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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
70 This manual also describes Debian policy as it relates to
71 creating Debian packages. It is not a tutorial on how to build
72 packages, nor is it exhaustive where it comes to describing
73 the behavior of the packaging system. Instead, this manual
74 attempts to define the interface to the package management
75 system that the developers have to be conversant with.<footnote>
77 Informally, the criteria used for inclusion is that the
78 material meet one of the following requirements:
79 <taglist compact="compact">
80 <tag>Standard interfaces</tag>
83 The material presented represents an interface to
84 the packaging system that is mandated for use, and
85 is used by, a significant number of packages, and
86 therefore should not be changed without peer
87 review. Package maintainers can then rely on this
88 interfaces not changing, and the package
89 management software authors need to ensure
90 compatibility with these interface
91 definitions. (Control file and changelog file
92 formats are examples.)
95 <tag>Chosen Convention</tag>
98 If there are a number of technically viable choices
99 that can be made, but one needs to select one of
100 these options for inter-operability. The version
101 number format is one example.
105 Please note that these are not mutually exclusive;
106 selected conventions often become parts of standard
113 The footnotes present in this manual are
114 merely informative, and are not part of Debian policy itself.
118 The appendices to this manual are not necessarily normative,
119 either. Please see <ref id="pkg-scope"> for more information.
123 In the normative part of this manual,
124 the words <em>must</em>, <em>should</em> and
125 <em>may</em>, and the adjectives <em>required</em>,
126 <em>recommended</em> and <em>optional</em>, are used to
127 distinguish the significance of the various guidelines in
128 this policy document. Packages that do not conform to the
129 guidelines denoted by <em>must</em> (or <em>required</em>)
130 will generally not be considered acceptable for the Debian
131 distribution. Non-conformance with guidelines denoted by
132 <em>should</em> (or <em>recommended</em>) will generally be
133 considered a bug, but will not necessarily render a package
134 unsuitable for distribution. Guidelines denoted by
135 <em>may</em> (or <em>optional</em>) are truly optional and
136 adherence is left to the maintainer's discretion.
139 These classifications are roughly equivalent to the bug
140 severities <em>serious</em> (for <em>must</em> or
141 <em>required</em> directive violations), <em>minor</em>,
142 <em>normal</em> or <em>important</em>
143 (for <em>should</em> or <em>recommended</em> directive
144 violations) and <em>wishlist</em> (for <em>optional</em>
146 <p>Compare RFC 2119. Note, however, that these words are
147 used in a different way in this document.</p>
151 Much of the information presented in this manual will be
152 useful even when building a package which is to be
153 distributed in some other way or is intended for local use
159 <heading>New versions of this document</heading>
162 This manual is distributed via the Debian package
163 <package>debian-policy</package>.
167 The current version of this document is also available from
168 the Debian web mirrors at
169 <tt><url name="/doc/debian-policy/"
170 id="http://www.debian.org/doc/debian-policy/"></tt>
171 and from the Debian archive mirrors at
172 <tt><url name="/doc/package-developer/policy.txt.gz"
173 id="http://ftp.debian.org/debian/doc/package-developer/policy.txt.gz"></tt>.
174 Also available from the same directory are several other
175 formats: <file>policy.html.tar.gz</file>, <file>policy.pdf.gz</file>
176 and <file>policy.ps.gz</file>.
180 The <package>debian-policy</package> package also includes the file
181 <file>upgrading-checklist.txt</file> which indicates policy
182 changes between versions of this document.
187 <heading>Authors and Maintainers</heading>
190 Originally called "Debian GNU/Linux Policy Manual", this
191 manual was initially written in 1996 by Ian Jackson.
192 It was revised on November 27th, 1996 by David A. Morris.
193 Christian Schwarz added new sections on March 15th, 1997,
194 and reworked/restructured it in April-July 1997.
195 Christoph Lameter contributed the "Web Standard".
196 Julian Gilbey largely restructured it in 2001.
200 Since September 1998, the responsibility for the contents of
201 this document lies on the debian-policy mailing list. Proposals
202 are discussed there and inserted into policy after a certain
203 consensus is established.
204 <!-- insert shameless policy-process plug here eventually -->
205 The actual editing is done by a group of maintainers that have
206 no editorial powers. These are the current maintainers:
209 <item>Julian Gilbey</item>
210 <item>Branden Robinson</item>
211 <item>Josip Rodin</item>
212 <item>Manoj Srivastava</item>
217 While the authors of this document have tried hard to avoid
218 typos and other errors, these do still occur. If you discover
219 an error in this manual or if you want to give any
220 comments, suggestions, or criticisms please send an email to
221 the Debian Policy List,
222 <email>debian-policy@lists.debian.org</email>, or submit a
223 bug report against the <tt>debian-policy</tt> package.
227 Please do not try to reach the individual authors or maintainers
228 of the Policy Manual regarding changes to the Policy.
234 <heading>The Debian Archive</heading>
236 The Debian GNU/Linux system is maintained and distributed as a
237 collection of <em>packages</em>. Since there are so many of
238 them (currently well over 6000), they are split into
239 <em>sections</em> and given <em>priorities</em> to simplify
240 the handling of them.
243 The effort of the Debian project is to build a free operating
244 system, but not every package we want to make accessible is
245 <em>free</em> in our sense (see the Debian Free Software
246 Guidelines, below), or may be imported/exported without
247 restrictions. Thus, the archive is split into the sections
248 <em>main</em>, <em>non-free</em>, <em>contrib</em>,
249 <em>non-US/main</em>, <em>non-US/non-free</em>, and
250 <em>non-US/contrib</em>. The sections are explained in detail
255 The <em>main</em> and the <em>non-US/main</em> sections
256 together form the <em>Debian GNU/Linux distribution</em>.
260 Packages in the other sections are not considered to be part
261 of the Debian distribution, although we support their use and
262 provide infrastructure for them (such as our bug-tracking
263 system and mailing lists). This Debian Policy Manual applies
264 to these packages as well.</p>
266 <sect id="pkgcopyright">
267 <heading>Package copyright and sections</heading>
269 The aims of this section are:
271 <list compact="compact">
273 <p>to allow us to make as much software available as we
277 <p>to allow us to encourage everyone to write free
281 <p>to allow us to make it easy for people to produce
282 CD-ROMs of our system without violating any licenses,
283 import/export restrictions, or any other laws.</p>
288 <heading>The Debian Free Software Guidelines</heading>
290 The Debian Free Software Guidelines (DFSG) form our
291 definition of "free software". These are:
293 <tag>Free Redistribution
297 The license of a Debian component may not restrict any
298 party from selling or giving away the software as a
299 component of an aggregate software distribution
300 containing programs from several different
301 sources. The license may not require a royalty or
302 other fee for such sale.
309 The program must include source code, and must allow
310 distribution in source code as well as compiled form.
317 The license must allow modifications and derived
318 works, and must allow them to be distributed under the
319 same terms as the license of the original software.
322 <tag>Integrity of The Author's Source Code
326 The license may restrict source-code from being
327 distributed in modified form <em>only</em> if the
328 license allows the distribution of "patch files"
329 with the source code for the purpose of modifying the
330 program at build time. The license must explicitly
331 permit distribution of software built from modified
332 source code. The license may require derived works to
333 carry a different name or version number from the
334 original software. (This is a compromise. The Debian
335 Project encourages all authors to not restrict any
336 files, source or binary, from being modified.)
339 <tag>No Discrimination Against Persons or Groups
343 The license must not discriminate against any person
347 <tag>No Discrimination Against Fields of Endeavor
351 The license must not restrict anyone from making use
352 of the program in a specific field of endeavor. For
353 example, it may not restrict the program from being
354 used in a business, or from being used for genetic
358 <tag>Distribution of License
362 The rights attached to the program must apply to all
363 to whom the program is redistributed without the need
364 for execution of an additional license by those
368 <tag>License Must Not Be Specific to Debian
372 The rights attached to the program must not depend on
373 the program's being part of a Debian system. If the
374 program is extracted from Debian and used or
375 distributed without Debian but otherwise within the
376 terms of the program's license, all parties to whom
377 the program is redistributed must have the same
378 rights as those that are granted in conjunction with
382 <tag>License Must Not Contaminate Other Software
386 The license must not place restrictions on other
387 software that is distributed along with the licensed
388 software. For example, the license must not insist
389 that all other programs distributed on the same medium
390 must be free software.
393 <tag>Example Licenses
397 The "GPL," "BSD," and "Artistic" licenses are examples of
398 licenses that we consider <em>free</em>.
405 <heading>The main section</heading>
407 Every package in <em>main</em> and <em>non-US/main</em>
408 must comply with the DFSG (Debian Free Software
412 In addition, the packages in <em>main</em>
413 <list compact="compact">
416 must not require a package outside of <em>main</em>
417 for compilation or execution (thus, the package must
418 not declare a "Depends", "Recommends", or
419 "Build-Depends" relationship on a non-<em>main</em>
425 must not be so buggy that we refuse to support them,
431 must meet all policy requirements presented in this
438 Similarly, the packages in <em>non-US/main</em>
439 <list compact="compact">
442 must not require a package outside of <em>main</em>
443 or <em>non-US/main</em> for compilation or
449 must not be so buggy that we refuse to support them,
454 must meet all policy requirements presented in this
462 <heading>The contrib section</heading>
464 Every package in <em>contrib</em> and
465 <em>non-US/contrib</em> must comply with the DFSG.
469 In addition, the packages in <em>contrib</em> and
470 <em>non-US/contrib</em>
471 <list compact="compact">
474 must not be so buggy that we refuse to support them,
480 must meet all policy requirements presented in this
488 Furthermore, packages in <em>contrib</em> must not require
489 a package in a <em>non-US</em> section for compilation or
494 Examples of packages which would be included in
495 <em>contrib</em> or <em>non-US/contrib</em> are:
496 <list compact="compact">
499 free packages which require <em>contrib</em>,
500 <em>non-free</em> packages or packages which are not
501 in our archive at all for compilation or execution,
507 wrapper packages or other sorts of free accessories for
515 <heading>The non-free section</heading>
517 Packages must be placed in <em>non-free</em> or
518 <em>non-US/non-free</em> if they are not compliant with
519 the DFSG or are encumbered by patents or other legal
520 issues that make their distribution problematic.
523 In addition, the packages in <em>non-free</em> and
524 <em>non-US/non-free</em>
525 <list compact="compact">
528 must not be so buggy that we refuse to support them,
534 must meet all policy requirements presented in this
535 manual that it is possible for them to meet.<footnote>
537 It is possible that there are policy
538 requirements which the package is unable to
539 meet, for example, if the source is
540 unavailable. These situations will need to be
541 handled on a case-by-case basis.
551 <heading>The non-US sections</heading>
553 Non-free programs with cryptographic program code need to
554 be stored on the <em>non-us</em> server because of export
555 restrictions of the U.S.
558 Programs which use patented algorithms that have a
559 restrictied license also need to be stored on "non-us",
560 since that is located in a country where it is not allowed
561 to patent algorithms.
564 A package depends on another package which is distributed
565 via the non-us server has to be stored on the non-us
570 <heading>Further copyright considerations</heading>
572 Every package must be accompanied by a verbatim copy of
573 its copyright and distribution license in the file
574 <file>/usr/share/doc/<var>package</var>/copyright</file>
575 (see <ref id="copyrightfile"> for further details).
578 We reserve the right to restrict files from being included
579 anywhere in our archives if
580 <list compact="compact">
583 their use or distribution would break a law,
588 there is an ethical conflict in their distribution or
594 we would have to sign a license for them, or
599 their distribution would conflict with other project
607 Programs whose authors encourage the user to make
608 donations are fine for the main distribution, provided
609 that the authors do not claim that not donating is
610 immoral, unethical, illegal or something similar; in such
611 a case they must go in <em>non-free</em>.</p>
614 Packages whose copyright permission notices (or patent
615 problems) do not even allow redistribution of binaries
616 only, and where no special permission has been obtained,
617 must not be placed on the Debian FTP site and its mirrors
621 Note that under international copyright law (this applies
622 in the United States, too), <em>no</em> distribution or
623 modification of a work is allowed without an explicit
624 notice saying so. Therefore a program without a copyright
625 notice <em>is</em> copyrighted and you may not do anything
626 to it without risking being sued! Likewise if a program
627 has a copyright notice but no statement saying what is
628 permitted then nothing is permitted.</p>
631 Many authors are unaware of the problems that restrictive
632 copyrights (or lack of copyright notices) can cause for
633 the users of their supposedly-free software. It is often
634 worthwhile contacting such authors diplomatically to ask
635 them to modify their license terms. However, this can be a
636 politically difficult thing to do and you should ask for
637 advice on the <tt>debian-legal</tt> mailing list first, as
642 When in doubt about a copyright, send mail to
643 <email>debian-legal@lists.debian.org</email>. Be prepared
644 to provide us with the copyright statement. Software
645 covered by the GPL, public domain software and BSD-like
646 copyrights are safe; be wary of the phrases "commercial
647 use prohibited" and "distribution restricted".
651 <heading>Subsections</heading>
654 The packages in the sections <em>main</em>,
655 <em>contrib</em> and <em>non-free</em> are grouped further
656 into <em>subsections</em> to simplify handling.
660 The section and subsection for each package should be
661 specified in the package's <tt>Section</tt> control
662 record. However, the maintainer of the Debian archive
663 may override this selection to ensure the consistency of
664 the Debian distribution. The <tt>Section</tt> field
665 should be of the form:
666 <list compact="compact">
669 <em>subsection</em> if the package is in the
670 <em>main</em> section,
675 <em>section/subsection</em> if the package is in
676 the <em>contrib</em> or <em>non-free</em> section,
682 <tt>non-US</tt>, <tt>non-US/contrib</tt> or
683 <tt>non-US/non-free</tt> if the package is in
684 <em>non-US/main</em>, <em>non-US/contrib</em> or
685 <em>non-US/non-free</em> respectively.
692 The Debian archive maintainers provide the authoritative
693 list of subsections. At present, they are:
694 <em>admin</em>, <em>base</em>, <em>comm</em>,
695 <em>contrib</em>, <em>devel</em>, <em>doc</em>,
696 <em>editors</em>, <em>electronics</em>, <em>games</em>,
697 <em>graphics</em>, <em>hamradio</em>,
698 <em>interpreters</em>, <em>libs</em>, <em>mail</em>,
699 <em>math</em>, <em>misc</em>, <em>net</em>, <em>news</em>,
700 <em>non-US</em>, <em>non-free</em>, <em>oldlibs</em>,
701 <em>otherosfs</em>, <em>science</em>, <em>shells</em>,
702 <em>sound</em>, <em>tex</em>, <em>text</em>,
703 <em>utils</em>, <em>web</em>, <em>x11</em>.
707 <heading>Priorities</heading>
710 Each package should have a <em>priority</em> value, which is
711 included in the package's <em>control record</em>. This
712 information is used by the Debian package management tools
713 to separate high-priority packages from less-important
717 The following <em>priority levels</em> are recognised by the
718 Debian package management tools.
720 <tag><tt>required</tt></tag>
723 Packages which are necessary for the proper
724 functioning of the system. You must not remove these
725 packages or your system may become totally broken and
726 you may not even be able to use <prgn>dpkg</prgn> to
727 put things back. Systems with only the
728 <tt>required</tt> packages are probably unusable, but
729 they do have enough functionality to allow the
730 sysadmin to boot and install more software.</p>
732 <tag><tt>important</tt></tag>
735 Important programs, including those which one would
736 expect to find on any Unix-like system. If the
737 expectation is that an experienced Unix person who
738 found it missing would say "What on earth is going on,
739 where is <prgn>foo</prgn>?", it must be an
740 <tt>important</tt> package.<footnote>
742 This is an important criterion because we are
743 trying to produce, amongst other things, a free
747 Other packages without which the system will not run
748 well or be usable must also have priority
749 <tt>important</tt>. This does
750 <em>not</em> include Emacs, the X Window System, TeX
751 or any other large applications. The
752 <tt>important</tt> packages are just a bare minimum of
753 commonly-expected and necessary tools.</p>
755 <tag><tt>standard</tt></tag>
758 These packages provide a reasonably small but not too
759 limited character-mode system. This is what will be
760 installed by default if the user doesn't select anything
761 else. It doesn't include many large applications.</p>
763 <tag><tt>optional</tt></tag>
766 (In a sense everything that isn't required is
767 optional, but that's not what is meant here.) This is
768 all the software that you might reasonably want to
769 install if you didn't know what it was and don't have
770 specialized requirements. This is a much larger system
771 and includes the X Window System, a full TeX
772 distribution, and many applications. Note that
773 optional packages should not conflict with each other.
776 <tag><tt>extra</tt></tag>
779 This contains all packages that conflict with others
780 with required, important, standard or optional
781 priorities, or are only likely to be useful if you
782 already know what they are or have specialised
789 Packages must not depend on packages with lower priority
790 values (excluding build-time dependencies). In order to
791 ensure this, the priorities of one or more packages may need
797 <heading>Binary packages</heading>
800 The Debian GNU/Linux distribution is based on the Debian
801 package management system, called <prgn>dpkg</prgn>. Thus,
802 all packages in the Debian distribution must be provided
803 in the <tt>.deb</tt> file format.</p>
807 <heading>The package name</heading>
810 Every package must have a name that's unique within the Debian
814 Package names must consist only of lower case letters
815 (<tt>a-z</tt>), digits (<tt>0-9</tt>), plus (<tt>+</tt>)
816 and minus (<tt>-</tt>) signs, and periods (<tt>.</tt>).
817 They must be at least two characters long and must start
818 with an alphanumeric character.
822 The package name is part of the file name of the
823 <tt>.deb</tt> file and is included in the control field
829 <heading>The maintainer of a package</heading>
831 Every package must have a Debian maintainer (the
832 maintainer may be one person or a group of people
833 reachable from a common email address, such as a mailing
834 list). The maintainer is responsible for ensuring that
835 the package is placed in the appropriate distributions.
839 The maintainer must be specified in the
840 <tt>Maintainer</tt> control field with their correct name
841 and a working email address. If one person maintains
842 several packages, he/she should try to avoid having
843 different forms of their name and email address in
844 the <tt>Maintainer</tt> fields of those packages.
848 If the maintainer of a package quits from the Debian
849 project, "Debian QA Group"
850 <email>packages@qa.debian.org</email> takes over the
851 maintainership of the package until someone else
852 volunteers for that task. These packages are called
853 <em>orphaned packages</em>.<footnote>
855 The detailed procedure for doing this gracefully can
856 be found in the Debian Developer's Reference, either
857 in the <tt>developers-reference</tt> package, or on
858 the Debian FTP server
859 <ftpsite>ftp.debian.org</ftpsite> as
860 <ftppath>/debian/doc/package-developer/developers-reference.txt.gz</ftppath>
862 id="http://www.debian.org/doc/packaging-manuals/developers-reference/"
863 name="Debian Developer's Reference"> webpage.
871 <heading>The description of a package</heading>
874 Every Debian package must have an extended description
875 stored in the appropriate field of the control record.</p>
878 The description should be written so that it gives the
879 system administrator enough information to decide whether
880 to install the package. This description should not just
881 be copied verbatim from the program's documentation.
882 Instructions for configuring or using the package should
883 not be included (that is what installation scripts,
884 manual pages, info files, etc., are for). Copyright
885 statements and other administrivia should not be included
886 either (that is what the copyright file is for).
890 Please refer to <ref id="descriptions"> for more information.
897 <heading>Dependencies</heading>
900 Every package must specify the dependency information
901 about other packages that are required for the first to
905 For example, a dependency entry must be provided for any
906 shared libraries required by a dynamically-linked executable
907 binary in a package.</p>
910 Packages are not required to declare any dependencies they
911 have on other packages which are marked <tt>Essential</tt>
912 (see below), and should not do so unless they depend on a
913 particular version of that package.</p>
916 Sometimes, a package requires another package to be installed
917 <em>and</em> configured before it can be installed. In this
918 case, you must specify a <tt>Pre-Depends</tt> entry for
922 You should not specify a <tt>Pre-Depends</tt> entry for a
923 package before this has been discussed on the
924 <tt>debian-devel</tt> mailing list and a consensus about
925 doing that has been reached.</p></sect1>
928 <sect1 id="virtual_pkg">
929 <heading>Virtual packages</heading>
932 Sometimes, there are several packages which offer
933 more-or-less the same functionality. In this case, it's
934 useful to define a <em>virtual package</em> whose name
935 describes that common functionality. (The virtual
936 packages only exist logically, not physically; that's why
937 they are called <em>virtual</em>.) The packages with this
938 particular function will then <em>provide</em> the virtual
939 package. Thus, any other package requiring that function
940 can simply depend on the virtual package without having to
941 specify all possible packages individually.</p>
944 All packages should use virtual package names where
945 appropriate, and arrange to create new ones if necessary.
946 They should not use virtual package names (except privately,
947 amongst a cooperating group of packages) unless they have
948 been agreed upon and appear in the list of virtual package
949 names. (See also <ref id="virtual">)</p>
952 The latest version of the authoritative list of virtual
953 package names can be found in the <tt>debian-policy</tt> package.
954 It's also available from the Debian web mirrors at
955 <tt><url name="/doc/packaging-manuals/virtual-package-names-list.txt"
956 id="http://www.debian.org/doc/packaging-manuals/virtual-package-names-list.txt"></tt>
957 and from the Debian archive mirrors at
958 <tt><url name="/doc/package-developer/virtual-package-names-list.txt"
959 id="http://ftp.debian.org/debian/doc/package-developer/virtual-package-names-list.txt"></tt>.
963 The procedure for updating the list is described in the preface
970 <heading>Base system</heading>
973 The <tt>base system</tt> is a minimum subset of the Debian
974 GNU/Linux system that is installed before everything else
975 on a new system. Thus, only very few packages are allowed
976 to go into the <tt>base</tt> section to keep the required
977 disk usage very small.</p>
980 Most of these packages will have the priority value
981 <tt>required</tt> or at least <tt>important</tt>, and many
982 of them will be tagged <tt>essential</tt> (see below).</p>
989 <heading>Essential packages</heading>
992 Some packages are tagged <tt>essential</tt>. (They have
993 <tt>Essential: yes</tt> in their package control record.)
994 This flag is used for packages that are <em>essential</em>
998 Since these packages cannot be easily removed (one has to
999 specify an extra <em>force option</em> to
1000 <prgn>dpkg</prgn> to do so), this flag must not be used
1001 unless absolutely necessary. A shared library package
1002 must not be tagged <tt>essential</tt>; dependencies will
1003 prevent its premature removal, and we need to be able to
1004 remove it when it has been superseded.
1008 Since dpkg will not prevent upgrading of other packages
1009 while an <tt>essential</tt> package is in an unconfigured
1010 state, all <tt>essential</tt> packages must supply all of
1011 their core functionality even when unconfigured. If the
1012 package cannot satisfy this requirement it must not be
1013 tagged as essential, and any packages depending on this
1014 package must instead have explicit dependency fields as
1019 You must not tag any packages <tt>essential</tt> before
1020 this has been discussed on the <tt>debian-devel</tt>
1021 mailing list and a consensus about doing that has been
1026 <heading>Tasks</heading>
1029 The Debian install process allows the user to choose from
1030 a number of common tasks which a Debian system can be used to
1031 perform. Selecting a task with <prgn>tasksel</prgn> causes
1032 a set of packages that are useful in performing that task to be
1037 This set of packages is all available packages which have the
1038 name of the selected task in the <tt>Task</tt> field of their
1039 control file. The format of this field is a list of tasks,
1040 separated by commas.
1044 You should not tag any packages as belonging to a task
1045 before this has been discussed on the
1046 <em>debian-devel</em> mailing list and a consensus about
1047 doing that has been reached.
1051 For third parties (and historical reasons), tasksel also
1052 supports constructing tasks based on <em>task
1053 packages</em>. These are packages whose names begin with
1054 <em>task-</em>. Task packages should not be included in the
1059 <sect1 id="maintscripts">
1060 <heading>Maintainer Scripts</heading>
1063 The package installation scripts should avoid producing
1064 output which it is unnecessary for the user to see and
1065 should rely on <prgn>dpkg</prgn> to stave off boredom on
1066 the part of a user installing many packages. This means,
1067 amongst other things, using the <tt>--quiet</tt> option on
1068 <prgn>install-info</prgn>.</p>
1071 Errors which occur during the execution of an installation
1072 script must be checked and the installation must not
1073 continue after an error.
1077 Note that in general <ref id="scripts"> applies to package
1078 maintainer scripts, too.
1082 You should not use <prgn>dpkg-divert</prgn> on a file
1083 belonging to another package without consulting the
1084 maintainer of that package first.
1088 All packages which supply an instance of a common command
1089 name (or, in general, filename) should generally use
1090 <prgn>update-alternatives</prgn>, so that they may be
1091 installed together. If <prgn>update-alternatives</prgn>
1092 is not used, then each package must use
1093 <tt>Conflicts</tt> to ensure that other packages are
1094 de-installed. (In this case, it may be appropriate to
1095 specify a conflict against earlier versions of something
1096 that previously did not use
1097 <prgn>update-alternatives</prgn>; this is an exception to
1098 the usual rule that versioned conflicts should be
1104 <heading>Prompting in maintainer scripts</heading>
1106 Package maintainer scripts may prompt the user if
1107 necessary. Prompting may be accomplished by
1109 <p>From the Jasrgon file: by hand 2. By extension,
1110 writing code which does something in an explicit or
1111 low-level way for which a presupplied library
1112 (<em>debconf, in this instance</em>) routine ought
1113 to have been available.</p>
1114 </footnote> (but this is deprecated), or by
1115 communicating though a program, which conforms to the
1116 Debian Configuration management specification, version 2
1117 or higher (such as <prgn>debconf</prgn>). Thiss
1118 specification is included in the
1119 <file>debconf_specification</file> files in the
1120 <package>debian-policy</package> package. You may also
1121 find this file on the FTP site
1122 <ftpsite>ftp.debian.org</ftpsite> in
1123 <ftppath>/debian/doc/package-developer/debconf_specification.txt.gz</ftppath>
1124 or on your local mirror.<footnote>
1126 6% of Debian packages [see <url
1127 id="http://auric.debian.org/%7Ejoeyh/debconf-stats/data/"
1128 name="Debconf stats">] currently use
1129 <package>debconf</package> to prompt the user at
1130 install time, and this number is growing daily. The
1131 benefits of using debconf are briefly explained at
1133 id="http://kitenet.net/doc/debconf-doc/introduction.html"
1134 name="Debconf introduction">; they include
1135 preconfiguration, (mostly) noninteractive
1136 installation, elimination of redundant prompting,
1137 consistency of user interface, etc.
1140 With this increasing number of packages using
1141 <package>debconf</package>, plus the existance of a
1142 nascent second implementation of the Debian
1143 configuration management system
1144 (<package>cdebconf</package>), and the stabilization
1145 of the protocol these things use, the time has
1146 finally come to reflect the use of these things in
1153 Packages which use the Debian Configuration management
1154 specification may contain an additional
1155 <prgn>config</prgn> script and a <tt>templates</tt>
1156 file in their control archive. The <prgn>config</prgn>
1157 script might be run before the <prgn>preinst</prgn>
1158 script, and before the package is unpacked or any of its
1159 dependencies or pre-dependancies are satisfied.
1160 Therefore it must work using only the tools present in
1161 <em>essential</em> packages.<footnote>
1163 <package>Debconf</package> or another tool that
1164 implements the Debian Configuration management
1165 specification will also be installed, and any
1166 versioned dependencies on it will be satisfied
1167 before preconfiguration begins.
1173 Packages should try to minimize the amount of prompting
1174 they need to do, and they should ensure that the user
1175 will only ever be asked each question once. This means
1176 that packages should try to use appropriate shared
1177 configuration files (such as <file>/etc/papersize</file> and
1178 <file>/etc/news/server</file>), and shared
1179 <package>debconf</package> variables rather than each
1180 prompting for their own list of required pieces of
1185 It also means that an upgrade should not ask the same
1186 questions again, unless the user has used <tt>dpkg
1187 --purge</tt> to remove the package's configuration. The
1188 answers to configuration questions should be stored in an
1189 appropriate place in <file>/etc</file> so that the user can
1190 modify them, and how this has been done should be
1194 If a package has a vitally important piece of
1195 information to pass to the user (such as "don't run me
1196 as I am, you must edit the following configuration files
1197 first or you risk your system emitting badly-formatted
1198 messages"), it should display this in the
1199 <prgn>config</prgn> or <prgn>postinst</prgn> script and
1200 prompt the user to hit return to acknowledge the
1201 message. Copyright messages do not count as vitally
1202 important (they belong in
1203 <file>/usr/share/doc/<var>package</var>/copyright</file>);
1204 neither do instructions on how to use a program (these
1205 should be in on-line documentation, where all the users
1209 Any necessary prompting should almost always be confined
1210 to the <prgn>config</prgn> or <prgn>postinst</prgn>
1211 script. If it is done in the <prgn>postinst</prgn>, it
1212 should be protected with a conditional so that
1213 unnecessary prompting doesn't happen if a package's
1214 installation fails and the <prgn>postinst</prgn> is
1215 called with <tt>abort-upgrade</tt>,
1216 <tt>abort-remove</tt> or <tt>abort-deconfigure</tt>.</p>
1221 <heading>Source packages</heading>
1223 <sect1 id="standardsversion">
1224 <heading>Standards conformance</heading>
1227 In the source package's <tt>Standards-Version</tt> control
1228 field, you should specify the most recent version number
1229 of this policy document with which your package complied
1230 when it was last updated. The current version number is
1235 This information may be used to file bug reports
1236 automatically if your package becomes too much out of
1241 The version number has four components: major and minor
1242 version number and major and minor patch level. When the
1243 standards change in a way that requires every package to
1244 change the major number will be changed. Significant
1245 changes that will require work in many packages will be
1246 signaled by a change to the minor number. The major patch
1247 level will be changed for any change to the meaning of the
1248 standards, however small; the minor patch level will be
1249 changed when only cosmetic, typographical or other edits
1250 are made which neither change the meaning of the document
1251 nor affect the contents of packages.</p>
1254 Thus only the first three components of the policy version
1255 are significant in the <em>Standards-Version</em> control
1256 field, and so either these three components or the all
1257 four components may be specified.<footnote>
1259 In the past, people specified the full version number
1260 in the Standards-Version field, for example "2.3.0.0".
1261 Since minor patch-level changes don't introduce new
1262 policy, it was thought it would be better to relax
1263 policy and only require the first 3 components to be
1264 specified, in this example "2.3.0". All four
1265 components may still be used if someone wishes to do
1272 You should regularly, and especially if your package has
1273 become out of date, check for the newest Policy Manual
1274 available and update your package, if necessary. When your
1275 package complies with the new standards you should update the
1276 <tt>Standards-Version</tt> source package field and
1277 release it.<footnote>
1279 See the file <file>upgrading-checklist</file> for
1280 information about policy which has changed between
1281 different versions of this document.
1288 <sect1 id="pkg-relations">
1289 <heading>Package relationships</heading>
1292 Source packages should specify which binary packages they
1293 require to be installed or not to be installed in order to
1294 build correctly. For example, if building a package
1295 requires a certain compiler, then the compiler should be
1296 specified as a build-time dependency.
1300 It is not necessary to explicitly specify build-time
1301 relationships on a minimal set of packages that are always
1302 needed to compile, link and put in a Debian package a
1303 standard "Hello World!" program written in C or C++. The
1304 required packages are called <em>build-essential</em>, and
1305 an informational list can be found in
1306 <file>/usr/share/doc/build-essential/list</file> (which is
1307 contained in the <tt>build-essential</tt>
1310 <list compact="compact">
1312 <p>This allows maintaining the list separately
1313 from the policy documents (the list does not
1314 need the kind of control that the policy
1320 Having a separate package allows one to install
1321 the build-essential packages on a machine, as
1322 well as allowing other packages such as tasks to
1323 require installation of the build-essential
1324 packages using the depends relation.
1329 The separate package allows bug reports against
1330 the list to be categorized separately from
1331 the policy management process in the BTS.
1341 When specifying the set of build-time dependencies, one
1342 should list only those packages explicitly required by the
1343 build. It is not necessary to list packages which are
1344 required merely because some other package in the list of
1345 build-time dependencies depends on them.<footnote>
1347 The reason for this is that dependencies change, and
1348 you should list all those packages, and <em>only</em>
1349 those packages that <em>you</em> need directly. What
1350 others need is their business. For example, if you
1351 only link against <file>libimlib</file>, you will need to
1352 build-depend on <package>libimlib2-dev</package> but
1353 not against any <tt>libjpeg*</tt> packages, even
1354 though <tt>libimlib2-dev</tt> currently depends on
1355 them: installation of <package>libimlib2-dev</package>
1356 will automatically ensure that all of its run-time
1357 dependencies are satisfied.
1363 If build-time dependencies are specified, it must be
1364 possible to build the package and produce working binaries
1365 on a system with only essential and build-essential
1366 packages installed and also those required to satisfy the
1367 build-time relationships (including any implied
1368 relationships). In particular, this means that version
1369 clauses should be used rigorously in build-time
1370 relationships so that one cannot produce bad or
1371 inconsistently configured packages when the relationships
1372 are properly satisfied.
1376 <ref id="relationships"> explains the technical details.
1380 <heading>Changes to the upstream sources</heading>
1383 If changes to the source code are made that are not
1384 specific to the needs of the Debian system, they should be
1385 sent to the upstream authors in whatever form they prefer
1386 so as to be included in the upstream version of the
1390 If you need to configure the package differently for
1391 Debian or for Linux, and the upstream source doesn't
1392 provide a way to do so, you should add such configuration
1393 facilities (for example, a new <prgn>autoconf</prgn> test
1394 or <tt>#define</tt>) and send the patch to the upstream
1395 authors, with the default set to the way they originally
1396 had it. You can then easily override the default in your
1397 <file>debian/rules</file> or wherever is appropriate.</p>
1400 You should make sure that the <prgn>configure</prgn> utility
1401 detects the correct architecture specification string
1402 (refer to <ref id="arch-spec"> for details).</p>
1405 If you need to edit a <prgn>Makefile</prgn> where
1406 GNU-style <prgn>configure</prgn> scripts are used, you
1407 should edit the <file>.in</file> files rather than editing the
1408 <prgn>Makefile</prgn> directly. This allows the user to
1409 reconfigure the package if necessary. You should
1410 <em>not</em> configure the package and edit the generated
1411 <prgn>Makefile</prgn>! This makes it impossible for
1412 someone else to later reconfigure the package.</p>
1415 You should document your changes and updates to the source
1416 package properly in the <file>debian/changelog</file> file.
1417 For more information, please see <ref id="changelogs">.
1423 <heading>Error trapping in makefiles</heading>
1426 When <prgn>make</prgn> invokes a command in a makefile
1427 (including your package's upstream makefiles and
1428 <file>debian/rules</file>), it does so using <prgn>sh</prgn>. This
1429 means that <prgn>sh</prgn>'s usual bad error handling
1430 properties apply: if you include a miniature script as one
1431 of the commands in your makefile you'll find that if you
1432 don't do anything about it then errors are not detected
1433 and <prgn>make</prgn> will blithely continue after
1437 Every time you put more than one shell command (this
1438 includes using a loop) in a makefile command you
1439 must make sure that errors are trapped. For
1440 simple compound commands, such as changing directory and
1441 then running a program, using <tt>&&</tt> rather
1442 than semicolon as a command separator is sufficient. For
1443 more complex commands including most loops and
1444 conditionals you should include a separate <tt>set -e</tt>
1445 command at the start of every makefile command that's
1446 actually one of these miniature shell scripts.</p></sect1>
1450 <heading>Obsolete constructs and libraries</heading>
1453 The include file <tt><varargs.h></tt> is
1454 provided to support end-users compiling very old software;
1455 the library <tt>libtermcap</tt> is provided to support the
1456 execution of software which has been linked against it
1457 (either old programs or those such as Netscape which are
1458 only available in binary form).</p>
1461 Debian packages should be patched to use
1462 <tt><stdarg.h></tt> and <tt>ncurses</tt>
1469 <chapt id="controlfields"><heading>Control files and their fields</heading>
1472 Many of the tools in the package management suite manipulate
1473 data represented in a common format, known as <em>control
1474 data</em>. The data is often stored in <em>control
1475 files</em>. Binary and source packages have control files,
1476 and the <file>.changes</file> files which control the installation
1477 of uploaded files are also in control file format.
1478 <prgn>dpkg</prgn>'s internal databases are in a similar
1482 <sect id="controlsyntax"><heading>Syntax of control files</heading>
1485 A control file consists of one or more paragraphs of fields.
1486 The paragraphs are separated by blank lines. Some control
1487 files allow only one paragraph; others allow several, in
1488 which case each paragraph usually refers to a different
1489 package. (For example, in source packages, the first
1490 paragraph refers to the source package, and later paragraphs
1491 refer to binary packages generated from the source.)
1495 Each paragraph consists of a series of data fields; each
1496 field consists of the field name, followed by a colon and
1497 then the data/value associated with that field. It ends at
1498 the end of the line. Horizontal whitespace (spaces and
1499 tabs) may occur immediately before or after the value and is
1500 ignored there; it is conventional to put a single space
1501 after the colon. For example, a field might be:
1502 <example compact="compact">
1505 the field name is <tt>Package</tt> and the field value
1510 Some fields' values may span several lines; in this case
1511 each continuation line <em>must</em> start with a space or
1512 tab. Any trailing spaces or tabs at the end of individual
1513 lines of a field value are ignored.
1517 Except where otherwise stated only a single line of data is
1518 allowed and whitespace is not significant in a field body.
1519 Whitespace must not appear inside names (of packages,
1520 architectures, files or anything else) or version numbers,
1521 or between the characters of multi-character version
1526 Field names are not case-sensitive, but it is usual to
1527 capitalize the field names using mixed case as shown below.
