and clients should be located under
6913 <file>/etc/news</file>.</p>
6916 There are some configuration issues that apply to a number
6917 of news clients and server packages on the machine. These
6921 <tag><file>/etc/news/organization</file></tag>
6922 <item><p>A string which should appear as the
6923 organization header for all messages posted
6924 by NNTP clients on the machine</p></item>
6926 <tag><file>/etc/news/server</file></tag>
6927 <item><p>Contains the FQDN of the upstream NNTP
6928 server, or localhost if the local machine is
6929 an NNTP server.</p></item>
6932 Other global files may be added as required for cross-package news
6933 configuration.</p></sect>
6937 <heading>Programs for the X Window System</heading>
6940 <heading>Providing X support and package priorities</heading>
6943 Programs that can be configured with support for the X
6944 Window System must be configured to do so and must declare
6945 any package dependencies necessary to satisfy their
6946 runtime requirements when using the X Window System. If
6947 such a package is of higher priority than the X packages
6948 on which it depends, it is required that either the
6949 X-specific components be split into a separate package, or
6950 that an alternative version of the package, which includes
6951 X support, be provided, or that the package's priority be
6957 <heading>Packages providing an X server</heading>
6960 Packages that provide an X server that, directly or
6961 indirectly, communicates with real input and display
6962 hardware should declare in their control data that they
6963 provide the virtual package <tt>xserver</tt>.<footnote>
6965 This implements current practice, and provides an
6966 actual policy for usage of the <tt>xserver</tt>
6967 virtual package which appears in the virtual packages
6968 list. In a nutshell, X servers that interface
6969 directly with the display and input hardware or via
6970 another subsystem (e.g., GGI) should provide
6971 <tt>xserver</tt>. Things like <tt>Xvfb</tt>,
6972 <tt>Xnest</tt>, and <tt>Xprt</tt> should not.
6979 <heading>Packages providing a terminal emulator</heading>
6982 Packages that provide a terminal emulator for the X Window
6983 System which meet the criteria listed below should declare
6984 in their control data that they provide the virtual
6985 package <tt>x-terminal-emulator</tt>. They should also
6986 register themselves as an alternative for
6987 <file>/usr/bin/x-terminal-emulator</file>, with a priority of
6992 To be an <tt>x-terminal-emulator</tt>, a program must:
6993 <list compact="compact">
6995 Be able to emulate a DEC VT100 terminal, or a
6996 compatible terminal.
7000 Support the command-line option <tt>-e
7001 <var>command</var></tt>, which creates a new
7002 terminal window<footnote>
7004 "New terminal window" does not necessarily mean
7005 a new top-level X window directly parented by
7006 the window manager; it could, if the terminal
7007 emulator application were so coded, be a new
7008 "view" in a multiple-document interface (MDI).
7011 and runs the specified <var>command</var>.
7015 Support the command-line option <tt>-T
7016 <var>title</var></tt>, which creates a new terminal
7017 window with the window title <var>title</var>.
7024 <heading>Packages providing a window manager</heading>
7027 Packages that provide a window manager should declare in
7028 their control data that they provide the virtual package
7029 <tt>x-window-manager</tt>. They should also register
7030 themselves as an alternative for
7031 <file>/usr/bin/x-window-manager</file>, with a priority
7032 calculated as follows:
7033 <list compact="compact">
7034 <item><p>Start with a priority of 20.</p></item>
7038 If the window manager supports the Debian menu
7039 system, add 20 points if this support is available
7040 in the package's default configuration (i.e., no
7041 configuration files belonging to the system or user
7042 have to be edited to activate the feature); if
7043 configuration files must be modified, add only 10
7049 If the window manager complies with <url
7050 id="http://www.freedesktop.org/standards/wm-spec.html"
7051 name="The Window Manager Specification Project">,
7052 written by the <url id="http://www.freedesktop.org"
7053 name="Free Desktop Group">, add 20 points.
7059 If the window manager permits the X session to be
7060 restarted using a <em>different</em> window manager
7061 (without killing the X server) in its default
7062 configuration, add 10 points; otherwise add none.
7070 <heading>Packages providing fonts</heading>
7073 Packages that provide fonts for the X Window
7076 For the purposes of Debian Policy, a "font for the X
7077 Window System" is one which is accessed via X protocol
7078 requests. Fonts for the Linux console, for PostScript
7079 renderers, or any other purpose, do not fit this
7080 definition. Any tool which makes such fonts available
7081 to the X Window System, however, must abide by this
7085 must do a number of things to ensure that they are both
7086 available without modification of the X or font server
7087 configuration, and that they do not corrupt files used by
7088 other font packages to register information about
7093 Fonts of any type supported by the X Window System
7094 must be in a separate binary package from any
7095 executables, libraries, or documentation (except
7096 that specific to the fonts shipped, such as their
7097 license information). If one or more of the fonts
7098 so packaged are necessary for proper operation of
7099 the package with which they are associated the font
7100 package may be Recommended; if the fonts merely
7101 provide an enhancement, a Suggests relationship may
7102 be used. Packages must not Depend on font
7105 This is because the X server may retrieve fonts
7106 from the local filesystem or over the network
7107 from an X font server; the Debian package system
7108 is empowered to deal only with the local
7117 BDF fonts must be converted to PCF fonts with the
7118 <prgn>bdftopcf</prgn> utility (available in the
7119 <tt>xutils</tt> package, <prgn>gzip</prgn>ped, and
7120 placed in a directory that corresponds to their
7122 <list compact="compact">
7124 100 dpi fonts must be placed in
7125 <file>/usr/X11R6/lib/X11/fonts/100dpi/</file>.
7129 75 dpi fonts must be placed in
7130 <file>/usr/X11R6/lib/X11/fonts/75dpi/</file>.
7134 Character-cell fonts, cursor fonts, and other
7135 low-resolution fonts must be placed in
7136 <file>/usr/X11R6/lib/X11/fonts/misc/</file>.
7143 Speedo fonts must be placed in
7144 <file>/usr/X11R6/lib/X11/fonts/Speedo/</file>.
7148 Type 1 fonts must be placed in
7149 <file>/usr/X11R6/lib/X11/fonts/Type1/</file>. If font
7150 metric files are available, they must be placed here
7156 Subdirectories of <file>/usr/X11R6/lib/X11/fonts/</file>
7157 other than those listed above must be neither
7158 created nor used. (The <file>PEX</file>, <file>CID</file>,
7159 and <file>cyrillic</file> directories are excepted for
7160 historical reasons, but installation of files into
7161 these directories remains discouraged.)
7167 Font packages may, instead of placing files directly
7168 in the X font directories listed above, provide
7169 symbolic links in that font directory pointing to
7170 the files' actual location in the filesystem. Such
7171 a location must comply with the FHS.
7177 Font packages should not contain both 75dpi and
7178 100dpi versions of a font. If both are available,
7179 they should be provided in separate binary packages
7180 with <tt>-75dpi</tt> or <tt>-100dpi</tt> appended to
7181 the names of the packages containing the
7182 corresponding fonts.
7188 Fonts destined for the <file>misc</file> subdirectory
7189 should not be included in the same package as 75dpi
7190 or 100dpi fonts; instead, they should be provided in
7191 a separate package with <tt>-misc</tt> appended to
7198 Font packages must not provide the files
7199 <file>fonts.dir</file>, <file>fonts.alias</file>, or
7200 <file>fonts.scale</file> in a font directory:
7203 <file>fonts.dir</file> files must not be provided at all.
7208 <file>fonts.alias</file> and <file>fonts.scale</file>
7209 files, if needed, should be provided in the
7211 <file>/etc/X11/fonts/<var>fontdir</var>/<var>package</var>.<var>extension</var></file>,
7212 where <var>fontdir</var> is the name of the
7214 <file>/usr/X11R6/lib/X11/fonts/</file> where the
7215 package's corresponding fonts are stored
7216 (e.g., <tt>75dpi</tt> or <tt>misc</tt>),
7217 <var>package</var> is the name of the package
7218 that provides these fonts, and
7219 <var>extension</var> is either <tt>scale</tt>
7220 or <tt>alias</tt>, whichever corresponds to
7230 Font packages must declare a dependency on
7231 <tt>xutils (>> 4.0.3)</tt> in their control
7238 Font packages that provide one or more
7239 <file>fonts.scale</file> files as described above must
7240 invoke <prgn>update-fonts-scale</prgn> on each
7241 directory into which they installed fonts
7242 <em>before</em> invoking
7243 <prgn>update-fonts-dir</prgn> on that directory.
7244 This invocation must occur in both the
7245 <prgn>postinst</prgn> (for all arguments) and
7246 <prgn>postrm</prgn> (for all arguments except
7247 <tt>upgrade</tt>) scripts.
7253 Font packages that provide one or more
7254 <file>fonts.alias</file> files as described above must
7255 invoke <prgn>update-fonts-alias</prgn> on each
7256 directory into which they installed fonts. This
7257 invocation must occur in both the
7258 <prgn>postinst</prgn> (for all arguments) and
7259 <prgn>postrm</prgn> (for all arguments except
7260 <tt>upgrade</tt>) scripts.
7266 Font packages must invoke
7267 <prgn>update-fonts-dir</prgn> on each directory into
7268 which they installed fonts. This invocation must
7269 occur in both the <prgn>postinst</prgn> (for all
7270 arguments) and <prgn>postrm</prgn> (for all
7271 arguments except <tt>upgrade</tt>) scripts.
7277 Font packages must not provide alias names for the
7278 fonts they include which collide with alias names
7279 already in use by fonts already packaged.
7285 Font packages must not provide fonts with the same
7286 XLFD registry name as another font already packaged.
7294 <heading>Application defaults files</heading>
7297 Application defaults files must be installed in the
7298 directory <file>/etc/X11/app-defaults/</file> (use of a
7299 localized subdirectory of <file>/etc/X11/</file> as described
7300 in the <em>X Toolkit Intrinsics - C Language
7301 Interface</em> manual is also permitted). They must be
7302 registered as <tt>conffile</tt>s or handled as
7303 configuration files. Packages must not provide the
7304 directory <file>/usr/X11R6/lib/X11/app-defaults/</file>.
7308 Customization of programs' X resources may also be
7309 supported with the provision of a file with the same name
7310 as that of the package placed in the
7311 <file>/etc/X11/Xresources/</file> directory, which must
7312 registered as a <tt>conffile</tt> or handled as a
7313 configuration file.<footnote>
7315 Note that this mechanism is not the same as using
7316 app-defaults; app-defaults are tied to the client
7317 binary on the local filesystem, whereas X resources
7318 are stored in the X server and affect all connecting
7322 <em>Important:</em> packages that install files into the
7323 <file>/etc/X11/Xresources/</file> directory must conflict with
7324 <tt>xbase (<< 3.3.2.3a-2)</tt>; if this is not done
7325 it is possible for the installing package to destroy a
7326 previously-existing <file>/etc/X11/Xresources</file> file
7327 which had been customized by the system administrator.
7332 <heading>Installation directory issues</heading>
7335 Packages using the X Window System should not be
7336 configured to install files under the <file>/usr/X11R6/</file>
7337 directory unless they use <prgn>imake</prgn>. The
7338 <file>/usr/X11R6/</file> directory hierarchy should be
7339 regarded as deprecated for all packages except the X
7340 Window System itself, and those which use the
7341 <prgn>imake</prgn> program it provides, in which case the
7342 packages may transition out of the <file>/usr/X11R6/</file>
7343 directory at the maintainer's discretion.<footnote>
7345 <prgn>Imake</prgn>-using programs are exempt because,
7346 as long as they are written correctly, the pathnames
7347 they use to locate resources and install themselves
7348 are derived wholly from the X Window System
7349 configuration. Thus, in the event that the X Window
7350 System moves to <file>/usr/X11R7/</file>,
7351 <file>/usr/X12/</file>, or just plain <file>/usr/</file>, all
7352 that is required for these programs is a recompile
7353 against the corresponding X Window System library
7354 development packages.
7357 Programs that use GNU <prgn>autoconf</prgn> and
7358 <prgn>automake</prgn> are usually easily configured at
7359 compile time to use <file>/usr/</file> instead of
7360 <file>/usr/X11R6/</file>, and this should be done whenever
7361 possible. Configuration files for window managers and
7362 display managers should be placed in a subdirectory of
7363 <file>/etc/X11/</file> corresponding to the package name due
7364 to these programs' tight integration with the mechanisms
7365 of the X Window System. Application-level programs should
7366 use the <file>/etc/</file> directory unless otherwise mandated
7367 by policy. The installation of files into subdirectories
7368 of <file>/usr/X11R6/include/X11/</file> and
7369 <file>/usr/X11R6/lib/X11/</file> is permitted but discouraged;
7370 package maintainers should determine if subdirectories of
7371 <file>/usr/lib/</file> and <file>/usr/share/</file> can be used
7372 instead. (The use of symbolic links from the
7373 <file>X11R6</file> directories to other FHS-compliant
7374 locations is encouraged if the program is not easily
7375 configured to look elsewhere for its files.) Packages
7376 must not provide or install files into the directories
7377 <file>/usr/bin/X11/</file>, <file>/usr/include/X11/</file> or
7378 <file>/usr/lib/X11/</file>. Files within a package should,
7379 however, make reference to these directories, rather than
7380 their <tt>X11R6</tt>-named counterparts
7381 <file>/usr/X11R6/bin/</file>, <file>/usr/X11R6/include/X11/</file>
7382 and <file>/usr/X11R6/lib/X11/</file>, if the resources being
7383 referred to have not been moved to other FHS-compliant
7389 <heading>The OSF/Motif and OpenMotif libraries</heading>
7392 <em>Programs that require the non-DFSG-compliant OSF/Motif or
7393 OpenMotif libraries</em><footnote>
7395 OSF/Motif and OpenMotif are collectively referred to as
7396 "Motif" in this policy document.
