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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 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 hand, or by
1108 communicating with a program, such as
1109 <prgn>debconf</prgn>, which conforms to the Debian
1110 Configuration management specification, version 2 or
1111 higher. These are included in the
1112 <file>debconf_specification</file> files in the
1113 <package>debian-policy</package> package.
1114 You may also find this file on the FTP site
1115 <ftpsite>ftp.debian.org</ftpsite> in
1116 <ftppath>/debian/doc/package-developer/debconf_specification.txt.gz</ftppath>
1117 or on your local mirror.<footnote>
1119 4% of Debian packages [see <url
1120 id="http://kitenet.net/programs/debconf/stats/"
1121 name="Debconf stats">] currently use
1122 <package>debconf</package> to prompt the user at
1123 install time, and this number is growing daily. The
1124 benefits of using debconf are briefly explained at
1126 id="http://kitenet.net/doc/debconf-doc/introduction.html"
1127 name="Debconf introduction">; they include
1128 preconfiguration, (mostly) noninteractive
1129 installation, elimination of redundant prompting,
1130 consistency of user interface, etc.
1133 With this increasing number of packages using
1134 <package>debconf</package>, plus the existance of a
1135 nascent second implementation of the Debian
1136 configuration management system
1137 (<package>cdebconf</package>), and the stabilization
1138 of the protocol these things use, the time has
1139 finally come to reflect the use of these things in
1146 Packages which use the Debian Configuration management
1147 specification may contain an additional
1148 <prgn>config</prgn> script and a <tt>templates</tt>
1149 file in their control archive. The <prgn>config</prgn>
1150 script might be run before the <prgn>preinst</prgn>
1151 script, and before the package is unpacked or any of its
1152 dependencies or pre-dependancies are satisfied.
1153 Therefore it must work using only the tools present in
1154 <em>essential</em> packages.<footnote>
1156 <package>Debconf</package> or another tool that
1157 implements the Debian Configuration management
1158 specification will also be installed, and any
1159 versioned dependencies on it will be satisfied
1160 before preconfiguration begins.
1166 Packages should try to minimize the amount of prompting
1167 they need to do, and they should ensure that the user
1168 will only ever be asked each question once. This means
1169 that packages should try to use appropriate shared
1170 configuration files (such as <file>/etc/papersize</file> and
1171 <file>/etc/news/server</file>), and shared
1172 <package>debconf</package> variables rather than each
1173 prompting for their own list of required pieces of
1178 It also means that an upgrade should not ask the same
1179 questions again, unless the user has used <tt>dpkg
1180 --purge</tt> to remove the package's configuration. The
1181 answers to configuration questions should be stored in an
1182 appropriate place in <file>/etc</file> so that the user can
1183 modify them, and how this has been done should be
1187 If a package has a vitally important piece of
1188 information to pass to the user (such as "don't run me
1189 as I am, you must edit the following configuration files
1190 first or you risk your system emitting badly-formatted
1191 messages"), it should display this in the
1192 <prgn>config</prgn> or <prgn>postinst</prgn> script and
1193 prompt the user to hit return to acknowledge the
1194 message. Copyright messages do not count as vitally
1195 important (they belong in
1196 <file>/usr/share/doc/<var>package</var>/copyright</file>);
1197 neither do instructions on how to use a program (these
1198 should be in on-line documentation, where all the users
1202 Any necessary prompting should almost always be confined
1203 to the <prgn>config</prgn> or <prgn>postinst</prgn>
1204 script. If it is done in the <prgn>postinst</prgn>, it
1205 should be protected with a conditional so that
1206 unnecessary prompting doesn't happen if a package's
1207 installation fails and the <prgn>postinst</prgn> is
1208 called with <tt>abort-upgrade</tt>,
1209 <tt>abort-remove</tt> or <tt>abort-deconfigure</tt>.</p>
1214 <heading>Source packages</heading>
1216 <sect1 id="standardsversion">
1217 <heading>Standards conformance</heading>
1220 In the source package's <tt>Standards-Version</tt> control
1221 field, you should specify the most recent version number
1222 of this policy document with which your package complied
1223 when it was last updated. The current version number is
1228 This information may be used to file bug reports
1229 automatically if your package becomes too much out of
1234 The version number has four components: major and minor
1235 version number and major and minor patch level. When the
1236 standards change in a way that requires every package to
1237 change the major number will be changed. Significant
1238 changes that will require work in many packages will be
1239 signaled by a change to the minor number. The major patch
1240 level will be changed for any change to the meaning of the
1241 standards, however small; the minor patch level will be
1242 changed when only cosmetic, typographical or other edits
1243 are made which neither change the meaning of the document
1244 nor affect the contents of packages.</p>
1247 Thus only the first three components of the policy version
1248 are significant in the <em>Standards-Version</em> control
1249 field, and so either these three components or the all
1250 four components may be specified.<footnote>
1252 In the past, people specified the full version number
1253 in the Standards-Version field, for example "2.3.0.0".
1254 Since minor patch-level changes don't introduce new
1255 policy, it was thought it would be better to relax
1256 policy and only require the first 3 components to be
1257 specified, in this example "2.3.0". All four
1258 components may still be used if someone wishes to do
1265 You should regularly, and especially if your package has
1266 become out of date, check for the newest Policy Manual
1267 available and update your package, if necessary. When your
1268 package complies with the new standards you should update the
1269 <tt>Standards-Version</tt> source package field and
1270 release it.<footnote>
1272 See the file <file>upgrading-checklist</file> for
1273 information about policy which has changed between
1274 different versions of this document.
1281 <sect1 id="pkg-relations">
1282 <heading>Package relationships</heading>
1285 Source packages should specify which binary packages they
1286 require to be installed or not to be installed in order to
1287 build correctly. For example, if building a package
1288 requires a certain compiler, then the compiler should be
1289 specified as a build-time dependency.
1293 It is not necessary to explicitly specify build-time
1294 relationships on a minimal set of packages that are always
1295 needed to compile, link and put in a Debian package a
1296 standard "Hello World!" program written in C or C++. The
1297 required packages are called <em>build-essential</em>, and
1298 an informational list can be found in
1299 <file>/usr/share/doc/build-essential/list</file> (which is
1300 contained in the <tt>build-essential</tt>
1303 <list compact="compact">
1305 <p>This allows maintaining the list separately
1306 from the policy documents (the list does not
1307 need the kind of control that the policy
1313 Having a separate package allows one to install
1314 the build-essential packages on a machine, as
1315 well as allowing other packages such as tasks to
1316 require installation of the build-essential
1317 packages using the depends relation.
1322 The separate package allows bug reports against
1323 the list to be categorized separately from
1324 the policy management process in the BTS.
1334 When specifying the set of build-time dependencies, one
1335 should list only those packages explicitly required by the
1336 build. It is not necessary to list packages which are
1337 required merely because some other package in the list of
1338 build-time dependencies depends on them.<footnote>
1340 The reason for this is that dependencies change, and
1341 you should list all those packages, and <em>only</em>
1342 those packages that <em>you</em> need directly. What
1343 others need is their business. For example, if you
1344 only link against <file>libimlib</file>, you will need to
1345 build-depend on <package>libimlib2-dev</package> but
1346 not against any <tt>libjpeg*</tt> packages, even
1347 though <tt>libimlib2-dev</tt> currently depends on
1348 them: installation of <package>libimlib2-dev</package>
1349 will automatically ensure that all of its run-time
1350 dependencies are satisfied.
1356 If build-time dependencies are specified, it must be
1357 possible to build the package and produce working binaries
1358 on a system with only essential and build-essential
1359 packages installed and also those required to satisfy the
1360 build-time relationships (including any implied
1361 relationships). In particular, this means that version
1362 clauses should be used rigorously in build-time
1363 relationships so that one cannot produce bad or
1364 inconsistently configured packages when the relationships
1365 are properly satisfied.
1369 <ref id="relationships"> explains the technical details.
1373 <heading>Changes to the upstream sources</heading>
1376 If changes to the source code are made that are not
1377 specific to the needs of the Debian system, they should be
1378 sent to the upstream authors in whatever form they prefer
1379 so as to be included in the upstream version of the
1383 If you need to configure the package differently for
1384 Debian or for Linux, and the upstream source doesn't
1385 provide a way to do so, you should add such configuration
1386 facilities (for example, a new <prgn>autoconf</prgn> test
1387 or <tt>#define</tt>) and send the patch to the upstream
1388 authors, with the default set to the way they originally
1389 had it. You can then easily override the default in your
1390 <file>debian/rules</file> or wherever is appropriate.</p>
1393 You should make sure that the <prgn>configure</prgn> utility
1394 detects the correct architecture specification string
1395 (refer to <ref id="arch-spec"> for details).</p>
1398 If you need to edit a <prgn>Makefile</prgn> where
1399 GNU-style <prgn>configure</prgn> scripts are used, you
1400 should edit the <file>.in</file> files rather than editing the
1401 <prgn>Makefile</prgn> directly. This allows the user to
1402 reconfigure the package if necessary. You should
1403 <em>not</em> configure the package and edit the generated
1404 <prgn>Makefile</prgn>! This makes it impossible for
1405 someone else to later reconfigure the package.</p>
1408 You should document your changes and updates to the source
1409 package properly in the <file>debian/changelog</file> file.
1410 For more information, please see <ref id="changelogs">.
1416 <heading>Error trapping in makefiles</heading>
1419 When <prgn>make</prgn> invokes a command in a makefile
1420 (including your package's upstream makefiles and
1421 <file>debian/rules</file>), it does so using <prgn>sh</prgn>. This
1422 means that <prgn>sh</prgn>'s usual bad error handling
1423 properties apply: if you include a miniature script as one
1424 of the commands in your makefile you'll find that if you
1425 don't do anything about it then errors are not detected
1426 and <prgn>make</prgn> will blithely continue after
1430 Every time you put more than one shell command (this
1431 includes using a loop) in a makefile command you
1432 must make sure that errors are trapped. For
1433 simple compound commands, such as changing directory and
1434 then running a program, using <tt>&&</tt> rather
1435 than semicolon as a command separator is sufficient. For
1436 more complex commands including most loops and
1437 conditionals you should include a separate <tt>set -e</tt>
1438 command at the start of every makefile command that's
1439 actually one of these miniature shell scripts.</p></sect1>
1443 <heading>Obsolete constructs and libraries</heading>
1446 The include file <tt><varargs.h></tt> is
1447 provided to support end-users compiling very old software;
1448 the library <tt>libtermcap</tt> is provided to support the
1449 execution of software which has been linked against it
1450 (either old programs or those such as Netscape which are
1451 only available in binary form).</p>
1454 Debian packages should be patched to use
1455 <tt><stdarg.h></tt> and <tt>ncurses</tt>
1462 <chapt id="controlfields"><heading>Control files and their fields</heading>
1465 Many of the tools in the package management suite manipulate
1466 data represented in a common format, known as <em>control
1467 data</em>. The data is often stored in <em>control
1468 files</em>. Binary and source packages have control files,
1469 and the <file>.changes</file> files which control the installation
1470 of uploaded files are also in control file format.
1471 <prgn>dpkg</prgn>'s internal databases are in a similar
1475 <sect id="controlsyntax"><heading>Syntax of control files</heading>
1478 A control file consists of one or more paragraphs of fields.
1479 The paragraphs are separated by blank lines. Some control
1480 files allow only one paragraph; others allow several, in
1481 which case each paragraph usually refers to a different
1482 package. (For example, in source packages, the first
1483 paragraph refers to the source package, and later paragraphs
1484 refer to binary packages generated from the source.)
1488 Each paragraph consists of a series of data fields; each
1489 field consists of the field name, followed by a colon and
1490 then the data/value associated with that field. It ends at
1491 the end of the line. Horizontal whitespace (spaces and
1492 tabs) may occur immediately before or after the value and is
1493 ignored there; it is conventional to put a single space
1494 after the colon. For example, a field might be:
1495 <example compact="compact">
1498 the field name is <tt>Package</tt> and the field value
1503 Some fields' values may span several lines; in this case
1504 each continuation line <em>must</em> start with a space or
1505 tab. Any trailing spaces or tabs at the end of individual
1506 lines of a field value are ignored.
1510 Except where otherwise stated only a single line of data is
1511 allowed and whitespace is not significant in a field body.
1512 Whitespace must not appear inside names (of packages,
1513 architectures, files or anything else) or version numbers,
1514 or between the characters of multi-character version
1519 Field names are not case-sensitive, but it is usual to
1520 capitalize the field names using mixed case as shown below.
1524 Blank lines, or lines consisting only of spaces and tabs,
1525 are not allowed within field values or between fields - that
1526 would mean a new paragraph.
1531 <sect><heading>List of fields</heading>
1533 This list here is not supposed to be exhaustive. Most fields
1534 are dealt with elsewhere in this document.
1536 <sect1 id="f-Package"><heading><tt>Package</tt>
1540 The name of the binary package. Package names consist of
1541 lower case letters (<tt>a-z</tt>), digits (<tt>0-9</tt>),
1542 plus (<tt>+</tt>) and minus (<tt>-</tt>) signs, and
1543 periods (<tt>.</tt>).
1547 They must be at least two characters long and must start
1548 with an alphanumeric character. The use of lowercase
1549 package names is required unless the package you're
1550 building (or referring to, in other fields) is already
1551 using uppercase characters.</p>
1554 <sect1 id="f-Version"><heading><tt>Version</tt>
1558 This lists the source or binary package's version number -
1559 see <ref id="versions">.
1565 id="f-Standards-Version"><heading><tt>Standards-Version</tt>
1569 The most recent version of the standards (the policy
1570 manual and associated texts) with which the package
1571 complies. This is updated manually when editing the
1572 source package to conform to newer standards; it can
1573 sometimes be used to tell when a package needs attention.
1574 Its format is described above; see
1575 <ref id="standardsversion">.
1580 <sect1 id="f-Distribution"><heading><tt>Distribution</tt>
1584 In a <file>.changes</file> file or parsed changelog output
1585 this contains the (space-separated) name(s) of the
1586 distribution(s) where this version of the package should
1587 be installed. Valid distributions are determined by the
1588 archive maintainers.<footnote>
1589 Current distribution names are:
1590 <taglist compact="compact">
1591 <tag><em>stable</em></tag>
1594 This is the current "released" version of Debian
1595 GNU/Linux. Once the distribution is
1596 <em>stable</em> only security fixes and other
1597 major bug fixes are allowed. When changes are
1598 made to this distribution, the release number is
1599 increased (for example: 2.2r1 becomes 2.2r2 then
1604 <tag><em>unstable</em></tag>
1607 This distribution value refers to the
1608 <em>developmental</em> part of the Debian
1609 distribution tree. New packages, new upstream
1610 versions of packages and bug fixes go into the
1611 <em>unstable</em> directory tree. Download from
1612 this distribution at your own risk.
1616 <tag><em>testing</em></tag>
1619 This distribution value refers to the
1620 <em>testing</em> part of the Debian distribution
1621 tree. It receives its packages from the
1622 unstable distribution after a short time lag to
1623 ensure that there are no major issues with the
1624 unstable packages. It is less prone to breakage
1625 than unstable, but still risky. It is not
1626 possible to upload packages directly to
1631 <tag><em>frozen</em></tag>
1634 From time to time, the <em>testing</em>
1635 distribution enters a state of "code-freeze" in
1636 anticipation of release as a <em>stable</em>
1637 version. During this period of testing only
1638 fixes for existing or newly-discovered bugs will
1639 be allowed. The exact details of this stage are
1640 determined by the Release Manager.
1644 <tag><em>experimental</em></tag>
1647 The packages with this distribution value are
1648 deemed by their maintainers to be high
1649 risk. Oftentimes they represent early beta or
1650 developmental packages from various sources that
1651 the maintainers want people to try, but are not
1652 ready to be a part of the other parts of the
1653 Debian distribution tree. Download at your own
1659 You should list <em>all</em> distributions that the
1660 package should be installed into.
1669 <chapt id="versions"><heading>Version numbering</heading>
1672 Every package has a version number recorded in its
1673 <tt>Version</tt> control file field.
1677 The package management system imposes an ordering on version
1678 numbers, so that it can tell whether packages are being up- or
1679 downgraded and so that package system front end applications
1680 can tell whether a package it finds available is newer than
1681 the one installed on the system. The version number format
1682 has the most significant parts (as far as comparison is
1683 concerned) at the beginning.
1687 The version number format is:
1688 [<var>epoch</var><tt>:</tt>]<var>upstream_version</var>[<tt>-</tt><var>debian_revision</var>]
1692 The three components here are:
1694 <tag><var>epoch</var></tag>
1697 This is a single (generally small) unsigned integer. It
1698 may be omitted, in which case zero is assumed. If it is
1699 omitted then the <var>upstream_version</var> may not
1704 It is provided to allow mistakes in the version numbers
1705 of older versions of a package, and also a package's
1706 previous version numbering schemes, to be left behind.
1710 <tag><var>upstream_version</var></tag>
1713 This is the main part of the version number. It is
1714 usually the version number of the original ("upstream")
1715 package from which the <file>.deb</file> file has been made,
1716 if this is applicable. Usually this will be in the same
1717 format as that specified by the upstream author(s);
1718 however, it may need to be reformatted to fit into the
1719 package management system's format and comparison
1724 The comparison behavior of the package management system
1725 with respect to the <var>upstream_version</var> is
1726 described below. The <var>upstream_version</var>
1727 portion of the version number is mandatory.
1731 The <var>upstream_version</var> may contain only
1732 alphanumerics<footnote>
1733 <p>Alphanumerics are <tt>A-Za-z0-9</tt> only.</p>
1735 and the characters <tt>.</tt> <tt>+</tt> <tt>-</tt>
1736 <tt>:</tt> (full stop, plus, hyphen, colon) and should
1737 start with a digit. If there is no
1738 <var>debian_revision</var> then hyphens are not allowed;
1739 if there is no <var>epoch</var> then colons are not
1743 <tag><var>debian_revision</var></tag>
1746 This part of the version number specifies the version of
1747 the Debian package based on the upstream version. It
1748 may contain only alphanumerics and the characters
1749 <tt>+</tt> and <tt>.</tt> (plus and full stop) and is
1750 compared in the same way as the
1751 <var>upstream_version</var> is.
1755 It is optional; if it isn't present then the
1756 <var>upstream_version</var> may not contain a hyphen.
1757 This format represents the case where a piece of
1758 software was written specifically to be turned into a
1759 Debian package, and so there is only one "debianization"
1760 of it and therefore no revision indication is required.
1764 It is conventional to restart the
1765 <var>debian_revision</var> at <tt>1</tt> each time the
1766 <var>upstream_version</var> is increased.
1770 The package management system will break the version
1771 number apart at the last hyphen in the string (if there
1772 is one) to determine the <var>upstream_version</var> and
1773 <var>debian_revision</var>. The absence of a
1774 <var>debian_revision</var> compares earlier than the
1775 presence of one (but note that the
1776 <var>debian_revision</var> is the least significant part
1777 of the version number).
1784 The <var>upstream_version</var> and <var>debian_revision</var>
1785 parts are compared by the package management system using the
1790 The strings are compared from left to right.
1794 First the initial part of each string consisting entirely of
1795 non-digit characters is determined. These two parts (one of
1796 which may be empty) are compared lexically. If a difference
1797 is found it is returned. The lexical comparison is a
1798 comparison of ASCII values modified so that all the letters
1799 sort earlier than all the non-letters.
1803 Then the initial part of the remainder of each string which
1804 consists entirely of digit characters is determined. The
1805 numerical values of these two parts are compared, and any
1806 difference found is returned as the result of the comparison.
1807 For these purposes an empty string (which can only occur at
1808 the end of one or both version strings being compared) counts
1813 These two steps (comparing and removing initial non-digit
1814 strings and initial digit strings) are repeated until a
1815 difference is found or both strings are exhausted.
1819 Note that the purpose of epochs is to allow us to leave behind
1820 mistakes in version numbering, and to cope with situations
1821 where the version numbering scheme changes. It is
1822 <em>not</em> intended to cope with version numbers containing
1823 strings of letters which the package management system cannot
1824 interpret (such as <tt>ALPHA</tt> or <tt>pre-</tt>), or with
1825 silly orderings (the author of this manual has heard of a
1826 package whose versions went <tt>1.1</tt>, <tt>1.2</tt>,
1827 <tt>1.3</tt>, <tt>1</tt>, <tt>2.1</tt>, <tt>2.2</tt>,
1828 <tt>2</tt> and so forth).
1832 If an upstream package has problematic version numbers they
1833 should be converted to a sane form for use in the
1834 <tt>Version</tt> field.
1838 <heading>Version numbers based on dates</heading>
1840 In general, Debian packages should use the same version
1841 numbers as the upstream sources.</p>
1844 However, in some cases where the upstream version number is
1845 based on a date (e.g., a development "snapshot" release) the
1846 package management system cannot handle these version
1847 numbers without epochs. For example, dpkg will consider
1848 "96May01" to be greater than "96Dec24".</p>
1851 To prevent having to use epochs for every new upstream
1852 version, the version number should be changed to the
1853 following format in such cases: "19960501", "19961224". It
1854 is up to the maintainer whether he/she wants to bother the
1855 upstream maintainer to change the version numbers upstream,
1859 Note that other version formats based on dates which are
1860 parsed correctly by the package management system should
1861 <em>not</em> be changed.</p>
1864 Native Debian packages (i.e., packages which have been
1865 written especially for Debian) whose version numbers include
1866 dates should always use the "YYYYMMDD" format.</p>
1870 <chapt id="miscellaneous"><heading>Packaging Considerations</heading>
1872 <sect id="timestamps"><heading>Time Stamps</heading>
1874 Maintainers should preserve the modification times of the
1875 upstream source files in a package, as far as is reasonably
1878 The rationale is that there is some information conveyed
1879 by knowing the age of the file, for example, you could
1880 recognize that some documentation is very old by looking
1881 at the modification time, so it would be nice if the
1882 modification time of the upstream source would be
1889 <sect id="debianrules"><heading><file>debian/rules</file> - the
1890 main building script</heading>
1893 This file must be an executable makefile, and contains the
1894 package-specific recipes for compiling the package and
1895 building binary package(s) from the source.
1899 It must start with the line <tt>#!/usr/bin/make -f</tt>,
1900 so that it can be invoked by saying its name rather than
1901 invoking <prgn>make</prgn> explicitly.
1905 Since an interactive <file>debian/rules</file> script makes it
1906 impossible to auto-compile that package and also makes it
1907 hard for other people to reproduce the same binary
1908 package, all <em>required targets</em> MUST be
1909 non-interactive. At a minimum, required targets are the
1910 ones called by <prgn>dpkg-buildpackage</prgn>, namely,
1911 <em>clean</em>, <em>binary</em>, <em>binary-arch</em>,
1912 <em>binary-indep</em>, and <em>build</em>. It also follows
1913 that any target that these targets depend on must also be
1918 The required and optional targets are as follows:
1920 <tag><tt>build</tt>, <tt>build-arch</tt> (optional),
1921 <tt>build-indep</tt> (optional)</tag>
1924 The <tt>build</tt> target should perform all
1925 non-interactive configuration and compilation of the
1926 package. If a package has an interactive pre-build
1927 configuration routine, the Debianized source package
1928 must either be built after this has taken place (so
1929 that the binary package can be built without rerunning
1930 the configuration) or the configuration routine
1931 modified to become non-interactive. (The latter is
1932 preferable if there are architecture-specific features
1933 detected by the configuration routine.)
1937 For some packages, notably ones where the same
1938 source tree is compiled in different ways to produce
1939 two binary packages, the <tt>build</tt> target
1940 does not make much sense. For these packages it is
1941 good enough to provide two (or more) targets
1942 (<tt>build-a</tt> and <tt>build-b</tt> or whatever)
1943 for each of the ways of building the package, and a
1944 <tt>build</tt> target that does nothing. The
1945 <tt>binary</tt> target will have to build the
1946 package in each of the possible ways and make the
1947 binary package out of each.
1951 The <tt>build</tt> target must not do anything
1952 that might require root privilege.
1956 The <tt>build</tt> target may need to run the
1957 <tt>clean</tt> target first - see below.
1961 When a package has a configuration and build routine
1962 which takes a long time, or when the makefiles are
1963 poorly designed, or when <tt>build</tt> needs to
1964 run <tt>clean</tt> first, it is a good idea to
1965 <tt>touch build</tt> when the build process is
1966 complete. This will ensure that if <tt>debian/rules
1967 build</tt> is run again it will not rebuild the whole
1970 Another common way to do this is for <tt>build</tt>
1971 to depend on <prgn>build-stamp</prgn> and to do
1972 nothing else, and for the <prgn>build-stamp</prgn>
1973 target to do the building and to <tt>touch
1974 build-stamp</tt> on completion. This is
1975 especially useful if the build routine creates a
1976 file or directory called <tt>build</tt>; in such a
1977 case, <tt>build</tt> will need to be listed as
1978 a phony target (i.e., as a dependency of the
1979 <tt>.PHONY</tt> target). See the documentation of
1980 <prgn>make</prgn> for more information on phony
1987 <tag><tt>binary</tt>, <tt>binary-arch</tt>,
1988 <tt>binary-indep</tt>
1992 The <tt>binary</tt> target must be all that is
1993 necessary for the user to build the binary package(s)
1994 produced from this source package. All of these
1995 targets are required to be non-interactive. It is
1996 split into two parts: <prgn>binary-arch</prgn> builds
1997 the binary packages which are specific to a particular
1998 architecture, and <tt>binary-indep</tt> builds
1999 those which are not.
2002 <tt>binary</tt> may be (and commonly is) a target with
2003 no commands which simply depends on
2004 <tt>binary-arch</tt> and <tt>binary-indep</tt>.
2007 Both <tt>binary-*</tt> targets should depend on the
2008 <tt>build</tt> target, or on the appropriate
2009 <tt>build-arch</tt> or <tt>build-indep</tt> target, if
2010 provided, so that the package is built if it has not
2011 been already. It should then create the relevant
2012 binary package(s), using <prgn>dpkg-gencontrol</prgn> to
2013 make their control files and <prgn>dpkg-deb</prgn> to
2014 build them and place them in the parent of the top
2019 Both the <tt>binary-arch</tt> and
2020 <tt>binary-indep</tt> targets <em>must</em> exist.
2021 If one of them has nothing to do (which will always be
2022 the case if the source generates only a single binary
2023 package, whether architecture-dependent or not), it
2024 must still exist and must always succeed.
2028 The <tt>binary</tt> targets must be invoked as
2031 The <prgn>fakeroot</prgn> package often allows one
2032 to build a package correctly even without being
2039 <tag><tt>clean</tt></tag>
2042 This must undo any effects that the <tt>build</tt>
2043 and <tt>binary</tt> targets may have had, except
2044 that it should leave alone any output files created in
2045 the parent directory by a run of a <tt>binary</tt>
2046 target. This target must be non-interactive.
2050 If a <tt>build</tt> file is touched at the end of
2051 the <tt>build</tt> target, as suggested above, it
2052 should be removed as the first action that
2053 <tt>clean</tt> performs, so that running
2054 <tt>build</tt> again after an interrupted
2055 <tt>clean</tt> doesn't think that everything is
2060 The <tt>clean</tt> target may need to be
2061 invoked as root if <tt>binary</tt> has been
2062 invoked since the last <tt>clean</tt>, or if
2063 <tt>build</tt> has been invoked as root (since
2064 <tt>build</tt> may create directories, for
2069 <tag><tt>get-orig-source</tt> (optional)</tag>
2072 This target fetches the most recent version of the
2073 original source package from a canonical archive site
2074 (via FTP or WWW, for example), does any necessary
2075 rearrangement to turn it into the original source
2076 tar file format described below, and leaves it in the
2081 This target may be invoked in any directory, and
2082 should take care to clean up any temporary files it
2087 This target is optional, but providing it if
2088 possible is a good idea.
2094 The <tt>build</tt>, <tt>binary</tt> and
2095 <tt>clean</tt> targets must be invoked with the current
2096 directory being the package's top-level directory.
2101 Additional targets may exist in <file>debian/rules</file>,
2102 either as published or undocumented interfaces or for the
2103 package's internal use.
2107 The architectures we build on and build for are determined
2108 by <prgn>make</prgn> variables using the utility
2109 <prgn>dpkg-architecture</prgn>. You can determine the
2110 Debian architecture and the GNU style architecture
2111 specification string for the build machine (the machine type
2112 we are building on) as well as for the host machine (the
2113 machine type we are building for). Here is a list of
2114 supported <prgn>make</prgn> variables:
2115 <list compact="compact">
2117 <p><tt>DEB_*_ARCH</tt> (the Debian architecture)</p>
2120 <p><tt>DEB_*_GNU_TYPE</tt> (the GNU style architecture
2121 specification string)</p>
2124 <p><tt>DEB_*_GNU_CPU</tt> (the CPU part of
2125 <tt>DEB_*_GNU_TYPE</tt>)</p>
2128 <p><tt>DEB_*_GNU_SYSTEM</tt> (the System part of
2129 <tt>DEB_*_GNU_TYPE</tt>)</p>
2131 where <tt>*</tt> is either <tt>BUILD</tt> for specification of
2132 the build machine or <tt>HOST</tt> for specification of the
2137 Backward compatibility can be provided in the rules file
2138 by setting the needed variables to suitable default
2139 values; please refer to the documentation of
2140 <prgn>dpkg-architecture</prgn> for details.
2144 It is important to understand that the <tt>DEB_*_ARCH</tt>
2145 string only determines which Debian architecture we are
2146 building on or for. It should not be used to get the CPU
2147 or system information; the GNU style variables should be
2152 <sect id="dpkgchangelog"><heading><file>debian/changelog</file>
2156 This file records the changes to the Debian-specific parts of the
2159 Though there is nothing stopping an author who is also
2160 the Debian maintainer from using it for all their
2161 changes, it will have to be renamed if the Debian and
2162 upstream maintainers become different people. In such a
2163 case, however, it might be better to maintain the
2164 package as a non-native package.
2170 It has a special format which allows the package building
2171 tools to discover which version of the package is being
2172 built and find out other release-specific information.
2176 That format is a series of entries like this:
2177 <example compact="compact">
2178 <var>package</var> (<var>version</var>) <var>distribution(s)</var>; urgency=<var>urgency</var>
2180 <p>[optional blank line(s), stripped]</p>
2182 * <var>change details</var>
2183 <var>more change details</var>
2185 <p>[blank line(s), included in output of dpkg-parsechangelog]</p>
2187 * <var>even more change details</var>
2189 <p>[optional blank line(s), stripped]</p>
2191 -- <var>maintainer name</var> <<var>email
2192 address</var>><var>[two spaces]</var> <var>date</var>
2197 <var>package</var> and <var>version</var> are the source
2198 package name and version number.
2202 <var>distribution(s)</var> lists the distributions where
2203 this version should be installed when it is uploaded - it
2204 is copied to the <tt>Distribution</tt> field in the
2205 <file>.changes</file> file. See <ref id="f-Distribution">.
2209 <var>urgency</var> is the value for the <tt>Urgency</tt>
2210 field in the <file>.changes</file> file for the upload. It is
2211 not possible to specify an urgency containing commas; commas
2212 are used to separate
2213 <tt><var>keyword</var>=<var>value</var></tt> settings in the
2214 <prgn>dpkg</prgn> changelog format (though there is
2215 currently only one useful <var>keyword</var>,
2216 <tt>urgency</tt>).<footnote>
2218 Recognised urgency values are <tt>low</tt>,
2219 <tt>medium</tt>, <tt>high</tt> and <tt>emergency</tt>.
2220 They have an effect on how quickly a package will be
2221 considered for inclusion into the <tt>testing</tt>
2222 distribution, and give an indication of the importance
2223 of any fixes included in this upload.
2229 The change details may in fact be any series of lines
2230 starting with at least two spaces, but conventionally each
2231 change starts with an asterisk and a separating space and
2232 continuation lines are indented so as to bring them in
2233 line with the start of the text above. Blank lines may be
2234 used here to separate groups of changes, if desired.
2238 If this upload resolves bugs recorded in the Bug Tracking
2239 System (BTS), they may be automatically closed on the
2240 inclusion of this package into the Debian archive by
2241 including the string: <tt>closes: Bug#<var>nnnnn</var></tt>
2242 in the change details.<footnote>
2244 To be precise, the string should match the following
2245 Perl regular expression:
2247 /closes:\s*(?:bug)?\#?\s?\d+(?:,\s*(?:bug)?\#?\s?\d+)*/i
2249 Then all of the bug numbers listed will be closed by the
2250 archive maintenance script (<prgn>katie</prgn>), or in
2251 the case of an NMU, marked as fixed.
2257 The maintainer name and email address used in the changelog
2258 should be the details of the person uploading <em>this</em>
2259 version. They are <em>not</em> necessarily those of the
2260 usual package maintainer. The information here will be
2261 copied to the <tt>Changed-By</tt> field in the
2262 <tt>.changes</tt> file, and then later used to send an
2263 acknowledgement when the upload has been installed.
2267 The <var>date</var> should be in RFC822 format<footnote>
2269 This is generated by the <prgn>822-date</prgn>
2272 </footnote>; it should include the time zone specified
2273 numerically, with the time zone name or abbreviation
2274 optionally present as a comment in parentheses.
2278 The first "title" line with the package name should start
2279 at the left hand margin; the "trailer" line with the
2280 maintainer and date details should be preceded by exactly
2281 one space. The maintainer details and the date must be
2282 separated by exactly two spaces.
2285 <sect1><heading>Defining alternative changelog formats</heading>
2288 It is possible to use a different format to the standard
2289 one, by providing a parser for the format you wish to
2293 A changelog parser must not interact with the user at
2299 <!-- FIXME: section pkg-srcsubstvars is the same as srcsubstvars -->
2301 <sect id="srcsubstvars"><heading><file>debian/substvars</file>
2302 and variable substitutions </heading>
2305 When <prgn>dpkg-gencontrol</prgn>,
2306 <prgn>dpkg-genchanges</prgn> and <prgn>dpkg-source</prgn>
2307 generate control files they perform variable substitutions
2308 on their output just before writing it. Variable
2309 substitutions have the form <tt>${<var>variable</var>}</tt>.
2310 The optional file <file>debian/substvars</file> contains
2311 variable substitutions to be used; variables can also be set
2312 directly from <file>debian/rules</file> using the <tt>-V</tt>
2313 option to the source packaging commands, and certain
2314 predefined variables are also available.
2318 The <file>debian/substvars</file> file is usually generated and
2319 modified dynamically by <file>debian/rules</file> targets, in
2320 which case it must be removed by the <tt>clean</tt> target.