1531 Blank lines, or lines consisting only of spaces and tabs,
1532 are not allowed within field values or between fields - that
1533 would mean a new paragraph.
1538 <sect><heading>List of fields</heading>
1540 This list here is not supposed to be exhaustive. Most fields
1541 are dealt with elsewhere in this document.
1543 <sect1 id="f-Package"><heading><tt>Package</tt>
1547 The name of the binary package. Package names consist of
1548 lower case letters (<tt>a-z</tt>), digits (<tt>0-9</tt>),
1549 plus (<tt>+</tt>) and minus (<tt>-</tt>) signs, and
1550 periods (<tt>.</tt>).
1554 They must be at least two characters long and must start
1555 with an alphanumeric character. The use of lowercase
1556 package names is required unless the package you're
1557 building (or referring to, in other fields) is already
1558 using uppercase characters.</p>
1561 <sect1 id="f-Version"><heading><tt>Version</tt>
1565 This lists the source or binary package's version number -
1566 see <ref id="versions">.
1572 id="f-Standards-Version"><heading><tt>Standards-Version</tt>
1576 The most recent version of the standards (the policy
1577 manual and associated texts) with which the package
1578 complies. This is updated manually when editing the
1579 source package to conform to newer standards; it can
1580 sometimes be used to tell when a package needs attention.
1581 Its format is described above; see
1582 <ref id="standardsversion">.
1587 <sect1 id="f-Distribution"><heading><tt>Distribution</tt>
1591 In a <file>.changes</file> file or parsed changelog output
1592 this contains the (space-separated) name(s) of the
1593 distribution(s) where this version of the package should
1594 be installed. Valid distributions are determined by the
1595 archive maintainers.<footnote>
1596 Current distribution names are:
1597 <taglist compact="compact">
1598 <tag><em>stable</em></tag>
1601 This is the current "released" version of Debian
1602 GNU/Linux. Once the distribution is
1603 <em>stable</em> only security fixes and other
1604 major bug fixes are allowed. When changes are
1605 made to this distribution, the release number is
1606 increased (for example: 2.2r1 becomes 2.2r2 then
1611 <tag><em>unstable</em></tag>
1614 This distribution value refers to the
1615 <em>developmental</em> part of the Debian
1616 distribution tree. New packages, new upstream
1617 versions of packages and bug fixes go into the
1618 <em>unstable</em> directory tree. Download from
1619 this distribution at your own risk.
1623 <tag><em>testing</em></tag>
1626 This distribution value refers to the
1627 <em>testing</em> part of the Debian distribution
1628 tree. It receives its packages from the
1629 unstable distribution after a short time lag to
1630 ensure that there are no major issues with the
1631 unstable packages. It is less prone to breakage
1632 than unstable, but still risky. It is not
1633 possible to upload packages directly to
1638 <tag><em>frozen</em></tag>
1641 From time to time, the <em>testing</em>
1642 distribution enters a state of "code-freeze" in
1643 anticipation of release as a <em>stable</em>
1644 version. During this period of testing only
1645 fixes for existing or newly-discovered bugs will
1646 be allowed. The exact details of this stage are
1647 determined by the Release Manager.
1651 <tag><em>experimental</em></tag>
1654 The packages with this distribution value are
1655 deemed by their maintainers to be high
1656 risk. Oftentimes they represent early beta or
1657 developmental packages from various sources that
1658 the maintainers want people to try, but are not
1659 ready to be a part of the other parts of the
1660 Debian distribution tree. Download at your own
1666 You should list <em>all</em> distributions that the
1667 package should be installed into.
1676 <chapt id="versions"><heading>Version numbering</heading>
1679 Every package has a version number recorded in its
1680 <tt>Version</tt> control file field.
1684 The package management system imposes an ordering on version
1685 numbers, so that it can tell whether packages are being up- or
1686 downgraded and so that package system front end applications
1687 can tell whether a package it finds available is newer than
1688 the one installed on the system. The version number format
1689 has the most significant parts (as far as comparison is
1690 concerned) at the beginning.
1694 The version number format is:
1695 [<var>epoch</var><tt>:</tt>]<var>upstream_version</var>[<tt>-</tt><var>debian_revision</var>]
1699 The three components here are:
1701 <tag><var>epoch</var></tag>
1704 This is a single (generally small) unsigned integer. It
1705 may be omitted, in which case zero is assumed. If it is
1706 omitted then the <var>upstream_version</var> may not
1711 It is provided to allow mistakes in the version numbers
1712 of older versions of a package, and also a package's
1713 previous version numbering schemes, to be left behind.
1717 <tag><var>upstream_version</var></tag>
1720 This is the main part of the version number. It is
1721 usually the version number of the original ("upstream")
1722 package from which the <file>.deb</file> file has been made,
1723 if this is applicable. Usually this will be in the same
1724 format as that specified by the upstream author(s);
1725 however, it may need to be reformatted to fit into the
1726 package management system's format and comparison
1731 The comparison behavior of the package management system
1732 with respect to the <var>upstream_version</var> is
1733 described below. The <var>upstream_version</var>
1734 portion of the version number is mandatory.
1738 The <var>upstream_version</var> may contain only
1739 alphanumerics<footnote>
1740 <p>Alphanumerics are <tt>A-Za-z0-9</tt> only.</p>
1742 and the characters <tt>.</tt> <tt>+</tt> <tt>-</tt>
1743 <tt>:</tt> (full stop, plus, hyphen, colon) and should
1744 start with a digit. If there is no
1745 <var>debian_revision</var> then hyphens are not allowed;
1746 if there is no <var>epoch</var> then colons are not
1750 <tag><var>debian_revision</var></tag>
1753 This part of the version number specifies the version of
1754 the Debian package based on the upstream version. It
1755 may contain only alphanumerics and the characters
1756 <tt>+</tt> and <tt>.</tt> (plus and full stop) and is
1757 compared in the same way as the
1758 <var>upstream_version</var> is.
1762 It is optional; if it isn't present then the
1763 <var>upstream_version</var> may not contain a hyphen.
1764 This format represents the case where a piece of
1765 software was written specifically to be turned into a
1766 Debian package, and so there is only one "debianization"
1767 of it and therefore no revision indication is required.
1771 It is conventional to restart the
1772 <var>debian_revision</var> at <tt>1</tt> each time the
1773 <var>upstream_version</var> is increased.
1777 The package management system will break the version
1778 number apart at the last hyphen in the string (if there
1779 is one) to determine the <var>upstream_version</var> and
1780 <var>debian_revision</var>. The absence of a
1781 <var>debian_revision</var> compares earlier than the
1782 presence of one (but note that the
1783 <var>debian_revision</var> is the least significant part
1784 of the version number).
1791 The <var>upstream_version</var> and <var>debian_revision</var>
1792 parts are compared by the package management system using the
1797 The strings are compared from left to right.
1801 First the initial part of each string consisting entirely of
1802 non-digit characters is determined. These two parts (one of
1803 which may be empty) are compared lexically. If a difference
1804 is found it is returned. The lexical comparison is a
1805 comparison of ASCII values modified so that all the letters
1806 sort earlier than all the non-letters.
1810 Then the initial part of the remainder of each string which
1811 consists entirely of digit characters is determined. The
1812 numerical values of these two parts are compared, and any
1813 difference found is returned as the result of the comparison.
1814 For these purposes an empty string (which can only occur at
1815 the end of one or both version strings being compared) counts
1820 These two steps (comparing and removing initial non-digit
1821 strings and initial digit strings) are repeated until a
1822 difference is found or both strings are exhausted.
1826 Note that the purpose of epochs is to allow us to leave behind
1827 mistakes in version numbering, and to cope with situations
1828 where the version numbering scheme changes. It is
1829 <em>not</em> intended to cope with version numbers containing
1830 strings of letters which the package management system cannot
1831 interpret (such as <tt>ALPHA</tt> or <tt>pre-</tt>), or with
1832 silly orderings (the author of this manual has heard of a
1833 package whose versions went <tt>1.1</tt>, <tt>1.2</tt>,
1834 <tt>1.3</tt>, <tt>1</tt>, <tt>2.1</tt>, <tt>2.2</tt>,
1835 <tt>2</tt> and so forth).
1839 If an upstream package has problematic version numbers they
1840 should be converted to a sane form for use in the
1841 <tt>Version</tt> field.
1845 <heading>Version numbers based on dates</heading>
1847 In general, Debian packages should use the same version
1848 numbers as the upstream sources.</p>
1851 However, in some cases where the upstream version number is
1852 based on a date (e.g., a development "snapshot" release) the
1853 package management system cannot handle these version
1854 numbers without epochs. For example, dpkg will consider
1855 "96May01" to be greater than "96Dec24".</p>
1858 To prevent having to use epochs for every new upstream
1859 version, the version number should be changed to the
1860 following format in such cases: "19960501", "19961224". It
1861 is up to the maintainer whether he/she wants to bother the
1862 upstream maintainer to change the version numbers upstream,
1866 Note that other version formats based on dates which are
1867 parsed correctly by the package management system should
1868 <em>not</em> be changed.</p>
1871 Native Debian packages (i.e., packages which have been
1872 written especially for Debian) whose version numbers include
1873 dates should always use the "YYYYMMDD" format.</p>
1877 <chapt id="miscellaneous"><heading>Packaging Considerations</heading>
1879 <sect id="timestamps"><heading>Time Stamps</heading>
1881 Maintainers should preserve the modification times of the
1882 upstream source files in a package, as far as is reasonably
1885 The rationale is that there is some information conveyed
1886 by knowing the age of the file, for example, you could
1887 recognize that some documentation is very old by looking
1888 at the modification time, so it would be nice if the
1889 modification time of the upstream source would be
1896 <sect id="debianrules"><heading><file>debian/rules</file> - the
1897 main building script</heading>
1900 This file must be an executable makefile, and contains the
1901 package-specific recipes for compiling the package and
1902 building binary package(s) from the source.
1906 It must start with the line <tt>#!/usr/bin/make -f</tt>,
1907 so that it can be invoked by saying its name rather than
1908 invoking <prgn>make</prgn> explicitly.
1912 Since an interactive <file>debian/rules</file> script makes it
1913 impossible to auto-compile that package and also makes it
1914 hard for other people to reproduce the same binary
1915 package, all <em>required targets</em> MUST be
1916 non-interactive. At a minimum, required targets are the
1917 ones called by <prgn>dpkg-buildpackage</prgn>, namely,
1918 <em>clean</em>, <em>binary</em>, <em>binary-arch</em>,
1919 <em>binary-indep</em>, and <em>build</em>. It also follows
1920 that any target that these targets depend on must also be
1925 The required and optional targets are as follows:
1927 <tag><tt>build</tt>, <tt>build-arch</tt> (optional),
1928 <tt>build-indep</tt> (optional)</tag>
1931 The <tt>build</tt> target should perform all
1932 non-interactive configuration and compilation of the
1933 package. If a package has an interactive pre-build
1934 configuration routine, the Debianized source package
1935 must either be built after this has taken place (so
1936 that the binary package can be built without rerunning
1937 the configuration) or the configuration routine
1938 modified to become non-interactive. (The latter is
1939 preferable if there are architecture-specific features
1940 detected by the configuration routine.)
1944 For some packages, notably ones where the same
1945 source tree is compiled in different ways to produce
1946 two binary packages, the <tt>build</tt> target
1947 does not make much sense. For these packages it is
1948 good enough to provide two (or more) targets
1949 (<tt>build-a</tt> and <tt>build-b</tt> or whatever)
1950 for each of the ways of building the package, and a
1951 <tt>build</tt> target that does nothing. The
1952 <tt>binary</tt> target will have to build the
1953 package in each of the possible ways and make the
1954 binary package out of each.
1958 The <tt>build</tt> target must not do anything
1959 that might require root privilege.
1963 The <tt>build</tt> target may need to run the
1964 <tt>clean</tt> target first - see below.
1968 When a package has a configuration and build routine
1969 which takes a long time, or when the makefiles are
1970 poorly designed, or when <tt>build</tt> needs to
1971 run <tt>clean</tt> first, it is a good idea to
1972 <tt>touch build</tt> when the build process is
1973 complete. This will ensure that if <tt>debian/rules
1974 build</tt> is run again it will not rebuild the whole
1977 Another common way to do this is for <tt>build</tt>
1978 to depend on <prgn>build-stamp</prgn> and to do
1979 nothing else, and for the <prgn>build-stamp</prgn>
1980 target to do the building and to <tt>touch
1981 build-stamp</tt> on completion. This is
1982 especially useful if the build routine creates a
1983 file or directory called <tt>build</tt>; in such a
1984 case, <tt>build</tt> will need to be listed as
1985 a phony target (i.e., as a dependency of the
1986 <tt>.PHONY</tt> target). See the documentation of
1987 <prgn>make</prgn> for more information on phony
1994 <tag><tt>binary</tt>, <tt>binary-arch</tt>,
1995 <tt>binary-indep</tt>
1999 The <tt>binary</tt> target must be all that is
2000 necessary for the user to build the binary package(s)
2001 produced from this source package. All of these
2002 targets are required to be non-interactive. It is
2003 split into two parts: <prgn>binary-arch</prgn> builds
2004 the binary packages which are specific to a particular
2005 architecture, and <tt>binary-indep</tt> builds
2006 those which are not.
2009 <tt>binary</tt> may be (and commonly is) a target with
2010 no commands which simply depends on
2011 <tt>binary-arch</tt> and <tt>binary-indep</tt>.
2014 Both <tt>binary-*</tt> targets should depend on the
2015 <tt>build</tt> target, or on the appropriate
2016 <tt>build-arch</tt> or <tt>build-indep</tt> target, if
2017 provided, so that the package is built if it has not
2018 been already. It should then create the relevant
2019 binary package(s), using <prgn>dpkg-gencontrol</prgn> to
2020 make their control files and <prgn>dpkg-deb</prgn> to
2021 build them and place them in the parent of the top
2026 Both the <tt>binary-arch</tt> and
2027 <tt>binary-indep</tt> targets <em>must</em> exist.
2028 If one of them has nothing to do (which will always be
2029 the case if the source generates only a single binary
2030 package, whether architecture-dependent or not), it
2031 must still exist and must always succeed.
2035 The <tt>binary</tt> targets must be invoked as
2038 The <prgn>fakeroot</prgn> package often allows one
2039 to build a package correctly even without being
2046 <tag><tt>clean</tt></tag>
2049 This must undo any effects that the <tt>build</tt>
2050 and <tt>binary</tt> targets may have had, except
2051 that it should leave alone any output files created in
2052 the parent directory by a run of a <tt>binary</tt>
2053 target. This target must be non-interactive.
2057 If a <tt>build</tt> file is touched at the end of
2058 the <tt>build</tt> target, as suggested above, it
2059 should be removed as the first action that
2060 <tt>clean</tt> performs, so that running
2061 <tt>build</tt> again after an interrupted
2062 <tt>clean</tt> doesn't think that everything is
2067 The <tt>clean</tt> target may need to be
2068 invoked as root if <tt>binary</tt> has been
2069 invoked since the last <tt>clean</tt>, or if
2070 <tt>build</tt> has been invoked as root (since
2071 <tt>build</tt> may create directories, for
2076 <tag><tt>get-orig-source</tt> (optional)</tag>
2079 This target fetches the most recent version of the
2080 original source package from a canonical archive site
2081 (via FTP or WWW, for example), does any necessary
2082 rearrangement to turn it into the original source
2083 tar file format described below, and leaves it in the
2088 This target may be invoked in any directory, and
2089 should take care to clean up any temporary files it
2094 This target is optional, but providing it if
2095 possible is a good idea.
2101 The <tt>build</tt>, <tt>binary</tt> and
2102 <tt>clean</tt> targets must be invoked with the current
2103 directory being the package's top-level directory.
2108 Additional targets may exist in <file>debian/rules</file>,
2109 either as published or undocumented interfaces or for the
2110 package's internal use.
2114 The architectures we build on and build for are determined
2115 by <prgn>make</prgn> variables using the utility
2116 <prgn>dpkg-architecture</prgn>. You can determine the
2117 Debian architecture and the GNU style architecture
2118 specification string for the build machine (the machine type
2119 we are building on) as well as for the host machine (the
2120 machine type we are building for). Here is a list of
2121 supported <prgn>make</prgn> variables:
2122 <list compact="compact">
2124 <p><tt>DEB_*_ARCH</tt> (the Debian architecture)</p>
2127 <p><tt>DEB_*_GNU_TYPE</tt> (the GNU style architecture
2128 specification string)</p>
2131 <p><tt>DEB_*_GNU_CPU</tt> (the CPU part of
2132 <tt>DEB_*_GNU_TYPE</tt>)</p>
2135 <p><tt>DEB_*_GNU_SYSTEM</tt> (the System part of
2136 <tt>DEB_*_GNU_TYPE</tt>)</p>
2138 where <tt>*</tt> is either <tt>BUILD</tt> for specification of
2139 the build machine or <tt>HOST</tt> for specification of the
2144 Backward compatibility can be provided in the rules file
2145 by setting the needed variables to suitable default
2146 values; please refer to the documentation of
2147 <prgn>dpkg-architecture</prgn> for details.
2151 It is important to understand that the <tt>DEB_*_ARCH</tt>
2152 string only determines which Debian architecture we are
2153 building on or for. It should not be used to get the CPU
2154 or system information; the GNU style variables should be
2159 <sect id="dpkgchangelog"><heading><file>debian/changelog</file>
2163 This file records the changes to the Debian-specific parts of the
2166 Though there is nothing stopping an author who is also
2167 the Debian maintainer from using it for all their
2168 changes, it will have to be renamed if the Debian and
2169 upstream maintainers become different people. In such a
2170 case, however, it might be better to maintain the
2171 package as a non-native package.
2177 It has a special format which allows the package building
2178 tools to discover which version of the package is being
2179 built and find out other release-specific information.
2183 That format is a series of entries like this:
2184 <example compact="compact">
2185 <var>package</var> (<var>version</var>) <var>distribution(s)</var>; urgency=<var>urgency</var>
2187 <p>[optional blank line(s), stripped]</p>
2189 * <var>change details</var>
2190 <var>more change details</var>
2192 <p>[blank line(s), included in output of dpkg-parsechangelog]</p>
2194 * <var>even more change details</var>
2196 <p>[optional blank line(s), stripped]</p>
2198 -- <var>maintainer name</var> <<var>email
2199 address</var>><var>[two spaces]</var> <var>date</var>
2204 <var>package</var> and <var>version</var> are the source
2205 package name and version number.
2209 <var>distribution(s)</var> lists the distributions where
2210 this version should be installed when it is uploaded - it
2211 is copied to the <tt>Distribution</tt> field in the
2212 <file>.changes</file> file. See <ref id="f-Distribution">.
2216 <var>urgency</var> is the value for the <tt>Urgency</tt>
2217 field in the <file>.changes</file> file for the upload. It is
2218 not possible to specify an urgency containing commas; commas
2219 are used to separate
2220 <tt><var>keyword</var>=<var>value</var></tt> settings in the
2221 <prgn>dpkg</prgn> changelog format (though there is
2222 currently only one useful <var>keyword</var>,
2223 <tt>urgency</tt>).<footnote>
2225 Recognised urgency values are <tt>low</tt>,
2226 <tt>medium</tt>, <tt>high</tt> and <tt>emergency</tt>.
2227 They have an effect on how quickly a package will be
2228 considered for inclusion into the <tt>testing</tt>
2229 distribution, and give an indication of the importance
2230 of any fixes included in this upload.
2236 The change details may in fact be any series of lines
2237 starting with at least two spaces, but conventionally each
2238 change starts with an asterisk and a separating space and
2239 continuation lines are indented so as to bring them in
2240 line with the start of the text above. Blank lines may be
2241 used here to separate groups of changes, if desired.
2245 If this upload resolves bugs recorded in the Bug Tracking
2246 System (BTS), they may be automatically closed on the
2247 inclusion of this package into the Debian archive by
2248 including the string: <tt>closes: Bug#<var>nnnnn</var></tt>
2249 in the change details.<footnote>
2251 To be precise, the string should match the following
2252 Perl regular expression:
2254 /closes:\s*(?:bug)?\#?\s?\d+(?:,\s*(?:bug)?\#?\s?\d+)*/i
2256 Then all of the bug numbers listed will be closed by the
2257 archive maintenance script (<prgn>katie</prgn>), or in
2258 the case of an NMU, marked as fixed.
2264 The maintainer name and email address used in the changelog
2265 should be the details of the person uploading <em>this</em>
2266 version. They are <em>not</em> necessarily those of the
2267 usual package maintainer. The information here will be
2268 copied to the <tt>Changed-By</tt> field in the
2269 <tt>.changes</tt> file, and then later used to send an
2270 acknowledgement when the upload has been installed.
2274 The <var>date</var> should be in RFC822 format<footnote>
2276 This is generated by the <prgn>822-date</prgn>
2279 </footnote>; it should include the time zone specified
2280 numerically, with the time zone name or abbreviation
2281 optionally present as a comment in parentheses.
2285 The first "title" line with the package name should start
2286 at the left hand margin; the "trailer" line with the
2287 maintainer and date details should be preceded by exactly
2288 one space. The maintainer details and the date must be
2289 separated by exactly two spaces.
2292 <sect1><heading>Defining alternative changelog formats</heading>
2295 It is possible to use a different format to the standard
2296 one, by providing a parser for the format you wish to
2300 A changelog parser must not interact with the user at
2306 <!-- FIXME: section pkg-srcsubstvars is the same as srcsubstvars -->
2308 <sect id="srcsubstvars"><heading><file>debian/substvars</file>
2309 and variable substitutions </heading>
2312 When <prgn>dpkg-gencontrol</prgn>,
2313 <prgn>dpkg-genchanges</prgn> and <prgn>dpkg-source</prgn>
2314 generate control files they perform variable substitutions
2315 on their output just before writing it. Variable
2316 substitutions have the form <tt>${<var>variable</var>}</tt>.
2317 The optional file <file>debian/substvars</file> contains
2318 variable substitutions to be used; variables can also be set
2319 directly from <file>debian/rules</file> using the <tt>-V</tt>
2320 option to the source packaging commands, and certain
2321 predefined variables are also available.
2325 The <file>debian/substvars</file> file is usually generated and
2326 modified dynamically by <file>debian/rules</file> targets, in
2327 which case it must be removed by the <tt>clean</tt> target.
2331 See <manref name="dpkg-source" section="1"> for full
2332 details about source variable substitutions, including the
2333 format of <file>debian/substvars</file>.</p>
2336 <sect id="debianfiles"><heading><file>debian/files</file>
2340 This file is not a permanent part of the source tree; it
2341 is used while building packages to record which files are
2342 being generated. <prgn>dpkg-genchanges</prgn> uses it
2343 when it generates a <file>.changes</file> file.
2347 It should not exist in a shipped source package, and so it
2348 (and any backup files or temporary files such as
2349 <file>files.new</file><footnote>
2351 <file>files.new</file> is used as a temporary file by
2352 <prgn>dpkg-gencontrol</prgn> and
2353 <prgn>dpkg-distaddfile</prgn> - they write a new
2354 version of <tt>files</tt> here before renaming it,
2355 to avoid leaving a corrupted copy if an error
2358 </footnote>) should be removed by the
2359 <tt>clean</tt> target. It may also be wise to
2360 ensure a fresh start by emptying or removing it at the
2361 start of the <tt>binary</tt> target.
2365 When <prgn>dpkg-gencontrol</prgn> is run for a binary
2366 package, it adds an entry to <file>debian/files</file> for the
2367 <file>.deb</file> file that will be created when <tt>dpkg-deb
2368 --build</tt> is run for that binary package. So for most
2369 packages all that needs to be done with this file is to
2370 delete it in the <tt>clean</tt> target.
2374 If a package upload includes files besides the source
2375 package and any binary packages whose control files were
2376 made with <prgn>dpkg-gencontrol</prgn> then they should be
2377 placed in the parent of the package's top-level directory
2378 and <prgn>dpkg-distaddfile</prgn> should be called to add
2379 the file to the list in <file>debian/files</file>.</p>
2382 <sect id="restrictions"><heading>Restrictions on objects in source packages
2386 The source package may not contain any hard links<footnote>
2388 This is not currently detected when building source
2389 packages, but only when extracting
2393 Hard links may be permitted at some point in the
2394 future, but would require a fair amount of
2397 </footnote>, device special files, sockets or setuid or
2398 setgid files.<footnote>
2400 Setgid directories are allowed.
2406 <sect id="descriptions"><heading>Descriptions of packages - the
2407 <tt>Description</tt> field</heading>
2410 The "Description" control file field consists of two parts,
2411 the synopsis or the short description, and the long description.
2412 The field's format is as follows:
2416 Description: <single line synopsis>
2417 <extended description over several lines>
2421 The description is intended to describe the program to a user
2422 who has never met it before so that they know whether they
2423 want to install it. It should also give information about the
2424 significant dependencies and conflicts between this package
2425 and others, so that the user knows why these dependencies and
2426 conflicts have been declared.
2430 Put important information first, both in the synopsis and
2431 extended description. Sometimes only the first part of the
2432 synopsis or of the description will be displayed. You can
2433 assume that there will usually be a way to see the whole
2434 extended description.
2437 <sect1 id="synopsis"><heading>The single line synopsis</heading>
2440 The single line synopsis should be kept brief - certainly
2441 under 80 characters.
2445 Do not include the package name in the synopsis line. The
2446 display software knows how to display this already, and you
2447 do not need to state it. Remember that in many situations
2448 the user may only see the synopsis line - make it as
2449 informative as you can.
2454 <sect1 id="extendeddesc"><heading>The extended description</heading>
2457 Do not try to continue the single line synopsis into the
2458 extended description. This will not work correctly when
2459 the full description is displayed, and makes no sense
2460 where only the summary (the single line synopsis) is
2465 The extended description should describe what the package
2466 does and how it relates to the rest of the system (in terms
2467 of, for example, which subsystem it is which part of).
2471 The description field needs to make sense to anyone, even
2472 people who have no idea about any of the things the
2473 package deals with.<footnote>
2474 The blurb that comes with a program in its
2475 announcements and/or <prgn>README</prgn> files is
2476 rarely suitable for use in a description. It is
2477 usually aimed at people who are already in the
2478 community where the package is used.
2483 The lines in the extended description can have these formats:
2489 Those starting with a single space are part of a paragraph.
2490 Successive lines of this form will be word-wrapped when
2491 displayed. The leading space will usually be stripped off.
2495 Those starting with two or more spaces. These will be
2496 displayed verbatim. If the display cannot be panned
2497 horizontally, the displaying program will linewrap them "hard"
2498 (i.e., without taking account of word breaks). If it can they
2499 will be allowed to trail off to the right. None, one or two
2500 initial spaces may be deleted, but the number of spaces
2501 deleted from each line will be the same (so that you can have
2502 indenting work correctly, for example).
2506 Those containing a single space followed by a single full stop
2507 character. These are rendered as blank lines. This is the
2508 <em>only</em> way to get a blank line<footnote>
2509 Completely empty lines will not be rendered as blank lines.
2510 Instead, they will cause the parser to think you're starting
2511 a whole new record in the control file, and will therefore
2512 likely abort with an error.
2517 Those containing a space, a full stop and some more characters.
2518 These are for future expansion. Do not use them.
2524 Do not use tab characters. Their effect is not predictable.
2534 <chapt id="maintainerscripts"><heading>Package maintainer scripts
2535 and installation procedure
2538 <sect><heading>Introduction to package maintainer scripts
2542 It is possible to supply scripts as part of a package which
2543 the package management system will run for you when your
2544 package is installed, upgraded or removed.
2548 These scripts are the files <prgn>preinst</prgn>,
2549 <prgn>postinst</prgn>, <prgn>prerm</prgn> and <prgn>postrm</prgn> in the
2550 control area of the package. They must be proper executable
2551 files; if they are scripts (which is recommended), they must
2552 start with the usual <tt>#!</tt> convention. They should be
2553 readable and executable by anyone, and not world-writable.
2557 The package management system looks at the exit status from
2558 these scripts. It is important that they exit with a
2559 non-zero status if there is an error, so that the package
2560 management system can stop its processing. For shell
2561 scripts this means that you <em>almost always</em> need to
2562 use <tt>set -e</tt> (this is usually true when writing shell
2563 scripts, in fact). It is also important, of course, that
2564 they don't exit with a non-zero status if everything went
2569 When a package is upgraded a combination of the scripts from
2570 the old and new packages is called during the upgrade
2571 procedure. If your scripts are going to be at all
2572 complicated you need to be aware of this, and may need to
2573 check the arguments to your scripts.
2577 Broadly speaking the <prgn>preinst</prgn> is called before
2578 (a particular version of) a package is installed, and the
2579 <prgn>postinst</prgn> afterwards; the <prgn>prerm</prgn>
2580 before (a version of) a package is removed and the
2581 <prgn>postrm</prgn> afterwards.
2585 Programs called from maintainer scripts should not normally
2586 have a path prepended to them. Before installation is
2587 started, the package management system checks to see if the
2588 programs <prgn>ldconfig</prgn>,
2589 <prgn>start-stop-daemon</prgn>, <prgn>install-info</prgn>,
2590 and <prgn>update-rc.d</prgn> can be found via the
2591 <tt>PATH</tt> environment variable. Those programs, and any
2592 other program that one would expect to be on the
2593 <tt>PATH</tt>, should thus be invoked without an absolute
2594 pathname. Maintainer scripts should also not reset the
2595 <tt>PATH</tt>, though they might choose to modify it by
2596 prepending or appending package-specific directories. These
2597 considerations really apply to all shell scripts.</p>
2601 <heading>Maintainer scripts Idempotency</heading>
2604 It is necessary for the error recovery procedures that the
2605 scripts be idempotent. This means that if it is run
2606 successfully, and then it is called again, it doesn't bomb
2607 out or cause any harm, but just ensures that everything is
2608 the way it ought to be. If the first call failed, or
2609 aborted half way through for some reason, the second call
2610 should merely do the things that were left undone the first
2611 time, if any, and exit with a success status if everything
2614 This is so that if an error occurs, the user interrupts
2615 <prgn>dpkg</prgn> or some other unforeseen circumstance
2616 happens you don't leave the user with a badly-broken
2617 package when <prgn>dpkg</prgn> attempts to repeat the
2625 <heading>Controlling terminal for maintainer scripts</heading>
2628 The maintainer scripts are guaranteed to run with a
2629 controlling terminal and can interact with the user.
2630 If they need to prompt for passwords, do full-screen
2631 interaction or something similar you should do these
2632 things to and from <file>/dev/tty</file>, since
2633 <prgn>dpkg</prgn> will at some point redirect scripts'
2634 standard input and output so that it can log the
2635 installation process. Likewise, because these scripts
2636 may be executed with standard output redirected into a
2637 pipe for logging purposes, Perl scripts should set
2638 unbuffered output by setting <tt>$|=1</tt> so that the
2639 output is printed immediately rather than being
2644 Each script should return a zero exit status for
2645 success, or a nonzero one for failure.
2649 <sect id="mscriptsinstact"><heading>Summary of ways maintainer
2654 <list compact="compact">
2656 <p><var>new-preinst</var> <tt>install</tt></p>
2659 <p><var>new-preinst</var> <tt>install</tt>
2660 <var>old-version</var></p>
2663 <p><var>new-preinst</var> <tt>upgrade</tt>
2664 <var>old-version</var></p>
2667 <p><var>old-preinst</var> <tt>abort-upgrade</tt>
2668 <var>new-version</var>
2674 <list compact="compact">
2676 <p><var>postinst</var> <tt>configure</tt>
2677 <var>most-recently-configured-version</var></p>
2680 <p><var>old-postinst</var> <tt>abort-upgrade</tt>
2681 <var>new-version</var></p>
2684 <p><var>conflictor's-postinst</var> <tt>abort-remove</tt>
2685 <tt>in-favour</tt> <var>package</var>
2686 <var>new-version</var></p>
2690 <var>deconfigured's-postinst</var>
2691 <tt>abort-deconfigure</tt> <tt>in-favour</tt>
2692 <var>failed-install-package</var> <var>version</var>
2693 <tt>removing</tt> <var>conflicting-package</var>
2700 <list compact="compact">
2702 <p><var>prerm</var> <tt>remove</tt></p>
2705 <p><var>old-prerm</var> <tt>upgrade</tt>
2706 <var>new-version</var></p>
2709 <p><var>new-prerm</var> <tt>failed-upgrade</tt>
2710 <var>old-version</var></p>
2713 <p><var>conflictor's-prerm</var> <tt>remove</tt>
2714 <tt>in-favour</tt> <var>package</var>
2715 <var>new-version</var></p>
2719 <var>deconfigured's-prerm</var> <tt>deconfigure</tt>
2720 <tt>in-favour</tt> <var>package-being-installed</var>
2721 <var>version</var> <tt>removing</tt>
2722 <var>conflicting-package</var>
2729 <list compact="compact">
2731 <p><var>postrm</var> <tt>remove</tt></p>
2734 <p><var>postrm</var> <tt>purge</tt></p>
2738 <var>old-postrm</var> <tt>upgrade</tt>
2739 <var>new-version</var></p>
2742 <p><var>new-postrm</var> <tt>failed-upgrade</tt>
2743 <var>old-version</var></p>
2746 <p><var>new-postrm</var> <tt>abort-install</tt></p>
2749 <p><var>new-postrm</var> <tt>abort-install</tt>
2750 <var>old-version</var></p>
2753 <p><var>new-postrm</var> <tt>abort-upgrade</tt>
2754 <var>old-version</var></p>
2758 <var>disappearer's-postrm</var> <tt>disappear</tt>
2759 <var>overwriter</var>
2760 <var>overwriter-version</var></p></item>
2765 <sect id="unpackphase"><heading>Details of unpack phase of
2766 installation or upgrade
2770 The procedure on installation/upgrade/overwrite/disappear
2771 (i.e., when running <tt>dpkg --unpack</tt>, or the unpack
2772 stage of <tt>dpkg --install</tt>) is as follows. In each
2773 case, if a major error occurs (unless listed below) the
2774 actions are, in general, run backwards - this means that the
2775 maintainer scripts are run with different arguments in
2776 reverse order. These are the "error unwind" calls listed
2784 <p>If a version of the package is already
2786 <example compact="compact">
2787 <var>old-prerm</var> upgrade <var>new-version</var>
2792 If the script runs but exits with a non-zero
2793 exit status, <prgn>dpkg</prgn> will attempt:
2794 <example compact="compact">
2795 <var>new-prerm</var> failed-upgrade <var>old-version</var>
2797 Error unwind, for both the above cases:
2798 <example compact="compact">
2799 <var>old-postinst</var> abort-upgrade <var>new-version</var>
2807 <p>If a "conflicting" package is being removed at the same time:
2811 If any packages depended on that conflicting
2812 package and <tt>--auto-deconfigure</tt> is
2813 specified, call, for each such package:
2814 <example compact="compact">
2815 <var>deconfigured's-prerm</var> deconfigure \
2816 in-favour <var>package-being-installed</var> <var>version</var> \
2817 removing <var>conflicting-package</var> <var>version</var>
2820 <example compact="compact">
2821 <var>deconfigured's-postinst</var> abort-deconfigure \
2822 in-favour <var>package-being-installed-but-failed</var> <var>version</var> \
2823 removing <var>conflicting-package</var> <var>version</var>
2825 The deconfigured packages are marked as
2826 requiring configuration, so that if
2827 <tt>--install</tt> is used they will be
2828 configured again if possible.</p>
2831 <p>To prepare for removal of the conflicting package, call:
2832 <example compact="compact">
2833 <var>conflictor's-prerm</var> remove \
2834 in-favour <var>package</var> <var>new-version</var>
2837 <example compact="compact">
2838 <var>conflictor's-postinst</var> abort-remove \
2839 in-favour <var>package</var> <var>new-version</var>
2850 <p>If the package is being upgraded, call:
2851 <example compact="compact">
2852 <var>new-preinst</var> upgrade <var>old-version</var>
2857 Otherwise, if the package had some configuration
2858 files from a previous version installed (i.e., it
2859 is in the "configuration files only" state):
2860 <example compact="compact">
2861 <var>new-preinst</var> install <var>old-version</var>
2865 <p>Otherwise (i.e., the package was completely purged):
2866 <example compact="compact">
2867 <var>new-preinst</var> install
2869 Error unwind actions, respectively:
2870 <example compact="compact">
2871 <var>new-postrm</var> abort-upgrade <var>old-version</var>
2872 <var>new-postrm</var> abort-install <var>old-version</var>
2873 <var>new-postrm</var> abort-install
2882 The new package's files are unpacked, overwriting any
2883 that may be on the system already, for example any
2884 from the old version of the same package or from
2885 another package. Backups of the old files are kept
2886 temporarily, and if anything goes wrong the package
2887 management system will attempt to put them back as
2888 part of the error unwind.
2892 It is an error for a package to contains files which
2893 are on the system in another package, unless
2894 <tt>Replaces</tt> is used (see <ref id="replaces">).
2896 The following paragraph is not currently the case:
2897 Currently the <tt>- - force-overwrite</tt> flag is
2898 enabled, downgrading it to a warning, but this may not
2904 It is a more serious error for a package to contain a
2905 plain file or other kind of non-directory where another
2906 package has a directory (again, unless
2907 <tt>Replaces</tt> is used). This error can be
2908 overridden if desired using
2909 <tt>--force-overwrite-dir</tt>, but this is not
2914 Packages which overwrite each other's files produce
2915 behavior which, though deterministic, is hard for the
2916 system administrator to understand. It can easily
2917 lead to "missing" programs if, for example, a package
2918 is installed which overwrites a file from another
2919 package, and is then removed again.<footnote>
2921 Part of the problem is due to what is arguably a
2922 bug in <prgn>dpkg</prgn>.