7399 should be compiled against and tested with LessTif (a free
7400 re-implementation of Motif) instead. If the maintainer
7401 judges that the program or programs do not work
7402 sufficiently well with LessTif to be distributed and
7403 supported, but do so when compiled against Motif, then two
7404 versions of the package should be created; one linked
7405 statically against Motif and with <tt>-smotif</tt>
7406 appended to the package name, and one linked dynamically
7407 against Motif and with <tt>-dmotif</tt> appended to the
7408 package name. Both Motif-linked versions are dependent
7409 upon non-DFSG-compliant software and thus cannot be
7410 uploaded to the <em>main</em> distribution; if the
7411 software is itself DFSG-compliant it may be uploaded to
7412 the <em>contrib</em> distribution. While known existing
7413 versions of Motif permit unlimited redistribution of
7414 binaries linked against the library (whether statically or
7415 dynamically), it is the package maintainer's
7416 responsibility to determine whether this is permitted by
7417 the license of the copy of Motif in his or her possession.
7423 <heading>Perl programs and modules</heading>
7425 Perl programs and modules should follow the current Perl
7426 policy as defined in the file found on
7427 <ftpsite>ftp.debian.org</ftpsite> in
7428 <ftppath>/debian/doc/package-developer/perl-policy.txt.gz</ftppath>
7429 or your local mirror. In addition, it is included in the
7430 <tt>debian-policy</tt> package.
7435 <heading>Emacs lisp programs</heading>
7438 Please refer to the "Debian Emacs Policy" (documented in
7439 <file>debian-emacs-policy.gz</file> of the
7440 <prgn>emacsen-common</prgn> package) for details of how to
7441 package emacs lisp programs.
7446 <heading>Games</heading>
7449 The permissions on <file>/var/games</file> are mode 755, owner
7450 <tt>root</tt> and group <tt>root</tt>.
7454 Each game decides on its own security policy.</p>
7457 Games which require protected, privileged access to
7458 high-score files, savegames, etc., may be made
7459 set-<em>group</em>-id (mode 2755) and owned by
7460 <tt>root.games</tt>, and use files and directories with
7461 appropriate permissions (770 <tt>root.games</tt>, for
7462 example). They must not be made
7463 set-<em>user</em>-id, as this causes security problems. (If
7464 an attacker can subvert any set-user-id game they can
7465 overwrite the executable of any other, causing other players
7466 of these games to run a Trojan horse program. With a
7467 set-group-id game the attacker only gets access to less
7468 important game data, and if they can get at the other
7469 players' accounts at all it will take considerably more
7473 Some packages, for example some fortune cookie programs, are
7474 configured by the upstream authors to install with their
7475 data files or other static information made unreadable so
7476 that they can only be accessed through set-id programs
7477 provided. You should not do this in a Debian package: anyone can
7478 download the <file>.deb</file> file and read the data from it,
7479 so there is no point making the files unreadable. Not
7480 making the files unreadable also means that you don't have
7481 to make so many programs set-id, which reduces the risk of a
7485 As described in the FHS, binaries of games should be
7486 installed in the directory <file>/usr/games</file>. This also
7487 applies to games that use the X Window System. Manual pages
7488 for games (X and non-X games) should be installed in
7489 <file>/usr/share/man/man6</file>.</p>
7493 <chapt id="docs"><heading>Documentation</heading>
7497 <heading>Manual pages</heading>
7500 You should install manual pages in <prgn>nroff</prgn> source
7501 form, in appropriate places under <file>/usr/share/man</file>. You
7502 should only use sections 1 to 9 (see the FHS for more
7503 details). You must not install a preformatted "cat
7507 Each program, utility, and function should have an
7508 associated manpage included in the same package. It is
7509 suggested that all configuration files also have a manual
7510 page included as well.
7514 There should be a manual page at for every program at the
7515 very least, and possibly one for every configuration file,
7516 protocol, utility, and function. If no manual page is
7517 available, this is considered as a bug and should be
7518 reported to the Debian Bug Tracking System (the maintainer
7519 of the package is allowed to write this bug report
7520 themselves, if they so desire). Do not close the bug report
7521 until a proper manpage is available.<footnote>
7523 It is not very hard to write a man page. See the
7524 <url id="http://www.schweikhardt.net/man_page_howto.html"
7525 name="Man-Page-HOWTO">,
7526 <manref name="man" section="7">, the examples
7527 created by <prgn>debmake</prgn> or <prgn>dh_make</prgn>,
7528 the helper programs <prgn>help2man</prgn>, or the
7529 directory <file>/usr/share/doc/man-db/examples</file>.
7535 You may forward a complaint about a missing manpage to the
7536 upstream authors, and mark the bug as forwarded in the
7537 Debian bug tracking system. Even though the GNU Project do
7538 not in general consider the lack of a manpage to be a bug,
7539 we do; if they tell you that they don't consider it a bug
7540 you should leave the bug in our bug tracking system open
7545 Manual pages should be installed compressed using <tt>gzip -9</tt>.
7549 If one manpage needs to be accessible via several names it
7550 is better to use a symbolic link than the <file>.so</file>
7551 feature, but there is no need to fiddle with the relevant
7552 parts of the upstream source to change from <file>.so</file> to
7553 symlinks: don't do it unless it's easy. You should not
7554 create hard links in the manual page directories, nor put
7555 absolute filenames in <file>.so</file> directives. The filename
7556 in a <file>.so</file> in a manpage should be relative to the
7557 base of the manpage tree (usually
7558 <file>/usr/share/man</file>). If you do not create any links
7559 (whether symlinks, hard links, or <tt>.so</tt> directives)
7560 in the filesystem to the alternate names of the manpage,
7561 then you should not rely on <prgn>man</prgn> finding your
7562 manpage under those names based solely on the information in
7563 the manpage's header.<footnote>
7565 Supporting this in <prgn>man</prgn> often requires
7566 unreasonable processing time to find a manual page or to
7567 report that none exists, and moves knowledge into man's
7568 database that would be better left in the filesystem.
7569 This support is therefore deprecated and will cease to
7570 be present in the future.
7577 <heading>Info documents</heading>
7580 Info documents should be installed in <file>/usr/share/info</file>.
7581 They should be compressed with <tt>gzip -9</tt>.
7585 Your package should call <prgn>install-info</prgn> to update
7586 the Info <file>dir</file> file in its <prgn>postinst</prgn>
7587 script when called with a <tt>configure</tt> argument, for
7589 <example compact="compact">
7590 install-info --quiet --section Development Development \
7591 /usr/share/info/foobar.info
7595 It is a good idea to specify a section for the location of
7596 your program; this is done with the <tt>--section</tt>
7597 switch. To determine which section to use, you should look
7598 at <file>/usr/share/info/dir</file> on your system and choose the most
7599 relevant (or create a new section if none of the current
7600 sections are relevant). Note that the <tt>--section</tt>
7601 flag takes two arguments; the first is a regular expression
7602 to match (case-insensitively) against an existing section,
7603 the second is used when creating a new one.</p>
7606 You should remove the entries in the <prgn>prerm</prgn>
7607 script when called with a <tt>remove</tt> argument:
7608 <example compact="compact">
7609 install-info --quiet --remove /usr/share/info/foobar.info
7613 If <prgn>install-info</prgn> cannot find a description entry
7614 in the Info file you must supply one. See <manref
7615 name="install-info" section="8"> for details.</p>
7619 <heading>Additional documentation</heading>
7622 Any additional documentation that comes with the package may
7623 be installed at the discretion of the package maintainer.
7624 Text documentation should be installed in the directory
7625 <file>/usr/share/doc/<var>package</var></file>, where
7626 <var>package</var> is the name of the package, and
7627 compressed with <tt>gzip -9</tt> unless it is small.
7631 If a package comes with large amounts of documentation which
7632 many users of the package will not require you should create
7633 a separate binary package to contain it, so that it does not
7634 take up disk space on the machines of users who do not need
7635 or want it installed.</p>
7638 It is often a good idea to put text information files
7639 (<file>README</file>s, changelogs, and so forth) that come with
7640 the source package in <file>/usr/share/doc/<var>package</var></file>
7641 in the binary package. However, you don't need to install
7642 the instructions for building and installing the package, of
7646 Packages must not require the existance of any files in
7647 <file>/usr/share/doc/</file> in order to function
7650 The system administrator should be able to
7651 delete files in <file>/usr/share/doc/</file> without causing
7652 any programs to break.
7655 Any files that are referenced by programs but are also
7656 useful as standalone documentation should be installed under
7657 <file>/usr/share/<var>package</var>/</file> with symbolic links from
7658 <file>/usr/share/doc/<var>package</var></file>.
7662 <file>/usr/share/doc/<var>package</var></file> may be a symbolic
7663 link to another directory in <file>/usr/share/doc</file> only if
7664 the two packages both come from the same source and the
7665 first package Depends on the second.
7669 Former Debian releases placed all additional documentation
7670 in <file>/usr/doc/<var>package</var></file>. This has been
7671 changed to <file>/usr/share/doc/<var>package</var></file>,
7672 and packages must not put documentation in the directory
7673 <file>/usr/doc/<var>package</var></file>. <footnote>
7674 <p>At this phase of the transition, we no longer require a
7675 symbolic link in <file>/usr/doc/</file>. At a later point,
7676 policy shall change to make the symbolic links a bug.</p>
7682 <heading>Preferred documentation formats</heading>
7685 The unification of Debian documentation is being carried out
7689 If your package comes with extensive documentation in a
7690 markup format that can be converted to various other formats
7691 you should if possible ship HTML versions in a binary
7692 package, in the directory
7693 <file>/usr/share/doc/<var>appropriate-package</var></file> or
7694 its subdirectories.<footnote>
7696 The rationale: The important thing here is that HTML
7697 docs should be available in <em>some</em> package, not
7698 necessarily in the main binary package.
7704 Other formats such as PostScript may be provided at the
7705 package maintainer's discretion.
7709 <sect id="copyrightfile">
7710 <heading>Copyright information</heading>
7713 Every package must be accompanied by a verbatim copy of its
7714 copyright and distribution license in the file
7715 <file>/usr/share/doc/<var>package</var>/copyright</file>. This
7716 file must neither be compressed nor be a symbolic link.
7720 In addition, the copyright file must say where the upstream
7721 sources (if any) were obtained. It should name the original
7722 authors of the package and the Debian maintainer(s) who were
7723 involved with its creation.</p>
7726 A copy of the file which will be installed in
7727 <file>/usr/share/doc/<var>package</var>/copyright</file> should
7728 be in <file>debian/copyright</file> in the source package.
7732 <file>/usr/share/doc/<var>package</var></file> may be a symbolic
7733 link to another directory in <file>/usr/share/doc</file> only if
7734 the two packages both come from the same source and the
7735 first package Depends on the second. These rules are
7736 important because copyrights must be extractable by
7741 Packages distributed under the UCB BSD license, the Artistic
7742 license, the GNU GPL, and the GNU LGPL should refer to the
7743 files <file>/usr/share/common-licenses/BSD</file>,
7744 <file>/usr/share/common-licenses/Artistic</file>,
7745 <file>/usr/share/common-licenses/GPL</file>, and
7746 <file>/usr/share/common-licenses/LGPL</file> respectively,
7747 rather than quoting them in the copyright file.
7751 You should not use the copyright file as a general <file>README</file>
7752 file. If your package has such a file it should be
7753 installed in <file>/usr/share/doc/<var>package</var>/README</file> or
7754 <file>README.Debian</file> or some other appropriate place.</p>
7758 <heading>Examples</heading>
7761 Any examples (configurations, source files, whatever),
7762 should be installed in a directory
7763 <file>/usr/share/doc/<var>package</var>/examples</file>. These
7764 files should not be referenced by any program: they're there
7765 for the benefit of the system administrator and users as
7766 documentation only. Architecture-specific example files
7767 should be installed in a directory
7768 <file>/usr/lib/<var>package</var>/examples</file> with symbolic
7770 <file>/usr/share/doc/<var>package</var>/examples</file>, or the
7771 latter directory itself may be a symbolic link to the
7776 <sect id="changelogs">
7777 <heading>Changelog files</heading>
7780 The Debian changelog file (<file>debian/changelog</file>) should
7781 explain briefly what modifications were made in the Debian version
7782 of the package compared to the upstream one. Other changes and
7783 updates to the package should also be documented in this file.
7787 Mistakes in changelogs are usually best rectified by
7788 making a new changelog entry rather than "rewriting history"
7789 by editing old changelog entries.