2324 See <manref name="dpkg-source" section="1"> for full
2325 details about source variable substitutions, including the
2326 format of <file>debian/substvars</file>.</p>
2329 <sect id="debianfiles"><heading><file>debian/files</file>
2333 This file is not a permanent part of the source tree; it
2334 is used while building packages to record which files are
2335 being generated. <prgn>dpkg-genchanges</prgn> uses it
2336 when it generates a <file>.changes</file> file.
2340 It should not exist in a shipped source package, and so it
2341 (and any backup files or temporary files such as
2342 <file>files.new</file><footnote>
2344 <file>files.new</file> is used as a temporary file by
2345 <prgn>dpkg-gencontrol</prgn> and
2346 <prgn>dpkg-distaddfile</prgn> - they write a new
2347 version of <tt>files</tt> here before renaming it,
2348 to avoid leaving a corrupted copy if an error
2351 </footnote>) should be removed by the
2352 <tt>clean</tt> target. It may also be wise to
2353 ensure a fresh start by emptying or removing it at the
2354 start of the <tt>binary</tt> target.
2358 When <prgn>dpkg-gencontrol</prgn> is run for a binary
2359 package, it adds an entry to <file>debian/files</file> for the
2360 <file>.deb</file> file that will be created when <tt>dpkg-deb
2361 --build</tt> is run for that binary package. So for most
2362 packages all that needs to be done with this file is to
2363 delete it in the <tt>clean</tt> target.
2367 If a package upload includes files besides the source
2368 package and any binary packages whose control files were
2369 made with <prgn>dpkg-gencontrol</prgn> then they should be
2370 placed in the parent of the package's top-level directory
2371 and <prgn>dpkg-distaddfile</prgn> should be called to add
2372 the file to the list in <file>debian/files</file>.</p>
2375 <sect id="restrictions"><heading>Restrictions on objects in source packages
2379 The source package may not contain any hard links<footnote>
2381 This is not currently detected when building source
2382 packages, but only when extracting
2386 Hard links may be permitted at some point in the
2387 future, but would require a fair amount of
2390 </footnote>, device special files, sockets or setuid or
2391 setgid files.<footnote>
2393 Setgid directories are allowed.
2399 <sect id="descriptions"><heading>Descriptions of packages - the
2400 <tt>Description</tt> field</heading>
2403 The "Description" control file field consists of two parts,
2404 the synopsis or the short description, and the long description.
2405 The field's format is as follows:
2409 Description: <single line synopsis>
2410 <extended description over several lines>
2414 The description is intended to describe the program to a user
2415 who has never met it before so that they know whether they
2416 want to install it. It should also give information about the
2417 significant dependencies and conflicts between this package
2418 and others, so that the user knows why these dependencies and
2419 conflicts have been declared.
2423 Put important information first, both in the synopsis and
2424 extended description. Sometimes only the first part of the
2425 synopsis or of the description will be displayed. You can
2426 assume that there will usually be a way to see the whole
2427 extended description.
2430 <sect1 id="synopsis"><heading>The single line synopsis</heading>
2433 The single line synopsis should be kept brief - certainly
2434 under 80 characters.
2438 Do not include the package name in the synopsis line. The
2439 display software knows how to display this already, and you
2440 do not need to state it. Remember that in many situations
2441 the user may only see the synopsis line - make it as
2442 informative as you can.
2447 <sect1 id="extendeddesc"><heading>The extended description</heading>
2450 Do not try to continue the single line synopsis into the
2451 extended description. This will not work correctly when
2452 the full description is displayed, and makes no sense
2453 where only the summary (the single line synopsis) is
2458 The extended description should describe what the package
2459 does and how it relates to the rest of the system (in terms
2460 of, for example, which subsystem it is which part of).
2464 The description field needs to make sense to anyone, even
2465 people who have no idea about any of the things the
2466 package deals with.<footnote>
2467 The blurb that comes with a program in its
2468 announcements and/or <prgn>README</prgn> files is
2469 rarely suitable for use in a description. It is
2470 usually aimed at people who are already in the
2471 community where the package is used.
2476 The lines in the extended description can have these formats:
2482 Those starting with a single space are part of a paragraph.
2483 Successive lines of this form will be word-wrapped when
2484 displayed. The leading space will usually be stripped off.
2488 Those starting with two or more spaces. These will be
2489 displayed verbatim. If the display cannot be panned
2490 horizontally, the displaying program will linewrap them "hard"
2491 (i.e., without taking account of word breaks). If it can they
2492 will be allowed to trail off to the right. None, one or two
2493 initial spaces may be deleted, but the number of spaces
2494 deleted from each line will be the same (so that you can have
2495 indenting work correctly, for example).
2499 Those containing a single space followed by a single full stop
2500 character. These are rendered as blank lines. This is the
2501 <em>only</em> way to get a blank line<footnote>
2502 Completely empty lines will not be rendered as blank lines.
2503 Instead, they will cause the parser to think you're starting
2504 a whole new record in the control file, and will therefore
2505 likely abort with an error.
2510 Those containing a space, a full stop and some more characters.
2511 These are for future expansion. Do not use them.
2517 Do not use tab characters. Their effect is not predictable.
2527 <chapt id="maintainerscripts"><heading>Package maintainer scripts
2528 and installation procedure
2531 <sect><heading>Introduction to package maintainer scripts
2535 It is possible to supply scripts as part of a package which
2536 the package management system will run for you when your
2537 package is installed, upgraded or removed.
2541 These scripts are the files <prgn>preinst</prgn>,
2542 <prgn>postinst</prgn>, <prgn>prerm</prgn> and <prgn>postrm</prgn> in the
2543 control area of the package. They must be proper executable
2544 files; if they are scripts (which is recommended), they must
2545 start with the usual <tt>#!</tt> convention. They should be
2546 readable and executable by anyone, and not world-writable.
2550 The package management system looks at the exit status from
2551 these scripts. It is important that they exit with a
2552 non-zero status if there is an error, so that the package
2553 management system can stop its processing. For shell
2554 scripts this means that you <em>almost always</em> need to
2555 use <tt>set -e</tt> (this is usually true when writing shell
2556 scripts, in fact). It is also important, of course, that
2557 they don't exit with a non-zero status if everything went
2562 When a package is upgraded a combination of the scripts from
2563 the old and new packages is called during the upgrade
2564 procedure. If your scripts are going to be at all
2565 complicated you need to be aware of this, and may need to
2566 check the arguments to your scripts.
2570 Broadly speaking the <prgn>preinst</prgn> is called before
2571 (a particular version of) a package is installed, and the
2572 <prgn>postinst</prgn> afterwards; the <prgn>prerm</prgn>
2573 before (a version of) a package is removed and the
2574 <prgn>postrm</prgn> afterwards.
2578 Programs called from maintainer scripts should not normally
2579 have a path prepended to them. Before installation is
2580 started, the package management system checks to see if the
2581 programs <prgn>ldconfig</prgn>,
2582 <prgn>start-stop-daemon</prgn>, <prgn>install-info</prgn>,
2583 and <prgn>update-rc.d</prgn> can be found via the
2584 <tt>PATH</tt> environment variable. Those programs, and any
2585 other program that one would expect to be on the
2586 <tt>PATH</tt>, should thus be invoked without an absolute
2587 pathname. Maintainer scripts should also not reset the
2588 <tt>PATH</tt>, though they might choose to modify it by
2589 prepending or appending package-specific directories. These
2590 considerations really apply to all shell scripts.</p>
2594 <heading>Maintainer scripts Idempotency</heading>
2597 It is necessary for the error recovery procedures that the
2598 scripts be idempotent. This means that if it is run
2599 successfully, and then it is called again, it doesn't bomb
2600 out or cause any harm, but just ensures that everything is
2601 the way it ought to be. If the first call failed, or
2602 aborted half way through for some reason, the second call
2603 should merely do the things that were left undone the first
2604 time, if any, and exit with a success status if everything
2607 This is so that if an error occurs, the user interrupts
2608 <prgn>dpkg</prgn> or some other unforeseen circumstance
2609 happens you don't leave the user with a badly-broken
2610 package when <prgn>dpkg</prgn> attempts to repeat the
2618 <heading>Controlling terminal for maintainer scripts</heading>
2621 The maintainer scripts are guaranteed to run with a
2622 controlling terminal and can interact with the user.
2623 If they need to prompt for passwords, do full-screen
2624 interaction or something similar you should do these
2625 things to and from <file>/dev/tty</file>, since
2626 <prgn>dpkg</prgn> will at some point redirect scripts'
2627 standard input and output so that it can log the
2628 installation process. Likewise, because these scripts
2629 may be executed with standard output redirected into a
2630 pipe for logging purposes, Perl scripts should set
2631 unbuffered output by setting <tt>$|=1</tt> so that the
2632 output is printed immediately rather than being
2637 Each script should return a zero exit status for
2638 success, or a nonzero one for failure.
2642 <sect id="mscriptsinstact"><heading>Summary of ways maintainer
2647 <list compact="compact">
2649 <p><var>new-preinst</var> <tt>install</tt></p>
2652 <p><var>new-preinst</var> <tt>install</tt>
2653 <var>old-version</var></p>
2656 <p><var>new-preinst</var> <tt>upgrade</tt>
2657 <var>old-version</var></p>
2660 <p><var>old-preinst</var> <tt>abort-upgrade</tt>
2661 <var>new-version</var>
2667 <list compact="compact">
2669 <p><var>postinst</var> <tt>configure</tt>
2670 <var>most-recently-configured-version</var></p>
2673 <p><var>old-postinst</var> <tt>abort-upgrade</tt>
2674 <var>new-version</var></p>
2677 <p><var>conflictor's-postinst</var> <tt>abort-remove</tt>
2678 <tt>in-favour</tt> <var>package</var>
2679 <var>new-version</var></p>
2683 <var>deconfigured's-postinst</var>
2684 <tt>abort-deconfigure</tt> <tt>in-favour</tt>
2685 <var>failed-install-package</var> <var>version</var>
2686 <tt>removing</tt> <var>conflicting-package</var>
2693 <list compact="compact">
2695 <p><var>prerm</var> <tt>remove</tt></p>
2698 <p><var>old-prerm</var> <tt>upgrade</tt>
2699 <var>new-version</var></p>
2702 <p><var>new-prerm</var> <tt>failed-upgrade</tt>
2703 <var>old-version</var></p>
2706 <p><var>conflictor's-prerm</var> <tt>remove</tt>
2707 <tt>in-favour</tt> <var>package</var>
2708 <var>new-version</var></p>
2712 <var>deconfigured's-prerm</var> <tt>deconfigure</tt>
2713 <tt>in-favour</tt> <var>package-being-installed</var>
2714 <var>version</var> <tt>removing</tt>
2715 <var>conflicting-package</var>
2722 <list compact="compact">
2724 <p><var>postrm</var> <tt>remove</tt></p>
2727 <p><var>postrm</var> <tt>purge</tt></p>
2731 <var>old-postrm</var> <tt>upgrade</tt>
2732 <var>new-version</var></p>
2735 <p><var>new-postrm</var> <tt>failed-upgrade</tt>
2736 <var>old-version</var></p>
2739 <p><var>new-postrm</var> <tt>abort-install</tt></p>
2742 <p><var>new-postrm</var> <tt>abort-install</tt>
2743 <var>old-version</var></p>
2746 <p><var>new-postrm</var> <tt>abort-upgrade</tt>
2747 <var>old-version</var></p>
2751 <var>disappearer's-postrm</var> <tt>disappear</tt>
2752 <var>overwriter</var>
2753 <var>overwriter-version</var></p></item>
2758 <sect id="unpackphase"><heading>Details of unpack phase of
2759 installation or upgrade
2763 The procedure on installation/upgrade/overwrite/disappear
2764 (i.e., when running <tt>dpkg --unpack</tt>, or the unpack
2765 stage of <tt>dpkg --install</tt>) is as follows. In each
2766 case, if a major error occurs (unless listed below) the
2767 actions are, in general, run backwards - this means that the
2768 maintainer scripts are run with different arguments in
2769 reverse order. These are the "error unwind" calls listed
2777 <p>If a version of the package is already
2779 <example compact="compact">
2780 <var>old-prerm</var> upgrade <var>new-version</var>
2785 If the script runs but exits with a non-zero
2786 exit status, <prgn>dpkg</prgn> will attempt:
2787 <example compact="compact">
2788 <var>new-prerm</var> failed-upgrade <var>old-version</var>
2790 Error unwind, for both the above cases:
2791 <example compact="compact">
2792 <var>old-postinst</var> abort-upgrade <var>new-version</var>
2800 <p>If a "conflicting" package is being removed at the same time:
2804 If any packages depended on that conflicting
2805 package and <tt>--auto-deconfigure</tt> is
2806 specified, call, for each such package:
2807 <example compact="compact">
2808 <var>deconfigured's-prerm</var> deconfigure \
2809 in-favour <var>package-being-installed</var> <var>version</var> \
2810 removing <var>conflicting-package</var> <var>version</var>
2813 <example compact="compact">
2814 <var>deconfigured's-postinst</var> abort-deconfigure \
2815 in-favour <var>package-being-installed-but-failed</var> <var>version</var> \
2816 removing <var>conflicting-package</var> <var>version</var>
2818 The deconfigured packages are marked as
2819 requiring configuration, so that if
2820 <tt>--install</tt> is used they will be
2821 configured again if possible.</p>
2824 <p>To prepare for removal of the conflicting package, call:
2825 <example compact="compact">
2826 <var>conflictor's-prerm</var> remove \
2827 in-favour <var>package</var> <var>new-version</var>
2830 <example compact="compact">
2831 <var>conflictor's-postinst</var> abort-remove \
2832 in-favour <var>package</var> <var>new-version</var>
2843 <p>If the package is being upgraded, call:
2844 <example compact="compact">
2845 <var>new-preinst</var> upgrade <var>old-version</var>
2850 Otherwise, if the package had some configuration
2851 files from a previous version installed (i.e., it
2852 is in the "configuration files only" state):
2853 <example compact="compact">
2854 <var>new-preinst</var> install <var>old-version</var>
2858 <p>Otherwise (i.e., the package was completely purged):
2859 <example compact="compact">
2860 <var>new-preinst</var> install
2862 Error unwind actions, respectively:
2863 <example compact="compact">
2864 <var>new-postrm</var> abort-upgrade <var>old-version</var>
2865 <var>new-postrm</var> abort-install <var>old-version</var>
2866 <var>new-postrm</var> abort-install
2875 The new package's files are unpacked, overwriting any
2876 that may be on the system already, for example any
2877 from the old version of the same package or from
2878 another package. Backups of the old files are kept
2879 temporarily, and if anything goes wrong the package
2880 management system will attempt to put them back as
2881 part of the error unwind.
2885 It is an error for a package to contains files which
2886 are on the system in another package, unless
2887 <tt>Replaces</tt> is used (see <ref id="replaces">).
2889 The following paragraph is not currently the case:
2890 Currently the <tt>- - force-overwrite</tt> flag is
2891 enabled, downgrading it to a warning, but this may not
2897 It is a more serious error for a package to contain a
2898 plain file or other kind of non-directory where another
2899 package has a directory (again, unless
2900 <tt>Replaces</tt> is used). This error can be
2901 overridden if desired using
2902 <tt>--force-overwrite-dir</tt>, but this is not
2907 Packages which overwrite each other's files produce
2908 behavior which, though deterministic, is hard for the
2909 system administrator to understand. It can easily
2910 lead to "missing" programs if, for example, a package
2911 is installed which overwrites a file from another
2912 package, and is then removed again.<footnote>
2914 Part of the problem is due to what is arguably a
2915 bug in <prgn>dpkg</prgn>.
2921 A directory will never be replaced by a symbolic link
2922 to a directory or vice versa; instead, the existing
2923 state (symlink or not) will be left alone and
2924 <prgn>dpkg</prgn> will follow the symlink if there is
2932 <p>If the package is being upgraded, call
2933 <example compact="compact">
2934 <var>old-postrm</var> upgrade <var>new-version</var>
2939 <p>If this fails, <prgn>dpkg</prgn> will attempt:
2940 <example compact="compact">
2941 <var>new-postrm</var> failed-upgrade <var>old-version</var>
2943 Error unwind, for both cases:
2944 <example compact="compact">
2945 <var>old-preinst</var> abort-upgrade <var>new-version</var>
2952 This is the point of no return - if
2953 <prgn>dpkg</prgn> gets this far, it won't back off
2954 past this point if an error occurs. This will
2955 leave the package in a fairly bad state, which
2956 will require a successful re-installation to clear
2957 up, but it's when <prgn>dpkg</prgn> starts doing
2958 things that are irreversible.
2963 Any files which were in the old version of the package
2964 but not in the new are removed.</p>
2967 <p>The new file list replaces the old.</p>
2970 <p>The new maintainer scripts replace the old.</p>
2974 <p>Any packages all of whose files have been overwritten during the
2975 installation, and which aren't required for
2976 dependencies, are considered to have been removed.
2977 For each such package
2980 <p><prgn>dpkg</prgn> calls:
2981 <example compact="compact">
2982 <var>disappearer's-postrm</var> disappear \
2983 <var>overwriter</var> <var>overwriter-version</var>
2988 <p>The package's maintainer scripts are removed.
2993 It is noted in the status database as being in a
2994 sane state, namely not installed (any conffiles
2995 it may have are ignored, rather than being
2996 removed by <prgn>dpkg</prgn>). Note that
2997 disappearing packages do not have their prerm
2998 called, because <prgn>dpkg</prgn> doesn't know
2999 in advance that the package is going to
3008 Any files in the package we're unpacking that are also
3009 listed in the file lists of other packages are removed
3010 from those lists. (This will lobotomize the file list
3011 of the "conflicting" package if there is one.)
3016 The backup files made during installation, above, are
3023 The new package's status is now sane, and recorded as
3028 Here is another point of no return - if the
3029 conflicting package's removal fails we do not unwind
3030 the rest of the installation; the conflicting package
3031 is left in a half-removed limbo.
3037 If there was a conflicting package we go and do the
3038 removal actions (described below), starting with the
3039 removal of the conflicting package's files (any that
3040 are also in the package being installed have already
3041 been removed from the conflicting package's file list,
3042 and so do not get removed now).
3049 <sect id="configdetails"><heading>Details of configuration</heading>
3052 When we configure a package (this happens with <tt>dpkg
3053 --install</tt> and <tt>dpkg --configure</tt>), we first
3054 update any <tt>conffile</tt>s and then call:
3055 <example compact="compact">
3056 <var>postinst</var> configure <var>most-recently-configured-version</var>
3061 No attempt is made to unwind after errors during
3066 If there is no most recently configured version
3067 <prgn>dpkg</prgn> will pass a null argument; older versions
3068 of dpkg may pass <tt><unknown></tt> (including the
3069 angle brackets) in this case. Even older ones do not pass a
3070 second argument at all, under any circumstances.
3074 <sect id="removedetails"><heading>Details of removal and/or
3075 configuration purging</heading>
3081 <example compact="compact">
3082 <var>prerm</var> remove
3088 The package's files are removed (except <tt>conffile</tt>s).
3093 <example compact="compact">
3094 <var>postrm</var> remove
3100 All the maintainer scripts except the <prgn>postrm</prgn>
3105 If we aren't purging the package we stop here. Note
3106 that packages which have no <prgn>postrm</prgn> and no
3107 <tt>conffile</tt>s are automatically purged when
3108 removed, as there is no difference except for the
3109 <prgn>dpkg</prgn> status.</p>
3113 The <tt>conffile</tt>s and any backup files
3114 (<tt>~</tt>-files, <tt>#*#</tt> files,
3115 <tt>%</tt>-files, <tt>.dpkg-{old,new,tmp}</tt>, etc.)
3120 <example compact="compact">
3121 <var>postrm</var> purge
3126 <p>The package's file list is removed.</p>
3129 No attempt is made to unwind after errors during
3136 <chapt id="relationships"><heading>Declaring relationships between
3139 <sect id="depsyntax"><heading>Syntax of relationship fields
3143 These fields all have a uniform syntax. They are a list of
3144 package names separated by commas.
3148 In the <tt>Depends</tt>, <tt>Recommends</tt>,
3149 <tt>Suggests</tt>, <tt>Pre-Depends</tt>,
3150 <tt>Build-Depends</tt> and <tt>Build-Depends-Indep</tt>
3151 control file fields of the package, which declare
3152 dependencies on other packages, the package names listed may
3153 also include lists of alternative package names, separated
3154 by vertical bar (pipe) symbols <tt>|</tt>. In such a case,
3155 if any one of the alternative packages is installed, that
3156 part of the dependency is considered to be satisfied.
3160 All of the fields except for <tt>Provides</tt> may restrict
3161 their applicability to particular versions of each named
3162 package. This is done in parentheses after each individual
3163 package name; the parentheses should contain a relation from
3164 the list below followed by a version number, in the format
3165 described in <ref id="versions">.
3169 The relations allowed are <tt><<</tt>, <tt><=</tt>,
3170 <tt>=</tt>, <tt>>=</tt> and <tt>>></tt> for
3171 strictly earlier, earlier or equal, exactly equal, later or
3172 equal and strictly later, respectively. The deprecated
3173 forms <tt><</tt> and <tt>></tt> were used to mean
3174 earlier/later or equal, rather than strictly earlier/later,
3175 so they should not appear in new packages (though
3176 <prgn>dpkg</prgn> still supports them).
3180 Whitespace may appear at any point in the version
3181 specification subject to the rules in <ref
3182 id="controlsyntax">, and must appear where it's necessary to
3183 disambiguate; it is not otherwise significant. For
3184 consistency and in case of future changes to
3185 <prgn>dpkg</prgn> it is recommended that a single space be
3186 used after a version relationship and before a version
3187 number; it is also conventional to put a single space after
3188 each comma, on either side of each vertical bar, and before
3189 each open parenthesis.
3193 For example, a list of dependencies might appear as:
3194 <example compact="compact">
3197 Depends: libc6 (>= 2.2.1), exim | mail-transport-agent
3202 All fields that specify build-time relationships
3203 (<tt>Build-Depends</tt>, <tt>Build-Depends-Indep</tt>,
3204 <tt>Build-Conflicts</tt> and <tt>Build-Conflicts-Indep</tt>)
3205 may be restricted to a certain set of architectures. This
3206 is indicated in brackets after each individual package name and
3207 the optional version specification. The brackets enclose a
3208 list of Debian architecture names separated by whitespace.
3209 Exclamation marks may be prepended to each of the names.
3210 (It is not permitted for some names to be prepended with
3211 exclamation marks and others not.) If the current Debian
3212 host architecture is not in this list and there are no
3213 exclamation marks in the list, or it is in the list with a
3214 prepended exclamation mark, the package name and the
3215 associated version specification are ignored completely for
3216 the purposes of defining the relationships.
3221 <example compact="compact">
3223 Build-Depends-Indep: texinfo
3224 Build-Depends: kernel-headers-2.2.10 [!hurd-i386],
3225 hurd-dev [hurd-i386], gnumach-dev [hurd-i386]
3230 Note that the binary package relationship fields such as
3231 <tt>Depends</tt> appear in one of the binary package
3232 sections of the control file, whereas the build-time
3233 relationships such as <tt>Build-Depends</tt> appear in the
3234 source package section of the control file (which is the
3240 <heading>Binary Dependencies - <tt>Depends</tt>,
3241 <tt>Recommends</tt>, <tt>Suggests</tt>, <tt>Enhances</tt>,
3242 <tt>Pre-Depends</tt>
3246 Packages can declare in their control file that they have
3247 certain relationships to other packages - for example, that
3248 they may not be installed at the same time as certain other
3249 packages, and/or that they depend on the presence of others.
3253 This is done using the <tt>Depends</tt>, <tt>Pre-Depends</tt>,
3254 <tt>Recommends</tt>, <tt>Suggests</tt>, <tt>Enhances</tt> and
3255 <tt>Conflicts</tt> control file fields.
3259 These six fields are used to declare a dependency
3260 relationship by one package on another. Except for
3261 <tt>Enhances</tt>, they appear in the depending (binary)
3262 package's control file. (<tt>Enhances</tt> appears in the
3263 recommending package's control file.)
3267 A <tt>Depends</tt> field takes effect <em>only</em> when a
3268 package is to be configured. It does not prevent a package
3269 being on the system in an unconfigured state while its
3270 dependencies are unsatisfied, and it is possible to replace
3271 a package whose dependencies are satisfied and which is
3272 properly installed with a different version whose
3273 dependencies are not and cannot be satisfied; when this is
3274 done the depending package will be left unconfigured (since
3275 attempts to configure it will give errors) and will not
3276 function properly. If it is necessary, a
3277 <tt>Pre-Depends</tt> field can be used, which has a partial
3278 effect even when a package is being unpacked, as explained
3279 in detail below. (The other three dependency fields,
3280 <tt>Recommends</tt>, <tt>Suggests</tt> and
3281 <tt>Enhances</tt>, are only used by the various front-ends
3282 to <prgn>dpkg</prgn> such as <prgn>dselect</prgn>.)
3286 For this reason packages in an installation run are usually
3287 all unpacked first and all configured later; this gives
3288 later versions of packages with dependencies on later
3289 versions of other packages the opportunity to have their
3290 dependencies satisfied.
3294 The <tt>Depends</tt> field thus allows package maintainers
3295 to impose an order in which packages should be configured.
3299 The meaning of the five dependency fields is as follows:
3301 <tag><tt>Depends</tt></tag>
3304 This declares an absolute dependency. A package will
3305 not be configured unless all of the packages listed in
3306 its <tt>Depends</tt> field have been correctly
3311 The <tt>Depends</tt> field should be used if the
3312 depended-on package is required for the depending
3313 package to provide a significant amount of
3317 The <tt>Depends</tt> field should also be used if the
3318 <prgn>postinst</prgn>, <prgn>prerm</prgn> or
3319 <prgn>postrm</prgn> scripts require the package to be
3320 present in order to run. Note, however, that the
3321 <prgn>postrm</prgn> cannot rely on any non-essential
3322 packages to be present during the <tt>purge</tt>
3326 <tag><tt>Recommends</tt></tag>
3328 <p>This declares a strong, but not absolute, dependency.
3332 The <tt>Recommends</tt> field should list packages
3333 that would be found together with this one in all but
3334 unusual installations.</p>
3337 <tag><tt>Suggests</tt></tag>
3340 This is used to declare that one package may be more
3341 useful with one or more others. Using this field
3342 tells the packaging system and the user that the
3343 listed packages are related to this one and can
3344 perhaps enhance its usefulness, but that installing
3345 this one without them is perfectly reasonable.
3349 <tag><tt>Enhances</tt></tag>
3352 This field is similar to Suggests but works in the
3353 opposite direction. It is used to declare that a
3354 package can enhance the functionality of another
3359 <tag><tt>Pre-Depends</tt></tag>
3362 This field is like <tt>Depends</tt>, except that it
3363 also forces <prgn>dpkg</prgn> to complete installation
3364 of the packages named before even starting the
3365 installation of the package which declares the
3366 pre-dependency, as follows:
3370 When a package declaring a pre-dependency is about to
3371 be <em>unpacked</em> the pre-dependency can be
3372 satisfied if the depended-on package is either fully
3373 configured, <em>or even if</em> the depended-on
3374 package(s) are only unpacked or half-configured,
3375 provided that they have been configured correctly at
3376 some point in the past (and not removed or partially
3377 removed since). In this case, both the
3378 previously-configured and currently unpacked or
3379 half-configured versions must satisfy any version
3380 clause in the <tt>Pre-Depends</tt> field.
3384 When the package declaring a pre-dependency is about
3385 to be <em>configured</em>, the pre-dependency will be
3386 treated as a normal <tt>Depends</tt>, that is, it will
3387 be considered satisfied only if the depended-on
3388 package has been correctly configured.
3392 <tt>Pre-Depends</tt> should be used sparingly,
3393 preferably only by packages whose premature upgrade or
3394 installation would hamper the ability of the system to
3395 continue with any upgrade that might be in progress.
3399 <tt>Pre-Depends</tt> are also required if the
3400 <prgn>preinst</prgn> script depends on the named
3401 package. It is best to avoid this situation if
3407 When selecting which level of dependency to use you should
3408 consider how important the depended-on package is to the
3409 functionality of the one declaring the dependency. Some
3410 packages are composed of components of varying degrees of
3411 importance. Such a package should list using
3412 <tt>Depends</tt> the package(s) which are required by the
3413 more important components. The other components'
3414 requirements may be mentioned as Suggestions or
3415 Recommendations, as appropriate to the components' relative
3420 <sect id="conflicts"><heading>Conflicting binary packages -
3421 <tt>Conflicts</tt></heading>
3424 When one binary package declares a conflict with another
3425 using a <tt>Conflicts</tt> field, <prgn>dpkg</prgn> will
3426 refuse to allow them to be installed on the system at the
3431 If one package is to be installed, the other must be removed
3432 first - if the package being installed is marked as
3433 replacing (see <ref id="replaces">) the one on the system,
3434 or the one on the system is marked as deselected, or both
3435 packages are marked <tt>Essential</tt>, then
3436 <prgn>dpkg</prgn> will automatically remove the package
3437 which is causing the conflict, otherwise it will halt the
3438 installation of the new package with an error. This
3439 mechanism is specifically designed to produce an error when
3440 the installed package is <tt>Essential</tt>, but the new
3445 A package will not cause a conflict merely because its
3446 configuration files are still installed; it must be at least
3451 A special exception is made for packages which declare a
3452 conflict with their own package name, or with a virtual
3453 package which they provide (see below): this does not
3454 prevent their installation, and allows a package to conflict
3455 with others providing a replacement for it. You use this
3456 feature when you want the package in question to be the only
3457 package providing some feature.
3461 A <tt>Conflicts</tt> entry should almost never have an
3462 "earlier than" version clause. This would prevent
3463 <prgn>dpkg</prgn> from upgrading or installing the package
3464 which declared such a conflict until the upgrade or removal
3465 of the conflicted-with package had been completed.
3469 <sect id="virtual"><heading>Virtual packages - <tt>Provides</tt>
3473 As well as the names of actual ("concrete") packages, the
3474 package relationship fields <tt>Depends</tt>,
3475 <tt>Recommends</tt>, <tt>Suggests</tt>, <tt>Enhances</tt>,
3476 <tt>Pre-Depends</tt>, <tt>Conflicts</tt>,
3477 <tt>Build-Depends</tt>, <tt>Build-Depends-Indep</tt>,
3478 <tt>Build-Conflicts</tt> and <tt>Build-Conflicts-Indep</tt>
3479 may mention "virtual packages".
3483 A <em>virtual package</em> is one which appears in the
3484 <tt>Provides</tt> control file field of another package.
3485 The effect is as if the package(s) which provide a
3486 particular virtual package name had been listed by name
3487 everywhere the virtual package name appears. (See also <ref
3492 If there are both concrete and virtual packages of the same
3493 name, then the dependency may be satisfied (or the conflict
3494 caused) by either the concrete package with the name in
3495 question or any other concrete package which provides the
3496 virtual package with the name in question. This is so that,
3497 for example, supposing we have
3498 <example compact="compact">
3502 and someone else releases an enhanced version of the
3503 <tt>bar</tt> package (for example, a non-US variant), they
3505 <example compact="compact">
3509 and the <tt>bar-plus</tt> package will now also satisfy the
3510 dependency for the <tt>foo</tt> package.
3514 If a dependency or a conflict has a version number attached
3515 then only real packages will be considered to see whether
3516 the relationship is satisfied (or the prohibition violated,
3517 for a conflict) - it is assumed that a real package which
3518 provides the virtual package is not of the "right" version.
3519 So, a <tt>Provides</tt> field may not contain version
3520 numbers, and the version number of the concrete package
3521 which provides a particular virtual package will not be
3522 looked at when considering a dependency on or conflict with
3523 the virtual package name.
3527 It is likely that the ability will be added in a future
3528 release of <prgn>dpkg</prgn> to specify a version number for
3529 each virtual package it provides. This feature is not yet
3530 present, however, and is expected to be used only
3535 If you want to specify which of a set of real packages
3536 should be the default to satisfy a particular dependency on
3537 a virtual package, you should list the real package as an
3538 alternative before the virtual one.
3543 <sect id="replaces"><heading>Overwriting files and replacing
3544 packages - <tt>Replaces</tt></heading>
3547 Packages can declare in their control file that they should
3548 overwrite files in certain other packages, or completely
3549 replace other packages. The <tt>Replaces</tt> control file
3550 field has these two distinct purposes.
3553 <sect1><heading>Overwriting files in other packages</heading>
3556 Firstly, as mentioned before, it is usually an error for a
3557 package to contain files which are on the system in
3562 However, if the overwriting package declares that it
3563 <tt>Replaces</tt> the one containing the file being
3564 overwritten, then <prgn>dpkg</prgn> will replace the file
3565 from the old package with that from the new. The file
3566 will no longer be listed as "owned" by the old package.
3570 If a package is completely replaced in this way, so that
3571 <prgn>dpkg</prgn> does not know of any files it still
3572 contains, it is considered to have "disappeared". It will
3573 be marked as not wanted on the system (selected for
3574 removal) and not installed. Any <tt>conffile</tt>s
3575 details noted for the package will be ignored, as they
3576 will have been taken over by the overwriting package. The
3577 package's <prgn>postrm</prgn> script will be run with a
3578 special argument to allow the package to do any final
3579 cleanup required. See <ref id="mscriptsinstact">.
3583 If an installed package, <tt>foo</tt> say, declares that
3584 it replaces another, <tt>bar</tt>, and an attempt is made
3585 to install <tt>bar</tt>, <prgn>dpkg</prgn> will discard
3586 files in the <tt>bar</tt> package which would overwrite
3587 those already present in <tt>foo</tt>. This is so that
3588 you can install an older version of a package without
3593 For this usage of <tt>Replaces</tt>, virtual packages (see
3594 <ref id="virtual">) are not considered when looking at a
3595 <tt>Replaces</tt> field - the packages declared as being
3596 replaced must be mentioned by their real names.
3600 Furthermore, this usage of <tt>Replaces</tt> only takes
3601 effect when both packages are at least partially on the
3602 system at once, so that it can only happen if they do not
3603 conflict or if the conflict has been overridden.