2928 A directory will never be replaced by a symbolic link
2929 to a directory or vice versa; instead, the existing
2930 state (symlink or not) will be left alone and
2931 <prgn>dpkg</prgn> will follow the symlink if there is
2939 <p>If the package is being upgraded, call
2940 <example compact="compact">
2941 <var>old-postrm</var> upgrade <var>new-version</var>
2946 <p>If this fails, <prgn>dpkg</prgn> will attempt:
2947 <example compact="compact">
2948 <var>new-postrm</var> failed-upgrade <var>old-version</var>
2950 Error unwind, for both cases:
2951 <example compact="compact">
2952 <var>old-preinst</var> abort-upgrade <var>new-version</var>
2959 This is the point of no return - if
2960 <prgn>dpkg</prgn> gets this far, it won't back off
2961 past this point if an error occurs. This will
2962 leave the package in a fairly bad state, which
2963 will require a successful re-installation to clear
2964 up, but it's when <prgn>dpkg</prgn> starts doing
2965 things that are irreversible.
2970 Any files which were in the old version of the package
2971 but not in the new are removed.</p>
2974 <p>The new file list replaces the old.</p>
2977 <p>The new maintainer scripts replace the old.</p>
2981 <p>Any packages all of whose files have been overwritten during the
2982 installation, and which aren't required for
2983 dependencies, are considered to have been removed.
2984 For each such package
2987 <p><prgn>dpkg</prgn> calls:
2988 <example compact="compact">
2989 <var>disappearer's-postrm</var> disappear \
2990 <var>overwriter</var> <var>overwriter-version</var>
2995 <p>The package's maintainer scripts are removed.
3000 It is noted in the status database as being in a
3001 sane state, namely not installed (any conffiles
3002 it may have are ignored, rather than being
3003 removed by <prgn>dpkg</prgn>). Note that
3004 disappearing packages do not have their prerm
3005 called, because <prgn>dpkg</prgn> doesn't know
3006 in advance that the package is going to
3015 Any files in the package we're unpacking that are also
3016 listed in the file lists of other packages are removed
3017 from those lists. (This will lobotomize the file list
3018 of the "conflicting" package if there is one.)
3023 The backup files made during installation, above, are
3030 The new package's status is now sane, and recorded as
3035 Here is another point of no return - if the
3036 conflicting package's removal fails we do not unwind
3037 the rest of the installation; the conflicting package
3038 is left in a half-removed limbo.
3044 If there was a conflicting package we go and do the
3045 removal actions (described below), starting with the
3046 removal of the conflicting package's files (any that
3047 are also in the package being installed have already
3048 been removed from the conflicting package's file list,
3049 and so do not get removed now).
3056 <sect id="configdetails"><heading>Details of configuration</heading>
3059 When we configure a package (this happens with <tt>dpkg
3060 --install</tt> and <tt>dpkg --configure</tt>), we first
3061 update any <tt>conffile</tt>s and then call:
3062 <example compact="compact">
3063 <var>postinst</var> configure <var>most-recently-configured-version</var>
3068 No attempt is made to unwind after errors during
3073 If there is no most recently configured version
3074 <prgn>dpkg</prgn> will pass a null argument; older versions
3075 of dpkg may pass <tt><unknown></tt> (including the
3076 angle brackets) in this case. Even older ones do not pass a
3077 second argument at all, under any circumstances.
3081 <sect id="removedetails"><heading>Details of removal and/or
3082 configuration purging</heading>
3088 <example compact="compact">
3089 <var>prerm</var> remove
3095 The package's files are removed (except <tt>conffile</tt>s).
3100 <example compact="compact">
3101 <var>postrm</var> remove
3107 All the maintainer scripts except the <prgn>postrm</prgn>
3112 If we aren't purging the package we stop here. Note
3113 that packages which have no <prgn>postrm</prgn> and no
3114 <tt>conffile</tt>s are automatically purged when
3115 removed, as there is no difference except for the
3116 <prgn>dpkg</prgn> status.</p>
3120 The <tt>conffile</tt>s and any backup files
3121 (<tt>~</tt>-files, <tt>#*#</tt> files,
3122 <tt>%</tt>-files, <tt>.dpkg-{old,new,tmp}</tt>, etc.)
3127 <example compact="compact">
3128 <var>postrm</var> purge
3133 <p>The package's file list is removed.</p>
3136 No attempt is made to unwind after errors during
3143 <chapt id="relationships"><heading>Declaring relationships between
3146 <sect id="depsyntax"><heading>Syntax of relationship fields
3150 These fields all have a uniform syntax. They are a list of
3151 package names separated by commas.
3155 In the <tt>Depends</tt>, <tt>Recommends</tt>,
3156 <tt>Suggests</tt>, <tt>Pre-Depends</tt>,
3157 <tt>Build-Depends</tt> and <tt>Build-Depends-Indep</tt>
3158 control file fields of the package, which declare
3159 dependencies on other packages, the package names listed may
3160 also include lists of alternative package names, separated
3161 by vertical bar (pipe) symbols <tt>|</tt>. In such a case,
3162 if any one of the alternative packages is installed, that
3163 part of the dependency is considered to be satisfied.
3167 All of the fields except for <tt>Provides</tt> may restrict
3168 their applicability to particular versions of each named
3169 package. This is done in parentheses after each individual
3170 package name; the parentheses should contain a relation from
3171 the list below followed by a version number, in the format
3172 described in <ref id="versions">.
3176 The relations allowed are <tt><<</tt>, <tt><=</tt>,
3177 <tt>=</tt>, <tt>>=</tt> and <tt>>></tt> for
3178 strictly earlier, earlier or equal, exactly equal, later or
3179 equal and strictly later, respectively. The deprecated
3180 forms <tt><</tt> and <tt>></tt> were used to mean
3181 earlier/later or equal, rather than strictly earlier/later,
3182 so they should not appear in new packages (though
3183 <prgn>dpkg</prgn> still supports them).
3187 Whitespace may appear at any point in the version
3188 specification subject to the rules in <ref
3189 id="controlsyntax">, and must appear where it's necessary to
3190 disambiguate; it is not otherwise significant. For
3191 consistency and in case of future changes to
3192 <prgn>dpkg</prgn> it is recommended that a single space be
3193 used after a version relationship and before a version
3194 number; it is also conventional to put a single space after
3195 each comma, on either side of each vertical bar, and before
3196 each open parenthesis.
3200 For example, a list of dependencies might appear as:
3201 <example compact="compact">
3204 Depends: libc6 (>= 2.2.1), exim | mail-transport-agent
3209 All fields that specify build-time relationships
3210 (<tt>Build-Depends</tt>, <tt>Build-Depends-Indep</tt>,
3211 <tt>Build-Conflicts</tt> and <tt>Build-Conflicts-Indep</tt>)
3212 may be restricted to a certain set of architectures. This
3213 is indicated in brackets after each individual package name and
3214 the optional version specification. The brackets enclose a
3215 list of Debian architecture names separated by whitespace.
3216 Exclamation marks may be prepended to each of the names.
3217 (It is not permitted for some names to be prepended with
3218 exclamation marks and others not.) If the current Debian
3219 host architecture is not in this list and there are no
3220 exclamation marks in the list, or it is in the list with a
3221 prepended exclamation mark, the package name and the
3222 associated version specification are ignored completely for
3223 the purposes of defining the relationships.
3228 <example compact="compact">
3230 Build-Depends-Indep: texinfo
3231 Build-Depends: kernel-headers-2.2.10 [!hurd-i386],
3232 hurd-dev [hurd-i386], gnumach-dev [hurd-i386]
3237 Note that the binary package relationship fields such as
3238 <tt>Depends</tt> appear in one of the binary package
3239 sections of the control file, whereas the build-time
3240 relationships such as <tt>Build-Depends</tt> appear in the
3241 source package section of the control file (which is the
3247 <heading>Binary Dependencies - <tt>Depends</tt>,
3248 <tt>Recommends</tt>, <tt>Suggests</tt>, <tt>Enhances</tt>,
3249 <tt>Pre-Depends</tt>
3253 Packages can declare in their control file that they have
3254 certain relationships to other packages - for example, that
3255 they may not be installed at the same time as certain other
3256 packages, and/or that they depend on the presence of others.
3260 This is done using the <tt>Depends</tt>, <tt>Pre-Depends</tt>,
3261 <tt>Recommends</tt>, <tt>Suggests</tt>, <tt>Enhances</tt> and
3262 <tt>Conflicts</tt> control file fields.
3266 These six fields are used to declare a dependency
3267 relationship by one package on another. Except for
3268 <tt>Enhances</tt>, they appear in the depending (binary)
3269 package's control file. (<tt>Enhances</tt> appears in the
3270 recommending package's control file.)
3274 A <tt>Depends</tt> field takes effect <em>only</em> when a
3275 package is to be configured. It does not prevent a package
3276 being on the system in an unconfigured state while its
3277 dependencies are unsatisfied, and it is possible to replace
3278 a package whose dependencies are satisfied and which is
3279 properly installed with a different version whose
3280 dependencies are not and cannot be satisfied; when this is
3281 done the depending package will be left unconfigured (since
3282 attempts to configure it will give errors) and will not
3283 function properly. If it is necessary, a
3284 <tt>Pre-Depends</tt> field can be used, which has a partial
3285 effect even when a package is being unpacked, as explained
3286 in detail below. (The other three dependency fields,
3287 <tt>Recommends</tt>, <tt>Suggests</tt> and
3288 <tt>Enhances</tt>, are only used by the various front-ends
3289 to <prgn>dpkg</prgn> such as <prgn>dselect</prgn>.)
3293 For this reason packages in an installation run are usually
3294 all unpacked first and all configured later; this gives
3295 later versions of packages with dependencies on later
3296 versions of other packages the opportunity to have their
3297 dependencies satisfied.
3301 The <tt>Depends</tt> field thus allows package maintainers
3302 to impose an order in which packages should be configured.
3306 The meaning of the five dependency fields is as follows:
3308 <tag><tt>Depends</tt></tag>
3311 This declares an absolute dependency. A package will
3312 not be configured unless all of the packages listed in
3313 its <tt>Depends</tt> field have been correctly
3318 The <tt>Depends</tt> field should be used if the
3319 depended-on package is required for the depending
3320 package to provide a significant amount of
3324 The <tt>Depends</tt> field should also be used if the
3325 <prgn>postinst</prgn>, <prgn>prerm</prgn> or
3326 <prgn>postrm</prgn> scripts require the package to be
3327 present in order to run. Note, however, that the
3328 <prgn>postrm</prgn> cannot rely on any non-essential
3329 packages to be present during the <tt>purge</tt>
3333 <tag><tt>Recommends</tt></tag>
3335 <p>This declares a strong, but not absolute, dependency.
3339 The <tt>Recommends</tt> field should list packages
3340 that would be found together with this one in all but
3341 unusual installations.</p>
3344 <tag><tt>Suggests</tt></tag>
3347 This is used to declare that one package may be more
3348 useful with one or more others. Using this field
3349 tells the packaging system and the user that the
3350 listed packages are related to this one and can
3351 perhaps enhance its usefulness, but that installing
3352 this one without them is perfectly reasonable.
3356 <tag><tt>Enhances</tt></tag>
3359 This field is similar to Suggests but works in the
3360 opposite direction. It is used to declare that a
3361 package can enhance the functionality of another
3366 <tag><tt>Pre-Depends</tt></tag>
3369 This field is like <tt>Depends</tt>, except that it
3370 also forces <prgn>dpkg</prgn> to complete installation
3371 of the packages named before even starting the
3372 installation of the package which declares the
3373 pre-dependency, as follows:
3377 When a package declaring a pre-dependency is about to
3378 be <em>unpacked</em> the pre-dependency can be
3379 satisfied if the depended-on package is either fully
3380 configured, <em>or even if</em> the depended-on
3381 package(s) are only unpacked or half-configured,
3382 provided that they have been configured correctly at
3383 some point in the past (and not removed or partially
3384 removed since). In this case, both the
3385 previously-configured and currently unpacked or
3386 half-configured versions must satisfy any version
3387 clause in the <tt>Pre-Depends</tt> field.
3391 When the package declaring a pre-dependency is about
3392 to be <em>configured</em>, the pre-dependency will be
3393 treated as a normal <tt>Depends</tt>, that is, it will
3394 be considered satisfied only if the depended-on
3395 package has been correctly configured.
3399 <tt>Pre-Depends</tt> should be used sparingly,
3400 preferably only by packages whose premature upgrade or
3401 installation would hamper the ability of the system to
3402 continue with any upgrade that might be in progress.
3406 <tt>Pre-Depends</tt> are also required if the
3407 <prgn>preinst</prgn> script depends on the named
3408 package. It is best to avoid this situation if
3414 When selecting which level of dependency to use you should
3415 consider how important the depended-on package is to the
3416 functionality of the one declaring the dependency. Some
3417 packages are composed of components of varying degrees of
3418 importance. Such a package should list using
3419 <tt>Depends</tt> the package(s) which are required by the
3420 more important components. The other components'
3421 requirements may be mentioned as Suggestions or
3422 Recommendations, as appropriate to the components' relative
3427 <sect id="conflicts"><heading>Conflicting binary packages -
3428 <tt>Conflicts</tt></heading>
3431 When one binary package declares a conflict with another
3432 using a <tt>Conflicts</tt> field, <prgn>dpkg</prgn> will
3433 refuse to allow them to be installed on the system at the
3438 If one package is to be installed, the other must be removed
3439 first - if the package being installed is marked as
3440 replacing (see <ref id="replaces">) the one on the system,
3441 or the one on the system is marked as deselected, or both
3442 packages are marked <tt>Essential</tt>, then
3443 <prgn>dpkg</prgn> will automatically remove the package
3444 which is causing the conflict, otherwise it will halt the
3445 installation of the new package with an error. This
3446 mechanism is specifically designed to produce an error when
3447 the installed package is <tt>Essential</tt>, but the new
3452 A package will not cause a conflict merely because its
3453 configuration files are still installed; it must be at least
3458 A special exception is made for packages which declare a
3459 conflict with their own package name, or with a virtual
3460 package which they provide (see below): this does not
3461 prevent their installation, and allows a package to conflict
3462 with others providing a replacement for it. You use this
3463 feature when you want the package in question to be the only
3464 package providing some feature.
3468 A <tt>Conflicts</tt> entry should almost never have an
3469 "earlier than" version clause. This would prevent
3470 <prgn>dpkg</prgn> from upgrading or installing the package
3471 which declared such a conflict until the upgrade or removal
3472 of the conflicted-with package had been completed.
3476 <sect id="virtual"><heading>Virtual packages - <tt>Provides</tt>
3480 As well as the names of actual ("concrete") packages, the
3481 package relationship fields <tt>Depends</tt>,
3482 <tt>Recommends</tt>, <tt>Suggests</tt>, <tt>Enhances</tt>,
3483 <tt>Pre-Depends</tt>, <tt>Conflicts</tt>,
3484 <tt>Build-Depends</tt>, <tt>Build-Depends-Indep</tt>,
3485 <tt>Build-Conflicts</tt> and <tt>Build-Conflicts-Indep</tt>
3486 may mention "virtual packages".
3490 A <em>virtual package</em> is one which appears in the
3491 <tt>Provides</tt> control file field of another package.
3492 The effect is as if the package(s) which provide a
3493 particular virtual package name had been listed by name
3494 everywhere the virtual package name appears. (See also <ref
3499 If there are both concrete and virtual packages of the same
3500 name, then the dependency may be satisfied (or the conflict
3501 caused) by either the concrete package with the name in
3502 question or any other concrete package which provides the
3503 virtual package with the name in question. This is so that,
3504 for example, supposing we have
3505 <example compact="compact">
3509 and someone else releases an enhanced version of the
3510 <tt>bar</tt> package (for example, a non-US variant), they
3512 <example compact="compact">
3516 and the <tt>bar-plus</tt> package will now also satisfy the
3517 dependency for the <tt>foo</tt> package.
3521 If a dependency or a conflict has a version number attached
3522 then only real packages will be considered to see whether
3523 the relationship is satisfied (or the prohibition violated,
3524 for a conflict) - it is assumed that a real package which
3525 provides the virtual package is not of the "right" version.
3526 So, a <tt>Provides</tt> field may not contain version
3527 numbers, and the version number of the concrete package
3528 which provides a particular virtual package will not be
3529 looked at when considering a dependency on or conflict with
3530 the virtual package name.
3534 It is likely that the ability will be added in a future
3535 release of <prgn>dpkg</prgn> to specify a version number for
3536 each virtual package it provides. This feature is not yet
3537 present, however, and is expected to be used only
3542 If you want to specify which of a set of real packages
3543 should be the default to satisfy a particular dependency on
3544 a virtual package, you should list the real package as an
3545 alternative before the virtual one.
3550 <sect id="replaces"><heading>Overwriting files and replacing
3551 packages - <tt>Replaces</tt></heading>
3554 Packages can declare in their control file that they should
3555 overwrite files in certain other packages, or completely
3556 replace other packages. The <tt>Replaces</tt> control file
3557 field has these two distinct purposes.
3560 <sect1><heading>Overwriting files in other packages</heading>
3563 Firstly, as mentioned before, it is usually an error for a
3564 package to contain files which are on the system in
3569 However, if the overwriting package declares that it
3570 <tt>Replaces</tt> the one containing the file being
3571 overwritten, then <prgn>dpkg</prgn> will replace the file
3572 from the old package with that from the new. The file
3573 will no longer be listed as "owned" by the old package.
3577 If a package is completely replaced in this way, so that
3578 <prgn>dpkg</prgn> does not know of any files it still
3579 contains, it is considered to have "disappeared". It will
3580 be marked as not wanted on the system (selected for
3581 removal) and not installed. Any <tt>conffile</tt>s
3582 details noted for the package will be ignored, as they
3583 will have been taken over by the overwriting package. The
3584 package's <prgn>postrm</prgn> script will be run with a
3585 special argument to allow the package to do any final
3586 cleanup required. See <ref id="mscriptsinstact">.
3590 If an installed package, <tt>foo</tt> say, declares that
3591 it replaces another, <tt>bar</tt>, and an attempt is made
3592 to install <tt>bar</tt>, <prgn>dpkg</prgn> will discard
3593 files in the <tt>bar</tt> package which would overwrite
3594 those already present in <tt>foo</tt>. This is so that
3595 you can install an older version of a package without
3600 For this usage of <tt>Replaces</tt>, virtual packages (see
3601 <ref id="virtual">) are not considered when looking at a
3602 <tt>Replaces</tt> field - the packages declared as being
3603 replaced must be mentioned by their real names.
3607 Furthermore, this usage of <tt>Replaces</tt> only takes
3608 effect when both packages are at least partially on the
3609 system at once, so that it can only happen if they do not
3610 conflict or if the conflict has been overridden.
3615 <sect1><heading>Replacing whole packages, forcing their
3619 Secondly, <tt>Replaces</tt> allows the packaging system to
3620 resolve which package should be removed when there is a
3621 conflict - see <ref id="conflicts">. This usage only
3622 takes effect when the two packages <em>do</em> conflict,
3623 so that the two usages of this field do not interfere with
3628 In this situation, the package declared as being replaced
3629 can be a virtual package, so for example, all mail
3630 transport agents (MTAs) would have the following fields in
3631 their control files:
3632 <example compact="compact">
3633 Provides: mail-transport-agent
3634 Conflicts: mail-transport-agent
3635 Replaces: mail-transport-agent
3637 ensuring that only one MTA can be installed at any one
3642 <sect><heading>Relationships between source and binary packages -
3643 <tt>Build-Depends</tt>, <tt>Build-Depends-Indep</tt>,
3644 <tt>Build-Conflicts</tt>, <tt>Build-Conflicts-Indep</tt>
3648 Source packages that require certain binary packages to be
3649 installed or absent at the time of building the package
3650 can declare relationships to those binary packages.
3654 This is done using the <tt>Build-Depends</tt>,
3655 <tt>Build-Depends-Indep</tt>, <tt>Build-Conflicts</tt> and
3656 <tt>Build-Conflicts-Indep</tt> control file fields.
3660 Build-dependencies on "build-essential" binary packages can be
3661 omitted. Please see <ref id="pkg-relations"> for more information.
3665 The dependencies and conflicts they define must be satisfied
3666 (as defined earlier for binary packages) in order to invoke
3667 the targets in <tt>debian/rules</tt>, as follows:<footnote>
3669 If you make "build-arch" or "binary-arch", you need
3670 Build-Depends. If you make "build-indep" or
3671 "binary-indep", you need Build-Depends and
3672 Build-Depends-Indep. If you make "build" or "binary",
3676 There is no Build-Depends-Arch; the autobuilders will
3677 only need the Build-Depends if they know how to build
3678 only build-arch and binary-arch. Anyone building the
3679 build-indep/binary-indep targets is basically assumed to
3680 be building the whole package and so installs all build
3684 The purpose of the original split, I recall, was so that
3685 the autobuilders wouldn't need to install extra packages
3686 needed only for the binary-indep targets. But without a
3687 build-arch/build-indep split, this didn't work, since
3688 most of the work is done in the build target, not in the
3694 <tag><tt>Build-Depends</tt>, <tt>Build-Conflicts</tt></tag>
3697 The <tt>Build-Depends</tt> and
3698 <tt>Build-Conflicts</tt> fields must be satisfied when
3699 any of the following targets is invoked:
3700 <tt>build</tt>, <tt>clean</tt>, <tt>binary</tt>,
3701 <tt>binary-arch</tt>, <tt>build-arch</tt>,
3702 <tt>build-indep</tt> and <tt>binary-indep</tt>.
3705 <tag><tt>Build-Depends-Indep</tt>,
3706 <tt>Build-Conflicts-Indep</tt></tag>
3709 The <tt>Build-Depends-Indep</tt> and
3710 <tt>Build-Conflicts-Indep</tt> fields must be
3711 satisfied when any of the following targets is
3712 invoked: <tt>build</tt>, <tt>clean</tt>,
3713 <tt>build-indep</tt>, <tt>binary</tt> and
3714 <tt>binary-indep</tt>.
3725 <chapt id="conffiles"><heading>Configuration file handling
3729 This chapter has been superseded by <ref id="config-files">.
3733 <chapt id="sharedlibs"><heading>Shared libraries</heading>
3736 Packages containing shared libraries must be constructed with
3737 a little care to make sure that the shared library is always
3738 available. This is especially important for packages whose
3739 shared libraries are vitally important, such as the C library
3740 (currently <tt>libc6</tt>).
3744 Packages involving shared libraries should be split up into
3745 several binary packages. This section mostly deals with how
3746 this separation is to be accomplished; rules for files within
3747 the shared library packages are in <ref id="libraries"> instead.
3750 <sect id="sharedlibs-runtime">
3751 <heading>Run-time shared libraries</heading>
3754 The run-time shared library needs to be placed in a package called
3755 <package><var>libraryname</var><var>soversion</var></package>, where
3756 <file><var>soversion</var></file> is the version number in the
3757 soname of the shared library<footnote>
3759 The soname is the shared object name: it's the thing
3760 that has to match exactly between building an executable
3761 and running it for the dynamic linker to be able run the
3762 program. For example, if the soname of the library is
3763 <file>libfoo.so.6</file>, the library package would be
3764 called <file>libfoo6</file>.
3767 Alternatively, if it would be confusing to directly append
3768 <var>soversion</var> to <var>libraryname</var> (e.g. because
3769 <var>libraryname</var> itself ends in a number), you may use
3770 <package><var>libraryname</var>-<var>soversion</var></package> and
3771 <package><var>libraryname</var>-<var>soversion</var>-dev</package>
3776 If you have several shared libraries built from the same
3777 source tree you may lump them all together into a single
3778 shared library package, provided that you change all of
3779 their sonames at once (so that you don't get filename
3780 clashes if you try to install different versions of the
3781 combined shared libraries package).
3785 The package should install the shared libraries under
3786 their normal names. For example, the <package>libgdbmg1</package>
3787 package should install <file>libgdbm.so.1.7.3</file> as
3788 <file>/usr/lib/libgdbm.so.1.7.3</file>. The files should not be
3789 renamed or re-linked by any <prgn>prerm</prgn> or
3790 <prgn>postrm</prgn> scripts; <prgn>dpkg</prgn> will take care
3791 of renaming things safely without affecting running programs,
3792 and attempts to interfere with this are likely to lead to
3797 Shared libraries should not be installed executable, since
3798 the dynamic linker does not require this and trying to
3799 execute a shared library usually results in a core dump.
3803 The run-time library package should include the symbolic link that
3804 <prgn>ldconfig</prgn> would create for the shared libraries.
3805 For example, the <package>libgdbmg1</package> package should include
3806 a symbolic link from <file>/usr/lib/libgdbm.so.1</file> to
3807 <file>libgdbm.so.1.7.3</file>. This is needed so that the dynamic
3808 linker (for example <prgn>ld.so</prgn> or
3809 <prgn>ld-linux.so.*</prgn>) can find the library between the
3810 time that <prgn>dpkg</prgn> installs it and the time that
3811 <prgn>ldconfig</prgn> is run in the <prgn>postinst</prgn>
3814 The package management system requires the library to be
3815 placed before the symbolic link pointing to it in the
3816 <file>.deb</file> file. This is so that when
3817 <prgn>dpkg</prgn> comes to install the symlink
3818 (overwriting the previous symlink pointing at an older
3819 version of the library), the new shared library is already
3820 in place. In the past, this was achieved by creating the
3821 library in the temporary packaging directory before
3822 creating the symlink. Unfortunately, this was not always
3823 effective, since the building of the tar file in the
3824 <file>.deb</file> depended on the behavior of the underlying
3825 file system. Some file systems (such as reiserfs) reorder
3826 the files so that the order of creation is forgotten.
3827 Since version 1.7.0, <prgn>dpkg</prgn>
3828 reorders the files itself as necessary when building a
3829 package. Thus it is no longer important to concern
3830 oneself with the order of file creation.
3835 <sect1 id="ldconfig">
3836 <heading><tt>ldconfig</tt></heading>
3839 Any package installing shared libraries in one of the default
3840 library directories of the dynamic linker (which are currently
3841 <file>/usr/lib</file> and <file>/lib</file>) or a directory that is
3842 listed in <file>/etc/ld.so.conf</file><footnote>
3845 <list compact="compact">
3846 <item><p>/usr/X11R6/lib/Xaw3d</p></item>
3847 <item><p>/usr/local/lib</p></item>
3848 <item><p>/usr/lib/libc5-compat</p></item>
3849 <item><p>/lib/libc5-compat</p></item>
3850 <item><p>/usr/X11R6/lib</p></item>
3854 must use <prgn>ldconfig</prgn> to update the shared library
3859 The package must call <prgn>ldconfig</prgn> in the
3860 <prgn>postinst</prgn> script if the first argument is
3861 <tt>configure</tt>; the <prgn>postinst</prgn> script may
3862 optionally invoke <prgn>ldconfig</prgn> at other times. The
3863 package should call <prgn>ldconfig</prgn> in the
3864 <prgn>postrm</prgn> script if the first argument is
3865 <tt>remove</tt>. The maintainer scripts must not invoke
3866 <prgn>ldconfig</prgn> under any circumstances other than those
3867 described in this paragraph.<footnote>
3868 <p>During install or upgrade, the preinst is called before
3869 the new files are installed, so calling "ldconfig" is
3870 pointless. The preinst of an existing package can also be
3871 called if an upgrade fails. However, this happens during
3872 the critical time when a shared libs may exist on-disk
3873 under a temporary name. Thus, it is dangerous and
3874 forbidden by current policy to call "ldconfig" at this
3877 <p>When a package is installed or upgraded, "postinst
3878 configure" runs after the new files are safely on-disk.
3879 Since it is perfectly safe to invoke ldconfig
3880 unconditionally in a postinst, it is OK for a package to
3881 simply put ldconfig in its postinst without checking the
3882 argument. The postinst can also be called to recover from
3883 a failed upgrade. This happens before any new files are
3884 unpacked, so there is no reason to call "ldconfig" at this
3887 <p>For a package that is being removed, prerm is
3888 called with all the files intact, so calling ldconfig is
3889 useless. The other calls to "prerm" happen in the case of
3890 upgrade at a time when all the files of the old package
3891 are on-disk, so again calling "ldconfig" is pointless.
3893 <p>postrm, on the other hand, is called with the "remove"
3894 argument just after the files are removed, so this is the
3895 proper time to call "ldconfig" to notify the system of the
3896 fact shared libraries from the package are removed.
3897 The postrm can be called at several other times. At the
3898 time of "postrm purge", "postrm abort-install", or "postrm
3899 abort-upgrade", calling "ldconfig" is useless because the
3900 shared lib files are not on-disk. However, when "postrm"
3901 is invoked with arguments "upgrade", "failed-upgrade", or
3902 "disappear", a shared lib may exist on-disk under a
3911 <sect id="sharedlibs-runtime-progs">
3912 <heading>Run-time support programs</heading>
3915 If your package has some run-time support programs which use
3916 the shared library you must not put them in the shared
3917 library package. If you do that then you won't be able to
3918 install several versions of the shared library without
3919 getting filename clashes.
3923 Instead, either create another package for the runtime binaries
3924 (this package might typically be named
3925 <package><var>libraryname</var>-runtime</package>; note the absence
3926 of the <var>soversion</var> in the package name), or if the
3927 development package is small, include them in there.
3931 <sect id="sharedlibs-static">
3932 <heading>Static libraries</heading>
3935 The static library (<file><var>libraryname.a</var></file>)
3936 is usually provided in addition to the shared version.
3937 It is placed into the development package (see below).
3941 In some cases, it is acceptable for a library to be
3942 available in static form only; these cases include:
3944 <item>libraries for languages whose shared library support
3945 is immature or unstable</item>
3946 <item>libraries whose interfaces are in flux or under
3947 development (commonly the case when the library's
3948 major version number is zero, or where the ABI breaks
3949 across patchlevels)</item>
3950 <item>libraries which are explicitly intended to be
3951 available only in static form by their upstream
3956 <sect id="sharedlibs-dev">
3957 <heading>Development files</heading>
3960 The development files associated to a shared library need to be
3961 placed in a package called
3962 <package><var>libraryname</var><var>soversion</var>-dev</package>,
3963 or if you prefer only to support one development version at a
3964 time, <package><var>libraryname</var>-dev</package>.
3968 In case several development versions of a library exist, you may
3969 need to use <prgn>dpkg</prgn>'s Conflicts mechanism (see
3970 <ref id="conflicts">) to ensure that the user only installs one
3971 development version at a time (as different development versions are
3972 likely to have the same header files in them, which would cause a
3973 filename clash if both were installed).
3977 The development package should contain a symlink for the associated
3978 shared library without a version number. For example, the
3979 <package>libgdbmg1-dev</package> package should include a symlink
3980 from <file>/usr/lib/libgdbm.so</file> to
3981 <file>libgdbm.so.1.7.3</file>. This symlink is needed by the linker
3982 (<prgn>ld</prgn>) when compiling packages, as it will only look for
3983 <file>libgdbm.so</file> when compiling dynamically.
3987 <sect id="sharedlibs-intradeps">
3988 <heading>Dependencies between the packages of the same library</heading>
3991 Typically the development version should have an exact
3992 version dependency on the runtime library, to make sure that
3993 compilation and linking happens correctly. The
3994 <tt>${Source-Version}</tt> substitution variable can be
3995 useful for this purpose.
3999 <sect id="sharedlibs-shlibdeps">
4000 <heading>Dependencies between the library and other packages -
4001 the <tt>shlibs</tt> system</heading>
4004 If a package contains a binary or library which links to a
4005 shared library, we must ensure that when the package is
4006 installed on the system, all of the libraries needed are
4007 also installed. This requirement led to the creation of the
4008 <tt>shlibs</tt> system, which is very simple in its design:
4009 any package which <em>provides</em> a shared library also
4010 provides information on the package dependencies required to
4011 ensure the presence of this library, and any package which
4012 <em>uses</em> a shared library uses this information to
4013 determine the dependencies it requires. The files which
4014 contain the mapping from shared libraries to the necessary
4015 dependency information are called <file>shlibs</file> files.
4019 Thus, when a package is built which contains any shared
4020 libraries, it must provide a <file>shlibs</file> file for other
4021 packages to use, and when a package is built which contains
4022 any shared libraries or compiled binaries, it must run
4023 <prgn>dpkg-shlibdeps</prgn> on these to determine the
4024 libraries used and hence the dependencies needed by this
4027 In the past, the shared libraries linked to were
4028 determined by calling <prgn>ldd</prgn>, but now
4029 <prgn>objdump</prgn> is used to do this. The only
4030 change this makes to package building is that
4031 <prgn>dpkg-shlibdeps</prgn> must also be run on shared
4032 libraries, whereas in the past this was unnecessary.
4033 The rest of this footnote explains the advantage that
4038 We say that a binary <tt>foo</tt> <em>directly</em> uses
4039 a library <tt>libbar</tt> if it is explicitly linked
4040 with that library (that is, it uses the flag
4041 <tt>-lbar</tt> during the linking stage). Other
4042 libraries that are needed by <tt>libbar</tt> are linked
4043 <em>indirectly</em> to <tt>foo</tt>, and the dynamic
4044 linker will load them automatically when it loads
4045 <tt>libbar</tt>. A package should depend on
4046 the libraries it directly uses, and the dependencies for
4047 those libraries should automatically pull in the other
4052 Unfortunately, the <prgn>ldd</prgn> program shows both
4053 the directly and indirectly used libraries, meaning that
4054 the dependencies determined included both direct and
4055 indirect dependencies. The use of <prgn>objdump</prgn>
4056 avoids this problem by determining only the directly
4061 A good example of where this helps is the following. We
4062 could update <tt>libimlib</tt> with a new version that
4063 supports a new graphics format called dgf (but retaining
4064 the same major version number). If we used the old
4065 <prgn>ldd</prgn> method, every package that uses
4066 <tt>libimlib</tt> would need to be recompiled so it
4067 would also depend on <tt>libdgf</tt> or it wouldn't run
4068 due to missing symbols. However with the new system,
4069 packages using <tt>libimlib</tt> can rely on
4070 <tt>libimlib</tt> itself having the dependency on
4071 <tt>libdgf</tt> and so they would not need rebuilding.
4077 In the following sections, we will first describe where the
4078 various <tt>shlibs</tt> files are to be found, then how to
4079 use <prgn>dpkg-shlibdeps</prgn>, and finally the
4080 <tt>shlibs</tt> file format and how to create them if your
4081 package contains a shared library.
4085 <heading>The <tt>shlibs</tt> files present on the system</heading>
4088 There are several places where <tt>shlibs</tt> files are
4089 found. The following list gives them in the order in which
4090 they are read by <prgn>dpkg-shlibdeps</prgn>. (The first
4091 one which gives the required information is used.)
4097 <p><file>debian/shlibs.local</file></p>
4099 This lists overrides for this package. Its use is
4100 described below (see <ref id="shlibslocal">).
4105 <p><file>/etc/dpkg/shlibs.override</file></p>
4107 This lists global overrides. This list is normally
4108 empty. It is maintained by the local system
4114 <p><file>DEBIAN/shlibs</file> files in the "build directory"</p>
4116 When packages are being built, any
4117 <file>debian/shlibs</file> files are copied into the
4118 control file area of the temporary build directory and
4119 given the name <file>shlibs</file>. These files give
4120 details of any shared libraries included in the
4123 An example may help here. Let us say that the
4124 source package <tt>foo</tt> generates two binary
4125 packages, <tt>libfoo2</tt> and
4126 <tt>foo-runtime</tt>. When building the binary
4127 packages, the two packages are created in the
4128 directories <file>debian/libfoo2</file> and
4129 <file>debian/foo-runtime</file> respectively.
4130 (<file>debian/tmp</file> could be used instead of one
4131 of these.) Since <tt>libfoo2</tt> provides the
4132 <tt>libfoo</tt> shared library, it will require a
4133 <tt>shlibs</tt> file, which will be installed in
4134 <file>debian/libfoo2/DEBIAN/shlibs</file>, eventually
4136 <file>/var/lib/dpkg/info/libfoo2.shlibs</file>. Then
4137 when <prgn>dpkg-shlibdeps</prgn> is run on the
4139 <file>debian/foo-runtime/usr/bin/foo-prog</file>, it
4141 <file>debian/libfoo2/DEBIAN/shlibs</file> file to
4142 determine whether <tt>foo-prog</tt>'s library
4143 dependencies are satisfied by any of the libraries
4144 provided by <tt>libfoo2</tt>. For this reason,
4145 <prgn>dpkg-shlibdeps</prgn> must only be run once
4146 all of the individual binary packages'
4147 <tt>shlibs</tt> files have been installed into the
4155 <p><file>/var/lib/dpkg/info/*.shlibs</file></p>
4157 These are the <file>shlibs</file> files corresponding to
4158 all of the packages installed on the system, and are
4159 maintained by the relevant package maintainers.
4164 <p><file>/etc/dpkg/shlibs.default</file></p>
4166 This file lists any shared libraries whose packages
4167 have failed to provide correct <file>shlibs</file> files.
4168 It was used when the <file>shlibs</file> setup was first
4169 introduced, but it is now normally empty. It is
4170 maintained by the <tt>dpkg</tt> maintainer.