7793 The format of the <file>debian/changelog</file> file is described
7794 in <ref id="dpkgchangelog">. In non-experimental packages you must
7795 use a format for <file>debian/changelog</file> which is supported
7796 by the most recent released version of <prgn>dpkg</prgn>.<footnote>
7798 If you wish to use an alternative format, you may do so as
7799 long as you include a parser for it in your source package.
7800 The parser must have an API compatible with that expected by
7801 <prgn>dpkg-genchanges</prgn> and <prgn>dpkg-gencontrol</prgn>.
7802 If there is general interest in the new format, you should
7803 contact the <package>dpkg</package> maintainer to have the
7804 parser script for it included in the <prgn>dpkg</prgn>
7805 package. (You will need to agree that the parser and its
7806 manpage may be distributed under the GNU GPL, just as the rest
7807 of <prgn>dpkg</prgn> is.)
7813 Packages that are not Debian-native must contain a
7814 compressed copy of the <file>debian/changelog</file> file from
7815 the Debian source tree in
7816 <file>/usr/share/doc/<var>package</var></file> with the name
7817 <file>changelog.Debian.gz</file>.
7821 If an upstream changelog is available, it should be accessible as
7822 <file>/usr/share/doc/<var>package</var>/changelog.gz</file> in
7823 plain text. If the upstream changelog is distributed in
7824 HTML, it should be made available in that form as
7825 <file>/usr/share/doc/<var>package</var>/changelog.html.gz</file>
7826 and a plain text <file>changelog.gz</file> should be generated
7827 from it using, for example, <tt>lynx -dump -nolist</tt>. If
7828 the upstream changelog files do not already conform to this
7829 naming convention, then this may be achieved either by
7830 renaming the files, or by adding a symbolic link, at the
7831 maintainer's discretion.<footnote>
7833 Rationale: People should not have to look in places for
7834 upstream changelogs merely because they are given
7835 different names or are distributed in HTML format.
7841 All of these files should be installed compressed using
7842 <tt>gzip -9</tt>, as they will become large with time even
7843 if they start out small.
7847 If the package has only one changelog which is used both as
7848 the Debian changelog and the upstream one because there is
7849 no separate upstream maintainer then that changelog should
7850 usually be installed as
7851 <file>/usr/share/doc/<var>package</var>/changelog.gz</file>; if
7852 there is a separate upstream maintainer, but no upstream
7853 changelog, then the Debian changelog should still be called
7854 <file>changelog.Debian.gz</file>.</p>
7859 <appendix id="pkg-scope">
7860 <heading>Introduction and scope of these appendices</heading>
7863 These appendices are taken essentially verbatim from the
7864 now-deprecated Packaging Manual, version 3.2.1.0. They are
7865 the chapters which are likely to be of use to package
7866 maintainers and which have not already been included in the
7867 policy document itself. Most of these sections are very likely
7868 not relevant to policy; they should be treated as
7869 documentation for the packaging system. Please note that these
7870 appendices are included for convenience, and for historical
7871 reasons: they used to be part of policy package, and they have
7872 not yet been incorporated into dpkg documentation. However,
7873 they still have value, and hence they are presented here.
7876 They have not yet been checked to ensure that they are
7877 compatible with the contents of policy, and if there are any
7878 contradictions, the version in the main policy document takes
7879 precedence. The remaining chapters of the old Packaging
7880 Manual have also not been read in detail to ensure that there
7881 are not parts which have been left out. Both of these will be
7886 <prgn>dpkg</prgn> is a suite of programs for creating binary
7887 package files and installing and removing them on Unix
7890 <prgn>dpkg</prgn> is targetted primarily at Debian
7891 GNU/Linux, but may work on or be ported to other
7898 The binary packages are designed for the management of
7899 installed executable programs (usually compiled binaries) and
7900 their associated data, though source code examples and
7901 documentation are provided as part of some packages.</p>
7904 This manual describes the technical aspects of creating Debian
7905 binary packages (<file>.deb</file> files). It documents the
7906 behaviour of the package management programs
7907 <prgn>dpkg</prgn>, <prgn>dselect</prgn> et al. and the way
7908 they interact with packages.</p>
7911 It also documents the interaction between
7912 <prgn>dselect</prgn>'s core and the access method scripts it
7913 uses to actually install the selected packages, and describes
7914 how to create a new access method.</p>
7917 This manual does not go into detail about the options and
7918 usage of the package building and installation tools. It
7919 should therefore be read in conjuction with those programs'
7924 The utility programs which are provided with <prgn>dpkg</prgn>
7925 for managing various system configuration and similar issues,
7926 such as <prgn>update-rc.d</prgn> and
7927 <prgn>install-info</prgn>, are not described in detail here -
7928 please see their manpages.
7932 It does <em>not</em> describe the policy requirements imposed
7933 on Debian packages, such as the permissions on files and
7934 directories, documentation requirements, upload procedure, and
7935 so on. You should see the Debian packaging policy manual for
7936 these details. (Many of them will probably turn out to be
7937 helpful even if you don't plan to upload your package and make
7938 it available as part of the distribution.)
7942 It is assumed that the reader is reasonably familiar with the
7943 <prgn>dpkg</prgn> System Administrators' manual.
7944 Unfortunately this manual does not yet exist.
7948 The Debian version of the FSF's GNU hello program is provided
7949 as an example for people wishing to create Debian
7950 packages. The Debian <prgn>debmake</prgn> package is
7951 recommended as a very helpful tool in creating and maintaining
7952 Debian packages. However, while the tools and examples are
7953 helpful, they do not replace the need to read and follow the
7954 Policy and Programmer's Manual.</p>
7957 <appendix id="pkg-binarypkg"><heading>Binary packages (from old
7962 The binary package has two main sections. The first part
7963 consists of various control information files and scripts used
7964 by <prgn>dpkg</prgn> when installing and removing. See <ref
7965 id="pkg-controlarea">.
7969 The second part is an archive containing the files and
7970 directories to be installed.
7974 In the future binary packages may also contain other
7975 components, such as checksums and digital signatures. The
7976 format for the archive is described in full in the
7977 <file>deb(5)</file> manpage.
7981 <sect id="pkg-bincreating"><heading>Creating package files -
7982 <prgn>dpkg-deb</prgn>
7986 All manipulation of binary package files is done by
7987 <prgn>dpkg-deb</prgn>; it's the only program that has
7988 knowledge of the format. (<prgn>dpkg-deb</prgn> may be
7989 invoked by calling <prgn>dpkg</prgn>, as <prgn>dpkg</prgn>
7990 will spot that the options requested are appropriate to
7991 <prgn>dpkg-deb</prgn> and invoke that instead with the same
7996 In order to create a binary package you must make a
7997 directory tree which contains all the files and directories
7998 you want to have in the filesystem data part of the package.
7999 In Debian-format source packages this directory is usually
8000 <file>debian/tmp</file>, relative to the top of the package's
8005 They should have the locations (relative to the root of the
8006 directory tree you're constructing) ownerships and
8007 permissions which you want them to have on the system when
8012 With current versions of <prgn>dpkg</prgn> the uid/username
8013 and gid/groupname mappings for the users and groups being
8014 used should be the same on the system where the package is
8015 built and the one where it is installed.
8019 You need to add one special directory to the root of the
8020 miniature filesystem tree you're creating:
8021 <prgn>DEBIAN</prgn>. It should contain the control
8022 information files, notably the binary package control file
8023 (see <ref id="pkg-controlfile">).
8027 The <prgn>DEBIAN</prgn> directory will not appear in the
8028 filesystem archive of the package, and so won't be installed
8029 by <prgn>dpkg</prgn> when the package is installed.
8033 When you've prepared the package, you should invoke:
8035 dpkg --build <var>directory</var>
8040 This will build the package in
8041 <file><var>directory</var>.deb</file>. (<prgn>dpkg</prgn> knows
8042 that <tt>--build</tt> is a <prgn>dpkg-deb</prgn> option, so
8043 it invokes <prgn>dpkg-deb</prgn> with the same arguments to
8048 See the manpage <manref name="dpkg-deb" section="8"> for details of how
8049 to examine the contents of this newly-created file. You may find the
8050 output of following commands enlightening:
8052 dpkg-deb --info <var>filename</var>.deb
8053 dpkg-deb --contents <var>filename</var>.deb
8054 dpkg --contents <var>filename</var>.deb
8056 To view the copyright file for a package you could use this command:
8058 dpkg --fsys-tarfile <var>filename</var>.deb | tar xof usr/share/doc/<var>\*</var>copyright | less
8063 <sect id="pkg-controlarea">
8065 Package control information files
8069 The control information portion of a binary package is a
8070 collection of files with names known to <prgn>dpkg</prgn>.
8071 It will treat the contents of these files specially - some
8072 of them contain information used by <prgn>dpkg</prgn> when
8073 installing or removing the package; others are scripts which
8074 the package maintainer wants <prgn>dpkg</prgn> to run.
8078 It is possible to put other files in the package control
8079 area, but this is not generally a good idea (though they
8080 will largely be ignored).
8084 Here is a brief list of the control info files supported by
8085 <prgn>dpkg</prgn> and a summary of what they're used for.
8090 <tag><tt>control</tt>
8094 This is the key description file used by
8095 <prgn>dpkg</prgn>. It specifies the package's name
8096 and version, gives its description for the user,
8097 states its relationships with other packages, and so
8098 forth. See <ref id="pkg-controlfile">.
8102 It is usually generated automatically from information
8103 in the source package by the
8104 <prgn>dpkg-gencontrol</prgn> program, and with
8105 assistance from <prgn>dpkg-shlibdeps</prgn>. See <ref
8106 id="pkg-sourcetools">.</p>
8109 <tag><tt>postinst</tt>, <tt>preinst</tt>, <tt>postrm</tt>,
8115 These are exectuable files (usually scripts) which
8116 <prgn>dpkg</prgn> runs during installation, upgrade
8117 and removal of packages. They allow the package to
8118 deal with matters which are particular to that package
8119 or require more complicated processing than that
8120 provided by <prgn>dpkg</prgn>. Details of when and
8121 how they are called are in <ref
8122 id="maintainerscripts">.
8126 It is very important to make these scripts
8130 That means that if it runs successfully or fails
8131 and then you call it again it doesn't bomb out,
8132 but just ensures that everything is the way it
8135 </footnote> This is so that if an error occurs, the
8136 user interrupts <prgn>dpkg</prgn> or some other
8137 unforeseen circumstance happens you don't leave the
8138 user with a badly-broken package.
8142 The maintainer scripts are guaranteed to run with a
8143 controlling terminal and can interact with the user.
8144 If they need to prompt for passwords, do full-screen
8145 interaction or something similar you should do these
8146 things to and from <file>/dev/tty</file>, since
8147 <prgn>dpkg</prgn> will at some point redirect scripts'
8148 standard input and output so that it can log the
8149 installation process. Likewise, because these scripts
8150 may be executed with standard output redirected into a
8151 pipe for logging purposes, Perl scripts should set
8152 unbuffered output by setting <tt>$|=1</tt> so that the
8153 output is printed immediately rather than being
8158 Each script should return a zero exit status for
8159 success, or a nonzero one for failure.</p>
8162 <tag><tt>conffiles</tt>
8167 This file contains a list of configuration files which
8168 are to be handled automatically by <prgn>dpkg</prgn>
8169 (see <ref id="pkg-conffiles">). Note that not necessarily
8170 every configuration file should be listed here.</p>
8173 <tag><tt>shlibs</tt>
8178 This file contains a list of the shared libraries
8179 supplied by the package, with dependency details for
8180 each. This is used by <prgn>dpkg-shlibdeps</prgn>
8181 when it determines what dependencies are required in a
8182 package control file. The <tt>shlibs</tt> file format
8183 is described on <ref id="shlibs">.
8189 <sect id="pkg-controlfile">
8191 The main control information file: <tt>control</tt>
8194 The most important control information file used by
8195 <prgn>dpkg</prgn> when it installs a package is
8196 <tt>control</tt>. It contains all the package"s "vital
8201 The binary package control files of packages built from
8202 Debian sources are made by a special tool,
8203 <prgn>dpkg-gencontrol</prgn>, which reads
8204 <file>debian/control</file> and <file>debian/changelog</file> to
8205 find the information it needs. See <ref id="pkg-sourcepkg"> for
8210 The fields in binary package control files are:
8211 <list compact="compact">
8213 <p><qref id="pkg-f-Package"><tt>Package</tt></qref> (mandatory)</p>
8216 <p><qref id="versions"><tt>Version</tt></qref> (mandatory)</p>
8218 <item><p><qref id="pkg-f-Architecture"><tt>Architecture</tt></qref>
8222 This field should appear in all packages, though
8223 <prgn>dpkg</prgn> doesn't require it yet so that
8224 old packages can still be installed.
8230 <p><qref id="relationships"><tt>Depends</tt>,
8231 <tt>Provides</tt> et al.</qref></p>
8234 <p><qref id="pkg-f-Essential"><tt>Essential</tt></qref></p>
8237 <p><qref id="pkg-f-Maintainer"><tt>Maintainer</tt></qref></p>
8240 <p><qref id="pkg-f-classification"><tt>Section</tt>,
8241 <tt>Priority</tt></qref></p>
8244 <p><qref id="pkg-f-Source"><tt>Source</tt></qref></p>
8247 <p><qref id="descriptions"><tt>Description</tt></qref></p>
8251 <qref id="pkg-f-Installed-Size"><tt>Installed-Size</tt></qref>
8257 A description of the syntax of control files and the purpose
8258 of these fields is available in <ref id="pkg-controlfields">.