3608 <sect1><heading>Replacing whole packages, forcing their
3612 Secondly, <tt>Replaces</tt> allows the packaging system to
3613 resolve which package should be removed when there is a
3614 conflict - see <ref id="conflicts">. This usage only
3615 takes effect when the two packages <em>do</em> conflict,
3616 so that the two usages of this field do not interfere with
3621 In this situation, the package declared as being replaced
3622 can be a virtual package, so for example, all mail
3623 transport agents (MTAs) would have the following fields in
3624 their control files:
3625 <example compact="compact">
3626 Provides: mail-transport-agent
3627 Conflicts: mail-transport-agent
3628 Replaces: mail-transport-agent
3630 ensuring that only one MTA can be installed at any one
3635 <sect><heading>Relationships between source and binary packages -
3636 <tt>Build-Depends</tt>, <tt>Build-Depends-Indep</tt>,
3637 <tt>Build-Conflicts</tt>, <tt>Build-Conflicts-Indep</tt>
3641 Source packages that require certain binary packages to be
3642 installed or absent at the time of building the package
3643 can declare relationships to those binary packages.
3647 This is done using the <tt>Build-Depends</tt>,
3648 <tt>Build-Depends-Indep</tt>, <tt>Build-Conflicts</tt> and
3649 <tt>Build-Conflicts-Indep</tt> control file fields.
3653 Build-dependencies on "build-essential" binary packages can be
3654 omitted. Please see <ref id="pkg-relations"> for more information.
3658 The dependencies and conflicts they define must be satisfied
3659 (as defined earlier for binary packages) in order to invoke
3660 the targets in <tt>debian/rules</tt>, as follows:<footnote>
3662 If you make "build-arch" or "binary-arch", you need
3663 Build-Depends. If you make "build-indep" or
3664 "binary-indep", you need Build-Depends and
3665 Build-Depends-Indep. If you make "build" or "binary",
3669 There is no Build-Depends-Arch; the autobuilders will
3670 only need the Build-Depends if they know how to build
3671 only build-arch and binary-arch. Anyone building the
3672 build-indep/binary-indep targets is basically assumed to
3673 be building the whole package and so installs all build
3677 The purpose of the original split, I recall, was so that
3678 the autobuilders wouldn't need to install extra packages
3679 needed only for the binary-indep targets. But without a
3680 build-arch/build-indep split, this didn't work, since
3681 most of the work is done in the build target, not in the
3687 <tag><tt>Build-Depends</tt>, <tt>Build-Conflicts</tt></tag>
3690 The <tt>Build-Depends</tt> and
3691 <tt>Build-Conflicts</tt> fields must be satisfied when
3692 any of the following targets is invoked:
3693 <tt>build</tt>, <tt>clean</tt>, <tt>binary</tt>,
3694 <tt>binary-arch</tt>, <tt>build-arch</tt>,
3695 <tt>build-indep</tt> and <tt>binary-indep</tt>.
3698 <tag><tt>Build-Depends-Indep</tt>,
3699 <tt>Build-Conflicts-Indep</tt></tag>
3702 The <tt>Build-Depends-Indep</tt> and
3703 <tt>Build-Conflicts-Indep</tt> fields must be
3704 satisfied when any of the following targets is
3705 invoked: <tt>build</tt>, <tt>clean</tt>,
3706 <tt>build-indep</tt>, <tt>binary</tt> and
3707 <tt>binary-indep</tt>.
3718 <chapt id="conffiles"><heading>Configuration file handling
3722 This chapter has been superseded by <ref id="config-files">.
3726 <chapt id="sharedlibs"><heading>Shared libraries</heading>
3729 Packages containing shared libraries must be constructed with
3730 a little care to make sure that the shared library is always
3731 available. This is especially important for packages whose
3732 shared libraries are vitally important, such as the C library
3733 (currently <tt>libc6</tt>).
3737 Packages involving shared libraries should be split up into
3738 several binary packages. This section mostly deals with how
3739 this separation is to be accomplished; rules for files within
3740 the shared library packages are in <ref id="libraries"> instead.
3743 <sect id="sharedlibs-runtime">
3744 <heading>Run-time shared libraries</heading>
3747 The run-time shared library needs to be placed in a package called
3748 <package><var>libraryname</var><var>soversion</var></package>, where
3749 <file><var>soversion</var></file> is the version number in the
3750 soname of the shared library<footnote>
3752 The soname is the shared object name: it's the thing
3753 that has to match exactly between building an executable
3754 and running it for the dynamic linker to be able run the
3755 program. For example, if the soname of the library is
3756 <file>libfoo.so.6</file>, the library package would be
3757 called <file>libfoo6</file>.
3760 Alternatively, if it would be confusing to directly append
3761 <var>soversion</var> to <var>libraryname</var> (e.g. because
3762 <var>libraryname</var> itself ends in a number), you may use
3763 <package><var>libraryname</var>-<var>soversion</var></package> and
3764 <package><var>libraryname</var>-<var>soversion</var>-dev</package>
3769 If you have several shared libraries built from the same
3770 source tree you may lump them all together into a single
3771 shared library package, provided that you change all of
3772 their sonames at once (so that you don't get filename
3773 clashes if you try to install different versions of the
3774 combined shared libraries package).
3778 The package should install the shared libraries under
3779 their normal names. For example, the <package>libgdbmg1</package>
3780 package should install <file>libgdbm.so.1.7.3</file> as
3781 <file>/usr/lib/libgdbm.so.1.7.3</file>. The files should not be
3782 renamed or re-linked by any <prgn>prerm</prgn> or
3783 <prgn>postrm</prgn> scripts; <prgn>dpkg</prgn> will take care
3784 of renaming things safely without affecting running programs,
3785 and attempts to interfere with this are likely to lead to
3790 Shared libraries should not be installed executable, since
3791 the dynamic linker does not require this and trying to
3792 execute a shared library usually results in a core dump.
3796 The run-time library package should include the symbolic link that
3797 <prgn>ldconfig</prgn> would create for the shared libraries.
3798 For example, the <package>libgdbmg1</package> package should include
3799 a symbolic link from <file>/usr/lib/libgdbm.so.1</file> to
3800 <file>libgdbm.so.1.7.3</file>. This is needed so that the dynamic
3801 linker (for example <prgn>ld.so</prgn> or
3802 <prgn>ld-linux.so.*</prgn>) can find the library between the
3803 time that <prgn>dpkg</prgn> installs it and the time that
3804 <prgn>ldconfig</prgn> is run in the <prgn>postinst</prgn>
3807 The package management system requires the library to be
3808 placed before the symbolic link pointing to it in the
3809 <file>.deb</file> file. This is so that when
3810 <prgn>dpkg</prgn> comes to install the symlink
3811 (overwriting the previous symlink pointing at an older
3812 version of the library), the new shared library is already
3813 in place. In the past, this was achieved by creating the
3814 library in the temporary packaging directory before
3815 creating the symlink. Unfortunately, this was not always
3816 effective, since the building of the tar file in the
3817 <file>.deb</file> depended on the behavior of the underlying
3818 file system. Some file systems (such as reiserfs) reorder
3819 the files so that the order of creation is forgotten.
3820 Since version 1.7.0, <prgn>dpkg</prgn>
3821 reorders the files itself as necessary when building a
3822 package. Thus it is no longer important to concern
3823 oneself with the order of file creation.
3828 <sect1 id="ldconfig">
3829 <heading><tt>ldconfig</tt></heading>
3832 Any package installing shared libraries in one of the default
3833 library directories of the dynamic linker (which are currently
3834 <file>/usr/lib</file> and <file>/lib</file>) or a directory that is
3835 listed in <file>/etc/ld.so.conf</file><footnote>
3838 <list compact="compact">
3839 <item><p>/usr/X11R6/lib/Xaw3d</p></item>
3840 <item><p>/usr/local/lib</p></item>
3841 <item><p>/usr/lib/libc5-compat</p></item>
3842 <item><p>/lib/libc5-compat</p></item>
3843 <item><p>/usr/X11R6/lib</p></item>
3847 must use <prgn>ldconfig</prgn> to update the shared library
3852 The package must call <prgn>ldconfig</prgn> in the
3853 <prgn>postinst</prgn> script if the first argument is
3854 <tt>configure</tt>; the <prgn>postinst</prgn> script may
3855 optionally invoke <prgn>ldconfig</prgn> at other times. The
3856 package should call <prgn>ldconfig</prgn> in the
3857 <prgn>postrm</prgn> script if the first argument is
3858 <tt>remove</tt>. The maintainer scripts must not invoke
3859 <prgn>ldconfig</prgn> under any circumstances other than those
3860 described in this paragraph.<footnote>
3861 <p>During install or upgrade, the preinst is called before
3862 the new files are installed, so calling "ldconfig" is
3863 pointless. The preinst of an existing package can also be
3864 called if an upgrade fails. However, this happens during
3865 the critical time when a shared libs may exist on-disk
3866 under a temporary name. Thus, it is dangerous and
3867 forbidden by current policy to call "ldconfig" at this
3870 <p>When a package is installed or upgraded, "postinst
3871 configure" runs after the new files are safely on-disk.
3872 Since it is perfectly safe to invoke ldconfig
3873 unconditionally in a postinst, it is OK for a package to
3874 simply put ldconfig in its postinst without checking the
3875 argument. The postinst can also be called to recover from
3876 a failed upgrade. This happens before any new files are
3877 unpacked, so there is no reason to call "ldconfig" at this
3880 <p>For a package that is being removed, prerm is
3881 called with all the files intact, so calling ldconfig is
3882 useless. The other calls to "prerm" happen in the case of
3883 upgrade at a time when all the files of the old package
3884 are on-disk, so again calling "ldconfig" is pointless.
3886 <p>postrm, on the other hand, is called with the "remove"
3887 argument just after the files are removed, so this is the
3888 proper time to call "ldconfig" to notify the system of the
3889 fact shared libraries from the package are removed.
3890 The postrm can be called at several other times. At the
3891 time of "postrm purge", "postrm abort-install", or "postrm
3892 abort-upgrade", calling "ldconfig" is useless because the
3893 shared lib files are not on-disk. However, when "postrm"
3894 is invoked with arguments "upgrade", "failed-upgrade", or
3895 "disappear", a shared lib may exist on-disk under a
3904 <sect id="sharedlibs-runtime-progs">
3905 <heading>Run-time support programs</heading>
3908 If your package has some run-time support programs which use
3909 the shared library you must not put them in the shared
3910 library package. If you do that then you won't be able to
3911 install several versions of the shared library without
3912 getting filename clashes.
3916 Instead, either create another package for the runtime binaries
3917 (this package might typically be named
3918 <package><var>libraryname</var>-runtime</package>; note the absence
3919 of the <var>soversion</var> in the package name), or if the
3920 development package is small, include them in there.
3924 <sect id="sharedlibs-static">
3925 <heading>Static libraries</heading>
3928 The static library (<file><var>libraryname.a</var></file>)
3929 is usually provided in addition to the shared version.
3930 It is placed into the development package (see below).
3934 In some cases, it is acceptable for a library to be
3935 available in static form only; these cases include:
3937 <item>libraries for languages whose shared library support
3938 is immature or unstable</item>
3939 <item>libraries whose interfaces are in flux or under
3940 development (commonly the case when the library's
3941 major version number is zero, or where the ABI breaks
3942 across patchlevels)</item>
3943 <item>libraries which are explicitly intended to be
3944 available only in static form by their upstream
3949 <sect id="sharedlibs-dev">
3950 <heading>Development files</heading>
3953 The development files associated to a shared library need to be
3954 placed in a package called
3955 <package><var>libraryname</var><var>soversion</var>-dev</package>,
3956 or if you prefer only to support one development version at a
3957 time, <package><var>libraryname</var>-dev</package>.
3961 In case several development versions of a library exist, you may
3962 need to use <prgn>dpkg</prgn>'s Conflicts mechanism (see
3963 <ref id="conflicts">) to ensure that the user only installs one
3964 development version at a time (as different development versions are
3965 likely to have the same header files in them, which would cause a
3966 filename clash if both were installed).
3970 The development package should contain a symlink for the associated
3971 shared library without a version number. For example, the
3972 <package>libgdbmg1-dev</package> package should include a symlink
3973 from <file>/usr/lib/libgdbm.so</file> to
3974 <file>libgdbm.so.1.7.3</file>. This symlink is needed by the linker
3975 (<prgn>ld</prgn>) when compiling packages, as it will only look for
3976 <file>libgdbm.so</file> when compiling dynamically.
3980 <sect id="sharedlibs-intradeps">
3981 <heading>Dependencies between the packages of the same library</heading>
3984 Typically the development version should have an exact
3985 version dependency on the runtime library, to make sure that
3986 compilation and linking happens correctly. The
3987 <tt>${Source-Version}</tt> substitution variable can be
3988 useful for this purpose.
3992 <sect id="sharedlibs-shlibdeps">
3993 <heading>Dependencies between the library and other packages -
3994 the <tt>shlibs</tt> system</heading>
3997 If a package contains a binary or library which links to a
3998 shared library, we must ensure that when the package is
3999 installed on the system, all of the libraries needed are
4000 also installed. This requirement led to the creation of the
4001 <tt>shlibs</tt> system, which is very simple in its design:
4002 any package which <em>provides</em> a shared library also
4003 provides information on the package dependencies required to
4004 ensure the presence of this library, and any package which
4005 <em>uses</em> a shared library uses this information to
4006 determine the dependencies it requires. The files which
4007 contain the mapping from shared libraries to the necessary
4008 dependency information are called <file>shlibs</file> files.
4012 Thus, when a package is built which contains any shared
4013 libraries, it must provide a <file>shlibs</file> file for other
4014 packages to use, and when a package is built which contains
4015 any shared libraries or compiled binaries, it must run
4016 <prgn>dpkg-shlibdeps</prgn> on these to determine the
4017 libraries used and hence the dependencies needed by this
4020 In the past, the shared libraries linked to were
4021 determined by calling <prgn>ldd</prgn>, but now
4022 <prgn>objdump</prgn> is used to do this. The only
4023 change this makes to package building is that
4024 <prgn>dpkg-shlibdeps</prgn> must also be run on shared
4025 libraries, whereas in the past this was unnecessary.
4026 The rest of this footnote explains the advantage that
4031 We say that a binary <tt>foo</tt> <em>directly</em> uses
4032 a library <tt>libbar</tt> if it is explicitly linked
4033 with that library (that is, it uses the flag
4034 <tt>-lbar</tt> during the linking stage). Other
4035 libraries that are needed by <tt>libbar</tt> are linked
4036 <em>indirectly</em> to <tt>foo</tt>, and the dynamic
4037 linker will load them automatically when it loads
4038 <tt>libbar</tt>. A package should depend on
4039 the libraries it directly uses, and the dependencies for
4040 those libraries should automatically pull in the other
4045 Unfortunately, the <prgn>ldd</prgn> program shows both
4046 the directly and indirectly used libraries, meaning that
4047 the dependencies determined included both direct and
4048 indirect dependencies. The use of <prgn>objdump</prgn>
4049 avoids this problem by determining only the directly
4054 A good example of where this helps is the following. We
4055 could update <tt>libimlib</tt> with a new version that
4056 supports a new graphics format called dgf (but retaining
4057 the same major version number). If we used the old
4058 <prgn>ldd</prgn> method, every package that uses
4059 <tt>libimlib</tt> would need to be recompiled so it
4060 would also depend on <tt>libdgf</tt> or it wouldn't run
4061 due to missing symbols. However with the new system,
4062 packages using <tt>libimlib</tt> can rely on
4063 <tt>libimlib</tt> itself having the dependency on
4064 <tt>libdgf</tt> and so they would not need rebuilding.
4070 In the following sections, we will first describe where the
4071 various <tt>shlibs</tt> files are to be found, then how to
4072 use <prgn>dpkg-shlibdeps</prgn>, and finally the
4073 <tt>shlibs</tt> file format and how to create them if your
4074 package contains a shared library.
4078 <heading>The <tt>shlibs</tt> files present on the system</heading>
4081 There are several places where <tt>shlibs</tt> files are
4082 found. The following list gives them in the order in which
4083 they are read by <prgn>dpkg-shlibdeps</prgn>. (The first
4084 one which gives the required information is used.)
4090 <p><file>debian/shlibs.local</file></p>
4092 This lists overrides for this package. Its use is
4093 described below (see <ref id="shlibslocal">).
4098 <p><file>/etc/dpkg/shlibs.override</file></p>
4100 This lists global overrides. This list is normally
4101 empty. It is maintained by the local system
4107 <p><file>DEBIAN/shlibs</file> files in the "build directory"</p>
4109 When packages are being built, any
4110 <file>debian/shlibs</file> files are copied into the
4111 control file area of the temporary build directory and
4112 given the name <file>shlibs</file>. These files give
4113 details of any shared libraries included in the
4116 An example may help here. Let us say that the
4117 source package <tt>foo</tt> generates two binary
4118 packages, <tt>libfoo2</tt> and
4119 <tt>foo-runtime</tt>. When building the binary
4120 packages, the two packages are created in the
4121 directories <file>debian/libfoo2</file> and
4122 <file>debian/foo-runtime</file> respectively.
4123 (<file>debian/tmp</file> could be used instead of one
4124 of these.) Since <tt>libfoo2</tt> provides the
4125 <tt>libfoo</tt> shared library, it will require a
4126 <tt>shlibs</tt> file, which will be installed in
4127 <file>debian/libfoo2/DEBIAN/shlibs</file>, eventually
4129 <file>/var/lib/dpkg/info/libfoo2.shlibs</file>. Then
4130 when <prgn>dpkg-shlibdeps</prgn> is run on the
4132 <file>debian/foo-runtime/usr/bin/foo-prog</file>, it
4134 <file>debian/libfoo2/DEBIAN/shlibs</file> file to
4135 determine whether <tt>foo-prog</tt>'s library
4136 dependencies are satisfied by any of the libraries
4137 provided by <tt>libfoo2</tt>. For this reason,
4138 <prgn>dpkg-shlibdeps</prgn> must only be run once
4139 all of the individual binary packages'
4140 <tt>shlibs</tt> files have been installed into the
4148 <p><file>/var/lib/dpkg/info/*.shlibs</file></p>
4150 These are the <file>shlibs</file> files corresponding to
4151 all of the packages installed on the system, and are
4152 maintained by the relevant package maintainers.
4157 <p><file>/etc/dpkg/shlibs.default</file></p>
4159 This file lists any shared libraries whose packages
4160 have failed to provide correct <file>shlibs</file> files.
4161 It was used when the <file>shlibs</file> setup was first
4162 introduced, but it is now normally empty. It is
4163 maintained by the <tt>dpkg</tt> maintainer.
4171 <heading>How to use <prgn>dpkg-shlibdeps</prgn> and the
4172 <file>shlibs</file> files</heading>
4175 Put a call to <prgn>dpkg-shlibdeps</prgn> into your
4176 <file>debian/rules</file> file. If your package contains only
4177 compiled binaries and libraries (but no scripts), you can
4178 use a command such as:
4179 <example compact="compact">
4180 dpkg-shlibdeps debian/tmp/usr/bin/* debian/tmp/usr/sbin/* \
4181 debian/tmp/usr/lib/*
4183 Otherwise, you will need to explicitly list the compiled
4184 binaries and libraries.<footnote>
4186 If you are using <tt>debhelper</tt>, the
4187 <prgn>dh_shlibdeps</prgn> program will do this work for
4188 you. It will also correctly handle multi-binary
4195 This command puts the dependency information into the
4196 <file>debian/substvars</file> file, which is then used by
4197 <prgn>dpkg-gencontrol</prgn>. You will need to place a
4198 <tt>${shlib:Depends}</tt> variable in the <tt>Depends</tt>
4199 field in the control file for this to work.
4203 If <prgn>dpkg-shlibdeps</prgn> doesn't complain, you're
4204 done. If it does complain you might need to create your own
4205 <file>debian/shlibs.local</file> file, as explained below (see
4206 <ref id="shlibslocal">).
4210 If you have multiple binary packages, you will need to call
4211 <prgn>dpkg-shlibdeps</prgn> on each one which contains
4212 compiled libraries or binaries. In such a case, you will
4213 need to use the <tt>-T</tt> option to the <tt>dpkg</tt>
4214 utilities to specify a different <file>substvars</file> file.
4215 For more details on this and other options, see <manref
4216 name="dpkg-shlibdeps" section="1">.
4221 <heading>The <file>shlibs</file> File Format</heading>
4224 Each <file>shlibs</file> file has the same format. Lines
4225 beginning with <tt>#</tt> are considered to be comments and
4226 are ignored. Each line is of the form:
4227 <example compact="compact">
4228 <var>library-name</var> <var>soname-version-number</var> <var>dependencies ...</var>
4233 We will explain this by reference to the example of the
4234 <tt>zlib1g</tt> package, which (at the time of writing)
4235 installs the shared library <file>/usr/lib/libz.so.1.1.3</file>.
4239 <var>library-name</var> is the name of the shared library,
4240 in this case <tt>libz</tt>. (This must match the name part
4241 of the soname, see below.)
4245 <var>soname-version-number</var> is the version part of the
4246 soname of the library. The soname is the thing that must
4247 exactly match for the library to be recognized by the
4248 dynamic linker, and is usually of the form
4249 <tt><var>name</var>.so.<var>major-version</var></tt>, in our
4250 example, <tt>libz.so.1</tt>.<footnote>
4252 This can be determined using the command
4253 <example compact="compact">
4254 objdump -p /usr/lib/libz.so.1.1.3 | grep SONAME
4258 The version part is the part which comes after
4259 <tt>.so.</tt>, so in our case, it is <tt>1</tt>.
4263 <var>dependencies</var> has the same syntax as a dependency
4264 field in a binary package control file. It should give
4265 details of which packages are required to satisfy a binary
4266 built against the version of the library contained in the
4267 package. See <ref id="depsyntax"> for details.
4271 In our example, if the first version of the <tt>zlib1g</tt>
4272 package which contained a minor number of at least
4273 <tt>1.3</tt> was <var>1:1.1.3-1</var>, then the
4274 <tt>shlibs</tt> entry for this library could say:
4275 <example compact="compact">
4276 libz 1 zlib1g (>= 1:1.1.3)
4278 The version-specific dependency is to avoid warnings from
4279 the dynamic linker about using older shared libraries with
4285 <heading>Providing a <file>shlibs</file> file</heading>
4288 If your package provides a shared library, you should create
4289 a <file>shlibs</file> file following the format described above.
4290 It is usual to call this file <file>debian/shlibs</file> (but if
4291 you have multiple binary packages, you might want to call it
4292 <file>debian/shlibs.<var>package</var></file> instead). Then
4293 let <file>debian/rules</file> install it in the control area:
4294 <example compact="compact">
4295 install -m644 debian/shlibs debian/tmp/DEBIAN
4297 or, in the case of a multi-binary package:
4298 <example compact="compact">
4299 install -m644 debian/shlibs.<var>package</var> debian/<var>package</var>/DEBIAN/shlibs
4301 An alternative way of doing this is to create the
4302 <file>shlibs</file> file in the control area directly from
4303 <file>debian/rules</file> without using a <file>debian/shlibs</file>
4304 file at all,<footnote>
4306 This is what <prgn>dh_makeshlibs</prgn> in the
4307 <tt>debhelper</tt> suite does.
4310 since the <file>debian/shlibs</file> file itself is ignored by
4311 <prgn>dpkg-shlibdeps</prgn>.
4315 As <prgn>dpkg-shlibdeps</prgn> reads the
4316 <file>DEBIAN/shlibs</file> files in all of the binary packages
4317 being built from this source package, all of the
4318 <file>DEBIAN/shlibs</file> files should be installed before
4319 <prgn>dpkg-shlibdeps</prgn> is called on any of the binary
4324 <sect1 id="shlibslocal">
4325 <heading>Writing the <file>debian/shlibs.local</file> file</heading>
4328 This file is intended only as a <em>temporary</em> fix if
4329 your binaries or libraries depend on a library whose package
4330 does not yet provide a correct <file>shlibs</file> file.
4334 We will assume that you are trying to package a binary
4335 <tt>foo</tt>. When you try running
4336 <prgn>dpkg-shlibdeps</prgn> you get the following error
4337 message (<tt>-O</tt> displays the dependency information on
4338 <tt>stdout</tt> instead of writing it to
4339 <tt>debian/substvars</tt>, and the lines have been wrapped
4340 for ease of reading):
4341 <example compact="compact">
4342 $ dpkg-shlibdeps -O debian/tmp/usr/bin/foo
4343 dpkg-shlibdeps: warning: unable to find dependency
4344 information for shared library libbar (soname 1,
4345 path /usr/lib/libbar.so.1, dependency field Depends)
4346 shlibs:Depends=libc6 (>= 2.2.2-2)
4348 You can then run <prgn>ldd</prgn> on the binary to find the
4349 full location of the library concerned:
4350 <example compact="compact">
4352 libbar.so.1 => /usr/lib/libbar.so.1 (0x4001e000)
4353 libc.so.6 => /lib/libc.so.6 (0x40032000)
4354 /lib/ld-linux.so.2 => /lib/ld-linux.so.2 (0x40000000)
4356 So the <prgn>foo</prgn> binary depends on the
4357 <prgn>libbar</prgn> shared library, but no package seems to
4358 provide a <file>*.shlibs</file> file handling
4359 <file>libbar.so.1</file> in <file>/var/lib/dpkg/info/</file>. Let's
4360 determine the package responsible:
4361 <example compact="compact">
4362 $ dpkg -S /usr/lib/libbar.so.1
4363 bar1: /usr/lib/libbar.so.1
4364 $ dpkg -s bar1 | grep Version
4367 This tells us that the <tt>bar1</tt> package, version 1.0-1,
4368 is the one we are using. Now we can file a bug against the
4369 <tt>bar1</tt> package and create our own
4370 <file>debian/shlibs.local</file> to locally fix the problem.
4371 Including the following line into your
4372 <file>debian/shlibs.local</file> file:
4373 <example compact="compact">
4374 libbar 1 bar1 (>= 1.0-1)
4376 should allow the package build to work.
4380 As soon as the maintainer of <tt>bar1</tt> provides a
4381 correct <file>shlibs</file> file, you should remove this line
4382 from your <file>debian/shlibs.local</file> file. (You should
4383 probably also then have a versioned <tt>Build-Depends</tt>
4384 on <tt>bar1</tt> to help ensure that others do not have the
4385 same problem building your package.)
4393 <chapt id="opersys"><heading>The Operating System</heading>
4396 <heading>Filesystem hierarchy</heading>
4400 <heading>Filesystem Structure</heading>
4403 The location of all installed files and directories must
4404 comply with the Filesystem Hierarchy Standard (FHS),
4405 version 2.1, except where doing so would violate other
4406 terms of Debian Policy. The version of this document
4407 referred here can be found in the <tt>debian-policy</tt>
4409 <url id="http://www.debian.org/doc/packaging-manuals/fhs/"
4410 name="FHS (Debian copy)"> alongside this manual (or, if
4411 you have the <package>debian-policy</package> installed,
4413 id="file:///usr/share/doc/debian-policy/fhs/" name="FHS
4414 (local copy)">). The
4415 latest version, which may be a more recent version, may
4417 <url id="http://www.pathname.com/fhs/" name="FHS (upstream)">.
4418 Specific questions about following the standard may be
4419 asked on the <tt>debian-devel</tt> mailing list, or
4420 referred to the FHS mailing list (see the
4421 <url id="http://www.pathname.com/fhs/" name="FHS web site"> for
4427 <heading>Site-specific programs</heading>
4430 As mandated by the FHS, packages must not place any
4431 files in <file>/usr/local</file>, either by putting them in
4432 the file system archive to be unpacked by <prgn>dpkg</prgn>
4433 or by manipulating them in their maintainer scripts.
4437 However, the package may create empty directories below
4438 <file>/usr/local</file> so that the system administrator knows
4439 where to place site-specific files. These directories
4440 should be removed on package removal if they are
4445 Note, that this applies only to directories <em>below</em>
4446 <file>/usr/local</file>, not <em>in</em> <file>/usr/local</file>.
4447 Packages must not create sub-directories in the directory
4448 <file>/usr/local</file> itself, except those listed in FHS,
4449 section 4.5. However, you may create directories below
4450 them as you wish. You must not remove any of the
4451 directories listed in 4.5, even if you created them.
4455 Since <file>/usr/local</file> can be mounted read-only from a
4456 remote server, these directories must be created and
4457 removed by the <prgn>postinst</prgn> and <prgn>prerm</prgn>
4458 maintainer scripts and not be included in the
4459 <file>.deb</file> archive. These scripts must not fail if
4460 either of these operations fail.
4464 For example, the <tt>emacsen-common</tt> package could
4465 contain something like
4466 <example compact="compact">
4467 if [ ! -e /usr/local/share/emacs ]
4469 if mkdir /usr/local/share/emacs 2>/dev/null
4471 chown root:staff /usr/local/share/emacs
4472 chmod 2775 /usr/local/share/emacs
4476 in its <prgn>postinst</prgn> script, and
4477 <example compact="compact">
4478 rmdir /usr/local/share/emacs/site-lisp 2>/dev/null || true
4479 rmdir /usr/local/share/emacs 2>/dev/null || true
4481 in the <prgn>prerm</prgn> script. (Note that this form is
4482 used to ensure that if the script is interrupted, the
4483 directory <file>/usr/local/share/emacs</file> will still be
4488 If you do create a directory in <file>/usr/local</file> for
4489 local additions to a package, you should ensure that
4490 settings in <file>/usr/local</file> take precedence over the
4491 equivalents in <file>/usr</file>.
4495 However, because <file>/usr/local</file> and its contents are
4496 for exclusive use of the local administrator, a package
4497 must not rely on the presence or absence of files or
4498 directories in <file>/usr/local</file> for normal operation.
4502 The <file>/usr/local</file> directory itself and all the
4503 subdirectories created by the package should (by default) have
4504 permissions 2775 (group-writable and set-group-id) and be
4505 owned by <tt>root.staff</tt>.
4510 <heading>The system-wide mail directory</heading>
4512 The system-wide mail directory is <file>/var/mail</file>. This
4513 directory is part of the base system and should not owned
4514 by any particular mail agents. The use of the old
4515 location <file>/var/spool/mail</file> is deprecated, even
4516 though the spool may still be physically located there.
4517 To maintain partial upgrade compatibility for systems
4518 which have <file>/var/spool/mail</file> as their physical mail
4519 spool, packages using <file>/var/mail</file> must depend on
4520 either <package>libc6</package> (>= 2.1.3-13), or on
4521 <package>base-files</package> (>= 2.2.0), or on later
4522 versions of either one of these packages.
4528 <heading>Users and groups</heading>
4531 <heading>Introduction</heading>
4533 The Debian system can be configured to use either plain or
4538 Some user ids (UIDs) and group ids (GIDs) are reserved
4539 globally for use by certain packages. Because some
4540 packages need to include files which are owned by these
4541 users or groups, or need the ids compiled into binaries,
4542 these ids must be used on any Debian system only for the
4543 purpose for which they are allocated. This is a serious
4544 restriction, and we should avoid getting in the way of
4545 local administration policies. In particular, many sites
4546 allocate users and/or local system groups starting at 100.
4550 Apart from this we should have dynamically allocated ids,
4551 which should by default be arranged in some sensible
4552 order, but the behavior should be configurable.
4556 Packages other than <tt>base-passwd</tt> must not modify
4557 <file>/etc/passwd</file>, <file>/etc/shadow</file>,
4558 <file>/etc/group</file> or <file>/etc/gshadow</file>.
4563 <heading>UID and GID classes</heading>
4565 The UID and GID numbers are divided into classes as
4571 Globally allocated by the Debian project, the same
4572 on every Debian system. These ids will appear in
4573 the <file>passwd</file> and <file>group</file> files of all
4574 Debian systems, new ids in this range being added
4575 automatically as the <tt>base-passwd</tt> package is
4580 Packages which need a single statically allocated
4581 uid or gid should use one of these; their
4582 maintainers should ask the <tt>base-passwd</tt>
4590 Dynamically allocated system users and groups.
4591 Packages which need a user or group, but can have
4592 this user or group allocated dynamically and
4593 differently on each system, should use <tt>adduser
4594 --system</tt> to create the group and/or user.
4595 <prgn>adduser</prgn> will check for the existence of
4596 the user or group, and if necessary choose an unused
4597 id based on the ranges specified in
4598 <file>adduser.conf</file>.
4602 <tag>1000-29999:</tag>
4605 Dynamically allocated user accounts. By default
4606 <prgn>adduser</prgn> will choose UIDs and GIDs for
4607 user accounts in this range, though
4608 <file>adduser.conf</file> may be used to modify this
4613 <tag>30000-59999:</tag>
4618 <tag>60000-64999:</tag>
4621 Globally allocated by the Debian project, but only
4622 created on demand. The ids are allocated centrally
4623 and statically, but the actual accounts are only
4624 created on users' systems on demand.
4628 These ids are for packages which are obscure or
4629 which require many statically-allocated ids. These
4630 packages should check for and create the accounts in
4631 <file>/etc/passwd</file> or <file>/etc/group</file> (using
4632 <prgn>adduser</prgn> if it has this facility) if
4633 necessary. Packages which are likely to require
4634 further allocations should have a "hole" left after
4635 them in the allocation, to give them room to
4640 <tag>65000-65533:</tag>
4648 User <tt>nobody</tt>. The corresponding gid refers
4649 to the group <tt>nogroup</tt>.
4656 <tt>(uid_t)(-1) == (gid_t)(-1)</tt> <em>must
4657 not</em> be used, because it is the error return
4666 <sect id="sysvinit">
4667 <heading>System run levels and <file>init.d</file> scripts</heading>
4669 <sect1 id="/etc/init.d">
4670 <heading>Introduction</heading>
4673 The <file>/etc/init.d</file> directory contains the scripts
4674 executed by <prgn>init</prgn> at boot time and when the
4675 init state (or "runlevel") is changed (see <manref
4676 name="init" section="8">).
4680 There are at least two different, yet functionally
4681 equivalent, ways of handling these scripts. For the sake
4682 of simplicity, this document describes only the symbolic
4683 link method. However, it must not be assumed by maintainer
4684 scripts that this method is being used, and any automated
4685 manipulation of the various runlevel behaviours by
4686 maintainer scripts must be performed using
4687 <prgn>update-rc.d</prgn> as described below and not by
4688 manually installing or removing symlinks. For information
4689 on the implementation details of the other method,
4690 implemented in the <tt>file-rc</tt> package, please refer
4691 to the documentation of that package.
4695 These scripts are referenced by symbolic links in the
4696 <file>/etc/rc<var>n</var>.d</file> directories. When changing
4697 runlevels, <prgn>init</prgn> looks in the directory
4698 <file>/etc/rc<var>n</var>.d</file> for the scripts it should
4699 execute, where <tt><var>n</var></tt> is the runlevel that
4700 is being changed to, or <tt>S</tt> for the boot-up
4705 The names of the links all have the form
4706 <file>S<var>mm</var><var>script</var></file> or
4707 <file>K<var>mm</var><var>script</var></file> where
4708 <var>mm</var> is a two-digit number and <var>script</var>
4709 is the name of the script (this should be the same as the
4710 name of the actual script in <file>/etc/init.d</file>).