4178 <heading>How to use <prgn>dpkg-shlibdeps</prgn> and the
4179 <file>shlibs</file> files</heading>
4182 Put a call to <prgn>dpkg-shlibdeps</prgn> into your
4183 <file>debian/rules</file> file. If your package contains only
4184 compiled binaries and libraries (but no scripts), you can
4185 use a command such as:
4186 <example compact="compact">
4187 dpkg-shlibdeps debian/tmp/usr/bin/* debian/tmp/usr/sbin/* \
4188 debian/tmp/usr/lib/*
4190 Otherwise, you will need to explicitly list the compiled
4191 binaries and libraries.<footnote>
4193 If you are using <tt>debhelper</tt>, the
4194 <prgn>dh_shlibdeps</prgn> program will do this work for
4195 you. It will also correctly handle multi-binary
4202 This command puts the dependency information into the
4203 <file>debian/substvars</file> file, which is then used by
4204 <prgn>dpkg-gencontrol</prgn>. You will need to place a
4205 <tt>${shlib:Depends}</tt> variable in the <tt>Depends</tt>
4206 field in the control file for this to work.
4210 If <prgn>dpkg-shlibdeps</prgn> doesn't complain, you're
4211 done. If it does complain you might need to create your own
4212 <file>debian/shlibs.local</file> file, as explained below (see
4213 <ref id="shlibslocal">).
4217 If you have multiple binary packages, you will need to call
4218 <prgn>dpkg-shlibdeps</prgn> on each one which contains
4219 compiled libraries or binaries. In such a case, you will
4220 need to use the <tt>-T</tt> option to the <tt>dpkg</tt>
4221 utilities to specify a different <file>substvars</file> file.
4222 For more details on this and other options, see <manref
4223 name="dpkg-shlibdeps" section="1">.
4228 <heading>The <file>shlibs</file> File Format</heading>
4231 Each <file>shlibs</file> file has the same format. Lines
4232 beginning with <tt>#</tt> are considered to be comments and
4233 are ignored. Each line is of the form:
4234 <example compact="compact">
4235 <var>library-name</var> <var>soname-version-number</var> <var>dependencies ...</var>
4240 We will explain this by reference to the example of the
4241 <tt>zlib1g</tt> package, which (at the time of writing)
4242 installs the shared library <file>/usr/lib/libz.so.1.1.3</file>.
4246 <var>library-name</var> is the name of the shared library,
4247 in this case <tt>libz</tt>. (This must match the name part
4248 of the soname, see below.)
4252 <var>soname-version-number</var> is the version part of the
4253 soname of the library. The soname is the thing that must
4254 exactly match for the library to be recognized by the
4255 dynamic linker, and is usually of the form
4256 <tt><var>name</var>.so.<var>major-version</var></tt>, in our
4257 example, <tt>libz.so.1</tt>.<footnote>
4259 This can be determined using the command
4260 <example compact="compact">
4261 objdump -p /usr/lib/libz.so.1.1.3 | grep SONAME
4265 The version part is the part which comes after
4266 <tt>.so.</tt>, so in our case, it is <tt>1</tt>.
4270 <var>dependencies</var> has the same syntax as a dependency
4271 field in a binary package control file. It should give
4272 details of which packages are required to satisfy a binary
4273 built against the version of the library contained in the
4274 package. See <ref id="depsyntax"> for details.
4278 In our example, if the first version of the <tt>zlib1g</tt>
4279 package which contained a minor number of at least
4280 <tt>1.3</tt> was <var>1:1.1.3-1</var>, then the
4281 <tt>shlibs</tt> entry for this library could say:
4282 <example compact="compact">
4283 libz 1 zlib1g (>= 1:1.1.3)
4285 The version-specific dependency is to avoid warnings from
4286 the dynamic linker about using older shared libraries with
4292 <heading>Providing a <file>shlibs</file> file</heading>
4295 If your package provides a shared library, you should create
4296 a <file>shlibs</file> file following the format described above.
4297 It is usual to call this file <file>debian/shlibs</file> (but if
4298 you have multiple binary packages, you might want to call it
4299 <file>debian/shlibs.<var>package</var></file> instead). Then
4300 let <file>debian/rules</file> install it in the control area:
4301 <example compact="compact">
4302 install -m644 debian/shlibs debian/tmp/DEBIAN
4304 or, in the case of a multi-binary package:
4305 <example compact="compact">
4306 install -m644 debian/shlibs.<var>package</var> debian/<var>package</var>/DEBIAN/shlibs
4308 An alternative way of doing this is to create the
4309 <file>shlibs</file> file in the control area directly from
4310 <file>debian/rules</file> without using a <file>debian/shlibs</file>
4311 file at all,<footnote>
4313 This is what <prgn>dh_makeshlibs</prgn> in the
4314 <tt>debhelper</tt> suite does.
4317 since the <file>debian/shlibs</file> file itself is ignored by
4318 <prgn>dpkg-shlibdeps</prgn>.
4322 As <prgn>dpkg-shlibdeps</prgn> reads the
4323 <file>DEBIAN/shlibs</file> files in all of the binary packages
4324 being built from this source package, all of the
4325 <file>DEBIAN/shlibs</file> files should be installed before
4326 <prgn>dpkg-shlibdeps</prgn> is called on any of the binary
4331 <sect1 id="shlibslocal">
4332 <heading>Writing the <file>debian/shlibs.local</file> file</heading>
4335 This file is intended only as a <em>temporary</em> fix if
4336 your binaries or libraries depend on a library whose package
4337 does not yet provide a correct <file>shlibs</file> file.
4341 We will assume that you are trying to package a binary
4342 <tt>foo</tt>. When you try running
4343 <prgn>dpkg-shlibdeps</prgn> you get the following error
4344 message (<tt>-O</tt> displays the dependency information on
4345 <tt>stdout</tt> instead of writing it to
4346 <tt>debian/substvars</tt>, and the lines have been wrapped
4347 for ease of reading):
4348 <example compact="compact">
4349 $ dpkg-shlibdeps -O debian/tmp/usr/bin/foo
4350 dpkg-shlibdeps: warning: unable to find dependency
4351 information for shared library libbar (soname 1,
4352 path /usr/lib/libbar.so.1, dependency field Depends)
4353 shlibs:Depends=libc6 (>= 2.2.2-2)
4355 You can then run <prgn>ldd</prgn> on the binary to find the
4356 full location of the library concerned:
4357 <example compact="compact">
4359 libbar.so.1 => /usr/lib/libbar.so.1 (0x4001e000)
4360 libc.so.6 => /lib/libc.so.6 (0x40032000)
4361 /lib/ld-linux.so.2 => /lib/ld-linux.so.2 (0x40000000)
4363 So the <prgn>foo</prgn> binary depends on the
4364 <prgn>libbar</prgn> shared library, but no package seems to
4365 provide a <file>*.shlibs</file> file handling
4366 <file>libbar.so.1</file> in <file>/var/lib/dpkg/info/</file>. Let's
4367 determine the package responsible:
4368 <example compact="compact">
4369 $ dpkg -S /usr/lib/libbar.so.1
4370 bar1: /usr/lib/libbar.so.1
4371 $ dpkg -s bar1 | grep Version
4374 This tells us that the <tt>bar1</tt> package, version 1.0-1,
4375 is the one we are using. Now we can file a bug against the
4376 <tt>bar1</tt> package and create our own
4377 <file>debian/shlibs.local</file> to locally fix the problem.
4378 Including the following line into your
4379 <file>debian/shlibs.local</file> file:
4380 <example compact="compact">
4381 libbar 1 bar1 (>= 1.0-1)
4383 should allow the package build to work.
4387 As soon as the maintainer of <tt>bar1</tt> provides a
4388 correct <file>shlibs</file> file, you should remove this line
4389 from your <file>debian/shlibs.local</file> file. (You should
4390 probably also then have a versioned <tt>Build-Depends</tt>
4391 on <tt>bar1</tt> to help ensure that others do not have the
4392 same problem building your package.)
4400 <chapt id="opersys"><heading>The Operating System</heading>
4403 <heading>Filesystem hierarchy</heading>
4407 <heading>Filesystem Structure</heading>
4410 The location of all installed files and directories must
4411 comply with the Filesystem Hierarchy Standard (FHS),
4412 version 2.1, except where doing so would violate other
4413 terms of Debian Policy. The version of this document
4414 referred here can be found in the <tt>debian-policy</tt>
4416 <url id="http://www.debian.org/doc/packaging-manuals/fhs/"
4417 name="FHS (Debian copy)"> alongside this manual (or, if
4418 you have the <package>debian-policy</package> installed,
4420 id="file:///usr/share/doc/debian-policy/fhs/" name="FHS
4421 (local copy)">). The
4422 latest version, which may be a more recent version, may
4424 <url id="http://www.pathname.com/fhs/" name="FHS (upstream)">.
4425 Specific questions about following the standard may be
4426 asked on the <tt>debian-devel</tt> mailing list, or
4427 referred to the FHS mailing list (see the
4428 <url id="http://www.pathname.com/fhs/" name="FHS web site"> for
4434 <heading>Site-specific programs</heading>
4437 As mandated by the FHS, packages must not place any
4438 files in <file>/usr/local</file>, either by putting them in
4439 the file system archive to be unpacked by <prgn>dpkg</prgn>
4440 or by manipulating them in their maintainer scripts.
4444 However, the package may create empty directories below
4445 <file>/usr/local</file> so that the system administrator knows
4446 where to place site-specific files. These directories
4447 should be removed on package removal if they are
4452 Note, that this applies only to directories <em>below</em>
4453 <file>/usr/local</file>, not <em>in</em> <file>/usr/local</file>.
4454 Packages must not create sub-directories in the directory
4455 <file>/usr/local</file> itself, except those listed in FHS,
4456 section 4.5. However, you may create directories below
4457 them as you wish. You must not remove any of the
4458 directories listed in 4.5, even if you created them.
4462 Since <file>/usr/local</file> can be mounted read-only from a
4463 remote server, these directories must be created and
4464 removed by the <prgn>postinst</prgn> and <prgn>prerm</prgn>
4465 maintainer scripts and not be included in the
4466 <file>.deb</file> archive. These scripts must not fail if
4467 either of these operations fail.
4471 For example, the <tt>emacsen-common</tt> package could
4472 contain something like
4473 <example compact="compact">
4474 if [ ! -e /usr/local/share/emacs ]
4476 if mkdir /usr/local/share/emacs 2>/dev/null
4478 chown root:staff /usr/local/share/emacs
4479 chmod 2775 /usr/local/share/emacs
4483 in its <prgn>postinst</prgn> script, and
4484 <example compact="compact">
4485 rmdir /usr/local/share/emacs/site-lisp 2>/dev/null || true
4486 rmdir /usr/local/share/emacs 2>/dev/null || true
4488 in the <prgn>prerm</prgn> script. (Note that this form is
4489 used to ensure that if the script is interrupted, the
4490 directory <file>/usr/local/share/emacs</file> will still be
4495 If you do create a directory in <file>/usr/local</file> for
4496 local additions to a package, you should ensure that
4497 settings in <file>/usr/local</file> take precedence over the
4498 equivalents in <file>/usr</file>.
4502 However, because <file>/usr/local</file> and its contents are
4503 for exclusive use of the local administrator, a package
4504 must not rely on the presence or absence of files or
4505 directories in <file>/usr/local</file> for normal operation.
4509 The <file>/usr/local</file> directory itself and all the
4510 subdirectories created by the package should (by default) have
4511 permissions 2775 (group-writable and set-group-id) and be
4512 owned by <tt>root.staff</tt>.
4517 <heading>The system-wide mail directory</heading>
4519 The system-wide mail directory is <file>/var/mail</file>. This
4520 directory is part of the base system and should not owned
4521 by any particular mail agents. The use of the old
4522 location <file>/var/spool/mail</file> is deprecated, even
4523 though the spool may still be physically located there.
4524 To maintain partial upgrade compatibility for systems
4525 which have <file>/var/spool/mail</file> as their physical mail
4526 spool, packages using <file>/var/mail</file> must depend on
4527 either <package>libc6</package> (>= 2.1.3-13), or on
4528 <package>base-files</package> (>= 2.2.0), or on later
4529 versions of either one of these packages.
4535 <heading>Users and groups</heading>
4538 <heading>Introduction</heading>
4540 The Debian system can be configured to use either plain or
4545 Some user ids (UIDs) and group ids (GIDs) are reserved
4546 globally for use by certain packages. Because some
4547 packages need to include files which are owned by these
4548 users or groups, or need the ids compiled into binaries,
4549 these ids must be used on any Debian system only for the
4550 purpose for which they are allocated. This is a serious
4551 restriction, and we should avoid getting in the way of
4552 local administration policies. In particular, many sites
4553 allocate users and/or local system groups starting at 100.
4557 Apart from this we should have dynamically allocated ids,
4558 which should by default be arranged in some sensible
4559 order, but the behavior should be configurable.
4563 Packages other than <tt>base-passwd</tt> must not modify
4564 <file>/etc/passwd</file>, <file>/etc/shadow</file>,
4565 <file>/etc/group</file> or <file>/etc/gshadow</file>.
4570 <heading>UID and GID classes</heading>
4572 The UID and GID numbers are divided into classes as
4578 Globally allocated by the Debian project, the same
4579 on every Debian system. These ids will appear in
4580 the <file>passwd</file> and <file>group</file> files of all
4581 Debian systems, new ids in this range being added
4582 automatically as the <tt>base-passwd</tt> package is
4587 Packages which need a single statically allocated
4588 uid or gid should use one of these; their
4589 maintainers should ask the <tt>base-passwd</tt>
4597 Dynamically allocated system users and groups.
4598 Packages which need a user or group, but can have
4599 this user or group allocated dynamically and
4600 differently on each system, should use <tt>adduser
4601 --system</tt> to create the group and/or user.
4602 <prgn>adduser</prgn> will check for the existence of
4603 the user or group, and if necessary choose an unused
4604 id based on the ranges specified in
4605 <file>adduser.conf</file>.
4609 <tag>1000-29999:</tag>
4612 Dynamically allocated user accounts. By default
4613 <prgn>adduser</prgn> will choose UIDs and GIDs for
4614 user accounts in this range, though
4615 <file>adduser.conf</file> may be used to modify this
4620 <tag>30000-59999:</tag>
4625 <tag>60000-64999:</tag>
4628 Globally allocated by the Debian project, but only
4629 created on demand. The ids are allocated centrally
4630 and statically, but the actual accounts are only
4631 created on users' systems on demand.
4635 These ids are for packages which are obscure or
4636 which require many statically-allocated ids. These
4637 packages should check for and create the accounts in
4638 <file>/etc/passwd</file> or <file>/etc/group</file> (using
4639 <prgn>adduser</prgn> if it has this facility) if
4640 necessary. Packages which are likely to require
4641 further allocations should have a "hole" left after
4642 them in the allocation, to give them room to
4647 <tag>65000-65533:</tag>
4655 User <tt>nobody</tt>. The corresponding gid refers
4656 to the group <tt>nogroup</tt>.
4663 <tt>(uid_t)(-1) == (gid_t)(-1)</tt> <em>must
4664 not</em> be used, because it is the error return
4673 <sect id="sysvinit">
4674 <heading>System run levels and <file>init.d</file> scripts</heading>
4676 <sect1 id="/etc/init.d">
4677 <heading>Introduction</heading>
4680 The <file>/etc/init.d</file> directory contains the scripts
4681 executed by <prgn>init</prgn> at boot time and when the
4682 init state (or "runlevel") is changed (see <manref
4683 name="init" section="8">).
4687 There are at least two different, yet functionally
4688 equivalent, ways of handling these scripts. For the sake
4689 of simplicity, this document describes only the symbolic
4690 link method. However, it must not be assumed by maintainer
4691 scripts that this method is being used, and any automated
4692 manipulation of the various runlevel behaviours by
4693 maintainer scripts must be performed using
4694 <prgn>update-rc.d</prgn> as described below and not by
4695 manually installing or removing symlinks. For information
4696 on the implementation details of the other method,
4697 implemented in the <tt>file-rc</tt> package, please refer
4698 to the documentation of that package.
4702 These scripts are referenced by symbolic links in the
4703 <file>/etc/rc<var>n</var>.d</file> directories. When changing
4704 runlevels, <prgn>init</prgn> looks in the directory
4705 <file>/etc/rc<var>n</var>.d</file> for the scripts it should
4706 execute, where <tt><var>n</var></tt> is the runlevel that
4707 is being changed to, or <tt>S</tt> for the boot-up
4712 The names of the links all have the form
4713 <file>S<var>mm</var><var>script</var></file> or
4714 <file>K<var>mm</var><var>script</var></file> where
4715 <var>mm</var> is a two-digit number and <var>script</var>
4716 is the name of the script (this should be the same as the
4717 name of the actual script in <file>/etc/init.d</file>).
4721 When <prgn>init</prgn> changes runlevel first the targets
4722 of the links whose names start with a <tt>K</tt> are
4723 executed, each with the single argument <tt>stop</tt>,
4724 followed by the scripts prefixed with an <tt>S</tt>, each
4725 with the single argument <tt>start</tt>. (The links are
4726 those in the <file>/etc/rc<var>n</var>.d</file> directory
4727 corresponding to the new runlevel.) The <tt>K</tt> links
4728 are responsible for killing services and the <tt>S</tt>
4729 link for starting services upon entering the runlevel.
4733 For example, if we are changing from runlevel 2 to
4734 runlevel 3, init will first execute all of the <tt>K</tt>
4735 prefixed scripts it finds in <file>/etc/rc3.d</file>, and then
4736 all of the <tt>S</tt> prefixed scripts in that directory.
4737 The links starting with <tt>K</tt> will cause the
4738 referred-to file to be executed with an argument of
4739 <tt>stop</tt>, and the <tt>S</tt> links with an argument
4744 The two-digit number <var>mm</var> is used to determine
4745 the order in which to run the scripts: low-numbered links
4746 have their scripts run first. For example, the
4747 <tt>K20</tt> scripts will be executed before the
4748 <tt>K30</tt> scripts. This is used when a certain service
4749 must be started before another. For example, the name
4750 server <prgn>bind</prgn> might need to be started before
4751 the news server <prgn>inn</prgn> so that <prgn>inn</prgn>
4752 can set up its access lists. In this case, the script
4753 that starts <prgn>bind</prgn> would have a lower number
4754 than the script that starts <prgn>inn</prgn> so that it
4756 <example compact="compact">
4763 The two runlevels 0 (halt) and 6 (reboot) are slightly
4764 different. In these runlevels, the links with an
4765 <tt>S</tt> prefix are still called after those with a
4766 <tt>K</tt> prefix, but they too are called with the single
4767 argument <tt>stop</tt>.
4771 Also, if the script name ends <tt>.sh</tt>, the script
4772 will be sourced in runlevel <tt>S</tt> rather that being
4773 run in a forked subprocess, but will be explicitly run by
4774 <prgn>sh</prgn> in all other runlevels.
4779 <heading>Writing the scripts</heading>
4782 Packages that include daemons for system services should
4783 place scripts in <file>/etc/init.d</file> to start or stop
4784 services at boot time or during a change of runlevel.
4785 These scripts should be named
4786 <file>/etc/init.d/<var>package</var></file>, and they should
4787 accept one argument, saying what to do:
4790 <tag><tt>start</tt></tag>
4791 <item><p>start the service,</p></item>
4793 <tag><tt>stop</tt></tag>
4794 <item><p>stop the service,</p></item>
4796 <tag><tt>restart</tt></tag>
4797 <item><p>stop and restart the service if it's already
4798 running, otherwise start the service</p></item>
4800 <tag><tt>reload</tt></tag>
4801 <item><p>cause the configuration of the service to be
4802 reloaded without actually stopping and restarting
4803 the service,</p></item>
4805 <tag><tt>force-reload</tt></tag>
4806 <item><p>cause the configuration to be reloaded if the
4807 service supports this, otherwise restart the
4811 The <tt>start</tt>, <tt>stop</tt>, <tt>restart</tt>, and
4812 <tt>force-reload</tt> options should be supported by all
4813 scripts in <file>/etc/init.d</file>, the <tt>reload</tt>
4814 option is optional.</p>
4817 The <file>init.d</file> scripts should ensure that they will
4818 behave sensibly if invoked with <tt>start</tt> when the
4819 service is already running, or with <tt>stop</tt> when it
4820 isn't, and that they don't kill unfortunately-named user
4821 processes. The best way to achieve this is usually to use
4822 <prgn>start-stop-daemon</prgn>.</p>
4825 If a service reloads its configuration automatically (as
4826 in the case of <prgn>cron</prgn>, for example), the
4827 <tt>reload</tt> option of the <file>init.d</file> script
4828 should behave as if the configuration has been reloaded
4832 The <file>/etc/init.d</file> scripts must be treated as
4833 configuration files, either (if they are present in the
4834 package, that is, in the .deb file) by marking them as
4835 <tt>conffile</tt>s, or, (if they do not exist in the .deb)
4836 by managing them correctly in the maintainer scripts (see
4837 <ref id="config-files">). This is important since we want
4838 to give the local system administrator the chance to adapt
4839 the scripts to the local system, e.g., to disable a
4840 service without de-installing the package, or to specify
4841 some special command line options when starting a service,
4842 while making sure her changes aren't lost during the next
4847 These scripts should not fail obscurely when the
4848 configuration files remain but the package has been
4849 removed, as configuration files remain on the system after
4850 the package has been removed. Only when <prgn>dpkg</prgn>
4851 is executed with the <tt>--purge</tt> option will
4852 configuration files be removed. In particular, as the
4853 <file>/etc/init.d/<var>package</var></file> script itself is
4854 usually a <tt>conffile</tt>, it will remain on the system
4855 if the package is removed but not purged. Therefore, you
4856 should include a <tt>test</tt> statement at the top of the
4858 <example compact="compact">
4859 test -f <var>program-executed-later-in-script</var> || exit 0
4864 Often there are some variables in the <file>init.d</file>
4865 scripts whose values control the behaviour of the scripts,
4866 and which a system administrator is likely to want to
4867 change. As the scripts themselves are frequently
4868 <tt>conffile</tt>s, modifying them requires that the
4869 administrator merge in their changes each time the package
4870 is upgraded and the <tt>conffile</tt> changes. To ease
4871 the burden on the system administrator, such configurable
4872 values should not be placed directly in the script.
4873 Instead, they should be placed in a file in
4874 <file>/etc/default</file>, which typically will have the same
4875 base name as the <file>init.d</file> script. This extra file
4876 should be sourced by the script when the script runs. It
4877 must contain only variable settings and comments in POSIX
4878 <prgn>sh</prgn> format. It may either be a
4879 <tt>conffile</tt> or a configuration file maintained by
4880 the package maintainer scripts. See <ref id="config-files">
4885 To ensure that vital configurable values are always
4886 available, the <file>init.d</file> script should set default
4887 values for each of the shell variables it uses, either
4888 before sourcing the <file>/etc/default/</file> file or
4889 afterwards using something like the <tt>:
4890 ${VAR:=default}</tt> syntax. Also, the <file>init.d</file>
4891 script must behave sensibly and not fail if the
4892 <file>/etc/default</file> file is deleted.
4897 <heading>Interfacing with the initscript system</heading>
4900 Maintainers should use the abstraction layer provided by
4901 the <prgn>update-rc.d</prgn> and <prgn>invoke-rc.d</prgn>
4902 programs to deal with initscripts in their packages'
4903 scripts such as <prgn>postinst</prgn>, <prgn>prerm</prgn>
4904 and <prgn>postrm</prgn>.
4907 Directly managing the /etc/rc?.d links and directly
4908 invoking the <file>/etc/init.d/</file> initscripts should
4909 be done only by packages providing the initscript
4910 subsystem (such as <prgn>sysvinit</prgn> and
4911 <prgn>file-rc</prgn>).
4916 <heading>Managing the links</heading>
4919 The program <prgn>update-rc.d</prgn> is provided for
4920 package maintainers to arrange for the proper creation and
4921 removal of <file>/etc/rc<var>n</var>.d</file> symbolic links,
4922 or their functional equivalent if another method is being
4923 used. This may be used by maintainers in their packages'
4924 <prgn>postinst</prgn> and <prgn>postrm</prgn> scripts.</p>
4927 You must not include any <file>/etc/rc<var>n</var>.d</file>
4928 symbolic links in the actual archive or manually create or
4929 remove the symbolic links in maintainer scripts; you must
4930 use the <prgn>update-rc.d</prgn> program instead. (The
4931 former will fail if an alternative method of maintaining
4932 runlevel information is being used.) You must not include
4933 the <file>/etc/rc<var>n</var>.d</file> directories themselves
4934 in the archive either. (Only the <tt>sysvinit</tt>
4939 By default <prgn>update-rc.d</prgn> will start services in
4940 each of the multi-user state runlevels (2, 3, 4, and 5)
4941 and stop them in the halt runlevel (0), the single-user
4942 runlevel (1) and the reboot runlevel (6). The system
4943 administrator will have the opportunity to customize
4944 runlevels by simply adding, moving, or removing the
4945 symbolic links in <file>/etc/rc<var>n</var>.d</file> if
4946 symbolic links are being used, or by modifying
4947 <file>/etc/runlevel.conf</file> if the <tt>file-rc</tt> method
4952 To get the default behavior for your package, put in your
4953 <prgn>postinst</prgn> script
4954 <example compact="compact">
4955 update-rc.d <var>package</var> defaults
4957 and in your <prgn>postrm</prgn>
4958 <example compact="compact">
4959 if [ "$1" = purge ]; then
4960 update-rc.d <var>package</var> remove
4962 </example>. Note that if your package changes runlevels
4963 or priority, you may have to remove and recreate the links,
4964 since otherwise the old links may persist. Refer to the
4965 documentation of <prgn>update-rc.d</prgn></p>
4968 This will use a default sequence number of 20. If it does
4969 not matter when or in which order the <file>init.d</file>
4970 script is run, use this default. If it does, then you
4971 should talk to the maintainer of the <prgn>sysvinit</prgn>
4972 package or post to <tt>debian-devel</tt>, and they will
4973 help you choose a number.
4977 For more information about using <tt>update-rc.d</tt>,
4978 please consult its manpage <manref name="update-rc.d"
4984 <heading>Running initscripts</heading>
4986 The program <prgn>invoke-rc.d</prgn> is provided to make
4987 it easier for package maintainers to properly invoke an
4988 initscript, obeying runlevel and other locally-defined
4989 constraints that might limit a package's right to start,
4990 stop and otherwise manage services. This program may be
4991 used by maintainers in their packages' scripts.
4994 The use of <prgn>invoke-rc.d</prgn> to invoke the
4995 <file>/etc/init.d/*</file> initscripts is strongly
4996 recommended<footnote>
4998 In the future, the use of invoke-rc.d to invoke
4999 initscripts shall be made mandatory. Maintainers are
5000 advised to switch to invoke-rc.d as soon as
5002 </footnote>, instead of calling them directly.
5006 By default, <prgn>invoke-rc.d</prgn> will pass any
5007 action requests (start, stop, reload, restart...) to the
5008 <file>/etc/init.d</file> script, filtering out requests
5009 to start or restart a service out of its intended
5013 Most packages will simply need to change:
5014 <example compact="compact">/etc/init.d/<package>
5015 <action></example> in their <prgn>postinst</prgn>
5016 and <prgn>prerm</prgn> scripts to:
5017 <example compact="compact">
5018 if [ -x /usr/sbin/invoke-rc.d ] ; then
5019 invoke-rc.d <var>package</var> <action>
5021 /etc/init.d/<var>package</var> <action>
5025 A package should register its initscript services using
5026 <prgn>update-rc.d</prgn> before it tries to invoke them
5027 using <prgn>invoke-rc.d</prgn>. Invocation of
5028 unregistered services may fail.
5031 For more information about using
5032 <prgn>invoke-rc.d</prgn>, please consult its manpage
5033 <manref name="invoke-rc.d" section="8">.
5040 <heading>Boot-time initialization</heading>
5043 There used to be another directory, <file>/etc/rc.boot</file>,
5044 which contained scripts which were run once per machine
5045 boot. This has been deprecated in favour of links from
5046 <file>/etc/rcS.d</file> to files in <file>/etc/init.d</file> as
5047 described in <ref id="/etc/init.d">. Packages must not
5048 place files in <file>/etc/rc.boot</file>.</p>
5051 <heading>Example</heading>
5054 The <prgn>bind</prgn> DNS (nameserver) package wants to
5055 make sure that the nameserver is running in multiuser
5056 runlevels, and is properly shut down with the system. It
5057 puts a script in <file>/etc/init.d</file>, naming the script
5058 appropriately <tt>bind</tt>. As you can see, the script
5059 interprets the argument <tt>reload</tt> to send the
5060 nameserver a <tt>HUP</tt> signal (causing it to reload its
5061 configuration); this way the system administrator can say
5062 <tt>/etc/init.d/bind reload</tt> to reload the name
5063 server. The script has one configurable value, which can
5064 be used to pass parameters to the named program at
5065 startup; this value is read from
5066 <file>/etc/default/bind</file> (see below).
5070 <example compact="compact">
5073 # Original version by Robert Leslie
5074 # <rob@mars.org>, edited by iwj and cs
5076 test -x /usr/sbin/named || exit 0
5078 # Source defaults file.
5080 if [ -f /etc/default/bind ]; then
5087 echo -n "Starting domain name service: named"
5088 start-stop-daemon --start --quiet --exec /usr/sbin/named \
5093 echo -n "Stopping domain name service: named"
5094 start-stop-daemon --stop --quiet \
5095 --pidfile /var/run/named.pid --exec /usr/sbin/named
5099 echo -n "Restarting domain name service: named"
5100 start-stop-daemon --stop --quiet \
5101 --pidfile /var/run/named.pid --exec /usr/sbin/named
5102 start-stop-daemon --start --verbose --exec /usr/sbin/named \
5106 force-reload|reload)
5107 echo -n "Reloading configuration of domain name service: named"
5108 start-stop-daemon --stop --signal 1 --quiet \
5109 --pidfile /var/run/named.pid --exec /usr/sbin/named
5113 echo "Usage: /etc/init.d/bind " \
5114 " {start|stop|restart|reload|force-reload}" >&2
5124 Complementing the above init script is a configuration
5125 file <file>/etc/default/bind</file>, which contains
5126 configurable parameters used by the script. This would be
5127 created by the <prgn>postinst</prgn> script if it was not
5128 already present, and removed on purge by the
5129 <prgn>postrm</prgn> script.
5130 <example compact="compact">
5131 # Specified parameters to pass to named. See named(8).
5132 # You may uncomment the following line, and edit to taste.
5138 Another example on which you can base your
5139 <file>/etc/init.d</file> scripts is found in
5140 <file>/etc/init.d/skeleton</file>.
5144 If this package is happy with the default setup from
5145 <prgn>update-rc.d</prgn>, namely an ordering number of 20
5146 and having named running in all runlevels, it can say in
5147 its <prgn>postinst</prgn>:
5148 <example compact="compact">
5149 update-rc.d bind defaults >/dev/null
5151 And in its <prgn>postrm</prgn>, to remove the links when the
5153 <example compact="compact">
5154 if [ "$1" = purge ]; then
5155 update-rc.d bind remove >/dev/null
5163 <heading>Console messages from <file>init.d</file> scripts</heading>
5166 This section describes the formats to be used for messages
5167 written to standard output by the <file>/etc/init.d</file>
5168 scripts. The intent is to improve the consistency of
5169 Debian's startup and shutdown look and feel. For this
5170 reason, please look very carefully at the details. We want
5171 the messages to have the same format in terms of wording,
5172 spaces, punctuation and case of letters.
5176 Here is a list of overall rules that you should use when you
5177 create output messages. They can be useful if you have a
5178 non-standard message that is not covered specifically in the
5186 Every message should fit in one line (fewer than 80
5187 characters), start with a capital letter and end with
5188 a period (<tt>.</tt>) and line feed (<tt>"\n"</tt>).
5194 If you want to express that the computer is working on
5195 something (that is, performing a specific task, not
5196 starting or stopping a program), we use an "ellipsis"
5197 (three dots: <tt>...</tt>). Note that we don't insert
5198 spaces before or after the dots. If the task has been
5199 completed we write <tt>done.</tt> and a line feed.
5205 Design your messages as if the computer is telling you
5206 what he is doing (let him be polite :-), but don't
5207 mention "him" directly. For example, if you think of
5209 <example compact="compact">
5210 I'm starting network daemons: nfsd mountd.
5213 <example compact="compact">
5214 Starting network daemons: nfsd mountd.
5222 There are standard message formats for the following
5223 situations. They should be used by the <tt>init.d</tt>
5230 <p>When daemons are started</p>
5233 If your script starts one or more daemons, the output
5234 should look like this (a single line, no leading
5236 <example compact="compact">
5237 Starting <var>description</var>: <var>daemon-1</var> ... <var>daemon-n</var>.
5239 The <var>description</var> should describe the
5240 subsystem the daemon or set of daemons are part of,
5241 while <var>daemon-1</var> up to <var>daemon-n</var>
5242 denote each daemon's name (typically the file name of
5247 For example, the output of <file>/etc/init.d/lpd</file>
5249 <example compact="compact">
5250 Starting printer spooler: lpd.
5255 This can be achieved by saying
5256 <example compact="compact">
5257 echo -n "Starting printer spooler: lpd"
5258 start-stop-daemon --start --quiet --exec /usr/sbin/lpd
5261 in the script. If you have more than one daemon to
5262 start, you should do the following:
5263 <example compact="compact">
5264 echo -n "Starting remote file system services:"
5265 echo -n " nfsd"; start-stop-daemon --start --quiet nfsd
5266 echo -n " mountd"; start-stop-daemon --start --quiet mountd
5267 echo -n " ugidd"; start-stop-daemon --start --quiet ugidd
5270 This makes it possible for the user to see what takes
5271 so long and when the final daemon has been started.
5272 You should be careful where to put spaces: in the
5273 example above the system administrator can easily
5274 comment out a line if he don't wants to start a
5275 specific daemon, while the displayed message still
5281 <p>When a system parameter is being set</p>
5284 If you have to set up different system parameters
5285 during the system boot, you should use this format:
5286 <example compact="compact">
5287 Setting <var>parameter</var> to "<var>value</var>".
5292 You can use a statement such as the following to get
5294 <example compact="compact">
5295 echo "Setting DNS domainname to \"$domainname\"."
5300 Note that the same symbol (<tt>"</tt>) is used for the left
5301 and right quotation marks. A grave accent (<tt>`</tt>) is
5302 not a quote character; neither is an apostrophe
5308 <p>When a daemon is stopped or restarted</p>
5311 When you stop or restart a daemon, you should issue a
5312 message identical to the startup message, except that
5313 <tt>Starting</tt> is replaced with <tt>Stopping</tt>
5314 or <tt>Restarting</tt> respectively.
5318 For example, stopping the printer daemon will like
5320 <example compact="compact">
5321 Stopping printer spooler: lpd.
5327 <p>When something is executed</p>
5330 There are several examples where you have to run a
5331 program at system startup or shutdown to perform a
5332 specific task, for example, setting the system's clock
5333 using <prgn>netdate</prgn> or killing all processes
5334 when the system shuts down. Your message should look
5336 <example compact="compact">
5337 Doing something very useful...done.
5339 You should print the <tt>done.</tt> immediately after
5340 the job has been completed, so that the user is
5341 informed why she has to wait. You can get this
5343 <example compact="compact">
5344 echo -n "Doing something very useful..."
5353 <p>When the configuration is reloaded</p>
5356 When a daemon is forced to reload its configuration
5357 files you should use the following format:
5358 <example compact="compact">
5359 Reloading <var>description</var> configuration...done.
5361 where <var>description</var> is the same as in the
5362 daemon starting message.
5370 <heading>Cron jobs</heading>
5373 Packages must not modify the configuration file
5374 <file>/etc/crontab</file>, and they must not modify the files in
5375 <file>/var/spool/cron/crontabs</file>.</p>
5378 If a package wants to install a job that has to be executed
5379 via cron, it should place a file with the name of the
5380 package in one or more of the following directories:
5381 <example compact="compact">
5386 As these directory names imply, the files within them are
5387 executed on a daily, weekly, or monthly basis,
5388 respectively. The exact times are listed in
5389 <file>/etc/crontab</file>.</p>
5392 All files installed in any of these directories must be
5393 scripts (e.g., shell scripts or Perl scripts) so that they
5394 can easily be modified by the local system administrator.
5395 In addition, they should be treated as configuration
5400 If a certain job has to be executed more frequently than
5401 daily, the package should install a file
5402 <file>/etc/cron.d/<var>package</var></file>. This file uses the
5403 same syntax as <file>/etc/crontab</file> and is processed by
5404 <prgn>cron</prgn> automatically. The file must also be
5405 treated as a configuration file. (Note that entries in the
5406 <file>/etc/cron.d</file> directory are not handled by
5407 <prgn>anacron</prgn>. Thus, you should only use this
5408 directory for jobs which may be skipped if the system is not
5412 The scripts or crontab entries in these directories should
5413 check if all necessary programs are installed before they
5414 try to execute them. Otherwise, problems will arise when a
5415 package was removed but not purged since configuration files
5416 are kept on the system in this situation.</p>
5420 <heading>Menus</heading>
5423 The Debian <tt>menu</tt> package provides a standard
5424 interface between packages providing applications and
5425 documents, and <em>menu programs</em> (either X window
5426 managers or text-based menu programs such as
5427 <prgn>pdmenu</prgn>).
5431 All packages that provide applications that need not be
5432 passed any special command line arguments for normal
5433 operation should register a menu entry for those
5434 applications, so that users of the <tt>menu</tt> package
5435 will automatically get menu entries in their window
5436 managers, as well in shells like <tt>pdmenu</tt>.
5440 Menu entries should follow the current menu policy.
5444 The menu policy can be found in the <tt>menu-policy</tt>
5445 files in the <tt>debian-policy</tt> package.
5446 They are also available from the Debian web mirrors at
5447 <tt><url name="/doc/packaging-manuals/menu-policy/"
5448 id="http://www.debian.org/doc/packaging-manuals/menu-policy/"></tt>
5449 and from the Debian archive mirrors at
5450 <tt><url name="/doc/package-developer/menu-policy.txt.gz"
5451 id="http://ftp.debian.org/debian/doc/package-developer/menu-policy.txt.gz"></tt>.