8263 <heading>Time Stamps</heading>
8265 Maintainers are encouraged to preserve the modification
8266 times of the upstream source files in a package, as far as
8267 is reasonably possible.
8270 The rationale is that there is some information conveyed
8271 by knowing the age of the file, for example, you could
8272 recognize that some documentation is very old by looking
8273 at the modification time, so it would be nice if the
8274 modification time of the upstream source would be
8282 <appendix id="pkg-sourcepkg">
8283 <heading>Source packages (from old Packaging Manual) </heading>
8286 The Debian binary packages in the distribution are generated
8287 from Debian sources, which are in a special format to assist
8288 the easy and automatic building of binaries.
8292 There was a previous version of the Debian source format,
8293 which is now being phased out. Instructions for converting an
8294 old-style package are given in the Debian policy manual.
8297 <sect id="pkg-sourcetools">
8298 <heading>Tools for processing source packages</heading>
8301 Various tools are provided for manipulating source packages;
8302 they pack and unpack sources and help build of binary
8303 packages and help manage the distribution of new versions.
8307 They are introduced and typical uses described here; see
8308 <manref name="dpkg-source" section="1"> for full
8309 documentation about their arguments and operation.
8313 For examples of how to construct a Debian source package,
8314 and how to use those utilities that are used by Debian
8315 source packages, please see the <prgn>hello</prgn> example
8321 <prgn>dpkg-source</prgn> - packs and unpacks Debian source
8326 This program is frequently used by hand, and is also
8327 called from package-independent automated building scripts
8328 such as <prgn>dpkg-buildpackage</prgn>.
8332 To unpack a package it is typically invoked with
8334 dpkg-source -x <var>.../path/to/filename</var>.dsc
8339 with the <file><var>filename</var>.tar.gz</file> and
8340 <file><var>filename</var>.diff.gz</file> (if applicable) in
8341 the same directory. It unpacks into
8342 <file><var>package</var>-<var>version</var></file>, and if
8344 <file><var>package</var>-<var>version</var>.orig</file>, in
8345 the current directory.
8349 To create a packed source archive it is typically invoked:
8351 dpkg-source -b <var>package</var>-<var>version</var>
8356 This will create the <file>.dsc</file>, <file>.tar.gz</file> and
8357 <file>.diff.gz</file> (if appropriate) in the current
8358 directory. <prgn>dpkg-source</prgn> does not clean the
8359 source tree first - this must be done separately if it is
8364 See also <ref id="pkg-sourcearchives">.</p>
8370 <prgn>dpkg-buildpackage</prgn> - overall package-building
8375 <prgn>dpkg-buildpackage</prgn> is a script which invokes
8376 <prgn>dpkg-source</prgn>, the <file>debian/rules</file>
8377 targets <tt>clean</tt>, <tt>build</tt> and
8378 <tt>binary</tt>, <prgn>dpkg-genchanges</prgn> and
8379 <prgn>pgp</prgn> to build a signed source and binary
8384 It is usually invoked by hand from the top level of the
8385 built or unbuilt source directory. It may be invoked with
8386 no arguments; useful arguments include:
8387 <taglist compact="compact">
8388 <tag><tt>-uc</tt>, <tt>-us</tt></tag>
8391 Do not PGP-sign the <tt>.changes</tt> file or the
8392 source package <tt>.dsc</tt> file, respectively.</p>
8394 <tag><tt>-p<var>pgp-command</var></tt></tag>
8397 Invoke <var>pgp-command</var> instead of finding
8398 <tt>pgp</tt> on the <prgn>PATH</prgn>.
8399 <var>pgp-command</var> must behave just like
8400 <prgn>pgp</prgn>.</p>
8402 <tag><tt>-r<var>root-command</var></tt></tag>
8405 When root privilege is required, invoke the command
8406 <var>root-command</var>. <var>root-command</var>
8407 should invoke its first argument as a command, from
8408 the <prgn>PATH</prgn> if necessary, and pass its
8409 second and subsequent arguments to the command it
8410 calls. If no <var>root-command</var> is supplied
8411 then <var>dpkg-buildpackage</var> will take no
8412 special action to gain root privilege, so that for
8413 most packages it will have to be invoked as root to
8416 <tag><tt>-b</tt>, <tt>-B</tt></tag>
8419 Two types of binary-only build and upload - see
8420 <manref name="dpkg-source" section="1">.
8429 <prgn>dpkg-gencontrol</prgn> - generates binary package
8434 This program is usually called from <file>debian/rules</file>
8435 (see <ref id="pkg-sourcetree">) in the top level of the source
8440 This is usually done just before the files and directories in the
8441 temporary directory tree where the package is being built have their
8442 permissions and ownerships set and the package is constructed using
8443 <prgn>dpkg-deb/</prgn>
8446 This is so that the control file which is produced has
8447 the right permissions
8453 <prgn>dpkg-gencontrol</prgn> must be called after all the
8454 files which are to go into the package have been placed in
8455 the temporary build directory, so that its calculation of
8456 the installed size of a package is correct.
8460 It is also necessary for <prgn>dpkg-gencontrol</prgn> to
8461 be run after <prgn>dpkg-shlibdeps</prgn> so that the
8462 variable substitutions created by
8463 <prgn>dpkg-shlibdeps</prgn> in <file>debian/substvars</file>
8468 For a package which generates only one binary package, and
8469 which builds it in <file>debian/tmp</file> relative to the top
8470 of the source package, it is usually sufficient to call
8471 <prgn>dpkg-gencontrol</prgn>.
8475 Sources which build several binaries will typically need
8478 dpkg-gencontrol -Pdebian/tmp-<var>pkg</var> -p<var>package</var>
8479 </example> The <tt>-P</tt> tells
8480 <prgn>dpkg-gencontrol</prgn> that the package is being
8481 built in a non-default directory, and the <tt>-p</tt>
8482 tells it which package's control file should be generated.
8486 <prgn>dpkg-gencontrol</prgn> also adds information to the
8487 list of files in <file>debian/files</file>, for the benefit of
8488 (for example) a future invocation of
8489 <prgn>dpkg-genchanges</prgn>.</p>
8494 <prgn>dpkg-shlibdeps</prgn> - calculates shared library
8499 This program is usually called from <file>debian/rules</file>
8500 just before <prgn>dpkg-gencontrol</prgn> (see <ref
8501 id="pkg-sourcetree">), in the top level of the source tree.
8505 Its arguments are executables.
8508 In a forthcoming dpkg version,
8509 <prgn>dpkg-shlibdeps</prgn> would be required to be
8510 called on shared libraries as well.
8513 They may be specified either in the locations in the
8514 source tree where they are created or in the locations
8515 in the temporary build tree where they are installed
8516 prior to binary package creation.
8518 </footnote> for which shared library dependencies should
8519 be included in the binary package's control file.
8523 If some of the found shared libraries should only
8524 warrant a <tt>Recommends</tt> or <tt>Suggests</tt>, or if
8525 some warrant a <tt>Pre-Depends</tt>, this can be achieved
8526 by using the <tt>-d<var>dependency-field</var></tt> option
8527 before those executable(s). (Each <tt>-d</tt> option
8528 takes effect until the next <tt>-d</tt>.)
8532 <prgn>dpkg-shlibdeps</prgn> does not directly cause the
8533 output control file to be modified. Instead by default it
8534 adds to the <file>debian/substvars</file> file variable
8535 settings like <tt>shlibs:Depends</tt>. These variable
8536 settings must be referenced in dependency fields in the
8537 appropriate per-binary-package sections of the source
8542 For example, the <prgn>procps</prgn> package generates two
8543 kinds of binaries, simple C binaries like <prgn>ps</prgn>
8544 which require a predependency and full-screen ncurses
8545 binaries like <prgn>top</prgn> which require only a
8546 recommendation. It can say in its <file>debian/rules</file>:
8548 dpkg-shlibdeps -dPre-Depends ps -dRecommends top
8550 and then in its main control file <file>debian/control</file>:
8554 Pre-Depends: ${shlibs:Pre-Depends}
8555 Recommends: ${shlibs:Recommends}
8561 Sources which produce several binary packages with
8562 different shared library dependency requirements can use
8563 the <tt>-p<var>varnameprefix</var></tt> option to override
8564 the default <tt>shlibs:</tt> prefix (one invocation of
8565 <prgn>dpkg-shlibdeps</prgn> per setting of this option).
8566 They can thus produce several sets of dependency
8567 variables, each of the form
8568 <tt><var>varnameprefix</var>:<var>dependencyfield</var></tt>,
8569 which can be referred to in the appropriate parts of the
8570 binary package control files.
8577 <prgn>dpkg-distaddfile</prgn> - adds a file to
8578 <file>debian/files</file>
8582 Some packages' uploads need to include files other than
8583 the source and binary package files.
8587 <prgn>dpkg-distaddfile</prgn> adds a file to the
8588 <file>debian/files</file> file so that it will be included in
8589 the <file>.changes</file> file when
8590 <prgn>dpkg-genchanges</prgn> is run.
8594 It is usually invoked from the <tt>binary</tt> target of
8595 <file>debian/rules</file>:
8597 dpkg-distaddfile <var>filename</var> <var>section</var> <var>priority</var>
8599 The <var>filename</var> is relative to the directory where
8600 <prgn>dpkg-genchanges</prgn> will expect to find it - this
8601 is usually the directory above the top level of the source
8602 tree. The <file>debian/rules</file> target should put the
8603 file there just before or just after calling
8604 <prgn>dpkg-distaddfile</prgn>.
8608 The <var>section</var> and <var>priority</var> are passed
8609 unchanged into the resulting <file>.changes</file> file. See
8610 <ref id="pkg-f-classification">.
8615 <sect1><heading><prgn>dpkg-genchanges</prgn> - generates a <file>.changes</file> upload
8620 This program is usually called by package-independent
8621 automatic building scripts such as
8622 <prgn>dpkg-buildpackage</prgn>, but it may also be called
8627 It is usually called in the top level of a built source
8628 tree, and when invoked with no arguments will print out a
8629 straightforward <file>.changes</file> file based on the
8630 information in the source package's changelog and control
8631 file and the binary and source packages which should have
8637 <sect1><heading><prgn>dpkg-parsechangelog</prgn> - produces parsed representation of
8642 This program is used internally by
8643 <prgn>dpkg-source</prgn> et al. It may also occasionally
8644 be useful in <file>debian/rules</file> and elsewhere. It
8645 parses a changelog, <file>debian/changelog</file> by default,
8646 and prints a control-file format representation of the
8647 information in it to standard output.
8651 <sect1 id="pkg-dpkgarch"><heading><prgn>dpkg-architecture</prgn> -
8652 information about the build and host system
8656 This program can be used manually, but is also invoked by
8657 <tt>dpkg-buildpackage</tt> or <file>debian/rules</file> to set
8658 to set environment or make variables which specify the build and
8659 host architecture for the package building process.
8664 <sect id="pkg-sourcetree"><heading>The Debianised source tree
8668 The source archive scheme described later is intended to
8669 allow a Debianised source tree with some associated control
8670 information to be reproduced and transported easily. The
8671 Debianised source tree is a version of the original program
8672 with certain files added for the benefit of the
8673 Debianisation process, and with any other changes required
8674 made to the rest of the source code and installation
8679 The extra files created for Debian are in the subdirectory
8680 <file>debian</file> of the top level of the Debianised source
8681 tree. They are described below.
8684 <sect1 id="pkg-debianrules"><heading><file>debian/rules</file> - the main building
8689 This file is an executable makefile, and contains the
8690 package-specific recipies for compiling the package and
8691 building binary package(s) out of the source.
8695 It must start with the line <tt>#!/usr/bin/make -f</tt>,
8696 so that it can be invoked by saying its name rather than
8697 invoking <prgn>make</prgn> explicitly.
8701 Since an interactive <file>debian/rules</file> script makes it
8702 impossible to autocompile that package and also makes it
8703 hard for other people to reproduce the same binary
8704 package, all <strong>required targets</strong> have to be
8705 non-interactive. At a minimul, required targets are the
8706 ones called by <prgn>dpkg-buildpackage</prgn>, namely,
8707 <em>clean</em>, <em>binary</em>, <em>binary-arch</em>, and
8708 <em>build</em>. It also follows that any target that these
8709 targets depend on must also be non-interactive.
8713 The targets which are required to be present are:
8715 <tag><tt>build</tt></tag>
8718 This should perform all non-interactive
8719 configuration and compilation of the package. If a
8720 package has an interactive pre-build configuration
8721 routine, the Debianised source package should be
8722 built after this has taken place, so that it can be
8723 built without rerunning the configuration.
8727 A package may also provide both of the targets
8728 <tt>build-arch</tt> and <tt>build-indep</tt>. The
8729 <tt>build-arch</tt> target, if provided, should
8730 perform all non-interactive configuration and
8731 compilation required for producing all
8732 architecture-dependant binary packages (those packages
8733 for which the body of the <tt>Architecture</tt> field
8734 in <tt>debian/control</tt> is not <tt>all</tt>).