4714 When <prgn>init</prgn> changes runlevel first the targets
4715 of the links whose names start with a <tt>K</tt> are
4716 executed, each with the single argument <tt>stop</tt>,
4717 followed by the scripts prefixed with an <tt>S</tt>, each
4718 with the single argument <tt>start</tt>. (The links are
4719 those in the <file>/etc/rc<var>n</var>.d</file> directory
4720 corresponding to the new runlevel.) The <tt>K</tt> links
4721 are responsible for killing services and the <tt>S</tt>
4722 link for starting services upon entering the runlevel.
4726 For example, if we are changing from runlevel 2 to
4727 runlevel 3, init will first execute all of the <tt>K</tt>
4728 prefixed scripts it finds in <file>/etc/rc3.d</file>, and then
4729 all of the <tt>S</tt> prefixed scripts in that directory.
4730 The links starting with <tt>K</tt> will cause the
4731 referred-to file to be executed with an argument of
4732 <tt>stop</tt>, and the <tt>S</tt> links with an argument
4737 The two-digit number <var>mm</var> is used to determine
4738 the order in which to run the scripts: low-numbered links
4739 have their scripts run first. For example, the
4740 <tt>K20</tt> scripts will be executed before the
4741 <tt>K30</tt> scripts. This is used when a certain service
4742 must be started before another. For example, the name
4743 server <prgn>bind</prgn> might need to be started before
4744 the news server <prgn>inn</prgn> so that <prgn>inn</prgn>
4745 can set up its access lists. In this case, the script
4746 that starts <prgn>bind</prgn> would have a lower number
4747 than the script that starts <prgn>inn</prgn> so that it
4749 <example compact="compact">
4756 The two runlevels 0 (halt) and 6 (reboot) are slightly
4757 different. In these runlevels, the links with an
4758 <tt>S</tt> prefix are still called after those with a
4759 <tt>K</tt> prefix, but they too are called with the single
4760 argument <tt>stop</tt>.
4764 Also, if the script name ends <tt>.sh</tt>, the script
4765 will be sourced in runlevel <tt>S</tt> rather that being
4766 run in a forked subprocess, but will be explicitly run by
4767 <prgn>sh</prgn> in all other runlevels.
4772 <heading>Writing the scripts</heading>
4775 Packages that include daemons for system services should
4776 place scripts in <file>/etc/init.d</file> to start or stop
4777 services at boot time or during a change of runlevel.
4778 These scripts should be named
4779 <file>/etc/init.d/<var>package</var></file>, and they should
4780 accept one argument, saying what to do:
4783 <tag><tt>start</tt></tag>
4784 <item><p>start the service,</p></item>
4786 <tag><tt>stop</tt></tag>
4787 <item><p>stop the service,</p></item>
4789 <tag><tt>restart</tt></tag>
4790 <item><p>stop and restart the service if it's already
4791 running, otherwise start the service</p></item>
4793 <tag><tt>reload</tt></tag>
4794 <item><p>cause the configuration of the service to be
4795 reloaded without actually stopping and restarting
4796 the service,</p></item>
4798 <tag><tt>force-reload</tt></tag>
4799 <item><p>cause the configuration to be reloaded if the
4800 service supports this, otherwise restart the
4804 The <tt>start</tt>, <tt>stop</tt>, <tt>restart</tt>, and
4805 <tt>force-reload</tt> options should be supported by all
4806 scripts in <file>/etc/init.d</file>, the <tt>reload</tt>
4807 option is optional.</p>
4810 The <file>init.d</file> scripts should ensure that they will
4811 behave sensibly if invoked with <tt>start</tt> when the
4812 service is already running, or with <tt>stop</tt> when it
4813 isn't, and that they don't kill unfortunately-named user
4814 processes. The best way to achieve this is usually to use
4815 <prgn>start-stop-daemon</prgn>.</p>
4818 If a service reloads its configuration automatically (as
4819 in the case of <prgn>cron</prgn>, for example), the
4820 <tt>reload</tt> option of the <file>init.d</file> script
4821 should behave as if the configuration has been reloaded
4825 The <file>/etc/init.d</file> scripts must be treated as
4826 configuration files, either (if they are present in the
4827 package, that is, in the .deb file) by marking them as
4828 <tt>conffile</tt>s, or, (if they do not exist in the .deb)
4829 by managing them correctly in the maintainer scripts (see
4830 <ref id="config-files">). This is important since we want
4831 to give the local system administrator the chance to adapt
4832 the scripts to the local system, e.g., to disable a
4833 service without de-installing the package, or to specify
4834 some special command line options when starting a service,
4835 while making sure her changes aren't lost during the next
4840 These scripts should not fail obscurely when the
4841 configuration files remain but the package has been
4842 removed, as configuration files remain on the system after
4843 the package has been removed. Only when <prgn>dpkg</prgn>
4844 is executed with the <tt>--purge</tt> option will
4845 configuration files be removed. In particular, as the
4846 <file>/etc/init.d/<var>package</var></file> script itself is
4847 usually a <tt>conffile</tt>, it will remain on the system
4848 if the package is removed but not purged. Therefore, you
4849 should include a <tt>test</tt> statement at the top of the
4851 <example compact="compact">
4852 test -f <var>program-executed-later-in-script</var> || exit 0
4857 Often there are some variables in the <file>init.d</file>
4858 scripts whose values control the behaviour of the scripts,
4859 and which a system administrator is likely to want to
4860 change. As the scripts themselves are frequently
4861 <tt>conffile</tt>s, modifying them requires that the
4862 administrator merge in their changes each time the package
4863 is upgraded and the <tt>conffile</tt> changes. To ease
4864 the burden on the system administrator, such configurable
4865 values should not be placed directly in the script.
4866 Instead, they should be placed in a file in
4867 <file>/etc/default</file>, which typically will have the same
4868 base name as the <file>init.d</file> script. This extra file
4869 should be sourced by the script when the script runs. It
4870 must contain only variable settings and comments in POSIX
4871 <prgn>sh</prgn> format. It may either be a
4872 <tt>conffile</tt> or a configuration file maintained by
4873 the package maintainer scripts. See <ref id="config-files">
4878 To ensure that vital configurable values are always
4879 available, the <file>init.d</file> script should set default
4880 values for each of the shell variables it uses, either
4881 before sourcing the <file>/etc/default/</file> file or
4882 afterwards using something like the <tt>:
4883 ${VAR:=default}</tt> syntax. Also, the <file>init.d</file>
4884 script must behave sensibly and not fail if the
4885 <file>/etc/default</file> file is deleted.
4890 <heading>Interfacing with the initscript system</heading>
4893 Maintainers should use the abstraction layer provided by
4894 the <prgn>update-rc.d</prgn> and <prgn>invoke-rc.d</prgn>
4895 programs to deal with initscripts in their packages'
4896 scripts such as <prgn>postinst</prgn>, <prgn>prerm</prgn>
4897 and <prgn>postrm</prgn>.
4900 Directly managing the /etc/rc?.d links and directly
4901 invoking the <file>/etc/init.d/</file> initscripts should
4902 be done only by packages providing the initscript
4903 subsystem (such as <prgn>sysvinit</prgn> and
4904 <prgn>file-rc</prgn>).
4909 <heading>Managing the links</heading>
4912 The program <prgn>update-rc.d</prgn> is provided for
4913 package maintainers to arrange for the proper creation and
4914 removal of <file>/etc/rc<var>n</var>.d</file> symbolic links,
4915 or their functional equivalent if another method is being
4916 used. This may be used by maintainers in their packages'
4917 <prgn>postinst</prgn> and <prgn>postrm</prgn> scripts.</p>
4920 You must not include any <file>/etc/rc<var>n</var>.d</file>
4921 symbolic links in the actual archive or manually create or
4922 remove the symbolic links in maintainer scripts; you must
4923 use the <prgn>update-rc.d</prgn> program instead. (The
4924 former will fail if an alternative method of maintaining
4925 runlevel information is being used.) You must not include
4926 the <file>/etc/rc<var>n</var>.d</file> directories themselves
4927 in the archive either. (Only the <tt>sysvinit</tt>
4932 By default <prgn>update-rc.d</prgn> will start services in
4933 each of the multi-user state runlevels (2, 3, 4, and 5)
4934 and stop them in the halt runlevel (0), the single-user
4935 runlevel (1) and the reboot runlevel (6). The system
4936 administrator will have the opportunity to customize
4937 runlevels by simply adding, moving, or removing the
4938 symbolic links in <file>/etc/rc<var>n</var>.d</file> if
4939 symbolic links are being used, or by modifying
4940 <file>/etc/runlevel.conf</file> if the <tt>file-rc</tt> method
4945 To get the default behavior for your package, put in your
4946 <prgn>postinst</prgn> script
4947 <example compact="compact">
4948 update-rc.d <var>package</var> defaults
4950 and in your <prgn>postrm</prgn>
4951 <example compact="compact">
4952 if [ "$1" = purge ]; then
4953 update-rc.d <var>package</var> remove
4955 </example>. Note that if your package changes runlevels
4956 or priority, you may have to remove and recreate the links,
4957 since otherwise the old links may persist. Refer to the
4958 documentation of <prgn>update-rc.d</prgn></p>
4961 This will use a default sequence number of 20. If it does
4962 not matter when or in which order the <file>init.d</file>
4963 script is run, use this default. If it does, then you
4964 should talk to the maintainer of the <prgn>sysvinit</prgn>
4965 package or post to <tt>debian-devel</tt>, and they will
4966 help you choose a number.
4970 For more information about using <tt>update-rc.d</tt>,
4971 please consult its manpage <manref name="update-rc.d"
4977 <heading>Running initscripts</heading>
4979 The program <prgn>invoke-rc.d</prgn> is provided to make
4980 it easier for package maintainers to properly invoke an
4981 initscript, obeying runlevel and other locally-defined
4982 constraints that might limit a package's right to start,
4983 stop and otherwise manage services. This program may be
4984 used by maintainers in their packages' scripts.
4987 The use of <prgn>invoke-rc.d</prgn> to invoke the
4988 <file>/etc/init.d/*</file> initscripts is strongly
4989 recommended<footnote>
4991 In the future, the use of invoke-rc.d to invoke
4992 initscripts shall be made mandatory. Maintainers are
4993 advised to switch to invoke-rc.d as soon as
4995 </footnote>, instead of calling them directly.
4999 By default, <prgn>invoke-rc.d</prgn> will pass any
5000 action requests (start, stop, reload, restart...) to the
5001 <file>/etc/init.d</file> script, filtering out requests
5002 to start or restart a service out of its intended
5006 Most packages will simply need to change:
5007 <example compact="compact">/etc/init.d/<package>
5008 <action></example> in their <prgn>postinst</prgn>
5009 and <prgn>prerm</prgn> scripts to:
5010 <example compact="compact">
5011 if [ -x /usr/sbin/invoke-rc.d ] ; then
5012 invoke-rc.d <var>package</var> <action>
5014 /etc/init.d/<var>package</var> <action>
5018 A package should register its initscript services using
5019 <prgn>update-rc.d</prgn> before it tries to invoke them
5020 using <prgn>invoke-rc.d</prgn>. Invocation of
5021 unregistered services may fail.
5024 For more information about using
5025 <prgn>invoke-rc.d</prgn>, please consult its manpage
5026 <manref name="invoke-rc.d" section="8">.
5033 <heading>Boot-time initialization</heading>
5036 There used to be another directory, <file>/etc/rc.boot</file>,
5037 which contained scripts which were run once per machine
5038 boot. This has been deprecated in favour of links from
5039 <file>/etc/rcS.d</file> to files in <file>/etc/init.d</file> as
5040 described in <ref id="/etc/init.d">. Packages must not
5041 place files in <file>/etc/rc.boot</file>.</p>
5044 <heading>Example</heading>
5047 The <prgn>bind</prgn> DNS (nameserver) package wants to
5048 make sure that the nameserver is running in multiuser
5049 runlevels, and is properly shut down with the system. It
5050 puts a script in <file>/etc/init.d</file>, naming the script
5051 appropriately <tt>bind</tt>. As you can see, the script
5052 interprets the argument <tt>reload</tt> to send the
5053 nameserver a <tt>HUP</tt> signal (causing it to reload its
5054 configuration); this way the system administrator can say
5055 <tt>/etc/init.d/bind reload</tt> to reload the name
5056 server. The script has one configurable value, which can
5057 be used to pass parameters to the named program at
5058 startup; this value is read from
5059 <file>/etc/default/bind</file> (see below).
5063 <example compact="compact">
5066 # Original version by Robert Leslie
5067 # <rob@mars.org>, edited by iwj and cs
5069 test -x /usr/sbin/named || exit 0
5071 # Source defaults file.
5073 if [ -f /etc/default/bind ]; then
5080 echo -n "Starting domain name service: named"
5081 start-stop-daemon --start --quiet --exec /usr/sbin/named \
5086 echo -n "Stopping domain name service: named"
5087 start-stop-daemon --stop --quiet \
5088 --pidfile /var/run/named.pid --exec /usr/sbin/named
5092 echo -n "Restarting domain name service: named"
5093 start-stop-daemon --stop --quiet \
5094 --pidfile /var/run/named.pid --exec /usr/sbin/named
5095 start-stop-daemon --start --verbose --exec /usr/sbin/named \
5099 force-reload|reload)
5100 echo -n "Reloading configuration of domain name service: named"
5101 start-stop-daemon --stop --signal 1 --quiet \
5102 --pidfile /var/run/named.pid --exec /usr/sbin/named
5106 echo "Usage: /etc/init.d/bind " \
5107 " {start|stop|restart|reload|force-reload}" >&2
5117 Complementing the above init script is a configuration
5118 file <file>/etc/default/bind</file>, which contains
5119 configurable parameters used by the script. This would be
5120 created by the <prgn>postinst</prgn> script if it was not
5121 already present, and removed on purge by the
5122 <prgn>postrm</prgn> script.
5123 <example compact="compact">
5124 # Specified parameters to pass to named. See named(8).
5125 # You may uncomment the following line, and edit to taste.
5131 Another example on which you can base your
5132 <file>/etc/init.d</file> scripts is found in
5133 <file>/etc/init.d/skeleton</file>.
5137 If this package is happy with the default setup from
5138 <prgn>update-rc.d</prgn>, namely an ordering number of 20
5139 and having named running in all runlevels, it can say in
5140 its <prgn>postinst</prgn>:
5141 <example compact="compact">
5142 update-rc.d bind defaults >/dev/null
5144 And in its <prgn>postrm</prgn>, to remove the links when the
5146 <example compact="compact">
5147 if [ "$1" = purge ]; then
5148 update-rc.d bind remove >/dev/null
5156 <heading>Console messages from <file>init.d</file> scripts</heading>
5159 This section describes the formats to be used for messages
5160 written to standard output by the <file>/etc/init.d</file>
5161 scripts. The intent is to improve the consistency of
5162 Debian's startup and shutdown look and feel. For this
5163 reason, please look very carefully at the details. We want
5164 the messages to have the same format in terms of wording,
5165 spaces, punctuation and case of letters.
5169 Here is a list of overall rules that you should use when you
5170 create output messages. They can be useful if you have a
5171 non-standard message that is not covered specifically in the
5179 Every message should fit in one line (fewer than 80
5180 characters), start with a capital letter and end with
5181 a period (<tt>.</tt>) and line feed (<tt>"\n"</tt>).
5187 If you want to express that the computer is working on
5188 something (that is, performing a specific task, not
5189 starting or stopping a program), we use an "ellipsis"
5190 (three dots: <tt>...</tt>). Note that we don't insert
5191 spaces before or after the dots. If the task has been
5192 completed we write <tt>done.</tt> and a line feed.
5198 Design your messages as if the computer is telling you
5199 what he is doing (let him be polite :-), but don't
5200 mention "him" directly. For example, if you think of
5202 <example compact="compact">
5203 I'm starting network daemons: nfsd mountd.
5206 <example compact="compact">
5207 Starting network daemons: nfsd mountd.
5215 There are standard message formats for the following
5216 situations. They should be used by the <tt>init.d</tt>
5223 <p>When daemons are started</p>
5226 If your script starts one or more daemons, the output
5227 should look like this (a single line, no leading
5229 <example compact="compact">
5230 Starting <var>description</var>: <var>daemon-1</var> ... <var>daemon-n</var>.
5232 The <var>description</var> should describe the
5233 subsystem the daemon or set of daemons are part of,
5234 while <var>daemon-1</var> up to <var>daemon-n</var>
5235 denote each daemon's name (typically the file name of
5240 For example, the output of <file>/etc/init.d/lpd</file>
5242 <example compact="compact">
5243 Starting printer spooler: lpd.
5248 This can be achieved by saying
5249 <example compact="compact">
5250 echo -n "Starting printer spooler: lpd"
5251 start-stop-daemon --start --quiet --exec /usr/sbin/lpd
5254 in the script. If you have more than one daemon to
5255 start, you should do the following:
5256 <example compact="compact">
5257 echo -n "Starting remote file system services:"
5258 echo -n " nfsd"; start-stop-daemon --start --quiet nfsd
5259 echo -n " mountd"; start-stop-daemon --start --quiet mountd
5260 echo -n " ugidd"; start-stop-daemon --start --quiet ugidd
5263 This makes it possible for the user to see what takes
5264 so long and when the final daemon has been started.
5265 You should be careful where to put spaces: in the
5266 example above the system administrator can easily
5267 comment out a line if he don't wants to start a
5268 specific daemon, while the displayed message still
5274 <p>When a system parameter is being set</p>
5277 If you have to set up different system parameters
5278 during the system boot, you should use this format:
5279 <example compact="compact">
5280 Setting <var>parameter</var> to "<var>value</var>".
5285 You can use a statement such as the following to get
5287 <example compact="compact">
5288 echo "Setting DNS domainname to \"$domainname\"."
5293 Note that the same symbol (<tt>"</tt>) is used for the left
5294 and right quotation marks. A grave accent (<tt>`</tt>) is
5295 not a quote character; neither is an apostrophe
5301 <p>When a daemon is stopped or restarted</p>
5304 When you stop or restart a daemon, you should issue a
5305 message identical to the startup message, except that
5306 <tt>Starting</tt> is replaced with <tt>Stopping</tt>
5307 or <tt>Restarting</tt> respectively.
5311 For example, stopping the printer daemon will like
5313 <example compact="compact">
5314 Stopping printer spooler: lpd.
5320 <p>When something is executed</p>
5323 There are several examples where you have to run a
5324 program at system startup or shutdown to perform a
5325 specific task, for example, setting the system's clock
5326 using <prgn>netdate</prgn> or killing all processes
5327 when the system shuts down. Your message should look
5329 <example compact="compact">
5330 Doing something very useful...done.
5332 You should print the <tt>done.</tt> immediately after
5333 the job has been completed, so that the user is
5334 informed why she has to wait. You can get this
5336 <example compact="compact">
5337 echo -n "Doing something very useful..."
5346 <p>When the configuration is reloaded</p>
5349 When a daemon is forced to reload its configuration
5350 files you should use the following format:
5351 <example compact="compact">
5352 Reloading <var>description</var> configuration...done.
5354 where <var>description</var> is the same as in the
5355 daemon starting message.
5363 <heading>Cron jobs</heading>
5366 Packages must not modify the configuration file
5367 <file>/etc/crontab</file>, and they must not modify the files in
5368 <file>/var/spool/cron/crontabs</file>.</p>
5371 If a package wants to install a job that has to be executed
5372 via cron, it should place a file with the name of the
5373 package in one or more of the following directories:
5374 <example compact="compact">
5379 As these directory names imply, the files within them are
5380 executed on a daily, weekly, or monthly basis,
5381 respectively. The exact times are listed in
5382 <file>/etc/crontab</file>.</p>
5385 All files installed in any of these directories must be
5386 scripts (e.g., shell scripts or Perl scripts) so that they
5387 can easily be modified by the local system administrator.
5388 In addition, they should be treated as configuration
5393 If a certain job has to be executed more frequently than
5394 daily, the package should install a file
5395 <file>/etc/cron.d/<var>package</var></file>. This file uses the
5396 same syntax as <file>/etc/crontab</file> and is processed by
5397 <prgn>cron</prgn> automatically. The file must also be
5398 treated as a configuration file. (Note that entries in the
5399 <file>/etc/cron.d</file> directory are not handled by
5400 <prgn>anacron</prgn>. Thus, you should only use this
5401 directory for jobs which may be skipped if the system is not
5405 The scripts or crontab entries in these directories should
5406 check if all necessary programs are installed before they
5407 try to execute them. Otherwise, problems will arise when a
5408 package was removed but not purged since configuration files
5409 are kept on the system in this situation.</p>
5413 <heading>Menus</heading>
5416 The Debian <tt>menu</tt> package provides a standard
5417 interface between packages providing applications and
5418 documents, and <em>menu programs</em> (either X window
5419 managers or text-based menu programs such as
5420 <prgn>pdmenu</prgn>).
5424 All packages that provide applications that need not be
5425 passed any special command line arguments for normal
5426 operation should register a menu entry for those
5427 applications, so that users of the <tt>menu</tt> package
5428 will automatically get menu entries in their window
5429 managers, as well in shells like <tt>pdmenu</tt>.
5433 Menu entries should follow the current menu policy.
5437 The menu policy can be found in the <tt>menu-policy</tt>
5438 files in the <tt>debian-policy</tt> package.
5439 They are also available from the Debian web mirrors at
5440 <tt><url name="/doc/packaging-manuals/menu-policy/"
5441 id="http://www.debian.org/doc/packaging-manuals/menu-policy/"></tt>
5442 and from the Debian archive mirrors at
5443 <tt><url name="/doc/package-developer/menu-policy.txt.gz"
5444 id="http://ftp.debian.org/debian/doc/package-developer/menu-policy.txt.gz"></tt>.
5448 Please also refer to the <em>Debian Menu System</em>
5449 documentation that comes with the <tt>menu</tt> package for
5450 information about how to register your applications and web
5456 <heading>Multimedia handlers</heading>
5459 MIME (Multipurpose Internet Mail Extensions, RFCs 2045-2049)
5460 is a mechanism for encoding files and data streams and
5461 providing meta-information about them, in particular their
5462 type (e.g. audio or video) and format (e.g. PNG, HTML,
5467 Registration of MIME type handlers allows programs like mail
5468 user agents and web browsers to to invoke these handlers to
5469 view, edit or display MIME types they don't support
5474 Packages which provide the ability to view/show/play,
5475 compose, edit or print MIME types should register themselves
5476 as such following the current MIME support policy.
5480 The MIME support policy can be found in the <tt>mime-policy</tt>
5481 files in the <tt>debian-policy</tt> package.
5482 They are also available from the Debian web mirrors at
5483 <tt><url name="/doc/packaging-manuals/mime-policy/"
5484 id="http://www.debian.org/doc/packaging-manuals/mime-policy/"></tt>
5485 and from the Debian archive mirrors at
5486 <tt><url name="/doc/package-developer/mime-policy.txt.gz"
5487 id="http://ftp.debian.org/debian/doc/package-developer/mime-policy.txt.gz"></tt>.
5493 <heading>Keyboard configuration</heading>
5496 To achieve a consistent keyboard configuration so that all
5497 applications interpret a keyboard event the same way, all
5498 programs in the Debian distribution must be configured to
5499 comply with the following guidelines.
5503 The following keys must have the specified interpretations:
5506 <tag><tt><--</tt></tag>
5507 <item><p>delete the character to the left of the cursor</p></item>
5509 <tag><tt>Delete</tt></tag>
5510 <item><p>delete the character to the right of the cursor</p></item>
5512 <tag><tt>Control+H</tt></tag>
5513 <item><p>emacs: the help prefix</p></item>
5516 The interpretation of any keyboard events should be
5517 independent of the terminal that is used, be it a virtual
5518 console, an X terminal emulator, an rlogin/telnet session,
5523 The following list explains how the different programs
5524 should be set up to achieve this:
5529 <item><p><tt><--</tt> generates <tt>KB_BackSpace</tt>
5532 <item><p><tt>Delete</tt> generates <tt>KB_Delete</tt> in
5537 X translations are set up to make
5538 <tt>KB_Backspace</tt> generate ASCII DEL, and to make
5539 <tt>KB_Delete</tt> generate <tt>ESC [ 3 ~</tt> (this
5540 is the vt220 escape code for the "delete character"
5541 key). This must be done by loading the X resources
5542 using <prgn>xrdb</prgn> on all local X displays, not
5543 using the application defaults, so that the
5544 translation resources used correspond to the
5545 <prgn>xmodmap</prgn> settings.</p></item>
5549 The Linux console is configured to make
5550 <tt><--</tt> generate DEL, and <tt>Delete</tt>
5551 generate <tt>ESC [ 3 ~</tt>.</p></item>
5555 X applications are configured so that <tt><</tt>
5556 deletes left, and <tt>Delete</tt> deletes right. Motif
5557 applications already work like this.</p></item>
5559 <item><p>Terminals should have <tt>stty erase ^?</tt> .</p></item>
5563 The <tt>xterm</tt> terminfo entry should have <tt>ESC
5564 [ 3 ~</tt> for <tt>kdch1</tt>, just as for
5565 <tt>TERM=linux</tt> and <tt>TERM=vt220</tt>.</p></item>
5569 Emacs is programmed to map <tt>KB_Backspace</tt> or
5570 the <tt>stty erase</tt> character to
5571 <tt>delete-backward-char</tt>, and <tt>KB_Delete</tt>
5572 or <tt>kdch1</tt> to <tt>delete-forward-char</tt>, and
5573 <tt>^H</tt> to <tt>help</tt> as always.</p></item>
5577 Other applications use the <tt>stty erase</tt>
5578 character and <tt>kdch1</tt> for the two delete keys,
5579 with ASCII DEL being "delete previous character" and
5580 <tt>kdch1</tt> being "delete character under
5587 This will solve the problem except for the following
5595 Some terminals have a <tt><--</tt> key that cannot
5596 be made to produce anything except <tt>^H</tt>. On
5597 these terminals Emacs help will be unavailable on
5598 <tt>^H</tt> (assuming that the <tt>stty erase</tt>
5599 character takes precedence in Emacs, and has been set
5600 correctly). <tt>M-x help</tt> or <tt>F1</tt> (if
5601 available) can be used instead.</p></item>
5605 Some operating systems use <tt>^H</tt> for <tt>stty
5606 erase</tt>. However, modern telnet versions and all
5607 rlogin versions propagate <tt>stty</tt> settings, and
5608 almost all UNIX versions honour <tt>stty erase</tt>.
5609 Where the <tt>stty</tt> settings are not propagated
5610 correctly, things can be made to work by using
5611 <tt>stty</tt> manually.</p></item>
5615 Some systems (including previous Debian versions) use
5616 <prgn>xmodmap</prgn> to arrange for both
5617 <tt><--</tt> and <tt>Delete</tt> to generate
5618 <tt>KB_Delete</tt>. We can change the behavior of
5619 their X clients using the same X resources that we use
5620 to do it for our own clients, or configure our clients
5621 using their resources when things are the other way
5622 around. On displays configured like this
5623 <tt>Delete</tt> will not work, but <tt><--</tt>
5628 Some operating systems have different <tt>kdch1</tt>
5629 settings in their <tt>terminfo</tt> database for
5630 <tt>xterm</tt> and others. On these systems the
5631 <tt>Delete</tt> key will not work correctly when you
5632 log in from a system conforming to our policy, but
5633 <tt><--</tt> will.</p></item>
5639 <heading>Environment variables</heading>
5642 A program must not depend on environment variables to get
5643 reasonable defaults. (That's because these environment
5644 variables would have to be set in a system-wide
5645 configuration file like <file>/etc/profile</file>, which is not
5646 supported by all shells.)</p>
5649 If a program usually depends on environment variables for its
5650 configuration, the program should be changed to fall back to
5651 a reasonable default configuration if these environment
5652 variables are not present. If this cannot be done easily
5653 (e.g., if the source code of a non-free program is not
5654 available), the program must be replaced by a small
5655 "wrapper" shell script which sets the environment variables
5656 if they are not already defined, and calls the original program.</p>
5659 Here is an example of a wrapper script for this purpose:
5661 <example compact="compact">
5663 BAR=${BAR:-/var/lib/fubar}
5665 exec /usr/lib/foo/foo "$@"
5670 Furthermore, as <file>/etc/profile</file> is a configuration
5671 file of the <prgn>base-files</prgn> package, other packages must not
5672 put any environment variables or other commands into that
5678 <heading>Files</heading>
5681 <heading>Binaries</heading>
5684 Two different packages must not install programs with
5685 different functionality but with the same filenames. (The
5686 case of two programs having the same functionality but
5687 different implementations is handled via "alternatives" or
5688 the "Conflicts" mechanism. See <ref id="maintscripts"> and
5689 <ref id="conflicts"> respectively.) If this case happens,
5690 one of the programs must be renamed. The maintainers should
5691 report this to the <tt>debian-devel</tt> mailing list and
5692 try to find a consensus about which program will have to be
5693 renamed. If a consensus cannot be reached, <em>both</em>
5694 programs must be renamed.
5698 By default, when a package is being built, any binaries
5699 created should include debugging information, as well as
5700 being compiled with optimization. You should also turn on
5701 as many reasonable compilation warnings as possible; this
5702 makes life easier for porters, who can then look at build
5703 logs for possible problems. For the C programming language,
5704 this means the following compilation parameters should be
5706 <example compact="compact">
5708 CFLAGS = -O2 -g -Wall # sane warning options vary between programs
5710 install -s # (or use strip on the files in debian/tmp)
5715 Note that by default all installed binaries should be stripped,
5716 either by using the <tt>-s</tt> flag to
5717 <prgn>install</prgn>, or by calling <prgn>strip</prgn> on
5718 the binaries after they have been copied into
5719 <file>debian/tmp</file> but before the tree is made into a
5723 Although binaries in the build tree should be compiled with
5724 debugging information by default, it can often be difficult
5725 to debug programs if they are also subjected to compiler
5726 optimization. For this reason, it is recommended to support
5727 the standardized environment
5728 variable <tt>DEB_BUILD_OPTIONS</tt>. This variable can
5729 contain several flags to change how a package is compiled
5737 The presence of this string means that the package
5738 should be complied with a minimum of optimization.
5739 For C programs, it is best to add <tt>-O0</tt>
5740 to <tt>CFLAGS</tt> (although this is usually the
5741 default). Some programs might fail to build or run at
5742 this level of optimization; it may be necessary to
5743 use <tt>-O1</tt>, for example.
5749 This string means that the debugging symbols should
5750 not be stripped from the binary during installation,
5751 so that debugging information may be included in the package.
5757 The following makefile snippet is an example of how one may
5758 implement the build options; you will probably have to
5759 massage this example in order to make it work for your
5761 <example compact="compact">
5764 INSTALL_FILE = $(INSTALL) -p -o root -g root -m 644
5765 INSTALL_PROGRAM = $(INSTALL) -p -o root -g root -m 755
5766 INSTALL_SCRIPT = $(INSTALL) -p -o root -g root -m 755
5767 INSTALL_DIR = $(INSTALL) -p -d -o root -g root -m 755
5769 ifneq (,$(findstring noopt,$(DEB_BUILD_OPTIONS)))
5774 ifeq (,$(findstring nostrip,$(DEB_BUILD_OPTIONS)))
5775 INSTALL_PROGRAM += -s
5781 It is up to the package maintainer to decide what
5782 compilation options are best for the package. Certain
5783 binaries (such as computationally-intensive programs) will
5784 function better with certain flags (<tt>-O3</tt>, for
5785 example); feel free to use them. Please use good judgment
5786 here. Don't use flags for the sake of it; only use them
5787 if there is good reason to do so. Feel free to override
5788 the upstream author's ideas about which compilation
5789 options are best: they are often inappropriate for our
5795 <sect id="libraries">
5796 <heading>Libraries</heading>
5799 The shared version of a library must be compiled with
5800 <tt>-fPIC</tt>, and the static version must not be. In other
5801 words, each source unit (<tt>*.c</tt>, for example, for C files)
5802 will need to be compiled twice.
5807 You must specify the gcc option <tt>-D_REENTRANT</tt>
5808 when building a library (either static or shared) to make
5809 the library compatible with LinuxThreads.
5813 All installed shared libraries should be stripped with
5814 <example compact="compact">
5815 strip --strip-unneeded <var>your-lib</var>
5817 (The option <tt>--strip-unneeded</tt> makes
5818 <prgn>strip</prgn> remove only the symbols which aren't
5819 needed for relocation processing.) Shared libraries can
5820 function perfectly well when stripped, since the symbols for
5821 dynamic linking are in a separate part of the ELF object
5824 You might also want to use the options
5825 <tt>--remove-section=.comment</tt> and
5826 <tt>--remove-section=.note</tt> on both shared libraries
5827 and executables, and <tt>--strip-debug</tt> on static
5834 Note that under some circumstances it may be useful to
5835 install a shared library unstripped, for example when
5836 building a separate package to support debugging.
5840 Shared object files (often <file>.so</file> files) that are not
5841 public libraries, that is, they are not meant to be linked
5842 to by third party executables (binaries of other packages),
5843 should be installed in subdirectories of the
5844 <file>/usr/lib</file> directory. Such files are exempt from the
5845 rules that govern ordinary shared libraries, except that
5846 they must not be installed executable and should be
5849 A common example are the so-called "plug-ins",
5850 internal shared objects that are dynamically loaded by
5851 programs using <manref name="dlopen" section="3">.
5857 Packages containing shared libraries that may be linked to
5858 by other packages' binaries, but which for some
5859 <em>compelling</em> reason can not be installed in
5860 <file>/usr/lib</file> directory, may install the shared library
5861 files in subdirectories of the <file>/usr/lib</file> directory,
5862 in which case they should arrange to add that directory in
5863 <file>/etc/ld.so.conf</file> in the package's post-installation
5864 script, and remove it in the package's post-removal script.