5455 Please also refer to the <em>Debian Menu System</em>
5456 documentation that comes with the <tt>menu</tt> package for
5457 information about how to register your applications and web
5463 <heading>Multimedia handlers</heading>
5466 MIME (Multipurpose Internet Mail Extensions, RFCs 2045-2049)
5467 is a mechanism for encoding files and data streams and
5468 providing meta-information about them, in particular their
5469 type (e.g. audio or video) and format (e.g. PNG, HTML,
5474 Registration of MIME type handlers allows programs like mail
5475 user agents and web browsers to to invoke these handlers to
5476 view, edit or display MIME types they don't support
5481 Packages which provide the ability to view/show/play,
5482 compose, edit or print MIME types should register themselves
5483 as such following the current MIME support policy.
5487 The MIME support policy can be found in the <tt>mime-policy</tt>
5488 files in the <tt>debian-policy</tt> package.
5489 They are also available from the Debian web mirrors at
5490 <tt><url name="/doc/packaging-manuals/mime-policy/"
5491 id="http://www.debian.org/doc/packaging-manuals/mime-policy/"></tt>
5492 and from the Debian archive mirrors at
5493 <tt><url name="/doc/package-developer/mime-policy.txt.gz"
5494 id="http://ftp.debian.org/debian/doc/package-developer/mime-policy.txt.gz"></tt>.
5500 <heading>Keyboard configuration</heading>
5503 To achieve a consistent keyboard configuration so that all
5504 applications interpret a keyboard event the same way, all
5505 programs in the Debian distribution must be configured to
5506 comply with the following guidelines.
5510 The following keys must have the specified interpretations:
5513 <tag><tt><--</tt></tag>
5514 <item><p>delete the character to the left of the cursor</p></item>
5516 <tag><tt>Delete</tt></tag>
5517 <item><p>delete the character to the right of the cursor</p></item>
5519 <tag><tt>Control+H</tt></tag>
5520 <item><p>emacs: the help prefix</p></item>
5523 The interpretation of any keyboard events should be
5524 independent of the terminal that is used, be it a virtual
5525 console, an X terminal emulator, an rlogin/telnet session,
5530 The following list explains how the different programs
5531 should be set up to achieve this:
5536 <item><p><tt><--</tt> generates <tt>KB_BackSpace</tt>
5539 <item><p><tt>Delete</tt> generates <tt>KB_Delete</tt> in
5544 X translations are set up to make
5545 <tt>KB_Backspace</tt> generate ASCII DEL, and to make
5546 <tt>KB_Delete</tt> generate <tt>ESC [ 3 ~</tt> (this
5547 is the vt220 escape code for the "delete character"
5548 key). This must be done by loading the X resources
5549 using <prgn>xrdb</prgn> on all local X displays, not
5550 using the application defaults, so that the
5551 translation resources used correspond to the
5552 <prgn>xmodmap</prgn> settings.</p></item>
5556 The Linux console is configured to make
5557 <tt><--</tt> generate DEL, and <tt>Delete</tt>
5558 generate <tt>ESC [ 3 ~</tt>.</p></item>
5562 X applications are configured so that <tt><</tt>
5563 deletes left, and <tt>Delete</tt> deletes right. Motif
5564 applications already work like this.</p></item>
5566 <item><p>Terminals should have <tt>stty erase ^?</tt> .</p></item>
5570 The <tt>xterm</tt> terminfo entry should have <tt>ESC
5571 [ 3 ~</tt> for <tt>kdch1</tt>, just as for
5572 <tt>TERM=linux</tt> and <tt>TERM=vt220</tt>.</p></item>
5576 Emacs is programmed to map <tt>KB_Backspace</tt> or
5577 the <tt>stty erase</tt> character to
5578 <tt>delete-backward-char</tt>, and <tt>KB_Delete</tt>
5579 or <tt>kdch1</tt> to <tt>delete-forward-char</tt>, and
5580 <tt>^H</tt> to <tt>help</tt> as always.</p></item>
5584 Other applications use the <tt>stty erase</tt>
5585 character and <tt>kdch1</tt> for the two delete keys,
5586 with ASCII DEL being "delete previous character" and
5587 <tt>kdch1</tt> being "delete character under
5594 This will solve the problem except for the following
5602 Some terminals have a <tt><--</tt> key that cannot
5603 be made to produce anything except <tt>^H</tt>. On
5604 these terminals Emacs help will be unavailable on
5605 <tt>^H</tt> (assuming that the <tt>stty erase</tt>
5606 character takes precedence in Emacs, and has been set
5607 correctly). <tt>M-x help</tt> or <tt>F1</tt> (if
5608 available) can be used instead.</p></item>
5612 Some operating systems use <tt>^H</tt> for <tt>stty
5613 erase</tt>. However, modern telnet versions and all
5614 rlogin versions propagate <tt>stty</tt> settings, and
5615 almost all UNIX versions honour <tt>stty erase</tt>.
5616 Where the <tt>stty</tt> settings are not propagated
5617 correctly, things can be made to work by using
5618 <tt>stty</tt> manually.</p></item>
5622 Some systems (including previous Debian versions) use
5623 <prgn>xmodmap</prgn> to arrange for both
5624 <tt><--</tt> and <tt>Delete</tt> to generate
5625 <tt>KB_Delete</tt>. We can change the behavior of
5626 their X clients using the same X resources that we use
5627 to do it for our own clients, or configure our clients
5628 using their resources when things are the other way
5629 around. On displays configured like this
5630 <tt>Delete</tt> will not work, but <tt><--</tt>
5635 Some operating systems have different <tt>kdch1</tt>
5636 settings in their <tt>terminfo</tt> database for
5637 <tt>xterm</tt> and others. On these systems the
5638 <tt>Delete</tt> key will not work correctly when you
5639 log in from a system conforming to our policy, but
5640 <tt><--</tt> will.</p></item>
5646 <heading>Environment variables</heading>
5649 A program must not depend on environment variables to get
5650 reasonable defaults. (That's because these environment
5651 variables would have to be set in a system-wide
5652 configuration file like <file>/etc/profile</file>, which is not
5653 supported by all shells.)</p>
5656 If a program usually depends on environment variables for its
5657 configuration, the program should be changed to fall back to
5658 a reasonable default configuration if these environment
5659 variables are not present. If this cannot be done easily
5660 (e.g., if the source code of a non-free program is not
5661 available), the program must be replaced by a small
5662 "wrapper" shell script which sets the environment variables
5663 if they are not already defined, and calls the original program.</p>
5666 Here is an example of a wrapper script for this purpose:
5668 <example compact="compact">
5670 BAR=${BAR:-/var/lib/fubar}
5672 exec /usr/lib/foo/foo "$@"
5677 Furthermore, as <file>/etc/profile</file> is a configuration
5678 file of the <prgn>base-files</prgn> package, other packages must not
5679 put any environment variables or other commands into that
5685 <heading>Files</heading>
5688 <heading>Binaries</heading>
5691 Two different packages must not install programs with
5692 different functionality but with the same filenames. (The
5693 case of two programs having the same functionality but
5694 different implementations is handled via "alternatives" or
5695 the "Conflicts" mechanism. See <ref id="maintscripts"> and
5696 <ref id="conflicts"> respectively.) If this case happens,
5697 one of the programs must be renamed. The maintainers should
5698 report this to the <tt>debian-devel</tt> mailing list and
5699 try to find a consensus about which program will have to be
5700 renamed. If a consensus cannot be reached, <em>both</em>
5701 programs must be renamed.
5705 By default, when a package is being built, any binaries
5706 created should include debugging information, as well as
5707 being compiled with optimization. You should also turn on
5708 as many reasonable compilation warnings as possible; this
5709 makes life easier for porters, who can then look at build
5710 logs for possible problems. For the C programming language,
5711 this means the following compilation parameters should be
5713 <example compact="compact">
5715 CFLAGS = -O2 -g -Wall # sane warning options vary between programs
5717 install -s # (or use strip on the files in debian/tmp)
5722 Note that by default all installed binaries should be stripped,
5723 either by using the <tt>-s</tt> flag to
5724 <prgn>install</prgn>, or by calling <prgn>strip</prgn> on
5725 the binaries after they have been copied into
5726 <file>debian/tmp</file> but before the tree is made into a
5730 Although binaries in the build tree should be compiled with
5731 debugging information by default, it can often be difficult
5732 to debug programs if they are also subjected to compiler
5733 optimization. For this reason, it is recommended to support
5734 the standardized environment
5735 variable <tt>DEB_BUILD_OPTIONS</tt>. This variable can
5736 contain several flags to change how a package is compiled
5744 The presence of this string means that the package
5745 should be complied with a minimum of optimization.
5746 For C programs, it is best to add <tt>-O0</tt>
5747 to <tt>CFLAGS</tt> (although this is usually the
5748 default). Some programs might fail to build or run at
5749 this level of optimization; it may be necessary to
5750 use <tt>-O1</tt>, for example.
5756 This string means that the debugging symbols should
5757 not be stripped from the binary during installation,
5758 so that debugging information may be included in the package.
5764 The following makefile snippet is an example of how one may
5765 implement the build options; you will probably have to
5766 massage this example in order to make it work for your
5768 <example compact="compact">
5771 INSTALL_FILE = $(INSTALL) -p -o root -g root -m 644
5772 INSTALL_PROGRAM = $(INSTALL) -p -o root -g root -m 755
5773 INSTALL_SCRIPT = $(INSTALL) -p -o root -g root -m 755
5774 INSTALL_DIR = $(INSTALL) -p -d -o root -g root -m 755
5776 ifneq (,$(findstring noopt,$(DEB_BUILD_OPTIONS)))
5781 ifeq (,$(findstring nostrip,$(DEB_BUILD_OPTIONS)))
5782 INSTALL_PROGRAM += -s
5788 It is up to the package maintainer to decide what
5789 compilation options are best for the package. Certain
5790 binaries (such as computationally-intensive programs) will
5791 function better with certain flags (<tt>-O3</tt>, for
5792 example); feel free to use them. Please use good judgment
5793 here. Don't use flags for the sake of it; only use them
5794 if there is good reason to do so. Feel free to override
5795 the upstream author's ideas about which compilation
5796 options are best: they are often inappropriate for our
5802 <sect id="libraries">
5803 <heading>Libraries</heading>
5806 The shared version of a library must be compiled with
5807 <tt>-fPIC</tt>, and the static version must not be. In other
5808 words, each source unit (<tt>*.c</tt>, for example, for C files)
5809 will need to be compiled twice.
5814 You must specify the gcc option <tt>-D_REENTRANT</tt>
5815 when building a library (either static or shared) to make
5816 the library compatible with LinuxThreads.
5820 All installed shared libraries should be stripped with
5821 <example compact="compact">
5822 strip --strip-unneeded <var>your-lib</var>
5824 (The option <tt>--strip-unneeded</tt> makes
5825 <prgn>strip</prgn> remove only the symbols which aren't
5826 needed for relocation processing.) Shared libraries can
5827 function perfectly well when stripped, since the symbols for
5828 dynamic linking are in a separate part of the ELF object
5831 You might also want to use the options
5832 <tt>--remove-section=.comment</tt> and
5833 <tt>--remove-section=.note</tt> on both shared libraries
5834 and executables, and <tt>--strip-debug</tt> on static
5841 Note that under some circumstances it may be useful to
5842 install a shared library unstripped, for example when
5843 building a separate package to support debugging.
5847 Shared object files (often <file>.so</file> files) that are not
5848 public libraries, that is, they are not meant to be linked
5849 to by third party executables (binaries of other packages),
5850 should be installed in subdirectories of the
5851 <file>/usr/lib</file> directory. Such files are exempt from the
5852 rules that govern ordinary shared libraries, except that
5853 they must not be installed executable and should be
5856 A common example are the so-called "plug-ins",
5857 internal shared objects that are dynamically loaded by
5858 programs using <manref name="dlopen" section="3">.
5864 Packages containing shared libraries that may be linked to
5865 by other packages' binaries, but which for some
5866 <em>compelling</em> reason can not be installed in
5867 <file>/usr/lib</file> directory, may install the shared library
5868 files in subdirectories of the <file>/usr/lib</file> directory,
5869 in which case they should arrange to add that directory in
5870 <file>/etc/ld.so.conf</file> in the package's post-installation
5871 script, and remove it in the package's post-removal script.
5875 An ever increasing number of packages are using
5876 <prgn>libtool</prgn> to do their linking. The latest GNU
5877 libtools (>= 1.3a) can take advantage of the metadata in the
5878 installed <prgn>libtool</prgn> archive files (<file>*.la</file>
5879 files). The main advantage of <prgn>libtool</prgn>'s
5880 <file>.la</file> files is that it allows <prgn>libtool</prgn> to
5881 store and subsequently access metadata with respect to the
5882 libraries it builds. <prgn>libtool</prgn> will search for
5883 those files, which contain a lot of useful information about
5884 a library (such as library dependency information for static
5885 linking). Also, they're <em>essential</em> for programs
5886 using <tt>libltdl</tt>.<footnote>
5888 Although <prgn>libtool</prgn> is fully capable of
5889 linking against shared libraries which don't have
5890 <tt>.la</tt> files, as it is a mere shell script it can
5891 add considerably to the build time of a
5892 <prgn>libtool</prgn>-using package if that shell script
5893 has to derive all this information from first principles
5894 for each library every time it is linked. With the
5895 advent of <prgn>libtool</prgn> version 1.4 (and to a
5896 lesser extent <prgn>libtool</prgn> version 1.3), the
5897 <file>.la</file> files also store information about
5898 inter-library dependencies which cannot necessarily be
5899 derived after the <file>.la</file> file is deleted.
5905 Packages that use <prgn>libtool</prgn> to create shared
5906 libraries should include the <file>.la</file> files in the
5907 <tt>-dev</tt> package, unless the package relies on
5908 <tt>libtool</tt>'s <tt>libltdl</tt> library, in which case
5909 the <tt>.la</tt> files must go in the run-time library
5914 You must make sure that you use only released versions of
5915 shared libraries to build your packages; otherwise other
5916 users will not be able to run your binaries
5917 properly. Producing source packages that depend on
5918 unreleased compilers is also usually a bad
5925 <heading>Shared libraries</heading>
5927 This section has moved to <ref id="sharedlibs">.
5933 <heading>Scripts</heading>
5936 All command scripts, including the package maintainer
5937 scripts inside the package and used by <prgn>dpkg</prgn>,
5938 should have a <tt>#!</tt> line naming the shell to be used
5939 to interpret them.</p>
5942 In the case of Perl scripts this should be
5943 <tt>#!/usr/bin/perl</tt>.</p>
5946 Shell scripts (<prgn>sh</prgn> and <prgn>bash</prgn>)
5947 should almost certainly start with <tt>set -e</tt> so that
5948 errors are detected. Every script should use
5949 <tt>set -e</tt> or check the exit status of <em>every</em>
5953 The standard shell interpreter <file>/bin/sh</file> can be a
5954 symbolic link to any POSIX compatible shell, if <tt>echo
5955 -n</tt> does not generate a newline.<footnote>
5957 Debian policy specifies POSIX behavior for
5958 <file>/bin/sh</file>, but <tt>echo -n</tt> has widespread
5959 use in the Linux community (in particular including this
5960 policy, the Linux kernel source, many Debian scripts,
5961 etc.). This <tt>echo -n</tt> mechanism is valid but not
5962 required under POSIX, hence this explicit addition.
5963 Also, rumour has it that this shall be mandated under
5967 Thus, shell scripts specifying <file>/bin/sh</file> as
5968 interpreter should only use POSIX features. If a script
5969 requires non-POSIX features from the shell interpreter, the
5970 appropriate shell must be specified in the first line of the
5971 script (e.g., <tt>#!/bin/bash</tt>) and the package must
5972 depend on the package providing the shell (unless the shell
5973 package is marked "Essential", as in the case of
5978 You may wish to restrict your script to POSIX features when
5979 possible so that it may use <file>/bin/sh</file> as its
5980 interpreter. If your script works with <prgn>dash</prgn>
5981 (originally called <prgn>ash</prgn>), it's probably POSIX
5982 compliant, but if you are in doubt, use
5983 <file>/bin/bash</file>.
5987 Perl scripts should check for errors when making any
5988 system calls, including <tt>open</tt>, <tt>print</tt>,
5989 <tt>close</tt>, <tt>rename</tt> and <tt>system</tt>.
5993 <prgn>csh</prgn> and <prgn>tcsh</prgn> should be avoided as
5994 scripting languages. See <em>Csh Programming Considered
5995 Harmful</em>, one of the <tt>comp.unix.*</tt> FAQs, which
5996 can be found at <url
5997 id="http://language.perl.com/versus/csh.whynot">.<footnote>
5999 It can also be found on
6000 <url id="http://www.cpan.org/doc/FMTEYEWTK/versus/csh.whynot">
6001 or on the ftp site <ftpsite>ftp.cpan.org</ftpsite> as
6002 <ftppath>/pub/perl/CPAN/doc/FMTEYEWTK/versus/csh.whynot</ftppath>.
6005 If an upstream package comes with <prgn>csh</prgn> scripts
6006 then you must make sure that they start with
6007 <tt>#!/bin/csh</tt> and make your package depend on the
6008 <prgn>c-shell</prgn> virtual package.
6012 Any scripts which create files in world-writeable
6013 directories (e.g., in <file>/tmp</file>) must use a
6014 mechanism which will fail if a file with the same name
6018 The Debian base system provides the <prgn>tempfile</prgn>
6019 and <prgn>mktemp</prgn> utilities for use by scripts for
6020 this purpose.</p></sect>
6024 <heading>Symbolic links</heading>
6027 In general, symbolic links within a top-level directory
6028 should be relative, and symbolic links pointing from one
6029 top-level directory into another should be absolute. (A
6030 top-level directory is a sub-directory of the root
6031 directory <file>/</file>.)</p>
6034 In addition, symbolic links should be specified as short as
6035 possible, i.e., link targets like <file>foo/../bar</file> are
6039 Note that when creating a relative link using
6040 <prgn>ln</prgn> it is not necessary for the target of the
6041 link to exist relative to the working directory you're
6042 running <prgn>ln</prgn> from, nor is it necessary to change
6043 directory to the directory where the link is to be made.
6044 Simply include the string that should appear as the target
6045 of the link (this will be a pathname relative to the
6046 directory in which the link resides) as the first argument
6047 to <prgn>ln</prgn>.</p>
6050 For example, in your <prgn>Makefile</prgn> or
6051 <file>debian/rules</file>, you can do things like:
6052 <example compact="compact">
6053 ln -fs gcc $(prefix)/bin/cc
6054 ln -fs gcc debian/tmp/usr/bin/cc
6055 ln -fs ../sbin/sendmail $(prefix)/bin/runq
6056 ln -fs ../sbin/sendmail debian/tmp/usr/bin/runq
6060 A symbolic link pointing to a compressed file should always
6061 have the same file extension as the referenced file. (For
6062 example, if a file <file>foo.gz</file> is referenced by a
6063 symbolic link, the filename of the link has to end with
6064 "<file>.gz</file>" too, as in <file>bar.gz</file>.)
6069 <heading>Device files</heading>
6072 Packages must not include device files in the package file
6076 If a package needs any special device files that are not
6077 included in the base system, it must call
6078 <prgn>MAKEDEV</prgn> in the <prgn>postinst</prgn> script,
6079 after notifying the user<footnote>
6081 This notification could be done via a (low-priority)
6082 debconf message, or an echo (printf) statement.
6088 Packages must not remove any device files in the
6089 <prgn>postrm</prgn> or any other script. This is left to the
6090 system administrator.</p>
6093 Debian uses the serial devices
6094 <file>/dev/ttyS*</file>. Programs using the old
6095 <file>/dev/cu*</file> devices should be changed to use
6096 <file>/dev/ttyS*</file>.</p>
6099 <sect id="config-files">
6100 <heading>Configuration files</heading>
6102 <heading>Definitions</heading>
6105 <tag>configuration file</tag>
6108 A file that affects the operation of a program, or
6109 provides site- or host-specific information, or
6110 otherwise customizes the behavior of a program.
6111 Typically, configuration files are intended to be
6112 modified by the system administrator (if needed or
6113 desired) to conform to local policy or to provide
6114 more useful site-specific behavior.
6118 <tag><tt>conffile</tt></tag>
6121 A file listed in a package's <tt>conffiles</tt>
6122 file, and is treated specially by <prgn>dpkg</prgn>
6123 (see <ref id="configdetails">).
6130 The distinction between these two is important; they are
6131 not interchangeable concepts. Almost all
6132 <tt>conffile</tt>s are configuration files, but many
6133 configuration files are not <tt>conffiles</tt>.
6137 Note that a script that embeds configuration information
6138 (such as most of the files in <file>/etc/default</file> and
6139 <file>/etc/cron.{daily,weekly,monthly}</file>) is de-facto a
6140 configuration file and should be treated as such.
6145 <heading>Location</heading>
6147 Any configuration files created or used by your package
6148 must reside in <file>/etc</file>. If there are several,
6149 consider creating a subdirectory of <file>/etc</file>
6150 named after your package.</p>
6153 If your package creates or uses configuration files
6154 outside of <file>/etc</file>, and it is not feasible to modify
6155 the package to use <file>/etc</file> directly, put the files
6156 in <file>/etc</file> and create symbolic links to those files
6157 from the location that the package requires.</p>
6161 <heading>Behavior</heading>
6163 Configuration file handling must conform to the following
6165 <list compact="compact">
6168 local changes must be preserved during a package
6174 configuration files must be preserved when the
6175 package is removed, and only deleted when the
6183 The easy way to achieve this behavior is to make the
6184 configuration file a <tt>conffile</tt>. This is
6185 appropriate only if it is possible to distribute a default
6186 version that will work for most installations, although
6187 some system administrators may choose to modify it. This
6188 implies that the default version will be part of the
6189 package distribution, and must not be modified by the
6190 maintainer scripts during installation (or at any other
6195 In order to ensure that local changes are preserved
6196 correctly, no package may contain or make hard links to
6197 conffiles.<footnote>
6199 Rationale: There are two problems with hard links.
6200 The first is that some editors break the link while
6201 editing one of the files, so that the two files may
6202 unwittingly become unlinked and different. The second
6203 is that <prgn>dpkg</prgn> might break the hard link
6204 while upgrading <tt>conffile</tt>s.
6210 The other way to do it is via the maintainer scripts. In
6211 this case, the configuration file must not be listed as a
6212 <tt>conffile</tt> and must not be part of the package
6213 distribution. If the existence of a file is required for
6214 the package to be sensibly configured it is the
6215 responsibility of the package maintainer to provide
6216 maintainer scripts which correctly create, update and
6217 maintain the file and remove it on purge. (See <ref
6218 id="maintainerscripts"> for more information.) These
6219 scripts must be idempotent (i.e., must work correctly if
6220 <prgn>dpkg</prgn> needs to re-run them due to errors
6221 during installation or removal), must cope with all the
6222 variety of ways <prgn>dpkg</prgn> can call maintainer
6223 scripts, must not overwrite or otherwise mangle the user's
6224 configuration without asking, must not ask unnecessary
6225 questions (particularly during upgrades), and otherwise be
6230 The scripts are not required to configure every possible
6231 option for the package, but only those necessary to get
6232 the package running on a given system. Ideally the
6233 sysadmin should not have to do any configuration other
6234 than that done (semi-)automatically by the
6235 <prgn>postinst</prgn> script.
6239 A common practice is to create a script called
6240 <file><var>package</var>-configure</file> and have the
6241 package's <prgn>postinst</prgn> call it if and only if the
6242 configuration file does not already exist. In certain
6243 cases it is useful for there to be an example or template
6244 file which the maintainer scripts use. Such files should
6245 be in <file>/usr/share/<var>package</var></file> or
6246 <file>/usr/lib/<var>package</var></file> (depending on whether
6247 they are architecture-independent or not). There should
6248 be symbolic links to them from
6249 <file>/usr/share/doc/<var>package</var>/examples</file> if
6250 they are examples, and should be perfectly ordinary
6251 <prgn>dpkg</prgn>-handled files (<em>not</em>
6252 configuration files).
6256 These two styles of configuration file handling must
6257 not be mixed, for that way lies madness:
6258 <prgn>dpkg</prgn> will ask about overwriting the file
6259 every time the package is upgraded.
6264 <heading>Sharing configuration files</heading>
6266 Packages which specify the same file as a
6267 <tt>conffile</tt> must be tagged as <em>conflicting</em>
6268 with each other. (This is an instance of the general rule
6269 about not sharing files. Note that neither alternatives
6270 nor diversions are likely to be appropriate in this case;
6271 in particular, <prgn>dpkg</prgn> does not handle diverted
6272 <tt>conffile</tt>s well.)
6276 The maintainer scripts must not alter a <tt>conffile</tt>
6277 of <em>any</em> package, including the one the scripts
6282 If two or more packages use the same configuration file
6283 and it is reasonable for both to be installed at the same
6284 time, one of these packages must be defined as
6285 <em>owner</em> of the configuration file, i.e., it will be
6286 the package which handles that file as a configuration
6287 file. Other packages that use the configuration file must
6288 depend on the owning package if they require the
6289 configuration file to operate. If the other package will
6290 use the configuration file if present, but is capable of
6291 operating without it, no dependency need be declared.</p>
6294 If it is desirable for two or more related packages to
6295 share a configuration file <em>and</em> for all of the
6296 related packages to be able to modify that configuration
6297 file, then the following should be done:
6298 <enumlist compact="compact">
6301 One of the related packages (the "owning" package)
6302 will manage the configuration file with maintainer
6303 scripts as described in the previous section.
6308 The owning package should also provide a program
6309 that the other packages may use to modify the
6315 The related packages must use the provided program
6316 to make any desired modifications to the
6317 configuration file. They should either depend on
6318 the core package to guarantee that the configuration
6319 modifier program is available or accept gracefully
6320 that they cannot modify the configuration file if it
6321 is not. (This is in addition to the fact that the
6322 configuration file may not even be present in the
6330 Sometimes it's appropriate to create a new package which
6331 provides the basic infrastructure for the other packages
6332 and which manages the shared configuration files. (The
6333 <tt>sgml-base</tt> package is a good example.)
6338 <heading>User configuration files ("dotfiles")</heading>
6341 The files in <file>/etc/skel</file> will automatically be
6342 copied into new user accounts by <prgn>adduser</prgn>.
6343 No other program should reference the files in
6344 <file>/etc/skel</file>.
6348 Therefore, if a program needs a dotfile to exist in
6349 advance in <file>$HOME</file> to work sensibly, that dotfile
6350 should be installed in <file>/etc/skel</file> and treated as a
6355 However, programs that require dotfiles in order to
6356 operate sensibly are a bad thing, unless they do create
6357 the dotfiles themselves automatically.
6361 Furthermore, programs should be configured by the Debian
6362 default installation to behave as closely to the upstream
6363 default behaviour as possible.
6367 Therefore, if a program in a Debian package needs to be
6368 configured in some way in order to operate sensibly, that
6369 should be done using a site-wide configuration file placed
6370 in <file>/etc</file>. Only if the program doesn't support a
6371 site-wide default configuration and the package maintainer
6372 doesn't have time to add it may a default per-user file be
6373 placed in <file>/etc/skel</file>.
6377 <file>/etc/skel</file> should be as empty as we can make it.
6378 This is particularly true because there is no easy (or
6379 necessarily desirable) mechanism for ensuring that the
6380 appropriate dotfiles are copied into the accounts of
6381 existing users when a package is installed.
6387 <heading>Log files</heading>
6389 Log files should usually be named
6390 <file>/var/log/<var>package</var>.log</file>. If you have many
6391 log files, or need a separate directory for permission
6392 reasons (<file>/var/log</file> is writable only by
6393 <file>root</file>), you should usually create a directory named
6394 <file>/var/log/<var>package</var></file> and place your log
6399 Log files must be rotated occasionally so that they don't
6400 grow indefinitely; the best way to do this is to drop a log
6401 rotation configuration file into the directory
6402 <file>/etc/logrotate.d</file> and use the facilities provided by
6403 logrotate.<footnote>
6405 The traditional approach to log files has been to set up
6406 <em>ad hoc</em> log rotation schemes using simple shell
6407 scripts and cron. While this approach is highly
6408 customizable, it requires quite a lot of sysadmin work.
6409 Even though the original Debian system helped a little
6410 by automatically installing a system which can be used
6411 as a template, this was deemed not enough.
6415 The use of <prgn>logrotate</prgn>, a program developed
6416 by Red Hat, is better, as it centralizes log management.
6417 It has both a configuration file
6418 (<file>/etc/logrotate.conf</file>) and a directory where
6419 packages can drop their individual log rotation
6420 configurations (<file>/etc/logrotate.d</file>).
6423 Here is a good example for a logrotate config
6424 file (for more information see <manref name="logrotate"
6426 <example compact="compact">
6427 /var/log/foo/*.log {
6432 /etc/init.d/foo force-reload
6436 This rotates all files under <file>/var/log/foo</file>, saves 12
6437 compressed generations, and forces the daemon to reload its
6438 configuration information after the log rotation.
6442 Log files should be removed when the package is
6443 purged (but not when it is only removed). This should be
6444 done by the <prgn>postrm</prgn> script when it is called
6445 with the argument <tt>purge</tt> (see <ref
6446 id="removedetails">).
6451 <heading>Permissions and owners</heading>
6454 The rules in this section are guidelines for general use.
6455 If necessary you may deviate from the details below.
6456 However, if you do so you must make sure that what is done
6457 is secure and you should try to be as consistent as possible
6458 with the rest of the system. You should probably also
6459 discuss it on <prgn>debian-devel</prgn> first.
6463 Files should be owned by <tt>root.root</tt>, and made
6464 writable only by the owner and universally readable (and
6465 executable, if appropriate), that is mode 644 or 755.
6469 Directories should be mode 755 or (for group-writability)
6470 mode 2775. The ownership of the directory should be
6471 consistent with its mode: if a directory is mode 2775, it
6472 should be owned by the group that needs write access to
6477 Setuid and setgid executables should be mode 4755 or 2755
6478 respectively, and owned by the appropriate user or group.
6479 They should not be made unreadable (modes like 4711 or
6480 2711 or even 4111); doing so achieves no extra security,
6481 because anyone can find the binary in the freely available
6482 Debian package; it is merely inconvenient. For the same
6483 reason you should not restrict read or execute permissions
6484 on non-set-id executables.
6488 Some setuid programs need to be restricted to particular
6489 sets of users, using file permissions. In this case they
6490 should be owned by the uid to which they are set-id, and by
6491 the group which should be allowed to execute them. They
6492 should have mode 4754; again there is no point in making
6493 them unreadable to those users who must not be allowed to
6498 It is possible to arrange that the system administrator can
6499 reconfigure the package to correspond to their local
6500 security policy by changing the permissions on a binary:
6501 they can do this by using <prgn>dpkg-statoverride</prgn>, as
6502 described below.<footnote>
6504 Ordinary files installed by <prgn>dpkg</prgn> (as
6505 opposed to <tt>conffile</tt>s and other similar objects)
6506 normally have their permissions reset to the distributed
6507 permissions when the package is reinstalled. However,
6508 the use of <prgn>dpkg-statoverride</prgn> overrides this
6509 default behaviour. If you use this method, you should
6510 remember to describe <prgn>dpkg-statoverride</prgn> in
6511 the package documentation; being a relatively new
6512 addition to Debian, it is probably not yet well-known.
6515 Another method you should consider is to create a group for
6516 people allowed to use the program(s) and make any setuid
6517 executables executable only by that group.
6521 If you need to create a new user or group for your package
6522 there are two possibilities. Firstly, you may need to
6523 make some files in the binary package be owned by this
6524 user or group, or you may need to compile the user or
6525 group id (rather than just the name) into the binary
6526 (though this latter should be avoided if possible, as in
6527 this case you need a statically allocated id).</p>
6530 If you need a statically allocated id, you must ask for a
6531 user or group id from the <tt>base-passwd</tt> maintainer,
6532 and must not release the package until you have been
6533 allocated one. Once you have been allocated one you must
6534 either make the package depend on a version of the
6535 <tt>base-passwd</tt> package with the id present in
6536 <file>/etc/passwd</file> or <file>/etc/group</file>, or arrange for
6537 your package to create the user or group itself with the
6538 correct id (using <tt>adduser</tt>) in its
6539 <prgn>preinst</prgn> or <prgn>postinst</prgn>. (Doing it in
6540 the <prgn>postinst</prgn> is to be preferred if it is
6541 possible, otherwise a pre-dependency will be needed on the
6542 <tt>adduser</tt> package.)
6546 On the other hand, the program might be able to determine
6547 the uid or gid from the user or group name at runtime, so
6548 that a dynamically allocated id can be used. In this case
6549 you should choose an appropriate user or group name,
6550 discussing this on <prgn>debian-devel</prgn> and checking
6551 with the <package/base-passwd/ maintainer that it is unique and that
6552 they do not wish you to use a statically allocated id
6553 instead. When this has been checked you must arrange for
6554 your package to create the user or group if necessary using
6555 <prgn>adduser</prgn> in the <prgn>preinst</prgn> or
6556 <prgn>postinst</prgn> script (again, the latter is to be
6557 preferred if it is possible).
6561 Note that changing the numeric value of an id associated
6562 with a name is very difficult, and involves searching the
6563 file system for all appropriate files. You need to think
6564 carefully whether a static or dynamic id is required, since
6565 changing your mind later will cause problems.
6568 <sect1><heading>The use of <prgn>dpkg-statoverride</prgn></heading>
6570 This section is not intended as policy, but as a
6571 description of the use of <prgn>dpkg-statoverride</prgn>.
6575 <prgn>dpkg-statoverride</prgn> is a replacement for the
6576 deprecated <tt>suidmanager</tt> package. Packages which
6577 previously used <tt>suidmanager</tt> should have a
6578 <tt>Conflicts: suidmanager (<< 0.50)</tt> entry (or even
6579 <tt>(<< 0.52)</tt>), and calls to <tt>suidregister</tt>
6580 and <tt>suidunregister</tt> should now be simply removed
6581 from the maintainer scripts.
6585 If a system administrator wishes to have a file (or
6586 directory or other such thing) installed with owner and
6587 permissions different from those in the distributed Debian
6588 package, he can use the <prgn>dpkg-statoverride</prgn>
6589 program to instruct <prgn>dpkg</prgn> to use the different
6590 settings every time the file is installed. Thus the
6591 package maintainer should distribute the files with their
6592 normal permissions, and leave it for the system
6593 administrator to make any desired changes. For example, a
6594 daemon which is normally required to be setuid root, but
6595 in certain situations could be used without being setuid,
6596 should be installed setuid in the <tt>.deb</tt>. Then the
6597 local system administrator can change this if they wish.
6598 If there are two standard ways of doing it, the package
6599 maintainer can use <tt>debconf</tt> to find out the
6600 preference, and call <prgn>dpkg-statoverride</prgn> in the
6601 maintainer script if necessary to accommodate the system
6602 administrator's choice.
6606 Given the above, <prgn>dpkg-statoverride</prgn> is
6607 essentially a tool for system administrators and would not
6608 normally be needed in the maintainer scripts. There is
6609 one type of situation, though, where calls to
6610 <prgn>dpkg-statoverride</prgn> would be needed in the
6611 maintainer scripts, and that involves packages which use
6612 dynamically allocated user or group ids. In such a
6613 situation, something like the following idiom can be very
6614 helpful in the package's <prgn>postinst</prgn>, where
6615 <tt>sysuser</tt> is a dynamically allocated id:
6617 for i in /usr/bin/foo /usr/sbin/bar
6619 if ! dpkg-statoverride --list $i >/dev/null
6621 dpkg-statoverride --update --add sysuser root 4755 $i
6625 The corresponding <tt>dpkg-statoverride --remove</tt>
6626 calls can then be made unconditionally when the package is
6633 <chapt id="customized-programs">
6634 <heading>Customized programs</heading>
6636 <sect id="arch-spec">
6637 <heading>Architecture specification strings</heading>
6640 If a program needs to specify an <em>architecture specification
6641 string</em> in some place, the following format should be
6642 used: <var>arch</var>-<var>os</var><footnote>
6644 The following architectures and operating systems are
6645 currently recognised by <prgn>dpkg-archictecture</prgn>.
6646 The architecture, <tt><var>arch</var></tt>, is one of
6647 the following: <tt>alpha</tt>, <tt>arm</tt>,
6648 <tt>hppa</tt>, <tt>i386</tt>, <tt>ia64</tt>,
6649 <tt>m68k</tt>, <tt>mips</tt>, <tt>mipsel</tt>,
6650 <tt>powerpc</tt>, <tt>s390</tt>, <tt>sh</tt>,
6651 <tt>sheb</tt>, <tt>sparc</tt> and <tt>sparc64</tt>. The
6652 operating system, <tt><var>os</var></tt>, is one of:
6653 <tt>linux</tt>, <tt>gnu</tt>, <tt>freebsd</tt> and
6654 <tt>openbsd</tt>. Use of <tt>gnu</tt> in this string is
6655 reserved for the GNU/Hurd operating system.
6661 Note that we don't want to use
6662 <tt><var>arch</var>-debian-linux</tt> to apply to the rule
6663 <tt><var>architecture</var>-<var>vendor</var>-<var>os</var></tt>
6664 since this would make our programs incompatible with other
6665 Linux distributions. We also don't use something like
6666 <tt><var>arch</var>-unknown-linux</tt>, since the
6667 <tt>unknown</tt> does not look very good.