8735 Similarly, the <tt>build-indep</tt> target, if
8736 provided, should perform all non-interactive
8737 configuration and compilation required for producing
8738 all architecture-independent binary packages (those
8739 packages for which the body of the
8740 <tt>Architecture</tt> field in <tt>debian/control</tt>
8741 is <tt>all</tt>). The <tt>build</tt> target should
8742 depend on those of the targets <tt>build-arch</tt> and
8743 <tt>build-indep</tt> that are provided in the rules
8748 If one or both of the targets <tt>build-arch</tt> and
8749 <tt>build-indep</tt> are not provided, then invoking
8750 <file>debian/rules</file> with one of the not-provided
8751 targets as arguments should produce a exit status code
8752 of 2. Usually this is provided automatically by make
8753 if the target is missing.
8757 For some packages, notably ones where the same
8758 source tree is compiled in different ways to produce
8759 two binary packages, the <tt>build</tt> target does
8760 not make much sense. For these packages it is good
8761 enough to provide two (or more) targets
8762 (<tt>build-a</tt> and <tt>build-b</tt> or whatever)
8763 for each of the ways of building the package, and a
8764 <tt>build</tt> target that does nothing. The
8765 <tt>binary</tt> target will have to build the
8766 package in each of the possible ways and make the
8767 binary package out of each.
8771 The targets <tt>build</tt>, <tt>build-arch</tt>
8772 and <tt>build-indep</tt> target must not do
8773 anything that might require root privilege.
8777 The <tt>build</tt> target may need to run
8778 <tt>clean</tt> first - see below.
8782 When a package has a configuration routine that takes
8783 a long time, or when the makefiles are poorly
8784 designed, or when <tt>build</tt> needs to run
8785 <tt>clean</tt> first, it is a good idea to <tt>touch
8786 build</tt> when the build process is complete. This
8787 will ensure that if <tt>debian/rules build</tt> is run
8788 again it will not rebuild the whole program.
8792 <tag><tt>binary</tt>, <tt>binary-arch</tt>,
8793 <tt>binary-indep</tt>
8797 The <tt>binary</tt> target should be all that is
8798 necessary for the user to build the binary
8799 package. All these targets are required to be
8800 non-interactive. It is split into two parts:
8801 <tt>binary-arch</tt> builds the packages' output
8802 files which are specific to a particular
8803 architecture, and <tt>binary-indep</tt> builds
8804 those which are not.
8808 <tt>binary</tt> should usually be a target with
8809 no commands which simply depends on
8810 <prgn>binary-arch</prgn> and
8811 <prgn>binary-indep</prgn>.
8815 Both <prgn>binary-*</prgn> targets should depend on
8816 the <tt>build</tt> target, above, so that the
8817 package is built if it has not been already. It
8818 should then create the relevant binary package(s),
8819 using <prgn>dpkg-gencontrol</prgn> to make their
8820 control files and <prgn>dpkg-deb</prgn> to build
8821 them and place them in the parent of the top level
8826 If one of the <prgn>binary-*</prgn> targets has
8827 nothing to do (this will be always be the case if
8828 the source generates only a single binary package,
8829 whether architecture-dependent or not) it
8830 <em>must</em> still exist, but should always
8835 <ref id="pkg-binarypkg"> describes how to construct
8840 The <tt>binary</tt> targets must be invoked as
8845 <tag><tt>clean</tt></tag>
8849 This should undo any effects that the
8850 <tt>build</tt> and <tt>binary</tt> targets
8851 may have had, except that it should leave alone any
8852 output files created in the parent directory by a
8853 run of <tt>binary</tt>. This target is required
8854 to be non-interactive.
8858 If a <tt>build</tt> file is touched at the end
8859 of the <tt>build</tt> target, as suggested
8860 above, it must be removed as the first thing that
8861 <tt>clean</tt> does, so that running
8862 <tt>build</tt> again after an interrupted
8863 <tt>clean</tt> doesn't think that everything is
8868 The <tt>clean</tt> target must be invoked as
8869 root if <tt>binary</tt> has been invoked since
8870 the last <tt>clean</tt>, or if
8871 <tt>build</tt> has been invoked as root (since
8872 <tt>build</tt> may create directories, for
8877 <tag><tt>get-orig-source</tt> (optional)</tag>
8881 This target fetches the most recent version of the
8882 original source package from a canonical archive
8883 site (via FTP or WWW, for example), does any
8884 necessary rearrangement to turn it into the original
8885 source tarfile format described below, and leaves it
8886 in the current directory.
8890 This target may be invoked in any directory, and
8891 should take care to clean up any temporary files it
8896 This target is optional, but providing it if
8897 possible is a good idea.
8903 The <tt>build</tt>, <tt>binary</tt> and
8904 <tt>clean</tt> targets must be invoked with a current
8905 directory of the package's top-level directory.
8910 Additional targets may exist in <file>debian/rules</file>,
8911 either as published or undocumented interfaces or for the
8912 package's internal use.
8916 The architecture we build on and build for is determined by make
8917 variables via dpkg-architecture (see <ref id="pkg-dpkgarch">). You can
8918 get the Debian architecture and the GNU style architecture
8919 specification string for the build machine as well as the host
8920 machine. Here is a list of supported make variables:
8921 <list compact="compact">
8923 <p><tt>DEB_*_ARCH</tt> (the Debian architecture)</p>
8926 <p><tt>DEB_*_GNU_TYPE</tt> (the GNU style architecture
8927 specification string)</p>
8930 <p><tt>DEB_*_GNU_CPU</tt> (the CPU part of DEB_*_GNU_TYPE)</p>
8933 <p><tt>DEB_*_GNU_SYSTEM</tt> (the System part of
8939 where <tt>*</tt> is either <tt>BUILD</tt> for specification of
8940 the build machine or <tt>HOST</tt> for specification of the machine
8945 Backward compatibility can be provided in the rules file
8946 by setting the needed variables to suitable default
8947 values, please refer to the documentation of
8948 dpkg-architecture for details.
8952 It is important to understand that the <tt>DEB_*_ARCH</tt>
8953 string does only determine which Debian architecture we
8954 build on resp. for. It should not be used to get the CPU
8955 or System information, the GNU style variables should be
8961 <sect1><heading><file>debian/control</file>
8965 This file contains version-independent details about the
8966 source package and about the binary packages it creates.
8970 It is a series of sets of control fields, each
8971 syntactically similar to a binary package control file.
8972 The sets are separated by one or more blank lines. The
8973 first set is information about the source package in
8974 general; each subsequent set describes one binary package
8975 that the source tree builds.
8979 The syntax and semantics of the fields are described below
8980 in <ref id="pkg-controlfields">.
8984 The general (binary-package-independent) fields are:
8985 <list compact="compact">
8987 <p><qref id="pkg-f-Source"><tt>Source</tt></qref> (mandatory)</p>
8990 <p><qref id="pkg-f-Maintainer"><tt>Maintainer</tt></qref></p>
8994 <qref id="pkg-f-classification"><tt>Section</tt> and
8995 <tt>Priority</tt></qref>
8996 (classification, mandatory)
9001 <qref id="relationships"><tt>Build-Depends</tt> et
9002 al.</qref> (source package interrelationships)
9007 <qref id="pkg-f-Standards-Version"><tt>Standards-Version</tt></qref>
9013 The per-binary-package fields are:
9014 <list compact="compact">
9016 <p><qref id="pkg-f-Package"><tt>Package</tt></qref> (mandatory)</p>
9020 <qref id="pkg-f-Architecture"><tt>Architecture</tt></qref>
9024 <p><qref id="descriptions"><tt>Description</tt></qref></p>
9028 <qref id="pkg-f-classification"><tt>Section</tt> and
9029 <tt>Priority</tt></qref> (classification)</p>
9032 <p><qref id="pkg-f-Essential"><tt>Essential</tt></qref></p>
9036 <qref id="relationships"><tt>Depends</tt> et
9037 al.</qref> (binary package interrelationships)
9043 These fields are used by <prgn>dpkg-gencontrol</prgn> to
9044 generate control files for binary packages (see below), by
9045 <prgn>dpkg-genchanges</prgn> to generate the
9046 <tt>.changes</tt> file to accompany the upload, and by
9047 <prgn>dpkg-source</prgn> when it creates the <file>.dsc</file>
9048 source control file as part of a source archive.
9052 The fields here may contain variable references - their
9053 values will be substituted by
9054 <prgn>dpkg-gencontrol</prgn>, <prgn>dpkg-genchanges</prgn>
9055 or <prgn>dpkg-source</prgn> when they generate output
9056 control files. See <ref id="pkg-srcsubstvars"> for details.
9059 <p> <sect2><heading>User-defined fields
9063 Additional user-defined fields may be added to the
9064 source package control file. Such fields will be
9065 ignored, and not copied to (for example) binary or
9066 source package control files or upload control files.
9070 If you wish to add additional unsupported fields to
9071 these output files you should use the mechanism
9076 Fields in the main source control information file with
9077 names starting <tt>X</tt>, followed by one or more of
9078 the letters <tt>BCS</tt> and a hyphen <tt>-</tt>, will
9079 be copied to the output files. Only the part of the
9080 field name after the hyphen will be used in the output
9081 file. Where the letter <tt>B</tt> is used the field
9082 will appear in binary package control files, where the
9083 letter <tt>S</tt> is used in source package control
9084 files and where <tt>C</tt> is used in upload control
9085 (<tt>.changes</tt>) files.
9089 For example, if the main source information control file
9092 XBS-Comment: I stand between the candle and the star.
9094 then the binary and source package control files will contain the
9097 Comment: I stand between the candle and the star.
9104 <sect1 id="pkg-dpkgchangelog"><heading><file>debian/changelog</file>
9108 This file records the changes to the Debian-specific parts of the
9112 Though there is nothing stopping an author who is also
9113 the Debian maintainer from using it for all their
9114 changes, it will have to be renamed if the Debian and
9115 upstream maintainers become different
9122 It has a special format which allows the package building
9123 tools to discover which version of the package is being
9124 built and find out other release-specific information.
9128 That format is a series of entries like this:
9130 <var>package</var> (<var>version</var>) <var>distribution(s)</var>; urgency=<var>urgency</var>
9132 * <var>change details</var>
9133 <var>more change details</var>
9134 * <var>even more change details</var>
9136 -- <var>maintainer name and email address</var> <var>date</var>
9141 <var>package</var> and <var>version</var> are the source
9142 package name and version number.
9146 <var>distribution(s)</var> lists the distributions where
9147 this version should be installed when it is uploaded - it
9148 is copied to the <tt>Distribution</tt> field in the
9149 <tt>.changes</tt> file. See <ref id="pkg-f-Distribution">.
9153 <var>urgency</var> is the value for the <tt>Urgency</tt>
9154 field in the <file>.changes</file> file for the upload. See
9155 <ref id="pkg-f-Urgency">. It is not possible to specify an
9156 urgency containing commas; commas are used to separate
9157 <tt><var>keyword</var>=<var>value</var></tt> settings in
9158 the <prgn>dpkg</prgn> changelog format (though there is
9159 currently only one useful <var>keyword</var>,
9164 The change details may in fact be any series of lines
9165 starting with at least two spaces, but conventionally each
9166 change starts with an asterisk and a separating space and
9167 continuation lines are indented so as to bring them in
9168 line with the start of the text above. Blank lines may be
9169 used here to separate groups of changes, if desired.
9173 The maintainer name and email address should <em>not</em>
9174 necessarily be those of the usual package maintainer.
9175 They should be the details of the person doing
9176 <em>this</em> version. The information here will be
9177 copied to the <file>.changes</file> file, and then later used
9178 to send an acknowledgement when the upload has been
9183 The <var>date</var> should be in RFC822 format
9186 This is generated by the <prgn>822-date</prgn>
9189 </footnote>; it should include the timezone specified
9190 numerically, with the timezone name or abbreviation
9191 optionally present as a comment.
9195 The first "title" line with the package name should start
9196 at the left hand margin; the "trailer" line with the
9197 maintainer and date details should be preceded by exactly
9198 one space. The maintainer details and the date must be
9199 separated by exactly two spaces.
9203 An Emacs mode for editing this format is available: it is
9204 called <tt>debian-changelog-mode</tt>. You can have this
9205 mode selected automatically when you edit a Debian
9206 changelog by adding a local variables clause to the end of
9210 <sect2><heading>Defining alternative changelog formats
9214 It is possible to use a different format to the standard
9215 one, by providing a parser for the format you wish to
9220 In order to have <tt>dpkg-parsechangelog</tt> run your
9221 parser, you must include a line within the last 40 lines
9222 of your file matching the Perl regular expression:
9223 <tt>\schangelog-format:\s+([0-9a-z]+)\W</tt> The part in
9224 parentheses should be the name of the format. For
9225 example, you might say:
9227 @@@ changelog-format: joebloggs @@@
9229 Changelog format names are non-empty strings of alphanumerics.
9233 If such a line exists then <tt>dpkg-parsechangelog</tt>
9234 will look for the parser as
9235 <file>/usr/lib/dpkg/parsechangelog/<var>format-name</var></file>
9237 <file>/usr/local/lib/dpkg/parsechangelog/<var>format-name</var></file>;
9238 it is an error for it not to find it, or for it not to
9239 be an executable program. The default changelog format
9240 is <tt>dpkg</tt>, and a parser for it is provided with
9241 the <tt>dpkg</tt> package.