5868 An ever increasing number of packages are using
5869 <prgn>libtool</prgn> to do their linking. The latest GNU
5870 libtools (>= 1.3a) can take advantage of the metadata in the
5871 installed <prgn>libtool</prgn> archive files (<file>*.la</file>
5872 files). The main advantage of <prgn>libtool</prgn>'s
5873 <file>.la</file> files is that it allows <prgn>libtool</prgn> to
5874 store and subsequently access metadata with respect to the
5875 libraries it builds. <prgn>libtool</prgn> will search for
5876 those files, which contain a lot of useful information about
5877 a library (such as library dependency information for static
5878 linking). Also, they're <em>essential</em> for programs
5879 using <tt>libltdl</tt>.<footnote>
5881 Although <prgn>libtool</prgn> is fully capable of
5882 linking against shared libraries which don't have
5883 <tt>.la</tt> files, as it is a mere shell script it can
5884 add considerably to the build time of a
5885 <prgn>libtool</prgn>-using package if that shell script
5886 has to derive all this information from first principles
5887 for each library every time it is linked. With the
5888 advent of <prgn>libtool</prgn> version 1.4 (and to a
5889 lesser extent <prgn>libtool</prgn> version 1.3), the
5890 <file>.la</file> files also store information about
5891 inter-library dependencies which cannot necessarily be
5892 derived after the <file>.la</file> file is deleted.
5898 Packages that use <prgn>libtool</prgn> to create shared
5899 libraries should include the <file>.la</file> files in the
5900 <tt>-dev</tt> package, unless the package relies on
5901 <tt>libtool</tt>'s <tt>libltdl</tt> library, in which case
5902 the <tt>.la</tt> files must go in the run-time library
5907 You must make sure that you use only released versions of
5908 shared libraries to build your packages; otherwise other
5909 users will not be able to run your binaries
5910 properly. Producing source packages that depend on
5911 unreleased compilers is also usually a bad
5918 <heading>Shared libraries</heading>
5920 This section has moved to <ref id="sharedlibs">.
5926 <heading>Scripts</heading>
5929 All command scripts, including the package maintainer
5930 scripts inside the package and used by <prgn>dpkg</prgn>,
5931 should have a <tt>#!</tt> line naming the shell to be used
5932 to interpret them.</p>
5935 In the case of Perl scripts this should be
5936 <tt>#!/usr/bin/perl</tt>.</p>
5939 Shell scripts (<prgn>sh</prgn> and <prgn>bash</prgn>)
5940 should almost certainly start with <tt>set -e</tt> so that
5941 errors are detected. Every script should use
5942 <tt>set -e</tt> or check the exit status of <em>every</em>
5946 The standard shell interpreter <file>/bin/sh</file> can be a
5947 symbolic link to any POSIX compatible shell, if <tt>echo
5948 -n</tt> does not generate a newline.<footnote>
5950 Debian policy specifies POSIX behavior for
5951 <file>/bin/sh</file>, but <tt>echo -n</tt> has widespread
5952 use in the Linux community (in particular including this
5953 policy, the Linux kernel source, many Debian scripts,
5954 etc.). This <tt>echo -n</tt> mechanism is valid but not
5955 required under POSIX, hence this explicit addition.
5956 Also, rumour has it that this shall be mandated under
5960 Thus, shell scripts specifying <file>/bin/sh</file> as
5961 interpreter should only use POSIX features. If a script
5962 requires non-POSIX features from the shell interpreter, the
5963 appropriate shell must be specified in the first line of the
5964 script (e.g., <tt>#!/bin/bash</tt>) and the package must
5965 depend on the package providing the shell (unless the shell
5966 package is marked "Essential", as in the case of
5971 You may wish to restrict your script to POSIX features when
5972 possible so that it may use <file>/bin/sh</file> as its
5973 interpreter. If your script works with <prgn>dash</prgn>
5974 (originally called <prgn>ash</prgn>), it's probably POSIX
5975 compliant, but if you are in doubt, use
5976 <file>/bin/bash</file>.
5980 Perl scripts should check for errors when making any
5981 system calls, including <tt>open</tt>, <tt>print</tt>,
5982 <tt>close</tt>, <tt>rename</tt> and <tt>system</tt>.
5986 <prgn>csh</prgn> and <prgn>tcsh</prgn> should be avoided as
5987 scripting languages. See <em>Csh Programming Considered
5988 Harmful</em>, one of the <tt>comp.unix.*</tt> FAQs, which
5989 can be found at <url
5990 id="http://language.perl.com/versus/csh.whynot">.<footnote>
5992 It can also be found on
5993 <url id="http://www.cpan.org/doc/FMTEYEWTK/versus/csh.whynot">
5994 or on the ftp site <ftpsite>ftp.cpan.org</ftpsite> as
5995 <ftppath>/pub/perl/CPAN/doc/FMTEYEWTK/versus/csh.whynot</ftppath>.
5998 If an upstream package comes with <prgn>csh</prgn> scripts
5999 then you must make sure that they start with
6000 <tt>#!/bin/csh</tt> and make your package depend on the
6001 <prgn>c-shell</prgn> virtual package.
6005 Any scripts which create files in world-writeable
6006 directories (e.g., in <file>/tmp</file>) must use a
6007 mechanism which will fail if a file with the same name
6011 The Debian base system provides the <prgn>tempfile</prgn>
6012 and <prgn>mktemp</prgn> utilities for use by scripts for
6013 this purpose.</p></sect>
6017 <heading>Symbolic links</heading>
6020 In general, symbolic links within a top-level directory
6021 should be relative, and symbolic links pointing from one
6022 top-level directory into another should be absolute. (A
6023 top-level directory is a sub-directory of the root
6024 directory <file>/</file>.)</p>
6027 In addition, symbolic links should be specified as short as
6028 possible, i.e., link targets like <file>foo/../bar</file> are
6032 Note that when creating a relative link using
6033 <prgn>ln</prgn> it is not necessary for the target of the
6034 link to exist relative to the working directory you're
6035 running <prgn>ln</prgn> from, nor is it necessary to change
6036 directory to the directory where the link is to be made.
6037 Simply include the string that should appear as the target
6038 of the link (this will be a pathname relative to the
6039 directory in which the link resides) as the first argument
6040 to <prgn>ln</prgn>.</p>
6043 For example, in your <prgn>Makefile</prgn> or
6044 <file>debian/rules</file>, you can do things like:
6045 <example compact="compact">
6046 ln -fs gcc $(prefix)/bin/cc
6047 ln -fs gcc debian/tmp/usr/bin/cc
6048 ln -fs ../sbin/sendmail $(prefix)/bin/runq
6049 ln -fs ../sbin/sendmail debian/tmp/usr/bin/runq
6053 A symbolic link pointing to a compressed file should always
6054 have the same file extension as the referenced file. (For
6055 example, if a file <file>foo.gz</file> is referenced by a
6056 symbolic link, the filename of the link has to end with
6057 "<file>.gz</file>" too, as in <file>bar.gz</file>.)
6062 <heading>Device files</heading>
6065 Packages must not include device files in the package file
6069 If a package needs any special device files that are not
6070 included in the base system, it must call
6071 <prgn>MAKEDEV</prgn> in the <prgn>postinst</prgn> script,
6072 after notifying the user<footnote>
6074 This notification could be done via a (low-priority)
6075 debconf message, or an echo (printf) statement.
6081 Packages must not remove any device files in the
6082 <prgn>postrm</prgn> or any other script. This is left to the
6083 system administrator.</p>
6086 Debian uses the serial devices
6087 <file>/dev/ttyS*</file>. Programs using the old
6088 <file>/dev/cu*</file> devices should be changed to use
6089 <file>/dev/ttyS*</file>.</p>
6092 <sect id="config-files">
6093 <heading>Configuration files</heading>
6095 <heading>Definitions</heading>
6098 <tag>configuration file</tag>
6101 A file that affects the operation of a program, or
6102 provides site- or host-specific information, or
6103 otherwise customizes the behavior of a program.
6104 Typically, configuration files are intended to be
6105 modified by the system administrator (if needed or
6106 desired) to conform to local policy or to provide
6107 more useful site-specific behavior.
6111 <tag><tt>conffile</tt></tag>
6114 A file listed in a package's <tt>conffiles</tt>
6115 file, and is treated specially by <prgn>dpkg</prgn>
6116 (see <ref id="configdetails">).
6123 The distinction between these two is important; they are
6124 not interchangeable concepts. Almost all
6125 <tt>conffile</tt>s are configuration files, but many
6126 configuration files are not <tt>conffiles</tt>.
6130 Note that a script that embeds configuration information
6131 (such as most of the files in <file>/etc/default</file> and
6132 <file>/etc/cron.{daily,weekly,monthly}</file>) is de-facto a
6133 configuration file and should be treated as such.
6138 <heading>Location</heading>
6140 Any configuration files created or used by your package
6141 must reside in <file>/etc</file>. If there are several,
6142 consider creating a subdirectory of <file>/etc</file>
6143 named after your package.</p>
6146 If your package creates or uses configuration files
6147 outside of <file>/etc</file>, and it is not feasible to modify
6148 the package to use <file>/etc</file> directly, put the files
6149 in <file>/etc</file> and create symbolic links to those files
6150 from the location that the package requires.</p>
6154 <heading>Behavior</heading>
6156 Configuration file handling must conform to the following
6158 <list compact="compact">
6161 local changes must be preserved during a package
6167 configuration files must be preserved when the
6168 package is removed, and only deleted when the
6176 The easy way to achieve this behavior is to make the
6177 configuration file a <tt>conffile</tt>. This is
6178 appropriate only if it is possible to distribute a default
6179 version that will work for most installations, although
6180 some system administrators may choose to modify it. This
6181 implies that the default version will be part of the
6182 package distribution, and must not be modified by the
6183 maintainer scripts during installation (or at any other
6188 In order to ensure that local changes are preserved
6189 correctly, no package may contain or make hard links to
6190 conffiles.<footnote>
6192 Rationale: There are two problems with hard links.
6193 The first is that some editors break the link while
6194 editing one of the files, so that the two files may
6195 unwittingly become unlinked and different. The second
6196 is that <prgn>dpkg</prgn> might break the hard link
6197 while upgrading <tt>conffile</tt>s.
6203 The other way to do it is via the maintainer scripts. In
6204 this case, the configuration file must not be listed as a
6205 <tt>conffile</tt> and must not be part of the package
6206 distribution. If the existence of a file is required for
6207 the package to be sensibly configured it is the
6208 responsibility of the package maintainer to provide
6209 maintainer scripts which correctly create, update and
6210 maintain the file and remove it on purge. (See <ref
6211 id="maintainerscripts"> for more information.) These
6212 scripts must be idempotent (i.e., must work correctly if
6213 <prgn>dpkg</prgn> needs to re-run them due to errors
6214 during installation or removal), must cope with all the
6215 variety of ways <prgn>dpkg</prgn> can call maintainer
6216 scripts, must not overwrite or otherwise mangle the user's
6217 configuration without asking, must not ask unnecessary
6218 questions (particularly during upgrades), and otherwise be
6223 The scripts are not required to configure every possible
6224 option for the package, but only those necessary to get
6225 the package running on a given system. Ideally the
6226 sysadmin should not have to do any configuration other
6227 than that done (semi-)automatically by the
6228 <prgn>postinst</prgn> script.
6232 A common practice is to create a script called
6233 <file><var>package</var>-configure</file> and have the
6234 package's <prgn>postinst</prgn> call it if and only if the
6235 configuration file does not already exist. In certain
6236 cases it is useful for there to be an example or template
6237 file which the maintainer scripts use. Such files should
6238 be in <file>/usr/share/<var>package</var></file> or
6239 <file>/usr/lib/<var>package</var></file> (depending on whether
6240 they are architecture-independent or not). There should
6241 be symbolic links to them from
6242 <file>/usr/share/doc/<var>package</var>/examples</file> if
6243 they are examples, and should be perfectly ordinary
6244 <prgn>dpkg</prgn>-handled files (<em>not</em>
6245 configuration files).
6249 These two styles of configuration file handling must
6250 not be mixed, for that way lies madness:
6251 <prgn>dpkg</prgn> will ask about overwriting the file
6252 every time the package is upgraded.
6257 <heading>Sharing configuration files</heading>
6259 Packages which specify the same file as a
6260 <tt>conffile</tt> must be tagged as <em>conflicting</em>
6261 with each other. (This is an instance of the general rule
6262 about not sharing files. Note that neither alternatives
6263 nor diversions are likely to be appropriate in this case;
6264 in particular, <prgn>dpkg</prgn> does not handle diverted
6265 <tt>conffile</tt>s well.)
6269 The maintainer scripts must not alter a <tt>conffile</tt>
6270 of <em>any</em> package, including the one the scripts
6275 If two or more packages use the same configuration file
6276 and it is reasonable for both to be installed at the same
6277 time, one of these packages must be defined as
6278 <em>owner</em> of the configuration file, i.e., it will be
6279 the package which handles that file as a configuration
6280 file. Other packages that use the configuration file must
6281 depend on the owning package if they require the
6282 configuration file to operate. If the other package will
6283 use the configuration file if present, but is capable of
6284 operating without it, no dependency need be declared.</p>
6287 If it is desirable for two or more related packages to
6288 share a configuration file <em>and</em> for all of the
6289 related packages to be able to modify that configuration
6290 file, then the following should be done:
6291 <enumlist compact="compact">
6294 One of the related packages (the "owning" package)
6295 will manage the configuration file with maintainer
6296 scripts as described in the previous section.
6301 The owning package should also provide a program
6302 that the other packages may use to modify the
6308 The related packages must use the provided program
6309 to make any desired modifications to the
6310 configuration file. They should either depend on
6311 the core package to guarantee that the configuration
6312 modifier program is available or accept gracefully
6313 that they cannot modify the configuration file if it
6314 is not. (This is in addition to the fact that the
6315 configuration file may not even be present in the
6323 Sometimes it's appropriate to create a new package which
6324 provides the basic infrastructure for the other packages
6325 and which manages the shared configuration files. (The
6326 <tt>sgml-base</tt> package is a good example.)
6331 <heading>User configuration files ("dotfiles")</heading>
6334 The files in <file>/etc/skel</file> will automatically be
6335 copied into new user accounts by <prgn>adduser</prgn>.
6336 No other program should reference the files in
6337 <file>/etc/skel</file>.
6341 Therefore, if a program needs a dotfile to exist in
6342 advance in <file>$HOME</file> to work sensibly, that dotfile
6343 should be installed in <file>/etc/skel</file> and treated as a
6348 However, programs that require dotfiles in order to
6349 operate sensibly are a bad thing, unless they do create
6350 the dotfiles themselves automatically.
6354 Furthermore, programs should be configured by the Debian
6355 default installation to behave as closely to the upstream
6356 default behaviour as possible.
6360 Therefore, if a program in a Debian package needs to be
6361 configured in some way in order to operate sensibly, that
6362 should be done using a site-wide configuration file placed
6363 in <file>/etc</file>. Only if the program doesn't support a
6364 site-wide default configuration and the package maintainer
6365 doesn't have time to add it may a default per-user file be
6366 placed in <file>/etc/skel</file>.
6370 <file>/etc/skel</file> should be as empty as we can make it.
6371 This is particularly true because there is no easy (or
6372 necessarily desirable) mechanism for ensuring that the
6373 appropriate dotfiles are copied into the accounts of
6374 existing users when a package is installed.
6380 <heading>Log files</heading>
6382 Log files should usually be named
6383 <file>/var/log/<var>package</var>.log</file>. If you have many
6384 log files, or need a separate directory for permission
6385 reasons (<file>/var/log</file> is writable only by
6386 <file>root</file>), you should usually create a directory named
6387 <file>/var/log/<var>package</var></file> and place your log
6392 Log files must be rotated occasionally so that they don't
6393 grow indefinitely; the best way to do this is to drop a log
6394 rotation configuration file into the directory
6395 <file>/etc/logrotate.d</file> and use the facilities provided by
6396 logrotate.<footnote>
6398 The traditional approach to log files has been to set up
6399 <em>ad hoc</em> log rotation schemes using simple shell
6400 scripts and cron. While this approach is highly
6401 customizable, it requires quite a lot of sysadmin work.
6402 Even though the original Debian system helped a little
6403 by automatically installing a system which can be used
6404 as a template, this was deemed not enough.
6408 The use of <prgn>logrotate</prgn>, a program developed
6409 by Red Hat, is better, as it centralizes log management.
6410 It has both a configuration file
6411 (<file>/etc/logrotate.conf</file>) and a directory where
6412 packages can drop their individual log rotation
6413 configurations (<file>/etc/logrotate.d</file>).
6416 Here is a good example for a logrotate config
6417 file (for more information see <manref name="logrotate"
6419 <example compact="compact">
6420 /var/log/foo/*.log {
6425 /etc/init.d/foo force-reload
6429 This rotates all files under <file>/var/log/foo</file>, saves 12
6430 compressed generations, and forces the daemon to reload its
6431 configuration information after the log rotation.
6435 Log files should be removed when the package is
6436 purged (but not when it is only removed). This should be
6437 done by the <prgn>postrm</prgn> script when it is called
6438 with the argument <tt>purge</tt> (see <ref
6439 id="removedetails">).
6444 <heading>Permissions and owners</heading>
6447 The rules in this section are guidelines for general use.
6448 If necessary you may deviate from the details below.
6449 However, if you do so you must make sure that what is done
6450 is secure and you should try to be as consistent as possible
6451 with the rest of the system. You should probably also
6452 discuss it on <prgn>debian-devel</prgn> first.
6456 Files should be owned by <tt>root.root</tt>, and made
6457 writable only by the owner and universally readable (and
6458 executable, if appropriate), that is mode 644 or 755.
6462 Directories should be mode 755 or (for group-writability)
6463 mode 2775. The ownership of the directory should be
6464 consistent with its mode: if a directory is mode 2775, it
6465 should be owned by the group that needs write access to
6470 Setuid and setgid executables should be mode 4755 or 2755
6471 respectively, and owned by the appropriate user or group.
6472 They should not be made unreadable (modes like 4711 or
6473 2711 or even 4111); doing so achieves no extra security,
6474 because anyone can find the binary in the freely available
6475 Debian package; it is merely inconvenient. For the same
6476 reason you should not restrict read or execute permissions
6477 on non-set-id executables.
6481 Some setuid programs need to be restricted to particular
6482 sets of users, using file permissions. In this case they
6483 should be owned by the uid to which they are set-id, and by
6484 the group which should be allowed to execute them. They
6485 should have mode 4754; again there is no point in making
6486 them unreadable to those users who must not be allowed to
6491 It is possible to arrange that the system administrator can
6492 reconfigure the package to correspond to their local
6493 security policy by changing the permissions on a binary:
6494 they can do this by using <prgn>dpkg-statoverride</prgn>, as
6495 described below.<footnote>
6497 Ordinary files installed by <prgn>dpkg</prgn> (as
6498 opposed to <tt>conffile</tt>s and other similar objects)
6499 normally have their permissions reset to the distributed
6500 permissions when the package is reinstalled. However,
6501 the use of <prgn>dpkg-statoverride</prgn> overrides this
6502 default behaviour. If you use this method, you should
6503 remember to describe <prgn>dpkg-statoverride</prgn> in
6504 the package documentation; being a relatively new
6505 addition to Debian, it is probably not yet well-known.
6508 Another method you should consider is to create a group for
6509 people allowed to use the program(s) and make any setuid
6510 executables executable only by that group.
6514 If you need to create a new user or group for your package
6515 there are two possibilities. Firstly, you may need to
6516 make some files in the binary package be owned by this
6517 user or group, or you may need to compile the user or
6518 group id (rather than just the name) into the binary
6519 (though this latter should be avoided if possible, as in
6520 this case you need a statically allocated id).</p>
6523 If you need a statically allocated id, you must ask for a
6524 user or group id from the <tt>base-passwd</tt> maintainer,
6525 and must not release the package until you have been
6526 allocated one. Once you have been allocated one you must
6527 either make the package depend on a version of the
6528 <tt>base-passwd</tt> package with the id present in
6529 <file>/etc/passwd</file> or <file>/etc/group</file>, or arrange for
6530 your package to create the user or group itself with the
6531 correct id (using <tt>adduser</tt>) in its
6532 <prgn>preinst</prgn> or <prgn>postinst</prgn>. (Doing it in
6533 the <prgn>postinst</prgn> is to be preferred if it is
6534 possible, otherwise a pre-dependency will be needed on the
6535 <tt>adduser</tt> package.)
6539 On the other hand, the program might be able to determine
6540 the uid or gid from the user or group name at runtime, so
6541 that a dynamically allocated id can be used. In this case
6542 you should choose an appropriate user or group name,
6543 discussing this on <prgn>debian-devel</prgn> and checking
6544 with the <package/base-passwd/ maintainer that it is unique and that
6545 they do not wish you to use a statically allocated id
6546 instead. When this has been checked you must arrange for
6547 your package to create the user or group if necessary using
6548 <prgn>adduser</prgn> in the <prgn>preinst</prgn> or
6549 <prgn>postinst</prgn> script (again, the latter is to be
6550 preferred if it is possible).
6554 Note that changing the numeric value of an id associated
6555 with a name is very difficult, and involves searching the
6556 file system for all appropriate files. You need to think
6557 carefully whether a static or dynamic id is required, since
6558 changing your mind later will cause problems.
6561 <sect1><heading>The use of <prgn>dpkg-statoverride</prgn></heading>
6563 This section is not intended as policy, but as a
6564 description of the use of <prgn>dpkg-statoverride</prgn>.
6568 <prgn>dpkg-statoverride</prgn> is a replacement for the
6569 deprecated <tt>suidmanager</tt> package. Packages which
6570 previously used <tt>suidmanager</tt> should have a
6571 <tt>Conflicts: suidmanager (<< 0.50)</tt> entry (or even
6572 <tt>(<< 0.52)</tt>), and calls to <tt>suidregister</tt>
6573 and <tt>suidunregister</tt> should now be simply removed
6574 from the maintainer scripts.
6578 If a system administrator wishes to have a file (or
6579 directory or other such thing) installed with owner and
6580 permissions different from those in the distributed Debian
6581 package, he can use the <prgn>dpkg-statoverride</prgn>
6582 program to instruct <prgn>dpkg</prgn> to use the different
6583 settings every time the file is installed. Thus the
6584 package maintainer should distribute the files with their
6585 normal permissions, and leave it for the system
6586 administrator to make any desired changes. For example, a
6587 daemon which is normally required to be setuid root, but
6588 in certain situations could be used without being setuid,
6589 should be installed setuid in the <tt>.deb</tt>. Then the
6590 local system administrator can change this if they wish.
6591 If there are two standard ways of doing it, the package
6592 maintainer can use <tt>debconf</tt> to find out the
6593 preference, and call <prgn>dpkg-statoverride</prgn> in the
6594 maintainer script if necessary to accommodate the system
6595 administrator's choice.
6599 Given the above, <prgn>dpkg-statoverride</prgn> is
6600 essentially a tool for system administrators and would not
6601 normally be needed in the maintainer scripts. There is
6602 one type of situation, though, where calls to
6603 <prgn>dpkg-statoverride</prgn> would be needed in the
6604 maintainer scripts, and that involves packages which use
6605 dynamically allocated user or group ids. In such a
6606 situation, something like the following idiom can be very
6607 helpful in the package's <prgn>postinst</prgn>, where
6608 <tt>sysuser</tt> is a dynamically allocated id:
6610 for i in /usr/bin/foo /usr/sbin/bar
6612 if ! dpkg-statoverride --list $i >/dev/null
6614 dpkg-statoverride --update --add sysuser root 4755 $i
6618 The corresponding <tt>dpkg-statoverride --remove</tt>
6619 calls can then be made unconditionally when the package is
6626 <chapt id="customized-programs">
6627 <heading>Customized programs</heading>
6629 <sect id="arch-spec">
6630 <heading>Architecture specification strings</heading>
6633 If a program needs to specify an <em>architecture specification
6634 string</em> in some place, the following format should be
6635 used: <var>arch</var>-<var>os</var><footnote>
6637 The following architectures and operating systems are
6638 currently recognised by <prgn>dpkg-archictecture</prgn>.
6639 The architecture, <tt><var>arch</var></tt>, is one of
6640 the following: <tt>alpha</tt>, <tt>arm</tt>,
6641 <tt>hppa</tt>, <tt>i386</tt>, <tt>ia64</tt>,
6642 <tt>m68k</tt>, <tt>mips</tt>, <tt>mipsel</tt>,
6643 <tt>powerpc</tt>, <tt>s390</tt>, <tt>sh</tt>,
6644 <tt>sheb</tt>, <tt>sparc</tt> and <tt>sparc64</tt>. The
6645 operating system, <tt><var>os</var></tt>, is one of:
6646 <tt>linux</tt>, <tt>gnu</tt>, <tt>freebsd</tt> and
6647 <tt>openbsd</tt>. Use of <tt>gnu</tt> in this string is
6648 reserved for the GNU/Hurd operating system.
6654 Note that we don't want to use
6655 <tt><var>arch</var>-debian-linux</tt> to apply to the rule
6656 <tt><var>architecture</var>-<var>vendor</var>-<var>os</var></tt>
6657 since this would make our programs incompatible with other
6658 Linux distributions. We also don't use something like
6659 <tt><var>arch</var>-unknown-linux</tt>, since the
6660 <tt>unknown</tt> does not look very good.
6665 <heading>Daemons</heading>
6668 The configuration files <file>/etc/services</file>,
6669 <file>/etc/protocols</file>, and <file>/etc/rpc</file> are managed
6670 by the <prgn>netbase</prgn> package and must not be modified
6675 If a package requires a new entry in one of these files, the
6676 maintainer should get in contact with the
6677 <prgn>netbase</prgn> maintainer, who will add the entries
6678 and release a new version of the <prgn>netbase</prgn>
6683 The configuration file <file>/etc/inetd.conf</file> must not be
6684 modified by the package's scripts except via the
6685 <prgn>update-inetd</prgn> script or the
6686 <file>DebianNet.pm</file> Perl module. See their documentation
6687 for details on how to add entries.
6691 If a package wants to install an example entry into
6692 <file>/etc/inetd.conf</file>, the entry must be preceded with
6693 exactly one hash character (<tt>#</tt>). Such lines are
6694 treated as "commented out by user" by the
6695 <prgn>update-inetd</prgn> script and are not changed or
6696 activated during package updates.
6701 <heading>Using pseudo-ttys and modifying wtmp, utmp and
6705 Some programs need to create pseudo-ttys. This should be done
6706 using Unix98 ptys if the C library supports it. The resulting
6707 program must not be installed setuid root, unless that
6708 is required for other functionality.
6712 The files <file>/var/run/utmp</file>, <file>/var/log/wtmp</file> and
6713 <file>/var/log/lastlog</file> must be installed writeable by
6714 group <tt>utmp</tt>. Programs which need to modify those
6715 files must be installed setgid <tt>utmp</tt>.
6720 <heading>Editors and pagers</heading>
6723 Some programs have the ability to launch an editor or pager
6724 program to edit or display a text document. Since there are
6725 lots of different editors and pagers available in the Debian
6726 distribution, the system administrator and each user should
6727 have the possibility to choose his/her preferred editor and
6732 In addition, every program should choose a good default
6733 editor/pager if none is selected by the user or system
6738 Thus, every program that launches an editor or pager must
6739 use the EDITOR or PAGER environment variable to determine
6740 the editor or pager the user wishes to use. If these
6741 variables are not set, the programs <file>/usr/bin/editor</file>
6742 and <file>/usr/bin/pager</file> should be used, respectively.
6746 These two files are managed through the <prgn>dpkg</prgn>
6747 "alternatives" mechanism. Thus every package providing an
6748 editor or pager must call the
6749 <prgn>update-alternatives</prgn> script to register these
6754 If it is very hard to adapt a program to make use of the
6755 EDITOR or PAGER variables, that program may be configured to
6756 use <file>/usr/bin/sensible-editor</file> and
6757 <file>/usr/bin/sensible-pager</file> as the editor or pager
6758 program respectively. These are two scripts provided in the
6759 Debian base system that check the EDITOR and PAGER variables
6760 and launch the appropriate program, and fall back to
6761 <file>/usr/bin/editor</file> and <file>/usr/bin/pager</file> if the
6762 variable is not set.
6766 A program may also use the VISUAL environment variable to
6767 determine the user's choice of editor. If it exists, it
6768 should take precedence over EDITOR. This is in fact what
6769 <file>/usr/bin/sensible-editor</file> does.
6773 It is not required for a package to depend on
6774 <tt>editor</tt> and <tt>pager</tt>, nor is it required for a
6775 package to provide such virtual packages.<footnote>
6777 The Debian base system already provides an editor and a
6784 <sect id="web-appl">
6785 <heading>Web servers and applications</heading>
6788 This section describes the locations and URLs that should
6789 be used by all web servers and web applications in the
6797 Cgi-bin executable files are installed in the
6799 <example compact="compact">
6800 /usr/lib/cgi-bin/<var>cgi-bin-name</var>
6802 and should be referred to as
6803 <example compact="compact">
6804 http://localhost/cgi-bin/<var>cgi-bin-name</var>
6809 <item><p>Access to HTML documents</p>
6812 HTML documents for a package are stored in
6813 <file>/usr/share/doc/<var>package</var></file>
6814 and can be referred to as
6815 <example compact="compact">
6816 http://localhost/doc/<var>package</var>/<var>filename</var>
6820 The web server should restrict access to the document
6821 tree so that only clients on the same host can read
6822 the documents. If the web server does not support such
6823 access controls, then it should not provide access at
6824 all, or ask about providing access during installation.
6828 <item><p>Web Document Root</p>
6831 Web Applications should try to avoid storing files in
6832 the Web Document Root. Instead they should use the
6833 /usr/share/doc/<var>package</var> directory for
6834 documents and register the Web Application via the
6835 menu package. If access to the web document root is
6836 unavoidable then use
6837 <example compact="compact">
6840 as the Document Root. This might be just a symbolic
6841 link to the location where the system administrator
6842 has put the real document root.
6846 </enumlist></p></sect>
6849 <sect id="mail-transport-agents">
6850 <heading>Mail transport, delivery and user agents</heading>
6853 Debian packages which process electronic mail, whether mail
6854 user agents (MUAs) or mail transport agents (MTAs), must
6855 ensure that they are compatible with the configuration
6856 decisions below. Failure to do this may result in lost
6857 mail, broken <tt>From:</tt> lines, and other serious brain
6862 The mail spool is <file>/var/mail</file> and the interface to
6863 send a mail message is <file>/usr/sbin/sendmail</file> (as per
6864 the FHS). On older systems, the mail spool may be
6865 physically located in <file>/var/spool/mail</file>, but all
6866 access to the mail spool should be via the
6867 <file>/var/mail</file> symlink. The mail spool is part of the
6868 base system and not part of the MTA package.
6872 All Debian MUAs, MTAs, MDAs and other mailbox accessing
6873 programs (such as IMAP daemons) must lock the mailbox in an
6874 NFS-safe way. This means that <tt>fcntl()</tt> locking must
6875 be combined with dot locking. To avoid deadlocks, a program
6876 should use <tt>fcntl()</tt> first and dot locking after
6877 this, or alternatively implement the two locking methods in
6878 a non blocking way<footnote>
6880 If it is not possible to establish both locks, the
6881 system shouldn't wait for the second lock to be
6882 established, but remove the first lock, wait a (random)
6883 time, and start over locking again.
6885 </footnote>. Using the functions <tt>maillock</tt> and
6886 <tt>mailunlock</tt> provided by the
6887 <tt>liblockfile*</tt><footnote>
6889 You will need to depend on <tt>liblockfile1
6890 (>>1.01)</tt> to use these functions.
6892 </footnote> packages is the recommended way to realize this.
6896 Mailboxes are generally mode 660
6897 <tt><var>user</var>.mail</tt> unless the system
6898 administrator has chosen otherwise. A MUA may remove a
6899 mailbox (unless it has nonstandard permissions) in which
6900 case the MTA or another MUA must recreate it if needed.
6901 Mailboxes must be writable by group mail.
6905 The mail spool is 2775 <tt>root.mail</tt>, and MUAs should
6906 be setgid mail to do the locking mentioned above (and
6907 must obviously avoid accessing other users' mailboxes
6908 using this privilege).</p>
6911 <file>/etc/aliases</file> is the source file for the system mail
6912 aliases (e.g., postmaster, usenet, etc.), it is the one
6913 which the sysadmin and <prgn>postinst</prgn> scripts may
6914 edit. After <file>/etc/aliases</file> is edited the program or
6915 human editing it must call <prgn>newaliases</prgn>. All MTA
6916 packages must come with a <prgn>newaliases</prgn> program,
6917 even if it does nothing, but older MTA packages did not do
6918 this so programs should not fail if <prgn>newaliases</prgn>
6919 cannot be found. Note that because of this, all MTA
6920 packages must have <tt>Provides</tt>, <tt>Conflicts</tt> and
6921 <tt>Replaces: mail-transport-agent</tt> control file
6926 The convention of writing <tt>forward to
6927 <var>address</var></tt> in the mailbox itself is not
6928 supported. Use a <tt>.forward</tt> file instead.</p>
6931 The <prgn>rmail</prgn> program used by UUCP
6932 for incoming mail should be <file>/usr/sbin/rmail</file>.
6933 Likewise, <prgn>rsmtp</prgn>, for receiving
6934 batch-SMTP-over-UUCP, should be <file>/usr/sbin/rsmtp</file> if it
6938 If your package needs to know what hostname to use on (for
6939 example) outgoing news and mail messages which are generated
6940 locally, you should use the file <file>/etc/mailname</file>. It
6941 will contain the portion after the username and <tt>@</tt>
6942 (at) sign for email addresses of users on the machine
6943 (followed by a newline).
6947 Such package should check for the existence of this file
6948 when it is being configured. If it exists, it should be
6949 used without comment, although an MTA's configuration script
6950 may wish to prompt the user even if it finds that this file
6951 exists. If the file does not exist, the package should
6952 prompt the user for the value (preferably using
6953 <prgn>debconf</prgn>) and store it in <file>/etc/mailname</file>
6954 as well as using it in the package's configuration. The
6955 prompt should make it clear that the name will not just be
6956 used by that package. For example, in this situation the
6957 <tt>inn</tt> package could say something like:
6958 <example compact="compact">
6959 Please enter the "mail name" of your system. This is the
6960 hostname portion of the address to be shown on outgoing
6961 news and mail messages. The default is
6962 <var>syshostname</var>, your system's host name. Mail
6963 name ["<var>syshostname</var>"]:
6965 where <var>syshostname</var> is the output of <tt>hostname
6971 <heading>News system configuration</heading>
6974 All the configuration files related to the NNTP (news)
6975 servers and clients should be located under
6976 <file>/etc/news</file>.</p>
6979 There are some configuration issues that apply to a number
6980 of news clients and server packages on the machine. These
6984 <tag><file>/etc/news/organization</file></tag>
6985 <item><p>A string which should appear as the
6986 organization header for all messages posted
6987 by NNTP clients on the machine</p></item>
6989 <tag><file>/etc/news/server</file></tag>
6990 <item><p>Contains the FQDN of the upstream NNTP
6991 server, or localhost if the local machine is
6992 an NNTP server.</p></item>
6995 Other global files may be added as required for cross-package news
6996 configuration.</p></sect>
7000 <heading>Programs for the X Window System</heading>
7003 <heading>Providing X support and package priorities</heading>
7006 Programs that can be configured with support for the X
7007 Window System must be configured to do so and must declare
7008 any package dependencies necessary to satisfy their
7009 runtime requirements when using the X Window System. If
7010 such a package is of higher priority than the X packages
7011 on which it depends, it is required that either the
7012 X-specific components be split into a separate package, or
7013 that an alternative version of the package, which includes
7014 X support, be provided, or that the package's priority be
7020 <heading>Packages providing an X server</heading>
7023 Packages that provide an X server that, directly or
7024 indirectly, communicates with real input and display
7025 hardware should declare in their control data that they
7026 provide the virtual package <tt>xserver</tt>.<footnote>
7028 This implements current practice, and provides an
7029 actual policy for usage of the <tt>xserver</tt>
7030 virtual package which appears in the virtual packages
7031 list. In a nutshell, X servers that interface
7032 directly with the display and input hardware or via
7033 another subsystem (e.g., GGI) should provide
7034 <tt>xserver</tt>. Things like <tt>Xvfb</tt>,
7035 <tt>Xnest</tt>, and <tt>Xprt</tt> should not.