6672 <heading>Daemons</heading>
6675 The configuration files <file>/etc/services</file>,
6676 <file>/etc/protocols</file>, and <file>/etc/rpc</file> are managed
6677 by the <prgn>netbase</prgn> package and must not be modified
6682 If a package requires a new entry in one of these files, the
6683 maintainer should get in contact with the
6684 <prgn>netbase</prgn> maintainer, who will add the entries
6685 and release a new version of the <prgn>netbase</prgn>
6690 The configuration file <file>/etc/inetd.conf</file> must not be
6691 modified by the package's scripts except via the
6692 <prgn>update-inetd</prgn> script or the
6693 <file>DebianNet.pm</file> Perl module. See their documentation
6694 for details on how to add entries.
6698 If a package wants to install an example entry into
6699 <file>/etc/inetd.conf</file>, the entry must be preceded with
6700 exactly one hash character (<tt>#</tt>). Such lines are
6701 treated as "commented out by user" by the
6702 <prgn>update-inetd</prgn> script and are not changed or
6703 activated during package updates.
6708 <heading>Using pseudo-ttys and modifying wtmp, utmp and
6712 Some programs need to create pseudo-ttys. This should be done
6713 using Unix98 ptys if the C library supports it. The resulting
6714 program must not be installed setuid root, unless that
6715 is required for other functionality.
6719 The files <file>/var/run/utmp</file>, <file>/var/log/wtmp</file> and
6720 <file>/var/log/lastlog</file> must be installed writeable by
6721 group <tt>utmp</tt>. Programs which need to modify those
6722 files must be installed setgid <tt>utmp</tt>.
6727 <heading>Editors and pagers</heading>
6730 Some programs have the ability to launch an editor or pager
6731 program to edit or display a text document. Since there are
6732 lots of different editors and pagers available in the Debian
6733 distribution, the system administrator and each user should
6734 have the possibility to choose his/her preferred editor and
6739 In addition, every program should choose a good default
6740 editor/pager if none is selected by the user or system
6745 Thus, every program that launches an editor or pager must
6746 use the EDITOR or PAGER environment variable to determine
6747 the editor or pager the user wishes to use. If these
6748 variables are not set, the programs <file>/usr/bin/editor</file>
6749 and <file>/usr/bin/pager</file> should be used, respectively.
6753 These two files are managed through the <prgn>dpkg</prgn>
6754 "alternatives" mechanism. Thus every package providing an
6755 editor or pager must call the
6756 <prgn>update-alternatives</prgn> script to register these
6761 If it is very hard to adapt a program to make use of the
6762 EDITOR or PAGER variables, that program may be configured to
6763 use <file>/usr/bin/sensible-editor</file> and
6764 <file>/usr/bin/sensible-pager</file> as the editor or pager
6765 program respectively. These are two scripts provided in the
6766 Debian base system that check the EDITOR and PAGER variables
6767 and launch the appropriate program, and fall back to
6768 <file>/usr/bin/editor</file> and <file>/usr/bin/pager</file> if the
6769 variable is not set.
6773 A program may also use the VISUAL environment variable to
6774 determine the user's choice of editor. If it exists, it
6775 should take precedence over EDITOR. This is in fact what
6776 <file>/usr/bin/sensible-editor</file> does.
6780 It is not required for a package to depend on
6781 <tt>editor</tt> and <tt>pager</tt>, nor is it required for a
6782 package to provide such virtual packages.<footnote>
6784 The Debian base system already provides an editor and a
6791 <sect id="web-appl">
6792 <heading>Web servers and applications</heading>
6795 This section describes the locations and URLs that should
6796 be used by all web servers and web applications in the
6804 Cgi-bin executable files are installed in the
6806 <example compact="compact">
6807 /usr/lib/cgi-bin/<var>cgi-bin-name</var>
6809 and should be referred to as
6810 <example compact="compact">
6811 http://localhost/cgi-bin/<var>cgi-bin-name</var>
6816 <item><p>Access to HTML documents</p>
6819 HTML documents for a package are stored in
6820 <file>/usr/share/doc/<var>package</var></file>
6821 and can be referred to as
6822 <example compact="compact">
6823 http://localhost/doc/<var>package</var>/<var>filename</var>
6827 The web server should restrict access to the document
6828 tree so that only clients on the same host can read
6829 the documents. If the web server does not support such
6830 access controls, then it should not provide access at
6831 all, or ask about providing access during installation.
6835 <item><p>Web Document Root</p>
6838 Web Applications should try to avoid storing files in
6839 the Web Document Root. Instead they should use the
6840 /usr/share/doc/<var>package</var> directory for
6841 documents and register the Web Application via the
6842 menu package. If access to the web document root is
6843 unavoidable then use
6844 <example compact="compact">
6847 as the Document Root. This might be just a symbolic
6848 link to the location where the system administrator
6849 has put the real document root.
6853 </enumlist></p></sect>
6856 <sect id="mail-transport-agents">
6857 <heading>Mail transport, delivery and user agents</heading>
6860 Debian packages which process electronic mail, whether mail
6861 user agents (MUAs) or mail transport agents (MTAs), must
6862 ensure that they are compatible with the configuration
6863 decisions below. Failure to do this may result in lost
6864 mail, broken <tt>From:</tt> lines, and other serious brain
6869 The mail spool is <file>/var/mail</file> and the interface to
6870 send a mail message is <file>/usr/sbin/sendmail</file> (as per
6871 the FHS). On older systems, the mail spool may be
6872 physically located in <file>/var/spool/mail</file>, but all
6873 access to the mail spool should be via the
6874 <file>/var/mail</file> symlink. The mail spool is part of the
6875 base system and not part of the MTA package.
6879 All Debian MUAs, MTAs, MDAs and other mailbox accessing
6880 programs (such as IMAP daemons) must lock the mailbox in an
6881 NFS-safe way. This means that <tt>fcntl()</tt> locking must
6882 be combined with dot locking. To avoid deadlocks, a program
6883 should use <tt>fcntl()</tt> first and dot locking after
6884 this, or alternatively implement the two locking methods in
6885 a non blocking way<footnote>
6887 If it is not possible to establish both locks, the
6888 system shouldn't wait for the second lock to be
6889 established, but remove the first lock, wait a (random)
6890 time, and start over locking again.
6892 </footnote>. Using the functions <tt>maillock</tt> and
6893 <tt>mailunlock</tt> provided by the
6894 <tt>liblockfile*</tt><footnote>
6896 You will need to depend on <tt>liblockfile1
6897 (>>1.01)</tt> to use these functions.
6899 </footnote> packages is the recommended way to realize this.
6903 Mailboxes are generally mode 660
6904 <tt><var>user</var>.mail</tt> unless the system
6905 administrator has chosen otherwise. A MUA may remove a
6906 mailbox (unless it has nonstandard permissions) in which
6907 case the MTA or another MUA must recreate it if needed.
6908 Mailboxes must be writable by group mail.
6912 The mail spool is 2775 <tt>root.mail</tt>, and MUAs should
6913 be setgid mail to do the locking mentioned above (and
6914 must obviously avoid accessing other users' mailboxes
6915 using this privilege).</p>
6918 <file>/etc/aliases</file> is the source file for the system mail
6919 aliases (e.g., postmaster, usenet, etc.), it is the one
6920 which the sysadmin and <prgn>postinst</prgn> scripts may
6921 edit. After <file>/etc/aliases</file> is edited the program or
6922 human editing it must call <prgn>newaliases</prgn>. All MTA
6923 packages must come with a <prgn>newaliases</prgn> program,
6924 even if it does nothing, but older MTA packages did not do
6925 this so programs should not fail if <prgn>newaliases</prgn>
6926 cannot be found. Note that because of this, all MTA
6927 packages must have <tt>Provides</tt>, <tt>Conflicts</tt> and
6928 <tt>Replaces: mail-transport-agent</tt> control file
6933 The convention of writing <tt>forward to
6934 <var>address</var></tt> in the mailbox itself is not
6935 supported. Use a <tt>.forward</tt> file instead.</p>
6938 The <prgn>rmail</prgn> program used by UUCP
6939 for incoming mail should be <file>/usr/sbin/rmail</file>.
6940 Likewise, <prgn>rsmtp</prgn>, for receiving
6941 batch-SMTP-over-UUCP, should be <file>/usr/sbin/rsmtp</file> if it
6945 If your package needs to know what hostname to use on (for
6946 example) outgoing news and mail messages which are generated
6947 locally, you should use the file <file>/etc/mailname</file>. It
6948 will contain the portion after the username and <tt>@</tt>
6949 (at) sign for email addresses of users on the machine
6950 (followed by a newline).
6954 Such package should check for the existence of this file
6955 when it is being configured. If it exists, it should be
6956 used without comment, although an MTA's configuration script
6957 may wish to prompt the user even if it finds that this file
6958 exists. If the file does not exist, the package should
6959 prompt the user for the value (preferably using
6960 <prgn>debconf</prgn>) and store it in <file>/etc/mailname</file>
6961 as well as using it in the package's configuration. The
6962 prompt should make it clear that the name will not just be
6963 used by that package. For example, in this situation the
6964 <tt>inn</tt> package could say something like:
6965 <example compact="compact">
6966 Please enter the "mail name" of your system. This is the
6967 hostname portion of the address to be shown on outgoing
6968 news and mail messages. The default is
6969 <var>syshostname</var>, your system's host name. Mail
6970 name ["<var>syshostname</var>"]:
6972 where <var>syshostname</var> is the output of <tt>hostname
6978 <heading>News system configuration</heading>
6981 All the configuration files related to the NNTP (news)
6982 servers and clients should be located under
6983 <file>/etc/news</file>.</p>
6986 There are some configuration issues that apply to a number
6987 of news clients and server packages on the machine. These
6991 <tag><file>/etc/news/organization</file></tag>
6992 <item><p>A string which should appear as the
6993 organization header for all messages posted
6994 by NNTP clients on the machine</p></item>
6996 <tag><file>/etc/news/server</file></tag>
6997 <item><p>Contains the FQDN of the upstream NNTP
6998 server, or localhost if the local machine is
6999 an NNTP server.</p></item>
7002 Other global files may be added as required for cross-package news
7003 configuration.</p></sect>
7007 <heading>Programs for the X Window System</heading>
7010 <heading>Providing X support and package priorities</heading>
7013 Programs that can be configured with support for the X
7014 Window System must be configured to do so and must declare
7015 any package dependencies necessary to satisfy their
7016 runtime requirements when using the X Window System. If
7017 such a package is of higher priority than the X packages
7018 on which it depends, it is required that either the
7019 X-specific components be split into a separate package, or
7020 that an alternative version of the package, which includes
7021 X support, be provided, or that the package's priority be
7027 <heading>Packages providing an X server</heading>
7030 Packages that provide an X server that, directly or
7031 indirectly, communicates with real input and display
7032 hardware should declare in their control data that they
7033 provide the virtual package <tt>xserver</tt>.<footnote>
7035 This implements current practice, and provides an
7036 actual policy for usage of the <tt>xserver</tt>
7037 virtual package which appears in the virtual packages
7038 list. In a nutshell, X servers that interface
7039 directly with the display and input hardware or via
7040 another subsystem (e.g., GGI) should provide
7041 <tt>xserver</tt>. Things like <tt>Xvfb</tt>,
7042 <tt>Xnest</tt>, and <tt>Xprt</tt> should not.
7049 <heading>Packages providing a terminal emulator</heading>
7052 Packages that provide a terminal emulator for the X Window
7053 System which meet the criteria listed below should declare
7054 in their control data that they provide the virtual
7055 package <tt>x-terminal-emulator</tt>. They should also
7056 register themselves as an alternative for
7057 <file>/usr/bin/x-terminal-emulator</file>, with a priority of
7062 To be an <tt>x-terminal-emulator</tt>, a program must:
7063 <list compact="compact">
7065 Be able to emulate a DEC VT100 terminal, or a
7066 compatible terminal.
7070 Support the command-line option <tt>-e
7071 <var>command</var></tt>, which creates a new
7072 terminal window<footnote>
7074 "New terminal window" does not necessarily mean
7075 a new top-level X window directly parented by
7076 the window manager; it could, if the terminal
7077 emulator application were so coded, be a new
7078 "view" in a multiple-document interface (MDI).
7081 and runs the specified <var>command</var>,
7082 interpreting the entirity of the rest of the command
7083 line as a command to pass straight to exec, in the
7084 manner that <tt>xterm</tt> does.
7088 Support the command-line option <tt>-T
7089 <var>title</var></tt>, which creates a new terminal
7090 window with the window title <var>title</var>.
7097 <heading>Packages providing a window manager</heading>
7100 Packages that provide a window manager should declare in
7101 their control data that they provide the virtual package
7102 <tt>x-window-manager</tt>. They should also register
7103 themselves as an alternative for
7104 <file>/usr/bin/x-window-manager</file>, with a priority
7105 calculated as follows:
7106 <list compact="compact">
7107 <item><p>Start with a priority of 20.</p></item>
7111 If the window manager supports the Debian menu
7112 system, add 20 points if this support is available
7113 in the package's default configuration (i.e., no
7114 configuration files belonging to the system or user
7115 have to be edited to activate the feature); if
7116 configuration files must be modified, add only 10
7122 If the window manager complies with <url
7123 id="http://www.freedesktop.org/standards/wm-spec.html"
7124 name="The Window Manager Specification Project">,
7125 written by the <url id="http://www.freedesktop.org"
7126 name="Free Desktop Group">, add 40 points.
7132 If the window manager permits the X session to be
7133 restarted using a <em>different</em> window manager
7134 (without killing the X server) in its default
7135 configuration, add 10 points; otherwise add none.
7143 <heading>Packages providing fonts</heading>
7146 Packages that provide fonts for the X Window
7149 For the purposes of Debian Policy, a "font for the X
7150 Window System" is one which is accessed via X protocol
7151 requests. Fonts for the Linux console, for PostScript
7152 renderers, or any other purpose, do not fit this
7153 definition. Any tool which makes such fonts available
7154 to the X Window System, however, must abide by this
7158 must do a number of things to ensure that they are both
7159 available without modification of the X or font server
7160 configuration, and that they do not corrupt files used by
7161 other font packages to register information about
7166 Fonts of any type supported by the X Window System
7167 must be in a separate binary package from any
7168 executables, libraries, or documentation (except
7169 that specific to the fonts shipped, such as their
7170 license information). If one or more of the fonts
7171 so packaged are necessary for proper operation of
7172 the package with which they are associated the font
7173 package may be Recommended; if the fonts merely
7174 provide an enhancement, a Suggests relationship may
7175 be used. Packages must not Depend on font
7178 This is because the X server may retrieve fonts
7179 from the local filesystem or over the network
7180 from an X font server; the Debian package system
7181 is empowered to deal only with the local
7190 BDF fonts must be converted to PCF fonts with the
7191 <prgn>bdftopcf</prgn> utility (available in the
7192 <tt>xutils</tt> package, <prgn>gzip</prgn>ped, and
7193 placed in a directory that corresponds to their
7195 <list compact="compact">
7197 100 dpi fonts must be placed in
7198 <file>/usr/X11R6/lib/X11/fonts/100dpi/</file>.
7202 75 dpi fonts must be placed in
7203 <file>/usr/X11R6/lib/X11/fonts/75dpi/</file>.
7207 Character-cell fonts, cursor fonts, and other
7208 low-resolution fonts must be placed in
7209 <file>/usr/X11R6/lib/X11/fonts/misc/</file>.
7216 Speedo fonts must be placed in
7217 <file>/usr/X11R6/lib/X11/fonts/Speedo/</file>.
7221 Type 1 fonts must be placed in
7222 <file>/usr/X11R6/lib/X11/fonts/Type1/</file>. If font
7223 metric files are available, they must be placed here
7229 Subdirectories of <file>/usr/X11R6/lib/X11/fonts/</file>
7230 other than those listed above must be neither
7231 created nor used. (The <file>PEX</file>, <file>CID</file>,
7232 and <file>cyrillic</file> directories are excepted for
7233 historical reasons, but installation of files into
7234 these directories remains discouraged.)
7240 Font packages may, instead of placing files directly
7241 in the X font directories listed above, provide
7242 symbolic links in that font directory pointing to
7243 the files' actual location in the filesystem. Such
7244 a location must comply with the FHS.
7250 Font packages should not contain both 75dpi and
7251 100dpi versions of a font. If both are available,
7252 they should be provided in separate binary packages
7253 with <tt>-75dpi</tt> or <tt>-100dpi</tt> appended to
7254 the names of the packages containing the
7255 corresponding fonts.
7261 Fonts destined for the <file>misc</file> subdirectory
7262 should not be included in the same package as 75dpi
7263 or 100dpi fonts; instead, they should be provided in
7264 a separate package with <tt>-misc</tt> appended to
7271 Font packages must not provide the files
7272 <file>fonts.dir</file>, <file>fonts.alias</file>, or
7273 <file>fonts.scale</file> in a font directory:
7276 <file>fonts.dir</file> files must not be provided at all.
7281 <file>fonts.alias</file> and <file>fonts.scale</file>
7282 files, if needed, should be provided in the
7284 <file>/etc/X11/fonts/<var>fontdir</var>/<var>package</var>.<var>extension</var></file>,
7285 where <var>fontdir</var> is the name of the
7287 <file>/usr/X11R6/lib/X11/fonts/</file> where the
7288 package's corresponding fonts are stored
7289 (e.g., <tt>75dpi</tt> or <tt>misc</tt>),
7290 <var>package</var> is the name of the package
7291 that provides these fonts, and
7292 <var>extension</var> is either <tt>scale</tt>
7293 or <tt>alias</tt>, whichever corresponds to
7303 Font packages must declare a dependency on
7304 <tt>xutils (>> 4.0.3)</tt> in their control
7311 Font packages that provide one or more
7312 <file>fonts.scale</file> files as described above must
7313 invoke <prgn>update-fonts-scale</prgn> on each
7314 directory into which they installed fonts
7315 <em>before</em> invoking
7316 <prgn>update-fonts-dir</prgn> on that directory.
7317 This invocation must occur in both the
7318 <prgn>postinst</prgn> (for all arguments) and
7319 <prgn>postrm</prgn> (for all arguments except
7320 <tt>upgrade</tt>) scripts.
7326 Font packages that provide one or more
7327 <file>fonts.alias</file> files as described above must
7328 invoke <prgn>update-fonts-alias</prgn> on each
7329 directory into which they installed fonts. This
7330 invocation must occur in both the
7331 <prgn>postinst</prgn> (for all arguments) and
7332 <prgn>postrm</prgn> (for all arguments except
7333 <tt>upgrade</tt>) scripts.
7339 Font packages must invoke
7340 <prgn>update-fonts-dir</prgn> on each directory into
7341 which they installed fonts. This invocation must
7342 occur in both the <prgn>postinst</prgn> (for all
7343 arguments) and <prgn>postrm</prgn> (for all
7344 arguments except <tt>upgrade</tt>) scripts.
7350 Font packages must not provide alias names for the
7351 fonts they include which collide with alias names
7352 already in use by fonts already packaged.
7358 Font packages must not provide fonts with the same
7359 XLFD registry name as another font already packaged.
7367 <heading>Application defaults files</heading>
7370 Application defaults files must be installed in the
7371 directory <file>/etc/X11/app-defaults/</file> (use of a
7372 localized subdirectory of <file>/etc/X11/</file> as described
7373 in the <em>X Toolkit Intrinsics - C Language
7374 Interface</em> manual is also permitted). They must be
7375 registered as <tt>conffile</tt>s or handled as
7376 configuration files. Packages must not provide the
7377 directory <file>/usr/X11R6/lib/X11/app-defaults/</file>.
7381 Customization of programs' X resources may also be
7382 supported with the provision of a file with the same name
7383 as that of the package placed in the
7384 <file>/etc/X11/Xresources/</file> directory, which must
7385 registered as a <tt>conffile</tt> or handled as a
7386 configuration file.<footnote>
7388 Note that this mechanism is not the same as using
7389 app-defaults; app-defaults are tied to the client
7390 binary on the local filesystem, whereas X resources
7391 are stored in the X server and affect all connecting
7395 <em>Important:</em> packages that install files into the
7396 <file>/etc/X11/Xresources/</file> directory must conflict with
7397 <tt>xbase (<< 3.3.2.3a-2)</tt>; if this is not done
7398 it is possible for the installing package to destroy a
7399 previously-existing <file>/etc/X11/Xresources</file> file
7400 which had been customized by the system administrator.
7405 <heading>Installation directory issues</heading>
7408 Packages using the X Window System should not be
7409 configured to install files under the <file>/usr/X11R6/</file>
7410 directory unless they use <prgn>imake</prgn>. The
7411 <file>/usr/X11R6/</file> directory hierarchy should be
7412 regarded as deprecated for all packages except the X
7413 Window System itself, and those which use the
7414 <prgn>imake</prgn> program it provides, in which case the
7415 packages may transition out of the <file>/usr/X11R6/</file>
7416 directory at the maintainer's discretion.<footnote>
7418 <prgn>Imake</prgn>-using programs are exempt because,
7419 as long as they are written correctly, the pathnames
7420 they use to locate resources and install themselves
7421 are derived wholly from the X Window System
7422 configuration. Thus, in the event that the X Window
7423 System moves to <file>/usr/X11R7/</file>,
7424 <file>/usr/X12/</file>, or just plain <file>/usr/</file>, all
7425 that is required for these programs is a recompile
7426 against the corresponding X Window System library
7427 development packages.
7430 Programs that use GNU <prgn>autoconf</prgn> and
7431 <prgn>automake</prgn> are usually easily configured at
7432 compile time to use <file>/usr/</file> instead of
7433 <file>/usr/X11R6/</file>, and this should be done whenever
7434 possible. Configuration files for window managers and
7435 display managers should be placed in a subdirectory of
7436 <file>/etc/X11/</file> corresponding to the package name due
7437 to these programs' tight integration with the mechanisms
7438 of the X Window System. Application-level programs should
7439 use the <file>/etc/</file> directory unless otherwise mandated
7440 by policy. The installation of files into subdirectories
7441 of <file>/usr/X11R6/include/X11/</file> and
7442 <file>/usr/X11R6/lib/X11/</file> is permitted but discouraged;
7443 package maintainers should determine if subdirectories of
7444 <file>/usr/lib/</file> and <file>/usr/share/</file> can be used
7445 instead. (The use of symbolic links from the
7446 <file>X11R6</file> directories to other FHS-compliant
7447 locations is encouraged if the program is not easily
7448 configured to look elsewhere for its files.) Packages
7449 must not provide or install files into the directories
7450 <file>/usr/bin/X11/</file>, <file>/usr/include/X11/</file> or
7451 <file>/usr/lib/X11/</file>. Files within a package should,
7452 however, make reference to these directories, rather than
7453 their <tt>X11R6</tt>-named counterparts
7454 <file>/usr/X11R6/bin/</file>, <file>/usr/X11R6/include/X11/</file>
7455 and <file>/usr/X11R6/lib/X11/</file>, if the resources being
7456 referred to have not been moved to other FHS-compliant
7462 <heading>The OSF/Motif and OpenMotif libraries</heading>
7465 <em>Programs that require the non-DFSG-compliant OSF/Motif or
7466 OpenMotif libraries</em><footnote>
7468 OSF/Motif and OpenMotif are collectively referred to as
7469 "Motif" in this policy document.
7472 should be compiled against and tested with LessTif (a free
7473 re-implementation of Motif) instead. If the maintainer
7474 judges that the program or programs do not work
7475 sufficiently well with LessTif to be distributed and
7476 supported, but do so when compiled against Motif, then two
7477 versions of the package should be created; one linked
7478 statically against Motif and with <tt>-smotif</tt>
7479 appended to the package name, and one linked dynamically
7480 against Motif and with <tt>-dmotif</tt> appended to the
7481 package name. Both Motif-linked versions are dependent
7482 upon non-DFSG-compliant software and thus cannot be
7483 uploaded to the <em>main</em> distribution; if the
7484 software is itself DFSG-compliant it may be uploaded to
7485 the <em>contrib</em> distribution. While known existing
7486 versions of Motif permit unlimited redistribution of
7487 binaries linked against the library (whether statically or
7488 dynamically), it is the package maintainer's
7489 responsibility to determine whether this is permitted by
7490 the license of the copy of Motif in his or her possession.
7496 <heading>Perl programs and modules</heading>
7499 Perl programs and modules should follow the current Perl policy.
7503 The Perl policy can be found in the <tt>perl-policy</tt>
7504 files in the <tt>debian-policy</tt> package.
7505 They are also available from the Debian web mirrors at
7506 <tt><url name="/doc/packaging-manuals/perl-policy/"
7507 id="http://www.debian.org/doc/packaging-manuals/perl-policy/"></tt>
7508 and from the Debian archive mirrors at
7509 <tt><url name="/doc/package-developer/perl-policy.txt.gz"
7510 id="http://ftp.debian.org/debian/doc/package-developer/perl-policy.txt.gz"></tt>.
7515 <heading>Emacs lisp programs</heading>
7518 Please refer to the "Debian Emacs Policy" for details of how to
7519 package emacs lisp programs.
7523 The Emacs policy is available in
7524 <file>debian-emacs-policy.gz</file> of the
7525 <package>emacsen-common</package> package.
7526 It is also available from the Debian web mirrors at
7527 <tt><url name="/doc/packaging-manuals/debian-emacs-policy"
7528 id="http://www.debian.org/doc/packaging-manuals/debian-emacs-policy"></tt>.
7533 <heading>Games</heading>
7536 The permissions on <file>/var/games</file> are mode 755, owner
7537 <tt>root</tt> and group <tt>root</tt>.
7541 Each game decides on its own security policy.</p>
7544 Games which require protected, privileged access to
7545 high-score files, savegames, etc., may be made
7546 set-<em>group</em>-id (mode 2755) and owned by
7547 <tt>root.games</tt>, and use files and directories with
7548 appropriate permissions (770 <tt>root.games</tt>, for
7549 example). They must not be made
7550 set-<em>user</em>-id, as this causes security problems. (If
7551 an attacker can subvert any set-user-id game they can
7552 overwrite the executable of any other, causing other players
7553 of these games to run a Trojan horse program. With a
7554 set-group-id game the attacker only gets access to less
7555 important game data, and if they can get at the other
7556 players' accounts at all it will take considerably more
7560 Some packages, for example some fortune cookie programs, are
7561 configured by the upstream authors to install with their
7562 data files or other static information made unreadable so
7563 that they can only be accessed through set-id programs
7564 provided. You should not do this in a Debian package: anyone can
7565 download the <file>.deb</file> file and read the data from it,
7566 so there is no point making the files unreadable. Not
7567 making the files unreadable also means that you don't have
7568 to make so many programs set-id, which reduces the risk of a
7572 As described in the FHS, binaries of games should be
7573 installed in the directory <file>/usr/games</file>. This also
7574 applies to games that use the X Window System. Manual pages
7575 for games (X and non-X games) should be installed in
7576 <file>/usr/share/man/man6</file>.</p>
7580 <chapt id="docs"><heading>Documentation</heading>
7584 <heading>Manual pages</heading>
7587 You should install manual pages in <prgn>nroff</prgn> source
7588 form, in appropriate places under <file>/usr/share/man</file>.
7589 You should only use sections 1 to 9 (see the FHS for more
7590 details). You must not install a preformatted "cat page".
7594 Each program, utility, and function should have an
7595 associated manual page included in the same package. It is
7596 suggested that all configuration files also have a manual
7597 page included as well. Manual pages for protocols and other
7598 auxiliary things are optional.
7602 If no manual page is available, this is considered as a bug
7603 and should be reported to the Debian Bug Tracking System (the
7604 maintainer of the package is allowed to write this bug report
7605 themselves, if they so desire). Do not close the bug report
7606 until a proper manpage is available.<footnote>
7608 It is not very hard to write a man page. See the
7609 <url id="http://www.schweikhardt.net/man_page_howto.html"
7610 name="Man-Page-HOWTO">,
7611 <manref name="man" section="7">, the examples
7612 created by <prgn>debmake</prgn> or <prgn>dh_make</prgn>,
7613 the helper programs <prgn>help2man</prgn>, or the
7614 directory <file>/usr/share/doc/man-db/examples</file>.
7620 You may forward a complaint about a missing manpage to the
7621 upstream authors, and mark the bug as forwarded in the
7622 Debian bug tracking system. Even though the GNU Project do
7623 not in general consider the lack of a manpage to be a bug,
7624 we do; if they tell you that they don't consider it a bug
7625 you should leave the bug in our bug tracking system open
7630 Manual pages should be installed compressed using <tt>gzip -9</tt>.
7634 If one manpage needs to be accessible via several names it
7635 is better to use a symbolic link than the <file>.so</file>
7636 feature, but there is no need to fiddle with the relevant
7637 parts of the upstream source to change from <file>.so</file> to
7638 symlinks: don't do it unless it's easy. You should not
7639 create hard links in the manual page directories, nor put
7640 absolute filenames in <file>.so</file> directives. The filename
7641 in a <file>.so</file> in a manpage should be relative to the
7642 base of the manpage tree (usually
7643 <file>/usr/share/man</file>). If you do not create any links
7644 (whether symlinks, hard links, or <tt>.so</tt> directives)
7645 in the filesystem to the alternate names of the manpage,
7646 then you should not rely on <prgn>man</prgn> finding your
7647 manpage under those names based solely on the information in
7648 the manpage's header.<footnote>
7650 Supporting this in <prgn>man</prgn> often requires
7651 unreasonable processing time to find a manual page or to
7652 report that none exists, and moves knowledge into man's
7653 database that would be better left in the filesystem.
7654 This support is therefore deprecated and will cease to
7655 be present in the future.
7662 <heading>Info documents</heading>
7665 Info documents should be installed in <file>/usr/share/info</file>.
7666 They should be compressed with <tt>gzip -9</tt>.
7670 Your package should call <prgn>install-info</prgn> to update
7671 the Info <file>dir</file> file in its <prgn>postinst</prgn>
7672 script when called with a <tt>configure</tt> argument, for
7674 <example compact="compact">
7675 install-info --quiet --section Development Development \
7676 /usr/share/info/foobar.info
7680 It is a good idea to specify a section for the location of
7681 your program; this is done with the <tt>--section</tt>
7682 switch. To determine which section to use, you should look
7683 at <file>/usr/share/info/dir</file> on your system and choose the most
7684 relevant (or create a new section if none of the current
7685 sections are relevant). Note that the <tt>--section</tt>
7686 flag takes two arguments; the first is a regular expression
7687 to match (case-insensitively) against an existing section,
7688 the second is used when creating a new one.</p>
7691 You should remove the entries in the <prgn>prerm</prgn>
7692 script when called with a <tt>remove</tt> argument:
7693 <example compact="compact">
7694 install-info --quiet --remove /usr/share/info/foobar.info
7698 If <prgn>install-info</prgn> cannot find a description entry
7699 in the Info file you must supply one. See <manref
7700 name="install-info" section="8"> for details.</p>
7704 <heading>Additional documentation</heading>
7707 Any additional documentation that comes with the package may
7708 be installed at the discretion of the package maintainer.
7709 Text documentation should be installed in the directory
7710 <file>/usr/share/doc/<var>package</var></file>, where
7711 <var>package</var> is the name of the package, and
7712 compressed with <tt>gzip -9</tt> unless it is small.
7716 If a package comes with large amounts of documentation which
7717 many users of the package will not require you should create
7718 a separate binary package to contain it, so that it does not
7719 take up disk space on the machines of users who do not need
7720 or want it installed.</p>
7723 It is often a good idea to put text information files
7724 (<file>README</file>s, changelogs, and so forth) that come with
7725 the source package in <file>/usr/share/doc/<var>package</var></file>
7726 in the binary package. However, you don't need to install
7727 the instructions for building and installing the package, of
7731 Packages must not require the existance of any files in
7732 <file>/usr/share/doc/</file> in order to function
7735 The system administrator should be able to
7736 delete files in <file>/usr/share/doc/</file> without causing
7737 any programs to break.
7740 Any files that are referenced by programs but are also
7741 useful as standalone documentation should be installed under
7742 <file>/usr/share/<var>package</var>/</file> with symbolic links from
7743 <file>/usr/share/doc/<var>package</var></file>.
7747 <file>/usr/share/doc/<var>package</var></file> may be a symbolic
7748 link to another directory in <file>/usr/share/doc</file> only if
7749 the two packages both come from the same source and the
7750 first package Depends on the second.
7754 Former Debian releases placed all additional documentation
7755 in <file>/usr/doc/<var>package</var></file>. This has been
7756 changed to <file>/usr/share/doc/<var>package</var></file>,
7757 and packages must not put documentation in the directory
7758 <file>/usr/doc/<var>package</var></file>. <footnote>
7759 <p>At this phase of the transition, we no longer require a
7760 symbolic link in <file>/usr/doc/</file>. At a later point,
7761 policy shall change to make the symbolic links a bug.</p>
7767 <heading>Preferred documentation formats</heading>
7770 The unification of Debian documentation is being carried out
7774 If your package comes with extensive documentation in a
7775 markup format that can be converted to various other formats
7776 you should if possible ship HTML versions in a binary
7777 package, in the directory
7778 <file>/usr/share/doc/<var>appropriate-package</var></file> or
7779 its subdirectories.<footnote>
7781 The rationale: The important thing here is that HTML
7782 docs should be available in <em>some</em> package, not
7783 necessarily in the main binary package.
7789 Other formats such as PostScript may be provided at the
7790 package maintainer's discretion.
7794 <sect id="copyrightfile">
7795 <heading>Copyright information</heading>
7798 Every package must be accompanied by a verbatim copy of its
7799 copyright and distribution license in the file
7800 <file>/usr/share/doc/<var>package</var>/copyright</file>. This
7801 file must neither be compressed nor be a symbolic link.
7805 In addition, the copyright file must say where the upstream
7806 sources (if any) were obtained. It should name the original
7807 authors of the package and the Debian maintainer(s) who were
7808 involved with its creation.</p>
7811 A copy of the file which will be installed in
7812 <file>/usr/share/doc/<var>package</var>/copyright</file> should
7813 be in <file>debian/copyright</file> in the source package.
7817 <file>/usr/share/doc/<var>package</var></file> may be a symbolic
7818 link to another directory in <file>/usr/share/doc</file> only if
7819 the two packages both come from the same source and the
7820 first package Depends on the second. These rules are
7821 important because copyrights must be extractable by
7826 Packages distributed under the UCB BSD license, the Artistic
7827 license, the GNU GPL, and the GNU LGPL should refer to the
7828 files <file>/usr/share/common-licenses/BSD</file>,
7829 <file>/usr/share/common-licenses/Artistic</file>,
7830 <file>/usr/share/common-licenses/GPL</file>, and
7831 <file>/usr/share/common-licenses/LGPL</file> respectively,
7832 rather than quoting them in the copyright file.
7836 You should not use the copyright file as a general <file>README</file>
7837 file. If your package has such a file it should be
7838 installed in <file>/usr/share/doc/<var>package</var>/README</file> or
7839 <file>README.Debian</file> or some other appropriate place.</p>
7843 <heading>Examples</heading>
7846 Any examples (configurations, source files, whatever),
7847 should be installed in a directory
7848 <file>/usr/share/doc/<var>package</var>/examples</file>. These
7849 files should not be referenced by any program: they're there
7850 for the benefit of the system administrator and users as
7851 documentation only. Architecture-specific example files
7852 should be installed in a directory
7853 <file>/usr/lib/<var>package</var>/examples</file> with symbolic
7855 <file>/usr/share/doc/<var>package</var>/examples</file>, or the
7856 latter directory itself may be a symbolic link to the
7861 If the purpose of a package is to provide examples, then the
7862 example files may be installed into
7863 <file>/usr/share/doc/<var>package</var></file>.
7867 <sect id="changelogs">
7868 <heading>Changelog files</heading>
7871 The Debian changelog file (<file>debian/changelog</file>) should
7872 explain briefly what modifications were made in the Debian version
7873 of the package compared to the upstream one. Other changes and
7874 updates to the package should also be documented in this file.
7878 Mistakes in changelogs are usually best rectified by
7879 making a new changelog entry rather than "rewriting history"
7880 by editing old changelog entries.
7884 The format of the <file>debian/changelog</file> file is described
7885 in <ref id="dpkgchangelog">. In non-experimental packages you must
7886 use a format for <file>debian/changelog</file> which is supported
7887 by the most recent released version of <prgn>dpkg</prgn>.<footnote>
7889 If you wish to use an alternative format, you may do so as
7890 long as you include a parser for it in your source package.
7891 The parser must have an API compatible with that expected by
7892 <prgn>dpkg-genchanges</prgn> and <prgn>dpkg-gencontrol</prgn>.
7893 If there is general interest in the new format, you should
7894 contact the <package>dpkg</package> maintainer to have the
7895 parser script for it included in the <prgn>dpkg</prgn>
7896 package. (You will need to agree that the parser and its
7897 manpage may be distributed under the GNU GPL, just as the rest
7898 of <prgn>dpkg</prgn> is.)
7904 Packages that are not Debian-native must contain a
7905 compressed copy of the <file>debian/changelog</file> file from
7906 the Debian source tree in
7907 <file>/usr/share/doc/<var>package</var></file> with the name
7908 <file>changelog.Debian.gz</file>.
7912 If an upstream changelog is available, it should be accessible as
7913 <file>/usr/share/doc/<var>package</var>/changelog.gz</file> in
7914 plain text. If the upstream changelog is distributed in
7915 HTML, it should be made available in that form as
7916 <file>/usr/share/doc/<var>package</var>/changelog.html.gz</file>
7917 and a plain text <file>changelog.gz</file> should be generated
7918 from it using, for example, <tt>lynx -dump -nolist</tt>. If
7919 the upstream changelog files do not already conform to this
7920 naming convention, then this may be achieved either by
7921 renaming the files, or by adding a symbolic link, at the
7922 maintainer's discretion.<footnote>
7924 Rationale: People should not have to look in places for
7925 upstream changelogs merely because they are given
7926 different names or are distributed in HTML format.
7932 All of these files should be installed compressed using
7933 <tt>gzip -9</tt>, as they will become large with time even
7934 if they start out small.