9245 The parser will be invoked with the changelog open on
9246 standard input at the start of the file. It should read
9247 the file (it may seek if it wishes) to determine the
9248 information required and return the parsed information
9249 to standard output in the form of a series of control
9250 fields in the standard format. By default it should
9251 return information about only the most recent version in
9252 the changelog; it should accept a
9253 <tt>-v<var>version</var></tt> option to return changes
9254 information from all versions present <em>strictly
9255 after</em> <var>version</var>, and it should then be an
9256 error for <var>version</var> not to be present in the
9262 <list compact="compact">
9264 <p><qref id="pkg-f-Source"><tt>Source</tt></qref></p>
9267 <p><qref id="versions"><tt>Version</tt></qref> (mandatory)</p>
9271 <qref id="pkg-f-Distribution"><tt>Distribution</tt></qref>
9276 <p><qref id="pkg-f-Urgency"><tt>Urgency</tt></qref> (mandatory)</p>
9280 <qref id="pkg-f-Maintainer"><tt>Maintainer</tt></qref>
9285 <p><qref id="pkg-f-Date"><tt>Date</tt></qref></p>
9289 <qref id="pkg-f-Changes"><tt>Changes</tt></qref>
9296 If several versions are being returned (due to the use
9297 of <tt>-v</tt>), the urgency value should be of the
9298 highest urgency code listed at the start of any of the
9299 versions requested followed by the concatenated
9300 (space-separated) comments from all the versions
9301 requested; the maintainer, version, distribution and
9302 date should always be from the most recent version.
9306 For the format of the <tt>Changes</tt> field see <ref
9307 id="pkg-f-Changes">.
9311 If the changelog format which is being parsed always or
9312 almost always leaves a blank line between individual
9313 change notes these blank lines should be stripped out,
9314 so as to make the resulting output compact.
9318 If the changelog format does not contain date or package
9319 name information this information should be omitted from
9320 the output. The parser should not attempt to synthesise
9321 it or find it from other sources.
9325 If the changelog does not have the expected format the
9326 parser should exit with a nonzero exit status, rather
9327 than trying to muddle through and possibly generating
9332 A changelog parser may not interact with the user at
9336 <!-- FIXME: section pkg-srcsubstvars is the same as srcsubstvars -->
9338 <sect1 id="pkg-srcsubstvars"><heading><file>debian/substvars</file>
9339 and variable substitutions
9343 When <prgn>dpkg-gencontrol</prgn>,
9344 <prgn>dpkg-genchanges</prgn> and <prgn>dpkg-source</prgn>
9345 generate control files they do variable substitutions on
9346 their output just before writing it. Variable
9347 substitutions have the form
9348 <tt>${<var>variable-name</var>}</tt>. The optional file
9349 <file>debian/substvars</file> contains variable substitutions
9350 to be used; variables can also be set directly from
9351 <file>debian/rules</file> using the <tt>-V</tt> option to the
9352 source packaging commands, and certain predefined
9353 variables are available.
9357 This file is usually generated and modified dynamically by
9358 <file>debian/rules</file> targets, in which case it must be
9359 removed by the <tt>clean</tt> target.
9363 See <manref name="dpkg-source" section="1"> for full
9364 details about source variable substitutions, including the
9365 format of <file>debian/substvars</file>.</p>
9368 <sect1><heading><file>debian/files</file>
9372 This file is not a permanent part of the source tree; it
9373 is used while building packages to record which files are
9374 being generated. <prgn>dpkg-genchanges</prgn> uses it
9375 when it generates a <file>.changes</file> file.
9379 It should not exist in a shipped source package, and so it
9380 (and any backup files or temporary files such as
9381 <file>files.new</file>
9384 <file>files.new</file> is used as a temporary file by
9385 <prgn>dpkg-gencontrol</prgn> and
9386 <prgn>dpkg-distaddfile</prgn> - they write a new
9387 version of <file>files</file> here before renaming it,
9388 to avoid leaving a corrupted copy if an error
9391 </footnote>) should be removed by the
9392 <tt>clean</tt> target. It may also be wise to
9393 ensure a fresh start by emptying or removing it at the
9394 start of the <tt>binary</tt> target.
9398 <prgn>dpkg-gencontrol</prgn> adds an entry to this file
9399 for the <file>.deb</file> file that will be created by
9400 <prgn>dpkg-deb</prgn> from the control file that it
9401 generates, so for most packages all that needs to be done
9402 with this file is to delete it in <tt>clean</tt>.
9406 If a package upload includes files besides the source
9407 package and any binary packages whose control files were
9408 made with <prgn>dpkg-gencontrol</prgn> then they should be
9409 placed in the parent of the package's top-level directory
9410 and <prgn>dpkg-distaddfile</prgn> should be called to add
9411 the file to the list in <file>debian/files</file>.</p>
9414 <sect1><heading><file>debian/tmp</file>
9418 This is the canonical temporary location for the
9419 construction of binary packages by the <tt>binary</tt>
9420 target. The directory <file>tmp</file> serves as the root of
9421 the filesystem tree as it is being constructed (for
9422 example, by using the package's upstream makefiles install
9423 targets and redirecting the output there), and it also
9424 contains the <tt>DEBIAN</tt> subdirectory. See <ref
9425 id="pkg-bincreating">.
9429 If several binary packages are generated from the same
9430 source tree it is usual to use several
9431 <file>debian/tmp<var>something</var></file> directories, for
9432 example <file>tmp-a</file> or <file>tmp-doc</file>.
9436 Whatever <file>tmp</file> directories are created and used by
9437 <tt>binary</tt> must of course be removed by the
9438 <tt>clean</tt> target.</p></sect1>
9442 <sect id="pkg-sourcearchives"><heading>Source packages as archives
9446 As it exists on the FTP site, a Debian source package
9447 consists of three related files. You must have the right
9448 versions of all three to be able to use them.
9453 <tag>Debian source control file - <tt>.dsc</tt></tag>
9457 This file contains a series of fields, identified and
9458 separated just like the fields in the control file of
9459 a binary package. The fields are listed below; their
9460 syntax is described above, in <ref id="pkg-controlfields">.
9461 <list compact="compact">
9463 <p><qref id="pkg-f-Source"><tt>Source</tt></qref></p>
9466 <p><qref id="versions"><tt>Version</tt></qref></p>
9469 <p><qref id="pkg-f-Maintainer"><tt>Maintainer</tt></qref></p>
9472 <p><qref id="pkg-f-Binary"><tt>Binary</tt></qref></p>
9475 <p><qref id="pkg-f-Architecture"><tt>Architecture</tt></qref></p>
9479 <qref id="relationships"><tt>Build-Depends</tt> et
9480 al.</qref> (source package interrelationships)
9485 <qref id="pkg-f-Standards-Version"><tt>Standards-Version</tt></qref></p>
9488 <p><qref id="pkg-f-Files"><tt>Files</tt></qref></p>
9493 The source package control file is generated by
9494 <prgn>dpkg-source</prgn> when it builds the source
9495 archive, from other files in the source package,
9496 described above. When unpacking it is checked against
9497 the files and directories in the other parts of the
9498 source package, as described below.</p>
9502 Original source archive -
9504 <var>package</var>_<var>upstream-version</var>.orig.tar.gz
9511 This is a compressed (with <tt>gzip -9</tt>)
9512 <prgn>tar</prgn> file containing the source code from
9513 the upstream authors of the program. The tarfile
9514 unpacks into a directory
9515 <file><var>package</var>-<var>upstream-version</var>.orig</file>,
9516 and does not contain files anywhere other than in
9517 there or in its subdirectories.</p>
9521 Debianisation diff -
9523 <var>package</var>_<var>upstream_version-revision</var>.diff.gz
9529 This is a unified context diff (<tt>diff -u</tt>)
9530 giving the changes which are required to turn the
9531 original source into the Debian source. These changes
9532 may only include editing and creating plain files.
9533 The permissions of files, the targets of symbolic
9534 links and the characteristics of special files or
9535 pipes may not be changed and no files may be removed
9540 All the directories in the diff must exist, except the
9541 <file>debian</file> subdirectory of the top of the source
9542 tree, which will be created by
9543 <prgn>dpkg-source</prgn> if necessary when unpacking.
9547 The <prgn>dpkg-source</prgn> program will
9548 automatically make the <file>debian/rules</file> file
9549 executable (see below).</p></item>
9554 If there is no original source code - for example, if the
9555 package is specially prepared for Debian or the Debian
9556 maintainer is the same as the upstream maintainer - the
9557 format is slightly different: then there is no diff, and the
9559 <file><var>package</var>_<var>version</var>.tar.gz</file> and
9560 contains a directory
9561 <file><var>package</var>-<var>version</var></file>.
9565 <sect><heading>Unpacking a Debian source package without
9566 <prgn>dpkg-source</prgn>
9570 <tt>dpkg-source -x</tt> is the recommended way to unpack a
9571 Debian source package. However, if it is not available it
9572 is possible to unpack a Debian source archive as follows:
9573 <enumlist compact="compact">
9576 Untar the tarfile, which will create a <file>.orig</file>
9580 <p>Rename the <file>.orig</file> directory to
9581 <file><var>package</var>-<var>version</var></file>.</p>
9585 Create the subdirectory <file>debian</file> at the top of
9586 the source tree.</p>
9588 <item><p>Apply the diff using <tt>patch -p0</tt>.</p>
9590 <item><p>Untar the tarfile again if you want a copy of the original
9591 source code alongside the Debianised version.</p>
9596 It is not possible to generate a valid Debian source archive
9597 without using <prgn>dpkg-source</prgn>. In particular,
9598 attempting to use <prgn>diff</prgn> directly to generate the
9599 <file>.diff.gz</file> file will not work.
9602 <sect1><heading>Restrictions on objects in source packages
9606 The source package may not contain any hard links
9609 This is not currently detected when building source
9610 packages, but only when extracting
9616 Hard links may be permitted at some point in the
9617 future, but would require a fair amount of
9620 </footnote>, device special files, sockets or setuid or
9624 Setgid directories are allowed.
9630 The source packaging tools manage the changes between the
9631 original and Debianised source using <prgn>diff</prgn> and
9632 <prgn>patch</prgn>. Turning the original source tree as
9633 included in the <file>.orig.tar.gz</file> into the debianised
9634 source must not involve any changes which cannot be
9635 handled by these tools. Problematic changes which cause
9636 <prgn>dpkg-source</prgn> to halt with an error when
9637 building the source package are:
9638 <list compact="compact">
9639 <item><p>Adding or removing symbolic links, sockets or pipes.</p>
9641 <item><p>Changing the targets of symbolic links.</p>
9643 <item><p>Creating directories, other than <file>debian</file>.</p>
9645 <item><p>Changes to the contents of binary files.</p></item>
9646 </list> Changes which cause <prgn>dpkg-source</prgn> to
9647 print a warning but continue anyway are:
9648 <list compact="compact">
9651 Removing files, directories or symlinks.
9654 Renaming a file is not treated specially - it is
9655 seen as the removal of the old file (which
9656 generates a warning, but is otherwise ignored),
9657 and the creation of the new
9664 Changed text files which are missing the usual final
9665 newline (either in the original or the modified
9670 Changes which are not represented, but which are not detected by
9671 <prgn>dpkg-source</prgn>, are:
9672 <list compact="compact">
9673 <item><p>Changing the permissions of files (other than
9674 <file>debian/rules</file>) and directories.</p></item>
9679 The <file>debian</file> directory and <file>debian/rules</file>
9680 are handled specially by <prgn>dpkg-source</prgn> - before
9681 applying the changes it will create the <file>debian</file>
9682 directory, and afterwards it will make
9683 <file>debian/rules</file> world-exectuable.
9689 <appendix id="pkg-controlfields"><heading>Control files and their
9690 fields (from old Packaging Manual)
9694 Many of the tools in the <prgn>dpkg</prgn> suite manipulate
9695 data in a common format, known as control files. Binary and
9696 source packages have control data as do the <file>.changes</file>
9697 files which control the installation of uploaded files, and
9698 <prgn>dpkg</prgn>'s internal databases are in a similar
9702 <sect><heading>Syntax of control files
9706 A file consists of one or more paragraphs of fields. The
9707 paragraphs are separated by blank lines. Some control files
9708 only allow one paragraph; others allow several, in which
9709 case each paragraph often refers to a different package.
9713 Each paragraph is a series of fields and values; each field
9714 consists of a name, followed by a colon and the value. It
9715 ends at the end of the line. Horizontal whitespace (spaces
9716 and tabs) may occur before or after the value and is ignored
9717 there; it is conventional to put a single space after the
9722 Some fields' values may span several lines; in this case
9723 each continuation line <em>must</em> start with a space or
9724 tab. Any trailing spaces or tabs at the end of individual
9725 lines of a field value are ignored.
9729 Except where otherwise stated only a single line of data is
9730 allowed and whitespace is not significant in a field body.
9731 Whitespace may never appear inside names (of packages,
9732 architectures, files or anything else), version numbers or
9733 in between the characters of multi-character version
9738 Field names are not case-sensitive, but it is usual to
9739 capitalise the field names using mixed case as shown below.