7042 <heading>Packages providing a terminal emulator</heading>
7045 Packages that provide a terminal emulator for the X Window
7046 System which meet the criteria listed below should declare
7047 in their control data that they provide the virtual
7048 package <tt>x-terminal-emulator</tt>. They should also
7049 register themselves as an alternative for
7050 <file>/usr/bin/x-terminal-emulator</file>, with a priority of
7055 To be an <tt>x-terminal-emulator</tt>, a program must:
7056 <list compact="compact">
7058 Be able to emulate a DEC VT100 terminal, or a
7059 compatible terminal.
7063 Support the command-line option <tt>-e
7064 <var>command</var></tt>, which creates a new
7065 terminal window<footnote>
7067 "New terminal window" does not necessarily mean
7068 a new top-level X window directly parented by
7069 the window manager; it could, if the terminal
7070 emulator application were so coded, be a new
7071 "view" in a multiple-document interface (MDI).
7074 and runs the specified <var>command</var>,
7075 interpreting the entirity of the rest of the command
7076 line as a command to pass straight to exec, in the
7077 manner that <tt>xterm</tt> does.
7081 Support the command-line option <tt>-T
7082 <var>title</var></tt>, which creates a new terminal
7083 window with the window title <var>title</var>.
7090 <heading>Packages providing a window manager</heading>
7093 Packages that provide a window manager should declare in
7094 their control data that they provide the virtual package
7095 <tt>x-window-manager</tt>. They should also register
7096 themselves as an alternative for
7097 <file>/usr/bin/x-window-manager</file>, with a priority
7098 calculated as follows:
7099 <list compact="compact">
7100 <item><p>Start with a priority of 20.</p></item>
7104 If the window manager supports the Debian menu
7105 system, add 20 points if this support is available
7106 in the package's default configuration (i.e., no
7107 configuration files belonging to the system or user
7108 have to be edited to activate the feature); if
7109 configuration files must be modified, add only 10
7115 If the window manager complies with <url
7116 id="http://www.freedesktop.org/standards/wm-spec.html"
7117 name="The Window Manager Specification Project">,
7118 written by the <url id="http://www.freedesktop.org"
7119 name="Free Desktop Group">, add 20 points.
7125 If the window manager permits the X session to be
7126 restarted using a <em>different</em> window manager
7127 (without killing the X server) in its default
7128 configuration, add 10 points; otherwise add none.
7136 <heading>Packages providing fonts</heading>
7139 Packages that provide fonts for the X Window
7142 For the purposes of Debian Policy, a "font for the X
7143 Window System" is one which is accessed via X protocol
7144 requests. Fonts for the Linux console, for PostScript
7145 renderers, or any other purpose, do not fit this
7146 definition. Any tool which makes such fonts available
7147 to the X Window System, however, must abide by this
7151 must do a number of things to ensure that they are both
7152 available without modification of the X or font server
7153 configuration, and that they do not corrupt files used by
7154 other font packages to register information about
7159 Fonts of any type supported by the X Window System
7160 must be in a separate binary package from any
7161 executables, libraries, or documentation (except
7162 that specific to the fonts shipped, such as their
7163 license information). If one or more of the fonts
7164 so packaged are necessary for proper operation of
7165 the package with which they are associated the font
7166 package may be Recommended; if the fonts merely
7167 provide an enhancement, a Suggests relationship may
7168 be used. Packages must not Depend on font
7171 This is because the X server may retrieve fonts
7172 from the local filesystem or over the network
7173 from an X font server; the Debian package system
7174 is empowered to deal only with the local
7183 BDF fonts must be converted to PCF fonts with the
7184 <prgn>bdftopcf</prgn> utility (available in the
7185 <tt>xutils</tt> package, <prgn>gzip</prgn>ped, and
7186 placed in a directory that corresponds to their
7188 <list compact="compact">
7190 100 dpi fonts must be placed in
7191 <file>/usr/X11R6/lib/X11/fonts/100dpi/</file>.
7195 75 dpi fonts must be placed in
7196 <file>/usr/X11R6/lib/X11/fonts/75dpi/</file>.
7200 Character-cell fonts, cursor fonts, and other
7201 low-resolution fonts must be placed in
7202 <file>/usr/X11R6/lib/X11/fonts/misc/</file>.
7209 Speedo fonts must be placed in
7210 <file>/usr/X11R6/lib/X11/fonts/Speedo/</file>.
7214 Type 1 fonts must be placed in
7215 <file>/usr/X11R6/lib/X11/fonts/Type1/</file>. If font
7216 metric files are available, they must be placed here
7222 Subdirectories of <file>/usr/X11R6/lib/X11/fonts/</file>
7223 other than those listed above must be neither
7224 created nor used. (The <file>PEX</file>, <file>CID</file>,
7225 and <file>cyrillic</file> directories are excepted for
7226 historical reasons, but installation of files into
7227 these directories remains discouraged.)
7233 Font packages may, instead of placing files directly
7234 in the X font directories listed above, provide
7235 symbolic links in that font directory pointing to
7236 the files' actual location in the filesystem. Such
7237 a location must comply with the FHS.
7243 Font packages should not contain both 75dpi and
7244 100dpi versions of a font. If both are available,
7245 they should be provided in separate binary packages
7246 with <tt>-75dpi</tt> or <tt>-100dpi</tt> appended to
7247 the names of the packages containing the
7248 corresponding fonts.
7254 Fonts destined for the <file>misc</file> subdirectory
7255 should not be included in the same package as 75dpi
7256 or 100dpi fonts; instead, they should be provided in
7257 a separate package with <tt>-misc</tt> appended to
7264 Font packages must not provide the files
7265 <file>fonts.dir</file>, <file>fonts.alias</file>, or
7266 <file>fonts.scale</file> in a font directory:
7269 <file>fonts.dir</file> files must not be provided at all.
7274 <file>fonts.alias</file> and <file>fonts.scale</file>
7275 files, if needed, should be provided in the
7277 <file>/etc/X11/fonts/<var>fontdir</var>/<var>package</var>.<var>extension</var></file>,
7278 where <var>fontdir</var> is the name of the
7280 <file>/usr/X11R6/lib/X11/fonts/</file> where the
7281 package's corresponding fonts are stored
7282 (e.g., <tt>75dpi</tt> or <tt>misc</tt>),
7283 <var>package</var> is the name of the package
7284 that provides these fonts, and
7285 <var>extension</var> is either <tt>scale</tt>
7286 or <tt>alias</tt>, whichever corresponds to
7296 Font packages must declare a dependency on
7297 <tt>xutils (>> 4.0.3)</tt> in their control
7304 Font packages that provide one or more
7305 <file>fonts.scale</file> files as described above must
7306 invoke <prgn>update-fonts-scale</prgn> on each
7307 directory into which they installed fonts
7308 <em>before</em> invoking
7309 <prgn>update-fonts-dir</prgn> on that directory.
7310 This invocation must occur in both the
7311 <prgn>postinst</prgn> (for all arguments) and
7312 <prgn>postrm</prgn> (for all arguments except
7313 <tt>upgrade</tt>) scripts.
7319 Font packages that provide one or more
7320 <file>fonts.alias</file> files as described above must
7321 invoke <prgn>update-fonts-alias</prgn> on each
7322 directory into which they installed fonts. This
7323 invocation must occur in both the
7324 <prgn>postinst</prgn> (for all arguments) and
7325 <prgn>postrm</prgn> (for all arguments except
7326 <tt>upgrade</tt>) scripts.
7332 Font packages must invoke
7333 <prgn>update-fonts-dir</prgn> on each directory into
7334 which they installed fonts. This invocation must
7335 occur in both the <prgn>postinst</prgn> (for all
7336 arguments) and <prgn>postrm</prgn> (for all
7337 arguments except <tt>upgrade</tt>) scripts.
7343 Font packages must not provide alias names for the
7344 fonts they include which collide with alias names
7345 already in use by fonts already packaged.
7351 Font packages must not provide fonts with the same
7352 XLFD registry name as another font already packaged.
7360 <heading>Application defaults files</heading>
7363 Application defaults files must be installed in the
7364 directory <file>/etc/X11/app-defaults/</file> (use of a
7365 localized subdirectory of <file>/etc/X11/</file> as described
7366 in the <em>X Toolkit Intrinsics - C Language
7367 Interface</em> manual is also permitted). They must be
7368 registered as <tt>conffile</tt>s or handled as
7369 configuration files. Packages must not provide the
7370 directory <file>/usr/X11R6/lib/X11/app-defaults/</file>.
7374 Customization of programs' X resources may also be
7375 supported with the provision of a file with the same name
7376 as that of the package placed in the
7377 <file>/etc/X11/Xresources/</file> directory, which must
7378 registered as a <tt>conffile</tt> or handled as a
7379 configuration file.<footnote>
7381 Note that this mechanism is not the same as using
7382 app-defaults; app-defaults are tied to the client
7383 binary on the local filesystem, whereas X resources
7384 are stored in the X server and affect all connecting
7388 <em>Important:</em> packages that install files into the
7389 <file>/etc/X11/Xresources/</file> directory must conflict with
7390 <tt>xbase (<< 3.3.2.3a-2)</tt>; if this is not done
7391 it is possible for the installing package to destroy a
7392 previously-existing <file>/etc/X11/Xresources</file> file
7393 which had been customized by the system administrator.
7398 <heading>Installation directory issues</heading>
7401 Packages using the X Window System should not be
7402 configured to install files under the <file>/usr/X11R6/</file>
7403 directory unless they use <prgn>imake</prgn>. The
7404 <file>/usr/X11R6/</file> directory hierarchy should be
7405 regarded as deprecated for all packages except the X
7406 Window System itself, and those which use the
7407 <prgn>imake</prgn> program it provides, in which case the
7408 packages may transition out of the <file>/usr/X11R6/</file>
7409 directory at the maintainer's discretion.<footnote>
7411 <prgn>Imake</prgn>-using programs are exempt because,
7412 as long as they are written correctly, the pathnames
7413 they use to locate resources and install themselves
7414 are derived wholly from the X Window System
7415 configuration. Thus, in the event that the X Window
7416 System moves to <file>/usr/X11R7/</file>,
7417 <file>/usr/X12/</file>, or just plain <file>/usr/</file>, all
7418 that is required for these programs is a recompile
7419 against the corresponding X Window System library
7420 development packages.
7423 Programs that use GNU <prgn>autoconf</prgn> and
7424 <prgn>automake</prgn> are usually easily configured at
7425 compile time to use <file>/usr/</file> instead of
7426 <file>/usr/X11R6/</file>, and this should be done whenever
7427 possible. Configuration files for window managers and
7428 display managers should be placed in a subdirectory of
7429 <file>/etc/X11/</file> corresponding to the package name due
7430 to these programs' tight integration with the mechanisms
7431 of the X Window System. Application-level programs should
7432 use the <file>/etc/</file> directory unless otherwise mandated
7433 by policy. The installation of files into subdirectories
7434 of <file>/usr/X11R6/include/X11/</file> and
7435 <file>/usr/X11R6/lib/X11/</file> is permitted but discouraged;
7436 package maintainers should determine if subdirectories of
7437 <file>/usr/lib/</file> and <file>/usr/share/</file> can be used
7438 instead. (The use of symbolic links from the
7439 <file>X11R6</file> directories to other FHS-compliant
7440 locations is encouraged if the program is not easily
7441 configured to look elsewhere for its files.) Packages
7442 must not provide or install files into the directories
7443 <file>/usr/bin/X11/</file>, <file>/usr/include/X11/</file> or
7444 <file>/usr/lib/X11/</file>. Files within a package should,
7445 however, make reference to these directories, rather than
7446 their <tt>X11R6</tt>-named counterparts
7447 <file>/usr/X11R6/bin/</file>, <file>/usr/X11R6/include/X11/</file>
7448 and <file>/usr/X11R6/lib/X11/</file>, if the resources being
7449 referred to have not been moved to other FHS-compliant
7455 <heading>The OSF/Motif and OpenMotif libraries</heading>
7458 <em>Programs that require the non-DFSG-compliant OSF/Motif or
7459 OpenMotif libraries</em><footnote>
7461 OSF/Motif and OpenMotif are collectively referred to as
7462 "Motif" in this policy document.
7465 should be compiled against and tested with LessTif (a free
7466 re-implementation of Motif) instead. If the maintainer
7467 judges that the program or programs do not work
7468 sufficiently well with LessTif to be distributed and
7469 supported, but do so when compiled against Motif, then two
7470 versions of the package should be created; one linked
7471 statically against Motif and with <tt>-smotif</tt>
7472 appended to the package name, and one linked dynamically
7473 against Motif and with <tt>-dmotif</tt> appended to the
7474 package name. Both Motif-linked versions are dependent
7475 upon non-DFSG-compliant software and thus cannot be
7476 uploaded to the <em>main</em> distribution; if the
7477 software is itself DFSG-compliant it may be uploaded to
7478 the <em>contrib</em> distribution. While known existing
7479 versions of Motif permit unlimited redistribution of
7480 binaries linked against the library (whether statically or
7481 dynamically), it is the package maintainer's
7482 responsibility to determine whether this is permitted by
7483 the license of the copy of Motif in his or her possession.
7489 <heading>Perl programs and modules</heading>
7492 Perl programs and modules should follow the current Perl policy.
7496 The Perl policy can be found in the <tt>perl-policy</tt>
7497 files in the <tt>debian-policy</tt> package.
7498 They are also available from the Debian web mirrors at
7499 <tt><url name="/doc/packaging-manuals/perl-policy/"
7500 id="http://www.debian.org/doc/packaging-manuals/perl-policy/"></tt>
7501 and from the Debian archive mirrors at
7502 <tt><url name="/doc/package-developer/perl-policy.txt.gz"
7503 id="http://ftp.debian.org/debian/doc/package-developer/perl-policy.txt.gz"></tt>.
7508 <heading>Emacs lisp programs</heading>
7511 Please refer to the "Debian Emacs Policy" for details of how to
7512 package emacs lisp programs.
7516 The Emacs policy is available in
7517 <file>debian-emacs-policy.gz</file> of the
7518 <package>emacsen-common</package> package.
7519 It is also available from the Debian web mirrors at
7520 <tt><url name="/doc/packaging-manuals/debian-emacs-policy"
7521 id="http://www.debian.org/doc/packaging-manuals/debian-emacs-policy"></tt>.
7526 <heading>Games</heading>
7529 The permissions on <file>/var/games</file> are mode 755, owner
7530 <tt>root</tt> and group <tt>root</tt>.
7534 Each game decides on its own security policy.</p>
7537 Games which require protected, privileged access to
7538 high-score files, savegames, etc., may be made
7539 set-<em>group</em>-id (mode 2755) and owned by
7540 <tt>root.games</tt>, and use files and directories with
7541 appropriate permissions (770 <tt>root.games</tt>, for
7542 example). They must not be made
7543 set-<em>user</em>-id, as this causes security problems. (If
7544 an attacker can subvert any set-user-id game they can
7545 overwrite the executable of any other, causing other players
7546 of these games to run a Trojan horse program. With a
7547 set-group-id game the attacker only gets access to less
7548 important game data, and if they can get at the other
7549 players' accounts at all it will take considerably more
7553 Some packages, for example some fortune cookie programs, are
7554 configured by the upstream authors to install with their
7555 data files or other static information made unreadable so
7556 that they can only be accessed through set-id programs
7557 provided. You should not do this in a Debian package: anyone can
7558 download the <file>.deb</file> file and read the data from it,
7559 so there is no point making the files unreadable. Not
7560 making the files unreadable also means that you don't have
7561 to make so many programs set-id, which reduces the risk of a
7565 As described in the FHS, binaries of games should be
7566 installed in the directory <file>/usr/games</file>. This also
7567 applies to games that use the X Window System. Manual pages
7568 for games (X and non-X games) should be installed in
7569 <file>/usr/share/man/man6</file>.</p>
7573 <chapt id="docs"><heading>Documentation</heading>
7577 <heading>Manual pages</heading>
7580 You should install manual pages in <prgn>nroff</prgn> source
7581 form, in appropriate places under <file>/usr/share/man</file>.
7582 You should only use sections 1 to 9 (see the FHS for more
7583 details). You must not install a preformatted "cat page".
7587 Each program, utility, and function should have an
7588 associated manual page included in the same package. It is
7589 suggested that all configuration files also have a manual
7590 page included as well. Manual pages for protocols and other
7591 auxiliary things are optional.
7595 If no manual page is available, this is considered as a bug
7596 and should be reported to the Debian Bug Tracking System (the
7597 maintainer of the package is allowed to write this bug report
7598 themselves, if they so desire). Do not close the bug report
7599 until a proper manpage is available.<footnote>
7601 It is not very hard to write a man page. See the
7602 <url id="http://www.schweikhardt.net/man_page_howto.html"
7603 name="Man-Page-HOWTO">,
7604 <manref name="man" section="7">, the examples
7605 created by <prgn>debmake</prgn> or <prgn>dh_make</prgn>,
7606 the helper programs <prgn>help2man</prgn>, or the
7607 directory <file>/usr/share/doc/man-db/examples</file>.
7613 You may forward a complaint about a missing manpage to the
7614 upstream authors, and mark the bug as forwarded in the
7615 Debian bug tracking system. Even though the GNU Project do
7616 not in general consider the lack of a manpage to be a bug,
7617 we do; if they tell you that they don't consider it a bug
7618 you should leave the bug in our bug tracking system open
7623 Manual pages should be installed compressed using <tt>gzip -9</tt>.
7627 If one manpage needs to be accessible via several names it
7628 is better to use a symbolic link than the <file>.so</file>
7629 feature, but there is no need to fiddle with the relevant
7630 parts of the upstream source to change from <file>.so</file> to
7631 symlinks: don't do it unless it's easy. You should not
7632 create hard links in the manual page directories, nor put
7633 absolute filenames in <file>.so</file> directives. The filename
7634 in a <file>.so</file> in a manpage should be relative to the
7635 base of the manpage tree (usually
7636 <file>/usr/share/man</file>). If you do not create any links
7637 (whether symlinks, hard links, or <tt>.so</tt> directives)
7638 in the filesystem to the alternate names of the manpage,
7639 then you should not rely on <prgn>man</prgn> finding your
7640 manpage under those names based solely on the information in
7641 the manpage's header.<footnote>
7643 Supporting this in <prgn>man</prgn> often requires
7644 unreasonable processing time to find a manual page or to
7645 report that none exists, and moves knowledge into man's
7646 database that would be better left in the filesystem.
7647 This support is therefore deprecated and will cease to
7648 be present in the future.
7655 <heading>Info documents</heading>
7658 Info documents should be installed in <file>/usr/share/info</file>.
7659 They should be compressed with <tt>gzip -9</tt>.
7663 Your package should call <prgn>install-info</prgn> to update
7664 the Info <file>dir</file> file in its <prgn>postinst</prgn>
7665 script when called with a <tt>configure</tt> argument, for
7667 <example compact="compact">
7668 install-info --quiet --section Development Development \
7669 /usr/share/info/foobar.info
7673 It is a good idea to specify a section for the location of
7674 your program; this is done with the <tt>--section</tt>
7675 switch. To determine which section to use, you should look
7676 at <file>/usr/share/info/dir</file> on your system and choose the most
7677 relevant (or create a new section if none of the current
7678 sections are relevant). Note that the <tt>--section</tt>
7679 flag takes two arguments; the first is a regular expression
7680 to match (case-insensitively) against an existing section,
7681 the second is used when creating a new one.</p>
7684 You should remove the entries in the <prgn>prerm</prgn>
7685 script when called with a <tt>remove</tt> argument:
7686 <example compact="compact">
7687 install-info --quiet --remove /usr/share/info/foobar.info
7691 If <prgn>install-info</prgn> cannot find a description entry
7692 in the Info file you must supply one. See <manref
7693 name="install-info" section="8"> for details.</p>
7697 <heading>Additional documentation</heading>
7700 Any additional documentation that comes with the package may
7701 be installed at the discretion of the package maintainer.
7702 Text documentation should be installed in the directory
7703 <file>/usr/share/doc/<var>package</var></file>, where
7704 <var>package</var> is the name of the package, and
7705 compressed with <tt>gzip -9</tt> unless it is small.
7709 If a package comes with large amounts of documentation which
7710 many users of the package will not require you should create
7711 a separate binary package to contain it, so that it does not
7712 take up disk space on the machines of users who do not need
7713 or want it installed.</p>
7716 It is often a good idea to put text information files
7717 (<file>README</file>s, changelogs, and so forth) that come with
7718 the source package in <file>/usr/share/doc/<var>package</var></file>
7719 in the binary package. However, you don't need to install
7720 the instructions for building and installing the package, of
7724 Packages must not require the existance of any files in
7725 <file>/usr/share/doc/</file> in order to function
7728 The system administrator should be able to
7729 delete files in <file>/usr/share/doc/</file> without causing
7730 any programs to break.
7733 Any files that are referenced by programs but are also
7734 useful as standalone documentation should be installed under
7735 <file>/usr/share/<var>package</var>/</file> with symbolic links from
7736 <file>/usr/share/doc/<var>package</var></file>.
7740 <file>/usr/share/doc/<var>package</var></file> may be a symbolic
7741 link to another directory in <file>/usr/share/doc</file> only if
7742 the two packages both come from the same source and the
7743 first package Depends on the second.
7747 Former Debian releases placed all additional documentation
7748 in <file>/usr/doc/<var>package</var></file>. This has been
7749 changed to <file>/usr/share/doc/<var>package</var></file>,
7750 and packages must not put documentation in the directory
7751 <file>/usr/doc/<var>package</var></file>. <footnote>
7752 <p>At this phase of the transition, we no longer require a
7753 symbolic link in <file>/usr/doc/</file>. At a later point,
7754 policy shall change to make the symbolic links a bug.</p>
7760 <heading>Preferred documentation formats</heading>
7763 The unification of Debian documentation is being carried out
7767 If your package comes with extensive documentation in a
7768 markup format that can be converted to various other formats
7769 you should if possible ship HTML versions in a binary
7770 package, in the directory
7771 <file>/usr/share/doc/<var>appropriate-package</var></file> or
7772 its subdirectories.<footnote>
7774 The rationale: The important thing here is that HTML
7775 docs should be available in <em>some</em> package, not
7776 necessarily in the main binary package.
7782 Other formats such as PostScript may be provided at the
7783 package maintainer's discretion.
7787 <sect id="copyrightfile">
7788 <heading>Copyright information</heading>
7791 Every package must be accompanied by a verbatim copy of its
7792 copyright and distribution license in the file
7793 <file>/usr/share/doc/<var>package</var>/copyright</file>. This
7794 file must neither be compressed nor be a symbolic link.
7798 In addition, the copyright file must say where the upstream
7799 sources (if any) were obtained. It should name the original
7800 authors of the package and the Debian maintainer(s) who were
7801 involved with its creation.</p>
7804 A copy of the file which will be installed in
7805 <file>/usr/share/doc/<var>package</var>/copyright</file> should
7806 be in <file>debian/copyright</file> in the source package.
7810 <file>/usr/share/doc/<var>package</var></file> may be a symbolic
7811 link to another directory in <file>/usr/share/doc</file> only if
7812 the two packages both come from the same source and the
7813 first package Depends on the second. These rules are
7814 important because copyrights must be extractable by
7819 Packages distributed under the UCB BSD license, the Artistic
7820 license, the GNU GPL, and the GNU LGPL should refer to the
7821 files <file>/usr/share/common-licenses/BSD</file>,
7822 <file>/usr/share/common-licenses/Artistic</file>,
7823 <file>/usr/share/common-licenses/GPL</file>, and
7824 <file>/usr/share/common-licenses/LGPL</file> respectively,
7825 rather than quoting them in the copyright file.
7829 You should not use the copyright file as a general <file>README</file>
7830 file. If your package has such a file it should be
7831 installed in <file>/usr/share/doc/<var>package</var>/README</file> or
7832 <file>README.Debian</file> or some other appropriate place.</p>
7836 <heading>Examples</heading>
7839 Any examples (configurations, source files, whatever),
7840 should be installed in a directory
7841 <file>/usr/share/doc/<var>package</var>/examples</file>. These
7842 files should not be referenced by any program: they're there
7843 for the benefit of the system administrator and users as
7844 documentation only. Architecture-specific example files
7845 should be installed in a directory
7846 <file>/usr/lib/<var>package</var>/examples</file> with symbolic
7848 <file>/usr/share/doc/<var>package</var>/examples</file>, or the
7849 latter directory itself may be a symbolic link to the
7854 If the purpose of a package is to provide examples, then the
7855 example files may be installed into
7856 <file>/usr/share/doc/<var>package</var></file>.
7860 <sect id="changelogs">
7861 <heading>Changelog files</heading>
7864 The Debian changelog file (<file>debian/changelog</file>) should
7865 explain briefly what modifications were made in the Debian version
7866 of the package compared to the upstream one. Other changes and
7867 updates to the package should also be documented in this file.
7871 Mistakes in changelogs are usually best rectified by
7872 making a new changelog entry rather than "rewriting history"
7873 by editing old changelog entries.
7877 The format of the <file>debian/changelog</file> file is described
7878 in <ref id="dpkgchangelog">. In non-experimental packages you must
7879 use a format for <file>debian/changelog</file> which is supported
7880 by the most recent released version of <prgn>dpkg</prgn>.<footnote>
7882 If you wish to use an alternative format, you may do so as
7883 long as you include a parser for it in your source package.
7884 The parser must have an API compatible with that expected by
7885 <prgn>dpkg-genchanges</prgn> and <prgn>dpkg-gencontrol</prgn>.
7886 If there is general interest in the new format, you should
7887 contact the <package>dpkg</package> maintainer to have the
7888 parser script for it included in the <prgn>dpkg</prgn>
7889 package. (You will need to agree that the parser and its
7890 manpage may be distributed under the GNU GPL, just as the rest
7891 of <prgn>dpkg</prgn> is.)
7897 Packages that are not Debian-native must contain a
7898 compressed copy of the <file>debian/changelog</file> file from
7899 the Debian source tree in
7900 <file>/usr/share/doc/<var>package</var></file> with the name
7901 <file>changelog.Debian.gz</file>.
7905 If an upstream changelog is available, it should be accessible as
7906 <file>/usr/share/doc/<var>package</var>/changelog.gz</file> in
7907 plain text. If the upstream changelog is distributed in
7908 HTML, it should be made available in that form as
7909 <file>/usr/share/doc/<var>package</var>/changelog.html.gz</file>
7910 and a plain text <file>changelog.gz</file> should be generated
7911 from it using, for example, <tt>lynx -dump -nolist</tt>. If
7912 the upstream changelog files do not already conform to this
7913 naming convention, then this may be achieved either by
7914 renaming the files, or by adding a symbolic link, at the
7915 maintainer's discretion.<footnote>
7917 Rationale: People should not have to look in places for
7918 upstream changelogs merely because they are given
7919 different names or are distributed in HTML format.
7925 All of these files should be installed compressed using
7926 <tt>gzip -9</tt>, as they will become large with time even
7927 if they start out small.
7931 If the package has only one changelog which is used both as
7932 the Debian changelog and the upstream one because there is
7933 no separate upstream maintainer then that changelog should
7934 usually be installed as
7935 <file>/usr/share/doc/<var>package</var>/changelog.gz</file>; if
7936 there is a separate upstream maintainer, but no upstream
7937 changelog, then the Debian changelog should still be called
7938 <file>changelog.Debian.gz</file>.</p>
7943 <appendix id="pkg-scope">
7944 <heading>Introduction and scope of these appendices</heading>
7947 These appendices are taken essentially verbatim from the
7948 now-deprecated Packaging Manual, version 3.2.1.0. They are
7949 the chapters which are likely to be of use to package
7950 maintainers and which have not already been included in the
7951 policy document itself. Most of these sections are very likely
7952 not relevant to policy; they should be treated as
7953 documentation for the packaging system. Please note that these
7954 appendices are included for convenience, and for historical
7955 reasons: they used to be part of policy package, and they have
7956 not yet been incorporated into dpkg documentation. However,
7957 they still have value, and hence they are presented here.
7960 They have not yet been checked to ensure that they are
7961 compatible with the contents of policy, and if there are any
7962 contradictions, the version in the main policy document takes
7963 precedence. The remaining chapters of the old Packaging
7964 Manual have also not been read in detail to ensure that there
7965 are not parts which have been left out. Both of these will be
7970 <prgn>dpkg</prgn> is a suite of programs for creating binary
7971 package files and installing and removing them on Unix
7974 <prgn>dpkg</prgn> is targetted primarily at Debian
7975 GNU/Linux, but may work on or be ported to other
7982 The binary packages are designed for the management of
7983 installed executable programs (usually compiled binaries) and
7984 their associated data, though source code examples and
7985 documentation are provided as part of some packages.</p>
7988 This manual describes the technical aspects of creating Debian
7989 binary packages (<file>.deb</file> files). It documents the
7990 behaviour of the package management programs
7991 <prgn>dpkg</prgn>, <prgn>dselect</prgn> et al. and the way
7992 they interact with packages.</p>
7995 It also documents the interaction between
7996 <prgn>dselect</prgn>'s core and the access method scripts it
7997 uses to actually install the selected packages, and describes
7998 how to create a new access method.</p>
8001 This manual does not go into detail about the options and
8002 usage of the package building and installation tools. It
8003 should therefore be read in conjuction with those programs'
8008 The utility programs which are provided with <prgn>dpkg</prgn>
8009 for managing various system configuration and similar issues,
8010 such as <prgn>update-rc.d</prgn> and
8011 <prgn>install-info</prgn>, are not described in detail here -
8012 please see their manpages.
8016 It is assumed that the reader is reasonably familiar with the
8017 <prgn>dpkg</prgn> System Administrators' manual.
8018 Unfortunately this manual does not yet exist.
8022 The Debian version of the FSF's GNU hello program is provided
8023 as an example for people wishing to create Debian
8024 packages. The Debian <prgn>debmake</prgn> package is
8025 recommended as a very helpful tool in creating and maintaining
8026 Debian packages. However, while the tools and examples are
8027 helpful, they do not replace the need to read and follow the
8028 Policy and Programmer's Manual.</p>
8031 <appendix id="pkg-binarypkg"><heading>Binary packages (from old
8036 The binary package has two main sections. The first part
8037 consists of various control information files and scripts used
8038 by <prgn>dpkg</prgn> when installing and removing. See <ref
8039 id="pkg-controlarea">.
8043 The second part is an archive containing the files and
8044 directories to be installed.
8048 In the future binary packages may also contain other
8049 components, such as checksums and digital signatures. The
8050 format for the archive is described in full in the
8051 <file>deb(5)</file> manpage.
8055 <sect id="pkg-bincreating"><heading>Creating package files -
8056 <prgn>dpkg-deb</prgn>
8060 All manipulation of binary package files is done by
8061 <prgn>dpkg-deb</prgn>; it's the only program that has
8062 knowledge of the format. (<prgn>dpkg-deb</prgn> may be
8063 invoked by calling <prgn>dpkg</prgn>, as <prgn>dpkg</prgn>
8064 will spot that the options requested are appropriate to
8065 <prgn>dpkg-deb</prgn> and invoke that instead with the same
8070 In order to create a binary package you must make a
8071 directory tree which contains all the files and directories
8072 you want to have in the filesystem data part of the package.
8073 In Debian-format source packages this directory is usually
8074 <file>debian/tmp</file>, relative to the top of the package's
8079 They should have the locations (relative to the root of the
8080 directory tree you're constructing) ownerships and
8081 permissions which you want them to have on the system when
8086 With current versions of <prgn>dpkg</prgn> the uid/username
8087 and gid/groupname mappings for the users and groups being
8088 used should be the same on the system where the package is
8089 built and the one where it is installed.
8093 You need to add one special directory to the root of the
8094 miniature filesystem tree you're creating:
8095 <prgn>DEBIAN</prgn>. It should contain the control
8096 information files, notably the binary package control file
8097 (see <ref id="pkg-controlfile">).
8101 The <prgn>DEBIAN</prgn> directory will not appear in the
8102 filesystem archive of the package, and so won't be installed
8103 by <prgn>dpkg</prgn> when the package is installed.
8107 When you've prepared the package, you should invoke:
8109 dpkg --build <var>directory</var>
8114 This will build the package in
8115 <file><var>directory</var>.deb</file>. (<prgn>dpkg</prgn> knows
8116 that <tt>--build</tt> is a <prgn>dpkg-deb</prgn> option, so
8117 it invokes <prgn>dpkg-deb</prgn> with the same arguments to
8122 See the manpage <manref name="dpkg-deb" section="8"> for details of how
8123 to examine the contents of this newly-created file. You may find the
8124 output of following commands enlightening:
8126 dpkg-deb --info <var>filename</var>.deb
8127 dpkg-deb --contents <var>filename</var>.deb
8128 dpkg --contents <var>filename</var>.deb
8130 To view the copyright file for a package you could use this command:
8132 dpkg --fsys-tarfile <var>filename</var>.deb | tar xof usr/share/doc/<var>\*</var>copyright | less
8137 <sect id="pkg-controlarea">
8139 Package control information files
8143 The control information portion of a binary package is a
8144 collection of files with names known to <prgn>dpkg</prgn>.
8145 It will treat the contents of these files specially - some
8146 of them contain information used by <prgn>dpkg</prgn> when
8147 installing or removing the package; others are scripts which
8148 the package maintainer wants <prgn>dpkg</prgn> to run.