7938 If the package has only one changelog which is used both as
7939 the Debian changelog and the upstream one because there is
7940 no separate upstream maintainer then that changelog should
7941 usually be installed as
7942 <file>/usr/share/doc/<var>package</var>/changelog.gz</file>; if
7943 there is a separate upstream maintainer, but no upstream
7944 changelog, then the Debian changelog should still be called
7945 <file>changelog.Debian.gz</file>.</p>
7950 <appendix id="pkg-scope">
7951 <heading>Introduction and scope of these appendices</heading>
7954 These appendices are taken essentially verbatim from the
7955 now-deprecated Packaging Manual, version 3.2.1.0. They are
7956 the chapters which are likely to be of use to package
7957 maintainers and which have not already been included in the
7958 policy document itself. Most of these sections are very likely
7959 not relevant to policy; they should be treated as
7960 documentation for the packaging system. Please note that these
7961 appendices are included for convenience, and for historical
7962 reasons: they used to be part of policy package, and they have
7963 not yet been incorporated into dpkg documentation. However,
7964 they still have value, and hence they are presented here.
7967 They have not yet been checked to ensure that they are
7968 compatible with the contents of policy, and if there are any
7969 contradictions, the version in the main policy document takes
7970 precedence. The remaining chapters of the old Packaging
7971 Manual have also not been read in detail to ensure that there
7972 are not parts which have been left out. Both of these will be
7977 <prgn>dpkg</prgn> is a suite of programs for creating binary
7978 package files and installing and removing them on Unix
7981 <prgn>dpkg</prgn> is targetted primarily at Debian
7982 GNU/Linux, but may work on or be ported to other
7989 The binary packages are designed for the management of
7990 installed executable programs (usually compiled binaries) and
7991 their associated data, though source code examples and
7992 documentation are provided as part of some packages.</p>
7995 This manual describes the technical aspects of creating Debian
7996 binary packages (<file>.deb</file> files). It documents the
7997 behaviour of the package management programs
7998 <prgn>dpkg</prgn>, <prgn>dselect</prgn> et al. and the way
7999 they interact with packages.</p>
8002 It also documents the interaction between
8003 <prgn>dselect</prgn>'s core and the access method scripts it
8004 uses to actually install the selected packages, and describes
8005 how to create a new access method.</p>
8008 This manual does not go into detail about the options and
8009 usage of the package building and installation tools. It
8010 should therefore be read in conjuction with those programs'
8015 The utility programs which are provided with <prgn>dpkg</prgn>
8016 for managing various system configuration and similar issues,
8017 such as <prgn>update-rc.d</prgn> and
8018 <prgn>install-info</prgn>, are not described in detail here -
8019 please see their manpages.
8023 It is assumed that the reader is reasonably familiar with the
8024 <prgn>dpkg</prgn> System Administrators' manual.
8025 Unfortunately this manual does not yet exist.
8029 The Debian version of the FSF's GNU hello program is provided
8030 as an example for people wishing to create Debian
8031 packages. The Debian <prgn>debmake</prgn> package is
8032 recommended as a very helpful tool in creating and maintaining
8033 Debian packages. However, while the tools and examples are
8034 helpful, they do not replace the need to read and follow the
8035 Policy and Programmer's Manual.</p>
8038 <appendix id="pkg-binarypkg"><heading>Binary packages (from old
8043 The binary package has two main sections. The first part
8044 consists of various control information files and scripts used
8045 by <prgn>dpkg</prgn> when installing and removing. See <ref
8046 id="pkg-controlarea">.
8050 The second part is an archive containing the files and
8051 directories to be installed.
8055 In the future binary packages may also contain other
8056 components, such as checksums and digital signatures. The
8057 format for the archive is described in full in the
8058 <file>deb(5)</file> manpage.
8062 <sect id="pkg-bincreating"><heading>Creating package files -
8063 <prgn>dpkg-deb</prgn>
8067 All manipulation of binary package files is done by
8068 <prgn>dpkg-deb</prgn>; it's the only program that has
8069 knowledge of the format. (<prgn>dpkg-deb</prgn> may be
8070 invoked by calling <prgn>dpkg</prgn>, as <prgn>dpkg</prgn>
8071 will spot that the options requested are appropriate to
8072 <prgn>dpkg-deb</prgn> and invoke that instead with the same
8077 In order to create a binary package you must make a
8078 directory tree which contains all the files and directories
8079 you want to have in the filesystem data part of the package.
8080 In Debian-format source packages this directory is usually
8081 <file>debian/tmp</file>, relative to the top of the package's
8086 They should have the locations (relative to the root of the
8087 directory tree you're constructing) ownerships and
8088 permissions which you want them to have on the system when
8093 With current versions of <prgn>dpkg</prgn> the uid/username
8094 and gid/groupname mappings for the users and groups being
8095 used should be the same on the system where the package is
8096 built and the one where it is installed.
8100 You need to add one special directory to the root of the
8101 miniature filesystem tree you're creating:
8102 <prgn>DEBIAN</prgn>. It should contain the control
8103 information files, notably the binary package control file
8104 (see <ref id="pkg-controlfile">).
8108 The <prgn>DEBIAN</prgn> directory will not appear in the
8109 filesystem archive of the package, and so won't be installed
8110 by <prgn>dpkg</prgn> when the package is installed.
8114 When you've prepared the package, you should invoke:
8116 dpkg --build <var>directory</var>
8121 This will build the package in
8122 <file><var>directory</var>.deb</file>. (<prgn>dpkg</prgn> knows
8123 that <tt>--build</tt> is a <prgn>dpkg-deb</prgn> option, so
8124 it invokes <prgn>dpkg-deb</prgn> with the same arguments to
8129 See the manpage <manref name="dpkg-deb" section="8"> for details of how
8130 to examine the contents of this newly-created file. You may find the
8131 output of following commands enlightening:
8133 dpkg-deb --info <var>filename</var>.deb
8134 dpkg-deb --contents <var>filename</var>.deb
8135 dpkg --contents <var>filename</var>.deb
8137 To view the copyright file for a package you could use this command:
8139 dpkg --fsys-tarfile <var>filename</var>.deb | tar xof usr/share/doc/<var>\*</var>copyright | less
8144 <sect id="pkg-controlarea">
8146 Package control information files
8150 The control information portion of a binary package is a
8151 collection of files with names known to <prgn>dpkg</prgn>.
8152 It will treat the contents of these files specially - some
8153 of them contain information used by <prgn>dpkg</prgn> when
8154 installing or removing the package; others are scripts which
8155 the package maintainer wants <prgn>dpkg</prgn> to run.
8159 It is possible to put other files in the package control
8160 area, but this is not generally a good idea (though they
8161 will largely be ignored).
8165 Here is a brief list of the control info files supported by
8166 <prgn>dpkg</prgn> and a summary of what they're used for.
8171 <tag><tt>control</tt>
8175 This is the key description file used by
8176 <prgn>dpkg</prgn>. It specifies the package's name
8177 and version, gives its description for the user,
8178 states its relationships with other packages, and so
8179 forth. See <ref id="pkg-controlfile">.
8183 It is usually generated automatically from information
8184 in the source package by the
8185 <prgn>dpkg-gencontrol</prgn> program, and with
8186 assistance from <prgn>dpkg-shlibdeps</prgn>. See <ref
8187 id="pkg-sourcetools">.</p>
8190 <tag><tt>postinst</tt>, <tt>preinst</tt>, <tt>postrm</tt>,
8196 These are exectuable files (usually scripts) which
8197 <prgn>dpkg</prgn> runs during installation, upgrade
8198 and removal of packages. They allow the package to
8199 deal with matters which are particular to that package
8200 or require more complicated processing than that
8201 provided by <prgn>dpkg</prgn>. Details of when and
8202 how they are called are in <ref
8203 id="maintainerscripts">.
8207 It is very important to make these scripts
8211 That means that if it runs successfully or fails
8212 and then you call it again it doesn't bomb out,
8213 but just ensures that everything is the way it
8216 </footnote> This is so that if an error occurs, the
8217 user interrupts <prgn>dpkg</prgn> or some other
8218 unforeseen circumstance happens you don't leave the
8219 user with a badly-broken package.
8223 The maintainer scripts are guaranteed to run with a
8224 controlling terminal and can interact with the user.
8225 If they need to prompt for passwords, do full-screen
8226 interaction or something similar you should do these
8227 things to and from <file>/dev/tty</file>, since
8228 <prgn>dpkg</prgn> will at some point redirect scripts'
8229 standard input and output so that it can log the
8230 installation process. Likewise, because these scripts
8231 may be executed with standard output redirected into a
8232 pipe for logging purposes, Perl scripts should set
8233 unbuffered output by setting <tt>$|=1</tt> so that the
8234 output is printed immediately rather than being
8239 Each script should return a zero exit status for
8240 success, or a nonzero one for failure.</p>
8243 <tag><tt>conffiles</tt>
8248 This file contains a list of configuration files which
8249 are to be handled automatically by <prgn>dpkg</prgn>
8250 (see <ref id="pkg-conffiles">). Note that not necessarily
8251 every configuration file should be listed here.</p>
8254 <tag><tt>shlibs</tt>
8259 This file contains a list of the shared libraries
8260 supplied by the package, with dependency details for
8261 each. This is used by <prgn>dpkg-shlibdeps</prgn>
8262 when it determines what dependencies are required in a
8263 package control file. The <tt>shlibs</tt> file format
8264 is described on <ref id="shlibs">.
8270 <sect id="pkg-controlfile">
8272 The main control information file: <tt>control</tt>
8275 The most important control information file used by
8276 <prgn>dpkg</prgn> when it installs a package is
8277 <tt>control</tt>. It contains all the package"s "vital
8282 The binary package control files of packages built from
8283 Debian sources are made by a special tool,
8284 <prgn>dpkg-gencontrol</prgn>, which reads
8285 <file>debian/control</file> and <file>debian/changelog</file> to
8286 find the information it needs. See <ref id="pkg-sourcepkg"> for
8291 The fields in binary package control files are:
8292 <list compact="compact">
8294 <p><qref id="pkg-f-Package"><tt>Package</tt></qref> (mandatory)</p>
8297 <p><qref id="versions"><tt>Version</tt></qref> (mandatory)</p>
8299 <item><p><qref id="pkg-f-Architecture"><tt>Architecture</tt></qref>
8303 This field should appear in all packages, though
8304 <prgn>dpkg</prgn> doesn't require it yet so that
8305 old packages can still be installed.
8311 <p><qref id="relationships"><tt>Depends</tt>,
8312 <tt>Provides</tt> et al.</qref></p>
8315 <p><qref id="pkg-f-Essential"><tt>Essential</tt></qref></p>
8318 <p><qref id="pkg-f-Maintainer"><tt>Maintainer</tt></qref></p>
8321 <p><qref id="pkg-f-classification"><tt>Section</tt>,
8322 <tt>Priority</tt></qref></p>
8325 <p><qref id="pkg-f-Source"><tt>Source</tt></qref></p>
8328 <p><qref id="descriptions"><tt>Description</tt></qref></p>
8332 <qref id="pkg-f-Installed-Size"><tt>Installed-Size</tt></qref>
8338 A description of the syntax of control files and the purpose
8339 of these fields is available in <ref id="pkg-controlfields">.
8344 <heading>Time Stamps</heading>
8346 Maintainers are encouraged to preserve the modification
8347 times of the upstream source files in a package, as far as
8348 is reasonably possible.
8351 The rationale is that there is some information conveyed
8352 by knowing the age of the file, for example, you could
8353 recognize that some documentation is very old by looking
8354 at the modification time, so it would be nice if the
8355 modification time of the upstream source would be
8363 <appendix id="pkg-sourcepkg">
8364 <heading>Source packages (from old Packaging Manual) </heading>
8367 The Debian binary packages in the distribution are generated
8368 from Debian sources, which are in a special format to assist
8369 the easy and automatic building of binaries.
8372 <sect id="pkg-sourcetools">
8373 <heading>Tools for processing source packages</heading>
8376 Various tools are provided for manipulating source packages;
8377 they pack and unpack sources and help build of binary
8378 packages and help manage the distribution of new versions.
8382 They are introduced and typical uses described here; see
8383 <manref name="dpkg-source" section="1"> for full
8384 documentation about their arguments and operation.
8388 For examples of how to construct a Debian source package,
8389 and how to use those utilities that are used by Debian
8390 source packages, please see the <prgn>hello</prgn> example
8396 <prgn>dpkg-source</prgn> - packs and unpacks Debian source
8401 This program is frequently used by hand, and is also
8402 called from package-independent automated building scripts
8403 such as <prgn>dpkg-buildpackage</prgn>.
8407 To unpack a package it is typically invoked with
8409 dpkg-source -x <var>.../path/to/filename</var>.dsc
8414 with the <file><var>filename</var>.tar.gz</file> and
8415 <file><var>filename</var>.diff.gz</file> (if applicable) in
8416 the same directory. It unpacks into
8417 <file><var>package</var>-<var>version</var></file>, and if
8419 <file><var>package</var>-<var>version</var>.orig</file>, in
8420 the current directory.
8424 To create a packed source archive it is typically invoked:
8426 dpkg-source -b <var>package</var>-<var>version</var>
8431 This will create the <file>.dsc</file>, <file>.tar.gz</file> and
8432 <file>.diff.gz</file> (if appropriate) in the current
8433 directory. <prgn>dpkg-source</prgn> does not clean the
8434 source tree first - this must be done separately if it is
8439 See also <ref id="pkg-sourcearchives">.</p>
8445 <prgn>dpkg-buildpackage</prgn> - overall package-building
8450 <prgn>dpkg-buildpackage</prgn> is a script which invokes
8451 <prgn>dpkg-source</prgn>, the <file>debian/rules</file>
8452 targets <tt>clean</tt>, <tt>build</tt> and
8453 <tt>binary</tt>, <prgn>dpkg-genchanges</prgn> and
8454 <prgn>pgp</prgn> to build a signed source and binary
8459 It is usually invoked by hand from the top level of the
8460 built or unbuilt source directory. It may be invoked with
8461 no arguments; useful arguments include:
8462 <taglist compact="compact">
8463 <tag><tt>-uc</tt>, <tt>-us</tt></tag>
8466 Do not PGP-sign the <tt>.changes</tt> file or the
8467 source package <tt>.dsc</tt> file, respectively.</p>
8469 <tag><tt>-p<var>pgp-command</var></tt></tag>
8472 Invoke <var>pgp-command</var> instead of finding
8473 <tt>pgp</tt> on the <prgn>PATH</prgn>.
8474 <var>pgp-command</var> must behave just like
8475 <prgn>pgp</prgn>.</p>
8477 <tag><tt>-r<var>root-command</var></tt></tag>
8480 When root privilege is required, invoke the command
8481 <var>root-command</var>. <var>root-command</var>
8482 should invoke its first argument as a command, from
8483 the <prgn>PATH</prgn> if necessary, and pass its
8484 second and subsequent arguments to the command it
8485 calls. If no <var>root-command</var> is supplied
8486 then <var>dpkg-buildpackage</var> will take no
8487 special action to gain root privilege, so that for
8488 most packages it will have to be invoked as root to
8491 <tag><tt>-b</tt>, <tt>-B</tt></tag>
8494 Two types of binary-only build and upload - see
8495 <manref name="dpkg-source" section="1">.
8504 <prgn>dpkg-gencontrol</prgn> - generates binary package
8509 This program is usually called from <file>debian/rules</file>
8510 (see <ref id="pkg-sourcetree">) in the top level of the source
8515 This is usually done just before the files and directories in the
8516 temporary directory tree where the package is being built have their
8517 permissions and ownerships set and the package is constructed using
8518 <prgn>dpkg-deb/</prgn>
8521 This is so that the control file which is produced has
8522 the right permissions
8528 <prgn>dpkg-gencontrol</prgn> must be called after all the
8529 files which are to go into the package have been placed in
8530 the temporary build directory, so that its calculation of
8531 the installed size of a package is correct.
8535 It is also necessary for <prgn>dpkg-gencontrol</prgn> to
8536 be run after <prgn>dpkg-shlibdeps</prgn> so that the
8537 variable substitutions created by
8538 <prgn>dpkg-shlibdeps</prgn> in <file>debian/substvars</file>
8543 For a package which generates only one binary package, and
8544 which builds it in <file>debian/tmp</file> relative to the top
8545 of the source package, it is usually sufficient to call
8546 <prgn>dpkg-gencontrol</prgn>.
8550 Sources which build several binaries will typically need
8553 dpkg-gencontrol -Pdebian/tmp-<var>pkg</var> -p<var>package</var>
8554 </example> The <tt>-P</tt> tells
8555 <prgn>dpkg-gencontrol</prgn> that the package is being
8556 built in a non-default directory, and the <tt>-p</tt>
8557 tells it which package's control file should be generated.
8561 <prgn>dpkg-gencontrol</prgn> also adds information to the
8562 list of files in <file>debian/files</file>, for the benefit of
8563 (for example) a future invocation of
8564 <prgn>dpkg-genchanges</prgn>.</p>
8569 <prgn>dpkg-shlibdeps</prgn> - calculates shared library
8574 This program is usually called from <file>debian/rules</file>
8575 just before <prgn>dpkg-gencontrol</prgn> (see <ref
8576 id="pkg-sourcetree">), in the top level of the source tree.
8580 Its arguments are executables.
8583 In a forthcoming dpkg version,
8584 <prgn>dpkg-shlibdeps</prgn> would be required to be
8585 called on shared libraries as well.
8588 They may be specified either in the locations in the
8589 source tree where they are created or in the locations
8590 in the temporary build tree where they are installed
8591 prior to binary package creation.
8593 </footnote> for which shared library dependencies should
8594 be included in the binary package's control file.
8598 If some of the found shared libraries should only
8599 warrant a <tt>Recommends</tt> or <tt>Suggests</tt>, or if
8600 some warrant a <tt>Pre-Depends</tt>, this can be achieved
8601 by using the <tt>-d<var>dependency-field</var></tt> option
8602 before those executable(s). (Each <tt>-d</tt> option
8603 takes effect until the next <tt>-d</tt>.)
8607 <prgn>dpkg-shlibdeps</prgn> does not directly cause the
8608 output control file to be modified. Instead by default it
8609 adds to the <file>debian/substvars</file> file variable
8610 settings like <tt>shlibs:Depends</tt>. These variable
8611 settings must be referenced in dependency fields in the
8612 appropriate per-binary-package sections of the source
8617 For example, the <prgn>procps</prgn> package generates two
8618 kinds of binaries, simple C binaries like <prgn>ps</prgn>
8619 which require a predependency and full-screen ncurses
8620 binaries like <prgn>top</prgn> which require only a
8621 recommendation. It can say in its <file>debian/rules</file>:
8623 dpkg-shlibdeps -dPre-Depends ps -dRecommends top
8625 and then in its main control file <file>debian/control</file>:
8629 Pre-Depends: ${shlibs:Pre-Depends}
8630 Recommends: ${shlibs:Recommends}
8636 Sources which produce several binary packages with
8637 different shared library dependency requirements can use
8638 the <tt>-p<var>varnameprefix</var></tt> option to override
8639 the default <tt>shlibs:</tt> prefix (one invocation of
8640 <prgn>dpkg-shlibdeps</prgn> per setting of this option).
8641 They can thus produce several sets of dependency
8642 variables, each of the form
8643 <tt><var>varnameprefix</var>:<var>dependencyfield</var></tt>,
8644 which can be referred to in the appropriate parts of the
8645 binary package control files.
8652 <prgn>dpkg-distaddfile</prgn> - adds a file to
8653 <file>debian/files</file>
8657 Some packages' uploads need to include files other than
8658 the source and binary package files.
8662 <prgn>dpkg-distaddfile</prgn> adds a file to the
8663 <file>debian/files</file> file so that it will be included in
8664 the <file>.changes</file> file when
8665 <prgn>dpkg-genchanges</prgn> is run.
8669 It is usually invoked from the <tt>binary</tt> target of
8670 <file>debian/rules</file>:
8672 dpkg-distaddfile <var>filename</var> <var>section</var> <var>priority</var>
8674 The <var>filename</var> is relative to the directory where
8675 <prgn>dpkg-genchanges</prgn> will expect to find it - this
8676 is usually the directory above the top level of the source
8677 tree. The <file>debian/rules</file> target should put the
8678 file there just before or just after calling
8679 <prgn>dpkg-distaddfile</prgn>.
8683 The <var>section</var> and <var>priority</var> are passed
8684 unchanged into the resulting <file>.changes</file> file. See
8685 <ref id="pkg-f-classification">.
8690 <sect1><heading><prgn>dpkg-genchanges</prgn> - generates a <file>.changes</file> upload
8695 This program is usually called by package-independent
8696 automatic building scripts such as
8697 <prgn>dpkg-buildpackage</prgn>, but it may also be called
8702 It is usually called in the top level of a built source
8703 tree, and when invoked with no arguments will print out a
8704 straightforward <file>.changes</file> file based on the
8705 information in the source package's changelog and control
8706 file and the binary and source packages which should have
8712 <sect1><heading><prgn>dpkg-parsechangelog</prgn> - produces parsed representation of
8717 This program is used internally by
8718 <prgn>dpkg-source</prgn> et al. It may also occasionally
8719 be useful in <file>debian/rules</file> and elsewhere. It
8720 parses a changelog, <file>debian/changelog</file> by default,
8721 and prints a control-file format representation of the
8722 information in it to standard output.
8726 <sect1 id="pkg-dpkgarch"><heading><prgn>dpkg-architecture</prgn> -
8727 information about the build and host system
8731 This program can be used manually, but is also invoked by
8732 <tt>dpkg-buildpackage</tt> or <file>debian/rules</file> to set
8733 to set environment or make variables which specify the build and
8734 host architecture for the package building process.
8739 <sect id="pkg-sourcetree"><heading>The Debianised source tree
8743 The source archive scheme described later is intended to
8744 allow a Debianised source tree with some associated control
8745 information to be reproduced and transported easily. The
8746 Debianised source tree is a version of the original program
8747 with certain files added for the benefit of the
8748 Debianisation process, and with any other changes required
8749 made to the rest of the source code and installation
8754 The extra files created for Debian are in the subdirectory
8755 <file>debian</file> of the top level of the Debianised source
8756 tree. They are described below.
8759 <sect1 id="pkg-debianrules"><heading><file>debian/rules</file> - the main building
8764 This file is an executable makefile, and contains the
8765 package-specific recipies for compiling the package and
8766 building binary package(s) out of the source.
8770 It must start with the line <tt>#!/usr/bin/make -f</tt>,
8771 so that it can be invoked by saying its name rather than
8772 invoking <prgn>make</prgn> explicitly.
8776 Since an interactive <file>debian/rules</file> script makes it
8777 impossible to autocompile that package and also makes it
8778 hard for other people to reproduce the same binary
8779 package, all <strong>required targets</strong> have to be
8780 non-interactive. At a minimul, required targets are the
8781 ones called by <prgn>dpkg-buildpackage</prgn>, namely,
8782 <em>clean</em>, <em>binary</em>, <em>binary-arch</em>, and
8783 <em>build</em>. It also follows that any target that these
8784 targets depend on must also be non-interactive.
8788 The targets which are required to be present are:
8790 <tag><tt>build</tt></tag>
8793 This should perform all non-interactive
8794 configuration and compilation of the package. If a
8795 package has an interactive pre-build configuration
8796 routine, the Debianised source package should be
8797 built after this has taken place, so that it can be
8798 built without rerunning the configuration.
8802 A package may also provide both of the targets
8803 <tt>build-arch</tt> and <tt>build-indep</tt>. The
8804 <tt>build-arch</tt> target, if provided, should
8805 perform all non-interactive configuration and
8806 compilation required for producing all
8807 architecture-dependant binary packages (those packages
8808 for which the body of the <tt>Architecture</tt> field
8809 in <tt>debian/control</tt> is not <tt>all</tt>).
8810 Similarly, the <tt>build-indep</tt> target, if
8811 provided, should perform all non-interactive
8812 configuration and compilation required for producing
8813 all architecture-independent binary packages (those
8814 packages for which the body of the
8815 <tt>Architecture</tt> field in <tt>debian/control</tt>
8816 is <tt>all</tt>). The <tt>build</tt> target should
8817 depend on those of the targets <tt>build-arch</tt> and
8818 <tt>build-indep</tt> that are provided in the rules
8823 If one or both of the targets <tt>build-arch</tt> and
8824 <tt>build-indep</tt> are not provided, then invoking
8825 <file>debian/rules</file> with one of the not-provided
8826 targets as arguments should produce a exit status code
8827 of 2. Usually this is provided automatically by make
8828 if the target is missing.
8832 For some packages, notably ones where the same
8833 source tree is compiled in different ways to produce
8834 two binary packages, the <tt>build</tt> target does
8835 not make much sense. For these packages it is good
8836 enough to provide two (or more) targets
8837 (<tt>build-a</tt> and <tt>build-b</tt> or whatever)
8838 for each of the ways of building the package, and a
8839 <tt>build</tt> target that does nothing. The
8840 <tt>binary</tt> target will have to build the
8841 package in each of the possible ways and make the
8842 binary package out of each.
8846 The targets <tt>build</tt>, <tt>build-arch</tt>
8847 and <tt>build-indep</tt> target must not do
8848 anything that might require root privilege.
8852 The <tt>build</tt> target may need to run
8853 <tt>clean</tt> first - see below.
8857 When a package has a configuration routine that takes
8858 a long time, or when the makefiles are poorly
8859 designed, or when <tt>build</tt> needs to run
8860 <tt>clean</tt> first, it is a good idea to <tt>touch
8861 build</tt> when the build process is complete. This
8862 will ensure that if <tt>debian/rules build</tt> is run
8863 again it will not rebuild the whole program.
8867 <tag><tt>binary</tt>, <tt>binary-arch</tt>,
8868 <tt>binary-indep</tt>
8872 The <tt>binary</tt> target should be all that is
8873 necessary for the user to build the binary
8874 package. All these targets are required to be
8875 non-interactive. It is split into two parts:
8876 <tt>binary-arch</tt> builds the packages' output
8877 files which are specific to a particular
8878 architecture, and <tt>binary-indep</tt> builds
8879 those which are not.
8883 <tt>binary</tt> should usually be a target with
8884 no commands which simply depends on
8885 <prgn>binary-arch</prgn> and
8886 <prgn>binary-indep</prgn>.
8890 Both <prgn>binary-*</prgn> targets should depend on
8891 the <tt>build</tt> target, above, so that the
8892 package is built if it has not been already. It
8893 should then create the relevant binary package(s),
8894 using <prgn>dpkg-gencontrol</prgn> to make their
8895 control files and <prgn>dpkg-deb</prgn> to build
8896 them and place them in the parent of the top level
8901 If one of the <prgn>binary-*</prgn> targets has
8902 nothing to do (this will be always be the case if
8903 the source generates only a single binary package,
8904 whether architecture-dependent or not) it
8905 <em>must</em> still exist, but should always
8910 <ref id="pkg-binarypkg"> describes how to construct
8915 The <tt>binary</tt> targets must be invoked as
8920 <tag><tt>clean</tt></tag>
8924 This should undo any effects that the
8925 <tt>build</tt> and <tt>binary</tt> targets
8926 may have had, except that it should leave alone any
8927 output files created in the parent directory by a
8928 run of <tt>binary</tt>. This target is required
8929 to be non-interactive.
8933 If a <tt>build</tt> file is touched at the end
8934 of the <tt>build</tt> target, as suggested
8935 above, it must be removed as the first thing that
8936 <tt>clean</tt> does, so that running
8937 <tt>build</tt> again after an interrupted
8938 <tt>clean</tt> doesn't think that everything is
8943 The <tt>clean</tt> target must be invoked as
8944 root if <tt>binary</tt> has been invoked since
8945 the last <tt>clean</tt>, or if
8946 <tt>build</tt> has been invoked as root (since
8947 <tt>build</tt> may create directories, for
8952 <tag><tt>get-orig-source</tt> (optional)</tag>
8956 This target fetches the most recent version of the
8957 original source package from a canonical archive
8958 site (via FTP or WWW, for example), does any
8959 necessary rearrangement to turn it into the original
8960 source tarfile format described below, and leaves it
8961 in the current directory.
8965 This target may be invoked in any directory, and
8966 should take care to clean up any temporary files it
8971 This target is optional, but providing it if
8972 possible is a good idea.
8978 The <tt>build</tt>, <tt>binary</tt> and
8979 <tt>clean</tt> targets must be invoked with a current
8980 directory of the package's top-level directory.
8985 Additional targets may exist in <file>debian/rules</file>,
8986 either as published or undocumented interfaces or for the
8987 package's internal use.
8991 The architecture we build on and build for is determined by make
8992 variables via dpkg-architecture (see <ref id="pkg-dpkgarch">). You can
8993 get the Debian architecture and the GNU style architecture
8994 specification string for the build machine as well as the host
8995 machine. Here is a list of supported make variables:
8996 <list compact="compact">
8998 <p><tt>DEB_*_ARCH</tt> (the Debian architecture)</p>
9001 <p><tt>DEB_*_GNU_TYPE</tt> (the GNU style architecture
9002 specification string)</p>
9005 <p><tt>DEB_*_GNU_CPU</tt> (the CPU part of DEB_*_GNU_TYPE)</p>
9008 <p><tt>DEB_*_GNU_SYSTEM</tt> (the System part of
9014 where <tt>*</tt> is either <tt>BUILD</tt> for specification of
9015 the build machine or <tt>HOST</tt> for specification of the machine
9020 Backward compatibility can be provided in the rules file
9021 by setting the needed variables to suitable default
9022 values, please refer to the documentation of
9023 dpkg-architecture for details.
9027 It is important to understand that the <tt>DEB_*_ARCH</tt>
9028 string does only determine which Debian architecture we
9029 build on resp. for. It should not be used to get the CPU
9030 or System information, the GNU style variables should be
9036 <sect1><heading><file>debian/control</file>
9040 This file contains version-independent details about the
9041 source package and about the binary packages it creates.
9045 It is a series of sets of control fields, each
9046 syntactically similar to a binary package control file.
9047 The sets are separated by one or more blank lines. The
9048 first set is information about the source package in
9049 general; each subsequent set describes one binary package
9050 that the source tree builds.
9054 The syntax and semantics of the fields are described below
9055 in <ref id="pkg-controlfields">.
9059 The general (binary-package-independent) fields are:
9060 <list compact="compact">
9062 <p><qref id="pkg-f-Source"><tt>Source</tt></qref> (mandatory)</p>
9065 <p><qref id="pkg-f-Maintainer"><tt>Maintainer</tt></qref></p>
9069 <qref id="pkg-f-classification"><tt>Section</tt> and
9070 <tt>Priority</tt></qref>
9071 (classification, mandatory)
9076 <qref id="relationships"><tt>Build-Depends</tt> et
9077 al.</qref> (source package interrelationships)
9082 <qref id="pkg-f-Standards-Version"><tt>Standards-Version</tt></qref>
9088 The per-binary-package fields are:
9089 <list compact="compact">
9091 <p><qref id="pkg-f-Package"><tt>Package</tt></qref> (mandatory)</p>
9095 <qref id="pkg-f-Architecture"><tt>Architecture</tt></qref>
9099 <p><qref id="descriptions"><tt>Description</tt></qref></p>
9103 <qref id="pkg-f-classification"><tt>Section</tt> and
9104 <tt>Priority</tt></qref> (classification)</p>
9107 <p><qref id="pkg-f-Essential"><tt>Essential</tt></qref></p>
9111 <qref id="relationships"><tt>Depends</tt> et
9112 al.</qref> (binary package interrelationships)
9118 These fields are used by <prgn>dpkg-gencontrol</prgn> to
9119 generate control files for binary packages (see below), by
9120 <prgn>dpkg-genchanges</prgn> to generate the
9121 <tt>.changes</tt> file to accompany the upload, and by
9122 <prgn>dpkg-source</prgn> when it creates the <file>.dsc</file>
9123 source control file as part of a source archive.
9127 The fields here may contain variable references - their
9128 values will be substituted by
9129 <prgn>dpkg-gencontrol</prgn>, <prgn>dpkg-genchanges</prgn>
9130 or <prgn>dpkg-source</prgn> when they generate output
9131 control files. See <ref id="pkg-srcsubstvars"> for details.
9134 <p> <sect2><heading>User-defined fields
9138 Additional user-defined fields may be added to the
9139 source package control file. Such fields will be
9140 ignored, and not copied to (for example) binary or
9141 source package control files or upload control files.
9145 If you wish to add additional unsupported fields to
9146 these output files you should use the mechanism
9151 Fields in the main source control information file with
9152 names starting <tt>X</tt>, followed by one or more of
9153 the letters <tt>BCS</tt> and a hyphen <tt>-</tt>, will
9154 be copied to the output files. Only the part of the
9155 field name after the hyphen will be used in the output
9156 file. Where the letter <tt>B</tt> is used the field
9157 will appear in binary package control files, where the
9158 letter <tt>S</tt> is used in source package control
9159 files and where <tt>C</tt> is used in upload control
9160 (<tt>.changes</tt>) files.
9164 For example, if the main source information control file
9167 XBS-Comment: I stand between the candle and the star.
9169 then the binary and source package control files will contain the
9172 Comment: I stand between the candle and the star.
9179 <sect1 id="pkg-dpkgchangelog"><heading><file>debian/changelog</file>
9183 This file records the changes to the Debian-specific parts of the
9187 Though there is nothing stopping an author who is also
9188 the Debian maintainer from using it for all their
9189 changes, it will have to be renamed if the Debian and
9190 upstream maintainers become different
9197 It has a special format which allows the package building
9198 tools to discover which version of the package is being
9199 built and find out other release-specific information.
9203 That format is a series of entries like this:
9205 <var>package</var> (<var>version</var>) <var>distribution(s)</var>; urgency=<var>urgency</var>
9207 * <var>change details</var>
9208 <var>more change details</var>
9209 * <var>even more change details</var>
9211 -- <var>maintainer name and email address</var> <var>date</var>
9216 <var>package</var> and <var>version</var> are the source
9217 package name and version number.
9221 <var>distribution(s)</var> lists the distributions where
9222 this version should be installed when it is uploaded - it
9223 is copied to the <tt>Distribution</tt> field in the
9224 <tt>.changes</tt> file. See <ref id="pkg-f-Distribution">.
9228 <var>urgency</var> is the value for the <tt>Urgency</tt>
9229 field in the <file>.changes</file> file for the upload. See
9230 <ref id="pkg-f-Urgency">. It is not possible to specify an
9231 urgency containing commas; commas are used to separate
9232 <tt><var>keyword</var>=<var>value</var></tt> settings in
9233 the <prgn>dpkg</prgn> changelog format (though there is
9234 currently only one useful <var>keyword</var>,
9239 The change details may in fact be any series of lines
9240 starting with at least two spaces, but conventionally each
9241 change starts with an asterisk and a separating space and
9242 continuation lines are indented so as to bring them in
9243 line with the start of the text above. Blank lines may be
9244 used here to separate groups of changes, if desired.
9248 The maintainer name and email address should <em>not</em>
9249 necessarily be those of the usual package maintainer.
9250 They should be the details of the person doing
9251 <em>this</em> version. The information here will be
9252 copied to the <file>.changes</file> file, and then later used
9253 to send an acknowledgement when the upload has been
9258 The <var>date</var> should be in RFC822 format
9261 This is generated by the <prgn>822-date</prgn>
9264 </footnote>; it should include the timezone specified
9265 numerically, with the timezone name or abbreviation
9266 optionally present as a comment.
9270 The first "title" line with the package name should start
9271 at the left hand margin; the "trailer" line with the
9272 maintainer and date details should be preceded by exactly
9273 one space. The maintainer details and the date must be
9274 separated by exactly two spaces.
9278 An Emacs mode for editing this format is available: it is
9279 called <tt>debian-changelog-mode</tt>. You can have this
9280 mode selected automatically when you edit a Debian
9281 changelog by adding a local variables clause to the end of
9285 <sect2><heading>Defining alternative changelog formats
9289 It is possible to use a different format to the standard
9290 one, by providing a parser for the format you wish to
9295 In order to have <tt>dpkg-parsechangelog</tt> run your
9296 parser, you must include a line within the last 40 lines
9297 of your file matching the Perl regular expression:
9298 <tt>\schangelog-format:\s+([0-9a-z]+)\W</tt> The part in
9299 parentheses should be the name of the format. For
9300 example, you might say:
9302 @@@ changelog-format: joebloggs @@@
9304 Changelog format names are non-empty strings of alphanumerics.
9308 If such a line exists then <tt>dpkg-parsechangelog</tt>
9309 will look for the parser as
9310 <file>/usr/lib/dpkg/parsechangelog/<var>format-name</var></file>
9312 <file>/usr/local/lib/dpkg/parsechangelog/<var>format-name</var></file>;
9313 it is an error for it not to find it, or for it not to
9314 be an executable program. The default changelog format
9315 is <tt>dpkg</tt>, and a parser for it is provided with
9316 the <tt>dpkg</tt> package.
9320 The parser will be invoked with the changelog open on
9321 standard input at the start of the file. It should read
9322 the file (it may seek if it wishes) to determine the
9323 information required and return the parsed information
9324 to standard output in the form of a series of control
9325 fields in the standard format. By default it should
9326 return information about only the most recent version in
9327 the changelog; it should accept a
9328 <tt>-v<var>version</var></tt> option to return changes
9329 information from all versions present <em>strictly
9330 after</em> <var>version</var>, and it should then be an
9331 error for <var>version</var> not to be present in the
9337 <list compact="compact">
9339 <p><qref id="pkg-f-Source"><tt>Source</tt></qref></p>
9342 <p><qref id="versions"><tt>Version</tt></qref> (mandatory)</p>
9346 <qref id="pkg-f-Distribution"><tt>Distribution</tt></qref>
9351 <p><qref id="pkg-f-Urgency"><tt>Urgency</tt></qref> (mandatory)</p>
9355 <qref id="pkg-f-Maintainer"><tt>Maintainer</tt></qref>
9360 <p><qref id="pkg-f-Date"><tt>Date</tt></qref></p>
9364 <qref id="pkg-f-Changes"><tt>Changes</tt></qref>
9371 If several versions are being returned (due to the use
9372 of <tt>-v</tt>), the urgency value should be of the
9373 highest urgency code listed at the start of any of the
9374 versions requested followed by the concatenated
9375 (space-separated) comments from all the versions
9376 requested; the maintainer, version, distribution and
9377 date should always be from the most recent version.