9743 Blank lines, or lines consisting only of spaces and tabs,
9744 are not allowed within field values or between fields - that
9745 would mean a new paragraph.
9749 It is important to note that there are several fields which
9750 are optional as far as <prgn>dpkg</prgn> and the related
9751 tools are concerned, but which must appear in every Debian
9752 package, or whose omission may cause problems. When writing
9753 the control files for Debian packages you <em>must</em> read
9754 the Debian policy manual in conjuction with the details
9755 below and the list of fields for the particular file.</p>
9758 <sect><heading>List of fields
9761 <sect1 id="pkg-f-Package"><heading><tt>Package</tt>
9765 The name of the binary package. Package names consist of
9766 the alphanumerics and <tt>+</tt> <tt>-</tt> <tt>.</tt>
9767 (plus, minus and full stop).
9770 The characters <tt>@</tt> <tt>:</tt> <tt>=</tt>
9771 <tt>%</tt> <tt>_</tt> (at, colon, equals, percent
9772 and underscore) used to be legal and are still
9773 accepted when found in a package file, but may not be
9774 used in new packages
9780 They must be at least two characters and must start with
9781 an alphanumeric. In current versions of dpkg they are
9782 sort of case-sensitive<footnote><p>This is a
9783 bug.</p></footnote>; use lowercase package names unless
9784 the package you're building (or referring to, in other
9785 fields) is already using uppercase.</p>
9788 <sect1 id="pkg-f-Version"><heading><tt>Version</tt>
9792 This lists the source or binary package's version number -
9793 see <ref id="versions">.
9798 <sect1 id="pkg-f-Architecture"><heading><tt>Architecture</tt>
9802 This is the architecture string; it is a single word for
9803 the Debian architecture.
9807 <prgn>dpkg</prgn> will check the declared architecture of
9808 a binary package against its own compiled-in value before
9813 The special value <tt>all</tt> indicates that the package
9814 is architecture-independent.
9818 In the main <file>debian/control</file> file in the source
9819 package, or in the source package control file
9820 <file>.dsc</file>, a list of architectures (separated by
9821 spaces) is also allowed, as is the special value
9822 <tt>any</tt>. A list indicates that the source will build
9823 an architecture-dependent package, and will only work
9824 correctly on the listed architectures. <tt>any</tt>
9825 indicates that though the source package isn't dependent
9826 on any particular architecture and should compile fine on
9827 any one, the binary package(s) produced are not
9828 architecture-independent but will instead be specific to
9829 whatever the current build architecture is.
9833 In a <file>.changes</file> file the <tt>Architecture</tt>
9834 field lists the architecture(s) of the package(s)
9835 currently being uploaded. This will be a list; if the
9836 source for the package is being uploaded too the special
9837 entry <tt>source</tt> is also present.
9841 See <ref id="pkg-debianrules"> for information how to get the
9842 architecture for the build process.
9846 <sect1 id="pkg-f-Maintainer"><heading><tt>Maintainer</tt>
9850 The package maintainer's name and email address. The name
9851 should come first, then the email address inside angle
9852 brackets <tt><></tt> (in RFC822 format).
9856 If the maintainer's name contains a full stop then the
9857 whole field will not work directly as an email address due
9858 to a misfeature in the syntax specified in RFC822; a
9859 program using this field as an address must check for this
9860 and correct the problem if necessary (for example by
9861 putting the name in round brackets and moving it to the
9862 end, and bringing the email address forward).
9866 In a <file>.changes</file> file or parsed changelog data this
9867 contains the name and email address of the person
9868 responsible for the particular version in question - this
9869 may not be the package's usual maintainer.
9873 This field is usually optional in as far as the
9874 <prgn>dpkg</prgn> are concerned, but its absence when
9875 building packages usually generates a warning.</p>
9878 <sect1 id="pkg-f-Source"><heading><tt>Source</tt>
9882 This field identifies the source package name.
9886 In a main source control information or a
9887 <file>.changes</file> or <file>.dsc</file> file or parsed
9888 changelog data this may contain only the name of the
9893 In the control file of a binary package (or in a
9894 <file>Packages</file> file) it may be followed by a version
9895 number in parentheses.
9898 It is usual to leave a space after the package name if
9899 a version number is specified.
9901 </footnote> This version number may be omitted (and is, by
9902 <prgn>dpkg-gencontrol</prgn>) if it has the same value as
9903 the <tt>Version</tt> field of the binary package in
9904 question. The field itself may be omitted from a binary
9905 package control file when the source package has the same
9906 name and version as the binary package.
9910 <sect1><heading>Package interrelationship fields:
9911 <tt>Depends</tt>, <tt>Pre-Depends</tt>,
9912 <tt>Recommends</tt> <tt>Suggests</tt>, <tt>Conflicts</tt>,
9913 <tt>Provides</tt>, <tt>Replaces</tt>
9917 These fields describe the package's relationships with
9918 other packages. Their syntax and semantics are described
9919 in <ref id="relationships">.</p>
9922 <sect1 id="pkg-f-Description"><heading><tt>Description</tt>
9926 In a binary package <tt>Packages</tt> file or main source
9927 control file this field contains a description of the
9928 binary package, in a special format. See <ref
9929 id="descriptions"> for details.
9933 In a <file>.changes</file> file it contains a summary of the
9934 descriptions for the packages being uploaded. The part of
9935 the field before the first newline is empty; thereafter
9936 each line has the name of a binary package and the summary
9937 description line from that binary package. Each line is
9938 indented by one space.</p>
9941 <sect1 id="pkg-f-Essential"><heading><tt>Essential</tt>
9945 This is a boolean field which may occur only in the
9946 control file of a binary package (or in the
9947 <file>Packages</file> file) or in a per-package fields
9948 paragraph of a main source control data file.
9952 If set to <tt>yes</tt> then <prgn>dpkg</prgn> and
9953 <prgn>dselect</prgn> will refuse to remove the package
9954 (though it can be upgraded and/or replaced). The other
9955 possible value is <tt>no</tt>, which is the same as not
9956 having the field at all.</p>
9959 <sect1 id="pkg-f-classification"><heading><tt>Section</tt> and
9964 These two fields classify the package. The
9965 <tt>Priority</tt> represents how important that it is that
9966 the user have it installed; the <tt>Section</tt>
9967 represents an application area into which the package has
9972 When they appear in the <file>debian/control</file> file these
9973 fields give values for the section and priority subfields
9974 of the <tt>Files</tt> field of the <file>.changes</file> file,
9975 and give defaults for the section and priority of the
9980 The section and priority are represented, though not as
9981 separate fields, in the information for each file in the
9982 <qref id="pkg-f-Files"><tt>-File</tt></qref>field of a
9983 <file>.changes</file> file. The section value in a
9984 <file>.changes</file> file is used to decide where to install
9985 a package in the FTP archive.
9989 These fields are not used by by <prgn>dpkg</prgn> proper,
9990 but by <prgn>dselect</prgn> when it sorts packages and
9991 selects defaults. See the Debian policy manual for the
9992 priorities in use and the criteria for selecting the
9993 priority for a Debian package, and look at the Debian FTP
9994 archive for a list of currently in-use priorities.
9998 These fields may appear in binary package control files,
9999 in which case they provide a default value in case the
10000 <file>Packages</file> files are missing the information.
10001 <prgn>dpkg</prgn> and <prgn>dselect</prgn> will only use
10002 the value from a <file>.deb</file> file if they have no other
10003 information; a value listed in a <file>Packages</file> file
10004 will always take precedence. By default
10005 <prgn>dpkg-gencontrol</prgn> does not include the section
10006 and priority in the control file of a binary package - use
10007 the <tt>-isp</tt>, <tt>-is</tt> or <tt>-ip</tt> options to
10008 achieve this effect.</p>
10011 <sect1 id="pkg-f-Binary"><heading><tt>Binary</tt>
10015 This field is a list of binary packages.
10019 When it appears in the <file>.dsc</file> file it is the list
10020 of binary packages which a source package can produce. It
10021 does not necessarily produce all of these binary packages
10022 for every architecture. The source control file doesn't
10023 contain details of which architectures are appropriate for
10024 which of the binary packages.
10028 When it appears in a <file>.changes</file> file it lists the
10029 names of the binary packages actually being uploaded.
10033 The syntax is a list of binary packages separated by
10037 A space after each comma is conventional.
10039 </footnote> Currently the packages must be separated using
10040 only spaces in the <file>.changes</file> file.</p>
10043 <sect1 id="pkg-f-Installed-Size"><heading><tt>Installed-Size</tt>
10047 This field appears in the control files of binary
10048 packages, and in the <file>Packages</file> files. It gives
10049 the total amount of disk space required to install the
10054 The disk space is represented in kilobytes as a simple
10055 decimal number.</p>
10058 <sect1 id="pkg-f-Files"><heading><tt>Files</tt>
10062 This field contains a list of files with information about
10063 each one. The exact information and syntax varies with
10064 the context. In all cases the part of the field
10065 contents on the same line as the field name is empty. The
10066 remainder of the field is one line per file, each line
10067 being indented by one space and containing a number of
10068 sub-fields separated by spaces.
10072 In the <file>.dsc</file> (Debian source control) file each
10073 line contains the MD5 checksum, size and filename of the
10074 tarfile and (if applicable) diff file which make up the
10075 remainder of the source package.
10078 That is, the parts which are not the
10081 </footnote> The exact forms of the filenames are described
10082 in <ref id="pkg-sourcearchives">.
10086 In the <file>.changes</file> file this contains one line per
10087 file being uploaded. Each line contains the MD5 checksum,
10088 size, section and priority and the filename. The section
10089 and priority are the values of the corresponding fields in
10090 the main source control file - see <ref
10091 id="pkg-f-classification">. If no section or priority is
10092 specified then <tt>-</tt> should be used, though section
10093 and priority values must be specified for new packages to
10094 be installed properly.
10098 The special value <tt>byhand</tt> for the section in a
10099 <tt>.changes</tt> file indicates that the file in question
10100 is not an ordinary package file and must by installed by
10101 hand by the distribution maintainers. If the section is
10102 <tt>byhand</tt> the priority should be <tt>-</tt>.
10106 If a new Debian revision of a package is being shipped and
10107 no new original source archive is being distributed the
10108 <tt>.dsc</tt> must still contain the <tt>Files</tt> field
10109 entry for the original source archive
10110 <file><var>package</var>-<var>upstream-version</var>.orig.tar.gz</file>,
10111 but the <file>.changes</file> file should leave it out. In
10112 this case the original source archive on the distribution
10113 site must match exactly, byte-for-byte, the original
10114 source archive which was used to generate the
10115 <file>.dsc</file> file and diff which are being uploaded.</p>
10120 id="pkg-f-Standards-Version"><heading><tt>Standards-Version</tt>
10124 The most recent version of the standards (the
10125 <prgn>dpkg</prgn> programmers' and policy manuals and
10126 associated texts) with which the package complies. This
10127 is updated manually when editing the source package to
10128 conform to newer standards; it can sometimes be used to
10129 tell when a package needs attention.
10133 Its format is the same as that of a version number except
10134 that no epoch or Debian revision is allowed - see <ref
10135 id="versions">.</p>
10139 <sect1 id="pkg-f-Distribution"><heading><tt>Distribution</tt>
10143 In a <file>.changes</file> file or parsed changelog output
10144 this contains the (space-separated) name(s) of the
10145 distribution(s) where this version of the package should
10146 be or was installed. Distribution names follow the rules
10147 for package names. (See <ref id="pkg-f-Package">).
10151 Current distribution values are:
10153 <tag><em>stable</em></tag>
10156 This is the current "released" version of Debian
10157 GNU/Linux. A new version is released approximately
10158 every 3 months after the <em>development</em> code has
10159 been <em>frozen</em> for a month of testing. Once the
10160 distribution is <em>stable</em> only major bug fixes
10161 are allowed. When changes are made to this
10162 distribution, the release number is increased
10163 (for example: 1.2r1 becomes 1.2r2 then 1.2r3, etc).
10167 <tag><em>unstable</em></tag>
10170 This distribution value refers to the
10171 <em>developmental</em> part of the Debian distribution
10172 tree. New packages, new upstream versions of packages
10173 and bug fixes go into the <em>unstable</em> directory
10174 tree. Download from this distribution at your own
10178 <tag><em>contrib</em></tag>
10181 The packages with this distribution value do not meet
10182 the criteria for inclusion in the main Debian
10183 distribution as defined by the Policy Manual, but meet
10184 the criteria for the <em>contrib</em>
10185 Distribution. There is currently no distinction
10186 between stable and unstable packages in the
10187 <em>contrib</em> or <em>non-free</em>
10188 distributions. Use your best judgement in downloading
10189 from this Distribution.</p>
10192 <tag><em>non-free</em></tag>
10195 Like the packages in the <em>contrib</em> seciton,
10196 the packages in <em>non-free</em> do not meet the
10197 criteria for inclusion in the main Debian distribution
10198 as defined by the Policy Manual. Again, use your best
10199 judgement in downloading from this Distribution.</p>
10201 <tag><em>experimental</em></tag>
10204 The packages with this distribution value are deemed
10205 by their maintainers to be high risk. Oftentimes they
10206 represent early beta or developmental packages from
10207 various sources that the maintainers want people to
10208 try, but are not ready to be a part of the other parts
10209 of the Debian distribution tree. Download at your own
10213 <tag><em>frozen</em></tag>
10216 From time to time, (currently, every 3 months) the
10217 <em>unstable</em> distribution enters a state of
10218 "code-freeze" in anticipation of release as a
10219 <em>stable</em> version. During this period of testing
10220 (usually 4 weeks) only fixes for existing or
10221 newly-discovered bugs will be allowed.