8152 It is possible to put other files in the package control
8153 area, but this is not generally a good idea (though they
8154 will largely be ignored).
8158 Here is a brief list of the control info files supported by
8159 <prgn>dpkg</prgn> and a summary of what they're used for.
8164 <tag><tt>control</tt>
8168 This is the key description file used by
8169 <prgn>dpkg</prgn>. It specifies the package's name
8170 and version, gives its description for the user,
8171 states its relationships with other packages, and so
8172 forth. See <ref id="pkg-controlfile">.
8176 It is usually generated automatically from information
8177 in the source package by the
8178 <prgn>dpkg-gencontrol</prgn> program, and with
8179 assistance from <prgn>dpkg-shlibdeps</prgn>. See <ref
8180 id="pkg-sourcetools">.</p>
8183 <tag><tt>postinst</tt>, <tt>preinst</tt>, <tt>postrm</tt>,
8189 These are exectuable files (usually scripts) which
8190 <prgn>dpkg</prgn> runs during installation, upgrade
8191 and removal of packages. They allow the package to
8192 deal with matters which are particular to that package
8193 or require more complicated processing than that
8194 provided by <prgn>dpkg</prgn>. Details of when and
8195 how they are called are in <ref
8196 id="maintainerscripts">.
8200 It is very important to make these scripts
8204 That means that if it runs successfully or fails
8205 and then you call it again it doesn't bomb out,
8206 but just ensures that everything is the way it
8209 </footnote> This is so that if an error occurs, the
8210 user interrupts <prgn>dpkg</prgn> or some other
8211 unforeseen circumstance happens you don't leave the
8212 user with a badly-broken package.
8216 The maintainer scripts are guaranteed to run with a
8217 controlling terminal and can interact with the user.
8218 If they need to prompt for passwords, do full-screen
8219 interaction or something similar you should do these
8220 things to and from <file>/dev/tty</file>, since
8221 <prgn>dpkg</prgn> will at some point redirect scripts'
8222 standard input and output so that it can log the
8223 installation process. Likewise, because these scripts
8224 may be executed with standard output redirected into a
8225 pipe for logging purposes, Perl scripts should set
8226 unbuffered output by setting <tt>$|=1</tt> so that the
8227 output is printed immediately rather than being
8232 Each script should return a zero exit status for
8233 success, or a nonzero one for failure.</p>
8236 <tag><tt>conffiles</tt>
8241 This file contains a list of configuration files which
8242 are to be handled automatically by <prgn>dpkg</prgn>
8243 (see <ref id="pkg-conffiles">). Note that not necessarily
8244 every configuration file should be listed here.</p>
8247 <tag><tt>shlibs</tt>
8252 This file contains a list of the shared libraries
8253 supplied by the package, with dependency details for
8254 each. This is used by <prgn>dpkg-shlibdeps</prgn>
8255 when it determines what dependencies are required in a
8256 package control file. The <tt>shlibs</tt> file format
8257 is described on <ref id="shlibs">.
8263 <sect id="pkg-controlfile">
8265 The main control information file: <tt>control</tt>
8268 The most important control information file used by
8269 <prgn>dpkg</prgn> when it installs a package is
8270 <tt>control</tt>. It contains all the package"s "vital
8275 The binary package control files of packages built from
8276 Debian sources are made by a special tool,
8277 <prgn>dpkg-gencontrol</prgn>, which reads
8278 <file>debian/control</file> and <file>debian/changelog</file> to
8279 find the information it needs. See <ref id="pkg-sourcepkg"> for
8284 The fields in binary package control files are:
8285 <list compact="compact">
8287 <p><qref id="pkg-f-Package"><tt>Package</tt></qref> (mandatory)</p>
8290 <p><qref id="versions"><tt>Version</tt></qref> (mandatory)</p>
8292 <item><p><qref id="pkg-f-Architecture"><tt>Architecture</tt></qref>
8296 This field should appear in all packages, though
8297 <prgn>dpkg</prgn> doesn't require it yet so that
8298 old packages can still be installed.
8304 <p><qref id="relationships"><tt>Depends</tt>,
8305 <tt>Provides</tt> et al.</qref></p>
8308 <p><qref id="pkg-f-Essential"><tt>Essential</tt></qref></p>
8311 <p><qref id="pkg-f-Maintainer"><tt>Maintainer</tt></qref></p>
8314 <p><qref id="pkg-f-classification"><tt>Section</tt>,
8315 <tt>Priority</tt></qref></p>
8318 <p><qref id="pkg-f-Source"><tt>Source</tt></qref></p>
8321 <p><qref id="descriptions"><tt>Description</tt></qref></p>
8325 <qref id="pkg-f-Installed-Size"><tt>Installed-Size</tt></qref>
8331 A description of the syntax of control files and the purpose
8332 of these fields is available in <ref id="pkg-controlfields">.
8337 <heading>Time Stamps</heading>
8339 Maintainers are encouraged to preserve the modification
8340 times of the upstream source files in a package, as far as
8341 is reasonably possible.
8344 The rationale is that there is some information conveyed
8345 by knowing the age of the file, for example, you could
8346 recognize that some documentation is very old by looking
8347 at the modification time, so it would be nice if the
8348 modification time of the upstream source would be
8356 <appendix id="pkg-sourcepkg">
8357 <heading>Source packages (from old Packaging Manual) </heading>
8360 The Debian binary packages in the distribution are generated
8361 from Debian sources, which are in a special format to assist
8362 the easy and automatic building of binaries.
8365 <sect id="pkg-sourcetools">
8366 <heading>Tools for processing source packages</heading>
8369 Various tools are provided for manipulating source packages;
8370 they pack and unpack sources and help build of binary
8371 packages and help manage the distribution of new versions.
8375 They are introduced and typical uses described here; see
8376 <manref name="dpkg-source" section="1"> for full
8377 documentation about their arguments and operation.
8381 For examples of how to construct a Debian source package,
8382 and how to use those utilities that are used by Debian
8383 source packages, please see the <prgn>hello</prgn> example
8389 <prgn>dpkg-source</prgn> - packs and unpacks Debian source
8394 This program is frequently used by hand, and is also
8395 called from package-independent automated building scripts
8396 such as <prgn>dpkg-buildpackage</prgn>.
8400 To unpack a package it is typically invoked with
8402 dpkg-source -x <var>.../path/to/filename</var>.dsc
8407 with the <file><var>filename</var>.tar.gz</file> and
8408 <file><var>filename</var>.diff.gz</file> (if applicable) in
8409 the same directory. It unpacks into
8410 <file><var>package</var>-<var>version</var></file>, and if
8412 <file><var>package</var>-<var>version</var>.orig</file>, in
8413 the current directory.
8417 To create a packed source archive it is typically invoked:
8419 dpkg-source -b <var>package</var>-<var>version</var>
8424 This will create the <file>.dsc</file>, <file>.tar.gz</file> and
8425 <file>.diff.gz</file> (if appropriate) in the current
8426 directory. <prgn>dpkg-source</prgn> does not clean the
8427 source tree first - this must be done separately if it is
8432 See also <ref id="pkg-sourcearchives">.</p>
8438 <prgn>dpkg-buildpackage</prgn> - overall package-building
8443 <prgn>dpkg-buildpackage</prgn> is a script which invokes
8444 <prgn>dpkg-source</prgn>, the <file>debian/rules</file>
8445 targets <tt>clean</tt>, <tt>build</tt> and
8446 <tt>binary</tt>, <prgn>dpkg-genchanges</prgn> and
8447 <prgn>pgp</prgn> to build a signed source and binary
8452 It is usually invoked by hand from the top level of the
8453 built or unbuilt source directory. It may be invoked with
8454 no arguments; useful arguments include:
8455 <taglist compact="compact">
8456 <tag><tt>-uc</tt>, <tt>-us</tt></tag>
8459 Do not PGP-sign the <tt>.changes</tt> file or the
8460 source package <tt>.dsc</tt> file, respectively.</p>
8462 <tag><tt>-p<var>pgp-command</var></tt></tag>
8465 Invoke <var>pgp-command</var> instead of finding
8466 <tt>pgp</tt> on the <prgn>PATH</prgn>.
8467 <var>pgp-command</var> must behave just like
8468 <prgn>pgp</prgn>.</p>
8470 <tag><tt>-r<var>root-command</var></tt></tag>
8473 When root privilege is required, invoke the command
8474 <var>root-command</var>. <var>root-command</var>
8475 should invoke its first argument as a command, from
8476 the <prgn>PATH</prgn> if necessary, and pass its
8477 second and subsequent arguments to the command it
8478 calls. If no <var>root-command</var> is supplied
8479 then <var>dpkg-buildpackage</var> will take no
8480 special action to gain root privilege, so that for
8481 most packages it will have to be invoked as root to
8484 <tag><tt>-b</tt>, <tt>-B</tt></tag>
8487 Two types of binary-only build and upload - see
8488 <manref name="dpkg-source" section="1">.
8497 <prgn>dpkg-gencontrol</prgn> - generates binary package
8502 This program is usually called from <file>debian/rules</file>
8503 (see <ref id="pkg-sourcetree">) in the top level of the source
8508 This is usually done just before the files and directories in the
8509 temporary directory tree where the package is being built have their
8510 permissions and ownerships set and the package is constructed using
8511 <prgn>dpkg-deb/</prgn>
8514 This is so that the control file which is produced has
8515 the right permissions
8521 <prgn>dpkg-gencontrol</prgn> must be called after all the
8522 files which are to go into the package have been placed in
8523 the temporary build directory, so that its calculation of
8524 the installed size of a package is correct.
8528 It is also necessary for <prgn>dpkg-gencontrol</prgn> to
8529 be run after <prgn>dpkg-shlibdeps</prgn> so that the
8530 variable substitutions created by
8531 <prgn>dpkg-shlibdeps</prgn> in <file>debian/substvars</file>
8536 For a package which generates only one binary package, and
8537 which builds it in <file>debian/tmp</file> relative to the top
8538 of the source package, it is usually sufficient to call
8539 <prgn>dpkg-gencontrol</prgn>.
8543 Sources which build several binaries will typically need
8546 dpkg-gencontrol -Pdebian/tmp-<var>pkg</var> -p<var>package</var>
8547 </example> The <tt>-P</tt> tells
8548 <prgn>dpkg-gencontrol</prgn> that the package is being
8549 built in a non-default directory, and the <tt>-p</tt>
8550 tells it which package's control file should be generated.
8554 <prgn>dpkg-gencontrol</prgn> also adds information to the
8555 list of files in <file>debian/files</file>, for the benefit of
8556 (for example) a future invocation of
8557 <prgn>dpkg-genchanges</prgn>.</p>
8562 <prgn>dpkg-shlibdeps</prgn> - calculates shared library
8567 This program is usually called from <file>debian/rules</file>
8568 just before <prgn>dpkg-gencontrol</prgn> (see <ref
8569 id="pkg-sourcetree">), in the top level of the source tree.
8573 Its arguments are executables.
8576 In a forthcoming dpkg version,
8577 <prgn>dpkg-shlibdeps</prgn> would be required to be
8578 called on shared libraries as well.
8581 They may be specified either in the locations in the
8582 source tree where they are created or in the locations
8583 in the temporary build tree where they are installed
8584 prior to binary package creation.
8586 </footnote> for which shared library dependencies should
8587 be included in the binary package's control file.
8591 If some of the found shared libraries should only
8592 warrant a <tt>Recommends</tt> or <tt>Suggests</tt>, or if
8593 some warrant a <tt>Pre-Depends</tt>, this can be achieved
8594 by using the <tt>-d<var>dependency-field</var></tt> option
8595 before those executable(s). (Each <tt>-d</tt> option
8596 takes effect until the next <tt>-d</tt>.)
8600 <prgn>dpkg-shlibdeps</prgn> does not directly cause the
8601 output control file to be modified. Instead by default it
8602 adds to the <file>debian/substvars</file> file variable
8603 settings like <tt>shlibs:Depends</tt>. These variable
8604 settings must be referenced in dependency fields in the
8605 appropriate per-binary-package sections of the source
8610 For example, the <prgn>procps</prgn> package generates two
8611 kinds of binaries, simple C binaries like <prgn>ps</prgn>
8612 which require a predependency and full-screen ncurses
8613 binaries like <prgn>top</prgn> which require only a
8614 recommendation. It can say in its <file>debian/rules</file>:
8616 dpkg-shlibdeps -dPre-Depends ps -dRecommends top
8618 and then in its main control file <file>debian/control</file>:
8622 Pre-Depends: ${shlibs:Pre-Depends}
8623 Recommends: ${shlibs:Recommends}
8629 Sources which produce several binary packages with
8630 different shared library dependency requirements can use
8631 the <tt>-p<var>varnameprefix</var></tt> option to override
8632 the default <tt>shlibs:</tt> prefix (one invocation of
8633 <prgn>dpkg-shlibdeps</prgn> per setting of this option).
8634 They can thus produce several sets of dependency
8635 variables, each of the form
8636 <tt><var>varnameprefix</var>:<var>dependencyfield</var></tt>,
8637 which can be referred to in the appropriate parts of the
8638 binary package control files.
8645 <prgn>dpkg-distaddfile</prgn> - adds a file to
8646 <file>debian/files</file>
8650 Some packages' uploads need to include files other than
8651 the source and binary package files.
8655 <prgn>dpkg-distaddfile</prgn> adds a file to the
8656 <file>debian/files</file> file so that it will be included in
8657 the <file>.changes</file> file when
8658 <prgn>dpkg-genchanges</prgn> is run.
8662 It is usually invoked from the <tt>binary</tt> target of
8663 <file>debian/rules</file>:
8665 dpkg-distaddfile <var>filename</var> <var>section</var> <var>priority</var>
8667 The <var>filename</var> is relative to the directory where
8668 <prgn>dpkg-genchanges</prgn> will expect to find it - this
8669 is usually the directory above the top level of the source
8670 tree. The <file>debian/rules</file> target should put the
8671 file there just before or just after calling
8672 <prgn>dpkg-distaddfile</prgn>.
8676 The <var>section</var> and <var>priority</var> are passed
8677 unchanged into the resulting <file>.changes</file> file. See
8678 <ref id="pkg-f-classification">.
8683 <sect1><heading><prgn>dpkg-genchanges</prgn> - generates a <file>.changes</file> upload
8688 This program is usually called by package-independent
8689 automatic building scripts such as
8690 <prgn>dpkg-buildpackage</prgn>, but it may also be called
8695 It is usually called in the top level of a built source
8696 tree, and when invoked with no arguments will print out a
8697 straightforward <file>.changes</file> file based on the
8698 information in the source package's changelog and control
8699 file and the binary and source packages which should have
8705 <sect1><heading><prgn>dpkg-parsechangelog</prgn> - produces parsed representation of
8710 This program is used internally by
8711 <prgn>dpkg-source</prgn> et al. It may also occasionally
8712 be useful in <file>debian/rules</file> and elsewhere. It
8713 parses a changelog, <file>debian/changelog</file> by default,
8714 and prints a control-file format representation of the
8715 information in it to standard output.
8719 <sect1 id="pkg-dpkgarch"><heading><prgn>dpkg-architecture</prgn> -
8720 information about the build and host system
8724 This program can be used manually, but is also invoked by
8725 <tt>dpkg-buildpackage</tt> or <file>debian/rules</file> to set
8726 to set environment or make variables which specify the build and
8727 host architecture for the package building process.
8732 <sect id="pkg-sourcetree"><heading>The Debianised source tree
8736 The source archive scheme described later is intended to
8737 allow a Debianised source tree with some associated control
8738 information to be reproduced and transported easily. The
8739 Debianised source tree is a version of the original program
8740 with certain files added for the benefit of the
8741 Debianisation process, and with any other changes required
8742 made to the rest of the source code and installation
8747 The extra files created for Debian are in the subdirectory
8748 <file>debian</file> of the top level of the Debianised source
8749 tree. They are described below.
8752 <sect1 id="pkg-debianrules"><heading><file>debian/rules</file> - the main building
8757 This file is an executable makefile, and contains the
8758 package-specific recipies for compiling the package and
8759 building binary package(s) out of the source.
8763 It must start with the line <tt>#!/usr/bin/make -f</tt>,
8764 so that it can be invoked by saying its name rather than
8765 invoking <prgn>make</prgn> explicitly.
8769 Since an interactive <file>debian/rules</file> script makes it
8770 impossible to autocompile that package and also makes it
8771 hard for other people to reproduce the same binary
8772 package, all <strong>required targets</strong> have to be
8773 non-interactive. At a minimul, required targets are the
8774 ones called by <prgn>dpkg-buildpackage</prgn>, namely,
8775 <em>clean</em>, <em>binary</em>, <em>binary-arch</em>, and
8776 <em>build</em>. It also follows that any target that these
8777 targets depend on must also be non-interactive.
8781 The targets which are required to be present are:
8783 <tag><tt>build</tt></tag>
8786 This should perform all non-interactive
8787 configuration and compilation of the package. If a
8788 package has an interactive pre-build configuration
8789 routine, the Debianised source package should be
8790 built after this has taken place, so that it can be
8791 built without rerunning the configuration.
8795 A package may also provide both of the targets
8796 <tt>build-arch</tt> and <tt>build-indep</tt>. The
8797 <tt>build-arch</tt> target, if provided, should
8798 perform all non-interactive configuration and
8799 compilation required for producing all
8800 architecture-dependant binary packages (those packages
8801 for which the body of the <tt>Architecture</tt> field
8802 in <tt>debian/control</tt> is not <tt>all</tt>).
8803 Similarly, the <tt>build-indep</tt> target, if
8804 provided, should perform all non-interactive
8805 configuration and compilation required for producing
8806 all architecture-independent binary packages (those
8807 packages for which the body of the
8808 <tt>Architecture</tt> field in <tt>debian/control</tt>
8809 is <tt>all</tt>). The <tt>build</tt> target should
8810 depend on those of the targets <tt>build-arch</tt> and
8811 <tt>build-indep</tt> that are provided in the rules
8816 If one or both of the targets <tt>build-arch</tt> and
8817 <tt>build-indep</tt> are not provided, then invoking
8818 <file>debian/rules</file> with one of the not-provided
8819 targets as arguments should produce a exit status code
8820 of 2. Usually this is provided automatically by make
8821 if the target is missing.
8825 For some packages, notably ones where the same
8826 source tree is compiled in different ways to produce
8827 two binary packages, the <tt>build</tt> target does
8828 not make much sense. For these packages it is good
8829 enough to provide two (or more) targets
8830 (<tt>build-a</tt> and <tt>build-b</tt> or whatever)
8831 for each of the ways of building the package, and a
8832 <tt>build</tt> target that does nothing. The
8833 <tt>binary</tt> target will have to build the
8834 package in each of the possible ways and make the
8835 binary package out of each.
8839 The targets <tt>build</tt>, <tt>build-arch</tt>
8840 and <tt>build-indep</tt> target must not do
8841 anything that might require root privilege.
8845 The <tt>build</tt> target may need to run
8846 <tt>clean</tt> first - see below.
8850 When a package has a configuration routine that takes
8851 a long time, or when the makefiles are poorly
8852 designed, or when <tt>build</tt> needs to run
8853 <tt>clean</tt> first, it is a good idea to <tt>touch
8854 build</tt> when the build process is complete. This
8855 will ensure that if <tt>debian/rules build</tt> is run
8856 again it will not rebuild the whole program.
8860 <tag><tt>binary</tt>, <tt>binary-arch</tt>,
8861 <tt>binary-indep</tt>
8865 The <tt>binary</tt> target should be all that is
8866 necessary for the user to build the binary
8867 package. All these targets are required to be
8868 non-interactive. It is split into two parts:
8869 <tt>binary-arch</tt> builds the packages' output
8870 files which are specific to a particular
8871 architecture, and <tt>binary-indep</tt> builds
8872 those which are not.
8876 <tt>binary</tt> should usually be a target with
8877 no commands which simply depends on
8878 <prgn>binary-arch</prgn> and
8879 <prgn>binary-indep</prgn>.
8883 Both <prgn>binary-*</prgn> targets should depend on
8884 the <tt>build</tt> target, above, so that the
8885 package is built if it has not been already. It
8886 should then create the relevant binary package(s),
8887 using <prgn>dpkg-gencontrol</prgn> to make their
8888 control files and <prgn>dpkg-deb</prgn> to build
8889 them and place them in the parent of the top level
8894 If one of the <prgn>binary-*</prgn> targets has
8895 nothing to do (this will be always be the case if
8896 the source generates only a single binary package,
8897 whether architecture-dependent or not) it
8898 <em>must</em> still exist, but should always
8903 <ref id="pkg-binarypkg"> describes how to construct
8908 The <tt>binary</tt> targets must be invoked as
8913 <tag><tt>clean</tt></tag>
8917 This should undo any effects that the
8918 <tt>build</tt> and <tt>binary</tt> targets
8919 may have had, except that it should leave alone any
8920 output files created in the parent directory by a
8921 run of <tt>binary</tt>. This target is required
8922 to be non-interactive.
8926 If a <tt>build</tt> file is touched at the end
8927 of the <tt>build</tt> target, as suggested
8928 above, it must be removed as the first thing that
8929 <tt>clean</tt> does, so that running
8930 <tt>build</tt> again after an interrupted
8931 <tt>clean</tt> doesn't think that everything is
8936 The <tt>clean</tt> target must be invoked as
8937 root if <tt>binary</tt> has been invoked since
8938 the last <tt>clean</tt>, or if
8939 <tt>build</tt> has been invoked as root (since
8940 <tt>build</tt> may create directories, for
8945 <tag><tt>get-orig-source</tt> (optional)</tag>
8949 This target fetches the most recent version of the
8950 original source package from a canonical archive
8951 site (via FTP or WWW, for example), does any
8952 necessary rearrangement to turn it into the original
8953 source tarfile format described below, and leaves it
8954 in the current directory.
8958 This target may be invoked in any directory, and
8959 should take care to clean up any temporary files it
8964 This target is optional, but providing it if
8965 possible is a good idea.
8971 The <tt>build</tt>, <tt>binary</tt> and
8972 <tt>clean</tt> targets must be invoked with a current
8973 directory of the package's top-level directory.
8978 Additional targets may exist in <file>debian/rules</file>,
8979 either as published or undocumented interfaces or for the
8980 package's internal use.
8984 The architecture we build on and build for is determined by make
8985 variables via dpkg-architecture (see <ref id="pkg-dpkgarch">). You can
8986 get the Debian architecture and the GNU style architecture
8987 specification string for the build machine as well as the host
8988 machine. Here is a list of supported make variables:
8989 <list compact="compact">
8991 <p><tt>DEB_*_ARCH</tt> (the Debian architecture)</p>
8994 <p><tt>DEB_*_GNU_TYPE</tt> (the GNU style architecture
8995 specification string)</p>
8998 <p><tt>DEB_*_GNU_CPU</tt> (the CPU part of DEB_*_GNU_TYPE)</p>
9001 <p><tt>DEB_*_GNU_SYSTEM</tt> (the System part of
9007 where <tt>*</tt> is either <tt>BUILD</tt> for specification of
9008 the build machine or <tt>HOST</tt> for specification of the machine
9013 Backward compatibility can be provided in the rules file
9014 by setting the needed variables to suitable default
9015 values, please refer to the documentation of
9016 dpkg-architecture for details.
9020 It is important to understand that the <tt>DEB_*_ARCH</tt>
9021 string does only determine which Debian architecture we
9022 build on resp. for. It should not be used to get the CPU
9023 or System information, the GNU style variables should be
9029 <sect1><heading><file>debian/control</file>
9033 This file contains version-independent details about the
9034 source package and about the binary packages it creates.
9038 It is a series of sets of control fields, each
9039 syntactically similar to a binary package control file.
9040 The sets are separated by one or more blank lines. The
9041 first set is information about the source package in
9042 general; each subsequent set describes one binary package
9043 that the source tree builds.
9047 The syntax and semantics of the fields are described below
9048 in <ref id="pkg-controlfields">.
9052 The general (binary-package-independent) fields are:
9053 <list compact="compact">
9055 <p><qref id="pkg-f-Source"><tt>Source</tt></qref> (mandatory)</p>
9058 <p><qref id="pkg-f-Maintainer"><tt>Maintainer</tt></qref></p>
9062 <qref id="pkg-f-classification"><tt>Section</tt> and
9063 <tt>Priority</tt></qref>
9064 (classification, mandatory)
9069 <qref id="relationships"><tt>Build-Depends</tt> et
9070 al.</qref> (source package interrelationships)
9075 <qref id="pkg-f-Standards-Version"><tt>Standards-Version</tt></qref>
9081 The per-binary-package fields are:
9082 <list compact="compact">
9084 <p><qref id="pkg-f-Package"><tt>Package</tt></qref> (mandatory)</p>
9088 <qref id="pkg-f-Architecture"><tt>Architecture</tt></qref>
9092 <p><qref id="descriptions"><tt>Description</tt></qref></p>
9096 <qref id="pkg-f-classification"><tt>Section</tt> and
9097 <tt>Priority</tt></qref> (classification)</p>
9100 <p><qref id="pkg-f-Essential"><tt>Essential</tt></qref></p>
9104 <qref id="relationships"><tt>Depends</tt> et
9105 al.</qref> (binary package interrelationships)
9111 These fields are used by <prgn>dpkg-gencontrol</prgn> to
9112 generate control files for binary packages (see below), by
9113 <prgn>dpkg-genchanges</prgn> to generate the
9114 <tt>.changes</tt> file to accompany the upload, and by
9115 <prgn>dpkg-source</prgn> when it creates the <file>.dsc</file>
9116 source control file as part of a source archive.
9120 The fields here may contain variable references - their
9121 values will be substituted by
9122 <prgn>dpkg-gencontrol</prgn>, <prgn>dpkg-genchanges</prgn>
9123 or <prgn>dpkg-source</prgn> when they generate output
9124 control files. See <ref id="pkg-srcsubstvars"> for details.
9127 <p> <sect2><heading>User-defined fields
9131 Additional user-defined fields may be added to the
9132 source package control file. Such fields will be
9133 ignored, and not copied to (for example) binary or
9134 source package control files or upload control files.
9138 If you wish to add additional unsupported fields to
9139 these output files you should use the mechanism
9144 Fields in the main source control information file with
9145 names starting <tt>X</tt>, followed by one or more of
9146 the letters <tt>BCS</tt> and a hyphen <tt>-</tt>, will
9147 be copied to the output files. Only the part of the
9148 field name after the hyphen will be used in the output
9149 file. Where the letter <tt>B</tt> is used the field
9150 will appear in binary package control files, where the
9151 letter <tt>S</tt> is used in source package control
9152 files and where <tt>C</tt> is used in upload control
9153 (<tt>.changes</tt>) files.
9157 For example, if the main source information control file
9160 XBS-Comment: I stand between the candle and the star.
9162 then the binary and source package control files will contain the
9165 Comment: I stand between the candle and the star.
9172 <sect1 id="pkg-dpkgchangelog"><heading><file>debian/changelog</file>
9176 This file records the changes to the Debian-specific parts of the
9180 Though there is nothing stopping an author who is also
9181 the Debian maintainer from using it for all their
9182 changes, it will have to be renamed if the Debian and
9183 upstream maintainers become different
9190 It has a special format which allows the package building
9191 tools to discover which version of the package is being
9192 built and find out other release-specific information.
9196 That format is a series of entries like this:
9198 <var>package</var> (<var>version</var>) <var>distribution(s)</var>; urgency=<var>urgency</var>
9200 * <var>change details</var>
9201 <var>more change details</var>
9202 * <var>even more change details</var>
9204 -- <var>maintainer name and email address</var> <var>date</var>
9209 <var>package</var> and <var>version</var> are the source
9210 package name and version number.
9214 <var>distribution(s)</var> lists the distributions where
9215 this version should be installed when it is uploaded - it
9216 is copied to the <tt>Distribution</tt> field in the
9217 <tt>.changes</tt> file. See <ref id="pkg-f-Distribution">.
9221 <var>urgency</var> is the value for the <tt>Urgency</tt>
9222 field in the <file>.changes</file> file for the upload. See
9223 <ref id="pkg-f-Urgency">. It is not possible to specify an
9224 urgency containing commas; commas are used to separate
9225 <tt><var>keyword</var>=<var>value</var></tt> settings in
9226 the <prgn>dpkg</prgn> changelog format (though there is
9227 currently only one useful <var>keyword</var>,
9232 The change details may in fact be any series of lines
9233 starting with at least two spaces, but conventionally each
9234 change starts with an asterisk and a separating space and
9235 continuation lines are indented so as to bring them in
9236 line with the start of the text above. Blank lines may be
9237 used here to separate groups of changes, if desired.
9241 The maintainer name and email address should <em>not</em>
9242 necessarily be those of the usual package maintainer.
9243 They should be the details of the person doing
9244 <em>this</em> version. The information here will be
9245 copied to the <file>.changes</file> file, and then later used
9246 to send an acknowledgement when the upload has been
9251 The <var>date</var> should be in RFC822 format
9254 This is generated by the <prgn>822-date</prgn>
9257 </footnote>; it should include the timezone specified
9258 numerically, with the timezone name or abbreviation
9259 optionally present as a comment.
9263 The first "title" line with the package name should start
9264 at the left hand margin; the "trailer" line with the
9265 maintainer and date details should be preceded by exactly
9266 one space. The maintainer details and the date must be
9267 separated by exactly two spaces.
9271 An Emacs mode for editing this format is available: it is
9272 called <tt>debian-changelog-mode</tt>. You can have this
9273 mode selected automatically when you edit a Debian
9274 changelog by adding a local variables clause to the end of
9278 <sect2><heading>Defining alternative changelog formats
9282 It is possible to use a different format to the standard
9283 one, by providing a parser for the format you wish to
9288 In order to have <tt>dpkg-parsechangelog</tt> run your
9289 parser, you must include a line within the last 40 lines
9290 of your file matching the Perl regular expression:
9291 <tt>\schangelog-format:\s+([0-9a-z]+)\W</tt> The part in
9292 parentheses should be the name of the format. For
9293 example, you might say:
9295 @@@ changelog-format: joebloggs @@@
9297 Changelog format names are non-empty strings of alphanumerics.
9301 If such a line exists then <tt>dpkg-parsechangelog</tt>
9302 will look for the parser as
9303 <file>/usr/lib/dpkg/parsechangelog/<var>format-name</var></file>
9305 <file>/usr/local/lib/dpkg/parsechangelog/<var>format-name</var></file>;
9306 it is an error for it not to find it, or for it not to
9307 be an executable program. The default changelog format
9308 is <tt>dpkg</tt>, and a parser for it is provided with
9309 the <tt>dpkg</tt> package.
9313 The parser will be invoked with the changelog open on
9314 standard input at the start of the file. It should read
9315 the file (it may seek if it wishes) to determine the
9316 information required and return the parsed information
9317 to standard output in the form of a series of control
9318 fields in the standard format. By default it should
9319 return information about only the most recent version in
9320 the changelog; it should accept a
9321 <tt>-v<var>version</var></tt> option to return changes
9322 information from all versions present <em>strictly
9323 after</em> <var>version</var>, and it should then be an
9324 error for <var>version</var> not to be present in the
9330 <list compact="compact">
9332 <p><qref id="pkg-f-Source"><tt>Source</tt></qref></p>
9335 <p><qref id="versions"><tt>Version</tt></qref> (mandatory)</p>
9339 <qref id="pkg-f-Distribution"><tt>Distribution</tt></qref>
9344 <p><qref id="pkg-f-Urgency"><tt>Urgency</tt></qref> (mandatory)</p>
9348 <qref id="pkg-f-Maintainer"><tt>Maintainer</tt></qref>
9353 <p><qref id="pkg-f-Date"><tt>Date</tt></qref></p>
9357 <qref id="pkg-f-Changes"><tt>Changes</tt></qref>
9364 If several versions are being returned (due to the use
9365 of <tt>-v</tt>), the urgency value should be of the
9366 highest urgency code listed at the start of any of the
9367 versions requested followed by the concatenated
9368 (space-separated) comments from all the versions
9369 requested; the maintainer, version, distribution and
9370 date should always be from the most recent version.
9374 For the format of the <tt>Changes</tt> field see <ref
9375 id="pkg-f-Changes">.
9379 If the changelog format which is being parsed always or
9380 almost always leaves a blank line between individual
9381 change notes these blank lines should be stripped out,
9382 so as to make the resulting output compact.
9386 If the changelog format does not contain date or package
9387 name information this information should be omitted from
9388 the output. The parser should not attempt to synthesise
9389 it or find it from other sources.
9393 If the changelog does not have the expected format the
9394 parser should exit with a nonzero exit status, rather
9395 than trying to muddle through and possibly generating
9400 A changelog parser may not interact with the user at
9404 <!-- FIXME: section pkg-srcsubstvars is the same as srcsubstvars -->
9406 <sect1 id="pkg-srcsubstvars"><heading><file>debian/substvars</file>
9407 and variable substitutions
9411 When <prgn>dpkg-gencontrol</prgn>,
9412 <prgn>dpkg-genchanges</prgn> and <prgn>dpkg-source</prgn>
9413 generate control files they do variable substitutions on
9414 their output just before writing it. Variable
9415 substitutions have the form
9416 <tt>${<var>variable-name</var>}</tt>. The optional file
9417 <file>debian/substvars</file> contains variable substitutions
9418 to be used; variables can also be set directly from
9419 <file>debian/rules</file> using the <tt>-V</tt> option to the
9420 source packaging commands, and certain predefined
9421 variables are available.
9425 This file is usually generated and modified dynamically by
9426 <file>debian/rules</file> targets, in which case it must be
9427 removed by the <tt>clean</tt> target.
9431 See <manref name="dpkg-source" section="1"> for full
9432 details about source variable substitutions, including the
9433 format of <file>debian/substvars</file>.</p>
9436 <sect1><heading><file>debian/files</file>
9440 This file is not a permanent part of the source tree; it
9441 is used while building packages to record which files are
9442 being generated. <prgn>dpkg-genchanges</prgn> uses it
9443 when it generates a <file>.changes</file> file.
9447 It should not exist in a shipped source package, and so it
9448 (and any backup files or temporary files such as
9449 <file>files.new</file>
9452 <file>files.new</file> is used as a temporary file by
9453 <prgn>dpkg-gencontrol</prgn> and
9454 <prgn>dpkg-distaddfile</prgn> - they write a new
9455 version of <file>files</file> here before renaming it,
9456 to avoid leaving a corrupted copy if an error
9459 </footnote>) should be removed by the
9460 <tt>clean</tt> target. It may also be wise to
9461 ensure a fresh start by emptying or removing it at the
9462 start of the <tt>binary</tt> target.