9381 For the format of the <tt>Changes</tt> field see <ref
9382 id="pkg-f-Changes">.
9386 If the changelog format which is being parsed always or
9387 almost always leaves a blank line between individual
9388 change notes these blank lines should be stripped out,
9389 so as to make the resulting output compact.
9393 If the changelog format does not contain date or package
9394 name information this information should be omitted from
9395 the output. The parser should not attempt to synthesise
9396 it or find it from other sources.
9400 If the changelog does not have the expected format the
9401 parser should exit with a nonzero exit status, rather
9402 than trying to muddle through and possibly generating
9407 A changelog parser may not interact with the user at
9411 <!-- FIXME: section pkg-srcsubstvars is the same as srcsubstvars -->
9413 <sect1 id="pkg-srcsubstvars"><heading><file>debian/substvars</file>
9414 and variable substitutions
9418 When <prgn>dpkg-gencontrol</prgn>,
9419 <prgn>dpkg-genchanges</prgn> and <prgn>dpkg-source</prgn>
9420 generate control files they do variable substitutions on
9421 their output just before writing it. Variable
9422 substitutions have the form
9423 <tt>${<var>variable-name</var>}</tt>. The optional file
9424 <file>debian/substvars</file> contains variable substitutions
9425 to be used; variables can also be set directly from
9426 <file>debian/rules</file> using the <tt>-V</tt> option to the
9427 source packaging commands, and certain predefined
9428 variables are available.
9432 This file is usually generated and modified dynamically by
9433 <file>debian/rules</file> targets, in which case it must be
9434 removed by the <tt>clean</tt> target.
9438 See <manref name="dpkg-source" section="1"> for full
9439 details about source variable substitutions, including the
9440 format of <file>debian/substvars</file>.</p>
9443 <sect1><heading><file>debian/files</file>
9447 This file is not a permanent part of the source tree; it
9448 is used while building packages to record which files are
9449 being generated. <prgn>dpkg-genchanges</prgn> uses it
9450 when it generates a <file>.changes</file> file.
9454 It should not exist in a shipped source package, and so it
9455 (and any backup files or temporary files such as
9456 <file>files.new</file>
9459 <file>files.new</file> is used as a temporary file by
9460 <prgn>dpkg-gencontrol</prgn> and
9461 <prgn>dpkg-distaddfile</prgn> - they write a new
9462 version of <file>files</file> here before renaming it,
9463 to avoid leaving a corrupted copy if an error
9466 </footnote>) should be removed by the
9467 <tt>clean</tt> target. It may also be wise to
9468 ensure a fresh start by emptying or removing it at the
9469 start of the <tt>binary</tt> target.
9473 <prgn>dpkg-gencontrol</prgn> adds an entry to this file
9474 for the <file>.deb</file> file that will be created by
9475 <prgn>dpkg-deb</prgn> from the control file that it
9476 generates, so for most packages all that needs to be done
9477 with this file is to delete it in <tt>clean</tt>.
9481 If a package upload includes files besides the source
9482 package and any binary packages whose control files were
9483 made with <prgn>dpkg-gencontrol</prgn> then they should be
9484 placed in the parent of the package's top-level directory
9485 and <prgn>dpkg-distaddfile</prgn> should be called to add
9486 the file to the list in <file>debian/files</file>.</p>
9489 <sect1><heading><file>debian/tmp</file>
9493 This is the canonical temporary location for the
9494 construction of binary packages by the <tt>binary</tt>
9495 target. The directory <file>tmp</file> serves as the root of
9496 the filesystem tree as it is being constructed (for
9497 example, by using the package's upstream makefiles install
9498 targets and redirecting the output there), and it also
9499 contains the <tt>DEBIAN</tt> subdirectory. See <ref
9500 id="pkg-bincreating">.
9504 If several binary packages are generated from the same
9505 source tree it is usual to use several
9506 <file>debian/tmp<var>something</var></file> directories, for
9507 example <file>tmp-a</file> or <file>tmp-doc</file>.
9511 Whatever <file>tmp</file> directories are created and used by
9512 <tt>binary</tt> must of course be removed by the
9513 <tt>clean</tt> target.</p></sect1>
9517 <sect id="pkg-sourcearchives"><heading>Source packages as archives
9521 As it exists on the FTP site, a Debian source package
9522 consists of three related files. You must have the right
9523 versions of all three to be able to use them.
9528 <tag>Debian source control file - <tt>.dsc</tt></tag>
9532 This file contains a series of fields, identified and
9533 separated just like the fields in the control file of
9534 a binary package. The fields are listed below; their
9535 syntax is described above, in <ref id="pkg-controlfields">.
9536 <list compact="compact">
9538 <p><qref id="pkg-f-Source"><tt>Source</tt></qref></p>
9541 <p><qref id="versions"><tt>Version</tt></qref></p>
9544 <p><qref id="pkg-f-Maintainer"><tt>Maintainer</tt></qref></p>
9547 <p><qref id="pkg-f-Binary"><tt>Binary</tt></qref></p>
9550 <p><qref id="pkg-f-Architecture"><tt>Architecture</tt></qref></p>
9554 <qref id="relationships"><tt>Build-Depends</tt> et
9555 al.</qref> (source package interrelationships)
9560 <qref id="pkg-f-Standards-Version"><tt>Standards-Version</tt></qref></p>
9563 <p><qref id="pkg-f-Files"><tt>Files</tt></qref></p>
9568 The source package control file is generated by
9569 <prgn>dpkg-source</prgn> when it builds the source
9570 archive, from other files in the source package,
9571 described above. When unpacking it is checked against
9572 the files and directories in the other parts of the
9573 source package, as described below.</p>
9577 Original source archive -
9579 <var>package</var>_<var>upstream-version</var>.orig.tar.gz
9586 This is a compressed (with <tt>gzip -9</tt>)
9587 <prgn>tar</prgn> file containing the source code from
9588 the upstream authors of the program. The tarfile
9589 unpacks into a directory
9590 <file><var>package</var>-<var>upstream-version</var>.orig</file>,
9591 and does not contain files anywhere other than in
9592 there or in its subdirectories.</p>
9596 Debianisation diff -
9598 <var>package</var>_<var>upstream_version-revision</var>.diff.gz
9604 This is a unified context diff (<tt>diff -u</tt>)
9605 giving the changes which are required to turn the
9606 original source into the Debian source. These changes
9607 may only include editing and creating plain files.
9608 The permissions of files, the targets of symbolic
9609 links and the characteristics of special files or
9610 pipes may not be changed and no files may be removed
9615 All the directories in the diff must exist, except the
9616 <file>debian</file> subdirectory of the top of the source
9617 tree, which will be created by
9618 <prgn>dpkg-source</prgn> if necessary when unpacking.
9622 The <prgn>dpkg-source</prgn> program will
9623 automatically make the <file>debian/rules</file> file
9624 executable (see below).</p></item>
9629 If there is no original source code - for example, if the
9630 package is specially prepared for Debian or the Debian
9631 maintainer is the same as the upstream maintainer - the
9632 format is slightly different: then there is no diff, and the
9634 <file><var>package</var>_<var>version</var>.tar.gz</file> and
9635 contains a directory
9636 <file><var>package</var>-<var>version</var></file>.
9640 <sect><heading>Unpacking a Debian source package without
9641 <prgn>dpkg-source</prgn>
9645 <tt>dpkg-source -x</tt> is the recommended way to unpack a
9646 Debian source package. However, if it is not available it
9647 is possible to unpack a Debian source archive as follows:
9648 <enumlist compact="compact">
9651 Untar the tarfile, which will create a <file>.orig</file>
9655 <p>Rename the <file>.orig</file> directory to
9656 <file><var>package</var>-<var>version</var></file>.</p>
9660 Create the subdirectory <file>debian</file> at the top of
9661 the source tree.</p>
9663 <item><p>Apply the diff using <tt>patch -p0</tt>.</p>
9665 <item><p>Untar the tarfile again if you want a copy of the original
9666 source code alongside the Debianised version.</p>
9671 It is not possible to generate a valid Debian source archive
9672 without using <prgn>dpkg-source</prgn>. In particular,
9673 attempting to use <prgn>diff</prgn> directly to generate the
9674 <file>.diff.gz</file> file will not work.
9677 <sect1><heading>Restrictions on objects in source packages
9681 The source package may not contain any hard links
9684 This is not currently detected when building source
9685 packages, but only when extracting
9691 Hard links may be permitted at some point in the
9692 future, but would require a fair amount of
9695 </footnote>, device special files, sockets or setuid or
9699 Setgid directories are allowed.
9705 The source packaging tools manage the changes between the
9706 original and Debianised source using <prgn>diff</prgn> and
9707 <prgn>patch</prgn>. Turning the original source tree as
9708 included in the <file>.orig.tar.gz</file> into the debianised
9709 source must not involve any changes which cannot be
9710 handled by these tools. Problematic changes which cause
9711 <prgn>dpkg-source</prgn> to halt with an error when
9712 building the source package are:
9713 <list compact="compact">
9714 <item><p>Adding or removing symbolic links, sockets or pipes.</p>
9716 <item><p>Changing the targets of symbolic links.</p>
9718 <item><p>Creating directories, other than <file>debian</file>.</p>
9720 <item><p>Changes to the contents of binary files.</p></item>
9721 </list> Changes which cause <prgn>dpkg-source</prgn> to
9722 print a warning but continue anyway are:
9723 <list compact="compact">
9726 Removing files, directories or symlinks.
9729 Renaming a file is not treated specially - it is
9730 seen as the removal of the old file (which
9731 generates a warning, but is otherwise ignored),
9732 and the creation of the new
9739 Changed text files which are missing the usual final
9740 newline (either in the original or the modified
9745 Changes which are not represented, but which are not detected by
9746 <prgn>dpkg-source</prgn>, are:
9747 <list compact="compact">
9748 <item><p>Changing the permissions of files (other than
9749 <file>debian/rules</file>) and directories.</p></item>
9754 The <file>debian</file> directory and <file>debian/rules</file>
9755 are handled specially by <prgn>dpkg-source</prgn> - before
9756 applying the changes it will create the <file>debian</file>
9757 directory, and afterwards it will make
9758 <file>debian/rules</file> world-exectuable.
9764 <appendix id="pkg-controlfields"><heading>Control files and their
9765 fields (from old Packaging Manual)
9769 Many of the tools in the <prgn>dpkg</prgn> suite manipulate
9770 data in a common format, known as control files. Binary and
9771 source packages have control data as do the <file>.changes</file>
9772 files which control the installation of uploaded files, and
9773 <prgn>dpkg</prgn>'s internal databases are in a similar
9777 <sect><heading>Syntax of control files
9781 A file consists of one or more paragraphs of fields. The
9782 paragraphs are separated by blank lines. Some control files
9783 only allow one paragraph; others allow several, in which
9784 case each paragraph often refers to a different package.
9788 Each paragraph is a series of fields and values; each field
9789 consists of a name, followed by a colon and the value. It
9790 ends at the end of the line. Horizontal whitespace (spaces
9791 and tabs) may occur before or after the value and is ignored
9792 there; it is conventional to put a single space after the
9797 Some fields' values may span several lines; in this case
9798 each continuation line <em>must</em> start with a space or
9799 tab. Any trailing spaces or tabs at the end of individual
9800 lines of a field value are ignored.
9804 Except where otherwise stated only a single line of data is
9805 allowed and whitespace is not significant in a field body.
9806 Whitespace may never appear inside names (of packages,
9807 architectures, files or anything else), version numbers or
9808 in between the characters of multi-character version
9813 Field names are not case-sensitive, but it is usual to
9814 capitalise the field names using mixed case as shown below.
9818 Blank lines, or lines consisting only of spaces and tabs,
9819 are not allowed within field values or between fields - that
9820 would mean a new paragraph.
9824 It is important to note that there are several fields which
9825 are optional as far as <prgn>dpkg</prgn> and the related
9826 tools are concerned, but which must appear in every Debian
9827 package, or whose omission may cause problems.
9831 <sect><heading>List of fields
9834 <sect1 id="pkg-f-Package"><heading><tt>Package</tt>
9838 The name of the binary package. Package names consist of
9839 the alphanumerics and <tt>+</tt> <tt>-</tt> <tt>.</tt>
9840 (plus, minus and full stop).
9843 The characters <tt>@</tt> <tt>:</tt> <tt>=</tt>
9844 <tt>%</tt> <tt>_</tt> (at, colon, equals, percent
9845 and underscore) used to be legal and are still
9846 accepted when found in a package file, but may not be
9847 used in new packages
9853 They must be at least two characters and must start with
9854 an alphanumeric. In current versions of dpkg they are
9855 sort of case-sensitive<footnote><p>This is a
9856 bug.</p></footnote>; use lowercase package names unless
9857 the package you're building (or referring to, in other
9858 fields) is already using uppercase.</p>
9861 <sect1 id="pkg-f-Version"><heading><tt>Version</tt>
9865 This lists the source or binary package's version number -
9866 see <ref id="versions">.
9871 <sect1 id="pkg-f-Architecture"><heading><tt>Architecture</tt>
9875 This is the architecture string; it is a single word for
9876 the Debian architecture.
9880 <prgn>dpkg</prgn> will check the declared architecture of
9881 a binary package against its own compiled-in value before
9886 The special value <tt>all</tt> indicates that the package
9887 is architecture-independent.
9891 In the main <file>debian/control</file> file in the source
9892 package, or in the source package control file
9893 <file>.dsc</file>, a list of architectures (separated by
9894 spaces) is also allowed, as is the special value
9895 <tt>any</tt>. A list indicates that the source will build
9896 an architecture-dependent package, and will only work
9897 correctly on the listed architectures. <tt>any</tt>
9898 indicates that though the source package isn't dependent
9899 on any particular architecture and should compile fine on
9900 any one, the binary package(s) produced are not
9901 architecture-independent but will instead be specific to
9902 whatever the current build architecture is.
9906 In a <file>.changes</file> file the <tt>Architecture</tt>
9907 field lists the architecture(s) of the package(s)
9908 currently being uploaded. This will be a list; if the
9909 source for the package is being uploaded too the special
9910 entry <tt>source</tt> is also present.
9914 See <ref id="pkg-debianrules"> for information how to get the
9915 architecture for the build process.
9919 <sect1 id="pkg-f-Maintainer"><heading><tt>Maintainer</tt>
9923 The package maintainer's name and email address. The name
9924 should come first, then the email address inside angle
9925 brackets <tt><></tt> (in RFC822 format).
9929 If the maintainer's name contains a full stop then the
9930 whole field will not work directly as an email address due
9931 to a misfeature in the syntax specified in RFC822; a
9932 program using this field as an address must check for this
9933 and correct the problem if necessary (for example by
9934 putting the name in round brackets and moving it to the
9935 end, and bringing the email address forward).
9939 In a <file>.changes</file> file or parsed changelog data this
9940 contains the name and email address of the person
9941 responsible for the particular version in question - this
9942 may not be the package's usual maintainer.
9946 This field is usually optional in as far as the
9947 <prgn>dpkg</prgn> are concerned, but its absence when
9948 building packages usually generates a warning.</p>
9951 <sect1 id="pkg-f-Source"><heading><tt>Source</tt>
9955 This field identifies the source package name.
9959 In a main source control information or a
9960 <file>.changes</file> or <file>.dsc</file> file or parsed
9961 changelog data this may contain only the name of the
9966 In the control file of a binary package (or in a
9967 <file>Packages</file> file) it may be followed by a version
9968 number in parentheses.
9971 It is usual to leave a space after the package name if
9972 a version number is specified.
9974 </footnote> This version number may be omitted (and is, by
9975 <prgn>dpkg-gencontrol</prgn>) if it has the same value as
9976 the <tt>Version</tt> field of the binary package in
9977 question. The field itself may be omitted from a binary
9978 package control file when the source package has the same
9979 name and version as the binary package.
9983 <sect1><heading>Package interrelationship fields:
9984 <tt>Depends</tt>, <tt>Pre-Depends</tt>,
9985 <tt>Recommends</tt> <tt>Suggests</tt>, <tt>Conflicts</tt>,
9986 <tt>Provides</tt>, <tt>Replaces</tt>
9990 These fields describe the package's relationships with
9991 other packages. Their syntax and semantics are described
9992 in <ref id="relationships">.</p>
9995 <sect1 id="pkg-f-Description"><heading><tt>Description</tt>
9999 In a binary package <tt>Packages</tt> file or main source
10000 control file this field contains a description of the
10001 binary package, in a special format. See <ref
10002 id="descriptions"> for details.
10006 In a <file>.changes</file> file it contains a summary of the
10007 descriptions for the packages being uploaded. The part of
10008 the field before the first newline is empty; thereafter
10009 each line has the name of a binary package and the summary
10010 description line from that binary package. Each line is
10011 indented by one space.</p>
10014 <sect1 id="pkg-f-Essential"><heading><tt>Essential</tt>
10018 This is a boolean field which may occur only in the
10019 control file of a binary package (or in the
10020 <file>Packages</file> file) or in a per-package fields
10021 paragraph of a main source control data file.
10025 If set to <tt>yes</tt> then <prgn>dpkg</prgn> and
10026 <prgn>dselect</prgn> will refuse to remove the package
10027 (though it can be upgraded and/or replaced). The other
10028 possible value is <tt>no</tt>, which is the same as not
10029 having the field at all.</p>
10032 <sect1 id="pkg-f-classification"><heading><tt>Section</tt> and
10037 These two fields classify the package. The
10038 <tt>Priority</tt> represents how important that it is that
10039 the user have it installed; the <tt>Section</tt>
10040 represents an application area into which the package has
10045 When they appear in the <file>debian/control</file> file these
10046 fields give values for the section and priority subfields
10047 of the <tt>Files</tt> field of the <file>.changes</file> file,
10048 and give defaults for the section and priority of the
10053 The section and priority are represented, though not as
10054 separate fields, in the information for each file in the
10055 <qref id="pkg-f-Files"><tt>-File</tt></qref>field of a
10056 <file>.changes</file> file. The section value in a
10057 <file>.changes</file> file is used to decide where to install
10058 a package in the FTP archive.
10062 These fields are not used by by <prgn>dpkg</prgn> proper,
10063 but by <prgn>dselect</prgn> when it sorts packages and
10068 These fields can appear in binary package control files,
10069 in which case they provide a default value in case the
10070 <file>Packages</file> files are missing the information.
10071 <prgn>dpkg</prgn> and <prgn>dselect</prgn> will only use
10072 the value from a <file>.deb</file> file if they have no other
10073 information; a value listed in a <file>Packages</file> file
10074 will always take precedence. By default
10075 <prgn>dpkg-gencontrol</prgn> does not include the section
10076 and priority in the control file of a binary package - use
10077 the <tt>-isp</tt>, <tt>-is</tt> or <tt>-ip</tt> options to
10078 achieve this effect.</p>
10081 <sect1 id="pkg-f-Binary"><heading><tt>Binary</tt>
10085 This field is a list of binary packages.
10089 When it appears in the <file>.dsc</file> file it is the list
10090 of binary packages which a source package can produce. It
10091 does not necessarily produce all of these binary packages
10092 for every architecture. The source control file doesn't
10093 contain details of which architectures are appropriate for
10094 which of the binary packages.
10098 When it appears in a <file>.changes</file> file it lists the
10099 names of the binary packages actually being uploaded.
10103 The syntax is a list of binary packages separated by
10107 A space after each comma is conventional.
10109 </footnote> Currently the packages must be separated using
10110 only spaces in the <file>.changes</file> file.</p>
10113 <sect1 id="pkg-f-Installed-Size"><heading><tt>Installed-Size</tt>
10117 This field appears in the control files of binary
10118 packages, and in the <file>Packages</file> files. It gives
10119 the total amount of disk space required to install the
10124 The disk space is represented in kilobytes as a simple
10125 decimal number.</p>
10128 <sect1 id="pkg-f-Files"><heading><tt>Files</tt>
10132 This field contains a list of files with information about
10133 each one. The exact information and syntax varies with
10134 the context. In all cases the part of the field
10135 contents on the same line as the field name is empty. The
10136 remainder of the field is one line per file, each line
10137 being indented by one space and containing a number of
10138 sub-fields separated by spaces.
10142 In the <file>.dsc</file> (Debian source control) file each
10143 line contains the MD5 checksum, size and filename of the
10144 tarfile and (if applicable) diff file which make up the
10145 remainder of the source package.
10148 That is, the parts which are not the
10151 </footnote> The exact forms of the filenames are described
10152 in <ref id="pkg-sourcearchives">.
10156 In the <file>.changes</file> file this contains one line per
10157 file being uploaded. Each line contains the MD5 checksum,
10158 size, section and priority and the filename. The section
10159 and priority are the values of the corresponding fields in
10160 the main source control file - see <ref
10161 id="pkg-f-classification">. If no section or priority is
10162 specified then <tt>-</tt> should be used, though section
10163 and priority values must be specified for new packages to
10164 be installed properly.
10168 The special value <tt>byhand</tt> for the section in a
10169 <tt>.changes</tt> file indicates that the file in question
10170 is not an ordinary package file and must by installed by
10171 hand by the distribution maintainers. If the section is
10172 <tt>byhand</tt> the priority should be <tt>-</tt>.
10176 If a new Debian revision of a package is being shipped and
10177 no new original source archive is being distributed the
10178 <tt>.dsc</tt> must still contain the <tt>Files</tt> field
10179 entry for the original source archive
10180 <file><var>package</var>-<var>upstream-version</var>.orig.tar.gz</file>,
10181 but the <file>.changes</file> file should leave it out. In
10182 this case the original source archive on the distribution
10183 site must match exactly, byte-for-byte, the original
10184 source archive which was used to generate the
10185 <file>.dsc</file> file and diff which are being uploaded.</p>
10190 id="pkg-f-Standards-Version"><heading><tt>Standards-Version</tt>
10194 The most recent version of the standards (the Debian Policy
10195 and associated texts) with which the package complies. This
10196 is updated manually when editing the source package to
10197 conform to newer standards; it can sometimes be used to
10198 tell when a package needs attention.
10202 Its format is the same as that of a version number except
10203 that no epoch or Debian revision is allowed - see <ref
10204 id="versions">.</p>
10208 <sect1 id="pkg-f-Distribution"><heading><tt>Distribution</tt>
10212 In a <file>.changes</file> file or parsed changelog output
10213 this contains the (space-separated) name(s) of the
10214 distribution(s) where this version of the package should
10215 be or was installed. Distribution names follow the rules
10216 for package names. (See <ref id="pkg-f-Package">).
10220 Current distribution values are:
10222 <tag><em>stable</em></tag>
10225 This is the current "released" version of Debian
10226 GNU/Linux. A new version is released approximately
10227 every 3 months after the <em>development</em> code has
10228 been <em>frozen</em> for a month of testing. Once the
10229 distribution is <em>stable</em> only major bug fixes
10230 are allowed. When changes are made to this
10231 distribution, the release number is increased
10232 (for example: 1.2r1 becomes 1.2r2 then 1.2r3, etc).
10236 <tag><em>unstable</em></tag>
10239 This distribution value refers to the
10240 <em>developmental</em> part of the Debian distribution
10241 tree. New packages, new upstream versions of packages
10242 and bug fixes go into the <em>unstable</em> directory
10243 tree. Download from this distribution at your own
10247 <tag><em>contrib</em></tag>
10250 The packages with this distribution value do not meet
10251 the criteria for inclusion in the main Debian
10252 distribution as defined by the Policy Manual, but meet
10253 the criteria for the <em>contrib</em>
10254 Distribution. There is currently no distinction
10255 between stable and unstable packages in the
10256 <em>contrib</em> or <em>non-free</em>
10257 distributions. Use your best judgement in downloading
10258 from this Distribution.</p>
10261 <tag><em>non-free</em></tag>
10264 Like the packages in the <em>contrib</em> seciton,
10265 the packages in <em>non-free</em> do not meet the
10266 criteria for inclusion in the main Debian distribution
10267 as defined by the Policy Manual. Again, use your best
10268 judgement in downloading from this Distribution.</p>
10270 <tag><em>experimental</em></tag>
10273 The packages with this distribution value are deemed
10274 by their maintainers to be high risk. Oftentimes they
10275 represent early beta or developmental packages from
10276 various sources that the maintainers want people to
10277 try, but are not ready to be a part of the other parts
10278 of the Debian distribution tree. Download at your own
10282 <tag><em>frozen</em></tag>
10285 From time to time, (currently, every 3 months) the
10286 <em>unstable</em> distribution enters a state of
10287 "code-freeze" in anticipation of release as a
10288 <em>stable</em> version. During this period of testing
10289 (usually 4 weeks) only fixes for existing or
10290 newly-discovered bugs will be allowed.
10293 </taglist> You should list <em>all</em> distributions that
10294 the package should be installed into. Except in unusual
10295 circumstances, installations to <em>stable</em> should also
10296 go into <em>frozen</em> (if it exists) and
10297 <em>unstable</em>. Likewise, installations into
10298 <em>frozen</em> should also go into <em>unstable</em>.</p>
10301 <sect1 id="pkg-f-Urgency"><heading><tt>Urgency</tt>
10305 This is a description of how important it is to upgrade to
10306 this version from previous ones. It consists of a single
10307 keyword usually taking one of the values <tt>LOW</tt>,
10308 <tt>MEDIUM</tt> or <tt>HIGH</tt>) followed by an optional
10309 commentary (separated by a space) which is usually in
10310 parentheses. For example:
10312 Urgency: LOW (HIGH for diversions users)
10317 This field appears in the <file>.changes</file> file and in
10318 parsed changelogs; its value appears as the value of the
10319 <tt>urgency</tt> attribute in a <prgn>dpkg</prgn>-style
10320 changelog (see <ref id="pkg-dpkgchangelog">).
10324 Urgency keywords are not case-sensitive.</p>
10327 <sect1 id="pkg-f-Date"><heading><tt>Date</tt>
10331 In <tt>.changes</tt> files and parsed changelogs, this
10332 gives the date the package was built or last edited.</p>
10335 <sect1 id="pkg-f-Format"><heading><tt>Format</tt>
10339 This field occurs in <file>.changes</file> files, and
10340 specifies a format revision for the file. The format
10341 described here is version <tt>1.5</tt>. The syntax of the
10342 format value is the same as that of a package version
10343 number except that no epoch or Debian revision is allowed
10344 - see <ref id="versions">.</p>
10347 <sect1 id="pkg-f-Changes"><heading><tt>Changes</tt>
10351 In a <file>.changes</file> file or parsed changelog this field
10352 contains the human-readable changes data, describing the
10353 differences between the last version and the current one.
10357 There should be nothing in this field before the first
10358 newline; all the subsequent lines must be indented by at
10359 least one space; blank lines must be represented by a line
10360 consiting only of a space and a full stop.
10364 Each version's change information should be preceded by a
10365 "title" line giving at least the version, distribution(s)
10366 and urgency, in a human-readable way.
10370 If data from several versions is being returned the entry
10371 for the most recent version should be returned first, and
10372 entries should be separated by the representation of a
10373 blank line (the "title" line may also be followed by the
10374 representation of blank line).</p>
10377 <sect1 id="pkg-f-Filename"><heading><tt>Filename</tt> and
10378 <tt>MSDOS-Filename</tt>
10382 These fields in <tt>Packages</tt> files give the
10383 filename(s) of (the parts of) a package in the
10384 distribution directories, relative to the root of the
10385 Debian hierarchy. If the package has been split into
10386 several parts the parts are all listed in order, separated
10390 <sect1 id="pkg-f-Size"><heading><tt>Size</tt> and <tt>MD5sum</tt>
10394 These fields in <file>Packages</file> files give the size (in
10395 bytes, expressed in decimal) and MD5 checksum of the
10396 file(s) which make(s) up a binary package in the
10397 distribution. If the package is split into several parts
10398 the values for the parts are listed in order, separated by
10402 <sect1 id="pkg-f-Status"><heading><tt>Status</tt>
10406 This field in <prgn>dpkg</prgn>'s status file records
10407 whether the user wants a package installed, removed or
10408 left alone, whether it is broken (requiring
10409 reinstallation) or not and what its current state on the
10410 system is. Each of these pieces of information is a
10414 <sect1 id="pkg-f-Config-Version"><heading><tt>Config-Version</tt>
10418 If a package is not installed or not configured, this
10419 field in <prgn>dpkg</prgn>'s status file records the last
10420 version of the package which was successfully
10424 <sect1 id="pkg-f-Conffiles"><heading><tt>Conffiles</tt>
10428 This field in <prgn>dpkg</prgn>'s status file contains
10429 information about the automatically-managed configuration
10430 files held by a package. This field should <em>not</em>
10431 appear anywhere in a package!</p>
10434 <sect1><heading>Obsolete fields
10438 These are still recognised by <prgn>dpkg</prgn> but should
10439 not appear anywhere any more.
10440 <taglist compact="compact">
10442 <tag><tt>Revision</tt></tag>
10443 <tag><tt>Package-Revision</tt></tag>
10444 <tag><tt>Package_Revision</tt></tag>
10447 The Debian revision part of the package version was
10448 at one point in a separate control file field. This
10449 field went through several names.</p>
10452 <tag><tt>Recommended</tt></tag>
10453 <item><p>Old name for <tt>Recommends</tt></p>
10456 <tag><tt>Optional</tt></tag>
10457 <item><p>Old name for <tt>Suggests</tt>.</p>
10459 <tag><tt>Class</tt></tag>
10460 <item><p>Old name for <tt>Priority</tt>.</p>
10468 <appendix id="pkg-conffiles"><heading>Configuration file handling
10469 (from old Packaging Manual)
10473 <prgn>dpkg</prgn> can do a certain amount of automatic
10474 handling of package configuration files.
10478 Whether this mechanism is appropriate depends on a number of
10479 factors, but basically there are two approaches to any
10480 particular configuration file.
10484 The easy method is to ship a best-effort configuration in the
10485 package, and use <prgn>dpkg</prgn>'s conffile mechanism to
10486 handle updates. If the user is unlikely to want to edit the
10487 file, but you need them to be able to without losing their
10488 changes, and a new package with a changed version of the file
10489 is only released infrequently, this is a good approach.
10493 The hard method is to build the configuration file from
10494 scratch in the <prgn>postinst</prgn> script, and to take the
10495 responsibility for fixing any mistakes made in earlier
10496 versions of the package automatically. This will be
10497 appropriate if the file is likely to need to be different on
10501 <sect><heading>Automatic handling of configuration files by
10506 A package may contain a control area file called
10507 <tt>conffiles</tt>. This file should be a list of filenames
10508 of configuration files needing automatic handling, separated
10509 by newlines. The filenames should be absolute pathnames,
10510 and the files referred to should actually exist in the
10515 When a package is upgraded <prgn>dpkg</prgn> will process
10516 the configuration files during the configuration stage,
10517 shortly before it runs the package's <prgn>postinst</prgn>
10522 For each file it checks to see whether the version of the
10523 file included in the package is the same as the one that was
10524 included in the last version of the package (the one that is
10525 being upgraded from); it also compares the version currently
10526 installed on the system with the one shipped with the last
10531 If neither the user nor the package maintainer has changed
10532 the file, it is left alone. If one or the other has changed
10533 their version, then the changed version is preferred - i.e.,
10534 if the user edits their file, but the package maintainer
10535 doesn't ship a different version, the user's changes will
10536 stay, silently, but if the maintainer ships a new version
10537 and the user hasn't edited it the new version will be
10538 installed (with an informative message). If both have
10539 changed their version the user is prompted about the problem
10540 and must resolve the differences themselves.
10544 The comparisons are done by calculating the MD5 message
10545 digests of the files, and storing the MD5 of the file as it
10546 was included in the most recent version of the package.
10550 When a package is installed for the first time
10551 <prgn>dpkg</prgn> will install the file that comes with it,
10552 unless that would mean overwriting a file already on the
10557 However, note that <prgn>dpkg</prgn> will <em>not</em>
10558 replace a conffile that was removed by the user (or by a
10559 script). This is necessary because with some programs a
10560 missing file produces an effect hard or impossible to
10561 achieve in another way, so that a missing file needs to be
10562 kept that way if the user did it.
10566 Note that a package should <em>not</em> modify a
10567 <prgn>dpkg</prgn>-handled conffile in its maintainer
10568 scripts. Doing this will lead to <prgn>dpkg</prgn> giving
10569 the user confusing and possibly dangerous options for
10570 conffile update when the package is upgraded.</p>
10573 <sect><heading>Fully-featured maintainer script configuration
10578 For files which contain site-specific information such as
10579 the hostname and networking details and so forth, it is
10580 better to create the file in the package's
10581 <prgn>postinst</prgn> script.
10585 This will typically involve examining the state of the rest
10586 of the system to determine values and other information, and
10587 may involve prompting the user for some information which
10588 can't be obtained some other way.
10592 When using this method there are a couple of important
10593 issues which should be considered:
10597 If you discover a bug in the program which generates the
10598 configuration file, or if the format of the file changes
10599 from one version to the next, you will have to arrange for
10600 the postinst script to do something sensible - usually this
10601 will mean editing the installed configuration file to remove
10602 the problem or change the syntax. You will have to do this
10603 very carefully, since the user may have changed the file,
10604 perhaps to fix the very problem that your script is trying
10605 to deal with - you will have to detect these situations and
10606 deal with them correctly.
10610 If you do go down this route it's probably a good idea to
10611 make the program that generates the configuration file(s) a
10612 separate program in <file>/usr/sbin</file>, by convention called
10613 <file><var>package</var>config</file> and then run that if
10614 appropriate from the post-installation script. The
10615 <tt><var>package</var>config</tt> program should not
10616 unquestioningly overwrite an existing configuration - if its
10617 mode of operation is geared towards setting up a package for
10618 the first time (rather than any arbitrary reconfiguration
10619 later) you should have it check whether the configuration
10620 already exists, and require a <tt>--force</tt> flag to
10621 overwrite it.</p></sect>
10624 <appendix id="pkg-alternatives"><heading>Alternative versions of
10625 an interface - <prgn>update-alternatives</prgn> (from old
10630 When several packages all provide different versions of the
10631 same program or file it is useful to have the system select a
10632 default, but to allow the system administrator to change it
10633 and have their decisions respected.
10637 For example, there are several versions of the <prgn>vi</prgn>
10638 editor, and there is no reason to prevent all of them from
10639 being installed at once, each under their own name
10640 (<prgn>nvi</prgn>, <prgn>vim</prgn> or whatever).
10641 Nevertheless it is desirable to have the name <tt>vi</tt>
10642 refer to something, at least by default.
10646 If all the packages involved cooperate, this can be done with
10647 <prgn>update-alternatives</prgn>.
10651 Each package provides its own version under its own name, and
10652 calls <prgn>update-alternatives</prgn> in its postinst to
10653 register its version (and again in its prerm to deregister
10658 See the manpage <manref name="update-alternatives"
10659 section="8"> for details.
10663 If <prgn>update-alternatives</prgn> does not seem appropriate
10664 you may wish to consider using diversions instead.</p>
10667 <appendix id="pkg-diversions"><heading>Diversions - overriding a
10668 package's version of a file (from old Packaging Manual)
10672 It is possible to have <prgn>dpkg</prgn> not overwrite a file
10673 when it reinstalls the package it belongs to, and to have it
10674 put the file from the package somewhere else instead.
10678 This can be used locally to override a package's version of a
10679 file, or by one package to override another's version (or
10680 provide a wrapper for it).
10684 Before deciding to use a diversion, read <ref
10685 id="pkg-alternatives"> to see if you really want a diversion
10686 rather than several alternative versions of a program.
10690 There is a diversion list, which is read by <prgn>dpkg</prgn>,
10691 and updated by a special program <prgn>dpkg-divert</prgn>.
10692 Please see <manref name="dpkg-divert" section="8"> for full
10693 details of its operation.
10697 When a package wishes to divert a file from another, it should
10698 call <prgn>dpkg-divert</prgn> in its preinst to add the
10699 diversion and rename the existing file. For example,
10700 supposing that a <prgn>smailwrapper</prgn> package wishes to
10701 install a wrapper around <file>/usr/sbin/smail</file>:
10703 if [ install = "$1" ]; then
10704 dpkg-divert --package smailwrapper --add --rename \
10705 --divert /usr/sbin/smail.real /usr/sbin/smail
10707 </example> Testing <tt>$1</tt> is necessary so that the script
10708 doesn't try to add the diversion again when
10709 <prgn>smailwrapper</prgn> is upgraded. The <tt>--package
10710 smailwrapper</tt> ensures that <prgn>smailwrapper</prgn>'s
10711 copy of <file>/usr/sbin/smail</file> can bypass the diversion and
10712 get installed as the true version.
10716 The postrm has to do the reverse:
10718 if [ remove = "$1" ]; then
10719 dpkg-divert --package smailwrapper --remove --rename \
10720 --divert /usr/sbin/smail.real /usr/sbin/smail
10726 Do not attempt to divert a file which is vitally important for
10727 the system's operation - when using <prgn>dpkg-divert</prgn>
10728 there is a time, after it has been diverted but before
10729 <prgn>dpkg</prgn> has installed the new version, when the file
10730 does not exist.</p>
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