10224 </taglist> You should list <em>all</em> distributions that
10225 the package should be installed into. Except in unusual
10226 circumstances, installations to <em>stable</em> should also
10227 go into <em>frozen</em> (if it exists) and
10228 <em>unstable</em>. Likewise, installations into
10229 <em>frozen</em> should also go into <em>unstable</em>.</p>
10232 <sect1 id="pkg-f-Urgency"><heading><tt>Urgency</tt>
10236 This is a description of how important it is to upgrade to
10237 this version from previous ones. It consists of a single
10238 keyword usually taking one of the values <tt>LOW</tt>,
10239 <tt>MEDIUM</tt> or <tt>HIGH</tt>) followed by an optional
10240 commentary (separated by a space) which is usually in
10241 parentheses. For example:
10243 Urgency: LOW (HIGH for diversions users)
10248 This field appears in the <file>.changes</file> file and in
10249 parsed changelogs; its value appears as the value of the
10250 <tt>urgency</tt> attribute in a <prgn>dpkg</prgn>-style
10251 changelog (see <ref id="pkg-dpkgchangelog">).
10255 Urgency keywords are not case-sensitive.</p>
10258 <sect1 id="pkg-f-Date"><heading><tt>Date</tt>
10262 In <tt>.changes</tt> files and parsed changelogs, this
10263 gives the date the package was built or last edited.</p>
10266 <sect1 id="pkg-f-Format"><heading><tt>Format</tt>
10270 This field occurs in <file>.changes</file> files, and
10271 specifies a format revision for the file. The format
10272 described here is version <tt>1.5</tt>. The syntax of the
10273 format value is the same as that of a package version
10274 number except that no epoch or Debian revision is allowed
10275 - see <ref id="versions">.</p>
10278 <sect1 id="pkg-f-Changes"><heading><tt>Changes</tt>
10282 In a <file>.changes</file> file or parsed changelog this field
10283 contains the human-readable changes data, describing the
10284 differences between the last version and the current one.
10288 There should be nothing in this field before the first
10289 newline; all the subsequent lines must be indented by at
10290 least one space; blank lines must be represented by a line
10291 consiting only of a space and a full stop.
10295 Each version's change information should be preceded by a
10296 "title" line giving at least the version, distribution(s)
10297 and urgency, in a human-readable way.
10301 If data from several versions is being returned the entry
10302 for the most recent version should be returned first, and
10303 entries should be separated by the representation of a
10304 blank line (the "title" line may also be followed by the
10305 representation of blank line).</p>
10308 <sect1 id="pkg-f-Filename"><heading><tt>Filename</tt> and
10309 <tt>MSDOS-Filename</tt>
10313 These fields in <tt>Packages</tt> files give the
10314 filename(s) of (the parts of) a package in the
10315 distribution directories, relative to the root of the
10316 Debian hierarchy. If the package has been split into
10317 several parts the parts are all listed in order, separated
10321 <sect1 id="pkg-f-Size"><heading><tt>Size</tt> and <tt>MD5sum</tt>
10325 These fields in <file>Packages</file> files give the size (in
10326 bytes, expressed in decimal) and MD5 checksum of the
10327 file(s) which make(s) up a binary package in the
10328 distribution. If the package is split into several parts
10329 the values for the parts are listed in order, separated by
10333 <sect1 id="pkg-f-Status"><heading><tt>Status</tt>
10337 This field in <prgn>dpkg</prgn>'s status file records
10338 whether the user wants a package installed, removed or
10339 left alone, whether it is broken (requiring
10340 reinstallation) or not and what its current state on the
10341 system is. Each of these pieces of information is a
10345 <sect1 id="pkg-f-Config-Version"><heading><tt>Config-Version</tt>
10349 If a package is not installed or not configured, this
10350 field in <prgn>dpkg</prgn>'s status file records the last
10351 version of the package which was successfully
10355 <sect1 id="pkg-f-Conffiles"><heading><tt>Conffiles</tt>
10359 This field in <prgn>dpkg</prgn>'s status file contains
10360 information about the automatically-managed configuration
10361 files held by a package. This field should <em>not</em>
10362 appear anywhere in a package!</p>
10365 <sect1><heading>Obsolete fields
10369 These are still recognised by <prgn>dpkg</prgn> but should
10370 not appear anywhere any more.
10371 <taglist compact="compact">
10373 <tag><tt>Revision</tt></tag>
10374 <tag><tt>Package-Revision</tt></tag>
10375 <tag><tt>Package_Revision</tt></tag>
10378 The Debian revision part of the package version was
10379 at one point in a separate control file field. This
10380 field went through several names.</p>
10383 <tag><tt>Recommended</tt></tag>
10384 <item><p>Old name for <tt>Recommends</tt></p>
10387 <tag><tt>Optional</tt></tag>
10388 <item><p>Old name for <tt>Suggests</tt>.</p>
10390 <tag><tt>Class</tt></tag>
10391 <item><p>Old name for <tt>Priority</tt>.</p>
10399 <appendix id="pkg-conffiles"><heading>Configuration file handling
10400 (from old Packaging Manual)
10404 <prgn>dpkg</prgn> can do a certain amount of automatic
10405 handling of package configuration files.
10409 Whether this mechanism is appropriate depends on a number of
10410 factors, but basically there are two approaches to any
10411 particular configuration file.
10415 The easy method is to ship a best-effort configuration in the
10416 package, and use <prgn>dpkg</prgn>'s conffile mechanism to
10417 handle updates. If the user is unlikely to want to edit the
10418 file, but you need them to be able to without losing their
10419 changes, and a new package with a changed version of the file
10420 is only released infrequently, this is a good approach.
10424 The hard method is to build the configuration file from
10425 scratch in the <prgn>postinst</prgn> script, and to take the
10426 responsibility for fixing any mistakes made in earlier
10427 versions of the package automatically. This will be
10428 appropriate if the file is likely to need to be different on
10432 <sect><heading>Automatic handling of configuration files by
10437 A package may contain a control area file called
10438 <tt>conffiles</tt>. This file should be a list of filenames
10439 of configuration files needing automatic handling, separated
10440 by newlines. The filenames should be absolute pathnames,
10441 and the files referred to should actually exist in the
10446 When a package is upgraded <prgn>dpkg</prgn> will process
10447 the configuration files during the configuration stage,
10448 shortly before it runs the package's <prgn>postinst</prgn>
10453 For each file it checks to see whether the version of the
10454 file included in the package is the same as the one that was
10455 included in the last version of the package (the one that is
10456 being upgraded from); it also compares the version currently
10457 installed on the system with the one shipped with the last
10462 If neither the user nor the package maintainer has changed
10463 the file, it is left alone. If one or the other has changed
10464 their version, then the changed version is preferred - i.e.,
10465 if the user edits their file, but the package maintainer
10466 doesn't ship a different version, the user's changes will
10467 stay, silently, but if the maintainer ships a new version
10468 and the user hasn't edited it the new version will be
10469 installed (with an informative message). If both have
10470 changed their version the user is prompted about the problem
10471 and must resolve the differences themselves.
10475 The comparisons are done by calculating the MD5 message
10476 digests of the files, and storing the MD5 of the file as it
10477 was included in the most recent version of the package.
10481 When a package is installed for the first time
10482 <prgn>dpkg</prgn> will install the file that comes with it,
10483 unless that would mean overwriting a file already on the
10488 However, note that <prgn>dpkg</prgn> will <em>not</em>
10489 replace a conffile that was removed by the user (or by a
10490 script). This is necessary because with some programs a
10491 missing file produces an effect hard or impossible to
10492 achieve in another way, so that a missing file needs to be
10493 kept that way if the user did it.
10497 Note that a package should <em>not</em> modify a
10498 <prgn>dpkg</prgn>-handled conffile in its maintainer
10499 scripts. Doing this will lead to <prgn>dpkg</prgn> giving
10500 the user confusing and possibly dangerous options for
10501 conffile update when the package is upgraded.</p>
10504 <sect><heading>Fully-featured maintainer script configuration
10509 For files which contain site-specific information such as
10510 the hostname and networking details and so forth, it is
10511 better to create the file in the package's
10512 <prgn>postinst</prgn> script.
10516 This will typically involve examining the state of the rest
10517 of the system to determine values and other information, and
10518 may involve prompting the user for some information which
10519 can't be obtained some other way.
10523 When using this method there are a couple of important
10524 issues which should be considered:
10528 If you discover a bug in the program which generates the
10529 configuration file, or if the format of the file changes
10530 from one version to the next, you will have to arrange for
10531 the postinst script to do something sensible - usually this
10532 will mean editing the installed configuration file to remove
10533 the problem or change the syntax. You will have to do this
10534 very carefully, since the user may have changed the file,
10535 perhaps to fix the very problem that your script is trying
10536 to deal with - you will have to detect these situations and
10537 deal with them correctly.
10541 If you do go down this route it's probably a good idea to
10542 make the program that generates the configuration file(s) a
10543 separate program in <file>/usr/sbin</file>, by convention called
10544 <file><var>package</var>config</file> and then run that if
10545 appropriate from the post-installation script. The
10546 <tt><var>package</var>config</tt> program should not
10547 unquestioningly overwrite an existing configuration - if its
10548 mode of operation is geared towards setting up a package for
10549 the first time (rather than any arbitrary reconfiguration
10550 later) you should have it check whether the configuration
10551 already exists, and require a <tt>--force</tt> flag to
10552 overwrite it.</p></sect>
10555 <appendix id="pkg-alternatives"><heading>Alternative versions of
10556 an interface - <prgn>update-alternatives</prgn> (from old
10561 When several packages all provide different versions of the
10562 same program or file it is useful to have the system select a
10563 default, but to allow the system administrator to change it
10564 and have their decisions respected.
10568 For example, there are several versions of the <prgn>vi</prgn>
10569 editor, and there is no reason to prevent all of them from
10570 being installed at once, each under their own name
10571 (<prgn>nvi</prgn>, <prgn>vim</prgn> or whatever).
10572 Nevertheless it is desirable to have the name <tt>vi</tt>
10573 refer to something, at least by default.
10577 If all the packages involved cooperate, this can be done with
10578 <prgn>update-alternatives</prgn>.
10582 Each package provides its own version under its own name, and
10583 calls <prgn>update-alternatives</prgn> in its postinst to
10584 register its version (and again in its prerm to deregister
10589 See the manpage <manref name="update-alternatives"
10590 section="8"> for details.
10594 If <prgn>update-alternatives</prgn> does not seem appropriate
10595 you may wish to consider using diversions instead.</p>
10598 <appendix id="pkg-diversions"><heading>Diversions - overriding a
10599 package's version of a file (from old Packaging Manual)
10603 It is possible to have <prgn>dpkg</prgn> not overwrite a file
10604 when it reinstalls the package it belongs to, and to have it
10605 put the file from the package somewhere else instead.
10609 This can be used locally to override a package's version of a
10610 file, or by one package to override another's version (or
10611 provide a wrapper for it).
10615 Before deciding to use a diversion, read <ref
10616 id="pkg-alternatives"> to see if you really want a diversion
10617 rather than several alternative versions of a program.
10621 There is a diversion list, which is read by <prgn>dpkg</prgn>,
10622 and updated by a special program <prgn>dpkg-divert</prgn>.
10623 Please see <manref name="dpkg-divert" section="8"> for full
10624 details of its operation.
10628 When a package wishes to divert a file from another, it should
10629 call <prgn>dpkg-divert</prgn> in its preinst to add the
10630 diversion and rename the existing file. For example,
10631 supposing that a <prgn>smailwrapper</prgn> package wishes to
10632 install a wrapper around <file>/usr/sbin/smail</file>:
10634 if [ install = "$1" ]; then
10635 dpkg-divert --package smailwrapper --add --rename \
10636 --divert /usr/sbin/smail.real /usr/sbin/smail
10638 </example> Testing <tt>$1</tt> is necessary so that the script
10639 doesn't try to add the diversion again when
10640 <prgn>smailwrapper</prgn> is upgraded. The <tt>--package
10641 smailwrapper</tt> ensures that <prgn>smailwrapper</prgn>'s
10642 copy of <file>/usr/sbin/smail</file> can bypass the diversion and
10643 get installed as the true version.
10647 The postrm has to do the reverse:
10649 if [ remove = "$1" ]; then
10650 dpkg-divert --package smailwrapper --remove --rename \
10651 --divert /usr/sbin/smail.real /usr/sbin/smail
10657 Do not attempt to divert a file which is vitally important for
10658 the system's operation - when using <prgn>dpkg-divert</prgn>
10659 there is a time, after it has been diverted but before
10660 <prgn>dpkg</prgn> has installed the new version, when the file
10661 does not exist.</p>
10666 <!-- vim:set ai et sts=2 sw=2 tw=76: -->