9466 <prgn>dpkg-gencontrol</prgn> adds an entry to this file
9467 for the <file>.deb</file> file that will be created by
9468 <prgn>dpkg-deb</prgn> from the control file that it
9469 generates, so for most packages all that needs to be done
9470 with this file is to delete it in <tt>clean</tt>.
9474 If a package upload includes files besides the source
9475 package and any binary packages whose control files were
9476 made with <prgn>dpkg-gencontrol</prgn> then they should be
9477 placed in the parent of the package's top-level directory
9478 and <prgn>dpkg-distaddfile</prgn> should be called to add
9479 the file to the list in <file>debian/files</file>.</p>
9482 <sect1><heading><file>debian/tmp</file>
9486 This is the canonical temporary location for the
9487 construction of binary packages by the <tt>binary</tt>
9488 target. The directory <file>tmp</file> serves as the root of
9489 the filesystem tree as it is being constructed (for
9490 example, by using the package's upstream makefiles install
9491 targets and redirecting the output there), and it also
9492 contains the <tt>DEBIAN</tt> subdirectory. See <ref
9493 id="pkg-bincreating">.
9497 If several binary packages are generated from the same
9498 source tree it is usual to use several
9499 <file>debian/tmp<var>something</var></file> directories, for
9500 example <file>tmp-a</file> or <file>tmp-doc</file>.
9504 Whatever <file>tmp</file> directories are created and used by
9505 <tt>binary</tt> must of course be removed by the
9506 <tt>clean</tt> target.</p></sect1>
9510 <sect id="pkg-sourcearchives"><heading>Source packages as archives
9514 As it exists on the FTP site, a Debian source package
9515 consists of three related files. You must have the right
9516 versions of all three to be able to use them.
9521 <tag>Debian source control file - <tt>.dsc</tt></tag>
9525 This file contains a series of fields, identified and
9526 separated just like the fields in the control file of
9527 a binary package. The fields are listed below; their
9528 syntax is described above, in <ref id="pkg-controlfields">.
9529 <list compact="compact">
9531 <p><qref id="pkg-f-Source"><tt>Source</tt></qref></p>
9534 <p><qref id="versions"><tt>Version</tt></qref></p>
9537 <p><qref id="pkg-f-Maintainer"><tt>Maintainer</tt></qref></p>
9540 <p><qref id="pkg-f-Binary"><tt>Binary</tt></qref></p>
9543 <p><qref id="pkg-f-Architecture"><tt>Architecture</tt></qref></p>
9547 <qref id="relationships"><tt>Build-Depends</tt> et
9548 al.</qref> (source package interrelationships)
9553 <qref id="pkg-f-Standards-Version"><tt>Standards-Version</tt></qref></p>
9556 <p><qref id="pkg-f-Files"><tt>Files</tt></qref></p>
9561 The source package control file is generated by
9562 <prgn>dpkg-source</prgn> when it builds the source
9563 archive, from other files in the source package,
9564 described above. When unpacking it is checked against
9565 the files and directories in the other parts of the
9566 source package, as described below.</p>
9570 Original source archive -
9572 <var>package</var>_<var>upstream-version</var>.orig.tar.gz
9579 This is a compressed (with <tt>gzip -9</tt>)
9580 <prgn>tar</prgn> file containing the source code from
9581 the upstream authors of the program. The tarfile
9582 unpacks into a directory
9583 <file><var>package</var>-<var>upstream-version</var>.orig</file>,
9584 and does not contain files anywhere other than in
9585 there or in its subdirectories.</p>
9589 Debianisation diff -
9591 <var>package</var>_<var>upstream_version-revision</var>.diff.gz
9597 This is a unified context diff (<tt>diff -u</tt>)
9598 giving the changes which are required to turn the
9599 original source into the Debian source. These changes
9600 may only include editing and creating plain files.
9601 The permissions of files, the targets of symbolic
9602 links and the characteristics of special files or
9603 pipes may not be changed and no files may be removed
9608 All the directories in the diff must exist, except the
9609 <file>debian</file> subdirectory of the top of the source
9610 tree, which will be created by
9611 <prgn>dpkg-source</prgn> if necessary when unpacking.
9615 The <prgn>dpkg-source</prgn> program will
9616 automatically make the <file>debian/rules</file> file
9617 executable (see below).</p></item>
9622 If there is no original source code - for example, if the
9623 package is specially prepared for Debian or the Debian
9624 maintainer is the same as the upstream maintainer - the
9625 format is slightly different: then there is no diff, and the
9627 <file><var>package</var>_<var>version</var>.tar.gz</file> and
9628 contains a directory
9629 <file><var>package</var>-<var>version</var></file>.
9633 <sect><heading>Unpacking a Debian source package without
9634 <prgn>dpkg-source</prgn>
9638 <tt>dpkg-source -x</tt> is the recommended way to unpack a
9639 Debian source package. However, if it is not available it
9640 is possible to unpack a Debian source archive as follows:
9641 <enumlist compact="compact">
9644 Untar the tarfile, which will create a <file>.orig</file>
9648 <p>Rename the <file>.orig</file> directory to
9649 <file><var>package</var>-<var>version</var></file>.</p>
9653 Create the subdirectory <file>debian</file> at the top of
9654 the source tree.</p>
9656 <item><p>Apply the diff using <tt>patch -p0</tt>.</p>
9658 <item><p>Untar the tarfile again if you want a copy of the original
9659 source code alongside the Debianised version.</p>
9664 It is not possible to generate a valid Debian source archive
9665 without using <prgn>dpkg-source</prgn>. In particular,
9666 attempting to use <prgn>diff</prgn> directly to generate the
9667 <file>.diff.gz</file> file will not work.
9670 <sect1><heading>Restrictions on objects in source packages
9674 The source package may not contain any hard links
9677 This is not currently detected when building source
9678 packages, but only when extracting
9684 Hard links may be permitted at some point in the
9685 future, but would require a fair amount of
9688 </footnote>, device special files, sockets or setuid or
9692 Setgid directories are allowed.
9698 The source packaging tools manage the changes between the
9699 original and Debianised source using <prgn>diff</prgn> and
9700 <prgn>patch</prgn>. Turning the original source tree as
9701 included in the <file>.orig.tar.gz</file> into the debianised
9702 source must not involve any changes which cannot be
9703 handled by these tools. Problematic changes which cause
9704 <prgn>dpkg-source</prgn> to halt with an error when
9705 building the source package are:
9706 <list compact="compact">
9707 <item><p>Adding or removing symbolic links, sockets or pipes.</p>
9709 <item><p>Changing the targets of symbolic links.</p>
9711 <item><p>Creating directories, other than <file>debian</file>.</p>
9713 <item><p>Changes to the contents of binary files.</p></item>
9714 </list> Changes which cause <prgn>dpkg-source</prgn> to
9715 print a warning but continue anyway are:
9716 <list compact="compact">
9719 Removing files, directories or symlinks.
9722 Renaming a file is not treated specially - it is
9723 seen as the removal of the old file (which
9724 generates a warning, but is otherwise ignored),
9725 and the creation of the new
9732 Changed text files which are missing the usual final
9733 newline (either in the original or the modified
9738 Changes which are not represented, but which are not detected by
9739 <prgn>dpkg-source</prgn>, are:
9740 <list compact="compact">
9741 <item><p>Changing the permissions of files (other than
9742 <file>debian/rules</file>) and directories.</p></item>
9747 The <file>debian</file> directory and <file>debian/rules</file>
9748 are handled specially by <prgn>dpkg-source</prgn> - before
9749 applying the changes it will create the <file>debian</file>
9750 directory, and afterwards it will make
9751 <file>debian/rules</file> world-exectuable.
9757 <appendix id="pkg-controlfields"><heading>Control files and their
9758 fields (from old Packaging Manual)
9762 Many of the tools in the <prgn>dpkg</prgn> suite manipulate
9763 data in a common format, known as control files. Binary and
9764 source packages have control data as do the <file>.changes</file>
9765 files which control the installation of uploaded files, and
9766 <prgn>dpkg</prgn>'s internal databases are in a similar
9770 <sect><heading>Syntax of control files
9774 A file consists of one or more paragraphs of fields. The
9775 paragraphs are separated by blank lines. Some control files
9776 only allow one paragraph; others allow several, in which
9777 case each paragraph often refers to a different package.
9781 Each paragraph is a series of fields and values; each field
9782 consists of a name, followed by a colon and the value. It
9783 ends at the end of the line. Horizontal whitespace (spaces
9784 and tabs) may occur before or after the value and is ignored
9785 there; it is conventional to put a single space after the
9790 Some fields' values may span several lines; in this case
9791 each continuation line <em>must</em> start with a space or
9792 tab. Any trailing spaces or tabs at the end of individual
9793 lines of a field value are ignored.
9797 Except where otherwise stated only a single line of data is
9798 allowed and whitespace is not significant in a field body.
9799 Whitespace may never appear inside names (of packages,
9800 architectures, files or anything else), version numbers or
9801 in between the characters of multi-character version
9806 Field names are not case-sensitive, but it is usual to
9807 capitalise the field names using mixed case as shown below.
9811 Blank lines, or lines consisting only of spaces and tabs,
9812 are not allowed within field values or between fields - that
9813 would mean a new paragraph.
9817 It is important to note that there are several fields which
9818 are optional as far as <prgn>dpkg</prgn> and the related
9819 tools are concerned, but which must appear in every Debian
9820 package, or whose omission may cause problems.
9824 <sect><heading>List of fields
9827 <sect1 id="pkg-f-Package"><heading><tt>Package</tt>
9831 The name of the binary package. Package names consist of
9832 the alphanumerics and <tt>+</tt> <tt>-</tt> <tt>.</tt>
9833 (plus, minus and full stop).
9836 The characters <tt>@</tt> <tt>:</tt> <tt>=</tt>
9837 <tt>%</tt> <tt>_</tt> (at, colon, equals, percent
9838 and underscore) used to be legal and are still
9839 accepted when found in a package file, but may not be
9840 used in new packages
9846 They must be at least two characters and must start with
9847 an alphanumeric. In current versions of dpkg they are
9848 sort of case-sensitive<footnote><p>This is a
9849 bug.</p></footnote>; use lowercase package names unless
9850 the package you're building (or referring to, in other
9851 fields) is already using uppercase.</p>
9854 <sect1 id="pkg-f-Version"><heading><tt>Version</tt>
9858 This lists the source or binary package's version number -
9859 see <ref id="versions">.
9864 <sect1 id="pkg-f-Architecture"><heading><tt>Architecture</tt>
9868 This is the architecture string; it is a single word for
9869 the Debian architecture.
9873 <prgn>dpkg</prgn> will check the declared architecture of
9874 a binary package against its own compiled-in value before
9879 The special value <tt>all</tt> indicates that the package
9880 is architecture-independent.
9884 In the main <file>debian/control</file> file in the source
9885 package, or in the source package control file
9886 <file>.dsc</file>, a list of architectures (separated by
9887 spaces) is also allowed, as is the special value
9888 <tt>any</tt>. A list indicates that the source will build
9889 an architecture-dependent package, and will only work
9890 correctly on the listed architectures. <tt>any</tt>
9891 indicates that though the source package isn't dependent
9892 on any particular architecture and should compile fine on
9893 any one, the binary package(s) produced are not
9894 architecture-independent but will instead be specific to
9895 whatever the current build architecture is.
9899 In a <file>.changes</file> file the <tt>Architecture</tt>
9900 field lists the architecture(s) of the package(s)
9901 currently being uploaded. This will be a list; if the
9902 source for the package is being uploaded too the special
9903 entry <tt>source</tt> is also present.
9907 See <ref id="pkg-debianrules"> for information how to get the
9908 architecture for the build process.
9912 <sect1 id="pkg-f-Maintainer"><heading><tt>Maintainer</tt>
9916 The package maintainer's name and email address. The name
9917 should come first, then the email address inside angle
9918 brackets <tt><></tt> (in RFC822 format).
9922 If the maintainer's name contains a full stop then the
9923 whole field will not work directly as an email address due
9924 to a misfeature in the syntax specified in RFC822; a
9925 program using this field as an address must check for this
9926 and correct the problem if necessary (for example by
9927 putting the name in round brackets and moving it to the
9928 end, and bringing the email address forward).
9932 In a <file>.changes</file> file or parsed changelog data this
9933 contains the name and email address of the person
9934 responsible for the particular version in question - this
9935 may not be the package's usual maintainer.
9939 This field is usually optional in as far as the
9940 <prgn>dpkg</prgn> are concerned, but its absence when
9941 building packages usually generates a warning.</p>
9944 <sect1 id="pkg-f-Source"><heading><tt>Source</tt>
9948 This field identifies the source package name.
9952 In a main source control information or a
9953 <file>.changes</file> or <file>.dsc</file> file or parsed
9954 changelog data this may contain only the name of the
9959 In the control file of a binary package (or in a
9960 <file>Packages</file> file) it may be followed by a version
9961 number in parentheses.
9964 It is usual to leave a space after the package name if
9965 a version number is specified.
9967 </footnote> This version number may be omitted (and is, by
9968 <prgn>dpkg-gencontrol</prgn>) if it has the same value as
9969 the <tt>Version</tt> field of the binary package in
9970 question. The field itself may be omitted from a binary
9971 package control file when the source package has the same
9972 name and version as the binary package.
9976 <sect1><heading>Package interrelationship fields:
9977 <tt>Depends</tt>, <tt>Pre-Depends</tt>,
9978 <tt>Recommends</tt> <tt>Suggests</tt>, <tt>Conflicts</tt>,
9979 <tt>Provides</tt>, <tt>Replaces</tt>
9983 These fields describe the package's relationships with
9984 other packages. Their syntax and semantics are described
9985 in <ref id="relationships">.</p>
9988 <sect1 id="pkg-f-Description"><heading><tt>Description</tt>
9992 In a binary package <tt>Packages</tt> file or main source
9993 control file this field contains a description of the
9994 binary package, in a special format. See <ref
9995 id="descriptions"> for details.
9999 In a <file>.changes</file> file it contains a summary of the
10000 descriptions for the packages being uploaded. The part of
10001 the field before the first newline is empty; thereafter
10002 each line has the name of a binary package and the summary
10003 description line from that binary package. Each line is
10004 indented by one space.</p>
10007 <sect1 id="pkg-f-Essential"><heading><tt>Essential</tt>
10011 This is a boolean field which may occur only in the
10012 control file of a binary package (or in the
10013 <file>Packages</file> file) or in a per-package fields
10014 paragraph of a main source control data file.
10018 If set to <tt>yes</tt> then <prgn>dpkg</prgn> and
10019 <prgn>dselect</prgn> will refuse to remove the package
10020 (though it can be upgraded and/or replaced). The other
10021 possible value is <tt>no</tt>, which is the same as not
10022 having the field at all.</p>
10025 <sect1 id="pkg-f-classification"><heading><tt>Section</tt> and
10030 These two fields classify the package. The
10031 <tt>Priority</tt> represents how important that it is that
10032 the user have it installed; the <tt>Section</tt>
10033 represents an application area into which the package has
10038 When they appear in the <file>debian/control</file> file these
10039 fields give values for the section and priority subfields
10040 of the <tt>Files</tt> field of the <file>.changes</file> file,
10041 and give defaults for the section and priority of the
10046 The section and priority are represented, though not as
10047 separate fields, in the information for each file in the
10048 <qref id="pkg-f-Files"><tt>-File</tt></qref>field of a
10049 <file>.changes</file> file. The section value in a
10050 <file>.changes</file> file is used to decide where to install
10051 a package in the FTP archive.
10055 These fields are not used by by <prgn>dpkg</prgn> proper,
10056 but by <prgn>dselect</prgn> when it sorts packages and
10061 These fields can appear in binary package control files,
10062 in which case they provide a default value in case the
10063 <file>Packages</file> files are missing the information.
10064 <prgn>dpkg</prgn> and <prgn>dselect</prgn> will only use
10065 the value from a <file>.deb</file> file if they have no other
10066 information; a value listed in a <file>Packages</file> file
10067 will always take precedence. By default
10068 <prgn>dpkg-gencontrol</prgn> does not include the section
10069 and priority in the control file of a binary package - use
10070 the <tt>-isp</tt>, <tt>-is</tt> or <tt>-ip</tt> options to
10071 achieve this effect.</p>
10074 <sect1 id="pkg-f-Binary"><heading><tt>Binary</tt>
10078 This field is a list of binary packages.
10082 When it appears in the <file>.dsc</file> file it is the list
10083 of binary packages which a source package can produce. It
10084 does not necessarily produce all of these binary packages
10085 for every architecture. The source control file doesn't
10086 contain details of which architectures are appropriate for
10087 which of the binary packages.
10091 When it appears in a <file>.changes</file> file it lists the
10092 names of the binary packages actually being uploaded.
10096 The syntax is a list of binary packages separated by
10100 A space after each comma is conventional.
10102 </footnote> Currently the packages must be separated using
10103 only spaces in the <file>.changes</file> file.</p>
10106 <sect1 id="pkg-f-Installed-Size"><heading><tt>Installed-Size</tt>
10110 This field appears in the control files of binary
10111 packages, and in the <file>Packages</file> files. It gives
10112 the total amount of disk space required to install the
10117 The disk space is represented in kilobytes as a simple
10118 decimal number.</p>
10121 <sect1 id="pkg-f-Files"><heading><tt>Files</tt>
10125 This field contains a list of files with information about
10126 each one. The exact information and syntax varies with
10127 the context. In all cases the part of the field
10128 contents on the same line as the field name is empty. The
10129 remainder of the field is one line per file, each line
10130 being indented by one space and containing a number of
10131 sub-fields separated by spaces.
10135 In the <file>.dsc</file> (Debian source control) file each
10136 line contains the MD5 checksum, size and filename of the
10137 tarfile and (if applicable) diff file which make up the
10138 remainder of the source package.
10141 That is, the parts which are not the
10144 </footnote> The exact forms of the filenames are described
10145 in <ref id="pkg-sourcearchives">.
10149 In the <file>.changes</file> file this contains one line per
10150 file being uploaded. Each line contains the MD5 checksum,
10151 size, section and priority and the filename. The section
10152 and priority are the values of the corresponding fields in
10153 the main source control file - see <ref
10154 id="pkg-f-classification">. If no section or priority is
10155 specified then <tt>-</tt> should be used, though section
10156 and priority values must be specified for new packages to
10157 be installed properly.
10161 The special value <tt>byhand</tt> for the section in a
10162 <tt>.changes</tt> file indicates that the file in question
10163 is not an ordinary package file and must by installed by
10164 hand by the distribution maintainers. If the section is
10165 <tt>byhand</tt> the priority should be <tt>-</tt>.
10169 If a new Debian revision of a package is being shipped and
10170 no new original source archive is being distributed the
10171 <tt>.dsc</tt> must still contain the <tt>Files</tt> field
10172 entry for the original source archive
10173 <file><var>package</var>-<var>upstream-version</var>.orig.tar.gz</file>,
10174 but the <file>.changes</file> file should leave it out. In
10175 this case the original source archive on the distribution
10176 site must match exactly, byte-for-byte, the original
10177 source archive which was used to generate the
10178 <file>.dsc</file> file and diff which are being uploaded.</p>
10183 id="pkg-f-Standards-Version"><heading><tt>Standards-Version</tt>
10187 The most recent version of the standards (the Debian Policy
10188 and associated texts) with which the package complies. This
10189 is updated manually when editing the source package to
10190 conform to newer standards; it can sometimes be used to
10191 tell when a package needs attention.
10195 Its format is the same as that of a version number except
10196 that no epoch or Debian revision is allowed - see <ref
10197 id="versions">.</p>
10201 <sect1 id="pkg-f-Distribution"><heading><tt>Distribution</tt>
10205 In a <file>.changes</file> file or parsed changelog output
10206 this contains the (space-separated) name(s) of the
10207 distribution(s) where this version of the package should
10208 be or was installed. Distribution names follow the rules
10209 for package names. (See <ref id="pkg-f-Package">).
10213 Current distribution values are:
10215 <tag><em>stable</em></tag>
10218 This is the current "released" version of Debian
10219 GNU/Linux. A new version is released approximately
10220 every 3 months after the <em>development</em> code has
10221 been <em>frozen</em> for a month of testing. Once the
10222 distribution is <em>stable</em> only major bug fixes
10223 are allowed. When changes are made to this
10224 distribution, the release number is increased
10225 (for example: 1.2r1 becomes 1.2r2 then 1.2r3, etc).
10229 <tag><em>unstable</em></tag>
10232 This distribution value refers to the
10233 <em>developmental</em> part of the Debian distribution
10234 tree. New packages, new upstream versions of packages
10235 and bug fixes go into the <em>unstable</em> directory
10236 tree. Download from this distribution at your own
10240 <tag><em>contrib</em></tag>
10243 The packages with this distribution value do not meet
10244 the criteria for inclusion in the main Debian
10245 distribution as defined by the Policy Manual, but meet
10246 the criteria for the <em>contrib</em>
10247 Distribution. There is currently no distinction
10248 between stable and unstable packages in the
10249 <em>contrib</em> or <em>non-free</em>
10250 distributions. Use your best judgement in downloading
10251 from this Distribution.</p>
10254 <tag><em>non-free</em></tag>
10257 Like the packages in the <em>contrib</em> seciton,
10258 the packages in <em>non-free</em> do not meet the
10259 criteria for inclusion in the main Debian distribution
10260 as defined by the Policy Manual. Again, use your best
10261 judgement in downloading from this Distribution.</p>
10263 <tag><em>experimental</em></tag>
10266 The packages with this distribution value are deemed
10267 by their maintainers to be high risk. Oftentimes they
10268 represent early beta or developmental packages from
10269 various sources that the maintainers want people to
10270 try, but are not ready to be a part of the other parts
10271 of the Debian distribution tree. Download at your own
10275 <tag><em>frozen</em></tag>
10278 From time to time, (currently, every 3 months) the
10279 <em>unstable</em> distribution enters a state of
10280 "code-freeze" in anticipation of release as a
10281 <em>stable</em> version. During this period of testing
10282 (usually 4 weeks) only fixes for existing or
10283 newly-discovered bugs will be allowed.
10286 </taglist> You should list <em>all</em> distributions that
10287 the package should be installed into. Except in unusual
10288 circumstances, installations to <em>stable</em> should also
10289 go into <em>frozen</em> (if it exists) and
10290 <em>unstable</em>. Likewise, installations into
10291 <em>frozen</em> should also go into <em>unstable</em>.</p>
10294 <sect1 id="pkg-f-Urgency"><heading><tt>Urgency</tt>
10298 This is a description of how important it is to upgrade to
10299 this version from previous ones. It consists of a single
10300 keyword usually taking one of the values <tt>LOW</tt>,
10301 <tt>MEDIUM</tt> or <tt>HIGH</tt>) followed by an optional
10302 commentary (separated by a space) which is usually in
10303 parentheses. For example:
10305 Urgency: LOW (HIGH for diversions users)
10310 This field appears in the <file>.changes</file> file and in
10311 parsed changelogs; its value appears as the value of the
10312 <tt>urgency</tt> attribute in a <prgn>dpkg</prgn>-style
10313 changelog (see <ref id="pkg-dpkgchangelog">).
10317 Urgency keywords are not case-sensitive.</p>
10320 <sect1 id="pkg-f-Date"><heading><tt>Date</tt>
10324 In <tt>.changes</tt> files and parsed changelogs, this
10325 gives the date the package was built or last edited.</p>
10328 <sect1 id="pkg-f-Format"><heading><tt>Format</tt>
10332 This field occurs in <file>.changes</file> files, and
10333 specifies a format revision for the file. The format
10334 described here is version <tt>1.5</tt>. The syntax of the
10335 format value is the same as that of a package version
10336 number except that no epoch or Debian revision is allowed
10337 - see <ref id="versions">.</p>
10340 <sect1 id="pkg-f-Changes"><heading><tt>Changes</tt>
10344 In a <file>.changes</file> file or parsed changelog this field
10345 contains the human-readable changes data, describing the
10346 differences between the last version and the current one.
10350 There should be nothing in this field before the first
10351 newline; all the subsequent lines must be indented by at
10352 least one space; blank lines must be represented by a line
10353 consiting only of a space and a full stop.
10357 Each version's change information should be preceded by a
10358 "title" line giving at least the version, distribution(s)
10359 and urgency, in a human-readable way.
10363 If data from several versions is being returned the entry
10364 for the most recent version should be returned first, and
10365 entries should be separated by the representation of a
10366 blank line (the "title" line may also be followed by the
10367 representation of blank line).</p>
10370 <sect1 id="pkg-f-Filename"><heading><tt>Filename</tt> and
10371 <tt>MSDOS-Filename</tt>
10375 These fields in <tt>Packages</tt> files give the
10376 filename(s) of (the parts of) a package in the
10377 distribution directories, relative to the root of the
10378 Debian hierarchy. If the package has been split into
10379 several parts the parts are all listed in order, separated
10383 <sect1 id="pkg-f-Size"><heading><tt>Size</tt> and <tt>MD5sum</tt>
10387 These fields in <file>Packages</file> files give the size (in
10388 bytes, expressed in decimal) and MD5 checksum of the
10389 file(s) which make(s) up a binary package in the
10390 distribution. If the package is split into several parts
10391 the values for the parts are listed in order, separated by
10395 <sect1 id="pkg-f-Status"><heading><tt>Status</tt>
10399 This field in <prgn>dpkg</prgn>'s status file records
10400 whether the user wants a package installed, removed or
10401 left alone, whether it is broken (requiring
10402 reinstallation) or not and what its current state on the
10403 system is. Each of these pieces of information is a
10407 <sect1 id="pkg-f-Config-Version"><heading><tt>Config-Version</tt>
10411 If a package is not installed or not configured, this
10412 field in <prgn>dpkg</prgn>'s status file records the last
10413 version of the package which was successfully
10417 <sect1 id="pkg-f-Conffiles"><heading><tt>Conffiles</tt>
10421 This field in <prgn>dpkg</prgn>'s status file contains
10422 information about the automatically-managed configuration
10423 files held by a package. This field should <em>not</em>
10424 appear anywhere in a package!</p>
10427 <sect1><heading>Obsolete fields
10431 These are still recognised by <prgn>dpkg</prgn> but should
10432 not appear anywhere any more.
10433 <taglist compact="compact">
10435 <tag><tt>Revision</tt></tag>
10436 <tag><tt>Package-Revision</tt></tag>
10437 <tag><tt>Package_Revision</tt></tag>
10440 The Debian revision part of the package version was
10441 at one point in a separate control file field. This
10442 field went through several names.</p>
10445 <tag><tt>Recommended</tt></tag>
10446 <item><p>Old name for <tt>Recommends</tt></p>
10449 <tag><tt>Optional</tt></tag>
10450 <item><p>Old name for <tt>Suggests</tt>.</p>
10452 <tag><tt>Class</tt></tag>
10453 <item><p>Old name for <tt>Priority</tt>.</p>
10461 <appendix id="pkg-conffiles"><heading>Configuration file handling
10462 (from old Packaging Manual)
10466 <prgn>dpkg</prgn> can do a certain amount of automatic
10467 handling of package configuration files.
10471 Whether this mechanism is appropriate depends on a number of
10472 factors, but basically there are two approaches to any
10473 particular configuration file.
10477 The easy method is to ship a best-effort configuration in the
10478 package, and use <prgn>dpkg</prgn>'s conffile mechanism to
10479 handle updates. If the user is unlikely to want to edit the
10480 file, but you need them to be able to without losing their
10481 changes, and a new package with a changed version of the file
10482 is only released infrequently, this is a good approach.
10486 The hard method is to build the configuration file from
10487 scratch in the <prgn>postinst</prgn> script, and to take the
10488 responsibility for fixing any mistakes made in earlier
10489 versions of the package automatically. This will be
10490 appropriate if the file is likely to need to be different on
10494 <sect><heading>Automatic handling of configuration files by
10499 A package may contain a control area file called
10500 <tt>conffiles</tt>. This file should be a list of filenames
10501 of configuration files needing automatic handling, separated
10502 by newlines. The filenames should be absolute pathnames,
10503 and the files referred to should actually exist in the
10508 When a package is upgraded <prgn>dpkg</prgn> will process
10509 the configuration files during the configuration stage,
10510 shortly before it runs the package's <prgn>postinst</prgn>
10515 For each file it checks to see whether the version of the
10516 file included in the package is the same as the one that was
10517 included in the last version of the package (the one that is
10518 being upgraded from); it also compares the version currently
10519 installed on the system with the one shipped with the last
10524 If neither the user nor the package maintainer has changed
10525 the file, it is left alone. If one or the other has changed
10526 their version, then the changed version is preferred - i.e.,
10527 if the user edits their file, but the package maintainer
10528 doesn't ship a different version, the user's changes will
10529 stay, silently, but if the maintainer ships a new version
10530 and the user hasn't edited it the new version will be
10531 installed (with an informative message). If both have
10532 changed their version the user is prompted about the problem
10533 and must resolve the differences themselves.
10537 The comparisons are done by calculating the MD5 message
10538 digests of the files, and storing the MD5 of the file as it
10539 was included in the most recent version of the package.
10543 When a package is installed for the first time
10544 <prgn>dpkg</prgn> will install the file that comes with it,
10545 unless that would mean overwriting a file already on the
10550 However, note that <prgn>dpkg</prgn> will <em>not</em>
10551 replace a conffile that was removed by the user (or by a
10552 script). This is necessary because with some programs a
10553 missing file produces an effect hard or impossible to
10554 achieve in another way, so that a missing file needs to be
10555 kept that way if the user did it.
10559 Note that a package should <em>not</em> modify a
10560 <prgn>dpkg</prgn>-handled conffile in its maintainer
10561 scripts. Doing this will lead to <prgn>dpkg</prgn> giving
10562 the user confusing and possibly dangerous options for
10563 conffile update when the package is upgraded.</p>
10566 <sect><heading>Fully-featured maintainer script configuration
10571 For files which contain site-specific information such as
10572 the hostname and networking details and so forth, it is
10573 better to create the file in the package's
10574 <prgn>postinst</prgn> script.
10578 This will typically involve examining the state of the rest
10579 of the system to determine values and other information, and
10580 may involve prompting the user for some information which
10581 can't be obtained some other way.
10585 When using this method there are a couple of important
10586 issues which should be considered:
10590 If you discover a bug in the program which generates the
10591 configuration file, or if the format of the file changes
10592 from one version to the next, you will have to arrange for
10593 the postinst script to do something sensible - usually this
10594 will mean editing the installed configuration file to remove
10595 the problem or change the syntax. You will have to do this
10596 very carefully, since the user may have changed the file,
10597 perhaps to fix the very problem that your script is trying
10598 to deal with - you will have to detect these situations and
10599 deal with them correctly.
10603 If you do go down this route it's probably a good idea to
10604 make the program that generates the configuration file(s) a
10605 separate program in <file>/usr/sbin</file>, by convention called
10606 <file><var>package</var>config</file> and then run that if
10607 appropriate from the post-installation script. The
10608 <tt><var>package</var>config</tt> program should not
10609 unquestioningly overwrite an existing configuration - if its
10610 mode of operation is geared towards setting up a package for
10611 the first time (rather than any arbitrary reconfiguration
10612 later) you should have it check whether the configuration
10613 already exists, and require a <tt>--force</tt> flag to
10614 overwrite it.</p></sect>
10617 <appendix id="pkg-alternatives"><heading>Alternative versions of
10618 an interface - <prgn>update-alternatives</prgn> (from old
10623 When several packages all provide different versions of the
10624 same program or file it is useful to have the system select a
10625 default, but to allow the system administrator to change it
10626 and have their decisions respected.
10630 For example, there are several versions of the <prgn>vi</prgn>
10631 editor, and there is no reason to prevent all of them from
10632 being installed at once, each under their own name
10633 (<prgn>nvi</prgn>, <prgn>vim</prgn> or whatever).
10634 Nevertheless it is desirable to have the name <tt>vi</tt>
10635 refer to something, at least by default.
10639 If all the packages involved cooperate, this can be done with
10640 <prgn>update-alternatives</prgn>.
10644 Each package provides its own version under its own name, and
10645 calls <prgn>update-alternatives</prgn> in its postinst to
10646 register its version (and again in its prerm to deregister
10651 See the manpage <manref name="update-alternatives"
10652 section="8"> for details.
10656 If <prgn>update-alternatives</prgn> does not seem appropriate
10657 you may wish to consider using diversions instead.</p>
10660 <appendix id="pkg-diversions"><heading>Diversions - overriding a
10661 package's version of a file (from old Packaging Manual)
10665 It is possible to have <prgn>dpkg</prgn> not overwrite a file
10666 when it reinstalls the package it belongs to, and to have it
10667 put the file from the package somewhere else instead.
10671 This can be used locally to override a package's version of a
10672 file, or by one package to override another's version (or
10673 provide a wrapper for it).
10677 Before deciding to use a diversion, read <ref
10678 id="pkg-alternatives"> to see if you really want a diversion
10679 rather than several alternative versions of a program.
10683 There is a diversion list, which is read by <prgn>dpkg</prgn>,
10684 and updated by a special program <prgn>dpkg-divert</prgn>.
10685 Please see <manref name="dpkg-divert" section="8"> for full
10686 details of its operation.
10690 When a package wishes to divert a file from another, it should
10691 call <prgn>dpkg-divert</prgn> in its preinst to add the
10692 diversion and rename the existing file. For example,
10693 supposing that a <prgn>smailwrapper</prgn> package wishes to
10694 install a wrapper around <file>/usr/sbin/smail</file>:
10696 if [ install = "$1" ]; then
10697 dpkg-divert --package smailwrapper --add --rename \
10698 --divert /usr/sbin/smail.real /usr/sbin/smail
10700 </example> Testing <tt>$1</tt> is necessary so that the script
10701 doesn't try to add the diversion again when
10702 <prgn>smailwrapper</prgn> is upgraded. The <tt>--package
10703 smailwrapper</tt> ensures that <prgn>smailwrapper</prgn>'s
10704 copy of <file>/usr/sbin/smail</file> can bypass the diversion and
10705 get installed as the true version.
10709 The postrm has to do the reverse:
10711 if [ remove = "$1" ]; then
10712 dpkg-divert --package smailwrapper --remove --rename \
10713 --divert /usr/sbin/smail.real /usr/sbin/smail
10719 Do not attempt to divert a file which is vitally important for
10720 the system's operation - when using <prgn>dpkg-divert</prgn>
10721 there is a time, after it has been diverted but before
10722 <prgn>dpkg</prgn> has installed the new version, when the file
10723 does not exist.</p>
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